Conversion of magnetic energy to runaway kinetic energy during the termination of runaway current on the J-TEXT tokamak

Science.gov (United States)

Dai, A. J.; Chen, Z. Y.; Huang, D. W.; Tong, R. H.; Zhang, J.; Wei, Y. N.; Ma, T. K.; Wang, X. L.; Yang, H. Y.; Gao, H. L.; Pan, Y.; the J-TEXT Team

2018-05-01

A large number of runaway electrons (REs) with energies as high as several tens of mega-electron volt (MeV) may be generated during disruptions on a large-scale tokamak. The kinetic energy carried by REs is eventually deposited on the plasma-facing components, causing damage and posing a threat on the operation of the tokamak. The remaining magnetic energy following a thermal quench is significant on a large-scale tokamak. The conversion of magnetic energy to runaway kinetic energy will increase the threat of runaway electrons on the first wall. The magnetic energy dissipated inside the vacuum vessel (VV) equals the decrease of initial magnetic energy inside the VV plus the magnetic energy flowing into the VV during a disruption. Based on the estimated magnetic energy, the evolution of magnetic-kinetic energy conversion are analyzed through three periods in disruptions with a runaway current plateau.

The effect of pH profiles in methanogenic aggregates on the kinetics of acetate conversion

NARCIS (Netherlands)

Beer, de D.; Huisman, J.W.; Heuvel, van den J.C.; Ottengraf, S.P.P.

1993-01-01

Due to the conversion of acetic acid into the weaker carbonic acid and CH4, the pH inside methanogenic aggregates is higher than in the bulk liq. The pH profiles in aggregates were measured with pH microelectrodes. These profiles strongly det. the macro-kinetics of the aggregate, by their influence

Steady-state and pre-steady-state kinetic analysis of halopropane conversion by a Rhodococcus haloalkane dehalogenase

NARCIS (Netherlands)

Bosma, T; Pikkemaat, MG; Kingma, Jacob; Dijk, J; Janssen, DB

2003-01-01

Haloalkane dehalogenase from Rhodococcus rhodochrous NCIMB 13064 (DhaA) catalyzes the hydrolysis of carbon-halogen bonds in a wide range of haloalkanes. We examined the steady-state and pre-steady-state kinetics of halopropane conversion by DhaA to illuminate mechanistic details of the

Conversations with Holocaust survivor residents.

Science.gov (United States)

Hirst, Sandra P; LeNavenec, Carole Lynne; Aldiabat, Khaldoun

2011-03-01

Traumatic events in one's younger years can have an impact on how an individual copes with later life. One traumatic experience for Jewish individuals was the Holocaust. Some of these people are moving into long-term care facilities. It was within this context that the research question emerged: What are Holocaust survivor residents' perceptions of a life lived as they move into a long-term care facility? For this qualitative study, Holocaust survivors were individually interviewed. Findings emphasize that nursing care needs to ensure that Holocaust survivor residents participate in activities, receive timely health care, and receive recognition of their life experiences. Copyright 2011, SLACK Incorporated.

"Batch" kinetics in flow: online IR analysis and continuous control.

Science.gov (United States)

Moore, Jason S; Jensen, Klavs F

2014-01-07

Currently, kinetic data is either collected under steady-state conditions in flow or by generating time-series data in batch. Batch experiments are generally considered to be more suitable for the generation of kinetic data because of the ability to collect data from many time points in a single experiment. Now, a method that rapidly generates time-series reaction data from flow reactors by continuously manipulating the flow rate and reaction temperature has been developed. This approach makes use of inline IR analysis and an automated microreactor system, which allowed for rapid and tight control of the operating conditions. The conversion/residence time profiles at several temperatures were used to fit parameters to a kinetic model. This method requires significantly less time and a smaller amount of starting material compared to one-at-a-time flow experiments, and thus allows for the rapid generation of kinetic data. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Numerical simulation and decomposition of kinetic energy in the Central Mediterranean: insight on mesoscale circulation and energy conversion

Directory of Open Access Journals (Sweden)

R. Sorgente

2011-08-01

Full Text Available The spatial and temporal variability of eddy and mean kinetic energy of the Central Mediterranean region has been investigated, from January 2008 to December 2010, by mean of a numerical simulation mainly to quantify the mesoscale dynamics and their relationships with physical forcing. In order to understand the energy redistribution processes, the baroclinic energy conversion has been analysed, suggesting hypotheses about the drivers of the mesoscale activity in this area. The ocean model used is based on the Princeton Ocean Model implemented at 1/32° horizontal resolution. Surface momentum and buoyancy fluxes are interactively computed by mean of standard bulk formulae using predicted model Sea Surface Temperature and atmospheric variables provided by the European Centre for Medium Range Weather Forecast operational analyses. At its lateral boundaries the model is one-way nested within the Mediterranean Forecasting System operational products.

The model domain has been subdivided in four sub-regions: Sardinia channel and southern Tyrrhenian Sea, Sicily channel, eastern Tunisian shelf and Libyan Sea. Temporal evolution of eddy and mean kinetic energy has been analysed, on each of the four sub-regions, showing different behaviours. On annual scales and within the first 5 m depth, the eddy kinetic energy represents approximately the 60 % of the total kinetic energy over the whole domain, confirming the strong mesoscale nature of the surface current flows in this area. The analyses show that the model well reproduces the path and the temporal behaviour of the main known sub-basin circulation features. New mesoscale structures have been also identified, from numerical results and direct observations, for the first time as the Pantelleria Vortex and the Medina Gyre.

The classical kinetic energy decomposition (eddy and mean allowed to depict and to quantify the permanent and fluctuating parts of the circulation in the region, and

Kinetics of coal liquefaction during heating-up and isothermal stages

Energy Technology Data Exchange (ETDEWEB)

Xian Li; Haoquan Hu; Shengwei Zhu; Shuxun Hu; Bo Wu; Meng Meng [Dalian University of Technology, Dalian (China). Institute of Coal Chemical Engineering

2008-04-15

Direct liquefaction of Shenhua bituminous coal was carried out in a 500 ml autoclave with iron catalyst and coal liquefaction cycle-oil as solvent at initial hydrogen of 8.0 MPa, residence time of 0-90 min. To investigate the liquefaction kinetics, a model for heating-up and isothermal stages was developed to estimate the rate constants of both stages. In the model, the coal was divided into three parts, easy reactive part, hard reactive part and unreactive part, and four kinetic constants were used to describe the reaction mechanism. The results showed that the model is valid for both heating-up and isothermal stages of liquefaction perfectly. The rate-controlled process for coal liquefaction is the reaction of preasphaltene plus asphaltene (PAA) to oil plus gas (O + G). The upper-limiting conversion of isothermal stage was estimated by the kinetic calculation. 21 refs., 4 figs., 4 tabs.

Direct conversion of fusion energy

International Nuclear Information System (INIS)

Johansson, Markus

2003-03-01

Deuterium and tritium are expected to be used as fuel in the first fusion reactors. Energy is released as kinetic energy of ions and neutrons, when deuterium reacts with tritium. One way to convert the kinetic energy to electrical energy, is to let the ions and neutrons hit the reactor wall and convert the heat that is caused by the particle bombardment to electrical energy with ordinary thermal conversion. If the kinetic energy of the ions instead is converted directly to electrical energy, a higher efficiency of the energy conversion is possible. The majority of the fusion energy is released as kinetic energy of neutrons, when deuterium reacts with tritium. Fusion reactions such as the D-D reactions, the D- 3 He reaction and the p- 11 B reaction, where a larger part of the fusion energy becomes kinetic energy of charged particles, appears therefore more suitable for direct conversion. Since they have lower reactivity than the D-T reaction, they need a larger βB 2 0 to give sufficiently high fusion power density. Because of this, the fusion configurations spherical torus (ST) and field-reversed configuration (FRC), where high β values are possible, appear interesting. Rosenbluth and Hinton come to the conclusion that efficient direct conversion isn't possible in closed field line systems and that open geometries, which facilitate direct conversion, provide inadequate confinement for D- 3 He. It is confirmed in this study that it doesn't seem possible to achieve as high direct conversion efficiency in closed systems as in open systems. ST and FRC fusion power plants that utilize direct conversion seem however interesting. Calculations with the help of Maple indicate that the reactor parameters needed for a D-D ST and a D 3 He ST hopefully are possible to achieve. The best energy conversion option for a D-D or D 3 He ST appears to be direct electrodynamic conversion (DEC) together with ordinary thermal conversion or liquid metal MHD conversion (LMMHD). For a D

Direct conversion of fusion energy

Energy Technology Data Exchange (ETDEWEB)

Johansson, Markus

2003-03-01

Deuterium and tritium are expected to be used as fuel in the first fusion reactors. Energy is released as kinetic energy of ions and neutrons, when deuterium reacts with tritium. One way to convert the kinetic energy to electrical energy, is to let the ions and neutrons hit the reactor wall and convert the heat that is caused by the particle bombardment to electrical energy with ordinary thermal conversion. If the kinetic energy of the ions instead is converted directly to electrical energy, a higher efficiency of the energy conversion is possible. The majority of the fusion energy is released as kinetic energy of neutrons, when deuterium reacts with tritium. Fusion reactions such as the D-D reactions, the D-{sup 3}He reaction and the p-{sup 11}B reaction, where a larger part of the fusion energy becomes kinetic energy of charged particles, appears therefore more suitable for direct conversion. Since they have lower reactivity than the D-T reaction, they need a larger {beta}B{sup 2}{sub 0} to give sufficiently high fusion power density. Because of this, the fusion configurations spherical torus (ST) and field-reversed configuration (FRC), where high {beta} values are possible, appear interesting. Rosenbluth and Hinton come to the conclusion that efficient direct conversion isn't possible in closed field line systems and that open geometries, which facilitate direct conversion, provide inadequate confinement for D-{sup 3}He. It is confirmed in this study that it doesn't seem possible to achieve as high direct conversion efficiency in closed systems as in open systems. ST and FRC fusion power plants that utilize direct conversion seem however interesting. Calculations with the help of Maple indicate that the reactor parameters needed for a D-D ST and a D{sub 3} He ST hopefully are possible to achieve. The best energy conversion option for a D-D or D{sub 3} He ST appears to be direct electrodynamic conversion (DEC) together with ordinary thermal conversion

Kinetic effects in the conversion of fast waves in pre-heated, low aspect ratio tokamak plasmas

Energy Technology Data Exchange (ETDEWEB)

Kommoshvili, K [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Cuperman, S [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Bruma, C [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)

2003-03-01

Kinetic effects in the conversion of fast waves to Alfven waves and their subsequent deposition in low aspect ratio (spherical) tokamaks (LARTs) have been investigated theoretically. More specifically, we have considered the consequences of incorporation of kinetic effects in the electron parallel (to the ambient magnetic field) dynamics derived by following the drift-tearing mode analysis of Chen et al (Chen L, Rutherford P H and Tang W M 1977 Phys. Rev. Lett. 39 460), and particle-conserving Krook collision operator for the passing electrons involved (Mett R R and Mahajan S M 1992 Phys. Fluids B 4 2885). The perpendicular plasma dynamics is described by a quite general resistive two-fluid (2F) model based dielectric tensor-operator (Cuperman S, Bruma C and Komoshvili K 2002 Solution of the resistive 2F wave equations for Alfvenic modes in spherical tokamak plasmas J. Plasma Phys. accepted for publication). The full-wave electromagnetic equations, formulated in terms of the vector and scalar potentials, have been solved by the aid of an advanced finite elements numerical code (Sewell G 1993 Adv. Eng. Software 17 105). Detailed solutions of the full-wave equations are obtained and compared with those corresponding to a pure resistive 2F model, this, for the illustrative pre-heated START-type device (Sykes 1994). Our results quantitatively confirm the general theory of the conversion of fast waves with subsequent power dissipation for the conditions of spherical tokamaks thus providing the required auxiliary energy source for the successful operation of LARTs. Moreover, these results indicate the absolute necessity of using a full model for the parallel electron dynamics, i.e. including both kinetic and collisional effects.

Kinetic effects in the conversion of fast waves in pre-heated, low aspect ratio tokamak plasmas

International Nuclear Information System (INIS)

Kommoshvili, K; Cuperman, S; Bruma, C

2003-01-01

Kinetic effects in the conversion of fast waves to Alfven waves and their subsequent deposition in low aspect ratio (spherical) tokamaks (LARTs) have been investigated theoretically. More specifically, we have considered the consequences of incorporation of kinetic effects in the electron parallel (to the ambient magnetic field) dynamics derived by following the drift-tearing mode analysis of Chen et al (Chen L, Rutherford P H and Tang W M 1977 Phys. Rev. Lett. 39 460), and particle-conserving Krook collision operator for the passing electrons involved (Mett R R and Mahajan S M 1992 Phys. Fluids B 4 2885). The perpendicular plasma dynamics is described by a quite general resistive two-fluid (2F) model based dielectric tensor-operator (Cuperman S, Bruma C and Komoshvili K 2002 Solution of the resistive 2F wave equations for Alfvenic modes in spherical tokamak plasmas J. Plasma Phys. accepted for publication). The full-wave electromagnetic equations, formulated in terms of the vector and scalar potentials, have been solved by the aid of an advanced finite elements numerical code (Sewell G 1993 Adv. Eng. Software 17 105). Detailed solutions of the full-wave equations are obtained and compared with those corresponding to a pure resistive 2F model, this, for the illustrative pre-heated START-type device (Sykes 1994). Our results quantitatively confirm the general theory of the conversion of fast waves with subsequent power dissipation for the conditions of spherical tokamaks thus providing the required auxiliary energy source for the successful operation of LARTs. Moreover, these results indicate the absolute necessity of using a full model for the parallel electron dynamics, i.e. including both kinetic and collisional effects

Optimization of semi-continuous anaerobic digestion of sugarcane straw co-digested with filter cake: Effects of macronutrients supplementation on conversion kinetics.

Science.gov (United States)

Janke, Leandro; Weinrich, Sören; Leite, Athaydes F; Schüch, Andrea; Nikolausz, Marcell; Nelles, Michael; Stinner, Walter

2017-12-01

Anaerobic digestion of sugarcane straw co-digested with sugarcane filter cake was investigated with a special focus on macronutrients supplementation for an optimized conversion process. Experimental data from batch tests and a semi-continuous experiment operated in different supplementation phases were used for modeling the conversion kinetics based on continuous stirred-tank reactors. The semi-continuous experiment showed an overall decrease in the performance along the inoculum washout from the reactors. By supplementing nitrogen alone or in combination to phosphorus and sulfur the specific methane production significantly increased (P0.99), the use of the depicted kinetics did not provide a good estimation for process simulation of the semi-continuous process (in any supplementation phase), possibly due to the different feeding modes and inoculum source, activity and adaptation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ab initio calculations and kinetic modeling of thermal conversion of methyl chloride: implications for gasification of biomass

DEFF Research Database (Denmark)

Singla, Mallika; Rasmussen, Morten Lund; Hashemi, Hamid

2018-01-01

. In the present work, the thermal conversion of CH3Cl under gasification conditions was investigated. A detailed chemical kinetic model for pyrolysis and oxidation of methyl chloride was developed and validated against selected experimental data from the literature. Key reactions of CH2Cl with O2 and C2H4......Limitations in current hot gas cleaning methods for chlorine species from biomass gasification may be a challenge for end use such as gas turbines, engines, and fuel cells, all requiring very low levels of chlorine. During devolatilization of biomass, chlorine is released partly as methyl chloride...... in low-temperature gasification. The present work illustrates how ab initio theory and chemical kinetic modeling can help to resolve emission issues for thermal processes in industrial scale....

Kinetic effects in the conversion of fast waves in pre-heated, low aspect ratio tokamak plasmas

Science.gov (United States)

Kommoshvili, K.; Cuperman, S.; Bruma, C.

2003-03-01

Kinetic effects in the conversion of fast waves to Alfvèn waves and their subsequent deposition in low aspect ratio (spherical) tokamaks (LARTs) have been investigated theoretically. More specifically, we have considered the consequences of incorporation of kinetic effects in the electron parallel (to the ambient magnetic field) dynamics derived by following the drift-tearing mode analysis of Chen et al (Chen L, Rutherford P H and Tang W M 1977 Phys. Rev. Lett. 39 460), and particle-conserving Krook collision operator for the passing electrons involved (Mett R R and Mahajan S M 1992 Phys. Fluids B 4 2885). The perpendicular plasma dynamics is described by a quite general resistive two-fluid (2F) model based dielectric tensor-operator (Cuperman S, Bruma C and Komoshvili K 2002 Solution of the resistive 2F wave equations for Alfvènic modes in spherical tokamak plasmas J. Plasma Phys. accepted for publication). The full-wave electromagnetic equations, formulated in terms of the vector and scalar potentials, have been solved by the aid of an advanced finite elements numerical code (Sewell G 1993 Adv. Eng. Software 17 105). Detailed solutions of the full-wave equations are obtained and compared with those corresponding to a pure resistive 2F model, this, for the illustrative pre-heated START-type device (Sykes 1994). Our results quantitatively confirm the general theory of the conversion of fast waves with subsequent power dissipation for the conditions of spherical tokamaks thus providing the required auxilliary energy source for the succesful operation of LARTs. Moreover, these results indicate the absolute necessity of using a full model for the parallel electron dynamics, i.e. including both kinetic and collisional effects.

Positronium spin conversion during collisions with Xe and its application for measuring the kinetic energy

International Nuclear Information System (INIS)

Shibuya, Kengo; Kawamura, Yoshihiro; Saito, Haruo

2015-01-01

Positronium(Ps) can undergo ortho-para spin conversion reaction during Ps-Xecollisions due to spin-orbit interaction. We have investigated energy dependence of this reaction rate and found it is nearly proportional to T 2.1 , where T is the temperature (300-623 K), while the pick-off annihilation rate is proportional to T. The strong temperature dependence of the former annihilation rate is attributed to a nature of p-wave scattering because this reaction is forbidden in s-wave scattering. In addition, a new method for measuring Ps kinetic energy has been developed with a high resolution and a high sensitivity by utilizing the strong temperature dependence as a 'thermometer.' Analyzingthe obtained time evolution of Ps kinetic energy, we have determined the momentum transfer cross section during Ps-Xecollisions at a very low energy (40-60 meV) to be 12(2)×10 −16 cm 2 . (paper)

Time-Dependent Effect of Refrigeration on Viscosity and Conversion Kinetics of Dental Adhesive Resins

Science.gov (United States)

Faria-e-Silva, André L; Piva, Evandro; Moraes, Rafael R

2010-01-01

Objectives: This study evaluated the effect of refrigeration at 4°C and post-refrigeration times (immediate, 5, 10, 15, or 20 min) on the viscosity and conversion kinetics of adhesive bonding resins. Methods: Scotchbond Dual-Cure (3M ESPE) and Clearfil SE Bond (Kuraray) were tested. Control samples were kept at 25°C for 24 h. At each post-refrigeration time, the temperature was checked with a K-type thermocouple. Viscosity measurements as a function of temperature were performed using a cone-plate viscometer. Real-time polymerization was monitored by infrared spectroscopy. Degree of conversion (DC) was calculated for each second during polymerization, and the rate of polymerization analyzed. Data were separately submitted to two-way ANOVA and Tukey’s test (P<.05). Results: Clearfil presented faster increase in temperature after exposure to room temperature than Scotchbond. A continuous decrease in viscosity (Pa.s) was observed for both Scotchbond (0.49, 0.34, 0.30, 0.26, 0.23, 0.23) and Clearfil (0.38, 0.37, 0.34, 0.25, 0.24, 0.22). For Scotchbond, higher final DC was detected for the control (62.7%) compared with the immediate (53.3%) and 5 min (54.7%) groups. For Clearfil, the control sample (81.4%) showed higher DC than all refrigerated groups (68.8–69.5%). Clearfil always showed significantly higher DC than Scotchbond. Conclusions: Refrigeration presented a significant time- and material-dependent effect on the viscosity and polymerization kinetics of the bonding resins. Under clinical conditions, adhesive agents should be removed from the refrigerator at least 20 min before being used. PMID:20396445

Experimental and Kinetic Modeling Studies on the Conversion of Sucrose to Levulinic Acid and 5-Hydroxymethylfurfural Using Sulfuric Acid in Water

NARCIS (Netherlands)

Tan-Soetedjo, Jenny N. M.; van de Bovenkamp, Henk H.; Abdilla, Ria M.; Rasrendra, Carolus B.; van Ginkel, Jacob; Heeres, Hero J.

2017-01-01

We here report experimental and kinetic modeling studies on the conversion of sucrose to levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) in water using sulfuric acid as the catalyst. Both compounds are versatile building blocks for the synthesis of various biobased (bulk) chemicals. A total of

Energy Conversion & Storage Program, 1993 annual report

Energy Technology Data Exchange (ETDEWEB)

Cairns, E.J.

1994-06-01

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

D-malate production by permeabilized Pseudomonas pseudoalcaligenes; optimization of conversion and biocatalyst productivity.

Science.gov (United States)

Michielsen, M J; Frielink, C; Wijffels, R H; Tramper, J; Beeftink, H H

2000-04-14

For the development of a continuous process for the production of solid D-malate from a Ca-maleate suspension by permeabilized Pseudomonas pseudoalcaligenes, it is important to understand the effect of appropriate process parameters on the stability and activity of the biocatalyst. Previously, we quantified the effect of product (D-malate2 -) concentration on both the first-order biocatalyst inactivation rate and on the biocatalytic conversion rate. The effects of the remaining process parameters (ionic strength, and substrate and Ca2 + concentration) on biocatalyst activity are reported here. At (common) ionic strengths below 2 M, biocatalyst activity was unaffected. At high substrate concentrations, inhibition occurred. Ca2+ concentration did not affect biocatalyst activity. The kinetic parameters (both for conversion and inactivation) were determined as a function of temperature by fitting the complete kinetic model, featuring substrate inhibition, competitive product inhibition and first-order irreversible biocatalyst inactivation, at different temperatures simultaneously through three extended data sets of substrate concentration versus time. Temperature affected both the conversion and inactivation parameters. The final model was used to calculate the substrate and biocatalyst costs per mmol of product in a continuous system with biocatalyst replenishment and biocatalyst recycling. Despite the effect of temperature on each kinetic parameter separately, the overall effect of temperature on the costs was found to be negligible (between 293 and 308 K). Within pertinent ranges, the sum of the substrate and biocatalyst costs per mmol of product was calculated to decrease with the influent substrate concentration and the residence time. The sum of the costs showed a minimum as a function of the influent biocatalyst concentration.

Resident Reactions to Person-Centered Communication by Long-Term Care Staff.

Science.gov (United States)

Savundranayagam, Marie Y; Sibalija, Jovana; Scotchmer, Emma

2016-09-01

Long-term care staff caregivers who are person centered incorporate the life history, preferences, and feelings of residents with dementia during care interactions. Communication is essential for person-centered care. However, little is known about residents' verbal reactions when staff use person-centered communication. Accordingly, this study investigated the impact of person-centered communication and missed opportunities for such communication by staff on resident reactions. Conversations (N = 46) between staff-resident dyads were audio-recorded during routine care tasks over 12 weeks. Staff utterances were coded for person-centered communication and missed opportunities. Resident utterances were coded for positive reactions, such as cooperation, and negative reactions, such as distress. Linear regression analyses revealed that the more staff used person-centered communication, the more likely that residents reacted positively. Additionally, the more missed opportunities in a conversation, the more likely that the residents reacted negatively. Conversation illustrations elaborate on the quantitative findings and implications for staff training are discussed. © The Author(s) 2016.

Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

Science.gov (United States)

Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

2016-05-24

Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

Hydrothermal pentose to furfural conversion and simultaneous extraction with SC-CO2--kinetics and application to biomass hydrolysates.

Science.gov (United States)

Gairola, Krishan; Smirnova, Irina

2012-11-01

This work explores hydrothermal d-xylose and hemicellulose to furfural conversion coupled with simultaneous furfural extraction by SC-CO(2) and the underlying reaction pathway. A maximum furfural yield of 68% was attained from d-xylose at 230°C and 12MPa. Additionally missing kinetic data for l-arabinose to furfural conversion was provided, showing close similarity to d-xylose. Furfural yields from straw and brewery waste hydrolysates were significantly lower than those obtained from model compounds, indicating side reactions with other hydrolysate components. Simultaneous furfural extraction by SC-CO(2) significantly increased extraction yield in all cases. The results indicate that furfural reacts with intermediates of pentose dehydration. The proposed processing route can be well integrated into existing lignocellulose biorefinery concepts. Copyright © 2012 Elsevier Ltd. All rights reserved.

Experimental and Kinetic Modeling Studies on the Sulfuric Acid Catalyzed Conversion of D-Fructose to 5-Hydroxymethylfurfural and Levulinic Acid in Water

NARCIS (Netherlands)

Fachri, Boy A.; Abdilla, Ria M.; van de Bovenkamp, Henk H.; Rasrendra, Carolus B.; Heeres, Hero J.

2015-01-01

Levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) have been identified as promising biomass-derived platform chemicals. A kinetic study on the conversion of D-fructose to HMF and LA in water using sulfuric acid as the catalyst has been performed in batch setups. The experiments were carried out

Fundamental Study of Black Liquor Gasification Kinetics. Quarterly progress report for the period October 1999 to December 1999

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-01-31

The overall objective of this research is to evaluate the kinetics of gasification of kraft black liquor under laboratory conditions simulating pressurized, oxygen-blown gasification. The significant independent variables are gasifier temperature, black liquor composition particle size, and particle residence time. The authors will quantify their impact on the concentration of major and trace gas phase species, as well as the composition of condensed phase inorganic products, including specification of the Na- and S-containing compounds and overall carbon conversion.

A Study on the Hydrotreating of Coal Hydroliquefaction Residue and its Kinetics

Directory of Open Access Journals (Sweden)

Jinsheng Gao

2010-09-01

Full Text Available Hydro-conversion of coal hydroliquefaction residue obtained from a 6t/day pilot plant of Shenhua Group in Shanghai was carried out under the hydrotreating condition. The coal hydroliquefaction residue and its product were extracted in sequence with n-hexane, toluene and tetrahydrofuran in a Soxhlet apparatus. The n-hexane soluble fractions increased with the increase of reaction temperature and time. Its amount increased from 14.14% to a maximum of 40.86% under the conditions of 470 °C and 30 min, which meant that moderate extension of coal residence time in the coal hydroliquefaction reactor is beneficial to the increase of oil yield. A 4-lumped kinetic model of coal hydroliquefaction residue hydro-conversion was performed using solubility-based lumped fractions. In the model, the tetrahydrofuran insoluble fractions were classified into two parts: easily reactive part and unreactive part. The kinetic parameters were estimated by a fourth-order Runge-Kutta method and a nonlinear least squares method, and the apparent activation energies were calculated according to the Arrhenius Equation. A large quantity of total catalyst consisting of remained liquefaction catalyst, part of the mineral from raw coal and additive Fe-based catalyst could considerably reduce the apparent activation energy of hydro-conversion for the toluene insoluble/tetrahydrofuran insoluble fractions to 36.79 kJ•mol-1. The calculated values of the model coincided well with the experimental values.

On-rate based optimization of structure-kinetic relationship--surfing the kinetic map.

Science.gov (United States)

Schoop, Andreas; Dey, Fabian

2015-10-01

In the lead discovery process residence time has become an important parameter for the identification and characterization of the most efficacious compounds in vivo. To enable the success of compound optimization by medicinal chemistry toward a desired residence time the understanding of structure-kinetic relationship (SKR) is essential. This article reviews various approaches to monitor SKR and suggests using the on-rate as the key monitoring parameter. The literature is reviewed and examples of compound series with low variability as well as with significant changes in on-rates are highlighted. Furthermore, findings of kinetic on-rate changes are presented and potential underlying rationales are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Qualitative and kinetic analysis of torrefaction of lignocellulosic biomass using DSC-TGA-FTIR

Directory of Open Access Journals (Sweden)

Bimal Acharya

2015-11-01

Full Text Available Torrefaction is a thermochemical conversion technique to improve the fuel properties of lignocellulosic biomass by treating at temperature 200 ℃-300 ℃ in the minimum oxygen environment for a reasonable residence time. In this study, thermal decomposition and thermal activities of miscanthus and wheat straw during the torrefaction at 200 ℃, 275 ℃, and 300 ℃ in a nitrogen environment for 45 minutes of residence time are analyzed in a simultaneous thermogravimetric analyzer (micro TGA with a differential scanning calorimetry (DSC, and a macro-TGA. The output of the micro TGA is fed into the Fourier transform infrared spectrometry (FTIR and qualitative analysis of the gaseous product is carried out. The composition of different gas products during the torrefaction of biomass are compared critically and kinetics were analyzed. It is found that the weight loss due to degradation of initial biomass in second stage (torrefaction process is a much faster conversion process than the weight loss process in the first stage (drying process. The weight loss of biomass increases with increase in the residence time and torrefaction treatment temperatures. The yield after torrefaction is a solid bio-coal product. The torrefied product were less reactive and has nearly 25% better heating value than the raw biomass. Between the two feedstocks studied, torrefied miscanthus proved to be a more stable fuel than the torrefied wheat straw. The major gaseous components observed during torrefaction are water, carbon dioxide, carbon monoxide, 1,2-Dibromethylene.

Kinetic Study of Nonequilibrium Plasma-Assisted Methane Steam Reforming

Directory of Open Access Journals (Sweden)

Hongtao Zheng

2014-01-01

Full Text Available To develop a detailed reaction mechanism for plasma-assisted methane steam reforming, a comprehensive numerical and experimental study of effect laws on methane conversion and products yield is performed at different steam to methane molar ratio (S/C, residence time s, and reaction temperatures. A CHEMKIN-PRO software with sensitivity analysis module and path flux analysis module was used for simulations. A set of comparisons show that the developed reaction mechanism can accurately predict methane conversion and the trend of products yield in different operating conditions. Using the developed reaction mechanism in plasma-assisted kinetic model, the reaction path flux analysis was carried out. The result shows that CH3 recombination is the limiting reaction for CO production and O is the critical species for CO production. Adding 40 wt.% Ni/SiO2 in discharge region has significantly promoted the yield of H2, CO, or CO2 in dielectric packed bed (DPB reactor. Plasma catalytic hybrid reforming experiment verifies the reaction path flux analysis tentatively.

A study on the hydrotreating of coal hydro liquefaction residue and its kinetics

Energy Technology Data Exchange (ETDEWEB)

Huang, J.; Lu, X.; Zhang, D.; Gao, J. [Department of Chemical Engineering for Energy Resources, East China University of Science and Technology, Shanghai (China)

2010-09-15

Hydro-conversion of coal hydro liquefaction residue obtained from a 6 t/day pilot plant of Shenhua Group in Shanghai was carried out under the hydrotreating condition. The coal hydro liquefaction residue and its product were extracted in sequence with n-hexane, toluene and tetrahydrofuran in a Soxhlet apparatus. The n-hexane soluble fractions increased with the increase of reaction temperature and time. Its amount increased from 14.14% to a maximum of 40.86% under the conditions of 470 {sup o}C and 30 min, which meant that moderate extension of coal residence time in the coal hydro liquefaction reactor is beneficial to the increase of oil yield. A 4-lumped kinetic model of coal hydro liquefaction residue hydro-conversion was performed using solubility-based lumped fractions. In the model, the tetrahydrofuran insoluble fractions were classified into two parts: easily reactive part and unreactive part. The kinetic parameters were estimated by a fourth-order Runge-Kutta method and a nonlinear least squares method, and the apparent activation energies were calculated according to the Arrhenius Equation. A large quantity of total catalyst consisting of remained liquefaction catalyst, part of the mineral from raw coal and additive Fe-based catalyst could considerably reduce the apparent activation energy of hydro-conversion for the toluene insoluble/tetrahydrofuran insoluble fractions to 36.79 kJ-mol{sup -1}. The calculated values of the model coincided well with the experimental values. (authors)

Thermochemical conversion of biomass in smouldering combustion across scales: The roles of heterogeneous kinetics, oxygen and transport phenomena.

Science.gov (United States)

Huang, Xinyan; Rein, Guillermo

2016-05-01

The thermochemical conversion of biomass in smouldering combustion is investigated here by combining experiments and modeling at two scales: matter (1mg) and bench (100g) scales. Emphasis is put on the effect of oxygen (0-33vol.%) and oxidation reactions because these are poorly studied in the literature in comparison to pyrolysis. The results are obtained for peat as a representative biomass for which there is high-quality experimental data published previously. Three kinetic schemes are explored, including various steps of drying, pyrolysis and oxidation. The kinetic parameters are found using the Kissinger-Genetic Algorithm method, and then implemented in a one-dimensional model of heat and mass transfer. The predictions are validated with thermogravimetric and bench-scale experiments and then analyzed to unravel the role of heterogeneous reaction. This is the first time that the influence of oxygen on biomass smouldering is explained in terms of both chemistry and transport phenomena across scales. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Kinetic modeling of cellulosic biomass to ethanol via simultaneous saccharification and fermentation: Part I. Accommodation of intermittent feeding and analysis of staged reactors.

Science.gov (United States)

Shao, Xiongjun; Lynd, Lee; Wyman, Charles; Bakker, André

2009-01-01

The model of South et al. [South et al. (1995) Enzyme Microb Technol 17(9): 797-803] for simultaneous saccharification of fermentation of cellulosic biomass is extended and modified to accommodate intermittent feeding of substrate and enzyme, cascade reactor configurations, and to be more computationally efficient. A dynamic enzyme adsorption model is found to be much more computationally efficient than the equilibrium model used previously, thus increasing the feasibility of incorporating the kinetic model in a computational fluid dynamic framework in the future. For continuous or discretely fed reactors, it is necessary to use particle conversion in conversion-dependent hydrolysis rate laws rather than reactor conversion. Whereas reactor conversion decreases due to both reaction and exit of particles from the reactor, particle conversion decreases due to reaction only. Using the modified models, it is predicted that cellulose conversion increases with decreasing feeding frequency (feedings per residence time, f). A computationally efficient strategy for modeling cascade reactors involving a modified rate constant is shown to give equivalent results relative to an exhaustive approach considering the distribution of particles in each successive fermenter.

Kinetics of vinyl acetate emulsion polymerization in a pulsed tubular reactor: comparison between experimental and simulation results

Directory of Open Access Journals (Sweden)

Sayer C.

2002-01-01

Full Text Available A new reactor, the pulsed sieve plate column (PSPC, was developed to perform continuous emulsion polymerization reactions. This reactor combines the enhanced flexibility of tubular reactors with the mixing behavior provided by sieved plates and by the introduction of pulses that is important to prevent emulsion destabilization. The main objective of this work is to study the kinetics of vinyl acetate (VA emulsion polymerization reactions performed in this PSPC. Therefore, both experimental studies and reaction simulations were performed. Results showed that it is possible to obtain high conversions with rather low residence times in the PSPC.

Carbon conversion predictor for fluidized bed gasification of biomass fuels - from TGA measurements to char gasification particle model

Energy Technology Data Exchange (ETDEWEB)

Konttinen, J.T. [University of Jyvaeskylae, Department of Chemistry, Renewable Energy Programme, POB 35, Jyvaeskylae (Finland); Moilanen, A. [VTT Technical Research Centre of Finland, POB 1000, Espoo (Finland); Martini, N. de; Hupa, M. [Abo Akademi University, Process Chemistry Centre, Combustion and Materials Chemistry, Turku (Finland)

2012-09-15

When a solid fuel particle is injected into a hot fluidized bed, the reactivity of fuel char in gasification reactions (between char carbon and steam and CO{sub 2}) plays a significant role for reaching a good carbon conversion. In this paper, the gasification reactivity data of some solid waste recovered fuels (SRF) obtained from thermogravimetric analysis (TGA) experiments is presented. Gas mixtures (H{sub 2}O, H{sub 2}, CO{sub 2}, CO), were used in the experiments to find the inhibitive effects of CO and H{sub 2}. Average char gasification reactivity values are determined from the TGA results. Kinetic parameters for char carbon gasification reactivity correlations are determined from this data. The Uniform Conversion model is used to account for the change of gasification reaction rate as function of carbon conversion. Some discrepancies, due to complicated ash-carbon interactions, are subjects of further research. In the carbon conversion predictor, laboratory measured reactivity numbers are converted into carbon conversion numbers in a real-scale fluidized bed gasifier. The predictor is a relatively simple and transparent tool for the comparison of the gasification reactivity of different fuels in fluidized bed gasification. The residence times for solid fuels in fluidized bed gasifiers are simulated. Simulations against some pilot-scale results show reasonable agreement. (orig.)

HYDROKINETIC ENERGY CONVERSION SYSTEMS: PROSPECTS ...

African Journals Online (AJOL)

eobe

Hydrokinetic energy conversion systems utilize the kinetic energy of flowing water bodies with little or no head to generate ... generator. ... Its principle of operation is analogous to that of wind ..... Crisis-solar and wind power systems, 2009,.

Kinetics of propionate conversion in anaerobic continuously stirred tank reactors

DEFF Research Database (Denmark)

Bangsø Nielsen, Henrik; Mladenovska, Zuzana; Ahring, Birgitte Kiær

2008-01-01

The kinetic parameters of anaerobic propionate degradation by biomass from 7 continuously stirred tank reactors differing in temperature, hydraulic retention time and substrate composition were investigated. In substrate-depletion experiments (batch) the maximum propionate degradation rate, A......-m, was estimated. The results demonstrate that the rate of endogenous substrate (propionate) production should be taken into account when estimating kinetic parameters in biomass from manure-based anaerobic reactors....

Tourism practices of Chinese residents in South Africa | Potgieter ...

African Journals Online (AJOL)

Chinese consumers are different due to their cultural background and way of life and this necessitates a conversion of the business model and products offered by leisure and tourism service providers. Very little is known about tourism practices of resident Chinese in South Africa. Research was conducted amongst resident ...

In-depth investigation on the pyrolysis kinetics of raw biomass. Part I: kinetic analysis for the drying and devolatilization stages.

Science.gov (United States)

Chen, Dengyu; Zheng, Yan; Zhu, Xifeng

2013-03-01

An in-depth investigation was conducted on the kinetic analysis of raw biomass using thermogravimetric analysis (TGA), from which the activation energy distribution of the whole pyrolysis process was obtained. Two different stages, namely, drying stage (Stage I) and devolatilization stage (Stage II), were shown in the pyrolysis process in which the activation energy values changed with conversion. The activation energy at low conversions (below 0.15) in the drying stage ranged from 10 to 30 kJ/mol. Such energy was calculated using the nonisothermal Page model, known as the best model to describe the drying kinetics. Kinetic analysis was performed using the distributed activation energy model in a wide range of conversions (0.15-0.95) in the devolatilization stage. The activation energy first ranged from 178.23 to 245.58 kJ/mol and from 159.66 to 210.76 kJ/mol for corn straw and wheat straw, respectively, then increasing remarkably with an irregular trend. Copyright © 2012 Elsevier Ltd. All rights reserved.

Metal-Oxide Film Conversions Involving Large Anions

Energy Technology Data Exchange (ETDEWEB)

Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C. [The University of Western Ontario, Chemistry Department, 1151 Richmond St., N6A 5B7, London, Ontario (Canada)

2008-07-01

The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I{sup -}, Br{sup -}, S{sup 2-}). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag{sub 2}O to (1) AgI and (2) AgBr. (authors)

Metal-Oxide Film Conversions Involving Large Anions

International Nuclear Information System (INIS)

Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C.

2008-01-01

The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I - , Br - , S 2- ). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag 2 O to (1) AgI and (2) AgBr. (authors)

Pyrolysis of Waste Castor Seed Cake: A Thermo-Kinetics Study

Directory of Open Access Journals (Sweden)

Abdullahi Muhammad Sokoto

2018-03-01

Full Text Available Biomass pyrolysis is a thermo-chemical conversion process that is of both industrial and ecological importance. The efficient chemical transformation of waste biomass to numerous products via pyrolysis reactions depends on process kinetic rates; hence the need for kinetic models to best design and operate the pyrolysis. Also, for an efficient design of an environmentally sustainable pyrolysis process of a specific lignocellulosic waste, a proper understanding of its thermo-kinetic behavior is imperative. Thus, pyrolysis kinetics of castor seed de-oiled cake (Ricinus communis using thermogravimetric technique was studied. The decomposition of the cake was carried out in a nitrogen atmosphere with a flow rate of 100mL min-1 from ambient temperature to 900 °C. The results of the thermal profile showed moisture removal and devolatilization stages, and maximum decomposition of the cake occurred at a temperature of 200-400 °C. The kinetic parameters such as apparent activation energy, pre-exponential factor, and order of reaction were determined using Friedman (FD, Kissinger-Akahira-Sunose (KAS, and Flynn-Wall-Ozawa (FWO kinetic models. The average apparent activation energy values of 124.61, 126.95 and 129.80 kJmol-1 were calculated from the slopes of the respective models. The apparent activation energy values obtained depends on conversion, which is an evidence of multi-step kinetic process during the pyrolytic decomposition of the cake. The kinetic data would be of immense benefit to model, design and develop a suitable thermo-chemical system for the conversion of waste de-oil cake to energy carrier.

Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion.

Science.gov (United States)

Zhao, Chen; Yan, Hu; Liu, Yan; Huang, Yan; Zhang, Ruihong; Chen, Chang; Liu, Guangqing

2016-06-01

Huge amounts of fruit residues are produced and abandoned annually. The high moisture and organic contents of these residues makes them a big problem to the environment. Conversely, they are a potential resource to the world. Anaerobic digestion is a good way to utilize these organic wastes. In this study, the biomethane conversion performances of a large number of fruit residues were determined and compared using batch anaerobic digestion, a reliable and easily accessible method. The results showed that some fruit residues containing high contents of lipids and carbohydrates, such as loquat peels and rambutan seeds, were well fit for anaerobic digestion. Contrarily, residues with high lignin content were strongly recommended not to be used as a single substrate for methane production. Multiple linear regression model was adopted to simulate the correlation between the organic component of these fruit residues and their experimental methane yield, through which the experimental methane yield could probably be predicted for any other fruit residues. Four kinetic models were used to predict the batch anaerobic digestion process of different fruit residues. It was shown that the modified Gompertz and Cone models were better fit for the fruit residues compared to the first-order and Fitzhugh models. The first findings of this study could provide useful reference and guidance for future studies regarding the applications and potential utilization of fruit residues. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methane production from cellulosic wastes: kinetic studies

Energy Technology Data Exchange (ETDEWEB)

Goma, G; De La Torre, I; Maugheri, F; Yameogo, T

1979-09-01

The anaerobic fermentation is studied on lignocellulosic materials and sucrose as substrate. With the lignocellulosic material cellulolysis is rate limiting. The reducing sugar concentration in the fermentation broth is less than 15 mgl/sup -1/. With rumen bacteria, 50% of the initial polyoside are used and 12% of the lignin is solubilized. With sucrose studies on the kinetic behaviour of the mixed population responsible of the acidogenesis step permite to find the optimal temperature (40/sup 0/C) feed substrate concentration (50 gl/sup -1/) residence time (60 hours) and pH (5,5 - 6). The better technology is a plug flow fermentor with cell recycling. Modeling of the behaviour of this reactor was performed. The use of this reactor for the selection of acido resistant bacteria is discussed. For methanogenesis, in continuous culture, the ideal technology seems to be an association of two reactors. In the first step, a plug flow reactor must be used for acidogenesis, and in the second step a well mixed reactor permit the conversion of organic acids in methane.

Nucleation and growth kinetics of zirconium hydroxide by precipitation with ammonium hydroxide

International Nuclear Information System (INIS)

Carleson, T.E.; Chipman, N.A.

1987-01-01

The results of a study of the nucleation and growth kinetics of the precipitation of zirconium hydroxide from the reaction of hexafluorozirconate solution with ammonium hydroxide are reported. The McCabe linear growth rate model was used to correlate the results. The growth rate decreased with residence time and supersaturation for studies with 7 residence times (3.5 - 90 minutes and two supersaturation ratios (0.03 - 0.04, and 0.4). The nucleation rate increased with residence time and supersaturation. A negative kinetic order of nucleation was observed that may be due to the inhibition of particle growth by adsorption of reacting species on the crystal surfaces

Apparatus for the direct conversion of the kinetic energy of charged particles

International Nuclear Information System (INIS)

Mims, L.S.

1976-01-01

An apparatus for converting the output of a high voltage dc source to a lower voltage and a higher current is described. The conversion system is comprised of a plurality of power conversion modules connected electrically in series across the dc source output so that each of the power conversion modules receives only a portion of the high voltage. Each power conversion module includes means for converting the high voltage portion to an ac signal and transformer means for reducing the voltage and increasing the current of such ac signal, the outputs of all of the transformers being connected electrically in parallel. Each of the power conversion means includes a pair of capacitors which are charged by the high voltage dc source and which are alternately, periodically only slightly discharged to convert the dc voltage to an ac signal

Characterization of 12 GnRH peptide agonists - a kinetic perspective.

Science.gov (United States)

Nederpelt, Indira; Georgi, Victoria; Schiele, Felix; Nowak-Reppel, Katrin; Fernández-Montalván, Amaury E; IJzerman, Adriaan P; Heitman, Laura H

2016-01-01

Drug-target residence time is an important, yet often overlooked, parameter in drug discovery. Multiple studies have proposed an increased residence time to be beneficial for improved drug efficacy and/or longer duration of action. Currently, there are many drugs on the market targeting the gonadotropin-releasing hormone (GnRH) receptor for the treatment of hormone-dependent diseases. Surprisingly, the kinetic receptor-binding parameters of these analogues have not yet been reported. Therefore, this project focused on determining the receptor-binding kinetics of 12 GnRH peptide agonists, including many marketed drugs. A novel radioligand-binding competition association assay was developed and optimized for the human GnRH receptor with the use of a radiolabelled peptide agonist, [(125) I]-triptorelin. In addition to radioligand-binding studies, a homogeneous time-resolved FRET Tag-lite™ method was developed as an alternative assay for the same purpose. Two novel competition association assays were successfully developed and applied to determine the kinetic receptor-binding characteristics of 12 high-affinity GnRH peptide agonists. Results obtained from both methods were highly correlated. Interestingly, the binding kinetics of the peptide agonists were more divergent than their affinities with residence times ranging from 5.6 min (goserelin) to 125 min (deslorelin). Our research provides new insights by incorporating kinetic, next to equilibrium, binding parameters in current research and development that can potentially improve future drug discovery targeting the GnRH receptor. © 2015 The British Pharmacological Society.

Frontal Conversion and Uniformity in 3D Printing by Photopolymerisation.

Science.gov (United States)

Vitale, Alessandra; Cabral, João T

2016-09-07

We investigate the impact of the non-uniform spatio-temporal conversion, intrinsic to photopolymerisation, in the context of light-driven 3D printing of polymers. The polymerisation kinetics of a series of model acrylate and thiol-ene systems, both neat and doped with a light-absorbing dye, is investigated experimentally and analysed according to a descriptive coarse-grained model for photopolymerisation. In particular, we focus on the relative kinetics of polymerisation with those of 3D printing, by comparing the evolution of the position of the conversion profile ( z f ) to the sequential displacement of the object stage ( ∆z ). After quantifying the characteristic sigmoidal monomer-to-polymer conversion of the various systems, with a combination of patterning experiments, FT-IR mapping, and modelling, we compute representative regimes for which z f is smaller, commensurate with, or larger than ∆z . While non-monotonic conversion can be detrimental to 3D printing, for instance in causing differential shrinkage of inhomogeneity in material properties, we identify opportunities for facile fabrication of modulated materials in the z -direction (i.e., along the illuminated axis). Our simple framework and model, based on directly measured parameters, can thus be employed in photopolymerisation-based 3D printing, both in process optimisation and in the precise design of complex, internally stratified materials by coupling the z -stage displacement and frontal polymerisation kinetics.

Frontal Conversion and Uniformity in 3D Printing by Photopolymerisation

Directory of Open Access Journals (Sweden)

Alessandra Vitale

2016-09-01

Full Text Available We investigate the impact of the non-uniform spatio-temporal conversion, intrinsic to photopolymerisation, in the context of light-driven 3D printing of polymers. The polymerisation kinetics of a series of model acrylate and thiol-ene systems, both neat and doped with a light-absorbing dye, is investigated experimentally and analysed according to a descriptive coarse-grained model for photopolymerisation. In particular, we focus on the relative kinetics of polymerisation with those of 3D printing, by comparing the evolution of the position of the conversion profile (zf to the sequential displacement of the object stage (∆z. After quantifying the characteristic sigmoidal monomer-to-polymer conversion of the various systems, with a combination of patterning experiments, FT-IR mapping, and modelling, we compute representative regimes for which zf is smaller, commensurate with, or larger than ∆z. While non-monotonic conversion can be detrimental to 3D printing, for instance in causing differential shrinkage of inhomogeneity in material properties, we identify opportunities for facile fabrication of modulated materials in the z-direction (i.e., along the illuminated axis. Our simple framework and model, based on directly measured parameters, can thus be employed in photopolymerisation-based 3D printing, both in process optimisation and in the precise design of complex, internally stratified materials by coupling the z-stage displacement and frontal polymerisation kinetics.

Conversion of methane to methanol in an ac dielectric barrier discharge

International Nuclear Information System (INIS)

Aghamir, F M; Matin, N S; Jalili, A H; Esfarayeni, M H; Khodagholi, M A; Ahmadi, R

2004-01-01

A dielectric barrier discharge (DBD) has been used to investigate the conversion of methane to methanol and higher hydrocarbons in ac non-equilibrium plasmas. Experiments were carried out at atmospheric pressure and ambient temperature. A non-equilibrium plasma was generated in a DBD reactor by applying a high voltage to the reactor electrodes. Activation of methane molecules led to the production of C 2 hydrocarbons and methanol. The effect of the applied voltage, residence time and feed mixture such as helium and oxygen on the methane conversion and product selectivity was studied. Helium appears to have no effect on the conversion and selectivity at our applied voltages. The methane conversion increases significantly on introduction of oxygen in the feed stream. Inclusion of oxygen leads to the formation of methanol. Our results show that production of methanol is initiated around an applied voltage of 12 kV and the conversion of methane increases with increasing voltage and residence time, while the product selectivity is independent of the applied voltage

Structure–kinetic relationship study of CDK8/CycC specific compounds

Science.gov (United States)

Schneider, Elisabeth V.; Böttcher, Jark; Huber, Robert; Maskos, Klaus; Neumann, Lars

2013-01-01

In contrast with the very well explored concept of structure–activity relationship, similar studies are missing for the dependency between binding kinetics and compound structure of a protein ligand complex, the structure–kinetic relationship. Here, we present a structure–kinetic relationship study of the cyclin-dependent kinase 8 (CDK8)/cyclin C (CycC) complex. The scaffold moiety of the compounds is anchored in the kinase deep pocket and extended with diverse functional groups toward the hinge region and the front pocket. These variations can cause the compounds to change from fast to slow binding kinetics, resulting in an improved residence time. The flip of the DFG motif (“DMG” in CDK8) to the inactive DFG-out conformation appears to have relatively little influence on the velocity of binding. Hydrogen bonding with the kinase hinge region contributes to the residence time but has less impact than hydrophobic complementarities within the kinase front pocket. PMID:23630251

Monte Carlo simulation on kinetics of batch and semi-batch free radical polymerization

KAUST Repository

Shao, Jing; Tang, Wei; Xia, Ru; Feng, Xiaoshuang; Chen, Peng; Qian, Jiasheng; Song, Changjiang

2015-01-01

experimental and simulation studies, we showed the capability of our Monte Carlo scheme on representing polymerization kinetics in batch and semi-batch processes. Various kinetics information, such as instant monomer conversion, molecular weight

Rational optimization of drug-target residence time: Insights from inhibitor binding to the S. aureus FabI enzyme-product complex

Science.gov (United States)

Chang, Andrew; Schiebel, Johannes; Yu, Weixuan; Bommineni, Gopal R.; Pan, Pan; Baxter, Michael V.; Khanna, Avinash; Sotriffer, Christoph A.; Kisker, Caroline; Tonge, Peter J.

2013-01-01

Drug-target kinetics has recently emerged as an especially important facet of the drug discovery process. In particular, prolonged drug-target residence times may confer enhanced efficacy and selectivity in the open in vivo system. However, the lack of accurate kinetic and structural data for series of congeneric compounds hinders the rational design of inhibitors with decreased off-rates. Therefore, we chose the Staphylococcus aureus enoyl-ACP reductase (saFabI) - an important target for the development of new anti-staphylococcal drugs - as a model system to rationalize and optimize the drug-target residence time on a structural basis. Using our new, efficient and widely applicable mechanistically informed kinetic approach, we obtained a full characterization of saFabI inhibition by a series of 20 diphenyl ethers complemented by a collection of 9 saFabI-inhibitor crystal structures. We identified a strong correlation between the affinities of the investigated saFabI diphenyl ether inhibitors and their corresponding residence times, which can be rationalized on a structural basis. Due to its favorable interactions with the enzyme, the residence time of our most potent compound exceeds 10 hours. In addition, we found that affinity and residence time in this system can be significantly enhanced by modifications predictable by a careful consideration of catalysis. Our study provides a blueprint for investigating and prolonging drug-target kinetics and may aid in the rational design of long-residence-time inhibitors targeting the essential saFabI enzyme. PMID:23697754

Automotive exhaust gas conversion: from elementary step kinetics to prediction of emission dynamics

NARCIS (Netherlands)

Hoebink, J.H.B.J.; Harmsen, J.M.A.; Balenovic, M.; Backx, A.C.P.M.; Schouten, J.C.

2001-01-01

Elementary step based kinetics show a high added value to describe the performance of catalytic exhaust gas converters under dynamic conditions, as demonstrated with a Euro test cycle. Combination of such kinetic models for individual global reactions covers the mutual interactions via common

Feedback-controlled electro-kinetic traps for single-molecule ...

Indian Academy of Sciences (India)

2014-01-11

Jan 11, 2014 ... limited residence time of a given molecule within the detection volume. A common ... information on individual folding pathways, as well as to the internal dynamics between ..... Essentials for building an electro-kinetic trap.

Energy conversion & storage program. 1995 annual report

Energy Technology Data Exchange (ETDEWEB)

Cairns, E.J.

1996-06-01

The 1995 annual report discusses laboratory activities in the Energy Conversion and Storage (EC&S) Program. The report is divided into three categories: electrochemistry, chemical applications, and material applications. Research performed in each category during 1995 is described. Specific research topics relate to the development of high-performance rechargeable batteries and fuel cells, the development of high-efficiency thermochemical processes for energy conversion, the characterization of new chemical processes and complex chemical species, and the study and application of novel materials related to energy conversion and transmission. Research projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials and deposition technologies, and advanced methods of analysis.

The eddy kinetic energy budget in the Red Sea

KAUST Repository

Zhan, Peng

2016-06-09

The budget of eddy kinetic energy (EKE) in the Red Sea, including the sources, redistributions and sink, is examined using a high-resolution eddy-resolving ocean circulation model. A pronounced seasonally varying EKE is identified, with its maximum intensity occurring in winter, and the strongest EKE is captured mainly in the central and northern basins within the upper 200 m. Eddies acquire kinetic energy from conversion of eddy available potential energy (EPE), from transfer of mean kinetic energy (MKE), and from direct generation due to time-varying (turbulent) wind stress, the first of which contributes predominantly to the majority of the EKE. The EPE-to-EKE conversion occurs almost in the entire basin, while the MKE-to-EKE transfer appears mainly along the shelf boundary of the basin (200 miso-bath) where high horizontal shear interacts with topography. The EKE generated by the turbulent wind stress is relatively small and limited to the southern basin. All these processes are intensified during winter, when the rate of energy conversion is about four to five times larger than that in summer. The EKE is redistributed by the vertical and horizontal divergence of energy flux and the advection of the mean flow. As a main sink of EKE, dissipation processes is ubiquitously found in the basin. The seasonal variability of these energy conversion terms can explain the significant seasonality of eddy activities in the Red Sea. This article is protected by copyright. All rights reserved.

Optical Energy Transfer and Conversion System

Science.gov (United States)

Hogan, Bartholomew P. (Inventor); Stone, William C. (Inventor)

2018-01-01

An optical energy transfer and conversion system comprising a fiber spooler and an electrical power extraction subsystem connected to the spooler with an optical waveguide. Optical energy is generated at and transferred from a base station through fiber wrapped around the spooler, and ultimately to the power extraction system at a remote mobility platform for conversion to another form of energy. The fiber spooler may reside on the remote mobility platform which may be a vehicle, or apparatus that is either self-propelled or is carried by a secondary mobility platform either on land, under the sea, in the air or in space.

Kinetics of the hydrogen production reaction in a copper-chlorine water splitting plant

International Nuclear Information System (INIS)

Zamfirescu, C.; Naterer, G.F.; Dincer, I.

2009-01-01

The exothermic reaction of HCl with particulate Cu occurs during hydrogen production step in the thermochemical copper-chlorine (Cu-Cl) water splitting cycle. In this paper, this chemical reaction is modeled kinetically, and a parametric study is performed to determine the influences of particle size, temperature and molar ratios on the reaction kinetics. It is determined that the residence time of copper particles varies between 10 and 100 s, depending on the operating conditions. The hydrogen conversion at equilibrium varies between 55 and 85%, depending on the reaction temperature. The heat flux at the particle surface, caused by the exothermic enthalpy of reaction, reaches about 3,000 W/m 2 when the particle shrinks to 0.1% from its initial size. A numerical algorithm is developed to solve the moving boundary Stefan problem with a chemical reaction. It predicts the shrinking of copper particles based on the hypothesis that the chemical reaction and heat transfer are decoupled. The model allows for estimation of the temperature of the copper particle, assumed spherical, in the radial direction. The maximum temperature at the interface is higher than the melting point of CuCl by 10-50 o C, depending on the assumed operating conditions. (author)

Biomass Conversion in Ionic Liquids - in-situ Investigations

DEFF Research Database (Denmark)

Kunov-Kruse, Andreas Jonas

Due to rising oil prices and global warming caused by CO2 emissions, there is an increased demand for new types of fuels and chemicals derived from biomass. This thesis investigates catalytic conversion of cellulose into sugars in ionic liquids and the important platform chemical 5-hydroxymethylf......Due to rising oil prices and global warming caused by CO2 emissions, there is an increased demand for new types of fuels and chemicals derived from biomass. This thesis investigates catalytic conversion of cellulose into sugars in ionic liquids and the important platform chemical 5......-hydroxymethylfurfural (HMF). The thesis focuses on kinetic and mechanistic investigations using new in-situ FTIR spectroscopic methods based on the ATR-principle. At first the kinetics of cellulose hydrolysis and the simultaneously HMF formation was investigated in the ionic liquid 1-butyl-2,3-dimethylimidazolium...... activation energies suggest that the ionic liquid acts co-catalytic by stabilizing the oxocarbenium transition state. The chromium catalyzed conversion of glucose to HMF in ionic liquid 1-butyl-3-methylimidazolium chloride with CrCl3⋅6H2O and CrCl2 as catalysts was investigated. The CrCl3⋅6H2O catalyst...

Laser-accelerated proton conversion efficiency thickness scaling

International Nuclear Information System (INIS)

Hey, D. S.; Foord, M. E.; Key, M. H.; LePape, S. L.; Mackinnon, A. J.; Patel, P. K.; Ping, Y.; Akli, K. U.; Stephens, R. B.; Bartal, T.; Beg, F. N.; Fedosejevs, R.; Friesen, H.; Tiedje, H. F.; Tsui, Y. Y.

2009-01-01

The conversion efficiency from laser energy into proton kinetic energy is measured with the 0.6 ps, 9x10 19 W/cm 2 Titan laser at the Jupiter Laser Facility as a function of target thickness in Au foils. For targets thicker than 20 μm, the conversion efficiency scales approximately as 1/L, where L is the target thickness. This is explained by the domination of hot electron collisional losses over adiabatic cooling. In thinner targets, the two effects become comparable, causing the conversion efficiency to scale weaker than 1/L; the measured conversion efficiency is constant within the scatter in the data for targets between 5 and 15 μm, with a peak conversion efficiency of 4% into protons with energy greater than 3 MeV. Depletion of the hydrocarbon contaminant layer is eliminated as an explanation for this plateau by using targets coated with 200 nm of ErH 3 on the rear surface. The proton acceleration is modeled with the hybrid-particle in cell code LSP, which reproduced the conversion efficiency scaling observed in the data.

The physical kinetics of magnetoplasticity of diamagnetic crystals

International Nuclear Information System (INIS)

Buchachenko, A. L.

2007-01-01

The kinetic equations describing the rate of magnetically induced release of dislocations entrapped by stoppers were solved. The magnetic field effect on the mobility of dislocations was calculated. Its comparison with experiment gave the ratio between the rate constants for two key processes governing magnetoplasticity, namely, singlet-triplet conversion in a spin nanoreactor and the release of a dislocation from it. The kinetic criterion of the existence of magnetoplasticity as a physical phenomenon was obtained

Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol

Directory of Open Access Journals (Sweden)

Gupta Rishi

2012-03-01

Full Text Available Abstract Background Enzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified Prosopis juliflora, using a fed-batch enzymatic hydrolysis approach. Results The enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with Saccharomyces cerevisiae and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time. Conclusion Fed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates.

Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol

Science.gov (United States)

2012-01-01

Background Enzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified Prosopis juliflora, using a fed-batch enzymatic hydrolysis approach. Results The enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v) and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with Saccharomyces cerevisiae and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time. Conclusion Fed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates. PMID:22433563

Innovative practice: Conversational use of English in bilingual adults with dementia.

Science.gov (United States)

Kokorelias, Kristina M; Ryan, Ellen B; Elliot, Gail

2017-02-01

Regression to mother tongue is common in those with dementia. In two long-term care facilities, we explored the use of bilinguals' two languages for five older adults with mild-moderate dementia who have begun to regress to Greek. We also examined the role of Montessori DementiAbility Methods: The Montessori Way-based English language activities in fostering conversational use of English. Over 10 sessions, participants' vocabulary or grammatical structure in English did not improve. However, four of the five participants were able to maintain a conversation in English for longer periods of time. This study contributes to strategies for optimizing meaningful conversation for bilingual long-term care residents with dementia. Moreover, the data suggest a change in the policy and practice for dementia care so that there are more opportunities for residents to speak English in non-English mother-tongue facilities. Greater attention to the specific language needs of bilinguals in English-dominant settings would also be advisable.

Raindrop Kinetic Energy Piezoelectric Harvesters and Relevant Interface Circuits: Review, Issues and Outlooks

Directory of Open Access Journals (Sweden)

Kok Gnee CHUA

2016-05-01

Full Text Available As an ecological source of renewable energy, the available kinetic energy of rainfall is not trifling, especially in tropical countries at the equators. The research on the use of piezoelectric transducer to harvest raindrop kinetic energy is gaining more and more attention recently. This article reviews the state-of-the-art energy harvesting technology from the conversion of raindrop kinetic energy using piezoelectric transducers as well as its interface circuits for vibration-based energy harvesters. Performance of different types of piezoelectric harvesters in terms of power output, area power density and energy conversion efficiency are compared. Summaries of key problems and suggestions on the optimization of the performance of the piezoelectric harvesters are also provided for future works.

Gene conversion and reversion events in Saccharomyces cerevisiae. Model for study of gamma radiation damage

International Nuclear Information System (INIS)

Moreno, Damaris; Fuentes, Jorge L.; Prieto Miranda, Enrique F.; Sanchez Lamar, Angel; Baluja, Ligia

2004-01-01

Radiosensitivity and kinetics of induction of gene conversion and reversion events in Saccharomyces cerevisiae strain D7 to gamma radiation at dose ranges from 100 to 800 Gy and 50 to 300 Gy respectively were studied. A source of 60Co PX- -30 at a dose rate of 49,43 GY/min was utilized. The cell survival curve showed DL50 of 150 Gy. Cell death kinetics was linear and adjusted over 98 %. The induction of gene conversion events was significant in relation to control from 50 Gy on. However, gene reversion was significant only at 200 Gy. Generally speaking, gene conversion event frequencies were higher than those of reversion, which indicates that gamma radiation preferably induces recombinogenic events. Both the conversion and reversion events showed exponential dependence on gamma radiation dose. The relative benefits of this test for mutagenesis and anti-mutagenesis studies were debated in this paper

A resource facility for kinetic analysis: modeling using the SAAM computer programs.

Science.gov (United States)

Foster, D M; Boston, R C; Jacquez, J A; Zech, L

1989-01-01

Kinetic analysis and integrated system modeling have contributed significantly to understanding the physiology and pathophysiology of metabolic systems in humans and animals. Many experimental biologists are aware of the usefulness of these techniques and recognize that kinetic modeling requires special expertise. The Resource Facility for Kinetic Analysis (RFKA) provides this expertise through: (1) development and application of modeling technology for biomedical problems, and (2) development of computer-based kinetic modeling methodologies concentrating on the computer program Simulation, Analysis, and Modeling (SAAM) and its conversational version, CONversational SAAM (CONSAM). The RFKA offers consultation to the biomedical community in the use of modeling to analyze kinetic data and trains individuals in using this technology for biomedical research. Early versions of SAAM were widely applied in solving dosimetry problems; many users, however, are not familiar with recent improvements to the software. The purpose of this paper is to acquaint biomedical researchers in the dosimetry field with RFKA, which, together with the joint National Cancer Institute-National Heart, Lung and Blood Institute project, is overseeing SAAM development and applications. In addition, RFKA provides many service activities to the SAAM user community that are relevant to solving dosimetry problems.

Dispersive kinetic model for the non-isothermal reduction of nickel oxide by hydrogen

International Nuclear Information System (INIS)

Adnadevic, Borivoj; Jankovic, Bojan

2008-01-01

The kinetics of the non-isothermal reduction process of powder nickel oxide samples using hydrogen was investigated by temperature-programmed experiments at the different constant heating rates. The new procedure for the determination of density distribution function of activation energies (ddfE a ), evaluated from the experimentally obtained non-isothermal conversion curves, was developed. The analytical relationships between the corresponding thermo-kinetic parameters for the investigated reduction process were established. From the influence of heating rate on the basic characteristics of ddfE a 's, it was concluded that the evaluated ddfE a 's are completely independent of the heating rate (v h ). It was found that the value of activation energy at the peak of the distribution curve (E a,max ), at all considered heating rates, is in good agreement with the value of E a,0 (96.6 kJ mol -1 ) calculated from the isoconversional dependence of activation energy, in the conversion range of 0.20≤α≤0.60. From the appearances of the true compensation effect, it was concluded that the factor that produces the changes of kinetic parameter values is a conversion fraction (α). Using the model prediction, the experimentally obtained conversion curves are completely described by the evaluated distribution curves (g(E a ) vhj ) at all considered heating rates. It was concluded that the assumption about the distribution of potential energies of oxygen vacancies presented in NiO samples leads to the distribution of activation energies, which determine the kinetics of non-isothermal reduction processes

Conversion of glucose into 5-hydroxymethylfurfural in different solvents and catalysts: Reaction kinetics and mechanism

Directory of Open Access Journals (Sweden)

Cunshan Zhou

2017-06-01

Full Text Available Synthesis of 5-hydroxymethylfurfural (HMF from glucose was done in H2O, dimethylsulfoxide (DMSO and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl catalyzed by metal (III chloride (FeCl3·6H2O, CrCl3·6H2O and AlCl3. The effects of solvent/catalyst system and temperature/time on the performance of the reaction are studied. HMF yield in the different solvents follows a decreasing order as DMSO > [Bmim]Cl > H2O. The highest HMF yield is achieved by CrCl3·6H2O, followed by AlCl3 and then FeCl3·6H2O. An optimal temperature/time is found at 393 K or 403 K and a time between 30 min and 480 min. Under the optimal reaction conditions, HMF yields of 54.43% and 52.86% are obtained in DMSO with CrCl3·6H2O at 403 K and 480 min and AlCl3 at 393 K and 240 min, respectively. The mechanism of the halide chlorides catalyzed glucose conversion reaction is proposed. The kinetic model is established to describe the HMF formation and the experimental data conform to the model.

Recent results in muonium solution kinetics

International Nuclear Information System (INIS)

Jean, Y.C.; Ito, Y.; Stadlbauer, J.M.; Ng, B.W.; Walker, D.C.

1983-06-01

Using muonium spin rotation (MSR) techniques the aqueous solution kinetics of several muonium addition reactions and spin conversion interactions have been studied. The addition reactions show both diffusion and activation-controlled reaction rates with isotope effects between 1 and 3 for diffusion-control and between 7 and 31 for activation-control reactions. Barrier energies are typically approximately 15 kJ/mole and approximately 30 kJ/mole, respectively, for these processes in water. Spin-conversion interactions involving Ni +2 (aq) and Ni(cyclam) +2 complexes showed that spin-conversion of 'triplet' Mu by a paramagnetic solute occurs at or near the diffusion-controlled limit while the chemical reaction with the diamagnetic configuration of Ni(cyclam) +2 occurred some 100 times slower at ksub(M) 18 M -1 s -1

Kinetic Modeling of a Heterogeneous Fenton Oxidative Treatment of Petroleum Refining Wastewater

Science.gov (United States)

Basheer Hasan, Diya'uddeen; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

2014-01-01

The mineralisation kinetics of petroleum refinery effluent (PRE) by Fenton oxidation were evaluated. Within the ambit of the experimental data generated, first-order kinetic model (FKM), generalised lumped kinetic model (GLKM), and generalized kinetic model (GKM) were tested. The obtained apparent kinetic rate constants for the initial oxidation step (k 2′), their final oxidation step (k 1′), and the direct conversion to endproducts step (k 3′) were 10.12, 3.78, and 0.24 min−1 for GKM; 0.98, 0.98, and nil min−1 for GLKM; and nil, nil, and >0.005 min−1 for FKM. The findings showed that GKM is superior in estimating the mineralization kinetics. PMID:24592152

Initial kinetics of the direct sulfation of limestone

DEFF Research Database (Denmark)

Hu, Guilin; Shang, Lei; Dam-Johansen, Kim

2008-01-01

The initial kinetics of direct sulfation of Faxe Bryozo, a porous bryozoan limestone was studied in the temperature interval from 873 to 973 K in a pilot entrained flow reactor with very short reaction times (between 0.1 and 0.6 s). The initial conversion rate of the limestone - for conversions...... less than 0.3% - was observed to be significantly promoted by higher SO2 concentrations and lower CO2 concentrations, whereas 02 showed negligible influence. A mathematical model for the sulfation of limestone involving chemical reaction at calcite grain surfaces and solid-state diffusion of carbonate...... ions in calcite grains is established. The validity of the model is limited to the initial sulfation period, in which nucleation of the solid product calcium sulphate is not started. This theoretical reaction-diffusion model gives a good simulation of the initial kinetics of the direct sulfation...

Kinetic modeling of ethylbenzene dehydrogenation over hydrotalcite catalysts

KAUST Repository

Atanda, Luqman

2011-07-01

Kinetics of ethylbenzene dehydrogenation to styrene was investigated over a series of quaternary mixed oxides of Mg3Fe0.25Me0.25Al0.5 (Me=Co, Mn and Ni) catalysts prepared by calcination of hydrotalcite-like compounds and compared with commercial catalyst. The study was carried out in the absence of steam using a riser simulator at 400, 450, 500 and 550°C for reaction times of 5, 10, 15 and 20s. Mg3Fe0.25Mn0.25Al0.5 afforded the highest ethylbenzene conversion of 19.7% at 550°C. Kinetic parameters for the dehydrogenation process were determined using the catalyst deactivation function based on reactant conversion model. The apparent activation energies for styrene production were found to decrease as follows: E1-Ni>E1-Co>E1-Mn. © 2011 Elsevier B.V.

Kinetics of the generation of the petroleum: Principles and application in the Colombian basins

International Nuclear Information System (INIS)

Goncalves, F T T; Garcia, D F; Penteado, H L B; Giraldo, B N; Bedregal, R P; Gomez

2001-01-01

Most of the mathematical models that describe the conversion of kerogen into petroleum are based on the formulations of first-order kinetics. Although the application of such models requires the knowledge of the kinetic parameters (activation energies and frequency factor) of the kerogen, the usual practice in basin modeling studies is to use kinetic data of standard kerogen types (I, II or III) when measured data are not available. In this study, Rock-Eval pyrolysis under different heating rates and numerical optimization techniques were used to determine the kinetic parameters of cretaceous and tertiary source rocks of the upper Magdalena and llanos basins. The obtained kinetic parameters revealed a significant variability, which appears to be unrelated to the kerogen type classification based on hydrogen and oxygen indices. Modeling exercises under a constant heating rate (1.25 degrades C/M.y., 274.5K/M.y.) using the measured kinetic data indicates that kerogen conversion of organic facies with distinct kinetic parameters may be out of phase by 20-30M.y. therefore, petroleum generation and expulsion history might be longer and more complex than if the kinetic behavior of these rocks was considered homogeneous. These differences are critical in defining the timing between petroleum generations a trap formation/destruction, particularly in the case of the Colombian sedimentary basins, characterized by a highly complex tectonic evolution

Infrared studies of ortho-para conversion at Cl-atom and H-atom impurity centers in cryogenic solid hydrogen

International Nuclear Information System (INIS)

Raston, P.L.; Kettwich, S.C.; Anderson, D.T.

2010-01-01

We report infrared spectroscopic studies of H 2 ortho-para (o/p) conversion in solid hydrogen doped with Cl-atoms at 2 K while the Cl + H 2 (υ = 1) → HCl + H infrared-induced chemical reaction is occurring. The Cl-atom doped hydrogen crystals are synthesized using 355 nm in situ photodissociation of Cl 2 precursor molecules. For hydrogen solids with high ortho-H 2 fractional concentrations (X o = 0.55), the o/p conversion kinetics is dominated by Cl-atom catalyzed conversion with a catalyzed conversion rate constant K cc = 1.16(11) min -1 and the process is rate-limited by ortho-H 2 quantum diffusion. For hydrogen crystals with low ortho-H2 concentrations (X o = 0.03), single-exponential decay of the ortho-H 2 concentration with time is observed which is attributed to H-atom catalyzed o/p conversion by the H-atoms produced during the infrared-induced Cl + H 2 reaction. The measured H-atom catalyzed o/p conversion kinetics indicates the H-atoms are mobile under these conditions in agreement with previous ESR measurements.

Qualitative study about the ways teachers react to feedback from resident evaluations.

Science.gov (United States)

van Roermund, Thea; Schreurs, Marie-Louise; Mokkink, Henk; Bottema, Ben; Scherpbier, Albert; van Weel, Chris

2013-07-16

Currently, one of the main interventions that are widely expected to contribute to teachers' professional development is confronting teachers with feedback from resident evaluations of their teaching performance. Receiving feedback, however, is a double edged sword. Teachers see themselves confronted with information about themselves and are, at the same time, expected to be role models in the way they respond to feedback. Knowledge about the teachers' responses could be not only of benefit for their professional development, but also for supporting their role modeling. Therefore, research about professional development should include the way teachers respond to feedback. We designed a qualitative study with semi-structured individual conversations about feedback reports, gained from resident evaluations. Two researchers carried out a systematic analysis using qualitative research software. The analysis focused on what happened in the conversations and structured the data in three main themes: conversation process, acceptance and coping strategies. The result section describes the conversation patterns and atmosphere. Teachers accepted their results calmly, stating that, although they recognised some points of interest, they could not meet with every standard. Most used coping strategies were explaining the results from their personal beliefs about good teaching and attributing poor results to external factors and good results to themselves. However, some teachers admitted that they had poor results because of the fact that they were not "sharp enough" in their resident group, implying that they did not do their best. Our study not only confirms that the effects of feedback depend first and foremost on the recipient but also enlightens the meaning and role of acceptance and being a role model. We think that the results justify the conclusion that teachers who are responsible for the day release programmes in the three departments tend to respond to the evaluation

Inter-machine comparison of the termination phase and energy conversion in tokamak disruptions with runaway current plateau formation and implications for ITER

International Nuclear Information System (INIS)

Martín-Solís, J.R.; Loarte, A.; Hollmann, E.M.; Esposito, B.; Riccardo, V.

2014-01-01

The termination of the current and the loss of runaway electrons following runaway current plateau formation during disruptions have been investigated in the JET, DIII-D and FTU tokamaks. Substantial conversion of magnetic energy into runaway kinetic energy, up to ∼10 times the initial plateau runaway kinetic energy, has been inferred for the slowest current terminations. Both modelling and experiment suggest that, in present devices, the efficiency of conversion into runaway kinetic energy is determined to a great extent by the characteristic runaway loss time, τ diff , and the resistive time of the residual ohmic plasma after the disruption, τ res , increasing with the ratio τ diff /τ res . It is predicted that, in large future devices such as ITER, the generation of runaways by the avalanche mechanism will play an important role, particularly for slow runaway discharge terminations, increasing substantially the amount of energy deposited by the runaways onto the plasma-facing components by the conversion of magnetic energy of the runaway plasma into runaway kinetic energy. Estimates of the power fluxes on the beryllium plasma-facing components during runaway termination in ITER indicate that for runaway currents of up to 2 MA no melting of the components is expected. For larger runaway currents, minimization of the effects of runaway impact on the first wall requires a reduction in the kinetic energy of the runaway beam before termination and, in addition, high plasma density n e and low ohmic plasma resistance (long τ res ) to prevent large conversion of magnetic into runaway kinetic energy during slow current terminations. (paper)

Conversion of Cassava Starch to Produce Glucose and Fructose by Enzymatic Process Using Microwave Heating

Directory of Open Access Journals (Sweden)

Sumardiono Siswo

2018-01-01

Full Text Available In this study, variation of glycosidase enzyme concentration and saccharification time on enzymatic hydrolysis using microwave have been investigated. Concentration and kinetic parameters rate of glucose and fructose were analyzed. Cassava starch was liquefied and gelatinized by microwave at 80°C. The gelatinized starch was saccharified at 60°C using (0.2;0.4;0.6;0.8;1% (w/v glycosidase enzyme for 24, 48 and 72 hours. The glucose which has been saccharified with 1% glycosidase enzyme for 72 hours gave highest conversion 66.23 %. The optimization process by multilevel reaction gave the highest conversion at enzyme concentrations 0.88 %and saccharification time 29 hours that 68.82%. The highest conversion of glucose was isomerized to fructose. The fructose which has been isomerized for 180 minutes gave highest conversion 20.05 %. The kinetics enzymatic reaction was approached and determined by Michaelis - Menten equation, Km and Vmax of reaction for glucose 22.94 g/L; 2.70 g/L hours and for fructose 3.39 g/L; 0.38 g/L. min respectively.

A kinetic model for the first stage of pygas upgrading

Directory of Open Access Journals (Sweden)

J. L. de Medeiros

2007-03-01

Full Text Available Pyrolysis gasoline - PYGAS - is an intermediate boiling product of naphtha steam cracking with a high octane number and high aromatic/unsaturated contents. Due to stabilization concerns, PYGAS must be hydrotreated in two stages. The first stage uses a mild trickle-bed conversion for removing extremely reactive species (styrene, dienes and olefins prior to the more severe second stage where sulfured and remaining olefins are hydrogenated in gas phase. This work addresses the reaction network and two-phase kinetic model for the first stage of PYGAS upgrading. Nonlinear estimation was used for model tuning with kinetic data obtained in bench-scale trickle-bed hydrogenation with a commercial Pd/Al2O3 catalyst. On-line sampling experiments were designed to study the influence of variables - temperature and spatial velocity - on the conversion of styrene, dienes and olefins.

Social worker assessment of bad news delivery by emergency medicine residents: a novel direct-observation milestone assessment.

Science.gov (United States)

Min, Alice Ann; Spear-Ellinwood, Karen; Berman, Melissa; Nisson, Peyton; Rhodes, Suzanne Michelle

2016-09-01

The skill of delivering bad news is difficult to teach and evaluate. Residents may practice in simulated settings; however, this may not translate to confidence or competence during real experiences. We investigated the acceptability and feasibility of social workers as evaluators of residents' delivery of bad news during patient encounters, and assessed the attitudes of both groups regarding this process. From August 2013 to June 2014, emergency medicine residents completed self-assessments after delivering bad news. Social workers completed evaluations after observing these conversations. The Assessment tools were designed by modifying the global Breaking Bad News Assessment Scale. Residents and social workers completed post-study surveys. 37 evaluations were received, 20 completed by social workers and 17 resident self-evaluations. Social workers reported discussing plans with residents prior to conversations 90 % of the time (18/20, 95 % CI 64.5, 97.8). Social workers who had previously observed the resident delivering bad news reported that the resident was more skilled on subsequent encounters 90 % of the time (95 % CI 42.2, 99). Both social workers and residents felt that prior training or experience was important. First-year residents valued advice from social workers less than advice from attending physicians, whereas more experienced residents perceived advice from social workers to be equivalent with that of attending physicians (40 versus 2.9 %, p = 0.002). Social worker assessment of residents' abilities to deliver bad news is feasible and acceptable to both groups. This formalized self-assessment and evaluation process highlights the importance of social workers' involvement in delivery of bad news, and the teaching of this skill. This method may also be used as direct-observation for resident milestone assessment.

Discussion of the Investigation Method on the Reaction Kinetics of Metallurgical Reaction Engineering

Science.gov (United States)

Du, Ruiling; Wu, Keng; Zhang, Jiazhi; Zhao, Yong

Reaction kinetics of metallurgical physical chemistry which was successfully applied in metallurgy (as ferrous metallurgy, non-ferrous metallurgy) became an important theoretical foundation for subject system of traditional metallurgy. Not only the research methods were very perfect, but also the independent structures and systems of it had been formed. One of the important tasks of metallurgical reaction engineering was the simulation of metallurgical process. And then, the mechanism of reaction process and the conversion time points of different control links should be obtained accurately. Therefore, the research methods and results of reaction kinetics in metallurgical physical chemistry were not very suitable for metallurgical reaction engineering. In order to provide the definite conditions of transmission, reaction kinetics parameters and the conversion time points of different control links for solving the transmission and reaction equations in metallurgical reaction engineering, a new method for researching kinetics mechanisms in metallurgical reaction engineering was proposed, which was named stepwise attempt method. Then the comparison of results between the two methods and the further development of stepwise attempt method were discussed in this paper. As a new research method for reaction kinetics in metallurgical reaction engineering, stepwise attempt method could not only satisfy the development of metallurgical reaction engineering, but also provide necessary guarantees for establishing its independent subject system.

Energy Conversion and Storage Program

Energy Technology Data Exchange (ETDEWEB)

Cairns, E.J.

1992-03-01

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Advance care planning for nursing home residents with dementia: policy vs. practice.

Science.gov (United States)

Ampe, Sophie; Sevenants, Aline; Smets, Tinne; Declercq, Anja; Van Audenhove, Chantal

2016-03-01

The aims of this study were: to evaluate the advance care planning policy for people with dementia in nursing homes; to gain insight in the involvement of residents with dementia and their families in advance care planning, and in the relationship between the policy and the actual practice of advance care planning. Through advance care planning, nursing home residents with dementia are involved in care decisions, anticipating their reduced decision-making capacity. However, advance care planning is rarely realized for this group. Prevalence and outcomes have been researched, but hardly any research has focused on the involvement of residents/families in advance care planning. Observational cross-sectional study in 20 nursing homes. The ACP audit assessed the views of the nursing homes' staff on the advance care planning policy. In addition, individual conversations were analysed with 'ACP criteria' (realization of advance care planning) and the 'OPTION' instrument (involvement of residents/families). June 2013-September 2013. Nursing homes generally met three quarters of the pre-defined criteria for advance care planning policy. In almost half of the conversations, advance care planning was explained and discussed substantively. Generally, healthcare professionals only managed to involve residents/families on a baseline skill level. There were no statistically significant correlations between policy and practice. The evaluations of the policy were promising, but the actual practice needs improvement. Future assessment of both policy and practice is recommended. Further research should focus on communication interventions for implementing advance care planning in the daily practice. © 2015 John Wiley & Sons Ltd.

Turbostar: an ICF reactor using both direct and thermal power conversion. Revision 1

International Nuclear Information System (INIS)

Pitts, J.H.

1986-01-01

Combining direct and thermal power conversion results in a 52% gross plant efficiency with DT fuel and 68% with advanced DD fuel. We maximize the fraction of fusion-yield energy converted to kinetic energy in a liquid-lithium blanket, and use this energy directly with turbine generators to produce electricity. We use the remainder of the energy to produce electricity in a standard Rankine thermal power conversion cycle

Straw - H{sub 2}O gasification kinetics. Determination and discussion

Energy Technology Data Exchange (ETDEWEB)

Holst Soerensen, L.; Tarp Poulsen, K. [ReaTech, Roskilde (Denmark); Henriksen, U. [The Technical Univ., Dept. of Energy Engineering, Lyngby (Denmark); Risnes, H. [NTNU, Dept. of Thermal Energy and Hydropower, Trondheim (Norway); Hansen, L.K. [FLS Miljoe A/S, Valby (Denmark); Olsen, A.; Rathmann, O. [Risoe National Lab., Roskilde (Denmark)

1999-11-01

Preliminary steam reactivity data is presented from an experimental study of reactivity for wheat and barley char. The parameters currently investigated ranges from 0.15-1.5 bar H{sub 2}O and 0-1.0 bar H{sub 2}. Kinetics of the Langmuir-Hinshelwood type is used to discuss the reactivity variations with steam partial pressure and also the effects of adding hydrogen. The reactivity of char from wheat and washed barley was low and significantly decreasing with conversion. A significant increasing reactivity with conversion was observed for the char derived from a barley sample and a barley sample six times enriched by the water-soluble parts from the straw sample. The six times enriched barley was roughly six times as reactive as the barley. For wheat significant inhibiting effect from hydrogen was found. Assuming Langmuir Hinshelwood kinetics with reverse oxygen exchange and structural profile invariance, kinetics for the inhibiting reaction by H{sub 2} were estimated. 0.5 and 1 bar H{sub 2} decreased the reactivity roughly by one order of magnitude in 1.5 bar H{sub 2}O. (au) EFP-96. 17 refs.

Oral and maxillofacial surgery residents have poor understanding of biostatistics.

Science.gov (United States)

Best, Al M; Laskin, Daniel M

2013-01-01

The purpose of this study was to evaluate residents' understanding of biostatistics and interpretation of research results. A questionnaire previously used in internal medicine residents was modified to include oral and maxillofacial surgery (OMS) examples. The survey included sections to identify demographic and educational characteristics of residents, attitudes and confidence, and the primary outcome-knowledge of biostatistics. In 2009 an invitation to the Internet survey was sent to all 106 program directors in the United States, who were requested to forward it to their residents. One hundred twelve residents responded. The percentage of residents who had taken a course in epidemiology was 53%; biostatistics, 49%; and evidence-based dentistry, 65%. Conversely, 10% of OMS residents had taken none of these classes. Across the 6-item test of knowledge of statistical methods, the mean percentage of correct answers was 38% (SD, 22%). Nearly half of the residents (42%) could not correctly identify continuous, ordinal, or nominal variables. Only 21% correctly identified a case-control study, but 79% correctly identified that the purpose of blinding was to reduce bias. Only 46% correctly interpreted a clinically unimportant and statistically nonsignificant result. None of the demographic or experience factors of OMS residents were related to statistical knowledge. Overall, OMS resident knowledge was below that of internal medicine residents (Pbiostatistics and the interpretation of research and are thus unprepared to interpret the results of published clinical research. Residency programs should include effective biostatistical training in their curricula to prepare residents in evidence-based dentistry. Copyright © 2013 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

A new kinetic biphasic approach applied to biodiesel process intensification

Energy Technology Data Exchange (ETDEWEB)

Russo, V.; Tesser, R.; Di Serio, M.; Santacesaria, E. [Naples Univ. (Italy). Dept. of Chemistry

2012-07-01

Many different papers have been published on the kinetics of the transesterification of vegetable oil with methanol, in the presence of alkaline catalysts to produce biodiesel. All the proposed approaches are based on the assumption of a pseudo-monophasic system. The consequence of these approaches is that some experimental aspects cannot be described. For the reaction performed in batch conditions, for example, the monophasic approach is not able to reproduce the different plateau obtained by using different amount of catalyst or the induction time observed at low stirring rates. Moreover, it has been observed by operating in continuous reactors that micromixing has a dramatic effect on the reaction rate. At this purpose, we have recently observed that is possible to obtain a complete conversion to biodiesel in less than 10 seconds of reaction time. This observation is confirmed also by other authors using different types of reactors like: static mixers, micro-reactors, oscillatory flow reactors, cavitational reactors, microwave reactors or centrifugal contactors. In this work we will show that a recently proposed biphasic kinetic approach is able to describe all the aspects before mentioned that cannot be described by the monophasic kinetic model. In particular, we will show that the biphasic kinetic model can describe both the induction time observed in the batch reactors, at low stirring rate, and the very high conversions obtainable in a micro-channel reactor. The adopted biphasic kinetic model is based on a reliable reaction mechanism that will be validated by the experimental evidences reported in this work. (orig.)

Reexamining Michaelis-Menten Enzyme Kinetics for Xanthine Oxidase

Science.gov (United States)

Bassingthwaighte, James B.; Chinn, Tamara M.

2013-01-01

Abbreviated expressions for enzyme kinetic expressions, such as the Michaelis-Menten (M-M) equations, are based on the premise that enzyme concentrations are low compared with those of the substrate and product. When one does progress experiments, where the solute is consumed during conversion to form a series of products, the idealized conditions…

Kinetic concepts of thermally stimulated reactions in solids

Science.gov (United States)

Vyazovkin, Sergey

Historical analysis suggests that the basic kinetic concepts of reactions in solids were inherited from homogeneous kinetics. These concepts rest upon the assumption of a single-step reaction that disagrees with the multiple-step nature of solid-state processes. The inadequate concepts inspire such unjustified anticipations of kinetic analysis as evaluating constant activation energy and/or deriving a single-step reaction mechanism for the overall process. A more adequate concept is that of the effective activation energy, which may vary with temperature and extent of conversion. The adequacy of this concept is illustrated by literature data as well as by experimental data on the thermal dehydration of calcium oxalate monohydrate and thermal decomposition of calcium carbonate, ammonium nitrate and 1,3,5,7- tetranitro-1,3,5,7-tetrazocine.

Kinetic and thermodynamic analysis of the polymerization of polyurethanes by a rheological method

International Nuclear Information System (INIS)

Lucio, Beatriz; Fuente, José Luis de la

2016-01-01

Graphical abstract: - Highlights: • Kinetic and thermodynamic analysis for the formation of a functional polyurethane (PU) has been carried out. • Rheological parameters were used to obtain the profile of the resin's curing degree. • Kamal-Sourour autocatalytic kinetic model describes well this polyaddition reaction. • A deeper understanding of the mechanism of PU systems has been achieved. • This metallo-PU finds its application in the chemistry of advanced energetic materials. - Abstract: As part of an investigation into the mechanism and chemorheology of linear segmented polyurethane (PU) systems, this paper presents the kinetic and thermodynamic characterization of the reaction between an advanced functional metallo-polyol derivative of hydroxyl-terminated polybutadiene (HTPB), (ferrocenylbutyl)dimethylsilane grafted HTPB, and isophorone diisocyanate (IPDI). The evolution of viscoelastic properties, such as the storage modulus (G′), was recorded in bulk under isothermal conditions at four different temperatures between 50 and 80 °C, and a resin curing degree profile was obtained for this elastic modulus. The use of the Kamal-Sourour autocatalytic kinetic model was proposed, describing the overall curing process perfectly. All the kinetic and thermodynamic parameters, including reaction orders, kinetic constants and activation energy, were determined for the polyaddition reaction under study. A relevant autocatalysis effect, promoted by the urethane group, has been found. The isoconversion method was also used to analyze the variation of the global activation energy with conversion. The global activation energy increases slightly as the curing reaction proceeds with a maximum value reached at approximately 30% conversion. In addition, the Eyring parameters were calculated from the obtained kinetic data.

Kinetic and thermodynamic analysis of the polymerization of polyurethanes by a rheological method

Energy Technology Data Exchange (ETDEWEB)

Lucio, Beatriz; Fuente, José Luis de la, E-mail: fuentegj@inta.es

2016-02-10

Graphical abstract: - Highlights: • Kinetic and thermodynamic analysis for the formation of a functional polyurethane (PU) has been carried out. • Rheological parameters were used to obtain the profile of the resin's curing degree. • Kamal-Sourour autocatalytic kinetic model describes well this polyaddition reaction. • A deeper understanding of the mechanism of PU systems has been achieved. • This metallo-PU finds its application in the chemistry of advanced energetic materials. - Abstract: As part of an investigation into the mechanism and chemorheology of linear segmented polyurethane (PU) systems, this paper presents the kinetic and thermodynamic characterization of the reaction between an advanced functional metallo-polyol derivative of hydroxyl-terminated polybutadiene (HTPB), (ferrocenylbutyl)dimethylsilane grafted HTPB, and isophorone diisocyanate (IPDI). The evolution of viscoelastic properties, such as the storage modulus (G′), was recorded in bulk under isothermal conditions at four different temperatures between 50 and 80 °C, and a resin curing degree profile was obtained for this elastic modulus. The use of the Kamal-Sourour autocatalytic kinetic model was proposed, describing the overall curing process perfectly. All the kinetic and thermodynamic parameters, including reaction orders, kinetic constants and activation energy, were determined for the polyaddition reaction under study. A relevant autocatalysis effect, promoted by the urethane group, has been found. The isoconversion method was also used to analyze the variation of the global activation energy with conversion. The global activation energy increases slightly as the curing reaction proceeds with a maximum value reached at approximately 30% conversion. In addition, the Eyring parameters were calculated from the obtained kinetic data.

Biomass Thermochemical Conversion Program. 1984 annual report

Energy Technology Data Exchange (ETDEWEB)

Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

1985-01-01

The objective of the program is to generate scientific data and conversion process information that will lead to establishment of cost-effective process for converting biomass resources into clean fuels. The goal of the program is to develop the data base for biomass thermal conversion by investigating the fundamental aspects of conversion technologies and by exploring those parameters that are critical to the conversion processes. The research activities can be divided into: (1) gasification technology; (2) liquid fuels technology; (3) direct combustion technology; and (4) program support activities. These activities are described in detail in this report. Outstanding accomplishments during fiscal year 1984 include: (1) successful operation of 3-MW combustor/gas turbine system; (2) successful extended term operation of an indirectly heated, dual bed gasifier for producing medium-Btu gas; (3) determination that oxygen requirements for medium-Btu gasification of biomass in a pressurized, fluidized bed gasifier are low; (4) established interdependence of temperature and residence times on biomass pyrolysis oil yields; and (5) determination of preliminary technical feasibility of thermally gasifying high moisture biomass feedstocks. A bibliography of 1984 publications is included. 26 figs., 1 tab.

Monte Carlo simulation on kinetics of batch and semi-batch free radical polymerization

KAUST Repository

Shao, Jing

2015-10-27

Based on Monte Carlo simulation technology, we proposed a hybrid routine which combines reaction mechanism together with coarse-grained molecular simulation to study the kinetics of free radical polymerization. By comparing with previous experimental and simulation studies, we showed the capability of our Monte Carlo scheme on representing polymerization kinetics in batch and semi-batch processes. Various kinetics information, such as instant monomer conversion, molecular weight, and polydispersity etc. are readily calculated from Monte Carlo simulation. The kinetic constants such as polymerization rate k p is determined in the simulation without of “steady-state” hypothesis. We explored the mechanism for the variation of polymerization kinetics those observed in previous studies, as well as polymerization-induced phase separation. Our Monte Carlo simulation scheme is versatile on studying polymerization kinetics in batch and semi-batch processes.

Secondary reactions of tar during thermochemical biomass conversion[Dissertation 14341

Energy Technology Data Exchange (ETDEWEB)

Morf, P.O.

2001-07-01

This dissertation submitted to the Swiss Federal Institute of Technology in Zurich presents and discusses the results obtained during the examination of the processes involved in the formation and conversion of tar in biomass gasification plant. Details are given on the laboratory reactor system used to provide separated tar production and conversion for the purposes of the experiments carried out. The results of analyses made of the tar and the gaseous products obtained after its conversion at various temperatures are presented. The development of kinetic models using the results of the experiments that were carried out is described. The results of the experiments and modelling are compared with the corresponding results obtained using a full-scale down-draft, fixed-bed gasifier. The author is of the opinion that the reaction conditions found in full-scale gasifiers can be well simulated using heterogeneous tar conversion experiments using the lab reactor system.

Development of a Comprehensive Communication Skills Curriculum for Pediatrics Residents.

Science.gov (United States)

Peterson, Eleanor B; Boland, Kimberly A; Bryant, Kristina A; McKinley, Tara F; Porter, Melissa B; Potter, Katherine E; Calhoun, Aaron W

2016-12-01

Effective communication is an essential element of medical care and a priority of medical education. Specific interventions to teach communication skills are at the discretion of individual residency programs. We developed the Resident Communication Skills Curriculum (RCSC), a formal curriculum designed to teach trainees the communication skills essential for high-quality practice. A multidisciplinary working group contributed to the development of the RCSC, guided by an institutional needs assessment, literature review, and the Accreditation Council for Graduate Medical Education core competencies. The result was a cohesive curriculum that incorporates didactic, role play, and real-life experiences over the course of the entire training period. Methods to assess curricular outcomes included self-reporting, surveys, and periodic faculty evaluations of the residents. Curricular components have been highly rated by residents (3.95-3.97 based on a 4-point Likert scale), and residents' self-reported communication skills demonstrated an improvement over the course of residency in the domains of requesting a consultation, providing effective handoffs, handling conflict, and having difficult conversations (intern median 3.0, graduate median 4.0 based on a 5-point Likert scale, P  ≤ .002). Faculty evaluations of residents have also demonstrated improvement over time (intern median 3.0, graduate median 4.5 based on a 5-point Likert scale, P  communication skills curriculum for pediatrics residents was implemented, with a multistep evaluative process showing improvement in skills over the course of the residency program. Positive resident evaluations and informal comments from faculty support its general acceptance. The use of existing resources makes this curriculum feasible.

Effects of molecular confinement and crowding on horseradish peroxidase kinetics using a nanofluidic gradient mixer.

Science.gov (United States)

Wichert, William R A; Han, Donghoon; Bohn, Paul W

2016-03-07

The effects of molecular confinement and crowding on enzyme kinetics were studied at length scales and under conditions similar to those found in biological cells. These experiments were carried out using a nanofluidic network of channels constituting a nanofluidic gradient mixer, providing the basis for measuring multiple experimental conditions simultaneously. The 100 nm × 40 μm nanochannels were wet etched directly into borosilicate glass, then annealed and characterized with fluorescein emission prior to kinetic measurements. The nanofluidic gradient mixer was then used to measure the kinetics of the conversion of the horseradish peroxidase (HRP)-catalyzed conversion of non-fluorescent Amplex Red (AR) to the fluorescent product resorufin in the presence of hydrogen peroxide (H2O2). The design of the gradient mixer allows reaction kinetics to be studied under multiple (five) unique solution compositions in a single experiment. To characterize the efficiency of the device the effects of confinement on HRP-catalyzed AR conversion kinetics were studied by varying the starting ratio of AR : H2O2. Equimolar concentrations of Amplex Red and H2O2 yielded the highest reaction rates followed by 2 : 1, 1 : 2, 5 : 1, and finally 1 : 5 [AR] : [H2O2]. Under all conditions, initial reaction velocities were decreased by excess H2O2. Crowding effects on kinetics were studied by increasing solution viscosity in the nanochannels in the range 1.0-1.6 cP with sucrose. Increasing the solution viscosities in these confined geometries decreases the initial reaction velocity at the highest concentration from 3.79 μM min(-1) at 1.00 cP to 0.192 μM min(-1) at 1.59 cP. Variations in reaction velocity are interpreted in the context of models for HRP catalysis and for molecular crowding.

Co-gasification of biomass and plastics: pyrolysis kinetics studies, experiments on 100 kW dual fluidized bed pilot plant and development of thermodynamic equilibrium model and balances.

Science.gov (United States)

Narobe, M; Golob, J; Klinar, D; Francetič, V; Likozar, B

2014-06-01

Thermo-gravimetric analysis (TGA) of volatilization reaction kinetics for 50 wt.% mixtures of plastics (PE) and biomass (wood pellets) as well as for 100 wt.% plastics was conducted to predict decomposition times at 850°C and 900°C using iso-conversional model method. For mixtures, agreement with residence time of dual fluidized bed (DFB) reactor, treated as continuous stirred-tank reactor (CSTR), was obtained at large conversions. Mono-gasification of plastics and its co-gasification with biomass were performed in DFB pilot plant, using olivine as heterogeneous catalyst and heat transfer agent. It was found that co-gasification led to successful thermochemical conversion of plastics as opposed to mono-gasification. Unknown flow rates were determined applying nonlinear regression to energy and mass balances acknowledging combustion fuel, air, steam, feedstock, but also exiting char, tar, steam and other components in DFB gasification unit. Water-gas shift equilibrium and methanol synthesis requirements were incorporated into gasification model, based on measurements. Copyright © 2014 Elsevier Ltd. All rights reserved.

KINETICS OF THE HYDROXYPROPYLATION OF POTATO STARCH IN AQUEOUS-SOLUTION

NARCIS (Netherlands)

LAMMERS, G; STAMHUIS, EJ; BEENACKERS, AACM

Kinetic results are presented for the hydroxypropylation of Potato starch with methyloxirane in aqueous solution. Reaction temperatures were varied from 303 to 362 K. Sodium hydroxide was used as a catalyst. The overall conversion rate of methyloxirane in alkaline starch solution is determined by

A unified approach for description of gas hydrate formation kinetics in the presence of kinetic promoters in gas hydrate converters

International Nuclear Information System (INIS)

ZareNezhad, Bahman; Varaminian, Farshad

2013-01-01

Highlights: • A unified kinetic model for description of promoted and non-promoted gas hydrate formation processes is presented. • Effects of impeller speed, promoter concentration and different kinetic promoters are investigated. • A unique region of gas hydrate formation is identified regarding gas hydrate formation processes. • The proposed model is useful for understanding the behavior of gas hydrate formation processes and design of GTH converters. - Abstract: The kinetic promoters have found wide applications in enhancing the rate of energy conversion and storage via gas hydrate formation processes. Effects of different kinetic promoters such as anionic surfactants sodium dodecyl sulfate (SDS), dodecylbenzene sulfonic acid (DBSA), and sodium dodecyl benzene sulfonate (SDBS); cationic surfactants, Cetyl trimethyl ammonium bromide (CTAB), dodecyl trimethyl ammonium bromide (DTAB) and non-ionic surfactants, alkylpolyglucoside (APG), dodecyl polysaccharide glycoside (DPG), TritonX-100 (TX100) on methane (CH 4 ), ethane (C 2 H 6 ) and propane (C 3 H 8 ) gas hydrate formation processes are investigated in this work. A macroscopic kinetic model based on the time variations of reaction chemical potential is also presented for global description of gas hydrate formation processes. Experimental gas hydrate formation data are employed to validate the proposed kinetic model. Effects of promoter’s concentrations and agitation intensities on the gas consumption profiles are also investigated. A universal correlation and a unified kinetic map have been proposed for macroscopic description of gas hydrate formation kinetics in the presence or absence of kinetic promoters. According to the presented unified kinetic map, a unique region of gas hydrate formation is identified for the first time. For negligible amounts of kinetic promoters, the presented region disappears and approaches to a unique path at high agitation intensities. The presented unified approach is

Interactions between oxygen permeation and homogeneous-phase fuel conversion on the sweep side of an ion transport membrane

KAUST Repository

Hong, Jongsup

2013-02-01

The interactions between oxygen permeation and homogeneous fuel oxidation reactions on the sweep side of an ion transport membrane (ITM) are examined using a comprehensive model, which couples the dependency of the oxygen permeation rate on the membrane surface conditions and detailed chemistry and transport in the vicinity of the membrane. We assume that the membrane surface is not catalytic to hydrocarbon or syngas oxidation. Results show that increasing the sweep gas inlet temperature and fuel concentration enhances oxygen permeation substantially. This is accomplished through promoting oxidation reactions (oxygen consumption) and the transport of the products and reaction heat towards the membrane, which lowers the oxygen concentration and increases the gas temperature near the membrane. Faster reactions at higher fuel concentration and higher inlet gas temperature support substantial fuel conversion and lead to a higher oxygen permeation flux without the contribution of surface catalytic activity. Beyond a certain maximum in the fuel concentration, extensive heat loss to the membrane (and feed side) reduces the oxidation kinetic rates and limits oxygen permeation as the reaction front reaches the membrane. The sweep gas flow rate and channel height have moderate impacts on oxygen permeation and fuel conversion due to the residence time requirements for the chemical reactions and the location of the reaction zone relative to the membrane surface. © 2012 Elsevier B.V.

Resident physician's knowledge and attitudes toward biostatistics and research methods concepts.

Science.gov (United States)

Alzahrani, Sami H; Aba Al-Khail, Bahaa A

2015-10-01

To assess the knowledge and attitudes of resident physicians toward biostatistics and research methodology concepts. We conducted a cross-sectional study between November 2014 and October 2014 at King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia. A self-administered questionnaire was distributed to all participants. The response rate was 90%. One hundred sixty-two resident completed the questionnaire. Most residents were well-informed in basic concepts, such as, "P" values, study power, and case control studies; more than half had confidence in interpreting the results of scientific papers. Conversely, more than 67% of the residents were not knowledgeable on more sophisticated terms in biostatistics. Residents with previous training in evidence-based medicine (EBM) (p=0.05) and non-specialist residents (p=0.003) were more likely to have better knowledge scores. Females (p=0.003), and those with previous training in biostatistics and epidemiology had positive attitude toward biostatistics (p less than 0.001 in both cases). Residents who read medical journals scored lower than those who never read journals (p=0.001). Prior courses in EBM, as well as male gender were associated with knowledge scores. Reinforcing training after graduation from medical school with special focus on integrating biostatistics with epidemiology and research methods is needed.

Kinetic Parameters during Bis-GMA and TEGDMA Monomer Polymerization by ATR-FTIR: The Influence of Photoinitiator and Light Curing Source

Directory of Open Access Journals (Sweden)

Aline B. Denis

2016-01-01

Full Text Available This study aimed to analyze the kinetic parameters of two monomers using attenuated total reflectance Fourier transform infrared (ATR-FTIR: 2,2-bis-[4-(2-hydroxy-3-methacryloxypropyl-1-oxy-phenyl] propane (Bis-GMA and triethylene glycol dimethacrylate (TEGDMA. The following were calculated to evaluate the kinetic parameters: maximum conversion rate (Rpmax, time at the maximum polymerization rate (tmax, conversion at Rpmax, and total conversion recorded at the maximum conversion point after 300 s. Camphorquinone (CQ and phenyl propanedione (PPD were used in this study as photoinitiators, whereas N,N-dimethyl-p-toluidine (DMPT amine was used as a coinitiator. LED apparatus and halogen lamp were used in turn to evaluate the effect that light source had on the monomer kinetics. The mass concentration ratio for the three resin preparations was 0.7 : 0.3 for Bis-GMA and TEGDMA: R1 (CQ + DMPT, R2 (PPD + DMPT, and R3 (PPD + CQ + DMPT. The PPD association with the CQ photoinitiator altered the polymerization kinetics compared to a resin containing only the CQ photoinitiator. The light sources exhibited no significant differences for tmax of R1 and R3. Resins containing only the PPD initiator exhibited a higher tmax than those containing only CQ. However, the Rpmax decreased for resins containing the PPD photoinitiator.

Kinetics of enzymatic synthesis of liquid wax ester from oleic acid and oleyl alcohol.

Science.gov (United States)

Radzi, Salina Mat; Mohamad, Rosfarizan; Basri, Mahiran; Salleh, Abu Bakar; Ariff, Arbakariya; Rahman, Mohammad Basyaruddin Abdul; Rahman, Raja Noor Zaliha Raja Abdul

2010-01-01

The kinetics of wax ester synthesis from oleic acid and oleyl alcohol using immobilized lipase from Candida antartica as catalyst was studied with different types of impeller (Rushton turbine and AL-hydrofoil) to create different mixing conditions in 2l stirred tank reactor. The effects of catalyst concentration, reaction temperature, and impeller tip speed on the synthesis were also evaluated. Rushton turbine impeller exhibited highest conversion rate at lower impeller tip speed as compared to AL-hydrofoil impeller. A second-order reversible kinetic model from single progress curve for the prediction of fractional conversion at given reaction time was proposed and the corresponding kinetic parameter values were calculated by non-linear regression method. The results from the simulation using the proposed model showed satisfactory agreement with the experimental data. Activation energy shows a value of 21.77 Kcal/mol. The thermodynamic parameters of the process, enthalpy and entropy, were 21.15 Kcal/mol and 52.07 cal/mol.K, respectively.

Ion-neutral gas reactions in a collision/reaction cell in inductively coupled plasma mass spectrometry: Correlation of ion signal decrease to kinetic rate constants

Energy Technology Data Exchange (ETDEWEB)

Gray, Patrick J. [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States); Department of Chemistry, The Ohio State University, 120 18th Avenue, Columbus, OH 43210 (United States); Olesik, John W., E-mail: olesik.2@osu.edu [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States)

2015-03-01

Reaction gas flow rate dependent Ar{sub 2}{sup +} and Ar{sup +} signals are correlated to fundamental kinetic rate coefficients. A simple calculation, assuming that gas exits the reaction cell due only to effusion, is described to estimate the gas pressure in the reaction cell. The value of the product of the kinetic rate constant and the ion residence time in the reaction cell can be determined from experimental measurement of the decrease in an ion signal as a function of reaction gas flow rate. New kinetic rate constants are determined for the reaction of CH{sub 3}F with Ar{sup +} and Ar{sub 2}{sup +}. - Highlights: • How to determine pressure and the product of the kinetic rate constant times the ion residence time in reaction cell • Relate measured ICP-DRC-MS signals versus gas flow rate to kinetic rate constants measured previously using SIFT-MS • Describe how to determine previously unmeasured kinetic rate constants using ICP-DRC-MS.

Effect of Residence Time on Hydrothermal Carbonization of Corn Cob Residual

Directory of Open Access Journals (Sweden)

Lei Zhang

2015-05-01

Full Text Available Hydrothermal carbonization is a promising technique for conversion of industrial waste into valuable products. Producing hydrochar from corn cob residual (CCR in a cost-effective way is key, from an economic standpoint. For this purpose, the effect of residence time in the range of 0.5 to 6 h was studied under the optimal temperature of 250 °C. Results showed that the higher heating value (HHV of hydrochar increased approximately 40% in comparison to that of the raw material; however, prolonging the residence time beyond 0.5 h had a negligible effect on the HHV increase. Chemical compositions and H/C and O/C ratios of hydrochars revealed a minimal effect of longer residence time. Furthermore, thermogravimetric and derivative thermogravimetric analysis (TG/DTG, Fourier transform infrared spectroscopy (FTIR, and X-ray diffraction (XRD analysis of hydrochars also verified that the pyrolysis behavior and chemical structure of hydrochars with various residence times were similar.

Application of a validated gasification model to determine the impact of coal particle grinding size on carbon conversion

KAUST Repository

Kumar, Mayank; Ghoniem, Ahmed F.

2013-01-01

In this paper, we describe the implementation of a comprehensive, previously validated multiscale model of entrained flow gasification to examine the impact of particle size on the gasification process in two different gasifier designs; the MHI and the GE gasifier. We show that the impact of the particle size depends on whether the char conversion process is kinetically limited or boundary layer diffusion-limited. Fine grinding helps accelerate char conversion under diffusion-control conditions, whereas the impact is not as noticeable under kinetic-control operation. The availability of particular gasification agents, namely O2 in the earlier sections of the gasifier or CO2 and H2O in the latter sections, as well as the temperature, are shown to have an impact on the relative importance of kinetics versus diffusion limitation. © 2013 Elsevier Ltd. All rights reserved.

Application of a validated gasification model to determine the impact of coal particle grinding size on carbon conversion

KAUST Repository

Kumar, Mayank

2013-06-01

In this paper, we describe the implementation of a comprehensive, previously validated multiscale model of entrained flow gasification to examine the impact of particle size on the gasification process in two different gasifier designs; the MHI and the GE gasifier. We show that the impact of the particle size depends on whether the char conversion process is kinetically limited or boundary layer diffusion-limited. Fine grinding helps accelerate char conversion under diffusion-control conditions, whereas the impact is not as noticeable under kinetic-control operation. The availability of particular gasification agents, namely O2 in the earlier sections of the gasifier or CO2 and H2O in the latter sections, as well as the temperature, are shown to have an impact on the relative importance of kinetics versus diffusion limitation. © 2013 Elsevier Ltd. All rights reserved.

Hydrolysis kinetics of tulip tree xylan in hot compressed water.

Science.gov (United States)

Yoon, Junho; Lee, Hun Wook; Sim, Seungjae; Myint, Aye Aye; Park, Hee Jeong; Lee, Youn-Woo

2016-08-01

Lignocellulosic biomass, a promising renewable resource, can be converted into numerous valuable chemicals post enzymatic saccharification. However, the efficacy of enzymatic saccharification of lignocellulosic biomass is low; therefore, pretreatment is necessary to improve the efficiency. Here, a kinetic analysis was carried out on xylan hydrolysis, after hot compressed water pretreatment of the lignocellulosic biomass conducted at 180-220°C for 5-30min, and on subsequent xylooligosaccharide hydrolysis. The weight ratio of fast-reacting xylan to slow-reacting xylan was 5.25 in tulip tree. Our kinetic results were applied to three different reaction systems to improve the pretreatment efficiency. We found that semi-continuous reactor is promising. Lower reaction temperatures and shorter space times in semi-continuous reactor are recommended for improving xylan conversion and xylooligosaccharide yield. In the theoretical calculation, 95% of xylooligosaccharide yield and xylan conversion were achieved simultaneously with high selectivity (desired product/undesired product) of 100 or more. Copyright © 2016. Published by Elsevier Ltd.

Early learning effect of residents for laparoscopic sigmoid resection.

Science.gov (United States)

Bosker, Robbert; Groen, Henk; Hoff, Christiaan; Totte, Eric; Ploeg, Rutger; Pierie, Jean-Pierre

2013-01-01

To evaluate the effect of learning the laparoscopic sigmoid resection procedure on resident surgeons; establish a minimum number of cases before a resident surgeon could be expected to achieve proficiency with the procedure; and examine if an analysis could be used to measure and support the clinical evaluation of the surgeon's competence with the procedure. Retrospective analysis of data which was prospective entered in the database. From 2003 to 2007 all patients who underwent a laparoscopic sigmoid resection carried out by senior residents, who completed the procedure as the primary surgeon proctored by an experienced surgeon, were included in the study. A cumulative sum control chart (CUSUM) analysis was used evaluate performance. The procedure was defined as a failure if major intra-operative complications occurred such as intra abdominal organ injury, bleeding, or anastomotic leakage; if an inadequate number of lymph nodes (<12 nodes) were removed; or if conversion to an open surgical procedure was required. Thirteen residents performed 169 laparoscopic sigmoid resections in the period evaluated. A significant majority of the resident surgeons were able to consistently perform the procedure without failure after 11 cases and determined to be competent. One resident was not determined to be competent and the CUSUM score supported these findings. We concluded that at least 11 cases are required for most residents to obtain necessary competence with the laparoscopic sigmoid resection procedure. Evaluation with the CUSUM analysis can be used to measure and support the clinical evaluation of the resident surgeon's competence with the procedure. Copyright © 2013 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Kinetic study on Iranian furfural extract hydrocracking

Energy Technology Data Exchange (ETDEWEB)

Zarkesh, J.; Akbarnejad, M. M. [NIOC Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of); Khorasheh, F. [Sharif Univ. of Technology, Tehran (Iran, Islamic Republic of); Badakhshan, A. [Calgary Univ., AB (Canada)

1998-05-01

Upgrading heavy crude oil to light crude oil is one of the most important refining processes. Familiarity with the kinetics and related kinetic models is one of the important aspects of developing expertise in this field. This joint study between the NIOC Institute of Research of the Petroleum Industry and Sharif University was undertaken to determine the most appropriate upgrading process for Iranian heavy feed stock and to predict the conversion and product distribution in commercial hydrocracking units. The study involved the evaluation of stoichiometry of the hydrocracking process, focusing on the catalytic hydrocracking of furfural extract (a by-product of the lubricating oil plant) of the Tehran refinery. A pilot plant reactor was used. Good correspondence between model predictions and theoretical values was obtained.

Kinetics and compensation effects during steam gasification of Fujian anthracite using viscose liquor as catalyst

Energy Technology Data Exchange (ETDEWEB)

Lin Ju; Zhang Ji-yu; Zhong Xue-qing [Fuzhou University, Fuzhou (China). Institute of Chemical Engineering and Technology

2009-08-15

Catalytic steam gasification kinetics of Fujian Youxi anthracite using viscose liquor as catalyst was investigated in an isothermal thermo-gravimetric analyzer under ambient pressure. Coal conversions versus reaction time with different viscose liquor concentrations (0-12% NaOH) were measured at the temperature range from 850 to 950{sup o}C. The research shows that the viscose liquor can greatly improve the gasification rate and carbon conversion. The Loading Saturation Level (LSL) of the viscose liquor within the experimental conditions was also determined. The catalytic steam gasification reaction can be well fitted by a shrinking-core model (SCM) and the reaction rate constants are obtained. The kinetic analysis indicates that the catalytic gasification exhibits a prominent compensation effect between the activation energy and the pre-exponential factor. The kinetic equation including the compensation effects for the catalytic steam gasification of Fujian Youxi anthracite using viscose liquor as catalyst is presented. 23 refs., 7 figs., 3 tabs.

Electrochemical energy conversion: methanol fuel cell as example

Directory of Open Access Journals (Sweden)

Vielstich Wolf

2003-01-01

Full Text Available Thermodynamic and kinetic limitations of the electrochemical energy conversion are presented for the case of a methanol/oxygen fuel cell. The detection of intermediates and products is demonstrated using insitu FTIR spectroscopy and online mass spectrometry. The bifunctional catalysis of methanol oxydation by PtRu model surfaces is explained. The formation of HCOOH and HCHO via parallel reaction pathways is discussed. An example of DMFC system technology is presented.

Comparison of techniques for the determination of conversion during suspension polymerization reactions

Directory of Open Access Journals (Sweden)

J. C. Santos

2008-06-01

Full Text Available The determination of conversion during suspension polymerization reactions is not an easy task due to the heterogeneity of the reaction medium and the tendency of particles to agglomerate rapidly when stirring is stopped. Usually, bulk polymerization in ampoules is employed to study the kinetics of suspension polymerization reactions. In this work, a comparison of different techniques for the determination of conversion during suspension polymerization reactions is presented. Results showed a good agreement between the conversion obtained by gravimetry during styrene suspension polymerization and on-line conversion monitoring data using fiber-optic based Raman Spectroscopy. Nevertheless, the polymerization rate of styrene bulk polymerization carried out in ampoules was higher than the real reaction rate of styrene suspension polymerization due to slightly higher reaction temperatures. Simulation results using the experimental temperature data in a mathematical model confirmed these results.

Effect of CO on NO and N2O conversions in nonthermal argon plasma

International Nuclear Information System (INIS)

Zhao Guibing; Argyle, Morris D.; Radosz, Maciej

2006-01-01

200-600 ppm of CO inhibit NO conversion in nonthermal Ar plasma, but do not produce N 2 O. However, 1.01% of CO has no effect on NO conversion, but produces N 2 O. In general, N 2 O conversion in Ar plasma decreases with increasing CO concentration. These experimental results cannot be explained by charge transfer reactions of Ar + . Selectivity analysis of all excited states of Ar possibly contributing to NO x conversion without and with CO suggests that only Ar( 3 P 2 ) contributes to NO x conversion and CO dissociation. A kinetic model of 43 reactions is required to model NO conversion or N 2 O conversion in Ar without CO, whereas 81 reactions are required to model NO conversion and N 2 O conversion in Ar with CO. At constant gas pressure, a single set of model parameters can predict NO conversion or N 2 O conversion without and with CO. All experimental results can be explained using a reaction mechanism in which excited neutral states of Ar are the only active species, which supports the conclusion that cations have a negligible impact on these nonthermal plasma reactions

Population control of resident and immigrant microglia by mitosis and apoptosis

DEFF Research Database (Denmark)

Wirenfeldt, Martin; Dissing-Olesen, Lasse; Babcock, Alicia

2007-01-01

microglia often occurred in clusters, some having recently incorporated bromodeoxyuridine, showing that proliferation had occurred. Annexin V labeling and staining for activated caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling showed that apoptotic mechanisms participate...... in dissolution of the microglial response. Using bone marrow chimeric mice, we found that the lesion-induced proliferative capacity of resident microglia superseded that of immigrant microglia, whereas lesion-induced kinetics of apoptosis were comparable. Microglial numbers and responses were severely reduced...... in bone marrow chimeric mice. These results broaden our understanding of the microglial response to neural damage by demonstrating that simultaneously occurring mitosis and apoptosis regulate expansion and reduction of both resident and immigrant microglial cell populations....

Drift-kinetic Alfven modes in high performance tokamaks

International Nuclear Information System (INIS)

Jaun, A.; Fasoli, A.F.; Testa, D.; Vaclavik, J.; Villard, L.

