Dissertations / Theses: 'Transfer reaction'

1

Gillespie, Stephen. "Indirect studies of astrophysical reaction rates through transfer reactions." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/16376/.

Full text

Abstract:

The work in this thesis describes two experiments which use transfer reactions to perform spectroscopic studies of nuclei in order to improve reaction rates in astrophysical environments. The first experiment is an indirect study of the 34S(p,γ)35Cl reaction rate at energies relevant to classical novae temperatures. By reducing uncertainties in this reaction it may be possible to use 32S/34S isotopic ratio as a diagnostic tool to determine pre-solar grain paternity. A study of the 34S(3He,d)35Cl transfer reaction was performed to identify energy levels in the astrophysically relevant energy region and assign spin and parity to these new states. A new reaction rate has been calculated from this spectroscopic information and is the first experimental measurement of the 34S(p,γ)35Cl reaction rate. Using this new rate it was concluded that it is now possible to determine the paternity of pre-solar grains using the 32S/34S isotopic ratio. The second experiment measured two proton transfer reactions, (3He,d) and (α,t), with the aim of making spin assignments of states above the neutron threshold in 27Al. Combined with information from complementary experiments this information would be used to calculate new 26Al(n,p/α) reaction rates. Direct comparison of the two transfer reactions should allow for low and high spin states to be identified, however due to lower than expected cross sections useful information could not be extracted from the (α,t) reaction. The experimental resolution was insufficient to resolve individual states with the (3He,d) reaction, however due to the selectivity of the reaction it appears that many of the previously known states show low spin behaviour and are likely not relevant to the reaction rate at astrophysical temperatures. In addition, the non-observation of 23 states known to exist in 27Al may indicate they are high spin and further measurements of these states should be performed in order to calculate new 26Al(n,p/α) reaction rates.

APA, Harvard, Vancouver, ISO, and other styles

2

Duff, Jack Lawrence. "Single electron transfer in nucleophilic reactions of substituted norbornanes." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/27444.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Maza, William Antonio. "Reaction Enthalpy and Volume Profiles for Excited State Reactions Involving Electron Transfer and Proton-Coupled Electron Transfer." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4539.

Full text

Abstract:

Electron transfer, ET, and proton-coupled electron transfer, PCET, reactions are central to biological reactions involving catalysis, energy conversion and energy storage. The movement of electrons and protons in either a sequential or concerted manner are coupled in a series of elementary reaction steps in respiration and photosynthesis to harvest and convert energy consumed in foodstuffs or by absorption of light into high energy chemi-cal bonds in the form of ATP. These electron transfer processes may be modulated by conformational dynamics within the protein matrix or at the protein-protein interface, the energetics of which are still not well understood. Photoacoustic calorimetry is an estab-lished method of obtaining time-resolved reaction enthalpy and volume changes on the nanosecond to microsecond timescale. Photoacoustic calorimetry is used here to probe 1) the energetics and volume changes for ET between the self-assembled anionic uroporphy-rin:cytochrome c complex and the role of the observed volume changes in modulating ET within the complex, 2) the enthalpy and volume change for the excited state PCET reac-tion of a tyramine functionalized ruthenium(II) bis-(2,2'-bipyridine)(4-carboxy-4'-methyl-2,2'-bipyrine) meant to be a model for the tyrosine PCET chemistry carried out by cyto-chrome c oxidase and photosystem II, 3) the enthalpy and volume changes related to car-bon monoxide and tryptophan migration in heme tryptophan catabolic enzyme indoleam-ine 2,3-dioxygenase.

APA, Harvard, Vancouver, ISO, and other styles

4

Serbetcioglu, Serpil. "Mass transfer and catalytic reaction in a three-phase monolith reactor." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332665.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Lekakou, Constantina. "Simulation of flow, reaction and heat transfer in reaction injection moulding." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47048.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Hasegawa, Jun-ya. "Theoretical Study on the Excited States and Electron Transfer Reactions in Photosynthetic Reaction Center." Kyoto University, 1998. http://hdl.handle.net/2433/77871.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Tran, Thu-Trang. "Electron and multielectron reaction characterizations in molecular photosystems by laser flash photolysis, towards energy production by artificial photosynthesis." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS320.

Full text

Abstract:

