Sample records for reaction parameters important

  1. Kinetics of Reaction Important in Oxygen Steelmaking

    Coley, Kenneth S.; Chen, Elaine; Pomeroy, Michael

    Recent work on modeling of BOF steelmaking is reviewed, highlighting the critical aspects of each approach. It is concluded that the most successful models should be based on a deep understanding of the mechanisms and kinetics of the critical reactions. The importance of the decarburization mechanism is discussed with particular reference to its role in droplet swelling or bloating which has a profound influence on the droplet residence time in the slag. Conditions which cause bloating are discussed and the rate determining step is proposed to be primarily nucleation of CO bubbles inside the metal droplet with some influence from growth by reaction at the bubble/metal interface. The discrepancy in the super-saturation ratio required for classical nucleation is discussed and an approach using a surface tension modifying parameter is illustrated. Finally, the role of CO nucleation in controlling the driving force for dephosphorization is discussed.

  2. Approximating parameters in nonlinear reaction diffusion equations

    Robert R. Ferdinand


    Full Text Available We present a model describing population dynamics in an environment. The model is a nonlinear, nonlocal, reaction diffusion equation with Neumann boundary conditions. An inverse method, involving minimization of a least-squares cost functional, is developed to identify unknown model parameters. Finally, numerical results are presented which display estimates of these parameters using computationally generated data.

  3. Important Parameters and Applications for Nickel Electroforming

    Tang, Peter Torben; Benzon, Michael Eis; Rasmussen, J.P.;


    Electroforming is versatile process that is being used more and more, although the basic idea is almost a hundred years old. This paper will concentrate on the important mechanical properties and electrolyte parameters of nickel electroforming. Electrolyte parameters such as current density, p......H-value, temperature and the use of pulse plating and additives will be examined with respect to mechanical properties such as internal stress, material distribution and hardness. Pulse plating in a chloride and Watts nickel bath and DC plating in sulphamate bath will be discussed, as well as different methods...

  4. The Importance of Vocal Parameters Correlation

    Valentin Ghisa


    Full Text Available To analyze communication we need to study the main parameters that describe the vocal sounds from the point of view of information content transfer efficiency. In this paper we analyze the physical quality of the “on air" information transfer, according to the audio streaming parameters and from the particular phonetic nature of the human factor. Applying this statistical analysis we aim to identify and record the correlation level of the acoustical parameters with the vocal ones and the impact which the presence of this cross-correlation can have on communication structures’ improvement.

  5. Estimation of parameter sensitivities for stochastic reaction networks

    Gupta, Ankit


    Quantification of the effects of parameter uncertainty is an important and challenging problem in Systems Biology. We consider this problem in the context of stochastic models of biochemical reaction networks where the dynamics is described as a continuous-time Markov chain whose states represent the molecular counts of various species. For such models, effects of parameter uncertainty are often quantified by estimating the infinitesimal sensitivities of some observables with respect to model parameters. The aim of this talk is to present a holistic approach towards this problem of estimating parameter sensitivities for stochastic reaction networks. Our approach is based on a generic formula which allows us to construct efficient estimators for parameter sensitivity using simulations of the underlying model. We will discuss how novel simulation techniques, such as tau-leaping approximations, multi-level methods etc. can be easily integrated with our approach and how one can deal with stiff reaction networks where reactions span multiple time-scales. We will demonstrate the efficiency and applicability of our approach using many examples from the biological literature.

  6. A robust methodology for kinetic model parameter estimation for biocatalytic reactions

    Al-Haque, Naweed; Andrade Santacoloma, Paloma de Gracia; Lima Afonso Neto, Watson;


    Effective estimation of parameters in biocatalytic reaction kinetic expressions are very important when building process models to enable evaluation of process technology options and alternative biocatalysts. The kinetic models used to describe enzyme-catalyzed reactions generally include several...

  7. Geant4 supplied parameters for gamma reaction history at NIF

    Rubery, Michael; Horsfield, Colin; Herrmann, Hans; Kim, Yongho; Mack, Joe; Young, Carl; Evans, Scott; Sedillo, Tom; Miller, Kirk; Stoeffl, Wolfgang; Grafil, Elliot


    The GRH diagnostics at NIF and Omega report ICF burn parameters through detection of multi-MeV γ emissions. Of particular interest is ` γ bang-time' (GBT), defined as the temporal separation between light impacting the capsule and peak in the nuclear reaction history; GBT can constrain shock and compression parameters, and indicate fuel/ablator mix. Early NIF commissioning experiments have identified contributions to GRH signals from n,n' γ reactions with remaining capsule ablator, hohlraum and thermo-mechanical package, outside the fuel hotspot region. Such contributions are mitigated by increasing the Cherenkov threshold above the energy of these emissions. The pressure adjustment modifies parameters important to GBT, such as cell time-of-flight and detector FWHM; corrections simulated using Geant4 are presented using models experimentally validated at Duke University. Beyond GBT, studies suggest GRH may be capable of recording ablator ρR, unfolding the DT γ spectrum, and inferring the DTγ /DTn branching ratio. All calculations rely on the energy-resolved intensity response as a function of gas pressure. Geant4 response simulations, together with calculations by LANL using the experimentally validated ACCEPT code, are also presented.

  8. Heterogeneous reactions important in atmospheric ozone depletion: a theoretical perspective.

    Bianco, Roberto; Hynes, James T


    Theoretical studies of the mechanisms of several heterogeneous reactions involving ClONO(2), H(2)O, HCl, HBr, and H(2)SO(4) important in atmospheric ozone depletion are described, focused primarily on reactions on aqueous aerosol surfaces. Among the insights obtained is the active chemical participation of the surface water molecules in several of these reactions. The general methodology adopted allows reduction of these complex chemical problems to meaningful model systems amenable to quantum chemical calculations.

  9. Structural parameter identifiability analysis for dynamic reaction networks

    Davidescu, Florin Paul; Jørgensen, Sten Bay


    . The proposed analysis is performed in two phases. The first phase determines the structurally identifiable reaction rates based on reaction network stoichiometry. The second phase assesses the structural parameter identifiability of the specific kinetic rate expressions using a generating series expansion...... method based on Lie derivatives. The proposed systematic two phase methodology is illustrated on a mass action based model for an enzymatically catalyzed reaction pathway network where only a limited set of variables is measured. The methodology clearly pinpoints the structurally identifiable parameters...

  10. Cellular metabolic network analysis: discovering important reactions in Treponema pallidum.

    Chen, Xueying; Zhao, Min; Qu, Hong


    T. pallidum, the syphilis-causing pathogen, performs very differently in metabolism compared with other bacterial pathogens. The desire for safe and effective vaccine of syphilis requests identification of important steps in T. pallidum's metabolism. Here, we apply Flux Balance Analysis to represent the reactions quantitatively. Thus, it is possible to cluster all reactions in T. pallidum. By calculating minimal cut sets and analyzing topological structure for the metabolic network of T. pallidum, critical reactions are identified. As a comparison, we also apply the analytical approaches to the metabolic network of H. pylori to find coregulated drug targets and unique drug targets for different microorganisms. Based on the clustering results, all reactions are further classified into various roles. Therefore, the general picture of their metabolic network is obtained and two types of reactions, both of which are involved in nucleic acid metabolism, are found to be essential for T. pallidum. It is also discovered that both hubs of reactions and the isolated reactions in purine and pyrimidine metabolisms play important roles in T. pallidum. These reactions could be potential drug targets for treating syphilis.

  11. Importance and sensitivity of parameters affecting the Zion Seismic Risk

    George, L.L.; O' Connell, W.J.


    This report presents the results of a study on the importance and sensitivity of structures, systems, equipment, components and design parameters used in the Zion Seismic Risk Calculations. This study is part of the Seismic Safety Margins Research Program (SSMRP) supported by the NRC Office of Nuclear Regulatory Research. The objective of this study is to provide the NRC with results on the importance and sensitivity of parameters used to evaluate seismic risk. These results can assist the NRC in making decisions dealing with the allocation of research resources on seismic issues. This study uses marginal analysis in addition to importance and sensitivity analysis to identify subject areas (input parameter areas) for improvements that reduce risk, estimate how much the improvement dfforts reduce risk, and rank the subject areas for improvements. Importance analysis identifies the systems, components, and parameters that are important to risk. Sensitivity analysis estimates the change in risk per unit improvement. Marginal analysis indicates the reduction in risk or uncertainty for improvement effort made in each subject area. The results described in this study were generated using the SEISIM (Systematic Evaluation of Important Safety Improvement Measures) and CHAIN computer codes. Part 1 of the SEISIM computer code generated the failure probabilities and risk values. Part 2 of SEISIM, along with the CHAIN computer code, generated the importance and sensitivity measures.

  12. Important Parameter Groups in Thermal Protection of Polymers

    John Staggs


    Full Text Available The problem of thermal protection is explored for two idiosyncratic reactive systems, namely a sacrificial heat-sink material and an intumescent system where a dynamically evolving insulation layer is produced from an initially thin coating. Relatively simple mathematical models of both systems are proposed that encompass the important physical characteristics of each situation and these models are analysed using a mixture of numerical and analytical techniques. Important dimensionless parameter groups are identified and domains of parameter space where thermal performance is particularly good- or particularly bad- are identified.

  13. Extraction of important electrical parameters of CuO

    Serin, T. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Ankara (Turkey); Yildiz, A., E-mail: [Department of Physics, Faculty of Science and Arts, Ahi Evran University, 40040 Kirsehir (Turkey); Horzum Sahin, S.; Serin, N. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Ankara (Turkey)


    Conductivity, X-ray diffraction (XRD), optical absorption and atomic force microscopy (AFM) measurements of CuO thin film were presented. Three distinct electrical conduction contributions with discrete characteristic activation energies were observed. The applicability of various theoretical models was considered to explain results on electrical transport. We extracted important electrical parameters of CuO, which might be useful for its gas sensor applications. -- Research Highlights: {yields} The important electrical parameters of CuO were extracted. Three distinct activation contributions were observed. {yields} Above 200 K, conductivity was controlled by potential barrier. {yields} Below 200 K, conductivity was described in terms of hopping conduction.

  14. Kinetic modeling of mechanisms of industrially important organic reactions in gas and liquid phase

    Vahteristo, K.


    This dissertation is based on 5 articles which deal with reaction mechanisms of the following selected industrially important organic reactions: 1. dehydrocyclization of n-butylbenzene to produce naphthalene, 2. dehydrocyclization of 1-(p-tolyl)-2-methylbutane (MB) to produce 2,6-dimethylnaphthalene, 3. esterification of neopentyl glycol (NPG) with different carboxylic acids to produce monoesters, 4. skeletal isomerization of 1-pentene to produce 2-methyl-1-butene and 2-methyl-2-butene. The results of initial- and integral-rate experiments of n-butylbenzene dehydrocyclization over selfmade chromia/alumina catalyst were applied when investigating reaction 2. Reaction 2 was performed using commercial chromia/alumina of different acidity, platina on silica and vanadium/calcium/alumina as catalysts. On all catalysts used for the dehydrocyclization, major reactions were fragmentation of MB and 1-(p-tolyl)-2-methylbutenes (MBes), dehydrogenation of MB, double bond transfer, hydrogenation and 1,6-cyclization of MBes. Minor reactions were 1,5-cyclization of MBes and methyl group fragmentation of 1,6- cyclization products. Esterification reactions of NPG were performed using three different carboxylic acids: propionic, isobutyric and 2-ethylhexanoic acid. Commercial heterogeneous gellular (Dowex 50WX2), macroreticular (Amberlyst 15) type resins and homogeneous para-toluene sulfonic acid were used as catalysts. At first NPG reacted with carboxylic acids to form corresponding monoester and water. Then monoester esterified with carboxylic acid to form corresponding diester. In disproportionation reaction two monoester molecules formed NPG and corresponding diester. All these three reactions can attain equilibrium. Concerning esterification, water was removed from the reactor in order to prevent backward reaction. Skeletal isomerization experiments of 1-pentene were performed over HZSM-22 catalyst. Isomerization reactions of three different kind were detected: double bond, cis

  15. Reaction parameters for controlled sonosynthesis of gold nanoparticles

    Gonzalez M, A. L. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Colon esq. Paseo Tollocan s/n, 50120 Toluca, Estado de Mexico (Mexico); Cabrera L, L. I. [UNAM-UAEM, Centro Conjunto de Investigacion en Quimica Sustentable, Km 14.5 Carretera Toluca-Atlacomulco, 50200 San Cayetano-Toluca, Estado de Mexico (Mexico)


    The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 k Hz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method. Characterization techniques used: Fourier transform infrared spectra (Ftir), X-ray diffraction and Atomic Force Microscope was used in order to determine particle size of the synthetic product of reaction M10c by tapping mode. (Author)

  16. Evaluation of true kinetic parameters for reversible immobilized enzyme reactions

    Ishikawa, H.; Tanaka, T.; Kurose, K.; Hikita, H.


    For a reversible one-substrate reaction system that follows the Haldane reaction mechanism, a new and effective method has been proposed to extract true or intrinsic kinetic parameters of immobilized enzymes from diffusion limited rate data. The method utilizes the effectiveness factors correlated in terms of the general modulus defined by Aris and Bischoff, and a new modulus defined in the present study. It requires a trial-and-error calculation, but only a few data points. Furthermore, it provides a saving of materials such as substrates and enzymes, and takes less time for experiments compared to the initial rate methods. The usefulness of the method is demonstrated by determining the kinetic parameters for membrane bound fumarase which catalyzes the reaction of the conversion of fumarate to L-malate, for which the equilibrium constant is circa 4. (Refs. 20).

  17. Open star cluster: formation, parameters, membership and importance

    Joshi, Gireesh C


    We have been represented the collective information of estimation procedures of parameters of the open clusters and put them together for showing the importance of clusters to understand their role in stellar evolution phenomenon. Moreover, we have been discussed about analytic techniques to determine the structural and dynamical properties of galactic clusters. The members of clusters provide unique opportunity to determine their basic parameters such as: age, metallicity, distance, reddening etc. The membership probabilities of stars of clusters is assigned through the various approaches and each approach provides different number of probable members of the cluster. Here, we have been briefly discussed about various approaches to determine the stellar membership within clusters.

  18. Importance of Non-Perturbative QCD Parameters for Bottom Mesons

    Upadhyay, A


    The importance of non-perturbative Quantum Chromodynamics [QCD] parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two non perturbative QCD parameters used in heavy quark effective theory formula and using the best fitted parameter, masses of the excited bottom meson states in JP=(1/2)+ doublet in strange as well as non-strange sector are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass and hyperfine splitting has also been analyzed for both strange and non-strange heavy mesons with respect to spin and flavor symmetries.

  19. Importance of Nonperturbative QCD Parameters for Bottom Mesons

    A. Upadhyay


    Full Text Available The importance of nonperturbative quantum chromodynamics (QCD parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two nonperturbative QCD parameters used in heavy quark effective theory formula, and using the best fitted parameter, masses of the excited bottom meson states in jp=1/2+ doublet in strange and nonstrange sectors are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass splitting and hyperfine splitting have also been analyzed for both strange and nonstrange heavy mesons with respect to spin and flavor symmetries.

  20. An important difference between "exposed" and "photodistributed" underscores the importance of identifying common reactions.

    Jacob, Sharon E; Breithaupt, Andrew D


    This article presents the case of a patient with rheumatoid arthritis who was referred to dermatology for what was suspected to be a photosensitivity reaction to hydroxychloroquine, a common culprit in photodrug reactions. Despite the patient's insistence to the contrary, the cause of her eruption was an airborne allergic contact dermatitis to chemicals she was exposed to during her longtime hobby of soap-making. This case serves as an important illustration of the anatomical differences between eruptions occurring in exposed and photodistributed areas. This article also discusses the causes of dermatitis that may mimic photodrug reactions.

  1. Important population viability analysis parameters for giant pandas (Aliuropoda melanoleuca)

    Minghao GONG; Yanling SONG; Zhisong YANG; Chen LIN


    Population viability analysis (PVA) is a tool to evaluate the risk of extinction for endangered species and aid conservation decision-making.The quality of PVA output is dependent on parameters related to population dynamics and life-history; however,it has been difficult to collect this information for the giant panda (Aliuropoda melanoleuca),a rare and endangered mammal native to China,confined to some 30 fragmented habitat patches.Since giant pandas are long-lived,mature late,have lower reproductive rates,and show little sexual dimorphism,obtaining data to perform adequate PVA has been difficult.Here,we develop a parameter sensitivity index by modeling the dynamics of six giant panda populations in the Minshan Mountains,in order to determine the parameters most influential to giant panda populations.Our data shows that the giant panda populations are most sensitive to changes in four female parameters:initial breeding age,reproductive rate,mortality rate between age 0 and 1,and mortality rate of adults.The parameter sensitivity index strongly correlated with initial population size,as smaller populations were more sensitive to changes in these four variables.This model suggests that demographic parameters of females have more influence on the results of PVA,indicating that females may play a more important role in giant panda population dynamics than males.Consequently,reintroduction of female individuals to a small giant panda population should be a high priority for conservation efforts.Our findings form a technical basis for the coming program of giant panda reintroduction,and inform which parameters are crucial to successfully and feasibly monitoring wild giant panda populations.

  2. Global parameter identification of stochastic reaction networks from single trajectories.

    Müller, Christian L; Ramaswamy, Rajesh; Sbalzarini, Ivo F


    We consider the problem of inferring the unknown parameters of a stochastic biochemical network model from a single measured time-course of the concentration of some of the involved species. Such measurements are available, e.g., from live-cell fluorescence microscopy in image-based systems biology. In addition, fluctuation time-courses from, e.g., fluorescence correlation spectroscopy (FCS) provide additional information about the system dynamics that can be used to more robustly infer parameters than when considering only mean concentrations. Estimating model parameters from a single experimental trajectory enables single-cell measurements and quantification of cell-cell variability. We propose a novel combination of an adaptive Monte Carlo sampler, called Gaussian Adaptation (GaA), and efficient exact stochastic simulation algorithms (SSA) that allows parameter identification from single stochastic trajectories. We benchmark the proposed method on a linear and a non-linear reaction network at steady state and during transient phases. In addition, we demonstrate that the present method also provides an ellipsoidal volume estimate of the viable part of parameter space and is able to estimate the physical volume of the compartment in which the observed reactions take place.

  3. Thermodynamic criteria for estimating the kinetic parameters of catalytic reactions

    Mitrichev, I. I.; Zhensa, A. V.; Kol'tsova, E. M.


    Kinetic parameters are estimated using two criteria in addition to the traditional criterion that considers the consistency between experimental and modeled conversion data: thermodynamic consistency and the consistency with entropy production (i.e., the absolute rate of the change in entropy due to exchange with the environment is consistent with the rate of entropy production in the steady state). A special procedure is developed and executed on a computer to achieve the thermodynamic consistency of a set of kinetic parameters with respect to both the standard entropy of a reaction and the standard enthalpy of a reaction. A problem of multi-criterion optimization, reduced to a single-criterion problem by summing weighted values of the three criteria listed above, is solved. Using the reaction of NO reduction with CO on a platinum catalyst as an example, it is shown that the set of parameters proposed by D.B. Mantri and P. Aghalayam gives much worse agreement with experimental values than the set obtained on the basis of three criteria: the sum of the squares of deviations for conversion, the thermodynamic consistency, and the consistency with entropy production.

  4. Efficient parameter sensitivity computation for spatially extended reaction networks

    Lester, C.; Yates, C. A.; Baker, R. E.


    Reaction-diffusion models are widely used to study spatially extended chemical reaction systems. In order to understand how the dynamics of a reaction-diffusion model are affected by changes in its input parameters, efficient methods for computing parametric sensitivities are required. In this work, we focus on the stochastic models of spatially extended chemical reaction systems that involve partitioning the computational domain into voxels. Parametric sensitivities are often calculated using Monte Carlo techniques that are typically computationally expensive; however, variance reduction techniques can decrease the number of Monte Carlo simulations required. By exploiting the characteristic dynamics of spatially extended reaction networks, we are able to adapt existing finite difference schemes to robustly estimate parametric sensitivities in a spatially extended network. We show that algorithmic performance depends on the dynamics of the given network and the choice of summary statistics. We then describe a hybrid technique that dynamically chooses the most appropriate simulation method for the network of interest. Our method is tested for functionality and accuracy in a range of different scenarios.

  5. Determination of kinetic parameters for complex transesterification reaction by standard optimisation methods

    Almagrbi Abdualnaser Muftah


    Full Text Available This article presents a methodology for kinetic parameter estimation which is based on standard optimization methods. The parameter estimation procedure is applied to the example of modelling of non-catalytic transesterification reaction, based on laboratory experiments performed under elevated pressure. The kinetic model employed in this study consists of three consecutive and parallel reversible reactions of the second order, with six kinetic constants. The influence of the mass transfer effects was considered as well. The best results were obtained by Genetic Algorithm method. The application of this method resulted in kinetic parameters with improved accuracy in predicting concentrations of important reaction intermediates, i.e. diglycerides and monoglycerides. Activation energies of kinetic parameters obtained by the Genetic Algorithm method are in very good agreement with theoretical values determined by molecular orbital calculations. [Projekat Ministarstva nauke Republike Srbije, br. III-45019

  6. The reaction of serpins with proteinases involves important enthalpy changes.

    Boudier, C; Bieth, J G


    When active serpins are proteolytically inactivated in a substrate-like reaction, they undergo an important structural transition with a resultant increase in their conformational stability. We have used microcalorimetry to show that this conformational alteration is accompanied by an important enthalpy change. For instance, the cleavage of alpha(1)-proteinase inhibitor by Pseudomonas aeruginosa elastase, Staphylococcus aureus V8 proteinase, or papain and that of antithrombin by leukocyte elastase are characterized by large enthalpy changes (DeltaH = -53 to -63 kcal mol(-1)). The former reaction also has a large and negative heat capacity (DeltaC(p)() = -566 cal K(-1) mol(-1)). In contrast, serpins release significantly less heat when they act as proteinase inhibitors. For example, the inhibition of pancreatic elastase, leukocyte elastase, and pancreatic chymotrypsin by alpha(1)-proteinase inhibitor and that of pancreatic trypsin and coagulation factor Xa by antithrombin are accompanied by a DeltaH of -20 to -31 kcal mol(-1). We observe no heat release upon proteolytic cleavage of inactive serpins or following inhibition of serine proteinases by canonical inhibitors or upon acylation of chymotrypsin by N-trans-cinnamoylimidazole. We suggest that part of the large enthalpy change that occurs during the structural transition of serpins is used to stabilize the proteinase in its inactive state.

  7. Parameters of importance to determine during geoscientific site investigation

    Andersson, Johan [QuantiSci AB (Sweden); Almen, K.E. [KEA GEO-Konsult AB (Sweden); Ericsson, Lars O.; Karlsson, Fred; Stroem, A. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Fredriksson, Anders [ADG Grundteknik AB (Sweden); Stanfors, R. [Roy Stanfors Consulting AB (Sweden)


    This document identifies and describes geo-scientific parameters that are of importance in order to carry out performance and safety assessments of a deep repository for spent nuclear fuel, based on the information that can be obtained from a site investigation. The document also discusses data needs for planning and design of the rock works and for description of other environmental aspects. Evaluation of the different parameters is discussed in the document as well. The document was produced by a working group consisting of the authors and various SKB staff and consultants, and comprises a step in the planning of a geo-scientific investigation programme at the sites where site investigations will be conducted. The goals of the work presented in this report can be derived directly from SKBs ongoing RD and D Programme. The programme stipulates that a geo-scientific site investigation programme must be available before a site investigation begins. This programme is supposed to specify the goals, measurement methods and evaluation methodology, as well as the acceptance criteria against which the site is evaluated. It is pointed out that site evaluation is a collective term for an interactive process consisting of different parts 65 refs, 15 figs, 12 tabs


    Žigmund Tóth


    Full Text Available Quality of final product is to great extent influenced by intermediate products that are formed during beer production. In addition quality of pH is one of the most important properties that forms suitable medium for activity of enzymes complexes that have crucial influence on character of produced wort. Moreover enzymes influence the yield of production process and quality of final product as well. Quality of boiling water and especially its hardness have crucial task in terms of keeping optimal qualitative parameters. Water hardness is given by amount of salts, mainly calcium and magnesium salts. It is expressed as absolute hardness which is given by sum of temporary (carbonate and permanent (noncarbonate hardness. In our work we solved the effect of total water hardness on final pH of various intermediate products. We used different water samples and we prepared variants of total hardness by stirring of unpurified water with distilled water thus we achieved various values of hardness. For comparison we prepared several brews with regard to combinations of unpurified water and distilled water. Higher pH of boiling water was caused due to higher water alkalinity that negatively affected enzyme complex present in used malt. Presence of hydrogenphosphates in used malt had high buffering ability and pH lowering ability. Such unfavorable result could be adjust by use of various additions of acidulates that would have in great extent influence on beer final price therefore boiling water adjustment seems to be the most acceptable approach.

  9. Assessing the importance of terrain parameters on glide avalanche release

    Peitzsch, Erich H.; Hendrikx, Jordy; Fagre, Daniel B.


    Glide snow avalanches are dangerous and difficult to predict. Despite recent research there is still a lack of understanding regarding the controls of glide avalanche release. Glide avalanches often occur in similar terrain or the same locations annually and observations suggest that topography may be critical. Thus, to gain an understanding of the terrain component of these types of avalanches we examined terrain parameters associated with glide avalanche release as well as areas of consistent glide crack formation but no subsequent avalanches. Glide avalanche occurrences visible from the Going-to-the-Sun Road corridor in Glacier National Park, Montana from 2003-2013 were investigated using an avalanche database derived of daily observations each year from April 1 to June 15. This yielded 192 glide avalanches in 53 distinct avalanche paths. Each avalanche occurrence was digitized in a GIS using satellite, oblique, and aerial imagery as reference. Topographical parameters such as area, slope, aspect, elevation and elevation were then derived for the entire dataset utilizing GIS tools and a 10m DEM. Land surface substrate and surface geology were derived from National Park Service Inventory and Monitoring maps and U.S. Geological Survey surface geology maps, respectively. Surface roughness and glide factor were calculated using a four level classification index. . Then, each avalanche occurrence was aggregated to general avalanche release zones and the frequencies were compared. For this study, glide avalanches released in elevations ranging from 1300 to 2700 m with a mean aspect of 98 degrees (east) and a mean slope angle of 38 degrees. The mean profile curvature for all glide avalanches was 0.15 and a plan curvature of -0.01, suggesting a fairly linear surface (i.e. neither convex nor concave). The glide avalanches occurred in mostly bedrock made up of dolomite and limestone slabs and talus deposits with very few occurring in alpine meadows. However, not all glide

  10. Determining important parameters related to cyanobacterial alkaloid toxin exposure

    Love, A H


    Science-based decision making required robust and high-fidelity mechanistic data about the system dynamics and impacts of system changes. Alkaloid cyanotoxins have the characteristics to warrant consideration for their potential threat. Since insufficient information is available to construct a systems model for the alkaloid cyanotoxins, saxitoxins, anatoxins, and anatoxin-a(S), an accurate assessments of these toxins as a potential threat for use for intentional contamination is not possible. Alkaloid cyanotoxin research that contributed to such a model has numerous areas of overlap for natural and intentional health effects issues that generates dual improvements to the state of the science. The use of sensitivity analyses of systems models can identify parameters that, when determined, result in the greatest impact to the overall system and may help to direct the most efficient use of research funding. This type of modeling-assisted experimentation may allow rapid progress for overall system understanding compared to observational or disciplinary research agendas. Assessment and management of risk from intentional contamination can be performed with greater confidence when mechanisms are known and the relationships between different components are validated. This level of understanding allows high-fidelity assessments that do not hamper legitimate possession of these toxins for research purposes, while preventing intentional contamination that would affect public health. It also allows for appropriate response to an intentional contamination event, even if the specific contamination had not been previous considered. Development of science-based decision making tools will only improve our ability to address the new requirements addressing potential threats to our nation.

  11. Osmoregulation – an important parameter of bacterial growth

    Marta Sochocka


    Full Text Available Environmental conditions such as temperature, pH, radiation and osmotic pressure are important factors limiting the growth and multiplication of bacteria. Regular structure and metabolism of bacterial cells are maintained through a stable arrangement of the water-electrolyte system, regulated by osmosis. The rapid changes caused by osmotic shock (dehydration, rehydration might lead to modifications of the phospholipid structure of the cell membrane and even cell death. Advances disturbing the osmosis, which are a natural part of living cells, may appear for example in colloid systems. The biological identification of the osmotic pressure is connected with an increase or decrease in the environmental osmotic strength of microorganisms’ habitat. Cells exposed to osmotic stress, such as an increase in osmotic pressure, initiate mechanisms of active coping with the adverse consequences of its effects. Osmoregulatory processes are designed to maintain cell turgor, hence ensuring proper conditions for bacterial growth. Osmoregulation, which consists of maintaining fluid and electrolyte balance of cells, raising concerns accumulation of specific compatible solutes (osmolytes. Osmolytes are small, soluble organic molecules with a positive influence on membrane stabilization and proteins, without disrupting cellular functions. Storage of compatible solutes takes place by synthesis or by downregulation from the medium by means of special transport systems, activated by mechanical stimuli. Knowledge of the impact of osmotic pressure on microbial cells and the regulation of its activity led to the appropriate use of bacteria in various branches of the biotechnology industry.

  12. Ozone - plant surface reactions an important ozone loss term?

    Hansel, Armin; Jud, Werner; Fischer, Lukas; Canaval, Eva; Wohlfahrt, Georg; Tissier, Alain


    Elevated tropospheric ozone concentrations are considered a toxic threat to plants responsible for global crop losses with associated economic costs of several billions dollar per year. Plant injuries have been related to the uptake of ozone through stomatal pores and oxidative effects damaging the internal leaf tissue. But a striking question remains: How much ozone enters the plant through open stomata and how much ozone is lost by chemical reactions at the plant surface? Until now surface losses are estimated from measured total ozone deposition fluxes and calculated stomatal conductance values. While stomatal conductance of CO2 and H2O is well understood and extensively used in describing plant atmosphere gas exchange, stomatal conductance of ozone is not well known. Here we use different Nicotiana tabacum varieties and find that surface reactions of ozone with diterpenoids synthesized by glandular trichomes reduce ozone flux through open stomata. Our measurements reveal that fast ozone loss at the plant surface is accompanied with prompt release of oxygenated volatile compounds. In the ozone fumigation experiments of different Nicotiana tabacum varieties the release of specific volatile oxy-VOCs allowed to identify the semi volatile precursor compounds at the plant surface. Ozone fumigation experiments with Norway spruce (Picea abies) and Scots Pine (Pinus sylvestris), two common species in the Northern Hemisphere, show also a significant ozone loss at the plant surface for Picea abies. Fluid dynamic calculations of ozone transport in the diffusive leaf boundary layer reveal a vertical but no horizontal ozone gradient thus reducing ozone fluxes through the pores in case of efficient ozone scavenging plant surfaces. We explain this efficient ozone protection mechanism by the porous surface architecture of plants in combination with unsaturated semi-volatile compounds deposited at the plant surface. These results show that unsaturated semi-volatile compounds at

  13. Importance of ~5He Emission in Neutron Induced Reactions


    The statistical model codes as the evaluation tool widely used in the world have long been performedto set up neutron data library below 20 MeV However, an important particle emission of ~5He has neverbeen included in the widely used codes. Based on the calculated threshold energies of ~3He and ~5He emissions for various nuclei, one can find

  14. Bimetallic Catalysts Containing Gold and Palladium for Environmentally Important Reactions

    Ahmad Alshammari


    Full Text Available Supported bimetallic nanoparticles (SBN are extensively used as efficient redox catalysts. This kind of catalysis particularly using SBN has attracted immense research interest compared to their parent metals due to their unique physico-chemical properties. The primary objective of this contribution is to provide comprehensive overview about SBN and their application as promising catalysts. The present review contains four sections in total. Section 1 starts with a general introduction, recent progress, and brief summary of the application of SBN as promising catalysts for different applications. Section 2 reviews the preparation and characterization methods of SBN for a wide range of catalytic reactions. Section 3 concentrates on our own results related to the application of SBN in heterogeneous catalysis. In this section, the oxidation of cyclohexane to adipic acid (an eco-friendly and novel approach will be discussed. In addition, the application of bimetallic Pd catalysts for vapor phase toluene acetoxylation in a fixed bed reactor will also be highlighted. Acetoxylation of toluene to benzyl acetate is another green route to synthesize benzyl acetate in one step. Finally, Section 4 describes the summary of the main points and also presents an outlook on the application of SBN as promising catalysts for the production of valuable products.

  15. New Method to Acquire Chemomechanical Parameters of Diverse Chemical Reactions


    a model for reversible and pseudoreversible isothermal photoactuation based on the Carnot -type formalism and used it to estimate the maximum single...reactions offers unique attributes, e.g., potentially fast actuation cycles , high chemical and mechanical stability, flexible device design and

  16. The reaction between iodine and silver under severe PWR accident conditions. An experimental parameter study

    Funke, F.; Greger, G.U.; Bleier, A.; Hellmann, S.; Morell, W. [Siemens AG, Power Generation Group, Erlangen (Germany)


    An extensive experimental parameter study was performed on the kinetics in the reaction system I{sub 2}/Ag and I{sup -}/Ag in a laboratory-scale apparatus.Starting with I{sub 2} or I{sup -} solutions and silver powder suspensions, the decrease of soluted I{sub 2} or I{sup -}, respectively, due to fixation on the silver particles, was monitored as function of time using the radioactive tracer I-131. The measured data were analyzed using a model of first order kinetics with respect to the iodine concentration. However, the analysis using first order kinetics had to be performed separately in an early, fast reaction phase and in a late, slow reaction phase. The reason for this unexpected behaviour was not identified. Thus, rate constant, two for each test, were deduced from 14 I{sub 2}/Ag main tests and from 36 I{sup -}/Ag tests. No dependencies of the rate constants were found on the parameters temperature, initial iodine concentration, presence of boric acid, type of silver educt, and pretreatment of the silver educt prior to the tests. However, the stirring of the reaction solution generally enhanced the kinetics highlighting the importance of mass transfer. The I{sup -}/Ag reaction proceeded only if there was no inertization of the reaction solution by sparging with nitrogen. The temperature-independent rate constant for the early, fast I{sub 2}/Ag reaction phase is 2E-5 m/s. However, a smaller rate constant of 6E-6 m/s is recommended for use in source term calculations with IMPAIR, which already contains a first order model. Analogously, the temperature-independent I{sup -}/Ag reaction rate constant is 8E-6 m/s in an early, fast reaction phase. For use in source term calculations, a smaller rate constant of 2E-6 m/s is recommended. The lower bound of the I{sup -}/Ag rate constant was 3E-8 m/s which could be used in very conservative source term calculations. (author) 20 figs., 6 tabs., 15 refs.

  17. Study on Optimization of Electromagnetic Relay's Reaction Torque Characteristics Based on Adjusted Parameters

    Zhai, Guofu; Wang, Qiya; Ren, Wanbin

    The cooperative characteristics of electromagnetic relay's attraction torque and reaction torque are the key property to ensure its reliability, and it is important to attain better cooperative characteristics by analyzing and optimizing relay's electromagnetic system and mechanical system. From the standpoint of changing reaction torque of mechanical system, in this paper, adjusted parameters (armature's maximum angular displacement αarm_max, initial return spring's force Finiti_return_spring, normally closed (NC) contacts' force FNC_contacts, contacts' gap δgap, and normally opened (NO) contacts' over travel δNO_contacts) were adopted as design variables, and objective function was provided for with the purpose of increasing breaking velocities of both NC contacts and NO contacts. Finally, genetic algorithm (GA) was used to attain optimization of the objective function. Accuracy of calculation for the relay's dynamic characteristics was verified by experiment.

  18. RIPL - Reference Input Parameter Library for Calculation of Nuclear Reactions and Nuclear Data Evaluations

    Capote, R.; Herman, M.; Obložinský, P.; Young, P. G.; Goriely, S.; Belgya, T.; Ignatyuk, A. V.; Koning, A. J.; Hilaire, S.; Plujko, V. A.; Avrigeanu, M.; Bersillon, O.; Chadwick, M. B.; Fukahori, T.; Ge, Zhigang; Han, Yinlu; Kailas, S.; Kopecky, J.; Maslov, V. M.; Reffo, G.; Sin, M.; Soukhovitskii, E. Sh.; Talou, P.


    We describe the physics and data included in the Reference Input Parameter Library, which is devoted to input parameters needed in calculations of nuclear reactions and nuclear data evaluations. Advanced modelling codes require substantial numerical input, therefore the International Atomic Energy Agency (IAEA) has worked extensively since 1993 on a library of validated nuclear-model input parameters, referred to as the Reference Input Parameter Library (RIPL). A final RIPL coordinated research project (RIPL-3) was brought to a successful conclusion in December 2008, after 15 years of challenging work carried out through three consecutive IAEA projects. The RIPL-3 library was released in January 2009, and is available on the Web through This work and the resulting database are extremely important to theoreticians involved in the development and use of nuclear reaction modelling (ALICE, EMPIRE, GNASH, UNF, TALYS) both for theoretical research and nuclear data evaluations. The numerical data and computer codes included in RIPL-3 are arranged in seven segments: MASSES contains ground-state properties of nuclei for about 9000 nuclei, including three theoretical predictions of masses and the evaluated experimental masses of Audi et al. (2003). DISCRETE LEVELS contains 117 datasets (one for each element) with all known level schemes, electromagnetic and γ-ray decay probabilities available from ENSDF in October 2007. NEUTRON RESONANCES contains average resonance parameters prepared on the basis of the evaluations performed by Ignatyuk and Mughabghab. OPTICAL MODEL contains 495 sets of phenomenological optical model parameters defined in a wide energy range. When there are insufficient experimental data, the evaluator has to resort to either global parameterizations or microscopic approaches. Radial density distributions to be used as input for microscopic calculations are stored in the MASSES segment. LEVEL DENSITIES contains

  19. Mass dependence of critical parameter and multiplicity of intermediatemass fragments in heavy ion reaction


    The mass dependence of critical parameters for the liquid-gas phase transition andmultiplicity of intermediate mass fragment in the heavyion reaction is qualitatively explored under the frameworkof lattice gas model. Some results are compared with experimental data.

  20. Influence of Reaction Parameters on Water Absorbency of Starch Grafted Superabsorbents

    LI Ming-da; ZHOU Yong-yuan


    Superabsorbents starch grafted sodium polyacrylate was synthesized by inverse suspension polymerization, using toluene as the continuous phase, potassium persulfate as the initiator. The effect of reaction parameters, such as starch pretreatment temperature, neutralization degree of monomer, reaction time and temperature,concentration of initiator, molar ratio of monomer and starch, on water absorbency of the starch grafted polymer was studied. The effects of the last two parameters were investigated by uniform design method,and the prediction equation was obtained.

  1. Vestibular stimulation after head injury: effect on reaction times and motor speech parameters

    Engberg, A


    motor speech parameters (reflecting dysarthria) was investigated. After eight weeks with regular stimulation, it was concluded that reaction time changes were individual and consistent for a given subject. Only occasionally were they shortened after stimulation. However, reaction time was lengthened...... in three cases, prohibiting further stimulation in one case. Motion sickness was prohibitive in a second case. However, after-stimulation increase of phonation time and/or vital capacity was found in one patient and four controls. Oral diadochokinetic rates were slowed in several cases. Collectively, when...... stimulation induced changes of reaction times or motor speech parameters, the changes were more pronounced in patients than in controls....

  2. Castor oil transesterification reaction: A kinetic study and optimization of parameters

    Ramezani, K. [Fuel Cell Research Laboratory, Green Research Center, Iran University of Science and Technology, Tehran (Iran); Rowshanzamir, S. [Fuel Cell Research Laboratory, Green Research Center, Iran University of Science and Technology, Tehran (Iran); School of Chemical Engineering, Iran University of Science and Technology, Tehran (Iran); Eikani, M.H. [Department of Chemical Industries, Iranian Research Organization for Science and Technology (IROST), Tehran (Iran)


    In this paper, parameters affecting castor oil transesterification reaction were investigated. Applying four basic catalysts including NaOCH{sub 3}, NaOH, KOCH{sub 3} and KOH the best one with maximum biodiesel yield was identified. Using Taguchi method consisting four parameters and three levels, the best experimental conditions were determined. Reaction temperature (25, 65 and 80 C), mixing intensity (250, 400 and 600 rpm), alcohol/oil ratio (4:1, 6:1 and 8:1) and catalyst concentration (0.25, 0.35 and 0.5%) were selected as experimental parameters. It was concluded that reaction temperature and mixing intensity can be optimized. Using the optimum results, we proposed a kinetic model which resulted in establishing an equation for the beginning rate of transesterification reaction. Furthermore, applying ASTM D 976 correlation, minimum cetane number of produced biodiesel was determined as 37.1. (author)

  3. The reaction between iodine and organic coatings under severe PWR accident conditions. An experimental parameter study

    Hellmann, S.; Funke, F.; Greger, G.U.; Bleier, A.; Morell, W. [Siemens AG, Power Generation Group, Erlangen (Germany)


    An extensive experimental parameter study was performed on the deposition and on the resuspension kinetics in the reaction system iodine/organically coated surfaces. Both reactions in the gas phase and in the liquid phase were investigated and kinetic rate constants suitable for modelling were derived. Previous experimental studies on the reaction of iodine with organic coated surfaces were mostly limited to temperatures below 100{sup o}C. Thus, this parameter study aims at filling a gap and providing kinetic data on heterogeneous reactions with organic surfaces in the accident-relevant temperature range of 100-160{sup o}C. Two types of laboratory experiments carried out at Siemens/KWU using coatings representative for German power plants (epoxy-tape paint), namely gas phase tests and liquid phase tests. (author) 6 figs., 6 tabs., 5 refs.

  4. Reaction Kinetic Parameters and Surface Thermodynamic Properties of Cu2O Nanocubes

    Xingxing Li


    Full Text Available Cuprous oxide (Cu2O nanocubes were synthesized by reducing Cu(OH2 in the presence of sodium citrate at room temperature. The samples were characterized in detail by field-emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction, and N2 absorption (BET specific surface area. The equations for acquiring reaction kinetic parameters and surface thermodynamic properties of Cu2O nanocubes were deduced by establishment of the relations between thermodynamic functions of Cu2O nanocubes and these of the bulk Cu2O. Combined with thermochemical cycle, transition state theory, basic theory of chemical thermodynamics, and in situ microcalorimetry, reaction kinetic parameters, specific surface enthalpy, specific surface Gibbs free energy, and specific surface entropy of Cu2O nanocubes were successfully determined. We also introduced a universal route for gaining reaction kinetic parameters and surface thermodynamic properties of nanomaterials.

  5. Ranking the importance of nuclear reactions for activation and transmutation events

    Arter, Wayne; Relton, Samuel D; Higham, Nicholas J


    Pathways-reduced analysis is one of the techniques used by the Fispact-II nuclear activation and transmutation software to study the sensitivity of the computed inventories to uncertainties in reaction cross-sections. Although deciding which pathways are most important is very helpful in for example determining which nuclear data would benefit from further refinement, pathways-reduced analysis need not necessarily define the most critical reaction, since one reaction may contribute to several different pathways. This work examines three different techniques for ranking reactions in their order of importance in determining the final inventory, viz. a pathways based metric (PBM), the direct method and one based on the Pearson correlation coefficient. Reasons why the PBM is to be preferred are presented.

  6. Influence of reaction parameters on the synthesis of surfactant-assisted tin oxide nanoparticles

    Farrukh, Muhammad Akhyar; ADNAN, Prisca TAN and Rohana


    Tin oxide nanoparticles were synthesized via hydrothermal method using a non-ionic surfactant, oleyl amine (OLM), in the presence of urea. The reactions were carried out at different calcination temperatures and varying concentrations of surfactant and urea. The effect of these reaction parameters on the particles' size, distribution, surface area, and the average pore diameter were investigated using X-ray diffraction analysis, transmission electron microscopy, scanning electro...

  7. Estimating kinetic parameters of complex catalytic reactions using a curve resolution based method

    Cruz, S.C.; Rothenberg, G.; Westerhuis, J.A.; Smilde, A.K.


    A Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) based algorithm is used to extract kinetic parameters from on-line FT - NIR data of a series of Heck reactions between iodobenzene and n-butyl acrylate (NBA), measured at different temperatures with different catalysts. Four

  8. Optimization of reaction parameters for the electrochemical oxidation of lidocaine with a Design of Experiments approach

    Gul, Turan; Bischoff, Rainer; Permentier, Hjalmar


    Identification of potentially toxic oxidative drug metabolites is a crucial step in the development of new drugs. Electrochemical methods are useful to study oxidative drug metabolism, but are not widely used to synthesize metabolites for follow-up studies. Careful optimization of reaction parameter

  9. Importance of cytochromes in cyclization reactions: quantum chemical study on a model reaction of proguanil to cycloguanil.

    Arfeen, Minhajul; Patel, Dhilon S; Abbat, Sheenu; Taxak, Nikhil; Bharatam, Prasad V


    Proguanil, an anti-malarial prodrug, undergoes cytochrome P450 catalyzed biotransformation to the pharmacologically active triazine metabolite (cycloguanil), which inhibits plasmodial dihydrofolate reductase. This cyclization is catalyzed by CYP2C19 and many anti-malarial lead compounds are being designed and synthesized to exploit this pathway. Quantum chemical calculations were performed using the model species (Cpd I for active species of cytochrome and N4-isopropyl-N6-methylbiguanide for proguanil) to elucidate the mechanism of the cyclization pathway. The overall reaction involves the loss of a water molecule, and is exothermic by approximately 55 kcal/mol, and involves a barrier of approximately 17 kcal/mol. The plausible reaction pathway involves the initial H-radical abstraction from the isopropyl group by Cpd I, followed by two alternative paths- (i) oxygen rebound to provide hydroxyl derivative and (ii) loss of additional H-radical to yield 1,3,5-triazatriene, which undergoes cyclization. This study helped in understanding the role of the active species of cytochromes in this important cyclization reaction. Copyright © 2014 Wiley Periodicals, Inc.

  10. Cross-entropy optimisation of importance sampling parameters for statistical model checking

    Jégourel, Cyrille; Sedwards, Sean


    Statistical model checking avoids the exponential growth of states associated with probabilistic model checking by estimating properties from multiple executions of a system and by giving results within confidence bounds. Rare properties are often very important but pose a particular challenge for simulation-based approaches, hence a key objective under these circumstances is to reduce the number and length of simulations necessary to produce a given level of confidence. Importance sampling is a well-established technique that achieves this, however to maintain the advantages of statistical model checking it is necessary to find good importance sampling distributions without considering the entire state space. Motivated by the above, we present a simple algorithm that uses the notion of cross-entropy to find the optimal parameters for an importance sampling distribution. In contrast to previous work, our algorithm uses a low dimensional vector of parameters to define this distribution and thus avoids the ofte...

  11. 'Adaptive Importance Sampling for Performance Evaluation and Parameter Optimization of Communication Systems'

    Remondo Bueno, D.; Srinivasan, R.; Nicola, V.F.; van Etten, Wim; Tattje, H.E.P.


    We present new adaptive importance sampling techniques based on stochastic Newton recursions. Their applicability to the performance evaluation of communication systems is studied. Besides bit-error rate (BER) estimation, the techniques are used for system parameter optimization. Two system models

  12. External Load Affects Ground Reaction Force Parameters Non-uniformly during Running in Weightlessness

    DeWitt, John; Schaffner, Grant; Laughlin, Mitzi; Loehr, James; Hagan, R. Donald


    Long-term exposure to microgravity induces detrimefits to the musculcskdetal system (Schneider et al., 1995; LeBlanc et al., 2000). Treadmill exercise is used onboard the International Space Station as an exercise countermeasure to musculoskeletal deconditioning due to spaceflight. During locomotive exercise in weightlessness (0G), crewmembers wear a harness attached to an external loading mechanism (EL). The EL pulls the crewmember toward the treadmill, and provides resistive load during the impact and propulsive phases of gait. The resulting forces may be important in stimulating bone maintenance (Turner, 1998). The EL can be applied via a bungee and carabineer clip configuration attached to the harness and can be manipulated to create varying amounts of load levels during exercise. Ground-based research performed using a vertically mounted treadmill found that peak ground reaction forces (GRF) during running at an EL of less than one body weight (BW) are less than those that occur during running in normal gravity (1G) (Davis et al., 1996). However, it is not known how the GRF are affected by the EL in a true OG environment. Locomotion while suspended may result in biomechanics that differ from free running. The purpose of this investigation was to determine how EL affects peak impact force, peak propulsive force, loading rate, and impulse of the GRF during running in 0G. It was hypothesized that increasing EL would result in increases in each GRF parameter.

  13. Correlation between electronic parameters and corrosion inhibition of benzothiazole derivatives- NMR parameters as important and neglected descriptors

    Behzadi, Hadi; Forghani, Ali


    The relation between electronic properties and corrosion inhibitive performance of three benzothiazole derivatives 1,3-benzothiazol-2-amine (BTA), 6-methyl-1,3-benzothiazol-2-amine (MBTA) and 2-amino-1,3-benzthiazole-6-thiol (TBTA) has been investigated by density functional theory. The electronic properties including EHOMO, ELUMO and related parameters were calculated at the B3LYP/6-311++G(d,p) level. The chemical shielding CS tensors were introduced as important and neglected descriptors to evaluate inhibitive efficiency of corrosion inhibitors. Nuclear independent chemical shift (NICS) components, as an aromaticity criterion, were also investigated as local descriptor. Polarizability and CS descriptors, as second rank tensors, show the best correlations with inhibition efficiencies of studied inhibitors.

  14. Determining Relative Importance and Effective Settings for Genetic Algorithm Control Parameters.

    Mills, K L; Filliben, J J; Haines, A L


    Setting the control parameters of a genetic algorithm to obtain good results is a long-standing problem. We define an experiment design and analysis method to determine relative importance and effective settings for control parameters of any evolutionary algorithm, and we apply this method to a classic binary-encoded genetic algorithm (GA). Subsequently, as reported elsewhere, we applied the GA, with the control parameter settings determined here, to steer a population of cloud-computing simulators toward behaviors that reveal degraded performance and system collapse. GA-steered simulators could serve as a design tool, empowering system engineers to identify and mitigate low-probability, costly failure scenarios. In the existing GA literature, we uncovered conflicting opinions and evidence regarding key GA control parameters and effective settings to adopt. Consequently, we designed and executed an experiment to determine relative importance and effective settings for seven GA control parameters, when applied across a set of numerical optimization problems drawn from the literature. This paper describes our experiment design, analysis, and results. We found that crossover most significantly influenced GA success, followed by mutation rate and population size and then by rerandomization point and elite selection. Selection method and the precision used within the chromosome to represent numerical values had least influence. Our findings are robust over 60 numerical optimization problems.

  15. Accurate prediction of severe allergic reactions by a small set of environmental parameters (NDVI, temperature).

    Notas, George; Bariotakis, Michail; Kalogrias, Vaios; Andrianaki, Maria; Azariadis, Kalliopi; Kampouri, Errika; Theodoropoulou, Katerina; Lavrentaki, Katerina; Kastrinakis, Stelios; Kampa, Marilena; Agouridakis, Panagiotis; Pirintsos, Stergios; Castanas, Elias


    Severe allergic reactions of unknown etiology,necessitating a hospital visit, have an important impact in the life of affected individuals and impose a major economic burden to societies. The prediction of clinically severe allergic reactions would be of great importance, but current attempts have been limited by the lack of a well-founded applicable methodology and the wide spatiotemporal distribution of allergic reactions. The valid prediction of severe allergies (and especially those needing hospital treatment) in a region, could alert health authorities and implicated individuals to take appropriate preemptive measures. In the present report we have collecterd visits for serious allergic reactions of unknown etiology from two major hospitals in the island of Crete, for two distinct time periods (validation and test sets). We have used the Normalized Difference Vegetation Index (NDVI), a satellite-based, freely available measurement, which is an indicator of live green vegetation at a given geographic area, and a set of meteorological data to develop a model capable of describing and predicting severe allergic reaction frequency. Our analysis has retained NDVI and temperature as accurate identifiers and predictors of increased hospital severe allergic reactions visits. Our approach may contribute towards the development of satellite-based modules, for the prediction of severe allergic reactions in specific, well-defined geographical areas. It could also probably be used for the prediction of other environment related diseases and conditions.

  16. Accurate prediction of severe allergic reactions by a small set of environmental parameters (NDVI, temperature.

    George Notas

    Full Text Available Severe allergic reactions of unknown etiology,necessitating a hospital visit, have an important impact in the life of affected individuals and impose a major economic burden to societies. The prediction of clinically severe allergic reactions would be of great importance, but current attempts have been limited by the lack of a well-founded applicable methodology and the wide spatiotemporal distribution of allergic reactions. The valid prediction of severe allergies (and especially those needing hospital treatment in a region, could alert health authorities and implicated individuals to take appropriate preemptive measures. In the present report we have collecterd visits for serious allergic reactions of unknown etiology from two major hospitals in the island of Crete, for two distinct time periods (validation and test sets. We have used the Normalized Difference Vegetation Index (NDVI, a satellite-based, freely available measurement, which is an indicator of live green vegetation at a given geographic area, and a set of meteorological data to develop a model capable of describing and predicting severe allergic reaction frequency. Our analysis has retained NDVI and temperature as accurate identifiers and predictors of increased hospital severe allergic reactions visits. Our approach may contribute towards the development of satellite-based modules, for the prediction of severe allergic reactions in specific, well-defined geographical areas. It could also probably be used for the prediction of other environment related diseases and conditions.

  17. A new algorithm for importance analysis of the inputs with distribution parameter uncertainty

    Li, Luyi; Lu, Zhenzhou


    Importance analysis is aimed at finding the contributions by the inputs to the uncertainty in a model output. For structural systems involving inputs with distribution parameter uncertainty, the contributions by the inputs to the output uncertainty are governed by both the variability and parameter uncertainty in their probability distributions. A natural and consistent way to arrive at importance analysis results in such cases would be a three-loop nested Monte Carlo (MC) sampling strategy, in which the parameters are sampled in the outer loop and the inputs are sampled in the inner nested double-loop. However, the computational effort of this procedure is often prohibitive for engineering problem. This paper, therefore, proposes a newly efficient algorithm for importance analysis of the inputs in the presence of parameter uncertainty. By introducing a 'surrogate sampling probability density function (SS-PDF)' and incorporating the single-loop MC theory into the computation, the proposed algorithm can reduce the original three-loop nested MC computation into a single-loop one in terms of model evaluation, which requires substantially less computational effort. Methods for choosing proper SS-PDF are also discussed in the paper. The efficiency and robustness of the proposed algorithm have been demonstrated by results of several examples.

  18. Monitoring biodiesel reactions of soybean oil and sunflower oil using ultrasonic parameters

    Figueiredo, M. K. K.; Silva, C. E. R.; Alvarenga, A. V.; Costa-Félix, R. P. B.


    Biodiesel is an innovation that attempts to substitute diesel oil with biomass. The aim of this paper is to show the development of a real-time method to monitor transesterification reactions by using low-power ultrasound and pulse/echo techniques. The results showed that it is possible to identify different events during the transesterification process by using the proposed parameters, showing that the proposed method is a feasible way to monitor the reactions of biodiesel during its fabrication, in real time, and with relatively low- cost equipment.

  19. Radiatively Important Parameters Best Estimate (RIPBE): An ARM Value-Added Product

    McFarlane, S; Shippert, T; Mather, J


    The Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to create a complete set of clearly identified set of parameters on a uniform vertical and temporal grid to use as input to a radiative transfer model. One of the main drivers for RIPBE was as input to the Broadband Heating Rate Profile (BBHRP) VAP, but we also envision using RIPBE files for user-run radiative transfer codes, as part of cloud/aerosol retrieval testbeds, and as input to averaged datastreams for model evaluation.

  20. Tattoo-Associated Skin Reaction: The Importance of an Early Diagnosis and Proper Treatment

    Andrea Bassi


    Full Text Available Tattoo is going to be a very common practice especially among young people and we are witnessing a gradual increase of numerous potential complications to tattoo placement which are often seen by physicians, but generally unknown to the public. The most common skin reactions to tattoo include a transient acute inflammatory reaction due to trauma of the skin with needles and medical complications such as superficial and deep local infections, systemic infections, allergic contact dermatitis, photodermatitis, granulomatous and lichenoid reactions, and skin diseases localized on tattooed area (eczema, psoriasis, lichen, and morphea. Next to these inflammatory skin reactions we have to consider also the possibility of the development of cutaneous conditions such as pseudolymphomatous reactions and pseudoepitheliomatous hyperplasia. The aim of this study is to underline the importance of an early diagnosis by performing a histological examination especially when we are in front of suspected papulonodular lesions arising from a tattoo, followed by a proper treatment, since cutaneous neoplastic evolution is known to be a rare but possible complication.

  1. Maximum Likelihood Estimates of Parameters in Various Types of Distribution Fitted to Important Data Cases.

    Hirose, Hideo


    TYPES OF THE DISTRIBUTION:13;Normal distribution (2-parameter)13;Uniform distribution (2-parameter)13;Exponential distribution ( 2-parameter)13;Weibull distribution (2-parameter)13;Gumbel Distribution (2-parameter)13;Weibull/Frechet Distribution (3-parameter)13;Generalized extreme-value distribution (3-parameter)13;Gamma distribution (3-parameter)13;Extended Gamma distribution (3-parameter)13;Log-normal distribution (3-parameter)13;Extended Log-normal distribution (3-parameter)13;Generalized ...

  2. Maximum Likelihood Estimates of Parameters in Various Types of Distribution Fitted to Important Data Cases.

    Hirose, Hideo


    TYPES OF THE DISTRIBUTION:13;Normal distribution (2-parameter)13;Uniform distribution (2-parameter)13;Exponential distribution ( 2-parameter)13;Weibull distribution (2-parameter)13;Gumbel Distribution (2-parameter)13;Weibull/Frechet Distribution (3-parameter)13;Generalized extreme-value distribution (3-parameter)13;Gamma distribution (3-parameter)13;Extended Gamma distribution (3-parameter)13;Log-normal distribution (3-parameter)13;Extended Log-normal distribution (3-parameter)13;Generalized ...

  3. Simple and Superlattice Turing Patterns in Reaction-Diffusion Systems Bifurcation, Bistability, and Parameter Collapse

    Judd, S L; Judd, Stephen L.; Silber, Mary


    This paper investigates the competition between both simple (e.g. stripes, hexagons) and ``superlattice'' (super squares, super hexagons) Turing patterns in two-component reaction-diffusion systems. ``Superlattice'' patterns are formed from eight or twelve Fourier modes, and feature structure at two different length scales. Using perturbation theory, we derive simple analytical expressions for the bifurcation equation coefficients on both rhombic and hexagonal lattices. These expressions show that, no matter how complicated the reaction kinectics, the nonlinear reaction terms reduce to just four effective terms within the bifurcation equation coefficients. Moreover, at the hexagonal degeneracy -- when the quadratic term in the hexagonal bifurcation equation disappears -- the number of effective system parameters drops to two, allowing a complete characterization of the possible bifurcation results at this degeneracy. The general results are then applied to specific model equations, to investigate the stabilit...

  4. Reaction parameter study for the chemical synthesis of adsorbent silica gel

    María Carolina Sáenz


    Full Text Available This article presents an appropriate set of reaction parameters (reaction temperature, sulphuric acid and sodium silicate reagent concentration for obtaining adsorbent silica gel (ASG using Colombian-produced raw materials. The core of ASG synthesis lies in sulphuric acid’s neutralisation reaction with sodium silicate. Their effect on final ASG moisture adsorption capacity was measured after changing such synthesis’ above–mentioned reaction parameters. Within the range of conditions studied, it was found that the highest adsorption capacity occurred by combining both low sodium silicate concentration with high temperatures or high sulphuric acid concentration and temperature. Synthesised ASG was also compared to a commercial product (Gel de sílice granulare con indicatore. Montedison group. Batch number 1684G100. Code number 453301 using adsorption capacity plots, BET areas, X–ray di-ffraction, mass and infrared spectrometry and mechanical strength measurements. Synthesised ASG presented larger specific surface areas but weaker mechanical strength than the commercial one. Likewise, all evaluated samples exhibited a low degree of molecular arrangement and conventional ASG chemical structure.

  5. Determination of 68Ga production parameters by different reactions using ALICE and TALYS codes

    Mahdi Sadeghi; Tayeb Kakavand; Leila Mokhtari; Zohreh Gholamzadeh


    Gallium-68 (1/2 = 68 min, + = 89%) is an important positron-emitting radionuclide for positron emission tomography and used in nuclear medicine for diagnosing tumours. This study gives a suitable reaction to produce 68Ga. Gallium-68 excitation function via 68Zn(, ) 68Ga, 68Zn(, 2) 68Ga, 70Zn(, 3) 68Ga and 65Cu(, ) 68Ga reactions were calculated by ALICE-91 and TALYS-1.0 codes. The calculated excitation function of 68Zn(, ) 68Ga reaction was compared with the reported measurement and evaluations. Requisite thickness of the targets was obtained by SRIM code for each reaction. The 68Ga production yield was evaluated using excitation function and stopping power.

  6. How important is heterogeneous parameter distribution in capturing the catchment response through hydrologic modelling?

    Devak, Manjula; Dhanya, Ct


    The scrupulous selection of critical spatial and temporal resolution and the evaluation of optimum values for various model parameters are essential aspects in any hydrological modelling study. The accurate assessment of various model parameters is vitally important for the detailed and complete representation of the various physical processes illustrating land-atmosphere interaction. Studies in the past have taken up various auto-calibration and parameter transferability schemes to address these; but the heterogeneity of calibration parameters across grids is greatly ignored often. In many studies, heterogeneity is often compromised through the usual interpolation approaches adopted across grids. In the present study, we focus to analyze the response of a catchment by adopting a heterogeneous and homogeneous parameter distribution in the hydrological model. The semi-distributed hydrological model, Variable Infiltration Capacity (VIC-3L) model, which offers sub-grid variability in soil moisture storage capacity and vegetation classes, is used for this comparison. Nine model parameters are selected for calibrating the VIC-3L model, namely variable infiltration curve parameter (infilt), maximum velocity of base flow for each grid cells (DSmax), fraction of DSmax where non-linear base flow begins (DS, fraction of maximum soil moisture where non-linear base flow occurs (WS), depth of 2nd soil layer (D2), depth of 3rd soil layer (D3), exponent used in baseflow curve (c), advection coefficient (C) and diffusion coefficient (D). Latin-Hypercube sampling is adopted to sample these nine parameters. In homogenous approach, the traditional way of constant soil parameter distribution (HoSCP) is adopted to prepare the parameter set. While, in heterogeneous approach, grid-to-grid variability is ensured by constructing a Heterogeneous Soil Calibration Parameter (HeSCP) set through systematic sampling of already sampled set. The sampling size is made equal to the number of grids

  7. Is H Atom Abstraction Important in the Reaction of Cl with 1-Alkenes?

    Walavalkar, M P; Vijayakumar, S; Sharma, A; Rajakumar, B; Dhanya, S


    The relative yields of products of the reaction of Cl atoms with 1-alkenes (C4-C9) were determined to see whether H atom abstraction is an important channel and if it is to identify the preferred position of abstraction. The presence of all the possible positional isomers of long chain alkenones and alkenols among the products, along with chloroketones and chloroalcohols, confirms the occurrence of H atom abstraction. A consistent pattern of distribution of abstraction products is observed with oxidation at C4 (next to allyl) being the lowest and that at CH2 groups away from the double bond being the highest. This contradicts with the higher stability of allyl (C3) radical. For a better understanding of the relative reactivity, ab initio calculations at MP2/6-311+G (d,p) level of theory are carried out in the case of 1-heptene. The total rate coefficient, calculated using conventional transition state theory, was found to be in good agreement with the experimental value at room temperature. The preferred position of Cl atom addition is predicted to be the terminal carbon atom, which matches with the experimental observation, whereas the rate coefficients calculated for individual channels of H atom abstraction do not explain the observed pattern of products. The distribution of abstraction products except at C4 is found to be better explained by reported structure activity relationship, developed from experimental rate coefficient data. This implies the reactions to be kinetically dictated and emphasizes the importance of secondary reactions.

  8. The Importance of Hematological Parameters in Acute Respiratory Viral Infections in Children

    L. A. Alekseeva


    Full Text Available Hematological studies are basic and mandatory in diagnostics and laboratory monitoring of infectious diseases, which led to their inclusion in the modern standards of laboratory examinations of children. Assessment of hematological parameters used for the provisional differential diagnosis of viral or bacterial nature of the disease. For research currently being used increasingly Hematology analyzers, which allows to facilitate and standardize the results. In this paper a comparison and differences hematological parameters practically healthy children and children with respiratory infections. Identified some changes in indicators of haemogram depending on the etiology and character of the clinical course of the disease. On the basis of the leukocyte formula defined leukocyte indices of intoxication and illustrates their importance in assessing the severity of the infection process.