2001-01-01

The stability of fast-particle driven Alfven eigenmodes is modeled in high performance tokamaks, successively with a conventional shear, an optimized shear and a tight aspect ratio plasma. A large bulk pressure yields global kinetic Alfven eigenmodes that are stabilized by mode conversion in the presence of a divertor. This suggests how conventional reactor scenarii could withstand significant pressure gradients from the fusion products. A large safety factor in the core q 0 >2.5 in deeply shear reversed configurations and a relatively large bulk ion Larmor radius in a low magnetic field can trigger global drift-kinetic Alfven eigenmodes that are unstable in high performance JET, NSTX and ITER plasmas. (author)

Residence time and physical processes in lakes

Directory of Open Access Journals (Sweden)

Nicoletta SALA

2003-09-01

Full Text Available The residence time of a lake is highly dependent on internal physical processes in the water mass conditioning its hydrodynamics; early attempts to evaluate this physical parameter emphasize the complexity of the problem, which depends on very different natural phenomena with widespread synergies. The aim of this study is to analyse the agents involved in these processes and arrive at a more realistic definition of water residence time which takes account of these agents, and how they influence internal hydrodynamics. With particular reference to temperate lakes, the following characteristics are analysed: 1 the set of the lake's caloric components which, along with summer heating, determine the stabilizing effect of the surface layers, and the consequent thermal stratification, as well as the winter destabilizing effect; 2 the wind force, which transfers part of its momentum to the water mass, generating a complex of movements (turbulence, waves, currents with the production of active kinetic energy; 3 the water flowing into the lake from the tributaries, and flowing out through the outflow, from the standpoint of hydrology and of the kinetic effect generated by the introduction of these water masses into the lake. These factors were studied in the context of the general geographical properties of the lake basin and the watershed (latitude, longitude, morphology, also taking account of the local and regional climatic situation. Also analysed is the impact of ongoing climatic change on the renewal of the lake water, which is currently changing the equilibrium between lake and atmosphere, river and lake, and relationships

The kinetics of the partial dehydration of gibbsite to activated alumina in a reactor for pneumatic transport

Directory of Open Access Journals (Sweden)

NADEZDA JOVANOVIC

2001-04-01

Full Text Available The dehidration kinetics of gibbsite to activated alumina was investigated at four different temperatures between 883 K and 943 K in a reactor for pneumatic transport in the dilute two phase flow regime. The first order kinetic behavior of this reactionwith respect to the water content of the solid material was proved and an activation energy of 66.5 kJ/mol was calculated. The effect of residence time on the water content is given and compared with theoretical calculations. The water content and other characteristics of the products depend on two main parameters, one is the short residence time and the other is the temperature of the dehydration of gibbsite. The short residence time of the gibbsite particles in a reactor for pneumatic transport prevents crystallization into new phases, as established from XRD analysis data. Reactive amorphous alumina powder, with a specific surface area of 250 m2/g, suitable as a precursor for catalyst supports is obtained.

Fructose decomposition kinetics in organic acids-enriched high temperature liquid water

Energy Technology Data Exchange (ETDEWEB)

Li, Yinghua; Lu, Xiuyang; Yuan, Lei; Liu, Xin [Department of Chemical and Biochemical Engineering, Zhejiang University, Zheda Road 38, Hangzhou 310027, Zhejiang (China)

2009-09-15

Biomass continues to be an important candidate as a renewable resource for energy, chemicals, and feedstock. Decomposition of biomass in high temperature liquid water is a promising technique for producing industrially important chemicals such as 5-hydroxymethylfurfural (5-HMF), furfural, levulinic acid with high efficiency. Hexose, which is the hydrolysis product of cellulose, will be one of the most important starting chemicals in the coming society that is highly dependent on biomass. Taking fructose as a model compound, its decomposition kinetics in organic acids-enriched high temperature liquid water was studied in the temperature range from 180 C to 220 C under the pressure of 10 MPa to further improve reaction rate and selectivity of the decomposition reactions. The results showed that the reaction rate is greatly enhanced with the addition of organic acids, especially formic acid. The effects of temperature, residence time, organic acids and their concentrations on the conversion of fructose and yield of 5-HMF were investigated. The evaluated apparent activation energies of fructose decomposition are 126.8 {+-} 3.3 kJ mol{sup -1} without any catalyst, 112.0 {+-} 13.7 kJ mol{sup -1} catalyzed with formic acid, and 125.6 {+-} 3.8 kJ mol{sup -1} catalyzed with acetic acid, respectively, which shows no significant difference. (author)

Influence of acids on the zinc conversion process with molybdate

International Nuclear Information System (INIS)

Silva, Cosmelina Goncalves da; Margarit-Mattos, Isabel Cristina Pereira; Mattos, Oscar Rosa; Barcia, Oswaldo Esteves

2010-01-01

Molybdate conversion coatings have been evaluated as possible alternative to the chromate ones. The acid used in the pH adjustment of the conversion baths exerts great influence on the anti corrosive properties of these coatings. The aim of this work was to verify the role of phosphoric and sulfuric acids on the zinc conversion process with molybdate. The techniques used were: chronopotentiometry, electrochemical impedance spectroscopy (EIS) and interfacial pH measurements. The surface characterization was made with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The chronopotentiometry results have shown that the influence of the variation of the electrode rotation speed on the conversion process is acid-dependent: the acid influences the mass transport during the conversion. The EIS measures have suggested that the conversion mechanism does not change with the acid, being the coatings thicker when H_2SO_4 is used than the obtained with H_3PO_4. The pH interfacial results have shown a pH increase more significant for the bath with H_2SO_4, indicating a fastest kinetic of zinc dissolution. It was identified the presence of Mo in all analyzed coatings, for both acids, and P in those obtained with H_3PO_4. (author)

Electron transfer kinetics on mono- and multilayer graphene.

Science.gov (United States)

Velický, Matěj; Bradley, Dan F; Cooper, Adam J; Hill, Ernie W; Kinloch, Ian A; Mishchenko, Artem; Novoselov, Konstantin S; Patten, Hollie V; Toth, Peter S; Valota, Anna T; Worrall, Stephen D; Dryfe, Robert A W

2014-10-28

Understanding of the electrochemical properties of graphene, especially the electron transfer kinetics of a redox reaction between the graphene surface and a molecule, in comparison to graphite or other carbon-based materials, is essential for its potential in energy conversion and storage to be realized. Here we use voltammetric determination of the electron transfer rate for three redox mediators, ferricyanide, hexaammineruthenium, and hexachloroiridate (Fe(CN)(6)(3-), Ru(NH3)(6)(3+), and IrCl(6)(2-), respectively), to measure the reactivity of graphene samples prepared by mechanical exfoliation of natural graphite. Electron transfer rates are measured for varied number of graphene layers (1 to ca. 1000 layers) using microscopic droplets. The basal planes of mono- and multilayer graphene, supported on an insulating Si/SiO(2) substrate, exhibit significant electron transfer activity and changes in kinetics are observed for all three mediators. No significant trend in kinetics with flake thickness is discernible for each mediator; however, a large variation in kinetics is observed across the basal plane of the same flakes, indicating that local surface conditions affect the electrochemical performance. This is confirmed by in situ graphite exfoliation, which reveals significant deterioration of initially, near-reversible kinetics for Ru(NH3)(6)(3+) when comparing the atmosphere-aged and freshly exfoliated graphite surfaces.

Glycerol acetals, kinetic study of the reaction between glycerol and formaldehyde

International Nuclear Information System (INIS)

Agirre, I.; Garcia, I.; Requies, J.; Barrio, V.L.; Gueemez, M.B.; Cambra, J.F.; Arias, P.L.

2011-01-01

The acetalization reaction between glycerol and formaldehyde using Amberlyst 47 acidic ion exchange resin was studied. These acetals can be obtained from renewable sources (bioalcohols and bioalcohol derived aldehydes) and seem to be good candidates for different applications such as oxygenated diesel additives. A preliminary kinetic study was performed in a batch stirred tank reactor studying the influence of different process parameters like temperature, feed composition and the stirring speed. A pseudo homogenous kinetic model able to explain the reaction mechanism was adjusted. Thus, the corresponding order of reaction was determined. Amberlyst 47 acidic ion exchange resin showed a fairly good behavior allowing 100% of selectivity towards acetals formation. However, the studied acetalization reaction showed high thermodynamic limitations achieving glycerol conversions around 50% using a stoichiometric feed ratio at 353 K. The product is a mixture of two isomers (1,3-Dioxan-5-ol and 1,3-dioxolane-4-methanol) and the conversion of 1,3-dioxolane-4-methanol into 1,3-Dioxan-5-ol was also observed. -- Highlights: → The reaction between glycerol and acetaldehyde shows thermodynamic limitations. → Amberlyst 47 ion exchange resins show 100% of selectivity. → A pseudo-homogeneous kinetic model is able to predict the reaction progress. → Isomerization reactions were observed from dioxalanes to dioxanes.

Conversion of ammonium uranyl carbonate to UO2 in a fluidized bed

International Nuclear Information System (INIS)

Zhao Jun; Qiu Lufu; Zhong Xing; Xu Heqing

1989-11-01

The conversion of AUC (Ammonium Uranyl Carbonate) to UO 2 was studied in a fluidized bed of 60 mm inner diameter based on the thermodynamics and kinetics data of decomposition-reduction of AUC. The influence of the reaction temperature, composition of fluidization gas and fluidization velocity on conversion were investigated by using N 2 , Ar and circulation gas (mixing gas of H 2 and CO obtained from the exhaust gas of the decomposition of AUC by catalyst crack-conversion) as the fluidization gas. The throughput is up to the high levels (3.32 kg(wet)/h·L) by using circulation gas or mixing of circulation gas and Ar (< 21%) as the fluidization gas when the reaction temperature exceeds 570 deg C

Oligosaccharide synthesis by the hyperthermostable b-glucosidase from Pyrococcus furiosus: kinetics and modelling

NARCIS (Netherlands)

Bruins, M.E.; Strubel, M.; Lieshout, van J.F.T.; Janssen, A.E.M.; Boom, R.M.

2003-01-01

Oligosaccharides can be synthesised from monosaccharides or disaccharides, using glycosidases as a catalyst. To investigate the potential of this synthesis with beta-glycosidase from Pyrococcus furiosus we determined kinetic parameters for substrate conversion and product formation from cellobiose,

Stability and kinetic studies of supported ionic liquid phase catalysts for hydroformylation of propene

DEFF Research Database (Denmark)

Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco

2005-01-01

Supported ionic liquid phase (SILP) catalysts have been studied with regard to their long-term stability in the continuous gas-phase hydroformylation of propene. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate concentration, and residence time...

Addition effect of erbium(III) trifluoromethanesulfonate in the homopolymerization kinetics of a DGEBA resin

International Nuclear Information System (INIS)

Garcia, S.J.; Ramis, X.; Serra, A.; Suay, J.

2006-01-01

Solid bisphenol-A epoxy resin of medium molecular weight was cured using a Lewis acid initiator (erbium(III) trifluoromethanesulfonate) in three different proportions (0.5, 1 and 2 phr). A kinetic study was performed in a differential scanning calorimeter. The complete kinetic triplet was determined (activation energy, pre-exponential factor, and integral function of the deg.ree of conversion) for each system. A kinetic analysis was performed with an integral isoconversional procedure (model-free), and the kinetic model was determined both with the Coats-Redfern method (the obtained isoconversional E value being accepted as the effective activation energy) and through the compensation effect. All the systems followed the same isothermal curing model simulated from non-isothermal ones. The 'nucleation and growth' Avrami kinetic model A 3/2 has been proposed as the polymerization kinetic model. The addition of initiator accelerated the reaction having higher influence when low temperatures were applied

Post-curing conversion kinetics as functions of the irradiation time and increment thickness

Directory of Open Access Journals (Sweden)

Nicola Scotti

2013-04-01

Full Text Available Objective: This study evaluated the variation of conversion degree (DC in the 12 hours following initial photoactivation of a low-shrinkage composite resin (Venus Diamond. Material and Methods: The conversion degree was monitored for 12 hours using Attenuated Total Reflection (ATR F-TIR Spectroscopy. The composite was placed in 1 or 2 mm rings and cured for 10 or 20 seconds with a LED lamp. ATR spectra were acquired from the bottom surface of each sample immediately after the initial photoactivation (P=0, 30 minutes (P=0.5 and 12 hours after photoactivation (P=12 in order to obtain the DC progression during the post-curing period. Interactions between thickness (T, irradiation time (I and post-curing (P on the DC were calculated through ANOVA testing. Results: All the first order interactions were statistically significant, with the exception of the T-P interaction. Furthermore, the shift from P=0 to P=0.5 had a statistically higher influence than the shift from P=0.5 to P=12. The post-curing period played a fundamental role in reaching higher DC values with the low-shrinkage composite resin tested in this study. Moreover, both the irradiation time and the composite thickness strongly influenced the DC. Conclusions: Increased irradiation time may be useful in obtaining a high conversion degree (DC with a low-shrinkage nano-hybrid composite resin, particularly with 2 mm composite layers.

Direct energy conversion system for D-3He fusion

International Nuclear Information System (INIS)

Tomita, Y.; Shu, L.Y.; Momota, H.

1993-11-01

A novel and highly efficient direct energy conversion system is proposed for utilizing D- 3 He fueled fusion. In order to convert kinetic energy of ions, we applied a pair of direct energy conversion systems each of which has a cusp-type DEC and a traveling wave DEC (TWDEC). In a cusp-type DEC, electrons are separated from the escaping ions at the first line-cusp and the energy of thermal ion components is converted at the second cusp DEC. The fusion protons go through the cusp-type DEC and arrive at the TWDEC, which principle is similar to 'LINAC.' The energy of fusion protons is recovered to electricity with an efficiency of more than 70%. These DECs bring about the high efficient fusion plant. (author)

Plasma Thermal Conversion of Methane to Acetylene

International Nuclear Information System (INIS)

Fincke, James Russell; Anderson, Raymond Paul; Hyde, Timothy Allen; Detering, Brent Alan; Wright, Randy Ben; Bewley, Randy Lee; Haggard, Delon C; Swank, William David

2002-01-01

This paper describes a re-examination of a known process for the direct plasma thermal conversion of methane to acetylene. Conversion efficiencies (% methane converted) approached 100% and acetylene yields in the 90-95% range with 2-4% solid carbon production were demonstrated. Specificity for acetylene was higher than in prior work. Improvements in conversion efficiency, yield, and specificity were due primarily to improved injector design and reactant mixing, and minimization of temperature gradients and cold boundary layers. At the 60-kilowatt scale cooling by wall heat transfer appears to be sufficient to quench the product stream and prevent further reaction of acetylene resulting in the formation of heavier hydrocarbon products or solid carbon. Significantly increasing the quenching rate by aerodynamic expansion of the products through a converging-diverging nozzle led to a reduction in the yield of ethylene but had little effect on the yield of other hydrocarbon products. While greater product selectivity for acetylene has been demonstrated, the specific energy consumption per unit mass of acetylene produced was not improved upon. A kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons, through benzene, is described

Kinetic study of the dehydration reaction of lithium sulfate monohydrate crystals using microscopy and modeling

Energy Technology Data Exchange (ETDEWEB)

Lan, Shuiquan [Department of Mechanical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven (Netherlands); Zondag, Herbert [Department of Mechanical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven (Netherlands); Energy research Center of the Netherlands – ECN, P.O. Box 1, 1755ZG Petten (Netherlands); Steenhoven, Anton van [Department of Mechanical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven (Netherlands); Rindt, Camilo, E-mail: c.c.m.rindt@tue.nl [Department of Mechanical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven (Netherlands)

2015-12-10

Highlights: • Kinetics of Li{sub 2}SO{sub 4}·H{sub 2}O single crystals were modeled based on elementary processes. • Kinetics of nucleation and nuclei growth were studied by using optical microscopy. • A novel experiment was designed to visualize the reaction front into crystal bulk. • Fractional conversion was calculated and compared with TGA-experiments. - Abstract: Simulation of gas–solid reactions occurring in industrial processes requires a robust kinetic model to be applicable in a wide range of complicated reaction conditions. However, in literature it is often seen that even the same reaction under specific controlled conditions is interpreted with different kinetic models. In the present work, a phenomenological model based on nucleation and nuclei growth processes is presented to study the kinetics of the dehydration reaction of lithium sulfate monohydrate single crystals. The two elementary processes of the reaction, nucleation and nuclei growth, are characterized and quantified as a function of temperature by using optical microscopy experiments. The in-situ measured characteristics of the dehydration reaction provided confirmatory evidence that the rate of nucleation obeys an exponential law and the rate of nuclei growth is approximately constant. With knowledge acquired from the optical observations as inputs of the kinetic model, the fractional conversion of the dehydration reaction was calculated and compared with experimental results from thermogravimetric analysis (TGA). A satisfactory comparison was found both in isothermal and non-isothermal conditions. It is demonstrated that this knowledge-based model has a great potential to represent the gas–solid reaction kinetics in a wide range of process conditions regarding temperature, pressure and particle geometry.

Evaluation of kinetic uncertainty in numerical models of petroleum generation

Science.gov (United States)

Peters, K.E.; Walters, C.C.; Mankiewicz, P.J.

2006-01-01

Oil-prone marine petroleum source rocks contain type I or type II kerogen having Rock-Eval pyrolysis hydrogen indices greater than 600 or 300-600 mg hydrocarbon/g total organic carbon (HI, mg HC/g TOC), respectively. Samples from 29 marine source rocks worldwide that contain mainly type II kerogen (HI = 230-786 mg HC/g TOC) were subjected to open-system programmed pyrolysis to determine the activation energy distributions for petroleum generation. Assuming a burial heating rate of 1??C/m.y. for each measured activation energy distribution, the calculated average temperature for 50% fractional conversion of the kerogen in the samples to petroleum is approximately 136 ?? 7??C, but the range spans about 30??C (???121-151??C). Fifty-two outcrop samples of thermally immature Jurassic Oxford Clay Formation were collected from five locations in the United Kingdom to determine the variations of kinetic response for one source rock unit. The samples contain mainly type I or type II kerogens (HI = 230-774 mg HC/g TOC). At a heating rate of 1??C/m.y., the calculated temperatures for 50% fractional conversion of the Oxford Clay kerogens to petroleum differ by as much as 23??C (127-150??C). The data indicate that kerogen type, as defined by hydrogen index, is not systematically linked to kinetic response, and that default kinetics for the thermal decomposition of type I or type II kerogen can introduce unacceptable errors into numerical simulations. Furthermore, custom kinetics based on one or a few samples may be inadequate to account for variations in organofacies within a source rock. We propose three methods to evaluate the uncertainty contributed by kerogen kinetics to numerical simulations: (1) use the average kinetic distribution for multiple samples of source rock and the standard deviation for each activation energy in that distribution; (2) use source rock kinetics determined at several locations to describe different parts of the study area; and (3) use a weighted

Investigation of current university research concerning energy conversion and conservation in small single-family dwellings

Science.gov (United States)

Grossman, G. R.; Roberts, A. S., Jr.

1975-01-01

An investigation was made of university research concerning energy conversion and conservation techniques which may be applied in small single-family residences. Information was accumulated through published papers, progress reports, telephone conversations, and personal interviews. A synopsis of each pertinent investigation is given. Finally, a discussion of the synopses is presented and recommendations are made concerning the applicability of concepts for the design and construction of NASA-Langley Research Center's proposed Technology Utilization House in Hampton, Virginia.

Potassium Capture by Kaolin, Part 2: K2CO3, KCI, and K2SO4

DEFF Research Database (Denmark)

Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao

2018-01-01

residence time on the reaction was investigated. The results showed that the K-capture level (C-K) (g potassium reacted by per g kaolin available) of K2CO3 and KCI by kaolin generally followed the equilibrium predictions at temperatures above 1100 degrees C, when using a kaolin particle size of D50 = 5.......47 mu m and a residence time of 1.2 s. This revealed that a nearly full conversion was obtained without kinetic or transport limitations at the conditions applied. At 800 and 900 degrees C, the measured conversions were lower than the equilibrium predictions, indicating that the reactions were either...

Experimental Study on Conversion of Stored Thermal Energy to Mechanical Work in FCI

International Nuclear Information System (INIS)

Fujii-e, Y.; Kondo, S.; Mivazaki, K.

1976-01-01

In the present study the process how the thermal energy stored in the coolant should be converted into the mechanical work is emphasized as well as the generation of pressure waves, eliminating the complicated problems involved in FCI, such as fragmentation, heat transfer from molten fuel to coolant, etc. A simulation experiment has been performed in a small scale vertical channel using stagnant potassium. Large superheat inherent in liquid metals was utilized as the method to accumulate the thermal energy. The following experimental parameters were chosen to examine their effects on the energy conversion ratio: the heat flux, the cover gas pressure, the liquid column length, the temperature of the upper unheated region and the incipient boiling superheat (corresponding to the stored thermal energy). The results are summarized that the conversion ratio from thermal to kinetic energies has increasing trends with increases of the incipient boiling superheat, the cover gas pressure and the temperature of upper unheated region, ranging over 0.02-0.75% in the present experiment. The important conclusions of the present experiment are summarized as follows. The thermal to kinetic energy conversion ratio n k ranges over 0.02-0.75 % for ΔT s = 10-150 deg.C, estimating from the maximum velocity measured. The thermal to mechanical work conversion ratio n w ranges over 0.14-5.6%. The effect of the heat flux on the both conversion ratios is small within the range covered by the present experiment (g≤133 W/cm 2 ). The effect of the liquid column length is not presented. The thermal to kinetic energy conversion ratio increases with the incipient boiling superheat which corresponds to the stored thermal energy in the present experiment. The both conversion ratio decrease with a decrease of the cover gas pressure. This is attributable to the thermal contact in the upper unheated region. The both conversion ratios increase with an increase in the temperature of the upper

Executive Summary from the 2017 Emergency Medicine Resident Wellness Consensus Summit.

Science.gov (United States)

Battaglioli, Nicole; Ankel, Felix; Doty, Christopher I; Chung, Arlene; Lin, Michelle

2018-03-01

Physician wellness has recently become a popular topic of conversation and publication within the house of medicine and specifically within emergency medicine (EM). Through a joint collaboration involving Academic Life in Emergency Medicine's (ALiEM) Wellness Think Tank, Essentials of Emergency Medicine (EEM), and the Emergency Medicine Residents' Association (EMRA), a one-day Resident Wellness Consensus Summit (RWCS) was organized. The RWCS was held on May 15, 2017, as a pre-day event prior to the 2017 EEM conference in Las Vegas, Nevada. Seven months before the RWCS event, pre-work began in the ALiEM Wellness Think Tank, which was launched in October 2016. The Wellness Think Tank is a virtual community of practice involving EM residents from the U.S. and Canada, hosted on the Slack digital-messaging platform. A working group was formed for each of the four predetermined themes: wellness curriculum development; educator toolkit resources for specific wellness topics; programmatic innovations; and wellness-targeted technologies. Pre-work for RWCS included 142 residents from 100 different training programs in the Wellness Think Tank. Participants in the actual RWCS event included 44 EM residents, five EM attendings who participated as facilitators, and three EM attendings who acted as participants. The four working groups ultimately reached a consensus on their specific objectives to improve resident wellness on both the individual and program level. The Resident Wellness Consensus Summit was a unique and novel consensus meeting, involving residents as the primary stakeholders. The summit demonstrated that it is possible to galvanize a large group of stakeholders in a relatively short time by creating robust trust, communication, and online learning networks to create resources that support resident wellness.

Combustion kinetics of hydrochar produced from hydrothermal carbonisation of Karanj (Pongamia pinnata) fruit hulls via thermogravimetric analysis.

Science.gov (United States)

Islam, Md Azharul; Kabir, G; Asif, M; Hameed, B H

2015-10-01

This study examined the combustion profile and kinetics of hydrochar produced from hydrothermal carbonisation (HTC) of Karanj fruit hulls (KFH). The HTC-KFH hydrochar combustion kinetics was investigated at 5, 10, and 20°C/min by thermogravimetric analysis. The kinetics model, Kissinger-Akahira-Sunose revealed the combustion kinetics parameters for the extent of conversion from 0.1 to 0.8; the activation energy varies from 114 to 67 kJ/mol respectively. The hydrochar combustion followed multi-steps kinetics; the Coats-Redfern models predicted the activation energies and pre-exponential constants for the hydrochar combustion zones. The diffusion models are the effective mechanism in the second and third zone. Copyright © 2015 Elsevier Ltd. All rights reserved.

The importance of inclusion of kinetic information in the extrapolation of high-to-low concentrations for human limit setting.

Science.gov (United States)

Geraets, Liesbeth; Zeilmaker, Marco J; Bos, Peter M J

2018-01-05

Human health risk assessment of inhalation exposures generally includes a high-to-low concentration extrapolation. Although this is a common step in human risk assessment, it introduces various uncertainties. One of these uncertainties is related to the toxicokinetics. Many kinetic processes such as absorption, metabolism or excretion can be subject to saturation at high concentration levels. In the presence of saturable kinetic processes of the parent compound or metabolites, disproportionate increases in internal blood or tissue concentration relative to the external concentration administered may occur resulting in nonlinear kinetics. The present paper critically reviews human health risk assessment of inhalation exposure. More specific, it emphasizes the importance of kinetic information for the determination of a safe exposure in human risk assessment of inhalation exposures assessed by conversion from a high animal exposure to a low exposure in humans. For two selected chemicals, i.e. methyl tert-butyl ether and 1,2-dichloroethane, PBTK-modelling was used, for illustrative purposes, to follow the extrapolation and conversion steps as performed in existing risk assessments for these chemicals. Human health-based limit values based on an external dose metric without sufficient knowledge on kinetics might be too high to be sufficiently protective. Insight in the actual internal exposure, the toxic agent, the appropriate dose metric, and whether an effect is related to internal concentration or dose is important. Without this, application of assessment factors on an external dose metric and the conversion to continuous exposure results in an uncertain human health risk assessment of inhalation exposures. Copyright © 2017 Elsevier B.V. All rights reserved.

Economic and socio-cultural impacts of Mainland Chinese tourists on Hong Kong residents

Directory of Open Access Journals (Sweden)

Manisa Piuchan

2018-01-01

Full Text Available The aim of this study was to investigate the economic and socio-cultural impacts from the burgeoning mainland Chinese tourists on Hong Kong residents. Ten individual, semi-structured interviews were conducted to collect Hong Kong residents' views. Content analysis was employed to analyze the data. The results showed that the socio-cultural aspects were reported negatively with regard to culture, shopping and dining, and transportation but conversely, it had a positive impact on education and infrastructure. The economic aspect showed that residents accepted and appreciated the economic benefits brought by the inflow of mainland Chinese tourists. The Hong Kong government should consider these impacts, and then provide better solutions for residents' lives and plans to cope with the upcoming scenario which might arise regarding Hong Kong's economic boom and more tourists traveling to Hong Kong. Recommendations are also suggested in this study for further development. Keywords: Chinese tourists, economic impacts, socio-cultural impacts, tourism impacts

An in situ study of zirconium-based conversion treatment on zinc surfaces

Energy Technology Data Exchange (ETDEWEB)

Taheri, P. [Materials innovation institute (M2i), Elektronicaweg 25, 2628 XG Delft (Netherlands); Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands); Laha, P. [Vrije Universiteit Brussel, Department of Electrochemical and Surface Engineering, Pleinlaan 2, B-1050 Brussels (Belgium); Terryn, H. [Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands); Vrije Universiteit Brussel, Department of Electrochemical and Surface Engineering, Pleinlaan 2, B-1050 Brussels (Belgium); Mol, J.M.C., E-mail: J.M.C.Mol@tudelft.nl [Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands)

2015-11-30

Highlights: • We investigated the deposition mechanism of zirconium conversion layer on zinc. • In situ FTIR and electrochemical measurements are conducted. • The initial hydroxyl fraction plays an important role in the deposition process. • Deposition starts with hydroxyl removal by fluoride ions. • An increase of alkalinity adjacent to the surface promotes deposition of Zr. - Abstract: This study is focused on the deposition process of zirconium-based conversion layers on Zn surfaces. The analysis approach is based on a Kretschmann configuration in which in situ ATR-FTIR spectroscopy is combined with open circuit potential (OCP) and near surface pH measurements. Differently pretreated Zn surfaces were subjected to conversion treatments, while the Zr-based deposition mechanism was probed in situ. It was found that the initial hydroxyl fraction promotes the overall Zr conversion process as the near surface pH values are influenced by the initial hydroxyl fraction. Kinetics of the early surface activation and the subsequent Zr-based conversion process are discussed and correlated to the initial hydroxyl fractions.

Effects of Alkali and Counter Ions in Sn-Beta Catalyzed Carbohydrate Conversion

DEFF Research Database (Denmark)

Elliot, Samuel G.; Tolborg, Søren; Madsen, Robert

2018-01-01

Alkali ions have been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure and are ......Alkali ions have been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure...... and are herein addressed experimentally through kinetic experiments and isotope tracking. Alkali ions have a differential effect in competing reaction pathways: they promote the rate of carbon-carbon bond breakage of carbohydrate substrates, but decrease the rates of competing dehydration pathways. Further...... addition of alkali inhibits activity of Sn-Beta in all major reaction pathways. The alkali effects on product distributions and on rates of product formation are similar, thus pointing to a kinetic reaction control and to irreversible reaction steps in the main pathways. Additionally, an effect...

Effective conversion of biomass tar into fuel gases in a microwave reactor

Energy Technology Data Exchange (ETDEWEB)

Anis, Samsudin, E-mail: samsudin-anis@yahoo.com [Department of Mechanical Engineering, Universitas Negeri Semarang, Kampus Sekaran, Gunungpati, 50229 Semarang, 8508101 (Indonesia); Zainal, Z. A., E-mail: mezainal@usm.my [School of Mechanical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia)

2016-06-03

This work deals with conversion of naphthalene (C{sub 10}H{sub 8}) as a biomass tar model compound by means of thermal and catalytic treatments. A modified microwave oven with a maximum output power of 700 W was used as the experimental reactor. Experiments were performed in a wide temperature range of 450-1200°C at a predetermined residence time of 0.24-0.5 s. Dolomite and Y-zeolite were applied to convert naphthalene catalytically into useful gases. Experimental results on naphthalene conversion showed that conversion efficiency and yield of gases increased significantly with the increase of temperature. More than 90% naphthalene conversion efficiency was achieved by thermal treatment at 1200°C and 0.5 s. Nevertheless, this treatment was unfavorable for fuel gases production. The main product of this treatment was soot. Catalytic treatment provided different results with that of thermal treatment in which fuel gases formation was found to be the important product of naphthalene conversion. At a high temperature of 900°C, dolomite had better conversion activity where almost 40 wt.% of naphthalene could be converted into hydrogen, methane and other hydrocarbon gases.

Addition effect of erbium(III) trifluoromethanesulfonate in the homopolymerization kinetics of a DGEBA resin

Energy Technology Data Exchange (ETDEWEB)

Garcia, S.J. [Area de Ciencia de los Materiales, Departament d' Enginyeria de Sistemes Industrials i Disseny, Universitat Jaume I, Avda. Vicent Sos Baynat s/n, 12071 Castellon (Spain)]. E-mail: espallar@sg.uji.es; Ramis, X. [Laboratori de Termodinamica, Escola Tecnica Superior Enginyeria Industrial Barcelona, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Serra, A. [Departament de Q. Analitica i Q. Organica, Facultat de Quimica, Universitat Rovira i Virgili, C/Marcel.li Domingo s/n, 43007 Tarragona (Spain); Suay, J. [Centro de Biomateriales, Universitat Politecnica de Valencia, Camino de Vera s/n, E-46071 Valencia (Spain)

2006-02-01

Solid bisphenol-A epoxy resin of medium molecular weight was cured using a Lewis acid initiator (erbium(III) trifluoromethanesulfonate) in three different proportions (0.5, 1 and 2 phr). A kinetic study was performed in a differential scanning calorimeter. The complete kinetic triplet was determined (activation energy, pre-exponential factor, and integral function of the deg.ree of conversion) for each system. A kinetic analysis was performed with an integral isoconversional procedure (model-free), and the kinetic model was determined both with the Coats-Redfern method (the obtained isoconversional E value being accepted as the effective activation energy) and through the compensation effect. All the systems followed the same isothermal curing model simulated from non-isothermal ones. The 'nucleation and growth' Avrami kinetic model A {sub 3/2} has been proposed as the polymerization kinetic model. The addition of initiator accelerated the reaction having higher influence when low temperatures were applied.

Single Molecule Kinetics of ENTH Binding to Lipid Membranes

Energy Technology Data Exchange (ETDEWEB)

Rozovsky, Sharon [Univ. of Delaware, Newark, DE (United States); Forstner, Martin B. [Syracuse Univ., NY (United States); Sondermann, Holger [Cornell Univ., Ithaca, NY (United States); Groves, Jay T. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-04-03

Transient recruitment of proteins to membranes is a fundamental mechanism by which the cell exerts spatial and temporal control over proteins’ localization and interactions. Thus, the specificity and the kinetics of peripheral proteins’ membrane residence are an attribute of their function. In this article, we describe the membrane interactions of the interfacial epsin N-terminal homology (ENTH) domain with its target lipid phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P₂). The direct visualization and quantification of interactions of single ENTH molecules with supported lipid bilayers is achieved using total internal reflection fluorescence microscopy (TIRFM) with a time resolution of 13 ms. This enables the recording of the kinetic behavior of ENTH interacting with membranes with physiologically relevant concentrations of PtdIns(4,5)P₂ despite the low effective binding affinity. Subsequent single fluorophore tracking permits us to build up distributions of residence times and to measure ENTH dissociation rates as a function of membrane composition. In addition, due to the high time resolution, we are able to resolve details of the motion of ENTH associated with a simple, homogeneous membrane. In this case ENTH’s diffusive transport appears to be the result of at least three different diffusion processes.

Nanostructured energy devices equilibrium concepts and kinetics

CERN Document Server

Bisquert, Juan

2014-01-01

Due to the pressing needs of society, low cost materials for energy devices have experienced an outstanding development in recent times. In this highly multidisciplinary area, chemistry, material science, physics, and electrochemistry meet to develop new materials and devices that perform required energy conversion and storage processes with high efficiency, adequate capabilities for required applications, and low production cost. Nanostructured Energy Devices: Equilibrium Concepts and Kinetics introduces the main physicochemical principles that govern the operation of energy devices. It inclu

Conversion of sulfur and nitrogen oxides in air under exposure to microsecond electron beams

International Nuclear Information System (INIS)

Denisov, G.V.; Kuznetsov, D.L.; Novoselov, Yu.N.; Tkachenko, R.M.

2002-01-01

Flue gases of power plants realizing sulfur and nitrogen oxides into the atmosphere represent one of the environmental pollution sources. Paper presents the results of experimental investigations of conversion of sulfur and nitrogen oxides in the ionized gas mixture simulating composition of off-gases of thermal power stations. Pulse beam of microsecond duration electrons was used as a source of ionization. Mutual influence of both types of oxides on process of their conversion is shown. One studied possible kinetic mechanisms to remove sulfur and nitrogen oxides from gaseous mixture [ru

Quantitative analysis of a wind energy conversion model

International Nuclear Information System (INIS)

Zucker, Florian; Gräbner, Anna; Strunz, Andreas; Meyn, Jan-Peter

2015-01-01

A rotor of 12 cm diameter is attached to a precision electric motor, used as a generator, to make a model wind turbine. Output power of the generator is measured in a wind tunnel with up to 15 m s −1 air velocity. The maximum power is 3.4 W, the power conversion factor from kinetic to electric energy is c p = 0.15. The v 3 power law is confirmed. The model illustrates several technically important features of industrial wind turbines quantitatively. (paper)

On the equivalence between the minimum entropy generation rate and the maximum conversion rate for a reactive system

International Nuclear Information System (INIS)

Bispo, Heleno; Silva, Nilton; Brito, Romildo; Manzi, João

2013-01-01

Highlights: • Minimum entropy generation (MEG) principle improved the reaction performance. • MEG rate and the maximum conversion equivalence have been analyzed. • Temperature and residence time are used to the domain establishment of MEG. • Satisfying the temperature and residence time relationship results a optimal performance. - Abstract: The analysis of the equivalence between the minimum entropy generation (MEG) rate and the maximum conversion rate for a reactive system is the main purpose of this paper. While being used as a strategy of optimization, the minimum entropy production was applied to the production of propylene glycol in a Continuous Stirred-Tank Reactor (CSTR) with a view to determining the best operating conditions, and under such conditions, a high conversion rate was found. The effects of the key variables and restrictions on the validity domain of MEG were investigated, which raises issues that are included within a broad discussion. The results from simulations indicate that from the chemical reaction standpoint a maximum conversion rate can be considered as equivalent to MEG. Such a result can be clearly explained by examining the classical Maxwell–Boltzmann distribution, where the molecules of the reactive system under the condition of the MEG rate present a distribution of energy with reduced dispersion resulting in a better quality of collision between molecules with a higher conversion rate

Athermal kinetics in low alloy steels

International Nuclear Information System (INIS)

Leiva, Jorge A Vega; Valencia Morales, Eduardo; Villar Cociña, Ernesto; Hernández Ruiz, Jesús; Donis, Carlos

2008-01-01

Athermic analyses for the kinetic study of the reactions in the solid state are preferred because they consume much less experimental work time than the isothermal tests, and lead to more accurate calculations of the energies of activation of reactions that have occurred. In the present work are required conditions where you can apply the equation of speed of an athermal reaction in a low alloy in solid steel. From records of steel (AISI 1050) dilatometric triples were calculated kinetics (E, Ko, n) that characterize the reactions that occurred during the tempering of samples using different methods of iso conversion, one of which is a new modification of the method of Friedman. Also, has shown that during the formation of carbide Epsilon in the first stage of the tempering has occurred a saturation of sites, which validates the use of some methods. Finally, the orders of the reactions occurred during tempering of steel studied treatment are calculated.

Burnout in medical residents: a study based on the job demands-resources model.

Science.gov (United States)

Zis, Panagiotis; Anagnostopoulos, Fotios; Sykioti, Panagiota

2014-01-01

Burnout is a prolonged response to chronic emotional and interpersonal stressors on the job. The purpose of our cross-sectional study was to estimate the burnout rates among medical residents in the largest Greek hospital in 2012 and identify factors associated with it, based on the job demands-resources model (JD-R). Job demands were examined via a 17-item questionnaire assessing 4 characteristics (emotional demands, intellectual demands, workload, and home-work demands' interface) and job resources were measured via a 14-item questionnaire assessing 4 characteristics (autonomy, opportunities for professional development, support from colleagues, and supervisor's support). The Maslach Burnout Inventory (MBI) was used to measure burnout. Of the 290 eligible residents, 90.7% responded. In total 14.4% of the residents were found to experience burnout. Multiple logistic regression analysis revealed that each increased point in the JD-R questionnaire score regarding home-work interface was associated with an increase in the odds of burnout by 25.5%. Conversely, each increased point for autonomy, opportunities in professional development, and each extra resident per specialist were associated with a decrease in the odds of burnout by 37.1%, 39.4%, and 59.0%, respectively. Burnout among medical residents is associated with home-work interface, autonomy, professional development, and resident to specialist ratio.

Energy Conversion and Storage Program. 1990 annual report

Energy Technology Data Exchange (ETDEWEB)

Cairns, E.J.

1992-03-01

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Wet oxidation of glycerol into fine organic acids: catalyst selection and kinetic evaluation

Directory of Open Access Journals (Sweden)

J. E. N. Brainer

2014-12-01

Full Text Available The liquid phase oxidation of glycerol was performed producing fine organic acids. Catalysts based on Pt, Pd and Bi supported on activated carbon were employed to perform the conversion of glycerol into organic acids at 313 K, 323 K and 333 K, under atmospheric pressure (1.0 bar, in a mechanically agitated slurry reactor (MASR. The experimental results indicated glycerol conversions of 98% with production of glyceric, tartronic and glycolic acids, and dihydroxyacetone. A yield of glyceric acid of 69.8%, and a selectivity of this compound of 70.6% were reached after 4 h of operation. Surface mechanisms were proposed and rate equations were formulated to represent the kinetic behavior of the process. Selective formation of glyceric acid was observed, and the kinetic parameter values indicated the lowest activation energy (38.5 kJ/mol for its production reaction step, and the highest value of the adsorption equilibrium constant of the reactant glycerol (10-4 dm³/mol.

Pyrolysis characteristics and kinetics of oil-based drilling cuttings in shale gas developing

Science.gov (United States)

Huang, Chuan; Li, Tong; Xu, Tengtun; Zeng, Yunmin; Song, Xue

2018-03-01

In this paper, the thermal behavior of waste oil-based drilling cuttings (from shale gas fields in Chongqing) was examined at different heating rates ranging from 5 to 15 °C min-1 in inert atmosphere using a sync analyzer of thermogravimetry (TG) and differential scanning calorimetry (DSC). Four methods were used to analyze the distributions and variations of kinetics parameter (active energy (E) and frequency gene (A)): Coats-Redfern and other three iso-conversion rate methods (Flynn-Wall-Ozawa, Vyazovkin and Friedman). The experimental results indicated that the process consists of three steps, i.e., water evaporation, volatilization of light oil component and heavy oil cracking. TG curves moved toward higher temperature zone caused by thermal hysteresis with the increase of temperature rising rate. For volatilization of lightweight components, the E calculated by three iso-conversion rate methods changed a little with conversion, and had almost the same results as the CR method (14.39˜20.08 kJ.mol-1). For reactions of heavy oil cracking with mixed mechanism, corresponding E rose gradually with the increase of reaction time. The CR method shows nonlinear trends and the reaction models and kinetic parameters cannot be extracted from CR curves. The results by three iso-conversion methods showed that apparent activation energy was given as 155.74˜561.10 kJ.mol-1, 141.06˜524.96 kJ.mol-1 and 74.37˜605.10 kJ.mol-1, respectively.

Mathematical modeling reveals kinetics of lymphocyte recirculation in the whole organism.

Directory of Open Access Journals (Sweden)

Vitaly V Ganusov

2014-05-01

Full Text Available The kinetics of recirculation of naive lymphocytes in the body has important implications for the speed at which local infections are detected and controlled by immune responses. With a help of a novel mathematical model, we analyze experimental data on migration of 51Cr-labeled thoracic duct lymphocytes (TDLs via major lymphoid and nonlymphoid tissues of rats in the absence of systemic antigenic stimulation. We show that at any point of time, 95% of lymphocytes in the blood travel via capillaries in the lung or sinusoids of the liver and only 5% migrate to secondary lymphoid tissues such as lymph nodes, Peyer's patches, or the spleen. Interestingly, our analysis suggests that lymphocytes travel via lung capillaries and liver sinusoids at an extremely rapid rate with the average residence time in these tissues being less than 1 minute. The model also predicts a relatively short average residence time of TDLs in the spleen (2.5 hours and a longer average residence time of TDLs in major lymph nodes and Peyer's patches (10 hours. Surprisingly, we find that the average residence time of lymphocytes is similar in lymph nodes draining the skin (subcutaneous LNs or the gut (mesenteric LNs or in Peyer's patches. Applying our model to an additional dataset on lymphocyte migration via resting and antigen-stimulated lymph nodes we find that enlargement of antigen-stimulated lymph nodes occurs mainly due to increased entrance rate of TDLs into the nodes and not due to decreased exit rate as has been suggested in some studies. Taken together, our analysis for the first time provides a comprehensive, systems view of recirculation kinetics of thoracic duct lymphocytes in the whole organism.

Thermodynamic criteria for estimating the kinetic parameters of catalytic reactions

Science.gov (United States)

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

2017-01-01

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.

The coupling effect of gas-phase chemistry and surface reactions on oxygen permeation and fuel conversion in ITM reactors

KAUST Repository

Hong, Jongsup

2015-08-01

© 2015 Elsevier B.V. The effect of the coupling between heterogeneous catalytic reactions supported by an ion transport membrane (ITM) and gas-phase chemistry on fuel conversion and oxygen permeation in ITM reactors is examined. In ITM reactors, thermochemical reactions take place in the gas-phase and on the membrane surface, both of which interact with oxygen permeation. However, this coupling between gas-phase and surface chemistry has not been examined in detail. In this study, a parametric analysis using numerical simulations is conducted to investigate this coupling and its impact on fuel conversion and oxygen permeation rates. A thermochemical model that incorporates heterogeneous chemistry on the membrane surface and detailed chemical kinetics in the gas-phase is used. Results show that fuel conversion and oxygen permeation are strongly influenced by the simultaneous action of both chemistries. It is shown that the coupling somewhat suppresses the gas-phase kinetics and reduces fuel conversion, both attributed to extensive thermal energy transfer towards the membrane which conducts it to the air side and radiates to the reactor walls. The reaction pathway and products, in the form of syngas and C2 hydrocarbons, are also affected. In addition, the operating regimes of ITM reactors in which heterogeneous- or/and homogeneous-phase reactions predominantly contribute to fuel conversion and oxygen permeation are elucidated.

Resident fatigue in otolaryngology residents: a Web based survey.

Science.gov (United States)

Nida, Andrew M; Googe, Benjamin J; Lewis, Andrea F; May, Warren L

2016-01-01

Resident fatigue has become a point of emphasis in medical education and its effects on otolaryngology residents and their patients require further study. The purpose of our study was to evaluate the prevalence and nature of fatigue in otolaryngology residents, evaluate various quality of life measures, and investigate associations of increased fatigue with resident safety. Anonymous survey. Internet based. United States allopathic otolaryngology residents. None. The survey topics included demographics, residency structure, sleep habits and perceived stress. Responses were correlated with a concurrent Epworth Sleep Scale questionnaire to evaluate effects of fatigue on resident training and quality of life. 190 residents responded to the survey with 178 completing the Epworth Sleep Scale questionnaire. Results revealed a mean Epworth Sleep Scale score of 9.9±5.1 with a median of 10.0 indicating a significant number of otolaryngology residents are excessively sleepy. Statistically significant correlations between Epworth Sleep Scale and sex, region, hours of sleep, and work hours were found. Residents taking in-house call had significantly fewer hours of sleep compared to home call (p=0.01). Residents on "head and neck" (typically consisting of a large proportion of head and neck oncologic surgery) rotations tended to have higher Epworth Sleep Scale and had significantly fewer hours of sleep (p=.003) and greater work hours (potolaryngology residents are excessively sleepy. Our data suggest that the effects of fatigue play a role in resident well-being and resident safety. Copyright © 2016 Elsevier Inc. All rights reserved.

Multisite Kinetic Modeling of 13C Metabolic MR Using [1-13C]Pyruvate

Directory of Open Access Journals (Sweden)

Pedro A. Gómez Damián

2014-01-01

Full Text Available Hyperpolarized 13C imaging allows real-time in vivo measurements of metabolite levels. Quantification of metabolite conversion between [1-13C]pyruvate and downstream metabolites [1-13C]alanine, [1-13C]lactate, and [13C]bicarbonate can be achieved through kinetic modeling. Since pyruvate interacts dynamically and simultaneously with its downstream metabolites, the purpose of this work is the determination of parameter values through a multisite, dynamic model involving possible biochemical pathways present in MR spectroscopy. Kinetic modeling parameters were determined by fitting the multisite model to time-domain dynamic metabolite data. The results for different pyruvate doses were compared with those of different two-site models to evaluate the hypothesis that for identical data the uncertainty of a model and the signal-to-noise ratio determine the sensitivity in detecting small physiological differences in the target metabolism. In comparison to the two-site exchange models, the multisite model yielded metabolic conversion rates with smaller bias and smaller standard deviation, as demonstrated in simulations with different signal-to-noise ratio. Pyruvate dose effects observed previously were confirmed and quantified through metabolic conversion rate values. Parameter interdependency allowed an accurate quantification and can therefore be useful for monitoring metabolic activity in different tissues.

Modelling Chemical Kinetics of Soybean Oil Transesterification Process for Biodiesel Production: An Analysis of Molar Ratio between Alcohol and Soybean Oil Temperature Changes on the Process Conversion Rate

Directory of Open Access Journals (Sweden)

Maicon Tait

2006-12-01

Full Text Available A mathematical model describing chemical kinetics of transesterification of soybean oil for biodiesel production has been developed. The model is based on the reverse mechanism of transesterification reactions and describes dynamics concentration changes of triglycerides, diglycerides, monoglycerides, biodiesel, and glycerol production. Reaction rate constants were written in the Arrhenius form. An analysis of key process variables such as temperature and molar ratio soybean oil- alcohol using response surface analysis was performed to achieve the maximum soybean conversion rate to biodiesel. The predictive power of the developed model was checked for the very wide range of operational conditions and parameters values by fitting different experimental results for homogeneous catalytic and non-catalytic processes published in the literature. A very good correlation between model simulations and experimental data was observed.

Reaction kinetics for preparation of silica film with Stoeber method

International Nuclear Information System (INIS)

Shang Mengying; Jiang Xiaodong; Liu Miao; Luo Xuan; Tang Yongjian; Cao Linhong

2013-01-01

A new formula was proposed to investigate the relationship between reaction time and tetraethylorthosilicate (TEOS) conversion rate for preparation of silica sol with Stöber method, by studying the reaction kinetics of TEOS hydrolytic process. An appropriate conversion rate was then determined and used to calculate the theoretical optimal reaction time. Meanwhile, silica sols were prepared by sol-gel process using TEOS as precursor and ammonia as catalyst. It was found that the reaction time decreases with an increasing amount of ammonia and water. The values of experimental optimal reaction time were obtained, and agree with the theoretical results (the errors are within 5%), which shows good applicability of our formula. (authors)

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multizone Reaction Kinetics: Modeling of Decarburization

Science.gov (United States)

Rout, Bapin Kumar; Brooks, Geoffrey; Akbar Rhamdhani, M.; Li, Zushu; Schrama, Frank N. H.; Overbosch, Aart

2018-03-01

In a previous study by the authors (Rout et al. in Metall Mater Trans B 49:537-557, 2018), a dynamic model for the BOF, employing the concept of multizone kinetics was developed. In the current study, the kinetics of decarburization reaction is investigated. The jet impact and slag-metal emulsion zones were identified to be primary zones for carbon oxidation. The dynamic parameters in the rate equation of decarburization such as residence time of metal drops in the emulsion, interfacial area evolution, initial size, and the effects of surface-active oxides have been included in the kinetic rate equation of the metal droplet. A modified mass-transfer coefficient based on the ideal Langmuir adsorption equilibrium has been proposed to take into account the surface blockage effects of SiO2 and P2O5 in slag on the decarburization kinetics of a metal droplet in the emulsion. Further, a size distribution function has been included in the rate equation to evaluate the effect of droplet size on reaction kinetics. The mathematical simulation indicates that decarburization of the droplet in the emulsion is a strong function of the initial size and residence time. A modified droplet generation rate proposed previously by the authors has been used to estimate the total decarburization rate by slag-metal emulsion. The model's prediction shows that about 76 pct of total carbon is removed by reactions in the emulsion, and the remaining is removed by reactions at the jet impact zone. The predicted bath carbon by the model has been found to be in good agreement with the industrially measured data.

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multizone Reaction Kinetics: Modeling of Decarburization

Science.gov (United States)

Rout, Bapin Kumar; Brooks, Geoffrey; Akbar Rhamdhani, M.; Li, Zushu; Schrama, Frank N. H.; Overbosch, Aart

2018-06-01

In a previous study by the authors (Rout et al. in Metall Mater Trans B 49:537-557, 2018), a dynamic model for the BOF, employing the concept of multizone kinetics was developed. In the current study, the kinetics of decarburization reaction is investigated. The jet impact and slag-metal emulsion zones were identified to be primary zones for carbon oxidation. The dynamic parameters in the rate equation of decarburization such as residence time of metal drops in the emulsion, interfacial area evolution, initial size, and the effects of surface-active oxides have been included in the kinetic rate equation of the metal droplet. A modified mass-transfer coefficient based on the ideal Langmuir adsorption equilibrium has been proposed to take into account the surface blockage effects of SiO2 and P2O5 in slag on the decarburization kinetics of a metal droplet in the emulsion. Further, a size distribution function has been included in the rate equation to evaluate the effect of droplet size on reaction kinetics. The mathematical simulation indicates that decarburization of the droplet in the emulsion is a strong function of the initial size and residence time. A modified droplet generation rate proposed previously by the authors has been used to estimate the total decarburization rate by slag-metal emulsion. The model's prediction shows that about 76 pct of total carbon is removed by reactions in the emulsion, and the remaining is removed by reactions at the jet impact zone. The predicted bath carbon by the model has been found to be in good agreement with the industrially measured data.

Feasibility of Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

Science.gov (United States)

Tarditi, A. G.; George, J. A.; Miley, G. H.; Scott, J. H.

2013-01-01

Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have 100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics.

Executive Summary from the 2017 Emergency Medicine Resident Wellness Consensus Summit

Directory of Open Access Journals (Sweden)

Felix Ankel

2018-02-01

Full Text Available Introduction: Physician wellness has recently become a popular topic of conversation and publication within the house of medicine and specifically within emergency medicine (EM. Through a joint collaboration involving Academic Life in Emergency Medicine’s (ALiEM Wellness Think Tank, Essentials of Emergency Medicine (EEM, and the Emergency Medicine Residents’ Association (EMRA, a one-day Resident Wellness Consensus Summit (RWCS was organized. Methods: The RWCS was held on May 15, 2017, as a pre-day event prior to the 2017 EEM conference in Las Vegas, Nevada. Seven months before the RWCS event, pre-work began in the ALiEM Wellness Think Tank, which was launched in October 2016. The Wellness Think Tank is a virtual community of practice involving EM residents from the U.S. and Canada, hosted on the Slack digital-messaging platform. A working group was formed for each of the four predetermined themes: wellness curriculum development; educator toolkit resources for specific wellness topics; programmatic innovations; and wellness-targeted technologies. Results: Pre-work for RWCS included 142 residents from 100 different training programs in the Wellness Think Tank. Participants in the actual RWCS event included 44 EM residents, five EM attendings who participated as facilitators, and three EM attendings who acted as participants. The four working groups ultimately reached a consensus on their specific objectives to improve resident wellness on both the individual and program level. Conclusion: The Resident Wellness Consensus Summit was a unique and novel consensus meeting, involving residents as the primary stakeholders. The summit demonstrated that it is possible to galvanize a large group of stakeholders in a relatively short time by creating robust trust, communication, and online learning networks to create resources that support resident wellness.

The investigation of degradation reaction of various saccharides in high temperature and high pressure water

Science.gov (United States)

Saito, T.; Noguchi, S.; Matsumoto, T.; Sasaki, M.; Goto, M.

2008-07-01

Recently, conversions of polysaccharides included in biomass resources have been studied in order to recover valuable chemicals. Degradation of polysaccharides has been attracted by many researchers, whereas by-products from secondary reactions of the materials have not been studied very well. For the purpose of understanding reaction behavior of various monosaccharides in high-temperature and high-pressure water regions, we investigated reaction pathway and kinetics through reaction experiments of degradation of saccharides in subcritical water. The experiment was conducted by using continuous flow-type micro-reactors. Glucose was used as the starting material. From the experimental results, the conversion of glucose increased with increasing the residence time. The yields of fructose and 1, 6-anhydro-β-D-glucose decreased with increasing the residence time. The yields of organic acids and some aldehydes increased with increasing the residence time.

The investigation of degradation reaction of various saccharides in high temperature and high pressure water

International Nuclear Information System (INIS)

Saito, T; Noguchi, S; Matsumoto, T; Sasaki, M; Goto, M

2008-01-01

Recently, conversions of polysaccharides included in biomass resources have been studied in order to recover valuable chemicals. Degradation of polysaccharides has been attracted by many researchers, whereas by-products from secondary reactions of the materials have not been studied very well. For the purpose of understanding reaction behavior of various monosaccharides in high-temperature and high-pressure water regions, we investigated reaction pathway and kinetics through reaction experiments of degradation of saccharides in subcritical water. The experiment was conducted by using continuous flow-type micro-reactors. Glucose was used as the starting material. From the experimental results, the conversion of glucose increased with increasing the residence time. The yields of fructose and 1, 6-anhydro-β-D-glucose decreased with increasing the residence time. The yields of organic acids and some aldehydes increased with increasing the residence time

Teaching Residents How to Talk About Death and Dying: A Mixed-Methods Analysis of Barriers and Randomized Educational Intervention.

Science.gov (United States)

Miller, David C; Sullivan, Amy M; Soffler, Morgan; Armstrong, Brett; Anandaiah, Asha; Rock, Laura; McSparron, Jakob I; Schwartzstein, Richard M; Hayes, Margaret M

2018-01-01

We present a pilot study exploring the effects of a brief, 30-minute educational intervention targeting resident communication surrounding dying in the intensive care unit (ICU). We sought to determine whether simulation or didactic educational interventions improved resident-reported comfort, preparation, and skill acquisition. We also sought to identify resident barriers to using the word "dying." In this mixed-methods prospective study, second- and third-year medical residents were randomized to participate in a simulation-based communication training or a didactic session. Residents completed a pre-post survey after the sessions evaluating the sessions and reflecting on their use of the word "dying" in family meetings. Forty-five residents participated in the study. Residents reported increases in comfort (Mean [M]-pre = 3.3 [standard deviation: 0.6], M-post = 3.7 [0.7]; P educational intervention improves internal medicine residents' self-reported comfort and preparation in talking about death and dying in the ICU. Residents in simulation-based training were more likely to report they learned new skills as compared to the didactic session. Residents report multiple barriers to using the word "dying" EOL conversations.

Dynamic Modeling of Cell-Free Biochemical Networks Using Effective Kinetic Models

Science.gov (United States)

2015-03-03

based whole-cell models of E. coli [6]. Conversely , highly abstracted kinetic frameworks, such as the cybernetic framework, represented a paradigm shift...metabolic objective function has been the optimization of biomass formation [18], although other metabolic objectives have also been estimated [19...experimental data. Toward these questions, we explored five hypothetical cell-free networks. Each network shared the same enzymatic connectivity, but

A Review of Previous Research in Direct Energy Conversion Fission Reactors

International Nuclear Information System (INIS)

DUONG, HENRY; POLANSKY, GARY F.; SANDERS, THOMAS L.; SIEGEL, MALCOLM D.

1999-01-01

From the earliest days of power reactor development, direct energy conversion was an obvious choice to produce high efficiency electric power generation. Directly capturing the energy of the fission fragments produced during nuclear fission avoids the intermediate conversion to thermal energy and the efficiency limitations of classical thermodynamics. Efficiencies of more than 80% are possible, independent of operational temperature. Direct energy conversion fission reactors would possess a number of unique characteristics that would make them very attractive for commercial power generation. These reactors would be modular in design with integral power conversion and operate at low pressures and temperatures. They would operate at high efficiency and produce power well suited for long distance transmission. They would feature large safety margins and passively safe design. Ideally suited to production by advanced manufacturing techniques, direct energy conversion fission reactors could be produced more economically than conventional reactor designs. The history of direct energy conversion can be considered as dating back to 1913 when Moseleyl demonstrated that charged particle emission could be used to buildup a voltage. Soon after the successful operation of a nuclear reactor, E.P. Wigner suggested the use of fission fragments for direct energy conversion. Over a decade after Wigner's suggestion, the first theoretical treatment of the conversion of fission fragment kinetic energy into electrical potential appeared in the literature. Over the ten years that followed, a number of researchers investigated various aspects of fission fragment direct energy conversion. Experiments were performed that validated the basic physics of the concept, but a variety of technical challenges limited the efficiencies that were achieved. Most research in direct energy conversion ceased in the US by the late 1960s. Sporadic interest in the concept appears in the literature until this

Impact of Managers' Coaching Conversations on Staff Knowledge Use and Performance in Long-Term Care Settings.

Science.gov (United States)

Cummings, Greta G; Hewko, Sarah J; Wang, Mengzhe; Wong, Carol A; Laschinger, Heather K Spence; Estabrooks, Carole A

2018-02-01

Extended lifespans and complex resident care needs have amplified resource demands on nursing homes. Nurse managers play an important role in staff job satisfaction, research use, and resident outcomes. Coaching skills, developed through leadership skill-building, have been shown to be of value in nursing. To test a theoretical model of nursing home staff perceptions of their work context, their managers' use of coaching conversations, and their use of instrumental, conceptual and persuasive research. Using a two-group crossover design, 33 managers employed in seven Canadian nursing homes were invited to attend a 2-day coaching development workshop. Survey data were collected from managers and staff at three time points; we analyzed staff data (n = 333), collected after managers had completed the workshop. We used structural equation modeling to test our theoretical model of contextual characteristics as causal variables, managers' characteristics, and coaching behaviors as mediating variables and staff use of research, job satisfaction, and burnout as outcome variables. The theoretical model fit the data well (χ 2 = 58, df = 43, p = .06) indicating no significant differences between data and model-implied matrices. Resonant leadership (a relational approach to influencing change) had the strongest significant relationship with manager support, which in turn influenced frequency of coaching conversations. Coaching conversations had a positive, non-significant relationship with staff persuasive use of research, which in turn significantly increased instrumental research use. Importantly, coaching conversations were significantly, negatively related to job satisfaction. Our findings add to growing research exploring the role of context and leadership in influencing job satisfaction and use of research by healthcare practitioners. One-on-one coaching conversations may be difficult for staff not used to participating in such conversations. Resonant leadership, as

Non-Linear Response to Periodic Forcing of Methane-Air Global and Detailed Kinetics in Continuous Stirred Tank Reactors Close to Extinction Conditions

Directory of Open Access Journals (Sweden)

Francesco Saverio Marra

2015-09-01

Full Text Available This paper focus on the behavior of a continuous stirred tank reactor (CSTR subject to perturbations of finite amplitude and frequency. Two main objectives are pursued: to determine the extinction line in the equivalence ratio (φ - residence time (τ plane, fixed the thermodynamic state conditions; and to characterize the response of the chemical system to periodic forcing of the residence time. Transient simulations of combustion of methane with air, using both global single-step and detailed chemical kinetic mechanisms, have been conducted and the corresponding asymptotic solutions analyzed. Results indicate very different dynamical behaviors, posing the issue of a proper choice of the kinetic scheme for the numerical study of combustion oscillations.