La demande énergétique de l’humanité augmente rapidement et ne montre aucun signe de ralentissement. Parallèlement à cette problématique, l'utilisation abusive de combustibles fossiles est l'une des principales causes d'augmentation de la concentration de CO₂ dans l'atmosphère. Ces problèmes doivent être résolus en termes de limitation des émissions de CO₂ et de recherche de sources d'énergie renouvelables pour remplacer les combustibles fossiles. De nos jours, l’énergie solaire est l’une des sources d’énergie renouvelables les plus efficaces. La conversion de l'énergie de la lumière solaire en électricité dans le photovoltaïque ou en énergie chimique par le biais de processus photocatalytiques implique invariablement un transfert d'énergie photo-induit et un transfert d'électrons. Dans ce contexte, l'objectif de la thèse est d'étudier les processus photo-induits dans les photosystèmes moléculaires utilisant la photolyse par flash laser. Le premier thème de cette thèse porte sur l’étude du transfert monoélectronique dans des systèmes de dyades donneur-accepteur en vue d’optimiser l’efficacité de la séparation des charges et de son application dans la cellule solaire organique photovoltaïque. Le deuxième thème de cette thèse porte sur l’étude de deux systèmes modèles de photosynthèse artificielle étudiés pour la possibilité d’une accumulation de charge par étapes. Ensuite, différents systèmes photocatalytiques, développés pour la photoréduction du CO₂, ont été étudiés. La compréhension des processus photo-induits devraient permettre l’amélioration de l'efficacité de la réduction du CO₂ dans les systèmes photocatalytiques pratiques
The energy demand of humanity is increasing rapidly, and shows no signs of slowing. Alongside this issue, abuse using fossil fuels is one of the main reasons which leads to an increase in atmospheric CO₂ concentration. These problems have to be solved in terms of both limiting CO₂ emission and finding renewable energy sources to replace fossil fuels. Nowadays, solar energy appears as one of the most effective renewable energy sources. Conversion of solar light energy to electricity in photovoltaics or to chemical energy through photocatalytic processes invariably involves photoinduced energy transfer and electron transfer. In this context, the aim of the thesis focuses on studying photoinduced processes in molecular photosystems using laser flash photolysis. The first theme of this thesis focus on studying single electron transfer in Donor-Acceptor Dyad systems towards optimization efficiency of charge separation and application in the photovoltaic organic solar cell. In the second theme of this thesis, two model systems of artificial photosynthesis were investigated to assess the possibility of stepwise charge accumulation on model molecules. A fairly good global yield of approximately 9% for the two charge accumulation on MV²⁺ molecule was achieved. Then, different photocatalytic systems, which have developed for CO₂ reduction, were studied. Understanding of the photoinduced processes is an important step toward improving the efficiency of reduction of CO₂ in practical photocatalytic systems

APA, Harvard, Vancouver, ISO, and other styles

8

Clower, Caroline Elizabeth. "Proton-transfer dynamics of novel photoexcited hydroxyarenes." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/27858.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Lee, Lester Y. C. "Transmembrane electron transfer in artificial bilayers /." Full text open access at:, 1985. http://content.ohsu.edu/u?/etd,86.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Cooper, Ian Blake. "Photosynthetic water oxidation and proton-coupled electron transfer." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26707.

Full text

Abstract:

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.
Committee Chair: Bridgette Barry; Committee Member: El-Sayed, Mostafa; Committee Member: Fahrni, Christoph; Committee Member: Kröger, Nils; Committee Member: McCarty, Nael. Part of the SMARTech Electronic Thesis and Dissertation Collection.

APA, Harvard, Vancouver, ISO, and other styles

11

Mahmutovic, Anel. "Reaction-Diffusion kinetics of Protein DNA Interactions." Doctoral thesis, Uppsala universitet, Beräknings- och systembiologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-263527.

Full text

Abstract:

Transcription factors need to rapidly find one specific binding site among millions of nonspecific sites on the chromosomal DNA. In this thesis I use various aspects of reaction-diffusion theory to investigate the interaction between proteins and DNA and to explain the searching, finding and binding to specific operator sites. Using molecular dynamics methods we calculate the free energy profile for the model protein LacI as it leaves a nonspecific stretch of DNA and as it slides along DNA. Based on the free energy profiles we estimate the microscopic dissociation rate constant, kdmicro ~1.45×104s-1, and the 1D diffusion coefficient, D1 ~ 0.05-0.29 μm2s-1 (2-40μs to slide 1 basepair (bp)). At a non-atomistic level of detail we estimate the number of microscopic rebindings before a macroscopic dissociation occurs which leads to the macroscopic residence time, τDmacro ~ 48±12ms resulting in a in vitro sliding length estimate of 135-345bp. When we fit the DNA interaction parameters for in vivo conditions to recent single molecule in vivo experiments we conclude that neither hopping nor intersegment transfer contribute to the target search for the LacI dimer, that it appears to bind the specific Osym operator site as soon as it slides into it, and that the sliding length is around 40bp in the cell. The estimated in vivo D1 ~ 0.025 μm2s-1 is higher than expected from estimates of D1 based on viscosity and the atomistic simulations. Surprisingly, we were also forced to conclude that the nonspecific association for the LacI dimer appeared reaction limited which is in conflict with the free energy profile. This inconsistency is resolved by allowing for steric effects. Using reaction-diffusion theory and simulations we show that an apparent reaction limited association can be diffusion limited if geometry and steric effects are taken into account. Furthermore, the simulations show that a protein binds ~2 times faster to a DNA molecule with a helical reactive patch than to a stripe patch running along the length of the DNA. This facilitated binding has a direct impact on the search time especially in the presence of other DNA binding proteins.