  9. Life cycle assessment and residue leaching: The importance of parameter, scenario and leaching data selection

    Allegrini, Elisa; Butera, Stefania; Kosson, D.S.


    boundaries. The importance of data quality and parameter selection in the overall LCA results was evaluated, and an innovative method to assess metal transport into the environment was applied, in order to determine emissions to the soil and water compartments for use in an LCA. It was found that toxic...... of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens...... in the scenario (e.g. electricity production). Based on the analysis of relevant parameters relative to leaching, and on general results of the study, recommendations are provided regarding the use of leaching data in LCA studies....

  10. Parameter Estimation


    of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set......In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....

  11. Relative importance of parameters affecting wind speed prediction using artificial neural networks

    Ghorbani, M. A.; Khatibi, R.; Hosseini, B.; Bilgili, M.


    In traditional artificial neural networks (ANN) models, the relative importance of the individual meteorological input variables is often overlooked. A case study is presented in this paper to model monthly wind speed values using meteorological data (air pressure, air temperature, relative humidity, and precipitation), where the study also includes an estimate of the relative importance of these variables. Recorded monthly mean data are available at a gauging site in Tabriz, Azerbaijan, Iran, for the period from 2000 to 2005, gauged in the city at the outskirt of alluvial funneling mountains with an established microclimatic conditions and a diurnal wind regime. This provides a sufficiently severe test for the ANN model with a good predictive capability of 1 year of lead time but without any direct approach to refer the predicted results to local microclimatic conditions. A method is used in this paper to calculate the relative importance of each meteorological input parameters affecting wind speed, showing that air pressure and precipitation are the most and least influential parameters with approximate values of 40 and 10 %, respectively. This gained knowledge corresponds to the local knowledge of the microclimatic and geomorphologic conditions surrounding Tabriz.

  12. Development of quantitative radioactive methodologies on paper to determine important lateral-flow immunoassay parameters.

    Mosley, Garrett L; Nguyen, Phuong; Wu, Benjamin M; Kamei, Daniel T


    The lateral-flow immunoassay (LFA) is a well-established diagnostic technology that has recently seen significant advancements due in part to the rapidly expanding fields of paper diagnostics and paper-fluidics. As LFA-based diagnostics become more complex, it becomes increasingly important to quantitatively determine important parameters during the design and evaluation process. However, current experimental methods for determining these parameters have certain limitations when applied to LFA systems. In this work, we describe our novel methods of combining paper and radioactive measurements to determine nanoprobe molarity, the number of antibodies per nanoprobe, and the forward and reverse rate constants for nanoprobe binding to immobilized target on the LFA test line. Using a model LFA system that detects for the presence of the protein transferrin (Tf), we demonstrate the application of our methods, which involve quantitative experimentation and mathematical modeling. We also compare the results of our rate constant experiments with traditional experiments to demonstrate how our methods more appropriately capture the influence of the LFA environment on the binding interaction. Our novel experimental approaches can therefore more efficiently guide the research process for LFA design, leading to more rapid advancement of the field of paper-based diagnostics.

  13. A finite difference method for estimating second order parameter sensitivities of discrete stochastic chemical reaction networks.

    Wolf, Elizabeth Skubak; Anderson, David F


    We present an efficient finite difference method for the approximation of second derivatives, with respect to system parameters, of expectations for a class of discrete stochastic chemical reaction networks. The method uses a coupling of the perturbed processes that yields a much lower variance than existing methods, thereby drastically lowering the computational complexity required to solve a given problem. Further, the method is simple to implement and will also prove useful in any setting in which continuous time Markov chains are used to model dynamics, such as population processes. We expect the new method to be useful in the context of optimization algorithms that require knowledge of the Hessian.

  14. Investigation of the effect of organic solvents on kinetic parameters in metal catalyzed reactions



    Full Text Available The effects of acetone and acetonitrile on the kinetic parameters of azorubin S oxidation by hydrogen peroxide catalyzed by manganese(II, pyrocatechol violet oxidation by hydrogen peroxide catalyzed by copper(II, and carminic acid oxidation by hydrogen peroxide catalyzed by copper(II and activated by bifenox, were examined. It was established that the examined solvents exhibit various effects on the kinetic parameters of the above said reactions. In a11 instances a change in the solvent concentration effects both the anthalpy and the entropy contributions to the free activation energy during the transition of the system into the active state, as well as the constant of the active complex formed at this point.

  15. An observer for an occluded reaction-diffusion system with spatially varying parameters

    Kramer, Sean; Bollt, Erik M.


    Spatially dependent parameters of a two-component chaotic reaction-diffusion partial differential equation (PDE) model describing ocean ecology are observed by sampling a single species. We estimate the model parameters and the other species in the system by autosynchronization, where quantities of interest are evolved according to misfit between model and observations, to only partially observed data. Our motivating example comes from oceanic ecology as viewed by remote sensing data, but where noisy occluded data are realized in the form of cloud cover. We demonstrate a method to learn a large-scale coupled synchronizing system that represents the spatio-temporal dynamics and apply a network approach to analyze manifold stability.

  16. Interpretation and application of reaction class transition state theory for accurate calculation of thermokinetic parameters using isodesmic reaction method.

    Wang, Bi-Yao; Li, Ze-Rong; Tan, Ning-Xin; Yao, Qian; Li, Xiang-Yuan


    We present a further interpretation of reaction class transition state theory (RC-TST) proposed by Truong et al. for the accurate calculation of rate coefficients for reactions in a class. It is found that the RC-TST can be interpreted through the isodesmic reaction method, which is usually used to calculate reaction enthalpy or enthalpy of formation for a species, and the theory can also be used for the calculation of the reaction barriers and reaction enthalpies for reactions in a class. A correction scheme based on this theory is proposed for the calculation of the reaction barriers and reaction enthalpies for reactions in a class. To validate the scheme, 16 combinations of various ab initio levels with various basis sets are used as the approximate methods and CCSD(T)/CBS method is used as the benchmarking method in this study to calculate the reaction energies and energy barriers for a representative set of five reactions from the reaction class: R(c)CH(R(b))CR(a)CH2 + OH(•) → R(c)C(•)(R(b))CR(a)CH2 + H2O (R(a), R(b), and R(c) in the reaction formula represent the alkyl or hydrogen). Then the results of the approximate methods are corrected by the theory. The maximum values of the average deviations of the energy barrier and the reaction enthalpy are 99.97 kJ/mol and 70.35 kJ/mol, respectively, before correction and are reduced to 4.02 kJ/mol and 8.19 kJ/mol, respectively, after correction, indicating that after correction the results are not sensitive to the level of the ab initio method and the size of the basis set, as they are in the case before correction. Therefore, reaction energies and energy barriers for reactions in a class can be calculated accurately at a relatively low level of ab initio method using our scheme. It is also shown that the rate coefficients for the five representative reactions calculated at the BHandHLYP/6-31G(d,p) level of theory via our scheme are very close to the values calculated at CCSD(T)/CBS level. Finally, reaction

  17. Surface and Atmospheric Parameter Retrieval From AVIRIS Data: The Importance of Non-Linear Effects

    Green Robert O.; Moreno, Jose F.


    AVIRIS data represent a new and important approach for the retrieval of atmospheric and surface parameters from optical remote sensing data. Not only as a test for future space systems, but also as an operational airborne remote sensing system, the development of algorithms to retrieve information from AVIRIS data is an important step to these new approaches and capabilities. Many things have been learned since AVIRIS became operational, and the successive technical improvements in the hardware and the more sophisticated calibration techniques employed have increased the quality of the data to the point of almost meeting optimum user requirements. However, the potential capabilities of imaging spectrometry over the standard multispectral techniques have still not been fully demonstrated. Reasons for this are the technical difficulties in handling the data, the critical aspect of calibration for advanced retrieval methods, and the lack of proper models with which to invert the measured AVIRIS radiances in all the spectral channels. To achieve the potential of imaging spectrometry, these issues must be addressed. In this paper, an algorithm to retrieve information about both atmospheric and surface parameters from AVIRIS data, by using model inversion techniques, is described. Emphasis is put on the derivation of the model itself as well as proper inversion techniques, robust to noise in the data and an inadequate ability of the model to describe natural variability in the data. The problem of non-linear effects is addressed, as it has been demonstrated to be a major source of error in the numerical values retrieved by more simple, linear-based approaches. Non-linear effects are especially critical for the retrieval of surface parameters where both scattering and absorption effects are coupled, as well as in the cases of significant multiple-scattering contributions. However, sophisticated modeling approaches can handle such non-linear effects, which are especially

  18. The determination of the kinetic parameters of electrochemical reaction in chemical power sources: A critical review

    Xu, Yanhui; Wu, Jun; Li, Decheng; Zheng, Junwei [The Institute of Chemical Power Sources, Soochow (Suzhou) University, Suzhou 215006 (China); Chen, Ying [Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Duesseldorf (Germany); Ju, Hua [School of Urban Rail Transportation, Soochow (Suzhou) University, Ganjiang East Road 178, Suzhou 215021 (China)


    The derivation and proposal of major electrochemical techniques used to determine and calculate the electrochemical kinetic parameters is basically based on the electrochemical reaction taking place at liquid/solid or liquid/liquid interface in which all the reactants and products are soluble in liquid aqueous solution or liquid mercury electrode, or are volatile gas. Such electrochemical reaction system is classical and traditional (ERS1). Recently, the electrochemical behavior of some materials used as the active electrode materials in chemical power sources has attracted much attention. In chemical power source systems, either reactant or product, or both are insoluble. This kind of electrochemical reaction system (ERS2) is slightly different from ERS1. The application of these electrochemical techniques/equations to chemical power sources' system requires carefulness. The misuse of these electrochemical techniques can be easily found in the literatures and some of them even lead to a wrong conclusion. In this review, almost all the electrochemical techniques to measure the exchange current and diffusion coefficient were compiled for reference to the readers, including pulse step, electrochemical impedance, alternating cyclic voltammetry, etc. The necessary requirements/conditions to apply these techniques have been briefly discussed and some simple examples were also discussed for a better understanding. (author)

  19. Deuterium–tritium catalytic reaction in fast ignition: Optimum parameters approach

    B Khanbabaei; A Ghasemizad; S Khoshbinfar


    One of the main concerns about the currentworking on nuclear power reactors is the potential hazard of their radioactive waste. There is hope that this issue will be reduced in next generation nuclear fusion power reactors. Reactors will release nuclear energy through microexplosions that occur in a mixture of hydrogen isotopes of deuterium and tritium. However, there exist radiological hazards due to the accumulation of tritium in the blanket layer. A catalytic fusion reaction of DT mixture may stand between DD and an equimolar DT approach in which the fusion process continues with a small amount of tritium seed. In this paper, we investigate the possibility of DT reaction in the fast ignition (FI) scheme. The kinematic study of the main mechanism of the energy gain–loss term, which may disturb the ignition and burn process, was performed in FI and the optimum values of precompressed fuel and proton beam driver were derived. The recommended values of fuel parameters are: areal density $ρ R ≥ 5\\cdot$cm-2 and initial tritium fraction ≤ 0.025. For the proton beam, the corresponding optimum interval values are proton average energy $3≤ E_p ≤ 10$ MeV, pulse duration $5 ≤ t_p ≤ 15$ ps and power $5≤ W_p ≤ 12 × 10^{22}$ (keV$\\cdot$cm3$\\cdot$ps-1). It was proved that under the above conditions, a fast ignition DT reaction stays in the catalytic regime.

  20. Methane dissociation on Pt(111): Searching for a specific reaction parameter density functional

    Nattino, Francesco, E-mail:; Migliorini, Davide; Kroes, Geert-Jan [Leiden Institute of Chemistry, Leiden University, Gorlaeus Laboratories, P.O. Box 9502, 2300 RA Leiden (Netherlands); Bonfanti, Matteo [Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano (Italy)


    The theoretical description of methane dissociating on metal surfaces is a current frontier in the field of gas-surface dynamics. Dynamical models that aim at achieving a highly accurate description of this reaction rely on potential energy surfaces based on density functional theory calculations at the generalized gradient approximation. We focus here on the effect that the exchange-correlation functional has on the reactivity of methane on a metal surface, using CHD{sub 3} + Pt(111) as a test case. We present new ab initio molecular dynamics calculations performed with various density functionals, looking also at functionals that account for the van der Waals (vdW) interaction. While searching for a semi-empirical specific reaction parameter density functional for this system, we find that the use of a weighted average of the PBE and the RPBE exchange functionals together with a vdW-corrected correlation functional leads to an improved agreement with quantum state-resolved experimental data for the sticking probability, compared to previous PBE calculations. With this semi-empirical density functional, we have also investigated the surface temperature dependence of the methane dissociation reaction and the influence of the rotational alignment on the reactivity, and compared our results with experiments.

  1. Ethanol-resistant ethylcellulose/guar gum coatings--importance of formulation parameters.

    Rosiaux, Y; Velghe, C; Muschert, S; Chokshi, R; Leclercq, B; Siepmann, F; Siepmann, J


    Recently, ethylcellulose/guar gum blends have been reported to provide ethanol-resistant drug release kinetics from coated dosage forms. This is because the ethanol insoluble guar gum effectively avoids undesired ethylcellulose dissolution in ethanol-rich bulk fluids. However, so far the importance of crucial formulation parameters, including the minimum amount of guar gum to be incorporated and the minimum required guar gum viscosity, remains unclear. The aim of this study was to identify the most important film coating properties, determining whether or not the resulting drug release kinetics is ethanol-resistant. Theophylline matrix cores were coated in a fluid bed with blends of the aqueous ethylcellulose dispersion "Aquacoat®ECD30" and guar gum. The polymer blend ratio, guar gum viscosity, and degree of dilution of the final coating dispersion were varied. Importantly, it was found that more than 5% guar gum (referred to the total polymer content) must be incorporated in the film coating and that the apparent viscosity of a 1% aqueous guar gum solution must be greater than 150 cP to provide ethanol-resistance. In contrast, the investigated degree of coating dispersion dilution was not found to be decisive for the ethanol sensitivity. Furthermore, all investigated formulations were long term stable, even upon open storage under stress conditions for 6 months.

  2. Life cycle assessment and residue leaching: The importance of parameter, scenario and leaching data selection

    Allegrini, E., E-mail: [Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Lyngby (Denmark); Butera, S. [Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Lyngby (Denmark); Kosson, D.S. [Vanderbilt University, Department of Civil and Environmental Engineering, Box 1831 Station B, Nashville, TN 37235 (United States); Van Zomeren, A. [Energy Research Centre of the Netherlands (ECN), Department of Environmental Risk Assessment, P.O. Box 1, 1755 ZG Petten (Netherlands); Van der Sloot, H.A. [Hans van der Sloot Consultancy, Dorpsstraat 216, 1721 BV Langedijk (Netherlands); Astrup, T.F. [Technical University of Denmark, Department of Environmental Engineering, Building 115, 2800 Lyngby (Denmark)


    Highlights: • Relevance of metal leaching in waste management system LCAs was assessed. • Toxic impacts from leaching could not be disregarded. • Uncertainty of toxicity, due to background activities, determines LCA outcomes. • Parameters such as pH and L/S affect LCA results. • Data modelling consistency and coverage within an LCA are crucial. - Abstract: Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens, due to the potential leaching of toxic substances. In waste LCA studies where residue utilisation is included, leaching has generally been neglected. In this study, municipal solid waste incineration bottom ash (MSWI BA) was used as a case study into three LCA scenarios having different system boundaries. The importance of data quality and parameter selection in the overall LCA results was evaluated, and an innovative method to assess metal transport into the environment was applied, in order to determine emissions to the soil and water compartments for use in an LCA. It was found that toxic impacts as a result of leaching were dominant in systems including only MSWI BA utilisation, while leaching appeared negligible in larger scenarios including the entire waste system. However, leaching could not be disregarded a priori, due to large uncertainties characterising other activities in the scenario (e.g. electricity production). Based on the analysis of relevant parameters relative to leaching, and on general results

  3. Supercritical water oxidation of Quinazoline: Effects of conversion parameters and reaction mechanism.

    Gong, Yanmeng; Guo, Yang; Wang, Shuzhong; Song, Wenhan


    The supercritical water oxidation reaction of quinazoline and a set of related reaction products were investigated in batch reactors by varying the temperature (T, 400-600 °C), time (t, 0-400 s), water density (ρ, 70.79-166.28  kg m(-3)) and oxidation coefficient (OC, 0-4.0). The TOC removal efficiency (CRE) increased significantly as the OC increased, whereas this effect was very limited at high OC (>2.0). Lack of oxygen resulted in low CRE and TN removal efficiency (NRE), also cause coke-formation, and giving high yield of NH3 and nitrogenous organic intermediates. Prolonging reaction time did not provide an appreciable improvement on CRE but remarkably increased NRE at temperature higher than 500 °C. Pyrimidines and pyridines as the nitrogenous intermediates were largely found in GC-MS spectrum. Polymerization among benzene, phenyl radical and benzyl radical played important roles in the formation of PAHs, such as naphthalene, biphenyl, phenanthrene. These collective results showed how the yield of intermediate products responded to changes in the process variables, which permitted the development of a potential reaction network for supercritical water oxidation of quinazoline.

  4. Assessment of changes in gait parameters and vertical ground reaction forces after total hip arthroplasty

    Bhargava P


    Full Text Available The principal objectives of arthroplasty are relief of pain and enhancement of range of motion. Currently, postoperative pain and functional capacity are assessed largely on the basis of subjective evaluation scores. Because of the lack of control inherent in this method it is often difficult to interpret data presented by different observers in the critical evaluation of surgical method, new components and modes of rehabilitation. Gait analysis is a rapid, simple and reliable method to assess functional outcome. This study was undertaken in an effort to evaluate the gait characteristics of patients who underwent arthroplasty, using an Ultraflex gait analyzer. Materials and Methods: The study was based on the assessment of gait and weight-bearing pattern of both hips in patients who underwent total hip replacement and its comparison with an age and sex-matched control group. Twenty subjects of total arthroplasty group having unilateral involvement, operated by posterior approach at our institution with a minimum six-month postoperative period were selected. Control group was age and sex-matched, randomly selected from the general population. Gait analysis was done using Ultraflex gait analyzer. Gait parameters and vertical ground reaction forces assessment was done by measuring the gait cycle properties, step time parameters and VGRF variables. Data of affected limb was compared with unaffected limb as well as control group to assess the weight-bearing pattern. Statistical analysis was done by′t′ test. Results: Frequency is reduced and gait cycle duration increased in total arthroplasty group as compared with control. Step time parameters including Step time, Stance time and Single support time are significantly reduced ( P value < .05 while Double support time and Single swing time are significantly increased ( P value < .05 in the THR group. Forces over each sensor are increased more on the unaffected limb of the THR group as compared to

  5. Predicting the wheel rolling resistance regarding important motion parameters using the artificial neural network

    F Gheshlaghi


    Full Text Available Introduction: Rolling resistance is one of the most substantial energy losses when the wheel moves on soft soil. Rolling resistance value optimization will help to improve energy efficiency. Accurate modeling of the interaction soil-tire is an important key to this optimization and has eliminated the need for costly field tests and has reduced the time required to test. Rolling resistance will change because of the tire and wheel motion parameters and characteristics of the ground surface. Some tire design parameters are more important such as the tire diameter, width, tire aspect ratio, lugs form, inflation pressure and mechanical properties of tire structure. On the other hand, the soil or ground surface characteristics include soil type; moisture content and bulk density have an important role in this phenomenon. In addition, the vertical load and the wheel motion parameters such as velocity and tire slip are the other factors which impact on tire rolling resistance. According to same studies about the rolling resistance of the wheel, the wheel is significantly affected by the dynamic load. Tire inflation pressure impacted on rolling resistance of tires that were moving on hard surfaces. Studies showed that the rolling resistance of tires with low inflation pressure (less than 100 kPa was too high. According to Zoz and Griss researches, increasing the tire pressure increases rolling resistance on soft soil but reduces the rolling resistance of on-road tires and tire-hard surface interaction. Based on these reports, the effect of velocity on tire rolling resistance for tractors and vehicles with low velocity (less than 5 meters per second is usually insignificant. According to Self and Summers studies, rolling resistance of the wheel is dramatically affected by dynamic load on the wheel. Artificial Neural Network is one of the best computational methods capable of complex regression estimation which is an advantage of this method compared with

  6. What are the important flood damage-influencing parameters? A data mining approach

    Merz, B.; Kreibich, H.; Lall, U.


    Today's approaches for assessing and modeling direct flood damages are not very advanced. The usual approach consists of stage-damage functions which relate the relative or absolute damage for a certain class of objects to the inundation depth. Other characteristics of the flooding situation and of the flooded object are rarely taken into account, although flood damage is influenced by a variety of factors. In this contribution we apply a group of data-mining techniques, known as tree-structured models, to flood damage assessment. Tree-structured models are attractive candidates for identifying important damage-influencing parameters in large damage data sets and for describing quantitatively the non-linear interactions between damage and damage-influencing parameters. A very comprehensive data set of more than 2000 damage records of private households in Germany is used. Each record contains details about a variety of potential damage-influencing characteristics, such as hydrological and hydraulic aspects of the flooding situation, state of precaution of the household, early warning and emergency measures undertaken, socio-economic status of the household. Tree-structured models are used to derive the dominating damage-influencing variables and their (non-linear) interactions. We show that they are a flexible and powerful alternative to traditional damage assessment approaches.

  7. Analytical applications of oscillatory chemical reactions: determination of some pharmaceuticaly and biologically important compounds

    Pejić Nataša D.


    Full Text Available Novel analytical methods for quantitive determination of analytes based on perturbations of oscillatory chemical reactions realized under open reactor conditions (continuosly fed well stirred tank reactor, CSTR, have been developed in the past twenty years. The proposed kinetic methods are generally based on the ability of the analyzed substances to change the kinetics of the chemical reactions matrix. The unambiguous correlation of quantitative characteristics of perturbations, and the amount (concentration of analyte expressed as a regression equation, or its graphics (calibration curve, enable the determination of the unknown analyte concentration. Attention is given to the development of these methods because of their simple experimental procedures, broad range of linear regression ( 10-7 10-4 mol L-1 and low limits of detection of analytes ( 10-6 10-8 mol L1, in some cases even lower than 10-12 mol L-1. Therefore, their application is very convenient for routine analysis of various inorganic and organic compounds as well as gases. This review summarizes progress made in the past 5 years on quantitative determination of pharmaceutically and biologically important compounds.

  8. Oxidation as an important factor of protein damage: Implications for Maillard reaction

    L Trnková; J Dršata; I Boušová


    Protein oxidation, the process caused especially by reactive oxygen and nitrogen species, is thought to play a major role in various oxidative processes within cells and is implicated in the development of many human diseases. This review provides a brief overview of the protein oxidation with the emphasis on the types of oxidation (oxidation of protein backbone and amino acid residues side chains, site-specific metal-catalysed protein oxidation), oxidation-dependent generation of protein hydroperoxides, carbonyl derivatives and protein–protein cross-linkages. Non-enzymatic glycoxidation (also known as Maillard reaction) as an important factor of protein damage, consequences of oxidative protein impairment and related diseases as well as means of monitoring and assessment of protein modifications are discussed.

  9. Life cycle assessment and residue leaching: the importance of parameter, scenario and leaching data selection.

    Allegrini, E; Butera, S; Kosson, D S; Van Zomeren, A; Van der Sloot, H A; Astrup, T F


    Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens, due to the potential leaching of toxic substances. In waste LCA studies where residue utilisation is included, leaching has generally been neglected. In this study, municipal solid waste incineration bottom ash (MSWI BA) was used as a case study into three LCA scenarios having different system boundaries. The importance of data quality and parameter selection in the overall LCA results was evaluated, and an innovative method to assess metal transport into the environment was applied, in order to determine emissions to the soil and water compartments for use in an LCA. It was found that toxic impacts as a result of leaching were dominant in systems including only MSWI BA utilisation, while leaching appeared negligible in larger scenarios including the entire waste system. However, leaching could not be disregarded a priori, due to large uncertainties characterising other activities in the scenario (e.g. electricity production). Based on the analysis of relevant parameters relative to leaching, and on general results of the study, recommendations are provided regarding the use of leaching data in LCA studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Identifiability of parameters and behaviour of MCMC chains: a case study using the reaction norm model.

    Shariati, M M; Korsgaard, I R; Sorensen, D


    Markov chain Monte Carlo (MCMC) enables fitting complex hierarchical models that may adequately reflect the process of data generation. Some of these models may contain more parameters than can be uniquely inferred from the distribution of the data, causing non-identifiability. The reaction norm model with unknown covariates (RNUC) is a model in which unknown environmental effects can be inferred jointly with the remaining parameters. The problem of identifiability of parameters at the level of the likelihood and the associated behaviour of MCMC chains were discussed using the RNUC as an example. It was shown theoretically that when environmental effects (covariates) are considered as random effects, estimable functions of the fixed effects, (co)variance components and genetic effects are identifiable as well as the environmental effects. When the environmental effects are treated as fixed and there are other fixed factors in the model, the contrasts involving environmental effects, the variance of environmental sensitivities (genetic slopes) and the residual variance are the only identifiable parameters. These different identifiability scenarios were generated by changing the formulation of the model and the structure of the data and the models were then implemented via MCMC. The output of MCMC sampling schemes was interpreted in the light of the theoretical findings. The erratic behaviour of the MCMC chains was shown to be associated with identifiability problems in the likelihood, despite propriety of posterior distributions, achieved by arbitrarily chosen uniform (bounded) priors. In some cases, very long chains were needed before the pattern of behaviour of the chain may signal the existence of problems. The paper serves as a warning concerning the implementation of complex models where identifiability problems can be difficult to detect a priori. We conclude that it would be good practice to experiment with a proposed model and to understand its features


    Dragan Lončar


    Full Text Available The implantation of the fertilized egg outside the uterine cavity leads to the development of ectopic pregnancy. The incidence of ectopic pregnancy is 1/100 births. The most common place of ectopic implantation of the fertilized ovum is the oviduct (98% with predilection for the ampullar part of the Fallopian tube. The aim of this study was to determine the predictive importance of beta-hCG and progesterone concentration compared to ultrasonographic finding in the ectopic pregnancy diagnosis.We examined 24 patients with ectopic pregnancies which we divided according to the days of amenorrhea into two groups: the first group with the total of 28 patients from 16–42 days and another group of 8 patients with amenorrhea longer than 42 days. The control group was comprised of 20 patients with vital intrauterine pregnancy, gestational age of 42-52 days. Blood samples for quantitative determination of hormones were collected on three occasions after 48 hours in the forenoon time in the examined and control group of pregnant women. Ultrasonographic examinations of all pregnant women were carried out immediately after blood sampling, with the trans-vaginal approach using "make loop" option, and measurements with an accuracy of 0.1 mm.Mean values for beta-hCG range from 698-1774 mlU/ml in the first group of pregnant women, and in the second group of 1896 mlU/ml to 4410 mlU/ml with a statistically significant difference compared to the values in the control group (p <0.001. The concentration of progesterone in the first group of women ranging from 41-70 nmol/l, and in the second group of 76-94 nmol/l which is also the statistically significant difference compared to the control group (p<0.002. We have shown that ultrasonographic finding with its parameters reliably predicts the values of biochemical parameters both in normal intrauterine pregnancy and in the case of ectopic pregnancy.Embryo viability and implantation place condition the values of

  12. Cintichem modified process - {sup 99}Mo precipitation step: application of statistical analysis tools over the reaction parameters

    Teodoro, Rodrigo; Dias, Carla R.B.R.; Osso Junior, Joao A., E-mail: jaosso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Fernandez Nunez, Eutimio Gustavo [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Quimica


    Precipitation of {sup 99}Mo by {alpha}-benzoin oxime ({alpha}-Bz) is a standard precipitation method for molybdenum due the high selectivity of this agent. Nowadays, statistical analysis tools have been employed in analytical systems to prove its efficiency and feasibility. IPEN has a project aiming the production of {sup 99}Mo by the fission of {sup 235}U route. The processing uses as the first step the precipitation of {sup 99}Mo with {alpha}-Bz. This precipitation step involves many key reaction parameters. The aim of this work is based on the development of the already known acidic route to produce {sup 99}Mo as well as the optimization of the reactional parameters applying statistical tools. In order to simulate {sup 99}Mo precipitation, the study was conducted in acidic media using HNO{sub 3}, {alpha}Bz as precipitant agent and NaOH /1%H{sub 2}O{sub 2} as dissolver solution. Then, a Mo carrier, KMnO{sub 4} solutions and {sup 99}Mo tracer were added to the reaction flask. The reactional parameters ({alpha}-Bz/Mo ratio, Mo carrier, reaction time and temperature, and cooling reaction time before filtration) were evaluated under a fractional factorial design of resolution V. The best values of each reactional parameter were determined by a response surface statistical planning. The precipitation and recovery yields of {sup 99}Mo were measured using HPGe detector. Statistical analysis from experimental data suggested that the reactional parameters {alpha}-Bz/Mo ratio, reaction time and temperature have a significant impact on {sup 99}Mo precipitation. Optimization statistical planning showed that higher {alpha}Bz/Mo ratios, room temperature, and lower reaction time lead to higher {sup 99}Mo yields. (author)

  13. Differential susceptibility of PCR reactions to inhibitors: an important and unrecognised phenomenon

    Miller Robert F


    Full Text Available Abstract Background PCR inhibition by nucleic acid extracts is a well known yet poorly described phenomenon. Inhibition assessment generally depends on the assumption that inhibitors affect all PCR reactions to the same extent; i.e. that the reaction of interest and the control reaction are equally susceptible to inhibition. To test this assumption we performed inhibition assessment on DNA extracts from human urine samples, fresh urine and EDTA using different PCR reactions. Results When copurified inhibitors were assessed using two different PCR reactions one reaction appeared to be inhibited whilst the other was not. Further experiments using various concentrations of unextracted urine to inhibit six different PCR reactions revealed that susceptibility to inhibition was highly variable between reactions. Similar results were obtained using EDTA as the PCR inhibitor. We could find no obvious explanation why one reaction should be more susceptible to inhibition than another, although a possible association with amplicon GC content was noted. Conclusion These findings have serious implications for all PCR-based gene expression studies, including the relatively new PCR array method, and for both qualitative and quantitative PCR-based molecular diagnostic assays, suggesting that careful consideration should be given to inhibition compatibility when conducting PCR analyses. We have demonstrated unequivocally that it is not safe to assume that different PCR reactions are equally susceptible to inhibition by substances co-purified in nucleic acid extracts.

  14. Model reduction and parameter estimation of non-linear dynamical biochemical reaction networks.

    Sun, Xiaodian; Medvedovic, Mario


    Parameter estimation for high dimension complex dynamic system is a hot topic. However, the current statistical model and inference approach is known as a large p small n problem. How to reduce the dimension of the dynamic model and improve the accuracy of estimation is more important. To address this question, the authors take some known parameters and structure of system as priori knowledge and incorporate it into dynamic model. At the same time, they decompose the whole dynamic model into subset network modules, based on different modules, and then they apply different estimation approaches. This technique is called Rao-Blackwellised particle filters decomposition methods. To evaluate the performance of this method, the authors apply it to synthetic data generated from repressilator model and experimental data of the JAK-STAT pathway, but this method can be easily extended to large-scale cases.

  15. Prediction of changes in important physical parameters during composting of separated animal slurry solid fractions.

    Chowdhury, Md Albarune; de Neergaard, Andreas; Jensen, Lars Stoumann


    Solid-liquid separation of animal slurry, with solid fractions used for composting, has gained interest recently. However, efficient composting of separated animal slurry solid fractions (SSFs) requires a better understanding of the process dynamics in terms of important physical parameters and their interacting physical relationships in the composting matrix. Here we monitored moisture content, bulk density, particle density and air-filled porosity (AFP) during composting of SSF collected from four commercially available solid-liquid separators. Composting was performed in laboratory-scale reactors for 30 days (d) under forced aeration and measurements were conducted on the solid samples at the beginning of composting and at 10-d intervals during composting. The results suggest that differences in initial physical properties of SSF influence the development of compost maximum temperatures (40-70 degreeC). Depending on SSF, total wet mass and volume losses (expressed as % of initial value) were up to 37% and 34%, respectively. After 30 d of composting, relative losses of total solids varied from 17.9% to 21.7% and of volatile solids (VS) from 21.3% to 27.5%, depending on SSF. VS losses in all composts showed different dynamics as described by the first-order kinetic equation. The estimated component particle density of 1441 kg m-3 for VS and 2625 kg m-3 for fixed solids can be used to improve estimates of AFP for SSF within the range tested. The linear relationship between wet bulk density and AFP reported by previous researchers held true for SSF.

  16. The relative importance and interrelations between behavior parameters for robots' mood expression

    Xu, J.; Broekens, J.; Hindriks, K.; Neerincx, M.A.


    Bodily expression of affect is crucial to human robot interaction. Our work aims at designing bodily expression of mood that does not interrupt ongoing functional behaviors. We propose a behavior model containing specific (pose and motion) parameters that characterize the behavior. Parameter modulat

  17. The Importance of the Range Parameter for Estimation and Prediction in Geostatistics

    Kaufman, Cari


    Two canonical problems in geostatistics are estimating the parameters in a specified family of stochastic process models and predicting the process at new locations. A number of asymptotic results for these problems over a fixed spatial domain indicate that, for a Gaussian process with Mat\\'ern covariance function, one can fix the range parameter controlling the rate of decay of the process and obtain results that are asymptotically equivalent to the case that the range parameter is known. We discuss why these results do not always provide the appropriate intuition for finite samples. Moreover, we prove that a number of these asymptotic results may be extended to the case that the variance and range parameters are jointly estimated via maximum likelihood or maximum tapered likelihood. Our simulation results show that performance on a variety of metrics is improved and asymptotic approximations are applicable for smaller sample sizes when the range parameter is estimated. These effects are particularly apparen...

  18. Determination of thermodynamic parameters for enolization reaction of malonic and metylmalonic acids by using quartz crystal microbalance

    Minoru Yoshimoto


    Full Text Available We investigated the process of a bromination reaction of malonic acid and methylmalonic acid in the Belousov-Zhabotinsky reaction by using a quartz crystal microbalance (QCM. The process involves an enolization reaction as a rate-determining step. We found that, in the step, the variation of Br2 concentration induced an exactly quantitative shift of a resonant frequency of the QCM, based on the change of the surface mass on the QCM and the solution viscosity and density. This new finding enabled us to estimate the reaction rate constants and the thermodynamic parameters of the enolization reaction due to a QCM measurement. The values measured by the QCM were in good agreement with those measured by a UV-spectrophotometer. As a result, we succeeded to develop a new measurement method of a nonlinear chemical reaction.

  19. Reaction parameters for the synthesis of N,N-dimethyl fatty hydrazides from oil.

    Ahmad, Norashikin; Azizul Hasan, Zafarizal Aldrin; Hassan, Hazimah Abu; Ahmad, Mansor; Zin Wan Yunus, Wan Md


    Hydrazide derivatives have been synthesized from methyl esters, hydrazones and vegetable oils. They are important due to their diverse applications in pharmaceutical products, detergents as well as in oil and gas industries. The chemical synthesis of fatty hydrazides is well-established; however, only a few publications described the synthesis of fatty hydrazide derivatives, particularly, when produced from refined, bleached and deodorized palm olein. Here, the synthesis and characterization of N,N-dimethyl fatty hydrazides are reported. The N,N-dimethyl fatty hydrazides was successfully synthesized from fatty hydrazides and dimethyl sulfate in the presence of potassium hydroxide with the molar ratio of 1:1:1, 6 hours reaction time and 80℃ reaction temperature in ethanol. The product yield and purity were 22% and 89%, respectively. The fatty hydrazides used were synthesized from refined, bleached and deodorized palm olein with hydrazine monohydrate at pH 12 by enzymatic route. Fourier transform infrared, gas chromatography and nuclear magnetic resonance (NMR) spectroscopy techniques were used to determine the chemical composition of N,N-dimethyl fatty hydrazides. Proton NMR confirmed the product obtained were N,N-dimethyl fatty hydrazides.

  20. Use of Direct Dynamics Simulations to Determine Unimolecular Reaction Paths and Arrhenius Parameters for Large Molecules.

    Yang, Li; Sun, Rui; Hase, William L


    In a previous study (J. Chem. Phys.2008, 129, 094701) it was shown that for a large molecule, with a total energy much greater than its barrier for decomposition and whose vibrational modes are harmonic oscillators, the expressions for the classical Rice-Ramsperger-Kassel-Marcus (RRKM) (i.e., RRK) and classical transition-state theory (TST) rate constants become equivalent. Using this relationship, a molecule's unimolecular rate constants versus temperature may be determined from chemical dynamics simulations of microcanonical ensembles for the molecule at different total energies. The simulation identifies the molecule's unimolecular pathways and their Arrhenius parameters. In the work presented here, this approach is used to study the thermal decomposition of CH3-NH-CH═CH-CH3, an important constituent in the polymer of cross-linked epoxy resins. Direct dynamics simulations, at the MP2/6-31+G* level of theory, were used to investigate the decomposition of microcanonical ensembles for this molecule. The Arrhenius A and Ea parameters determined from the direct dynamics simulation are in very good agreement with the TST Arrhenius parameters for the MP2/6-31+G* potential energy surface. The simulation method applied here may be particularly useful for large molecules with a multitude of decomposition pathways and whose transition states may be difficult to determine and have structures that are not readily obvious.

  1. Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

    Kharab Rajesh


    Full Text Available We have investigated the relative importance of the energy dependence of diffuseness parameter and barrier position in the description of the fusion excitation function data of some heavy ion systems in near barrier energy region. The effects of the energy dependent diffuseness parameter are found to be much more prominent in comparison to those of barrier position.

  2. Differential effects of uninostril and alternate nostril pranayamas on cardiovascular parameters and reaction time

    Ananda Balayogi Bhavanani


    Full Text Available Background: Recent studies have reported the differential physiological and psychological effects of yogic uninostril breathing (UNB and alternate nostril breathing (ANB techniques. This study aims to determine differential effects of these techniques on reaction time (RT, heart rate (HR, and blood pressure (BP. Materials and Methods: Twenty yoga-trained subjects came to the lab on six different days and RT, HR, and BP were recorded randomly before and after nine rounds of right UNB (surya nadi [SN], left UNB (chandra nadi [CN], right initiated ANB (surya bhedana [SB], left initiated ANB (chandra bhedana [CB], nadi shuddhi (NS, and normal breathing (NB. Results: Overall comparison of ∆ % changes showed statistically significant differences between groups for all parameters. There was an overall reduction in HR- and BP-based parameters following CB, CN, and NS with concurrent increases following SB and SN. The differential effects of right nostril initiated (SB and SN and left nostril initiated (CB, CN, and NS UNB and ANB techniques were clearly evidenced. Changes following NB were insignificant in all respects. The overall comparison of ∆ % changes for RT showed statistically significant differences between groups that were significantly lowered following both SB and SN. Discussion and Conclusion: Our study provides evidence of sympathomimetic effects of right nostril initiated pranayamas with sympatholytic/parasympathomimetic effect following left nostril initiated pranayamas. We suggest that the main effect of UNB and ANB techniques is determined by the nostril used for inspiration rather than that used for expiration. We conclude that right and left yogic UNB and ANB techniques have differential physiological effects that are in tune with the traditional swara yoga concept that air flow through right nostril (SN and pingala swara is activatory in nature, whereas the flow through left nostril (CN and ida swara is relaxatory.

  3. Permeability as an important parameter for radon risk classification of foundation soils

    M. Neznal


    Full Text Available Permeability of soils and rocks for gases is one of the main parameters for final radon risk classification of building sites. For the improvement of the method for radon risk classification it is recommended to complete in situ measurements of permeability and/or results derived from grain size analysis by an expert description of parameters of soils and rocks and their changes in vertical profile.

  4. The importance of transport parameter cross correlations in natural systems radioactive transport models

    Reimus, Paul W [Los Alamos National Laboratory


    Transport parameter cross correlations are rarely considered in models used to predict radionuclide transport in natural systems. In this paper, it is shown that parameter cross correlations could have a significant impact on radionuclide transport predictions in saturated media. In fractured rock, the positive correlation between fracture apertures and groundwater residence times is shown to result in significantly less retardation due to matrix diffusion than is predicted without the correlation. The suppression of matrix diffusion is further amplified by a tendency toward larger apertures, smaller matrix diffusion coefficients, and less sorption capacity in rocks of lower matrix porosity. In a hypothetical example, strong cross correlations between these parameters result in a decrease in predicted radionuclide travel times of an order of magnitude or more relative to travel times calculated with uncorrelated parameters. In porous media, expected correlations between permeability, porosity, and sorption capacity also result in shorter predicted travel times than when the parameters are assumed to be uncorrelated. Individual parameter standard deviations can also have a significant influence on predicted radionuclide travel times, particularly when cross correlations are considered.

  5. Importance of fluctuations of cross sections in muon-catalysed t-t fusion reactions

    Kimura, S


    We discuss the reaction rate of the muon-catalysed $t$-$t$ fusion. The reaction rate is determined as a function of the temperature using the model of "in flight" fusion. We especially take into account the effect of the fluctuation of the cross section due to the existence of the muon. The obtained reaction rate 5.0$\\times10^{-3} \\mu$s$^{-1}$ is a factor of 10$^{-3}$ smaller than the experimental muonic cycling rate in the solid tritium target.

  6. Calculation of radiation reaction effect on orbital parameters in Kerr spacetime

    Sago, Norichika


    We calculate the secular changes of the orbital parameters of a point particle orbiting a Kerr black hole, due to the gravitational radiation reaction. For this purpose, we use the post-Newtonian (PN) approximation in the first order black hole perturbation theory, with the expansion with respect to the orbital eccentricity. In this work, the calculation is done up to the fourth post-Newtonian (4PN) order and to the sixth order of the eccentricity, including the effect of the absorption of gravitational waves by the black hole. We confirm that, in the Kerr case, the effect of the absorption appears at the 2.5PN order beyond the leading order in the secular change of the particle's energy and may induce a superradiance, as known previously for circular orbits. In addition, we find that the superradiance may be suppressed when the orbital plane inclines with respect to the equatorial plane of the central black hole. We also investigate the accuracy of the 4PN formulae by comparing to numerical results. If we re...

  7. Elucidation of inorganic reaction mechanisms in ionic liquids: the important role of solvent donor and acceptor properties.

    Schmeisser, Matthias; van Eldik, Rudi


    In this article, we focus on the important role of solvent donor and acceptor properties of ionic liquids in the elucidation of inorganic reaction mechanisms. For this purpose, mechanistic and structural studies on typical inorganic reactions, performed in ionic liquids, have been conducted. The presented systems range from simple complex-formation and ligand-substitution reactions to the activation of small molecules by catalytically active complexes. The data obtained for the reactions in ionic liquids are compared with those for the same reactions carried out in conventional solvents, and are discussed with respect to the donor and acceptor properties of the applied ionic liquids. The intention of this perspective is to gain more insight into the role of ILs as solvents and their interaction with metal ions and complexes in solution.




    A key element tied to using a code like MAAP4 is an uncertainty analysis. The purpose of this paper is to present a MAAP4 based analysis to examine the sensitivity of a key parameter, in this case hydrogen production, to a set of model parameters that are related to a Level 2 PRA analysis. The Level 2 analysis examines those sequences that result in core melting and subsequent reactor pressure vessel failure and its impact on the containment. This paper identifies individual contributors and MAAP4 model parameters that statistically influence hydrogen production. Hydrogen generation was chosen because of its direct relationship to oxidation. With greater oxidation, more heat is added to the core region and relocation (core slump should occur faster. This, in theory, would lead to shorter failure times and subsequent “hotter” debris pool on the containment floor.

  9. Sensitivity analysis of parameters important to nuclear criticality safety of Castor X/28F spent nuclear fuel cask

    Leotlela, Mosebetsi J. [Witwatersrand Univ., Johannesburg (South Africa). School of Physics; Koeberg Operating Unit, Johannesburg (South Africa). Regulations and Licensing; Malgas, Isaac [Koeberg Nuclear Power Station, Duinefontein (South Africa). Nuclear Engineering Analysis; Taviv, Eugene [ASARA consultants (PTY) LTD, Johannesburg (South Africa)


    In nuclear criticality safety analysis it is essential to ascertain how various components of the nuclear system will perform under certain conditions they may be subjected to, particularly if the components of the system are likely to be affected by environmental factors such as temperature, radiation or material composition. It is therefore prudent that a sensitivity analysis is performed to determine and quantify the response of the output to variation in any of the input parameters. In a fissile system, the output parameter of importance is the k{sub eff}. Therefore, in attempting to prevent reactivity-induced accidents, it is important for the criticality safety analyst to have a quantified degree of response for the neutron multiplication factor to perturbation in a given input parameter. This article will present the results of the perturbation of the parameters that are important to nuclear criticality safety analysis and their respective correlation equations for deriving the sensitivity coefficients.

  10. Important Physiological Parameters and Physical Activity Data for Evaluating Exposure Modeling Performance: a Synthesis

    The purpose of this report is to develop a database of physiological parameters needed for understanding and evaluating performance of the APEX and SHEDS exposure/intake dose rate model used by the Environmental Protection Agency (EPA) as part of its regulatory activities. The A...

  11. [Evaluation of imported Plasmodium falciparum malaria cases: the use of polymerase chain reaction in diagnosis].

    Demiraslan, Hayati; Erdoğan, Emrah; Türe, Zeynep; Kuk, Salih; Yazar, Süleyman; Metan, Gökhan


    Malaria affecting almost half of the world population continues to be an important health problem. Although domestic malaria cases have been decreasing in Turkey recently, cases caused by Plasmodium falciparum have increased due to the frequent travelling to Africa. The aims of this study were to evaluate demographic characteristics, clinical and laboratory findings in cases with falciparum malaria who attended to our clinic in 2012-2013 period, and the impact of polymerase chain reaction (PCR) for diagnosis. Nine patients evaluated were all male with a mean age of 34.3 (age range: 18-48) years, with the history of travel to Africa. Six cases did not take prophylaxis against malaria and other three cases used insufficient time. Mean duration of symptoms after return was 18.4 (range: 1-75) days, and the patients were admitted to the clinic within a mean of 5.2 (range: 1-15) days. Two patients had leucopenia, two patients had anemia, and eight patients had thrombocytopenia on admission. Alanine aminotransferase (ALT) levels in four cases and total bilirubin levels of six cases were over upper normal limits. Definitive diagnosis of cases was performed with the detection of ring and/or gametocytes forms of the parasite in Giemsa-stained peripheral blood smears. Furthermore, samples from seven patients were studied by nested PCR by using genus (Plasmodium rPLU 1 and 5) and species (rFAL 1 and 2, rVIV 1 and 2, rMAL 1 and 2, rOVA 1 and 2) specific primers. All of these seven samples yielded positive results with primers specific for P.falciparum ssrRNA. In the treatment, arthemeter/lumefantrin and doxycycline combination was used in seven patients, while intravenous artesunate and doxycycline combination was given to two patients, resulting with complete cure. Mean duration for the resolving of fever was 3.3 days, and mean duration for clearing the parasitemia from peripheral blood was 4.9 days. Initial ALT values and the duration of fever resolution (-796; p= 0.010), as

  12. Mathematical modeling of drying of potato slices in a forced convective dryer based on important parameters.

    Naderinezhad, Samira; Etesami, Nasrin; Poormalek Najafabady, Arefe; Ghasemi Falavarjani, Majid


    The effect of air temperature, air velocity, and sample shapes (circle and square with the same cross-sectional area) on kinetic drying of potato slices in a tunnel dryer was investigated experimentally and a suitable drying model was developed. The experiments of drying of potato slices were conducted at an air temperature of 45-70°C with an air velocity 1.60 and 1.81 m sec(-1). Results showed that drying temperature was the most effective parameter in the drying rate. The influence of air velocity was more profound in low temperature. The time for drying square slices was lower compared to the circle ones. Furthermore, drying data were fitted to different empirical models. Among the models, Midilli-Kucuk was the best to explain the single layer drying of potato slices. The parameters of this model were determined as functions of air velocity and temperature by multiple regression analysis for circle and square slices. Various statistical parameters were examined for evaluating the model.

  13. The importance of expression of uncertainty of acoustical parameters of ultrasonic phantoms

    Maggi, L E; Souza, A B B; Ichinose, R M; Pereira, W C A; Kruger, M A von [Programa de Engenharia Biomedica/COPPE - UFRJ, Rio de Janeiro (Brazil); Costa-Felix, R P B, E-mail: [Ultrasound Laboratory, Diavi/Dimci/Inmetro, Duque de Caxias, RJ (Brazil)


    The measurement of uncertainties in scientific experiments improves greatly quality and reliability of the results. However, in many cases, experimental results are only expressed by its average value and standard deviation. The longitudinal velocity and attenuation coefficient are acoustic parameters commonly used to characterize biological tissues and materials. In this work it is studied the uncertainty in experiments designed to evaluate these parameters on two different materials (silicone rubber and PVCP). The uncertainties were studied following the Guide to the Expression of Uncertainty in Measurement and calculated by a program in Labview8.6. One setup was developed to measure the acoustic parameters by a transmission/reception technique. Five signals of each medium (water and materials) were collected. The attenuation coefficient was calculated using the relation between the amplitude spectrum peak of the water signal and its respective point on the spectrum of the material signal. The longitudinal velocity was calculated using the time delay between signal peaks (from water and from the material). The individual uncertainties of each part of setup were estimated and these values permitted to identify which were the sources of uncertainty that most contributed to increase the value of associated uncertainty. It permitted to improve experiment's quality and reliability.

  14. Use of neuropathological tissue for molecular genetic studies: parameters affecting DNA extraction and polymerase chain reaction.

    Kösel, S; Graeber, M B


    Nuclear and mitochondrial DNA were extracted from gray matter of human cerebral cortex which had either been formalin-fixed and embedded into paraffin or stored in formalin for up to 26 years. Extraction conditions were optimized for proteinase K digestion, i.e., enzyme concentration, digestion temperature and incubation time. Using the polymerase chain reaction (PCR), DNA was successfully amplified from archival material and sequenced employing a direct nonradioactive cycle sequencing protocol. In general, tissue embedded into paraffin following brief fixation in formalin gave good quantitative results, i.e., up to 1 microgram DNA/mg tissue were extracted. This yield was at least one order of magnitude higher than that obtained with tissue stored in formalin. However, paraffin-embedded neuropathological material was found to contain an as-yet-unidentified PCR inhibitor, and a deleterious effect of long-term fixation in unbuffered low-grade formalin was clearly detectable. Importantly, both paraffin-embedded tissue blocks and human brain that had been stored in formalin for many years yielded DNA sufficient for qualitative analysis. The implications of these findings for the use of neuropathological material in molecular genetic studies are discussed.

  15. Cofactors in allergic reactions to food : physical exercise and alcohol are the most important

    Versluis, Astrid; van Os-Medendorp, Harmieke; Kruizinga, Astrid G; Blom, W Marty; Houben, Geert F; Knulst, André C


    INTRODUCTION: Involvement of cofactors, like physical exercise, alcohol consumption and use of several types of medication, are associated with more severe food allergic symptoms. However, there is limited evidence on how often cofactors play a role in food allergic reactions. The study aimed to get

  16. Fuzzy Logic Water Quality Index and Importance of Water Quality Parameters

    Raman Bai. V


    Full Text Available Determination of status of water quality of a river or any other water sources is highly indeterminate. It is necessary to have a competent model to predict the status of water quality and to advice for type of water treatment for meeting different demands. One such model (UNIQ2007 is developed as an application software in water quality engineering. The unit operates in a fuzzy logic mode including a fuzzification engine receiving a plurality of input variables on its input and being adapted to compute membership function parameters. A processor engine connected downstream of the fuzzification unit will produce fuzzy set, based on fuzzy variable viz. DO, BOD, COD, AN, SS and pH. It has a defuzzification unit operative to translate the inference results into a discrete crisp value of WQI. The UNIQ2007 contains a first memory device connected to the fuzzification unit and containing the set of membership functions, a secondary memory device connected to the defuzzification unit and containing the set of crisp value which appear in the THEN part of the fuzzy rules and an additional memory device connected to the defuzzification unit. More advantageously, UINQ2007 is constructed with control elements having dynamic fuzzy logic properties wherein target non-linearity can be input to result in a perfect evaluation of water quality. The development of the fuzzy model with one river system is explained in this paper. Further the model has been evaluated with the data from few rivers in Malaysia, India and Thailand. This water quality assessor probe can provide better quality index or identify the status of river with 90% perfection. Presently, WQI in most of the countries is referring to physic-chemical parameters only due to great efforts needed to quantify the biological parameters. This study ensures a better method to include pathogens into WQI due to superior capabilities of fuzzy logic in dealing with non-linear, complex and uncertain systems.

  17. Pole tide Love number - an important parameter for polar motion modeling

    Kirschner, S.; Schmidt, M. G.; Seitz, F.


    The Euler-Liouville equation is the basic physical model to describe Earth rotation. It is based on the balance of angular momentum in the Earth system. The pole tide Love number is needed to characterize the rotational deformation effect, which depends on the internal structure and rheology of the Earth. There is a direct dependency between the pole tide Love number and the period and damping of the Chandler oscillation. Here we estimate the pole tide Love number on the basis of an inversion of the Euler-Liouville equation. The Earth orientation parameters are used as input parameters. They have been observed precisely over several decades by geodetic methods (C01 and C04 time series). It will be shown that the estimated pole tide Love number leads to significantly better results for polar motion compared to the original value taken from the Conventions of the International Earth Rotation and Reference System Service (IERS). Nevertheless the estimation is dependent on the input models for the subsystems (e.g. atmosphere and ocean models), applied estimation approach and time frame. These aspects are analyzed and discussed in detail.

  18. Importance of composite parameters in enhanced power conversion efficiency of Terfenol-D/PZT magnetoelectric gyrators

    Leung, Chung Ming; Zhuang, Xin; Xu, Junran; Li, Jiefang; Srinivasan, G.; Viehland, D.


    A gyrator that is capable of current-to-voltage conversion can be realized with a magnetoelectric (ME) composite of ferromagnetic and ferroelectric phases placed in a coil. Here, we report the dependence of the power conversion efficiency (PE) on the relative thickness of the two ferroic phases in a gyrator of Terfenol-D and PZT. Both experimental and theoretical results on PE as a function of composite parameters, such as thickness ratio of the ferroic layers (n), magnetic field bias (HBias) and several gyrator parameters, such as the resistance load (RL), were discussed. By decreasing the thickness ratio of Terfenol-D to composite (n = 0.28) in coil-ME gyrators, a high power efficiency of 73.9% was found at a fundamental resonance frequency of 72.5 kHz under a HBias of 1000 Oe and RL = 2.6 kΩ in experiments. At the same time, the non-linear mechanical loss was reduced by decreasing the value of n which resulted in a flat response over a wide HBias range. This improved power efficiency promises ME gyrators for power transfer devices.

  19. [Correction of autonomic reactions parameters in organism of cosmonaut with adaptive biocontrol method

    Kornilova, L. N.; Cowings, P. S.; Toscano, W. B.; Arlashchenko, N. I.; Korneev, D. Iu; Ponomarenko, A. V.; Salagovich, S. V.; Sarantseva, A. V.; Kozlovskaia, I. B.


    Presented are results of testing the method of adaptive biocontrol during preflight training of cosmonauts. Within the MIR-25 crew, a high level of controllability of the autonomous reactions was characteristic of Flight Commanders MIR-23 and MIR-25 and flight Engineer MIR-23, while Flight Engineer MIR-25 displayed a weak intricate dependence of these reactions on the depth of relaxation or strain.

  20. Adaptively biased sequential importance sampling for rare events in reaction networks with comparison to exact solutions from finite buffer dCME method.

    Cao, Youfang; Liang, Jie


    Critical events that occur rarely in biological processes are of great importance, but are challenging to study using Monte Carlo simulation. By introducing biases to reaction selection and reaction rates, weighted stochastic simulation algorithms based on importance sampling allow rare events to be sampled more effectively. However, existing methods do not address the important issue of barrier crossing, which often arises from multistable networks and systems with complex probability landscape. In addition, the proliferation of parameters and the associated computing cost pose significant problems. Here we introduce a general theoretical framework for obtaining optimized biases in sampling individual reactions for estimating probabilities of rare events. We further describe a practical algorithm called adaptively biased sequential importance sampling (ABSIS) method for efficient probability estimation. By adopting a look-ahead strategy and by enumerating short paths from the current state, we estimate the reaction-specific and state-specific forward and backward moving probabilities of the system, which are then used to bias reaction selections. The ABSIS algorithm can automatically detect barrier-crossing regions, and can adjust bias adaptively at different steps of the sampling process, with bias determined by the outcome of exhaustively generated short paths. In addition, there are only two bias parameters to be determined, regardless of the number of the reactions and the complexity of the network. We have applied the ABSIS method to four biochemical networks: the birth-death process, the reversible isomerization, the bistable Schlögl model, and the enzymatic futile cycle model. For comparison, we have also applied the finite buffer discrete chemical master equation (dCME) method recently developed to obtain exact numerical solutions of the underlying discrete chemical master equations of these problems. This allows us to assess sampling results objectively

  1. Importance of $1n$-stripping process in the $^{6}$Li+$^{159}$Tb reaction

    Pradhan, M K; Roy, Subinit; Basu, P; Goswami, A; Kshetri, R; Palit, R; Parkar, V V; Ray, M; Sarkar, M Saha; Santra, S


    The inclusive cross sections of the $\\alpha$-particles produced in the reaction $^{6}$Li+$^{159}$Tb have been measured at energies around the Coulomb barrier. The measured cross sections are found to be orders of magnitude larger than the calculated cross sections of $^{6}$Li breaking into $\\alpha$ and $d$ fragments, thus indicating contributions from other processes. The experimental cross sections of $1n$-stripping and $1n$-pickup processes have been determined from an entirely different measurement, reported earlier. Apart from incomplete fusion and/ $d$-transfer processes, the $1n$-stripping process is found to be a significant contributor to the inclusive $\\alpha$-particle cross sections in this reaction.

  2. Hidden but important parameters in Ga{sub 0.5}In{sub 0.5}P cell growth

    Kurtz, S.R.; Olson, J.M.; Bertness, K.A. [National Renewable Energy Lab., Golden, CO (United States)] [and others


    Despite their best intentions, authors often omit from publications many important technical details. These omissions can lead to contradictions in the literature and inhibit {open_quotes}researchers{close_quotes} abilities to duplicate published results. Here, the authors explore {open_quote}hidden{close_quote} parameters that are usually not reported, either because they are unknown (e.g., impurity levels) or because they are considered to be of little importance. Specifically the authors focus on the effects - and how to reduce the effects - of growth parameters in nearby layers (diffusion), impurities (oxygen), and the cooldown atmosphere (hydrogen passivation).

  3. Hypochlorous acid-mediated protein oxidation: how important are chloramine transfer reactions and protein tertiary structure?

    Pattison, David I; Hawkins, Clare L; Davies, Michael J


    Hypochlorous acid (HOCl) is a powerful oxidant generated from H2O2 and Cl- by the heme enzyme myeloperoxidase, which is released from activated leukocytes. HOCl possesses potent antibacterial properties, but excessive production can lead to host tissue damage that occurs in numerous human pathologies. As proteins and amino acids are highly abundant in vivo and react rapidly with HOCl, they are likely to be major targets for HOCl. In this study, two small globular proteins, lysozyme and insulin, have been oxidized with increasing excesses of HOCl to determine whether the pattern of HOCl-mediated amino acid consumption is consistent with reported kinetic data for isolated amino acids and model compounds. Identical experiments have been carried out with mixtures of N-acetyl amino acids (to prevent reaction at the alpha-amino groups) that mimic the protein composition to examine the role of protein structure on reactivity. The results indicate that tertiary structure facilitates secondary chlorine transfer reactions of chloramines formed on His and Lys side chains. In light of these data, second-order rate constants for reactions of Lys side chain and Gly chloramines with Trp side chains and disulfide bonds have been determined, together with those for further oxidation of Met sulfoxide by HOCl and His side chain chloramines. Computational kinetic models incorporating these additional rate constants closely predict the experimentally observed amino acid consumption. These studies provide insight into the roles of chloramine formation and three-dimensional structure on the reactions of HOCl with isolated proteins and demonstrate that kinetic models can predict the outcome of HOCl-mediated protein oxidation.

  4. Structural, spectroscopic and energetic parameters of P-bearing species having astrophysical importance

    Kevin Gooniah


    Full Text Available Molecular parameters such as equilibrium structure, dipole moment, rotational constant, harmonic frequency, IR intensity, adiabatic electron affinity, atomisation energy and ionisation potential of some P-bearing molecules PS, PO and HC3P in their neutral, cationic and anionic forms were investigated using the popular B3LYP hybrid density functional with four basis sets 6-311++G(2df,2pd, 6-311++G(3df,3pd, cc-pVTZ and aug-cc-pVTZ. The computed data conform well to those existing in the literature. Therefore, the predicted data for those molecules or ions which are not available in the literature should be reliable.

  5. [The importance of choline and different serum parameters for the course of the anorexia nervosa].

    Wöckel, L; Bertsch, T; Koch, S; Achtnichts, L; Holtmann, M; Gretz, N; Schmidt, M H; Poustka, F


    Malnutrition in anorexia nervosa was simulated in an animal starvation study. Female rats aged 11 to 13 weeks received a hypocaloric standard diet or a hypocaloric choline reduced diet. Weight reduction lasted for 12 to 20 weeks and was between 30 % to 40 % of initial weight. Several animals were refed after weight reduction up to 6 to 12 weeks with a standard or a choline enriched diet ad libitum. Serum parameters and membrane fluidity of the CNS were measured after weight reduction or after refeeding. Weight reduction leads to a significant decrease of serum protein, triglycerides (Z = -3.53 resp. -3.42; p brain and consequently for the course of anorexia nervosa. We furthermore hypothesize that choline enriched nutrition after starvation improves the stabilization of cerebral membranes and the metabolic situation in anorexia nervosa.

  6. The importance of risk-aversion as a measurable psychological parameter governing risk-taking behaviour

    Thomas, P. J.


    A utility function with risk-aversion as its sole parameter is developed and used to examine the well-known psychological phenomenon, whereby risk averse people adopt behavioural strategies that are extreme and apparently highly risky. The pioneering work of the psychologist, John W. Atkinson, is revisited, and utility theory is used to extend his mathematical model. His explanation of the psychology involved is improved by regarding risk-aversion not as a discrete variable with three possible states: risk averse, risk neutral and risk confident, but as continuous and covering a large range. A probability distribution is derived, the "motivational density", to describe the process of selecting tasks of different degrees of difficulty. An assessment is then made of practicable methods for measuring risk-aversion.

  7. Effects of Solid-State Reaction Synthesis Processing Parameters on Thermoelectric Properties of Mg2Si

    JIANG Hong-yi; LONG Hai-shan; ZHANG Lian-meng


    The Mg2Si-matrix thermoelectric material was synthesized by low temperature solid-state reaction.This paper studies the effects of holding time and reaction temperature on the particle size and the properties of the material,and also studies effects of doping elemental Sb,Te and their doping seqence on the properties of the material.The result shows that excessively high temperature and elongated holding time of solid-state reaction are harmful,there is a range of particle size to ensure optimum properties and the doping sequence of Sb or Te without influencing the properties.

  8. [Heart current density as the most important biological parameter of electrocution in the bathtub].

    Fechner, G; Brinkmann, B; Heckmann, M


    The most important factor during electrocution in a bathtub is the amount of current flowing through a body, not the amount of voltage. A method of measurement is introduced which--under simulation of various electrical situations--provides the possibility to measure the current flowing through the heart and to determine it's direction and density in the tissue. Hereby a ranking of the different factors influencing electrocution can be set up.

  9. Importance of viscosity parameters in electrospinning: Of monolithic and core-shell fibers

    Tiwari, Sandeep Kumar, E-mail:; Venkatraman, Subbu S.