Electrohydrodynamics: a high-voltage direct energy conversion process; L'electrohydrodynamique: Un procede de conversion directe d'energie a haute tension

Energy Technology Data Exchange (ETDEWEB)

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

1967-04-15

This analysis consists of a theoretical and practical study of a high-tension electrical power generator based on the Van de Graaff generator principle, the main difference being that the charges produced are transported by a gas in motion and not by a belt. The electrical and thermal properties of such a generator are studied, as well as the difficult problem of the production of the ionised particles used in the conversion. A certain number of results already published on this process for converting kinetic energy into electrical energy is given, as well as some possible applications in the field of space technology. (author) [French] Cette analyse est une etude theorique et pratique d'un generateur de puissance electrique a haute tension, base sur le principe du generateur Van de Graaff, la difference principale etant que les charges produites sont transportees pur un gaz en mouvement et non par une courroie. Les proprietes electriques et thermiques d'un tel generateur sont etudiees ainsi que le probleme delicat de la production des particules ionisees utilisees dans la conversion. Un certain nombre de resultats publies sur ce procede de conversion d'energie cinetique en energie electrique sont reproduits, ainsi que les applications possibles aux problemes spatiaux. (auteur)

Space use and habitat selection of migrant and resident American Avocets in San Francisco Bay

Science.gov (United States)

Demers, Scott A.; Takekawa, John Y.; Ackerman, Joshua T.; Warnock, N.; Athearn, N.D.

2010-01-01

San Francisco Bay is a wintering area for shorebirds, including American Avocets (Recurvirostra americana). Recently, a new resident population of avocets has emerged, presumably because of the development of tidal marshes into salt-evaporation ponds. In habitat restoration now underway, as many as 90% of salt ponds will be restored to tidal marsh. However, it is unknown if wintering and resident avocets coexist and if their requirements for space and habitat differ, necessitating different management for their populations to be maintained during restoration. We captured and radio-marked wintering avocets at a salt pond and a tidal flat to determine their population status (migrant or resident) and examine their space use and habitat selection. Of the radio-marked avocets, 79% were migrants and 21% were residents. At the salt pond, residents' fidelity to their location of capture was higher, and residents moved less than did migrants from the same site. Conversely, on the tidal flat, fidelity of residents to their site of capture was lower, and residents' home ranges were larger than those of migrants from the same site. Habitat selection of migrants and residents differed little; however, capture site influenced habitat selection far more than the birds' status as migrants or residents. Our study suggests that individual avocets have high site fidelity while wintering in San Francisco Bay, although the avocet as a species is plastic in its space use and habitat selection. This plasticity may allow wintering migrant and resident avocets to adapt to habitat change in San Francisco Bay. ?? The Cooper Ornithological Society 2010.

CaRMeN: a tool for analysing and deriving kinetics in the real world.

Science.gov (United States)

Gossler, H; Maier, L; Angeli, S; Tischer, S; Deutschmann, O

2018-04-25

This paper presents the concepts of an open software tool (CaRMeN) that can be used to rapidly analyse and derive models, in particular chemical kinetics. The software automates the workflow of comparing model vs. experiment, which must currently be done manually and is thus a time-consuming and error-prone task. The capabilities of the software are illustrated through a case study. Experimental data for the conversion of methane over rhodium catalysts in a wide range of conditions and experimental setups are numerically simulated using five different mechanisms from the literature. The applicability of the mechanisms as well as differences between flow and diffusion models are evaluated. The results show that no single mechanism reliably predicts the chemical conversions of all of the experiments. Although the software was initially developed for chemical kinetics applications, it can also be extended to run any simulation code, and can therefore be applied in other scenarios.

Model-free method for isothermal and non-isothermal decomposition kinetics analysis of PET sample

International Nuclear Information System (INIS)

Saha, B.; Maiti, A.K.; Ghoshal, A.K.

2006-01-01

Pyrolysis, one possible alternative to recover valuable products from waste plastics, has recently been the subject of renewed interest. In the present study, the isoconversion methods, i.e., Vyazovkin model-free approach is applied to study non-isothermal decomposition kinetics of waste PET samples using various temperature integral approximations such as Coats and Redfern, Gorbachev, and Agrawal and Sivasubramanian approximation and direct integration (recursive adaptive Simpson quadrature scheme) to analyze the decomposition kinetics. The results show that activation energy (E α ) is a weak but increasing function of conversion (α) in case of non-isothermal decomposition and strong and decreasing function of conversion in case of isothermal decomposition. This indicates possible existence of nucleation, nuclei growth and gas diffusion mechanism during non-isothermal pyrolysis and nucleation and gas diffusion mechanism during isothermal pyrolysis. Optimum E α dependencies on α obtained for non-isothermal data showed similar nature for all the types of temperature integral approximations

Burnout in Medical Residents: A Study Based on the Job Demands-Resources Model

Directory of Open Access Journals (Sweden)

Panagiotis Zis

2014-01-01

Full Text Available Purpose. Burnout is a prolonged response to chronic emotional and interpersonal stressors on the job. The purpose of our cross-sectional study was to estimate the burnout rates among medical residents in the largest Greek hospital in 2012 and identify factors associated with it, based on the job demands-resources model (JD-R. Method. Job demands were examined via a 17-item questionnaire assessing 4 characteristics (emotional demands, intellectual demands, workload, and home-work demands’ interface and job resources were measured via a 14-item questionnaire assessing 4 characteristics (autonomy, opportunities for professional development, support from colleagues, and supervisor’s support. The Maslach Burnout Inventory (MBI was used to measure burnout. Results. Of the 290 eligible residents, 90.7% responded. In total 14.4% of the residents were found to experience burnout. Multiple logistic regression analysis revealed that each increased point in the JD-R questionnaire score regarding home-work interface was associated with an increase in the odds of burnout by 25.5%. Conversely, each increased point for autonomy, opportunities in professional development, and each extra resident per specialist were associated with a decrease in the odds of burnout by 37.1%, 39.4%, and 59.0%, respectively. Conclusions. Burnout among medical residents is associated with home-work interface, autonomy, professional development, and resident to specialist ratio.

The role of fluid compression in energy conversion and particle energization during magnetic reconnection

Science.gov (United States)

Li, X.; Guo, F.; Li, G.; Li, H.

2016-12-01

Theories of particle transport and acceleration have shown that fluid compression is the leading mechanism for particle acceleration and plasma energization. However, the role of compression in particle acceleration during magnetic reconnection is unclear. We use two approaches to study this issue. First, using fully kinetic simulations, we quantitatively calculate the effect of compression in energy conversion and particle energization during magnetic reconnection for a range of plasma beta and guide field. We show that compression has an important contribution for the energy conversion between the bulk kinetic energy and the internal energy when the guide field is smaller than the reconnecting component. Based on this result, we then study the large-scale reconnection acceleration by solving the Parker's transport equation in a background reconnecting flow provided by MHD simulations. Due to the compression effect, the simulations suggest fast particle acceleration to high energies in the reconnection layer. This study clarifies the nature of particle acceleration in reconnection layer, and may be important to understand particle acceleration and plasma energization during solar flares.

Accounting for chemical kinetics in field scale transport calculations

International Nuclear Information System (INIS)

Bryan, N.D.

2005-01-01

The modelling of column experiments has shown that the humic acid mediated transport of metal ions is dominated by the non-exchangeable fraction. Metal ions enter this fraction via the exchangeable fraction, and may transfer back again. However, in both directions these chemical reactions are slow. Whether or not a kinetic description of these processes is required during transport calculations, or an assumption of local equilibrium will suffice, will depend upon the ratio of the reaction half-time to the residence time of species within the groundwater column. If the flow rate is sufficiently slow or the reaction sufficiently fast then the assumption of local equilibrium is acceptable. Alternatively, if the reaction is sufficiently slow (or the flow rate fast), then the reaction may be 'decoupled', i.e. removed from the calculation. These distinctions are important, because calculations involving chemical kinetics are computationally very expensive, and should be avoided wherever possible. In addition, column experiments have shown that the sorption of humic substances and metal-humate complexes may be significant, and that these reactions may also be slow. In this work, a set of rules is presented that dictate when the local equilibrium and decoupled assumptions may be used. In addition, it is shown that in all cases to a first approximation, the behaviour of a kinetically controlled species, and in particular its final distribution against distance at the end of a calculation, depends only upon the ratio of the reaction first order rate to the residence time, and hence, even in the region where the simplifications may not be used, the behaviour is predictable. In this way, it is possible to obtain an estimate of the migration of these species, without the need for a complex transport calculation. (orig.)

Kinetic considerations of three-way catalysis in automobile exhaust converters

International Nuclear Information System (INIS)

Botas, J.A.; Gutierrez-Ortiz, M.A.; Gonzalez-Marcos, M.P.; Gonzalez-Marcos, J.A.; Gonzalez-Velasco, J.R.

2001-01-01

The activity of three-way catalysts is highly dependent on the reactants present in the automobile exhaust gases (CO, NO x , HC, O 2 , H 2 O, CO 2 , N 2 ) as well as their relative concentration. Thus, the influence of each reactant on the kinetic behavior of the whole mixture makes difficult to establish the accurate kinetics of the system. Activity experiments carried out close to the real operation conditions (GHSV, concentration, etc.) with a Pt/CeO 2 /Al 2 O 3 catalyst supplied data on the CO and HC oxidation and NO reduction reactions in environments formed by different reactant combinations (from binary mixtures to the whole mixture simulating the real conditions at the automobile converter).The obtained results have shown notable variations in the oxidation/reduction mechanisms depending on the presence (or absence) of components in the environment. The presence of water always promoted the three-way activity of the catalyst. The compensation effect applied to the CO, NO and HC conversions confirmed that kinetic expressions obtained with partial mixtures (not very close to the real converter environment) have only limited application for determining the whole kinetic scheme occurring in the automobile converters

Impact of Residency Training Redesign on Residents' Clinical Knowledge.

Science.gov (United States)

Waller, Elaine; Eiff, M Patrice; Dexter, Eve; Rinaldo, Jason C B; Marino, Miguel; Garvin, Roger; Douglass, Alan B; Phillips, Robert; Green, Larry A; Carney, Patricia A

2017-10-01

The In-training Examination (ITE) is a frequently used method to evaluate family medicine residents' clinical knowledge. We compared family medicine ITE scores among residents who trained in the 14 programs that participated in the Preparing the Personal Physician for Practice (P4) Project to national averages over time, and according to educational innovations. The ITE scores of 802 consenting P4 residents who trained in 2007 through 2011 were obtained from the American Board of Family Medicine. The primary analysis involved comparing scores within each academic year (2007 through 2011), according to program year (PGY) for P4 residents to all residents nationally. A secondary analysis compared ITE scores among residents in programs that experimented with length of training and compared scores among residents in programs that offered individualized education options with those that did not. Release of ITE scores was consented to by 95.5% of residents for this study. Scores of P4 residents were higher compared to national scores in each year. For example, in 2011, the mean P4 score for PGY1 was 401.2, compared to the national average of 386. For PGY2, the mean P4 score was 443.1, compared to the national average of 427, and for PGY3, the mean P4 score was 477.0, compared to the national PGY3 score of 456. Scores of residents in programs that experimented with length of training were similar to those in programs that did not. Scores were also similar between residents in programs with and without individualized education options. Family medicine residency programs undergoing substantial educational changes, including experiments in length of training and individualized education, did not appear to experience a negative effect on resident's clinical knowledge, as measured by ITE scores. Further research is needed to study the effect of a wide range of residency training innovations on ITE scores over time.

Multi site Kinetic Modeling of 13C Metabolic MR Using [1-13C]Pyruvate

International Nuclear Information System (INIS)

Damian, P.A.G.; Sperl, J.I.; Janich, M.A.; Wiesinger, F.; Schulte, R.F.; Menzel, M.I.; Damian, P.A.G.; Damian, P.A.G.; Haase, A.; Janich, M.A.; Schwaiger, M.; Janich, M.A.; Khegai, O.; Glaser, S.J.

2014-01-01

Hyperpolarized 13 C imaging allows real-time in vivo measurements of metabolite levels. Quantification of metabolite conversion between [1- 13 C]pyruvate and downstream metabolites [1- 13 C]alanine, [1- 13 C]lactate, and [ 13 C] bicarbonate can be achieved through kinetic modeling. Since pyruvate interacts dynamically and simultaneously with its downstream metabolites, the purpose of this work is the determination of parameter values through a multi site, dynamic model involving possible biochemical pathways present in MR spectroscopy. Kinetic modeling parameters were determined by fitting the multi site model to time-domain dynamic metabolite data. The results for different pyruvate doses were compared with those of different two-site models to evaluate the hypothesis that for identical data the uncertainty of a model and the signal-to-noise ratio determine the sensitivity in detecting small physiological differences in the target metabolism. In comparison to the two-site exchange models, the multi site model yielded metabolic conversion rates with smaller bias and smaller standard deviation, as demonstrated in simulations with different signal-to-noise ratio. Pyruvate dose effects observed previously were confirmed and quantified through metabolic conversion rate values. Parameter interdependency allowed an accurate quantification and can therefore be useful for monitoring metabolic activity in different tissues

Evaluation of the conversion efficiency of ceramic and metallic three way catalytic converters

International Nuclear Information System (INIS)

Santos, H.; Costa, M.

2008-01-01

Ceramic and metallic three way catalytic converters have been compared to assess the influence of the substrate geometrical and physical parameters on the exhaust gas conversions for several vehicle operating conditions. Both catalysts were placed on a vehicle equipped with a 2.8 l DOHC V6 spark ignition engine that was tested on a chassis dynamometer under steady state conditions for several engine speeds and loads. The data obtained include exhaust gas species concentrations and temperature taken both upstream and downstream of the catalytic converter, as well as temperatures in various locations within the substrate of the catalysts. The experimental data revealed that: (i) at low space velocities, the ceramic substrate presents better conversions, particularly for HC and CO, as compared to the metallic substrate, possibly because of its lower thermal conductivity which facilitates local ignition; (ii) at high space velocities, the metallic substrate presents better conversions, as compared to the ceramic substrate, mainly because of its larger geometric surface area and lower transverse Peclet number; and (iii) in general, the HC conversion for small space velocities is kinetically controlled while for high space velocities it is mass transfer limited; both limitations are less pronounced for the CO conversion and insignificant for the NO x conversion

An Analysis of Publication Productivity During Residency for 1506 Neurosurgical Residents and 117 Residency Departments in North America.

Science.gov (United States)

Khan, Nickalus R; Saad, Hassan; Oravec, Chesney S; Norrdahl, Sebastian P; Fraser, Brittany; Wallace, David; Lillard, Jock C; Motiwala, Mustafa; Nguyen, Vincent N; Lee, Siang Liao; Jones, Anna V; Ajmera, Sonia; Kalakoti, Piyush; Dave, Pooja; Moore, Kenneth A; Akinduro, Olutomi; Nyenwe, Emmanuel; Vaughn, Brandy; Michael, L Madison; Klimo, Paul

2018-05-30

Bibliometrics is defined as the study of statistical and mathematical methods used to quantitatively analyze scientific literature. The application of bibliometrics in neurosurgery continues to evolve. To calculate a number of publication productivity measures for almost all neurosurgical residents and departments within North America. These measures were correlated with survey results on the educational environment within residency programs. During May to June 2017, data were collected from departmental websites and Scopus to compose a bibliometric database of neurosurgical residents and residency programs. Data related to authorship value and study content were collected on all articles published by residents. A survey of residency program research and educational environment was administered to program directors and coordinators; results were compared with resident academic productivity. The median number of publications in residency was 3; median h-index and Resident index were 1 and 0.17 during residency, respectively. There was a statistically significant difference in academic productivity among male neurosurgical residents compared with females. The majority of articles published were tier 1 clinical articles. Residency program research support was significantly associated with increased resident productivity (P productivity. This study represents the most comprehensive bibliometric assessment of neurosurgical resident academic productivity during training to date. New benchmarks for individual and department academic productivity are provided. A supportive research environment for neurosurgical residents is associated with increased academic productivity, but a scholarly activity requirement was, surprisingly, not shown to have a positive effect.

Kinetic parameters for plasma β-endorphin in lean and obese Zucker rats

International Nuclear Information System (INIS)

Rodd, D.; Farrell, P.A.; Caston, A.L.; Green, M.H.

1991-01-01

To determine plasma clearance kinetics for β-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data. Plasma transit times were very short (10 s); however, plasma fractional catabolic rate was much slower. Plasma mean residence time was similar for both groups (50 min) as was recycle time (1.3 min). These data suggest that BE plasma disappearance kinetics are similar in L and O rats

Kinetic parameters for plasma. beta. -endorphin in lean and obese Zucker rats

Energy Technology Data Exchange (ETDEWEB)

Rodd, D.; Farrell, P.A.; Caston, A.L.; Green, M.H. (Department of Exercise and Sport Science, Pennsylvania State University, University Park (USA))

1991-03-01

To determine plasma clearance kinetics for {beta}-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data. Plasma transit times were very short (10 s); however, plasma fractional catabolic rate was much slower. Plasma mean residence time was similar for both groups (50 min) as was recycle time (1.3 min). These data suggest that BE plasma disappearance kinetics are similar in L and O rats.

Conversion of tritium gas to tritiated water

International Nuclear Information System (INIS)

Papagiannakopoulos, P.J.; Easterly, C.E.

1979-05-01

The mechanisms of conversion of tritium gas to tritiated water (HTO) have been examined for several tritium gaseous mixtures. The physical and chemical processes involved in the self-radiolysis of such mixtures have been analyzed and the kinetics involved in the formation of HTO has been presented. It has been determined that the formation of the H and/or OH free radicals, as intermediate species, are of significance in the formation of HTO. Therefore, the problem of reducing the rate of formation of tritiated water in a mixture of gaseous tritium with atmospheric components is one of finding an effective scavenger for the H and/or OH free radicals

Kinetic Study on the Esterification of Palm Fatty Acid Distillate (PFAD) Using Heterogeneous Catalyst

Science.gov (United States)

Rofiqah, U.; Djalal, R. A.; Sutrisno, B.; Hidayat, A.

2018-05-01

Esterification with heterogeneous catalysts is believed to have advantages compared to homogeneous catalysts. Palm Fatty Acid Distillate (PFAD) was esterified by ZrO2 -SO4 2-/natural zeolite at temperature variation of 55°C, 60°C, and 65°C to produce biodiesel. Determination of reaction kinetics was done by experiment and modeling. Kinetic study was approached using pseudo-homogeneous model of first order. For experiment, reaction kinetics were 0.0031 s-1, 0.0054 s-1, and 0.00937 s-1 for a temperature of 55 °C, 60 °C and 65 °C, respectively. For modelling, reaction kinetics were 0.0030 s-1, 0.0055 s-1, and 0.0090 s-1 for a temperature of 55°C, 60°C and 65°C, respectively. Rate and conversion of reaction are getting increased by increasing temperature.

First passage times for multiple particles with reversible target-binding kinetics

Science.gov (United States)

Grebenkov, Denis S.

2017-10-01

We investigate the first passage problem for multiple particles that diffuse towards a target, partially adsorb there, and then desorb after a finite exponentially distributed residence time. We search for the first time when m particles undergoing such reversible target-binding kinetics are found simultaneously on the target that may trigger an irreversible chemical reaction or a biophysical event. Even if the particles are independent, the finite residence time on the target yields an intricate temporal coupling between particles. We compute analytically the mean first passage time (MFPT) for two independent particles by mapping the original problem to higher-dimensional surface-mediated diffusion and solving the coupled partial differential equations. The respective effects of the adsorption and desorption rates on the MFPT are revealed and discussed.

The effect of water presence on the photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene in the gas-phase

Science.gov (United States)

Korologos, Christos A.; Philippopoulos, Constantine J.; Poulopoulos, Stavros G.

2011-12-01

In the present work, the gas-solid heterogeneous photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene (BTEX) over UV-irradiated titanium dioxide was studied in an annular reactor operated in the CSTR (continuous stirred-tank reactor) mode. GC-FID and GC-MS were used for analysing reactor inlet and outlet streams. Initial BTEX concentrations were in the low parts per million (ppmv) range, whereas the water concentration was in the range of 0-35,230 ppmv and the residence time varied from 50 to 210 s. The effect of water addition on the photocatalytic process showed strong dependence on the type of the BTEX and the water vapour concentration. The increase in residence time resulted in a considerable increase in the conversion achieved for all compounds and experimental conditions. There was a clear interaction between residence time and water presence regarding the effect on conversions achieved. It was established that conversions over 95% could be achieved by adjusting appropriately the experimental conditions and especially the water concentration in the reactor. In all cases, no by-products were detected above the detection limit and carbon dioxide was the only compound detected. Finally, various Langmuir-Hinshelwood kinetic models have been tested in the analysis of the experimental data obtained. The kinetic data obtained confirmed that water had an active participation in the photocatalytic reactions of benzene, toluene, ethylbenzene and m-xylene since the model involving reaction of BTEX and water adsorbed on different active sites yielded the most successful fitting to the experimental results for the first three compounds, whereas the kinetic model based on the assumption that reaction between VOC and water dissociatively adsorbed on the photocatalyst takes place was the most appropriate in the case of m-xylene.

Incorporating resident research into the dermatology residency program

Science.gov (United States)

Wagner, Richard F; Raimer, Sharon S; Kelly, Brent C

2013-01-01

Programmatic changes for the dermatology residency program at The University of Texas Medical Branch were first introduced in 2005, with the faculty goal incorporating formal dermatology research projects into the 3-year postgraduate training period. This curriculum initially developed as a recommendation for voluntary scholarly project activity by residents, but it evolved into a program requirement for all residents in 2009. Departmental support for this activity includes assignment of a faculty mentor with similar interest about the research topic, financial support from the department for needed supplies, materials, and statistical consultation with the Office of Biostatistics for study design and data analysis, a 2-week elective that provides protected time from clinical activities for the purpose of preparing research for publication and submission to a peer-reviewed medical journal, and a departmental award in recognition for the best resident scholarly project each year. Since the inception of this program, five classes have graduated a total of 16 residents. Ten residents submitted their research studies for peer review and published their scholarly projects in seven dermatology journals through the current academic year. These articles included three prospective investigations, three surveys, one article related to dermatology education, one retrospective chart review, one case series, and one article about dermatopathology. An additional article from a 2012 graduate about dermatology education has also been submitted to a journal. This new program for residents was adapted from our historically successful Dermatology Honors Research Program for medical students at The University of Texas Medical Branch. Our experience with this academic initiative to promote dermatology research by residents is outlined. It is recommended that additional residency programs should consider adopting similar research programs to enrich resident education. PMID:23901305

Incorporating resident research into the dermatology residency program.

Science.gov (United States)

Wagner, Richard F; Raimer, Sharon S; Kelly, Brent C

2013-01-01

Programmatic changes for the dermatology residency program at The University of Texas Medical Branch were first introduced in 2005, with the faculty goal incorporating formal dermatology research projects into the 3-year postgraduate training period. This curriculum initially developed as a recommendation for voluntary scholarly project activity by residents, but it evolved into a program requirement for all residents in 2009. Departmental support for this activity includes assignment of a faculty mentor with similar interest about the research topic, financial support from the department for needed supplies, materials, and statistical consultation with the Office of Biostatistics for study design and data analysis, a 2-week elective that provides protected time from clinical activities for the purpose of preparing research for publication and submission to a peer-reviewed medical journal, and a departmental award in recognition for the best resident scholarly project each year. Since the inception of this program, five classes have graduated a total of 16 residents. Ten residents submitted their research studies for peer review and published their scholarly projects in seven dermatology journals through the current academic year. These articles included three prospective investigations, three surveys, one article related to dermatology education, one retrospective chart review, one case series, and one article about dermatopathology. An additional article from a 2012 graduate about dermatology education has also been submitted to a journal. This new program for residents was adapted from our historically successful Dermatology Honors Research Program for medical students at The University of Texas Medical Branch. Our experience with this academic initiative to promote dermatology research by residents is outlined. It is recommended that additional residency programs should consider adopting similar research programs to enrich resident education.

Kinetics of gas to particle conversion in the NH/sub 3/-Chl system

Energy Technology Data Exchange (ETDEWEB)

Luria, M; Cohen, B

1980-01-01

Particle formation in the reaction of NH/sub 3/ and Chl under 1 atm of N/sub 2/ and at 25/sup 0/C was studied in a flow reactor. The critical concentration below which NO particle can be formed was found to be 3.5 x 10/sup +14/ molecule/CM/sup 3/ for (NH/sub 3/)=(HCl). Above this concentration, gas-particle conversion percentage increases rapidly to approach 100%.

Cell Origin Dictates Programming of Resident versus Recruited Macrophages during Acute Lung Injury.

Science.gov (United States)

Mould, Kara J; Barthel, Lea; Mohning, Michael P; Thomas, Stacey M; McCubbrey, Alexandra L; Danhorn, Thomas; Leach, Sonia M; Fingerlin, Tasha E; O'Connor, Brian P; Reisz, Julie A; D'Alessandro, Angelo; Bratton, Donna L; Jakubzick, Claudia V; Janssen, William J

2017-09-01

Two populations of alveolar macrophages (AMs) coexist in the inflamed lung: resident AMs that arise during embryogenesis, and recruited AMs that originate postnatally from circulating monocytes. The objective of this study was to determine whether origin or environment dictates the transcriptional, metabolic, and functional programming of these two ontologically distinct populations over the time course of acute inflammation. RNA sequencing demonstrated marked transcriptional differences between resident and recruited AMs affecting three main areas: proliferation, inflammatory signaling, and metabolism. Functional assays and metabolomic studies confirmed these differences and demonstrated that resident AMs proliferate locally and are governed by increased tricarboxylic acid cycle and amino acid metabolism. Conversely, recruited AMs produce inflammatory cytokines in association with increased glycolytic and arginine metabolism. Collectively, the data show that even though they coexist in the same environment, inflammatory macrophage subsets have distinct immunometabolic programs and perform specialized functions during inflammation that are associated with their cellular origin.

Low severity conversion of activated coal

Energy Technology Data Exchange (ETDEWEB)

Hirschon, A.S.; Ross, D.S.

1990-01-01

The results suggest that coal contains regions with structural components significantly reactive under the hydrothermal environment. Although the specific mechanism for this process remains to be developed, this activity is reminiscent of findings in studies of accelerated maturation of oil shale, where hydrothermal treatment (hydrous pyrolysis) leads to the production of petroleum hydrocarbons. In line with what has been seen in the oil shale work, the pretreatment-generated hydrocarbons and phenols appear to represent a further or more complete maturation of some fraction of the organic material within the coal. These observations could have an impact in two areas. The first is in the area of coal structure, where immature, reactive regions have not been included in the structures considered at present. The second area of interest is the more practical one of conversions to coal liquids and pyrolytic tars. It seems clear that the hydrothermal pretreatment changes the coal in some manner that favorably affects the product quality substantially and, as in the CO/water liquefaction case, favorably affects the yields. The conversions of coals of lower rank, i.e., less mature coals, could particularly benefit in terms of both product quality and product quantity. The second portion of this project also shows important benefits to coal conversion technology. It deals with synthesizing catalysts designed to cleave the weak links in the coal structure and then linking these catalysts with the pretreatment methods in Task 2. The results show that highly dispersed catalysts can effectively be used to increase the yields of soluble material. An important aspect of highly dispersed catalysts are that they can effectively catalyze coal conversion even in poor liquefaction solvents, thus making them very attractive in processes such as coprocessing where inexpensive liquefaction media such as resids are used.

Applying Expectancy Theory to residency training: proposing opportunities to understand resident motivation and enhance residency training.

Science.gov (United States)

Shweiki, Ehyal; Martin, Niels D; Beekley, Alec C; Jenoff, Jay S; Koenig, George J; Kaulback, Kris R; Lindenbaum, Gary A; Patel, Pankaj H; Rosen, Matthew M; Weinstein, Michael S; Zubair, Muhammad H; Cohen, Murray J

2015-01-01

Medical resident education in the United States has been a matter of national priority for decades, exemplified initially through the Liaison Committee for Graduate Medical Education and then superseded by the Accreditation Council for Graduate Medical Education. A recent Special Report in the New England Journal of Medicine, however, has described resident educational programs to date as prescriptive, noting an absence of innovation in education. Current aims of contemporary medical resident education are thus being directed at ensuring quality in learning as well as in patient care. Achievement and work-motivation theories attempt to explain people's choice, performance, and persistence in tasks. Expectancy Theory as one such theory was reviewed in detail, appearing particularly applicable to surgical residency training. Correlations between Expectancy Theory as a work-motivation theory and residency education were explored. Understanding achievement and work-motivation theories affords an opportunity to gain insight into resident motivation in training. The application of Expectancy Theory in particular provides an innovative perspective into residency education. Afforded are opportunities to promote the development of programmatic methods facilitating surgical resident motivation in education.

Kinetics of enzymatic high-solid hydrolysis of lignocellulosic biomass studied by calorimetry.

Science.gov (United States)

Olsen, Søren N; Lumby, Erik; McFarland, Kc; Borch, Kim; Westh, Peter

2011-03-01

Enzymatic hydrolysis of high-solid biomass (>10% w/w dry mass) has become increasingly important as a key step in the production of second-generation bioethanol. To this end, development of quantitative real-time assays is desirable both for empirical optimization and for detailed kinetic analysis. In the current work, we have investigated the application of isothermal calorimetry to study the kinetics of enzymatic hydrolysis of two substrates (pretreated corn stover and Avicel) at high-solid contents (up to 29% w/w). It was found that the calorimetric heat flow provided a true measure of the hydrolysis rate with a detection limit of about 500 pmol glucose s(-1). Hence, calorimetry is shown to be a highly sensitive real-time method, applicable for high solids, and independent on the complexity of the substrate. Dose-response experiments with a typical cellulase cocktail enabled a multidimensional analysis of the interrelationships of enzyme load and the rate, time, and extent of the reaction. The results suggest that the hydrolysis rate of pretreated corn stover is limited initially by available attack points on the substrate surface (conversion) but becomes proportional to enzyme dosage (excess of attack points) at later stages (>10% conversion). This kinetic profile is interpreted as an increase in polymer end concentration (substrate for CBH) as the hydrolysis progresses, probably due to EG activity in the enzyme cocktail. Finally, irreversible enzyme inactivation did not appear to be the source of reduced hydrolysis rate over time.

Kinetic studies on the carboxylation of 6-amino-penicillanic acid to 8-hydroxy-penillic acid

DEFF Research Database (Denmark)

Henriksen, Claus Maxel; Holm, SS; Schipper, D.

1997-01-01

The carboxylation in aqueous solution of 6-amino-penicillanic acid (6-APA) to 8-hydroxy-penillic acid (8-HPA) was studied at 25 degrees C and pH 6.5. During sparging with either a citrate buffer or a chemically defined cultivation medium containing 6-APA with mixtures of carbon dioxide and air (2.......7-41% (v/v) CO2), the kinetics for conversion of 6-APA was followed by HPLC. In the citrate buffer 6-APA was converted by two competitive reactions each following first order kinetics with respect to the concentration of 6-APA: 1. carboxylation into 8-HPA; and 2. slow conversion into an unknown compound....... Formation of the unknown compound was not observed in the cultivation medium. The carboxylation of 6-APA was also found to be first order with respect to the concentration of dissolved carbon dioxide. The rate constant for formation of 8-HPA did not differ significantly in the cultivation medium compared...

Detecting Elusive Intermediates in Carbohydrate Conversion: A Dynamic Ensemble of Acyclic Glucose-Catalyst Complexes

DEFF Research Database (Denmark)

Meier, Sebastian; Karlsson, Magnus; Jensen, Pernille Rose

2017-01-01

within few seconds prior to reaching a steady state. Exchange between the acyclic intermediates increases at conditions that favor epimerization. Species accounting for less than 0.05% of total glucose can be monitored with sub-second time resolution to allow kinetic analysis of intermediate formation...... and catalytic conversion. Epimerization occurs 2-3 orders of magnitude-fold faster than the binding of acyclic glucose to the catalyst at near-optimum reaction conditions. The current study brings insight in to the nature of acyclic intermediate-catalyst complexes of very low population and into experimental...... strategies for characterizing very minor intermediates in carbohydrate conversion to value-added compounds....

Kinetics of the subtransition in dipalmitoylphosphatidylcholine

International Nuclear Information System (INIS)

Tristram-Nagle, S.; Wiener, M.C.; Yang, C.P.; Nagle, J.F.

1987-01-01

The kinetics of the interconversions of the subgel and gel phases in dipalmitoylphosphatidylcholine have been studied by using differential dilatometry, differential scanning calorimetry (DSC), and neutral buoyancy centrifugation as a function of incubation temperature and deuteriation of the solvent. As seen by others, DSC scans show two peaks in the subgel transition region for incubation temperatures below 1 0 C. After incubation at 0.1 0 C, the DSC peak that occurs at the lower scanning temperature appears with an incubation half-time of 0.5 day and eventually converts into a peak at higher scanning temperature with an incubation half-time of 18 days. By varying the scanning rate, the authors show that these two peaks merge into one at slow scanning rates with a common equilibrium transition temperature of 13.8 0 C, in agreement with equilibrium calorimetry and dilatometry. For incubation temperatures above 4.6 0 C, only one peak appears in both scanning dilatometry and calorimetry. While the initial rate of subgel conversion is smaller at the higher incubation temperatures, after 300 h a higher percentage of the sample has converted to subgel than at the lower incubation temperatures. They suggest that higher incubation temperatures (near 5 0 C) are preferable for forming the stable subgel phase, and they present a colliding domain picture that indicates why this may be so. The results in D 2 O and the similarity of the kinetics of volume decrease with the kinetics of wide-angle diffraction lines also support the suggestion that the partial loss of interlamellar water plays a kinetic role in subgel formation

Kinetics of the subtransition in dipalmitoylphosphatidylcholine.

Science.gov (United States)

Tristram-Nagle, S; Wiener, M C; Yang, C P; Nagle, J F

1987-07-14

The kinetics of the interconversions of the subgel and gel phases in dipalmitoylphosphatidylcholine have been studied by using differential dilatometry, differential scanning calorimetry (DSC), and neutral buoyancy centrifugation as a function of incubation temperature and deuteriation of the solvent. As seen by others, DSC scans show two peaks in the subgel transition region for incubation temperatures below 1 degree C. After incubation at 0.1 degree C, the DSC peak that occurs at the lower scanning temperature appears with an incubation half-time of 0.5 day and eventually converts into a peak at higher scanning temperature with an incubation half-time of 18 days. By varying the scanning rate, we show that these two peaks merge into one at slow scanning rates with a common equilibrium transition temperature of 13.8 degrees C, in agreement with equilibrium calorimetry and dilatometry (delta V = 0.017 +/- 0.001 mL/g). For incubation temperatures above 4.6 degrees C, only one peak appears in both scanning dilatometry and calorimetry. While the initial rate of subgel conversion is smaller at the higher incubation temperatures, after 300 h a higher percentage of the sample has converted to subgel than at the lower incubation temperatures. We suggest that higher incubation temperatures (near 5 degrees C) are preferable for forming the stable subgel phase, and we present a colliding domain picture that indicates why this may be so. Our results in D2O and the similarity of the kinetics of volume decrease with the kinetics of wide-angle diffraction lines also support the suggestion that the partial loss of interlamellar water plays a kinetic role in subgel formation.

Is ecological personality always consistent with low-carbon behavioral intention of urban residents?

International Nuclear Information System (INIS)

Wei, Jia; Chen, Hong; Long, Ruyin

2016-01-01

In the field of low-carbon economics, researchers have become interested in residential consumption as a potential means for reducing carbon emissions. By analyzing and expanding the fundamental concept of personality, a type of personality, namely ecological personality (EP), was defined and a structural model of EP was constructed based on a five-factor model. The study surveyed 890 urban residents to examine the relationship between EP and low-carbon behavioral intention (LCBI). Ecological personality is a five-dimensional concept comprising eco-neuroticism, eco-agreeableness, eco-openness, eco-extraversion, and eco-conscientiousness. Ecological personality traits were positively correlated with the LCBI. However, a quadrifid graph model showed that the EP is not always consistent with LCBI, and respondents fell into two groups: one group comprised ecological residents with consistent traits (positive EP and high LCBI) and non-ecological residents with consistent traits (negative EP and low LCBI), and their EP was consistent with LCBI; the other group comprised ecological residents with gap traits (positive EP and low LCBI) and non-ecological residents with gap traits (negative EP and high LCBI), and neither showed any consistency between personality and intentions. A policy to guide the conversion of different groups into ecological residents with consistent traits is discussed. - Highlights: • The structural model of ecological personality was constructed. • The relationship between personality and behavioral intention was examined. • Ecological personality and low-carbon behavioral intention donot always match up. • A policy urging residents to be ecological was discussed.

A novel optimization approach to estimating kinetic parameters of the enzymatic hydrolysis of corn stover

Directory of Open Access Journals (Sweden)

Fenglei Qi

2016-01-01

Full Text Available Enzymatic hydrolysis is an integral step in the conversion of lignocellulosic biomass to ethanol. The conversion of cellulose to fermentable sugars in the presence of inhibitors is a complex kinetic problem. In this study, we describe a novel approach to estimating the kinetic parameters underlying this process. This study employs experimental data measuring substrate and enzyme loadings, sugar and acid inhibitions for the production of glucose. Multiple objectives to minimize the difference between model predictions and experimental observations are developed and optimized by adopting multi-objective particle swarm optimization method. Model reliability is assessed by exploring likelihood profile in each parameter space. Compared to previous studies, this approach improved the prediction of sugar yields by reducing the mean squared errors by 34% for glucose and 2.7% for cellobiose, suggesting improved agreement between model predictions and the experimental data. Furthermore, kinetic parameters such as K2IG2, K1IG, K2IG, K1IA, and K3IA are identified as contributors to the model non-identifiability and wide parameter confidence intervals. Model reliability analysis indicates possible ways to reduce model non-identifiability and tighten parameter confidence intervals. These results could help improve the design of lignocellulosic biorefineries by providing higher fidelity predictions of fermentable sugars under inhibitory conditions.

Kinetic model for quartz and spinel dissolution during melting of high-level-waste glass batch

International Nuclear Information System (INIS)

Pokorny, Richard; Rice, Jarrett A.; Crum, Jarrod V.; Schweiger, Michael J.; Hrma, Pavel

2013-01-01

The dissolution of quartz particles and the growth and dissolution of crystalline phases during the conversion of batch to glass potentially affects both the glass melting process and product quality. Crystals of spinel exiting the cold cap to molten glass below can be troublesome during the vitrification of iron-containing high-level wastes. To estimate the distribution of quartz and spinel fractions within the cold cap, we used kinetic models that relate fractions of these phases to temperature and heating rate. Fitting the model equations to data showed that the heating rate, apart from affecting quartz and spinel behavior directly, also affects them indirectly via concurrent processes, such as the formation and motion of bubbles. Because of these indirect effects, it was necessary to allow one kinetic parameter (the pre-exponential factor) to vary with the heating rate. The resulting kinetic equations are sufficiently simple for the detailed modeling of batch-to-glass conversion as it occurs in glass melters. The estimated fractions and sizes of quartz and spinel particles as they leave the cold cap, determined in this study, will provide the source terms needed for modeling the behavior of these solid particles within the flow of molten glass in the melter

Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA

International Nuclear Information System (INIS)

Liangping, Wang; Mo, Li; Juanjuan, Han; Ning, Guo; Jian, Wu; Aici, Qiu

2014-01-01

The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6–1.0 Ω in about 10–20 ns

Energy Conversion in Imploding Z-Pinch Plasma

International Nuclear Information System (INIS)

Fisher, V.I.; Gregorian, L.; Davara, G.; Kroupp, E.; Bernshtam, V.A.; Ralchenko, Yu. V.; Starobinets, A.; Maron, Y.

2002-01-01

Due to important applications, Z-pinches became a subject of extensive studies. In these studies, main attention is directed towards improvement in efficiency of electric energy conversion into high-power radiation burst. At present, knowledge available on physics of Z-pinch operation, plasma motion, atomic kinetics, and energy conversion is mainly knowledge of numerical simulation results. We believe further progress require (i) experimental determination of spatial distribution and time history of thermodynamic parameters and magnetic field, as well as (ii) utilization of this data for experiment-based calculation of r,t-distribution of driving forces, mass and energy fluxes, and local energy deposition rates due to each of contributing mechanisms, what provides an insight into a process of conversion of stored electric energy into radiation burst. Moreover, experimentally determined r, t-distribution of parameters may serve for verification of computer programs developed for simulation of Z-pinch operation and optimization of radiation output. Within this research program we performed detailed spectroscopic study of plasmas imploding in modest-size (25 kV, 5 kJ, 1.2 μs quaterperiod) gas-puff Z-pinch. This facility has reasonably high repetition rate and provides good reproducibility of results. Consistent with plasma ionization degree in the implosion period, measurements are performed in UV-visible spectral range. Observation of spectral lines emitted at various azimuthal angles f showed no dependence on f. Dependence on axial coordinate z is found to be weak in near-anode half of the anode-cathode gap. Based on these observations and restricting the measurements to near-anode half of the gap, an evolution of parameters is studied in time and radial coordinate r only. In present talk we report on determination of radial component of plasma hydrodynamic velocity u r (r,t), magnetic field B ζ (r,t), electron density n e (r,t), density of ions in various

In Vivo Hemozoin Kinetics after Clearance of Plasmodium berghei Infection in Mice

Directory of Open Access Journals (Sweden)

Rosangela Frita

2012-01-01

Full Text Available Hemozoin (Hz is released into the blood stream after rupture of infected red blood cells (iRBCs at the end of each parasite replication cycle. This free Hz is ingested by circulating and resident phagocytes. The presence of Hz in tissues after clearance of infection has been previously reported. Still, little is known about the kinetics of Hz in vivo, during and after Plasmodium infection. It is particularly important to understand Hz kinetics after malaria infections as it has been reported that Hz is associated with impairment of immune functions, including possible consequences for coinfections. Indeed, if Hz remains biologically active for prolonged periods of time inside immunocompetent cells, the potential consequences of such accumulation and presence to the immune system should be clarified. Here, using several independent methods to assess the presence of Hz, we report the long-term in vivo kinetics of Hz in diverse organs in a murine model of malaria infection.

Plasma-assisted CO2 conversion: optimizing performance via microwave power modulation

Science.gov (United States)

Britun, Nikolay; Silva, Tiago; Chen, Guoxing; Godfroid, Thomas; van der Mullen, Joost; Snyders, Rony

2018-04-01

Significant improvement in the energy efficiency of plasma-assisted CO2 conversion is achieved with applied power modulation in a surfaguide microwave discharge. The obtained values of CO2 conversion and energy efficiency are, respectively, 0.23 and 0.33 for a 0.95 CO2  +  0.05 N2 gas mixture. Analysis of the energy relaxation mechanisms shows that power modulation can potentially affect the vibrational-translational energy exchange in plasma. In our case, however, this mechanism does not play a major role, likely due to the low degree of plasma non-equilibrium in the considered pressure range. Instead, the gas residence time in the discharge active zone together with plasma pulse duration are found to be the main factors affecting the CO2 conversion efficiency at low plasma pulse repetition rates. This effect is confirmed experimentally by the in situ time-resolved two-photon absorption laser-induced fluorescence measurements of CO molecular density produced in the discharge as a result of CO2 decomposition.

Conversion of different ash content brown coal in fluidized bed

Energy Technology Data Exchange (ETDEWEB)

Osipov, P.; Chernyavskiy, N.; Ryzhkov, A.; Remenuk, A. [Ural Federal Univ., Ekaterinburg (Russian Federation). Dept. of Thermal Power Plants; Dulienko, S. [National Academy of Science of Ukraine, Kiev (Ukraine). Coal Energy Technology Inst.

2013-07-01

Available equations used to determine combustion specific rate of coal-derived cokes describe the burning of carbon particles well enough but are not accurate in case of ash-containing coke particles combustion. This study is an attempt to account for the influence of both initial ash content and its increase in the course of carbon conversion in specific rate calculations. The results of experimental study of burn-out dynamics of Volchanskiy field (North Urals) brown coal and its coke with different ash content under conditions of fluidized bed combustion at impulse-type non-gradient reactor RSC-1 and dynamic installation Pyrolysis-M are summarized. Diffusion and heterogeneous (kinetic) components of carbon combustion rate are identified separately by using diffusion and kinetics equation with correction for carbon mass fraction in particles. Burning particle overheating values and heterogeneous combustion rate constants at different temperatures are estimated.

Kinetic Study of Methyl Acetate Oxidation in a Pt/Al2O3 Fixed-Bed Reactor

Science.gov (United States)

Hoy, Michael; Li, K. Y.; Li, Jeffrey S.; Chen, S. M.; Yaws, C. L.; Chu, H. W.; Simon, W. E.

1994-01-01

To support technology development for future long-term missions, a metabolic simulator will be used in a closed chamber to test the functions of a Controlled Ecological Life Support System (CELSS). Methyl acetate (MA) was selected as the fuel because its metabolic respiratory quotient is near that of humans. A kinetic study of the catalytic oxidation of MA over Pt/Al203 was then conducted to support the design and operation of the simulator. Kinetic data were obtained as a conversion percentage of MA versus retention time. The reaction was studied at one atmosphere and temperatures from 220 to 340 deg. C. The inlet MA concentration was varied from 100 to 2000 ppm with retention times from 0.01 to 10 sec. A first-order rate law and a Langmuir-Hinshelwood rate equation were tested by nonlinear regression of the kinetic data to estimate rate constants in the rate law. Regression results of the L-H equation explain the kinetic data better than the results of the first-order rate law. A Taguchi experimental design was used to study the effects of temperature, retention time, and concentrations of MA, CO2, and O2 on the conversion of MA. Results indicate that temperature has greatest effect, followed by retention time, and finally MA concentration. It was further determined that the effects of CO2 and O2 concentrations, and the cross effects, are negligible.

Kinetics of oxidation of H2 and reduction of H2O in Ni-YSZ based solid oxide cells

DEFF Research Database (Denmark)

Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

2012-01-01

Reduction of H2O and oxidation of H2 was studied in a Ni-YSZ electrode supported Solid Oxide Cells produced at DTU Energy conversion (former Risø DTU). Polarisation (i-V) and electrochemical impedance spectroscopic characterisation show that the kinetics for reduction of H 2O is slower compared...... to oxidation of H2. The kinetic differences cannot be explained by the reaction mechanisms which are similar in the two cases but are rather an effect of the thermodynamics. The preliminary analysis performed in this study show that the slow kinetic for reduction is partly related to the endothermic nature...... of the reaction, cooling the active electrode, thereby leading to slower kinetics at low current densities. Likewise, the increased kinetic for oxidation was found to be related to the exothermic nature of the reaction, heating the active electrode, and thereby leading to faster kinetics. At higher current...

Early resident-to-resident physics education in diagnostic radiology.

Science.gov (United States)

Kansagra, Akash P

2014-01-01

The revised ABR board certification process has updated the method by which diagnostic radiology residents are evaluated for competency in clinical radiologic physics. In this work, the author reports the successful design and implementation of a resident-taught physics course consisting of 5 weekly, hour-long lectures intended for incoming first-year radiology residents in their first month of training. To the author's knowledge, this is the first description of a course designed to provide a very early framework for ongoing physics education throughout residency without increasing the didactic burden on faculty members. Twenty-six first-year residents spanning 2 academic years took the course and reported subjective improvement in their knowledge (90%) and interest (75%) in imaging physics and a high level of satisfaction with the use of senior residents as physics educators. Based on the success of this course and the minimal resources required for implementation, this work may serve as a blueprint for other radiology residency programs seeking to develop revised physics curricula. Copyright © 2014 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Kinetic study of hydrolysis of coconut fiber into glucose

Science.gov (United States)

Muhaimin, Sudiono, Sri

2017-03-01

Kinetic study of hydrolysis of coconut fiber into glucose has been done. The aim of this research was to study of the effect of time and temperature to the glucose as the result of the conversion of coconut fiber. The various temperature of the hydrolysis process were 30 °C, 48 °C, 72 °C and 95 °C and the various time of the hydrolysis process were 0, 15, 30, 60, 120, 180, 240, 300 minutes. A quantitative analysis was done by measured the concentration of the glucose as the result of the conversion of coconut fiber. The result showed that the rate constant from the various temperature were 3.10-4 minute-1; 8.10-4 minutees-1; 84.10-4 minute-1, and 205.10-4 minute-1, and the energy activation was 7,69. 103 kJ/mol.

Gallbladder Nonvisualization in Cholecystectomy: A Factor for Conversion.

Science.gov (United States)

Slack, Daniel R; Grisby, Shaunda; Dike, Uzoamaka Kimberly; Kohli, Harjeet

2018-01-01

Many risk factors have been identified in minimally invasive cholecystectomies that lead to higher complications and conversion rates. No study that we encountered looked at nonvisualization of the gallbladder (GB) during surgery as a risk factor. We hypothesized that nonvisualization was associated with an increased risk of complications and could be an early intraoperative identifier of a higher risk procedure. Recognizing this could allow surgeons to be aware of potential risks and to be more likely to convert to open for the safety of the patient. We looked at minimally invasive cholecystectomies performed at our institution from January 2015 through April 2016 and had the performing resident fill out a survey after the surgery. Outcomes were conversion rates, intraoperative complications, and blood loss and were analyzed via Pearson χ 2 test or Mann-Whitney U test. The primary outcome showed a conversion rate of 37% in nonvisualized GBs versus 0% in visualized ( P = .001). Secondary outcomes showed significant differences in GB perforations (74% vs 13%, P = .001), omental vessel bleeding (16% vs. 0%, P = .005), and EBL (46 mL vs 29 mL, P = .001). Intraoperative nonvisualization of the GB after adequate positioning caused significantly increased risk of intraoperative complications and conversion. This knowledge could be useful during intraoperative assessment, to decide whether a case should be continued as a minimally invasive procedure or converted early to help reduce risk to the patient. Further randomized controlled studies should be performed to further demonstrate the value of this assessment.

Kinetics of photoirradiation-induced synthesis of soy oil-conjugated linoleic acid isomers.

Science.gov (United States)

Jain, Vishal P; Proctor, Andrew

2007-02-07

Photoirradiation of soy oil with UV/visible light has been shown to produce significant amounts of trans,trans conjugated linoleic acid (CLA) isomers through conversion of various synthesized intermediate cis,trans isomers. The objective of this study was to determine the kinetics of CLA isomers synthesis to better understand the production of various isomers. Soy oil was irradiated with UV/visible light for 144 h in the presence of an iodine catalyst and CLA isomers analyzed by gas chromatography (GC). Arrhenius plots were developed for the conversion of soy oil linoleic acid (A) to form cis-, trans/trans-, cis-CLA (B), conversion of cis-, trans/trans-, cis-CLA to form trans,trans-CLA (C) with respect to B, and formation of trans,trans-CLA isomers with respect to C. The kinetics of consumption of linoleic acid (LA) to form cis-, trans/trans-, cis-CLA was found to be of second-order with a rate constant of 9.01 x 10-7 L/mol s. The rate of formation of cis-, trans/trans-, cis-CLA isomers depends on the rate of formation from LA and its rate of consumption to form trans,trans-CLA isomers. The conversion of cis-, trans/trans-, cis-CLA isomers to trans,trans-CLA isomers was found to be of first-order with a rate constant of 2.75 x 10-6 s-1. However, the formation of thermodynamically stable trans,trans-CLA isomers (C) with respect to C was found to be a zero-order reaction with a rate constant of 10.66 x 10-7 mol/L s. The consumption of LA was found to be the rate-determining step in the CLA isomers formation reaction mechanism. The findings provide a better understanding of the mechanism of CLA isomers synthesis by photoirradiation and the factors controlling the ratio of various isomers.

Experimental determination of the kinetic conversion rate of gaseous tritium into HTO

International Nuclear Information System (INIS)

Gulden, W.; Guenot, J.; Djerassi, H.; Clerc, H.

1986-09-01

To assess the impact of atmospheric tritium releases from a fusion plant to the environment, the dose to man usually is determined under the conservative assumption that all tritium is released in the more dangerous oxide form. To quantify this overprediction, experiments are presently being performed by CEA. Oxidation of tritium gas by soil and subsequent resuspension of HTO from soil to atmosphere is one of them. First results have been obtained by CEA on the kinetics of HTO resuspension from contaminated soils. Immediately after contamination, the fraction of the deposited activity which is resuspended to atmosphere is in the range of 1% to 5% per hour. This resuspension rate then decreases more or less slowly with time, depending on specific conditions

Use of social media by residency program directors for resident selection.

Science.gov (United States)

Cain, Jeff; Scott, Doneka R; Smith, Kelly

2010-10-01

Pharmacy residency program directors' attitudes and opinions regarding the use of social media in residency recruitment and selection were studied. A 24-item questionnaire was developed, pilot tested, revised, and sent to 996 residency program directors via SurveyMonkey.com. Demographic, social media usage, and opinions on social media data were collected and analyzed. A total of 454 residency program directors completed the study (response rate, 46.4%). The majority of respondents were women (58.8%), were members of Generation X (75.4%), and worked in a hospital or health system (80%). Most respondents (73%) rated themselves as either nonusers or novice users of social media. Twenty percent indicated that they had viewed a pharmacy residency applicant's social media information. More than half (52%) had encountered e-professionalism issues, including questionable photos and posts revealing unprofessional attitudes, and 89% strongly agreed or agreed that information voluntarily published online was fair game for judgments on character, attitudes, and professionalism. Only 4% of respondents had reviewed applicants' profiles for residency selection decisions. Of those respondents, 52% indicated that the content had no effect on resident selection. Over half of residency program directors were unsure whether they will use social media information for future residency selection decisions. Residency program directors from different generations had different views regarding social media information and its use in residency applicant selections. Residency program directors anticipated using social media information to aid in future decisions for resident selection and hiring.

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts

Science.gov (United States)

Bhatt, R. T.; Palczer, A. R.

1998-01-01

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

Enhancing charge transfer kinetics by nanoscale catalytic cermet interlayer.

Science.gov (United States)

An, Jihwan; Kim, Young-Beom; Gür, Turgut M; Prinz, Fritz B

2012-12-01

Enhancing the density of catalytic sites is crucial for improving the performance of energy conversion devices. This work demonstrates the kinetic role of 2 nm thin YSZ/Pt cermet layers on enhancing the oxygen reduction kinetics for low temperature solid oxide fuel cells. Cermet layers were deposited between the porous Pt cathode and the dense YSZ electrolyte wafer using atomic layer deposition (ALD). Not only the catalytic role of the cermet layer itself but the mixing effect in the cermet was explored. For cells with unmixed and fully mixed cermet interlayers, the maximum power density was enhanced by a factor of 1.5 and 1.8 at 400 °C, and by 2.3 and 2.7 at 450 °C, respectively, when compared to control cells with no cermet interlayer. The observed enhancement in cell performance is believed to be due to the increased triple phase boundary (TPB) density in the cermet interlayer. We also believe that the sustained kinetics for the fully mixed cermet layer sample stems from better thermal stability of Pt islands separated by the ALD YSZ matrix, which helped to maintain the high-density TPBs even at elevated temperature.

Experimental conditions affecting the kinetics of aqueous HCN polymerization as revealed by UV-vis spectroscopy.

Science.gov (United States)

Marín-Yaseli, Margarita R; Moreno, Miguel; de la Fuente, José L; Briones, Carlos; Ruiz-Bermejo, Marta

2018-02-15

HCN polymerization is one of the most important and fascinating reactions in prebiotic chemistry, and interest in HCN polymers in the field of materials science is growing. However, little is known about the kinetics of the HCN polymerization process. In the present study, a first approach to the kinetics of two sets of aqueous HCN polymerizations, from NH 4 CN and NaCN, at middle temperatures between 4 and 38°C, has been carried out. For each series, the presence of air and salts in the reaction medium has been systematically explored. A previous kinetic analysis was conducted during the conversion of the insoluble black HCN polymers obtained as gel fractions in these precipitation polymerizations for a reaction of one month, where a limit conversion was achieved at the highest polymerization temperature. The kinetic description of the gravimetric data for this complex system shows a clear change in the linear dependence with the polymerization temperature for the reaction from NH 4 CN, besides a relevant catalytic effect of ammonium, in comparison with those data obtained from the NaCN series. These results also demonstrated the notable influence of air, oxygen, and the saline medium in HCN polymer formation. Similar conclusions were reached when the sol fractions were monitored by UV-vis spectroscopy, and a Hill type correlation was used to describe the polymerization profiles obtained. This technique was chosen because it provides an easy, prompt and fast method to follow the evolution of the liquid or continuous phase of the process under study. Copyright © 2017 Elsevier B.V. All rights reserved.

DIRECT ENERGY CONVERSION (DEC) FISSION REACTORS - A U.S. NERI PROJECT

International Nuclear Information System (INIS)

Beller, D.; Polansky, G.

2000-01-01

The direct conversion of the electrical energy of charged fission fragments was examined early in the nuclear reactor era, and the first theoretical treatment appeared in the literature in 1957. Most of the experiments conducted during the next ten years to investigate fission fragment direct energy conversion (DEC) were for understanding the nature and control of the charged particles. These experiments verified fundamental physics and identified a number of specific problem areas, but also demonstrated a number of technical challenges that limited DEC performance. Because DEC was insufficient for practical applications, by the late 1960s most R and D ceased in the US. Sporadic interest in the concept appears in the literature until this day, but there have been no recent programs to develop the technology. This has changed with the Nuclear Energy Research Initiative that was funded by the U.S. Congress in 1999. Most of the previous concepts were based on a fission electric cell known as a triode, where a central cathode is coated with a thin layer of nuclear fuel. A fission fragment that leaves the cathode with high kinetic energy and a large positive charge is decelerated as it approaches the anode by a charge differential of several million volts, it then deposits its charge in the anode after its kinetic energy is exhausted. Large numbers of low energy electrons leave the cathode with each fission fragment; they are suppressed by negatively biased on grid wires or by magnetic fields. Other concepts include magnetic collimators and quasi-direct magnetohydrodynamic generation (steady flow or pulsed). We present the basic principles of DEC fission reactors, review the previous research, discuss problem areas in detail and identify technological developments of the last 30 years relevant to overcoming these obstacles. A prognosis for future development of direct energy conversion fission reactors will be presented

Electrohydrodynamics: a high-voltage direct energy conversion process

International Nuclear Information System (INIS)

Brun, S.

1967-04-01

This analysis consists of a theoretical and practical study of a high-tension electrical power generator based on the Van de Graaff generator principle, the main difference being that the charges produced are transported by a gas in motion and not by a belt. The electrical and thermal properties of such a generator are studied, as well as the difficult problem of the production of the ionised particles used in the conversion. A certain number of results already published on this process for converting kinetic energy into electrical energy is given, as well as some possible applications in the field of space technology. (author) [fr

COAL CONVERSION WASTEWATER TREATMENT BY CATALYTIC OXIDATION IN SUPERCRITICAL WATER; FINAL

International Nuclear Information System (INIS)

Phillip E. Savage

1999-01-01

Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, we examined the oxidation of phenol over a commercial catalyst and over bulk MnO(sub 2), bulk TiO(sub 2), and CuO supported on Al(sub 2) O(sub 3). We used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which we can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO(sub 2) yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that we could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, we performed experiments with bulk transition metal oxides. The bulk MnO(sub 2) and TiO(sub 2) catalysts enhance both the phenol disappearance and CO(sub 2) formation rates during SCWO. MnO(sub 2) does not affect the selectivity to CO(sub 2), or to the phenol dimers at a given phenol conversion. However, the selectivities to CO(sub 2) are increased and the selectivities to phenol dimers are decreased in the presence of TiO(sub 2) , which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the rate of formation of

Comparison of Emergency Medicine Malpractice Cases Involving Residents to Non-Resident Cases.

Science.gov (United States)

Gurley, Kiersten L; Grossman, Shamai A; Janes, Margaret; Yu-Moe, C Winnie; Song, Ellen; Tibbles, Carrie D; Shapiro, Nathan I; Rosen, Carlo L

2018-04-17

Data are lacking on how emergency medicine (EM) malpractice cases with resident involvement differs from cases that do not name a resident. To compare malpractice case characteristics in cases where a resident is involved (resident case) to cases that do not involve a resident (non-resident case) and to determine factors that contribute to malpractice cases utilizing EM as a model for malpractice claims across other medical specialties. We used data from the Controlled Risk Insurance Company (CRICO) Strategies' division Comparative Benchmarking System (CBS) to analyze open and closed EM cases asserted from 2009-2013. The CBS database is a national repository that contains professional liability data on > 400 hospitals and > 165,000 physicians, representing over 30% of all malpractice cases in the U.S (> 350,000 claims). We compared cases naming residents (either alone or in combination with an attending) to those that did not involve a resident (non-resident cohort). We reported the case statistics, allegation categories, severity scores, procedural data, final diagnoses and contributing factors. Fisher's exact test or t-test was used for comparisons (alpha set at 0.05). Eight hundred and forty-five EM cases were identified of which 732 (87%) did not name a resident (non-resident cases), while 113 (13%) included a resident (resident cases) (Figure 1). There were higher total incurred losses for non-resident cases (Table 1). The most frequent allegation categories in both cohorts were "Failure or Delay in Diagnosis/Misdiagnosis" and "Medical Treatment" (non-surgical procedures or treatment regimens i.e. central line placement). Allegation categories of Safety and Security, Patient Monitoring, Hospital Policy and Procedure and Breach of Confidentiality were found in the non-resident cases. Resident cases incurred lower payments on average ($51,163 vs. $156,212 per case). Sixty six percent (75) of resident vs 57% (415) of non-resident cases were high severity claims

Determination of glutamate dehydrogenase activity and its kinetics in mouse tissues using metabolic mapping (quantitative enzyme histochemistry)

NARCIS (Netherlands)

Botman, Dennis; Tigchelaar, Wikky; van Noorden, Cornelis J. F.