APA, Harvard, Vancouver, ISO, and other styles

12

Brunet, Robert A. H. "Silent discharge water treatment, mass transfer and reaction rates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39805.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Beaufils, Florent. "Recent developments in radical-mediated hydrogen atom transfer reaction /." [S.l.] : [s.n.], 2004. http://www.zb.unibe.ch/download/eldiss/04beaufils_f.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Booth, Paula Jane. "Thermodynamics of electron transfer in photosystem 2 reaction centres." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47779.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Wilson, Gleason. "Hydrogen Transfer Reaction Involving Nickel POCOP-Pincer Hydride Complexes." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688935.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Saleh, Nail Asad. "Dynamical solvent effect in 1-(9-anthryl)-3-(4-dimethylaniline) propane charge transfer reactions /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3060138.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Jenson, David L. Jenson. "Proton-coupled electron transfer and tyrosine D of phototsystem II." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29667.

Full text

Abstract:

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.
Committee Chair: Bridgette Barry; Committee Member: Ingeborg Schmidt-Krey; Committee Member: Jake Soper; Committee Member: Nils Kroger; Committee Member: Wendy Kelly. Part of the SMARTech Electronic Thesis and Dissertation Collection.

APA, Harvard, Vancouver, ISO, and other styles

18

Lee, Heung Chan. "Magnetic field effects on electron transfer reactions: heterogeneous photoelectrochemical hydrogen evolution and homogeneous self exchange reaction." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/2562.

Full text

Abstract:

Magnetic field effects (MFE) on electrochemical systems have been of interest to researchers for the past 60 years. MFEs on mass transport, such as magnetohydrodynamics and magnetic field gradients effects are reported, but MFEs on electron transfer kinetics have been rarely investigated. Magnetic modification of electrodes enhances electron transfer kinetics under conditions of high concentrations and low physical diffusion conditions, as shown by Leddy and coworkers. Magnetic microparticles embedded in an ion exchange polymer (e.g., Nafion) applied to electrode surfaces. Rates of electron transfer reactions to diffusing redox probes and to adsorbates are markedly enhanced. This work reports MFEs on hydrogen evolution on illuminated p-Si; MFEs on hydrogen evolution on noncatalytic electrodes; a model for MFEs on homogeneous self-exchange reactions; and a convolution based voltammetric method for film modified electrodes. First, a MFE on the photoelectrochemical hydrogen evolution reaction (HER) at p-Si semiconductors is demonstrated. The HER is an adsorbate reaction. Magnetic modification reduces the energetic cost of the HER by 400 - 500 mV as compared to Nafion modified electrodes and by 1200 mV as compared to unmodified p-Si. Magnetically modified p-Si achieves 6.2 % energy conversion efficiency. Second, from HER on noncatalytic electrodes, the MFE on photoelectrochemical cells arises from improved heterogeneous electron transfer kinetics. On glassy carbon electrodes, magnetic modification improves heterogeneous electron transfer rate constant, k₀,for HER 80,000 fold. Third, self exchange reaction rates are investigated under magnetic modification for various temperatures, outersphere redox probes, and magnetic particles. Arrhenius analyses of the rate constants collected from the experiments show a 30 - 40 % decrease in activation energy at magnetically modified electrodes. A kinetic model is established based on transition state theory. The model includes pre-polarization and electron nuclear spin polarization steps and characterizes a majority of the experimental results. Lastly, a convolution technique for modified with uniform films electrodes is developed and coded in Matlab (mathematical software) for simple and straightforward analysis of Nafion modified electrodes.

APA, Harvard, Vancouver, ISO, and other styles

19

Smith, Dean A. "The demonstration of electron-transfer reactions and their effect on model lignin condensation reactions under alkaline pulping conditions." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/5700.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Ling, Juliette Roseanne. "Enhancement of the interfacial transfer of iodine by chemical reaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29382.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Ishikita, Hiroshi. "Energetics of electron and proton transfer in photosynthetic reaction centers." [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2005/329/index.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Wakeham, Marion Charlotte. "Inactive branch electron transfer in the purple bacterial reaction centre." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400271.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Onuchic, José Nelson Hopfield John J. "New aspects of the theory of electron transfer reaction dynamics /." Diss., Pasadena, Calif. : California Institute of Technology, 1987. http://resolver.caltech.edu/CaltechETD:etd-02242006-162144.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Kirk, Daniel Robert 1975. "Near-wall reaction effects on film-cooled surface heat transfer." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/27047.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, June 2003.
"August 2002."
Includes bibliographical references (p. 73-77).
As commercial and military aircraft engines approach higher total temperatures and increasing overall fuel-to-air ratios, there exists a potential for significant heat release to occur in the turbine if energetic species emitted from the combustor are further oxidized during interaction with film-cooling flows. Currently there is little basis for understanding the effects on aero-performance and durability due to such secondary reactions. To study surface heat flux augmentation due to near-wall reactions, a shock tube experiment was employed to generate short duration, high temperature (1000-2800 K) and pressure (6 atm.) fuel-rich flows over a film-cooled flat plate. The relative increase in surface heat flux due to near-wall reactions was investigated over a range of fuel levels, mass blowing ratios (0.5-2.0), and Damkohler numbers (ratio of flow to chemical time scales) from near zero to 30. It was shown that significant increases in surface heat flux can be produced due to chemical reactions in the film-cooling layer. Under some conditions, the heat flux exceeded that obtained when no film-cooling layer was present on the surface. A numerical tool was developed and showed good agreement with the experimental results for predicting changes in surface heat flux and film effectiveness in the presence of local reactions. Off-surface effects and changes in convective heat transfer coefficient were also evaluated. Realistic turbine and cooling flows were examined to ascertain the robustness of various cooling configurations to near-wall reactions. The result of this work is a set of tools based on a group of parameters that can be used to assess changes in heat load due to near-wall reactions. The non-dimensional parameters are the Damkohler
(cont.) number (Da), mass and momentum blowing ratios (B and I), freestream energetic heat release potential (H*), and scaled heat flux ratio (Qs). The scaled heat flux ratio always increases with Damk6hler number and depends on the structure of the cooling jet, but is not a function of the freestream fuel energy content.
by Daniel Robert Kirk.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