    Electrospun polymeric fibers are attractive candidates in the development of scaffolds for the tissue engineering and for providing new systems for delivery of bioactive molecules. Co-axial fibers have emerged as an efficient tool to protect the core material from the adverse conditions of electrospinning process, to spin difficult-to-process fluids and to generate fibers with much more control of the delivery of encapsulated bioactive molecules. Currently, there is very little reported work on the optimization of the processing parameters of electrospinning, especially core-shell electrospinning. This study extends the understanding of the role of solution viscosity as a vital material parameter for electrospinning of fibers. The spinning solutions were characterized for viscosity and optical imaging of the compound Taylor cone for spinnability, and the fibers were imaged by Scanning Electron Microscopy (SEM). Our experimental results, using PLGA as the model polymer, confirm that the solution concentration be above the entanglement concentration (C{sub e}) to obtain uniform beadless monolithic fibers; for core-shell fibers, the shell solution must fulfill the above criterion for spinnability and, further, the ratio of the viscosities of core and shell solutions ({eta}{sub core}/{eta}{sub shell}) has to be greater than a threshold value to get a stable compound Taylor cone and therefore to obtain uniform beadless core-shell fibers. Addition of surfactant led to reduction of the threshold {eta}{sub core}/{eta}{sub shell} (from 0.55 to 0.18) for the PVA-PLGA system. - Graphical abstract: A workable range of {eta}{sub core}/{eta}{sub shell} values exists for co-electrospinning in addition to other viscosity requirements for electrospinning of core and shell solutions. Highlights: Black-Right-Pointing-Pointer To produce uniform beadless fibers, the concentration of the polymer solution must be above entanglement concentration (C{sub e}). Black

  10. Important parameters affecting the cell voltage of aqueous electrical double-layer capacitors

    Wu, Tzu-Ho; Hsu, Chun-Tsung; Hu, Chi-Chang; Hardwick, Laurence J.


    This study discusses and demonstrates how the open-circuit potential and charges stored in the working potential window on positive and negative electrodes affect the cell voltage of carbon-based electrical double-layer capacitors (EDLCs) in aqueous electrolytes. An EDLC consisting of two activated carbon electrodes is employed as the model system for identifying these key parameters although the potential window of water decomposition can be simply determined by voltammetric methods. First, the capacitive performances of an EDLC with the same charge on positive and negative electrodes are evaluated by cyclic voltammetric, charge-discharge, electrochemical impedance spectroscopic (EIS) analyses, and inductance-capacitance-resistance meter (LCR meter). The principles for obtaining the highest acceptable cell voltage of such symmetric ECs with excellent reversibility and capacitor-like behaviour are proposed. Aqueous charge-balanced EDLCs can be operated as high as 2.0 V with high energy efficiency (about 90%) and only 4% capacitance loss after the 600-cycle stability checking. The necessity of charge balance (but not capacitance balance) for positive and negative electrodes is substantiated from the lower acceptable cell voltage of charge-unbalanced EDLCs.

  11. Uncertainty evaluation of nuclear reaction model parameters using integral and microscopic measurements. Covariances evaluation with CONRAD code

    Tommasi J.


    Full Text Available In the [eV;MeV] energy range, modelling of the neutron induced reactions are based on nuclear reaction models having parameters. Estimation of co-variances on cross sections or on nuclear reaction model parameters is a recurrent puzzle in nuclear data evaluation. Major breakthroughs were asked by nuclear reactor physicists to assess proper uncertainties to be used in applications. In this paper, mathematical methods developped in the CONRAD code[2] will be presented to explain the treatment of all type of uncertainties, including experimental ones (statistical and systematic and propagate them to nuclear reaction model parameters or cross sections. Marginalization procedure will thus be exposed using analytical or Monte-Carlo solutions. Furthermore, one major drawback found by reactor physicist is the fact that integral or analytical experiments (reactor mock-up or simple integral experiment, e.g. ICSBEP, … were not taken into account sufficiently soon in the evaluation process to remove discrepancies. In this paper, we will describe a mathematical framework to take into account properly this kind of information.

  12. Tensor methods for parameter estimation and bifurcation analysis of stochastic reaction networks.

    Liao, Shuohao; Vejchodský, Tomáš; Erban, Radek


    Stochastic modelling of gene regulatory networks provides an indispensable tool for understanding how random events at the molecular level influence cellular functions. A common challenge of stochastic models is to calibrate a large number of model parameters against the experimental data. Another difficulty is to study how the behaviour of a stochastic model depends on its parameters, i.e. whether a change in model parameters can lead to a significant qualitative change in model behaviour (bifurcation). In this paper, tensor-structured parametric analysis (TPA) is developed to address these computational challenges. It is based on recently proposed low-parametric tensor-structured representations of classical matrices and vectors. This approach enables simultaneous computation of the model properties for all parameter values within a parameter space. The TPA is illustrated by studying the parameter estimation, robustness, sensitivity and bifurcation structure in stochastic models of biochemical networks. A Matlab implementation of the TPA is available at

  13. Spray granulation: importance of process parameters on in vitro and in vivo behavior of dried nanosuspensions.

    Figueroa, Carlos E; Bose, Sonali


    The use of fluid bed granulation for drying of pharmaceutical nanoparticulates on micron-sized granule substrates is a relatively new technique, with limited understanding in the current literature of the effects of process parameters on the physical properties of the dried nanoparticle powders. This work evaluated the effects of spray mode, spray rate and atomizing pressure for spray granulation of drug nanosuspensions through a systematic study. Naproxen and a proprietary Novartis compound were converted into nanosuspensions through wet media milling and dried onto a mannitol based substrate using spray granulation. For naproxen, various physical properties of the granules, as well as the in vitro re-dispersion and dissolution characteristics of the nano-crystals, were measured. It was found that the spray mode had the most drastic effect, where top spray yielded smaller re-dispersed particle sizes and faster release rates of drug from granules than bottom spray. This was attributed to the co-current spraying in bottom spray resulting in denser, homogenous films on the substrate. Similar in vitro results were obtained for the proprietary molecule, Compound A. In vivo studies in beagle dogs with Compound A showed no significant difference between the liquid and the dried forms of the nanosuspension in terms of overall AUC, differences were observed in the tmax which correlated with the rank ordering observed from the in vitro dissolution profiles. These findings make spray granulation amenable to the production of powders with desired processing and handling properties, without compromising the overall exposure of the compound under investigation. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Fundamental study on photodynamic therapy for atrial fibrillation: effect of photosensitization reaction parameters on myocardial necrosis in vitro

    Ogawa, Emiyu; Ito, Arisa; Arai, Tsunenori


    We studied necrotic cell death effect on myocardial cells with photosensitizer existed outside the cells varying photosensitization reaction parameters widely in vitro. We have developed non-thermal ablator with the application of photosensitization reaction for atrial fibrillation. Since laser irradiation is applied shortly after photosensitizer injection, the photosensitization reaction is induced outside the cells. The interaction for the myocardial cells by the photosensitization reaction is not well understood yet on various photosensitization reaction parameters. Rat myocardial cells were cultured in 96 well plates for 7 days. The photosensitization reaction was applied with talaporfin sodium (NPe6) and the semiconductor laser of 663nm wavelength. The average drug light interval was set 8 mins. The photosensitizer concentration and radiant exposure were varied from 5 to 40 μg/ml and 1.2 to 60 J/cm2, respectively. The well bottom was irradiated by the red laser with irradiance of 293 mW/cm2. The photosensitizer fluorescence was monitored during the photosensitization reaction. Alive cell rate was measured by WST assay after 2 hours from the irradiation. In the case of the photosensitizer concentration of 10 μg/ml, the myocardial cells were almost alive even thought 60 J/cm2 in the radiant exposure was applied. In the 15 μg/ml case, the alive cell rate was almost linear relation to the photosensitizer concentration and radiant exposure. We obtained that the threshold for myocardial cell necrosis on the photosensitizer concentration was around 15 μg/ml with 20 J/cm2 in the radiant exposure. This threshold on the photosensitizer concentration was similar to the reported threshold for cancer therapy.

  15. Heritability, phenotypic and genotypic correlations of Peanut bud necrosis virus (PBNV reaction parameters in peanut

    Aran Patanothai


    Full Text Available Peanut bud necrosis disease (PBND caused by Peanut bud necrosis virus (PBNV is an important disease of peanut (Arachis hypogaea L. in Thailand especially during the dry season. Host plant resistance is one of the effective methods to control the disease. The objectives of this study were to estimate broad sense heritability and to evaluate phenotypic and genotypic correlation between PBND score and PBND incidence in the F4 generation of 10 crosses of peanut. A randomized complete block design with 4 replications was used for testing the mentioned F3 families in F4 generation at two locations in Kalasin province in the Northeast of Thailand. Characters under study were PBND score and PBND incidence (percent infected plants evaluated at 30, 40, 50, 60, 70, and 90 days after sowing (DAS. The 50 and 60 day data are reported herein. There were significant differences among crosses for PBND score and PBND incidence. Means for PBND score and PBND incidence of resistant x susceptible group were intermediate between resistant x resistant group and susceptible x susceptible one. ICGV 86388 x IC 34 and IC 10 x KK 4 had lower PBND score and PBND incidence than the other crosses. Heritability estimates for PBND score and PBND incidence evaluated at 50 and 60 DAS were moderate to high, ranging from 0.27 to 0.90, revealing that families that had low PBND score and PBND incidence could be readily identified in the F4 generation. Phenotypic and genotypic correlations between PBND score and PBND incidence were closely associated, indicating that single parameter evaluation is sufficient. PBND incidence is more suitable than PBND score because of its simplicity.

  16. The importance of direct patient reporting of suspected adverse drug reactions: a patient perspective

    Anderson, Claire; Krska, Janet; Murphy, Elizabeth; Avery, Anthony


    .... WHAT THIS STUDY ADDS • Direct patient reporting through the Yellow Card Scheme is viewed as important by those who have used the scheme, in order to provide the patient experience for the benefit of pharmacovigilance...

  17. Crucial ignored parameters on nanotoxicology: the importance of toxicity assay modifications and "cell vision".

    Sophie Laurent

    Full Text Available Until now, the results of nanotoxicology research have shown that the interactions between nanoparticles (NPs and cells are remarkably complex. In order to get a deep understanding of the NP-cell interactions, scientists have focused on the physicochemical effects. However, there are still considerable debates about the regulation of nanomaterials and the reported results are usually in contradictions. Here, we are going to introduce the potential key reasons for these conflicts. In this case, modification of conventional in vitro toxicity assays, is one of the crucial ignored matter in nanotoxicological sciences. More specifically, the conventional methods neglect important factors such as the sedimentation of NPs and absorption of proteins and other essential biomolecules onto the surface of NPs. Another ignored matter in nanotoxicological sciences is the effect of cell "vision" (i.e., cell type. In order to show the effects of these ignored subjects, we probed the effect of superparamagnetic iron oxide NPs (SPIONs, with various surface chemistries, on various cell lines. We found thatthe modification of conventional toxicity assays and the consideration of the "cell vision" concept are crucial matters to obtain reliable, and reproducible nanotoxicology data. These new concepts offer a suitable way to obtain a deep understanding on the cell-NP interactions. In addition, by consideration of these ignored factors, the conflict of future toxicological reports would be significantly decreased.

  18. Assessing the importance of demographic parameters for population dynamics using Bayesian integrated population modeling.

    Eacker, Daniel R; Lukacs, Paul M; Proffitt, Kelly M; Hebblewhite, Mark


    To successfully respond to changing habitat, climate or harvest, managers need to identify the most effective strategies to reverse population trends of declining species and/or manage harvest of game species. A classic approach in conservation biology for the last two decades has been the use of matrix population models to determine the most important vital rates affecting population growth rate (λ), that is, sensitivity. Ecologists quickly realized the critical role of environmental variability in vital rates affecting λ by developing approaches such as life-stage simulation analysis (LSA) that account for both sensitivity and variability of a vital rate. These LSA methods used matrix-population modeling and Monte Carlo simulation methods, but faced challenges in integrating data from different sources, disentangling process and sampling variation, and in their flexibility. Here, we developed a Bayesian integrated population model (IPM) for two populations of a large herbivore, elk (Cervus canadensis) in Montana, USA. We then extended the IPM to evaluate sensitivity in a Bayesian framework. We integrated known-fate survival data from radio-marked adults and juveniles, fecundity data, and population counts in a hierarchical population model that explicitly accounted for process and sampling variance. Next, we tested the prevailing paradigm in large herbivore population ecology that juvenile survival of neonates modeling in a Bayesian framework can provide multiple advantages. Our Bayesian LSA framework will provide a useful approach to addressing conservation challenges across a variety of species and data types. © 2017 by the Ecological Society of America.

  19. The Importance of Materials Data and Modelling Parameters in an FE Simulation of Linear Friction Welding

    R. Turner


    Full Text Available Linear friction welding has become a key technology in the aeroengine industry due to its capability to produce blisk components. Finite element (FE simulation of linear friction welding applications has been studied in recent years by a number of institutions, using a variety of software codes. Several codes have been demonstrated to be capable of predicting with reasonable accuracy some or all of the critical outputs of friction welding, namely, the thermal loading, plastic deformation, and residual stresses generated. The importance of reliable material data in performing these calculations is paramount. Available material data in the published literature is often restricted to lower temperatures and strain rate regimes. Extrapolation methods used on this data to estimate high temperature properties can lead to uncertainties in the modelled predictions. This paper reviews the approach to materials modelling, including material datasets and material constitutive laws, for FE simulation work in the literature regarding linear friction welding. Best-practice methods for materials constitutive laws, materials data-sets, and the associated experimental temperatures and strain rates used to gather data are suggested. Finally, successfully validated modelled outcomes—when a robust, reliable, and accurate material database has been selected—are demonstrated for a number of the FE methods considered.

  20. Selection effects in identifying magnetic clouds and the importance of the closest approach parameter

    R. P. Lepping


    Full Text Available This study is motivated by the unusually low number of magnetic clouds (MCs that are strictly identified within interplanetary coronal mass ejections (ICMEs, as observed at 1 AU; this is usually estimated to be around 30% or lower. But a looser definition of MCs may significantly increase this percentage. Another motivation is the unexpected shape of the occurrence distribution of the observers' "closest approach distances" (measured from a MC's axis, and called CA which drops off somewhat rapidly as |CA| (in % of MC radius approaches 100%, based on earlier studies. We suggest, for various geometrical and physical reasons, that the |CA|-distribution should be somewhere between a uniform one and the one actually observed, and therefore the 30% estimate should be higher. So we ask, When there is a failure to identify a MC within an ICME, is it occasionally due to a large |CA| passage, making MC identification more difficult, i.e., is it due to an event selection effect? In attempting to answer this question we examine WIND data to obtain an accurate distribution of the number of MCs vs. |CA| distance, whether the event is ICME-related or not, where initially a large number of cases (N=98 are considered. This gives a frequence distribution that is far from uniform, confirming earlier studies. This along with the fact that there are many ICME identification-parameters that do not depend on |CA| suggest that, indeed an MC event selection effect may explain at least part of the low ratio of (No. MCs/(No. ICMEs. We also show that there is an acceptable geometrical and physical consistency in the relationships for both average "normalized" magnetic field intensity change and field direction change vs. |CA| within a MC, suggesting that our estimates of |CA|, BO (magnetic field intensity on the axis, and choice of a proper "cloud coordinate" system (all needed in the analysis are acceptably accurate. Therefore, the MC

  1. Froude Number is the Single Most Important Hydraulic Parameter for Salmonid Spawning Habitat.

    Gillies, E.; Moir, H. J.


    Many gravel-bed rivers exhibit historic straightening or embanking, reducing river complexity and the available habitat for key species such as salmon. A defensible method for predicting salmonid spawning habitat is an important tool for anyone engaged in assessing a river restoration. Most empirical methods to predict spawning habitat use lookup tables of depth, velocity and substrate. However, natural site selection is different: salmon must pick a location where they can successfully build a redd, and where eggs have a sufficient survival rate. Also, using dimensional variables, such as depth and velocity, is problematic: spawning occurs in rivers of differing size, depth and velocity range. Non-dimensional variables have proven useful in other branches of fluid dynamics, and instream habitat is no different. Empirical river data has a high correlation between observed salmon redds and Froude number, without insight into why. Here we present a physics based model of spawning and bedform evolution, which shows that Froude number is indeed a rational choice for characterizing the bedform, substrate, and flow necessary for spawning. It is familiar for Froude to characterize surface waves, but Froude also characterizes longitudinal bedform in a mobile bed river. We postulate that these bedforms and their hydraulics perform two roles in salmonid spawning: allowing transport of clasts during redd building, and oxygenating eggs. We present an example of this Froude number and substrate based habitat characterization on a Scottish river for which we have detailed topography at several stages during river restoration and subsequent evolution of natural processes. We show changes to the channel Froude regime as a result of natural process and validate habitat predictions against redds observed during 2014 and 2015 spawning seasons, also relating this data to the Froude regime in other, nearby, rivers. We discuss the use of the Froude spectrum in providing an indicator of

  2. Developing principles for predicting ionic liquid effects on reaction outcome. The importance of the anion in controlling microscopic interactions.

    Keaveney, Sinead T; Haines, Ronald S; Harper, Jason B


    A series of ionic liquids containing anions of differing coordination strength were investigated as solvents for the condensation reaction of an alkyl amine and an aromatic aldehyde. As predicted, the rate constant of the process was found to increase with the proportion of the ionic liquid in the reaction mixture. Temperature-dependent kinetic analyses demonstrated that by varying the ability of the anion to interact with the cation the magnitude of both the enthalpy and entropy of activation could be controlled in a predictable manner, with the activation parameters being linearly dependent on the ionic liquid basicity. Interestingly, the unexpected trend in the rate constants observed when altering the anion of the ionic liquid highlighted the presence of more subtle secondary microscopic interactions involving the anion, further emphasizing the fragility of the enthalpy - entropy balance.

  3. Statistical values of valence electron structure parameters applied to research on phase transition temperature and eutectoid reaction of titanium alloy


    Based on the empirical electron theory of solids and molecules (EET), the statisti- cal values of valence electron structure parameters SnA and SEA which can char- acterize the properties of alloy phases are calculated, and influences of alloying elements (e.g., V, Nb, Mo, Hf, Zr, Fe, Mn, Co, Cr, Si, and so on) on the phase transi- tion temperature and eutectoid reaction of titanium alloy are discussed with the statistical values of valence electron structure parameters. The research results agree well with real situations.

  4. New Measurements of the Astrophysically Important ^44Ti Radionuclide Through the ^40Ca(α,γ)^44Ti Reaction

    Robertson, Daniel; Becker, Hans-Werner; Collon, Philippe; Goerres, Joachim; Wiescher, Michael


    The relatively short-lived radionuclide ^44Ti (t1/2=58.9 ± 0.3 yrs), is of considerable importance in the study of nucleosynthesis in explosive stellar environments. It's production predominantly through the ^40Ca(α,γ)^44Ti reaction, takes place during α-rich freeze-out, in the inner most layers of a core-collapse supernova. A number of experimental studies have been previously performed to determine the stellar reaction rate. These studies included prompt γ-ray measurements from in-beam experiments, atom counting techniques utilizing accelerator mass spectrometry (AMS) and multi energy step measurements at the DRAGON recoil mass separator. The resulting calculated reaction rates show drastic disagreement. New results from experiments at the DTL, Bochum and NSL, Notre Dame, used both gamma spectroscopy and AMS techniques to measure the reaction, and investigate the discrepancies in both the experimental and predicted results. Final results of the experiments and their impact on the reaction rate will be discussed.

  5. Evaluation of reaction mechanisms and the kinetic parameters for the transesterification of castor oil by liquid enzymes

    Andrade, Thalles Allan; Errico, Massimiliano; Christensen, Knud Villy


    The use of liquid enzymes for the production of biodiesel as an alternative to chemical catalysts requires significant investigation due to the lack of experimental data for the various feedstock and catalyst combinations. In this paper, reaction rates and kinetic modeling...... of the transesterification of castor oil with methanol using the enzyme Eversa® Transform as catalyst were investigated. Reactions were carried out for 8 hours at 35 °C with: an alcohol-to-oil molar ratio equal to 6:1, a 5 wt% of liquid enzyme solution and addition of 5 wt% of water by weight of castor oil. From...... methanolysis rates of glycerides obtained, indicated that transesterification dominates over hydrolysis. The mechanism among the four models proposed that gave the best fit could be simplified, eliminating the kinetic parameters with negligible effects on the reaction rates. This model was able to fit...

  6. Heterogeneous reduction of PuO₂ with Fe(II): importance of the Fe(III) reaction product.

    Felmy, Andrew R; Moore, Dean A; Rosso, Kevin M; Qafoku, Odeta; Rai, Dhanpat; Buck, Edgar C; Ilton, Eugene S


    Heterogeneous reduction of actinides in higher, more soluble oxidation states to lower, more insoluble oxidation states by reductants such as Fe(II) has been the subject of intensive study for more than two decades. However, Fe(II)-induced reduction of sparingly soluble Pu(IV) to the more soluble lower oxidation state Pu(III) has been much less studied, even though such reactions can potentially increase the mobility of Pu in the subsurface. Thermodynamic calculations are presented that show how differences in the free energy of various possible solid-phase Fe(III) reaction products can greatly influence aqueous Pu(III) concentrations resulting from reduction of PuO₂(am) by Fe(II). We present the first experimental evidence that reduction of PuO₂(am) to Pu(III) by Fe(II) was enhanced when the Fe(III) mineral goethite was spiked into the reaction. The effect of goethite on reduction of Pu(IV) was demonstrated by measuring the time dependence of total aqueous Pu concentration, its oxidation state, and system pe/pH. We also re-evaluated established protocols for determining Pu(III) {[Pu(III) + Pu(IV)] - Pu(IV)} by using thenoyltrifluoroacetone (TTA) in toluene extractions; the study showed that it is important to eliminate dissolved oxygen from the TTA solutions for accurate determinations. More broadly, this study highlights the importance of the Fe(III) reaction product in actinide reduction rate and extent by Fe(II).

  7. Irregular response of nanofluid flow subject to chemical reaction and shape parameter in the presence of variable stream conditions

    R. Kandasamy


    Full Text Available The problem of boundary layer of nanofluid flow which results from the stretching of a flat surface has been investigated numerically. The model includes the effects of Brownian motion, magnetic effect, non-linear velocity, variable thickness, thermophoresis, chemical reaction, porous medium, shape, thickness and heat source. The Partial differential equations are converted to ordinary deferential equations to solve analytically using shooting technique. The velocity, temperature and concentration profiles are discussed in detail for all parameters.

  8. Rate parameters for the reaction of atomic hydrogen with dimethyl ether and dimethyl sulfide

    Lee, J. H.; Machen, R. C.; Nava, D. F.; Stief, L. J.


    Absolute rate constants for the reaction of atomic hydrogen with dimethyl ether (DME) and dimethyl sulfide (DMS) were obtained using the flash photolysis-resonance fluorescence technique. Under conditions where secondary reactions are avoided, rate constants for the H+DME reaction over the temperature range 273-426 K are well represented by the Arrhenius expression k1=(4.38±0.59)×10-12 exp(-1956±43/T) cm3 molecule-1 s-1. The corresponding Arrhenius expression for the H+DMS reaction over the temperature range 212-500 K is k2=(1.30±0.43)×10-11exp(-1118±81/T) cm3 molecule-1 s-1. The Arrhenius plot for k2 shows signs of curvature, however, and separate Arrhenius expressions are derived for the data above and below room temperature. These results are discussed and comparisons are made with previous determinations which employed flow discharge and product analysis techniques.

  9. Food avoidance in children with adverse food reactions: Influence of anxiety and clinical parameters

    Le, T.M.; Zijlstra, W.T.; Opstal, E.Y. van; Knol, M.J.; L'Hoir, M.P.; Knulst, A.C.; Pasmans, S.G.M.A.


    Background: Many children in the general population avoid food because of self-reported adverse food reactions (AFR). Food avoidance can have negative consequences for well-being and nutritional status. This study aimed to investigate which factors are related to avoidance behavior in children (10-1

  10. Immobilization of denatured DNA to macroporous supports: II. Steric and kinetic parameters of heterogeneous hybridization reactions.

    Bünemann, H


    The accessibility of immobilized DNA has been shown to depend more crucially on the method of immobilization than on the type of support used for fixation. When sonicated denatured DNA is coupled via diazotization or via cyanogen bromide reaction to solid Sephadex G-25 and Cellex 410 or to macroporous Sephacryl S-500 and Sepharose C1-6B its accessibility varies from 100 to 24 percent. Generally the loss of accessibility is linked to a depression of the melting temperature of DNA helices formed on the support. This correlation shows a characteristic course for a particular coupling method. DNA coupled under denaturing conditions may become totally inaccessible when only 3 percent of its bases are involved in the covalent linkage. Kinetic experiments with sonicated E.coli DNA have shown that the rate constants for renaturation or hybridization reactions are very similar for DNA immobilized by different methods to solid or macroporous supports. Generally the second order rate constant for a heterogeneous reaction (between mobile and immobilized DNA) is about one order of magnitude smaller than that of the analogous homogeneous reaction (in solution).

  11. Modelling and simulation of a transketolase mediated reaction: Sensitivity analysis of kinetic parameters

    Sayar, N.A.; Chen, B.H.; Lye, G.J.


    In this paper we have used a proposed mathematical model, describing the carbon-carbon bond format ion reaction between beta-hydroxypyruvate and glycolaldehyde to synthesise L-erythrulose, catalysed by the enzyme transketolase, for the analysis of the sensitivity of the process to its kinetic par....... (C) 2009 Elsevier B.V. All rights reserved....

  12. Polymerase Chain Reaction: An Important Tool for Early Diagnosis of Leptospirosis Cases

    Mullan, Summaiya


    Introduction Various diagnostic methods like Microscopic Agglutination Test (MAT), IgM ELISA, Isolation of Leptospira from the clinical specimen, Rapid leptocheck tests etc., are available for diagnosis of leptospirosis. Polymerase Chain Reaction (PCR) is used for diagnosis of various diseases of infectious origin including leptospirosis but there is paucity of data about comparison of PCR with other available method of diagnosis of leptospirosis. Aim The aim of the study was to detect the leptospiral DNA by PCR method and to compare the results of PCR with other available diagnostic methods used for diagnosis of suspected leptospirosis cases in acute phase of illness. Materials and Methods A total of 207 blood samples were obtained from suspected patients of leptospirosis admitted in New Civil Hospital, a tertiary care hospital in South Gujarat, during the period of July 2008 to November 2008. These blood samples were subjected to Rapid leptocheck, IgM ELISA, MAT test to detect (IgG or IgM) antibody level, Leptospira culture and PCR. Results In early phase of the disease, Rapid leptocheck test gave 44% detection, but along with PCR seropositivity reached upto 71%. Detection rate by IgM ELISA was 59% which increased to 80% with PCR. By MAT seropositivity was 57% but combined seropositivity of MAT with PCR was 78%. Sensitivity and specificity of PCR as compared to MAT (Gold standard) was 52% and 79% respectively. Leptospira was not growing in culture. Conclusion In present study, PCR picked up to 50% of cases which were negative by other serological tests so these finding suggest that PCR should be used routinely in acute phase of disease.

  13. [Correlation between clinical parameters and quantitative analysis of inflammatory infiltrate. Importance in the diagnosis of active periodontal disease].

    Mendieta Fiter, C


    Recent studies have indicated that the destruction in chronic periodontal disease occurs in relatively short periods of time which are followed of prolonged periods of inactivity. These bursts of activity are characterized by an increase in the inflammatory reaction. It has been the purpose of this paper to study the correlation between the clinical measurements of periodontal disease and the histomorphometric quantification of areas of dense inflammatory infiltrate. The results of this study show that the clinical parameters that measure gingival inflammation or loss of periodontal attachment are useful to distinguish pathology from normal (p less than 0.003), but lack sensitivity to detect burst of periodontal disease activity (p greater than 0.05).

  14. Mechanism and stereoselectivity of biologically important oxygenation reactions of the 7-dehydrocholesterol radical.

    Rajeev, Ramanan; Sunoj, Raghavan B


    The mechanism of free radical oxygenation of 7-dehydrocholesterol (7-DHC), one of the biologically important sterols, is investigated by using density functional theory. The energetic origin of the product distribution and the stereoelectronic factors involved in various mechanistic pathways are delineated. The addition of triplet molecular oxygen to two types of conjugatively stabilized radicals, generated by the removal of the reactive allylic hydrogens from C9 or C14 positions, respectively denoted as H9 and H14 pathways, is studied. The distortion-interaction analysis of the C-O bond formation transition states suggests that the energetic preference toward the α prochiral face stems from reduced skeletal distortions of the cholesterol backbone as compared to that in the corresponding β prochiral face. This insight derived through a detailed quantitative analysis of the stereocontrolling transition states suggests that the commonly found interpretations solely based on steric interactions between the incoming oxygen and the protruding angular methyl groups (C10, C13 methyls) in the β face calls for adequate refinement. The relative energies of the transition states for molecular oxygen addition to C9, C5, and C14 (where spin densities are higher) and the ensuing products thereof are in agreement with the experimentally reported distribution of oxygenated 7-DHCs.

  15. Immobilization of denatured DNA to macroporous supports: II. Steric and kinetic parameters of heterogeneous hybridization reactions.

    Bünemann, H


    The accessibility of immobilized DNA has been shown to depend more crucially on the method of immobilization than on the type of support used for fixation. When sonicated denatured DNA is coupled via diazotization or via cyanogen bromide reaction to solid Sephadex G-25 and Cellex 410 or to macroporous Sephacryl S-500 and Sepharose C1-6B its accessibility varies from 100 to 24 percent. Generally the loss of accessibility is linked to a depression of the melting temperature of DNA helices forme...

  16. Energy dependence of deformation parameters in the SC(p,p') SC reaction

    Jones, K.W.; Glashausser, C.; de Swiniarski, R.; Nanda, S.; Carey, T.A.; Cornelius, W.; Moss, J.M.; McClelland, J.B.; Comfort, J.R.; Escudie, J.


    Values of deformation parameters have been extracted from macroscopic coupled-channels analyses of inelastic proton scattering to the first 2 , 3 , and 4 states of SC over the energy range from 200 to 700 MeV. The apparent deformations are almost unchanged over this energy interval; they agree also with nucleon scattering data at much lower energies and at 800 MeV and 1 GeV.

  17. Heterogeneous Reduction of PuO2 with Fe(II): Importance of the Fe(III) Reaction Product

    Felmy, Andrew R.; Moore, Dean A.; Rosso, Kevin M.; Qafoku, Odeta; Rai, Dhanpat; Buck, Edgar C.; Ilton, Eugene S.


    Abstract Heterogeneous reduction of actinides in higher and more soluble oxidation states to lower more insoluble oxidation states by reductants such as Fe(II) has been the subject of intensive study for more than two decades. However, Fe(II)-induced reduction of sparingly soluble Pu(IV) to the more soluble lower oxidation state Pu(III) has been much less studied even though such reactions can potentially increase the mobility of Pu in the subsurface. Thermodynamic calculations are presented that show how differences in the free energy of various possible solid-phase Fe(III) reaction products can greatly influence aqueous Pu(III) concentrations resulting from reduction of PuO2(am) by Fe(II). We present the first experimental evidence that reduction of PuO2(am) to Pu(III) by Fe(II) was enhanced when the Fe(III) mineral goethite was spiked into the reaction. The effect of goethite on reduction of Pu(IV) was demonstrated by measuring the time-dependence of total aqueous Pu concentration, its oxidation state, and system pe/pH. We also re-evaluated established protocols for determining Pu(III) [(Pu(III) + Pu(IV)) - Pu(IV)] by using thenoyltrifluoroacetone (TTA) in toluene extractions; the study showed that it is important to eliminate dissolved oxygen from the TTA solutions for accurate determinations. More broadly, this study highlights the importance of the Fe(III) reaction product in actinide reduction rate and extent by Fe(II).

  18. Study of reaction parameters and kinetics of esterification of lauric acid with butanol by immobilized Candida antarctica lipase.

    Shankar, Sini; Agarwal, Madhu; Chaurasia, S P


    Esterification of lauric acid with n-butanol, catalyzed by immobilized Candida antarctica lipase (CAL) in aqueous-organic biphasic solvent system was studied. Effects of various reaction parameters on esterification were investigated, such as type and amount of solvent, amount of buffer, pH, temperature, speed of agitation, amount of enzyme, butanol and lauric acid. The most suitable reaction conditions for esterification were observed at 50 degrees C and pH 7.0 using 5000 micromoles of lauric acid, 7000 pmoles of butanol, 0.25 ml phosphate buffer, 1 ml of isooctane as the solvent and 50 mg of immobilized enzyme in the reaction medium at agitation speed of 150 rpm. Maximum esterification of 96.36% was acheived in 600 min of reaction time at n-butanol to lauric acid molar ratio of 1: 0.7. Kinetic study for the esterification of lauric acid with n-butanol using immobilized CAL was carried out and the kinetic constants were estimated by using non-linear regression method. The estimated value of Michaelis kinetic constants for butanol (KmBt) and acid (KmAc) were 451.56 (M) and 4.7 x 10(-7)(M), respectively and the value of dissociation constant (KBt) of the butanol-lipase complex was 9.41 x 10(7)(M). The estimated constants agreed fairly well with literature data.

  19. Evaluation of the kinetic and thermodynamic parameters of oxidation reaction in biodiesel from a quaternary mixture of raw material

    Karina Gomes Angilelli


    Full Text Available A mixture of vegetable oil and animal fat as raw materials was optimized by simplex-centroid mixture design to produce a type of biodiesel with good oxidative stability, flow properties and reaction yield. Further, kinetic and thermodynamic parameters of oxidation reaction were determined by the accelerated method at different temperatures. Biodiesel produced with sodium methoxide as catalyst presented 6.5°C of cloud point, 2.0°C of pour point, and oxidative stability at 110°C equal to 8.98h, with a reaction yield of 96.04%. Activation energy of the oxidation reaction was 81.03 kJ mol-1 for biodiesel produced with sodium hydroxide and 90.51 kJ mol-1 for sodium methoxide. The positive values for DH‡ and DG‡ indicate that the oxidation process is endothermic and endergonic. The less negative DS‡ for biodiesel produced with sodium methoxide (-28.87 JK-1 mol-1 showed that the process of degradation of this biofuel was slower than that produced with NaOH. The mixture of raw materials proposed, transesterified with the methoxide catalyst, resulted in a biofuel that resisted oxidation for longer periods, making unnecessary the addition of antioxidant

  20. Microwave assisted synthesis of guar gum grafted sodium acrylate/cloisite superabsorbent nanocomposites: reaction parameters and swelling characteristics.

    Likhitha, M; Sailaja, R R N; Priyambika, V S; Ravibabu, M V


    In this study, superabsorbent nanocomposites of guar gum grafted sodium acrylate have been synthesized via both microwave and conventional techniques. The reaction parameters of both techniques were optimized and the microwave assisted method was proved to have higher grafting yield with lesser time of reaction as compared to the conventional method. X-ray diffraction and scanning electron microscopy analyses revealed that cloisite was exfoliated and uniformly dispersed in guar gum grafted sodium acrylate matrix. The results show that introducing cloisite into the guar gum grafted sodium acrylate network improved the swelling capability and the swelling rate of the superabsorbent nanocomposite was found to be enhanced at an optimal loading of 10% cloisite. The nanocomposites showed high water absorbency within a wide pH range. Preliminary studies on crystal violet dye removal showed promising results.

  1. A study of practical parameters and their relative importance as perceived by various stakeholders in clinical trials.

    Pant, R; Joshi, Y


    A contract research organization (CRO) is a company which conducts a Good Clinical Practice (GCP) in clinical trial. There are literally hundreds of CROs worldwide employing a workforce of nearly 100,000 professionals. The project proposes the study of practical parameters and their relative importance as perceived by the various stakeholders in clinical trials. The survey was conducted in Bangalore and New Delhi. Primary market data was obtained by primary market research which included 80 clinical trial stakeholders by having a preliminary communication with them, followed by administering a questionnaire along with prior permission. There were 15 Sponsors/ CROs, 27 Investigators /Monitors and 38 Ethics committee members involved in the study. It was shown from the study that a clinical investigator involved in a clinical trial is responsible for ensuring that an investigation is conducted according to the signed investigator statement, the investigational plan, and applicable regulations; for protecting the rights, safety, and welfare of the subjects under the investigator's care; and for the control of drugs under investigation. It was also shown from the study that the sponsors of a clinical trial carry the ultimate responsibility for the initiation, management and financing of the clinical trial. The study has identified a specific training need at the level of the individual stakeholder to perform a particular job function and to identify the actual practical parameters in the Indian context important for the conduction of clinical trials (GCP) with respect to the different stakeholders, to determine the relative importance of these parameters as perceived by various stakeholders involved in clinical trials, and to identify the relative contributions of different stakeholders to the success/ satisfactory conduct of a clinical trial.

  2. Kinetic parameters of oscillating reaction of amino acid-BrO-3-Mn2+-H2SO4-acetone system

    LI Zongxiao; YUAN Chunlan; NIE Fei


    The oscillating behavior of thirteen amino acids [leucine (Leu), threonine (Thr), arginine (Arg), lysine (Lys), histidine (His), alanine (Ala), glutamine (Glu), glycine (Gly), methionine (Met), cystine (Cys), tryptophan (Trp), serine (Ser) and tyrosine (Tyr)] in amino acid--Mn2+-H2SO4-acetone system is studied by using a potentiometric determination. With the help of the oscillatory induction period and oscillation period obtained by the oscillating wave, and Arrhenius equation, the kinetic parameters [the apparent activation energy (E) and pre-exponential constant (A)] and rate constant (k) of the above-mentioned oscillating reaction are estimated.

  3. Assessing the importance of conduit geometry and physical parameters in karst systems using the storm water management model (SWMM)

    Peterson, Eric W.; Wicks, Carol M.


    SummaryQuestions about the importance of conduit geometry and about the values of hydraulic parameters in controlling ground-water flow and solute transport through karstic aquifers have remained largely speculative. One goal of this project was to assess the role that the conduit geometry and the hydraulic parameters have on controlling transport dynamics within karstic aquifers. The storm water management model (SWMM) was applied to the Devil's Icebox-Connor's Cave System in central Missouri, USA. Simulations with incremental changes to conduit geometry or hydraulic parameters were performed with the output compared to a calibrated baseline model. Ten percent changes in the length or width of a conduit produced statistically significant different fluid flow responses. The model exhibited minimal sensitivity to slope and infiltration rates; however, slight changes in Manning's roughness coefficient can highly alter the simulated output. Traditionally, the difference in flow dynamics between karstified aquifers and porous media aquifers has led to the idea that modeling of karst aquifers is more difficult and less precise than modeling of porous media aquifers. When evaluated against models for porous media aquifers, SWMM produced results that were as accurate (10% error compared to basecase). In addition, SWMM has the advantage of providing data about local flow. While SWMM may be an appropriate modeling technique for some karstic aquifers, SWMM should not be viewed as a universal solution to modeling karst systems.

  4. Atlas of Relations Between Climatic Parameters and Distributions of Important Trees and Shrubs in North America - Alaska Species and Ecoregions

    Thompson, Robert S.; Anderson, Katherine H.; Strickland, Laura E.; Shafer, Sarah L.; Pelltier, Richard T.; Bartlein, Patrick J.


    Climate is the primary factor in controlling the continental-scale distribution of plant species, although the relations between climatic parameters and species' ranges is only now beginning to be quantified. Preceding volumes of this atlas explored the continental-scale relations between climatic parameters and the distributions of woody plant species across all of the continent of North America. This volume presents similar information for important woody species, groups of species, and ecoregions in more detail for the State of Alaska. For these analyses, we constructed a 25-kilometer equal-area grid of modern climatic and bioclimatic parameters for North America from instrumental weather records. We obtained a digital representation of the geographic distribution of each species or ecoregion, either from a published source or by digitizing the published distributions ourselves. The presence or absence of each species or ecoregion was then determined for each point on the 25-kilometer grid, thus providing a basis for comparison of the climatic data with the geographic distribution of each species or ecoregion. The relations between climate and these distributions are presented in graphical and tabular form.

  5. Coccidioidomycosis: adenosine deaminase levels, serologic parameters, culture results, and polymerase chain reaction testing in pleural fluid.

    Thompson, George R; Sharma, Shobha; Bays, Derek J; Pruitt, Rachel; Engelthaler, David M; Bowers, Jolene; Driebe, Elizabeth M; Davis, Michael; Libke, Robert; Cohen, Stuart H; Pappagianis, Demosthenes


    In a patient with positive serum serology for coccidioidomycosis, the differential diagnosis of concurrent pleural effusions can be challenging. We, therefore, sought to clarify the performance characteristics of biochemical, serologic, and nucleic-acid-based testing in an attempt to avoid invasive procedures. The utility of adenosine deaminase (ADA), coccidioidal serology, and polymerase chain reaction (PCR) in the evaluation of pleuropulmonary coccidioidomycosis has not been previously reported. Forty consecutive patients evaluated for pleuropulmonary coccidioidomycosis were included. Demographic data, pleural fluid values, culture results, and clinical diagnoses were obtained from patient chart review. ADA testing was performed by ARUP Laboratories, coccidioidal serologic testing was performed by the University of California-Davis coccidioidomycosis serology laboratory, and PCR testing was performed by the Translational Genomics Research Institute using a previously published methodology. Fifteen patients were diagnosed with pleuropulmonary coccidioidomycosis by European Organization for the Research and Treatment of Cancer/Mycoses Study Group criteria. Pleural fluid ADA concentrations were coccidioidomycosis were not elevated in this study. The sensitivity and specificity of coccidioidal serologic testing in nonserum samples remained high, but the clinical usefulness of PCR testing in pleural fluid was disappointing and was comparable to pleural fluid culture.

  6. The comparison of dairy performance and some reproductive parameters of holstein cows imported from Sweden and their Polish age mates

    Ewa Czerniawska-Piątkowska


    Full Text Available The general aim of the present work was to compare dairy performance and some reproductive parameters of Holstein-Friesian (HF cows imported from Sweden as an in-calf heifers, and their age mates in Poland. The animals were kept freely on the deep litter on the farm owned by Agro-company “Witkowo” and feeding was based on TMR (total mixed ration system during whole year. All ration’s ingredients (bulky feed, concentrate, miscellaneous additives were mixed and fed as all-mash. The feed ration depended from the physiological condition of a cow and it was composed of corn and grass ensilage, mash concentrate, crushed corn meal, brewer’s grains and beet pulp.Cows imported from Sweden as in-calf heifers obtained higher milk, fat and protein yield in both lactations comparing to home cows. Significant statistical differences were observed for kg of milk, kg of protein, for FCM (P<0.01 and for kg of fat (P<0.05 in 2nd lactation. Fat and protein content in milk was in average higher for home cows (P<0.01. Big differences (P<0.01 were observed in SBT (proportion of protein to fat content and RTB (difference between concentration of fat and protein at imported cows in 2nd lactation. As far as reproduction parameters (gestation interval, calving interval, insemination index are concerned was cows from Sweden better too. Heifers from Sweden calved earlier. The usage of high genetic potential of imported cows is possible only with providing them optimum living conditions suitable to their needs.

  7. Caffeic Acid Phenethyl Ester Loaded PLGA Nanoparticles: Effect of Various Process Parameters on Reaction Yield, Encapsulation Efficiency, and Particle Size

    Serap Derman


    Full Text Available CAPE loaded PLGA nanoparticles were prepared using the oil in water (o/w single emulsion solvent evaporation methods. Five different processing parameters including initial CAPE amount, initial PLGA amount, PVA concentration in aqueous phase, PVA volume, and solvent type were screened systematically to improve encapsulation of hydrophobic CAPE molecule, simultaneously minimize particle size, and raise the reaction yield. Obtained results showed that the encapsulation efficiency of the nanoparticles significantly increased with the increase of the initial CAPE amount (p<0.05 and particle size (p<0.05. Furthermore, the particle size is significantly influenced by initial polymer amount (p<0.05 and surfactant concentration (p<0.05. By the optimization of process parameters, the nanoparticles produced 70±6% reaction yield, 89±3% encapsulation efficiency, -34.4±2.5 mV zeta potential, and 163±2 nm particle size with low polydispersity index 0.119±0.002. The particle size and surface morphology of optimized nanoparticles were studied and analyses showed that the nanoparticles have uniform size distribution, smooth surface, and spherical shape. Lyophilized nanoparticles with different CAPE and PLGA concentration in formulation were examined for in vitro release at physiological pH. Interestingly, the optimized nanoparticles showed a high (83.08% and sustained CAPE release (lasting for 16 days compared to nonoptimized nanoparticle.

  8. An individual and dynamic Body Segment Inertial Parameter validation method using ground reaction forces.

    Hansen, Clint; Venture, Gentiane; Rezzoug, Nasser; Gorce, Philippe; Isableu, Brice


    Over the last decades a variety of research has been conducted with the goal to improve the Body Segment Inertial Parameters (BSIP) estimations but to our knowledge a real validation has never been completely successful, because no ground truth is available. The aim of this paper is to propose a validation method for a BSIP identification method (IM) and to confirm the results by comparing them with recalculated contact forces using inverse dynamics to those obtained by a force plate. Furthermore, the results are compared with the recently proposed estimation method by Dumas et al. (2007). Additionally, the results are cross validated with a high velocity overarm throwing movement. Throughout conditions higher correlations, smaller metrics and smaller RMSE can be found for the proposed BSIP estimation (IM) which shows its advantage compared to recently proposed methods as of Dumas et al. (2007). The purpose of the paper is to validate an already proposed method and to show that this method can be of significant advantage compared to conventional methods.

  9. Lipase-catalyzed Synthesis of Caffeic Acid Phenethyl Ester in Ionic Liquids:Effect of Specific Ions and Reaction Parameters

    王俊; 李晶; 张磊霞; 顾双双; 吴福安


    Caffeic acid phenethyl ester (CAPE) is a rare, naturally occurring phenolic food additive. This work systematically reported fundamental data on conversion of caffeic acid (CA), yield of CAPE, and reactive selectiv-ity during the lipase-catalyzed esterification process of CA and phenylethanol (PE) in ionic liquids (ILs). Sixteen ILs were selected as the reaction media, and the relative lipase-catalyzed synthesis properties of CAPE were meas-ured in an effort to enhance the yield of CAPE with high selectivity. The results indicated that ILs containing weakly coordinating anions and cations with adequate alkyl chain length improved the synthesis of CAPE. [Emim][Tf2N] was selected as the optimal reaction media. The optimal parameters were as follows by response surface methodology (RSM):reaction temperature, 84.0 °C;mass ratio of Novozym 435 to CA, 14︰1;and molar ratio of PE to CA, 16︰1. The highest reactive selectivity of CAPE catalyzed by Novozym 435 in [Emim][Tf2N] reached 64.55%(CA conversion 98.76%and CAPE yield 63.75%, respectively). Thus, lipase-catalyzed esterifica-tion in ILs is a promising method suitable for CAPE production.

  10. The importance of social dimension and maturation stage for the probabilistic maturation reaction norm in Poecilia reticulata.

    Diaz Pauli, B; Pauli, B D; Heino, M


    Maturation is an important event in an organism's life history, with important implications on dynamics of both wild and captive populations. The probabilistic maturation reaction norm (PMRN) has emerged as an important method to describe variation in maturation in wild fish. Because most PMRNs are based on age and size only, it is important to understand limitations of these variables in explaining maturation. We experimentally assessed (i) the sensitivity of age- and size-based PMRNs to unaccounted sources of plasticity, (ii) the role of social environment on maturation and (iii) the significance of estimating PMRNs early and late in the maturation process (initiation and completion of maturation, respectively). We reared male guppies (Poecilia reticulata) under laboratory conditions, subjected to two food levels and three different social cues. We found that growth and social environment affected the maturation in a way that could not be accounted for by their effect on age and size. PMRNs estimated for the initiation stage were less plastic (growth differences and social cues influenced the PMRN shape only little) than those for completion. The initiation of maturation is probably closer to the maturation 'decision' and allows determining factors influencing maturation decision most accurately.

  11. Influence of experimental parameters on sonochemistry dosimetries: KI oxidation, Fricke reaction and H{sub 2}O{sub 2} production

    Merouani, Slimane [Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, University of Annaba, P.O. Box 12, 23000 Annaba (Algeria); Hamdaoui, Oualid, E-mail: [Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, University of Annaba, P.O. Box 12, 23000 Annaba (Algeria); Saoudi, Fethi; Chiha, Mahdi [Laboratory of Environmental Engineering, Department of Process Engineering, Faculty of Engineering, University of Annaba, P.O. Box 12, 23000 Annaba (Algeria)


    Central events of the ultrasonic action are the cavitation bubbles that can be considered as microreactors. Adiabatic collapse of cavitation bubbles leads to the formation of reactive species such as hydroxyl radicals ({center_dot}OH), hydrogen peroxide (H{sub 2}O{sub 2}) and hydroperoxyl radicals (HOO{center_dot}). Several chemical methods were used to detect the production of these reactive moieties in sonochemistry. In this work, the influence of several operational parameters on the sonochemistry dosimetries namely KI oxidation, Fricke reaction and H{sub 2}O{sub 2} production using 300 kHz ultrasound was investigated. The main experimental parameters showing significant effect in KI oxidation dosimetry were initial KI concentration, acoustic power and pH. The solution temperature showed restricted influence on KI oxidation. The acoustic power and liquid temperature highly affected Fricke reaction dosimetry. Operational conditions having important influence on H{sub 2}O{sub 2} formation were acoustic power, solution temperature and pH. For the three tested dosimetries, the sonochemical efficiency was independent of liquid volume.

  12. Insights into solar photo-Fenton reaction parameters in the oxidation of a sanitary landfill leachate at lab-scale.

    Silva, Tânia F C V; Ferreira, Rui; Soares, Petrick A; Manenti, Diego R; Fonseca, Amélia; Saraiva, Isabel; Boaventura, Rui A R; Vilar, Vítor J P


    This work evaluates the effect of the main photo-Fenton (PF) reaction variables on the treatment of a sanitary landfill leachate collected at the outlet of a leachate treatment plant, which includes aerated lagooning followed by aerated activated sludge and a final coagulation-flocculation step. The PF experiments were performed in a lab-scale compound parabolic collector (CPC) photoreactor using artificial solar radiation. The photocatalytic reaction rate was determined while varying the total dissolved iron concentration (20-100 mg Fe(2+)/L), solution pH (2.0-3.6), operating temperature (10-50 °C), type of acid used for acidification (H2SO4, HCl and H2SO4 + HCl) and UV irradiance (22-68 W/m(2)). This work also tries to elucidate the role of ferric hydroxides, ferric sulphate and ferric chloride species, by taking advantage of ferric speciation diagrams, in the efficiency of the PF reaction when applied to leachate oxidation. The molar fraction of the most photoactive ferric species, FeOH(2+), was linearly correlated with the PF pseudo-first order kinetic constants obtained at different solution pH and temperature values. Ferric ion speciation diagrams also showed that the presence of high amounts of chloride ions negatively affected the PF reaction, due to the decrease of ferric ions solubility and scavenging of hydroxyl radicals for chlorine radical formation. The increment of the PF reaction rates with temperature was mainly associated with the increase of the molar fraction of FeOH(2+). The optimal parameters for the photo-Fenton reaction were: pH = 2.8 (acidification agent: H2SO4); T = 30 °C; [Fe(2+)] = 60 mg/L and UV irradiance = 44 WUV/m(2), achieving 72% mineralization after 25 kJUV/L of accumulated UV energy and 149 mM of H2O2 consumed.

  13. Study on Lattice Parameter Variance and Eutectic Reaction during Crystal Growth of Nd,Cr∶GSGG by Czochralksi Method


    During the crystal growth of Nd, Cr∶GSGG by Czochralski method, in some cases eutectic reaction occurred in the nether region of the crystal, and the boule was divided into two obvious different parts, which is upper Nd,Cr∶GSGG crystal and the nether coexisting Nd,Cr∶GSGG and GdScO3. By X-ray powder diffraction, the structure change of NdCr∶GSGG crystal of Φ 27 mm×120 mm with eutectic along its grown direction was studied. By the least square method and extrapolation function f=sinθ-sinθ1-t(t is an adjustable parameter), the lattice parameters of Nd,Cr∶GSGG and additional GdScO3 phase were computed. The results indicate that the lattice parameters of Nd,Cr∶GSGG increase along its growth direction, which changes from a=(1.25650±0.00007) nm of the top to (1.25798±0.00010) nm of the bottom. In the process of Nd,Cr∶GSGG growth, Gd3+ in Nd,Cr∶GSGG is partly replaced by Nd3+ with larger ionic radii, and the volatilization of Ga component results in its composition variance, which cause the lattice parameters increase along growth direction. In the eutectic section, there are the Nd,Cr∶GSGG and the second phase orthorhombic GdScO3. The lattice parameters of GdScO3 are a=0.5443±0.0007, b=0.5699±0.0005 and c=(0.7865±0.0009) nm, and that of Nd,Cr∶GSGG is (1.25798±0.00010) nm. In the final growth stage, excessive volatilization of Ga composition during the crystal growth causes the growth melt deflect of the Nd,Cr∶GSGG solid solution range seriously, and results in the eutectic reaction, and the outgrowth of Nd,Cr∶GSGG and GdScO3. So it is necessary to decrease the effect of gallium volatilization during the growth in order to avoid eutectic growth and obtain a high-quality Nd,Cr∶GSGG.

  14. Improved quantification of important beer quality parameters based on nonlinear calibration methods applied to FT-MIR spectra.

    Cernuda, Carlos; Lughofer, Edwin; Klein, Helmut; Forster, Clemens; Pawliczek, Marcin; Brandstetter, Markus


    During the production process of beer, it is of utmost importance to guarantee a high consistency of the beer quality. For instance, the bitterness is an essential quality parameter which has to be controlled within the specifications at the beginning of the production process in the unfermented beer (wort) as well as in final products such as beer and beer mix beverages. Nowadays, analytical techniques for quality control in beer production are mainly based on manual supervision, i.e., samples are taken from the process and analyzed in the laboratory. This typically requires significant lab technicians efforts for only a small fraction of samples to be analyzed, which leads to significant costs for beer breweries and companies. Fourier transform mid-infrared (FT-MIR) spectroscopy was used in combination with nonlinear multivariate calibration techniques to overcome (i) the time consuming off-line analyses in beer production and (ii) already known limitations of standard linear chemometric methods, like partial least squares (PLS), for important quality parameters Speers et al. (J I Brewing. 2003;109(3):229-235), Zhang et al. (J I Brewing. 2012;118(4):361-367) such as bitterness, citric acid, total acids, free amino nitrogen, final attenuation, or foam stability. The calibration models are established with enhanced nonlinear techniques based (i) on a new piece-wise linear version of PLS by employing fuzzy rules for local partitioning the latent variable space and (ii) on extensions of support vector regression variants (-PLSSVR and ν-PLSSVR), for overcoming high computation times in high-dimensional problems and time-intensive and inappropriate settings of the kernel parameters. Furthermore, we introduce a new model selection scheme based on bagged ensembles in order to improve robustness and thus predictive quality of the final models. The approaches are tested on real-world calibration data sets for wort and beer mix beverages, and successfully compared to

  15. Application of artificial neural networks and DFT-based parameters for prediction of reaction kinetics of ethylbenzene dehydrogenase

    Szaleniec, Maciej; Witko, Małgorzata; Tadeusiewicz, Ryszard; Goclon, Jakub


    Artificial neural networks (ANNs) are used for classification and prediction of enzymatic activity of ethylbenzene dehydrogenase from EbN1 Azoarcus sp. bacterium. Ethylbenzene dehydrogenase (EBDH) catalyzes stereo-specific oxidation of ethylbenzene and its derivates to alcohols, which find its application as building blocks in pharmaceutical industry. ANN systems are trained based on theoretical variables derived from Density Functional Theory (DFT) modeling, topological descriptors, and kinetic parameters measured with developed spectrophotometric assay. Obtained models exhibit high degree of accuracy (100% of correct classifications, correlation between predicted and experimental values of reaction rates on the 0.97 level). The applicability of ANNs is demonstrated as useful tool for the prediction of biochemical enzyme activity of new substrates basing only on quantum chemical calculations and simple structural characteristics. Multi Linear Regression and Molecular Field Analysis (MFA) are used in order to compare robustness of ANN and both classical and 3D-quantitative structure-activity relationship (QSAR) approaches.

  16. Autonomic reactions and peri-interventional alterations in body weight as potential supplementary outcome parameters for thromboembolic stroke in rats

    Michalski Dominik


    Full Text Available Abstract Background Since several neuroprotectives failed to reproduce promising preclinical results under clinical conditions, efforts emerged to implement clinically relevant endpoints in animal stroke studies. Thereby, insufficient attention was given on autonomic reactions due to experimental stroke, although clinical trials reported on high functional and prognostic impact. This study focused on autonomic consequences and body weight changes in a translational relevant stroke model and investigated interrelations to different outcome measurements. Methods Forty-eight rats underwent thromboembolic middle cerebral artery occlusion (MCAO while recording heart rate (HR and mean arterial pressure (MAP. After assessing early functional impairment (Menzies score, animals were assigned to control procedure or potentially neuroprotective treatment with normobaric (NBO or hyperbaric oxygen (HBO. Four or 24 hours after ischemia onset, functional impairment was re-assessed and FITC-albumin administered intravenously obtaining leakage-related blood–brain barrier (BBB impairment. Body weight was documented prior to MCAO and 4 or 24 hours after ischemia onset. Results During MCAO, HR was found to increase significantly while MAP decreased. The amount of changes in HR was positively correlated with early functional impairment (P = 0.001: Severely affected animals provided an increase of 15.2 compared to 0.8 beats/minute in rats with low impairment (P = 0.048. Regarding body weight, a decrease of 9.4% within 24 hours after MCAO occurred, but treatment-specific alterations showed no significant correlations with respective functional or BBB impairment. Conclusions Future studies should routinely include autonomic parameters to allow inter-group comparisons and better understanding of autonomic reactions due to experimental stroke. Prospectively, autonomic consequences might represent a useful outcome parameter enhancing the methodological spectrum

  17. An Investigation into the Impact of Reaction Temperature on Various Parameters during Torrefaction of Sugarcane Bagasse Relevant to Gasification

    Anthony Anukam


    Full Text Available Torrefaction of sugarcane bagasse was conducted in an electric muffle furnace at 200, 250, and 300°C in order to establish the impact of heat treatment temperature on various parameters and as a method to improve sugarcane bagasse characteristics for the purpose of gasification. The results show that weight loss of bagasse reduced as temperature of torrefaction increased due to excessive devolatilization. A reduced moisture and volatile matter content as well as improved calorific value were also achieved with increasing temperature of torrefaction. The torrefaction progress was again followed by elemental analysis of the material which showed the presence of C, H, and O in varying proportions depending on torrefaction temperature. The decrease in the weight percentages of O2 and H2 as torrefaction reaction temperature increased resulted in the accumulation of C in the solid product. The thermogravimetric analysis conducted established the maximum reactivity temperature of the torrefied material and revealed that the degradation of torrefied sugarcane bagasse was accelerated by thermal treatment of the material prior to analysis. Finally, the study established that torrefaction at 300°C led to a much more degraded material compared to the lower torrefaction reaction temperatures of 200 and 250°C, respectively.

  18. Experimental study of the astrophysically important 23Na(α ,p )26Mg and 23Na(α ,n )26Al reactions

    Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; Ayangeakaa, A. D.; Dickerson, C.; Hoffman, C. R.; Jiang, C. L.; Kay, B. P.; Lai, J.; Nusair, O.; Pardo, R. C.; Santiago-Gonzalez, D.; Talwar, R.; Ugalde, C.


    The 23Na(α ,p )26Mg and 23Na(α ,n )26Al reactions are important for our understanding of the 26Al abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α ,p )26Mg and the 23Na(α ,n )26Al reactions are in good agreement with previous experiments and with statistical-model calculations. The astrophysical reaction rate of the 23Na(α ,n )26Al reaction has been reevaluated and it was found to be larger than the recommended rate.

  19. Slow hydrogen atom transfer reactions of oxo- and hydroxo-vanadium compounds: the importance of intrinsic barriers.

    Waidmann, Christopher R; Zhou, Xin; Tsai, Erin A; Kaminsky, Werner; Hrovat, David A; Borden, Weston Thatcher; Mayer, James M


    Reactions are described that interconvert vanadium(IV) oxo-hydroxo complexes [V(IV)O(OH)(R(2)bpy)(2)]BF(4) (1a-c) and vanadium(V) dioxo complexes [V(V)O(2)(R(2)bpy)(2)]BF(4) (2a-c) [R(2)bpy = 4,4'-di-tert-butyl-2,2'-bipyridine ((t)Bu(2)bpy), a; 4,4'-dimethyl-2,2'-bipyridine (Me(2)bpy), b; 2,2'-bipyridine (bpy), c]. These are rare examples of pairs of isolated, sterically unencumbered, first-row metal-oxo/hydroxo complexes that differ by a hydrogen atom (H(+) + e(-)). The V(IV)-(t)Bu(2)bpy derivative 1a has a useful (1)H NMR spectrum, despite being paramagnetic. Complex 2a abstracts H(*) from organic substrates with weak O-H and C-H bonds, converting 2,6-(t)Bu(2)-4-MeO-C(6)H(2)OH (ArOH) and 2,2,6,6-tetramethyl-N-hydroxypiperidine (TEMPOH) to their corresponding radicals ArO(*) and TEMPO, hydroquinone to benzoquinone, and dihydroanthracene to anthracene. The equilibrium constant for 2a + ArOH 1a + ArO(*) is (4 +/- 2) x 10(-3), implying that the VO-H bond dissociation free energy (BDFE) is 70.6 +/- 1.2 kcal mol(-1). Consistent with this value, 1a is oxidized by 2,4,6-(t)Bu(3)C(6)H(2)O(*). All of these reactions are surprisingly slow, typically occurring over hours at ambient temperatures. The net hydrogen-atom pseudo-self-exchange 1a + 2b 2a + 1b, using the (t)Bu- and Me-bpy substituents as labels, also occurs slowly, with k(se) = 1.3 x 10(-2) M(-1) s(-1) at 298 K, DeltaH(double dagger) = 15 +/- 2 kcal mol(-1), and DeltaS(double dagger) = 16 +/- 5 cal mol(-1) K. Using this k(se) and the BDFE, the vanadium reactions are shown to follow the Marcus cross relation moderately well, with calculated rate constants within 10(2) of the observed values. The vanadium self-exchange reaction is ca. 10(6) slower than that for the related Ru(IV)O(py)(bpy)(2)(2+)/Ru(III)OH(py)(bpy)(2)(2+) self-exchange. The origin of this dramatic difference has been probed with DFT calculations on the self-exchange reactions of 1c + 2c and on monocationic ruthenium complexes with pyrrolate or

  20. Influence of instrumental parameters on the kinetic energy of ions and plasma temperature for a hexapole collision/reaction-cell-based inductively coupled plasma quadrupole mass spectrometer.

    Favre, Georges; Brennetot, René; Chartier, Frédéric; Tortajada, Jeanine


    Inductively coupled plasma mass spectrometry (ICP-MS) is widely used in inorganic analytical chemistry for element and/or isotope ratio measurements. The presence of interferences, which is one of the main limitations of this method, has been addressed in recent years with the introduction of collision/reaction cell devices on ICP-MS apparatus. The study of ion-molecule reactions in the gas phase then became of great importance for the development of new analytical strategies. Knowing the kinetic energy and the electronic states of the ions prior to their entrance into the cell, i.e., just before they react, thereby constitutes crucial information for the interpretation of the observed reactivities. Such studies on an ICP-MS commonly used for routine analyses require the determination of the influence of different instrumental parameters on the energy of the ions and on the plasma temperature from where ions are sampled. The kinetic energy of ions prior to their entrance into the cell has been connected to the voltage applied to the hexapole according to a linear relationship determined from measurements of ion energy losses due to collisions with neutral gas molecules. The effects of the plasma forward power, sampling depth, and the addition of a torch shield to the ICP source were then examined. A decrease of the plasma potential due to the torch shielding, already mentioned in the literature, has been quantified in this study at about 3 V.

  1. A murine model of mixed bone marrow transplant: importance of the splenocytes to balance HVG and GVH reactions

    WU Di; ZHANG Mei; HE Peng-cheng; XU Hui; LI Jing; CAI Rui-bo


    Objective: A murine model of mixing syngeneic and haploidentical major histocompatibility complex (MHC) matched bone marrow cells transplant was used to evaluate the effect of splenocytes in graft-versus-host disease (GVHD) and host-versus-graft reaction (HVGR). Methods: BALB/C recipient mice were lethally conditioned with 8.5 Gy and injected with different grafts which consisted of syngeneic bone marrow cells plus splenocytes (SPLCs) and haploidentical MHC matched bone marrow cells (BMCs)plus different doses of splenocytes. Recipient mice were detected for the percentage of haploidentical MHC matched mouse origin cells in the peripheral blood cells and checked daily for the appearance of GVHD symptoms. Histopathological examination of multiple organs from moribund mice was used to evaluate the grades of GVHD. Results: Recipient mice infused with 10 × 106 haploidentical MHC matched SPLCs and 5×106 syngeneic splenocytes showed a higher level and more stable chimerism with GVHD Ⅱ degree histopathological alterations. Histopathological results of GVHD in other group's hosts were not obvious, and the levels of chimerism were unstable. All of the mice survived over 150 d. Conclusion:The proportion and dose of syngeneic and haploidentical MHC splenocytes are of importance for inducing stable engraftment on the basis of nonlethal GVHD and to balance GVHD and HVGR.

  2. Development of a road transport emission inventory for Greece and the Greater Athens Area: effects of important parameters.

    Fameli, K M; Assimakopoulos, V D


    Traffic is considered one of the major polluting sectors and as a consequence a significant cause for the measured exceedances of ambient air quality limit values mainly in urban areas. The Greater Athens Area (located in Attica), the most populated area in Greece, faces severe air pollution problems due to the combination of high road traffic emissions, complex topography and local meteorological conditions. Even though several efforts were made to construct traffic emission inventories for Greece and Attica, still there is not a spatially and temporally resolved one, based on data from relevant authorities and organisations. The present work aims to estimate road emissions in Greece and Attica based on the top down approach. The programme COPERT 4 was used to calculate the annual total emissions from the road transport sector for the period 2006-2010 and an emission inventory for Greece and Attica was developed with high spatial (6 × 6 km(2) for Greece and 2 × 2 km(2) for Attica) and temporal (1-hour) resolutions. The results revealed that about 40% of national CO₂, CO, VOC and NMVOC values and 30% of NOx and particles are emitted in Attica. The fuel consumption and the subsequent reduction of annual mileage driven in combination with the import of new engine anti-pollution technologies affected CO₂, CO, VOC and NMVOC emissions. The major part of CO (56.53%) and CO₂ (66.15%) emissions was due to passenger cars (2010), while heavy duty vehicles (HDVs) were connected with NOx, PM₂.₅ and PM₁₀ emissions with 51.27%, 43.97% and 38.13% respectively (2010). The fleet composition, the penetration of diesel fuelled cars, the increase of urban average speed and the fleet renewal are among the most effective parameters towards the emission reduction strategies.

  3. Research on optimal process parameters in thermally oxidation-assisted polishing of reaction-sintered silicon carbide

    Shen, Xinmin; Yamamura, Kazuya; Zhang, Xiaonan; Zhang, Xiangpo; Wang, Dong; Peng, Kang


    Reaction-sintered silicon carbide (RS-SiC) has been widely used in space telescope systems for its excellent physical and mechanical properties. Thermally oxidation-assisted polishing is a practical machining method to obtain RS-SiC parts with high precision, and the research focus is optimization of process parameters, because there are bumpy structures on the oxidized RS-SiC. By atomic force microscopy (AFM) detection, the distributions of oxides on the oxidized RS-SiC sample are quantitative analyzed when the thermal oxidation time is 5min, 30min, and 60min, and the calculated average differences of oxide heights between the initial Si grains and SiC grains are 10.7nm, 25.1nm, and 35.2nm, respectively. Meanwhile, the volume expansion coefficient in oxidation of Si/SiC to SiO2 is 2.257 and 2.194, respectively. Through theoretical derivation based on the Deal-Grove model, the numerical relationship between differences of oxide heights and thermal oxidation time is obtained. Combining with the material removal rate of oxide by ceria slurry in the abrasive polishing, the obtained surface quality can be precisely forecasted and controlled. The oxidized RS-SiC sample, when the oxidation time is 30min, is polished with different times to verify the theoretical analysis results. When the polishing times are 20min, 30min, and 40min, the obtained differences of oxide heights by the AFM detection are consistent with theoretical calculated results. Research on the optimal process parameters in thermally oxidation-assisted polishing of RS-SiC can improve the process level of RS-SiC sample and promote the application of SiC parts.

  4. Hydrolysis of Surfactants Containing Ester Bonds: Modulation of Reaction Kinetics and Important Aspects of Surfactant Self-Assembly

    Lundberg, Dan; Stjerndahl, Maria


    The effects of self-assembly on the hydrolysis kinetics of surfactants that contain ester bonds are discussed. A number of examples on how reaction rates and apparent reaction orders can be modulated by changes in the conditions, including an instance of apparent zero-order kinetics, are presented. Furthermore, it is shown that the examples on…

  5. Effect of diluent and reaction parameter on selective oxidation of propane over MoVTeNb catalyst using nanoflow catalytic reactor

    Restu Kartiko Widi; Sharifah Bee Abdul Hamid; Robert Schl(o)gl


    The selective oxidation of propane to acrylic acid over an MoVTeNb mixed oxide catalyst, dried and calcined before reaction has been studied using high-throughput instrumentation, which is called nanoflow catalytic reactor. The effects of catalyst dilution on the catalytic performance of the MoVTeNb mixed oxide catalyst in selective oxidation of propane to acrylic acid were also investigated. The effects of some reaction parameters, such as gas hourly space velocity (GHSV) and reaction temperature, for selective oxidation of propane to acrylic acid over diluted MoVTeNb catalyst have also been studied. The configuration of the nanoflow is shown to be suitable for screen catalytic performance, and its operating conditions were mimicked closely to conventional laboratory as well as to industrial conditions. The results obtained provided very good reproducibility and it showed that preparation methods as well as reaction parameters can play significant roles in catalytic performance of these catalysts.

  6. A hydrogen-bonding network is important for oxidation and isomerization in the reaction catalyzed by cholesterol oxidase

    Lyubimov, Artem Y. [Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Sinsheimer Laboratories, 1156 High Street, Santa Cruz, CA 95064 (United States); Chen, Lin; Sampson, Nicole S. [Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400 (United States); Vrielink, Alice, E-mail: [School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Sinsheimer Laboratories, 1156 High Street, Santa Cruz, CA 95064 (United States)


    The importance of active-site electrostatics for oxidative and reductive half-reactions in a redox flavoenzyme (cholesterol oxidase) have been investigated by a combination of biochemistry and atomic resolution crystallography. A detailed examination of active-site dynamics demonstrates that the oxidation of substrate and the re-oxidation of the flavin cofactor by molecular oxygen are linked by a single active-site asparagine. Cholesterol oxidase is a flavoenzyme that catalyzes the oxidation and isomerization of 3β-hydroxysteroids. Structural and mutagenesis studies have shown that Asn485 plays a key role in substrate oxidation. The side chain makes an NH⋯π interaction with the reduced form of the flavin cofactor. A N485D mutant was constructed to further test the role of the amide group in catalysis. The mutation resulted in a 1800-fold drop in the overall k{sub cat}. Atomic resolution structures were determined for both the N485L and N485D mutants. The structure of the N485D mutant enzyme (at 1.0 Å resolution) reveals significant perturbations in the active site. As predicted, Asp485 is oriented away from the flavin moiety, such that any stabilizing interaction with the reduced flavin is abolished. Met122 and Glu361 form unusual hydrogen bonds to the functional group of Asp485 and are displaced from the positions they occupy in the wild-type active site. The overall effect is to disrupt the stabilization of the reduced FAD cofactor during catalysis. Furthermore, a narrow transient channel that is shown to form when the wild-type Asn485 forms the NH⋯π interaction with FAD and that has been proposed to function as an access route of molecular oxygen, is not observed in either of the mutant structures, suggesting that the dynamics of the active site are altered.

  7. Application of Multi-Valued Weighting Logical Functions in the Analysis of a Degree of Importance of Construction Parameters on the Example of Hydraulic Valves

    Deptuła A.


    Full Text Available In the optimization process, changes in the construction parameters value influence the behaviour of functions depending on time. Weighting logical coefficients for the stabilisation time are taken into consideration here, i.e., a shorter (better stabilisation time has a more important (bigger value of the weighting coefficient. An example of applying weighting logical functions in the analysis of a degree of importance of construction parameters of a hydraulic valve is presented in the paper

  8. Laser kinetic spectroscopic studies of (a) the unimolecular reactions of nitroalkanes and, (b) elementary reactions important in combustion. Annual progress report 1 Jan-31 Aug 81

    Estler, R.C.; Reisler, H.; Wittig, C.


    The multiphoton ionization (MPI) of NO is used to probe the dynamics of the photodissociation of NO2 in a one-color experiment. The resulting MPI spectra clearly indicate the high internal rotational energy in the NO fragment. MPI shows promise as a highly-sensitive, information-rich diagnostic for internal state determinations of nitric oxide. We report that the 300 K reaction of C2H with O2 has as one of its product channels CH + CO2. By monitoring time resolved CH chemiluminescence following laser photolysis production of C2H in the presence of O2, we have measured rate coefficients for reactions of C2H with O2, H2, and CH4.

  9. Assessing the relative importance of parameter and forcing uncertainty and their interactions in conceptual hydrological model simulations

    Mockler, E. M.; Chun, K. P.; Sapriza-Azuri, G.; Bruen, M.; Wheater, H. S.


    Predictions of river flow dynamics provide vital information for many aspects of water management including water resource planning, climate adaptation, and flood and drought assessments. Many of the subjective choices that modellers make including model and criteria selection can have a significant impact on the magnitude and distribution of the output uncertainty. Hydrological modellers are tasked with understanding and minimising the uncertainty surrounding streamflow predictions before communicating the overall uncertainty to decision makers. Parameter uncertainty in conceptual rainfall-runoff models has been widely investigated, and model structural uncertainty and forcing data have been receiving increasing attention. This study aimed to assess uncertainties in streamflow predictions due to forcing data and the identification of behavioural parameter sets in 31 Irish catchments. By combining stochastic rainfall ensembles and multiple parameter sets for three conceptual rainfall-runoff models, an analysis of variance model was used to decompose the total uncertainty in streamflow simulations into contributions from (i) forcing data, (ii) identification of model parameters and (iii) interactions between the two. The analysis illustrates that, for our subjective choices, hydrological model selection had a greater contribution to overall uncertainty, while performance criteria selection influenced the relative intra-annual uncertainties in streamflow predictions. Uncertainties in streamflow predictions due to the method of determining parameters were relatively lower for wetter catchments, and more evenly distributed throughout the year when the Nash-Sutcliffe Efficiency of logarithmic values of flow (lnNSE) was the evaluation criterion.

  10. Chemical reaction, thermal relaxation time and internal material parameter effects on MHD viscoelastic fluid with internal structure using the Cattaneo-Christov heat flux equation

    Khan, Sabeel M.; Hammad, M.; Sunny, D. A.


    In this article, the influence of thermal relaxation time and chemical reaction is studied on the MHD upper-convected viscoelastic fluid with internal structure using the Cattaneo-Christov heat flux equation for the first time in the literature. The flow-governing equations are formulated and are converted into their respective ordinary differential equations (ODEs) with the application of similarity functions. The resulting system of coupled nonlinear ODEs is solved along with the prescribed conditions at boundary using a finite-difference code in MATLAB. Influence of chemical reaction, thermal relaxation time and internal material parameter on the macroscopic and micropolar velocities as well as on the temperature and concentration profiles is examined along with other physical parameters ( e.g., magnetic parameter, Eckert number, Prandtl number and fluid relaxation time). The accuracy of the obtained numerical solution is shown by comparing the physical parameters of interest with particular cases of existing results in the literature.

  11. Optical Potential Parameters for Halo Nucleus System 6He+12C from Transfer Reaction11B (7Li, 6He) 12C

    WU Zhen-Dong; XU Xin-Xing; BAI Chun-Lin; YU Ning; JIA Fei; LIN Cheng-Jian; ZHANG Huan-Qiao; LIU Zu-Hua; YANG Feng; AN Guang-Peng; ZHANG Chun-Lei; ZHANG Gao-Long; JIA Hui-Ming


    The optical potential parameters for the halo nucleus system 6He+12 C are extracted from fits to the measured angular distributions of 11B(7 Li, 6He)12C reaction at energies of 18.3 and 28.3 MeV with distorted-wave Born approximation analysis. The characters of the obtained optical potential parameters are basically consistent with the results extracted from the fits to the elastic-scattering angular distributions in the literature.

  12. Importance of tunneling in H-abstraction reactions by OH radicals. The case of CH4 + OH studied through isotope-substituted analogs

    Lamberts, T.; Fedoseev, G.; Kästner, J.; Ioppolo, S.; Linnartz, H.


    We present a combined experimental and theoretical study focussing on the quantum tunneling of atoms in the reaction between CH4 and OH. The importance of this reaction pathway is derived by investigating isotope substituted analogs. Quantitative reaction rates needed for astrochemical models at low temperature are currently unavailable both in the solid state and in the gas phase. Here, we study tunneling effects upon hydrogen abstraction in CH4 + OH by focusing on two reactions: CH4 + OD → CH3 + HDO and CD4 + OH → CD3 + HDO. The experimental study shows that the solid-state reaction rate RCH4 + OD is higher than RCD4 + OH at 15 K. Experimental results are accompanied by calculations of the corresponding unimolecular and bimolecular reaction rate constants using instanton theory taking into account surface effects. For the work presented here, the unimolecular reactions are particularly interesting as these provide insight into reactions following a Langmuir-Hinshelwood process. The resulting ratio of the rate constants shows that the H abstraction (kCH4 + OD) is approximately ten times faster than D-abstraction (kCD4 + OH) at 65 K. We conclude that tunneling is involved at low temperatures in the abstraction reactions studied here. The unimolecular rate constants can be used by the modeling community as a first approach to describe OH-mediated abstraction reactions in the solid phase. For this reason we provide fits of our calculated rate constants that allow the inclusion of these reactions in models in a straightforward fashion.

  13. Quantification of CO2 generation in sedimentary basins through carbonate/clays reactions with uncertain thermodynamic parameters

    Ceriotti, G.; Porta, G. M.; Geloni, C.; Dalla Rosa, M.; Guadagnini, A.


    We develop a methodological framework and mathematical formulation which yields estimates of the uncertainty associated with the amounts of CO2 generated by Carbonate-Clays Reactions (CCR) in large-scale subsurface systems to assist characterization of the main features of this geochemical process. Our approach couples a one-dimensional compaction model, providing the dynamics of the evolution of porosity, temperature and pressure along the vertical direction, with a chemical model able to quantify the partial pressure of CO2 resulting from minerals and pore water interaction. The modeling framework we propose allows (i) estimating the depth at which the source of gases is located and (ii) quantifying the amount of CO2 generated, based on the mineralogy of the sediments involved in the basin formation process. A distinctive objective of the study is the quantification of the way the uncertainty affecting chemical equilibrium constants propagates to model outputs, i.e., the flux of CO2. These parameters are considered as key sources of uncertainty in our modeling approach because temperature and pressure distributions associated with deep burial depths typically fall outside the range of validity of commonly employed geochemical databases and typically used geochemical software. We also analyze the impact of the relative abundancy of primary phases in the sediments on the activation of CCR processes. As a test bed, we consider a computational study where pressure and temperature conditions are representative of those observed in real sedimentary formation. Our results are conducive to the probabilistic assessment of (i) the characteristic pressure and temperature at which CCR leads to generation of CO2 in sedimentary systems, (ii) the order of magnitude of the CO2 generation rate that can be associated with CCR processes.

  14. A case study of the mechanism of alcohol-mediated Morita Baylis-Hillman reactions. The importance of experimental observations.

    Plata, R Erik; Singleton, Daniel A


    The mechanism of the Morita Baylis-Hillman reaction has been heavily studied in the literature, and a long series of computational studies have defined complete theoretical energy profiles in these reactions. We employ here a combination of mechanistic probes, including the observation of intermediates, the independent generation and partitioning of intermediates, thermodynamic and kinetic measurements on the main reaction and side reactions, isotopic incorporation from solvent, and kinetic isotope effects, to define the mechanism and an experimental mechanistic free-energy profile for a prototypical Morita Baylis-Hillman reaction in methanol. The results are then used to critically evaluate the ability of computations to predict the mechanism. The most notable prediction of the many computational studies, that of a proton-shuttle pathway, is refuted in favor of a simple but computationally intractable acid-base mechanism. Computational predictions vary vastly, and it is not clear that any significant accurate information that was not already apparent from experiment could have been garnered from computations. With care, entropy calculations are only a minor contributor to the larger computational error, while literature entropy-correction processes lead to absurd free-energy predictions. The computations aid in interpreting observations but fail utterly as a replacement for experiment.

  15. Communication: Energetics of reaction pathways for reactions of ethenol with the hydroxyl radical: the importance of internal hydrogen bonding at the transition state.

    Tishchenko, Oksana; Ilieva, Sonia; Truhlar, Donald G


    We find high multireference character for abstraction of H from the OH group of ethenol (also called vinyl alcohol); therefore we adopt a multireference approach to calculate barrier heights for the various possible reaction channels of OH+C(2)H(3)OH. The relative barrier heights of ten possible saddle points for reaction of OH with ethenol are predicted by multireference Møller-Plesset perturbation theory with active spaces based on correlated participating orbitals (CPOs) and CPO plus a correlated pi orbital (CPO+pi). Six barrier heights for abstracting H from a C-H bond range from 3.1 to 7.7 kcal/mol, two barrier heights for abstracting H from an O-H bond are both 6.0 kcal/mol, and two barrier heights for OH addition to the double bond are -1.8 and -2.8 kcal/mol. Thus we expect abstraction at high-temperature and addition at low temperature. The factor that determines which H is most favorable to abstract is an internal hydrogen bond that constitutes part of a six-membered ring at one of the abstraction saddle points; the hydrogen bond contributes about 3 kcal/mol stabilization.

  16. Effect of entrance channel parameters on the fusion of two heavy ions: Excitation functions of reaction products in 16O+66Zn and 37Cl + 45Sc reactions

    Suparne Sodaye; B S Tomar; A Goswami


    Excitation functions of reaction products formed in 16O+66Zn and 37Cl + 45Sc systems, leading to the same compound nucleus, 82Sr, were measured using recoilcatcher technique and off-line -ray spectrometry. The contribution of non-compound processes like transfer and incomplete fusion (ICF) reactions to the cross-sections of different evaporation residues were delineated by comparing the experimental data with the predictions of Monte Carlo simulation code PACE2. The results show that non-compound processes become a significant fraction of the total reaction cross-section in 16O+66Zn systems in the beam energy range studied, while 37Cl + 45Sc gives mainly compound nucleus products. The mass asymmetry dependence of the fusion and non-compound cross-sections have been analysed in terms of the static fusion model and sum rule model.

  17. Estimating Important Electrode Parameters of High Temperature PEM Fuel Cells By Fitting a Model to Polarisation Curves and Impedance Spectra

    Vang, Jakob Rabjerg; Zhou, Fan; Andreasen, Søren Juhl;


    A high temperature PEM (HTPEM) fuel cell model capable of simulating both steady state and dynamic operation is presented. The purpose is to enable extraction of unknown parameters from sets of impedance spectra and polarisation curves. The model is fitted to two polarisation curves and four...... impedance spectra measured on a Dapozol 77 MEA. The model is capable of achieving good agreement with the recorded curves. Except at OCV, where the voltage is overpredicted, the simulated polarisation curves deviate maximum 3.0% from the measurements. The impedance spectra deviate maximum 3.7%. The fitted...... parameter values are within the range reported in literature. The only exception is the catalyst layer acid content, which is an order of magnitude lower. This may derive from acid migration. The model is used to illustrate the effect of reactant dynamics on the impedance spectrum. The model can aid...

  18. The comparison of the estimation of enzyme kinetic parameters by fitting reaction curve to the integrated Michaelis-Menten rate equations of different predictor variables.

    Liao, Fei; Zhu, Xiao-Yun; Wang, Yong-Mei; Zuo, Yu-Ping


    The estimation of enzyme kinetic parameters by nonlinear fitting reaction curve to the integrated Michaelis-Menten rate equation ln(S(0)/S)+(S(0)-S)/K(m)=(V(m)/K(m))xt was investigated and compared to that by fitting to (S(0)-S)/t=V(m)-K(m)x[ln(S(0)/S)/t] (Atkins GL, Nimmo IA. The reliability of Michaelis-Menten constants and maximum velocities estimated by using the integrated Michaelis-Menten equation. Biochem J 1973;135:779-84) with uricase as the model. Uricase reaction curve was simulated with random absorbance error of 0.001 at 0.075 mmol/l uric acid. Experimental reaction curve was monitored by absorbance at 293 nm. For both CV and deviation kinetic parameters and applicable for the characterization of enzyme inhibitors.

  19. The homogeneously catalysed addition reaction of polyhalogenoalkanes to olefins by divalent arylnickel complexes: comparative reactivity and some important mechanistic leads

    Koten, G. van; Grove, D.M.; Verschuuren, A.H.M.; Beek, J.A.M. van


    In comparative studies some bis(ortho-chelated) arylnickel compounds of the type [Ni{C{6}H{3}(CH{2}NRR'){2}-2, 6}X] have been tested for activity in the Kharasch addition reaction of polyhalogenoalkanes to an alkene double bond using methyl methacrylate as substrate and carbon tetrachloride as reage

  20. A coupled transport and solid mechanics formulation with improved reaction kinetics parameters for modeling oxidation and decomposition in a uranium hydride bed.

    Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.


    Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.

  1. A hierarchical method for Bayesian inference of rate parameters from shock tube data: Application to the study of the reaction of hydroxyl with 2-methylfuran

    Kim, Daesang


    We developed a novel two-step hierarchical method for the Bayesian inference of the rate parameters of a target reaction from time-resolved concentration measurements in shock tubes. The method was applied to the calibration of the parameters of the reaction of hydroxyl with 2-methylfuran, which is studied experimentally via absorption measurements of the OH radical\\'s concentration following shock-heating. In the first step of the approach, each shock tube experiment is treated independently to infer the posterior distribution of the rate constant and error hyper-parameter that best explains the OH signal. In the second step, these posterior distributions are sampled to calibrate the parameters appearing in the Arrhenius reaction model for the rate constant. Furthermore, the second step is modified and repeated in order to explore alternative rate constant models and to assess the effect of uncertainties in the reflected shock\\'s temperature. Comparisons of the estimates obtained via the proposed methodology against the common least squares approach are presented. The relative merits of the novel Bayesian framework are highlighted, especially with respect to the opportunity to utilize the posterior distributions of the parameters in future uncertainty quantification studies.

  2. The reliability horizon for semi-classical quantum gravity metric fluctuations are often more important than back-reaction

    Visser, M


    In this note I introduce the notion of the ``reliability horizon'' for semi-classical quantum gravity. This reliability horizon is an attempt to quantify the extent to which we should trust semi-classical quantum gravity, and to get a better handle on just where the Planck regime resides. I point out that the key obstruction to pushing semi-classical quantum gravity into the Planck regime is often the existence of large metric fluctuations, rather than a large back-reaction. There are many situations where the metric fluctuations become large long before the back-reaction is significant. Issues of this type are fundamental to any attempt at proving Hawking's chronology protection conjecture from first principles, since I shall prove that the onset of chronology violation is always hidden behind the reliability horizon.

  3. Prediction and quantifying parameter importance in simultaneous anaerobic sulfide and nitrate removal process using artificial neural network.

    Cai, Jing; Zheng, Ping; Qaisar, Mahmood; Luo, Tao


    The present investigation deals with the prediction of the performance of simultaneous anaerobic sulfide and nitrate removal in an upflow anaerobic sludge bed (UASB) reactor through an artificial neural network (ANN). Influent sulfide concentration, influent nitrate concentration, S/N mole ratio, pH, and hydraulic retention time (HRT) for 144 days' steady-state condition were the inputs of the model; whereas output parameters were sulfide removal percentage, nitrate removal percentage, sulfate production percentage, and nitrogen production percentage. The prediction performance was evaluated by calculating root mean square error (RMSE), mean absolute error (MAE), mean absolute relative error (MARE), and determination coefficient (R (2)) values. Generally, the ANN model exhibited good prediction of the simultaneous sulfide and nitrate removal process. The effect of five input parameters to the performance of the reactor was quantified and compared using the connection weights method, Garson's algorithm method, and partial derivatives (PaD) method. The results showed that HRT markedly affects the performance of the reactor.

  4. Production Biodiesel from Coconut Oil Using Microwave: Effect of Some Parameters on Transesterification Reaction by NaOH Catalyst

    A. Suryanto


    Full Text Available The purpose of this research was to study the effect of reaction time and NaOH catalyst in transesterification of coconut oil enhanced by microwave and to obtain a biodiesel. Reaction was conducted in batch reactor which equipped by microwave. Coconut oil contains saturated fatty acids about 70% with medium chain (C8-C14, especially lauric acid and myristic acid. The reaction was initiated by mixing oil and methanol with oil to methanol mole ratios of 1:3, 1:6, 1:9 and 1:12, catalyst concentration of 0.1, 0.15, 0.2, 0.25 and 0.3 wt.%, as well as setting electrical power at 100, 264 and 400 W. The reaction times were of  0.5, 1, 1.5, 2, 2.5, 3 and 3.5 min. The result showed that microwave could be employed as an energy source and was able to accelerate the transesterification process to produce biodiesel using NaOH catalyst. The biodiesel yields increase with increasing microwave power. The highest yield of biodiesel obtained  was of  97.37%  with reaction conditions set at 0.2 wt.% catalyst, a reaction time of 2 min, molar ratio of methanol to oil 1:9 and microwave power of 400 watt. © 2015 BCREC UNDIP. All rights reservedReceived: 15th January 2015; Revised: 10th March 2015; Accepted: 15th March 2015How to Cite: Suryanto, A., Suprapto, S., Mahfud, M. (2015. Production Biodiesel from Coconut Oil Using Microwave: Effect of Reaction Time on Transesterification Reaction by NaOH Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 162-168. (doi:10.9767/bcrec.10.2.8080.162-168 Permalink/DOI: 

  5. Evaluation of kinetic parameters of exothermic gas/solid-reactions by the ignition point method; Bestimmung kinetischer Parameter exothermer Gas/Feststoff-Reaktionen mit der Zuendpunktsmethode

    Hein, O.; Jess, A. [Technische Hochschule Aachen (Germany). Inst. fuer Technische Chemie und Makromolekulare Chemie


    The determination of kinetic constants of heterogeneous reactions is usually performed in tubular flow reactors under isothermal and stationary reaction conditions. This is often time-consuming and difficult. For example, in case of strong exothermic reactions, temperature gradients up to the ignition of the fixed-bed are hard to avoid, and therefore expensive reactors with internal or external gas recycle are needed. The effect of ignition can also be used to characterize the reactivity of solid fuels and the activity of catalysts, respectively. A well-known method for a simple, fast and accurate determination of the ignition temperature in a lab-scale tubular flow reactor is already described in literature. Yet, the ignition point method is up to now only used as a qualitative measure for the (relative) reactivity of solid fuels and activity of catalysts. Therefore, an attempt was made to extend this method towards a quantitative characterization of the kinetics of exothermic heterogeneous reaction systems, i.e. for a determination of the activation energy and the preexponential factor. The basic idea is thereby to alter the ignition point by a defined variation of the operation conditions such as particle diameter, heating rate as well as of the composition and flow rate of the reacting gas mixture. The resulting data are then used to calculate the kinetic constants based on the theory of ignition of exothermic reactions. The combustion of different cokes as well as of carbon deposits on a Pt-catalyst were selected as model reactions for gas/solid-reactions. In addition, the oxidation of methane on a Pt-catalyst was investigated. The experiments on the influence of the operation conditions show that the gas composition - in case of combustion of coke the oxygen content - has the strongest influence on the ignition temperature. This method is therefore very suitable to determine kinetic constants. To prove the accuracy of this method, the kinetic data were also

  6. The importance of calibration parameters on the accuracy of the floods description in the Snyder’s model

    Wałęga Andrzej


    Full Text Available Comparison of quality of Snyder’s model for determination flood waves was examination in this work. Model parameters were calibrated based on objective functions: percentage error in peak flow (PEPF, percentage error in volume (PEV, peak-weighted root mean square error (PWRMSE, sum of absolute residuals (SAR and sum of squared residuals (SSR. Quality of model was calculating by Nash-Sutcliffe efficiency coefficient E. Additionally sensitivity of a model was characterized by its flexibility. The analyses were performed in the watershed of Grabinka. It has been found that the use PWRMSE as the objective function allows to obtain the best quality results of simulation. Furthermore, Snyder’s model is flexible to the change of Cp coefficient.

  7. Sequential identification of model parameters by derivative double two-dimensional correlation spectroscopy and calibration-free approach for chemical reaction systems.

    Spegazzini, Nicolas; Siesler, Heinz W; Ozaki, Yukihiro


    A sequential identification approach by two-dimensional (2D) correlation analysis for the identification of a chemical reaction model, activation, and thermodynamic parameters is presented in this paper. The identification task is decomposed into a sequence of subproblems. The first step is the construction of a reaction model with the suggested information by model-free 2D correlation analysis using a novel technique called derivative double 2D correlation spectroscopy (DD2DCOS), which enables one to analyze intensities with nonlinear behavior and overlapped bands. The second step is a model-based 2D correlation analysis where the activation and thermodynamic parameters are estimated by an indirect implicit calibration or a calibration-free approach. In this way, a minimization process for the spectral information by sample-sample 2D correlation spectroscopy and kinetic hard modeling (using ordinary differential equations) of the chemical reaction model is carried out. The sequential identification by 2D correlation analysis is illustrated with reference to the isomeric structure of diphenylurethane synthesized from phenylisocyanate and phenol. The reaction was investigated by FT-IR spectroscopy. The activation and thermodynamic parameters of the isomeric structures of diphenylurethane linked through a hydrogen bonding equilibrium were studied by means of an integration of model-free and model-based 2D correlation analysis called a sequential identification approach. The study determined the enthalpy (ΔH = 15.25 kJ/mol) and entropy (TΔS = 13.20 kJ/mol) of C═O···H hydrogen bonding of diphenylurethane through direct calculation from the differences in the kinetic parameters (δΔ(‡)H, -TδΔ(‡)S) at equilibrium in the chemical reaction system.

  8. Flexibility, stroke, and dimensionless parameters: the importance of telling the whole story for swimming micro-organisms in complex fluids

    Thomases, Becca; Guy, Robert


    The question of how fluid elasticity affects the swimming performance of micro-organisms is complicated and has been the subject of many recent experimental and theoretical studies. The Deborah number, De = λω , is typically used to characterize the strength of the fluid elasticity in these studies, and for swimmers is expressed as the product of the elastic relaxation time and the frequency of the swimmer stroke. In simulations of undulatory flexible swimmers in an Oldroyd-B-type fluid, we find that varying the frequency of the stroke and varying the relaxation time separately results in a significantly different dependence of swimming speed for the same De . Thus the elastic effects on swimming cannot be characterized by a single dimensionless number. The Weissenberg number, defined as the product of elastic relaxation time and characteristic strain rate (Wi = λγ˙), is another dimensionless parameter useful for describing complex fluids. For a fixed swimmer frequency, varying the relaxation time will also vary the Weissenberg number. We conjecture that the different behavior is a consequence of a Weissenberg-number transition in the fluid, which additionally depends on the amplitude of the swimmer stroke.

  9. On the Importance of the Aromatic Ring Parameter in Studies of the Solvolyses of Cinnamyl and Cinnamoyl Halides

    Malcolm J. D'Souza


    Full Text Available In solvolysis studies using Grunwald-Winstein plots, dispersions were observed for substrates with aromatic rings at the α-carbon. Several examples for the unimolecular solvolysis of monoaryl benzylic derivatives and related diaryl- or naphthyl-substituted derivatives have now been reported, where the application of the aromatic ring parameter (I removes this dispersion. A recent claim suggesting the presence of an appreciable nucleophilic component to the I scale has now been shown, in a review of the solvolysis of highly-hindered alkyl halides, to be unlikely to be correct. Attention is now focused on the application of the hI term for the solvolysis of compounds containing a double bond in the vicinity of any developing carbocation. Available specific rates of solvolysis (plus some new values at 25°C of cinnamyl chloride, cinnamyl bromide, cinnamoyl chloride, p-chlorocinnamoyl chloride, and p-nitrocinnamoyl chloride are analyzed using the simple and extended (including the hI term Grunwald-Winstein equations.

  10. [Prospective study of the importance of constitutional parameters in the development of eczema in hairdressers and construction workers].

    Hornstein, O P; Bäurle, G; Kienlein-Kletschka, B


    The considerable rate of professional hand eczema in hairdressers, especially in young ones, emphasizes the necessity of practicable methods for early diagnosis of risk and manifestation of eczema. Therefore, we investigated different constitutional parameters of the skin (hyperhidrosis, dyshidrosis and acrocyanosis of the hands, seborrhea, sebostasis, white dermographism) in a prospective study of 210 hairdressers' and 95 bricklayers' apprentices over 3 years. In addition, the alkali resistance and the permeability of the horny layers (by nitrazine yellow) were examined every year in each of the probands. Among other results dyshidrosis and sebostasis proved to be statistically relevant in the development of hand eczema, whereas no statistic causality was seen for acrocyanosis and hyperhidrosis. Risk of eczema could not be diagnosed early by alcali resistance tests. Frequent wet-work and insufficient skin protection were further factors causing eczema, especially in atopic subjects. There was also a statistically relevant correlation between a periumbilical eczema (caused by metallic buttons on jeans), indicating allergy against nickel, and pierced earlobes. The results of this prospective study show that by simple clinical methods serious risks of eczema in hairdressers and bricklayers can be detected already in the first years of work. Several practical recommendations for prevention of occupational eczema in hairdressers are given.

  11. Coprecipitation of (14)C and Sr with carbonate precipitates: The importance of reaction kinetics and recrystallization pathways.

    Hodkin, David J; Stewart, Douglas I; Graham, James T; Burke, Ian T


    This study investigated the simultaneous removal of Sr(2+) and (14)CO3(2-) from pH>12 Ca(OH)2 solution by the precipitation of calcium carbonate. Initial Ca(2+):CO3(2-) ratios ranged from 10:1 to 10:100 (mM:mM). Maximum removal of (14)C and Sr(2+) both occurred in the system containing 10mM Ca(2+) and 1mM CO3(2-) (99.7% and 98.6% removal respectively). A kinetic model is provided that describes (14)C and Sr removal in terms of mineral dissolution and precipitation reactions. The removal of (14)C was achieved during the depletion of the initial TIC in solution, and was subsequently significantly affected by recrystallization of the calcite precipitate from an elongate to isotropic morphology. This liberated >46% of the (14)C back to solution. Sr(2+) removal occurred as Ca(2+) became depleted in solution and was not significantly affected by the recrystallization process. The proposed reaction could form the basis for low cost remediation scheme for (90)Sr and (14)C in radioactively contaminated waters (<$0.25 reagent cost per m(3) treated).

  12. Importance of fluorodeoxyglucose-positron emission tomography (FDG-PET) and endoscopic ultrasonography parameters in predicting survival following surgery for esophageal cancer

    Omloo, J. M. T.; Sloof, G. W.; Boellaard, R.; Hoekstra, O. S.; Jager, P. L.; van Dullemen, H. M.; Fockens, P.; Plukker, J. T. M.; van Lanschot, J. J. B.


    Background and study aims: To assess the prognostic importance of standardized uptake value (SUV) for 18F-fluorodeoxyglucose (FDG) at positron emission tomography (PET) and of EUS parameters, in esophageal cancer patients primarily treated by surgery. Patients and methods: Between October 2002 and A

  13. Estimation of Important Reproductive Parameters for Management of the Shoemaker Spinefoot Rabbitfish (Siganus sutor in Southern Kenya

    Simon Agembe


    Full Text Available The shoemaker spinefoot, Siganus sutor, is a member of the family Siganidae, commonly known as rabbitfish. Many demersal fish populations in the Kenyan waters are heavily exploited, and fishing effort may be above optimum levels for some species. This study was aimed at determining missing parameters on spawning periodicity and maturity of S. sutor for the Kenyan south coast area of Msambweni, complementing a suite of parallel studies on spawning aggregation based fisheries for this species. A total of 376 samples were collected over 12 months, including 85 that were collected over four lunar phases in November and December 2010. Monthly GSI showed two distinct peaks, one in June and July and one in November and January, suggested two distinct spawning periods within the year. The highest GSI was recorded in November while the lowest values occurred in April August and September. A lunar pattern in ovarian development stage was seen with the highest proportion of ripe ovaries (RI observed in the full moon phase, whereas running ripe (RR or hydrated ovaries dominated samples in the last quarter. Imminent spawning was confirmed by the presence of hydrated oocytes and post ovulatory follicles, observed primarily during the last quarter and to a lesser extent during full moon. GSI value Kruskal-Wallis test showed significant differences in GSI between moon phases (p< 0.05. In conclusion, histological analysis of ovaries points to synchronous development of oocytes with moon phases, suggest that their release takes place over short period of time after the full moon.

  14. Coprecipitation of {sup 14}C and Sr with carbonate precipitates: The importance of reaction kinetics and recrystallization pathways

    Hodkin, David J. [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Stewart, Douglas I. [School of Civil Engineering, University of Leeds (United Kingdom); Graham, James T. [National Nuclear Laboratory, Sellafield, Cumbria (United Kingdom); Burke, Ian T., E-mail: [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom)


    This study investigated the simultaneous removal of Sr{sup 2+} and {sup 14}CO{sub 3}{sup 2−} from pH > 12 Ca(OH){sub 2} solution by the precipitation of calcium carbonate. Initial Ca{sup 2+}:CO{sub 3}{sup 2−} ratios ranged from 10:1 to 10:100 (mM:mM). Maximum removal of {sup 14}C and Sr{sup 2+} both occurred in the system containing 10 mM Ca{sup 2+} and 1 mM CO{sub 3}{sup 2−} (99.7% and 98.6% removal respectively). A kinetic model is provided that describes {sup 14}C and Sr removal in terms of mineral dissolution and precipitation reactions. The removal of {sup 14}C was achieved during the depletion of the initial TIC in solution, and was subsequently significantly affected by recrystallization of the calcite precipitate from an elongate to isotropic morphology. This liberated > 46% of the {sup 14}C back to solution. Sr{sup 2+} removal occurred as Ca{sup 2+} became depleted in solution and was not significantly affected by the recrystallization process. The proposed reaction could form the basis for low cost remediation scheme for {sup 90}Sr and {sup 14}C in radioactively contaminated waters (<$0.25 reagent cost per m{sup 3} treated). - Highlights: • 99.7% of {sup 14}C and 98.6% of Sr removed from aqueous solution by CaCO{sub 3} precipitation. • Remobilization of {sup 14}C observed during calcium carbonate recrystallization. • Sr displayed variable distribution coefficient (possibly affected by Ca:Sr ratio). • Reagent cost of $0.22/m{sup 3} of treated groundwater.

  15. Studies of ClO and BrO reactions important in the polar stratosphere: Kinetics and mechanism of the ClO+BrO and ClO+ClO reactions

    Friedl, Randall R.; Sander, Stanley P.


    The reactions, BrO + ClO yields Br + ClOO (1a) yields Br + OClO (1b) yields BrCl + O2 (1c) and ClO + ClO yields Cl + CiOO (2a) yields Cl + OClO (2b) yields Cl2 + O2 (2c) yields (ClO)2 (2d) have assumed new importance in explaining the unusual springtime depletion of ozone observed in the Antarctic stratosphere. The mechanisms of these reactions involve the formation of metastable intermediates which subsequently decompose through several energetically allowed products providing the motivation to study these reactions using both the discharge flow-mass spectrometric and flash photolysis - ultraviolet absorption techniques. These methods have also been used to explore aspects of the kinetics and spectroscopy of the ClO dimer.

  16. Importance of Physical and Physiological Parameters in Simulated Particle Transport in the Alveolar Zone of the Human Lung

    Dogan Ciloglu


    Full Text Available The trajectory and deposition efficiency of micron-sized (1–5 µm particles, inhaled into the pulmonary system, are accurately determined with the aid of a newly developed model and modified simulation techniques. This alveolar model, which has a simple but physiologically appropriate geometry, and the utilized fluid structure interaction (FSI methods permit the precise simulation of tissue wall deformation and particle fluid interactions. The relation between tissue movement and airflow in the alveolated duct is solved by a two-way fluid structure interaction simulation technique, using ANSYS Workbench (Release 16.0, ANSYS INC., Pittsburgh, PA, USA, 2015. The dynamic transport of particles and their deposition are investigated as a function of aerodynamic particle size, tissue visco-elasticity, tidal breathing period, gravity orientation and particle–fluid interactions. It is found that the fluid flows and streamlines differ between the present flexible model and rigid models, and the two-way coupling particle trajectories vary relative to one-way particle coupling. In addition, the results indicate that modelling the two-way coupling particle system is important because the two-way discrete phase method (DPM approach despite its complexity provides more extensive particle interactions and is more reliable than transport results from the one-way DPM approach. The substantial difference between the results of the two approaches is likely due to particle–fluid interactions, which re-suspend the sediment particles in the airway stream and hence pass from the current generation.

  17. Leaching of polycyclic aromatic hydrocarbons from power plant lignite ash--influence of parameters important for environmental pollution.

    Pergal, Miodrag M; Relić, Dubravka; Tešić, Zivoslav Lj; Popović, Aleksandar R


    Nikola Tesla B power plant (TENT B), located at the Sava River, in Obrenovac, 50 km west from the Serbian's capital, Belgrade, is the second largest coal-fired power plant in the country, consisting of two blocks, each of 620 MW capacity. In order to investigate the threat polycyclic aromatic hydrocarbons (PAHs) from deposited coal ash, obtained by coal combustion in this power plant, can represent for the surrounding environment, samples of coal ash were submitted to extraction with river water used for transport of coal ash to the dump, as well as with water of different ionic strength and acidity. It was found that, out of 16 EPA priority PAHs, only naphthalene, acenaphthylene, fluorene, phenantrene, fluoranthene, and pyrene were found in measurable concentrations in the different extracts. Their combined concentration was around 0.1 μg/L, so they do not, in terms of leached concentrations, represent serious danger for the surrounding environment. In all cases of established (and leached) PAH compounds, changes of ionic strength, acidity, or the presence of organic compounds in river water may to some extent influence the leached concentrations. However, under the examined conditions, similar to those present in the environment, leached concentrations were not more than 50 % greater than the concentrations leached by distilled water. Therefore, water desorption is likely the most important mechanism responsible for leaching of PAH compounds from filter coal ash.

  18. Optimization of reaction parameters for enzymatic glyceride synthesis from fish oil: Ethyl esters versus free fatty acids

    Ravn, Helle Christine; Damstrup, Marianne L.; Meyer, Anne S.


    Enzymatic conversion of fish oil free fatty acids (FFA) or fatty acid ethyl esters (FAE) into glycerides via esterification or transesterification was examined. The reactions catalyzed by Lipozyme™ 435, a Candida antarctica lipase, were optimized. Influence on conversion yields of fatty acid chain...

  19. Calculation of total free energy yield as an alternative approach for predicting the importance of potential chemolithotrophic reactions in geothermal springs.

    Dodsworth, Jeremy A; McDonald, Austin I; Hedlund, Brian P


    To inform hypotheses regarding the relative importance of chemolithotrophic metabolisms in geothermal environments, we calculated free energy yields of 26 chemical reactions potentially supporting chemolithotrophy in two US Great Basin hot springs, taking into account the effects of changing reactant and product activities on the Gibbs free energy as each reaction progressed. Results ranged from 1.2 × 10(-5) to 3.6 J kg(-1) spring water, or 3.7 × 10(-5) to 11.5 J s(-1) based on measured flow rates, with aerobic oxidation of CH(4) or NH4 + giving the highest average yields. Energy yields calculated without constraining pH were similar to those at constant pH except for reactions where H(+) was consumed, which often had significantly lower yields when pH was unconstrained. In contrast to the commonly used normalization of reaction chemical affinities per mole of electrons transferred, reaction energy yields for a given oxidant varied by several orders of magnitude and were more sensitive to differences in the activities of products and reactants. The high energy yield of aerobic ammonia oxidation is consistent with previous observations of significant ammonia oxidation rates and abundant ammonia-oxidizing archaea in sediments of these springs. This approach offers an additional lens through which to view the thermodynamic landscape of geothermal springs.

  20. Mechanism of the Orotidine 5’-Monophosphate Decarboxylase-Catalyzed Reaction: Importance of Residues in the Orotate Binding Site†

    Iiams, Vanessa; Desai, Bijoy J.; Fedorov, Alexander A.; Fedorov, Elena V.; Almo, Steven C.; Gerlt, John A.


    The reaction catalyzed by orotidine 5’-monophosphate decarboxylase (OMPDC) is accompanied by exceptional values for the rate enhancement [kcat/knon = 7.1 × 1016] and catalytic proficiency [(kcat/KM)/knon = 4.8 × 1022 M−1]. Although a stabilized vinyl carbanion/carbene intermediate is located on the reaction coordinate, the structural strategies by which the reduction in the activation energy barrier is realized remain incompletely understood. This laboratory recently reported that “substrate destabilization” by Asp 70 in the OMPDC from Methanothermobacter thermoautotrophicus (MtOMPDC) lowers the activation energy barrier by ~5 kcal/mol (contributing ~2.7 × 103 to the rate enhancement) [K. K. Chan, B. M. Wood, A. A. Fedorov, E. V. Fedorov, H. J. Imker, T. L. Amyes, J. P. Richard, S. C. Almo, and J. A. Gerlt (2009) Biochemistry 48, 5518–31]. We now report that substitutions of hydrophobic residues in a pocket proximal to the carboxylate group of the substrate (Ile 96, Leu 123, and Val 155) with neutral hydrophilic residues decrease the value of kcat by as much as 400-fold but have minimal effect on the value of kex for exchange of H6 of the FUMP product analog with solvent deuterium; we hypothesize that this pocket destabilizes the substrate by preventing hydration of the substrate carboxylate group. We also report that substitutions for Ser 127 that is proximal to O4 of the orotate ring decrease the value of kcat/KM, with the S127P substitution that eliminates hydrogen-bonding interactions with O4 producing a 2.5 × 106-fold reduction in the value of kcat/KM; this effect is consistent with delocalization of the negative charge of the carbanionic intermediate on O4 to produce an anionic carbene intermediate and thereby provide a structural strategy for stabilization of the intermediate. These observations provide additional information on the identities of the active site residues that contribute to the rate enhancement and, therefore, insights into the

  1. Perceived effectiveness of cessation advertisements: the importance of audience reactions and practical implications for media campaign planning.

    Davis, Kevin C; Nonnemaker, James; Duke, Jennifer; Farrelly, Matthew C


    Cessation television ads are often evaluated with measures of perceived effectiveness (PE) that gauge smokers' reactions to the ads. Although measures of PE have been validated for other genres of public service announcements, no studies to our knowledge have demonstrated the predictive validity of PE for cessation TV ads specifically. We analyzed data from a longitudinal Web survey of smokers in the United States to assess whether measures of PE for cessation TV ads are causally antecedent to cessation-related outcomes. These data consisted of baseline and 2-week follow-up surveys of 3,411 smokers who were shown a number of cessation TV ads and were asked to provide their appraisals of PE for those messages. We found that baseline PE for the ads was associated with increased negative feelings about smoking, increased outcome expectations about the benefits of quitting, increased consideration of the benefits of quitting, increased desire to quit, and increased intentions to quit smoking at follow-up. Results suggest that measures of PE for cessation TV ads can be powerful predictors of likely ad success. Hence, our findings support the use of PE in quantitative ad pretesting as part of a standard regimen of formative research for cessation television campaigns.

  2. Modeling stopped-flow data for nucleic acid duplex formation reactions: the importance of off-path intermediates.

    Sikora, Jacqueline R; Rauzan, Brittany; Stegemann, Rachel; Deckert, Alice


    Evidence for unexpected off-path intermediates to DNA duplex formation is presented. These off-path intermediates are shown to involve unimolecular and, in one case, bimolecular structure in one of the single strands of complementary DNA. Three models are developed to account for the observed single-stranded structures that are formed in parallel with duplex formation. These models are applied to the analysis of stopped-flow data for eight different nonself-complementary duplex formation reactions in order to extract the elementary rate constant for formation of the duplex from the complementary random coil single-stranded DNA. The free energy of activation (at 25 °C) for the denaturation of each duplex is calculated from these data and is shown to have a linear correlation to the overall standard free energy for duplex formation (also at 25 °C). Duplexes that contain mismatches obey a parallel linear free-energy (LFE) relationship with a y-intercept that is greater than that of duplexes without mismatches. Slopes near unity for the LFE relationships indicate that all duplexes go through an early, unstructured transition state.

  3. Importance of lifetime effects in breakup and suppression of complete fusion in reactions of weakly bound nuclei

    Cook, K J; Luong, D H; Kalkal, Sunil; Dasgupta, M; Hinde, D J


    Complete fusion cross sections in collisions of light, weakly bound nuclei and high Z targets show above-barrier suppression of complete fusion. This has been interpreted as resulting from breakup of the weakly bound nucleus prior to reaching the fusion barrier, reducing the probability of complete fusion. This paper investigates how these conclusions are affected by lifetimes of the resonant states that are populated prior to breakup. If the mean life of a populated resonance is much longer than the fusion timescale, then its breakup cannot suppress complete fusion. For short-lived resonances, the situation is more complex. This work includes the mean life of the short-lived 2+ resonance in 8Be in classical dynamical model calculations to determine its effect on energy and angular correlations of the breakup fragments and on predictions of fusion suppression. Coincidence measurements of breakup fragments produced in reactions of 9Be with 144Sm, 168Er, 186W, 196Pt, 208Pb and 209Bi at energies below the barrie...

  4. Deuterium D(V/K) isotope effects on ethanol oxidation in hepatocytes; Importance of the reverse ADH-reaction

    Lundquist, F.; Iversen, H.L.; Hansen, L.L. (Department of Biochemistry A, The Panum Institute, University of Copenhagen (Denmark))


    The kinetic deuterium isotope effect, D(V/K), on ethanol oxidation was measured on hepatocytes from rat and pig by the radiometric competitive method using {sup 14}C-labelled ethanol containing deuterium in the (a-R)-position. The corrected D(V/K) values of 2.68 and 2.80 for rat and pig hepatocytes respectively were significantly different, suggesting differences in the amount of non-ADH ethanol oxidizing activity. The apparent isotope effects declined repidly with time when acetaldehyde was present in the medium as a result of the reduction to ethanol of the ({sup 14}C)-acetaldehyde formed from the double labelled ethanol by alcohol dehydrogenase (ADH). Fructose and cynamide caused the acetaldehyde concentration during ethanol oxidation to increase by entirely different mechanisms, and the isotope effect to decrease with time, as did also the addition of acetaldehyde. The apparent first order rate constant for the reverse ADH reaction, assuming the reactants to be acetaldehyde and the ADH-NADH complex, was determined by two metohods giving comparable results. In the presence of semicarbazide, which removes acetaldehyde, the isotope effect was nearly constant. This was the case also when the acetaldehyde concentration was very low (<1 {mu}M) for other reasons, as in hepatocytes from starved animals. A mathematical formula describing the expected decrease of the apparent isotope effect with time was derived. The different response of pig and rat hepatocytes to addition of fructose (the 'fructose effect') is suggested to be caused by differences in activity of aldehyde dehydrogenases in the two species. (author).

  5. The role of various parameters used in proximity potential in heavy-ion fusion reactions: New extension

    Ishwar Dutt


    An attempt has been made to modify the original proximity potential using up-to-date knowledge of the universal function and surface energy coefficient available in the literature. A new radius formula has also been obtained using the recent data on charge distribution. The detailed investigation of over 395 reactions reveal that the new proximity potential reproduces the experimental data better than earlier versions.

  6. Uncertainty study of nuclear model parameters for the n+ ^{56}Fe reactions in the fast neutron region below 20 MeV

    Duan, Junfeng; Sjöstrand, Henrik; Alhassan, Erwin; Gustavsson, Cecilia; Österlund, Michael; Koning, Arjan; Rochman, Dimitri


    In this work, we study the uncertainty of nuclear model parameters for neutron induced ^{56}Fe reactions in fast neutron region by using the Total Monte Carlo method. We perform a large number of TALYS runs and compare the calculated results with the experimental data of the cross sections to obtain the uncertainties of the model parameters. Based on the derived uncertainties another 1000 TALYS runs have been performed to create random cross section files. For comparison with the experimental data we calculate a weighted \\chi^2 value for each random file as well as the ENDF/B-VII.1, JEFF3.1, JENDL4.0 and CENDL3.1 data libraries. Furthermore, we investigate the optical model parameters correlation obtained by way of this procedure.

  7. Laser thermal effect on silicon nitride ceramic based on thermo-chemical reaction with temperature-dependent thermo-physical parameters

    Pan, A. F.; Wang, W. J.; Mei, X. S.; Wang, K. D.; Zhao, W. Q.; Li, T. Q.


    In this study, a two-dimensional thermo-chemical reaction model with temperature-dependent thermo-physical parameters on Si3N4 with 10 ns laser was developed to investigate the ablated size, volume and surface morphology after single pulse. For model parameters, thermal conductivity and heat capacity of β-Si3N4 were obtained from first-principles calculations. Thermal-chemical reaction rate was fitted by collision theory, and then, reaction element length was deduced using the relationship between reaction rate and temperature distribution. Furthermore, plasma absorption related to energy loss was approximated as a function of electron concentration in Si3N4. It turned out that theoretical ablated volume and radius increased and then remained constant with increasing laser energy, and the maximum ablated depth was not in the center of the ablated zone. Moreover, the surface maximum temperature of Si3N4 was verified to be above 3000 K within pulse duration, and it was much higher than its thermal decomposition temperature of 1800 K, which indicated that Si3N4 was not ablated directly above the thermal decomposition temperature. Meanwhile, the single pulse ablation of Si3N4 was performed at different powers using a TEM00 10 ns pulse Nd:YAG laser to validate the model. The model showed a satisfactory consistence between the experimental data and numerical predictions, presenting a new modeling technology that may significantly increase the accuracy of the predicated results for laser ablation of materials undergoing thermo-chemical reactions.

  8. The importance of hinge sequence for loop function and catalytic activity in the reaction catalyzed by triosephosphate isomerase.

    Xiang, J; Sun, J; Sampson, N S


    We have determined the sequence requirements for the N-terminal protein hinge of the active-site lid of triosephosphate isomerase. The codons for the hinge (PVW) were replaced with a genetic library of all possible 8000 amino acid combinations. The most active of these 8000 mutants were selected using in vivo complementation of a triosephosphate isomerase-deficient strain of Escherichia coli, DF502. Approximately 0.3 % of the mutants complement DF502 with an activity that is between 10 and 70 % of wild-type activity. They all contain Pro at the first position. Furthermore, the sequences of these hinge mutants reveal that hydrophobic packing is very important for efficient formation of the enediol intermediate. However, the reduced catalytic activities observed are not due to increased rates of loop opening. To explore the relationship between the N-terminal and C-terminal hinges, three semi-active mutants from the N-terminal hinge selection experiment (PLH, PHS and PTF), and six active C-terminal hinge mutants from previous work (NSS, LWA, YSL, KTK, NPN, KVA) were combined to form 18 "double-hinge" mutants. The activities of these mutants suggest that the N-terminal and C-terminal hinge structures affect one another. It appears that specific side-chain interactions are important for forming a catalytically active enzyme, but not for preventing release of the unstable enediol intermediate from the active site of the enzyme. The independence of intermediate release on amino acid sequence is consistent with the absence of a "universal" hinge sequence in structurally related enzymes.

  9. Evaluation of Tafel-Volmer kinetic parameters for the hydrogen oxidation reaction on Pt(1 1 0) electrodes

    Mann, R. F.; Thurgood, C. P.


    Modelling of PEM fuel cells has long been an active research area to improve understanding of cell and stack operation, facilitate design improvements and support simulation studies. The prediction of activation polarization in most PEM models has concentrated on the cathode losses since anode losses are commonly much smaller and tend to be ignored. Further development of the anode activation polarization term is being undertaken to broaden the application and usefulness of PEM models in general. Published work on the kinetics of the hydrogen oxidation reaction (HOR) using Pt(h k l) electrodes in dilute H2SO4 has been recently reassessed and published. Correlations for diffusion-free exchange current densities were developed and empirical predictive equations for the anode activation polarization were proposed for the experimental conditions of the previously published work: Pt(1 0 0), Pt(1 1 0) and Pt(1 1 1) electrodes, pH2 of 1 atm, and temperatures of 1, 30 and 60 °C. It was concluded that the HOR on Pt(1 1 0) electrodes followed a Tafel-Volmer reaction sequence. The aim of the present paper is to generalize these Tafel-Volmer correlations, apply them to published data for Pt(1 1 0) electrodes and further develop the modelling of anode activation polarization over the range of operating conditions found in PEMFC operation.

  10. Kinetics and mechanism of superoxide radical reactions with some biologically important compounds in aqueous solutions. Pulse radiolysis

    Revina, A. A.; Amiragova, M. I.; Volod'ko, V. V.; Vannikov, A. V.

    Microsecond pulse radiolysis of oxygenated aqueous solutions containing 0.02 mol dm -3 sodium formate and 2 mmol dm -3 phosphate buffer at pH 7 was used to generate superoxide anion radicals. The influence of some biologically important compounds upon the rate of O ⨪2 decay was monitored spectrophotometrically in the range of 245-300 nm. Hematoporphyrin (HP), hemin C (HC), catalase (Cat), cobalt sulfophthalocyanine (CoTSPc) were studied. Among the investigated compounds only Cat was found to show a high catalytic efficiency towards the self-decay of O ⨪2. A red shift of O ⨪2 absorption band and slowing down of its decay were observed to take place by adding HP or CoTSPc to the solutions containing formate ions in excess. This effect is associated with the formation of a transient superoxo-complex. An appearance of an intermediate species with absorption maxima at 350 nm and half-life of about 2s was observed to accompany the superoxo-complex of CoTSPc decay. In the aerated solution of HP the intensity of absorbance at 260 nm was found to be independent of the presence of formate ions.

  11. Testing of the Effect of Reaction Parameters on the Enzyme Immobilization by Adsorption and Cross-Linking Processes with Kinetic Desorption Method

    Dániel Radva


    Full Text Available The activity of enzymes after the immobilization by weak interactions such as adsorption or adsorption followed by a cross-linking reaction can change easily not only during further application but during the activity measured via desorption and/or inactivation of enzymes. The changes in activity could be a consequence of the interactions between the enzyme and support. In this work a quick and efficient method is developed that permits studying of the strength and properties of the forces between the enzymes and support by examining the kinetics of desorption and/or inactivation. Applying this new cyclic kinetic desorption method, the effect of reaction parameters on immobilization could also be studied. The efficiency of this method was tested for optimizing the parameters for immobilization of β-glucosidase on Amberlite IRA 900 anion exchange resin by an adsorption followed by a cross-linking with glutaraldehyde to form potential preparation for food industry. The following parameters were chosen: concentration (0.10 M of the buffer (sodium acetate, pH=5.5 and the ratio of carrier to enzyme (10:1 for the adsorption step, then the time of treatment (1 min and concentration (0.25, by mass per volume of glutaraldehyde for the cross-linking by using the kinetic desorption method. The activity of this preparation was 57 μmol/(min·g in respect of dry resin. It was established that the effect of different parameters on this enzyme immobilization could be characterized by the new cyclic kinetic desorption method in a quick and efficient way; furthermore, it permitted separate testing of the effect of parameters on the adsorption and cross-linking processes.


    Mohammad Najafi; Vahid Haddadi-Asl


    Different Ziegler-Natta catalysts were employed to polymerize ethylene.To investigate the influences of reaction parameters,namely Al/Ti molar ratio,hydrogen and processing parameters,I.e.ethylene pressure and temperature,a Taguchi experimental design was worked out.An L27 orthogonal array was chosen to take the above-mentioned parameters and relevant interactions into account.Response surface method was the tool used to analyze the experimental design results.Al/Ti,ethylene pressure and temperature were selected as experimental design factors.and catalyst activity and polymerization yield were the response parameters.Increasing pressure,due to an increment in monomer accessibility,and rising Al/Ti,because of higher reduction in the catalysts,cause an increase in both polymerization yield and catalyst activity.Nonetheless,a higher temperature,thanks to reducing ethylene solubility in the slurry medium and partially catalyst destruction.lead to a reduction in both response parameters.A synergistic eflfect was also observed between temperature and pressure.All catalyst activities will reduce in the presence of hydrogen.Molecular weight also shows a decline in the presence of hydrogen as a transfer agent.However,the polydispersity index remains approximately intact.Using SEM,various morphologies,owing to different catalyst morphologies,were seen for the polyethylene.

  13. Enzymatic acidolysis of triolein with palmitic and caprylic acids: Optimization of reaction parameters by response surface methodology

    Keskin, H.


    Full Text Available An acidolysis reaction of triolein with caprylic and palmitic acids was performed using immobilized sn-1,3 specific lipase from Mucor miehei to produce a reduced calorie spreadable structured lipid (SL. Response surface methodology was applied to model and optimize the reaction conditions using a four-factor five-level central composite rotatable design. The selected factors were time (10-24 h, enzyme load (10-25 wt%, substrate mole ratio (Triolein:Caprylic acid:Palmitic acid, (1:1:1-1:2.5:2.5 and temperature (45-60 °C. The produced SLs were compared to fat extracts of commercial margarine in terms of melting profile and solid fat content (SFC. SL with a melting peak of 42 °C and SFC of 40.69% at 0 °C was very similar to soft margarines. The caloric value of this SL was determined as 37.74 kJ/g, theoretically. The optimum reaction conditions were found as reaction time 14 h; substrate mole ratio 1:2.1:2.1; temperature 58 °C; and enzyme load 15 wt%. Under optimum conditions, the product contained 29.68% COC, 25.47% POC, and 3.80% POP.

    La reacción de acidolísis de la trioleina con los ácidos caprílico y palmítico se realizó utilizando lipasa inmovilizada Mucor miehei, específica de sn-1, 3, para producir una grasa de untar baja en calorías compuesta de lípidos estructurados (SL. La metodología de superficie de respuesta se aplica para modelar y optimizar las condiciones de reacción utilizando un factor-cuatro y nivel-cinco de diseño central compuesto. Los factores seleccionados fueron el tiempo (10-24 h, la carga de enzima (10-25% en peso, la relación molar de sustratos (Trioleína:Ácido Caprílico:Ácido Palmítico, (1:1:1-1:2.5:2.5 y la temperatura (45-60 °C. Los SLs producidos se compararon con extractos de grasa de margarina comercial en términos de perfil de fusión y contenido de grasa sólida (SFC. El SL con un pico de fusión a 42 °C y SFC de 40,69% a 0 °C era muy similar a las

  14. The Importance of Parameter Variances, Correlations Lengths, and Cross-Correlations in Reactive Transport Models: Key Considerations for Assessing the Need for Microscale Information (Invited)

    Reimus, P. W.


    A process-oriented modeling approach is implemented to examine the importance of parameter variances, correlation lengths, and especially cross-correlations in contaminant transport predictions over large scales. It is shown that the most important consideration is the correlation between flow rates and retardation processes (e.g., sorption, matrix diffusion) in the system. If flow rates are negatively correlated with retardation factors in systems containing multiple flow pathways, then characterizing these negative correlation(s) may have more impact on reactive transport modeling than microscale information. Such negative correlations are expected in porous-media systems where permeability is negatively correlated with clay content and rock alteration (which are usually associated with increased sorption). Likewise, negative correlations are expected in fractured rocks where permeability is positively correlated with fracture apertures, which in turn are negatively correlated with sorption and matrix diffusion. Parameter variances and correlation lengths are also shown to have important effects on reactive transport predictions, but they are less important than parameter cross-correlations. Microscale information pertaining to contaminant transport has become more readily available as characterization methods and spectroscopic instrumentation have achieved lower detection limits, greater resolution, and better precision. Obtaining detailed mechanistic insights into contaminant-rock-water interactions is becoming a routine practice in characterizing reactive transport processes in groundwater systems (almost necessary for high-profile publications). Unfortunately, a quantitative link between microscale information and flow and transport parameter distributions or cross-correlations has not yet been established. One reason for this is that quantitative microscale information is difficult to obtain in complex, heterogeneous systems, so simple systems that lack the

  15. Measurement of the Slope Parameter for the eta->3pi0 Decay in the pp->pp eta Reaction

    Bashkanov, M; Calén, H; Capellaro, F; Clement, H; Demirörs, L; Ekström, C; Fransson, K; Gustafsson, L; Höistad, B; Ivanov, G; Jacewicz, M; Jiganov, E; Johansson, T; Keleta, S; Koch, I; Kullander, Sven; Kupsc, A; Kuznetsov, A; Marciniewski, P; Meier, R; Morosov, B; Oelert, W; Pauly, C; Petukhov, Yu P; Pettersson, H; Povtorejko, A; Ruber, R J M Y; Schönning, K; Scobel, W; Skorodko, T; Shwartz, B; Sopov, V; Stepaniak, J; Chernyshov, V; Engblom, P Thörngren; Tikhomirov, V; Turowiecki, A; Wagner, G J; Wiedner, U; Wolke, M; Yamamoto, A; Zabierowski, J; Złomańczuk, J


    The CELSIUS/WASA setup is used to measure the 3pi0 decay of eta mesons produced in pp interactions with beam kinetic energies of 1.36 and 1.45 GeV. The efficiency-corrected Dalitz plot and density distributions for this decay are shown, together with a fit of the quadratic slope parameter alpha yielding alpha = -0.026 +/- 0.010(stat) +/- 0.010(syst). This value is compared to recent experimental results and theoretical predictions.

  16. Cross section of reaction 181Ta(p,nγ)181W and the influence of the spin cut-off parameter on the cross section

    ZHANG Jun-Jie; HU Bi-Tao


    In this work,the program Cindy was modified to calculate the formation cross section of each energy level of residual nucleus 181W resulting from the reaction 181Ta(p,nγ)181 W.The concerned cross sections calculated at proton energy Ep=4.5-8.5 MeV agreed well with experimental results.The influence of the spin cut-off parameter in the energy level density model on the cross section was studied.The obtained results show that the influence of spin cut-off is obvious for lower energy levels.

  17. Effect of reaction parameters on the growth of MWCNTs using mesoporous Sb/MCM-41 by chemical vapour deposition

    Atchudan, R.; Pandurangan, A.; Subramanian, K.


    Mesoporous Si-MCM-41 molecular sieve was synthesized hydrothermally and different wt.% of Sb (1.0, 2.0, 3.0, 5.0, 10.0, 15.0 and 20.0) was loaded on it by wet impregnation method. The Sb/MCM-41 materials were characterized by various physico-chemical techniques such as XRD, TGA and TEM. The TEM image showed a honeycomb structure of the host material. They were used as catalytic templates for the growth of MWCNTs by CVD method with different temperatures at 700, 800, 900 and 1000 °C using acetylene as a carbon precursor. The reaction temperature was optimized for the better formation of MWCNTs and they were purified and then characterized by XRD, SEM, HR-TEM and Raman spectroscopy techniques. The formation of MWCNTs with diameter in the range of 4-6 nm was observed from HR-TEM. The good thermal stability and high productivity of catalyst observed in this study revealed that the 2 wt.% Sb loaded MCM-41 could be a promising support for the catalytic synthesis of MWCNTs at 800 °C by CVD method.

  18. Properties and reactions of manganese methylene complexes in the gas phase. The importance of strong metal: carbene bonds for effective olefin metathesis catalysts

    Stevens, A.E.; Beauchamp, J.L.


    In this communication the formation, properties and reactions of the gas phase carbenes MnCH/sub 2//sup +/, (CO)/sub 5/MnCH/sub 2//sup +/, and (CO)/sub 4/MnCH/sub 2//sup +/ are described. Reported results include observation of metathesis and abstraction reactions of the methylene ligand with olefins and the first experimental determination of metal-carbene bond dissociation energies. Important points are that: (a) metal-methylene bond energies are extremely strong; and (b) the Mn/sup +/-methylene bond energy is decreased substantially on addition of five carbonyls to the metal center. If the metal-carbene bond energy exceeds 100 kcal/mol, then transfer of the carbene to an olefin to give a cyclopropane or new olefin will be endothermic and thus will not compete with the metathesis reaction. In order to avoid low turnover numbers resulting from consumption of carbene intermediates, strong metal-carbene bonds are a desirable feature of practical metathesis catalysts. (DP)

  19. A new multimedia contaminant fate model for China: how important are environmental parameters in influencing chemical persistence and long-range transport potential?

    Zhu, Ying; Price, Oliver R; Tao, Shu; Jones, Kevin C; Sweetman, Andy J


    We present a new multimedia chemical fate model (SESAMe) which was developed to assess chemical fate and behaviour across China. We apply the model to quantify the influence of environmental parameters on chemical overall persistence (POV) and long-range transport potential (LRTP) in China, which has extreme diversity in environmental conditions. Sobol sensitivity analysis was used to identify the relative importance of input parameters. Physicochemical properties were identified as more influential than environmental parameters on model output. Interactive effects of environmental parameters on POV and LRTP occur mainly in combination with chemical properties. Hypothetical chemicals and emission data were used to model POV and LRTP for neutral and acidic chemicals with different KOW/DOW, vapour pressure and pKa under different precipitation, wind speed, temperature and soil organic carbon contents (fOC). Generally for POV, precipitation was more influential than the other environmental parameters, whilst temperature and wind speed did not contribute significantly to POV variation; for LRTP, wind speed was more influential than the other environmental parameters, whilst the effects of other environmental parameters relied on specific chemical properties. fOC had a slight effect on POV and LRTP, and higher fOC always increased POV and decreased LRTP. Example case studies were performed on real test chemicals using SESAMe to explore the spatial variability of model output and how environmental properties affect POV and LRTP. Dibenzofuran released to multiple media had higher POV in northwest of Xinjiang, part of Gansu, northeast of Inner Mongolia, Heilongjiang and Jilin. Benzo[a]pyrene released to the air had higher LRTP in south Xinjiang and west Inner Mongolia, whilst acenaphthene had higher LRTP in Tibet and west Inner Mongolia. TCS released into water had higher LRTP in Yellow River and Yangtze River catchments. The initial case studies demonstrated that SESAMe

  20. Stepped MS(All) Relied Transition (SMART): An approach to rapidly determine optimal multiple reaction monitoring mass spectrometry parameters for small molecules.

    Ye, Hui; Zhu, Lin; Wang, Lin; Liu, Huiying; Zhang, Jun; Wu, Mengqiu; Wang, Guangji; Hao, Haiping


    Multiple reaction monitoring (MRM) is a universal approach for quantitative analysis because of its high specificity and sensitivity. Nevertheless, optimization of MRM parameters remains as a time and labor-intensive task particularly in multiplexed quantitative analysis of small molecules in complex mixtures. In this study, we have developed an approach named Stepped MS(All) Relied Transition (SMART) to predict the optimal MRM parameters of small molecules. SMART requires firstly a rapid and high-throughput analysis of samples using a Stepped MS(All) technique (sMS(All)) on a Q-TOF, which consists of serial MS(All) events acquired from low CE to gradually stepped-up CE values in a cycle. The optimal CE values can then be determined by comparing the extracted ion chromatograms for the ion pairs of interest among serial scans. The SMART-predicted parameters were found to agree well with the parameters optimized on a triple quadrupole from the same vendor using a mixture of standards. The parameters optimized on a triple quadrupole from a different vendor was also employed for comparison, and found to be linearly correlated with the SMART-predicted parameters, suggesting the potential applications of the SMART approach among different instrumental platforms. This approach was further validated by applying to simultaneous quantification of 31 herbal components in the plasma of rats treated with a herbal prescription. Because the sMS(All) acquisition can be accomplished in a single run for multiple components independent of standards, the SMART approach are expected to find its wide application in the multiplexed quantitative analysis of complex mixtures.

  1. Importance of the support and the grade of Pt in the oxygen reduction reaction; Importancia del soporte y del grado del Pt en la reaccion de reduccion de oxigeno

    Enriquez M, O.; Fernandez V, S.M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)


    The technology of the fuel cells type Proton Exchange Membrane (PEM), needs to define clearly the influence of the different involved parameters, this is made in general using methods of electrochemical impedance, in which the involved reactions can be presupposed. Another form of making is identifying experimentally the influence of the different parameters. In this work the obtained results are reported with for the oxygen reduction reaction using as electro catalyst platinum analytical grade and fuel cell grade and like support graphite and vulcan. It was found that as much the support as the particle size modify the over potential for the oxygen reduction reaction (Orr). (Author)

  2. Study of castor oil polyurethane - poly(methyl methacrylate semi-interpenetrating polymer network (SIPN reaction parameters using a 2³ factorial experimental design

    Fernanda Oliveira Vieira da Cunha


    Full Text Available In this work was employed a 2³ factorial experiment design to evaluate the castor oil polyurethane-poly(methyl methacrylate semi-IPN synthesis. The reaction parameters used as independent variables were NCO/OH molar ratio, polyurethane polymerization time and methyl methacrylate (MMA content. The semi-IPNs were cured over 28 h using two thermal treatments. The polymers were characterized by infrared and Raman spectroscopy, thermal analysis and swelling profiles in n-hexane. The glass transition temperature (Tg and the swelling were more affect by the NCO/OH molar ratio variation. The semi-IPNs showed Tg from - 27 to - 6 °C and the swelling range was from 3 to 22%, according to the crosslink density. The IPN mechanical properties were dependent on the cure temperature and MMA content in it. Lower elastic modulus values were observed in IPNs cured at room temperature.

  3. Measurement of the spin correlation parameters All and Asl for the reaction pp-->dπ+ in the energy region 500-800 MeV

    Barlow, D. B.; Saha, A.; Seth, K. K.; Bhatia, T. S.; Glass, G.; Hiebert, J. C.; Kenefick, R. A.; Nath, S.; Northcliffe, L. C.; Tippens, W. B.; Jarmer, J. J.; Simmons, J. E.; Jeppesen, R. H.; Tripard, G. E.


    Angular distributions of the spin-correlation parameters Asl and All for the reaction pp-->π+d have been measured at pion center-of-mass angles 40°<=θ+π*<=130° at incident energies of 500, 650, and 800 MeV. Additional measurements of All were made at 600, 700, and 750 MeV. The results of the experiment are compared with the predictions of several unified coupled-channel calculations and partial-wave analyses. While the latest partial-wave analyses were found to fit the data reasonably well, all except one of the various model predictions not only do not fit the data well, but also tend to be in disagreement with each other. The data show no clear sign of a need for proposed dibaryon resonances.

  4. Collective phenomena in the Au (150 - 400 A MeV) + Au reactions at very low impact parameters; Phenomenes collectifs dans les reactions Au (150 - 400 A MeV) + Au a tres faibles parametres d`impact

    Roy, CH.


    In this work, we present a study concerning some collective phenomena in highly central Au (150 - 400 A MeV) + Au collisions, measured with the FOPI detector. The selection of the central reactions is performed by applying a criterion whose definition is based on the concept that low impact parameter reactions imply the non-existence of projectile and target remnants. The analysis of the center-of-mass polar angular distributions indicates that fragments (Z {<=} 3) are emitted preferentially in the direction transverse to the be beam axis. The shape of these distributions depends strongly on the degree of stopping of the nuclear matter. In the Quantum Molecular Dynamics (QMD) calculations, this phenomenon is mainly parameterized with the nucleon-nucleon cross-section ({sigma}{sub nn}). The comparison of the experimental polar angle distributions with those predicted by QMD suggests a value of 30 mb for {sigma}{sub nn} to reproduce the experimental trend observed at 150 A MeV incident energy. A simulation of a thermal source whose expansion is partially governed by a transverse flow indicates that the collective energy represents about 75 % of the total transverse energy ({approx} 65 % at 250 and 400 A MeV). (author). 102 refs.

  5. 环己烯催化环氧化反应体系热力学参数计算%Cyclohexene epoxidation reaction calculated thermodynamic parameters

    徐燏; 蒋登高


      The thermodynamics property of this catalytic epoxidation reaction system was analysed in this paper. Thermodynamic basic datas (the heat capacity at constant pressure, formation heat and gibbs free energy) of components in the reaction system were calculated by using Joback genetic contribution method. In the same time, Chemical reaction equilibrium constants were calculated. These are the important basic datas for the industrialized production process design.%  本文对所研究的催化环氧化反应体系进行了热力学性质的有关分析,采用 Joback 基因贡献法估算了反应体系中相关组分的恒压热容、生成热和吉布斯自由能等热力学基础数据,并计算了相关反应的平衡常数,为其工业化生产过程的设计提供了相关基础数据。

  6. Trajectory dynamics study of the Ar + CH4 dissociation reaction at high temperatures: the importance of zero-point-energy effects.

    Marques, J M C; Martínez-Núñez, E; Fernandez-Ramos, A; Vazquez, S A


    Large-scale classical trajectory calculations have been performed to study the reaction Ar + CH4--> CH3 +H + Ar in the temperature range 2500 energy surface used for ArCH4 is the sum of the nonbonding pairwise potentials of Hase and collaborators (J. Chem. Phys. 2001, 114, 535) that models the intermolecular interaction and the CH4 intramolecular potential of Duchovic et al. (J. Phys. Chem. 1984, 88, 1339), which has been modified to account for the H-H repulsion at small bending angles. The thermal rate coefficient has been calculated, and the zero-point energy (ZPE) of the CH3 product molecule has been taken into account in the analysis of the results; also, two approaches have been applied for discarding predissociative trajectories. In both cases, good agreement is observed between the experimental and trajectory results after imposing the ZPE of CH3. The energy-transfer parameters have also been obtained from trajectory calculations and compared with available values estimated from experiment using the master equation formalism; in general, the agreement is good.

  7. Radiation reaction in fusion plasmas.

    Hazeltine, R D; Mahajan, S M


    The effects of a radiation reaction on thermal electrons in a magnetically confined plasma, with parameters typical of planned burning plasma experiments, are studied. A fully relativistic kinetic equation that includes the radiation reaction is derived. The associated rate of phase-space contraction is computed and the relative importance of the radiation reaction in phase space is estimated. A consideration of the moments of the radiation reaction force show that its effects are typically small in reactor-grade confined plasmas, but not necessarily insignificant.

  8. Atlas of relations between climatic parameters and distributions of important trees and shrubs in North America—Modern data for climatic estimation from vegetation inventories

    Thompson, Robert S.; Anderson, Katherine H.; Pelltier, Richard T.; Strickland, Laura E.; Shafer, Sarah L.; Bartlein, Patrick J.


    Vegetation inventories (plant taxa present in a vegetation assemblage at a given site) can be used to estimate climatic parameters based on the identification of the range of a given parameter where all taxa in an assemblage overlap ("Mutual Climatic Range"). For the reconstruction of past climates from fossil or subfossil plant assemblages, we assembled the data necessary for such analyses for 530 woody plant taxa and eight climatic parameters in North America. Here we present examples of how these data can be used to obtain paleoclimatic estimates from botanical data in a straightforward, simple, and robust fashion. We also include matrices of climate parameter versus occurrence or nonoccurrence of the individual taxa. These relations are depicted graphically as histograms of the population distributions of the occurrences of a given taxon plotted against a given climatic parameter. This provides a new method for quantification of paleoclimatic parameters from fossil plant assemblages.

  9. Determination of the Most Important Soil Parameters Affecting the Availability of Phosphorus in Sistan Plain, Using Connection Weight Method in Neural Networks

    H. Mir


    Full Text Available Introduction: Phosphorus is important as an essential element in the production of agricultural products. On the other hand, its ability to induce essential micronutrient deficiency and its negative effects on the environment, have attracted more attention to this element. The knowledge of phosphorus availability conditions in the soil and consequently the accurate management of fertilizer consumption has a key role in the environmental protection. The degree of phosphorus absorption in the soil depends on the environmental factors, soil characteristics and compositions, and phosphorus fertilizer which have been used. The amount of available phosphorus in the soil has relationship with some of the physical and chemical properties of the soil. Since, the soil characteristics are important factors in the reaction of phosphorus in the soil, the present study aimed to investigate and determine the most important soil characteristics affecting the availability of phosphorus using regression and artificial neural network techniques, in the soils of Sistan plain. Materials and Methods: Soil sampling was done in 1.5×1.5 km intervals, from 0-30 cm depth, and 200 soil samples were taken. The amounts of available phosphorus and the soil properties including the percentages of clay , organic matter, calcium carbonate and the amount of pH were measured. Then, stepwise multivariate linear regression analysis was performed to determine linear relation between available phosphorus and the soil properties. In order to model and validate the regression model, respectively 80 and 20% of data were selected and entered into SPSS software. To train the neural network, multilayer perceptron (MLP network was used by MATLAB 7.6 package. In this type of network, 70% of data is selected for training, 15% for validation and 15% for testing the model. Levenberg-Marquardt algorithm and hyperbolic tangent (as a transfer function were used to train the network. The numbers of

  10. Importance of atmospheric aging in reactivity of mineral dust aerosol: a case study of heterogeneous reaction of gaseous hydrogen peroxide on processed mineral particles

    Y. Zhao


    Full Text Available Atmospheric aging and processing appears to alter physical and chemical properties of mineral dust aerosol and thus its role as reactive surface in the troposphere. Yet, previous studies in the atmosphere have mainly focused on the clean surfaces of mineral dust aerosol, and the reactivity of aged mineral aerosol toward atmospheric trace gases is still poorly recognized. This work presents the first laboratory investigation of heterogeneous reactions of gaseous hydrogen peroxide (H2O2, an important atmospheric oxidant, on the surface of HNO3 and SO2-processed alumina particles as surrogates of mineral dust aerosol aged by acidic trace gases as a function of relative humidity (RH and surface coverage of coatings. Pretreatment of the alumina surfaces with HNO3 and SO2 has a strong impact on its reactivity toward H2O2 uptake. On HNO3-processed particles, because of the dual role of the nitrate coating in modifying the reactivity of the particle surface, namely blocking oxide active sites but altering surface hygroscopicity, H2O2 uptake seems to decrease in some cases whereas increase in other cases, largely depending on RH and surface coverage of nitrate. On SO2-processed particles, the presence of adsorbed S(IV species appears to enhance the intrinsic reactivity of the alumina particles due to its affinity for H2O2, and the uptake of H2O2 increases by 40–80% in the range of RH from 25% to 92% relative to the unprocessed particles. However, when S(IV is completely oxidized to S(VI, the alumina surface is significantly deactivated and the measured uptake of H2O2 decreased markedly. The mechanisms for heterogeneous reactions of H2O2 with these processed particles are discussed, as well as its potential implications on tropospheric

  11. Benchmark study of the structural and spectroscopic parameters of the hydroxymethyl peroxy (HOCH2OO) radical and its decomposition reaction to HO2 and H2CO

    Linguerri, Roberto; Puzzarini, Cristina; Al Mogren, Muneerah Mogren; Francisco, Joseph S.; Hochlaf, Majdi


    The hydroxymethyl peroxy (HMOO) radical is a product of the oxidation of non-methane hydrocarbons. The present study provides the first accurate computational determination of critical spectroscopic features of the title radical that should aid in its experimental characterization. Structure, energetics, vibrational frequencies, and rotational parameters are reported for the three stable isomers on the ground electronic state of HMOO. While preliminary computations have been carried out using density functional theory as well as second-order Møller-Plesset perturbation theory, for the accurate structural and spectroscopic characterization we made use of coupled-cluster techniques, herewith considering both standard and explicitly correlated methods. The "CCSD(T)/CBS + CV" composite scheme, a state-of-the-art composite approach based on the coupled-cluster theory including single and double excitations together with a perturbative treatment of triples that accounts for extrapolation to the complete basis-set limit as well as core-valence correlation effects, is used to obtain accurate structural and energetic data, in particular for the decomposition reaction to HO2 and H2CO.

  12. The importance of molecular structures, endpoints' values, and predictivity parameters in QSAR research: QSAR analysis of a series of estrogen receptor binders.

    Li, Jiazhong; Gramatica, Paola


    Quantitative structure-activity relationship (QSAR) methodology aims to explore the relationship between molecular structures and experimental endpoints, producing a model for the prediction of new data; the predictive performance of the model must be checked by external validation. Clearly, the qualities of chemical structure information and experimental endpoints, as well as the statistical parameters used to verify the external predictivity have a strong influence on QSAR model reliability. Here, we emphasize the importance of these three aspects by analyzing our models on estrogen receptor binders (Endocrine disruptor knowledge base (EDKB) database). Endocrine disrupting chemicals, which mimic or antagonize the endogenous hormones such as estrogens, are a hot topic in environmental and toxicological sciences. QSAR shows great values in predicting the estrogenic activity and exploring the interactions between the estrogen receptor and ligands. We have verified our previously published model for additional external validation on new EDKB chemicals. Having found some errors in the used 3D molecular conformations, we redevelop a new model using the same data set with corrected structures, the same method (ordinary least-square regression, OLS) and DRAGON descriptors. The new model, based on some different descriptors, is more predictive on external prediction sets. Three different formulas to calculate correlation coefficient for the external prediction set (Q2 EXT) were compared, and the results indicated that the new proposal of Consonni et al. had more reasonable results, consistent with the conclusions from regression line, Williams plot and root mean square error (RMSE) values. Finally, the importance of reliable endpoints values has been highlighted by comparing the classification assignments of EDKB with those of another estrogen receptor binders database (METI): we found that 16.1% assignments of the common compounds were opposite (20 among 124 common

  13. On the impedance of galvanic cells XXVII. The temperature-dependence of the kinetic parameters of the hydrogen electrode reaction on mercury in concentrated HI

    Dekker, B.G.; Sluyters-Rehbach, M.; Sluyters, J.H.


    The impedance of a dropping mercury electrode in 57% HI (7.6 M) was measured at temperatures between −35° and +25°C. In a certain potential and temperature region, two reactions were found to be proceeding simultaneously: the reversible Hg/HgI4−2 reaction and the irreversible H+/H2(Hg) reaction. Ana

  14. Isotope modeling of nitric acid formation in the atmosphere using ISO-RACM: testing the importance of NO oxidation, heterogeneous reactions, and trace gas chemistry

    G. Michalski


    Full Text Available Here we present ISO-RACM, an isotope mass balance model that utilizes the Regional Atmospheric Chemistry Mechanism to predict Δ17O values in atmospheric nitrate. A large number of simulations were carried out that varied atmospheric parameters that are important in altering the magnitude and range of Δ17O values generated in photochemically produce nitrate. These parameters included temperature, relative humidity, actinic flux, aerosol surface area and chemical speciation, and three different N2O5 uptake parameterizations. Trace gas mixing ratios were also varied including CH4, CO, NOx, O3, volatile organic compounds and biogenic organic compounds. The model predicts that there are seasonal, latitudinal and diurnal variations in Δ17O values due to changes in actinic flux with lower values corresponding to higher actinic fluxes. There was also a minor positive correlation between higher Δ17O values and increased temperature. There were distinct differences in Δ17O depending on which N2O5 parameterization was used, mostly the result of changing relative humidity being a factor in two of the parameterization schemes. Changing CO and CH4 mixing ratios had negligible impact on Δ17O values but significant variation in magnitude and range were predicted with NOx, O3, and organic loading. High NOx and O3 generated high Δ17O with a narrow (10 ‰ range, while high organics led to low Δ17O values and a wider range of possible values. Implications for using Δ17O to evaluate NOx-NOy chemistry and aerosol formation processes are discussed, as is needed future research.

  15. Theoretical study of the influence of chemical reactions and physical parameters on the convective dissolution of CO2 in aqueous solutions

    Loodts, Vanessa; Rongy, Laurence; De Wit, Anne


    to the non reactive one. On the basis of a reaction-diffusion-convection model, we classify the various possible cases and show that the difference between the solutal expansion coefficients of the reactant and of the product governs the type of density profile building up in the aqueous solution and thus the stability of the system. By contrast to non reactive density profiles, reactive density profiles can feature a minimum that induces a delay of the buoyancy-driven convection. This work identifies the parameters that could influence the dissolution-driven convection in the aquifers, and thus impact the safety of the sequestration. In other words, this theoretical study shows that it is crucial to analyse the composition and reactivity of potential storage sites to choose those that will be most efficient for long-term CO2 sequestration.

  16. Study of the astrophysically important $\\boldsymbol{^{23}\\mathrm{Na}(\\alpha,p)^{26}\\mathrm{Mg}}$ and $\\boldsymbol{^{23}\\mathrm{Na}(\\alpha,n)^{26}\\mathrm{Al}}$ reactions

    Avila, M L; Almaraz-Calderon, S; Ayangeakaa, A D; Dickerson, C; Hoffman, C R; Jiang, C L; Kay, B P; Lai, J; Nusair, O; Pardo, R C; Santiago-Gonzalez, D; Talwar, R; Ugalde, C


    The $^{23}$Na$(\\alpha,p)^{26}$Mg and $^{23}$Na$(\\alpha,n)^{26}$Al reactions are important for our understanding of the $^{26}$Al abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using $^{4}$He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the $^{23}$Na$(\\alpha,p)^{26}$Mg and the $^{23}$Na$(\\alpha,n)^{26}$Al reactions are in good agreement with previous experiments, and with statistical model calculations.

  17. A Green Approach to the Synthesis of Biologically Important Indeno[2,1-e]pyrazolo[5,4-b]pyridines via Microwave-assisted Multi-component Reactions in Water


    A green approach to the synthesis of biologically important indeno[2,1-e]pyrazolo[5,4-b]pyridines was suc-cessfully realized via multi-component reactions of aldehyde, 3-methyl-l-phenyl-1H-pyrazol-5-amine and 1,3-indanedione in water under microwave irradiation without catalyst. This protocol has the prominent advantages of environmental-friendliness, short reaction time, excellent yields, low cost, easy operation as well as broad scope of applicability.

  18. Therapeutics interventions with anti-inflammatory creams in post radiation acute skin reactions: a systematic review of most important clinical trials.

    Koukourakis, Georgios V; Kelekis, Nikolaos; Kouvaris, John; Beli, Ivelina K; Kouloulias, Vassilios E


    The majority of cancer patients will receive radiation therapy treatment at some stage during their malignancy. An acute skin reaction represents a common post radiation side effect with different grade of severity. In order to investigate the optimal methods to prevent and manage acute skin reactions related to radiation therapy we have conducted a systematic review on this topic. It seems that skin washing, including gentle washing with water alone with or without mild soap, should be permitted in patients receiving radiation therapy, to prevent acute skin reaction. In addition, a low dose (i.e., 1%) corticosteroid cream may be beneficial in the reduction of itching and irritation. We have concluded that there is insufficient evidence to support or refute specific topical or oral agents for the prevention or management of acute skin reaction. There is a need for further research to review treatments that have produced promising results in the reviewed research studies and to evaluate other commonly recommended topical treatments. The purpose of this patent and literature review is to advocate the current management of acute skin reaction.

  19. Kinetic solvent effects on hydrogen abstraction reactions from carbon by the cumyloxyl radical. The importance of solvent hydrogen-bond interactions with the substrate and the abstracting radical.

    Salamone, Michela; Giammarioli, Ilaria; Bietti, Massimo


    A kinetic study of the hydrogen atom abstraction reactions from propanal (PA) and 2,2-dimethylpropanal (DMPA) by the cumyloxyl radical (CumO•) has been carried out in different solvents (benzene, PhCl, MeCN, t-BuOH, MeOH, and TFE). The corresponding reactions of the benzyloxyl radical (BnO•) have been studied in MeCN. The reaction of CumO• with 1,4-cyclohexadiene (CHD) also has been investigated in TFE solution. With CHD a 3-fold increase in rate constant (k(H)) has been observed on going from benzene, PhCl, and MeCN to TFE. This represents the first observation of a sizable kinetic solvent effect for hydrogen atom abstraction reactions from hydrocarbons by alkoxyl radicals and indicates that strong HBD solvents influence the hydrogen abstraction reactivity of CumO•. With PA and DMPA a significant decrease in k(H) has been observed on going from benzene and PhCl to MeOH and TFE, indicative of hydrogen-bond interactions between the carbonyl lone pair and the solvent in the transition state. The similar k(H) values observed for the reactions of the aldehydes in MeOH and TFE point toward differential hydrogen bond interactions of the latter solvent with the substrate and the radical in the transition state. The small reactivity ratios observed for the reactions of CumO• and BnO• with PA and DMPA (k(H)(BnO•)/k(H)(CumO•) = 1.2 and 1.6, respectively) indicate that with these substrates alkoxyl radical sterics play a minor role.

  20. Quantitative Microbial Risk Assessment Tutorial - SDMProjectBuilder: Import Local Data Files to Identify and Modify Contamination Sources and Input ParametersUpdated 2017

    Twelve example local data support files are automatically downloaded when the SDMProjectBuilder is installed on a computer. They allow the user to modify values to parameters that impact the release, migration, fate, and transport of microbes within a watershed, and control delin...

  1. Hydrogen atom abstraction selectivity in the reactions of alkylamines with the benzyloxyl and cumyloxyl radicals. The importance of structure and of substrate radical hydrogen bonding.

    Salamone, Michela; DiLabio, Gino A; Bietti, Massimo


    A time-resolved kinetic study on the hydrogen abstraction reactions from a series of primary and secondary amines by the cumyloxyl (CumO(•)) and benzyloxyl (BnO(•)) radicals was carried out. The results were compared with those obtained previously for the corresponding reactions with tertiary amines. Very different hydrogen abstraction rate constants (k(H)) and intermolecular selectivities were observed for the reactions of the two radicals. With CumO(•), k(H) was observed to decrease on going from the tertiary to the secondary and primary amines. The lowest k(H) values were measured for the reactions with 2,2,6,6-tetramethylpiperidine (TMP) and tert-octylamine (TOA), substrates that can only undergo N-H abstraction. The opposite behavior was observed for the reactions of BnO(•), where the k(H) values increased in the order tertiary < secondary < primary. The k(H) values for the reactions of BnO(•) were in all cases significantly higher than those measured for the corresponding reactions of CumO(•), and no significant difference in reactivity was observed between structurally related substrates that could undergo exclusive α-C-H and N-H abstraction. This different behavior is evidenced by the k(H)(BnO(•))/k(H)(CumO(•)) ratios that range from 55-85 and 267-673 for secondary and primary alkylamines up to 1182 and 3388 for TMP and TOA. The reactions of CumO(•) were described in all cases as direct hydrogen atom abstractions. With BnO(•) the results were interpreted in terms of the rate-determining formation of a hydrogen-bonded prereaction complex between the radical α-C-H and the amine lone pair wherein hydrogen abstraction occurs. Steric effects and amine HBA ability play a major role, whereas the strength of the substrate α-C-H and N-H bonds involved appears to be relatively unimportant. The implications of these different mechanistic pictures are discussed.

  2. A study of the atmospherically important reactions of dimethylsulfide (DMS) with I2 and ICl using infrared matrix isolation spectroscopy and electronic structure calculations.

    Beccaceci, Sonya; Armata, Nerina; Ogden, J Steven; Dyke, John M; Rhyman, Lydia; Ramasami, Ponnadurai


    The reactions of dimethylsulfide (DMS) with molecular iodine (I(2)) and iodine monochloride (ICl) have been studied by infrared matrix isolation spectroscopy by co-condensation of the reagents in an inert gas matrix. Molecular adducts of DMS + I(2) and DMS + ICl have also been prepared using standard synthetic methods. The vapour above each of these adducts trapped in an inert gas matrix gave the same infrared spectrum as that recorded for the corresponding co-condensation reaction. In each case, the infrared spectrum has been interpreted in terms of a van der Waals adduct, DMS : I(2) and DMS : ICl, with the aid of infrared spectra computed for their minimum energy structures at the MP2 level. Computed relative energies of minima and transition states on the potential energy surfaces of these reactions were used to understand why they do not proceed further than the reactant complexes DMS : I(2) and DMS : ICl. The main findings of this research are compared with results obtained earlier for the DMS + Cl(2) and DMS + Br(2) reactions, and the atmospheric implications of the conclusions are also considered.

  3. Optimization of the most important operational parameters of a pneumatic seeder using real-time monitoring for Cucumber and Watermelon seeds

    Z Abdolahzare


    Full Text Available Introduction: Since the application of pneumatic planters for seeds with different physical properties is growing, it is essential to evaluation the performance of these machines to improve the operating parameters under different pressures and forward speeds. To evaluate the performance of precision vacuum seeders numerous procedures of laboratory and field have been developed and their feed mechanism evaluation is of great importance. The use of instrumentation is essential in laboratory procedures. Many systems have been designed, using instrumentation, to be able to monitor seed falling trajectory and as a result, in those systems the precise place of falling seed in the seed bed could be determined. In this study, the uniformity of seed spacing of a seed drill was determined using of high speed camera with a frame rate of 480 frames s-1. So that, the uniformity of planting was statistically significant under the influence of the speed of seed metering rollers (Karayel et al., 2006. Singh et al. (2005 studied the effects of disk rotation speed, vacuum pressure and shape of seed entrance hole on planting spacing uniformity using uniformity indices under laboratory and field conditions. They reported miss index values were reduced as the pressure was increased but they were increased with increasing of the speed. The multiple indices on the other hand were low at higher speed but they were increased as the pressure was increased. Ground speed was affected by changes in engine speed and gear selection, both of which effect on amount of fan rotation speed for different pressures. The aim of this study was to identify and determine the effects of forward speed and optimum vacuum pressure amount of the pneumatic seeder. Materials and Methods: The pneumatic planter (Unissem was mounted on a tractor (MF399 and passed over the soil bin. Thus, the acquired data would be more reliable and practical. To do so, the tractor was equipped with electronic

  4. HIV-associated tuberculous lymphadenitis: the importance of polymerase chain reaction (PCR) as a complementary tool for the diagnosis of tuberculosis - a study of 104 patients.

    Cortez, Marcio Valle; Oliveira, Cintia Mara Costa de; Monte, Rossicléia Lins; Araújo, José Ribamar de; Braga, Bruna Backsmann; Reis, Débora Zotteli dos; Ferreira, Luis Carlos de Lima; Moraes, Milton Ozório; Talhari, Sinésio


    Lymphadenitis is common in HIV-positive patients. Diagnosis of the infections associated with this condition is complex, particularly in the case of tuberculosis. Rapid and specific detection of Mycobacterium tuberculosis (M. tuberculosis) is fundamental in ensuring adequate treatment. In addition, frequent causes of lymphadenitis such as those associated with lymphoma and histoplasmosis, among others, must be eliminated as possible causes. To evaluate the accuracy of polymerase chain reaction as a tool for the diagnosis of lymphadenitis resulting from M. tuberculosis. In this study, a protocol was developed using the following procedures: direct microscopy using Ziehl-Neelsen staining, culture in Lowenstein-Jensen medium, histology and polymerase chain reaction. A total of 104 patients were included in the study. According to histopathology, 38 patients (36%) were found to have nonspecific chronic lymphadenitis, 27 (26%) had tuberculous lymphadenitis, 11 patients (10.5%) had lymphoma and 9 (8.7%) had histoplasmosis. When Lowenstein-Jensen culture was performed, positive tests for tuberculous lymphadenitis increased by 30%. With polymerase chain reaction, M. tuberculosis DNA was detected in 6 out of 38 samples of non-specific chronic lymphadenitis. Three of these patients were followed up, developed symptoms of tuberculosis and were cured following specific treatment. The data obtained in this study suggest that all cases of lymphadenopathies should be submitted to histopathology, Lowenstein-Jensen or Ogawa culture and polymerase chain reaction. Polymerase chain reaction may prove to be useful in providing an early and accurate detection of cases of extrapulmonary tuberculosis in HIV-positive patients with lymphadenopathies, avoiding empirical treatment and the possible development of resistant strains.

  5. The effect of fuel/air mixer design parameters on the continuous and discrete phase structure in the reaction-stabilizing region

    Ateshkadi, Arash

    The demands on current and future aero gas turbine combustors are demanding a greater insight into the role of the injector/dome design on combustion performance. The structure of the two-phase flow and combustion performance associated with practical injector/dome hardware is thoroughly investigated. A spray injector with two radial inflow swirlers was custom-designed to maintain tight tolerances and strict assembly protocol to isolate the sensitivity of performance to hardware design. The custom set is a unique modular design that (1) accommodates parametric variation in geometry, (2) retains symmetry, and (3) maintains effective area. Swirl sense and presence of a venturi were found to be the most influential on fuel distribution and Lean Blowout. The venturi acts as a fuel-prefilming surface and constrains the highest fuel mass concentration to an annular ring near the centerline. Co-swirl enhances the radial dispersion of the continuous phase and counter-swirl increases the level of mixing that occurs in the downstream region of the mixer. The smallest drop size distributions were found to occur with the counter-swirl configuration with venturi. In the case of counter-swirl without venturi the high concentration of fluid mass is found in the center region of the flow. The Lean Blowout (LBO) equivalence ratio was lower for counter-swirl due to the coupling of the centerline recirculation zone with the location of high fuel concentration emanating from smaller droplets. In the co-swirl configuration a more intense reaction was found near the mixer exit leading to the lowest concentration of NOx, CO and UHC. An LBO model with good agreement to the measured values was developed that related, for the first time, specific hardware parameters and operating condition to stability performance. A semi-analytical model, which agreed best with co-swirl configurations, was modified and used to describe the axial velocity profile downstream of the mixer exit. The

  6. Validation of SMOS L1C and L2 Products and Important Parameters of the Retrieval Algorithm in the Skjern River Catchment, Western Denmark

    Bircher, Simone; Skou, Niels; Kerr, Yann H.


    The Soil Moisture and Ocean Salinity (SMOS) satellite with a passive L-band radiometer monitors surface soil moisture. In addition to soil moisture, vegetation optical thickness tau(NAD) is retrieved (L2 product) from brightness temperatures (T-B, L1C product) using an algorithm based on the L...... and the most sensitive algorithm parameters were analyzed by network and airborne campaign data collected within one SMOS pixel (44 km diameter). The SMOS retrieval is based on the prevailing low vegetation class. For the L1C comparison, T-B's were calculated from in situ soil moisture using L-MEB. Consistent......-band Microwave Emission of the Biosphere (L-MEB) model with initial guesses on the two parameters (derived from ECMWF products and ECOCLIMAP Leaf Area Index, respectively) and other auxiliary input. This paper presents the validation work carried out in the Skjern River Catchment, Denmark. L1C/L2 data...

  7. 重大军事任务下军人急性应激反应特点%CharacteristiCs of Soldiers' Acute Stress Reaction Under Important Military Tasks

    朱霞; 杨业兵; 张华军; 江源; 黄鹏


    目的:揭示军人在执行重大军事任务期间急性应激反应特点。方法:采用《急性应激反应量表》对执行重大军事任务下军人的心理反应进行测试和对比。结果:五种重大军事任务下,军人的急性应激反应各维度及总反应指数均存在显著性差异,急性应激反应主要表现在认知改变和情绪变化方面;执行任务过程中的暴露因素影响军人急性应激反应的程度;军人急性应激反应各症状与工作效率降低呈显著正相关,影响工作效率的因素主要为生理反应、焦虑、注意减退和自责。结论:随着执行重大任务的性质和暴露因素不同,军人急性应激反应特点存在显著差异,并对军事作业效能产生明显的影响。%In the 21st century, there have been many unexpected events in which the destructions of life and property go hand in hand with harm to people's mentality. After the occurrence of an incident, soldiers, often the timeliest rescuers, are not only burdened with heavy, tense rescue missions, but alse bear the uncertainty of events, life safety in high risks, and the strong shock of the tragic situation. In fulfilling their the major unexpected tasks, acute stress reaction, often results in a great impact on soldiers' mentality. Relevant studies have become a hot issue of military psychological research. To reveal the characteristics of soldiers' acute stress reaction when fulfilling major military tasks, we used the "acute stress reaction scale" to test them and then c(~npared each task. The scale, which had good reliability and validity, contained 112 items, five estimate dimensions, namely, cognitive change, behavior change, emotional response, physiological response and pathological change, and one efficiency standard, work efficiency. Their overall average is a total response index which suggests the severity of acute stress reaction. We used the scale to test 2627 soldiers

  8. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    Minenkov, Yury


    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  9. Distributed Parameter Modelling Applications


    Here the issue of distributed parameter models is addressed. Spatial variations as well as time are considered important. Several applications for both steady state and dynamic applications are given. These relate to the processing of oil shale, the granulation of industrial fertilizers and the d......Here the issue of distributed parameter models is addressed. Spatial variations as well as time are considered important. Several applications for both steady state and dynamic applications are given. These relate to the processing of oil shale, the granulation of industrial fertilizers...... sands processing. The fertilizer granulation model considers the dynamics of MAP-DAP (mono and diammonium phosphates) production within an industrial granulator, that involves complex crystallisation, chemical reaction and particle growth, captured through population balances. A final example considers...

  10. The importance of the toxicological analysis in newborns: clearing the case of a tetralogy of Fallot with a paradoxical reaction to 1-hydroxymidazolam

    Cristiano Ialongo


    Full Text Available Short half-life benzodiazepines like midazolam are used as premedication to relieve intra-partum pain, and are known to have no adverse effects to the newborn. However, such short-acting drugs are known to induce paradoxical reactions when their concentration is abnormally elevated respect to the age of the subject. In a 1 day-old newborn, admitted to the Cardiology Unit of the “Bambino Gesù” Children Hospital of Rome due to a prenatal diagnosis of tetralogy of Fallot, a paradoxical reaction with a spontaneous resolution was observed. The analysis of urines, performed by gas chromatography/mass spectrometry after a drug screening, showed the presence of the active metabolite 1-hydroxymidazolam at 9.7 µg/mL with no detectable trace of its precursor midazolam and of the alternative metabolite 4-hydroxymidazolam. On the basis of these evidences, we speculated that 1-hydroxymidazolam, produced by the mother’s liver enzymes, passed to the newborn whose reduced volume of distribution (for the shunted circulation favoured the onset of such a reaction. Hence, the toxicological approach should be carried out on both mother and child wherever the clinical picture may appear unexplainable or does not match with the other findings collected.

  11. Importância dos parâmetros seminais nos resultados de inseminação intra-uterina Importance of seminal parameters for intrauterine insemination outcomes

    Edson Borges Junior


    Full Text Available OBJETIVOS: analisar a relevância dos parâmetros seminais nos resultados dos ciclos de inseminação intra-uterina (IIU em pacientes com causa masculina de infertilidade e salientar o caráter prognóstico de cada parâmetro para o sucesso da técnica. MÉTODOS: duzentos e trinta e nove ciclos de IIU (155 casais foram analisados durante período de 15 meses. Todos as pacientes foram submetidas à indução da ovulação de acordo com protocolos do I Consenso Brasileiro de Indução de Ovulação. A análise seminal foi realizada de acordo com os critérios da Organização Mundial da Saúde (OMS para parâmetros como concentração e motilidade e critério estrito de Kruger para avaliação da morfologia. O preparo da amostra para IIU foi realizado por meio de gradientes descontínuos de densidade (ISolate®. Foram formados dois grupos de pacientes de acordo com o resultado de gestação: grupo G - gestação positiva e grupo NG - gestação negativa. RESULTADOS: não houve diferença significativa nos valores obtidos relacionados à concentração total de espermatozóides/mL de sêmen, motilidade total, motilidade de formas progressivas antes e depois do processamento seminal. Quando a morfologia estrita de Kruger foi comparada entre os dois grupos, diferenças significativas foram encontradas (grupo G=10,6% de formas normais; grupo NG=6,4% de formas normais; pPURPOSE: to analyze the influence of seminal parameters on intrauterine insemination (IUI outcomes in patients with male factor and to emphasize the predictive value of each parameter for the successful result. METHODS: two hundred and thirty-nine IUI cycles (155 couples were analyzed for 15 months. Female patients were submitted to ovary hyperstimulation according to the "I Consenso Brasileiro de Indução de Ovulação". Seminal analysis based on the World Health Organization (WHO for sperm concentration and motility was used and sperm morphology was evaluated according to Kruger

  12. The effect of a non-steroidal anti-inflammatory drug on two important predictors for accidental falls: postural balance and manual reaction time. A randomized, controlled pilot study.

    Hegeman, J.; Nienhuis, B.; Bemt, B.J.F van den; Weerdesteijn, V.G.M.; Limbeek, J. van; Duysens, J.E.J.


    Accidental falls in older individuals are a major health and research topic. Increased reaction time and impaired postural balance have been determined as reliable predictors for those at risk of falling and are important functions of the central nervous system (CNS). An essential risk factor for fa


    S.S. Prasad*, Anita Sinha, Kamlesh Patel, Chandresh Dumatar, S.K. Vajpeyee and V.H. Bhavsar


    Full Text Available The aim of this study was to investigate the possibility of gastric-ulceration by ginger-juice (Zingiber officinale Roscoe in rat. (A Albino rats (n=6-12 were administered G.J at two doses (2ml & 4 ml/rat, p.o as single administration and chronic treatment over period of 30 days. Following this assessment was done for possible gastric lesion. Effect of treatment with G.J acutely and chronically (30 days administered, was assessed. Parameters used during assessment were total acidity, gastric volume & pH and ulcer index ‘UI’ (acute and chronic. Acute & chronic administration of G.J (2ml & 4ml/rat, p.o caused an increase in pH and vol. of gastric content, a decrease in total acidity and no significant change in ulcer index.

  14. Photo degradation of methyl orange an azo dye by advanced Fenton process using zero valent metallic iron: influence of various reaction parameters and its degradation mechanism.

    Gomathi Devi, L; Girish Kumar, S; Mohan Reddy, K; Munikrishnappa, C


    Advanced Fenton process (AFP) using zero valent metallic iron (ZVMI) is studied as a potential technique to degrade the azo dye in the aqueous medium. The influence of various reaction parameters like effect of iron dosage, concentration of H(2)O(2)/ammonium per sulfate (APS), initial dye concentration, effect of pH and the influence of radical scavenger are studied and optimum conditions are reported. The degradation rate decreased at higher iron dosages and also at higher oxidant concentrations due to the surface precipitation which deactivates the iron surface. The rate constant for the processes Fe(0)/UV and Fe(0)/APS/UV is twice compared to their respective Fe(0)/dark and Fe(0)/APS/dark processes. The rate constant for Fe(0)/H(2)O(2)/UV process is four times higher than Fe(0)/H(2)O(2)/dark process. The increase in the efficiency of Fe(0)/UV process is attributed to the cleavage of stable iron complexes which produces Fe(2+) ions that participates in cyclic Fenton mechanism for the generation of hydroxyl radicals. The increase in the efficiency of Fe(0)/APS/UV or H(2)O(2) compared to dark process is due to continuous generation of hydroxyl radicals and also due to the frequent photo reduction of Fe(3+) ions to Fe(2+) ions. Though H(2)O(2) is a better oxidant than APS in all respects, but it is more susceptible to deactivation by hydroxyl radical scavengers. The decrease in the rate constant in the presence of hydroxyl radical scavenger is more for H(2)O(2) than APS. Iron powder retains its recycling efficiency better in the presence of H(2)O(2) than APS. The decrease in the degradation rate in the presence of APS as an oxidant is due to the fact that generation of free radicals on iron surface is slower compared to H(2)O(2). Also, the excess acidity provided by APS retards the degradation rate as excess H(+) ions acts as hydroxyl radical scavenger. The degradation of Methyl Orange (MO) using Fe(0) is an acid driven process shows higher efficiency at pH 3. The

  15. The base catalysed hydrolysis of methyl paraben: a test reaction for flow microcalorimeters used for determination of both kinetic and thermodynamic parameters

    O' Neill, M.A.A.; Beezer, A.E.; Labetoulle, C.; Nicolaides, L.; Mitchell, J.C.; Orchard, J.A.; Connor, J.A.; Kemp, R.B.; Olomolaiye, D


    The results of an inter/intra-laboratory study into a test and reference reaction for isothermal microcalorimeters, the imidazole catalysed hydrolysis of triacetin, have been reported in a recent paper [Thermochim. Acta 380 (2001) 13]. The results and conclusions drawn from this study have been extended to a consideration of the need for a similar test and reference reaction for isothermal microcalorimeters operating in flow mode. This paper reports the findings of a preliminary inter/intra-laboratory study of the base catalysed hydrolysis of methyl 4-hydroxy benzoate (methyl paraben) and its suitability as a test and reference reaction. The derived values for the hydrolysis reaction were (3.15{+-}0.11)x10{sup -4} s{sup -1} and -50.5{+-}4.3 kJ mol{sup -1} for the rate constant and enthalpy, respectively. It is also reported how such a test and reference reaction can be used to validate the thermal output from a LKB 10-700-1 and Thermometric Thermal Activity Monitor (TAM) 2277-202 flow microcalorimeters.

  16. Analysis of kinetic reaction mechanisms

    Turányi, Tamás


    Chemical processes in many fields of science and technology, including combustion, atmospheric chemistry, environmental modelling, process engineering, and systems biology, can be described by detailed reaction mechanisms consisting of numerous reaction steps. This book describes methods for the analysis of reaction mechanisms that are applicable in all these fields. Topics addressed include: how sensitivity and uncertainty analyses allow the calculation of the overall uncertainty of simulation results and the identification of the most important input parameters, the ways in which mechanisms can be reduced without losing important kinetic and dynamic detail, and the application of reduced models for more accurate engineering optimizations. This monograph is invaluable for researchers and engineers dealing with detailed reaction mechanisms, but is also useful for graduate students of related courses in chemistry, mechanical engineering, energy and environmental science and biology.

  17. Mechanism of adsorption of single and double stranded DNA on gold and silver nanoparticles: Investigating some important parameters in bio-sensing applications.

    Farkhari, Nahid; Abbasian, Sara; Moshaii, Ahmad; Nikkhah, Maryam


    The mechanism of adsorption of single and double stranded DNAs on colloidal gold and silver nanoparticles has been studied by measuring the resistance of the nanoparticles, surrounded by various oligonucleotides, against salt induced aggregation. It is shown that both single and double stranded DNAs can be adsorbed on the metal nanoparticles and the adsorption strength is determined by the interaction between various bases of DNA and the nanoparticles. By changing the salt concentration, the difference between adsorption of various DNA strands on the nanoparticles can be specified. The results indicate that a key parameter in success of a sensing assay of DNA hybridization is the salt concentration which should be greater than a minimum threshold depending on the nanoparticles characteristics. We have also investigated the interaction mechanism between various DNA bases with the metal nanoparticles. For both gold and silver nanoparticles, adenine has the highest and thymine has the lowest attachment to the nanoparticles. From surface enhanced Raman spectroscopy (SERS) data of various bases in the presence of gold nanoparticles, the probable interaction points in the bases with the nanoparticles have been determined, which are mainly the nitrogen sites of these oligonucleotides.

  18. Hydrodynamical Simulations to Determine the Feeding Rate of Black Holes by the Tidal Disruption of Stars: The Importance of the Impact Parameter and Stellar Structure

    Guillochon, James


    The disruption of stars by supermassive black holes has been linked to more than a dozen flares in the cores of galaxies out to redshift $z \\sim 0.4$. Modeling these flares properly requires a prediction of the rate of mass return to the black hole after a disruption. Through hydrodynamical simulation, we show that aside from the full disruption of a solar mass star at the exact limit where the star is destroyed, the common assumptions used to estimate $\\dot{M}(t)$, the rate of mass return to the black hole, are largely invalid. While the analytical approximation to tidal disruption predicts that the least-centrally concentrated stars and the deepest encounters should have more quickly-peaked flares, we find that the most-centrally concentrated stars have the quickest-peaking flares, and the trend between the time of peak and the impact parameter for deeply-penetrating encounters reverses beyond the critical distance at which the star is completely destroyed. We also show that the most-centrally concentrated ...

  19. Photocatalytic hydrogen production on SOLECTRO {sup registered} titanium dioxide layers. Investigation of reaction processes and of the influence of various reaction parameters; Photokatalytische Wasserstoffgewinnung an SOLECTRO {sup registered} -Titandioxidschichten. Untersuchung der ablaufenden Reaktionsprozesse und des Einflusses verschiedener Reaktionsparameter

    Keil, Doreen


    The dissertation investigated the reaction processes of photocatalytic hydrogen production on palladium and copper-doped SOLECTRO {sup registered} titanium dioxide layers. Methanol was used as electron donor. [German] In dieser Doktorarbeit werden die ablaufenden Reaktionsprozesse der photokatalytischen Wasserstoffentwicklung an palladium- und kupferbeladenen SOLECTRO {sup registered} -Titandioxidschichten untersucht. Als Elektronendonator wurde Methanol verwendet.


    段毅文; 陈丽萍; 斯钦达莱


    分形学是一个十分重要的自然分支.为了描述一个真实多孔固体催化剂颗粒中等温扩散催化反应的特性,分形几何对称模型的分形参数m是至关重要的.单颗粒化学反应模型参数m的一个关系已被得到.而且这个模型参数m的一些影响因素也已经搞清楚.%Fractals is a very important natural science branch.The fractal parameter m in fractal geometry symmetry model is a very important one in order to describe the fractal characteristics for isothermal diffusion catalysis reactions within a porous solid catalyst particle.A relationship,that for the parameter m in single particle chemical reaction engineering,has been obtained.And some influence factors on the parameter m have been made clear.

  1. Efficient catalysis of Suzuki–Miyaura C-C coupling reactions with palladium(II) complexes of partially hydrolyzed bisimine ligands: A process important in environment context

    Kumar, Arun; Rao, Gyandshwar Kumar; Saleem, Fariha; Kumar, Rupesh; Singh, Ajai K., E-mail:


    Graphical abstract: - Highlights: • Syntheses of hexadentate chalcogenated (S/Se/Te) bisimine ligands. • Reactions with Pd(II) resulted in their metal promoted partial hydrolysis to 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-EAr]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} and ArE-(CH{sub 2}){sub 2}-NH{sub 2}. • Isolation and characterization of Pd(II) complexes of products of hydrolysis. • Exploration of catalytic potential of Pd(II) complexes for Suzuki coupling. • Highest catalytic efficiency of complex of Se based ligand which shows activity for coupling aryl chlorides. - Abstract: Potentially hexadentante [O{sup −},N,E:E,N,O{sup −}] chalcogenated bisimine ligands L1–L3 have been synthesized by reaction of 1,1′-(4,6-dihydroxy-1,3-phenylene)bisethanone with H{sub 2}N-(CH{sub 2}){sub 2}-S-Ph, H{sub 2}N-(CH{sub 2}){sub 2}-Se-Ph and H{sub 2}N-(CH{sub 2}){sub 2}-Te-C{sub 6}H{sub 4}-4-OMe respectively. The L1–L3 react with Na{sub 2}PdCl{sub 4} resulting in their partial hydrolysis, which appears to be metal-promoted. Of the two [-(CH{sub 3})C=N-(CH{sub 2}){sub 2}-EAr] fragments of L1–L3, one is converted to -(CH{sub 3})C=O and H{sub 2}N-(CH{sub 2}){sub 2}-E-Ar eliminated. The hydrolysis products 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-SPh]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} (L1′), 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-SePh]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} (L2′) and 1-[C(CH{sub 3})=N-(CH{sub 2}){sub 2}-Te-C{sub 6}H{sub 4}-4-OMe]-3-[C(CH{sub 3})=O]-4,6-[OH]{sub 2}C{sub 6}H{sub 2} (L3′) have formed complexes [PdCl(L′–H)] (1, 3 and 5). The other product of hydrolysis H{sub 2}N-(CH{sub 2}){sub 2}-E-Ar (L″) reacted with Na{sub 2}PdCl{sub 4} yielding the complexes [PdL”Cl{sub 2}] (2, 4 and 6). All the complexes (1–6) were found thermally and air stable. Complexes 1, 3 and 5 have been investigated as catalysts for Suzuki–Miyaura C-C coupling reactions. The catalytic activities of 1 and 3 which are

  2. New parameters for evaluating the quality of commercial krill oil capsules from the aspect of lipid oxidation and non-enzymatic browning reactions

    Lu, Henna Fung Sieng; Bruheim, Inge; Jacobsen, Charlotte


    different commercial krill oil capsules through parameters such as: investigation of chemical compositions (bioactive compounds such as phospholipids, n-3 polyunsaturated fatty acids, antioxidants), hydrophobic pyrroles, and volatile profiles (lipid and Strecker-derived volatiles, pyridines, pyrazines...

  3. Direct conversion of natural gas into COx-free hydrogen and MWCNTs over commercial Ni–Mo/Al2O3 catalyst: Effect of reaction parameters

    Ahmed E. Awadallah


    Full Text Available A commercial hydrotreating nickel molybdate/alumina catalyst was used for the direct conversion of natural gas (NG into COx-free hydrogen and a co-valuable product of multi-walled carbon nanotubes (MWCNTs. The catalytic runs were carried out atmospherically in a fixed-bed flow reactor. The effect of reaction temperature between 600 and 800 °C, and dilution of the NG feed with nitrogen as well as pretreatment of the catalyst with hydrogen were investigated. At a reaction temperature of 700 °C and dilution ratio of NG/N2 = 20/30, the optimum yield of H2 (∼80% was obtained with higher longevity. However, using the feed ratio of NG/N2 = 30/20, the optimum yield of MWCNTs was obtained (669%. X-ray diffraction pattern for the catalyst after the reaction showed that the MWCNTs were grown on the catalyst at all reaction temperatures under study. TEM pictures revealed that the as-grown MWCNTs at 600, 650 and 800 °C are short and long with a low graphitization degree. At 700 °C a forest of condensed CNTs is formed, whereas both carbon nanofibers and CNTs were formed at 750 °C.

  4. Determination of Kinetic Parameters and Metal Ions in Urea-Urease System Based on the Biochemical Reaction Heat Induced Laser Beam Deflection


    A new analytical method for the determination of urea-urease system based on biochemical reaction heat induced laser beam deflection is presented in this paper. With the method, the Michaelis constant (Km) of urease and apparent inhibition constant (Ki) of some metal ion inhibitors were measured respectively. This method was also used for the quantitative determination of metal ions with satisfactory result.

  5. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation.

    Minenkov, Yury; Bistoni, Giovanni; Riplinger, Christoph; Auer, Alexander A; Neese, Frank; Cavallo, Luigi


    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol(-1) if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol(-1), indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.




    The importance of solvation in determining substituent effects of alkyl groups has been assessed in a quantitative study of the medium effects of ethanol and 1-propanol on the neutral hydrolysis of 18 1-acyl-(3-substituted)-1,2,4-triazoles in highly aqueous solutions. The dependence of the pseudo-fi

  7. The influence of anionic ligands on stereoisomerism of Ru carbenes and their importance to efficiency and selectivity of catalytic olefin metathesis reactions.

    Torker, Sebastian; Khan, R Kashif M; Hoveyda, Amir H


    Investigations detailed herein provide insight regarding the mechanism of stereochemical inversion of stereogenic-at-Ru carbene complexes through a nonolefin metathesis-based polytopal rearrangement pathway. Computational analyses (DFT) reveal that there are two key factors that generate sufficient energy barriers that are responsible for the possibility of isolation and characterization of high-energy, but kinetically stable, intermediates: (1) donor-donor interactions that involve the anionic ligands and the strongly electron donating carbene groups and (2) dipolar effects arising from the syn relationship between the anionic groups (iodide and phenoxide). We demonstrate that a Brønsted acid lowers barriers to facilitate isomerization, and that the positive influence of a proton source is the result of its ability to diminish the repulsive electronic interactions originating from the anionic ligands. The implications of the present studies regarding a more sophisticated knowledge of the role of anionic units on the efficiency of Ru-catalyzed olefin metathesis reactions are discussed. The electronic basis for the increased facility with which allylic alcohols participate in olefin metathesis processes will be presented as well. Finally, we illustrate how a better understanding of the role of anionic ligands has served as the basis for successful design of Ru-based Z-selective catalysts for alkene metathesis.

  8. Importance of π-stacking interactions in the hydrogen atom transfer reactions from activated phenols to short-lived N-oxyl radicals.

    Mazzonna, Marco; Bietti, Massimo; DiLabio, Gino A; Lanzalunga, Osvaldo; Salamone, Michela


    A kinetic study of the hydrogen atom transfer from activated phenols (2,6-dimethyl- and 2,6-di-tert-butyl-4-substituted phenols, 2,2,5,7,8-pentamethylchroman-6-ol, caffeic acid, and (+)-cathechin) to a series of N-oxyl radical (4-substituted phthalimide-N-oxyl radicals (4-X-PINO), 6-substituted benzotriazole-N-oxyl radicals (6-Y-BTNO), 3-quinazolin-4-one-N-oxyl radical (QONO), and 3-benzotriazin-4-one-N-oxyl radical (BONO)), was carried out by laser flash photolysis in CH3CN. A significant effect of the N-oxyl radical structure on the hydrogen transfer rate constants (kH) was observed with kH values that monotonically increase with increasing NO-H bond dissociation energy (BDENO-H) of the N-hydroxylamines. The analysis of the kinetic data coupled to the results of theoretical calculations indicates that these reactions proceed by a hydrogen atom transfer (HAT) mechanism where the N-oxyl radical and the phenolic aromatic rings adopt a π-stacked arrangement. Theoretical calculations also showed pronounced structural effects of the N-oxyl radicals on the charge transfer occurring in the π-stacked conformation. Comparison of the kH values measured in this study with those previously reported for hydrogen atom transfer to the cumylperoxyl radical indicates that 6-CH3-BTNO is the best N-oxyl radical to be used as a model for evaluating the radical scavenging ability of phenolic antioxidants.

  9. Immunological reaction of the demyelinating Semliki Forest virus with immune serum to glycolipids and its possible importance to central nervous system viral auto-immune disease.

    Webb, H E; Mehta, S; Gregson, N A; Leibowitz, S


    The avirulent demyelinating strain A7(74) of Semliki Forest virus after passage through mouse brain in vivo and mouse brain cell cultures has been shown to react immunologically with immune sera against galactocerebroside, glucocerebroside, total ganglioside and GT1b ganglioside but not against myelin or sulphatide . Semliki Forest virus is known to take host membrane glycolipid into its coat. The importance of the findings is discussed in relation to the production of a possible anti-brain cell auto-immune phenomenon and its implication in a disease such as multiple sclerosis.

  10. Enthalpy/entropy driven activation of the first interquinone electron transfer in bacterial photosynthetic reaction centers embedded in vesicles of physiologically important phospholipids.

    Milano, Francesco; Dorogi, Márta; Szebényi, Kornélia; Nagy, László; Maróti, Péter; Váró, György; Giotta, Livia; Agostiano, Angela; Trotta, Massimo


    The thermodynamics and kinetics of light-induced electron transfer in bacterial photosynthetic RCs are sensitive to physiologically important lipids (phosphatidylcholine, cardiolipin and phosphatidylglycerol) in the environment. The analysis of the temperature-dependence of the rate of the P(+)Q(A)(-)Q(B)-->P(+)Q(A)Q(B)(-) interquinone electron transfer revealed high enthalpy change of activation in zwitterionic or neutral micelles and vesicles and low enthalpy change of activation in vesicles constituted of negatively charged phospholipids. The entropy change of activation was compensated by the changes of enthalpy, thus the free energy change of activation ( approximately 500 meV) did not show large variation in vesicles of different lipids.

  11. Comparison of the accuracy of Hybrid Capture II and polymerase chain reaction in detecting clinically important cervical dysplasia: a systematic review and meta-analysis.

    Luu, Hung N; Dahlstrom, Kristina R; Mullen, Patricia Dolan; VonVille, Helena M; Scheurer, Michael E


    The effectiveness of screening programs for cervical cancer has benefited from the inclusion of Human papillomavirus (HPV) DNA assays; which assay to choose, however, is not clear based on previous reviews. Our review addressed test accuracy of Hybrid Capture II (HCII) and polymerase chain reaction (PCR) assays based on studies with stronger designs and with more clinically relevant outcomes. We searched OvidMedline, PubMed, and the Cochrane Library for English language studies comparing both tests, published 1985-2012, with cervical dysplasia defined by the Bethesda classification. Meta-analysis provided pooled sensitivity, specificity, and 95% confidence intervals (CIs); meta-regression identified sources of heterogeneity. From 29 reports, we found that the pooled sensitivity and specificity to detect high-grade squamous intraepithelial lesion (HSIL) was higher for HCII than PCR (0.89 [CI: 0.89-0.90] and 0.85 [CI: 0.84-0.86] vs. 0.73 [CI: 0.73-0.74] and 0.62 [CI: 0.62-0.64]). Both assays had higher accuracy to detect cervical dysplasia in Europe than in Asia-Pacific or North America (diagnostic odd ratio - dOR = 4.08 [CI: 1.39-11.91] and 4.56 [CI: 1.86-11.17] for HCII vs. 2.66 [CI: 1.16-6.53] and 3.78 [CI: 1.50-9.51] for PCR) and accuracy to detect HSIL than atypical squamous cells of undetermined significance (ASCUS)/ low-grade squamous intraepithelial lesion (LSIL) (HCII-dOR = 9.04 [CI: 4.12-19.86] and PCR-dOR = 5.60 [CI: 2.87-10.94]). For HCII, using histology as a gold standard results in higher accuracy than using cytology (dOR = 2.87 [CI: 1.31-6.29]). Based on higher test accuracy, our results support the use of HCII in cervical cancer screening programs. The role of HPV type distribution should be explored to determine the worldwide comparability of HPV test accuracy.

  12. The reaction index and positivity ratio revisited

    Andersen, Klaus Ejner; Andersen, Flemming


    BACKGROUND AND OBJECTIVES: Assessing the quality of patch test preparations continues to be a challenge. 2 parameters, the reaction index (RI) and positivity ratio (PR), have been proposed as quality indicators by the Information Network of Departments of Dermatology (IVDK). The value of these st......BACKGROUND AND OBJECTIVES: Assessing the quality of patch test preparations continues to be a challenge. 2 parameters, the reaction index (RI) and positivity ratio (PR), have been proposed as quality indicators by the Information Network of Departments of Dermatology (IVDK). The value...... of the IVDK and our department. Calculation of RI's and PR's for patch test allergens is of limited value as a measure of quality of the patch test materials, because it predominantly reflects differences in scoring and reading of patch test reactions. Further, questionable reactions (+?) may be clinically...... relevant and very important for the individual patient. Focus on standardization of patch test materials, patch test technique, and reading of patch test reactions is mandatory....

  13. Dimethyl carbonate synthesis via transesterification of propylene carbonate with methanol by ceria-zinc catalysts: Role of catalyst support and reaction parameters

    Kumar, Praveen; Srivastava, Vimal Chandra; Mishra, Indra Mani [Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand (India)


    Ceria and zinc oxide catalyst were impregnated onto various oxide supports, namely Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, individually by deposition-coprecipitation method. The synthesized catalysts (CZA, CZS and CZT having supports Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, respectively) were characterized by X-ray diffraction (XRD), NH{sub 3}- and CO{sub 2}-temperature programmed desorption (TPD) and N2 adsorption. These catalysts were used for synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate in a batch reactor. CZS was found to have larger average grain size as compared to CZA and CZT. Composite oxides (catalysts) were found to contain individual phases of ZnO, CeO{sub 2} and some spinel forms of Zn, Ce along with their supports. CZS having highest basicity and surface area showed better catalytic activity as compared to CZA and CZT. Effect of reaction temperature and methanol/PC molar ratio on DMC yield was studied and a reaction mechanism has been discussed. Maximum DMC yield of 77% was observed with CZS catalyst at 170 .deg. C with methanol/PC molar ratio of 10.

  14. A New General Method for Simultaneous Fitting of Temperature- and Concentration-Dependence of Reaction Rates Yields Kinetic and Thermodynamic Parameters for HIV Reverse Transcriptase Specificity.

    Li, An; Ziehr, Jessica L; Johnson, Kenneth A


    Recent studies have demonstrated the dominant role of induced-fit in enzyme specificity of HIV reverse transcriptase and many other enzymes. However, relevant thermodynamic parameters are lacking and equilibrium thermodynamic methods are of no avail because the key parameters can only determined by kinetic measurement. By modifying KinTek Explorer software, we present a new general method for globally fitting data collected over a range of substrate concentrations and temperatures and apply it to HIV reverse transcriptase. Fluorescence stopped-flow methods were used to record the kinetics of enzyme conformational changes that monitor nucleotide binding and incorporation. The nucleotide concentration dependence was measured at temperatures ranging from 5 to 37C and the raw data were fit globally to derive a single set of rate constants at 37C and a set of activation enthalpy terms to account for the kinetics at all other temperatures. This comprehensive analysis afforded thermodynamic parameters for nucleotide binding (Kd, ΔG, ΔH, ΔS at 37C), and kinetic parameters for enzyme conformational changes and chemistry (rate constants and activation enthalpy). Comparisons between wild-type enzyme and a mutant resistant to nucleoside analogs used to treat HIV infections reveal that the ground state binding is weaker and the activation enthalpy for the conformational change step is significantly larger for the mutant. Further studies to explore the structural underpinnings of the observed thermodynamics and kinetics of the conformational change step may help to design better analogs to treat HIV infections and other diseases. Our new method is generally applicable to enzyme and chemical kinetics.

  15. Understanding the Importance of “Symbolic Interaction Stigma:” How Expectations about the Reactions of Others Adds to the Burden of Mental illness Stigma

    Link, Bruce G.; Wells, Jennifer; Phelan, Jo C.; Yang, Lawrence


    Objective Important components of stigma include imagining what others might think of a stigmatized status, anticipating what might transpire in an interaction with others, and rehearsing what one might do if something untoward occurs. These imagined relations are here called “symbolic interaction stigma” and can be impactful even if the internalization of negative stereotypes fails to occur. Concepts and measures that capture symbolic interaction stigma are introduced and a preliminary assessment of their impact provided. Methods Four self-report measures of symbolic interaction stigma (perceived devaluation discrimination, anticipation of rejection, stigma consciousness and concern with staying in) were developed or adapted and administered to a sample of individuals who have experienced mental illness (N=65). Regression analyses examined whether forms of symbolic interaction stigma were associated with withdrawal, self-esteem and isolation from relatives independent of measures of internalization of stigma and rejection experiences. Results As evidenced by scores on four distinct measures symbolic interaction stigma was relatively common in the sample, somewhat more common than the internalization of stigma. Additionally, measures of symbolic interaction stigma were significantly associated with withdrawal, self-esteem and isolation from relatives even when a measure of the internalization of stigma was statistically controlled. Conclusions and Implications for Practice The study suggests the potential importance of considering symbolic interaction forms of stigma in understanding and addressing stigma and its consequences. Being aware of symbolic interaction stigma could be useful in enhancing rehabilitation goals if an approach to counteracting the negative effects of these aspects of stigma can be developed. PMID:26075528

  16. Understanding the importance of "symbolic interaction stigma": How expectations about the reactions of others adds to the burden of mental illness stigma.

    Link, Bruce G; Wells, Jennifer; Phelan, Jo C; Yang, Lawrence


    Important components of stigma include imagining what others might think of a stigmatized status, anticipating what might transpire in an interaction with others, and rehearsing what one might do if something untoward occurs. These imagined relations are here called symbolic interaction stigma and can have an impact even if the internalization of negative stereotypes fails to occur. Concepts and measures that capture symbolic interaction stigma are introduced, and a preliminary assessment of their impact is provided. Four self-report measures of symbolic interaction stigma (perceived devaluation discrimination, anticipation of rejection, stigma consciousness, and concern with staying in) were developed or adapted and administered to a sample of individuals who have experienced mental illness (N = 65). Regression analyses examined whether forms of symbolic interaction stigma were associated with withdrawal, self-esteem, and isolation from relatives independent of measures of internalization of stigma and rejection experiences. As evidenced by scores on 4 distinct measures, symbolic interaction stigma was relatively common in the sample, somewhat more common than the internalization of stigma. In addition, measures of symbolic interaction stigma were significantly associated with withdrawal, self-esteem, and isolation from relatives even when a measure of the internalization of stigma was statistically controlled. The study suggests the potential importance of considering symbolic interaction forms of stigma in understanding and addressing stigma and its consequences. Being aware of symbolic interaction stigma could be useful in enhancing rehabilitation goals if an approach to counteracting the negative effects of these aspects of stigma can be developed. (c) 2015 APA, all rights reserved).

  17. The effect of a non-steroidal anti-inflammatory drug on two important predictors for accidental falls: postural balance and manual reaction time. A randomized, controlled pilot study.

    Hegeman, Judith; Nienhuis, Bart; van den Bemt, Bart; Weerdesteyn, Vivian; van Limbeek, Jacques; Duysens, Jacques


    Accidental falls in older individuals are a major health and research topic. Increased reaction time and impaired postural balance have been determined as reliable predictors for those at risk of falling and are important functions of the central nervous system (CNS). An essential risk factor for falls is medication exposure. Amongst the medications related to accidental falls are the non-steroidal anti-inflammatory drugs (NSAIDs). About 1-10% of all users experience CNS side effects. These side effects, such as dizziness, headaches, drowsiness, mood alteration, and confusion, seem to be more common during treatment with indomethacin. Hence, it is possible that maintenance of (static) postural balance and swift reactions to stimuli are affected by exposure to NSAIDs, indomethacin in particular, consequently putting older individuals at a greater risk for accidental falls. The present study investigated the effect of a high indomethacin dose in healthy middle-aged individuals on two important predictors of falls: postural balance and reaction time. Twenty-two healthy middle-aged individuals (59.5 ± 4.7 years) participated in this double-blind, placebo-controlled, randomized crossover trial. Three measurements were conducted with a week interval each. A measurement consisted of postural balance as a single task and while concurrently performing a secondary cognitive task and reaction time tasks. For the first measurement indomethacin 75 mg (slow-release) or a visually identical placebo was randomly assigned. In total, five capsules were taken orally in the 2.5 days preceding assessment. The second measurement was without intervention, for the final one the first placebo group got indomethacin and vice versa. Repeated measures GLM revealed no significant differences between indomethacin, placebo, and baseline in any of the balance tasks. No differences in postural balance were found between the single and dual task conditions, or on the performance of the dual task

  18. Capture reactions

    Endt, P.M.


    Capture reactions will be considered here from the viewpoint of the nuclear spectroscopist. Especially important to him are the capture of neutrons, protons, and alpha particles, which may proceed through narrow resonances, offering a well defined initial state for the subsequent deexcitation proces

  19. Oxidative dehydration reaction of glycerol into acrylic acid: A first-principles prediction of structural and thermodynamic parameters of a bifunctional catalyst

    Lacerda, Lívia Clara T.; dos Santos Pires, Maíra; Corrêa, Silviana; Oliveira, Luiz Carlos A.; Ramalho, Teodorico C.


    The production of biodiesel generates crude glycerol as a byproduct. The search for glycerol conversion routes has attracted the attention of researchers and thus, this work evaluated the properties of the catalysts T-Nb2O5 and T-Nb2O5/V treated with H2O2 applied to the reaction of oxidative dehydration of glycerol. The peroxo groups from the treatment with H2O2 had a greater oxidation capacity in relation to those in the pure catalyst. Furthermore, the catalyst doped with vanadium presented lower energy costs during the process. Those results might be helpful for designing new catalysts for the production of strategic chemical products from glycerol.

  20. Reaction rates for reaction-diffusion kinetics on unstructured meshes

    Hellander, Stefan; Petzold, Linda


    The reaction-diffusion master equation is a stochastic model often utilized in the study of biochemical reaction networks in living cells. It is applied when the spatial distribution of molecules is important to the dynamics of the system. A viable approach to resolve the complex geometry of cells accurately is to discretize space with an unstructured mesh. Diffusion is modeled as discrete jumps between nodes on the mesh, and the diffusion jump rates can be obtained through a discretization of the diffusion equation on the mesh. Reactions can occur when molecules occupy the same voxel. In this paper, we develop a method for computing accurate reaction rates between molecules occupying the same voxel in an unstructured mesh. For large voxels, these rates are known to be well approximated by the reaction rates derived by Collins and Kimball, but as the mesh is refined, no analytical expression for the rates exists. We reduce the problem of computing accurate reaction rates to a pure preprocessing step, depending only on the mesh and not on the model parameters, and we devise an efficient numerical scheme to estimate them to high accuracy. We show in several numerical examples that as we refine the mesh, the results obtained with the reaction-diffusion master equation approach those of a more fine-grained Smoluchowski particle-tracking model.

  1. Concurrent validity and reliability of using ground reaction force and center of pressure parameters in the determination of leg movement initiation during single leg lift.

    Aldabe, Daniela; de Castro, Marcelo Peduzzi; Milosavljevic, Stephan; Bussey, Melanie Dawn


    Postural adjustment evaluations during single leg lift requires the initiation of heel lift (T1) identification. T1 measured by means of motion analyses system is the most reliable approach. However, this method involves considerable workspace, expensive cameras, and time processing data and setting up laboratory. The use of ground reaction forces (GRF) and centre of pressure (COP) data is an alternative method as its data processing and setting up is less time consuming. Further, kinetic data is normally collected using frequency samples higher than 1000Hz whereas kinematic data are commonly captured using 50-200Hz. This study describes the concurrent-validity and reliability of GRF and COP measurements in determining T1, using a motion analysis system as reference standard. Kinematic and kinetic data during single leg lift were collected from ten participants. GRF and COP data were collected using one and two force plates. Displacement of a single heel marker was captured by means of ten Vicon(©) cameras. Kinetic and kinematic data were collected using a sample frequency of 1000Hz. Data were analysed in two stages: identification of key events in the kinetic data, and assessing concurrent validity of T1 based on the chosen key events with T1 provided by the kinematic data. The key event presenting the least systematic bias, along with a narrow 95% CI and limits of agreement against the reference standard T1, was the Baseline COPy event. Baseline COPy event was obtained using one force plate and presented excellent between-tester reliability.

  2. Activity, stability and kinetic parameters for -chymotrypsin catalysed reactions in AOT/isooctane reverse micelles with nonionic and zwitterionic mixed surfactants

    Santosh Kumar Verma; Kallol K Ghosh


    Reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulphosuccinate (AOT) in nonpolar organic solvents are widely known to have very high solubilization power for water. The method is applied to the hydrolysis of -nitrophenyl acetate (PNPA) catalysed by -chymotrypsin (-CT) in AOT/isooctane/buffer RMs. The increase in -CT activity and stability was an optimum at wo ([H2O]/[AOT]) = 10, z [Isooctane]/[AOT]) = 5. Three typical surfactants were selected based on their head group charges: a non-ionic surfactant Triton-X 100 and two zwitterionic sulphobetaine surfactants of the type CH2+1N+Me2 (CH2)3 SO$^{−}_{3}$ (n = 10; SB3-10, n = 16; SB3-16). The kinetic parameters (such as cat and M) of the -CT at 27°C were determined and compared in the absence and presence of three surfactants. The effect of chain length of zwitterionic surfactant (SB3-10 and SB3-16) on the enzymatic efficacy of -CT as a function of mixed surfactant addition has been investigated in AOT/isooctane RMs at pH 7.75.

  3. A theoretical study of the atmospherically important radical-radical reaction BrO + HO2; the product channel O2(a(1)Δg) + HOBr is formed with the highest rate.

    Chow, Ronald; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M


    A theoretical study has been made of the BrO + HO2 reaction, a radical-radical reaction which contributes to ozone depletion in the atmosphere via production of HOBr. Reaction enthalpies, activation energies and mechanisms have been determined for five reaction channels. Also rate coefficients have been calculated, in the atmospherically important temperature range 200-400 K, for the two channels with the lowest activation energies, both of which produce HOBr: (R1a) HOBr(X(1)A') + O2(X(3)Σ) and (R1b) HOBr(X(1)A') + O2(a(1)Δg). The other channels considered are: (R2) BrO + HO2 → HBr + O3, (R3) BrO + HO2 → OBrO + OH and (R4) BrO + HO2 → BrOO + OH. For all channels, geometry optimization and frequency calculations were carried out at the M06-2X/AVDZ level, while relative energies of the stationary points on the reaction surface were improved at a higher level (BD(TQ)/CBS or CCSD(T)/CBS). The computed standard reaction enthalpies (ΔH) for channels (R1a), (R1b), (R2), (R3) and (R4) are -47.5, -25.0, -4.3, 14.9 and 5.9 kcal mol(-1), and the corresponding computed activation energies (ΔE) are 2.53, -3.07, 11.83, 35.0 and 37.81 kcal mol(-1). These values differ significantly from those obtained in earlier work by Kaltsoyannis and Rowley (Phys. Chem. Chem. Phys., 2002, 4, 419-427), particularly for channel (R1b), and reasons for this are discussed. In particular, the importance of obtaining an open-shell singlet wavefunction, rather than a closed-shell singlet wavefunction, for the transition state of this channel is emphasized. Rate coefficient calculations from computed potential energy surfaces were made for BrO + HO2 for the first time. Although channel (R1a) is the most exothermic, channel (R1b) has the lowest barrier height, which is negative (at -3.07 kcal mol(-1)). Most rate coefficient calculations were therefore made for (R1b). A two transition state model has been used, involving an outer and an inner transition state. The inner transition state was

  4. The Importance of Geochemical Parameters and Shale Composition on Rock Mechanical Properties of Gas Shale Reservoirs: a Case Study From the Kockatea Shale and Carynginia Formation From the Perth Basin, Western Australia

    Labani, Mohammad Mahdi; Rezaee, Reza


    Evaluation of the gas shale mechanical properties is very important screening criteria for determining the potential intervals for hydraulic fracturing and as a result in gas shale sweet spot mapping. Young's modulus and Poisson's ratio are two controlling mechanical properties that dictate the brittleness of the gas shale layers. These parameters can be determined in the laboratory by testing the rock sample under different conditions (static method) or can be calculated using the well-logging data including sonic and density log data (dynamic method). This study investigates the importance of the shale composition and geochemical parameters on the Young's modulus and Poisson's ratio using log data. The data set of this study is coming from five different wells targeting the Kockatea Shale and Carynginia formation, two potential gas shale formations in the Perth Basin, Western Australia. The results show that converse to the common idea the effect of organic matter quantity and maturity on the rock mechanical properties of the gas shale reservoirs is not so much prominent, while the composition of the rock has an important effect on these properties. Considering the weight percentage of shale composition and organic matter quantity it could be concluded that effect of these parameters on rock mechanical properties is dependent on their weight contribution on the shale matrix. As well as effect of thermal maturity on the shale matrix and consequently on the rock mechanical properties of the shales is dependent on the organic matter content itself; therefore, obviously with a low organic matter content thermal maturity has no prominent effect on the brittleness as well.

  5. Influence of different head-neck positions on vertical ground reaction forces, linear and time parameters in the unridden horse walking and trotting on a treadmill.

    Waldern, N M; Wiestner, T; von Peinen, K; Gómez Alvarez, C G; Roepstorff, L; Johnston, C; Meyer, H; Weishaupt, M A


    It is believed that the head-neck position (HNP) has specific effects on the loading pattern of the equine locomotor system, but very few quantitative data are available. To quantify the effects of 6 different HNPs on forelimb-hindlimb loading and underlying temporal changes. Vertical ground reaction forces of each limb and interlimb coordination were measured in 7 high level dressage horses walking and trotting on an instrumented treadmill in 6 predetermined HNPs: HNP1--unrestrained; HNP2--elevated neck, bridge of the nose in front of the vertical; HNP3--elevated neck, bridge of the nose behind the vertical; HNP4--low and flexed neck; HNP5--head and neck in extreme high position; and HNP6--forward downward extension of head and neck. HNP1 served as a velocity-matched control. At the walk, the percentage of vertical stride impulse carried by the forehand (Iz(fore)) as well as stride length and overreach distance were decreased in HNP2, HNP3, HNP4 and HNP5 when compared to HNP1. At the trot, Iz(fore) was decreased in HNP2, HNP3, HNP4 and HNP5. Peak forces in the forelimbs increased in HNP5 and decreased in HNP6. Stance duration in the forelimbs was decreased in HNP2 and HNP5. Suspension duration was increased in HNP2, HNP3 and HNP5. Overreach distance was shorter in HNP4 and longer in HNP6. In comparison to HNP1 and HNP6, HNPs with elevation of the neck with either flexion or extension at the poll as well as a low and flexed head and neck lead to a weight shift from the forehand to the hindquarters. HNP5 had the biggest effect on limb timing and load distribution. At the trot, shortening of forelimb stance duration in HNP5 increased peak vertical forces although Iz(fore) decreased. Presented results contribute to the understanding of the value of certain HNPs in horse training.

  6. 食品化学物风险评估中一些重要参数的选择和使用%The choices and usage of some important parameters in risk assessment of food chemicals

    张磊; 刘兆平


    食品安全风险评估是我国制定、修订食品安全标准、实施食品安全监督管理的科学依据,评估结果的准确性和可靠性将直接影响食品安全监管决策的科学性.评估方法、统计学参数、模型构建和健康指导值是影响评估结果的几个重要因素,而对这些因素的选择和使用往往存在模糊认识和误区.本文主要针对食品中化学物的风险评估,对上述几个参数的选择和使用进行探讨.%The result of food safety risk assessment is the scientific basis for formulating and revising the food safety standards,and exercising food safety supervision and administration.Therefore,the accuracy and reliability of the result of risk assessment will affect the decision making of food safety risk management.Risk assessment methods,statistic parameters,models and health-based guidance values are some of the most important parameters that affect the result of risk assessment.Meanwhile,there are some misunderstandings and incorrect use of these parameters.This paper discussed the choices and usage of these parameters in the risk assessmentof food chemicals.

  7. Impact of reaction parameters on the chemical profile of 3,4-methylenedioxymethamphetamine synthesized via reductive amination: target analysis based on GC-qMS compared to non-targeted analysis based on GC×GC-TOF-MS.

    Schäffer, M; Dieckmann, S; Pütz, M; Kohles, T; Pyell, U; Zimmermann, R


    The most common clandestine manufacturing procedure for the ecstasy derivative 3,4-methylenedioxymethamphetamine (MDMA), is the reductive amination of piperonylmethylketone (PMK) via platinum(IV) oxide/hydrogen. Deviations of the reaction conditions during the synthesis may result in different chemical profiles of the products. The chemical analysis of these profiles is an important objective for forensic drug intelligence. In this work we studied the impact of a systematic variation of the hydrogenation time, the reaction temperature and the precursor batch on the resulting organic chemical profiles of the MDMA bases and MDMA hydrochlorides. Target analysis was based on a gas chromatography mass spectrometry (GC-MS) method which was harmonized during the European project CHAMP.(2) In addition, samples were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) and subjected to non-targeted data analysis for a comprehensive analysis of the complete profiles. The reaction temperature, followed by the used precursor batch, revealed the highest impact on the chemical profile. The effect on individual impurity compounds is discussed in detail. With respect to the interpretation of the data, the profiles were compared to the profiles of MDMA samples obtained by reductive amination using sodium borohydride ("cold method") and aluminium/mercury amalgam as alternative reducing agents. Non-targeted analysis revealed that the discrimination according to the synthetic route and the batch of precursor used for the synthesis strongly depends on the selected target compounds.

  8. Reaction Selectivity in Heterogeneous Catalysis

    Somorjai, Gabor A.; Kliewer, Christopher J.


    The understanding of selectivity in heterogeneous catalysis is of paramount importance to our society today. In this review we outline the current state of the art in research on selectivity in heterogeneous catalysis. Current in-situ surface science techniques have revealed several important features of catalytic selectivity. Sum frequency generation vibrational spectroscopy has shown us the importance of understanding the reaction intermediates and mechanism of a heterogeneous reaction, and can readily yield information as to the effect of temperature, pressure, catalyst geometry, surface promoters, and catalyst composition on the reaction mechanism. DFT calculations are quickly approaching the ability to assist in the interpretation of observed surface spectra, thereby making surface spectroscopy an even more powerful tool. HP-STM has revealed three vitally important parameters in heterogeneous selectivity: adsorbate mobility, catalyst mobility, and selective site-blocking. The development of size controlled nanoparticles from 0.8 to 10 nm, of controlled shape, and of controlled bimetallic composition has revealed several important variables for catalytic selectivity. Lastly, DFT calculations may be paving the way to guiding the composition choice for multi-metallic heterogeneous catalysis for the intelligent design of catalysts incorporating the many factors of selectivity we have learned.

  9. The importance of the geonomic dimensions for geodynamic concepts

    Bemmelen, R.W. van


    An analysis is made of the importance and interrelation of the parameters of length, time, pressure and temperature, and their bearing upon concepts regarding the earth's evolution. This leads to a tentative model of the chain of reactions caused by the continuous escape of the endogenic energy from

  10. Parâmetros relevantes na determinação da velocidade terminal de frutos de café Important parameters for determination of terminal velocity of coffee fruits

    Sandra M. Couto


    Full Text Available No desenvolvimento de máquinas de separação movidas a fluxos de ar, o conhecimento da velocidade terminal de um produto e das impurezas associadas é de importância fundamental. Neste trabalho, investigou-se o comportamento dos valores da velocidade terminal de frutos de café (variedades Catuaí e Híbrido Timor em função dos parâmetros (a estádio de maturação do produto na colheita ("verde" e "cereja"; (b época de colheita; (c variedade; (d teor de umidade dos frutos e (e número de frutos contidos na amostra usada para as determinações da velocidade. A análise dos resultados mostrou que os valores das velocidades terminais foram influenciados, significativamente, pelo teor de umidade do produto, estádio de maturação dos frutos e tamanho das amostras usadas nas determinações; entretanto, a época de colheita e a variedade dos frutos não se mostraram como parâmetros importantes nas determinações da velocidade terminal do produto. Relações funcionais entre parâmetros adimensionais, usando-se análise dimensional e o teorema Pi de Buckingham, foram também obtidas e são apresentadas neste trabalho; por outro lado, essas relações fornecem estimativas razoáveis para a velocidade terminal de um fruto, em função das velocidades de flutuação determinadas, experimentalmente, para amostras com um número maior de frutos.The knowledge of the terminal velocity of a product is of fundamental importance in the development of separation machines using airflows. The behavior of the values of the terminal velocity of coffee fruits (varieties Catuaí and Hybrid Timor was investigated in this work as a function of following parameters: (a maturation level of the coffee at the harvesting ("green" and "cherry" fruits; (b harvesting time; (c variety; (d moisture content of the fruits and (e number of fruits in the sample used for the determinations of the terminal velocity. Analysis of the results showed that the values of the

  11. Spallation reactions; Reactions de spallation

    Cugon, J.


    Spallation reactions dominate the interactions of hadrons with nuclei in the GeV range (from {approx} 0.1 to {approx} 10 GeV). They correspond to a sometimes important ejection of light particles leaving most of the time a residue of mass commensurate with the target mass. The main features of the experimental data are briefly reviewed. The most successful theoretical model, namely the intranuclear cascade + evaporation model, is presented. Its physical content, results and possible improvements are critically discussed. Alternative approaches are shortly reviewed. (author). 84 refs.

  12. Part I. Evaluation of thermodynamic and kinetic parameters for electron transfer and following chemical reaction from a global analysis of current-potential-time data. Part II. Electro-catalytic detection in high-performance liquid chromatography of vitamin B[sub 12] and other molecules of biological and environmental interest

    Kumar, V.T.


    Simultaneous evaluation of electron transfer rate constant, k[sup 0], following chemical reaction rate constant, k[sub f], electron transfer coefficient, [alpha] and standard potential, E[sup 0][prime] for an electrochemical reaction following the EC mechanism is described. A mathematical model for the current response to a potential step is developed, starting with the Butler-Volmer equation for electrode kinetics and concentration expressions for the redox couple. The resulting integral equations are solved numerically via the Step Function method. Current-potential and current-time curves are simulated and tested under limiting conditions. The four parameters of the system are evaluated by fitting simulated current-voltage-time (i-E-t) surface to the theoretical equation. The method is applied to study an important biological molecule, viz., methyl cobalamin, in DMSO. Included in the discussion part is the use of kinetic zone diagrams to depict chronoamperometric current response as a function of dimensionless rate constants for the EC reaction scheme. This compact display of the influence of the two rate constants on current in all time windows can be used to select the best data for analysis. Theoretical limits of measurable rate constants can be estimated from the zone diagram. The development of a dropping mercury electrode detector for High Performance Liquid Chromatography (HPLC) and its application to analysis of B[sub 12] and other vitamins is described. This EC detector is able to achieve high levels of sensitivity by exploiting the catalytic hydrogen evolution undergone by many nitrogenous organic molecules. Vitamin B[sub 12], thiamine, riboflavin and niacinamide were analyzed individually and in mixtures on reverse phase C18 column. Preliminary results from the analysis of commercial multivitamin preparations are also discussed.

  13. Kinetic Parameter of Reactions Between Mercury and Fluorine Compounds%应用量子化学计算研究燃煤烟气中氟与汞的反应动力学

    殷立宝; 周黎明; 徐齐胜; 于航; 陈传敏


    The ab initio calculation of quantum chemistry was performed to study the reaction mechanism of mercury with fluorine compounds. The bond length and angle of each molecular structure for Hg/F system were obtained and compared with literature results and NIST experimental data. The geometric configurations of reactants , intermediates,transition states and products were optimized. Then,the activation energies and pre-exponential fac-tors were calculated. The transition state theory was used to calculate the reaction rate within the temperature range of 298-1500,K. Besides,the variation tendency of each reaction with temperature was studied. The results show that reaction rate increases significantly before temperature reaches about 600,K. Compared to HF,F2,obviously promotes Hg oxidation. The rates of reaction Hg+F2→HgF+F and reaction HgF+F2→HgF2+F stay at a high level within the whole temperature range. For HgO existing in the flue gas,it is very important to convert it into HgF.%应用量子化学从头计算研究了汞与含氟物质的反应机理。计算得到汞/氟体系中有关分子结构的键长和键角值,并与文献值及美国国家标准技术局(NIST)中的理论值比较,以验证计算方法和基组的准确性。优化得到反应物、中间体、过渡态和产物的几何构型,计算活化能和指前因子。采用经典过渡态理论计算了298~1500,K 温度范围内各基元反应的反应速率常数,比较分析了不同温度下各反应速率的变化趋势。计算结果表明,温度低于600,K时,各反应速率随温度升高而增大,相对温度高于600,K后则更明显。相比于HF,F2对Hg的影响更显著,在所计算的温度范围内,Hg、HgF与F2的反应速率始终保持较高的水平。对于燃煤烟气中的HgO,将其转化为HgF对加速Hg污染物的脱除效果显得十分重要。




    Extended Huckel (EHT) calculations have been used to discuss the two alternative sigma-bond C-H metathesis reactions which occur with organo-lanthanide (Ln = Y, Lu) compounds. The two reactions lead either to H/H (H/D) exchange or to metalation and have been modelled by studying the interaction of a

  15. Minimum Energy Pathways for Chemical Reactions

    Walch, S. P.; Langhoff, S. R. (Technical Monitor)


    Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives useful results for a number of chemically important systems. The talk will focus on a number of applications to reactions leading to NOx and soot formation in hydrocarbon combustion.

  16. Fluctuation in nonextensive reaction-diffusion systems

    Wu Junlin; Chen Huaijun [Department of Physics, Shaanxi Normal University, Xian 710062 (China)


    The density fluctuation in a nonextensive reaction-diffusion system is investigated, where the nonequilibrium stationary-state distribution is described by the generalized Maxwell-Boltzmann distribution in the framework of Tsallis statistics (or nonextensive statistics). By using the density operator technique, the nonextensive pressure effect is introduced into the master equation and thus the generalized master equation is derived for the system. As an example, we take the{sup 3}He reaction-diffusion model inside stars to analyse the nonextensive effect on the density fluctuation and we find that the nonextensive parameter q different from one plays a very important role in determining the characteristics of the fluctuation waves.

  17. Biomixing by chemotaxis and efficiency of biological reactions: The critical reaction case

    Kiselev, Alexander; Ryzhik, Lenya


    Many phenomena in biology involve both reactions and chemotaxis. These processes can clearly influence each other, and chemotaxis can play an important role in sustaining and speeding up the reaction. In continuation of our work [A. Kiselev and L. Ryzhik, "Biomixing by chemotaxis and enhancement of biological reactions," Comm. Partial Differential Equations 37, 298-318 (2012)], 10.1080/03605302.2011.589879, we consider a model with a single density function involving diffusion, advection, chemotaxis, and absorbing reaction. The model is motivated, in particular, by the studies of coral broadcast spawning, where experimental observations of the efficiency of fertilization rates significantly exceed the data obtained from numerical models that do not take chemotaxis (attraction of sperm gametes by a chemical secreted by egg gametes) into account. We consider the case of the weakly coupled quadratic reaction term, which is the most natural from the biological point of view and was left open in Kiselev and Ryzhik ["Biomixing by chemotaxis and enhancement of biological reactions," Comm. Partial Differential Equations 37, 298-318 (2012)], 10.1080/03605302.2011.589879. The result is that similarly to Kiselev and Ryzhik ["Biomixing by chemotaxis and enhancement of biological reactions," Comm. Partial Differential Equations 37, 298-318 (2012)], 10.1080/03605302.2011.589879, the chemotaxis plays a crucial role in ensuring efficiency of reaction. However, mathematically, the picture is quite different in the quadratic reaction case and is more subtle. The reaction is now complete even in the absence of chemotaxis, but the timescales are very different. Without chemotaxis, the reaction is very slow, especially for the weak reaction coupling. With chemotaxis, the timescale and efficiency of reaction are independent of the coupling parameter.

  18. Effect of sol gel coating on wettability and interfacial reaction in Al-SiC MMC

    Liu, Y.L.; Breivik, T.R.; Kindl, B.


    The control of the interfacial reaction between the matrix and the SiC reinforcement in Al-SiC metal matrix composites (MMCs) is an important production parameter. The reaction causes degradation of the reinforcement, weakening of the interface and a decrease of the mechanical properties of the p...

  19. 质子自递反应常数(ks)是酸碱平衡的重要参数%On the constant of autoprolysis reaction (Ks ) as the important parameter in the acid-base balance problem

    郭瑞华; 张志斐; 潘海宇


    论述了ks在酸碱平衡中的重要作用。具体讨论了ks与 Ka、Kb的关系;ks决定了酸碱滴定反应完全度,为实现混合酸碱的连续滴定和极弱酸碱的滴定寻找出区分效应范围较大的非水溶剂;将kw与〔H+〕、〔OH-〕关系引入PB E 中,导出酸碱水溶液〔H+〕、酸碱滴定曲线方程、终点误差和缓冲容量计算式。提出了溶剂的pks只决定溶剂对酸碱的区分和拉平范围,但不决定溶剂的酸碱性的观点。%The article discussed the improtance of Ks in the acid-base balance.The article discussed the relationship between Ks and Ka 、K b in detail;Ks decided the complete level of acid-base titration.In order to ac hieve mixing acid-base continous titration and the weakest acid-base titration , the paper studied the non-aqueous solvent that has wider range of differntiatin g effect.The connection of Kw And 〔H+〕、〔OH〕 was put in to PBE and then the formule 〔H+〕and equilibrium of acid-base titration curve and end-point error and buffer capacity were obtained in the acid-base solution.T h e article also mentioned the idea that pKs of solvent did not decide the propert y acid-base of acid-base but the range of differentiate effect and leveling ef fect to acid-base.

  20. Research of Motorcycle Braking Parameters

    Loreta Levulytė


    Full Text Available From a technical point of view, in dangerous or emergency situation is very important motorcycle driver reaction and vehicle braking time. Motor-cycle deceleration parameters depend not only on the motorcycle brake system, but also on the driving experience. A significant influence on decel-eration the motorcycle has aerodynamic parameters, pavement type and condition, as well as the technical condition of the motocycle, shock absorb-ers, tire type and their technical condition. This article provides an analysis of the motorcycle longitudinal deceleration, braking modes of the mo-torcycle on a dry asphalt road surface. Motorcycle stopping – deceleration – acceleration efficiency issue, stopping in different modes. First ana-lyzed the dynamics of a motorcycle deceleration braking only the front wheel, then braked front and rear wheels and complex – then braked the front and rear wheels at the same time. The goal of experimental study is to determine the influence of braking modes intense fir motorcycle brak-ing deceleration when braking on dry road pavement, at three different braking modes, and set the braking path of change. Motorcycle decelera-tion in the longitudinal direction is an important parameter for analysis traffic accidents, for accident reconstruction process and the examination of motorcyclists technical possibility to avoid an accident.


    HR Department


    Green plates, removals and importation of personal effects Please note that, as from 1 April 2009, formalities relating to K and CD special series French vehicle plates (green plates), removals and importation of personal effects into France and Switzerland will be dealt with by GS Department (Building 73/3-014, tel. 73683/74407). Importation and purchase of tax-free vehicles in Switzerland, as well as diplomatic privileges, will continue to be dealt with by the Installation Service of HR Department (Building 33/1-011, tel. 73962). HR and GS Departments

  2. HIV-associated tuberculous lymphadenitis: the importance of polymerase chain reaction (PCR as a complementary tool for the diagnosis of tuberculosis - a study of 104 patients Linfadenite tuberculosa associada ao HIV: a importância da reação em cadeia de polimerase (PCR como ferramenta complementar para o diagnóstico da tuberculose - estudo de 104 pacientes

    Marcio Valle Cortez


    Full Text Available BACKGROUND: Lymphadenitis is common in HIV-positive patients. Diagnosis of the infections associated with this condition is complex, particularly in the case of tuberculosis. Rapid and specific detection of Mycobacterium tuberculosis (M. tuberculosis is fundamental in ensuring adequate treatment. In addition, frequent causes of lymphadenitis such as those associated with lymphoma and histoplasmosis, among others, must be eliminated as possible causes. OBJECTIVES: To evaluate the accuracy of polymerase chain reaction as a tool for the diagnosis of lymphadenitis resulting from M. tuberculosis. METHODS: In this study, a protocol was developed using the following procedures: direct microscopy using Ziehl-Neelsen staining, culture in Lowenstein-Jensen medium, histology and polymerase chain reaction. RESULTS: A total of 104 patients were included in the study. According to histopathology, 38 patients (36% were found to have nonspecific chronic lymphadenitis, 27 (26% had tuberculous lymphadenitis, 11 patients (10.5% had lymphoma and 9 (8.7% had histoplasmosis. When Lowenstein-Jensen culture was performed, positive tests for tuberculous lymphadenitis increased by 30%. With polymerase chain reaction, M. tuberculosis DNA was detected in 6 out of 38 samples of non-specific chronic lymphadenitis. Three of these patients were followed up, developed symptoms of tuberculosis and were cured following specific treatment. CONCLUSION: The data obtained in this study suggest that all cases of lymphadenopathies should be submitted to histopathology, Lowenstein-Jensen or Ogawa culture and polymerase chain reaction. Polymerase chain reaction may prove to be useful in providing an early and accurate detection of cases of extrapulmonary tuberculosis in HIV-positive patients with lymphadenopathies, avoiding empirical treatment and the possible development of resistant strains.FUNDAMENTOS: A linfadenite é comum em pacientes HIV-positivos. O diagnóstico das infec

  3. Characterizing multistationarity regimes in biochemical reaction networks.

    Irene Otero-Muras

    Full Text Available Switch like responses appear as common strategies in the regulation of cellular systems. Here we present a method to characterize bistable regimes in biochemical reaction networks that can be of use to both direct and reverse engineering of biological switches. In the design of a synthetic biological switch, it is important to study the capability for bistability of the underlying biochemical network structure. Chemical Reaction Network Theory (CRNT may help at this level to decide whether a given network has the capacity for multiple positive equilibria, based on their structural properties. However, in order to build a working switch, we also need to ensure that the bistability property is robust, by studying the conditions leading to the existence of two different steady states. In the reverse engineering of biological switches, knowledge collected about the bistable regimes of the underlying potential model structures can contribute at the model identification stage to a drastic reduction of the feasible region in the parameter space of search. In this work, we make use and extend previous results of the CRNT, aiming not only to discriminate whether a biochemical reaction network can exhibit multiple steady states, but also to determine the regions within the whole space of parameters capable of producing multistationarity. To that purpose we present and justify a condition on the parameters of biochemical networks for the appearance of multistationarity, and propose an efficient and reliable computational method to check its satisfaction through the parameter space.

  4. Inorganic Reaction Mechanisms Part II: Homogeneous Catalysis

    Cooke, D. O.


    Suggests several mechanisms for catalysis by metal ion complexes. Discusses the principal factors of importance in these catalysis reactions and suggests reactions suitable for laboratory study. (MLH)

  5. Articulatory Parameters.

    Ladefoged, Peter


    Summarizes the 16 parameters hypothesized to be necessary and sufficient for linguistic phonetic specifications. Suggests seven parameters affecting tongue shapes, three determining the positions of the lips, one controlling the position of the velum, four varying laryngeal actions, and one controlling respiratory activity. (RL)

  6. Parameter Estimation

    Sales-Cruz, Mauricio; Heitzig, Martina; Cameron, Ian;


    of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set...

  7. Ab initio calculations on 2,6-dimethylphenol and 4-(2,6-dimethylphenoxy)-2,6-dimethylphenol. Evidence of an important role for the phenoxonium cation in the copper-catalyzed oxidative phenol coupling reaction

    Baesjou, PJ; Driessen, WL; Challa, G; Reedijk, J


    Ab initio unrestricted Hartree-Fock calculations with a 6-31G* basis set were performed on 2, 6-dimethylphenol (DMP or monomer) and 4-(2, 6-dimethylphenoxy)-2, 6-dimethylphenol (dimer) to gain more insight into the mechanism of the copper-catalyzed oxidative phenol coupling reaction. Atomic charges

  8. Parâmetros reacionais para a síntese enzimática do butirato de butila em solventes orgânicos Reactional parameters for enzymatic synthesis of butyl butyrate in organic solvent

    Heizir F. CASTRO


    Full Text Available A síntese orgânica catalisada por enzimas envolve um mecanismo complexo dependente do tipo de substrato, enzima, solvente orgânico e teor de água no meio reacional. Neste trabalho foi estudado a influência de alguns desses parâmetros no rendimento da esterificação do butanol com ácido butírico, utilizando uma preparação enzimática comercial de lipase. A polaridade e natureza do solvente, bem como a razão molar entre o butanol e ácido butírico, foram considerados os fatores que mais influenciaram o desenvolvimento dessa síntese enzimática.The organic synthesis catalyzed by enzymes is a complex function of substrate concentration, water concentration in the liquid phase, enzyme and organic solvent properties. In this work the influence of some parameters on the esterification of butanol with butyric acid was investigated, using a commercial lipase preparation. The polarity and nature of the solvent and also the substrate mole ratios played an important role in the performance of this enzymatic synthesis.

  9. Atom addition reactions in interstellar ice analogues

    Linnartz, Harold; Fedoseev, Gleb


    This review paper summarizes the state-of-the-art in laboratory based interstellar ice chemistry. The focus is on atom addition reactions, illustrating how water, carbon dioxide and methanol can form in the solid state at astronomically relevant temperatures, and also the formation of more complex species such as hydroxylamine, an important prebiotic molecule, and glycolaldehyde, the smallest sugar, is discussed. These reactions are particularly relevant during the dark ages of star and planet formation, i.e., when the role of UV light is restricted. A quantitative characterization of such processes is only possible through dedicated laboratory studies, i.e., under full control of a large set of parameters such as temperature, atom-flux, and ice morphology. The resulting numbers, physical and chemical constants, e.g., barrier heights, reaction rates and branching ratios, provide information on the molecular processes at work and are needed as input for astrochemical models, in order to bridge the timescales t...

  10. Reaction Graph



    The paper proposes reaction graphs as graphical representations of computational objects.A reaction graph is a directed graph with all its arrows and some of its nodes labeled.Computations are modled by graph rewriting of a simple nature.The basic rewriting rules embody the essence of both the communications among processes and cut-eliminations in proofs.Calculi of graphs are ideentified to give a formal and algebraic account of reaction graphs in the spirit of process algebra.With the help of the calculi,it is demonstrated that reaction graphs capture many interesting aspects of computations.

  11. Ranking of Reactions Based on Sensitivity of Protein Noise Depends on the Choice of Noise Measure.

    Sucheta Gokhale

    Full Text Available Gene expression is a stochastic process. Identification of the step maximally affecting noise in the protein level is an important aspect of investigation of gene product distribution. There are numerous experimental and theoretical studies that seek to identify this important step. However, these studies have used two different measures of noise, viz. coefficient of variation and Fano factor, and have compared different processes leading to contradictory observations regarding the important step. In this study, we performed systematic global and local sensitivity analysis on two models of gene expression to investigate relative contribution of reaction rate parameters to steady state noise in the protein level using both the measures of noise. We analytically and computationally showed that the ranking of parameters based on the sensitivity of the noise to variation in a given parameter is a strong function of the choice of the noise measure. If the Fano factor is used as the noise measure, translation is the important step whereas for coefficient of variation, transcription is the important step. We derived an analytical expression for local sensitivity and used it to explain the distinct contributions of each reaction parameter to the two measures of noise. We extended the analysis to a generic linear catalysis reaction system and observed that the reaction network topology was an important factor influencing the local sensitivity of the two measures of noise. Our study suggested that, for the analysis of contributions of reactions to the noise, consideration of both the measures of noise is important.

  12. Inventory parameters

    Sharma, Sanjay


    This book provides a detailed overview of various parameters/factors involved in inventory analysis. It especially focuses on the assessment and modeling of basic inventory parameters, namely demand, procurement cost, cycle time, ordering cost, inventory carrying cost, inventory stock, stock out level, and stock out cost. In the context of economic lot size, it provides equations related to the optimum values. It also discusses why the optimum lot size and optimum total relevant cost are considered to be key decision variables, and uses numerous examples to explain each of these inventory parameters separately. Lastly, it provides detailed information on parameter estimation for different sectors/products. Written in a simple and lucid style, it offers a valuable resource for a broad readership, especially Master of Business Administration (MBA) students.

  13. A density functional study of chiral phosphoric acid-catalyzed direct arylation of trifluoromethyl ketone and diarylation of methyl ketone: reaction mechanism and the important role of the CF3 group.

    Fu, Aiping; Meng, Wei; Li, Hongliang; Nie, Jing; Ma, Jun-An


    The detailed mechanism of the chiral phosphoric acid-catalyzed diarylation reaction between acetophenone and indole has been investigated by DFT methods and compared with that of the reaction between 2,2,2-trifluoroacetophenone and indole. The calculated results confirm our previous hypothesis that the CF3 group in the ketone plays a perfect double role in activating the substrate and stabilizing the single arylation product of tertiary alcohol. It is also demonstrated that the different ratio of the F-substitution in the CH3 group of methyl ketone (CH3-nFn, n = 0, 1, 2, 3) affects the activation energy of the key dehydration step for the proposed diarylation process differently, and determines whether the subsequent re-arylation proceeds or is being suppressed. The computational prediction that the prohibitive barriers for CF3 and CHF2 ketones in the rate-determining dehydration step for the diarylation process could be overcome at higher reaction temperature has been validated by our additional experiments at 80 °C. Furthermore, the origin of the high enantioselectivity of the chiral phosphoric acid-catalyzed single arylation of trifluoromethyl ketone has been studied with the two-layer ONIOM method. The experimentally observed enantiomeric excess can be successfully rationalized.

  14. Experimental study on the effect of SO{sub 2} on PCDD/F emissions: determination of the importance of gas-phase versus solid-phase reactions in PCDD/F formation

    Shawn P. Ryan; Xiao-dong Li; Brian K. Gullett; C. W. Lee; Matt Clayton; Abderrahmane Touati [U.S. Environmental Protection Agency, Research Triangle Park, NC (United States). Office of Research and Development, National Risk Management Research Laboratory


    Cofiring coal in municipal solid waste incinerators (MSWIs) has previously been reported to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) emissions due to increasing the flue gas SO{sub 2} concentration. The present study was focused on understanding the primary mechanism responsible for the suppressant effect of SO{sub 2} on total PCDD/F formation and toxic equivalent (TEQ) emissions. The addition of SO{sub 2}, simulating the effect of coal addition on the flue gas composition, resulted in significant reductions in the TEQ emissions due to reactions involving SO{sub 2} in the postcombustion zone. However, emissions of total PCDDs/Fs, unlike the TEQ value, were dependent upon the Cl{sub 2} and SO{sub 2} injection temperatures due to increases in non-TEQ correlated isomers. The conversion of metal chlorides in the fly ash to sulfates, thus reducing the sites responsible for chlorination/oxidation reactions, was concluded to be the main suppressant mechanism; proposed reactions for copper and iron are presented. This mechanism was found to be independent of combustion conditions and could have prolonged effects on PCDD/F emissions from deposits formed with high flue gas S/Cl ratios. 43 refs., 2 figs., 4 tabs.

  15. Electronic device for measuring the polarization parameter in the {pi}{sup -}p {yields} {pi}{sup 0}n charge exchange reaction on a polarized proton target; Un appareillage electronique destine a la mesure du parametre de polarisation dans la reaction d'echange de charge {pi}{sup -}p {yields} {pi}{sup 0}n sur cible de protons polarises

    Brehin, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires


    An electronic apparatus has been constructed to measure the polarization parameter P{sub 0}(t) in {pi}{sup -}p {yields} {pi}{sup 0}n charge exchange scattering at 5.9 GeV/c and 11,2 GeV/c on polarized proton target. This device insures triggering of a heavy plate spark chamber, allowing visualisation of {gamma} rays from the {pi}{sup 0} decays when the associated neutron offers suitable characteristics in direction and energy. The neutron is detected by an array of 32 counters and his energy is measured by a time of flight method. Electronic circuits of this apparatus are described as test and calibration methods used. (author) [French] Un appareillage electronique a ete realise pour mesurer le parametre de polarisation P{sub 0}(t) dans la reaction d'echange de charge {pi}{sup -}p {yields} {pi}{sup 0}n a 5,9 GeV/c et 11,2 GeV/c sur une cible de protons polarises. Ce dispositif assure le declenchement d'une chambre a etincelles a plaques lourdes, permettant de visualiser les {gamma} de desitegration du {pi}{sup 0}, lorsque le neutron associe presente les caracteristiques convenables en direction et en energie. Le neutron est detecte par un ensemble de 32 compteurs et son energie est mesuree par une methode de temps de vol. Les circuits composant cet appareillage sont decrits ainsi que les methodes d'etalonnage et de verification utilisees. (auteur)

  16. [Imported histoplasmosis].

    Stete, Katarina; Kern, Winfried V; Rieg, Siegbert; Serr, Annerose; Maurer, Christian; Tintelnot, Kathrin; Wagner, Dirk


    Infections with Histoplasma capsulatum are rare in Germany, and mostly imported from endemic areas. Infections can present as localized or disseminated diseases in immunocompromised as well as immunocompetent hosts. A travel history may be a major clue for diagnosing histoplasmosis. Diagnostic tools include histology, cultural and molecular detection as well as serology. Here we present four cases of patients diagnosed and treated in Freiburg between 2004 and 2013 that demonstrate the broad range of clinical manifestations of histoplasmosis: an immunocompetent patient with chronic basal meningitis; a patient with HIV infection and fatal disseminated disease; a patient with pulmonary and cutaneous disease and mediastinal and cervical lymphadenopathy; and an immunosuppressed patient with disseminated involvement of lung, bone marrow and adrenal glands.

  17. Theoretical studies on concerted versus two steps hydrogen atom transfer reaction by non-heme Mn(IV/III)=O complexes: how important is the oxo ligand basicity in the C-H activation step?

    Jaccob, Madhavan; Ansari, Azaj; Pandey, Bhawana; Rajaraman, Gopalan


    High-valent metal-oxo complexes have been extensively studied over the years due to their intriguing properties and their abundant catalytic potential. The majority of the catalytic reactions performed by these metal-oxo complexes involves a C-H activation step and extensive efforts over the years have been undertaken to understand the mechanistic aspects of this step. The C-H activation by metal-oxo complexes proceeds via a hydrogen atom transfer reaction and this could happen by multiple pathways, (i) via a proton-transfer followed by an electron transfer (PT-ET), (ii) via an electron-transfer followed by a proton transfer (ET-PT), (iii) via a concerted proton-coupled electron transfer (PCET) mechanism. Identifying the right mechanism is a surging topic in this area and here using [Mn(III)H3buea(O)](2-) (1) and [Mn(IV)H3buea(O)](-) (2) species (where H3buea = tris[(N'-tert-butylureaylato)-N-ethylene]aminato) and its C-H activation reaction with dihydroanthracene (DHA), we have explored the mechanism of hydrogen atom transfer reactions. The experimental kinetic data reported earlier (T. H. Parsell, M.-Y. Yang and A. S. Borovik, J. Am. Chem. Soc., 2009, 131, 2762) suggests that the mechanism between 1 and 2 is drastically different. By computing the transition states, reaction energies and by analyzing the wavefunction of the reactant and transitions states, we authenticate the proposal that the Mn(III)=O undergoes a step wise PT-ET mechanism where as the Mn(IV)=O species undergo a concerted PCET mechanism. Both the species pass through a [Mn(III)-OH] intermediate and the stability of this species hold the key to the difference in the reactivity. The electronic origin for the difference in reactivity is routed back to the strength and basicity of the Mn-oxo bond and the computed results are in excellent agreement with the experimental results.




    Full Text Available A two-dimensional sagittally symmetric human-body model was established to simulate an optimal trajectory for manual material handling tasks. Nonlinear control techniques and genetic algorithms were utilized in the optimizations to explore optimal lifting patterns. The simulation results were then compared with the experimental data. Since the kinetic measures such as joint reactions and moments are vital parameters in injury determination, the importance of comparing kinetic measures rather than kinematical ones was emphasized.

  19. On conditions and parameters important to model sensitivity for unsaturated flow through layered, fractured tuff; Results of analyses for HYDROCOIN [Hydrologic Code Intercomparison Project] Level 3 Case 2: Yucca Mountain Project

    Prindle, R.W.; Hopkins, P.L.


    The Hydrologic Code Intercomparison Project (HYDROCOIN) was formed to evaluate hydrogeologic models and computer codes and their use in performance assessment for high-level radioactive-waste repositories. This report describes the results of a study for HYDROCOIN of model sensitivity for isothermal, unsaturated flow through layered, fractured tuffs. We investigated both the types of flow behavior that dominate the performance measures and the conditions and model parameters that control flow behavior. We also examined the effect of different conceptual models and modeling approaches on our understanding of system behavior. The analyses included single- and multiple-parameter variations about base cases in one-dimensional steady and transient flow and in two-dimensional steady flow. The flow behavior is complex even for the highly simplified and constrained system modeled here. The response of the performance measures is both nonlinear and nonmonotonic. System behavior is dominated by abrupt transitions from matrix to fracture flow and by lateral diversion of flow. The observed behaviors are strongly influenced by the imposed boundary conditions and model constraints. Applied flux plays a critical role in determining the flow type but interacts strongly with the composite-conductivity curves of individual hydrologic units and with the stratigraphy. One-dimensional modeling yields conservative estimates of distributions of groundwater travel time only under very limited conditions. This study demonstrates that it is wrong to equate the shortest possible water-travel path with the fastest path from the repository to the water table. 20 refs., 234 figs., 10 tabs.

  20. Influence of the reaction conditions on the enzyme catalyzed transesterification of castor oil

    Andrade, Thalles Allan; Errico, Massimiliano; Christensen, Knud Villy


    The identification of the influence of the reaction parameters is of paramount importance when defining a process design. In this work, non-edible castor oil was reacted with methanol to produce a possible component for biodiesel blends, using liquid enzymes as the catalyst. Temperature, alcohol......-to-oil molar ratio, enzyme and added water contents were the reaction parameters evaluated in the transesterification reactions. The optimal conditions, giving the optimal final FAME yield and FFA content in the methyl ester-phase was identified. At 35 °C, 6.0 methanol-to-oil molar ratio, 5 wt% of enzyme and 5...

  1. Reaction Kinetics of Nanostructured Silicon Carbide

    Wallis, Kendra; Zerda, T. W.


    Nanostructured silicon carbide (SiC) is of interest particularly for use in nanocomposites that demonstrate high hardness as well as for use in semiconductor applications. Reaction kinetics studies of solid-solid reactions are relatively recent and present a method of determining the reaction mechanism and activation energy by measuring reaction rates. We have used induction heating to heat quickly, thus reducing the error in reaction time measurements. Data will be presented for reactions using silicon nanopowder (melting point of silicon. Using the well-known Avrami-Erofeev model, a two-parameter chi- square fit of the data provided a rate constant (k) and parameter (n), related to the reaction mechanism, for each temperature. From these data, an activation energy of 138 kJ/mol was calculated. In addition, the parameter n suggests the reaction mechanism, which will also be discussed. Experiments are continuing at higher temperatures to consider the liquid- solid reaction as well.

  2. RT3D Reaction Modules for Natural and Enhanced Attenuation of Chloroethanes, Chloroethenes, Chloromethanes, and Daughter Products

    Johnson, Christian D.; Truex, Michael J.


    This document describes a suite of MNA/EA reaction modules that were developed for addressing complex chlorinated solvent reactions using RT3D. As an introduction, an overview of these MNA/EA reaction modules is presented, including discussions of similarities between reaction modules, the purpose of key reaction parameters, and important considerations for using the reaction modules. Subsequent sections provide the details of the reaction kinetics (conceptual model and equations), data input requirements, and example (batch reactor) results for each reaction module. This document does not discuss reaction module implementation or validation; such information will accompany the software in the form of release notes or a supplement to the RT3D manual.

  3. Chaos in the Belousov-Zhabotinsky reaction

    Field, Richard J.

    The dynamics of reacting chemical systems is governed by typically polynomial differential equations that may contain nonlinear terms and/or embedded feedback loops. Thus the dynamics of such systems may exhibit features associated with nonlinear dynamical systems, including (among others): temporal oscillations, excitability, multistability, reaction-diffusion-driven formation of spatial patterns, and deterministic chaos. These behaviors are exhibited in the concentrations of intermediate chemical species. Bifurcations occur between particular dynamic behaviors as system parameters are varied. The governing differential equations of reacting chemical systems have as variables the concentrations of all chemical species involved, as well as controllable parameters, including temperature, the initial concentrations of all chemical species, and fixed reaction-rate constants. A discussion is presented of the kinetics of chemical reactions as well as some thermodynamic considerations important to the appearance of temporal oscillations and other nonlinear dynamic behaviors, e.g., deterministic chaos. The behavior, chemical details, and mechanism of the oscillatory Belousov-Zhabotinsky Reaction (BZR) are described. Furthermore, experimental and mathematical evidence is presented that the BZR does indeed exhibit deterministic chaos when run in a flow reactor. The origin of this chaos seems to be in toroidal dynamics in which flow-driven oscillations in the control species bromomalonic acid couple with the BZR limit cycle...

  4. Componentes genéticos e fenotípicos para caracteres de importância agronômica em população de cenoura sob seleção recorrente Genotypic and phenotypic parameters for economically important traits of carrot

    Giovani Olegário da Silva


    characters in carrot populations, in order to guide the choice of selection strategies. The experiments were performed at two locations (Lapão, Bahia State and Brasília, Brazil in the summer of 2004. Nine carrot hybrid populations were evaluated in randomized complete block design with 4 replications and 2 m² treatments. 90 days after sowing, 15 competitive plants per plot were harvested and evaluated individually for the characters yield, root length, green shoulder length, tip type, shoulder type, root diameter, xylem root diameter, relationship among xylem diameter/root diameter, and both xylem and phloem a* color (color parameter determined by colorimetry, varying from green to red. The data were submitted to variance analyses and the heritability in the wide sense of plot average was estimated by medium square and the correlation among the characters. According to the heritability values, for the characters xylem diameter (0.92 and 0.87, color of a* xylem (0.96 and 0.95 and ratio among xylem diameter and root diameter (0.87 and 0.91, strong selection pressure can be applied in the two evaluation places. Larger root yield was associated with larger root diameter and larger xylem diameter, as well as by larger values of the ratio among xylem diameter and root diameter. Thicker roots are associated with smaller a* (content of β-carotene, mainly in relation to the part constituted by the xylem. Therefore, through the correlation values, there exist an indication that selection for larger carotene content cannot be carried out without considering the characters of root diameter, which are important yield components.

  5. Direct K-shell ionization probabilities in 30-MeV/u Ne- and 8.3-MeV/u C-induced reactions near zero impact parameter

    Kravchuk, VL; Wilschut, HW; van den Berg, AM; Davids, B; Fleurot, F; Hunyadi, M; de Huu, MA; Lohner, H; van der Woude, A


    Direct K-shell ionization probabilities were measured in coincidence with elastically scattered particles in 30-MeV/u Ne+Sn, Tb, Pb, Th and 8.3-MeV/u C+Zr, Ag, Sn, Sm, Au, Pb, Th reactions. Experimental data were compared with calculations in the semiclassical approximation. The transitional behavio

  6. Polymerase chain reaction for Enterococcus faecalis in drain fluid: the first screening test for symptomatic colorectal anastomotic leakage. The Appeal-study: analysis of parameters predictive for evident anastomotic leakage.

    Komen, N.; Slieker, J.; Willemsen, P.; Mannaerts, G.; Pattyn, P.; Karsten, T.; Wilt, H. de; Harst, E. van der; Leeuwen, W. van; Decaestecker, C.; Jeekel, H.; Lange, J.F.


    PURPOSE: With current diagnostic methods, the majority of patients with symptomatic colorectal anastomotic leakage(CAL) is identified approximately 1 week after operation.The aim of this study is to determine whether real-time polymerase chain reaction (RT-PCR) for detection of Escherichia coli and

  7. The Optimization of ZVI and TCE Reaction Parameters and the Establishment of Dynamics Equations%ZVI 与 TCE 反应参数优化及动力学方程的建立

    高艳娇; 黄润竹; 刘瑞; 宋铁红


    以批量研究的方法,考察了ZVI纯度、ZVI粒径、ZVI投量、pH值、温度和初始TCE浓度对TCE去除的影响,建立了ZVI去除TCE的动力学方程。最佳参数为:ZVI纯度92%,ZVI粒径30目,ZVI投量30 g ,pH值为6.0,温度25℃,初始TCE质量浓度50mg/L。最佳条件下TCE去除率可达73.6%,反应符合一级动力学方程。%Batch research methods are used to investigate the influences of ZVI purity ,ZVI particle size ,ZVI dosing quan-tity ,solution pH value ,reaction temperature and initial concentration of TCE on TCE removing .The mathematical models of ZVI removing TCE are established .The optimum experiment conditions are :92% purity of ZVI ,size 30 mu size of ZVI ,30 g of ZVI additive amount ,solution pH 6 .0 ,reaction temperature of 25℃ and initial TCE concentration of 50 mg/L .TCE removal rate can reach 73 .6% under these optimum conditions and the reaction kinetics equations agree with the pseudo -first-order reaction kinetics equation .

  8. Nuclear reaction rates and opacity in massive star evolution calculations

    Bahena, D [Astronomical Institute of the Academy of Sciences, BocnI II 1401, 14131 Praha 4 (Czech Republic); Klapp, J [Instituto Nacional de Investigaciones Nucleares, Km. 36.5 Carr. Mexico-Toluca, 52750 Edo. de Mexico (Mexico); Dehnen, H, E-mail: jaime.klapp@inin.gob.m [Universitaet Konstanz, Fachbereich Physik, Fach M568, D-78457 Konstanz (Germany)


    Nuclear reaction rates and opacity are important parameters in stellar evolution. The input physics in a stellar evolution code determines the main theoretical characteristics of the stellar structure, evolution and nucleosynthesis of a star. For different input physics, in this work we calculate stellar evolution models of very massive first stars during the hydrogen and helium burning phases. We have considered 100 and 200M{sub s}un galactic and pregalactic stars with metallicity Z = 10{sup -6} and 10{sup 9}, respectively. The results show important differences from old to new formulations for the opacity and nuclear reaction rates, in particular the evolutionary tracks are significantly affected, that indicates the importance of using up to date and reliable input physics. The triple alpha reaction activates sooner for pregalactic than for galactic stars.

  9. Multiscale stochastic simulations of chemical reactions with regulated scale separation

    Koumoutsakos, Petros, E-mail: [Chair of Computational Science, Clausiusstrasse 33, ETH Zurich, CH-8092 (Switzerland); Feigelman, Justin [Chair of Computational Science, Clausiusstrasse 33, ETH Zurich, CH-8092 (Switzerland)


    We present a coupling of multiscale frameworks with accelerated stochastic simulation algorithms for systems of chemical reactions with disparate propensities. The algorithms regulate the propensities of the fast and slow reactions of the system, using alternating micro and macro sub-steps simulated with accelerated algorithms such as τ and R-leaping. The proposed algorithms are shown to provide significant speedups in simulations of stiff systems of chemical reactions with a trade-off in accuracy as controlled by a regulating parameter. More importantly, the error of the methods exhibits a cutoff phenomenon that allows for optimal parameter choices. Numerical experiments demonstrate that hybrid algorithms involving accelerated stochastic simulations can be, in certain cases, more accurate while faster, than their corresponding stochastic simulation algorithm counterparts.

  10. Speeding chemical reactions by focusing

    Lacasta, A M; Sancho, J M; Lindenberg, K


    We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate (t to the power -1/2) to very close to the perfect mixing rate, (t to the power -1).

  11. Selecting water-alcohol mixed solvent for synthesis of polydopamine nano-spheres using solubility parameter

    Jiang, Xiaoli; Wang, Yinling; Li, Maoguo


    The solvent plays an important role in a given chemical reaction. Since most reaction in nature occur in the mixed-solvent systems, a comprehensive principle for solvent optimization was required. By calculating the Hansen solubility parameters (HSP) distance Ra , we designed a model experiment to explore the influence of mixed solvents on the chemical synthesis. The synthesis of polydopamine (PDA) in the water-alcohol system was chosen as model. As predicted, the well-dispersed PDA spheres w...

  12. Enzymatic hydrolysis of salmon oil by native lipases: optimization of process parameters

    Carvalho,Patrícia de O.; Campos,Paula R. B.; Noffs,Maximiliano D'Addio; Fregolente, Patrícia B. L.; Fregolente, Leonardo V.


    In an attempt to concentrate the content of n-3 polyunsaturated fatty acids (n-3 PUFA) in the residual acylglycerol, salmon oil (n-3 PUFA content of 30.1%) was hydrolyzed with three kinds of native microbial lipases (Aspergillus niger, Rhizopus javanicus and Penicillium solitum). For each lipase, a response surface methodology was used to obtain maximum PUFA content and to optimize the parameters of enzymatic reactions with respect to important reaction variables; temperature (X1), amount of ...

  13. Resonance Reaction in Diffusion-Influenced Bimolecular Reactions

    Kolb, Jakob J; Dzubiella, Joachim


    We investigate the influence of a stochastically fluctuating step-barrier potential on bimolecular reaction rates by exact analytical theory and stochastic simulations. We demonstrate that the system exhibits a new resonant reaction behavior with rate enhancement if an appropriately defined fluctuation decay length is of the order of the system size. Importantly, we find that in the proximity of resonance the standard reciprocal additivity law for diffusion and surface reaction rates is violated due to the dynamical coupling of multiple kinetic processes. Together, these findings may have important repercussions on the correct interpretation of various kinetic reaction problems in complex systems, as, e.g., in biomolecular association or catalysis.

  14. Allergic Reactions

    ... round, they may be caused by exposure to indoor allergens such as dust mites, indoor molds or pets. Urticaria, or hives, is characterized ... home. Video: What is an allergic reaction? » Utility navigation Donate Annual meeting Browse your conditions Check pollen ...

  15. Predicting the distribution of whey protein fouling in a plate heat exchanger using the kinetic parameters of the thermal denaturation reaction of β-lactoglobulin and the bulk temperature profiles.

    Blanpain-Avet, P; André, C; Khaldi, M; Bouvier, L; Petit, J; Six, T; Jeantet, R; Croguennec, T; Delaplace, G


    Fouling of plate heat exchangers (PHE) is a severe problem in the dairy industry, notably because the relationship between the build-up of protein fouling deposits and the chemical reactions taking place in the fouling solution has not yet been fully elucidated. Experiments were conducted at pilot scale in a corrugated PHE, and fouling deposits were generated using a model β-lactoglobulin (β-LG) fouling solution for which the β-LG thermal denaturation reaction constants had been previously determined experimentally. Then 18 different bulk temperature profiles within the PHE were imposed. Analysis of the fouling runs shows that the dry deposit mass per channel versus the ratio R=kunf/kagg (with kunf and kagg representing, respectively, the unfolding and aggregation rate constants computed from both the identification of the β-LG thermal denaturation process and knowledge of the imposed bulk temperature profile into the PHE channel) is able to gather reasonably well the experimental fouling mass data into a unique master curve. This type of representation of the results clearly shows that the heat-induced reactions (unfolding and aggregation) of the various β-LG molecular species in the bulk fluid are essential to capture the trend of the fouling mass distribution inside a PHE. This investigation also illustrates unambiguously that the release of the unfolded β-LG (also called β-LG molten globule) within the bulk fluid (and the absence of its consumption in the form of aggregates) is a key phenomenon that controls the extent of protein fouling as well as its location inside the PHE. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  16. Mesh implants: An overview of crucial mesh parameters

    Lei-Ming; Zhu; Philipp; Schuster; Uwe; Klinge


    Hernia repair is one of the most frequently performed surgical interventions that use mesh implants. This article evaluates crucial mesh parameters to facilitate selection of the most appropriate mesh implant, considering raw materials, mesh composition, structure parameters and mechanical parameters. A literature review was performed using the Pub Med database. The most important mesh parameters in the selection of a mesh implant are the raw material, structural parameters and mechanical parameters, which should match the physiological conditions. The structural parameters, especially the porosity, are the most important predictors of the biocompatibility performance of synthetic meshes. Meshes with large pores exhibit less inflammatory infiltrate, connective tissue and scar bridging, which allows increased soft tissue ingrowth. The raw material and combination of raw materials of the used mesh, including potential coatings and textile design, strongly impact the inflammatory reaction to the mesh. Synthetic meshes made from innovative polymers combined with surface coating have been demonstrated to exhibit advantageous behavior in specialized fields. Monofilament, largepore synthetic meshes exhibit advantages. The value of mesh classification based on mesh weight seems to be overestimated. Mechanical properties of meshes, such as anisotropy/isotropy, elasticity and tensile strength, are crucial parameters for predicting mesh performance after implantation.

  17. Supergranular Parameters

    Udayashankar, Paniveni


    I study the complexity of supergranular cells using intensity patterns from Kodaikanal solar observatory. The chaotic and turbulent aspect of the solar supergranulation can be studied by examining the interrelationships amongst the parameters characterizing supergranular cells namely size, horizontal flow field, lifetime and physical dimensions of the cells and the fractal dimension deduced from the size data. The findings are supportive of Kolmogorov's theory of turbulence. The Data consists of visually identified supergranular cells, from which a fractal dimension 'D' for supergranulation is obtained according to the relation P α AD/2 where 'A' is the area and 'P' is the perimeter of the supergranular cells. I find a fractal dimension close to about 1.3 which is consistent with that for isobars and suggests a possible turbulent origin. The cell circularity shows a dependence on the perimeter with a peak around (1.1-1.2) x 105 m. The findings are supportive of Kolmogorov's theory of turbulence.

  18. Excitation functions and yields of proton induced reactions at intermediate energies leading to important diagnostics radioisotopes of {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 97}Ru, {sup 111}In, {sup 123}I, {sup 127}Xe, {sup 128}Cs, {sup 178}Ta and {sup 201}Tl

    Rurarz, E. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)


    This report describes investigations of the excitation functions of the proton induced reactions on 14 targets (Mn, Co, Br, Rb, {sup 99}Tc, {sup 113}Cd, {sup 114}Cd, Cd, I, Cs, Ta, {sup 206,207,208}Pb) leading directly or indirectly to the formation of radionuclides {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 97}Ru, {sup 111}In, {sup 123}I, {sup 127}Xe, {sup 128}Cs, {sup 178}Ta and {sup 201}Tl frequently used in diagnostic procedures of nuclear medicine. The measurements of the excitation functions were made over a wide proton energy range from the reaction threshold up to 100 MeV using the stacked foil (or pellet) technique. Small energy steps were used to allow for accurate determination of the structure of excitation functions. For {sup 97}Ru, {sup 111}In and {sup 127}Xe formation with protons, new reaction channels and targets were used and data concerning this method are published for the first time. The data for {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 123}I, {sup 128}Cs and {sup 201}Tl obtained in the present work for the E{sub p}=70-100 MeV region are also published for the first time. The measured excitation functions for the formation of desired (and undesired) radionuclides (altogether 28 excitation functions) are compared with the theoretical ones calculated on the basis of a hybrid model of nuclear reactions in the form of the Overlaid Alice computer code. In order to determine the contribution of the competitive reaction channels to the purity of the produced, desired radionuclide, the excitation functions of the accompanying reactions were also calculated. The 122 calculated excitation functions for the possible contaminant are given. The comparison of experimental excitation functions with the results of model calculations showed satisfactory agreement; no parameter adjustment for individual reaction products was undertaken. Production yields for 28 radionuclides mentioned above were determined (author). 262 refs, 65 figs, 34 tabs.

  19. Reactions of Negative Ions


    2 + H2 SO 4 + HS04 (HNO 3 ) 2 + HNO 3 1.1 0.6 * defined as 1 The most important results from an atmospheric viewpoint are the reactions of H SO with NO...constant HS04 >4.5 bracketing 22 0 C1 , 1.95 * 0.25 bracketlng 32 -4 __.. . .___,_=____,,_______... . . . -- . . . . One particularly interesting aspect of

  20. 胶原多肽基表面活性剂合成工艺的优化%Optimization of Reaction Parameters for Synthesis of Collagen- Peptide Based Surfactant

    迟原龙; 崔敏; 廖学品; 张文华; 石碧


    采用碱性蛋白酶水解废弃皮屑提取胶原多肽,然后使其与油酰氯反应合成胶原多肽基表面活性剂。以胶原多肽的氨基转化率和油酰氯的效率值作为评价指标,考察反应温度和时间、油酰氯用量、丙酮用量、氢氧化钠用量和胶原多肽浓度的影响,进而确定合成胶原多肽基表面活性剂的优化工艺。试验结果表明:合成目标产物的优化条件为100mL质量浓度为10%的胶原多肽、30mmoL/L油酰氯、10mL丙酮和60mmol/L氢氧化钠,先在30℃反应2h,再升温至60℃反应2h。在此条件下胶原多肽的氨基转化率为74.4%,油酰氯的效率值为1.21,合成产物的临界胶束浓度为0.66g/L,在此浓度下表面张力为35.85mN/m。%The collagen peptide was prepared by digestion of tannery skin waste using alkaline protease. Then a collagen - peptide based surfactant (CBS) was synthesized by interaction between the collagen peptide and oleoyl chloride. The effects of reaction temperature and time, the contents of oleoyl chloride, acetone and sodium hydroxide, and collagen peptide concentration on the transfer ratio of peptide amino group and the reaction efficiency of oleoyl chloride were investigated. The results show that the optimized reaction conditions are as follows: 100mL 10% (w/v) collagen peptide, 30mmol/L oleoyl chloride, 10mL acetone and 60mmol/L sodium hydroxide react at 30℃ for 2h, and then 60℃ for 2h. The transfer ratio of peptide amino group and the reaction efficiency of oleoyl chloride under the optimized reaction conditions are 74.4% and 1.21, respectively. The critical micelle concentration (cmc) and surface tension at cmc of CBS are 0.66g/L and 35.85mN/m, respectively.

  1. Surface-active ionic liquids in micellar catalysis: impact of anion selection on reaction rates in nucleophilic substitutions† †Electronic supplementary information (ESI) available: Formulae for calculating aggregation parameters and fitting of kinetic constants and copies of NMR spectra. See DOI: 10.1039/c6cp00493h Click here for additional data file.

    Cognigni, Alice; Gaertner, Peter; Zirbs, Ronald; Peterlik, Herwig; Prochazka, Katharina; Schröder, Christian


    A series of surface-active ionic liquids based on the 1-dodecyl-3-methylimidazolium cation and different anions such as halides and alkylsulfates was synthesized. The aggregation behavior of these ionic liquids in water was characterized by surface tension, conductivity measurements and UV-Vis spectroscopy in order to determine the critical micelle concentration (CMC) and to provide aggregation parameters. The determination of surface activity and aggregation properties of amphiphilic ionic liquids was accompanied by SAXS studies on selected surface-active ionic liquids. The application of these surface-active ionic liquids with different anions was tested in nucleophilic substitution reactions for the degradation of organophosphorus compounds. Kinetic studies via UV-Vis spectrophotometry showed a strong acceleration of the reaction in the micellar system compared to pure water. In addition, an influence of the anion was observed, resulting in a correlation between the anion binding to the micelle and the reaction rate constants, indicating that the careful choice of the surface-active ionic liquid can considerably affect the outcome of reactions. PMID:27121134

  2. Thermochemistry, reaction paths, and kinetics on the tert-isooctane radical reaction with O2.

    Snitsiriwat, Suarwee; Bozzelli, Joseph W


    Thermochemical properties of tert-isooctane hydroperoxide and its radicals are determined by computational chemistry. Enthalpies are determined using isodesmic reactions with B3LYP density function and CBS QB3 methods. Application of group additivity with comparison to calculated values is illustrated. Entropy and heat capacities are determined using geometric parameters and frequencies from the B3LYP/6-31G(d,p) calculations for the lowest energy conformer. Internal rotor potentials are determined for the tert-isooctane hydroperoxide and its radicals in order to identify isomer energies. Recommended values derived from the most stable conformers of tert-isooctane hydroperoxide of are -77.85 ± 0.44 kcal mol(-1). Isooctane is a highly branched molecule, and its structure has a significant effect on its thermochemistry and reaction barriers. Intramolecular interactions are shown to have a significant effect on the enthalpy of the isooctane parent and its radicals on peroxy/peroxide systems, the R• + O2 well depths and unimolecular reaction barriers. Bond dissociation energies and well depths, for tert-isooctane hydroperoxide → R• + O2 are 33.5 kcal mol(-1) compared to values of ∼38 to 40 kcal mol(-1) for the smaller tert-butyl-O2 → R• + O2. Transition states and kinetic parameters for intramolecular hydrogen atom transfer and molecular elimination channels are characterized to evaluate reaction paths and kinetics. Kinetic parameters are determined versus pressure and temperature for the chemically activated formation and unimolecular dissociation of the peroxide adducts. Multifrequency quantum RRK (QRRK) analysis is used for k(E) with master equation analysis for falloff. The major reaction paths at 1000 K are formation of isooctane plus HO2 followed by cyclic ether plus OH. Stabilization of the tert-isooctane hydroperoxy radical becomes important at lower temperatures.

  3. Nucleosynthesis by photon-induced reactions

    Mohr, P. E-mail:; Babilon, M.; Galaviz, D.; Sonnabend, K.; Vogt, K.; Zilges, A


    Similar to the well-known Gamow window for charged particle induced reactions, there exists an effective energy window for photon-induced reactions. Properties of this window are discussed in detail for ({gamma}, n) and ({gamma}, {alpha}) reactions. These reactions are important for the nucleosynthesis of rare neutron-deficient p nuclei.

  4. Influence of the Reaction Conditions on the Enzyme Catalyzed Transesterification of Castor Oil: a possible step in Biodiesel Production

    Andrade, Thalles Allan; Errico, Massimiliano; Christensen, Knud Villy


    The identification of the influence of the reaction parameters is of paramount importance when defining a process design. In this work, non-edible castor oil was reacted with methanol to produce a possible component for biodiesel blends, using liquid enzymes as the catalyst. Temperature, alcohol......-to-oil molar ratio, enzyme and added water contents were the reaction parameters evaluated in the transesterification reactions. The optimal conditions, giving the optimal final FAME yield and FFA content in the methyl ester-phase was identified. At 35 °C, 6.0 methanol-to-oil molar ratio, 5 wt% of enzyme and 5...

  5. Kinetic and mechanistic studies of free-radical reactions in combustion

    Tully, F.P. [Sandia National Laboratories, Livermore, CA (United States)


    Combustion is driven by energy-releasing chemical reactions. Free radicals that participate in chain reactions carry the combustion process from reactants to products. Research in chemical kinetics enables us to understand the microscopic mechanisms involved in individual chemical reactions as well as to determine the rates at which they proceed. Both types of information are required for an understanding of how flames burn, why engines knock, how to minimize the production of pollutants, and many other important questions in combustion. In this program the authors emphasize accurate measurements over wide temperature ranges of the rates at which ubiquitous free radicals react with stable molecules. The authors investigate a variety of OH, CN, and CH + stable molecule reactions important to fuel conversion, emphasizing application of the extraordinarily precise technique of laser photolysis/continuous-wave laser-induced fluorescence (LP/cwLIF). This precision enables kinetic measurements to serve as mechanistic probes. Since considerable effort is required to study each individual reaction, prudent selection is critical. Two factors encourage selection of a specific reaction: (1) the rates and mechanisms of the subject reaction are required input to a combustion model; and (2) the reaction is a chemical prototype which, upon characterization, will provide fundamental insight into chemical reactivity, facilitate estimation of kinetic parameters for similar reactions, and constrain and test the computational limits of reaction-rate theory. Most studies performed in this project satisfy both conditions.

  6. Nanoparticle Reactions on Chip

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  7. Hipersensitivity Reactions to Corticosteroids.

    Berbegal, L; DeLeon, F J; Silvestre, J F


    Corticosteroids are widely used drugs in the clinical practice, especially by topic application in dermatology. These substances may act as allergens and produce immediate and delayed hypersensitivity reactions. Allergic contact dermatitis is the most frequent presentation of corticosteroid allergy and it should be studied by patch testing in specific units. The corticosteroids included in the Spanish standard battery are good markers but not ideal. Therefore, if those makers are positive, it is useful to apply a specific battery of corticosteroids and the drugs provided by patients. Immediate reactions are relatively rare but potentially severe, and it is important to confirm the sensitization profile and to guide the use of alternative corticosteroids, because they are often necessary in several diseases. In this article we review the main concepts regarding these two types of hypersensitivity reactions in corticosteroid allergy, as well as their approach in the clinical practice. Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved.



    cracking of n-hexane on different zeolites has been studied.   Catalytic experiments at atmospheric pressure were carried out in a continuous fixed bed reactor.   By means of measuring the initial rates for the cracking of n-hexane over two series zeolites, Y and Beta, a correlation between the Bronsted acid sites and the initial rates has been found. The results show that the initiation steps of n-hexane cracking occur on the Bronsted acid sites, Lewis acid sites are inactive for these steps.   Acid site density and acid site strength of zeolite determine the activity of n-hexane cracking. The role of acid site density predominates in most cases, however, the acid site strength also plays an important role in some instances. Meanwhile, similar intrinsic catalytic activities of different zeolites have been found.   A well-correlated linear relationship exists between acid site density of zeolite and the initial formation rates of some primary products. For zeolites with different structural pore diameters, their acid site density does not show significant effects on the cracking chain length for n-hexane. The results indicate that bimolecular reactions in the cracking of n-hexane proceed via Rideal mechanism. The reaction scheme of n-hexane can be explained by chain mechanism. A parameter “Cracking chain length” (CCL) has been proposed, and some elementary steps in cracking procedures have been scrutinized. The effects of zeolite structure, acid site density, and reaction temperature on the mechanism of n-hexane cracking and CCL have been studied.   The cracking of n-hexane proceeded via the chain reactions includes three steps: initiation, propagation and termination. The chain initiation proceeds through monomolecular protolytic cracking mechanism. All the carbenium ions formed with carbon number above 4 are mainly tertiary carbenium ions. The chain process of cracking is propagated by bimolecular reactions, namely disproportionation and hydrogen

  9. Fundamental stellar parameters

    Wittkowski, M


    I present a discussion of fundamental stellar parameters and their observational determination in the context of interferometric measurements with current and future optical/infrared interferometric facilities. Stellar parameters and the importance of their determination for stellar physics are discussed. One of the primary uses of interferometry in the field of stellar physics is the measurement of the intensity profile across the stellar disk, both as a function of position angle and of wavelength. High-precision fundamental stellar parameters are also derived by characterizations of binary and multiple system using interferometric observations. This topic is discussed in detail elsewhere in these proceedings. Comparison of observed spectrally dispersed center-to-limb intensity variations with models of stellar atmospheres and stellar evolution may result in an improved understanding of key phenomena in stellar astrophysics such as the precise evolutionary effects on the main sequence, the evolution of meta...

  10. Study of important parameters on the irradiation of {sup 124}Xe, to improve the production of {sup 123}I with high purity using the Cyclone-30 cyclotron at IPEN-CNEN/SP; Estudo de parametros relevantes na irradiacao de {sup 124}Xe, visando a otimizacao na obtencao de {sup 123}I ultra puro no ciclotron Cyclone-30 do IPEN-CNEN/SP

    Sumiya, Luiz Carlos do Amaral


    The development of diagnosis equipment and therapy procedures in nuclear medicine depends on the availability of commercial radioisotopes. IPEN is the most important institution that provides radioisotopes for national market. In order to achieve this function, IPEN had invested in the acquisition of a 30 MeV Cyclone-30 cyclotron to produce mainly {sup 18}F, {sup 67}Ga, {sup 201}Tl and {sup 123}I. The {sup 123}I production is the aim of the present work. With the {sup 123}I routine production data obtained by proton irradiation of Xe targets with an enrichment greater than 99.8%, it was possible to identify the important parameters that have direct influence on the production yield of high purity degree {sup 123}I. Even though the methodology for the commercial production of {sup 123}I, there are an scarcity of operational parameters data for this task. In this work the evaluated parameters were: {sup 124}Xe pressure, proton beam quality, irradiation time, operational temperature of the irradiation system under irradiation, waiting time to obtain {sup 123}I, temperature of washing solution and the impact of the internal Ni coating in the target. With the obtained results it was possible to modify the operational conditions for routine production and increasing the efficiency in about 30%. (author)

  11. Parameter Estimation Through Ignorance

    Du, Hailiang


    Dynamical modelling lies at the heart of our understanding of physical systems. Its role in science is deeper than mere operational forecasting, in that it allows us to evaluate the adequacy of the mathematical structure of our models. Despite the importance of model parameters, there is no general method of parameter estimation outside linear systems. A new relatively simple method of parameter estimation for nonlinear systems is presented, based on variations in the accuracy of probability forecasts. It is illustrated on the Logistic Map, the Henon Map and the 12-D Lorenz96 flow, and its ability to outperform linear least squares in these systems is explored at various noise levels and sampling rates. As expected, it is more effective when the forecast error distributions are non-Gaussian. The new method selects parameter values by minimizing a proper, local skill score for continuous probability forecasts as a function of the parameter values. This new approach is easier to implement in practice than alter...

  12. The Progression of Sequential Reactions

    Jack McGeachy


    Full Text Available Sequential reactions consist of linked reactions in which the product of the first reaction becomes the substrate of a second reaction. Sequential reactions occur in industrially important processes, such as the chlorination of methane. A generalized series of three sequential reactions was analyzed in order to determine the times at which each chemical species reaches its maximum. To determine the concentration of each species as a function of time, the differential rate laws for each species were solved. The solution of each gave the concentration curve of the chemical species. The concentration curves of species A1 and A2 possessed discreet maxima, which were determined through slope-analysis. The concentration curve of the final product, A3, did not possess a discreet maximum, but rather approached a finite limit.

  13. Theoretical Study on the NO2 + NO2- Electron Transfer Reaction

    ZHOU,Zheng-Yu(周正宇); GAO,Hong-Wei(高洪伟); XING,Yu-Mei(邢玉梅); GUO,Li(郭丽); QU,Yu-Hui(曲玉辉)


    The NO2 + NO2- electron transfer reaction was studied with DFT-B3LYP method at 6-311 + G* basis set level for the eight selected structures: four species favor the strucure of "head to head". The geometry of transition state was obtained by the linear coordinate method. Three parameters, non-adiahatic activation energy (Ead), coupling matrix element (Hif) and reorganization energy (λ) for electron transfer reaction can be calculated. According to the reorganization energy of the ET reaction, the values obtained from George-Griffith-Marcus (GGM) method (the contribution only from diagonal elements of force constant matrix) are larger than those obtained from Hessian matrix method (including the contribution from both diagonal and off-diagonal elements), which suggests that the coupling interactions between different vibrational modes are important to the inner-sphere reogrganization energy for the ET reactions in gaseous phase. The value of rate constant was obtained by using above three activation parameters.

  14. Site selectivity of specific reaction steps important for catalysis

    Nielsen, Kenneth

    it was possible to shift its TPD behavior from the nano-particle type to the single crystal type by annealing it for 600 s at 900 K. In the Bi/Pt(111) side project samples was prepared by PVD of bismuth on a Pt(111) single crystal, after which the sample was subjected to successively increasing heat treatments...... and characterized with XPS and STM. From the experiments it was determined that the 500C 3 min heat treatment was sucient to evaporate the bismuth in excess of 1ML from the sample. Furthermore, two small shifts was observed in the XPS binding energy of the Bi 4f 7=2 peak. The first 0.08±0.02 eV shift up is likely...... due to the ordering of the overlayers after the first heat treatment at 300C 3 min. The second 0.10±0.02 eV shift down after the heat treatment to 500C for 30 min could be due to the evaporation of the excess bismuth layers or to alloying of the bismuth into the platinum surface. The STM images showed...

  15. Increasing awareness of corticosteroid hypersensitivity reactions is important

    Knarborg, Malene; Bendstrup, Elisabeth; Hilberg, Ole


    the tolerability to other corticosteroid preparations and thus identify a safe treatment alternative. We report a case of corticosteroid hypersensitivity in a 65-year-old woman with a history of difficult-to-treat asthma and systemic corticosteroid allergy admitted with increasing dyspnea and dry cough...

  16. Palladium-catalyzed coupling reactions

    Molnár, Árpád


    This handbook and ready reference brings together all significant issues of practical importance for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of modern-day coupling reactions and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With i

  17. Effects of process parameters on hydrothermal carbonization

    Uddin, Md. Helal

    In recent years there has been increased research activity in renewable energy, especially upgrading widely available lignicellulosic biomass, in a bid to counter the increasing environmental concerns related with the use of fossil fuels. Hydrothermal carbonization (HTC), also known as wet torrefaction or hot water pretreatment, is a process for pretreatment of diverse lignocellulosic biomass feedstocks, where biomass is treated under subcritical water conditions in short contact time to produce high-value products. The products of this process are: a solid mass characterized as biochar/biocoal/biocarbon, which is homogeneous, energy dense, and hydrophobic; a liquid stream composed of five and six carbon sugars, various organic acids, and 5-HMF; and a gaseous stream, mainly CO2. A number of process parameters are considered important for the extensive application of the HTC process. Primarily, reaction temperature determines the characteristics of the products. In the solid product, the oxygen carbon ratio decreases with increasing reaction temperature and as a result, HTC biochar has the similar characteristics to low rank coal. However, liquid and gaseous stream compositions are largely correlated with the residence time. Biomass particle size can also limit the reaction kinetics due to the mass transfer effect. Recycling of process water can help to minimize the utility consumption and reduce the waste treatment cost as a result of less environmental impact. Loblolly pine was treated in hot compressed water at 200 °C, 230 °C, and 260 °C with 5:1 water:biomass mass ratio to investigate the effects of process parameters on HTC. The solid product were characterized by their mass yields, higher heating values (HHV), and equilibrium moisture content (EMC), while the liquid were characterized by their total organic carbon content and pH value.

  18. A model for reaction-assisted polymer dissolution in LIGA.

    Larson, Richard S.


    A new chemically-oriented mathematical model for the development step of the LIGA process is presented. The key assumption is that the developer can react with the polymeric resist material in order to increase the solubility of the latter, thereby partially overcoming the need to reduce the polymer size. The ease with which this reaction takes place is assumed to be determined by the number of side chain scissions that occur during the x-ray exposure phase of the process. The dynamics of the dissolution process are simulated by solving the reaction-diffusion equations for this three-component, two-phase system, the three species being the unreacted and reacted polymers and the solvent. The mass fluxes are described by the multicomponent diffusion (Stefan-Maxwell) equations, and the chemical potentials are assumed to be given by the Flory-Huggins theory. Sample calculations are used to determine the dependence of the dissolution rate on key system parameters such as the reaction rate constant, polymer size, solid-phase diffusivity, and Flory-Huggins interaction parameters. A simple photochemistry model is used to relate the reaction rate constant and the polymer size to the absorbed x-ray dose. The resulting formula for the dissolution rate as a function of dose and temperature is ?t to an extensive experimental data base in order to evaluate a set of unknown global parameters. The results suggest that reaction-assisted dissolution is very important at low doses and low temperatures, the solubility of the unreacted polymer being too small for it to be dissolved at an appreciable rate. However, at high doses or at higher temperatures, the solubility is such that the reaction is no longer needed, and dissolution can take place via the conventional route. These results provide an explanation for the observed dependences of both the dissolution rate and its activation energy on the absorbed dose.

  19. Theory of diffusion-influenced reactions in complex geometries

    Galanti, Marta; Fanelli, Duccio; Traytak, Sergey D.; Piazza, Francesco

    Chemical reactions involving diffusion of reactants and subsequent chemical fixation steps are generally termed "diffusion-influenced" (DI). Virtually all biochemical processes in living media can be counted among them, together with those occurring in an ever-growing number of emerging nano-technologies. The role of the environment's geometry (obstacles, compartmentalization) and distributed reactivity (competitive reactants, traps) is key in modulating the rate constants of DI reactions, and is therefore a prime design parameter. Yet, it is a formidable challenge to build a comprehensive theory able to describe the environment's "reactive geometry". Here we show that such a theory can be built by unfolding this many-body problem through addition theorems for special functions. Our method is powerful and general and allows one to study a given DI reaction occurring in arbitrary "reactive landscapes", made of multiple spherical boundaries of given size and reactivity. Importantly, ready-to-use analytical formulas can be derived easily in most cases.

  20. Modelling population growth with delayed nonlocal reaction in 2-dimensions.

    Liang, Dong; Wu, Jianhong; Zhang, Fan


    In this paper, we consider the population growth of a single species living in a two-dimensional spatial domain. New reaction-difusion equation models with delayed nonlocal reaction are developed in two-dimensional bounded domains combining diferent boundary conditions. The important feature of the models is the reflection of the joint efect of the difusion dynamics and the nonlocal maturation delayed efect. We consider and ana- lyze numerical solutions of the mature population dynamics with some wellknown birth functions. In particular, we observe and study the occurrences of asymptotically stable steady state solutions and periodic waves for the two-dimensional problems with nonlocal delayed reaction. We also investigate numerically the efects of various parameters on the period, the peak and the shape of the periodic wave as well as the shape of the asymptotically stable steady state solution.

  1. Theory of diffusion-influenced reactions in complex geometries

    Galanti, Marta; Piazza, Francesco


    Chemical reactions involving diffusion of reactants and subsequent chemical fixation steps are generally termed "diffusion-influenced" (DI). Virtually all biochemical processes in living media can be counted among them, together with those occurring in an ever-growing number of emerging nano-technologies. The role of the environment's geometry (obstacles, compartmentalization) and distributed reactivity (competitive reactants, traps) is key in modulating the rate constants of DI reactions, and is therefore a prime design parameter. Yet, it is a formidable challenge to build a comprehensive theory able to describe the environment's "reactive geometry". Here we show that such a theory can be built by unfolding this many-body problem through addition theorems for special functions. Our method is powerful and general and allows one to study a given DI reaction occurring in arbitrary "reactive landscapes", made of multiple spherical boundaries of given size and reactivity. Importantly, ready-to-use analytical form...

  2. Cluster knockout reactions

    Arun K Jain; B N Joshi


    Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile–cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (, 2) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.

  3. 基于响应曲面和重要性抽样方法的热力系统参数失效概率计算%Calculation of Parameter Failure Probability of Thermodynamic System by Response Surface and Importance Sampling Method

    尚彦龙; 蔡琦; 陈力生; 张杨伟


    本文研究了将响应曲面与重要性抽样相结合的方法用于复杂热力系统参数失效概率的计算.建立了热力系统物理过程参数失效的数学模型,在此基础上研究了将响应曲面与重要性抽样相结合的算法模型,并给出了热力系统组成设备的性能退化模型和基于重要性抽样的仿真流程,进而对反应堆净化系统工作过程中参数失效问题进行了分析计算.研究表明,对于高维、非线性特性明显并考虑性能退化的复杂热力系统参数失效概率的计算,重要性抽样法较直接抽样能以较高效率获得满意精度的计算结果,而响应曲面法存在局限;响应曲面和重要性抽样相结合的方法是分析热力系统物理过程参数失效的有效方法.%In this paper, the combined method of response surface and importance sampling was applied for calculation of parameter failure probability of the thermodynamic system. The mathematics model was present for the parameter failure of physics process in the thermodynamic system, by which the combination arithmetic model of response surface and importance sampling was established, then the performance degradation model of the components and the simulation process of parameter failure in the physics process of thermodynamic system were also present. The parameter failure probability of the purification water system in nuclear reactor was obtained by the combination method. The results show that the combination method is an effective method for the calculation of the parameter failure probability of the thermodynamic system with high dimensionality and non-linear characteristics, because of the satisfactory precision with less computing time than the direct sampling method and the draw-backs of response surface method.

  4. Bayesian Estimation of Thermonuclear Reaction Rates

    Iliadis, C.; Anderson, K. S.; Coc, A.; Timmes, F. X.; Starrfield, S.


    The problem of estimating non-resonant astrophysical S-factors and thermonuclear reaction rates, based on measured nuclear cross sections, is of major interest for nuclear energy generation, neutrino physics, and element synthesis. Many different methods have been applied to this problem in the past, almost all of them based on traditional statistics. Bayesian methods, on the other hand, are now in widespread use in the physical sciences. In astronomy, for example, Bayesian statistics is applied to the observation of extrasolar planets, gravitational waves, and Type Ia supernovae. However, nuclear physics, in particular, has been slow to adopt Bayesian methods. We present astrophysical S-factors and reaction rates based on Bayesian statistics. We develop a framework that incorporates robust parameter estimation, systematic effects, and non-Gaussian uncertainties in a consistent manner. The method is applied to the reactions d(p,γ)3He, 3He(3He,2p)4He, and 3He(α,γ)7Be, important for deuterium burning, solar neutrinos, and Big Bang nucleosynthesis.

  5. The human acrosome reaction

    H.W.G.Baker; D.Y.Liu; C.Garrett; M.Martic


    We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, spermzona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertilization (IVF). Although oocyte defects contribute to failure of sperm oocyte interaction, rarely are all oocytes from one woman affected. Low or zero fertilization in standard IVFwas usually caused by sperm abnormalities. Poor sperm-zona pellucida binding was frequently associated with failure of standard IVF and obvious defects of sperm motility or morphology. The size and shape of the acrosome is particularly important for sperm binding to the oocyte. The proportion of acrosome intact sperm in the insemination medium was related to the IVF rate. Inducing the acrosome reaction with a calcium ionophore reduced sperm-zona binding. Blocking acrosome dispersal with an acrosin inhibitor prevented spermzona penetration. Sperm-zona penetration was even more highly related to IVF rates than was sperm-zona binding. Some patients had low or zero fertilization rates with standard IVF but normal sperm by conventional tests and normal sperm-zona binding. Few of their sperm underwent the acrosome reaction on the surface of the zona and none penetrated the zona. In contrast, fertilization and pregnancy rates were high with intracytoplasmic sperm injection. We call thiscondition defective zona pellucida induced acrosome reaction. Discovery of the nature of the abnormalities in the signal transduction and effector pathways of the human zona pellucida induced acrosome reaction should result in simpler tests and treatments for the patients and also provide new leads for contraceptive development.

  6. Eikonal reaction theory for two-neutron removal reactions

    Minomo, K; Egashira, K; Ogata, K; Yahiro, M


    The eikonal reaction theory (ERT) proposed lately is a method of calculating one-neutron removal reactions at intermediate incident energies in which Coulomb breakup is treated accurately with the continuum discretized coupled-channels method. ERT is extended to two-neutron removal reactions. ERT reproduces measured one- and two-neutron removal cross sections for 6He scattering on 12C and 208Pb targets at 240 MeV/nucleon and also on a 28Si target at 52 MeV/nucleon. For the heavier target in which Coulomb breakup is important, ERT yields much better agreement with the measured cross sections than the Glauber model.

  7. Parameter estimation in food science.

    Dolan, Kirk D; Mishra, Dharmendra K


    Modeling includes two distinct parts, the forward problem and the inverse problem. The forward problem-computing y(t) given known parameters-has received much attention, especially with the explosion of commercial simulation software. What is rarely made clear is that the forward results can be no better than the accuracy of the parameters. Therefore, the inverse problem-estimation of parameters given measured y(t)-is at least as important as the forward problem. However, in the food science literature there has been little attention paid to the accuracy of parameters. The purpose of this article is to summarize the state of the art of parameter estimation in food science, to review some of the common food science models used for parameter estimation (for microbial inactivation and growth, thermal properties, and kinetics), and to suggest a generic method to standardize parameter estimation, thereby making research results more useful. Scaled sensitivity coefficients are introduced and shown to be important in parameter identifiability. Sequential estimation and optimal experimental design are also reviewed as powerful parameter estimation methods that are beginning to be used in the food science literature.

  8. Application of chaotic theory to parameter estimation


    High precision parameter estimation is very important for control system design and compensation. This paper utilizes the properties of chaotic system for parameter estimation. Theoretical analysis and experimental results indicated that this method has extremely high sensitivity and resolving power. The most important contribution of this paper is apart from the traditional engineering viewpoint and actualizing parameter estimation just based on unstable chaotic systems.


    XU Haiyan; FEI Heliang


    Because of the importance of grouped data, many scholars have been devoted to the study of this kind of data. But, few documents have been concerned with the threshold parameter. In this paper, we assume that the threshold parameter is smaller than the first observing point. Then, on the basis of the two-parameter exponential distribution, the maximum likelihood estimations of both parameters are given, the sufficient and necessary conditions for their existence and uniqueness are argued, and the asymptotic properties of the estimations are also presented, according to which approximate confidence intervals of the parameters are derived. At the same time, the estimation of the parameters is generalized, and some methods are introduced to get explicit expressions of these generalized estimations. Also, a special case where the first failure time of the units is observed is considered.

  10. Detecting radiation reaction at moderate laser intensities.

    Heinzl, Thomas; Harvey, Chris; Ilderton, Anton; Marklund, Mattias; Bulanov, Stepan S; Rykovanov, Sergey; Schroeder, Carl B; Esarey, Eric; Leemans, Wim P


    We propose a new method of detecting radiation reaction effects in the motion of particles subjected to laser pulses of moderate intensity and long duration. The effect becomes sizable for particles that gain almost no energy through the interaction with the laser pulse. Hence, there are regions of parameter space in which radiation reaction is actually the dominant influence on charged particle motion.

  11. Test of statistical model cross section calculations for $\\alpha$-induced reactions on $^{107}$Ag at energies of astrophysical interest

    Yalcin, C; Rauscher, T; Kiss, G G; Özkan, N; Güray, R T; Halász, Z; Szücs, T; Fülöp, Zs; Korkulu, Z; Somorjai, E


    Astrophysical reaction rates, which are mostly derived from theoretical cross sections, are necessary input to nuclear reaction network simulations for studying the origin of $p$ nuclei. Past experiments have found a considerable difference between theoretical and experimental cross sections in some cases, especially for ($\\alpha$,$\\gamma$) reactions at low energy. Therefore, it is important to experimentally test theoretical cross section predictions at low, astrophysically relevant energies. The aim is to measure reaction cross sections of $^{107}$Ag($\\alpha$,$\\gamma$)$^{111}$In and $^{107}$Ag($\\alpha$,n)$^{110}$In at low energies in order to extend the experimental database for astrophysical reactions involving $\\alpha$ particles towards lower mass numbers. Reaction rate predictions are very sensitive to the optical model parameters and this introduces a large uncertainty into theoretical rates involving $\\alpha$ particles at low energy. We have also used Hauser-Feshbach statistical model calculations to s...

  12. Enzymatic Reactions in Microfluidic Devices

    Ristenpart, W. D.; Wan, J.; Stone, H. A.


    We establish simple scaling laws for enzymatic reactions in microfluidic devices, and we demonstrate that kinetic parameters obtained conventionally using multiple stop-flow experiments may instead be extracted from a single microfluidic experiment. Introduction of an enzyme and substrate species in different arms of a Y-shaped channel allows the two species to diffuse across the parallel streamlines and to begin reacting. Measurements of the product concentration versus distance down the channel provide information about the kinetics of the reaction. In the limit where the enzyme is much larger (and thus less diffusive) than the substrate, we show that near the entrance the total amount of product (P) formed varies as a power law in the distance x down the channel. For reactions that follow standard Michaelis-Menten kinetics, the power law takes the form P˜(Vmax/Km) x^5/2, where Vmax and Km are the maximum reaction rate and Michaelis constant respectively. If a large excess of substrate is used, then Km is identified by measuring Vmax far downstream where the different species are completely mixed by diffusion. Numerical simulations and experiments using the bioluminescent reaction between luciferase and ATP as a model system are both shown to accord with the model. We discuss the implications for significant savings in the amount of time and enzyme required for determination of kinetic parameters.

  13. [Arthropod bite reactions and pyodermias].

    Hengge, U R


    Tourists in the tropics often develop reactions to bites or stings of mosquitoes, fleas, mites, ants, bedbugs, beetles, larva, millipedes, spiders and scorpions. In addition, they may have fresh or salt water exposure to sponges, corals, jellyfish and sea urchins with resultant injury and inflammation. Bacterial skin infections (pyodermias) can follow bites or stings as well as mechanical trauma. The most common bacteria involved in skin infections are staphylococci and streptococci. For tourists, bacterial infections are often complicating a pruritic bite reaction and scratching. It is important to know the cause of the bite reaction and pyoderma in order to take appropriate therapeutic measures.

  14. Organocatalytic Enantioselective Henry Reactions

    Raquel P. Herrera


    Full Text Available A large number of interesting organocatalytic enantioselective protocols have been explored and successfully applied in the last decade. Among them, the Henry (nitroaldol reaction represents a powerful carbon-carbon bond-forming procedure for the preparation of valuable synthetic intermediates, such as enantioenriched nitro alcohols, which can be further transformed in a number of important nitrogen and oxygen-containing compounds. This area of research is still in expansion and a more complex version of this useful process has recently emerged, the domino Michael/Henry protocol, affording highly functionalized cycles with multiple stereogenic centers.

  15. Quantum dynamics of the abstraction reaction of H with cyclopropane.

    Shan, Xiao; Clary, David C


    The dynamics of the abstraction reaction of H atoms with the cyclopropane molecule is studied using quantum mechanical scattering theory. The quantum scattering calculations are performed in hyperspherical coordinates with a two-dimensional (2D) potential energy surface. The ab initio energy calculations are carried out with CCSD(T)-F12a/cc-pVTZ-F12 level of theory with the geometry and frequency calculations at the MP2/cc-pVTZ level. The contribution to the potential energy surface from the spectator modes is included as the projected zero-point energy correction to the ab initio energy. The 2D surface is fitted with a 29-parameter double Morse potential. An R-matrix propagation scheme is carried out to solve the close-coupled equations. The adiabatic energy barrier and reaction enthalpy are compared with high level computational calculations as well as experimental data. The calculated reaction rate constants shows very good agreement when compared with the experimental data, especially at lower temperature highlighting the importance of quantum tunnelling. The reaction probabilities are also presented and discussed. The special features of performing quantum dynamics calculation on the chemical reaction of a cyclic molecule are discussed.

  16. Python framework for kinetic modeling of electronically excited reaction pathways

    Verboncoeur, John; Parsey, Guy; Guclu, Yaman; Christlieb, Andrew


    The use of plasma energy to enhance and control the chemical reactions during combustion, a technology referred to as ``plasma assisted combustion'' (PAC), can result in a variety of beneficial effects: e.g. stable lean operation, pollution reduction, and wider range of p-T operating conditions. While experimental evidence abounds, theoretical understanding of PAC is at best incomplete, and numerical tools still lack in reliable predictive capabilities. In the context of a joint experimental-numerical effort at Michigan State University, we present here an open-source modular Python framework dedicated to the dynamic optimization of non-equilibrium PAC systems. Multiple sources of experimental reaction data, e.g. reaction rates, cross-sections and oscillator strengths, are used in order to quantify the effect of data uncertainty and limiting assumptions. A collisional-radiative model (CRM) is implemented to organize reactions by importance and as a potential means of measuring a non-Maxwellian electron energy distribution function (EEDF), when coupled to optical emission spectroscopy data. Finally, we explore scaling laws in PAC parameter space using a kinetic global model (KGM) accelerated with CRM optimized reaction sequences and sparse stiff integrators.

  17. Catalysis of Photochemical Reactions.

    Albini, A.


    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  18. [Allergic reactions to transfusion].

    Hergon, E; Paitre, M L; Coeffic, B; Piard, N; Bidet, J M


    Frequent allergic reactions following transfusion are observed. Usually, they are benign but sometimes we observe severe allergic reactions. Adverse reactions may be brought about by least two mechanisms. First, immediate-type hypersensibility reactions due to IgE. Secondly, anaphylactic-type reactions due to interaction between transfused IgA and class specific anti IgA in the recipient's plasma. They are characterized by their severest form (anaphylactic shock). The frequency of severe reactions following the transfusion blood plasma is very low. These transfusion reactions are complement-mediated and kinins-mediated. Prevention of allergic reactions is necessary among blood donors and recipients.

  19. A ZeroDimensional Model of a 2nd Generation Planar SOFC Using Calibrated Parameters

    Brian Elmegaard


    Full Text Available This paper presents a zero-dimensional mathematical model of a planar 2nd generation coflow SOFC developed for simulation of power systems. The model accounts for the electrochemical oxidation of hydrogen as well as the methane reforming reaction and the water-gas shift reaction. An important part of the paper is the electrochemical sub-model, where experimental data was used to calibrate specific parameters. The SOFC model was implemented in the DNA simulation software which is designed for energy system simulation. The result is an accurate and flexible tool suitable for simulation of many different SOFC-based power systems.

  20. 复合随机振动系统的动力可靠性矩独立重要性测度及态相关参数解法%Moment-independent importance measure of dynamic reliability for double random vibration systems and its state dependent parameter solution

    张屹尚; 刘永寿; 赵彬; 翟红波


    针对激励与结构参数同时存在不确定性的复合随机振动系统,由随机结构无条件动力可靠度表达式出发,利用条件概率密度函数解析变换给出衡量基本随机变量对动力可靠性影响的矩独立重要性测度指标。该指标可表征不确定性随机变量对动力可靠度响应量分布的平均影响程度,可全面反映随机变量对响应分布影响。基于状态依存参数模型,提出求解矩独立重要性测度指标的态相关参数(SDP)法。利用算例分析结构动力可靠性参数的矩独立重要性测度,并与直接 Monte -Carlo 法对比。所提方法可在保证计算精度同时大幅度提高计算效率,适用于分析复合随机振动系统非线性可靠性响应。%A moment-independent importance measure index of dynamic reliability for double random vibration systems,in which the randomness of structural parameters and excitation was taken into account,was introduced to analyze the effect of input variables on dynamic reliability.Based on the expressions of unconditional dynamic reliability and conditional probability density function (PDF),the importance measure index was numerically obtained.The index can effectively describe the mean effect of the PDF on dynamic reliability from the distribution density of the basic variable.Then,on the basis of the state dependent parameter (SDP)model,the SDP method was established to estimate the defined moment-independent importance measure index.Additionally,two examples were given to illustrate the advantages of the presented method.Comparing with the direct Monte Carlo method,the results show that the established solution can considerably improve computational efficiency with acceptable precision and be suitable for analyzing non-linear dynamic reliability responses of double random vibration systems.

  1. Determination of the hemocytology and blood biochemical parameters in imported malarial patients in Beijing areas%北京地区输入性疟疾血细胞及生化检验指标变化的敏感性分析

    邹洋; 李晶晶; 黄敏君; 谷俊朝; 魏巍; 李小丽; 王磊; 王非; 李威; 齐志群; 田小军; 安亦君


    Objective To investigate the clinical significance by determining the biochemical indicators on urine and blood for early diagnosis of imported malarial patients. Methods The parameters of urine and blood biochemistry were retrospectively analyzed in 55 clinically confirmed patients with imported malaria in Beijing area with multiple Logistic regression by using software SPSS 18.0, and the results were compared with health controls. Results The biochemical parameters, including decreased blood platelet(OR=0.980, P=0.003), elevated glutamic-oxaloacetic transaminase(OR=0.969, P=0.013) and blood urea nitrogen(OR=1.907, P=0.013), were statistically significant in early stage of infection in imported malarial patients. Conclusion Bio⁃chemical parameters changed significantly in the early stage of infection in patients of imported malaria, suggest⁃ing that determination of these indicators can lead to early diagnosis and treatment of this disease.%目的:分析输入性疟疾患者确诊前的各项血、尿常规和血生化等检查指标,探讨各检测参数指标的临床早期诊断方面的意义。方法使用SPSS 18.0软件,回顾性分析55例临床确诊输入性疟疾患者的各项血、尿常规和血生化等检查指标,并建立正常对照组。采用Logistic多元回归分析,初步完成输入性疟疾各检验参数指标的分析。结果血常规中血小板减少(OR=0.980,P=0.003),肝功能中谷草转氨酶升高(OR=0.969,P=0.013),和尿素氮的变化(OR=1.907,P=0.013),在疟疾早期各生化指标变化中具有明显意义。结论通过本次研究,初步表明血常规中血小板减少,肝功能中谷草转氨酶升高,和尿素氮的变化,在疟疾早期各生化指标变化中具有明显意义。其综合判断,有利于输入性疟疾诊断早期预警,降低误诊率,提高诊断率。对疟疾的临床早期诊断具有重要意义。

  2. Determination and analysis of synchronous motor's parameters

    Mesņajevs, Aleksandrs; Zviedris, Andrejs


    In this work the parameters of synchronous machines are analyzed- direct-axis reaction Xad and quadrature-axis reaction Xaq. Methods of calculation in view of magnetic system's and its element's saturation are presented. It is shown that definition of these reactances, using as a basis a two-reaction method, is not correct and connected with work demanding chart analyzing calculations. The new approach to the qualitative and quantitative analysis of synchronous machine's operating modes which is based on consecutive use of the magnetic field's theory is offered, without it with two-reaction parameters Xad and Xaq. This approach is realized by means of a magnetic field's modeling using numerical methods with help of modern computers.

  3. Understanding Active Metal Reaction Kinetis with Cu-Mg Replacement Reaction

    Ilhami Ceyhun; Zafer Karagolge


    Metal substitution reactions are simple redox reactions. Thesereactions demonstrate the relative activity and the electrochemicalseries of metals. In particular, the purpose of thisstudy is to help students comprehend the displacement reactionamong, Mg metal and solutions containing Cu$^{+2}$, Ni$^{+2}$,Pb$^{+2}$, Cd$^{+2}$, Co$^{+2}$. This study is an important experiment towardsunderstanding reaction kinetics.

  4. Investigation of the quasifission process by theoretical analysis of experimental data of fissionlike reaction products

    Giardina, G; Mandaglio, G; Curciarello, F; De Leo, V; Fazio, G; Manganaro, M; Romaniuk, M; Saccá, C; 10.1088/1742-6596/282/1/012006


    The fusion excitation function is the important quantity in planning experiments for the synthesis of superheavy elements. Its values seem to be determined by the experimental study of the hindrance to complete fusion by the observation of mass, angular and energy distributions of the fissionlike fragments. There is ambiguity in establishment of the reaction mechanism leading to the observed binary fissionlike fragments. The fissionlike fragments can be produced in the quasifission, fast fission, and fusion-fission processes which have overlapping in the mass (angular, kinetic energy) distributions of fragments. The branching ratio between quasifission and complete fusion strongly depends on the characteristics of the entrance channel. In this paper we consider a wide set of reactions (with different mass asymmetry and mass symmetry parameters) with the aim to explain the role played by many quantities on the reaction mechanisms. We also present the results of study of the $^{48}$Ca+$^{249}$Bk reaction used t...

  5. An optimal adaptive time-stepping scheme for solving reaction-diffusion-chemotaxis systems.

    Chiu, Chichia; Yu, Jui-Ling


    Reaction-diffusion-chemotaxis systems have proven to be fairly accurate mathematical models for many pattern formation problems in chemistry and biology. These systems are important for computer simulations of patterns, parameter estimations as well as analysis of the biological systems. To solve reaction-diffusion-chemotaxis systems, efficient and reliable numerical algorithms are essential for pattern generations. In this paper, a general reaction-diffusion-chemotaxis system is considered for specific numerical issues of pattern simulations. We propose a fully explicit discretization combined with a variable optimal time step strategy for solving the reaction-diffusion-chemotaxis system. Theorems about stability and convergence of the algorithm are given to show that the algorithm is highly stable and efficient. Numerical experiment results on a model problem are given for comparison with other numerical methods. Simulations on two real biological experiments will also be shown.

  6. Automatic generation of reaction energy databases from highly accurate atomization energy benchmark sets.

    Margraf, Johannes T; Ranasinghe, Duminda S; Bartlett, Rodney J


    In this contribution, we discuss how reaction energy benchmark sets can automatically be created from arbitrary atomization energy databases. As an example, over 11 000 reaction energies derived from the W4-11 database, as well as some relevant subsets are reported. Importantly, there is only very modest computational overhead involved in computing >11 000 reaction energies compared to 140 atomization energies, since the rate-determining step for either benchmark is performing the same 140 quantum chemical calculations. The performance of commonly used electronic structure methods for the new database is analyzed. This allows investigating the relationship between the performances for atomization and reaction energy benchmarks based on an identical set of molecules. The atomization energy is found to be a weak predictor for the overall usefulness of a method. The performance of density functional approximations in light of the number of empirically optimized parameters used in their design is also discussed.

  7. A Reaction-based Diagonalization Approach to Modeling Surface Water Quality

    Yu, J.; Yeh, G.; Zhang, F.; Wu, T.; Hu, G.


    There are many water quality models (e.g., WASP, QAUL2E/QUAL2K, CE-QUAL-ICM, RCA, RMA11, etc.) that have been employed by practitioners in surface water quality modeling. All of these models are similar to each others. The major differences among them are the number of water quality parameters included and the number of biogeochemical processes considered. Because of the limitation on the number of biogeochemical processes considered and, in a lesser extent, on the number of water quality parameters included, these models often perform only fairly in validation and their predictions may be unreliable, even though they can be adequately calibrated in most occasions and excellently in some occasions. Obviously, there is a need to develop a model that would allow the inclusion of any number of water quality parameters and enable the hypothesis of any number of biogeochemical processes. This paper presents the development of a numerical water quality model using a general paradigm of reaction-based approaches. In a reaction-based approach, all conceptualized biogoechemical processes are transformed into a reaction network. Through the decomposition of species governing equations via Gauss-Jordan column reduction of the reaction network, (1) redundant fast reactions and irrelevant kinetic reactions are removed from the system, which alleviates the problem of unnecessary and erroneous formulation and parameterization of these reactions, and (2) fast reactions and slow reactions are decoupled, which enables robust numerical integrations. The system of species governing equations is transformed into two sets: algebraic equations (either mass action equations or users' specified) of equilibrium variables and differential equations of kinetic variables. As a result, the model alleviates the needs of using simple partitions for fast reactions and uses kinetic-variables instead of biogeochemical species as primary dependent variables. With the diagonalization strategy, it

  8. Thermal reactions of brushite cements.

    Bohner, M; Gbureck, U


    The thermal reactions of a brushite cement made of beta-tricalcium phosphate (beta-TCP), monocalcium phosphate monohydrate (MCPM), and an aqueous solution were followed in situ with an isothermal calorimeter at 37 degrees C. The investigated parameters were the beta-TCP/MCPM weight ratio, the liquid-to-powder ratio, the synthesis route and milling duration of the beta-TCP powder, as well as the presence of sulfate, citrate, and pyrophosphate ions in the mixing liquid. The thermograms were complex, particularly for mixtures containing an excess of MCPM or additives in the mixing solution. Results suggested that the endothermic MCPM dissolution and the highly exothermic beta-TCP dissolution occurred simultaneously, thereby leading to the formation of a large exothermic peak at early reaction time. Both reactions were followed by the exothermic crystallization of brushite and in the presence of an excess of MCPM by the endothermic crystallization of monetite. Additives generally widened the main exothermic reaction peak, or in some cases with pyrophosphate ions postponed the main exothermic peak at late reaction time. Generally, the results could be well explained and understood based on thermodynamic and solubility data.

  9. Image guided personalization of reaction-diffusion type tumor growth models using modified anisotropic eikonal equations.

    Konukoglu, Ender; Clatz, Olivier; Menze, Bjoern H; Stieltjes, Bram; Weber, Marc-André; Mandonnet, Emmanuel; Delingette, Hervé; Ayache, Nicholas


    Reaction-diffusion based tumor growth models have been widely used in the literature for modeling the growth of brain gliomas. Lately, recent models have started integrating medical images in their formulation. Including different tissue types, geometry of the brain and the directions of white matter fiber tracts improved the spatial accuracy of reaction-diffusion models. The adaptation of the general model to the specific patient cases on the other hand has not been studied thoroughly yet. In this paper, we address this adaptation. We propose a parameter estimation method for reaction-diffusion tumor growth models using time series of medical images. This method estimates the patient specific parameters of the model using the images of the patient taken at successive time instances. The proposed method formulates the evolution of the tumor delineation visible in the images based on the reaction-diffusion dynamics; therefore, it remains consistent with the information available. We perform thorough analysis of the method using synthetic tumors and show important couplings between parameters of the reaction-diffusion model. We show that several parameters can be uniquely identified in the case of fixing one parameter, namely the proliferation rate of tumor cells. Moreover, regardless of the value the proliferation rate is fixed to, the speed of growth of the tumor can be estimated in terms of the model parameters with accuracy. We also show that using the model-based speed, we can simulate the evolution of the tumor for the specific patient case. Finally, we apply our method to two real cases and show promising preliminary results.

  10. Uniqueness is Important in Competition

    FENG Ai-Xia; XV Xiu-Lian; HE Da-Ren


    We propose a quantitative network description on the function of uniqueness in a competition system. Two statistical parameters, competition ability and uniqueness are defined, and their relationship in ordinary cases is analytically discussed. The competition between Chinese regional universities is taken as an example. The empirical investigation results show that the uniqueness of a university is really important in competition. Also,uniqueness is very helpful in the promotion of the university overall quality.

  11. Assessment and parameter identification of simplified models to describe the kinetics of semi-continuous biomethane production from anaerobic digestion of green and food waste.

    Owhondah, Raymond O; Walker, Mark; Ma, Lin; Nimmo, Bill; Ingham, Derek B; Poggio, Davide; Pourkashanian, Mohamed


    Biochemical reactions occurring during anaerobic digestion have been modelled using reaction kinetic equations such as first-order, Contois and Monod which are then combined to form mechanistic models. This work considers models which include between one and three biochemical reactions to investigate if the choice of the reaction rate equation, complexity of the model structure as well as the inclusion of inhibition plays a key role in the ability of the model to describe the methane production from the semi-continuous anaerobic digestion of green waste (GW) and food waste (FW). A parameter estimation method was used to investigate the most important phenomena influencing the biogas production process. Experimental data were used to numerically estimate the model parameters and the quality of fit was quantified. Results obtained reveal that the model structure (i.e. number of reactions, inhibition) has a much stronger influence on the quality of fit compared with the choice of kinetic rate equations. In the case of GW there was only a marginal improvement when moving from a one to two reaction model, and none with inclusion of inhibition or three reactions. However, the behaviour of FW digestion was more complex and required either a two or three reaction model with inhibition functions for both ammonia and volatile fatty acids. Parameter values for the best fitting models are given for use by other authors.

  12. Avoiding Buffer Interference in ITC Experiments: A Case Study from the Analysis of Entropy-Driven Reactions of Glucose-6-Phosphate Dehydrogenase.

    Bianconi, M Lucia


    Isothermal titration calorimetry (ITC) is a label-free technique that allows the direct determination of the heat absorbed or released in a reaction. Frequently used to determining binding parameters in biomolecular interactions, it is very useful to address enzyme-catalyzed reactions as both kinetic and thermodynamic parameters can be obtained. Since calorimetry measures the total heat effects of a reaction, it is important to consider the contribution of the heat of protonation/deprotonation that is possibly taking place. Here, we show a case study of the reaction catalyzed by the glucose-6-phosphate dehydrogenase (G6PD) from Leuconostoc mesenteroides. This enzyme is able to use either NAD(+) or NADP(+) as a cofactor. The reactions were done in five buffers of different enthalpy of protonation. Depending on the buffer used, the observed calorimetric enthalpy (ΔH(cal)) of the reaction varied from -22.93 kJ/mol (Tris) to 19.37 kJ/mol (phosphate) for the NADP(+)-linked reaction, and -11.67 kJ/mol (Tris) to 7.32 kcal/mol or 30.63 kJ/mol (phosphate) for the NAD(+) reaction. We will use this system as an example of how to extract proton-independent reaction enthalpies from kinetic data to ensure that the reported accurately represent the intrinsic heat of reaction.

  13. Reaction Coordinates and Mechanistic Hypothesis Tests.

    Peters, Baron


    Reaction coordinates are integral to several classic rate theories that can (a) predict kinetic trends across conditions and homologous reactions, (b) extract activation parameters with a clear physical interpretation from experimental rates, and (c) enable efficient calculations of free energy barriers and rates. New trajectory-based rare events methods can provide rates directly from dynamical trajectories without a reaction coordinate. Trajectory-based frameworks can also generate ideal (but abstract) reaction coordinates such as committors and eigenfunctions of the master equation. However, rates and mechanistic insights obtained from trajectory-based methods and abstract coordinates are not readily generalized across simulation conditions or reaction families. We discuss methods for identifying physically meaningful reaction coordinates, including committor analysis, variational transition state theory, Kramers-Langer-Berezhkovskii-Szabo theory, and statistical inference methods that can use path sampling data to screen, mix, and optimize thousands of trial coordinates. Special focus is given to likelihood maximization and inertial likelihood maximization approaches.

  14. Reaction Coordinates and Mechanistic Hypothesis Tests

    Peters, Baron


    Reaction coordinates are integral to several classic rate theories that can (a) predict kinetic trends across conditions and homologous reactions, (b) extract activation parameters with a clear physical interpretation from experimental rates, and (c) enable efficient calculations of free energy barriers and rates. New trajectory-based rare events methods can provide rates directly from dynamical trajectories without a reaction coordinate. Trajectory-based frameworks can also generate ideal (but abstract) reaction coordinates such as committors and eigenfunctions of the master equation. However, rates and mechanistic insights obtained from trajectory-based methods and abstract coordinates are not readily generalized across simulation conditions or reaction families. We discuss methods for identifying physically meaningful reaction coordinates, including committor analysis, variational transition state theory, Kramers-Langer-Berezhkovskii-Szabo theory, and statistical inference methods that can use path sampling data to screen, mix, and optimize thousands of trial coordinates. Special focus is given to likelihood maximization and inertial likelihood maximization approaches.

  15. Controlling chemical reactions of a single particle

    Ratschbacher, Lothar; Sias, Carlo; Köhl, Michael


    The control of chemical reactions is a recurring theme in physics and chemistry. Traditionally, chemical reactions have been investigated by tuning thermodynamic parameters, such as temperature or pressure. More recently, physical methods such as laser or magnetic field control have emerged to provide completely new experimental possibilities, in particular in the realm of cold collisions. The control of reaction pathways is also a critical component to implement molecular quantum information processing. For these undertakings, single particles provide a clean and well-controlled experimental system. Here, we report on the experimental tuning of the exchange reaction rates of a single trapped ion with ultracold neutral atoms by exerting control over both their quantum states. We observe the influence of the hyperfine interaction on chemical reaction rates and branching ratios, and monitor the kinematics of the reaction products. These investigations advance chemistry with single trapped particles towards achi...

  16. Effect of Chemical Reaction on Convective Heat Transfer of Boundary Layer Flow in Nanofluid over a Wedge with Heat Generation/Absorption and Suction

    R. M. Kasmani


    Full Text Available The aim of the present study is to examine the convective heat transfer of nanofluid past a wedge subject to first-order chemical reaction, heat generation/absorption and suction effects. The influence of wedge angle parameter, thermophoresis, Dufour and Soret type diffusivity are included. The local similarity transformation is applied to convert the governing nonlinear partial differential equations into ordinary differential equations. Shooting method integrated with fourth-order Runge-Kutta method is used to solve the ordinary differential equations. The skin friction, heat and mass transfer rates as well as the effects of various parameters on velocity, temperature and solutal concentration profiles are analyzed. The results indicate that when the chemical reaction parameter increases, the heat transfer coefficient increases while the mass transfer coefficient decreases. The effect of chemical reaction parameter is very important in solutal concentration field compared to velocity and temperature profiles since it decreases the solutal concentration of the nanoparticle.

  17. Modeling violent reaction following low speed impact on confined explosives

    Curtis, John Philip; Jones, Andrew; Hughes, Christopher; Reaugh, John


    To ensure the safe storage and deployment of explosives it is important to understand the mechanisms that give rise to ignition and reaction growth in low speed impacts. The High Explosive Response to Mechanical Stimulus (HERMES) material model, integrated in the Lagrangian code LSDYNA, has been developed to model the progress of the reaction after such an impact. The low speed impact characteristics of an HMX based formulation have been examined using the AWE Steven Test. Axisymmetric simulations of an HMX explosive in the AWE Steven Test have been performed. A sensitivity study included the influence of friction, mesh resolution, and confinement. By comparing the experimental and calculated results, key model parameters which determine the explosive's response in this configuration have been identified. The model qualitatively predicts the point of ignition within the vehicle. Future refinements are discussed.

  18. Palladium-Catalysed Coupling Reactions

    de Vries, Johannes G.; Beller, M; Blaser, HU


    Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems

  19. Insect bite reactions

    Sanjay Singh


    Full Text Available Insects are a class of living creatures within the arthropods. Insect bite reactions are commonly seen in clinical practice. The present review touches upon the medically important insects and their places in the classification, the sparse literature on the epidemiology of insect bites in India, and different variables influencing the susceptibility of an individual to insect bites. Clinical features of mosquito bites, hypersensitivity to mosquito bites Epstein-Barr virus NK (HMB-EBV-NK disease, eruptive pseudoangiomatosis, Skeeter syndrome, papular pruritic eruption of HIV/AIDS, and clinical features produced by bed bugs, Mexican chicken bugs, assassin bugs, kissing bugs, fleas, black flies, Blandford flies, louse flies, tsetse flies, midges, and thrips are discussed. Brief account is presented of the immunogenic components of mosquito and bed bug saliva. Papular urticaria is discussed including its epidemiology, the 5 stages of skin reaction, the SCRATCH principle as an aid in diagnosis, and the recent evidence supporting participation of types I, III, and IV hypersensitivity reactions in its causation is summarized. Recent developments in the treatment of pediculosis capitis including spinosad 0.9% suspension, benzyl alcohol 5% lotion, dimethicone 4% lotion, isopropyl myristate 50% rinse, and other suffocants are discussed within the context of evidence derived from randomized controlled trials and key findings of a recent systematic review. We also touch upon a non-chemical treatment of head lice and the ineffectiveness of egg-loosening products. Knockdown resistance (kdr as the genetic mechanism making the lice nerves insensitive to permethrin is discussed along with the surprising contrary clinical evidence from Europe about efficacy of permethrin in children with head lice carrying kdr-like gene. The review also presents a brief account of insects as vectors of diseases and ends with discussion of prevention of insect bites and some

  20. Lumped-parameter models

    Ibsen, Lars Bo; Liingaard, M.


    A lumped-parameter model represents the frequency dependent soil-structure interaction of a massless foundation placed on or embedded into an unbounded soil domain. In this technical report the steps of establishing a lumped-parameter model are presented. Following sections are included in this report: Static and dynamic formulation, Simple lumped-parameter models and Advanced lumped-parameter models. (au)

  1. Simultaneous Thermodynamic and Kinetic Parameters Determination Using Differential Scanning Calorimetry

    Nader Frikha


    Full Text Available Problem statement: The determination of reaction kinetics is of major importance, as for industrial reactors optimization as for environmental reasons or energy limitations. Although calorimetry is often used for the determination of thermodynamic parameters alone, the question that arises is: how can we apply the Differential Scanning Calorimetry for the determination of kinetic parameters. The objective of this study consists to proposing an original methodology for the simultaneous determination of thermodynamic and kinetic parameters, using a laboratory scale Differential Scanning Calorimeter (DSC. The method is applied to the dichromate-catalysed hydrogen peroxide decomposition. Approach: The methodology is based on operating of experiments carried out with a Differential Scanning Calorimeter. The interest of this approach proposed is that it requires very small quantities of reactants (about a few grams to be implemented. The difficulty lies in the fact that, using such microcalorimeters, the reactants temperature cannot directly be measured and a particular calibration procedure has thus to be developed, to determine the media temperature in an indirect way. The proposed methodology for determination of kinetics parameters is based on resolution of the coupled heat and mass balances. Results: A complete kinetic law is proposed. The Arrhenius parameters are determined as frequency factor k0 = 1.39×109 s−1 and activation energy E = 54.9 kJ mol−1. The measured enthalpy of reaction is ΔrH=−94 kJ mol−1. Conclusion: The comparison of the results obtained by such an original methodology with those obtained using a conventional laboratory scale reactor calorimetry, for the kinetics determination of, shows that this new approach is very relevant.

  2. Nanolithographic Fabrication and Heterogeneous Reaction Studies ofTwo-Dimensional Platinum Model Catalyst Systems

    Contreras, Anthony Marshall [Univ. of California, Berkeley, CA (United States)


    In order to better understand the fundamental components that govern catalytic activity, two-dimensional model platinum nanocatalyst arrays have been designed and fabricated. These catalysts arrays are meant to model the interplay of the metal and support important to industrial heterogeneous catalytic reactions. Photolithography and sub-lithographic techniques such as electron beam lithography, size reduction lithography and nanoimprint lithography have been employed to create these platinum nanoarrays. Both in-situ and ex-situ surface science techniques and catalytic reaction measurements were used to correlate the structural parameters of the system to catalytic activity.

  3. Identification of biomolecule mass transport and binding rate parameters in living cells by inverse modeling

    Shirmohammadi Adel


    Full Text Available Abstract Background Quantification of in-vivo biomolecule mass transport and reaction rate parameters from experimental data obtained by Fluorescence Recovery after Photobleaching (FRAP is becoming more important. Methods and results The Osborne-Moré extended version of the Levenberg-Marquardt optimization algorithm was coupled with the experimental data obtained by the Fluorescence Recovery after Photobleaching (FRAP protocol, and the numerical solution of a set of two partial differential equations governing macromolecule mass transport and reaction in living cells, to inversely estimate optimized values of the molecular diffusion coefficient and binding rate parameters of GFP-tagged glucocorticoid receptor. The results indicate that the FRAP protocol provides enough information to estimate one parameter uniquely using a nonlinear optimization technique. Coupling FRAP experimental data with the inverse modeling strategy, one can also uniquely estimate the individual values of the binding rate coefficients if the molecular diffusion coefficient is known. One can also simultaneously estimate the dissociation rate parameter and molecular diffusion coefficient given the pseudo-association rate parameter is known. However, the protocol provides insufficient information for unique simultaneous estimation of three parameters (diffusion coefficient and binding rate parameters owing to the high intercorrelation between the molecular diffusion coefficient and pseudo-association rate parameter. Attempts to estimate macromolecule mass transport and binding rate parameters simultaneously from FRAP data result in misleading conclusions regarding concentrations of free macromolecule and bound complex inside the cell, average binding time per vacant site, average time for diffusion of macromolecules from one site to the next, and slow or rapid mobility of biomolecules in cells. Conclusion To obtain unique values for molecular diffusion coefficient and

  4. Infrared Drying Parameter Optimization

    Jackson, Matthew R.

    In recent years, much research has been done to explore direct printing methods, such as screen and inkjet printing, as alternatives to the traditional lithographic process. The primary motivation is reduction of the material costs associated with producing common electronic devices. Much of this research has focused on developing inkjet or screen paste formulations that can be printed on a variety of substrates, and which have similar conductivity performance to the materials currently used in the manufacturing of circuit boards and other electronic devices. Very little research has been done to develop a process that would use direct printing methods to manufacture electronic devices in high volumes. This study focuses on developing and optimizing a drying process for conductive copper ink in a high volume manufacturing setting. Using an infrared (IR) dryer, it was determined that conductive copper prints could be dried in seconds or minutes as opposed to tens of minutes or hours that it would take with other drying devices, such as a vacuum oven. In addition, this study also identifies significant parameters that can affect the conductivity of IR dried prints. Using designed experiments and statistical analysis; the dryer parameters were optimized to produce the best conductivity performance for a specific ink formulation and substrate combination. It was determined that for an ethylene glycol, butanol, 1-methoxy 2- propanol ink formulation printed on Kapton, the optimal drying parameters consisted of a dryer height of 4 inches, a temperature setting between 190 - 200°C, and a dry time of 50-65 seconds depending on the printed film thickness as determined by the number of print passes. It is important to note that these parameters are optimized specifically for the ink formulation and substrate used in this study. There is still much research that needs to be done into optimizing the IR dryer for different ink substrate combinations, as well as developing a

  5. Structure-function investigations of bacterial photosynthetic reaction centers.

    Leonova, M M; Fufina, T Yu; Vasilieva, L G; Shuvalov, V A


    During photosynthesis light energy is converted into energy of chemical bonds through a series of electron and proton transfer reactions. Over the first ultrafast steps of photosynthesis that take place in the reaction center (RC) the quantum efficiency of the light energy transduction is nearly 100%. Compared to the plant and cyanobacterial photosystems, bacterial RCs are well studied and have relatively simple structure. Therefore they represent a useful model system both for manipulating of the electron transfer parameters to study detailed mechanisms of its separate steps as well as to investigate the common principles of the photosynthetic RC structure, function, and evolution. This review is focused on the research papers devoted to chemical and genetic modifications of the RCs of purple bacteria in order to study principles and mechanisms of their functioning. Investigations of the last two decades show that the maximal rates of the electron transfer reactions in the RC depend on a number of parameters. Chemical structure of the cofactors, distances between them, their relative orientation, and interactions to each other are of great importance for this process. By means of genetic and spectral methods, it was demonstrated that RC protein is also an essential factor affecting the efficiency of the photochemical charge separation. Finally, some of conservative water molecules found in RC not only contribute to stability of the protein structure, but are directly involved in the functioning of the complex.

  6. The coupling of ω-transaminase and Oppenauer oxidation reactions via intra-membrane multicomponent diffusion – A process model for the synthesis of chiral amines

    Esparza-Isunza, T.; González-Brambila, M.; Gani, Rafiqul


    In this study we consider the theoretical coupling of an otherwise thermodynamically limited ω-transaminase reaction to an Oppenauer oxidation, in order to shift the equilibria of both reactions, with the aim of achieving a significant (and important) increase in the yield of the desired chiral a...... a significant increase in the yield of the chiral amine product may be obtained. Finally, the role of the different parameters involved in the process model has been analyzed....

  7. Elucidating thermodynamic parameters for electron transfer proteins using isothermal titration calorimetry: application to the nitrogenase Fe protein.

    Sørlie, Morten; Chan, Jeannine M; Wang, Haijang; Seefeldt, Lance C; Parker, Vernon D


    Establishing thermodynamic parameters for electron transfer reactions involving redox proteins is essential for a complete description of these important reactions. While various methods have been developed for measuring the Gibbs free energy change (Delta G(HR) or E(m)) for the protein half-reactions, deconvolution of the respective contributions of enthalpy (Delta H(HR)) and entropy (Delta S(HR)) changes is much more challenging. In the present work, an approach is developed using isothermal titration calorimetry (ITC) that allows accurate determination of all of these thermodynamic parameters for protein electron transfer half-reactions. The approach was validated for essentially irreversible and reversible electron transfer reactions between well-characterized mediators and between mediators and the protein cytochrome c. In all cases, the measured thermodynamic parameters were in excellent agreement with parameters determined by electrochemical methods. Finally, the calorimetry approach was used to determine thermodynamic parameters for electron transfer reactions of the nitrogenase Fe protein [4Fe-4S](2+/+) couple in the absence or presence of MgADP or MgATP. The E(m) value was found to change from -290 mV in the absence of nucleotides to -381 mV with MgATP and -423 mV with MgADP, consistent with earlier values. For the first time, the enthalpy (Delta H(HR)) and entropy (Delta S(HR)) contributions for each case were established, revealing shifts in the contribution of each thermodynamic parameter induced by nucleotide binding. The results are discussed in the context of current models for electron transfer in nitrogenase.

  8. A unified diabatic description for electron transfer reactions, isomerization reactions, proton transfer reactions, and aromaticity.

    Reimers, Jeffrey R; McKemmish, Laura K; McKenzie, Ross H; Hush, Noel S


    While diabatic approaches are ubiquitous for the understanding of electron-transfer reactions and have been mooted as being of general relevance, alternate applications have not been able to unify the same wide range of observed spectroscopic and kinetic properties. The cause of this is identified as the fundamentally different orbital configurations involved: charge-transfer phenomena involve typically either 1 or 3 electrons in two orbitals whereas most reactions are typically closed shell. As a result, two vibrationally coupled electronic states depict charge-transfer scenarios whereas three coupled states arise for closed-shell reactions of non-degenerate molecules and seven states for the reactions implicated in the aromaticity of benzene. Previous diabatic treatments of closed-shell processes have considered only two arbitrarily chosen states as being critical, mapping these states to those for electron transfer. We show that such effective two-state diabatic models are feasible but involve renormalized electronic coupling and vibrational coupling parameters, with this renormalization being property dependent. With this caveat, diabatic models are shown to provide excellent descriptions of the spectroscopy and kinetics of the ammonia inversion reaction, proton transfer in N2H7(+), and aromaticity in benzene. This allows for the development of a single simple theory that can semi-quantitatively describe all of these chemical phenomena, as well as of course electron-transfer reactions. It forms a basis for understanding many technologically relevant aspects of chemical reactions, condensed-matter physics, chemical quantum entanglement, nanotechnology, and natural or artificial solar energy capture and conversion.

  9. Hecke algebras with unequal parameters

    Lusztig, G


    Hecke algebras arise in representation theory as endomorphism algebras of induced representations. One of the most important classes of Hecke algebras is related to representations of reductive algebraic groups over p-adic or finite fields. In 1979, in the simplest (equal parameter) case of such Hecke algebras, Kazhdan and Lusztig discovered a particular basis (the KL-basis) in a Hecke algebra, which is very important in studying relations between representation theory and geometry of the corresponding flag varieties. It turned out that the elements of the KL-basis also possess very interesting combinatorial properties. In the present book, the author extends the theory of the KL-basis to a more general class of Hecke algebras, the so-called algebras with unequal parameters. In particular, he formulates conjectures describing the properties of Hecke algebras with unequal parameters and presents examples verifying these conjectures in particular cases. Written in the author's precise style, the book gives rese...

  10. Nuclear reactions in astrophysics

    Arnould, M.; Rayet, M. (Universite Libre de Bruxelles (BE))


    At all times and at all astrophysical scales, nuclear reactions have played and continue to play a key role. This concerns the energetics as well as the production of nuclides (nucleosynthesis). After a brief review of the observed composition of various objects in the universe, and especially of the solar system, the basic ingredients that are required in order to build up models for the chemical evolution of galaxies are sketched. Special attention is paid to the evaluation of the stellar yields through an overview of the important burning episodes and nucleosynthetic processes that can develop in non-exploding or exploding stars. Emphasis is put on the remaining astrophysical and nuclear physics uncertainties that hamper a clear understanding of the observed characteristics, and especially compositions, of a large variety of astrophysical objects.

  11. On Markov parameters in system identification

    Phan, Minh; Juang, Jer-Nan; Longman, Richard W.


    A detailed discussion of Markov parameters in system identification is given. Different forms of input-output representation of linear discrete-time systems are reviewed and discussed. Interpretation of sampled response data as Markov parameters is presented. Relations between the state-space model and particular linear difference models via the Markov parameters are formulated. A generalization of Markov parameters to observer and Kalman filter Markov parameters for system identification is explained. These extended Markov parameters play an important role in providing not only a state-space realization, but also an observer/Kalman filter for the system of interest.

  12. Redefining solubility parameters: the partial solvation parameters.

    Panayiotou, Costas


    The present work reconsiders a classical and universally accepted concept of physical chemistry, the solubility parameter. Based on the insight derived from modern quantum chemical calculations, a new definition of solubility parameter is proposed, which overcomes some of the inherent restrictions of the original definition and expands its range of applications. The original single solubility parameter is replaced by four partial solvation parameters reflecting the dispersion, the polar, the acidic and the basic character of the chemical compounds as expressed either in their pure state or in mixtures. Simple rules are adopted for the definition and calculation of these four parameters and their values are tabulated for a variety of common substances. In contrast, however, to the well known Hansen solubility parameters, their design and evaluation does not rely exclusively on the basic rule of "similarity matching" for solubility but it makes also use of the other basic rule of compatibility, namely, the rule of "complementarity matching". This complementarity matching becomes particularly operational with the sound definition of the acidic and basic components of the solvation parameter based on the third σ-moments of the screening charge distributions of the quantum mechanics-based COSMO-RS theory. The new definitions are made in a simple and straightforward manner, thus, preserving the strength and appeal of solubility parameter stemming from its simplicity. The new predictive method has been applied to a variety of solubility data for systems of pharmaceuticals and polymers. The results from quantum mechanics calculations are critically compared with the results from Abraham's acid/base descriptors.

  13. Thermodynamics of random reaction networks.

    Jakob Fischer

    Full Text Available Reaction networks are useful for analyzing reaction systems occurring in chemistry, systems biology, or Earth system science. Despite the importance of thermodynamic disequilibrium for many of those systems, the general thermodynamic properties of reaction networks are poorly understood. To circumvent the problem of sparse thermodynamic data, we generate artificial reaction networks and investigate their non-equilibrium steady state for various boundary fluxes. We generate linear and nonlinear networks using four different complex network models (Erdős-Rényi, Barabási-Albert, Watts-Strogatz, Pan-Sinha and compare their topological properties with real reaction networks. For similar boundary conditions the steady state flow through the linear networks is about one order of magnitude higher than the flow through comparable nonlinear networks. In all networks, the flow decreases with the distance between the inflow and outflow boundary species, with Watts-Strogatz networks showing a significantly smaller slope compared to the three other network types. The distribution of entropy production of the individual reactions inside the network follows a power law in the intermediate region with an exponent of circa -1.5 for linear and -1.66 for nonlinear networks. An elevated entropy production rate is found in reactions associated with weakly connected species. This effect is stronger in nonlinear networks than in the linear ones. Increasing the flow through the nonlinear networks also increases the number of cycles and leads to a narrower distribution of chemical potentials. We conclude that the relation between distribution of dissipation, network topology and strength of disequilibrium is nontrivial and can be studied systematically by artificial reaction networks.

  14. Surface reactions in microelectronics process technology.

    Levitin, Galit; Hess, Dennis W


    Current integrated circuit (IC) manufacturing consists of more than 800 process steps, nearly all of which involve reactions at surfaces that significantly impact device yield and performance. From initial surface preparation through film deposition, patterning, etching, residue removal, and metallization, an understanding of surface reactions and interactions is critical to the successful continuous scaling, yield, and reliability of electronic devices. In this review, some of the most important surface reactions that drive the development of microelectronic device fabrication are described. The reactions discussed do not constitute comprehensive coverage of this topic in IC manufacture but have been selected to demonstrate the importance of surface/interface reactions and interactions in the development of new materials, processing sequences, and process integration challenges. Specifically, the review focuses on surface reactions related to surface cleaning/preparation, semiconductor film growth, dielectric film growth, metallization, and etching (dry and wet).

  15. Computed potential energy surfaces for chemical reactions

    Walch, Stephen P.


    Quantum mechanical methods have been used to compute potential energy surfaces for chemical reactions. The reactions studied were among those believed to be important to the NASP and HSR programs and included the recombination of two H atoms with several different third bodies; the reactions in the thermal Zeldovich mechanism; the reactions of H atom with O2, N2, and NO; reactions involved in the thermal De-NO(x) process; and the reaction of CH(squared Pi) with N2 (leading to 'prompt NO'). These potential energy surfaces have been used to compute reaction rate constants and rates of unimolecular decomposition. An additional application was the calculation of transport properties of gases using a semiclassical approximation (and in the case of interactions involving hydrogen inclusion of quantum mechanical effects).

  16. Voltage stability, bifurcation parameters and continuation methods

    Alvarado, F.L. [Wisconsin Univ., Madison, WI (United States)


    This paper considers the importance of the choice of bifurcation parameter in the determination of the voltage stability limit and the maximum power load ability of a system. When the bifurcation parameter is power demand, the two limits are equivalent. However, when other types of load models and bifurcation parameters are considered, the two concepts differ. The continuation method is considered as a method for determination of voltage stability margins. Three variants of the continuation method are described: the continuation parameter is the bifurcation parameter the continuation parameter is initially the bifurcation parameter, but is free to change, and the continuation parameter is a new `arc length` parameter. Implementations of voltage stability software using continuation methods are described. (author) 23 refs., 9 figs.

  17. ReactionPredictor: prediction of complex chemical reactions at the mechanistic level using machine learning.

    Kayala, Matthew A; Baldi, Pierre


    Proposing reasonable mechanisms and predicting the course of chemical reactions is important to the practice of organic chemistry. Approaches to reaction prediction have historically used obfuscating representations and manually encoded patterns or rules. Here we present ReactionPredictor, a machine learning approach to reaction prediction that models elementary, mechanistic reactions as interactions between approximate molecular orbitals (MOs). A training data set of productive reactions known to occur at reasonable rates and yields and verified by inclusion in the literature or textbooks is derived from an existing rule-based system and expanded upon with manual curation from graduate level textbooks. Using this training data set of complex polar, hypervalent, radical, and pericyclic reactions, a two-stage machine learning prediction framework is trained and validated. In the first stage, filtering models trained at the level of individual MOs are used to reduce the space of possible reactions to consider. In the second stage, ranking models over the filtered space of possible reactions are used to order the reactions such that the productive reactions are the top ranked. The resulting model, ReactionPredictor, perfectly ranks polar reactions 78.1% of the time and recovers all productive reactions 95.7% of the time when allowing for small numbers of errors. Pericyclic and radical reactions are perfectly ranked 85.8% and 77.0% of the time, respectively, rising to >93% recovery for both reaction types with a small number of allowed errors. Decisions about which of the polar, pericyclic, or radical reaction type ranking models to use can be made with >99% accuracy. Finally, for multistep reaction pathways, we implement the first mechanistic pathway predictor using constrained tree-search to discover a set of reasonable mechanistic steps from given reactants to given products. Webserver implementations of both the single step and pathway versions of Reaction

  18. NIF Gamma Reaction History

    Herrmann, H. W.; Kim, Y.; Young, C. S.; Mack, J. M.; McEvoy, A. M.; Hoffman, N. M.; Wilson, D. C.; Langenbrunner, J. R.; Evans, S.; Batha, S. H.; Stoeffl, W.; Lee, A.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Malone, R. M.; Kaufman, M. I.


    The primary objective of the NIF Gamma Reaction History (GRH) diagnostics is to provide bang time and burn width information based upon measurement of fusion gamma-rays. This is accomplished with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. In addition, the GRH detectors can perform γ-ray spectroscopy to explore other nuclear processes from which additional significant implosion parameters may be inferred (e.g., plastic ablator areal density). Implementation is occurring in 2 phases: 1) four PMT-based channels mounted to the outside of the NIF target chamber at ˜6 m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and 2) several channels located just inside the target bay shield wall at ˜15 m from TCC (GRH-15m) with optical paths leading through the wall into well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. This suite of diagnostics will allow exploration of interesting γ-ray physics well beyond the ignition campaign. Recent data from OMEGA and NIF will be shown.

  19. Double Pion Production Reactions

    Oset, E; Cano, F; Hernández, E; Kamalov, S S; Nacher, J C; Tejedor, J A G


    We report on reactions producing two pions induced by real and virtual photons or nucleons. The role of different resonances in these reactions is emphasized. Novel results on coherent two pion photoproduction in nuclei are also reported.

  20. Microfluidic chemical reaction circuits

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine


    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  1. Microscale Thermite Reactions.

    Arnaiz, Francisco J.; Aguado, Rafael; Arnaiz, Susana


    Describes the adaptation of thermite (aluminum with metal oxides) reactions from whole-class demonstrations to student-run micro-reactions. Lists detailed directions and possible variations of the experiment. (WRM)

  2. Back Reaction of Cosmological Perturbations

    Brandenberger, R H


    The presence of cosmological perturbations affects the background metric and matter configuration in which the perturbations propagate. This effect, studied a long time ago for gravitational waves, also is operational for scalar gravitational fluctuations, inhomogeneities which are believed to be more important in inflationary cosmology. The back-reaction of fluctuations can be described by an effective energy-momentum tensor. The issue of coordinate invariance makes the analysis more complicated for scalar fluctuations than for gravitational waves. We show that the back-reaction of fluctuations can be described in a diffeomorphism-invariant way. In an inflationary cosmology, the back-reaction is dominated by infrared modes. We show that these modes give a contribution to the effective energy-momentum tensor of the form of a negative cosmological constant whose absolute value grows in time. We speculate that this may lead to a self-regulating dynamical relaxation mechanism for the cosmological constant. This ...

  3. Light in elementary biological reactions

    Sundström, Villy


    Light plays an important role in biology. In this review we discuss several processes and systems where light triggers a biological response, i.e. photosynthesis, vision, photoreceptors. For these functions Nature has chosen simple elementary chemical reactions, which occur in highly specialized and organized structures. The high efficiency and specificity of these reactions make them interesting for applications in light energy conversion and opto-electronics. In order to emphasize the synergism in studies of natural and synthetic systems we will discuss a few of each kind, with similar functions. In all cases light triggers a rapid sequence of events, which makes ultrafast spectroscopy an ideal tool to disentangle reaction mechanisms and dynamics.

  4. Chemical transport reactions

    Schäfer, Harald


    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  5. Solvent effect in the Walden inversion reactions

    Jaume, J.; Lluch, J. M.; Oliva, A.; Bertrán, J.


    The solvent effect on the fluoride exchange reaction has been studied by means of ab initio calculations using the 3-21G basis set. It is shown that the motion of the solvent molecules is an important part of the reaction coordinate.

  6. Ambulatory Measurement of Ground Reaction Forces

    Veltink, Petrus H.; Liedtke, C.B.; Droog, Adriaan


    The measurement of ground reaction forces is important in the biomechanical analysis of gait and other motor activities. It is the purpose of this study to show the feasibility of ambulatory measurement of ground reaction forces using two six degrees of freedom sensors mounted under the shoe. One

  7. Reaction systems with precipitation

    Marek Rogalski


    Full Text Available This article proposes expanding Reaction Systems of Ehrenfeucht and Rozenberg by incorporating precipitation reactions into it. This improves the computing power of Reaction Systems by allowing us to implement a stack. This addition enables us to implement a Deterministic Pushdown Automaton.




    Full Text Available This study aims at analysing effects of intermediate goods, capital goods and consumer goods on both import and export, and at determining the subsector led to deficits of balance of payments. To achieve this, various statistical techniques have been applied. To carry out the present study, data reported by the Central Bank of Turkey were used in the time period of 2000–2013.These results revealed that the economic factors (intermediate, capital, consumer goods are significantly effective on the deficits of balance of payments. The analysis also showed that the corresponding imported goods are effective parameters onboth import and export. Contrary to common expectation, it is concluded that the deficits of balance of payments in the external trade of Turkey stem from the imports of the consumer goods. This study reveals that the policies should be created to encourage the decreasing of the items caused the deficits. It is important to note that our findings are usually in agreement with the literature. Possibility of countries’ involvement into economic crises can be determined before the crises take place and the countries will be therefore warned according to the results obtained. All graphical and statistical results here have been produced by the authors through EViews 7.1.

  9. Reaction-Diffusion in the NEURON Simulator

    Robert A. McDougal


    Full Text Available In order to support research on the role of cell biological principles (genomics, proteomics, signaling cascades and reaction dynamics on the dynamics of neuronal response in health and disease, NEURON has developed a Reaction-Diffusion (rxd module in Python which provides specification and simulation for these dynamics, coupled with the electrophysiological dynamics of the cell membrane. Arithmetic operations on species and parameters are overloaded, allowing arbitrary reaction formulas to be specified using Python syntax. These expressions are then transparently compiled into bytecode that uses NumPy for fast vectorized calculations. At each time step, rxd combines NEURON's integrators with SciPy’s sparse linear algebra library.

  10. Reaction-diffusion in the NEURON simulator.

    McDougal, Robert A; Hines, Michael L; Lytton, William W


    In order to support research on the role of cell biological principles (genomics, proteomics, signaling cascades and reaction dynamics) on the dynamics of neuronal response in health and disease, NEURON's Reaction-Diffusion (rxd) module in Python provides specification and simulation for these dynamics, coupled with the electrophysiological dynamics of the cell membrane. Arithmetic operations on species and parameters are overloaded, allowing arbitrary reaction formulas to be specified using Python syntax. These expressions are then transparently compiled into bytecode that uses NumPy for fast vectorized calculations. At each time step, rxd combines NEURON's integrators with SciPy's sparse linear algebra library.

  11. Selecting water-alcohol mixed solvent for synthesis of polydopamine nano-spheres using solubility parameter

    Jiang, Xiaoli; Wang, Yinling; Li, Maoguo


    The solvent plays an important role in a given chemical reaction. Since most reaction in nature occur in the mixed-solvent systems, a comprehensive principle for solvent optimization was required. By calculating the Hansen solubility parameters (HSP) distance Ra, we designed a model experiment to explore the influence of mixed solvents on the chemical synthesis. The synthesis of polydopamine (PDA) in the water-alcohol system was chosen as model. As predicted, the well-dispersed PDA spheres were obtained in selected solvents with smaller Ra values: methanol/water, ethanol/water and 2-propanol/water. In addition, the mixed solvent with smaller Ra values gave a higher conversion of dopamine. The strategy for mixed solvent selection is might be useful to choose optimal reaction media for efficient chemical synthesis.

  12. Selecting water-alcohol mixed solvent for synthesis of polydopamine nano-spheres using solubility parameter

    Jiang, Xiaoli; Wang, Yinling; Li, Maoguo


    The solvent plays an important role in a given chemical reaction. Since most reaction in nature occur in the mixed-solvent systems, a comprehensive principle for solvent optimization was required. By calculating the Hansen solubility parameters (HSP) distance Ra, we designed a model experiment to explore the influence of mixed solvents on the chemical synthesis. The synthesis of polydopamine (PDA) in the water-alcohol system was chosen as model. As predicted, the well-dispersed PDA spheres were obtained in selected solvents with smaller Ra values: methanol/water, ethanol/water and 2-propanol/water. In addition, the mixed solvent with smaller Ravalues gave a higher conversion of dopamine. The strategy for mixed solvent selection is might be useful to choose optimal reaction media for efficient chemical synthesis. PMID:25317902

  13. Visualization of Input Parameters for Stream and Pathline Seeding

    Tony McLoughlin


    Full Text Available Uncertainty arises in all stages of the visualization pipeline. However, the majority of flow visualization applications convey no uncertainty information to the user. In tools where uncertainty is conveyed, the focus is generally on data, such as error that stems from numerical methods used to generate a simulation or on uncertainty associated with mapping visualiza-tion primitives to data. Our work is aimed at another source of uncertainty - that associated with user-controlled input param-eters. The navigation and stability analysis of user-parameters has received increasing attention recently. This work presents an investigation of this topic for flow visualization, specifically for three-dimensional streamline and pathline seeding. From a dynamical systems point of view, seeding can be formulated as a predictability problem based on an initial condition. Small perturbations in the initial value may result in large changes in the streamline in regions of high unpredictability. Analyzing this predictability quantifies the perturbation a trajectory is subjugated to by the flow. In other words, some predictions are less certain than others as a function of initial conditions. We introduce novel techniques to visualize important user input parameters such as streamline and pathline seeding position in both space and time, seeding rake position and orientation, and inter-seed spacing. The implementation is based on a metric which quantifies similarity between stream and pathlines. This is important for Computational Fluid Dynamics (CFD engineers as, even with the variety of seeding strategies available, manual seeding using a rake is ubiquitous. We present methods to quantify and visualize the effects that changes in user-controlled input parameters have on the resulting stream and pathlines. We also present various visualizations to help CFD scientists to intuitively and effectively navigate this parameter space. The reaction from a domain

  14. Key parameters controlling the performance of catalytic motors

    Esplandiu, Maria J.; Afshar Farniya, Ali; Reguera, David


    The development of autonomous micro/nanomotors driven by self-generated chemical gradients is a topic of high interest given their potential impact in medicine and environmental remediation. Although impressive functionalities of these devices have been demonstrated, a detailed understanding of the propulsion mechanism is still lacking. In this work, we perform a comprehensive numerical analysis of the key parameters governing the actuation of bimetallic catalytic micropumps. We show that the fluid motion is driven by self-generated electro-osmosis where the electric field originates by a proton current rather than by a lateral charge asymmetry inside the double layer. Hence, the surface potential and the electric field are the key parameters for setting the pumping strength and directionality. The proton flux that generates the electric field stems from the proton gradient induced by the electrochemical reactions taken place at the pump. Surprisingly the electric field and consequently the fluid flow are mainly controlled by the ionic strength and not by the conductivity of the solution, as one could have expected. We have also analyzed the influence of the chemical fuel concentration, electrochemical reaction rates, and size of the metallic structures for an optimized pump performance. Our findings cast light on the complex chemomechanical actuation of catalytic motors and provide important clues for the search, design, and optimization of novel catalytic actuators.

  15. Determination of the Astrophysical S(E) Factors or Rates for Radiative Capture Reaction with One Nucleon Transfer Reaction%Determination of the Astrophysical S(E) Factors or Rates for Radiative Capture Reaction with One Nucleon Transfer Reaction

    李志宏; 郭冰; 李云居; 苏俊; 李二涛; 白希祥; 王友宝; 曾晟; 王宝祥; 颜胜权; 李志常; 刘建成; 连钢; 金孙均; 刘鑫; 柳卫平


    The radiative capture reaction plays an important role in nuclear astrophysics. We have indirectly measured the astrophysical S(E) factors for some proton capture reactions and reaction rates for several neutron capture reactions with one nucleon transfer reactions at HI-13 tandem accelerator in recent years. Some of them are compiled into IAEA EXFOR database and JINA REACLIB project, and used in the network calculations of Big Bang nucleosynthesis and type-I X-ray bursts.

  16. [Acoustical parameters of toys].

    Harazin, Barbara


    Toys play an important role in the development of the sight and hearing concentration in children. They also support the development of manipulation, gently influence a child and excite its emotional activities. A lot of toys emit various sounds. The aim of the study was to assess sound levels produced by sound-emitting toys used by young children. Acoustical parameters of noise were evaluated for 16 sound-emitting plastic toys in laboratory conditions. The noise level was recorded at four different distances, 10, 20, 25 and 30 cm, from the toy. Measurements of A-weighted sound pressure levels and noise levels in octave band in the frequency range from 31.5 Hz to 16 kHz were performed at each distance. Taking into consideration the highest equivalent A-weighted sound levels produced by tested toys, they can be divided into four groups: below 70 dB (6 toys), from 70 to 74 dB (4 toys), from 75 to 84 dB (3 toys) and from 85 to 94 dB (3 toys). The majority of toys (81%) emitted dominant sound levels in octave band at the frequency range from 2 kHz to 4 kHz. Sound-emitting toys produce the highest acoustic energy at the frequency range of the highest susceptibility of the auditory system. Noise levels produced by some toys can be dangerous to children's hearing.

  17. Phase transitions in a holographic s + p model with back-reaction

    Nie, Zhang-Yu [Kunming University of Science and Technology, Kunming (China); Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China); Shanghai Jiao Tong University, INPAC, Department of Physics, and Shanghai Key Laboratory of Particle Physics and Cosmology, Shanghai (China); Cai, Rong-Gen [Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China); Gao, Xin [Virginia Tech, Department of Physics, Blacksburg, VA (United States); Li, Li [University of Crete, Department of Physics, Crete Center for Theoretical Physics, Heraklion (Greece); Zeng, Hui [Kunming University of Science and Technology, Kunming (China); Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China)


    In a previous paper (Nie et al. in JHEP 1311:087, arXiv:1309.2204 [hep-th], 2013), we presented a holographic s + p superconductor model with a scalar triplet charged under an SU(2) gauge field in the bulk. We also study the competition and coexistence of the s-wave and p-wave orders in the probe limit. In this work we continue to study the model by considering the full back-reaction. The model shows a rich phase structure and various condensate behaviors such as the ''n-type'' and ''u-type'' ones, which are also known as reentrant phase transitions in condensed matter physics. The phase transitions to the p-wave phase or s + p coexisting phase become first order in strong back-reaction cases. In these first order phase transitions, the free energy curve always forms a swallow tail shape, in which the unstable s + p solution can also play an important role. The phase diagrams of this model are given in terms of the dimension of the scalar order and the temperature in the cases of eight different values of the back-reaction parameter, which show that the region for the s + p coexisting phase is enlarged with a small or medium back-reaction parameter but is reduced in the strong back-reaction cases. (orig.)

  18. The Pozzolanic reaction of silica fume

    Jensen, Ole Mejlhede


    Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the ...... of activation of the pozzolanic reaction of silica fume is estimated. The results show that the pozzolanic reaction of silica fume has notable differences from Portland cement hydration.......Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone....... In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy...

  19. Anaphylactic reaction to intravenous diclofenac

    Ranju Singh


    Full Text Available Diclofenac sodium is a non-steroidal anti-inflammatory drug widely used as an opioid sparing agent for postoperative analgesia. Anaphylaxis due to intravenous diclofenac sodium is very rare. We report a case of anaphylactic reaction to IV diclofenac sodium, occurring postoperatively in a 25-year-old primigravida, the clinical features of which mimicked pulmonary embolism. The rarity, clinical importance and the diagnostic dilemma associated prompted us to report this case.

  20. Estimating Cosmological Parameter Covariance

    Taylor, Andy


    We investigate the bias and error in estimates of the cosmological parameter covariance matrix, due to sampling or modelling the data covariance matrix, for likelihood width and peak scatter estimators. We show that these estimators do not coincide unless the data covariance is exactly known. For sampled data covariances, with Gaussian distributed data and parameters, the parameter covariance matrix estimated from the width of the likelihood has a Wishart distribution, from which we derive the mean and covariance. This mean is biased and we propose an unbiased estimator of the parameter covariance matrix. Comparing our analytic results to a numerical Wishart sampler of the data covariance matrix we find excellent agreement. An accurate ansatz for the mean parameter covariance for the peak scatter estimator is found, and we fit its covariance to our numerical analysis. The mean is again biased and we propose an unbiased estimator for the peak parameter covariance. For sampled data covariances the width estimat...

  1. Emergy and Its Importance

    Emergy is an important quantity needed for public policy analysis that is based on a complex methodology. The intent of this Environmental Research Brief is to define emergy and its importance in a manner that is accessible to everyone with at least a high school education. Emer...

  2. Thermokinetics of the Formation Reaction of Zinc Histidine Complex

    GAO,Sheng-Li(高胜利); CHEN,San-Ping(陈三平); HU,Rong-Zu(胡荣祖); SHI,Qi-Zhen(史启祯)


    The enthalpy change of reaction of zinc chloride with L-α-histidine in the temperature range of 25-50 ℃ has been determined by a microcalorimeter. On the basis of experimental and calculated results, three thermodynamics parameters (the activation enthalpy, the activation entropy, the activation free energy), the rate constant and three kinetic parameters (the activation energy, the pre-exponential constant and the reaction order) of the reaction, and the standard enthalpy of formarion of Zn(His)2+ (aq.) are obtained. The results showed that the title reaction easily took place at the studied temperature.

  3. Selectivity in the carbon-oxygen reaction

    Skokova, Kristina A.

    The dependence of the carbon-oxygen reaction rate and the CO/COsb2 ratio on temperature, oxygen pressure, carbon crystallite size, concentration of surface C(O) complexes, and content of heteroatoms was studied. It was shown that the temperature dependence of the CO/COsb2 ratio obeys an Arrhenius-type relationship, but the pre-exponential factor and the activation energy depend on oxygen pressure and carbon nature. The Arrhenius parameters were found to be directly proportional to each other. This confirmed the importance of the compensation effect in carbon oxidation. It was explained by active site heterogeneity in carbon materials. For all experimental conditions, the CO/COsb2 ratio was lower for carbons with more ordered graphitic structure. It was shown that the CO/COsb2 ratio is inversely proportional to the surface coverage with reactive C(O) complexes. More ordered carbons were revealed to possess lower concentrations of stable complexes, higher surface coverages with reactive complexes and thus lower CO/COsb2 ratios. The influence of B and N heteroatoms on carbon reactivity and the CO/COsb2 ratio was studied. It was confirmed that B acts as an inhibitor of carbon oxidation due to the formation of a protective Bsb2Osb3 coating. The N presence in the carbon structure increases its rate of oxidation, maybe due to decreasing carbon crystallite dimensions. The CO/COsb2 ratio did not correlate with the N content in the carbon, but depended on the concentration of surface carbon-oxygen complexes. A new reaction mechanism is proposed. A key feature of the mechanism is that it takes into account the presence and mobility of oxygen atoms on the basal plane. It was shown with the aid of theoretical molecular orbital calculations that chemisorption on a pair of adjacent edge and basal sites is thermodynamically favorable as a parallel process to the generally accepted path of chemisorption on two edge carbon atoms. The former process can lead to the formation of a

  4. Understanding bibliometric parameters and analysis.

    Choudhri, Asim F; Siddiqui, Adeel; Khan, Nickalus R; Cohen, Harris L


    Bibliometric parameters have become an important part of modern assessment of academic productivity. These parameters exist for the purpose of evaluating authors (publication count, citation count, h-index, m-quotient, hc-index, e-index, g-index, i-10 [i-n] index) and journals (impact factor, Eigenfactor, article influence score, SCImago journal rank, source-normalized impact per paper). Although in recent years there has been a proliferation of bibliometric parameters, the true meaning and appropriate use of these parameters is generally not well understood. Effective use of existing and emerging bibliometric tools can aid in assessment of academic productivity, including readiness for promotions and other awards. However, if not properly understood, the data can be misinterpreted and may be subject to manipulation. Familiarity with bibliometric parameters will aid in their effective implementation in the review of authors-whether individuals or groups-and journals, as well as their possible use in the promotions review process, maximizing the effectiveness of bibliometric analysis.

  5. Mode choice model parameters estimation

    Strnad, Irena


    The present work focuses on parameter estimation of two mode choice models: multinomial logit and EVA 2 model, where four different modes and five different trip purposes are taken into account. Mode choice model discusses the behavioral aspect of mode choice making and enables its application to a traffic model. Mode choice model includes mode choice affecting trip factors by using each mode and their relative importance to choice made. When trip factor values are known, it...

  6. Noncanonical Reactions of Flavoenzymes

    Pablo Sobrado


    Full Text Available Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetonephosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base reactions or as a nucleophile or electrophile. In addition, the flavin cofactor is proposed to function as a “molecular scaffold” in the formation of UDP-galactofuranose and alkyl-dihydroxyacetonephosphate by forming a covalent adduct with reaction intermediates.

  7. Predicting CYP2C19 catalytic parameters for enantioselective oxidations using artificial neural networks and a chirality code.

    Hartman, Jessica H; Cothren, Steven D; Park, Sun-Ha; Yun, Chul-Ho; Darsey, Jerry A; Miller, Grover P


    Cytochromes P450 (CYP for isoforms) play a central role in biological processes especially metabolism of chiral molecules; thus, development of computational methods to predict parameters for chiral reactions is important for advancing this field. In this study, we identified the most optimal artificial neural networks using conformation-independent chirality codes to predict CYP2C19 catalytic parameters for enantioselective reactions. Optimization of the neural networks required identifying the most suitable representation of structure among a diverse array of training substrates, normalizing distribution of the corresponding catalytic parameters (k(cat), K(m), and k(cat)/K(m)), and determining the best topology for networks to make predictions. Among different structural descriptors, the use of partial atomic charges according to the CHelpG scheme and inclusion of hydrogens yielded the most optimal artificial neural networks. Their training also required resolution of poorly distributed output catalytic parameters using a Box-Cox transformation. End point leave-one-out cross correlations of the best neural networks revealed that predictions for individual catalytic parameters (k(cat) and K(m)) were more consistent with experimental values than those for catalytic efficiency (k(cat)/K(m)). Lastly, neural networks predicted correctly enantioselectivity and comparable catalytic parameters measured in this study for previously uncharacterized CYP2C19 substrates, R- and S-propranolol. Taken together, these seminal computational studies for CYP2C19 are the first to predict all catalytic parameters for enantioselective reactions using artificial neural networks and thus provide a foundation for expanding the prediction of cytochrome P450 reactions to chiral drugs, pollutants, and other biologically active compounds.

  8. Predicting CYP2C19 Catalytic Parameters for Enantioselective Oxidations Using Artificial Neural Networks and a Chirality Code

    Hartman, Jessica H.; Cothren, Steven D.; Park, Sun-Ha; Yun, Chul-Ho; Darsey, Jerry A.; Miller, Grover P.


    Cytochromes P450 (CYP for isoforms) play a central role in biological processes especially metabolism of chiral molecules; thus, development of computational methods to predict parameters for chiral reactions is important for advancing this field. In this study, we identified the most optimal artificial neural networks using conformation-independent chirality codes to predict CYP2C19 catalytic parameters for enantioselective reactions. Optimization of the neural networks required identifying the most suitable representation of structure among a diverse array of training substrates, normalizing distribution of the corresponding catalytic parameters (kcat, Km, and kcat/Km), and determining the best topology for networks to make predictions. Among different structural descriptors, the use of partial atomic charges according to the CHelpG scheme and inclusion of hydrogens yielded the most optimal artificial neural networks. Their training also required resolution of poorly distributed output catalytic parameters using a Box-Cox transformation. End point leave-one-out cross correlations of the best neural networks revealed that predictions for individual catalytic parameters (kcat and Km) were more consistent with experimental values than those for catalytic efficiency (kcat/Km). Lastly, neural networks predicted correctly enantioselectivity and comparable catalytic parameters measured in this study for previously uncharacterized CYP2C19 substrates, R- and S-propranolol. Taken together, these seminal computational studies for CYP2C19 are the first to predict all catalytic parameters for enantioselective reactions using artificial neural networks and thus provide a foundation for expanding the prediction of cytochrome P450 reactions to chiral drugs, pollutants, and other biologically active compounds. PMID:23673224

  9. Pure Gravitational Back-Reaction Observables

    Tsamis, N C


    After discussing the various issues regarding and requirements on pure quantum gravitational observables in homogeneous-isotropic conditions, we construct a composite operator observable satisfying most of them. We also expand it to first order in the loop counting parameter and suggest it as a physical quantifier of gravitational back-reaction in an initially inflating cosmology.

  10. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.


    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl tereph

  11. Transfusion reaction - hemolytic

    ... of allergic transfusion reactions that do not cause hemolysis. ... transfusion, the transfusion must be stopped right away. Blood samples from the recipient (person getting the transfusion) and ...

  12. Desosamine in multicomponent reactions

    Achatz, Sepp; Dömling, Alexander


    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  13. Metal-mullite reactions

    Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)


    Mullite was reacted with pure Al and with Ti or Zr dissolved in Ag-Cu eutectic alloys at 1100 C in Ar. Analysis of the Ti and Zr-containing specimens showed reaction zones with compositions of Ti{sub 50}Cu{sub 3O}O{sub 20} and ZrO{sub 2}, respectively. The Al-mullite specimen showed much more extensive penetration into the ceramic and a more diffuse reaction zone than the other two systems. Al{sub 2}O{sub 3} and Si were the main reaction products for Al-mullite reaction.

  14. Reactions at Solid Surfaces

    Ertl, Gerhard


    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  15. Desosamine in multicomponent reactions

    Achatz, Sepp; Dömling, Alexander


    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  16. Roughness parameter selection for novel manufacturing processes.

    Ham, M; Powers, B M


    This work proposes a method of roughness parameter (RP) selection for novel manufacturing processes or processes where little knowledge exists about which RPs are important. The method selects a single parameter to represent a group of highly correlated parameters. Single point incremental forming (SPIF) is used as the case study for the manufacturing process. This methodology was successful in reducing the number of RPs investigated from 18 to 8 in the case study. © Wiley Periodicals, Inc.

  17. Lumped-parameter models

    Ibsen, Lars Bo; Liingaard, Morten

    A lumped-parameter model represents the frequency dependent soil-structure interaction of a massless foundation placed on or embedded into an unbounded soil domain. The lumped-parameter model development have been reported by (Wolf 1991b; Wolf 1991a; Wolf and Paronesso 1991; Wolf and Paronesso 19...

  18. Sample controlled reaction temperature (SCRT): Controlling the phase composition of silicon nitride obtained by carbothermal reduction

    Alcala, M.D.; Criado, J.M.; Real, C. [Instituto de Ciencia de Materiales de Sevilla, c/Americo Vespucio s/n; Isla de La Cartuja, 41092 Sevilla (Spain)


    Carbothermal reduction of silica is one of the most common methods of producing Si{sub 3}N{sub 4} powders. The experimental conditions have an important influence on the structure of the final product, especially the balance of {alpha}- to {beta}- Si{sub 3}N{sub 4}. The Sample Controlled Reaction Temperature method describes here has permitted to conclude that the phase composition of the silicon nitride is governed by the partial pressure of CO in the close vicinity of the sample. Moreover, the control of this parameter has an important influence on particle size and morphology of the final product. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  19. DNA Import into Mitochondria.

    Konstantinov, Yu M; Dietrich, A; Weber-Lotfi, F; Ibrahim, N; Klimenko, E S; Tarasenko, V I; Bolotova, T A; Koulintchenko, M V


    In recent decades, it has become evident that the condition for normal functioning of mitochondria in higher eukaryotes is the presence of membrane transport systems of macromolecules (proteins and nucleic acids). Natural competence of the mitochondria in plants, animals, and yeasts to actively uptake DNA may be directly related to horizontal gene transfer into these organelles occurring at much higher rate compared to the nuclear and chloroplast genomes. However, in contrast with import of proteins and tRNAs, little is known about the biological role and molecular mechanism underlying import of DNA into eukaryotic mitochondria. In this review, we discuss current state of investigations in this area, particularly specificity of DNA import into mitochondria and its features in plants, animals, and yeasts; a tentative mechanism of DNA import across the mitochondrial outer and inner membranes; experimental data evidencing several existing, but not yet fully understood mechanisms of DNA transfer into mitochondria. Currently available data regarding transport of informational macromolecules (DNA, RNA, and proteins) into the mitochondria do not rule out that the mechanism of protein and tRNA import as well as tRNA and DNA import into the mitochondria may partially overlap.


    Ayşegül Akdoğan Eker


    Full Text Available Nanotechnology concept which has added a new dimension to our lives in recent years, is finding a place in every sector day by day. The combined effect of nanotechnology is almost equal to the industrial revolution of last 200 years and have is able to fill all developments in a few years. However this development should be taken under control. Otherwise unstoppable new structures will not ease life but will be a problem for humanity. For this purpose, the main parameters (from the start up stage of nano-technologic applications to the obtained product should be checked. These parameters are actually not different than the adaptation of the classical quality indicators for nanotechnology applications. Especially it plays an important role in obtaining a uniform distribution and regarding the features of the end product in nano-technological ceramic and etc. applications. The most important problem faced in particles of that size is the accumulation they create. Another problem is the increasing friction force as size gets smaller. The friction force of asubstance increases proportionally with the cube of its surface area. Another problem is surface tension. The increasing surface tension due to increasing surface area will cause the particles to attract and stick to each other. The structures aimed to be obtained are mostly complex and especially in upwards approach, it is thermodynamically very hard for the atoms to get into that order. Therefore in this announcement, we stated the quality parameters that will be taken into consideration in nano-technological applications and the methods for obtaining those parameters. The aim is to explain these parameters with all dimensions so that they will lead the way to the future nano-technological applications.

  1. Impact parameter dependence of collective flow and its disappearance for different mass asymmetries

    Goyal, Supriya


    We study the role of impact parameter on the collective flow and its disappearance for different mass asymmetric reactions. The mass asymmetry is varied from 0 to 0.7 keeping the total mass of the system fixed. Our results clearly indicate a significant role of impact parameter on the collective flow and its disappearance for the mass asymmetric reactions. The impact parameter dependence is also found to vary with mass asymmetry of the reaction.

  2. Cosmological parameter estimation using Particle Swarm Optimization

    Prasad, J.; Souradeep, T.


    Constraining parameters of a theoretical model from observational data is an important exercise in cosmology. There are many theoretically motivated models, which demand greater number of cosmological parameters than the standard model of cosmology uses, and make the problem of parameter estimation challenging. It is a common practice to employ Bayesian formalism for parameter estimation for which, in general, likelihood surface is probed. For the standard cosmological model with six parameters, likelihood surface is quite smooth and does not have local maxima, and sampling based methods like Markov Chain Monte Carlo (MCMC) method are quite successful. However, when there are a large number of parameters or the likelihood surface is not smooth, other methods may be more effective. In this paper, we have demonstrated application of another method inspired from artificial intelligence, called Particle Swarm Optimization (PSO) for estimating cosmological parameters from Cosmic Microwave Background (CMB) data taken from the WMAP satellite.

  3. A flow reactor setup for photochemistry of biphasic gas/liquid reactions

    Josef Schachtner


    Full Text Available A home-built microreactor system for light-mediated biphasic gas/liquid reactions was assembled from simple commercial components. This paper describes in full detail the nature and function of the required building elements, the assembly of parts, and the tuning and interdependencies of the most important reactor and reaction parameters. Unlike many commercial thin-film and microchannel reactors, the described set-up operates residence times of up to 30 min which cover the typical rates of many organic reactions. The tubular microreactor was successfully applied to the photooxygenation of hydrocarbons (Schenck ene reaction. Major emphasis was laid on the realization of a constant and highly reproducible gas/liquid slug flow and the effective illumination by an appropriate light source. The optimized set of conditions enabled the shortening of reaction times by more than 99% with equal chemoselectivities. The modular home-made flow reactor can serve as a prototype model for the continuous operation of various other reactions at light/liquid/gas interfaces in student, research, and industrial laboratories.

  4. A flow reactor setup for photochemistry of biphasic gas/liquid reactions.

    Schachtner, Josef; Bayer, Patrick; Jacobi von Wangelin, Axel


    A home-built microreactor system for light-mediated biphasic gas/liquid reactions was assembled from simple commercial components. This paper describes in full detail the nature and function of the required building elements, the assembly of parts, and the tuning and interdependencies of the most important reactor and reaction parameters. Unlike many commercial thin-film and microchannel reactors, the described set-up operates residence times of up to 30 min which cover the typical rates of many organic reactions. The tubular microreactor was successfully applied to the photooxygenation of hydrocarbons (Schenck ene reaction). Major emphasis was laid on the realization of a constant and highly reproducible gas/liquid slug flow and the effective illumination by an appropriate light source. The optimized set of conditions enabled the shortening of reaction times by more than 99% with equal chemoselectivities. The modular home-made flow reactor can serve as a prototype model for the continuous operation of various other reactions at light/liquid/gas interfaces in student, research, and industrial laboratories.

  5. EMPIRE: Nuclear Reaction Model Code System for Data Evaluation

    Herman, M.; Capote, R.; Carlson, B. V.; Obložinský, P.; Sin, M.; Trkov, A.; Wienke, H.; Zerkin, V.


    accompanying code EMPEND and completed with neutron resonances extracted from the existing evaluations. The package contains the full EXFOR (CSISRS) library of experimental reaction data that are automatically retrieved during the calculations. Publication quality graphs can be obtained using the powerful and flexible plotting package ZVView. The graphic user interface, written in Tcl/Tk, provides for easy operation of the system. This paper describes the capabilities of the code, outlines physical models and indicates parameter libraries used by EMPIRE to predict reaction cross sections and spectra, mainly for nucleon-induced reactions. Selected applications of EMPIRE are discussed, the most important being an extensive use of the code in evaluations of neutron reactions for the new US library ENDF/B-VII.0. Future extensions of the system are outlined, including neutron resonance module as well as capabilities of generating covariances, using both KALMAN and Monte-Carlo methods, that are still being advanced and refined.

  6. Comparison of dosimetric parameter and adverse reaction analysis in different radiation technology in the patients received modi-fied radical mastectomy for breast cancer%乳腺癌改良根治术后不同放疗技术的剂量学比较及不良反应观察

    王承伟; 许刚; 薛辉; 张良


    Objective: To compare dosimetric difference and acute adverse reactions between 3 different radiotherapy plan in pa⁃tients who received modified radical mastectomy for breast cancer. Methods:30 cases of modified radical mastectomy of breast cancer pa⁃tients were left after the design of volumetric modulated arc (VMAT), intensity-modulated (IMRT) and three-dimensional conformal radiother⁃apy (3D-CRT), were randomly divided into VMAT, IMRT and 3D-CRT group, each group of 10 cases, radiotherapy according to the prescrip⁃tion dose of 50 Gy The dose volume histogram (DVH) analysis was used to evaluate the dose parameters of planning target volume (PTV) , the treatment time in each time. V5, V10, V20, Dmean in left lung, V30, V40, and Dmeanof heart were compared between 3 groups. Acute radiation skin reaction, lung injury was evaluated. The changes of cardiac TroponinI was used to evaluate cardiac injury.Results:All of the evaluation indexes except for HI of 3D-CRT PTVwere inferior to VMAT and IMRT (P2, 30.05).Conclusion:The dose distribution and uniformity in VMAT and IMRT were better than that in 3D-CRT, and VMAT has obvious advantage in target volume dose coverage and fraction treatment time than other 2 groups, VMAT and IMRT can effec⁃tively reduce the high dose area volume and average dose of OAR, reduce the incidence of acute adverse reactions such as skin damage, heart damage and so on.%目的:比较乳腺癌改良根治术后3种不同放疗计划的剂量学差异和急性不良反应。方法:将30例左侧乳腺癌改良根治术后患者分别设计容积旋转调强(VMAT)、固定野调强(IMRT)和三维适形放疗(3D-CRT)计划,随机分成VMAT、IMRT和3D-CRT组,各10例,按处方剂量50 Gy进行放射治疗。利用剂量体积直方图(DVH)分析评价PTV的剂量参数,比较患侧肺V5、V10、V20、Dmean,心脏V30、V40、Dmean。评价急性放射性皮肤反应、肺损伤。以心肌肌钙蛋白Ⅰ

  7. American coal imports 2015

    Frank Kolojeski [TransGlobal Ventures Corp. (United States)


    As 2007 ends, the US coal industry passes two major milestones - the ending of the Synfuel tax break, affecting over 100M st annually, and the imposition of tighter and much more expensive safety measures, particularly in deep mines. Both of these issues, arriving at a time of wretched steam coal price levels, promise to result in a major shake up in the Central Appalachian mining sector. The report utilizes a microeconomic regional approach to determine whether either of these two schools of thought have any validity. Transport, infrastructure, competing fuels and regional issues are examined in detail and this forecasts estimates coal demand and imports on a region by region basis for the years 2010 and 2015. Some of the major highlights of the forecast are: Import growth will be driven by steam coal demand in the eastern and southern US; Transport will continue to be the key driver - we believe that inland rail rates will deter imports from being railed far inland and that the great majority of imports will be delivered directly by vessel, barge or truck to end users; Colombian coal will be the overwhelmingly dominant supply source and possesses a costs structure to enable it to compete with US-produced coal in any market conditions; Most of the growth will come from existing power plants - increasing capacity utilization at existing import facilities and other plants making investments to add imports to the supply portfolio - the growth is not dependent upon a lot of new coal fired capacity being built. Contents of the report are: Key US market dynamics; International supply dynamics; Structure of the US coal import market; and Geographic analysis.

  8. Relationship between maximal exercise parameters and individual ...

    Relationship between maximal exercise parameters and individual time trial ... It is widely accepted that the ventilatory threshold (VT) is an important ... This study investigated whether the physiological responses during a 20km time trial (TT) ...

  9. Emergence and spread of antibiotic resistance: setting a parameter space.

    Martínez, José Luis; Baquero, Fernando


    The emergence and spread of antibiotic resistance among human pathogens is a relevant problem for human health and one of the few evolution processes amenable to experimental studies. In the present review, we discuss some basic aspects of antibiotic resistance, including mechanisms of resistance, origin of resistance genes, and bottlenecks that modulate the acquisition and spread of antibiotic resistance among human pathogens. In addition, we analyse several parameters that modulate the evolution landscape of antibiotic resistance. Learning why some resistance mechanisms emerge but do not evolve after a first burst, whereas others can spread over the entire world very rapidly, mimicking a chain reaction, is important for predicting the evolution, and relevance for human health, of a given mechanism of resistance. Because of this, we propose that the emergence and spread of antibiotic resistance can only be understood in a multi-parameter space. Measuring the effect on antibiotic resistance of parameters such as contact rates, transfer rates, integration rates, replication rates, diversification rates, and selection rates, for different genes and organisms, growing under different conditions in distinct ecosystems, will allow for a better prediction of antibiotic resistance and possibilities of focused interventions.

  10. Power-law Fokker-Planck equation of unimolecular reaction based on the approximation to master equation

    Zhou, Yanjun; Yin, Cangtao


    The Fokker-Planck equation (FPE) of the unimolecular reaction with Tsallis distribution is established by means of approximation to the master equation. The memory effect, taken into transition probability, is relevant and important for lots of anomalous phenomena. The Taylor expansion for large volume is applied to derive the power-law FPE. The steady-state solution of FPE and microscopic dynamics Ito-Langevin equation of concentration variables are therefore obtained and discussed. Two unimolecular reactions are taken as examples and the concentration distributions with different power-law parameters are analyzed, which may imply strong memory effect of hopping process.

  11. Fluorogenic organocatalytic reactions

    Raeisolsadati Oskouei, M.


    In this thesis, we introduce fluorescence spectroscopy as a new tool to gain insight into the interactions between the substrates and catalyst during organocatalytic reactions. The ultimate goal is to resolve the kinetics of the binding and reaction steps and obtain detailed understanding of the

  12. Chemical burn or reaction

    ... this page: // Chemical burn or reaction To use the sharing features on this page, please enable JavaScript. Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ...

  13. Reactions to Attitudinal Deviancy.

    Levine, John M.; Allen, Vernon L.

    This paper presents a critical review of empirical and theoretical treatments of group reaction to attitudinal deviancy. Inspired by Festinger's (1950) ideas on resolution of attitudinal discrepancies in groups, Schachter (1951) conducted an experiment that has greatly influenced subsequent research and theory concerning reaction to attitudinal…

  14. Allergic reactions to vaccines.

    Wood, Robert A


    Anaphylactic reactions to vaccines are rare but do occur, and have been reported for nearly every vaccine. And while the reaction rate per each dose of vaccine is low, this is a common clinical question due in large part to the enormous numbers of vaccines administered. Reactions are most often due to vaccine constituents rather than the microbial components of the vaccine, but in many instances, the specific ingredient triggering the reaction cannot be definitively identified. Evaluation of patients with suspected vaccine reactions should begin by determining whether the symptoms and timing of the reaction were consistent with a true allergic reaction, followed by an assessment to determine whether the patient needs further doses of the vaccine in question, or similar vaccines, in the future. Skin and serologic testing to vaccines and vaccine constituents can then be performed to further assess the potential cause of the reaction and to develop a plan for future immunizations. Specific guidelines for the administration of influenza vaccines to egg allergic patients have been revised to allow virtually all patients to receive this vaccine in a straightforward manner. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Chemical reaction and separation method

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.


    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  16. Reactivity of bromoalkanes in reactions of coordinated molecular decay

    Pokidova, T. S.; Denisov, E. T.


    The results from experiments on reactions of the coordinated molecular decay of RBr bromoalkanes on olefin and HBr are analyzed using the model of intersecting parabolas (MIP). Kinetic parameters within the MIP are calculated from the experimental data, enabling calculation of the activation energies ( E) and rate constants ( k) of such reactions, based on the enthalphy of the reaction and the MIP algorithms. The factors affecting the E of the RBr decay reaction are established: the enthalphy of the reaction, triplet repulsion, the energy of radical R• stabilization, the presence of a π bond adjacent to the reaction center, and the dipole-dipole interaction of polar groups. The energy spectrum of the partial energies of activation is constructed for the reaction of coordinated molecular decay of RBr, and the E and k of inverse addition reactions are evaluated.

  17. Supersymmetry Parameter Analysis

    Kalinowski, Jan


    Supersymmetric particles can be produced copiously at future colliders. From the high-precision data taken at e+e- linear colliders, TESLA in particular, and combined with results from LHC, and CLIC later, the low-energy parameters of the supersymmetric model can be determined. Evolving the parameters from the low-energy scale to the high-scale by means of renormalization group techniques the fundamental supersymmetry parameters at the high scale, GUT or Planck, can be reconstructed to reveal the origin of supersymmetry breaking.

  18. Magnetic S-parameter

    Sannino, Francesco


    We propose a direct test of the existence of gauge duals for nonsupersymmetric asymptotically free gauge theories developing an infrared fixed point by computing the S-parameter in the electric and dual magnetic description. In particular we show that at the lower bound of the conformal window...... the magnetic S-parameter, i.e. the one determined via the dual magnetic gauge theory, assumes a simple expression in terms of the elementary magnetic degrees of freedom. The results further support our recent conjecture of the existence of a universal lower bound on the S parameter and indicates...

  19. Kinetics and Mechanism of the Reaction of Coherently Synchronized Oxidation and Dehydrogenation of Cyclohexane by Hydrogen Peroxide

    Aghamammadova S.


    Based on this experimental researches, the complex reaction, consisting of parallel-sequential oxidation and dehydrogenation reactions, which are coherently synchronized, proceeds during the process of cyclohexane oxidation with biomimetic catalyst. Depending on the reaction parameters it is possible to deliberately adjust the direction of oxidation reaction and reaction rate.

  20. Deexcitation Modes in Spallation Nuclear Reactions

    Velasco, F. G.; Guzmán, F.; Rodriguez, O.; Tumbarell, O.; Souza, D. A.; Samana, A. R.; Andrade-II, E.; Bernal Castillo, J. L.; Deppman, A.


    Spallation nuclear reactions in the range of 0.2 to 1.2 GeV are studied using the CRISP code. A new approach for the deexcitation stage of the compound nucleus was introduced. For the calculations of the level densities, this approach is based on the Back-shifted Fermi gas model (BSFG), which takes into account pairing effects and shell corrections, whereas the calculation of the fission barriers were performed by means of the Extended Thomas-Fermi plus Strutinsky Integral (ETFSI) method, which is a high-speed approximation to the Hartree-Fock method with pairing correlations treated as in the usual BCS plus blocking approach. This procedure is more appropriate to calculate level densities for exotic nuclei. Satisfactory results were obtained and compared with experimental data obtained in the GSI experiments. As another important result, we highlight some directions for the development of a qualitatively superior version of the CRISP code with the implementation of more realistic and suitable physical models to be applied in stable and exotic nuclei that participate in the process. This new version of the code includes several substantial changes in the decay of the hot compound nucleus which allow satisfactory agreement with the experimental data and a reduction of the adjustment parameters.