2014-01-01

Glutamate dehydrogenase (GDH) catalyses the reversible conversion of glutamate into α-ketoglutarate with the concomitant reduction of NAD(P)(+) to NAD(P)H or vice versa. GDH activity is subject to complex allosteric regulation including substrate inhibition. To determine GDH kinetics in situ, we

Thermal conversion of polyolefins/polystyrene ternary mixtures: Kinetics and pyrolysis on a laboratory and commercial scales

Czech Academy of Sciences Publication Activity Database

Straka, Pavel; Bičáková, Olga; Šupová, Monika

2017-01-01

Roč. 128, November (2017), s. 196-207 ISSN 0165-2370 Institutional support: RVO:67985891 Keywords : kinetics * pyrolysis * oil * waste plastics * GS-MS * TG-MS Subject RIV: DM - Solid Waste and Recycling OBOR OECD: Energy and fuels Impact factor: 3.471, year: 2016

Formalization of hydrocarbon conversion scheme of catalytic cracking for mathematical model development

Science.gov (United States)

Nazarova, G.; Ivashkina, E.; Ivanchina, E.; Kiseleva, S.; Stebeneva, V.

2015-11-01

The issue of improving the energy and resource efficiency of advanced petroleum processing can be solved by the development of adequate mathematical model based on physical and chemical regularities of process reactions with a high predictive potential in the advanced petroleum refining. In this work, the development of formalized hydrocarbon conversion scheme of catalytic cracking was performed using thermodynamic parameters of reaction defined by the Density Functional Theory. The list of reaction was compiled according to the results of feedstock structural-group composition definition, which was done by the n-d-m-method, the Hazelvuda method, qualitative composition of feedstock defined by gas chromatography-mass spectrometry and individual composition of catalytic cracking gasoline fraction. Formalized hydrocarbon conversion scheme of catalytic cracking will become the basis for the development of the catalytic cracking kinetic model.

A Series of Supramolecular Complexes for Solar Energy Conversion via Water Reduction to Produce Hydrogen: An Excited State Kinetic Analysis of Ru(II,Rh(III,Ru(II Photoinitiated Electron Collectors

Directory of Open Access Journals (Sweden)

Shamindri M. Arachchige

2011-12-01

Full Text Available Mixed-metal supramolecular complexes have been designed that photochemically absorb solar light, undergo photoinitiated electron collection and reduce water to produce hydrogen fuel using low energy visible light. This manuscript describes these systems with an analysis of the photophysics of a series of six supramolecular complexes, [{(TL2Ru(dpp}2RhX2](PF65 with TL = bpy, phen or Ph2phen with X = Cl or Br. The process of light conversion to a fuel requires a system to perform a number of complicated steps including the absorption of light, the generation of charge separation on a molecular level, the reduction by one and then two electrons and the interaction with the water substrate to produce hydrogen. The manuscript explores the rate of intramolecular electron transfer, rate of quenching of the supramolecules by the DMA electron donor, rate of reduction of the complex by DMA from the 3MLCT excited state, as well as overall rate of reduction of the complex via visible light excitation. Probing a series of complexes in detail exploring the variation of rates of important reactions as a function of sub-unit modification provides insight into the role of each process in the overall efficiency of water reduction to produce hydrogen. The kinetic analysis shows that the complexes display different rates of excited state reactions that vary with TL and halide. The role of the MLCT excited state is elucidated by this kinetic study which shows that the 3MLCT state and not the 3MMCT is likely that key contributor to the photoreduction of these complexes. The kinetic analysis of the excited state dynamics and reactions of the complexes are important as this class of supramolecules behaves as photoinitiated electron collectors and photocatalysts for the reduction of water to hydrogen.

Experimental kinetic study and modeling of calcium oxide carbonation

International Nuclear Information System (INIS)

Rouchon, L.

2012-01-01

Anthropogenic carbon dioxide (CO 2 ) emissions, major contributors to the greenhouse effect, are considered as the main cause of global warming. So, decrease of CO 2 emitted by large industrial combustion sources or power plants, is an important scientific goal. One of the approaches is based on CO 2 separation and capture from flue gas, followed by sequestration in a wide range of geological formations. In this aim, CO 2 is captured by sorbents like calcium oxide (CaO) in multi-cycle process of carbonation/de-carbonation. However, it was shown that the most important limitations of such process are related to the reversibility of reaction. CaO rapidly loses activity towards CO 2 , so the maximum extent of carbonation decreases as long as the number of cycles increases. In order to well understand the processes and parameters influencing the capture capacity of CaO-based sorbents, it appears important to get details on the kinetic law governing the reaction, which have not been really studied up to now. To investigate this reaction, CaO carbonation kinetics was followed by means of thermogravimetric analysis (TGA) on divided materials. Special care was given to the validation of the usual kinetic assumptions such as steady state and rate-determining step assumptions. The aim was to obtain a model describing the reaction in order to explain the influence of intensive variables such as carbonation temperature and CO 2 partial pressure. TGA curves obtained under isothermal and isobaric conditions showed an induction period linked to the nucleation process and a strong slowing down of the reaction rate once a given fractional conversion was reached. Both phenomena were observed to depend on carbonation temperature and CO 2 partial pressure. To explain these results, the evolution of texture and microstructure of the solid during the reaction was regarded as essential. Reaction at the grain scale induces a volume increase from CaO to CaCO 3 which causes a change in the

Residents' experiences of abuse, discrimination and sexual harassment during residency training. McMaster University Residency Training Programs.

Science.gov (United States)

Cook, D J; Liutkus, J F; Risdon, C L; Griffith, L E; Guyatt, G H; Walter, S D

1996-06-01

To assess the prevalence of psychological abuse, physical assault, and discrimination on the basis of gender and sexual orientation, and to examine the prevalence and impact of sexual harassment in residency training programs. Self-administered questionnaire. McMaster University, Hamilton, Ont. Residents in seven residency training programs during the academic year from July 1993 to June 1994. Of 225 residents 186 (82.7%) returned a completed questionnaire, and 50% of the respondents were women. Prevalence of psychological abuse, physical assault and discrimination on the basis of gender and sexual orientation experienced by residents during medical training, prevalence and residents' perceived frequency of sexual harassment. Psychological abuse was reported by 50% of the residents. Some of the respondents reported physical assault, mostly by patients and their family members (14.7% reported assaults by male patients and family members, 9.8% reported assaults by female patients and family members), 5.4% of the female respondents reported assault by male supervising physicians. Discrimination on the basis of gender was reported to be common and was experienced significantly more often by female residents than by male residents (p sexual orientation. Most of the respondents experienced sexual harassment, especially in the form of sexist jokes, flirtation and unwanted compliments on their dress or figure. On average, 40% of the respondents, especially women (p sexual harassment to someone (p sexual harassment were embarassment (reported by 24.0%), anger (by 23.4%) and frustration (20.8%). Psychological abuse, discrimination on the basis of gender and sexual harassment are commonly experienced by residents in training programs. A direct, progressive, multidisciplinary approach is needed to label and address these problems.

Renewable energy from corn residues by thermochemical conversion

Science.gov (United States)

Yu, Fei

Declining fossil oil reserve, skyrocket price, unsecured supplies, and environment pollution are among the many energy problems we are facing today. It is our conviction that renewable energy is a solution to these problems. The long term goal of the proposed research is to develop commercially practical technologies to produce energy from renewable resources. The overall objective of my research is to study and develop thermochemical processes for converting bulky and low-energy-density biomass materials into bio-fuels and value-added bio-products. The rationale for the proposed research is that, once such processes are developed, processing facility can be set up on or near biomass product sites, reducing the costs associated with transport of bulky biomass which is a key technical barrier to biomass conversion. In my preliminary research, several conversion technologies including atmospheric pressure liquefaction, high pressure liquefaction, and microwave pyrolysis have been evaluated. Our data indicated that microwave pyrolysis had the potential to become a simple and economically viable biomass conversion technology. Microwave pyrolysis is an innovative process that provides efficient and uniform heating, and are robust to type, size and uniformity of feedstock and therefore suitable for almost any waste materials without needing to reduce the particle size. The proposed thesis focused on in-depth investigations of microwave pyrolysis of corn residues. My first specific aim was to examine the effects of processing parameters on product yields. The second specific research aim was to characterize the products (gases, bio-oils, and solid residues), which was critical to process optimization and product developments. Other research tasks included conducting kinetic modeling and preliminary mass and energy balance. This study demonstrated that microwave pyrolysis could be optimized to produce high value syngas, liquid fuels and pyrolytic carbons, and had a great

Kinetic Modelling and Experimental Studies for the Effects of Fe2+ Ions on Xylan Hydrolysis with Dilute-Acid Pretreatment and Subsequent Enzymatic Hydrolysis

Directory of Open Access Journals (Sweden)

Hui Wei

2018-01-01

Full Text Available High-temperature (150–170 °C pretreatment of lignocellulosic biomass with mineral acids is well established for xylan breakdown. Fe2+ is known to be a cocatalyst of this process although kinetics of its action remains unknown. The present work addresses the effect of ferrous ion concentration on sugar yield and degradation product formation from corn stover for the entire two-step treatment, including the subsequent enzymatic cellulose hydrolysis. The feedstock was impregnated with 0.5% acid and 0.75 mM iron cocatalyst, which was found to be optimal in preliminary experiments. The detailed kinetic data of acid pretreatment, with and without iron, was satisfactorily modelled with a four-step linear sequence of first-order irreversible reactions accounting for the formation of xylooligomers, xylose and furfural as intermediates to provide the values of Arrhenius activation energy. Based on this kinetic modelling, Fe2+ turned out to accelerate all four reactions, with a significant alteration of the last two steps, that is, xylose degradation. Consistent with this model, the greatest xylan conversion occurred at the highest severity tested under 170 °C/30 min with 0.75 mM Fe2+, with a total of 8% xylan remaining in the pretreated solids, whereas the operational conditions leading to the highest xylose monomer yield, 63%, were milder, 150 °C with 0.75 mM Fe2+ for 20 min. Furthermore, the subsequent enzymatic hydrolysis with the prior addition of 0.75 mM of iron(II increased the glucose production to 56.3% from 46.3% in the control (iron-free acid. The detailed analysis indicated that conducting the process at lower temperatures yet long residence times benefits the yield of sugars. The above kinetic modelling results of Fe2+ accelerating all four reactions are in line with our previous mechanistic research showing that the pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C�

Conversing about Citrus Greening: Extension's Role in Educating about Genetic Modification Science as a Solution

Science.gov (United States)

Ruth, Taylor K.; Lamm, Alexa J.; Rumble, Joy N.; Ellis, Jason D.

2017-01-01

Extension agents across the nation will need to facilitate difficult conversations with the public if genetic modification (GM) science is used to combat citrus greening disease. This study used the innovation characteristics described by Rogers to explore if using GM science as a solution to citrus greening had diffused amongst US residents. An…

MAGNETIC NULL POINTS IN KINETIC SIMULATIONS OF SPACE PLASMAS

International Nuclear Information System (INIS)

Olshevsky, Vyacheslav; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni; Deca, Jan; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano

2016-01-01

We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind, and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3–9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their cross sections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data

Anesthesiology resident personality type correlates with faculty assessment of resident performance.

Science.gov (United States)

Schell, Randall M; Dilorenzo, Amy N; Li, Hsin-Fang; Fragneto, Regina Y; Bowe, Edwin A; Hessel, Eugene A

2012-11-01

To study the association between anesthesiology residents' personality preference types, faculty evaluations of residents' performance, and knowledge. Convenience sample and prospective study. Academic department of anesthesiology. Consenting anesthesiology residents (n = 36). All participants completed the Myers Briggs Type Indicator® (MBTI®). All residents' 6-month summation of daily focal evaluations completed by faculty [daily performance score (DPS); 1 = unsatisfactory, 2 = needs improvement, 3 = meets expectations, 4 = exceeds expectations], as well as a global assessment of performance (GAP) score based on placement of each resident into perceived quartile compared with their peers (ie,1 = first, or top, quartile) by senior faculty (n = 7) who also completed the MBTI, were obtained. The resident MBTI personality preferences were compared with the DPS and GAP scores, the United States Medical Licensing Examination (USMLE) I and II scores, and faculty MBTI personality type. There was no association between personality preference type and performance on standardized examinations (USMLE I, II). The mean GAP score was better (higher quartile score) for Extraverts than Introverts (median 2.0 vs 2.6, P = 0.0047) and for Sensing versus Intuition (median 2.0 vs 2.6, P = 0.0206) preference. Faculty evaluator MBTI preference type did not influence the GAP scores they assigned residents. Like GAP, the DPS was better for residents with Sensing versus Intuition preference (median 3.5 vs 3.3, P = 0.0111). No difference in DPS was noted between Extraverts and Introverts. Personality preference type was not associated with resident performance on standardized examinations, but it was associated with faculty evaluations of resident performance. Residents with Sensing personality preference were evaluated more favorably on global and focal faculty evaluations than those residents who chose the Intuition preference. Extraverted residents were evaluated more favorably on

The influence of gas–solid reaction kinetics in models of thermochemical heat storage under monotonic and cyclic loading

International Nuclear Information System (INIS)

Nagel, T.; Shao, H.; Roßkopf, C.; Linder, M.; Wörner, A.; Kolditz, O.

2014-01-01

Highlights: • Detailed analysis of cyclic and monotonic loading of thermochemical heat stores. • Fully coupled reactive heat and mass transport. • Reaction kinetics can be simplified in systems limited by heat transport. • Operating lines valid during monotonic and cyclic loading. • Local integral degree of conversion to capture heterogeneous material usage. - Abstract: Thermochemical reactions can be employed in heat storage devices. The choice of suitable reactive material pairs involves a thorough kinetic characterisation by, e.g., extensive thermogravimetric measurements. Before testing a material on a reactor level, simulations with models based on the Theory of Porous Media can be used to establish its suitability. The extent to which the accuracy of the kinetic model influences the results of such simulations is unknown yet fundamental to the validity of simulations based on chemical models of differing complexity. In this article we therefore compared simulation results on the reactor level based on an advanced kinetic characterisation of a calcium oxide/hydroxide system to those obtained by a simplified kinetic model. Since energy storage is often used for short term load buffering, the internal reactor behaviour is analysed under cyclic partial loading and unloading in addition to full monotonic charge/discharge operation. It was found that the predictions by both models were very similar qualitatively and quantitatively in terms of thermal power characteristics, conversion profiles, temperature output, reaction duration and pumping powers. Major differences were, however, observed for the reaction rate profiles themselves. We conclude that for systems not limited by kinetics the simplified model seems sufficient to estimate the reactor behaviour. The degree of material usage within the reactor was further shown to strongly vary under cyclic loading conditions and should be considered when designing systems for certain operating regimes

Uncovering the unknown: A grounded theory study exploring the impact of self-awareness on the culture of feedback in residency education

NARCIS (Netherlands)

Ramani, S.; Konings, K.; Mann, K.V.; Vleuten, C. van der

2017-01-01

AIM: Self-assessment and reflection are essential for meaningful feedback. We aimed to explore whether the well-known Johari window model of self-awareness could guide feedback conversations between faculty and residents and enhance the institutional feedback culture. METHODS: We had previously

Lymphocyte development in irradiated thymuses: dynamics of colonization by progenitor cells and regeneration of resident cells

International Nuclear Information System (INIS)

Mehr, R.; Fridkis-Hareli, M.; Abel, L.; Segel, L.; Globerson, A.

1995-01-01

Lymphocyte development in irradiated thymuses was analyzed using two complementary strategies: an in vitro experimental model and computer simulations. In the in vitro model, fetal thymus lobes were irradiated and the regeneration of cells that survived irradiation were examined, with the results compared to those of reconstitution of the thymus by donor bone marrow cells and their competition with the thymic resident cells. In vitro measurements of resident cell kinetics showed that cell proliferation is slowed down significantly after a relatively low (10Gy) irradiation dose. Although the number of thymocytes that survived irradiation remained low for several days post-irradiation, further colonization by donor cells was not possible, unless performed within 6 h after irradiation. These experimental results, coupled with the analysis by computer simulations, suggest that bone marrow cell engraftment in the irradiated thymus may be limited by the presence of radiation-surviving thymic resident cells and the reduced availability of seeding niches. (Author)

Kinetics of reaction of 1,10- decanedioland dimeric fatty acid C36

International Nuclear Information System (INIS)

Falah, A.

2013-01-01

Kinetic studies were carried out on the reaction between 1,10- Decanedioland dimeric fatty acid C 3 6 in melt phase. The reaction was performed at 140, 150, 160, 170, and 185 o C and followed by determining the acid value of the product. The polyesterfication reaction was found to be of overall second order with an activation energy of 39,91kj/mol up to (50, 44, 55,42, 63)% conversion at (140, 150, 160, 170, 185) o C and overall third order with an activation energy of 71.17 k j/ mol above (50, 44, 55, 42, 63)% conversion at (140, 150, 160, 170, 185) o C. The Degree of Polymerization, number average molecular weight and weight average molecular weight have been calculated during different times, the relationships between Degree of Polymerization, number average molecular weight, weight average molecular weight and the times is linear until, (50, 44, 55, 42, 63)%conversion at (140, 150, 160, 170, 185) o C. (author)

Mixtures of rubber tyre and plastic wastes pyrolysis: A kinetic study

International Nuclear Information System (INIS)

Miranda, Miguel; Cabrita, I.; Pinto, Filomena; Gulyurtlu, I.

2013-01-01

The study performed aimed at analysing possible routes for pyrolysis reaction mechanisms of polymeric materials namely RT (rubber tyre) and plastic wastes (PE (polyethylene), PP (polypropylene) and PS (polystyrene)). Consequently, and seeking sustainable transformation of waste streams into valuable chemicals and renewable liquid fuels, mixture of 30% RT, 20% PE, 30% PP and 20% PS was subjected to pyrolysis. Different kinetic models were studied using experimental data. None of the mechanisms found in literature led to a numerical adjustment and different pathways were investigated. Kinetic studies were performed aiming to evaluate direct conversions into new solid, liquid and gaseous products and if parallel reactions and/or reversible elementary steps should be included. Experiments were performed in batch system at different temperatures and reaction times. Kinetic models were evaluated and reaction pathways were proposed. Models reasonably fit experimental data, allow explaining wastes thermal degradation. Kinetic parameters were estimated for all temperatures and dependence of Ea and pre-exponential factor on temperature was evaluated. The rate constant of some reactions exhibited nonlinear temperature dependence on the logarithmic form of Arrhenius law. This fact strongly suggests that temperature has a significant effect on reaction mechanism of pyrolysis of mixtures of rubber tyre and plastic wastes. - Highlights: • Kinetic study of rubber tyre (RT) and different plastic wastes (PE, PP and PS) was performed in batch reactor. • Definition of possible pathways taken into account for the formation of final products. • Kinetic parameters were estimated. • The effect of reaction temperature and reaction time on liquid composition was performed

Measuring resident well-being: impostorism and burnout syndrome in residency.

Science.gov (United States)

Legassie, Jenny; Zibrowski, Elaine M; Goldszmidt, Mark A

2008-07-01

Assessing resident well-being is becoming increasingly important from a programmatic standpoint. Two measures that have been used to assess this are the Clance Impostor Scale (CIS) and the Maslach Burnout Inventory-Human Services Survey (MBI-HSS). However, little is known about the relationship between the two phenomena. To explore the prevalence and association between impostorism and burnout syndrome in a sample of internal medicine residents. Anonymous, cross-sectional postal survey. Forty-eight internal medicine residents (postgraduate year [PGY] 1-3) at the Schulich School of Medicine & Dentistry (62.3% response rate). Short demographic questionnaire, CIS and MBI-HSS. Impostorism and burnout syndrome were identified in 43.8% and 12.5% of residents, respectively. With the exception of a negative correlation between CIS scores and the MBI's personal accomplishment subscale (r = -.30; 95% CI -.54 to -.02), no other significant relations were identified. Foreign-trained residents were more likely to score as impostors (odds ratio [OR] 10.7; 95% CI 1.2 to 98.2) while senior residents were more likely to experience burnout syndrome (OR 16.5 95% CI 1.6 to 168.5). Both impostorism and burnout syndrome appear to be threats to resident well-being in our program. The lack of relationship between the two would suggest that programs and researchers wishing to address the issue of resident distress should consider using both measures. The finding that foreign-trained residents appear to be more susceptible to impostorism warrants further study.

The production of sinterable UO2 from AUC

International Nuclear Information System (INIS)

Chang, I.S.; Do, J.B.; Choi, Y.D.; Park, M.H.; Yun, H.H.; Kim, E.H.; Kim, Y.W.

1982-01-01

Fluidization, feeding and discharging, and mixing of fine particles (-up to 40μ in diameter) in fluidized bed reactor has been examined. The degree of conversion has been estimated using the kinetic data differential scanning colorimetry(DSC) and thermogravimetic analysis (TGA) of ammonium uranyl carbonate (AUC) and residence time distribution data. Satisfactory operation is obtained with a sintered ceramic distributor and filters. The reactor equilvalent to approximately 1.1-1.3 stages. Thermal analysis of AUC in hydrogen atmosphere shows that the decomposition of AUC to UO 3 at 200degC is followed by reduction of UO 3 to UO 2 in two steps in the range between 400degC and 500degC and the complete conversion to UO 2 takes two minutes at 550degC. The overall conversion of above 99.5% in the fluidized bed reactor is estimated with 40 minutes of a mean particle residence time at 600degC. (Author)

Small-scale semi-continuous reactor for the conversion of wood to fuel oil

Energy Technology Data Exchange (ETDEWEB)

Eager, R L; Pepper, J M; Mathews, J F

1983-04-01

The design and operation of a small-scale semi-continuous reactor to convert aspen wood meal into an oil product is described. Modifications that reduce erosion/corrosion are also presented. Short residence times and relatively low operating pressures have been achieved for the reaction of aspen with CO and H2O in the presence of Na2CO3. Conversions, char formation, and the effect of sodium carbonate concentration on oil product are reported.

Energy conversion and dissipation at dipolarization fronts: Theory, modeling and MMS observations

Science.gov (United States)

Sitnov, M. I.; Motoba, T.; Merkin, V. G.; Ohtani, S.; Cohen, I. J.; Mauk, B.; Vines, S. K.; Anderson, B. J.; Moore, T. E.; Torbert, R. B.; Giles, B. L.; Burch, J. L.

2017-12-01

Magnetic reconnection is one of the most important energy conversion mechanisms in space plasmas. In the classical picture it converts the energy of antiparallel magnetic fields into the kinetic and thermal energy of accelerated plasma particles in reconnection exhausts. It also involves energy dissipation near the X-line. This classical picture may be substantially modified in real space plasma configurations, such as the dayside magnetopause and the magnetotail. In particular, in the magnetotail the flows of accelerated particles may be strongly asymmetric along the tail with the domination of earthward flows. At the same time, strong energy conversion and even dissipation may occur away from the X-line, in particular, at dipolarization fronts. Here we present a theoretical picture of spontaneous magnetotail reconnection based on 3-D PIC simulations with the focus on plasma bulk flows, energy conversion and dissipation. This picture is compared with some observations from the MMS tail season. An important finding from these observations is that dipolarizations fronts may not only be regions of the total energy conversion with jE>0, but they may also be the sites of energy dissipation, both positive (jE'>0, E' is the electric field E in the system moving with one of the plasma species) and negative (jE'braking).

Magnetic reconnection in Earth's magnetotail: Energy conversion and its earthward-tailward asymmetry

Science.gov (United States)

Lu, San; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A. V.

2018-01-01

Magnetic reconnection, a fundamental plasma process, releases magnetic energy and converts it to particle energy, by accelerating and heating ions and electrons. This energy conversion plays an important role in the Earth's magnetotail. A two-dimensional particle-in-cell simulation is performed to study such a conversion in a magnetotail topology, one with a nonzero Bz, and the energy conversion is found to be more efficient in the earthward outflow than in the tailward outflow. Such earthward-tailward asymmetry is manifested not only in j .E but also in Poynting flux, Hall electromagnetic fields, bulk kinetic energy flux, enthalpy flux, heat flux, bulk acceleration, heating, and suprathermal particle energization, all of which are more prevalent on the earthward side. Such asymmetries are consistent with spacecraft observations reported in the literature. Our study shows that in the magnetotail, most of the energy converted by reconnection flows predominantly toward the Earth and has the potential of being geoeffective, rather than being expelled to the solar wind by the tailward flow. The energy conversion asymmetry arises from the presence of the non-zero normal magnetic field, the stronger lobe magnetic field, and the stronger cross-tail current earthward of the reconnection site in the pre-reconnecting thin current sheet.

Applying Expectancy Theory to residency training: proposing opportunities to understand resident motivation and enhance residency training

Directory of Open Access Journals (Sweden)

Shweiki E

2015-04-01

Full Text Available Ehyal Shweiki,1 Niels D Martin,2 Alec C Beekley,1 Jay S Jenoff,1 George J Koenig,1 Kris R Kaulback,1 Gary A Lindenbaum,1 Pankaj H Patel,1 Matthew M Rosen,1 Michael S Weinstein,1 Muhammad H Zubair,2 Murray J Cohen1 1Department of Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA; 2Department of Surgery, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA Abstract: Medical resident education in the United States has been a matter of national priority for decades, exemplified initially through the Liaison Committee for Graduate Medical Education and then superseded by the Accreditation Council for Graduate Medical Education. A recent Special Report in the New England Journal of Medicine, however, has described resident educational programs to date as prescriptive, noting an absence of innovation in education. Current aims of contemporary medical resident education are thus being directed at ensuring quality in learning as well as in patient care. Achievement and work-motivation theories attempt to explain people's choice, performance, and persistence in tasks. Expectancy Theory as one such theory was reviewed in detail, appearing particularly applicable to surgical residency training. Correlations between Expectancy Theory as a work-motivation theory and residency education were explored. Understanding achievement and work-motivation theories affords an opportunity to gain insight into resident motivation in training. The application of Expectancy Theory in particular provides an innovative perspective into residency education. Afforded are opportunities to promote the development of programmatic methods facilitating surgical resident motivation in education. Keywords: learning, education, achievement

Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

KAUST Repository

Takanabe, Kazuhiro

2012-01-01

Natural gas conversion remains one of the essential technologies for current energy needs. This review focuses on the mechanistic aspects of the development of efficient and durable catalysts for two reactions, carbon dioxide reforming and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would support the design of industrial catalysts. CO 2 reforming of methane utilizes CO 2, which is often stored in large quantities, to convert as a reactant. Strategies to eliminate carbon deposition, which is the major problem associated with this reaction, are discussed. The oxidative coupling of methane directly produces ethylene in one reactor through a slightly exothermic reaction, potentially minimizing the capital cost of the natural gas conversion process. The focus of discussion in this review will be on the attainable yield of C 2 products by rigorous kinetic analyses.

Kinetic study of enzymatic hydrolysis of potato starch

Directory of Open Access Journals (Sweden)

Óscar Fernando Castellanos Domínguez

2004-01-01

Full Text Available This article describes the kinetic study of potato starch enzymatic hydrolysis using soluble enzymes (Novo Nordisk. Different assays divided into four groups were used: reaction time (with which it was possible to reduce the 48-72 hour duration reported in the literature to 16 hours with comparable productivity levels; selecting the set of enzymes to be used (different types were evaluated - BAN and Termamyl as alfa-amylases during dextrinisation stage, and AMG, Promozyme and Fungamyl for sacarification reaction- identifying those presenting the best performance during hydrolysis.Reaction conditions were optimised for the process's two stages (destrinisation and sacarification. Enzyme dose, calcium cofactor concentration, pH, temperature and agitation speed were studied for the first stage. Enzyme ratio, pH and agitation speed were studied for sacarification; the latter parameter reported values having no antecedents in the literature (60 rpm and 30 rpm for first and second reactions, respectively. Michaelis Menten kinetics were calculated once conditions had been optimised, varying substrate from 10-50% P/V, obtaining km and Vmax kinetic parameters for each reaction. A kinetic model was found according to local working conditions which was able to explain potato starch conversion to glucose syrup, achieving 96 dextrose equivalents by the end of the reaction, being well within the maximum range reported in the literature (94-98.Laboratory equipment was constructed prior to carrying out assays which was able to reproduce and improve the conditions reported in the literature, making it a useful, reliable tool for use in assays returning good results.

Does Residency Selection Criteria Predict Performance in Orthopaedic Surgery Residency?

Science.gov (United States)

Raman, Tina; Alrabaa, Rami George; Sood, Amit; Maloof, Paul; Benevenia, Joseph; Berberian, Wayne

2016-04-01

More than 1000 candidates applied for orthopaedic residency positions in 2014, and the competition is intense; approximately one-third of the candidates failed to secure a position in the match. However, the criteria used in the selection process often are subjective and studies have differed in terms of which criteria predict either objective measures or subjective ratings of resident performance by faculty. Do preresidency selection factors serve as predictors of success in residency? Specifically, we asked which preresidency selection factors are associated or correlated with (1) objective measures of resident knowledge and performance; and (2) subjective ratings by faculty. Charts of 60 orthopaedic residents from our institution were reviewed. Preresidency selection criteria examined included United States Medical Licensing Examination (USMLE) Step 1 and Step 2 scores, Medical College Admission Test (MCAT) scores, number of clinical clerkship honors, number of letters of recommendation, number of away rotations, Alpha Omega Alpha (AOA) honor medical society membership, fourth-year subinternship at our institution, and number of publications. Resident performance was assessed using objective measures including American Board of Orthopaedic Surgery (ABOS) Part I scores and Orthopaedics In-Training Exam (OITE) scores and subjective ratings by faculty including global evaluation scores and faculty rankings of residents. We tested associations between preresidency criteria and the subsequent objective and subjective metrics using linear correlation analysis and Mann-Whitney tests when appropriate. Objective measures of resident performance namely, ABOS Part I scores, had a moderate linear correlation with the USMLE Step 2 scores (r = 0.55, p communication skills" subsection of the global evaluations. We found that USMLE Step 2, number of honors in medical school clerkships, and AOA membership demonstrated the strongest correlations with resident performance. Our

Comparative evaluation of thermal oxidative decomposition for oil-plant residues via thermogravimetric analysis: Thermal conversion characteristics, kinetics, and thermodynamics.

Science.gov (United States)

Chen, Jianbiao; Wang, Yanhong; Lang, Xuemei; Ren, Xiu'e; Fan, Shuanshi

2017-11-01

Thermal oxidative decomposition characteristics, kinetics, and thermodynamics of rape straw (RS), rapeseed meal (RM), camellia seed shell (CS), and camellia seed meal (CM) were evaluated via thermogravimetric analysis (TGA). TG-DTG-DSC curves demonstrated that the combustion of oil-plant residues proceeded in three stages, including dehydration, release and combustion of organic volatiles, and chars oxidation. As revealed by combustion characteristic parameters, the ignition, burnout, and comprehensive combustion performance of residues were quite distinct from each other, and were improved by increasing heating rate. The kinetic parameters were determined by Coats-Redfern approach. The results showed that the most possible combustion mechanisms were order reaction models. The existence of kinetic compensation effect was clearly observed. The thermodynamic parameters (ΔH, ΔG, ΔS) at peak temperatures were calculated through the activated complex theory. With the combustion proceeding, the variation trends of ΔH, ΔG, and ΔS for RS (RM) similar to those for CS (CM). Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation on CO catalytic oxidation reaction kinetics of faceted perovskite nanostructures loaded with Pt

KAUST Repository

Yin, S. M.

2017-01-18

Perovskite lead titanate nanostructures with specific {111}, {100} and {001} facets exposed, have been employed as supports to investigate the crystal facet effect on the growth and CO catalytic activity of Pt nanoparticles. The size, distribution and surface chemical states of Pt on the perovskite supports have been significantly modified, leading to a tailored conversion temperature and catalytic kinetics towards CO catalytic oxidation.

Investigation on CO catalytic oxidation reaction kinetics of faceted perovskite nanostructures loaded with Pt

KAUST Repository

Yin, S. M.; Duanmu, J. J.; Zhu, Yihan; Yuan, Y. F.; Guo, S. Y.; Yang, J. L.; Ren, Z. H.; Han, G. R.

2017-01-01

Perovskite lead titanate nanostructures with specific {111}, {100} and {001} facets exposed, have been employed as supports to investigate the crystal facet effect on the growth and CO catalytic activity of Pt nanoparticles. The size, distribution and surface chemical states of Pt on the perovskite supports have been significantly modified, leading to a tailored conversion temperature and catalytic kinetics towards CO catalytic oxidation.

Non-kinetic capabilities: complementing the kinetic prevalence to targeting

OpenAIRE

Ducheine, P.

2014-01-01

Targeting is used in military doctrine to describe a military operational way, using (military) means to influence a target (or addressee) in order to achieve designated political and/or military goals. The four factors italicized are used to analyse non-kinetic targeting, complementing our knowledge and understanding of the kinetic prevalence. Paradoxically, non-kinetic targeting is not recognized as a separate concept: kinetic and non-kinetic are intertwined facets of targeting. Kinetic tar...

Roles of kinetics and energetics in the growth of AlN by plasma-assisted molecular beam epitaxy

International Nuclear Information System (INIS)

Im, I. H.; Minegishi, T.; Hanada, T.; Lee, S. W.; Cho, M. W.; Yao, T.; Oh, D. C.; Chang, J. H.

2006-01-01

The roles of kinetics and energetics in the growth processes of AlN on c-sapphire by plasma assisted molecular beam epitaxy are investigated by varying the growth rate from 1 to 31 A/min and the substrate temperature from 800 to 1000 .deg. C. The energetics is found to govern the growth of AlN in the low-growth rate region even at a low substrate temperature of 800 .deg. C owing to the enhanced residence time of adatoms, thereby increasing the surface migration length. As the growth rate increases, the growth tends to be governed by kinetics because of a reduction in the residence time of adatoms. Consequently, the surface roughness and crystal quality are greatly improved for the low-growth-rate case. In addition, the lattice strain relaxation is completed from the beginning of epitaxy for energetics-limiting growth while lattice strain relaxation is retarded for kinetics-limiting growth because of pre-existing partial strain relaxation. Energetics becomes more favorable as the substrate temperature is raised because of an increase in the surface diffusion length owing to an enhanced diffusion coefficient. Consequently high-crystal-quality AlN layers are grown under the energetics-limiting growth condition with a screw dislocation density of 7.4 x 10 8 cm -2 even for a thin 42-nm thick film.

Needs Assessment for Incoming PGY-1 Residents in Neurosurgical Residency.

Science.gov (United States)

Brandman, David M; Haji, Faizal A; Matte, Marie C; Clarke, David B

2015-01-01

Residents must develop a diverse range of skills in order to practice neurosurgery safely and effectively. The purpose of this study was to identify the foundational skills required for neurosurgical trainees as they transition from medical school to residency. Based on the CanMEDS competency framework, a web-based survey was distributed to all Canadian academic neurosurgical centers, targeting incoming and current PGY-1 neurosurgical residents as well as program directors. Using Likert scale and free-text responses, respondents rated the importance of various cognitive (e.g. management of raised intracranial pressure), technical (e.g. performing a lumbar puncture) and behavioral skills (e.g. obtaining informed consent) required for a PGY-1 neurosurgical resident. Of 52 individuals contacted, 38 responses were received. Of these, 10 were from program directors (71%), 11 from current PGY-1 residents (58%) and 17 from incoming PGY-1 residents (89%). Respondents emphasized operative skills such as proper sterile technique and patient positioning; clinical skills such as lesion localization and interpreting neuro-imaging; management skills for common scenarios such as raised intracranial pressure and status epilepticus; and technical skills such as lumbar puncture and external ventricular drain placement. Free text answers were concordant with the Likert scale results. We surveyed Canadian neurosurgical program directors and PGY-1 residents to identify areas perceived as foundational to neurosurgical residency education and training. This information is valuable for evaluating the appropriateness of a training program's goals and objectives, as well as for generating a national educational curriculum for incoming PGY-1 residents.

Steam cracking of hydrocarbons 6. Effect of dibenzyl sulfide and dibenzyl disulfide on reaction kinetics and coking

NARCIS (Netherlands)

Bajus, M.; Baxa, J.; Leclercq, P.A.; Rijks, J.A.

1983-01-01

The influence of aromatic sulfides on the kinetics and selectivity of hydrocarbon conversion by steam cracking and on pyrolytic coke formation was investigated in stainless steel tubular reactors with relatively large inner surface.The rate of decomposition of heptane (at 700 ‘C, 100 kPa, and a mass

Synthesis of Prebiotic Caramels Catalyzed by Ion-Exchange Resin Particles: Kinetic Model for the Formation of Di-d-fructose Dianhydrides.

Science.gov (United States)

Ortiz Cerda, Imelda-Elizabeth; Thammavong, Phahath; Caqueret, Vincent; Porte, Catherine; Mabille, Isabelle; Garcia Fernandez, José Manuel; Moscosa Santillan, Mario; Havet, Jean-Louis

2018-02-21

Caramel enriched in di-d-fructose dianhydrides (DFAs, a family of prebiotic cyclic fructodisaccharides) is a functional food with beneficial properties for health. The aim of this work was to study the conversion of fructose into DFAs catalyzed by acid ion-exchange resin, in order to establish a simplified mechanism of the caramelization reaction and a kinetic model for DFA formation. Batch reactor experiments were carried out in a 250 mL spherical glass flask and afforded up to 50% DFA yields. The mechanism proposed entails order 2 reactions that describe fructose conversion on DFAs or formation of byproducts such as HMF or melanoidines. A third order 1 reaction defines DFA transformation into fructosyl-DFAs or fructo-oligosaccharides. The influence of fructose concentration, resin loading and temperature was studied to calculate the kinetic parameters necessary to scale up the process.

Influence of vegetable oils fatty acid composition on reaction temperature and glycerides conversion to biodiesel during transesterification.

Science.gov (United States)

Pinzi, S; Gandía, L M; Arzamendi, G; Ruiz, J J; Dorado, M P

2011-01-01

Presence of unreacted glycerides in biodiesel may reduce drastically its quality. This is why conversion of raw material in biodiesel through transesterification needs to readjust reaction parameter values to complete. In the present work, monitoring of glycerides transformation in biodiesel during the transesterification of vegetable oils was carried out. To check the influence of the chemical composition on glycerides conversion, selected vegetable oils covered a wide range of fatty acid composition. Reactions were carried out under alkali-transesterification in the presence of methanol. In addition, a multiple regression model was proposed. Results showed that kinetics depends on chemical and physical properties of the oils. It was found that the optimal reaction temperature depends on both length and unsaturation degree of vegetable oils fatty acid chains. Vegetable oils with higher degree of unsaturation exhibit faster monoglycerides conversion to biodiesel. It can be concluded that fatty acid composition influences reaction parameters and glycerides conversion, hence biodiesel yield and economic viability. Copyright © 2010 Elsevier Ltd. All rights reserved.

Continuous production of biodiesel under supercritical methyl acetate conditions: Experimental investigation and kinetic model.

Science.gov (United States)

Farobie, Obie; Matsumura, Yukihiko

2017-10-01

In this study, biodiesel production by using supercritical methyl acetate in a continuous flow reactor was investigated for the first time. The aim of this study was to elucidate the reaction kinetics of biodiesel production by using supercritical methyl. Experiments were conducted at various reaction temperatures (300-400°C), residence times (5-30min), oil-to-methyl acetate molar ratio of 1:40, and a fixed pressure of 20MPa. Reaction kinetics of biodiesel production with supercritical methyl acetate was determined. Finally, biodiesel yield obtained from this method was compared to that obtained with supercritical methanol, ethanol, and MTBE (methyl tertiary-butyl ether). The results showed that biodiesel yield with supercritical methyl acetate increased with temperature and time. The developed kinetic model was found to fit the experimental data well. The reactivity of supercritical methyl acetate was the lowest, followed by that of supercritical MTBE, ethanol, and methanol, under the same conditions. Copyright © 2017. Published by Elsevier Ltd.

Catalytic Conversion of Biomass to Fuels and Chemicals Using Ionic Liquids

Energy Technology Data Exchange (ETDEWEB)

Liu, Wei; Zheng, Richard; Brown, Heather; Li, Joanne; Holladay, John; Cooper, Alan; Rao, Tony

2012-04-13

This project provides critical innovations and fundamental understandings that enable development of an economically-viable process for catalytic conversion of biomass (sugar) to 5-hydroxymethylfurfural (HMF). A low-cost ionic liquid (Cyphos 106) is discovered for fast conversion of fructose into HMF under moderate reaction conditions without any catalyst. HMF yield from fructose is almost 100% on the carbon molar basis. Adsorbent materials and adsorption process are invented and demonstrated for separation of 99% pure HMF product and recovery of the ionic liquid from the reaction mixtures. The adsorbent material appears very stable in repeated adsorption/regeneration cycles. Novel membrane-coated adsorbent particles are made and demonstrated to achieve excellent adsorption separation performances at low pressure drops. This is very important for a practical adsorption process because ionic liquids are known of high viscosity. Nearly 100% conversion (or dissolution) of cellulose in the catalytic ionic liquid into small molecules was observed. It is promising to produce HMF, sugars and other fermentable species directly from cellulose feedstock. However, several gaps were identified and could not be resolved in this project. Reaction and separation tests at larger scales are needed to minimize impacts of incidental errors on the mass balance and to show 99.9% ionic liquid recovery. The cellulose reaction tests were troubled with poor reproducibility. Further studies on cellulose conversion in ionic liquids under better controlled conditions are necessary to delineate reaction products, dissolution kinetics, effects of mass and heat transfer in the reactor on conversion, and separation of final reaction mixtures.

Crystallization Kinetics of Precipitating Calcium from Yellow Phosphorus Slag Lixivium

Directory of Open Access Journals (Sweden)

Li, G. -B.

2014-11-01

Full Text Available The crystallization dynamic parameters of calcium sulphate were determined in the course of the precipitation conversion process of calcium in lixivium. The crystallization dynamic equations of calcium sulphate were achieved by multiple linear regression. The study results indicate that CaSO4 · 2 H2O crystal nucleation-growth kinetics equation in nitric acid leaching liquid of yellow phosphorus slag at room temperature is expressed by B0 = 2.904 · 1011 · G0.83 · MT 0.167.

Elective time during dermatology residency: A survey of residents and program directors.

Science.gov (United States)

Uppal, Pushpinder; Shantharam, Rohini; Kaufmann, Tara Lynn

2017-12-15

Elective time during residency training provides residents with exposure to different subspecialties. This opportunity gives residents the chance tonurture growth in particular areas of interest and broaden their knowledge base in certain topics in dermatology by having the chance to work withexperts in the field. The purpose of this study was to assess the views of residency program directors and dermatology residents on the value of elective time through a cross sectional survey. An eight-questionIRB exempt survey was sent out to 113 residency program directors via email through the American Professors of Dermatology (APD) program director listserv. Program directors were asked to forward a separate set of 9 questions to their residents. The majority of programs that responded allowed for some elective time within their schedule, often duringthe PGY 4 (3rd year of dermatology training), but the amount of time allowed widely varied among many residency programs. Overall, residents and program directors agree that elective is important in residencytraining, but no standardization is established across programs.

Longitudinal density modulation and energy conversion in intense beams

International Nuclear Information System (INIS)

Harris, J. R.; Neumann, J. G.; Tian, K.; O'Shea, P. G.

2007-01-01

Density modulation of charged particle beams may occur as a consequence of deliberate action, or may occur inadvertently because of imperfections in the particle source or acceleration method. In the case of intense beams, where space charge and external focusing govern the beam dynamics, density modulation may, under some circumstances, be converted to velocity modulation, with a corresponding conversion of potential energy to kinetic energy. Whether this will occur depends on the properties of the beam and the initial modulation. This paper describes the evolution of discrete and continuous density modulations on intense beams and discusses three recent experiments related to the dynamics of density-modulated electron beams

Kinetics of Waterborne Alkyd/Acrylic Hybrid Resin Free Radical Polymerization by Two Systems of Redox and Thermal Initiators

Directory of Open Access Journals (Sweden)

shirin Madadi

2012-12-01

Full Text Available Kinetics of radical polymerizations of waterborne alkyd/acrylic hybrid resin via batch mini-emulsion technique was studied using redox initiators (TBHP/Fe2+/EDTA/AsAc  and  TBHP/Fe2+/EDTA/SFS at relatively low temperatures and thermal initiators (BPO, KPS and AIBN at higher temperatures to seek the most suitable initiator system. At the end of all reactions the unreacted monomer content was reduced using post-polymerization technique; consequently, leading to increased monomer conversion and flm formation with improved properties. The kinetics of mini-emulsion polymerization showed that in all redox initiator systems (Fe2+ catalyst + EDTA chelating agent, the radials are produced at relatively low temperature with more effcient control of the reactor temperature. It was found that at 45°C TBHP/Fe2+/EDTA/SFS redox initiator system leads to 98% monomer conversion, a much higher rate than that of systems involved thermal initiators.

Factors influencing photo curing kinetics of novel UV-cured siloxane-modified acrylic coatings: Oxygen inhibition and composition

International Nuclear Information System (INIS)

Esposito Corcione, Carola; Frigione, Mariaenrica

2012-01-01

Highlights: ► The inhibition effect of oxygen on the kinetic behaviour of photopolymerizable siloxane acrylic formulations was analyzed by thermal analysis. ► The addition of a thiol in the mixtures allows to obtain higher conversion, to reduce the content of the UV initiator and to increase the T g . ► The data found in air were fitted as a function of the presence of the thiol monomer obtaining a good agreement. - Abstract: An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings of stone substrates. The kinetics of the radical photopolymerization mechanism induced by UV radiations in presence of a suitable photoinitiator was studied by a calorimetric analysis by varying the atmosphere (oxygen or nitrogen) and the composition of the mixtures, in particular of the UV photoinitiator. The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free radical polymerization. The addition of a proper thiol to the acrylic modified resin was found to reduce the adverse effect of oxygen on the kinetic reaction and on the degree of conversion. This result allowed to reduce the content of the photoinitiator and to increase the content of the siloxane in the acrylic based mixtures. The effect of the change of the composition of the formulations on the kinetic behaviour of the acrylic based resins was also analysed by calorimetric analysis. Calorimetric experimental data were fitted to a simple kinetic model for radical photopolymerization reactions. Finally, a proper relationship between the glass transition temperature and the total extent of reaction was applied to the experimental data. A good agreement between the experimental data and both the theoretical models was generally

Decomposing Fuel Economy and Greenhouse Gas Regulatory Standards in the Energy Conversion Efficiency and Tractive Energy Domain

Energy Technology Data Exchange (ETDEWEB)

Pannone, Greg [Novation Analytics; Thomas, John F [ORNL; Reale, Michael [Novation Analytics; Betz, Brian [Novation Analytics

2017-01-01

The three foundational elements that determine mobile source energy use and tailpipe carbon dioxide (CO2) emissions are the tractive energy requirements of the vehicle, the on-cycle energy conversion efficiency of the propulsion system, and the energy source. The tractive energy requirements are determined by the vehicle's mass, aerodynamic drag, tire rolling resistance, and parasitic drag. Oncycle energy conversion of the propulsion system is dictated by the tractive efficiency, non-tractive energy use, kinetic energy recovery, and parasitic losses. The energy source determines the mobile source CO2 emissions. For current vehicles, tractive energy requirements and overall energy conversion efficiency are readily available from the decomposition of test data. For future applications, plausible levels of mass reduction, aerodynamic drag improvements, and tire rolling resistance can be transposed into the tractive energy domain. Similarly, by combining thermodynamic, mechanical efficiency, and kinetic energy recovery fundamentals with logical proxies, achievable levels of energy conversion efficiency can be established to allow for the evaluation of future powertrain requirements. Combining the plausible levels of tractive energy and on-cycle efficiency provides a means to compute sustainable vehicle and propulsion system scenarios that can achieve future regulations. Using these principles, the regulations established in the United States (U.S.) for fuel consumption and CO2 emissions are evaluated. Fleet-level scenarios are generated and compared to the technology deployment assumptions made during rule-making. When compared to the rule-making assumptions, the results indicate that a greater level of advanced vehicle and propulsion system technology deployment will be required to achieve the model year 2025 U.S. standards for fuel economy and CO2 emissions.

Prediction of Non-Equilibrium Kinetics of Fuel-Rich Kerosene/LOX Combustion in Gas Generator

International Nuclear Information System (INIS)

Yu, Jung Min; Lee, Chang Jin

2007-01-01

Gas generator is the device to produce high enthalpy gases needed to drive turbo-pump system in liquid rocket engine. And, the combustion temperature in gas generator should be controlled below around 1,000K to avoid any possible thermal damages to turbine blade by using either fuel rich combustion or oxidizer rich combustion. Thus, nonequilibrium chemical reaction dominates in fuel-rich combustion of gas generator. Meanwhile, kerosene is a compounded fuel with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focuses on the prediction of the non-equilibrium reaction of fuel rich kerosene/LOX combustion with detailed kinetics developed by Dagaut using PSR (Perfectly Stirred Reactor) assumption. In Dagaut's surrogate model for kerosene, chemical kinetics of kerosene consists of 1,592 reaction steps with 207 chemical species. Also, droplet evaporation time is taken into account in the PSR calculation by changing the residence time of droplet in the gas generator. Frenklach's soot model was implemented along with detailed kinetics to calculate the gas properties of fuel rich combustion efflux. The results could provide very reliable and accurate numbers in the prediction of combustion gas temperature,species fraction and material properties

Plasma kinetics of 125I beta endorphin turnover in lean and obese Zucker rats

International Nuclear Information System (INIS)

Rodd, D.; Caston, A.L.; Green, M.H.; Farrell, P.A.

1990-01-01

Plasma clearance kinetics for Beta Endorphin (BEP) are not well-defined and no definitive data exist for lean versus obese animals. To determine such kinetic parameters, a bolus of 125 I BEP (1μCi/kg) was infused into awake lean(L) and obese(O) Zucker rats. Arterial blood samples were withdrawn initially at 20 seconds intervals and less frequently as a 3-hour experimental period progressed. Donor rat blood was infused (venous catheter) to replace withdrawn blood. At 180 minutes approximately 10% of the initial dose remained in the plasma. Clearance kinetics for 125 I BEP were analyzed by compartmental analysis. A 3-component equation (i.e., 3 compartment model) provided the best fit for both L and O groups. Plasma transit times were very rapid; however, plasma fractional catabolic rate was low. Plasma mean residence time was similar for both groups (50 minutes) as was recycle time. These data suggest that BEP kinetics are similar in L and O rats, and that this peptide may undergo extensive recycling into and out of the plasma compartment. The identity of the other two compartments requires further investigation

Pediatric dermatology training during residency: a survey of the 2014 graduating residents.

Science.gov (United States)

Akhavan, Alaleh; Murphy-Chutorian, Blair; Friedman, Adam

2015-01-01

Knowledge of pediatric dermatology is considered a core competency of dermatology training and should be expected of all practicing dermatologists. While the numbers of both pediatric dermatology fellowships and board certified pediatric dermatologists in the workforce have increased over the years, recent reports suggest that there is a gap in pediatric dermatology education during dermatology residency. The goal of this study is to assess the current state of pediatric education during residency, as well as the clinical experience, satisfaction and expectations of graduating dermatology residents. A 31-question self-report survey was distributed electronically to 294 third-year dermatology residents with questions pertaining to demographics, didactic education, resident experience in pediatric dermatology training, satisfaction with pediatric training and future plans. One hundred and twenty-three residents responded (41.8% response rate) representing approximately 29.1% of the total number of graduating residents. 69 (56.1%) residents reported academic time specifically devoted to pediatric dermatology, the majority (79.7%) of which was led by pediatric dermatologists. 82% of residents reported dedicated pediatric dermatology clinics at their program. 86.8% of respondents felt that their training in pediatric dermatology will allow them to confidently see pediatric dermatology patients in practice. This survey highlights a promising state of pediatric dermatology training among current graduating dermatology residents. The majority of current graduating dermatology residents are satisfied with their pediatric dermatology education, feel confident treating pediatric patients, and plan to see pediatric patients in clinical practice. © 2015 Wiley Periodicals, Inc.

Kinetics study of the fluorination of uranium tetrafluoride in a fluidized bed reactor

International Nuclear Information System (INIS)

Khani, M.H.; Pahlavanzadeh, H.; Ghannadi, M.

2008-01-01

The kinetics of reaction of the uranium tetrafluoride conversion to the uranium hexafluoride with fluorine gas taking place in a fluidized bed reactor operating in industrial conditions have been studied. The external and internal diffusion effects are investigated by Mears and Weisz-Prater criterions. The kinetic equation for the fluorination of uranium tetrafluoride is developed in the absence of diffusional limitation using an integral method by assuming that the gas flow is of plug or perfectly mixed type. A good agreement is observed between the experimental data and a first-order model with respect to fluorine in the CSTR system. The activation energy of the reaction and the pre-exponential factor are obtained using analytical results from a better model

Selection criteria of residents for residency programs in Kuwait.

Science.gov (United States)

Marwan, Yousef; Ayed, Adel

2013-01-19

In Kuwait, 21 residency training programs were offered in the year 2011; however, no data is available regarding the criteria of selecting residents for these programs. This study aims to provide information about the importance of these criteria. A self-administered questionnaire was used to collect data from members (e.g. chairmen, directors, assistants …etc.) of residency programs in Kuwait. A total of 108 members were invited to participate. They were asked to rate the importance level (scale from 1 to 5) of criteria that may affect the acceptance of an applicant to their residency programs. Average scores were calculated for each criterion. Of the 108 members invited to participate, only 12 (11.1%) declined to participate. Interview performance was ranked as the most important criteria for selecting residents (average score: 4.63/5.00), followed by grade point average (average score: 3.78/5.00) and honors during medical school (average score: 3.67/5.00). On the other hand, receiving disciplinary action during medical school and failure in a required clerkship were considered as the most concerning among other criteria used to reject applicants (average scores: 3.83/5.00 and 3.54/5.00 respectively). Minor differences regarding the importance level of each criterion were noted across different programs. This study provided general information about the criteria that are used to accept/reject applicants to residency programs in Kuwait. Future studies should be conducted to investigate each criterion individually, and to assess if these criteria are related to residents' success during their training.

Towards an efficient conversion of ethanol in low temperature fuel cells

Energy Technology Data Exchange (ETDEWEB)

Rao, Vineet [Technische Universitaet Muenchen, Physik Department E19, James-Franck-Str. 1, D-85747 Garching (Germany); Stimming, Ulrich [Technische Universitaet Muenchen, Physik Department E19, James-Franck-Str. 1, D-85747 Garching (Germany); ZAE Bayern, Abteilung 1, Walther-Meissner-Str. 6, D-85748 Garching (Germany)

2009-07-01

Direct conversion of ethanol in low temperature fuel cells is a major goal in the development of fuel cells. Advantages of ethanol are its availability from biomass and the high energy density of such liquid fuel. Nevertheless, a major drawback is the incomplete oxidation of ethanol. Recent research focused mainly on novel catalyst materials for the ethanol oxidation reaction (EOR) based on e.g. Pt-Sn. Furthermore, some groups have carried out tests on solid OH- ion exchange membrane fuel cells. Better kinetics of fuel cell processes in such exchange membrane fuel cells could allow using also higher alcohols as fuel. Ethanol has slower kinetics of oxidation in acidic media and several by-products are formed because of incomplete oxidation. In our studies we investigated EOR in alkaline membrane electrode assemblies (MEA). Here, ethanol undergoes significantly more complete electro-oxidation to CO{sub 2} than in case of acidic MEA with same Pt anode.

Process for the aerobic conversion of poultry manure into high-protein feedstuff

Energy Technology Data Exchange (ETDEWEB)

Shuler, M.L.; Roberts, E.D.; Mitchell, D.W.; Kargi, F.; Austic, R.E.; Henry, A.; Vashon, R.; Seeley, H.W. Jr.

1979-01-01

A two-stage aerobic continuous process is suggested for the conversion of poultry waste into a single-cell protein (SCP) product. The technical feasibility of the process is examined in this paper. Using bench-scale apparatus the approximate growth kinetics have been discovered. Possible modes of product recovery have been examined. The product consists primarily of a strain of Pseudomonas fluorescens which has a lysine-rich (approx. 9.3%) amino acid profile that could make this product an attractive feed ingredient for poultry diets.

Comparative evaluation of kinetic, equilibrium and semi-equilibrium models for biomass gasification

Energy Technology Data Exchange (ETDEWEB)

Buragohain, Buljit [Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Chakma, Sankar; Kumar, Peeush [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Mahanta, Pinakeswar [Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Moholkar, Vijayanand S. [Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India)

2013-07-01

Modeling of biomass gasification has been an active area of research for past two decades. In the published literature, three approaches have been adopted for the modeling of this process, viz. thermodynamic equilibrium, semi-equilibrium and kinetic. In this paper, we have attempted to present a comparative assessment of these three types of models for predicting outcome of the gasification process in a circulating fluidized bed gasifier. Two model biomass, viz. rice husk and wood particles, have been chosen for analysis, with gasification medium being air. Although the trends in molar composition, net yield and LHV of the producer gas predicted by three models are in concurrence, significant quantitative difference is seen in the results. Due to rather slow kinetics of char gasification and tar oxidation, carbon conversion achieved in single pass of biomass through the gasifier, calculated using kinetic model, is quite low, which adversely affects the yield and LHV of the producer gas. Although equilibrium and semi-equilibrium models reveal relative insensitivity of producer gas characteristics towards temperature, the kinetic model shows significant effect of temperature on LHV of the gas at low air ratios. Kinetic models also reveal volume of the gasifier to be an insignificant parameter, as the net yield and LHV of the gas resulting from 6 m and 10 m riser is same. On a whole, the analysis presented in this paper indicates that thermodynamic models are useful tools for quantitative assessment of the gasification process, while kinetic models provide physically more realistic picture.

High-capacity lithium-ion battery conversion cathodes based on iron fluoride nanowires and insights into the conversion mechanism.

Science.gov (United States)

Li, Linsen; Meng, Fei; Jin, Song

2012-11-14

The increasing demands from large-scale energy applications call for the development of lithium-ion battery (LIB) electrode materials with high energy density. Earth abundant conversion cathode material iron trifluoride (FeF(3)) has a high theoretical capacity (712 mAh g(-1)) and the potential to double the energy density of the current cathode material based on lithium cobalt oxide. Such promise has not been fulfilled due to the nonoptimal material properties and poor kinetics of the electrochemical conversion reactions. Here, we report for the first time a high-capacity LIB cathode that is based on networks of FeF(3) nanowires (NWs) made via an inexpensive and scalable synthesis. The FeF(3) NW cathode yielded a discharge capacity as high as 543 mAh g(-1) at the first cycle and retained a capacity of 223 mAh g(-1) after 50 cycles at room temperature under the current of 50 mA g(-1). Moreover, high-resolution transmission electron microscopy revealed the existence of continuous networks of Fe in the lithiated FeF(3) NWs after discharging, which is likely an important factor for the observed improved electrochemical performance. The loss of active material (FeF(3)) caused by the increasingly ineffective reconversion process during charging was found to be a major factor responsible for the capacity loss upon cycling. With the advantages of low cost, large quantity, and ease of processing, these FeF(3) NWs are not only promising battery cathode materials but also provide a convenient platform for fundamental studies and further improving conversion cathodes in general.

Factors influencing resident's decision to reside in gated and guarded community

Science.gov (United States)

Shamsudin, Zarina; Shamsudin, Shafiza; Zainal, Rozlin

2017-10-01

Gated communities are residential areas developed with restricted access with strictly controlled entrances and surrounded by a close perimeter of wall or fences. Developers, conscious of the need to fulfill the requirement of living in modern and sophisticated lifestyle and gated properties become the trend and mushroomed over the past decade. Nowadays, it is obvious that gated and guarded communities become almost a dominant feature of Malaysia housing development projects. The focus of this paper is to identify the factors contribute resident's decision to reside in gated and guarded community and to study social interaction among gated communities' residents. 150 questionnaires were distributed to the residents of selected gated and guarded community area in order to achieve the objectives and analyzed by using Statistical Package for Social Science (SPSS) and descriptive analysis. The result was tabulated and presented in charts and graphs for a clear and better understanding. The five main factors contribute to resident decision to reside in gated communities were identified and ranked; there are privacy, security, location, lifestyle and prestige. Besides, the residents are feeling neutral towards the facilities and services provided in their gated and guarded residential area. A comprehensive improvement towards the facilities and services is needed to reach higher satisfaction from the residents.