25

Miller, Sylvia C. "Application of proton transfer reaction mass spectrometry to analytical science." Thesis, Open University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664473.

Full text

Abstract:

This work concerns a proton transfer reaction time-of-flight mass spectrometer, PTR-TOF-MS, a bespoke model manufactured by Kore Technology Ltd. for Smiths Detection. This instrument achieves 'soft' ionization of volatile 'organic compounds (VOCs) by proton transfer from protonated water vapour in a reaction chamber at 1 mbar (= 100 Pa). The resulting ions are separated by mass in a field-free time-of-flight tube prior to detection by a multi-channel plate. The instrument was modified to facilitate direct determination of the electric field in the reaction chamber. Sensitivity measurements determined a value of 4-6 counts per second per parts per billion by volume (ncps ppbv·1 ) normalised to 106 H30+. The calibration gas mixture used in this investigation consisted of 14 compounds, (alkylbenzenes and chlorobenzenes) spanning an mlz range of 78 to 180. Each of these was separately investigated over EIN = 90 to 245 Td to establish fragmentation behaviour and possible interfering contributions. For example, several of the alkylbenzenes fragmented to product ions occurring at mlz 79, the same value as that of protonated benzene. Most of this occurred at the higher EIN values with ethylbenzene a notable exception. The isobaric compounds ethyl benzene and the xylenes exhibit very different fragmentation patterns so enabling differentiation of these two compounds. However, it is not possible to distinguish the individual xylene isomers using this method. Benchmarking was continued using the hexenol compounds cis-3-, cis-2-, trans-3- and trans-2- hexen-I-ols. This work demonstrated that the same four product ions are seen for all of the hexenol isomers at mlz 39 (C3H/), 41 (C3H/), 55 (C4H/) and 83 (C6Hl1+) when reacted with H30+ in a PTR-TOF-MS. A characteristic peak at mlz 99 was seen in trans-2-hexen-1-01 and cis- 2-hexen-1-01 at low EINvalues « 140 Td) when the protonated parent ion, mlz 101, is absent. In trans-3-hexen-l-ol and cis-3-hexen-1-01 the MW ion at mlz 101 is seen at these lower EIN values but there is no product ion at mlz 99. This suggests a possible method for distinguishing between the 2- and 3-hexenols. It may also be possible to further identify the individual isomers from the differences in the percentage yield of these product ions.

APA, Harvard, Vancouver, ISO, and other styles

26

Inagaki, Taichi. "Theoretical Study on Mechanism and Dynamics of Hydrogen Transfer Reaction." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/189341.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Quan, Xu. "Hydrogenation, Transfer Hydrogenation and Hydrogen Transfer Reactions Catalyzed by Iridium Complexes." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-119701.

Full text

Abstract:

The work described in this thesis is focused on the development of new bidentate iridium complexes and their applications in the asymmetric reduction of olefins, ketones and imines. Three new types of iridium complexes were synthesized, which included pyridine derived chiral N,P-iridium complexes, achiral NHC complexes and chiral NHC-phosphine complexes. A study of their catalytic applications demonstrated a high efficiency of the N,P-iridium complexes for asymmetric hydrogenation of olefins, with good enantioselectivity. The carbene complexes were found to be very efficient hydrogen transfer mediators capable of abstracting hydrogen from alcohols and subsequently transfer it to other unsaturated bonds. This hydrogen transferring property of the carbene complexes was used in the development of C–C and C–N bond formation reactions via the hydrogen borrowing process. The complexes displayed high catalytic reactivity using 0.5–1.0 mol% of the catalyst and mild reaction conditions. Finally chiral carbene complexes were found to be activated by hydrogen gas. Their corresponding iridium hydride species were able to reduce ketones and imines with high efficiency and enantioselectivity without any additives, base or acid.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Submitted. Paper 6: Manuscript.

APA, Harvard, Vancouver, ISO, and other styles

28

Georgieva, Polina. "Quantum Chemical Modeling of Enzymatic Methyl Transfer Reactions." Doctoral thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9695.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Margerin, Vincent. "Transfer reaction measurements and the stellar nucleosynthesis of 26A1 and 44Ti." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25428.