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite

Institute of Scientific and Technical Information of China (English)

Jiangbo WANG; Zhong XIN

2009-01-01

The thermal degradation behaviors of poly-carbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy (E), in the case of isothermal degradation, was a quick increasing function of conversion (a) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.

Large impact of reorganization energy on photovoltaic conversion due to interfacial charge-transfer transitions.

Science.gov (United States)

Fujisawa, Jun-ichi

2015-05-14

Interfacial charge-transfer (ICT) transitions are expected to be a novel charge-separation mechanism for efficient photovoltaic conversion featuring one-step charge separation without energy loss. Photovoltaic conversion due to ICT transitions has been investigated using several TiO2-organic hybrid materials that show organic-to-inorganic ICT transitions in the visible region. In applications of ICT transitions to photovoltaic conversion, there is a significant problem that rapid carrier recombination is caused by organic-inorganic electronic coupling that is necessary for the ICT transitions. In order to solve this problem, in this work, I have theoretically studied light-to-current conversions due to the ICT transitions on the basis of the Marcus theory with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. An apparent correlation between the reported incident photon-to-current conversion efficiencies (IPCE) and calculated reorganization energies was clearly found, in which the IPCE increases with decreasing the reorganization energy consistent with the Marcus theory in the inverted region. This activation-energy dependence was systematically explained by the equation formulated by the Marcus theory based on a simple excited-state kinetic scheme. This result indicates that the reduction of the reorganization energy can suppress the carrier recombination and enhance the IPCE. The reorganization energy is predominantly governed by the structural change in the chemical-adsorption moiety between the ground and ICT excited states. This work provides crucial knowledge for efficient photovoltaic conversion due to ICT transitions.

Microstructure and corrosion resistance of Ce–V conversion coating on AZ31 magnesium alloy

International Nuclear Information System (INIS)

Jiang, Xiao; Guo, Ruiguang; Jiang, Shuqin

2015-01-01

Highlights: • Through simple chemical conversion process, a Ce–V conversion coating is prepared on AZ31 magnesium alloy. The coating (∼2 μm thick) has a duplex structure and is composed of Mg, Al, Ce, V and O in the outer layer and Mg, Al, V, F and O in the inner layer. • The Ce–V conversion coating can increase the E corr by 157 mV and decrease the i corr by 80 times compared to AZ31 magnesium alloy substrate. Moreover, the performance of the Ce–V conversion coating excels the chromate conversion coating on AZ31 magnesium alloy. • The EIS results of Ce–V conversion coating indicate an increase of 10× in the corrosion resistance and a delay in the corrosion process kinetics compared to uncoated AZ31 magnesium alloy in 3.5 wt.% NaCl solution. • The ball cratering is a simple and effective technique of thickness measurement for chemical conversion coating. - Abstract: A Ce–V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 μm. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce–V conversion coating can provide effective protection to AZ31 magnesium alloy

Microstructure and corrosion resistance of Ce–V conversion coating on AZ31 magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Jiang, Xiao, E-mail: xiaoxiao217@126.com; Guo, Ruiguang; Jiang, Shuqin

2015-06-30

Highlights: • Through simple chemical conversion process, a Ce–V conversion coating is prepared on AZ31 magnesium alloy. The coating (∼2 μm thick) has a duplex structure and is composed of Mg, Al, Ce, V and O in the outer layer and Mg, Al, V, F and O in the inner layer. • The Ce–V conversion coating can increase the E{sub corr} by 157 mV and decrease the i{sub corr} by 80 times compared to AZ31 magnesium alloy substrate. Moreover, the performance of the Ce–V conversion coating excels the chromate conversion coating on AZ31 magnesium alloy. • The EIS results of Ce–V conversion coating indicate an increase of 10× in the corrosion resistance and a delay in the corrosion process kinetics compared to uncoated AZ31 magnesium alloy in 3.5 wt.% NaCl solution. • The ball cratering is a simple and effective technique of thickness measurement for chemical conversion coating. - Abstract: A Ce–V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 μm. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce–V conversion coating can provide effective protection to AZ31 magnesium alloy.

Low severity conversion of activated coal. Final report

Energy Technology Data Exchange (ETDEWEB)

Hirschon, A.S.; Ross, D.S.

1990-01-01

The results suggest that coal contains regions with structural components significantly reactive under the hydrothermal environment. Although the specific mechanism for this process remains to be developed, this activity is reminiscent of findings in studies of accelerated maturation of oil shale, where hydrothermal treatment (hydrous pyrolysis) leads to the production of petroleum hydrocarbons. In line with what has been seen in the oil shale work, the pretreatment-generated hydrocarbons and phenols appear to represent a further or more complete maturation of some fraction of the organic material within the coal. These observations could have an impact in two areas. The first is in the area of coal structure, where immature, reactive regions have not been included in the structures considered at present. The second area of interest is the more practical one of conversions to coal liquids and pyrolytic tars. It seems clear that the hydrothermal pretreatment changes the coal in some manner that favorably affects the product quality substantially and, as in the CO/water liquefaction case, favorably affects the yields. The conversions of coals of lower rank, i.e., less mature coals, could particularly benefit in terms of both product quality and product quantity. The second portion of this project also shows important benefits to coal conversion technology. It deals with synthesizing catalysts designed to cleave the weak links in the coal structure and then linking these catalysts with the pretreatment methods in Task 2. The results show that highly dispersed catalysts can effectively be used to increase the yields of soluble material. An important aspect of highly dispersed catalysts are that they can effectively catalyze coal conversion even in poor liquefaction solvents, thus making them very attractive in processes such as coprocessing where inexpensive liquefaction media such as resids are used.

Results of the 2003 Association of Residents in Radiation Oncology (ARRO) surveys of residents and chief residents in the United States

International Nuclear Information System (INIS)

Jagsi, Reshma; Buck, David A.; Singh, Anurag K.; Engleman, Mark; Thakkar, Vipul; Frank, Steven J.; Flynn, Daniel

2005-01-01

Purpose: To document demographic characteristics of current residents, career motivations and aspirations, and training program policies and resources. Methods: In 2003, the Association of Residents in Radiation Oncology (ARRO) conducted two nationwide surveys: one of all U.S. radiation oncology residents and one of chief residents. Results: The Chief Residents' Survey was completed by representatives from all 77 programs (response rate, 100%). The Residents' Survey was returned by 229 respondents (response rate, 44%). In each, 32% of respondents were female. The most popular career after residency was private practice (46%), followed by permanent academic practice (28%). Changes that would entice those choosing private practice to consider an academic career included more research experience as a resident (76%), higher likelihood of tenure (69%), lesser time commitment (66%), and higher salary (54%). Although the majority of respondents were satisfied with educational experience overall, a number of programs were reported to provide fewer resources than required. Conclusions: Median program resources and numbers of outliers are documented to allow residents and program directors to assess the relative adequacy of experience in their own programs. Policy-making bodies and individual programs should consider these results when developing interventions to improve educational experiences of residents and to increase retention of radiation oncologists in academic practice

Introduction of laparoscopic low anterior resection for rectal cancer early during residency: a single institutional study on short-term outcomes.

Science.gov (United States)

Ogiso, Satoshi; Yamaguchi, Takashi; Hata, Hiroaki; Kuroyanagi, Hiroya; Sakai, Yoshiharu

2010-11-01

Laparoscopic surgery for rectal cancer is unpopular because it is technically challenging. Suitable training systems have not been widely studied or established despite the steep learning curve for this procedure. We developed a systematic training program that enables resident surgeons to perform laparoscopic low anterior resection (LLAR) for rectal cancer and evaluated the safety and feasibility of this training program. We analyzed prospectively gathered data on all LLARs for rectal cancer performed at a single center over a 7-year period. Patients were assessed for demographic characteristics, tumor characteristics, operative procedure, operative time, blood loss, conversion to open surgery, complications, time to bowel recovery, distal margin, and number of lymph nodes harvested. We compared the early surgical, oncological, and functional outcomes of LLARs performed by expert surgeons with those of LLARs performed by resident surgeons for both intraperitoneal and extraperitoneal rectal cancer. All analyses were performed on an intention-to-treat basis. A total of 137 patients met the inclusion criteria for this study. Of the 75 LLARs for intraperitoneal rectal cancer, 40 were performed by expert surgeons (I-E group) and 35 by resident surgeons (I-R group). Of the 62 LLARs for extraperitoneal rectal cancer, 51 were performed by expert surgeons (E-E group) and 11 by resident surgeons (E-R group). The operative time was longer in the E-R group than in the E-E group. The time to resumption of diet was longer in the I-E group than in the I-R group. The other early outcomes, including blood loss, anastomotic leakage, conversion to open surgery, and number of lymph nodes harvested, were similar in the I-E and I-R groups and in the E-E and E-R groups. Our systematic training program on LLAR for rectal cancer enables resident surgeons to perform this procedure safely early during residency, with acceptable short-term outcomes.

Residents' engagement in everyday activities and its association with thriving in nursing homes.

Science.gov (United States)

Björk, Sabine; Lindkvist, Marie; Wimo, Anders; Juthberg, Christina; Bergland, Ådel; Edvardsson, David

2017-08-01

To describe the prevalence of everyday activity engagement for older people in nursing homes and the extent to which engagement in everyday activities is associated with thriving. Research into residents' engagement in everyday activities in nursing homes has focused primarily on associations with quality of life and prevention and management of neuropsychiatric symptoms. However, the mere absence of symptoms does not necessarily guarantee experiences of well-being. The concept of thriving encapsulates and explores experiences of well-being in relation to the place where a person lives. A cross-sectional survey. A national survey of 172 Swedish nursing homes (2013-2014). Resident (n = 4831) symptoms, activities and thriving were assessed by staff using a study survey based on established questionnaires. Descriptive statistics, simple and multiple linear regression, and linear stepwise multiple regression were performed. The most commonly occurring everyday activities were receiving hugs and physical touch, talking to relatives/friends and receiving visitors, having conversation with staff not related to care and grooming. The least commonly occurring everyday activities were going to the cinema, participating in an educational program, visiting a restaurant and doing everyday chores. Positive associations were found between activity engagement and thriving, where engagement in an activity program, dressing nicely and spending time with someone the resident likes had the strongest positive association with resident thriving. Engagement in everyday activities can support personhood and thriving and can be conceptualized and implemented as nursing interventions to enable residents to thrive in nursing homes. © 2017 John Wiley & Sons Ltd.

Investigation of effect of air flow rate on Zircaloy-4 oxidation kinetics and breakaway phenomenon in air at 850 .deg. C

International Nuclear Information System (INIS)

Maeng, Yunhwan; Lee, Jaeyoung; Park, Sanggil

2016-01-01

This paper analyzed an effect of flow rate on oxidation kinetics of Zircaloy-4 in air at 850 .deg. C. In case of the oxidation of Zircaloy-4 in air at 850 .deg. C, acceleration of oxidation kinetics from parabolic to linear (breakaway phenomenon) occurs. Oxidation and breakaway kinetics of the Zircaloy-4 in air was experimentally studied by changing a flow rate of argon/air mixture. Tests were conducted at 850 .deg. C under constant ratio of argon and air. The effects of flow rate on the oxidation and breakaway kinetics was observed. This paper is based on a revised and considerably extended presentation given at the 21 st International Quench Workshop. The effects of flow conditions on the oxidation kinetics of Zircaloy-4 samples were explained with residence time and percent flow efficiency. In addition, several issues were observed from this study, interdiffusion at breakaway and deformation of oxide structure by breakaway phenomenon

The resident's view of residency training in Canada.

Science.gov (United States)

Fish, D G

1966-04-09

In the view of residents in their last year of specialty training, the Fellowship is now becoming the operative standard for obtaining hospital privileges in urban centres and they felt that this implied that the two standards, the Certificate and the Fellowship of the Royal College, were not achieving the purpose for which they were designed. Although 80% of the residents intended to write the Fellowship, few viewed a year in a basic science department or in research as of intrinsic value in terms of their future practice.The examinations of the Royal College were the subject of criticism, most residents feeling that the examinations did not test the knowledge and ability gained in training. Most expressed a desire for ongoing evaluation during the training period.Service responsibilities were generally regarded as too heavy.Despite the criticism of both training and examination, most residents felt that their training had provided them with the experience and background they needed to practise as specialists.

Identifying Gaps and Launching Resident Wellness Initiatives: The 2017 Resident Wellness Consensus Summit.

Science.gov (United States)

Zaver, Fareen; Battaglioli, Nicole; Denq, William; Messman, Anne; Chung, Arlene; Lin, Michelle; Liu, Emberlynn L

2018-03-01

Burnout, depression, and suicidality among residents of all specialties have become a critical focus for the medical education community, especially among learners in graduate medical education. In 2017 the Accreditation Council for Graduate Medical Education (ACGME) updated the Common Program Requirements to focus more on resident wellbeing. To address this issue, one working group from the 2017 Resident Wellness Consensus Summit (RWCS) focused on wellness program innovations and initiatives in emergency medicine (EM) residency programs. Over a seven-month period leading up to the RWCS event, the Programmatic Initiatives workgroup convened virtually in the Wellness Think Tank, an online, resident community consisting of 142 residents from 100 EM residencies in North America. A 15-person subgroup (13 residents, two faculty facilitators) met at the RWCS to develop a public, central repository of initiatives for programs, as well as tools to assist programs in identifying gaps in their overarching wellness programs. An online submission form and central database of wellness initiatives were created and accessible to the public. Wellness Think Tank members collected an initial 36 submissions for the database by the time of the RWCS event. Based on general workplace, needs-assessment tools on employee wellbeing and Kern's model for curriculum development, a resident-based needs-assessment survey and an implementation worksheet were created to assist residency programs in wellness program development. The Programmatic Initiatives workgroup from the resident-driven RWCS event created tools to assist EM residency programs in identifying existing initiatives and gaps in their wellness programs to meet the ACGME's expanded focus on resident wellbeing.

Kinetics based reaction optimization of enzyme catalysed reduction of formaldehyde to methanol with synchronous cofactor regeneration

DEFF Research Database (Denmark)

Marpani, Fauziah Binti; Sárossy, Zsuzsa; Pinelo, Manuel

2017-01-01

regeneration of the reducing equivalents during reaction is required. Herein, we report the optimization of the enzymatic conversion of formaldehyde (CHOH) to CH3 OH by alcohol dehydrogenase, the final step of the enzymatic redox reaction of CO2 to CH3 OH, with kinetically synchronous enzymatic cofactor...... regeneration using either glucose dehydrogenase (System I) or xylose dehydrogenase (System II). A mathematical model of the enzyme kinetics was employed to identify the best reaction set-up for attaining optimal cofactor recycling rate and enzyme utilization efficiency. Targeted process optimization...... experiments were conducted to verify the kinetically modelled results. Repetitive reaction cycles were shown to enhance the yield of CH3 OH, increase the total turnover number (TTN) and the biocatalytic productivity rate (BPR) value for both system I and II whilst minimizing the exposure of the enzymes...

Soil Carbon Residence Time in the Arctic - Potential Drivers of Past and Future Change

Science.gov (United States)

Huntzinger, D. N.; Fisher, J.; Schwalm, C. R.; Hayes, D. J.; Stofferahn, E.; Hantson, W.; Schaefer, K. M.; Fang, Y.; Michalak, A. M.; Wei, Y.

2017-12-01

Carbon residence time is one of the most important factors controlling carbon cycling in ecosystems. Residence time depends on carbon allocation and conversion among various carbon pools and the rate of organic matter decomposition; all of which rely on environmental conditions, primarily temperature and soil moisture. As a result, residence time is an emergent property of models and a strong determinant of terrestrial carbon storage capacity. However, residence time is poorly constrained in process-based models due, in part, to the lack of data with which to benchmark global-scale models in order to guide model improvements and, ultimately, reduce uncertainty in model projections. Here we focus on improving the understanding of the drivers to observed and simulated carbon residence time in the Arctic-Boreal region (ABR). Carbon-cycling in the ABR represents one of the largest sources of uncertainty in historical and future projections of land-atmosphere carbon dynamics. This uncertainty is depicted in the large spread of terrestrial biospheric model (TBM) estimates of carbon flux and ecosystem carbon pool size in this region. Recent efforts, such as the Arctic-Boreal Vulnerability Experiment (ABoVE), have increased the availability of spatially explicit in-situ and remotely sensed carbon and ecosystem focused data products in the ABR. Together with simulations from Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP), we use these observations to evaluate the ability of models to capture soil carbon stocks and changes in the ABR. Specifically, we compare simulated versus observed soil carbon residence times in order to evaluate the functional response and sensitivity of modeled soil carbon stocks to changes in key environmental drivers. Understanding how simulated carbon residence time compares with observations and what drives these differences is critical for improving projections of changing carbon dynamics in the ABR and globally.

Resident and attending physician perception of maladaptive response to stress in residents

Directory of Open Access Journals (Sweden)

Lee Ann Riesenberg

2014-11-01

Full Text Available Background: Residency stress has been shown to interfere with resident well-being and patient safety. We developed a survey research study designed to explore factors that may affect perception of a maladaptive response to stress. Methods: A 16-item survey with 12 Likert-type perception items was designed to determine how often respondents agreed or disagreed with statements regarding the resident on the trigger tape. A total of 438 respondents from multiple institutions completed surveys. Results: Attending physicians were more likely than residents to agree that the resident on the trigger tape was impaired, p<0.0001; needed to seek professional counseling, p=0.0003; should be removed from the service, p=0.002; was not receiving adequate support from the attending physician, p=0.007; and was a risk to patient safety, p=0.02. Attending physicians were also less likely to agree that the resident was a good role model, p=0.001, and that the resident should be able to resolve these issues herself/himself, p<0.0001. Conclusion: Our data suggest that resident physicians may not be able to adequately detect maladaptive responses to stress and that attending physicians may be more adept at recognizing this problem. More innovative faculty and resident development workshops should be created to teach and encourage physicians to better observe and detect residents who are displaying maladaptive responses to stress.

Bioinspired co-crystals of Imatinib providing enhanced kinetic solubility.

Science.gov (United States)

Reggane, Maude; Wiest, Johannes; Saedtler, Marco; Harlacher, Cornelius; Gutmann, Marcus; Zottnick, Sven H; Piechon, Philippe; Dix, Ina; Müller-Buschbaum, Klaus; Holzgrabe, Ulrike; Meinel, Lorenz; Galli, Bruno

2018-05-04

Realizing the full potential of co-crystals enhanced kinetic solubility demands a comprehensive understanding of the mechanisms of dissolution, phase conversion, nucleation and crystal growth, and of the complex interplay between the active pharmaceutical ingredient (API), the coformer and co-existing forms in aqueous media. One blueprint provided by nature to keep poorly water-soluble bases in solution is the complexation with phenolic acids. Consequently, we followed a bioinspired strategy for the engineering of co-crystals of a poorly water-soluble molecule - Imatinib - with a phenolic acid, syringic acid (SYA). The dynamics of dissolution and solution-mediated phase transformations were monitored by Nuclear Magnetic Resonance (NMR) spectroscopy, providing mechanistic insights into the 60 fold-increased long lasting concentrations achieved by the syringate co-crystals as compared to Imatinib base and Imatinib mesylate. This lasting effect was linked to SYA's ability to delay the formation and nucleation of Imatinib hydrate - the thermodynamically stable form in aqueous media - through a metastable association of SYA with Imatinib in solution. Results from permeability studies evidenced that SYA did not impact Imatinib's permeability across membranes while suggesting improved bioavailability through higher kinetic solubility at the biological barriers. These results reflect that some degree of hydrophobicity of the coformer might be key to extend the kinetic solubility of co-crystals with hydrophobic APIs. Understanding how kinetic supersaturation can be shaped by the selection of an interactive coformer may help achieving the needed performance of new forms of poorly water-soluble, slowly dissolving APIs. Copyright © 2018. Published by Elsevier B.V.

THERMO-MECHANICAL PULPING AS A PRETREATMENT FOR AGRICULTURAL BIOMASS FOR BIOCHEMICAL CONVERSION

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Ronalds W. Gonzalez

2011-03-01

Full Text Available The use of thermo-mechanical pulping (TMP, an existing and well known technology in the pulp and paper industry, is proposed as a potential pretreatment pathway of agriculture biomass for monomeric sugar production in preparation for further fermentation into alcohol species. Three agricultural biomass types, corn stover, wheat straw, and sweet sorghum bagasse, were pretreated in a TMP unit under two temperature conditions, 160 ºC and 170 ºC, and hydrolyzed using cellulase at 5, 10, and 20 FPU/g OD biomass. Wheat straw biomass was further pretreated at different conditions including: i soaking with acetic acid, ii longer steaming residence time (15 and 30 min, and iii refined at lower disk gap (0.0508 and 0.1524 mm. Preliminary results showed that carbohydrate conversion increased from 25% to 40% when the TMP temperature was increased from 160 to 170 ºC. Carbohydrate conversion was relatively similar for the three biomasses under the same pretreatment conditions and enzyme loading. Acetic acid soaking and refining at a reduce disk gap increases carbohydrate conversion. Further studies within this technological field to identify optimum process and TMP conditions for pretreatment are suggested.

Identifying Gaps and Launching Resident Wellness Initiatives: The 2017 Resident Wellness Consensus Summit

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Nicole Battaglioli

2018-02-01

Full Text Available Introduction: Burnout, depression, and suicidality among residents of all specialties have become a critical focus for the medical education community, especially among learners in graduate medical education. In 2017 the Accreditation Council for Graduate Medical Education (ACGME updated the Common Program Requirements to focus more on resident wellbeing. To address this issue, one working group from the 2017 Resident Wellness Consensus Summit (RWCS focused on wellness program innovations and initiatives in emergency medicine (EM residency programs. Methods: Over a seven-month period leading up to the RWCS event, the Programmatic Initiatives workgroup convened virtually in the Wellness Think Tank, an online, resident community consisting of 142 residents from 100 EM residencies in North America. A 15-person subgroup (13 residents, two faculty facilitators met at the RWCS to develop a public, central repository of initiatives for programs, as well as tools to assist programs in identifying gaps in their overarching wellness programs. Results: An online submission form and central database of wellness initiatives were created and accessible to the public. Wellness Think Tank members collected an initial 36 submissions for the database by the time of the RWCS event. Based on general workplace, needs-assessment tools on employee wellbeing and Kern’s model for curriculum development, a resident-based needs-assessment survey and an implementation worksheet were created to assist residency programs in wellness program development. Conclusion: The Programmatic Initiatives workgroup from the resident-driven RWCS event created tools to assist EM residency programs in identifying existing initiatives and gaps in their wellness programs to meet the ACGME’s expanded focus on resident wellbeing.

Case-Logging Practices in Otolaryngology Residency Training: National Survey of Residents and Program Directors.

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Dermody, Sarah M; Gao, William; McGinn, Johnathan D; Malekzadeh, Sonya

2017-06-01

Objective (1) Evaluate the consistency and manner in which otolaryngology residents log surgical cases. (2) Assess the extent of instruction and guidance provided by program directors on case-logging practices. Study Design Cross-sectional national survey. Setting Accreditation Council for Graduate Medical Education otolaryngology residency programs in the United States. Subjects and Methods US otolaryngology residents, postgraduate year 2 through graduating chiefs as of July 2016, were recruited to respond to an anonymous questionnaire designed to characterize surgical case-logging practices. Program directors of US otolaryngology residency programs were recruited to respond to an anonymous questionnaire to elucidate how residents are instructed to log cases. Results A total of 272 residents and 53 program directors completed the survey, yielding response rates of 40.6% and 49.5%, respectively. Perceived accuracy of case logs is low among residents and program directors. Nearly 40% of residents purposely choose not to log certain cases, and 65.1% of residents underreport cases performed. More than 80% of program directors advise residents to log procedures performed outside the operating room, yet only 16% of residents consistently log such cases. Conclusion Variability in surgical case-logging behaviors and differences in provided instruction highlight the need for methods to improve consistency of logging practices. It is imperative to standardize practices across otolaryngology residency programs for case logs to serve as an accurate measure of surgical competency. This study provides a foundation for reform efforts within residency programs and for the Resident Case Log System.

Plasma kinetics of sup 125 I beta endorphin turnover in lean and obese Zucker rats

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Rodd, D.; Caston, A.L.; Green M.H.; Farrell, P.A. (Pennsylvania State Univ., University Park (United States))

1990-02-26

Plasma clearance kinetics for Beta Endorphin (BEP) are not well-defined and no definitive data exist for lean versus obese animals. To determine such kinetic parameters, a bolus of {sup 125}I BEP (1{mu}Ci/kg) was infused into awake lean(L) and obese(O) Zucker rats. Arterial blood samples were withdrawn initially at 20 seconds intervals and less frequently as a 3-hour experimental period progressed. Donor rat blood was infused (venous catheter) to replace withdrawn blood. At 180 minutes approximately 10% of the initial dose remained in the plasma. Clearance kinetics for {sup 125}I BEP were analyzed by compartmental analysis. A 3-component equation (i.e., 3 compartment model) provided the best fit for both L and O groups. Plasma transit times were very rapid; however, plasma fractional catabolic rate was low. Plasma mean residence time was similar for both groups (50 minutes) as was recycle time. These data suggest that BEP kinetics are similar in L and O rats, and that this peptide may undergo extensive recycling into and out of the plasma compartment. The identity of the other two compartments requires further investigation.

Uranium conversion

International Nuclear Information System (INIS)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina

2006-03-01

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF 6 and UF 4 are present require equipment that is made of corrosion resistant material

Kinetically controlled synthesis of large-scale morphology-tailored silver nanostructures at low temperature

Science.gov (United States)

Zhang, Ling; Zhao, Yuda; Lin, Ziyuan; Gu, Fangyuan; Lau, Shu Ping; Li, Li; Chai, Yang

2015-08-01

Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology-tailored Ag nanostructures, which is significant to the controllable fabrication of Ag nanostructures and fundamental understanding of the growth kinetics.Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology

Deciphering visible light photoreductive conversion of CO2 to formic acid and methanol using waste prepared material.

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Zhang, Qian; Lin, Cheng-Fang; Chen, Bor-Yann; Ouyang, Tong; Chang, Chang-Tang

2015-02-17

As gradual increases in atmospheric CO2 and depletion of fossil fuels have raised considerable public concern in recent decades, utilizing the unlimited solar energy to convert CO2 to fuels (e.g., formic acid and methanol) apparently could simultaneously resolve these issues for sustainable development. However, due to the complicated characteristics of CO2 reduction, the mechanism has yet to be disclosed. To clarify the postulated pathway as mentioned in the literature, the technique of electron paramagnetic resonance (ESR) was implemented herein to confirm the mechanism and related pathways of CO2 reduction under visible light using graphene-TiO2 as catalyst. The findings indicated that CO(-•) radicals, as the main intermediates, were first detected herein to react with several hydrogen ions and electrons for the formation of CH3OH. For example, the generation of CO(-•) radicals is possibly the vital rate-controlling step for conversion of CO2 to methanol as hypothesized elsewhere. The kinetics behind the proposed mechanism was also determined in this study. The mechanism and kinetics could provide the in-depth understanding to the pathway of CO2 reduction and disclose system optimization of maximal conversion for further application.

Feasibility of an innovative third-year chief resident system: an internal medicine residency leadership study

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Victor O. Kolade

2014-07-01

Full Text Available Introduction: The role of the internal medicine chief resident includes various administrative, academic, social, and educational responsibilities, fulfillment of which prepares residents for further leadership tasks. However, the chief resident position has historically only been held by a few residents. As fourth-year chief residents are becoming less common, we considered a new model for rotating third-year residents as the chief resident. Methods: Online surveys were given to all 29 internal medicine residents in a single university-based program after implementation of a leadership curriculum and specific job description for the third-year chief resident. Chief residents evaluated themselves on various aspects of leadership. Participation was voluntary. Descriptive statistics were generated using SPSS version 21. Results: Thirteen junior (first- or second-year resident responses reported that the chief residents elicited input from others (mean rating 6.8, were committed to the team (6.8, resolved conflict (6.7, ensured efficiency, organization and productivity of the team (6.7, participated actively (7.0, and managed resources (6.6. Responses from senior residents averaged 1 point higher for each item; this pattern repeated itself in teaching evaluations. Chief resident self-evaluators were more comfortable running a morning report (8.4 than with being chief resident (5.8. Conclusion: The feasibility of preparing internal medicine residents for leadership roles through a rotating PGY-3 (postgraduate year chief residency curriculum was explored at a small internal medicine residency, and we suggest extending the study to include other programs.

Sexy gene conversions: locating gene conversions on the X-chromosome.

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Lawson, Mark J; Zhang, Liqing

2009-08-01

Gene conversion can have a profound impact on both the short- and long-term evolution of genes and genomes. Here, we examined the gene families that are located on the X-chromosomes of human (Homo sapiens), chimpanzee (Pan troglodytes), mouse (Mus musculus) and rat (Rattus norvegicus) for evidence of gene conversion. We identified seven gene families (WD repeat protein family, Ferritin Heavy Chain family, RAS-related Protein RAB-40 family, Diphosphoinositol polyphosphate phosphohydrolase family, Transcription Elongation Factor A family, LDOC1-related family, Zinc Finger Protein ZIC, and GLI family) that show evidence of gene conversion. Through phylogenetic analyses and synteny evidence, we show that gene conversion has played an important role in the evolution of these gene families and that gene conversion has occurred independently in both primates and rodents. Comparing the results with those of two gene conversion prediction programs (GENECONV and Partimatrix), we found that both GENECONV and Partimatrix have very high false negative rates (i.e. failed to predict gene conversions), which leads to many undetected gene conversions. The combination of phylogenetic analyses with physical synteny evidence exhibits high resolution in the detection of gene conversions.

Furaldehyde substrate specificity and kinetics of Saccharomyces cerevisiae alcohol dehydrogenase 1 variants.

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Laadan, Boaz; Wallace-Salinas, Valeria; Carlsson, Åsa Janfalk; Almeida, João Rm; Rådström, Peter; Gorwa-Grauslund, Marie F

2014-08-09

A previously discovered mutant of Saccharomyces cerevisiae alcohol dehydrogenase 1 (Adh1p) was shown to enable a unique NADH-dependent reduction of 5-hydroxymethylfurfural (HMF), a well-known inhibitor of yeast fermentation. In the present study, site-directed mutagenesis of both native and mutated ADH1 genes was performed in order to identify the key amino acids involved in this substrate shift, resulting in Adh1p-variants with different substrate specificities. In vitro activities of the Adh1p-variants using two furaldehydes, HMF and furfural, revealed that HMF reduction ability could be acquired after a single amino acid substitution (Y295C). The highest activity, however, was reached with the double mutation S110P Y295C. Kinetic characterization with both aldehydes and the in vivo primary substrate acetaldehyde also enabled to correlate the alterations in substrate affinity with the different amino acid substitutions. We demonstrated the key role of Y295C mutation in HMF reduction by Adh1p. We generated and kinetically characterized a group of protein variants using two furaldehyde compounds of industrial relevance. Also, we showed that there is a threshold after which higher in vitro HMF reduction activities do not correlate any more with faster in vivo rates of HMF conversion, indicating other cell limitations in the conversion of HMF.

Synchrotron Study on Crystallization Kinetics of Milk Fat under Shear Flow

International Nuclear Information System (INIS)

Mazzanti, G.; Marangoni, A.; Idziak, S.

2009-01-01

A detailed synchrotron X-ray diffraction study on the kinetics of crystallization of anhydrous milk fat (AMF) and milk fat triacylglycerols (MFT) was done in a Couette cell at 17 C, 17.5 C and 20 C under shear rates between 0 and 2880 s-1. We observed shear-induced acceleration of the transition from phase ? to ?? and the presence of crystalline orientation, but no effect of shear on the onset time of phase ? was observed. A two stage regime was observed for the growth of phase ??. The first stage follows a series-parallel system of differential equations describing the conversion between liquid and crystalline phases. The second stage follows a diffusion-controlled regime. These mechanisms are consistent with the crystalline orientation, the growth of the crystalline domains and the observed displacement of the diffraction peak positions. The absence of the polar lipids explains the faster kinetics of MFT.

Thermal degradation behaviors of polyethylene and polypropylene. Part I: Pyrolysis kinetics and mechanisms

International Nuclear Information System (INIS)

Aboulkas, A.; El harfi, K.; El Bouadili, A.

2010-01-01

Study of the decomposition kinetics is an important tool for the development of polymer recycling in industrial scale. In this work, the activation energy and the reaction model of the pyrolysis of high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) have been estimated from non-isothermal kinetic results. Firstly, the activation energy values obtained by Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa isoconversional methods, are 238-247 kJ/mol for HDPE, 215-221 kJ/mol for LDPE and 179-188 kJ/mol for PP. Secondly, the appropriate conversion model of the process was determined by Coats-Redfern and Criado methods. The pyrolysis reaction models of HDPE and LDPE are accounted for by 'Contracting Sphere' model, whereas that of PP by 'Contracting Cylinder' model.

Current integrated cardiothoracic surgery residents: a Thoracic Surgery Residents Association survey.

Science.gov (United States)

Tchantchaleishvili, Vakhtang; LaPar, Damien J; Stephens, Elizabeth H; Berfield, Kathleen S; Odell, David D; DeNino, Walter F

2015-03-01

After approval by the Thoracic Surgery Residency Review Committee in 2007, 6-year integrated cardiothoracic surgery (I-6) residency programs have gained in popularity. We sought to assess and objectively quantify the level of satisfaction I-6 residents have with their training and to identify areas of improvement for future curriculum development. A completely anonymous, electronic survey was created by the Thoracic Surgery Residents Association that asked the responders to provide demographic information, specialty interest, and lifestyle priorities, and to rate their experience and satisfaction with I-6 residency. The survey was distributed nationwide to all residents in I-6 programs approved by the Accreditation Council for Graduate Medical Education. Of a total of 88 eligible I-6 residents, 49 completed the survey (55.7%). Career choice satisfaction was high (75.5%), as was overall satisfaction with integrated training (83.7%). The majority (77.6%) were interested in cardiac surgery. Overall, the responders reported sufficient time for life outside of the hospital (57.1%), but experienced conflicts between work obligations and personal life at least sometimes (75.5%). Early exposure to cardiothoracic surgery was reported as the dominant advantage of the I-6 model, whereas variable curriculum structure and unclear expectations along with poor integration with general surgery training ranked highest among perceived disadvantages. Current I-6 residents are largely satisfied with the integrated training model and report a reasonable work/life balance. The focused nature of training is the primary perceived advantage of the integrated pathway. Curriculum variability and poor integration with general surgery training are identified by residents as primary areas of concern. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation

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Mohamad Irfan Fathurrohman

2015-07-01

Full Text Available The vulcanization kinetics of Ethylene-propylene diene monomer (EPDM rubber thermal insulation was studied by using rheometer under isothermal condition at different temperatures. The rheometry analysis was used to determining the cure kinetic parameters and predicting the cure time of EPDM thermal insulation. The experimental results revealed that the curing curves of EPDM thermal insulation were marching and the optimum curing time decreased with increasing the temperature. The kinetic parameters were determined from the autocatalytic model showed close fitting with the experimental results, indicating suitability of autocatalytic model in characterizing the cure kinetics. The activation energy was determined from the autocatalytic model is 46.3661 kJ mol-1. The cure time were predicted from autocatalytic model and the obtained kinetic parameter by using the relationship among degree of conversion, cure temperature, and cure time. The predictions of cure time provide information for the actual curing characteristic of EPDM thermal insulation. The mechanical properties of EPDM thermal insulation with different vulcanization temperatures showed the same hardness, tensile strength and modulus at 300%, except at temperature 70 °C, while the elongation at breaking point decreased with increasing temperature of vulcanization. © 2015 BCREC UNDIP. All rights reservedReceived: 8th April 2014; Revised: 7th January 2015; Accepted: 16th January 2015How to Cite: Fathurrohman, M.I., Maspanger, D.R., Sutrisno, S. (2015. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation. Bulletin of Chemi-cal Reaction Engineering & Catalysis, 10 (2, 104-110. (doi:10.9767/bcrec.10.2.6682.104-110Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.6682.104-110 

Confidence, knowledge, and skills at the beginning of residency. A survey of pathology residents.

Science.gov (United States)

Hsieh, Cindy M; Nolan, Norris J

2015-01-01

To document the pathology learning experiences of pathology residents prior to residency and to determine how confident they were in their knowledge and technical skills. An online survey was distributed to all pathology residency program directors in the United States, who were requested to forward the survey link to their residents. Data were obtained on pathology electives, grossing experience, and frozen section experience. Likert scale questions assessed confidence level in knowledge and skills. In total, 201 pathology residents responded (8% of residents in the United States). Prior to starting residency, most respondents had exposure to anatomic pathology through elective rotations. Few respondents had work-related experience. Most did not feel confident in their pathology-related knowledge or skills, and many did not understand what pathology resident duties entail. Respondents gained exposure to pathology primarily through elective rotations, and most felt the elective experience prepared them for pathology residency. However, elective time may be enhanced by providing opportunities for students to increase hands-on experience and understanding of resident duties. Copyright© by the American Society for Clinical Pathology.

The Role of Conversation Policy in Carrying Out Agent Conversations

International Nuclear Information System (INIS)

Link, Hamilton E.; Phillips, Laurence R.

1999-01-01

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

Does resident ranking during recruitment accurately predict subsequent performance as a surgical resident?

Science.gov (United States)

Fryer, Jonathan P; Corcoran, Noreen; George, Brian; Wang, Ed; Darosa, Debra

2012-01-01

While the primary goal of ranking applicants for surgical residency training positions is to identify the candidates who will subsequently perform best as surgical residents, the effectiveness of the ranking process has not been adequately studied. We evaluated our general surgery resident recruitment process between 2001 and 2011 inclusive, to determine if our recruitment ranking parameters effectively predicted subsequent resident performance. We identified 3 candidate ranking parameters (United States Medical Licensing Examination [USMLE] Step 1 score, unadjusted ranking score [URS], and final adjusted ranking [FAR]), and 4 resident performance parameters (American Board of Surgery In-Training Examination [ABSITE] score, PGY1 resident evaluation grade [REG], overall REG, and independent faculty rating ranking [IFRR]), and assessed whether the former were predictive of the latter. Analyses utilized Spearman correlation coefficient. We found that the URS, which is based on objective and criterion based parameters, was a better predictor of subsequent performance than the FAR, which is a modification of the URS based on subsequent determinations of the resident selection committee. USMLE score was a reliable predictor of ABSITE scores only. However, when we compared our worst residence performances with the performances of the other residents in this evaluation, the data did not produce convincing evidence that poor resident performances could be reliably predicted by any of the recruitment ranking parameters. Finally, stratifying candidates based on their rank range did not effectively define a ranking cut-off beyond which resident performance would drop off. Based on these findings, we recommend surgery programs may be better served by utilizing a more structured resident ranking process and that subsequent adjustments to the rank list generated by this process should be undertaken with caution. Copyright © 2012 Association of Program Directors in Surgery

Personal Therapy in Psychiatry Residency Training: A National Survey of Canadian Psychiatry Residents.

Science.gov (United States)

Hadjipavlou, George; Halli, Priyanka; Hernandez, Carlos A Sierra; Ogrodniczuk, John S

2016-02-01

The authors collected nationally representative data on Canadian residents' experiences with and perspectives on personal psychotherapy in their psychiatric training. A 43-item questionnaire was distributed electronically to all current psychiatry residents in Canada (N = 839). Four hundred residents from every program across Canada returned the survey (response rate 47.7%). The prevalence of personal therapy at any time was 55.3%, with 42.8% receiving personal therapy during residency. Of residents who undertook personal psychotherapy, 59.3% engaged in weekly therapy, 74.1% received psychodynamic psychotherapy, and 81.5% participated in long-term therapy (>1 year). Personal growth, self-understanding, and professional development were the most common reasons for engaging in personal therapy; however, one-third of residents did so to alleviate symptoms of depression, anxiety, or other mental health concerns. Time was the most important factor impeding residents from personal therapy; only 8.8% found stigma to act as a barrier. The vast majority of residents rated their experience with personal therapy as having a positive or very positive impact on their personal life (84.8%) and overall development as psychiatrists (81.8%). For 64% of respondents, personal therapy had an important or very important role in psychiatry residency training. Residents who received personal therapy rated themselves as better able to understand what happens moment by moment during therapy sessions, detect and deal with patients' emotional reactions, and constructively use their personal reactions to patients. Interest in personal therapy remains strong among psychiatry trainees in Canada. Residents who engaged in psychotherapy endorsed greater confidence in psychotherapy and rated their psychotherapy skills more favorably than those who had never been in the patient role, supporting the view of personal therapy as an important adjunct to psychotherapy training during residency.

The Generalized Conversion Factor in Einstein's Mass-Energy Equation

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Ajay Sharma

2008-07-01

Full Text Available Einstein's September 1905 paper is origin of light energy-mass inter conversion equation ($L = Delta mc^{2}$ and Einstein speculated $E = Delta mc^{2}$ from it by simply replacing $L$ by $E$. From its critical analysis it follows that $L = Delta mc^{2}$ is only true under special or ideal conditions. Under general cases the result is $L propto Delta mc^{2}$ ($E propto Delta mc^{2}$. Consequently an alternate equation $Delta E = A ub c^{2}Delta M$ has been suggested, which implies that energy emitted on annihilation of mass can be equal, less and more than predicted by $Delta E = Delta mc^{2}$. The total kinetic energy of fission fragments of U-235 or Pu-239 is found experimentally 20-60 MeV less than Q-value predicted by $Delta mc^{2}$. The mass of particle Ds (2317 discovered at SLAC, is more than current estimates. In many reactions including chemical reactions $E = Delta mc^{2}$ is not confirmed yet, but regarded as true. It implies the conversion factor than $c^{2}$ is possible. These phenomena can be explained with help of generalized mass-energy equation $Delta E = A ub c^{2}Delta M$.

Tracer kinetics: Modelling by partial differential equations of inhomogeneous compartments with age-dependent elimination rates. Pt. 1

International Nuclear Information System (INIS)

Winkler, E.

1991-01-01

Mathematical models in tracer kinetics are usually based on ordinary differential equations which correspond to a system of kinetically homogeneous compartments (standard compartments). A generalization is possible by the admission of inhomogeneities in the behaviour of the elements belonging to a compartment. The important special case of the age-dependence of elimination rates is treated in its deterministic version. It leads to partial different equations (i.e., systems with distributed coefficients) with the 'age' or the 'residence time' of an element of the compartment as a variable additional to 'time'. The basic equations for one generalized compartment and for systems of such compartments are given together with their general solutions. (orig.) [de

L'hydrodésazotation des distillats issus de la conversion des hydrocarbures lourds Hydrodenitrogenation of Distillates Issuing from the Conversion of Heavy Hydrocarbons

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Toulhoat H.

2006-11-01

Full Text Available L'hydrodésazotation catalytique (HDN est un des points clés de la valorisation des hydrocarbures lourds par leur conversion en carburants. Les coupes lourdes sont riches en azote, et leur conversion produit des distillats eux-mêmes très riches en azote, qui ne pourront être absorbés par une raffinerie classique sans un sévère prétraitement désazotant. Ce problème se pose quel que soit le procédé de conversion mis en oeuvre. On propose donc une analyse de l'HDN comprenant la description des structures azotées rencontrées dans les coupes à traiter, la mise en évidence des réactions à promouvoir, et les règles de choix de catalyseurs et de conditions opératoires en découlant compte tenu des principales déterminantes thermodynamiques et cinétiques. Cette analyse s'appuie sur des résultats de recherche très récents. Elle conduit à la mise en évidence de solutions actuelles au problème posé, et ouvre des perspectives pour des améliorations futures. Catalytic hydrodenitrogenation (HDN is one of the key steps in the upgrading of heavy hydrocarbons by converting them into fuels. Heavy cuts are rich in nitrogen, and their conversion produces distillates that are also very rich in nitrogen, making them unable to be absorbed by a conventional refinery without a severe denitrogenation pretreatment. This problem occurs no matter what conversion process is implemented. Therefore, an analysis of HDN is proposed, including the description of the nitrogen structures encountered in the cuts to be treated, the description of the reactions to be promoted, and the resulting rules for choosing catalysts and operating conditions, in the light of the principal thermodynamic and kinetic constraints. This analysis is based on very recent research results. It leads to the recommending of solutions to the problem at hand and opens up prospects for future improvements.

Well-being in residency training: a survey examining resident physician satisfaction both within and outside of residency training and mental health in Alberta

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Patten Scott

2005-06-01

Full Text Available Abstract Background Despite the critical importance of well-being during residency training, only a few Canadian studies have examined stress in residency and none have examined well-being resources. No recent studies have reported any significant concerns with respect to perceived stress levels in residency. We investigated the level of perceived stress, mental health and understanding and need for well-being resources among resident physicians in training programs in Alberta, Canada. Methods A mail questionnaire was distributed to the entire resident membership of PARA during 2003 academic year. PARA represents each of the two medical schools in the province of Alberta. Results In total 415 (51 % residents participated in the study. Thirty-four percent of residents who responded to the survey reported their life as being stressful. Females reported stress more frequently than males (40% vs. 27%, p Residents highly valued their colleagues (67%, program directors (60% and external psychiatrist/psychologist (49% as well-being resources. Over one third of residents wished to have a career counselor (39% and financial counselor (38%. Conclusion Many Albertan residents experience significant stressors and emotional and mental health problems. Some of which differ among genders. This study can serve as a basis for future resource application, research and advocacy for overall improvements to well-being during residency training.

Simultaneous FT-NIR and ESR analysis to study of the kinetics of photo induced polymerization of vinyl radical polymers

International Nuclear Information System (INIS)

Le, T.T.; Hill, D.J.T.; Pomery, P.J.

2000-01-01

Full text:The rate parameters for free vinyl radical polymerizations are difficult to determine accurately over the whole range of conversion. For systems which polymerize rapidly and for networks, this is a particular problem, because small differences in polymerization conditions, e.g., temperature, initiator concentration, photon flux, etc., can cause a large change in the time evolution of the concentration of carbon double bonds and radicals if these are monitored in separate experiments. The IUPAC Working Party on the Modeling of kinetics and processes of polymerization has the role of recommending the 'best' values for the kinetic parameters, using pulsed-laser polymerization (PLP) in conjunction with molar mass distribution (MMD) to determine k p as a function of temperature (T deg C) for bulk free-radical polymerization of methyl methacrylate at low conversions and ambient temperature. The vinyl radical polymers used in this study were methyl methacrylate and ethylene glycol dimethacrylate. In the past kinetic studies of vinyl photo-polymerization required the time dependence of the monomer and radical concentrations to be monitored separately by using FT-NIR spectroscopy and ESR spectroscopy, respectively. For the systems which polymerize rapidly, small differences in the conditions for two measurements, e.g. temperature and light intensity, can introduce significant errors. Hyphenated experiments involving in-situ ESR and FT-NIR spectroscopies using fibre optic, can overcome these problems. In this paper, the radical and monomer concentrations were measured under the same experimental conditions using the above techniques. The results obtained were used to evaluate the kinetic parameters for free radical vinyl polymerizations

Kinetic Typography

DEFF Research Database (Denmark)

van Leeuwen, Theo; Djonov, Emilia

2014-01-01

After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images.......After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images....

Overproduction of a kinetic subclass of VLDL-apoB, and direct catabolism of VLDL-apoB in human endogenous hypertriglyceridemia: an analytical model solution of tracer data

International Nuclear Information System (INIS)

Eaton, R.P.; Allen, R.C.; Schade, D.S.

1983-01-01

To investigate the participation of the major apoprotein involved in triglyceride transport in the pathogenesis of endogenous hypertriglyceridemia, five kinetic studies of apoprotein B were conducted in volunteer normolipidemic subjects and six studies in four patients with endogenous hypertriglyceridemia. The transport of apoprotein B within four kinetic subclasses of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL) was studied by injection of [ 75 Se]selenomethionine. A 24-fold increase in the entry of newly synthesized apoprotein B at the initial kinetic subclass of the four-compartment VLDL delipidation sequence characterized the hypertriglyceridemic studies relative to normal subjects. Moreover, approximately 75 mg/kg per day of VLDL-B turnover reflected direct catabolism independent of conversion to IDL and/or to LDL, in contrast to the 8 mg/kg per day observed in controls. IDL-B was derived from VLDL-B in both normal and hypertriglyceridemic subjects, and was responsible for greater than 70% of all LDL-B synthesis. LDL-B pool size and turnover were indistinguishable in hypertriglyceridemic subjects from that observed in normal subjects. These studies suggest that two kinetic phenomena may characterize the pathophysiology of endogenous hypertriglyceridemia: a) over-production of apoB within a kinetic subclass of VLDL and b) preferential catabolism of hypertriglyceridemic VLDL without prior conversion to IDL/LDL

Conversion of Oleum papaveris seminis oil into methyl esters via esterification process optimization and kinetic study

Energy Technology Data Exchange (ETDEWEB)

Syam, A.M.; Rashid, U.; Yunus, R.; Hamid, H.A.; Al-Resayes, S.I.; Nehdi, I.A.; Al-Muhtaseb, A.H.

2016-07-01

This paper presents an acid pre-treatment process and a kinetic study for the esterification reaction of Oleum papaveris seminis oil with methanol in the presence of amberlite 120 as a solid catalyst to convert the oil into methyl esters. Response surface methodology (RSM) was applied to optimize the reaction parameters, i.e. reaction time, percentage of the catalyst and volume ratio of methanol to oil. The results revealed that 0.87% w/w of catalyst concentration and 44.70% v/v of methanol to oil ratio provided final free fatty acid (FFA) contents of 0.60% w/w at 102.40 min of reaction time. It proved that the contribution of Amberlite 120 in the esterification of FFA was highly significant. The kinetics of the esterification in Oleum papaveris seminis oil with methanol in the presence of the amberlite 120 catalyst were also investigated to establish the reaction rate constant (k), reaction order, and activation energy. The study was performed under the optimized parameters at three reaction temperatures (50, 55, and 60 ºC). The value of k was in the range of 0.013 to 0.027 min-1. The first-order kinetics’ model was suitable for this irreversible FFA esterification with the activation energy of about 60.9 KJ·mol-1. (Author)

Permanent resident

Directory of Open Access Journals (Sweden)

John F. Fisher

2016-05-01

Full Text Available The training of physicians in the past century was based primarily on responsibility and the chain-of-command. Those with the bulk of that responsibility in the fields of pediatrics and internal medicine were residents. Residents trained the medical students and supervised them carefully in caring for patients. Most attending physicians supervised their teams at arm's length, primarily serving as teachers of the finer points of diagnosis and treatment during set periods of the day or week with a perfunctory signature on write-ups or progress notes. Residents endeavored to protect the attending physician from being heavily involved unless they were unsure about a clinical problem. Before contacting the attending physician, a more senior resident would be called. Responsibility was the ultimate teacher. The introduction of diagnosis-related groups by the federal government dramatically changed the health care delivery system, placing greater emphasis on attending physician visibility in the medical record, ultimately resulting in more attending physician involvement in day-to-day care of patients in academic institutions. Without specified content in attending notes, hospital revenues would decline. Although always in charge technically, attending physicians increasingly have assumed the role once dominated by the resident. Using biographical experiences of more than 40 years, the author acknowledges and praises the educational role of responsibility in his own training and laments its declining role in today's students and house staff.

Cluster-cluster aggregation kinetics and primary particle growth of soot nanoparticles in flame by light scattering and numerical simulations.

Science.gov (United States)

di Stasio, Stefano; Konstandopoulos, Athanasios G; Kostoglou, Margaritis

2002-03-01

The agglomeration kinetics of growing soot generated in a diffusion atmospheric flame are here studied in situ by light scattering technique to infer cluster morphology and size (fractal dimension D(f) and radius of gyration R(g)). SEM analysis is used as a standard reference to obtain primary particle size D(P) at different residence times. The number N(P) of primary particles per aggregate and the number concentration n(A) of clusters are evaluated on the basis of the measured angular patterns of the scattered light intensity. The major finding is that the kinetics of the coagulation process that yields to the formation of chain-like aggregates by soot primary particles (size 10 to 40 nm) can be described with a constant coagulation kernel beta(c,exp)=2.37x10(-9) cm3/s (coagulation constant tau(c) approximately = 0.28 ms). This result is in nice accord with the Smoluchowski coagulation equation in the free molecular regime, and, vice versa, it is in contrast with previous studies conducted by invasive (ex situ) techniques, which claimed the evidence in flames of coagulation rates much larger than the kinetic theory predictions. Thereafter, a number of numerical simulations is implemented to compare with the experimental results on primary particle growth rate and on the process of aggregate reshaping that is observed by light scattering at later residence times. The restructuring process is conjectured to occur, for not well understood reasons, as a direct consequence of the atomic rearrangement in the solid phase carbon due to the prolonged residence time within the flame. Thus, on one side, it is shown that the numerical simulations of primary size history compare well with the values of primary size from SEM experiment with a growth rate constant of primary diameter about 1 nm/s. On the other side, the evolution of aggregate morphology is found to be predictable by the numerical simulations when the onset of a first-order "thermal" restructuring mechanism is

Study of solid phase kinetics during cyanidation using the 198 Au radioactive tracer

International Nuclear Information System (INIS)

Barbus, A.; Pop, I.I.; Gaspar, E.

1995-01-01

During cyanidation, the various gold bearing pyrite sorts exhibit different behaviour, that sometimes cause increased cyanidation times influencing the reagent and power consumption, in the same time generating fluctuations in the recovery efficiencies. The introduction of the 198 Au radioactive tracer into the cyanidation circuit enabled us to follow several parameters of the cyanidation kinetics: the average residence time of the gold bearing pyrite in the technological equipment, information about the homogenization process, dispersion of solids and gold dissolution efficiency on each technological stage. (author)

Career Interests of Canadian Psychiatry Residents: What Makes Residents Choose a Research Career?

Science.gov (United States)

Laliberté, Vincent; Rapoport, Mark J.; Andrew, Melissa; Davidson, Marla

2016-01-01

Objectives: Training future clinician-researchers remains a challenge faced by Canadian psychiatry departments. Our objectives were to determine the prevalence of residents interested in pursuing research and other career options as part of their practice, and to identify the factors associated with interest in research. Method: Data from a national online survey of 207 Canadian psychiatry residents from a total of 853 (24.3% response rate) were examined. The main outcome was interest in research as part of residents’ future psychiatrist practice. Bivariate and multivariate analyses were performed to identify demographic and vocational variables associated with research interest. Results: Interest in research decreases by 76% between the first and fifth year of psychiatry residency (OR 0.76 per year, 95% CI 0.60 to 0.97). Training in a department with a residency research track did not correlate with increased research interest (χ2 = 0.007, df = 1, P = 0.93). Conclusions: Exposing and engaging psychiatry residents in research as early as possible in residency training appears key to promoting future research interest. Psychiatry residency programs and research tracks could consider emphasizing research training initiatives and protected research time early in residency. PMID:27253699

Electro-Kinetic Pumping with Slip Irreversibility in Heat Exchange of CSP-Powered Bio-Digester Assemblies

OpenAIRE

Ogedengbe, Emmanuel; Rosen, Marc

2012-01-01

Parametric studies of the effects of slip irreversibility in concentrating solar power (CSP)-powered bio-digester assemblies are investigated. Complexities regarding the identification of the appropriate electro-kinetic phenomena for certain electrolyte phases are reviewed. The application of exergy analysis to the design of energy conversion devices, like solar thermal collectors, for the required heat of formation in a downdraft waste food bio-digester, is discussed. Thermal management in t...

Results of the 2005-2008 Association of Residents in Radiation Oncology Survey of Chief Residents in the United States: Clinical Training and Resident Working Conditions

International Nuclear Information System (INIS)

Gondi, Vinai; Bernard, Johnny Ray; Jabbari, Siavash; Keam, Jennifer; Amorim Bernstein, Karen L. de; Dad, Luqman K.; Li, Linna; Poppe, Matthew M.; Strauss, Jonathan B.; Chollet, Casey T.

2011-01-01

Purpose: To document clinical training and resident working conditions reported by chief residents during their residency. Methods and Materials: During the academic years 2005 to 2006, 2006 to 2007, and 2007 to 2008, the Association of Residents in Radiation Oncology conducted a nationwide survey of all radiation oncology chief residents in the United States. Chi-square statistics were used to assess changes in clinical training and resident working conditions over time. Results: Surveys were completed by representatives from 55 programs (response rate, 71.4%) in 2005 to 2006, 60 programs (75.9%) in 2006 to 2007, and 74 programs (93.7%) in 2007 to 2008. Nearly all chief residents reported receiving adequate clinical experience in commonly treated disease sites, such as breast and genitourinary malignancies; and commonly performed procedures, such as three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. Clinical experience in extracranial stereotactic radiotherapy increased over time (p < 0.001), whereas clinical experience in endovascular brachytherapy (p <0.001) decreased over time. The distribution of gynecologic and prostate brachytherapy cases remained stable, while clinical case load in breast brachytherapy increased (p = 0.006). A small but significant percentage of residents reported receiving inadequate clinical experience in pediatrics, seeing 10 or fewer pediatric cases during the course of residency. Procedures involving higher capital costs, such as particle beam therapy and intraoperative radiotherapy, and infrequent clinical use, such as head and neck brachytherapy, were limited to a minority of institutions. Most residency programs associated with at least one satellite facility have incorporated resident rotations into their clinical training, and the majority of residents at these programs find them valuable experiences. The majority of residents reported working 60 or fewer hours per week on required clinical duties

Ontario Radiation Oncology Residents' Needs in the First Postgraduate Year-Residents' Perspective Survey

International Nuclear Information System (INIS)

Szumacher, Ewa; Warner, Eiran; Zhang Liying; Kane, Gabrielle; Ackerman, Ida; Nyhof-Young, Joyce; Agboola, Olusegun; Metz, Catherine de; Rodrigues, George; Voruganti, Sachi; Rappolt, Susan

2007-01-01

Purpose: To assess radiation oncology residents' needs and satisfaction in their first postgraduate year (PGY-1) in the province of Ontario. Methods and Materials: Of 62 radiation oncology residents, 58 who had completed their PGY-1 and were either enrolled or had graduated in 2006 were invited to participate in a 31-item survey. The questionnaire explored PGY-1 residents' needs and satisfaction in four domains: clinical workload, faculty/learning environment, stress level, and discrimination/harassment. The Fisher's exact and Wilcoxon nonparametric tests were used to determine relationships between covariate items and summary scores. Results: Of 58 eligible residents, 44 (75%) responded. Eighty-four percent of residents felt that their ward and call duties were appropriate. More than 50% of respondents indicated that they often felt isolated from their radiation oncology program. Only 77% agreed that they received adequate feedback, and 40% received sufficient counseling regarding career planning. More than 93% of respondents thought that faculty members had contributed significantly to their learning experience. Approximately 50% of residents experienced excessive stress and inadequate time for leisure or for reading the medical literature. Less than 10% of residents indicated that they had been harassed or experienced discrimination. Eighty-three percent agreed or strongly agreed that their PGY-1 experience had been outstanding. Conclusions: Most Ontario residents were satisfied with their PGY-1 training program. More counseling by radiation oncology faculty members should be offered to help residents with career planning. The residents might also benefit from more exposure to 'radiation oncology' and an introduction to stress management strategies

Residency Allocation Database

Data.gov (United States)

Department of Veterans Affairs — The Residency Allocation Database is used to determine allocation of funds for residency programs offered by Veterans Affairs Medical Centers (VAMCs). Information...

Kinetic modeling of hydrocracking reaction in a trickle-bed reactor with Pt/Y-zeolite catalysts

Energy Technology Data Exchange (ETDEWEB)

Lee, BalSang; Park, Myung-June; Kim, Young-A; Park, Eun Duck [Ajou University, Suwon (Korea, Republic of); Han, Jeongsik [Agency for Defense Development, Daejeon (Korea, Republic of); Jeong, Kwang-Eun; Kim, Chul-Ung; Jeong, Soon-Yong [Korea Research Institute of Chemical Technology (KRICT), Daejeon (Korea, Republic of)

2014-03-15

A kinetic model is developed to predict the entire distribution of hydrocarbon products for the hydrocracking reaction with Pt/Y-zeolite catalysts in a trickle-bed reactor. Operating conditions, such as temperature, pressure, and wax and H{sub 2} flow rates were varied to evaluate their effects on conversion and distribution, and kinetic parameters were estimated using the experimental data that covers the window of operating conditions. The comparison between experimental data and simulated results corroborated the validity of the developed model, and the quantitative prediction of the reactor performance was clearly demonstrated. To make evident the usefulness of the model, an optimization method, genetic algorithm (GA), was applied, and the optimal condition for the maximum production of C{sub 10}-C{sub 17} was successfully calculated.