Full text

Abstract:

Progress in the description of stellar evolution is driven by the collaborative effort of nuclear physics, astrophysics and astronomy. Using those developments, the theory of the origin of elements in the Universe is challenged. This thesis addresses the problem behind the abundance of 44Ti and the origin of 26Al. The mismatch between the predicted abundance of 44Ti as produced by the only sites known to be able to create 44Ti, core collapse supernovae (CCSNe), and the observations, highlight the current uncertainty that exists in the physics of these stars. Several satellite based γ-ray observations of the isotope 44Ti have been reported in recent times and confirm the disagreement. As the amount of this isotope in stellar ejecta is thought to critically depend on the explosion mechanism, the ability to accurately model the observed abundance would be a pivotal step towards validating that theory. The most influential reaction to the amount of 44Ti in supernovae is 44Ti(α, p)47V. Here we report on a direct study of this reaction conducted at the REX-ISOLDE facility, CERN. The experiment was performed at a centre of mass energy 4.15±0.23 MeV, which is, for the first time, well within the Gamow window for core collapse supernovae. The experiment employed a beam of 44Ti extracted from highly irradiated components of the SINQ spallation neutron source of the Paul Scherrer Institute. No yield above background was observed, enabling an upper limit for the rate of this reaction to be determined. This result is below expectation, suggesting that the 44Ti(α, p)47V reaction proceeds more slowly than previously thought. Implications for astrophysical events, and remnant age, are discussed. In Wolf-Rayet and asymptotic giant branch (AGB) stars, the 26gAl(p,γ)27Si reaction is expected to govern the destruction of the cosmic γ-ray emitting nucleus 26Al. The rate of this reaction, however, is highly uncertain due to the unknown properties of several resonances in the temperature regime of hydrogen burning. We present a high-resolution inverse kinematic study of the 26gAl(d, p)27Al reaction as a method for constraining the strengths of key astrophysical resonances in the 26gAl(p,γ)27Si reaction. In particular, the results indicate that the resonance at Er = 127 keV in 27Si determines the entire 26gAl(p, γ)27Si reaction rate over almost the complete temperature range of Wolf-Rayet stars and AGB stars. The measurements of spectroscopic factors for many states in 27Al and a shell model calculation of nuclear properties of rp-resonant states in 27Si also allow for testing the structure model.

APA, Harvard, Vancouver, ISO, and other styles

30

Tervasmäki, P. (Petri). "Reaction and mass transfer kinetics in multiphase bioreactors:experimental and modelling studies." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526220390.

Full text

Abstract:

Abstract In the sugar platform of biorefining, the complex polymeric structure of lignocellulose biomass is degraded into sugars, which are utilized by microbial cells in the further processing steps. The reaction steps in both biomass degradation and microbial fermentation processes involve multiphase reactions in which mass transfer and reaction kinetics often play a key role. The aim of this thesis is to characterize the effect of these conditions on enzymatic hydrolysis of cellulose and utilization of sugars by aerobic microbes. These types of liquid-solid (cellulose hydrolysis) and liquid-gas (microbial cultivation) systems are typically very demanding on the reactors that are used in the process. By the fed-batch process utilized in this work, sufficient mixing in enzymatic hydrolysis of cellulose is achieved even with high final substrate concentration. One of the main outcomes of this work is the kinetic model that concentrates on the kinetics of fed-batch process by discretizing the substrate into subpopulations. By using this approach, the model parameters were identified in an adequate manner, and the poorly identified parameters could be sorted out. Parameter identifiability has been an issue in previous models for enzymatic hydrolysis of cellulose. Based on the experiments and modelling studies, it can be concluded that the enzymes remain intact for time scales relevant for the hydrolysis process. Thus, the decrease in the hydrolysis rate found in many literature studies is probably mostly due to substrate-enzyme interactions rather than denaturation of the enzyme. In aerobic cell cultivations, the mixing and mass transfer conditions are often more critical for the process performance. In this work, we studied the performance and suitability of alternative reactor types to be used in aerobic cell cultivations and obtained some promising results. In addition, the thesis presents a modelling approach to study the effect of process conditions on metabolism and growth rate of Pichia pastoris yeast. The model combines a kinetic model for yeast growth and a model for the mixing and mass transfer conditions in stirred tank reactor
Tiivistelmä Biojalostuksen sokerialustassa lignoselluloosapohjaisen biomassan monimutkaista polymeerirakennetta muokataan ja sieltä vapautetaan monomeerisia sokereita, joita voidaan edelleen hyödyntää jatkojalostuksessa. Monet jatkojalostusprosessit käyttävät mikrobeja, joiden aineenvaihdunnassa sokereita voidaan jalostaa arvokkaammiksi tuotteiksi ns. fermentointiprosesseissa. Tämän väitöstyön tarkoitus on tutkia reaktio- ja aineensiirtokinetiikan vaikutusta selluloosan entsymaattiseen hydrolyysiin ja aerobisiin mikrobifermentointeihin. Näistä ensimmäinen on neste-kiintoainesysteemi ja jälkimmäinen neste-kaasusysteemi, ja tällaiset prosessit asettavat tyypillisesti merkittäviä vaatimuksia niissä käytettäville reaktoreille. Tässä työssä hyödynnettiin kiinteän raaka-aineen vähittäistä syöttöä (ns. fed-batch prosessi) selluloosan hydrolyysissä, jolloin sekoitus voidaan pitää riittävänä suurillakin kiintoainemäärillä. Työn merkittävin tuotos on kineettinen malli, jossa hyödynnetään fed-batch prosessia ja koedataa osittamalla mallinnusyhtälöt raaka-aineen syöttöajan perusteella. Tällä tavalla mallin parametrit saatiin identifioitua kohtuullisella tarkkuudella sekä eriteltyä huonosti identifioituneet parametrit. Mallin parametrien identifiointi on ollut ongelmallista monissa vastaavan tyyppisissä malleissa aiemmin. Kokeiden ja mallinnustulosten perusteella voidaan sanoa, että hydrolyysissä käytettävät entsyymit pysyvät aktiivisina prosessin aikana, ja usein todettu hydrolyysin hidastuminen johtuu ennemmin kiinteän kuidun ja entsyymien vuorovaikutuksen muutoksista kuin entsyymin denaturoitumisesta. Aerobisiin mikrobikasvatuksiin liittyen tässä työssä tutkittiin vaihtoehtoisten reaktorityyppien hyödyntämistä, joista saatiin myös lupaavia tuloksia. Lisäksi työssä kehitettiin mallinnustyökaluja, joilla voidaan tutkia prosessiolosuhteiden vaikutusta Pichia pastoris –hiivan metaboliaan ja kasvunopeuteen. Mallissa yhdistetään hiivan kasvun kineettinen malli sekä reaktoriolosuhteiden mallinnus

APA, Harvard, Vancouver, ISO, and other styles

31

Georgiadou, Anastasia. "Transfer Reactions Induced with 56Ni : Pairing and N=28 Shell Closure." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS294/document.

Full text

Abstract:

La structure du noyau N = Z doublement magique 56Ni (N = 28, Z = 28) a été étudiée en mesurant les réactions de transfert á un et deux nucléons. Le transfert nous donne des informations sur deux aspects physiques différents: la fermeture de couche N=28 et l’intensité de l’appariement neutron-proton. Le nombre magique N=28 est particulier, car c’est le premier créé par le spin-orbit. La double magicité permet la détermination de la nature de particule indépendante des voisins N±1 par réaction de transfert d’un nucléon. De plus, en tant que noyau N=Z a couches fermeés, le 56Ni est un noyau clé pour l’étude de l’apparement np dans la plus grande couche accessible expérimentalement. L’apparement np se manifeste dans le canal isoscalaire (T=0) et isovecteur (T=1). L’intensité relative de chaque canal révèle la nature collective des états. L’expérience de ce travail a eu lieu au GANIL-Caen, en France, avec un faisceau radioactif de 56Ni á 30MeV / u produit par frag- mentation de 58Ni et purification avec le spectromètreLISE. Les mesures ont été effectuées en cinématique inverse sur des cibles CH2 et CD2. Les détecteurs MUST2 et TIARA ont été utilisés pour la détection de éjectiles légers et couvraient presque 4π. En outre, quatre détecteurs germanium d’EXOGAM ont été utilisés pour les coïncidences de particules-gamma afin d’identifier l’état peuplé du résidu de réaction. Pour étudier le gap de N=28, nous étudions la spectroscopie du 55Ni par les réactions de transfert de nucléons (d, t) et (p, d) sur le 56Ni. Le spectre en énergie d’excitation est déduit de la mesure des éjectiles légers seulement. Ensuite,les coincidences particule-gamma sont utilisées pour améliorer la résolution et identifier les principaux états peuplés. La comparaison des distributions angulaires ainsi obtenues avec des calculs DWBA permet d’extraire les facteurs spectroscopiques pour les états de particules et de trous ainsi peuplés. En ce qui concerne l’appariement np, nous avons analysé la réaction 56Ni(d,α)54Co qui réalise un transfert de paires neutron-proton. Un affaiblissement du canal T=0 á cause de l’effet du spin-orbite est attendu. La sélectivité en ∆T=0 de la réaction (d, α) permet d’étudier plus en détail le canal isoscalaire T = 0
The structure of the unstable doubly ma- gic nucleus 56Ni has been investigated by measuring one- and two-nucleon transfer reactions. Each trans- fer reaction provides information for two different physical aspects: the robustness of the N=28 shell gap and the strength of the neutron-proton pairing. 56Ni is a self-conjugate doubly magic nucleus with N=28 and Z=28. The magic number 28 is a peculiar shell closure created by spin-orbit splitting effects. The double magicity makes the determination of the single-particle nature of their N±1 neighbors by one-neutron transfer reaction of major interest to test both the robustness of shell closures as well as the evolution of particle and/or valence orbitals. Moreover 56Ni, as a N=Z nucleus with fully closed shells, is a key nucleus to investigate neutron-proton pairing in the largest shell accessible experimentally, the fp shell. Neutron-proton pairing can occur both in the isoscalar (T=0) and in the isovector (T=1) channels. The relative intensity of both channels reveals the collective nature of the states. The radioactive beam of 56Ni was produced at GANIL-Caen, France at 30 MeV/u by fragmentation of 58Ni and purification with the LISE spectrometer. The experimental set-up used, consists of the TIARA- MUST2-EXOGAM combination which provides an al- most 4π coverage and the ability to perform particle- γ coincidences. To probe the N=28 gap, we studied the spectroscopy of 55Ni through one-nucleon trans- fer reactions on 56Ni. The excitation energy spectrum is deduced by measuring the light ejectiles only, while particle-γ coincidences are used to improve the re- solution of the populated states and select the main ones. Comparison in between the extracted angular distributions and DWBA calculations allow the extraction of the spectroscopic strength of the hole- and particle- states populated by these one neutron pick- up reactions. As for neutron-proton pairing, a weakening of the strength is expected in the T=0 channel from previous results. The selectivity in ∆T=0 of the 56Ni(d,α)54Co reaction enables further investigation of the isoscalar channel contribution