Kinetic modeling of hydrocracking reaction in a trickle-bed reactor with Pt/Y-zeolite catalysts

International Nuclear Information System (INIS)

Lee, BalSang; Park, Myung-June; Kim, Young-A; Park, Eun Duck; Han, Jeongsik; Jeong, Kwang-Eun; Kim, Chul-Ung; Jeong, Soon-Yong

2014-01-01

A kinetic model is developed to predict the entire distribution of hydrocarbon products for the hydrocracking reaction with Pt/Y-zeolite catalysts in a trickle-bed reactor. Operating conditions, such as temperature, pressure, and wax and H 2 flow rates were varied to evaluate their effects on conversion and distribution, and kinetic parameters were estimated using the experimental data that covers the window of operating conditions. The comparison between experimental data and simulated results corroborated the validity of the developed model, and the quantitative prediction of the reactor performance was clearly demonstrated. To make evident the usefulness of the model, an optimization method, genetic algorithm (GA), was applied, and the optimal condition for the maximum production of C 10 -C 17 was successfully calculated

Kinetic model for hydrothermal biomass gasification; Kinetisches Modell der hydrothermalen Biomassevergasung

Energy Technology Data Exchange (ETDEWEB)

Kruse, A.; Keskin, M.; Faquir, M.; Dahmen, N. [Inst. fuer Technische Chemie, Forschungszentrum Karlsruhe (Germany)

2008-07-01

Hydrothermal biomass gasification is a promising technology to produce hydrogen from wet biomass, i.e. a water content of at least 50 %. This process allows the utilization of agricultural wastes or residuals from biochemical conversions. Since the reaction is highly kinetically controlled, it should be possible to optimimize gas yield and composition with respect to a maximum hydrogen yield. The paper describes the simulation of the process using a kinetic reaction model and experimental data from appropriate test facilities. Experiments were performed for several reactor types and a variety of model systems, like glucose, methane and hydroxy methyl furfural, that were identified as intermediate product for the hydrothermal hydrogen production. The influence of different additive 'catalysts' was tested. It was shown that the biomass composition has an important influence on the gas yield. Alkaline salts can be added to increase the yield. A fast heating and agitation of the biomass are also increasing the gas yield.

Improvement of skeleton conversion in ICRP reference phantom conversion project

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of); Kim, Seong Hoon [Dept. of Radiation Oncology, College of Medicine, Hanyang University, Seoul (Korea, Republic of)

2014-11-15

In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future.

Improvement of skeleton conversion in ICRP reference phantom conversion project

International Nuclear Information System (INIS)

Wang, Zhao Jun; Yeom, Yeon Soo; Thang, Nguyen Tat; Kim, Han Sung; Han, Min Cheol; Kim, Chan Hyeong; Kim, Seong Hoon

2014-01-01

In the previous skeleton conversion, most bones were directly converted from the ICRP voxel phantoms by using the 3D rendering method whereas several complex-shape bones (cranium, ribs, spines, feet, and hands) were not able to be directly converted. We alternatively employed the corresponding well-defined polygonal models and attempted to adjust them to match the voxel models. However, this approach was unsatisfactory. The shapes of the alternative models were significantly different from those of the voxel models, making it virtually impossible to exactly match the voxel models as shown in Fig. 3 (left). In order to overcome the difficulty in the complex bone conversion, the present study developed a new conversion method and converted these complex bones voxel models of the ICRP male phantom to polygonal models. The present study developed the new conversion method and successfully improved polygonal models for cranium, ribs, and spines for the ICRP male phantom. The new conversion method will be also applied to the complex bone conversion for the ICRP female phantom as well as other complex organ conversion in the future

Association of General Surgery Resident Remediation and Program Director Attitudes With Resident Attrition.

Science.gov (United States)

Schwed, Alexander C; Lee, Steven L; Salcedo, Edgardo S; Reeves, Mark E; Inaba, Kenji; Sidwell, Richard A; Amersi, Farin; Are, Chandrakanth; Arnell, Tracey D; Damewood, Richard B; Dent, Daniel L; Donahue, Timothy; Gauvin, Jeffrey; Hartranft, Thomas; Jacobsen, Garth R; Jarman, Benjamin T; Melcher, Marc L; Mellinger, John D; Morris, Jon B; Nehler, Mark; Smith, Brian R; Wolfe, Mary; Kaji, Amy H; de Virgilio, Christian

2017-12-01

Previous studies of resident attrition have variably included preliminary residents and likely overestimated categorical resident attrition. Whether program director attitudes affect attrition has been unclear. To determine whether program director attitudes are associated with resident attrition and to measure the categorical resident attrition rate. This multicenter study surveyed 21 US program directors in general surgery about their opinions regarding resident education and attrition. Data on total resident complement, demographic information, and annual attrition were collected from the program directors for the study period of July 1, 2010, to June 30, 2015. The general surgery programs were chosen on the basis of their geographic location, previous collaboration with some coauthors, prior work in surgical education and research, or a program director willing to participate. Only categorical surgical residents were included in the study; thus, program directors were specifically instructed to exclude any preliminary residents in their responses. Five-year attrition rates (2010-2011 to 2014-2015 academic years) as well as first-time pass rates on the General Surgery Qualifying Examination and General Surgery Certifying Examination of the American Board of Surgery (ABS) were collected. High- and low-attrition programs were compared. The 21 programs represented different geographic locations and 12 university-based, 3 university-affiliated, and 6 independent program types. Programs had a median (interquartile range [IQR]) number of 30 (20-48) categorical residents, and few of those residents were women (median [IQR], 12 [5-17]). Overall, 85 of 966 residents (8.8%) left training during the study period: 15 (17.6%) left after postgraduate year 1, 34 (40.0%) after postgraduate year 2, and 36 (42.4%) after postgraduate year 3 or later. Forty-four residents (51.8%) left general surgery for another surgical discipline, 21 (24.7%) transferred to a different surgery

Diffusion and reaction within porous packing media: a phenomenological model.

Science.gov (United States)

Jones, W L; Dockery, J D; Vogel, C R; Sturman, P J

1993-04-25

A phenomenological model has been developed to describe biomass distribution and substrate depletion in porous diatomaceous earth (DE) pellets colonized by Pseudomonas aeruginosa. The essential features of the model are diffusion, attachment and detachment to/from pore walls of the biomass, diffusion of substrate within the pellet, and external mass transfer of both substrate and biomass in the bulk fluid of a packed bed containing the pellets. A bench-scale reactor filled with DE pellets was inoculated with P. aeruginosa and operated in plug flow without recycle using a feed containing glucose as the limiting nutrient. Steady-state effluent glucose concentrations were measured at various residence times, and biomass distribution within the pellet was measured at the lowest residence time. In the model, microorganism/substrate kinetics and mass transfer characteristics were predicted from the literature. Only the attachment and detachment parameters were treated as unknowns, and were determined by fitting biomass distribution data within the pellets to the mathematical model. The rate-limiting step in substrate conversion was determined to be internal mass transfer resistance; external mass transfer resistance and microbial kinetic limitations were found to be nearly negligible. Only the outer 5% of the pellets contributed to substrate conversion.

Dynamic Model of Basic Oxygen Steelmaking Process Based on Multi-zone Reaction Kinetics: Model Derivation and Validation

Science.gov (United States)

Rout, Bapin Kumar; Brooks, Geoff; Rhamdhani, M. Akbar; Li, Zushu; Schrama, Frank N. H.; Sun, Jianjun

2018-04-01

A multi-zone kinetic model coupled with a dynamic slag generation model was developed for the simulation of hot metal and slag composition during the basic oxygen furnace (BOF) operation. The three reaction zones (i) jet impact zone, (ii) slag-bulk metal zone, (iii) slag-metal-gas emulsion zone were considered for the calculation of overall refining kinetics. In the rate equations, the transient rate parameters were mathematically described as a function of process variables. A micro and macroscopic rate calculation methodology (micro-kinetics and macro-kinetics) were developed to estimate the total refining contributed by the recirculating metal droplets through the slag-metal emulsion zone. The micro-kinetics involves developing the rate equation for individual droplets in the emulsion. The mathematical models for the size distribution of initial droplets, kinetics of simultaneous refining of elements, the residence time in the emulsion, and dynamic interfacial area change were established in the micro-kinetic model. In the macro-kinetics calculation, a droplet generation model was employed and the total amount of refining by emulsion was calculated by summing the refining from the entire population of returning droplets. A dynamic FetO generation model based on oxygen mass balance was developed and coupled with the multi-zone kinetic model. The effect of post-combustion on the evolution of slag and metal composition was investigated. The model was applied to a 200-ton top blowing converter and the simulated value of metal and slag was found to be in good agreement with the measured data. The post-combustion ratio was found to be an important factor in controlling FetO content in the slag and the kinetics of Mn and P in a BOF process.

Model-free pyrolysis kinetics of sunflower seed and its de-oiled cake

International Nuclear Information System (INIS)

Özsin, Gamzenur; Kilic, Murat; Pütün, Ersan; Pütün, Ayşe E.

2015-01-01

Sunflower seed wastes from oil production are a potential biomass source for bio- energy production due to extensive and excessive oil production from sunflower seeds. Considering global energy requirement, pyrolysis seems a promising route for utilisation of such industrial biomass wastes. To develop, scale-up and operate pyrolysis plants efficiently, a fundamental understanding of pyrolysis behaviour and kinetics is essential. In this study, sunflower seeds and their waste cakes after extraction were evaluated as a potential biomass feedstock in pyrolysis process. In order to enlighten pyrolytic degradation behaviours, samples were pyrolysed under dynamic conditions from room temperature to 1000 °C using multiple heating rates. The main degradation regimes of the structures were characterized by high weight loss rates. Reaction kinetics was investigated with respect to conversion degree. It is anticipated that this study will be beneficial in optimizing the thermochemical processes, which may be utilize industrial biomass wastes. (full text)

Resident Characteristics Report

Data.gov (United States)

Department of Housing and Urban Development — The Resident Characteristics Report summarizes general information about households who reside in Public Housing, or who receive Section 8 assistance. The report...

Relevance and bio-catalytic strategies for the kinetic resolution of ketoprofen towards dexketoprofen.

Science.gov (United States)

Toledo, María Victoria; Briand, Laura Estefanía

2017-11-10

This review presents the most relevant investigations concerning the biocatalytic kinetic resolution of racemic ketoprofen to dexketoprofen for the last 22 years. The advantages related to the administration of the dex-enantiomer in terms of human health, the so called "chiral switch" in the pharmaceutical industry and the sustainability of biotransformations have been the driving forces to develop innovative technology to obtain dexketoprofen. In particular, the kinetic resolution of racemic ketoprofen through enantiomeric esterification and hydrolysis using lipases as biocatalysts are thoroughly revised and commented upon. In this context, the biocatalysts, acyl-acceptors (alcohols), reaction conditions, conversion, enantiomeric excess, and enantiomeric ratio among others are discussed. Moreover, the investigations concerning scaling up processes in order to obtain an optically pure enantiomer of the profen are presented. Finally, some guidelines about perspectives of the technology and research opportunities are given.

Sandia’s Current Energy Conversion module for the Flexible-Mesh Delft3D flow solver v. 1.0

Energy Technology Data Exchange (ETDEWEB)

2018-04-25

The DOE has funded Sandia National Labs (SNL) to develop an open-source modeling tool to guide the design and layout of marine hydrokinetic (MHK) arrays to maximize power production while minimizing environmental effects. This modeling framework simulates flows through and around a MHK arrays while quantifying environmental responses. As an augmented version of the Dutch company, Deltares’s, environmental hydrodynamics code, Delft3D, SNL-Delft3D-CEC-FM includes a new module that simulates energy conversion (momentum withdrawal) by MHK current energy conversion devices with commensurate changes in the turbulent kinetic energy and its dissipation rate. SNL-Delft3D-CEC-FM modified the Delft3D flexible mesh flow solver, DFlowFM.

Modeling the Influence of Diffusion-Controlled Reactions and Residual Termination and Deactivation on the Rate and Control of Bulk ATRP at High Conversions

Directory of Open Access Journals (Sweden)

Ali Mohammad Rabea

2015-04-01

Full Text Available In high-conversion atom transfer radical polymerization (ATRP, all the reactions, such as radical termination, radical deactivation, dormant chain activation, monomer propagation, etc. could become diffusion controlled sooner or later, depending on relative diffusivities of the involved reacting species. These diffusion-controlled reactions directly affect the rate of polymerization and the control of polymer molecular weight. A model is developed to investigate the influence of diffusion-controlled reactions on the high conversion ATRP kinetics. Model simulation reveals that diffusion-controlled termination slightly increases the rate, but it is the diffusion-controlled deactivation that causes auto-acceleration in the rate (“gel effect” and loss of control. At high conversions, radical chains are “trapped” because of high molecular weight. However, radical centers can still migrate through (1 radical deactivation–activation cycles and (2 monomer propagation, which introduce “residual termination” reactions. It is found that the “residual termination” does not have much influence on the polymerization kinetics. The migration of radical centers through propagation can however facilitate catalytic deactivation of radicals, which improves the control of polymer molecular weight to some extent. Dormant chain activation and monomer propagation also become diffusion controlled and finally stop the polymerization when the system approaches its glass state.

Status of HEU-LEU conversion of FRJ-2

International Nuclear Information System (INIS)

Damm, G.; Nabbi, R.

2002-01-01

The operator of the German FRJ-2 research reactor, 'Research Center Juelich', has participated from the beginning in the RERTR programme and made comprehensive contributions to the test and use of LEU fuel for HEU-LEU-conversion measures. The originally planned time scale for the conversion of FRJ-2 was significantly delayed because of a change of the manufacturer of the LEU fuel elements and a 4 years shutdown of the reactor for refurbishment purposes. In the meantime the new LEU fuel elements are qualified and tested in the reactor. In the moment calculations for the safety report are made and it is planned to apply for the license of FRJ-2 operation with LEU fuel at the beginning of 2003. In order to get most reliable results a sophisticated computational method based on a MCNP model coupled with the depletion code BURN was developed for reactor physical calculations, core conversion studies and fuel element performance analysis and applied to the mixed and LEU core. The licensing schedule and results of latest calculations for the conversion study will be presented. The simulations shows that the thermal flux in the LEU core is about 19% resulting in a lower burnup rate. But in the reflector area around the core and in the center of the cold n source the neutron flux reduction remains limited to 6%. Due to a harder neutron spectrum in the LEU core the kinetic and safety related parameters are slightly reduced. Using the ORIGEN code it could be shown that the increase of the total fission products inventory amounts to about 6% compared to a HEU core. As a consequence of the high amount of U-238, the amount of U-235 in the LEU core has to be about 27% higher than in the HEU core but the U-235 burnup is approx. 5% lower due to the contribution of fissile plutonium. (author)

[Burnout in nursing residents].

Science.gov (United States)

Franco, Gianfábio Pimentel; de Barros, Alba Lúcia Bottura Leite; Nogueira-Martins, Luiz Antônio; Zeitoun, Sandra Salloum

2011-03-01

Nursing residents may experience physical and emotional exhaustion from the daily life of attending the Program. The aim of this study was to determine the Burnout incidence among Nursing Residents. An investigative, descriptive, analytical, longitudinal-prospective study was conducted with 16 Residents over two years. The Maslach Burnout Inventory was used, translated and validated for Brazil, as well as a sociodemographic/occupational data tool. Of all residents, 17.2% showed high rates in Emotional Exhaustion and Depersonalization; 18.8% showed impaired commitment in Personal Accomplishment, 75% of which belonged to specialty areas, such as Emergency Nursing, Adult and Pediatric Intensive Care. Age and specialty area were positively correlated with Personal Accomplishment. One of the Residents was identified with changes in three subscales of the Maslach Burnout Inventory, thus characterized as a Burnout Syndrome patient. Nursing Residents have profiles of disease. Knowing these factors can minimize health risks of these workers.

Discourse analysis: Conversational analysis of the internal conversation in Oracle Corporation Malaysia

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Marwa Marwa

2017-07-01

Full Text Available This study highlights the internal conversation which takes place in Oracle CorporationMalaysia. Through the study, it will be shown how conversational analysis is used toanalyze the transcription of a telephone conversation between Oracle staffs. The analysisof the transcriptions will apply a few basic concepts of conversational analysis; turntakingorganization, and the adjacency pair. The objective of the study is to find out howthe internal conversations takes place by focusing on the conversation itself, that is, theconversational structures spontaneously produced by people during talk ranging fromturn-taking strategies, how topics are introduced, conversation closings and so on. Bylooking in detail at such talk, we can gain a detailed understanding of how the staffs seethemselves in relation to the company that influence their daily lives.Keywords: conversational analysis, turn-taking, adjacency pairs

Reproductive Psychiatry Residency Training: A Survey of Psychiatric Residency Program Directors.

Science.gov (United States)

Osborne, Lauren M; MacLean, Joanna V; Barzilay, Erin Murphy; Meltzer-Brody, Samantha; Miller, Laura; Yang, Sarah Nagle

2018-04-01

The reproductive life cycle has unique influences on the phenotypic expression of mental illness in women. Didactic and clinical training focused on these sex-specific influences should be a vital component of the education of future psychiatrists. The authors sought to determine the current state of and attitudes toward reproductive psychiatry in resident education. The authors administered a web-based survey to psychiatry residency training directors. They assessed the availability of both mandated and optional didactic and clinical training experiences in reproductive psychiatry. Fifty residency program directors answered the survey, for a response rate of 28%. More than half of residency program directors (59%) reported requiring some training in reproductive psychiatry. Both the breadth and depth of topics covered varied greatly among programs. Lack of time (48%) and lack of qualified faculty (26%) were the most frequently cited barriers to more training. Only 40% of residency directors surveyed agreed that all residents should be competent in reproductive psychiatry. These findings suggest that specific training in reproductive psychiatry is inconsistent in US residency programs, and that training that does exist varies considerably in clinical time and content. Given that women comprise more than 50% of all psychiatric patients and most women will menstruate, give birth, and undergo menopause, future psychiatrists would benefit from more systematic instruction in this area. The authors propose the development of a national, standardized reproductive psychiatry curriculum to address this gap and aid in producing psychiatrists competent to treat women at all stages of life.

Kinetic Evaluation of Lipid Oils Conversion to Biofuel Using Layered Double Hydroxide Doped with Triazabicyclodece Catalyst

Science.gov (United States)

Nato Lopez, Frank D.

Worldwide, there is an ever increasing need for sustainable, renewable fuels that will accommodate the rapidly increasing energy demand and provide independence from fossil fuels. The search for a sustainable alternative to petroleum based fuels has been a great challenge to the scientific community; therefore, great efforts are being made to overcome the fossil fuels dependence by exploring the prominent field of biofuels (bioethanol and biodiesel). Traditional biodiesel is produced from feedstocks such as vegetable oils and animal fats by converting the triglycerides with methanol in the presence of a homogeneous catalyst to produce fatty acid methyl esters (FAMEs). However, drawbacks of this process are the undesired glycerol byproduct and post reaction processing, including separation from reaction mixture, that results in high costs factors. In the present work, the reaction kinetics of a glycerol-free biodiesel method is studied. This method consists of the transesterification of a vegetable oil (i.e. canola oil) using dimethyl carbonate (DMC) as an alternative methylating agent in presence of layered double hydroxides doped with triazabicyclodecene catalyst (a basic organocatalyst). Furthermore, is theorized that this heterogeneous catalyst (TBD/LDH) simultaneously converts both FFAs and triglycerides due to acid sites formed by Al3+ active sites of the LDH structure. Additionally, the versatility of the Raman in situ technique was used as quantitative analysis tool to monitor the reaction kinetics and collect real time data.

NONLINEAR OPTICAL PHENOMENA Intracavity SRS conversion in diode-pumpedmultifunctional Nd3+:SrMoO4 laser crystal

Science.gov (United States)

Basiev, Tasoltan T.; Smetanin, Sergei N.; Fedin, Aleksandr V.; Shurygin, Anton S.

2010-10-01

Lasing of a miniature all-solid-state SRS laser based on a Nd3+:SrMoO4 crystal with a LiF:F2--passive Q-switch is studied. The dependences of the laser and SRS self-conversion parameters on the initial transmission of the passive Q-switch are studied experimentally and theoretically. Simulation of the lasing kinetics has shown the possibility of nonlinear cavity dumping upon highly efficient SRS self-conversion of laser radiation. An increase in the active medium length from 1 to 3mm resulted in an increase in the energy of the output 1.17-μm SRS radiation from 20 μJ to record-high 60 μJ at the absorbed multimode diode pump energy of 3.7 mJ.

Estimating global "blue carbon" emissions from conversion and degradation of vegetated coastal ecosystems.

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Linwood Pendleton

Full Text Available Recent attention has focused on the high rates of annual carbon sequestration in vegetated coastal ecosystems--marshes, mangroves, and seagrasses--that may be lost with habitat destruction ('conversion'. Relatively unappreciated, however, is that conversion of these coastal ecosystems also impacts very large pools of previously-sequestered carbon. Residing mostly in sediments, this 'blue carbon' can be released to the atmosphere when these ecosystems are converted or degraded. Here we provide the first global estimates of this impact and evaluate its economic implications. Combining the best available data on global area, land-use conversion rates, and near-surface carbon stocks in each of the three ecosystems, using an uncertainty-propagation approach, we estimate that 0.15-1.02 Pg (billion tons of carbon dioxide are being released annually, several times higher than previous estimates that account only for lost sequestration. These emissions are equivalent to 3-19% of those from deforestation globally, and result in economic damages of $US 6-42 billion annually. The largest sources of uncertainty in these estimates stems from limited certitude in global area and rates of land-use conversion, but research is also needed on the fates of ecosystem carbon upon conversion. Currently, carbon emissions from the conversion of vegetated coastal ecosystems are not included in emissions accounting or carbon market protocols, but this analysis suggests they may be disproportionally important to both. Although the relevant science supporting these initial estimates will need to be refined in coming years, it is clear that policies encouraging the sustainable management of coastal ecosystems could significantly reduce carbon emissions from the land-use sector, in addition to sustaining the well-recognized ecosystem services of coastal habitats.

An operando FTIR spectroscopic and kinetic study of carbon monoxide pressure influence on rhodium-catalyzed olefin hydroformylation.

Science.gov (United States)

Kubis, Christoph; Sawall, Mathias; Block, Axel; Neymeyr, Klaus; Ludwig, Ralf; Börner, Armin; Selent, Detlef

2014-09-08

The influence of carbon monoxide concentration on the kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a phosphite-modified rhodium catalyst has been studied for the pressure range p(CO)=0.20-3.83 MPa. Highly resolved time-dependent concentration profiles of the organometallic intermediates were derived from IR spectroscopic data collected in situ for the entire olefin-conversion range. The dynamics of the catalyst and organic components are described by enzyme-type kinetics with competitive and uncompetitive inhibition reactions involving carbon monoxide taken into account. Saturation of the alkyl-rhodium intermediates with carbon monoxide as a cosubstrate occurs between 1.5 and 2 MPa of carbon monoxide pressure, which brings about a convergence of aldehyde regioselectivity. Hydrogenolysis of the acyl intermediate is fast at 30 °C and low pressure of p(CO)=0.2 MPa, but is of minus first order with respect to the solution concentration of carbon monoxide. Resting 18-electron hydrido and acyl complexes that correspond to early and late rate-determining states, respectively, coexist as long as the conversion of the substrate is not complete. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

How Residents Learn From Patient Feedback: A Multi-Institutional Qualitative Study of Pediatrics Residents' Perspectives.

Science.gov (United States)

Bogetz, Alyssa L; Orlov, Nicola; Blankenburg, Rebecca; Bhavaraju, Vasudha; McQueen, Alisa; Rassbach, Caroline

2018-04-01

Residents may view feedback from patients and their families with greater skepticism than feedback from supervisors and peers. While discussing patient and family feedback with faculty may improve residents' acceptance of feedback and learning, specific strategies have not been identified. We explored pediatrics residents' perspectives of patient feedback and identified strategies that promote residents' reflection on and learning from feedback. In this multi-institutional, qualitative study conducted in June and July 2016, we conducted focus groups with a purposive sample of pediatrics residents after their participation in a randomized controlled trial in which they received written patient feedback and either discussed it with faculty or reviewed it independently. Focus group transcripts were audiorecorded, transcribed, and analyzed for themes using the constant comparative approach associated with grounded theory. Thirty-six of 92 (39%) residents participated in 7 focus groups. Four themes emerged: (1) residents valued patient feedback but felt it may lack the specificity they desire; (2) discussing feedback with a trusted faculty member was helpful for self-reflection; (3) residents identified 5 strategies faculty used to facilitate their openness to and acceptance of patient feedback (eg, help resident overcome emotional responses to feedback and situate feedback in the context of lifelong learning); and (4) residents' perceptions of feedback credibility improved when faculty observed patient encounters and solicited feedback on the resident's behalf prior to discussions. Discussing patient feedback with faculty provided important scaffolding to enhance residents' openness to and reflection on patient feedback.

A bibliographic review of mathematical models of packed-bed biological reactors (PBR

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Deisy Corredor

2005-09-01

Full Text Available Several authors have sublected packed-bed biological reactors to mathematical and theoretical analysis. They have taken reaction kinetics and single-dimensional, homogeneous, pseudo-homogeneous and heterogeneous models into account. Numerical methods have provided the set of equations so developed. The effect of physically important process variables in terms of design and operation have been investigated (i.e. residence time, operating- flow, substrate conversion, bio-film area and film thickness.

The pregnant female surgical resident

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Shifflette V

2018-05-01

Full Text Available Vanessa Shifflette,1 Susannah Hambright,2 Joseph Darryl Amos,1 Ernest Dunn,3 Maria Allo4 1Associates in Surgical Acute Care, Methodist Dallas Medical Center, Dallas, TX, USA; 2Methodist Surgical Associates, Methodist Dallas Medical Center, Dallas, TX, USA; 3Graduate Medical Education - General Surgery, Methodist Dallas Medical Center, Dallas, TX, USA; 4Santa Clara Valley Medical Center, San Jose, CA, USA Background: Surgery continues to be an intense, time-consuming residency. Many medical students decide against surgery as a profession due to the long work hours and family strain. The pregnant female surgical resident has an added stress factor compared to her male counterpart. Methods: We distributed an electronic, online 26-question survey to 32 general surgery programs in the southwestern region of the United States. Each program distributed our survey to the female surgical residents who had been pregnant during residency in the last 5 years. Each program was re-contacted 6 weeks after the initial contact. Most questions were in a 5-point Likert scale format. The responses were collected and analyzed using the Survey Monkey website. Results: An unvalidated survey was sent to 32 general surgery programs and 26 programs responded (81%. Each program was asked for the total number of possible responses from female residents that met our criteria (60 female residents. Seven of the programs (27% stated that they have had zero residents pregnant. We had 22 residents respond (37%. Over half of the residents (55% were pregnant during their 2nd or 3rd year of residency, with only 18% pregnant during a research year. Thirty-one percent had a lower American Board of Surgery In-Training Exam (ABSITE score. Ninety percent of the residents were able to take 4 weeks or more for maternity leave. Most of the residents (95% stated that they would do this again during residency given the opportunity, but many of the residents felt that returning back to work

Use and utility of Web-based residency program information: a survey of residency applicants.

Science.gov (United States)

Embi, Peter J; Desai, Sima; Cooney, Thomas G

2003-01-01

The Internet has become essential to the residency application process. In recent years, applicants and residency programs have used the Internet-based tools of the National Residency Matching Program (NRMP, the Match) and the Electronic Residency Application Service (ERAS) to process and manage application and Match information. In addition, many residency programs have moved their recruitment information from printed brochures to Web sites. Despite this change, little is known about how applicants use residency program Web sites and what constitutes optimal residency Web site content, information that is critical to developing and maintaining such sites. To study the use and perceived utility of Web-based residency program information by surveying applicants to an internal medicine program. Our sample population was the applicants to the Oregon Health & Science University Internal Medicine Residency Program who were invited for an interview. We solicited participation using the group e-mail feature available through the Electronic Residency Application Service Post-Office application. To minimize the possibility for biased responses, the study was confined to the period between submission of National Residency Matching Program rank-order lists and release of Match results. Applicants could respond using an anonymous Web-based form or by reply to the e-mail solicitation. We tabulated responses, calculated percentages for each, and performed a qualitative analysis of comments. Of the 431 potential participants, 218 responded (51%) during the study period. Ninety-nine percent reported comfort browsing the Web; 52% accessed the Web primarily from home. Sixty-nine percent learned about residency Web sites primarily from residency-specific directories while 19% relied on general directories. Eighty percent found these sites helpful when deciding where to apply, 69% when deciding where to interview, and 36% when deciding how to rank order programs for the Match. Forty

Toward a Resident Personal Finance Curriculum: Quantifying Resident Financial Circumstances, Needs, and Interests.

Science.gov (United States)

McKillip, Ryan; Ernst, Michael; Ahn, James; Tekian, Ara; Shappell, Eric

2018-04-26

Introduction Resident financial health has been linked to wellness and resiliency, yet financial literacy among residents is highly variable. While some medical school curricula include budgeting and student loan education, content on managing finances as a resident is usually lacking. We sought to quantitatively assess residents' financial circumstances, needs, and interests to inform the design of a resident personal finance curriculum. Methods Surveys were sent to residents in eight specialties at an academic medical center. Likert-type responses allowed respondents to rate their level of comfort (1 = Very Uncomfortable, 7 = Very Comfortable) and interest (1 = Very Uninterested, 7 = Very Interested) in various personal finance topics including budgeting, loan repayment, disability insurance, life insurance, home buying, and retirement planning. Details regarding financial circumstances, including assets, liabilities, and insurance, were also collected. Results of questions that utilized a Likert-type scale are reported as median (interquartile range). Results Of 346 residents surveyed, 144 (41.6%) responded. Residents were from Internal Medicine (56, 38.9%), Pediatrics (34, 23.6%), Emergency Medicine (18, 12.5%), and other specialties (36, 25.0%). Ninety-one (63.2%) reported educational loans, with an average balance of $191,730. Credit card balances exceeding $3,000 were reported by 11 (7.6%) respondents. One-hundred-two (70.1%) reported emergency savings, but only 65 (45.1%) reported having a retirement account (average balance $27,608). Respondents rated highest comfort levels with budgeting (5[4-6]), and lowest level of comfort with disability insurance (2[2-4]) and home buying (2[2-5]). Interest in learning each topic was high (6[5-7]), with retirement planning (6[5-7]), investing (6[5-7]), and home buying (6[5-7]) the topics of highest interest. Conclusion These results highlight the deficits in personal finance literacy among residents. Future work should

Space Use and Habitat Selection by Resident and Transient Red Wolves (Canis rufus.

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Joseph W Hinton

Full Text Available Recovery of large carnivores remains a challenge because complex spatial dynamics that facilitate population persistence are poorly understood. In particular, recovery of the critically endangered red wolf (Canis rufus has been challenging because of its vulnerability to extinction via human-caused mortality and hybridization with coyotes (Canis latrans. Therefore, understanding red wolf space use and habitat selection is important to assist recovery because key aspects of wolf ecology such as interspecific competition, foraging, and habitat selection are well-known to influence population dynamics and persistence. During 2009-2011, we used global positioning system (GPS radio-telemetry to quantify space use and 3rd-order habitat selection for resident and transient red wolves on the Albemarle Peninsula of eastern North Carolina. The Albemarle Peninsula was a predominantly agricultural landscape in which red wolves maintained spatially stable home ranges that varied between 25 km2 and 190 km2. Conversely, transient red wolves did not maintain home ranges and traversed areas between 122 km2 and 681 km2. Space use by transient red wolves was not spatially stable and exhibited shifting patterns until residency was achieved by individual wolves. Habitat selection was similar between resident and transient red wolves in which agricultural habitats were selected over forested habitats. However, transients showed stronger selection for edges and roads than resident red wolves. Behaviors of transient wolves are rarely reported in studies of space use and habitat selection because of technological limitations to observed extensive space use and because they do not contribute reproductively to populations. Transients in our study comprised displaced red wolves and younger dispersers that competed for limited space and mating opportunities. Therefore, our results suggest that transiency is likely an important life-history strategy for red wolves that

Space use and habitat selection by resident and transient red wolves (Canis rufus)

Science.gov (United States)

Hinton, Joseph W.; Proctor, Christine; Kelly, Marcella J.; van Manen, Frank T.; Vaughan, Michael R.; Chamberlain, Michael J.

2016-01-01

Recovery of large carnivores remains a challenge because complex spatial dynamics that facilitate population persistence are poorly understood. In particular, recovery of the critically endangered red wolf (Canis rufus) has been challenging because of its vulnerability to extinction via human-caused mortality and hybridization with coyotes (Canis latrans). Therefore, understanding red wolf space use and habitat selection is important to assist recovery because key aspects of wolf ecology such as interspecific competition, foraging, and habitat selection are well-known to influence population dynamics and persistence. During 2009–2011, we used global positioning system (GPS) radio-telemetry to quantify space use and 3rd-order habitat selection for resident and transient red wolves on the Albemarle Peninsula of eastern North Carolina. The Albemarle Peninsula was a predominantly agricultural landscape in which red wolves maintained spatially stable home ranges that varied between 25 km2 and 190 km2. Conversely, transient red wolves did not maintain home ranges and traversed areas between 122 km2 and 681 km2. Space use by transient red wolves was not spatially stable and exhibited shifting patterns until residency was achieved by individual wolves. Habitat selection was similar between resident and transient red wolves in which agricultural habitats were selected over forested habitats. However, transients showed stronger selection for edges and roads than resident red wolves. Behaviors of transient wolves are rarely reported in studies of space use and habitat selection because of technological limitations to observed extensive space use and because they do not contribute reproductively to populations. Transients in our study comprised displaced red wolves and younger dispersers that competed for limited space and mating opportunities. Therefore, our results suggest that transiency is likely an important life-history strategy for red wolves that facilitates

Perspectives of Residents of Mashhad School of Dentistry about the Curriculum of Residency Program

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Javad Sarabadani

2015-09-01

Full Text Available Introduction: This study was carried out to analyze the viewpoint of the residents of school of dentistry about the curriculum presented in the residency program to students of Mashhad School of Dentistry. Methods: To evaluate the perspectives of residents of dental school about the curriculum and regulations of residency program, a questionnaire was designed whose validity and reliability were confirmed by the authorities of School of Dentistry and test-retest reliability, respectively. The questionnaire was distributed among 100 residents and 80 of them completed the questionnaires. The data were analyzed by SPSS software (version 11.5. Results: A total of 43% of residents were informed of the curriculum (e.g. academic leave, transfer, removal of semester, etc.. As for the ability to write research proposal, 42.7% of residents were reported to have a favorable status, i.e. they were able to write more than 80% of their proposal. From among the residents, 30.4% had specialized English language certificate. Most of them (77% were satisfied with the professional staff, faculty members, of the faculty. Many students liked to participate in the teaching method courses of the residency program. Conclusion: Residents maintained that the curriculum in such domains as educational and research issues and special capabilities had some weak points. Thus, appropriate strategies are recommended to be applied to revise the curriculum using the residents’ views on these programs.

An estimate of spherical impactor energy transfer for mechanical frequency up-conversion energy harvester

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L. R. Corr

2016-08-01

Full Text Available Vibration energy harvesters, which use the impact mechanical frequency up-conversion technique, utilize an impactor, which gains kinetic energy from low frequency ambient environmental vibrations, to excite high frequency systems that efficiently convert mechanical energy to electrical energy. To take full advantage of the impact mechanical frequency up-conversion technique, it is prudent to understand the energy transfer from the low frequency excitations, to the impactor, and finally to the high frequency systems. In this work, the energy transfer from a spherical impactor to a multi degree of freedom spring / mass system, due to Hertzian impact, is investigated to gain insight on how best to design impact mechanical frequency up-conversion energy harvesters. Through this academic work, it is shown that the properties of the contact (or impact area, i.e., radius of curvature and material properties, only play a minor role in energy transfer and that the equivalent mass of the target system (i.e., the spring / mass system dictates the total amount of energy transferred during the impact. The novel approach of utilizing the well-known Hertzian impact methodology to gain an understanding of impact mechanical frequency up-conversion energy harvesters has made it clear that the impactor and the high frequency energy generating systems must be designed together as one system to ensure maximum energy transfer, leading to efficient ambient vibration energy harvesters.

Pyrolysis characteristics and kinetics of aquatic biomass using thermogravimetric analyzer.

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Wu, Kejing; Liu, Ji; Wu, Yulong; Chen, Yu; Li, Qinghai; Xiao, Xin; Yang, Mingde

2014-07-01

The differences in pyrolysis process of three species of aquatic biomass (microalgae, macroalgae and duckweed) were investigated by thermogravimetric analysis (TGA). Three stages were observed during the pyrolysis process and the main decomposition stage could be divided further into three zones. The pyrolysis characteristics of various biomasses were different at each zone, which could be attributed to the differences in their components. A stepwise procedure based on iso-conversional and master-plots methods was used for the kinetic and mechanism analysis of the main decomposition stage. The calculation results based on the kinetic model was in good agreement with the experimental data of weight loss, and each biomass had an increasing activation energy of 118.35-156.13 kJ/mol, 171.85-186.46 kJ/mol and 258.51-268.71 kJ/mol in zone 1, 2 and 3, respectively. This study compares the pyrolysis behavior of various aquatic biomasses and provides basis for further applications of the biomass thermochemical conversion. Copyright © 2014. Published by Elsevier Ltd.

Cesium removal and kinetics equilibrium: Precipitation kinetics

International Nuclear Information System (INIS)

Barnes, M.J.

1999-01-01

This task consisted of both non-radioactive and radioactive (tracer) tests examining the influence of potentially significant variables on cesium tetraphenylborate precipitation kinetics. The work investigated the time required to reach cesium decontamination and the conditions that affect the cesium precipitation kinetics

Facebook Use between College Resident Advisors' and Their Residents: A Mixed Methods Approach.

Science.gov (United States)

Kacvinsky, Lauren E; Moreno, Megan A

2014-01-01

Facebook use is nearly ubiquitous among college students. Studies have shown links between Facebook displays of depression or problem drinking and risk of these problems. This project aimed to determine whether Facebook could be used to help Resident Advisors (RAs) identify college students at risk for depression or problem drinking. Interviews were conducted with college freshmen to investigate whether they were Facebook "friends" with their RA. Focus groups were conducted with RAs to determine their views on Facebook friending their dormitory residents and using Facebook to help identify at-risk students. 72 freshmen were interviewed and 25 RAs participated in focus groups; both agreed it is common for RAs and residents to be Facebook friends. RAs commonly noted references to depression and problem drinking on residents' Facebook pages, which often led to in-person discussions with the resident. This study provides support that RAs use Facebook to identify issues that may impact their student residents. RAs emphasized benefits of in-person interactions in order to provide support and obtain additional details about the situation. Universities could consider whether providing RA education about Facebook interactions with residents merits encouragement within their existing RA training programs.

Catalytic Process for the Conversion of Coal-derived Syngas to Ethanol

Energy Technology Data Exchange (ETDEWEB)

James Spivery; Doug Harrison; John Earle; James Goodwin; David Bruce; Xunhau Mo; Walter Torres; Joe Allison Vis Viswanathan; Rick Sadok; Steve Overbury; Viviana Schwartz

2011-07-29

The catalytic conversion of coal-derived syngas to C{sub 2+} alcohols and oxygenates has attracted great attention due to their potential as chemical intermediates and fuel components. This is particularly true of ethanol, which can serve as a transportation fuel blending agent, as well as a hydrogen carrier. A thermodynamic analysis of CO hydrogenation to ethanol that does not allow for byproducts such as methane or methanol shows that the reaction: 2 CO + 4 H{sub 2} {yields} C{sub 2}H{sub 5}OH + H{sub 2}O is thermodynamically favorable at conditions of practical interest (e.g,30 bar, {approx}< 250 C). However, when methane is included in the equilibrium analysis, no ethanol is formed at any conditions even approximating those that would be industrially practical. This means that undesired products (primarily methane and/or CO{sub 2}) must be kinetically limited. This is the job of a catalyst. The mechanism of CO hydrogenation leading to ethanol is complex. The key step is the formation of the initial C-C bond. Catalysts that are selective for EtOH can be divided into four classes: (a) Rh-based catalysts, (b) promoted Cu catalysts, (c) modified Fischer-Tropsch catalysts, or (d) Mo-sulfides and phosphides. This project focuses on Rh- and Cu-based catalysts. The logic was that (a) Rh-based catalysts are clearly the most selective for EtOH (but these catalysts can be costly), and (b) Cu-based catalysts appear to be the most selective of the non-Rh catalysts (and are less costly). In addition, Pd-based catalysts were studied since Pd is known for catalyzing CO hydrogenation to produce methanol, similar to copper. Approach. The overall approach of this project was based on (a) computational catalysis to identify optimum surfaces for the selective conversion of syngas to ethanol; (b) synthesis of surfaces approaching these ideal atomic structures, (c) specialized characterization to determine the extent to which the actual catalyst has these structures, and (d) testing

Residents as teachers: psychiatry and family medicine residents' self-assessment of teaching knowledge, skills, and attitudes.

Science.gov (United States)

Brand, Michael W; Ekambaram, Vijayabharathi; Tucker, Phebe; Aggarwal, Ruchi

2013-09-01

Residents are one of the prime sources of information and education for medical students. As an initial step in supporting residents as teachers, a baseline self-assessment of residents' knowledge, skills, attitudes, and values related to teaching was conducted among psychiatry and family medicine residents to compare and improve their confidence and skills as teachers. Psychiatry residents (N=12) and family medicine residents (N=23) completed self-assessments of their knowledge, skills, attitudes, and values related to teaching. Residents also were asked to list steps used in the One-Minute Preceptor process and estimate the time each spent in teaching. Descriptive summary statistics were used for four main areas related to teaching; t-test and chi-square analyses were conducted to ascertain whether there was a significant difference in resident groups. In the current study, the perceived amount of time spent for teaching patients was significantly higher among family practice residents, whereas no group differences were found for time teaching medical students, peers, community members, non-physicians, or others. However, family medicine residents rated themselves higher than psychiatry residents in their understanding of their roles in teaching medical students and teaching patients. Also, family medicine residents' self-reported teaching skills were more advanced (82.4%) than psychiatry residents' (54.2%). They most likely applied at least two different teaching methods in inpatient and outpatient settings, as compared with psychiatry residents. No significant group differences were found in the other 15 items assessing teaching knowledge, skills, attitudes, and values. Results indicate that residents' knowledge, skills, attitudes, and values regarding teaching varies across institutions and training programs. The psychiatry residents in this study do not clearly understand their role as educators with patients and medical students; they have a less clear

Thermogravimetric analysis and kinetic study of bamboo waste treated by Echinodontium taxodii using a modified three-parallel-reactions model.

Science.gov (United States)

Yu, Hongbo; Liu, Fang; Ke, Ming; Zhang, Xiaoyu

2015-06-01

In this study, the effect of pretreatment with Echinodontium taxodii on thermal decomposition characteristics and kinetics of bamboo wastes was investigated by thermogravimetric analysis. The results showed fungal pretreatment can enhance the thermal degradation of bamboo. The negative effect of extractives in bamboo on the thermal decomposition can be decreased by the pretreatment. A modified three-parallel-reactions model based on isolated lignin was firstly proposed to study pyrolysis kinetics of bamboo lignocellulose. Kinetic analysis showed that with increasing pretreatment time fungal delignification was enhanced to transform the lignin component with high activation energy into that with low activation energy and raise the cellulose content in bamboo, making the thermal decomposition easier. These results demonstrated fungal pretreatment provided a potential way to improve thermal conversion efficiency of bamboo. Copyright © 2015 Elsevier Ltd. All rights reserved.

Process Simulation for the Design and Scale Up of Heterogeneous Catalytic Process: Kinetic Modelling Issues

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Antonio Tripodi

2017-05-01

Full Text Available Process simulation represents an important tool for plant design and optimization, either applied to well established or to newly developed processes. Suitable thermodynamic packages should be selected in order to properly describe the behavior of reactors and unit operations and to precisely define phase equilibria. Moreover, a detailed and representative kinetic scheme should be available to predict correctly the dependence of the process on its main variables. This review points out some models and methods for kinetic analysis specifically applied to the simulation of catalytic processes, as a basis for process design and optimization. Attention is paid also to microkinetic modelling and to the methods based on first principles, to elucidate mechanisms and independently calculate thermodynamic and kinetic parameters. Different case studies support the discussion. At first, we have selected two basic examples from the industrial chemistry practice, e.g., ammonia and methanol synthesis, which may be described through a relatively simple reaction pathway and the relative available kinetic scheme. Then, a more complex reaction network is deeply discussed to define the conversion of bioethanol into syngas/hydrogen or into building blocks, such as ethylene. In this case, lumped kinetic schemes completely fail the description of process behavior. Thus, in this case, more detailed—e.g., microkinetic—schemes should be available to implement into the simulator. However, the correct definition of all the kinetic data when complex microkinetic mechanisms are used, often leads to unreliable, highly correlated parameters. In such cases, greater effort to independently estimate some relevant kinetic/thermodynamic data through Density Functional Theory (DFT/ab initio methods may be helpful to improve process description.

Leadership Training in Otolaryngology Residency.

Science.gov (United States)

Bent, John P; Fried, Marvin P; Smith, Richard V; Hsueh, Wayne; Choi, Karen

2017-06-01

Although residency training offers numerous leadership opportunities, most residents are not exposed to scripted leadership instruction. To explore one program's attitudes about leadership training, a group of otolaryngology faculty (n = 14) and residents (n = 17) was polled about their attitudes. In terms of self-perception, more faculty (10 of 14, 71.4%) than residents (9 of 17, 52.9%; P = .461) considered themselves good leaders. The majority of faculty and residents (27 of 31) thought that adults could be taught leadership ability. Given attitudes about leadership ability and the potential for improvement through instruction, consideration should be given to including such training in otolaryngology residency.

Effects of a Short Video-Based Resident-as-Teacher Training Toolkit on Resident Teaching.

Science.gov (United States)

Ricciotti, Hope A; Freret, Taylor S; Aluko, Ashley; McKeon, Bri Anne; Haviland, Miriam J; Newman, Lori R

2017-10-01

To pilot a short video-based resident-as-teacher training toolkit and assess its effect on resident teaching skills in clinical settings. A video-based resident-as-teacher training toolkit was previously developed by educational experts at Beth Israel Deaconess Medical Center, Harvard Medical School. Residents were recruited from two academic hospitals, watched two videos from the toolkit ("Clinical Teaching Skills" and "Effective Clinical Supervision"), and completed an accompanying self-study guide. A novel assessment instrument for evaluating the effect of the toolkit on teaching was created through a modified Delphi process. Before and after the intervention, residents were observed leading a clinical teaching encounter and scored using the 15-item assessment instrument. The primary outcome of interest was the change in number of skills exhibited, which was assessed using the Wilcoxon signed-rank test. Twenty-eight residents from two academic hospitals were enrolled, and 20 (71%) completed all phases of the study. More than one third of residents who volunteered to participate reported no prior formal teacher training. After completing two training modules, residents demonstrated a significant increase in the median number of teaching skills exhibited in a clinical teaching encounter, from 7.5 (interquartile range 6.5-9.5) to 10.0 (interquartile range 9.0-11.5; P<.001). Of the 15 teaching skills assessed, there were significant improvements in asking for the learner's perspective (P=.01), providing feedback (P=.005), and encouraging questions (P=.046). Using a resident-as-teacher video-based toolkit was associated with improvements in teaching skills in residents from multiple specialties.

Supported black phosphorus nanosheets as hydrogen-evolving photocatalyst achieving 5.4% energy conversion efficiency at 353 K.

Science.gov (United States)

Tian, Bin; Tian, Bining; Smith, Bethany; Scott, M C; Hua, Ruinian; Lei, Qin; Tian, Yue

2018-04-11

Solar-driven water splitting using powdered catalysts is considered as the most economical means for hydrogen generation. However, four-electron-driven oxidation half-reaction showing slow kinetics, accompanying with insufficient light absorption and rapid carrier combination in photocatalysts leads to low solar-to-hydrogen energy conversion efficiency. Here, we report amorphous cobalt phosphide (Co-P)-supported black phosphorus nanosheets employed as photocatalysts can simultaneously address these issues. The nanosheets exhibit robust hydrogen evolution from pure water (pH = 6.8) without bias and hole scavengers, achieving an apparent quantum efficiency of 42.55% at 430 nm and energy conversion efficiency of over 5.4% at 353 K. This photocatalytic activity is attributed to extremely efficient utilization of solar energy (~75% of solar energy) by black phosphorus nanosheets and high-carrier separation efficiency by amorphous Co-P. The hybrid material design realizes efficient solar-to-chemical energy conversion in suspension, demonstrating the potential of black phosphorus-based materials as catalysts for solar hydrogen production.

Acetalised Galactarate Polyesters: Interplay between Chemical Structure and Polymerisation Kinetics

Directory of Open Access Journals (Sweden)

Ionela Gavrila

2018-02-01

Full Text Available In spite of the progress that has made so far in the recent years regarding the synthesis of bio-based polymers and in particular polyesters, only few references address the optimisation of these new reactions with respect to conversion and reaction time. Related to this aspect, we here describe the transesterification reaction of two different acetalised galactarate esters with a model aliphatic diol, 1,6-hexanediol. The kinetics of these two apparently similar reactions is compared, with a focus on the conversion while varying the concentration of a di-butyltin oxide catalyst (DBTO, respectively, the used N2 flow-rate. During the first stage of polymerisation, the molecular weight of the end-products is more than doubled when using a 250 mL/min flow as opposed to an almost static N2 pressure. Additionally, the resulted pre-polymers are subjected to further polycondensation and the comparison between the obtained polyesters is extended to their thermal, mechanical and dielectrical characterisation. The influence of the acetal groups on the stability of the polyesters in acidic conditions concludes the study.

Thermogravimetric study on pyrolysis kinetics of Chlorella pyrenoidosa and bloom-forming cyanobacteria.

Science.gov (United States)

Hu, Mian; Chen, Zhihua; Guo, Dabin; Liu, Cuixia; Xiao, Bo; Hu, Zhiquan; Liu, Shiming

2015-02-01

The pyrolysis process of two microalgae, Chlorella pyrenoidosa (CP) and bloom-forming cyanobacteria (CB) was examined by thermo-gravimetry to investigate their thermal decomposition behavior under non-isothermal conditions. It has found that the pyrolysis of both microalgae consists of three stages and stage II is the major mass reduction stage with mass loss of 70.69% for CP and 64.43% for CB, respectively. The pyrolysis kinetics of both microalgae was further studied using single-step global model (SSGM) and distributed activation energy model (DAEM). The mean apparent activation energy of CP and CB in SSGM was calculated as 143.71 and 173.46 kJ/mol, respectively. However, SSGM was not suitable for modeling pyrolysis kinetic of both microalgae due to the mechanism change during conversion. The DAEM with 200 first-order reactions showed an excellent fit between simulated data and experimental results. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhancing teamwork between chief residents and residency program directors: description and outcomes of an experiential workshop.

Science.gov (United States)

McPhillips, Heather A; Frohna, John G; Murad, M Hassan; Batra, Maneesh; Panda, Mukta; Miller, Marsha A; Brigham, Timothy P; Doughty, Robert A

2011-12-01

An effective working relationship between chief residents and residency program directors is critical to a residency program's success. Despite the importance of this relationship, few studies have explored the characteristics of an effective program director-chief resident partnership or how to facilitate collaboration between the 2 roles, which collectively are important to program quality and resident satisfaction. We describe the development and impact of a novel workshop that paired program directors with their incoming chief residents to facilitate improved partnerships. The Accreditation Council for Graduate Medical Education sponsored a full-day workshop for residency program directors and their incoming chief residents. Sessions focused on increased understanding of personality styles, using experiential learning, and open communication between chief residents and program directors, related to feedback and expectations of each other. Participants completed an anonymous survey immediately after the workshop and again 8 months later to assess its long-term impact. Participants found the workshop to be a valuable experience, with comments revealing common themes. Program directors and chief residents expect each other to act as a role model for the residents, be approachable and available, and to be transparent and fair in their decision-making processes; both groups wanted feedback on performance and clear expectations from each other for roles and responsibilities; and both groups identified the need to be innovative and supportive of changes in the program. Respondents to the follow-up survey reported that workshop participation improved their relationships with their co-chiefs and program directors. Participation in this experiential workshop improved the working relationships between chief residents and program directors. The themes that were identified can be used to foster communication between incoming chief residents and residency directors and to

Protected Time for Research During Orthopaedic Residency Correlates with an Increased Number of Resident Publications.

Science.gov (United States)

Williams, Benjamin R; Agel, Julie A; Van Heest, Ann E

2017-07-05

The Accreditation Council for Graduate Medical Education (ACGME) requires orthopaedic residency programs to promote scholarship and research, which manifest differently among programs. We assess the impact of protected research time during orthopaedic residency on the number of resident publications. Rotation schedules and resident names were collected from 125 ACGME-accredited U.S. orthopaedic residency programs. Protected research time was classified as 1 of 3 types: (1) block time, (2) longitudinal time, or (3) no dedicated time. In April 2016, we searched residents in postgraduate year (PGY)-3 to PGY-5 on pubmed.gov to generate all orthopaedic publications with a PubMed identifier published during residency. Each publication's 2015 Thomson Reuters Journal Citation Reports 5-Year Journal Impact Factor and resident first authorship were noted. The number of PubMed identifiers for each program was summed and was divided by the number of residents in PGY-3 to PGY-5, giving a mean number of publications per resident. The relationship between output and program research time was compared using t tests and analysis of variance (ANOVA). A total of 1,690 residents were included, with an overall mean number (and standard deviation) of 1.2 ± 2.4 publications per resident. Eighty-seven programs reported block time, 14 programs reported longitudinal time, and 24 programs reported no time. There was a significant difference (p = 0.02) in the mean number of publications per resident when compared between programs with protected time (1.1 ± 1.2 publications) and programs with no protected time (0.6 ± 0.5 publication). One-way ANOVA demonstrated a significant mean difference across the 3 groups (p publications than block time at 1.0 ± 1.0 publication or no time at 0.6 ± 0.5 publication, a difference that persisted when adjusted to include only impact factors of >0 and exclude case reports (p = 0.0015). Both the presence of and the type of dedicated research time correlate

Psychiatry residents in a milieu participatory democracy: a resident's view.

Science.gov (United States)

Gersten, D

1978-11-01

Psychiatry residents respond with a variety of coping mechanisms to the lack of traditional structure in a milieu participatory democracy. To incorporate themselves into the system they must accept such democratic ideals as equality among staff and patients, group decision making, and free self-expression and give up some of their traditional ideas about staff and patient roles, treatment modalities, and the therapeutic environment. The author was a first-year resident in psychiatry on a university hospital inpatient therapeutic community; he discusses the conflicts between residents, who often adopt a "we-they" attitude, and the permanent staff, whose protectiveness of the ward community reflects their personal commitment to its ideals.

Blended Learning in Obstetrics and Gynecology Resident Education: Impact on Resident Clinical Performance.

Science.gov (United States)

Ghareeb, Allen; Han, Heeyoung; Delfino, Kristin; Taylor, Funminiyi

2016-01-01

Effects of residents' blended learning on their clinical performance have rarely been reported. A blended learning pilot program was instituted at Southern Illinois University School of Medicine's Obstetrics and Gynecology program. One of the modules was chronic hypertension in pregnancy. We sought to evaluate if the resident blended learning was transferred to their clinical performance six months after the module. A review of patient charts demonstrated inadequate documentation of history, evaluation, and counseling of patients with chronic hypertension at the first prenatal visit by Obstetrics and Gynecology (OB/GYN) residents. A blended learning module on chronic hypertension in pregnancy was then provided to the residents. A retrospective chart review was then performed to assess behavioral changes in the OB/GYN residents. This intervention was carried out at the Department of Obstetrics and Gynecology, Southern Illinois University. All 16 OB/GYN residents were enrolled in this module as part of their educational curriculum. A query of all prenatal patients diagnosed with chronic hypertension presenting to the OB/GYN resident clinics four months prior to the implementation of the blended learning module (March 2015-June 2015) and six months after (July 20, 2015-February 2016) was performed. Data were collected from outpatient charts utilizing the electronic medical record. Data were abstracted from resident documentation at the first prenatal visit. The residents thought that the blended learning module was applicable to performance improvement in the real-world setting. Patients evaluated before ( n = 10) and after ( n = 7) the intervention were compared. After the intervention, there was an increase in assessment of baseline liver enzymes, referral for electrocardiogram, and early assessment for diabetes in the obese patients. More patients were provided a blood pressure cuff after the module (71.4% vs. 20%). Data were provided to the residents in an

Uranium conversion; Urankonvertering

Energy Technology Data Exchange (ETDEWEB)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina [Swedish Defence Research Agency (FOI), Stockholm (Sweden)

2006-03-15

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF{sub 6} and UF{sub 4} are present require equipment that is made of corrosion resistant material.

Kinetics of cellobiose hydrolysis using cellobiase composites from Trichoderma reesei and Aspergillus niger

Energy Technology Data Exchange (ETDEWEB)

Grous, W.; Converse, A.; Grethlein, H.; Lynd, L.

1985-01-01

The enzymatic hydrolysis of cellulose to glucose involves the formation of cellobiose as an intermediate. It has been found necessary to add cellobiase from Aspergillus niger (NOVO) to the cellobiase component of Trichoderma reesei mutant Rut C-30 (Natick) cellulase enzymes in order to obtain after 48 h complete conversion of the cellobiose formed in the enzymatic hydrolysis of biomass. This study of the cellobiase activity of these two enzyme sources was undertaken as a first step in the formation of a kinetic model for cellulose hydrolysis that can be used in process design. In order to cover the full range of cellobiose concentrations, it was necessary to develop separate kinetic parameters for high- and low-concentration ranges of cellobiose for the enzymes from each organism. Competitive glucose inhibition was observed with the enzymes from both organisms. Substrate inhibition was observed only with the A. niger enzymes.

Depression is associated with poor functioning in activities of daily living among nursing home residents without cognitive impairment.

Science.gov (United States)

Drageset, Jorunn; Eide, Geir E; Ranhoff, Anette H

2011-11-01

To explore depressive symptoms among nursing home residents without cognitive impairment and the relationship between their depressive symptoms and dependence on activities of daily living, comorbidity and sociodemographic variables. Depression has become a major health care concern among older people, but depression and its association with functioning in activities of daily living among nursing home residents without cognitive impairment has previously not been studied in Norway. A cross-sectional comparative design. The sample comprised older residents (age 65-102 years; n = 227) from 30 nursing homes with at least six months of residence. All nursing home residents had a Clinical Dementia Rating scale score ≤0·5 and were capable of conversation. Scores on the Geriatric Depression Scale (15 items) and demographic variables were collected during face-to-face interviews. The activities of daily living were assessed using the Katz Index based on nurses' observation, and medical diagnoses were obtained from the patient records. Pearson's chi-square test and ordinal logistic regression were used to identify possible associations between activities of daily living and depression. After adjustment for age, sex, marital status, length of stay per year and education, more dependence on activities of daily living was associated with depression [odds ratio (OR): 1·18; 95% confidence interval (CI): 1·04-1·37; p = 0·02]. Higher age was associated with less depression (OR: 0·64; 95% CI: 0·43-0·94; p = 0·02), that is, the odds of depression declined by 36% for each 10-year increase in age. Our results suggest that depression symptoms are a major health problem among nursing home residents without cognitive impairment and that younger residents are more prone to having depressive symptoms. Nursing home staff should communicate with and observe residents closely for signs of depression, especially younger residents with high dependence on activities of daily living

Heparin kinetics

International Nuclear Information System (INIS)

Swart, C.A.M. de.

1983-01-01

The author has studied the kinetics of heparin and heparin fractions after intravenous administration in humans and in this thesis the results of this study are reported. Basic knowledge about the physico-chemical properties of heparin and its interactions with proteins resulting in anticoagulant and lipolytic effects are discussed in a review (chapter II), which also comprises some clinical aspects of heparin therapy. In chapter III the kinetics of the anticoagulant effect are described after intravenous administration of five commercial heparin preparations. A mathematical model is presented that fits best to these kinetics. The kinetics of the anticoagulant and lipolytic effects after intravenous injection of various 35 S-radiolabelled heparin fractions and their relationship with the disappearance of the radiolabel are described in chapter IV. Chapter V gives a description of the kinetics of two radiolabels after injection of in vitro formed complexes consisting of purified, 125 I-radiolabelled antithrombin III and various 35 S-radiolabelled heparin fractions. (Auth.)

Education Research: Neurology resident education

Science.gov (United States)

Mayans, David; Schneider, Logan; Adams, Nellie; Khawaja, Ayaz M.; Engstrom, John

2016-01-01

Objective: To survey US-trained graduating neurology residents who are American Academy of Neurology members, in an effort to trend perceived quality and completeness of graduate neurology education. Methods: An electronic survey was sent to all American Academy of Neurology members graduating from US neurology residency programs in the Spring of 2014. Results: Of 805 eligible respondents, 24% completed the survey. Ninety-three percent of adult neurology residents and 56% of child neurology residents reported plans to pursue fellowship training after residency. Respondents reported a desire for additional training in neurocritical care, neuro-oncology, neuromuscular diseases, botulinum toxin injection, and nerve blocks. There remains a clear deficit in business training of neurology residents, although there was notable improvement in knowledge of coding and office management compared to previous surveys. Discussion: Although there are still areas of perceived weakness in neurology training, graduating neurology residents feel generally well prepared for their chosen careers. However, most still pursue fellowship training for reasons that are little understood. In addition to certain subspecialties and procedures, practice management remains deficient in neurology training and is a point of future insecurity for most residents. Future curriculum changes should consider resident-reported gaps in knowledge, with careful consideration of improving business training. PMID:26976522

Fly Ash Formation during Suspension-Firing of Biomass. Effects of Residence Time and Fuel-Type

DEFF Research Database (Denmark)

Damø, Anne Juul; Jensen, Peter Arendt; Jappe Frandsen, Flemming

2017-01-01

particles were subjected to various analyses, including char burnout level, particle size distribution, elemental composition, and particle morphology and composition. Furthermore, the transient release, i.e. the vaporization of the flame-volatile inorganic elements K, Cl and S, from the burning fuel...... particles to the gas phase, has been quantified by using two different calculation methods. The ash formation mechanisms were found to be quite similar for straw and wood. The degree of conversion (char burn-out level) was generally good at residence times ≥ 1s. The size distribution of the residual fly ash...

Simultaneous measurement of polymerization stress and curing kinetics for photo-polymerized composites with high filler contents.

Science.gov (United States)

Wang, Zhengzhi; Landis, Forrest A; Giuseppetti, Anthony A M; Lin-Gibson, Sheng; Chiang, Martin Y M

2014-12-01

Photopolymerized composites are used in a broad range of applications with their performance largely directed by reaction kinetics and contraction accompanying polymerization. The present study was to demonstrate an instrument capable of simultaneously collecting multiple kinetics parameters for a wide range of photopolymerizable systems: degree of conversion (DC), reaction exotherm, and polymerization stress (PS). Our system consisted of a cantilever beam-based instrument (tensometer) that has been optimized to capture a large range of stress generated by lightly-filled to highly-filled composites. The sample configuration allows the tensometer to be coupled to a fast near infrared (NIR) spectrometer collecting spectra in transmission mode. Using our instrument design, simultaneous measurements of PS and DC are performed, for the first time, on a commercial composite with ≈80% (by mass) silica particle fillers. The in situ NIR spectrometer collects more than 10 spectra per second, allowing for thorough characterization of reaction kinetics. With increased instrument sensitivity coupled with the ability to collect real time reaction kinetics information, we show that the external constraint imposed by the cantilever beam during polymerization could affect the rate of cure and final degree of polymerization. The present simultaneous measurement technique is expected to provide new insights into kinetics and property relationships for photopolymerized composites with high filler content such as dental restorative composites. Published by Elsevier Ltd.

Preconceptual design studies and cost data of depleted uranium hexafluoride conversion plants

International Nuclear Information System (INIS)

Jones, E

1999-01-01

One of the more important legacies left with the Department of Energy (DOE) after the privatization of the United States Enrichment Corporation is the large inventory of depleted uranium hexafluoride (DUF6). The DOE Office of Nuclear Energy, Science and Technology (NE) is responsible for the long-term management of some 700,000 metric tons of DUF6 stored at the sites of the two gaseous diffusion plants located at Paducah, Kentucky and Portsmouth, Ohio, and at the East Tennessee Technology Park in Oak Ridge, Tennessee. The DUF6 management program resides in NE's Office of Depleted Uranium Hexafluoride Management. The current DUF6 program has largely focused on the ongoing maintenance of the cylinders containing DUF6. However, the long-term management and eventual disposition of DUF6 is the subject of a Programmatic Environmental Impact Statement (PEIS) and Public Law 105-204. The first step for future use or disposition is to convert the material, which requires construction and long-term operation of one or more conversion plants. To help inform the DUF6 program's planning activities, it was necessary to perform design and cost studies of likely DUF6 conversion plants at the preconceptual level, beyond the PEIS considerations but not as detailed as required for conceptual designs of actual plants. This report contains the final results from such a preconceptual design study project. In this fast track, three month effort, Lawrence Livermore National Laboratory and Bechtel National Incorporated developed and evaluated seven different preconceptual design cases for a single plant. The preconceptual design, schedules, costs, and issues associated with specific DUF6 conversion approaches, operating periods, and ownership options were evaluated based on criteria established by DOE. The single-plant conversion options studied were similar to the dry-conversion process alternatives from the PEIS. For each of the seven cases considered, this report contains information on

Conversion electron Moessbauer spectroscopy of plasma immersion ion implanted H13 tool steel

International Nuclear Information System (INIS)

Terwagne, G.; Hutchings, R.

1994-01-01

Conversion electron Moessbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI 3 ) at 350 C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ε-Fe 2 N through ε-Fe 3 N to γ'-Fe 4 N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone. (orig.)

Kinetics of the decomposition reaction of phosphorite concentrate

Directory of Open Access Journals (Sweden)

Huang Run

2014-01-01

Full Text Available Apatite is the raw material, which is mainly used in phosphate fertilizer, and part are used in yellow phosphorus, red phosphorus, and phosphoric acid in the industry. With the decrease of the high grade phosphorite lump, the agglomeration process is necessary for the phosphorite concentrate after beneficiation process. The decomposition behavior and the phase transformation are of vital importance for the agglomeration process of phosphorite. In this study, the thermal kinetic analysis method was used to study the kinetics of the decomposition of phosphorite concentrate. The phosphorite concentrate was heated under various heating rate, and the phases in the sample heated were examined by the X-ray diffraction method. It was found that the main phases in the phosphorite are fluorapatiteCa5(PO43F, quartz SiO2,and dolomite CaMg(CO32.The endothermic DSC peak corresponding to the mass loss caused by the decomposition of dolomite covers from 600°C to 850°C. The activation energy of the decomposition of dolomite, which increases with the increase in the extent of conversion, is about 71.6~123.6kJ/mol. The mechanism equation for the decomposition of dolomite agrees with the Valensi equation and G-B equation.

Orthopedic resident work-shift analysis: are we making the best use of resident work hours?

Science.gov (United States)

Hamid, Kamran S; Nwachukwu, Benedict U; Hsu, Eugene; Edgerton, Colston A; Hobson, David R; Lang, Jason E

2014-01-01

Surgery programs have been tasked to meet rising demands in patient surgical care while simultaneously providing adequate resident training in the midst of increasing resident work-hour restrictions. The purpose of this study was to quantify orthopedic surgery resident workflow and identify areas needing improved resident efficiency. We hypothesize that residents spend a disproportionate amount of time involved in activities that do not relate directly to patient care or maximize resident education. We observed 4 orthopedic surgery residents on the orthopedic consult service at a major tertiary care center for 72 consecutive hours (6 consecutive shifts). We collected minute-by-minute data using predefined work-task criteria: direct new patient contact, direct existing patient contact, communications with other providers, documentation/administrative time, transit time, and basic human needs. A seventh category comprised remaining less-productive work was termed as standby. In a 720-minute shift, residents spent on an average: 191 minutes (26.5%) performing documentation/administrative duties, 167.0 minutes (23.2%) in direct contact with new patient consults, 129.6 minutes (17.1%) in communication with other providers regarding patients, 116.2 (16.1%) minutes in standby, 63.7 minutes (8.8%) in transit, 32.6 minutes (4.5%) with existing patients, and 20 minutes (2.7%) attending to basic human needs. Residents performed an additional 130 minutes of administrative work off duty. Secondary analysis revealed residents were more likely to perform administrative work rather than directly interact with existing patients (p = 0.006) or attend to basic human needs (p = 0.003). Orthopedic surgery residents spend a large proportion of their time performing documentation/administrative-type work and their workday can be operationally optimized to minimize nonvalue-adding tasks. Formal workflow analysis may aid program directors in systematic process improvements to better align

Characterization of ligand binding to melanocortin 4 receptors using fluorescent peptides with improved kinetic properties.

Science.gov (United States)

Link, Reet; Veiksina, Santa; Rinken, Ago; Kopanchuk, Sergei

2017-03-15

Melanocortin 4 (MC 4 ) receptors are important drug targets as they regulate energy homeostasis, eating behaviour and sexual functions. The ligand binding process to these G protein-coupled receptors is subject to considerable complexity. Different steps in the complex dynamic regulation can be characterized by ligand binding kinetics. Optimization of these kinetic parameters in terms of on-rate and residence time can increase the rapid onset of drug action and reduce off-target effects. Fluorescence anisotropy (FA) is one of the homogeneous fluorescence-based assays that enable continuous online monitoring of ligand binding kinetics. FA has been implemented for the kinetic study of melanocortin MC 4 receptors expressed on budded baculoviruses. However, the slow dissociation of the fluorescently labelled peptide NDP-α-MSH does not enable reaching equilibrium nor enable more in-depth study of the binding mechanisms. To overcome this problem, two novel red-shifted fluorescent ligands were designed. These cyclized heptapeptide derivatives (UTBC101 and UTBC102) exhibited nanomolar affinity toward melanocortin MC 4 receptors but had relatively different kinetic properties. The dissociation half-lives of UTBC101 (τ 1/2 =160min) and UTBC102 (τ 1/2 =7min) were shorter compared to that what was previously reported for Cy3B-NDP-α-MSH (τ 1/2 =224min). The significantly shorter dissociation half-life of UTBC102 enables equilibrium in screening assays, whereas the higher affinity of UTBC101 helps to resolve a wider range of competitor potencies. These two ligands are suitable for further kinetic screening of novel melanocortin MC 4 receptor specific ligands and could complement each other in these studies. Copyright © 2017 Elsevier B.V. All rights reserved.

In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions.

Science.gov (United States)

L Moore, Radhika; Mann, Jason P; Montoya, Alejandro; Haynes, Brian S

2018-04-25

The phase transition by thermal activation of natural α-spodumene was followed by in situ synchrotron XRD in the temperature range 896 to 940 °C. We observed both β- and γ-spodumene as primary products in approximately equal proportions. The rate of the α-spodumene inversion is first order and highly sensitive to temperature (apparent activation energy ∼800 kJ mol-1). The γ-spodumene product is itself metastable, forming β-spodumene, with the total product mass fraction ratio fγ/fβ decreasing as the conversion of α-spodumene continues. We found the relationship between the product yields and the degree of conversion of α-spodumene to be the same at all temperatures in the range studied. A model incorporating first order kinetics of the α- and γ-phase inversions with invariant rate constant ratio describes the results accurately. Theoretical phonon analysis of the three phases indicates that the γ phase contains crystallographic instabilities, whilst the α and β phases do not.

MECHANISTIC KINETIC MODELS FOR STEAM REFORMING OF CONCENTRATED CRUDE ETHANOL ON NI/AL2O3 CATALYST

Directory of Open Access Journals (Sweden)

O. A. OLAFADEHAN

2015-05-01

Full Text Available Mechanistic kinetic models were postulated for the catalytic steam reforming of concentrated crude ethanol on a Ni-based commercial catalyst at atmosphere pressure in the temperature range of 673-863 K, and at different catalyst weight to the crude ethanol molar flow rate ratio (in the range 0.9645-9.6451 kg catalyst h/kg mole crude ethanol in a stainless steel packed bed tubular microreactor. The models were based on Langmuir-Hinshelwood-Hougen-Watson (LHHW and Eley-Rideal (ER mechanisms. The optimization routine of Nelder-Mead simplex algorithm was used to estimate the inherent kinetic parameters in the proposed models. The selection of the best kinetic model amongst the rival kinetic models was based on physicochemical, statistical and thermodynamic scrutinies. The rate determining step for the steam reforming of concentrated crude ethanol on Ni/Al2O3 catalyst was found to be surface reaction between chemisorbed CH3O and O when hydrogen and oxygen were adsorbed as monomolecular species on the catalyst surface. Excellent agreement was obtained between the experimental rate of reaction and conversion of crude ethanol, and the simulated results, with ADD% being ±0.46.

Potential Impacts of Hydrokinetic and Wave Energy Conversion Technologies on Aquatic Environments

Energy Technology Data Exchange (ETDEWEB)

Čada, Glenn F.

2007-04-01

A new generation of hydropower technologies, the kinetic hydro and wave energy conversion devices, offers the possibility of generating electricity from the movements of water, without the need for dams and diversions. The Energy Policy Act of 2005 encouraged the development of these sources of renewable energy in the United States, and there is growing interest in deploying them globally. The technologies that would extract electricity from free-flowing streams, estuaries, and oceans have not been widely tested. Consequently, the U.S. Department of Energy convened a workshop to (1) identify the varieties of hydrokinetic energy and wave energy conversion devices and their stages of development, (2) identify where these technologies can best operate, (3) identify the potential environmental issues associated with these technologies and possible mitigation measures, and (4) develop a list of research needs and/or practical solutions to address unresolved environmental issues. The article reviews the results of that workshop, focusing on potential effects on freshwater, estuarine, and marine ecosystems, and we describe recent national and international developments.

Kinetic modeling of the polymer-derived ceramics route: investigation of the thermal decomposition kinetics of poly[B-(methylamino)borazine] precursors into boron nitride.

Science.gov (United States)

Bernard, Samuel; Fiaty, Koffi; Cornu, David; Miele, Philippe; Laurent, Pierre

2006-05-11

A complete kinetic modeling of the polymer-derived ceramics (PDCs) route is achieved for the first time through the investigation of the solid-state decomposition of a typical melt-spinnable poly[B-(methylamino)borazine] into boron nitride fibers at various heating rates. Through the use of the Lorentz fitting approach, it is shown that the two-step weight loss associated with the polymer-to-ceramic conversion is governed by a complex interplay of five diffusion-type transport mechanisms that are independent of the applied heating schedule. The application of the Friedman method to dynamic thermogravimetry data yields Ea and ln A values that are seen to increase with the extent of the ceramic conversion from region one (Ea = 38.73 kJ mol(-1)) to region five (Ea = 146.64 kJ mol(-1)). This fact indicates that both the mechanisms within those regions are parallel routes to the formation of the final solid-state material and their complexity increases with the conversion progress. The cross-linking process (first weight loss) of the polymer is governed by three dependent poorly energetic mechanisms. The first weight loss is activated by ammonolysis reactions that provide a modified polymer capable of undergoing condensation reactions in regions two and three to yield a highly cross-linked polymer. A large evolution of methylamine is identified during this process. Mineralization (region four) and ceramization (region five) steps are represented by two highly energetic multistep mechanisms. The mineralization step is associated with a large evolution of methylamine and occurs during the transition between the cross-linking and ceramization processes through the cleavage of the inter-ring B-N bonds. Ceramization represents the end of the polymer-to-ceramic conversion in which the planar consolidation of BN hexagons occurs through complex structural rearrangements of the borazine units (cleavage of the intraring B-N bonds) accompanied with an ammonia evolution. Finally

Drug-target residence time--a case for G protein-coupled receptors.

Science.gov (United States)

Guo, Dong; Hillger, Julia M; IJzerman, Adriaan P; Heitman, Laura H

2014-07-01

A vast number of marketed drugs act on G protein-coupled receptors (GPCRs), the most successful category of drug targets to date. These drugs usually possess high target affinity and selectivity, and such combined features have been the driving force in the early phases of drug discovery. However, attrition has also been high. Many investigational new drugs eventually fail in clinical trials due to a demonstrated lack of efficacy. A retrospective assessment of successfully launched drugs revealed that their beneficial effects in patients may be attributed to their long drug-target residence times (RTs). Likewise, for some other GPCR drugs short RT could be beneficial to reduce the potential for on-target side effects. Hence, the compounds' kinetics behavior might in fact be the guiding principle to obtain a desired and durable effect in vivo. We therefore propose that drug-target RT should be taken into account as an additional parameter in the lead selection and optimization process. This should ultimately lead to an increased number of candidate drugs moving to the preclinical development phase and on to the market. This review contains examples of the kinetics behavior of GPCR ligands with improved in vivo efficacy and summarizes methods for assessing drug-target RT. © 2014 Wiley Periodicals, Inc.

Changes in Personal Relationships During Residency and Their Effects on Resident Wellness: A Qualitative Study.

Science.gov (United States)

Law, Marcus; Lam, Michelle; Wu, Diana; Veinot, Paula; Mylopoulos, Maria

2017-11-01

Residency poses challenges for residents' personal relationships. Research suggests residents rely on family and friends for support during their training. The authors explored the impact of residency demands on residents' personal relationships and the effects changes in those relationships could have on their wellness. The authors used a constructivist grounded theory approach. In 2012-2014, they conducted semistructured interviews with a purposive and theoretical sample of 16 Canadian residents from various specialties and training levels. Data analysis occurred concurrently with data collection, allowing authors to use a constant comparative approach to explore emergent themes. Transcripts were coded; codes were organized into categories and then themes to develop a substantive theory. Residents perceived their relationships to be influenced by their evolving professional identity: Although personal relationships were important, being a doctor superseded them. Participants suggested they were forced to adapt their personal relationships, which resulted in the evolution of a hierarchy of relationships that was reinforced by the work-life imbalance imposed by their training. This poor work-life balance seemed to result in relationship issues and diminish residents' wellness. Participants applied coping mechanisms to manage the conflict arising from the adaptation and protect their relationships. To minimize the effects of identity dissonance, some gravitated toward relationships with others who shared their professional identity or sought social comparison as affirmation. Erosion of personal relationships could affect resident wellness and lead to burnout. Educators must consider how educational programs impact relationships and the subsequent effects on resident wellness.

A Comparison Between the Level of Happiness Among the Elderly Living at Home and That of Senior Home Residents

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2011-10-01

Full Text Available Objectives: The present study was designed to compare the level of happiness among the elderly population living at home with that of senior home residents. Methods & Materials: This was a causative-comparative study. The statistical population consisted of all 60 plus men and women residing at home and senior homes in the city of Tabriz, from whom 100 samples were selected in two groups of 50 individuals (25 females and 25 males using an availability non-random sampling method. The oxford happiness questionnaire was used in order to collect data, which were then analyzed using an independent t-test. Results: Results showed that the level of happiness among the elderly living at home was significantly higher than that of senior home residents. Furthermore, among indicators of happiness, life satisfaction levels, psychological health, positive mood, and efficiency were significantly higher among the elderly living at home. However, there was no significant difference between the two in terms of self-esteem. Conclusion: Findings indicate that, due to better social and family support, the level of happiness among the elderly living at home is significantly higher than that of senior home residents. Conversely, residing at senior homes consequent to financial and family conditions, for those who would otherwise live with family, leads to depressed mood, dissatisfaction with life, and ultimately lack of happiness.

Population control of resident and immigrant microglia by mitosis and apoptosis.

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Wirenfeldt, Martin; Dissing-Olesen, Lasse; Anne Babcock, Alicia; Nielsen, Marianne; Meldgaard, Michael; Zimmer, Jens; Azcoitia, Iñigo; Leslie, Robert Graham Quinton; Dagnaes-Hansen, Frederik; Finsen, Bente

2007-08-01

Microglial population expansion occurs in response to neural damage via processes that involve mitosis and immigration of bone marrow-derived cells. However, little is known of the mechanisms that regulate clearance of reactive microglia, when microgliosis diminishes days to weeks later. We have investigated the mechanisms of microglial population control in a well-defined model of reactive microgliosis in the mouse dentate gyrus after perforant pathway axonal lesion. Unbiased stereological methods and flow cytometry demonstrate significant lesion-induced increases in microglial numbers. Reactive microglia often occurred in clusters, some having recently incorporated bromodeoxyuridine, showing that proliferation had occurred. Annexin V labeling and staining for activated caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling showed that apoptotic mechanisms participate in dissolution of the microglial response. Using bone marrow chimeric mice, we found that the lesion-induced proliferative capacity of resident microglia superseded that of immigrant microglia, whereas lesion-induced kinetics of apoptosis were comparable. Microglial numbers and responses were severely reduced in bone marrow chimeric mice. These results broaden our understanding of the microglial response to neural damage by demonstrating that simultaneously occurring mitosis and apoptosis regulate expansion and reduction of both resident and immigrant microglial cell populations.

Overall Reduction Kinetics of Low-grade Pyrolusite Using a Mixture of Hemicellulose and Lignin as Reductant

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Yun-Fei Long

2015-11-01

Full Text Available Manganese is widely used in many fields. Many efforts have been made to recover manganese from low-grade pyrolusite due to the depletion of high-grade manganese ore. Thus, it is of practical significance to develop a clean, energy-saving and environmentally friendly technical route to reduce the low-grade pyrolusite. The reported results show that biomass wastes from crops, crop waste, wood and wood waste are environmentally friendly, energy-saving, and low-cost reducing agents for roasting reduction of low-grade pyrolusite. Kinetics of the reduction reactions is necessary for an efficient design of biomass reduction of pyrolusite. Therefore, it is important to look for a general kinetics equation to describe the reduction of pyrolusite by different kinds of biomass, because there is a wide variety of biomass wastes, meaning that it is impossible to investigate the kinetics for each biomass waste. In this paper, thermal gravimetric analysis and differential thermal analysis were applied to study the overall reduction kinetics of pyrolusite using a mixture of hemicellulose and lignin, two major components of biomass. Overall reduction process is the overlap of the respective reduction processes. A new empirical equation based on the Johnson–Mehl–Avrami equation can be used to describe the respective reduction kinetics using hemicellulose and lignin as reductants, and the corresponding apparent activation energy is 30.14 kJ mol−1 and 38.91 kJ mol−1, respectively. The overall kinetic model for the reduction of pyrolusite by the mixture of hemicellulose and lignin can be simulated by the summation of the respective kinetics by considering their mass-loss fractions, while a unit step function was used to avoid the invalid conversion data. The obtained results in this work are necessary to understand the biomass reduction of pyrolusite and provide valuable assistance in the development of a general kinetics equation.

Perioperative self-reflection among surgical residents.

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Peshkepija, Andi N; Basson, Marc D; Davis, Alan T; Ali, Muhammad; Haan, Pam S; Gupta, Rama N; Hardaway, John C; Nebeker, Cody A; McLeod, Michael K; Osmer, Robert L; Anderson, Cheryl I

2017-09-01

We studied prevalence and predictors of meaningful self-reflection among surgical residents and with prompting/structured interventions, sought to improve/sustain resident skills. Residents from six programs recorded 1032 narrative self-reflective comments (120 residents), using a web-based platform. If residents identified something learned or to be improved, self-reflection was deemed meaningful. Independent variables PGY level, resident/surgeon gender, study site/Phase1: July2014-August2015 vs. Phase2: September2015-September2016) were analyzed. Meaningful self-reflection was documented in 40.6% (419/1032) of entries. PGY5's meaningfully self-reflected less than PGY1-4's, 26.1% vs. 49.6% (p = 0.002). In multivariate analysis, resident narratives during Phase 2 were 4.7 times more likely to engage in meaningful self-reflection compared to Phase1 entries (p self-reflection, compared to Phase1. Surgical residents uncommonly practice meaningful self-reflection, even when prompted, and PGY5/chief residents reflect less than more junior residents. Substantial/sustained improvements in resident self-reflection can occur with both training and interventions. Copyright © 2017 Elsevier Inc. All rights reserved.

Using spontaneous commentary of nursing home residents to develop resident-centered measurement tools: A case study.

Science.gov (United States)

Bangerter, Lauren R; Abbott, Katherine; Heid, Allison; Eshraghi, Karen; Van Haitsma, Kimberly

Nursing home (NH) residents routinely complete surveys that assess their health, well-being, preferences, and care needs. Such surveys reveal important information, however, are largely based on the concerns of providers as opposed to the concerns of residents. Thus, researchers must enhance efforts to ensure that these surveys are guided by the priorities, needs, and concerns of residents. We present a case study to demonstrate how spontaneous commentary of NH residents holds particular efficacy for ensuring that measurement tools are guided by the needs, concerns, and priorities of residents. Spontaneous comments from NH residents (N = 370) collected as part of a study developing the Preferences for Everyday Living Inventory for NH residents (PELI-NH) were used to refine the PELI-NH across key phases of measurement development. This work demonstrates how the spontaneous commentary of NH residents may contribute to the refinement of NH measurement tools, and allow researchers to base these tools on the needs and priorities of NH residents. Copyright © 2017 Elsevier Inc. All rights reserved.

Status of anesthesiology resident research education in the United States: structured education programs increase resident research productivity.

Science.gov (United States)

Ahmad, Shireen; De Oliveira, Gildasio S; McCarthy, Robert J

2013-01-01

The enhancement of resident research education has been proposed to increase the number of academic anesthesiologists with the skills and knowledge to conduct meaningful research. Program directors (PDs) of the U.S. anesthesiology residency programs were surveyed to evaluate the status of research education during residency training and to test the hypothesis that structured programs result in greater resident research productivity based on resident publications. Survey responses were solicited from 131 anesthesiology residency PDs. Seventy-four percent of PDs responded to the survey. Questions evaluated department demographic information, the extent of faculty research activity, research resources and research funding in the department, the characteristics of resident research education and resident research productivity, departmental support for resident research, and perceived barriers to resident research education. Thirty-two percent of programs had a structured resident research education program. Structured programs were more likely to be curriculum based, require resident participation in a research project, and provide specific training in presentation and writing skills. Productivity expectations were similar between structured and nonstructured programs. Forty percent of structured programs had > 20% of trainees with a publication in the last 2 years compared with 14% of departments with unstructured programs (difference, 26%; 99% confidence interval [CI], 8%-51%; P = 0.01). The percentage of programs that had research rotations for ≥2 months was not different between the structured and the nonstructured programs. A research rotation of >2 months did not increase the percentage of residents who had published an article within the last 2 months compared with a research rotation of 20% of residents with a publication in the last 2 years compared with 36% in programs with >20% of faculty involvement (difference, 21%; 99% CI, -4% to 46%; P = 0.03). Our

Resident perceptions of the impact of duty hour restrictions on resident-attending interactions: an exploratory study.

Science.gov (United States)

Gerjevic, Kristen A; Rosenbaum, Marcy E; Suneja, Manish

2017-07-18

The institution of duty hour reforms by the Accreditation Council for Graduate Medical Education in 2003 has created a learning environment where residents are consistently looking for input from attending physicians with regards to balancing duty hour regulations and providing quality patient care. There is a paucity of literature regarding resident perceptions of attending physician actions or attitudes towards work hour restrictions. The purpose of this study was to identify attending physician behaviors that residents perceived as supportive or unsupportive of their compliance with duty hour regulations. Focus group interviews were conducted with residents exploring their perceptions of how duty hour regulations impact their interactions with attending physicians. Qualitative analysis identified key themes in residents' experiences interacting with faculty in regard to duty hour regulations. Forty residents from five departments in two hospital systems participated. Discussion of these interactions highlighted that attending physicians demonstrate behaviors that explicitly or implicitly either lend their support and understanding of residents' need to comply with these regulations or imply a lack of support and understanding. Three major themes that contributed to the ease or difficulty in addressing duty hour regulations included attending physicians' explicit communication of expectations, implicit non-verbal and verbal cues and the program's organizational culture. Resident physicians' perception of attending physicians' explicit and implicit communication and residency programs organization culture has an impact on residents' experience with duty hour restrictions. Residency faculty and programs could benefit from explicitly addressing and supporting the challenges that residents perceive in complying with duty hour restrictions.

Psychotherapy Training: Residents' Perceptions and Experiences.

Science.gov (United States)

Kovach, Jessica G; Dubin, William R; Combs, Christopher J

2015-10-01

This survey examined actual training hours in psychotherapy modalities as reported by residents, residents' perceptions of training needs, and residents' perceptions of the importance of different aspects of psychotherapy training. A brief, voluntary, anonymous, Internet-based survey was developed. All 14 program directors for Accreditation Council for Graduate Medical Education accredited programs in Pennsylvania, New Jersey, and Delaware provided email addresses for current categorical residents. The survey inquired about hours of time spent in various aspects of training, value assigned to aspects of training, residents' involvement in their own psychotherapy, and overall resident wellness. The survey was e-mailed to 328 residents. Of the 328 residents contacted, 133 (40.5%) responded. Median reported number of PGY 3 and 4 performed versus perceived ideal hours of supportive therapy, cognitive behavioral therapy (CBT), and psychodynamic therapy did not differ. Answers for clinical time utilizing these modalities ranged from "none or less than 1 h" per month to 20+ h per month. PGY 3 and 4 residents reported a median of "none or less than 1 h" per month performed of interpersonal, dialectical behavior therapy, couples/family/group, and child therapies but preferred more time using these therapies. Residents in all years of training preferred more hours of didactic instruction for all psychotherapies and for medication management. Residents ranked teaching modalities in the following order of importance: supervision, hours of psychotherapy performed, personal psychotherapy, readings, and didactic instruction. Residents engaged in their own psychotherapy were significantly more likely to rank the experiential aspects of psychotherapy training (personal psychotherapy, supervision, and hours performed) higher than residents not in psychotherapy. Current psychotherapy training for psychiatry residents is highly variable, but overall, residents want more

Kinetics of Hydrogen Absorption and Desorption in Titanium

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Suwarno Suwarno

2017-10-01

Full Text Available Titanium is reactive toward hydrogen forming metal hydride which has a potential application in      energy storage and conversion. Titanium hydride has been widely studied for hydrogen storage, thermal storage, and battery electrodes applications. A special interest is using titanium for hydrogen production in a hydrogen sorption-enhanced steam reforming of natural gas. In the present work, non-isothermal dehydrogenation kinetics of titanium hydride and kinetics of hydrogenation in gaseous flow at isothermal conditions were investigated. The hydrogen desorption was studied using temperature desorption spectroscopy (TDS while the hydrogen absorption and desorption in gaseous flow were studied by temperature programmed desorption (TPD. The present work showed that the path of dehydrogenation of the TiH2 is d®b®a hydride phase with possible overlapping steps occurred. The fast hydrogen desorption rate observed at the TDS main peak temperature were correlated with the fast transformation of the d-TiH1.41 to b-TiH0.59. In the gaseous flow, hydrogen absorption and desorption were related to the transformation of b-TiH0.59 Û d-TiH1.41 with 2 wt.% hydrogen reversible content. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 20th March 2017; Accepted: 9th April 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Suwarno, S., Yartys, V.A. (2017. Kinetics of Hydrogen Absorption and Desorption in Titanium. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (3: 312-317  (doi:10.9767/bcrec.12.3.810.312-317

Kinetics of the hydrothermal treatment of tannin for producing carbonaceous microspheres.

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Braghiroli, F L; Fierro, V; Izquierdo, M T; Parmentier, J; Pizzi, A; Celzard, A

2014-01-01

Aqueous solutions of condensed tannins were submitted to hydrothermal carbonization (HTC) in a stainless steel autoclave, and the kinetics of hydrothermal carbon formation was investigated by changing several parameters: amount of tannin (0.5; 1.0; 1.5; 2.0 g in 16 mL of water), HTC temperature (130, 160, 180 and 200°C) and reaction times (from 1 to 720 h). The morphology and the structure of the tannin-based hydrothermal carbons were studied by TEM, krypton adsorption at -196°C and helium pycnometry. These materials presented agglomerated spherical particles, having surface areas ranging from 0.6 to 10.0 m(2) g(-1). The chemical composition of the hydrothermal carbons was found to be constant and independent of reaction time. HTC kinetics of tannin were determined and shown to correspond to first-order reaction. Temperature-dependent measurements led to an activation energy of 91 kJ mol(-1) for hydrothermal conversion of tannin into carbonaceous microspheres separable by centrifugation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hydrolytic Activation Kinetics of the Herbicide Benzobicyclon in Simulated Aquatic Systems.

Science.gov (United States)

Williams, Katryn L; Tjeerdema, Ronald S

2016-06-22

Herbicide resistance is a growing concern for weeds in California rice fields. Benzobicyclon (BZB; 3-(2-chloro-4-(methylsulfonyl)benzoyl)-2-phenylthiobicyclo[3.2.1]oct-2-en-4-one) has proven successful against resistant rice field weeds in Asia. A pro-herbicide, BZB forms the active agent, benzobicyclon hydrolysate (BH), in water; however, the transformation kinetics are not understood for aquatic systems, particularly flooded California rice fields. A quantitative experiment was performed to assess the primary mechanism and kinetics of BZB hydrolysis to BH. Complete conversion to BH was observed for all treatments. Basic conditions (pH 9) enhanced the reaction, with half-lives ranging from 5 to 28 h. Dissolved organic carbon (DOC) hindered transformation, which is consistent with other base-catalyzed hydrolysis reactions. BH was relatively hydrolytically stable, with 18% maximum loss after 5 days. Results indicate BZB is an efficient pro-herbicide under aqueous conditions such as those of a California rice field, although application may be best suited for fields with recirculating tailwater systems.

Operative time and cost of resident surgical experience: effect of instituting an otolaryngology residency program.

Science.gov (United States)

Pollei, Taylor R; Barrs, David M; Hinni, Michael L; Bansberg, Stephen F; Walter, Logan C

2013-06-01

Describe the procedure length difference between surgeries performed by an attending surgeon alone compared with the resident surgeon supervised by the same attending surgeon. Case series with chart review. Tertiary care center and residency program. Six common otolaryngologic procedures performed between August 1994 and May 2012 were divided into 2 cohorts: attending surgeon alone or resident surgeon. This division coincided with our July 2006 initiation of an otolaryngology-head and neck surgery residency program. Operative duration was compared between cohorts with confounding factors controlled. In addition, the direct result of increased surgical length on operating room cost was calculated and applied to departmental and published resident case log report data. Five of the 6 procedures evaluated showed a statistically significant increase in surgery length with resident involvement. Operative time increased 6.8 minutes for a cricopharyngeal myotomy (P = .0097), 11.3 minutes for a tonsillectomy (P operative time difference. Cost of increased surgical time was calculated per surgery and ranged from $286 (cricopharyngeal myotomy) to $2142 (mastoidectomy). When applied to reported national case log averages for graduating residents, this resulted in a significant increase of direct training-related costs. Resident participation in the operating room results in increased surgical length and additional system cost. Although residency is a necessary part of surgical training, associated costs need to be acknowledged.

First-Year Residents Outperform Third-Year Residents after Simulation-Based Education in Critical Care Medicine

Science.gov (United States)

Singer, Benjamin D.; Corbridge, Thomas C.; Schroedl, Clara J.; Wilcox, Jane E.; Cohen, Elaine R.; McGaghie, William C.; Wayne, Diane B.

2012-01-01

Introduction Prior research shows that gaps exist in internal medicine residents’ critical care knowledge and skills. The purpose of this study was to compare the bedside critical care competency of first-year residents who received a simulation-based educational intervention plus clinical training to third-year residents who received clinical training alone. Methods During their first three months of residency, a group of first-year residents completed a simulation-based educational intervention. A group of traditionally-trained third-year residents who did not receive simulation-based training served as a comparison group. Both groups were evaluated using a 20-item clinical skills assessment at the bedside of a patient receiving mechanical ventilation at the end of their medical intensive care unit rotation. Scores on the skills assessment were compared between groups. Results Simulator-trained first-year residents (n=40) scored significantly higher compared to traditionally-trained third-year residents (n=27) on the bedside assessment, 91.3% (95% CI 88.2% to 94.3%) vs. 80.9% (95% CI 76.8% to 85.0%), P = simulation-based educational intervention demonstrated higher clinical competency than third-year residents who did not undergo simulation training. Critical care competency cannot be assumed after clinical ICU rotations; simulation-based curricula can help ensure residents are proficient to care for critically ill patients. PMID:23222546

Surgical resident learning styles: faculty and resident accuracy at identification of preferences and impact on ABSITE scores.

Science.gov (United States)

Kim, Roger H; Gilbert, Timothy; Ristig, Kyle; Chu, Quyen D

2013-09-01

As a consequence of surgical resident duty hour restrictions, there is a need for faculty to utilize novel teaching methods to convey information in a more efficient manner. The current paradigm of surgical training, which has not changed significantly since the time of Halsted, assumes that all residents assimilate information in a similar fashion. However, recent data has shown that learners have preferences for the ways in which they receive and process information. The VARK model categorizes learners as visual (V), aural (A), read/write (R), and kinesthetic (K). The VARK learning style preferences of surgical residents have not been previously evaluated. In this study, the preferred learning styles of general surgery residents were determined, along with faculty and resident perception of resident learning styles. In addition, we hypothesized that American Board of Surgery In-Training Exam (ABSITE) scores are associated with preference for a read/write (R) learning style. The Fleming VARK learning styles inventory was administered to all general surgery residents at a university hospital-based program. Responses on the inventory were scored to determine the preferred learning style for each resident. Faculty members were surveyed to determine their accuracy in identifying the preferred learning style of each resident. All residents were also surveyed to determine their accuracy in identifying their peers' VARK preferences. Resident ABSITE scores were examined for association with preferred learning styles. Twenty-nine residents completed the inventory. Most (18 of 29, 62%) had a multimodal preference, although more than a third (11 of 29, 38%) demonstrated a single-modality preference. Seventy-six percent of all residents (22 of 29) had some degree of kinesthetic (K) learning, while under 50% (14 of 29) were aural (A) learners. Although not significant, dominant (R) learners had the highest mean ABSITE scores. Faculty identified residents' learning styles

Experimental study of the efficiency of transformation of the dense plasma hypersonic flow kinetic energy into a radiation

International Nuclear Information System (INIS)

Kamrukov, A.S.; Kozlov, N.P.; Myshelov, E.P.; Protasov, Yu.S.

1981-01-01

Analysis of physical specific features of radiator where plasma heating is performed with tbermalization of directed kinetic energy of dense plasma flows accelerated electrodynamically up to hypersonic velocities during its shock deceleration, is given. It is shown that the plasma heating method considered has a number of principle advantages as compared with methods most disseminated now for generation of dense intensively radiating plasma (current heating exploding method) and suggests new possibilities for construction of selective high brightness radiat.ion sources of ultraviolet and far vacuum ultraviolet ranges of spectrum. Radiation gas dynamic processes of hypersonic plasma flow deceleration formed with magnetoplasma compressors have been experimentally investigated on their interaction with condenced matters in vacuum and basic thermodynamic parameters of shock compressed plasma have been determined. It is shown that the conversion process of kinetic energy of high-velocity plasma flows to radiation is accomplished at very high efficiency-integral luminescence of shock compressed plasma can reach approximately 90% of initial kinetic energy of flow [ru

Continuous esterification to produce biodiesel by SPES/PES/NWF composite catalytic membrane in flow-through membrane reactor: experimental and kinetic studies.

Science.gov (United States)

Shi, Wenying; He, Benqiao; Cao, Yuping; Li, Jianxin; Yan, Feng; Cui, Zhenyu; Zou, Zhiqun; Guo, Shiwei; Qian, Xiaomin

2013-02-01

A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml min(-1). The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data. Copyright © 2012 Elsevier Ltd. All rights reserved.

Titanium dioxide nanotube membranes for solar energy conversion: effect of deep and shallow dopants.

Science.gov (United States)

Ding, Yuchen; Nagpal, Prashant

2017-04-12

Nanostructured titanium dioxide (TiO 2 ) has been intensively investigated as a material of choice for solar energy conversion in photocatalytic, photoelectrochemical, photovoltaic, and other photosensitized devices for converting light into chemical feedstocks or electricity. Towards management of light absorption in TiO 2 , while the nanotubular structure improves light absorption and simultaneous charge transfer to mitigate problems due to the indirect bandgap of the semiconductor, typically dopants are used to improve light absorption of incident solar irradiation in the wide bandgap of TiO 2 . While these dopants can be critical to the success of these solar energy conversion devices, their effect on photophysical and photoelectrochemical properties and detailed photokinetics are relatively under-studied. Here, we show the effect of deep and shallow metal dopants on the kinetics of photogenerated charged carriers in TiO 2 and the resulting effect on photocatalytic and photoelectrochemical processes using these nanotube membranes. We performed a detailed optical, electronic, voltammetry and electrochemical impedance study to understand the effect of shallow and deep metal dopants (using undoped and niobium- and copper-doped TiO 2 nanotubes) on light absorption, charge transport and charge transfer processes. Using wireless photocatalytic methylene blue degradation and carbon dioxide reduction, and wired photoelectrochemical device measurements, we elucidate the effect of different dopants on solar-to-fuel conversion efficiency and simultaneously describe the photokinetics using a model, to help design better energy conversion devices.

Skin-Resident T Cells Drive Dermal Dendritic Cell Migration in Response to Tissue Self-Antigen.

Science.gov (United States)

Ali, Niwa; Zirak, Bahar; Truong, Hong-An; Maurano, Megan M; Gratz, Iris K; Abbas, Abul K; Rosenblum, Michael D

2018-05-01

Migratory dendritic cell (DC) subsets deliver tissue Ags to draining lymph nodes (DLNs) to either initiate or inhibit T cell-mediated immune responses. The signals mediating DC migration in response to tissue self-antigen are largely unknown. Using a mouse model of inducible skin-specific self-antigen expression, we demonstrate that CD103 + dermal DCs (DDCs) rapidly migrate from skin to skin DLN (SDLNs) within the first 48 h after Ag expression. This window of time was characterized by the preferential activation of tissue-resident Ag-specific effector T cells (Teffs), with no concurrent activation of Ag-specific Teffs in SDLNs. Using genetic deletion and adoptive transfer approaches, we show that activation of skin-resident Teffs is required to drive CD103 + DDC migration in response to tissue self-antigen and this Batf3-dependent DC population is necessary to mount a fulminant autoimmune response in skin. Conversely, activation of Ag-specific Teffs in SDLNs played no role in DDC migration. Our studies reveal a crucial role for skin-resident T cell-derived signals, originating at the site of self-antigen expression, to drive DDC migration during the elicitation phase of an autoimmune response. Copyright © 2018 by The American Association of Immunologists, Inc.

Personal finances of urology residents in Canada.

Science.gov (United States)

Teichman, J M; Tongco, W; MacNeily, A E; Smart, M

2000-12-01

We examined how Urology residents in Canada manage their personal finances. A survey instrument was designed to elicit information on demographics, expenses, savings and incomes. The questionnaire was completed by 40 Urology residents attending the 2000 Queen's Urology Exam Skills Training (QUEST) program. Twenty-eight residents (70%) had educational debt (median debt $50 000). Seventeen residents (45%) paid credit card interest charges within the last year. Four residents (10%) maintained an unpaid credit card balance > $7500 at 17% annual interest rate. Twenty-six residents (67%) contributed to Registered Retirement Savings Program (RRSP) accounts. Seventeen residents (44%) contributed to non-RRSP retirement accounts. Nineteen residents (50%) budgeted expenses. Median resident income was $45 000. Thirteen residents (34%) had cash reserves < $250. Many residents save little, and incur substantial debt over and above educational loans. Many residents would benefit from instruction concerning prudent financial management. Residents should be informed of the consequences of low saving and high debt.

Formulation, radiopharmaceutical kinetics and dosimetry of the 188Re(V)-DMSA complex

International Nuclear Information System (INIS)

Garcia S, L.; Ferro F, G.; Murphy, C.A. de; Pedraza L, M.; Azorin N, J.

1999-01-01

It was developed through experimental design (ANOVA), a formulation to prepare the 188 Re(V)-Dmsa complex. Likewise, there were realized studies of radiopharmaceutical kinetics and internal dosimetry in animals, its normal and with induced tumors, considering an open bi compartmental model using the MIRD methodology. The 188 Re(V)-Dmsa complex was obtained with a radiochemical purity greater than 95% incubating 30 min at 90 Centigrade under the following formulation: [SnCl 2 ] = 1.4 mg/ml, [ascorbic acid] = 0.5 mg/ml, p H = 2.0 - 3.0. The stability test of the formulation, shows that after 48 h of its preparation, does not produce radiolytic degradation neither chemical decomposition. The radiopharmaceutical kinetics data show an average residence time 7.2h, velocity constant α = 0.6508h -1 and β = 0.1046 h -1 with an apparent distribution volume 6.9 l. The main elimination via was renal and it was observed osseous caption with an accumulated activity 522.049 ± 62 MBq h (residence time 14.1094 ± 1.69h). In according with the dosimetric calculations, by each 37 MBq injected, the equivalent dose at the tumor was 9.67± 0.33 Sv/g, for an effective dose 0.292 ± 0.0017 mSv/MBq. The images obtained in the gamma camera of the mice with induced tumors, show that do not have significant accumulation in the metabolic organs. The caption in bone and in tumors induced of the 188 Re(V)-Dmsa complex, show its potential for be used as a palliative agent for pain in patients with osseous metastasis and in the treatment of tumors of soft tissue. (Author)

Computers and conversation

CERN Document Server

Luff, Paul; Gilbert, Nigel G

1986-01-01

In the past few years a branch of sociology, conversation analysis, has begun to have a significant impact on the design of human*b1computer interaction (HCI). The investigation of human*b1human dialogue has emerged as a fruitful foundation for interactive system design.****This book includes eleven original chapters by leading researchers who are applying conversation analysis to HCI. The fundamentals of conversation analysis are outlined, a number of systems are described, and a critical view of their value for HCI is offered.****Computers and Conversation will be of interest to all concerne

Mental health literacy as a function of remoteness of residence: an Australian national study.

Science.gov (United States)

Griffiths, Kathleen M; Christensen, Helen; Jorm, Anthony F

2009-03-27

Although there have been many population studies of mental health literacy, little is known about the mental health literacy of people who reside in rural areas. This study sought to determine the impact of remoteness on public knowledge of depression and schizophrenia. The mental health literacy of residents of major cities, inner regional, and outer-remote (including outer regional, remote, and very remote) regions were compared using data from a 2003-04 Australian national survey of the mental health literacy of 3998 adults. Measures included the perceived helpfulness of a range of professionals, non-professionals and interventions, and the causes, prognosis, and outcomes after treatment for four case vignettes describing depression, depression with suicidal ideation, early schizophrenia and chronic schizophrenia. Participant awareness of Australia's national depression initiative and depression in the media, their symptoms of depression and exposure to the conditions depicted in the vignettes were also compared. Mental health literacy was similar across remoteness categories. However, inner regional residents showed superior identification of the disorders depicted in the suicidal ideation and chronic schizophrenia vignettes. They were also more likely to report having heard of Australia's national depression health promotion campaign. Conversely, they were less likely than major city residents to rate the evidence-based treatment of psychotherapy helpful for depression. Both inner regional and outer-remote residents were less likely to rate psychologists as helpful for depression alone. The rural groups were more likely to rate the non-evidence based interventions of drinking and painkillers as helpful for a depression vignette. In addition, outer-remote residents were more likely to identify the evidence based treatment of antipsychotics as harmful for early schizophrenia and less likely to endorse psychiatrists, psychologists, social workers and general

Mental health literacy as a function of remoteness of residence: an Australian national study

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Jorm Anthony F

2009-03-01

Full Text Available Abstract Background Although there have been many population studies of mental health literacy, little is known about the mental health literacy of people who reside in rural areas. This study sought to determine the impact of remoteness on public knowledge of depression and schizophrenia. Methods The mental health literacy of residents of major cities, inner regional, and outer-remote (including outer regional, remote, and very remote regions were compared using data from a 2003–04 Australian national survey of the mental health literacy of 3998 adults. Measures included the perceived helpfulness of a range of professionals, non-professionals and interventions, and the causes, prognosis, and outcomes after treatment for four case vignettes describing depression, depression with suicidal ideation, early schizophrenia and chronic schizophrenia. Participant awareness of Australia's national depression initiative and depression in the media, their symptoms of depression and exposure to the conditions depicted in the vignettes were also compared. Results Mental health literacy was similar across remoteness categories. However, inner regional residents showed superior identification of the disorders depicted in the suicidal ideation and chronic schizophrenia vignettes. They were also more likely to report having heard of Australia's national depression health promotion campaign. Conversely, they were less likely than major city residents to rate the evidence-based treatment of psychotherapy helpful for depression. Both inner regional and outer-remote residents were less likely to rate psychologists as helpful for depression alone. The rural groups were more likely to rate the non-evidence based interventions of drinking and painkillers as helpful for a depression vignette. In addition, outer-remote residents were more likely to identify the evidence based treatment of antipsychotics as harmful for early schizophrenia and less likely to endorse

Mental health literacy as a function of remoteness of residence: an Australian national study

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Griffiths, Kathleen M; Christensen, Helen; Jorm, Anthony F

2009-01-01

Background Although there have been many population studies of mental health literacy, little is known about the mental health literacy of people who reside in rural areas. This study sought to determine the impact of remoteness on public knowledge of depression and schizophrenia. Methods The mental health literacy of residents of major cities, inner regional, and outer-remote (including outer regional, remote, and very remote) regions were compared using data from a 2003–04 Australian national survey of the mental health literacy of 3998 adults. Measures included the perceived helpfulness of a range of professionals, non-professionals and interventions, and the causes, prognosis, and outcomes after treatment for four case vignettes describing depression, depression with suicidal ideation, early schizophrenia and chronic schizophrenia. Participant awareness of Australia's national depression initiative and depression in the media, their symptoms of depression and exposure to the conditions depicted in the vignettes were also compared. Results Mental health literacy was similar across remoteness categories. However, inner regional residents showed superior identification of the disorders depicted in the suicidal ideation and chronic schizophrenia vignettes. They were also more likely to report having heard of Australia's national depression health promotion campaign. Conversely, they were less likely than major city residents to rate the evidence-based treatment of psychotherapy helpful for depression. Both inner regional and outer-remote residents were less likely to rate psychologists as helpful for depression alone. The rural groups were more likely to rate the non-evidence based interventions of drinking and painkillers as helpful for a depression vignette. In addition, outer-remote residents were more likely to identify the evidence based treatment of antipsychotics as harmful for early schizophrenia and less likely to endorse psychiatrists, psychologists

Simulation of the organic-waste processing in plasma with allowance for kinetics of thermochemical transformations

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Messerle, V. E.; Ustimenko, A. B.

2017-07-01

Kinetic calculations of the plasma processing/utilization process of organic waste in air and steam ambient were carried out. It is shown that, during the time of waste residence in the plasma reactor, 0.7 and 1.2 s, at the exit from the reactor there forms a high-calorific fuel gas with a combustion heat of 3540 and 5070 kcal/kg, respectively. In this process, 1 kg of waste yields 1.16 kg of fuel gas at air gasification of waste and 0.87 kg of pure synthesis gas at steam gasification. The energy efficiency of the waste gasification process, defined by the ratio between the calorific value of the resultant fuel gas and the initial calorific value of the waste amounts to 91 % in air plasma and 98 % in steam plasma. A comparison between the results of kinetic and thermodynamic calculations has revealed their good agreement.

The Advancing a Healthier Wisconsin Endowment: How a Health Care Conversion Foundation Is Transforming a Medical School.

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Maurana, Cheryl A; Lucey, Paula A; Ahmed, Syed M; Kerschner, Joseph E; Bolton, G Allen; Raymond, John R

2016-01-01

Health care conversion foundations, such as the Advancing a Healthier Wisconsin Endowment (the endowment) at the Medical College of Wisconsin (MCW), result from the conversion of nonprofit health organizations to for-profit corporations. Over the past several decades, nearly 200 of these foundations have been created, and they have had a substantial impact on the field of health philanthropy. The MCW was a recipient of funds resulting from Blue Cross & Blue Shield United of Wisconsin's conversion from a nonprofit to a for-profit status in 1999. Established in 2004, the endowment has invested approximately $185 million in 337 research, education, and public and community health initiatives that benefit Wisconsin residents. However, the transformative potential of the health care conversion foundation has extended well beyond the opportunities provided through the endowment's financial resources. As the endowment celebrates its 10th anniversary, the authors describe the transformative nature of the endowment, as well as significant accomplishments and lessons learned, in the following areas: shared power, community partnerships, translational research, and integration of medicine and public health. It is the authors' hope that these lessons will be valuable to other medical schools and the communities they serve, as they invest in improving the health of their communities, irrespective of the funding source.

Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

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Ripeng Jiang

2014-07-01

Full Text Available The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

Modelling and determination of the kinetic parameters of the pyrolysis of Dichrostachys cinerea

International Nuclear Information System (INIS)

Abreu Naranjo, Reinier; Romero Romero, Osvaldo

2011-01-01

In the present study were analyzed biomass samples of Dichrostachys cinerea, commonly known in Cuba as marabou, by thermogravimetric method at various heating rates of devolatilization in nitrogen atmosphere at 5, 10 and 20 C min-1. On the kinetic analysis was used a mechanism of three independent reactions of order 1, generally attributed to three chief components of this kind of lignocellulose materials, hemicelluloses, cellulose and lignin. The values of activation energy, pre-exponential factor and contribution factor were similar to those reported in previous research for this type of biomass. The proposed model predicts with acceptable correlation the experimental and calculated curves of the decomposition of D. cinerea, with a deviation factor less than 5% for the temperature range studied. On the other hand, the kinetic parameters of the thermal decomposition coupled at equations of transport phenomena are essential to optimize the design and use of biomass thermochemical conversion processes, hence the importance of the research. (author)

Resident satisfaction on their residence and environment (case study of Srondol Bumi Indah Housing of Semarang City)

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Hariyono, Paulus

2017-12-01

A piece of an architecture work will be meaningful if it meets the needs of the residents. Likewise, the design and natural environment of a residence will surely be meaningful if it is able to satisfy the residents. The degree of satisfaction can be referred to the theory of human need hierarchy proposed by Abraham Maslow. Although his theory is an old one, it is still a good one for a reference. Socio economic status (SES)also affects someone in understanding the comfort of his resident. This research has some purpose: 1) to know the satisfaction level of the residents, 2) to know the effects of socio economic status towards the residents, and 3) to know the natural environment aspect to resident satisfaction. The methode analysis used is qualitative analysis. The major finding are: 1)security factor is the main aspect of the human need residents; 2) upper and lowerclass residents have different knowledge and understanding regarding the natural environment satisfaction on the house they live.

An Evidence-based, Longitudinal Curriculum for Resident Physician Wellness: The 2017 Resident Wellness Consensus Summit.

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Arnold, Jacob; Tango, Jennifer; Walker, Ian; Waranch, Chris; McKamie, Joshua; Poonja, Zafrina; Messman, Anne

2018-03-01

Physicians are at much higher risk for burnout, depression, and suicide than their non-medical peers. One of the working groups from the May 2017 Resident Wellness Consensus Summit (RWCS) addressed this issue through the development of a longitudinal residency curriculum to address resident wellness and burnout. A 30-person (27 residents, three attending physicians) Wellness Curriculum Development workgroup developed the curriculum in two phases. In the first phase, the workgroup worked asynchronously in the Wellness Think Tank - an online resident community - conducting a literature review to identify 10 core topics. In the second phase, the workgroup expanded to include residents outside the Wellness Think Tank at the live RWCS event to identify gaps in the curriculum. This resulted in an additional seven core topics. Seventeen foundational topics served as the framework for the longitudinal resident wellness curriculum. The curriculum includes a two-module introduction to wellness; a seven-module "Self-Care Series" focusing on the appropriate structure of wellness activities and everyday necessities that promote physician wellness; a two-module section on physician suicide and self-help; a four-module "Clinical Care Series" focusing on delivering bad news, navigating difficult patient encounters, dealing with difficult consultants and staff members, and debriefing traumatic events in the emergency department; wellness in the workplace; and dealing with medical errors and shame. The resident wellness curriculum, derived from an evidence-based approach and input of residents from the Wellness Think Tank and the RWCS event, provides a guiding framework for residency programs in emergency medicine and potentially other specialties to improve physician wellness and promote a culture of wellness.

An Evidence-based, Longitudinal Curriculum for Resident Physician Wellness: The 2017 Resident Wellness Consensus Summit

Directory of Open Access Journals (Sweden)

Jacob Arnold

2018-02-01

Full Text Available Introduction: Physicians are at much higher risk for burnout, depression, and suicide than their non-medical peers. One of the working groups from the May 2017 Resident Wellness Consensus Summit (RWCS addressed this issue through the development of a longitudinal residency curriculum to address resident wellness and burnout. Methods: A 30-person (27 residents, three attending physicians Wellness Curriculum Development workgroup developed the curriculum in two phases. In the first phase, the workgroup worked asynchronously in the Wellness Think Tank – an online resident community – conducting a literature review to identify 10 core topics. In the second phase, the workgroup expanded to include residents outside the Wellness Think Tank at the live RWCS event to identify gaps in the curriculum. This resulted in an additional seven core topics. Results: Seventeen foundational topics served as the framework for the longitudinal resident wellness curriculum. The curriculum includes a two-module introduction to wellness; a seven-module “Self-Care Series” focusing on the appropriate structure of wellness activities and everyday necessities that promote physician wellness; a two-module section on physician suicide and self-help; a four-module “Clinical Care Series” focusing on delivering bad news, navigating difficult patient encounters, dealing with difficult consultants and staff members, and debriefing traumatic events in the emergency department; wellness in the workplace; and dealing with medical errors and shame. Conclusion: The resident wellness curriculum, derived from an evidence-based approach and input of residents from the Wellness Think Tank and the RWCS event, provides a guiding framework for residency programs in emergency medicine and potentially other specialties to improve physician wellness and promote a culture of wellness.

Burnout Syndrome During Residency.

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Turgut, Namigar; Karacalar, Serap; Polat, Cengiz; Kıran, Özlem; Gültop, Fethi; Kalyon, Seray Türkmen; Sinoğlu, Betül; Zincirci, Mehmet; Kaya, Ender

2016-10-01

The aim of this study is identified the degree of Burnout Syndrome (BOS) and find out its correlation with years of recidency and sociodemograpfic chareacteristics, training, sleeping habits, such as smoking and alcohol consumption. After approval from the Hospital Ethics Committee and obtaining informed consent, First, second, third, fourth and fifth year of recidency staff (n=127) working in our hospital were involved in this study. The standardized Maslach Burnout Inventory (MBI) was used in this study. Fifty six male (44.1%) and seventy one female (55.9%) residents were enroled in this study (Coranbach Alfa(α)=0.873). 57% of the first year residents smokes cigaret and 54% of them use alcohol. 2% of them gets one day off after hospital night shift, 61% of them suffers from disturbed sleep. 60% of them had been stated that they willingly selected their profession. 61% of them prefers talking to friends and 32% of them prefers shopping to overcome stress. There were statistical difference acording to years of recidency in MBI, Emotional Burnout (EB) and desensitisation scale (DS) points. EB scale points of the second year of residency group was statisticaly higher than fourth year of residency group. DS points of second year of residency group was also statisticaly higher than the third and fourth year of residency group. There was no statistical difference between any groups in Personal Success. BOS is a frequent problem during residency in anaesthesia. Appropriate definition and awareness are the first important steps to prevent this syndrome. Further administrative approaches should be evaluated with regard to their effects.

The "resident's dilemma"? Values and strategies of medical residents for education interactions: a cellular automata simulation.

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Heckerling, P S; Gerber, B S; Weiner, S J

2006-01-01

Medical residents engage in formal and informal education interactions with fellow residents during the working day, and can choose whether to spend time and effort on such interactions. Time and effort spent on such interactions can bring learning and personal satisfaction to residents, but may also delay completion of clinical work. Using hypothetical cases, we assessed the values and strategies of internal medicine residents at one hospital for both cooperative and non-cooperative education interactions with fellow residents. We then used these data and cellular automata models of two-person games to simulate repeated interactions between residents, and to determine which strategies resulted in greatest accrued value. We conducted sensitivity analyses on several model parameters, to test the robustness of dominant strategies to model assumptions. Twenty-nine of the 57 residents (50.9%) valued cooperation more than non-cooperation no matter what the other resident did during the current interaction. Similarly, thirty-six residents (63.2%) endorsed an unconditional always-cooperate strategy no matter what the other resident had done during their previous interaction. In simulations, an always-cooperate strategy accrued more value (776.42 value units) than an aggregate of strategies containing non-cooperation components (675.0 value units, p = 0.052). Only when the probability of strategy errors reached 50%, or when values were re-ordered to match those of a Prisoner's Dilemma, did non-cooperation-based strategies accrue the most value. Cooperation-based values and strategies were most frequent among our residents, and dominated in simulations of repeated education interactions between them.

Text messaging among residents and faculty in a university general surgery residency program: prevalence, purpose, and patient care.

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Shah, Dhruvil R; Galante, Joseph M; Bold, Richard J; Canter, Robert J; Martinez, Steve R

2013-01-01

There is little information about the use of text messaging (texting) devices among resident and faculty physicians for patient-related care (PRC). To determine the prevalence, frequency, purpose, and concerns regarding texting among resident and attending surgeons and to identify factors associated with PRC texting. E-mail survey. University medical center and its affiliated hospitals. Surgery resident and attending staff. Prevalence, frequency, purpose, and concerns regarding patient-related care text messaging. Overall, 73 (65%) surveyed physicians responded, including 45 resident (66%) and 28 attending surgeons (62%). All respondents owned a texting device. Majority of surgery residents (88%) and attendings (71%) texted residents, whereas only 59% of residents and 65% of attendings texted other faculty. Most resident to resident text occurred at a frequency of 3-5 times/d (43%) compared with most attending to resident texts, which occurred 1-2 times/d (33%). Most resident to attending (25%) and attending to attending (30%) texts occurred 1-2 times/d. Among those that texted, PRC was the most frequently reported purpose for resident to resident (46%), resident to attending (64%), attending to resident (82%), and attending to other attending staff (60%) texting. Texting was the most preferred method to communicate about routine PRC (47% of residents vs 44% of attendings). Age (OR: 0.86, 95% CI: 0.79-0.95; p = 0.003), but not sex, specialty/clinical rotation, academic rank, or postgraduate year (PGY) level predicted PRC texting. Most resident and attending staff surveyed utilize texting, mostly for PRC. Texting was preferred for communicating routine PRC information. Our data may facilitate the development of guidelines for the appropriate use of PRC texting. Copyright © 2013 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.