APA, Harvard, Vancouver, ISO, and other styles

32

Coetsee, Theresa. "Non-isothermal reaction of iron ore-coal mixtures." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-07092008-142912/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Sun, Xiao-Jing. "The extent and importance of single electron transfers in organic reactions." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27981.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Panda, Kishora Kumar. "Ozone mass transfer and reaction in In situ and stirred tank reactors /." Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Ramström, Eva. "Mass transfer and slag-metal reaction in ladle refining : a CFD approach." Licentiate thesis, Stockholm : KTH, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11864.

Full text

Abstract:

In order to optimise the ladle treatment mass transfer modelling of aluminium addition and homogenisation time was carried out. It was stressed that incorporating slag-metal reactions into the mass transfer modelling strongly would enhance the reliability and amount of information to be analyzed from the CFD calculations.

In the present work, a thermodynamic model taking all the involved slag metal reactions into consideration was incorporated into a 2-D fluid flow model of an argon stirred ladle. Both thermodynamic constraints and mass balance were considered. The activities of the oxide components in the slag phase were described using the thermodynamic model by Björkvall and the liquid metal using the dilute solution model. Desulphurization was simulated using the sulphide capacity model developed by KTH group. A 2-D fluid flow model considering the slag, steel and argon phases was adopted.

The model predictions were compared with industrial data and the agreement was found quite satisfactory. The promising model calculation would encourage new CFD simulation of 3-D along this direction.

APA, Harvard, Vancouver, ISO, and other styles

36

Jäckl, Magnus [Verfasser]. "Structural characterization of reaction intermediates of HECT-mediated ubiquitin transfer / Magnus Jäckl." Tübingen : Universitätsbibliothek Tübingen, 2020. http://d-nb.info/1222510588/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Thompson, Neil Graham. "Analysis of the C-12(e,e'pd) reaction at high energy transfer." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2465/.

Full text

Abstract:

The Jefferson Lab Hall A experiment E01015 measured the differential cross sections of the C-12(e,e'pd) reaction with low yields for kinematics of omega=0.865 GeV, Q^2=2 (GeV/c)^2, Bjorken x=1.2 at three kinematic settings of C-12(e,e'p) missing momentum of 300, 400 and 500 MeV/c. The main objective of the experiment was to measure the C-12(e,e'p) cross section and the cross section ratios of C-12(e,e'pp) and C-12(e,e'pn) to investigate Short Range Correlations. The C-12(e,e'pd) reaction was investigated to find out what its magnitude of cross section. The very low yields and differential cross sections of C-12(e,e'pd) reaction measured at the three different kinematic settings suggests that the contribution of many of the different reaction mechanisms, including three nucleon forces, may be suppressed at the kinematics of this experiment.

APA, Harvard, Vancouver, ISO, and other styles

38

Chuang, Jessica I.-Jane. "Understanding unidirectional electron transfer in the photosynthetic reaction center using protein engineering /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Balabin, Ilya A. "Structural and dynamical control of the reaction rate in protein electron transfer /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9938586.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Milanes, David Wade 1979. "Near wall reaction effects on film-cooled backward-facing step heat transfer." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/82769.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Trevino, Lisandro. "Mold Filling Analysis of Structural Reaction Injection Molding and Resin Transfer Molding." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392736921.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Widmann, John F. "Chemical reaction and thermodynamic studies of microparticles using electrodynamic balances /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9873.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Adekola, Aderemi S. "Proton-transfer study of unbound ¹⁹Ne states via ²H(¹⁸F,[alpha]¹⁵O)n REACTION." Ohio : Ohio University, 2009. http://www.ohiolink.edu/etd/view.cgi?ohiou1230079038.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Singh, Pradyumna Shaakuntal. "The Electrochemical Reduction of Superoxide in Acetonitrile: A Concerted Proton-Coupled Electron Transfer (PCET) Reaction." Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/194763.

Full text

Abstract:

Superoxide, the product of the one-electron reduction of dioxygen, is a molecule of enormous importance. It participates in a variety of critical physiological processes and is also an important component of fuel cells where it is an intermediate in the cathodic reaction. However, the electrochemical behavior of superoxide, mainly its reduction, is not well understood. Here, the electrochemical behavior of superoxide has been investigated in acetonitrile on glassy carbon electrodes, through cyclic voltammetry experiments. By stabilizing the electrogenerated superoxide, aprotic solvents afford an opportunity to study its electrochemical reactions further. Superoxide was generated electrochemically from dioxygen at the first voltammetric peak. In the presence of hydrogen-bond donors (water, methanol, 2-propanol), the superoxide forms a complex with the donor resulting in a positive shift in the formal potential which can be analyzed to obtain formation constants for these complexes. Stronger acids (2,2,2- trifluoroethanol, 4-tert-butylphenol) result in protonation of superoxide followed by reduction to produce HO₂-. On scanning to more negative potentials a second peak is observed which is irreversible and extremely drawn out along the potential axis indicating a small value of the transfer coefficient α. Addition of hydrogenbond donors, HA, brings about a positive shift in this peak, without a noticeable change in shape. The reaction occurring at the second peak is a concerted proton-coupled electron transfer (PCET) in which the electron is transferred to superoxide and a proton is transferred from HA to superoxide forming HO₂- and A- in a concerted process. We estimate the standard potential for this reaction for the case of water as the donor. This value suggests that the reaction at the second peak occurs at very high driving forces. Kinetic simulations using both Butler-Volmer and Marcusian schemes were performed to estimate the kinetic parameters. The unusually low rate constants obtained suggest high nonadiabaticity for this PCET reaction. The reaction was also found to proceed with an unusually large reorganization energy. Consistent with a PCET, a kinetic isotope effect, HA vs. DA, was detected for the three hydrogen-bond donors.

APA, Harvard, Vancouver, ISO, and other styles

45

McCoskey, Jacob K. "Sample dehumidification to enhance formaldehyde detection by a proton transfer reaction mass spectrometer." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Summer2009/J_McCoskey_072109.pdf.

Full text

Abstract:

Thesis (M.S. in environmental engineering)--Washington State University, August 2009.
Title from PDF title page (viewed on Aug. 7, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 73-76).

APA, Harvard, Vancouver, ISO, and other styles

46

Wang, Yueming. "Ionic liquids and iridium hydrogen transfer catalysts for the reaction of renewable alcohols." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709855.

Full text

Abstract:

This thesis is about the study of developing novel catalysts and catalytic processes and applying them to convert renewable alcohols produced from biomass into value-added chemicals. It focuses on developing iridium catalysts for hydrogen transfer initiated dehydration of 1,3- propanediol in ionic liquids as solvent and applying functionalized ionic liquids as homo- and heterogeneous catalysts for dehydration of D-sorbitol and rac-1-phenylethanol respectively.

APA, Harvard, Vancouver, ISO, and other styles

47

Sai, Masahiro. "Metal-Catalyzed Allyl-, Allenyl-, Propargyl-Transfer Reaction and Its Application to Functional Materials." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157600.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Kometani, Noritsugu. "High Pressure Studies of Solvation Effect on Intramolecular Charge-Transfer Reaction in Alcohols." 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/202450.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Gunawardhana, Kihanduwage N. Gipson Stephen L. "Chemistry, electrochemistry and electron transfer induced reactions of cobalt complexes with fluorinated ligands." Waco, Tex. : Baylor University, 2007. http://hdl.handle.net/2104/5114.

Full text

Abstract:

Thesis (Ph.D.)--Baylor University, 2007.
In the abstract "CF3COCo(CO)3PPh3, CF3, Bu3SnH, CF3H, [Co(CO)4]-, [Co(CO)3(PPh3)]-, C2F4, C6F5Co(CO)3PPh3, C6F5, C6F5H, C6F5D, CF3COCo(CO)3PPh3, and Co-C(acyl)" are subscript. Includes bibliographical references (p. 205-213).

APA, Harvard, Vancouver, ISO, and other styles

50

Patil, Shradha Vasant. "Radical additions of hydrocarbons, ethers and acetals to alkenes via allyl transfer reaction: A new chain reaction for C-H bond functionalization." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50658.

Full text

Abstract:

Functionalization of hydrocarbons via a free-radical based allyl transfer reaction using various allyl bromide substrates has been previously studied. The work described in this dissertation focuses on the replacement of Br by phthalimido-N-oxyl (PINO ) which helps make this chemistry environmentally friendly. To replace Br with PINO , replacement of previously used allyl-bromide substrates with new allyl-PINO substrates were necessary. Various allyl- PINO compounds were synthesized and the use of these allyl-phthalimido-N-oxyl (allyl-PINO) compounds for the functionalization of various alkyl aromatic hydrocarbons is demonstrated.
Kinetic studies were performed to observe the efficiency of the new chain reaction compared to the previously reported studies with allyl-bromides. We recently discovered that these allyl substrates are useful for the functionalization of ethers and acetals. The functionalization of various cyclic and acyclic ethers was performed using these allyl transfer reactions. This reaction was also performed in-solution, which allowed us to perform these reactions at low reagent concentrations. Kinetic chain lengths were measured for these reactions. High chain lengths were observed for all used ethers. Kinetic studies to investigate the rate of radical addition-elimination processes were performed using laser flash photolysis and competition kinetics. These experiments helped us to measure the reactivity and selectivity of PINO as a chain carrier in comparison with Br .
Additionally, a new competition experiment was designed to study the relative rate constant for
the 􀈕-fragmentation process. For this experiment a novel substrate that contains two leaving
groups, Br and PINO , was synthesized, and the relative rates of elimination of Br vs PINO
were compared.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Transfer reaction'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles