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Academic literature on the topic 'Reaction Mechanism - Theoretical Study'

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Published: 7 September 2023

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Journal articles on the topic "Reaction Mechanism - Theoretical Study"

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Wang, Zhi-Xiang, Ming-Bao Huang., and Ruo-Zhuang Liu. "Theoretical study on the insertion reaction of CH(X2Π) with CH4." Canadian Journal of Chemistry 75, no. 7 (July 1, 1997): 996–1001. http://dx.doi.org/10.1139/v97-119.

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The CH + CH4 reaction has been studied by means of ab initio molecular orbital calculations incorporating electron correlation with Møller–Plesset perturbation theory up to second and fourth orders with the 6-31G(d,p) and 6-311++G(2d,p) basis sets. An energetically feasible insertion reaction path has been found in the potential energy surface that confirms the experimental proposal for the mechanism of the CH + CH4 reaction. The feature of the mechanism for the CH + CH4 insertion reaction is found to be different from the feature of the mechanisms for the CH + NH3, CH + H2O, and CH + HF insertion reactions, but somewhat similar to that for the CH2 + CH4 insertion reaction. Energetic results for the CH + CH4 reactions are in agreement with experiment. Keywords: CH radical, methane, reaction mechanism.
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Chen, Shi-Lu, Wei-Hai Fang, and Fahmi Himo. "Theoretical Study of the Phosphotriesterase Reaction Mechanism." Journal of Physical Chemistry B 111, no. 6 (February 2007): 1253–55. http://dx.doi.org/10.1021/jp068500n.

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Himo, Fahmi, Jing-Dong Guo, Agnes Rinaldo-Matthis, and Pär Nordlund. "Reaction Mechanism of Deoxyribonucleotidase: A Theoretical Study." Journal of Physical Chemistry B 109, no. 42 (October 2005): 20004–8. http://dx.doi.org/10.1021/jp0546150.

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Suhail, Mohammad, Sofi Danish Mukhtar, Imran Ali, Ariba Ansari, and Saiyam Arora. "Theoretical DFT study of Cannizzaro reaction mechanism: A mini perspective." European Journal of Chemistry 11, no. 2 (June 30, 2020): 139–44. http://dx.doi.org/10.5155/eurjchem.11.2.139-144.1975.

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In regards to the Cannizzaro reaction and its peculiar mechanism, some researchers have presented a free radical mechanism for the Cannizzaro reaction, while others have found that it is feasible through an ionic mechanism, but the actual mechanism has not been finalized yet. The researchers have given the proof of both the mechanisms through their papers published. Actually, Cannizzaro reaction may occur through both mechanisms depending on both molecular structure and different conditions which are yet to be explained. Recently published papers describe that free radical mechanism occurs only in a heterogeneous medium, while an ionic mechanism occurs in a homogeneous medium. We revealed no explanation of the molecular structure-based reason, responsible for a radical or an ionic mechanism. The present paper reviews not only homogeneous/heterogeneous medium conditions but also molecular structure-based facts, which may be responsible for the Cannizzaro reaction to occur through the radical or ionic mechanism, and that may be acceptable to the scientific society. Besides, Density Functional Theory study using Gaussian software was also involved in the explanation of the molecular structure, responsible for one of the two mechanisms. Also, the present paper specifies all points related to future perspectives on which additional studies are required to understand the actual mechanism with a definite molecular structure in the different reaction media.
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Amano, Tatsuo, Noriaki Ochi, Hirofumi Sato, and Shigeyoshi Sakaki. "Oxidation Reaction by Xanthine Oxidase. Theoretical Study of Reaction Mechanism." Journal of the American Chemical Society 129, no. 26 (July 2007): 8131–38. http://dx.doi.org/10.1021/ja068584d.

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YU, LINGJUAN, DACHENG FENG, MAOXIA HE, RUI LI, and ZHENGTING CAI. "THEORETICAL STUDY ON HYDROLYSIS MECHANISM OF β-PHOSPHOLACTAMS." Journal of Theoretical and Computational Chemistry 05, spec01 (January 2006): 421–31. http://dx.doi.org/10.1142/s0219633606002362.

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The neutral hydrolysis mechanisms of a simple β-phospholactam with and without water-assisted reaction have been studied by using quantum chemical method at HF/6-31G**, MP2/6-31G** and B3LYP/6-31G** levels, respectively. The reaction can proceed by two different mechanisms: concerted and stepwise. There are two pathways in stepwise, i.e. pathway a and b, and the energy barriers of them are close. The energy barriers of water-assisted hydrolysis of β-phospholactam are obviously lower than those of no-water-assisted hydrolysis system. The energy barriers of stepwise mechanism are much lower than those of the concerted pathway in both cases. The solvent effects have been considered by means of a polarizable continuum model. The hydrolysis mechanism of β-phospholactam with that of the β-lactam and β-sultam was compared.
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Wu, Nan-Nan, Shun-li OuYang, and Liang Li. "Theoretical Study of C2H5 + NCO Reaction: Mechanism and Kinetics." Journal of Chemistry 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/3036791.

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Theoretical investigations are performed on mechanism and kinetics of the reactions of ethyl radical C2H5 with NCO radical. The electronic structure information of the PES is obtained at the B3LYP/6-311++G(d,p) level of theory, and the single-point energies are refined by the CCSD(T)/6-311+G(3df,2p) level of theory. The rate constants for various product channels of the reaction in the temperature range of 200–2000 K are predicted by performing VTST and RRKM calculations. The calculated results show that both the N and O atoms of the NCO radical can attack the C atom of C2H5 via a barrierless addition mechanism to form two energy-rich intermediates IM1 C2H5NCO (89.1 kcal/mol) and IM2 C2H5OCN (64.7 kcal/mol) on the singlet PES. Then they both dissociate to produce bimolecular products P1 C2H4 + HOCN and P2 C2H4 + HNCO. At high temperatures or low pressures, the reaction channel leading to bimolecular product P2 is dominant and the channel leading to P1 is the secondary, while, at low temperatures and high pressures, the collisional stabilization of the intermediate plays an important role and as a result IM2 becomes the primary product. The present results will enrich our understanding of the chemistry of the NCO radical in combustion processes.
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Ishikawa, Ryo, Yasuko Y. Maruo, Keiji Kobayashi, and Hiroyuki Teramae. "Theoretical Study on Reaction Mechanism ofLutidine Derivative Formation." Journal of Computer Chemistry, Japan 14, no. 2 (2015): 30–35. http://dx.doi.org/10.2477/jccj.2015-0006.

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Li, Yan, Hui-ling Liu, Xu-ri Huang, Dequan Wang, Chia-chung Sun, and Au-chin Tang. "Reaction Mechanism of HCN++ C2H4: A Theoretical Study." Journal of Physical Chemistry A 112, no. 47 (November 27, 2008): 12252–62. http://dx.doi.org/10.1021/jp805285p.

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Tan, Wei, Tian-jing He, Fan-chen Liu, and Dong-ming Chen. "Theoretical Study on Mechanism of C5H7 +O2 Reaction." Chinese Journal of Chemical Physics 20, no. 3 (June 2007): 249–57. http://dx.doi.org/10.1088/1674-0068/20/03/249-257.

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Dissertations / Theses on the topic "Reaction Mechanism - Theoretical Study"

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Markovi, Z., JP Engelbrecht, and S. Markovi. "Theoretical Study of the Kolbe-Schmitt Reaction Mechanism." A Journal of Chemical Sciences, 2002. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1002008.

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Abstract A theoretical study of the Kolbe-Schmitt reaction mechanism, performed using a DFT method, reveals that the reaction between sodium phenoxide and carbon dioxide proceedswith the formation of three transition states and three intermediates. In the first step of the reaction, a polarized ONa bond of sodium phenoxide is attacked by the carbon dioxide molecule, and the intermediate NaPh-CO2 complex is formed. In the next step of the reaction the electrophilic carbon atom attacks the ring primarily at the ortho position, thus forming two new intermediates. The final product, sodium salicylate, is formed by a 1,3-proton shift from C to O atom. The mechanism agrees with the experimental data related to the Kolbe-Schmitt reaction.
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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.

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Pérez, Gallegos Ayax. "Theoretical study on the mechanism of the reaction catalyzed by protein kinase." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/386487.

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Malgrat el gran nombre d’estudis experimentals i computacionals sobre l’estructura i funció de les proteïnes quinases, els detalls exactes dels canvis estructurals i mecanístics dels passos individuals de la reacció catalítica de transferència del grup fosforil romanen incerts. En principi, els estudis computacionals poden subministrar informació minuciosa i una coneixença complementària al treball experimental, però aquest objectiu només es pot assolir si es fan servir els mètodes computacionals adequats i si el model teòric que s’utilitza representa correctament el sistema biològic. En aquesta Tesi, el mètode QM/MM a nivell DFT/MM s’ha utilitzat per a descriure els diferents mecanismes de reacció sobre la hipersuperfície d’energia potencial de la reacció global de transferència del grup fosforil catalitzada per la Proteïna Quinasa A (PKA). Cal destacar, que a més d’utilitzar models complets i solvatats del sistema biomolecular i nivells de teoria més alts que en treballs anteriors, s’han fet servir també diferents tècniques i algoritmes inclosos en el codi ChemShell, a fi de millorar els càlculs dels camins de reacció i les optimitzacions d’estats estacionaris. En particular, coordenades de reacció més flexibles i el mètode microiteratiu per a localitzar estructures d’estats de transició ens han permès aplicar una metodologia multiescala consistent i fiable per a analitzar minuciosament tant el mecanisme associatiu (que implica la transferència de fosforil simultàniament amb la protonació del grup fosfat transferit) com el dissociatiu (que implica dues etapes: la transferència de fosforil i la protonació del substrat fosforilat) de la reacció de transferència de fosforil catalitzada per la PKA. S’ha prestat especial atenció a les funcions específiques dels residus Asp166, Lys168 i Thr201, al Gly-rich loop, als ions metàl·lics, i a la conformació i l’estat de protonació al llarg de la reacció química de la cadena lateral del substrat i del fosfat que es transfereix. Els resultats d’aquesta Tesi han demostrat que la reacció catalitzada per la PKA no depèn del substrat i que el mecanisme dissociatiu és clarament favorable respecte el mecanisme associatiu. No obstant, els càlculs presentats també mostren que el mecanisme associatiu seria viable quan el dissociatiu està impedit, com amb el mutant D166A. Aquest punt reobre un debat sobre la viabilitat del mecanisme associatiu que semblava superat donat els darrers estudis teòrics. A més a més, els camins de reacció per a la retro-protonació del substrat fosforilat per part del residu Asp166 s’han localitzat, demostrant que Asp166 es comporta com un catalitzador àcid/base general al llarg del mecanisme dissociatiu. Per altra banda, els perfils d’energia potencial QM/MM calculats també demostren, per primera vegada, que la reacció catalítica de transferència de fosforil és viable amb ions metàl·lics alcalinoterris diferents del Mg2+, confirmant resultats experimentals recents que proposen el paper fisiològic del Ca2+ a l’activitat de les quinases. Tant pel mecanisme associatiu com pel dissociatiu, la localització precisa i l’orientació de la triada Asp166-Lys168-Thr201 i de la xarxa de ponts d’hidrogen que aquests residus estableixen al centre actiu, s’ha vist que són essencials per a la catàlisi i especialment per a l’estabilització de les estructures dels estats de transició involucrats. Finalment, els resultats d’aquesta Tesi han proveït amb una seqüència completa de l’evolució geomètrica de l’estructura del complex ternari al llarg de la reacció catalítica. Això permet una comparació acurada amb les estructures de raigs-X cristal·logràfiques que han estat proposades experimentalment com a imatges moleculars del procés catalític de fosforilació. En particular, el bon acord entre les estructures teòriques i els estudis experimentals validen la visió atòmica de la reacció presentada en aquesta Tesi, revelant canvis conformacionals, de coordinació i dels ponts d’hidrogen que tenen lloc durant la recció química i la seva relació amb la dinàmica de l’enzim.
Despite extensive experimental and computational studies about the structure and function of kinases, exact details regarding the complex structural changes and the mechanistic details of individual stages involved in the catalyzed phosphoryl-transfer reaction remain uncertain. In principle, computational studies can provide detailed information and insights to complement experimental studies, but this goal can only be attained when the appropriate computational approaches are employed and the theoretical model used is a good mimic of the biological system. In this Thesis, the QM/MM approach at the DFT/MM level of theory was used to describe the different reaction mechanisms on the potential energy hypersurface of the global phosphoryl-transfer reaction catalyzed by the Protein Kinase A (PKA). Remarkably, besides making use of more complete solvated models of the biomolecular system and higher levels of theory than the ones employed in previous works, several techniques and algorithms within the computational chemistry suite ChemShell were used to improve the accuracy of the reaction path calculations and stationary points optimizations. In particular, more flexible reaction coordinates, the location of the stationary points with the hybrid delocalized internal coordinates, and the microiterative method to locate transition structures allowed us to apply a consistent and reliable multiscale methodology to examine minutely both the associative (involving a concomitant phosphoryl-transfer and protonation of transferred phosphate) and dissociative (involving two steps: phosphoryl-transfer and back protonation of the phosphorylated substrate) mechanisms of the phosphoryl-transfer reaction catalyzed by PKA. Special attention was paid in the specific roles of the invariant residues Asp166, Lys168, and Thr201, the conserved Gly-rich loop, the metal ions, and the conformation and protonation state of the substrate residue side chain and transferred phosphate along the chemical reaction. The results in this Thesis demonstrate that the catalytic reaction catalyzed by PKA is not substrate-dependent and that the dissociative mechanism is clearly more favorable than the associative one. Nevertheless, the presented calculations also show the plausibility of the associative reaction pathway when the dissociative counterpart is impeded as it is in the D166A mutant. This reopens the debate about the plausibility of the associative reaction pathway that in view of the last theoretical works in the field seemed to be overcame. Moreover, the reaction paths for the back protonation of the phosphorylated substrate by Asp166 have been located, so demonstrating that Asp166 behaves as a general acid/base catalyst along the dissociative mechanism. In addition, QM/MM potential energy profiles determined in this Thesis also demonstrate, for the first time, that the catalyzed phosphoryl-transfer is plausible with alkali earth metal ions other than Mg2+ ions, what confirms recent experimental results where the physiological role of Ca2+ in kinase activity has been proposed. For both the associative and the dissociative mechanisms, the precise location and orientation of the triad Asp166-Lys168-Thr201 and the hydrogen bond network these residues establish within the active site are shown to be essential for catalysis, particularly in the stabilization of the transition state structures involved. Lastly, the results in this Thesis provide a complete sequence of the geometrical evolution of the structure of the ternary complex along the catalytic reaction. This permits an accurate comparison with new X-ray crystallographic structures that have been suggested as experimental snapshots of the catalyzed-phosphorylation process In particular, the good agreement between the theoretically determined structures and the crystallographic studies validate the atomic view of the reaction presented in this Thesis, thus revealing conformational, coordination, and hydrogen bond changes that occur during the chemical step and its relation with the enzyme dynamics.
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Moagi, Kgotso Herbet. "Reaction Mechanism of 2-monosubstituted Quinoxalines with Organolithium Compounds : a Theoretical Study." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/75182.

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This dissertation describes the density functional theory (DFT) computational modelling of reactions between organolithium nucleophiles and various substituted quinoxalines. These reactions result in the functionalisation of the C (sp2)–H bond, thus substituting the sigma-hydrogen. The reactions are known as nucleophilic substitution of hydrogen (SNH) and are used by experimental chemists to form new C–C bonds. The SNH reactions are very important in various industries, e.g. in designing and manufacturing of pharmaceuticals. Quinoxaline is widely used in medicinal chemistry due to its various biological activities; these reactions play a crucial role in the synthesis of new classes of compounds. The reactions of 2-phenyl- (A), 2-butyl- (B), and 6-nitro-2-phenyl- (C) quinoxaline with lithiofuran (a) and lithiothiophene (b) involves a direct (1) nucleophilic attack on an activated electron-deficient system, leading to the intermediate sigma^H-complex. This is followed by hydrolysis (2), where an sp2-type nitrogen is changed to an sp3 while forming Li---OH as a by-product. The presence of Li---OH then allows the departure of an sigma-proton via oxidation reaction, concomitantly forming H2O2 as the second by-product. All approaches to functionalise the C(sp2)–H bond involve elimination of a proton, and an oxidant is needed for the departure of the sigma-hydrogen. Although the sequence of steps and mechanisms of these C–H transformations are the same, various factors have shown to affect the reactions differently. The theoretical study of this catalytic-free transformation, shows that the formation of sigma^H-adducts is not easily reversible, and that their formation is spontaneous. The reaction does not just require an oxidant to eliminate the sigma-hydrogen with the pair of electrons, but rather requires the presence of water for hydrolysis prior to oxidation. We must stress the crucial role of the oxidant since the key problem of the SNH reactions is associated with the elimination of sigma-hydrogen. However, the main objective of this study is to present a correct and complete mechanistic picture of oxidative nucleophilic substitution of hydrogen (ONSH). Previous reports indicated that the presence of an electron donating/withdrawing group on the quinoxaline ring had a significant influence on the yield and selectivity. This is between reactions A+a, A+b, and B+a. These experimental observations correlated well with the modelling results when the potential energy surfaces (PES) of the reactions were compared.
Dissertation (MSc)--University of Pretoria, 2020.
National Research Foundation (NRF)
Chemistry
MSc
Unrestricted
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Nowroozi-Isfahani, Taraneh. "Theoretical study on the mechanism of removing nitrogen oxides using isocyanic acid." [Johnson City, Tenn. : East Tennessee State University], 2001. http://etd-submit.etsu.edu/etd/theses/available/etd-0528101-112444/unrestricted/nowroozi0621.pdf.

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Jiménez, Halla José Óscar Carlos. "Theoretical study of catalytic reactions of carbenes: haptotropic rearrangements and the Dötz reaction." Doctoral thesis, Universitat de Girona, 2009. http://hdl.handle.net/10803/7942.

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En aquesta tesi s'han estudiat mecanismes de reaccions de cicloanulació en carbens de Fischer a través de mètodes teòrics, concretament fent servir el nivell de teoria B3LYP/(Wachters' basis / 6-31G**). Els alcoxi- i amino carbens de pentacarbonil crom, ja siguin vinílics o aromàtics, reaccionen amb acetilè per produir fenols, naftols o derivats ciclopentadiè o indè substituïts amb el Cr(CO)3 coordinat, d'una manera regioselectiva. L'objectiu d'aquest treball és discutir ambudes reaccions competitives particularment a la reacció de Dötz, la qual durant els darrers anys ha estat explorada experimentalment per W.D. Wulff, C.P. Casey, R. Aumann i J. Barluenga entre altres diferents propostes mecanístiques. A més K.H. Dötz va demostrar que la coordinació del Cr(CO)3, un cop l'anell ja està format, pot patir canvis haptotròpics, és a dir, la caminada del complex metàl·lic d'un anell a un altre -generalment almenys substituït- canviant la seva hapticitat (coordinació pi amb els membres de l'anell). Llavors, s'han estudiat les migracions haptotròpiques intramoleculars en petits hidrocarbons aromàtics policíclics amb l'objectiu d'analitzar les rutes de reacció per les quals aquestes reaccions es porten a terme
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Zhang, Tianhou. "Theoretical Studies of Fuel Cell Reaction Mechanisms: Water and Oxygen on Platinum Electrodes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1215456813.

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Tussupbayev, Samat. "Theoretical study of reactivity and dynamics of hybride-bridged diruthenium complexes and silylium." Doctoral thesis, Universitat de Girona, 2009. http://hdl.handle.net/10803/8052.

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Esta tesis presenta un estudio computacional de los sistemas con hidruros puente. En la primera parte se estudia la química de complejos de dirutenio con cuatro hidruros puente. Esto incluye las siguientes reacciones: el intercambio del hidruro con hidrógeno molecular; la activación del enlace C-H del etileno para formar el complejo de bis(vinilo)-etileno; el acoplamiento C-C entre el etileno coordinado y dos ligandos vinilo para producir el complejo rutenaciclopentadieno. Al final de esta parte, se discuten a detalle los mecanismos de estas reacciones. Además, se demostró la importancia de la flexibilidad de los ligandos hidruro y la cooperación entre los dos centros metálicos.
En la segunda parte, se estudió el comportamiento fluxional de dos complejos μ-silileno y de un catión sililio. Con esto, se estableció la ruta más favorable en donde se realiza el intercambio de los ligandos hidruro y de los grupos metilo en los complejos μ-silileno. Finalmente, se encontró que hay dos posibles rutas relativas al cambio en la posición del puente Si-H-Si en el cation sililio poliagóstico, asociadas con la rotación interna de los grupos sililo.
The thesis presents a computational study of hydride bridged systems. The chemistry of diruthenium tetrahydride-bridged complex was studied in the first part. It includes the next reactions: the hydride exchange with dihydrogen; the C-H bond activation in ethylene to yield bis(vinyl) ethylene complex; the C-C coupling between coordinated ethy¬lene and two vinyl ligands to yield ruthenacyclopentadiene complex. The detailed mechanism of these reactions has been determined. The importance of flexibility of hydride ligands and cooperation between two metal centers has been demonstrated.
The fluxional behavior of two μ-silylene complexes and a silylium cation was studied in the second part. The pathway responsible for the site-exchange of hydride ligands and methyl groups in the μ-silylene complexes has been established. Two possible mecha¬nisms of the shift of Si-H-Si bridge position in the polyagostic silylium cation, associated with internal rota¬tion of si¬lyl groups have been found.
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Fernández, Villanueva Estefanía. "Theoretical Study of the Geometrical, Electronic and Catalytic properties of Metal Clusters and Nanoparticles." Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/135277.

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[ES] Dado su tamaño subnanométrico, los clusters metálicos están regidos por el confinamiento cuántico, lo que les hace más "moleculares" y menos "metálicos". En consecuencia, manifiestan propiedades que difieren con respecto a las de partículas más grandes del mismo elemento, y que a menudo son ventajosas para la catálisis de reacciones específicas. Además, su menor tamaño los hace más económicos, con una mayor superficie expuesta. Todo ello hace que los clusters sean opciones muy interesantes en catálisis, y su estudio, síntesis y aplicación ha crecido continuamente desde su descubrimiento en los años 90. Esta tesis se ha centrado principalmente en el cobre, del que se presenta, en primer lugar, un estudio fundamental sobre la disociación de oxígeno por clusters de diferentes tamaños. Después, se explora computacionalmente la catálisis de las oxidaciones de CO y propeno, confirmando que los clusters de Cu5 (o inferior) son prometedores para reacciones de oxidación. Las dos reacciones utilizadas son buenos ejemplos de la aplicación potencial en industria, sea para reducir emisiones de CO o para producir epóxido de propeno, que es un intermedio importante en la producción de plásticos y adhesivos, entre otros. Además, también se estudió la influencia de dos soportes en los clusters de cobre y su capacidad de oxidación: N-grafeno como un sistema más inerte y ceria como uno que puede participar activamente en reacciones de oxidación. Finalmente, se incluyen otros dos estudios más específicos, sobre la capacidad de los clusters de Pt3 y Pd3 para catalizar reaciones de acoplamiento C-C como la reacción de Heck, importante para la síntesis de productos de la química fina, y sobre la reacción CO + NO en clusters de Pt, motivado por su uso potencial como catalizadores para la conversión de esas especies en los menos perjudiciales CO2 y N2 en motores de combustión interna.
[CAT] Atès que són de grandària subnanomètrica, els clusters metàl·lics estan regits pel confinament quàntic, el qual els fa més "moleculars" i menys "metàl·lics". En conseqüència, manifesten propietats que són diferents a les de partícules més grans del mateix element, i que sovint són avantatjoses per a la catàlisi de reaccions específiques. A més a més, la seua menor grandària fa que siguen més econòmics, amb una major superfície exposada. Així, els clusters són una opció molt interesant en catàlisi, i el seu estudi, síntesi i aplicació ha cres-cut contínuament des del seu descobriment als anys 90. Aquesta tesi s'ha centrat principalment en el coure, del qual es presenta, en primer lloc, un estudi fonamental sobre la dissociació de l'oxígen per clusters de diferents grandàries. Després, s'explora computacionalment la catàlisi de les oxidacions de CO i de propè, confirmant que els clusters de Cu5 (o inferior) són prometedors per a reaccions d'oxidació. Les dues reaccions utilitzades són bons exemples de l'aplicació potencial en indústria, siga per reduir emissions de CO o per produir epòxid de propè, que és un intermedi important en la producció de plàstics i adhesius, entre altres. A més, també es va estudiar la influència de dos suports en els clusters de coure i la seua capacitat d'oxidació: N-grafè com a un sistema més inert i cèria com a un que pot participar activament en reaccions d'oxidació. Finalment, s'inclouen altres dos estudis més específics, sobre la capacitat dels clusters de Pt3 y Pd3 per catalitzar reaccions d'acoblament C-C com la reacció de Heck, important per a la síntesi de productes de la química fina, i sobre la reacció CO + NO als clusters de Pt, motivat pel seu ús potencial com a catalitzadors per a la conversió d'eixes espècies en els menys perjudicials CO2 i N2 als motors de combustió interna.
[EN] Due to their subnanometric size, metal clusters belong to the regime affected by quantum confinement, which makes them more "molecular" and less "metallic". As a result, they exhibit properties that differ with respect to those of larger particles of the same element, and which are often advantageous in the catalysis of specific reactions. Besides, their smaller size makes them more economic and with a higher surface exposed. All of this renders metal clusters very interesting options for catalysis, and their study, synthesis and application has steadily increased since their discovery in the 90s. In this work we have largely focused on copper, of which a fundamental study on the oxygen dissociation by clusters of different sizes is first presented. Then, the catalysis of the CO and propene oxidation reactions is theoretically explored, confirming that Cu5 (or smaller) clusters are promising systems for oxidation reactions. The two reactions used are good examples of the potential application in industry, either to reduce CO emissions or to produce propene epoxide, an important intermediate in the production of plastics and adhesives, among others. In addition, the influence of two supports in the copper clusters and their oxidation capability is explored: on N-graphene as a more inert system and on ceria as one that can actively participate in oxidation reactions. Finally, two other more specific studies are included, regarding the capability of Pt3 and Pd3 clusters to undergo C-C coupling reactions such as the Heck reaction, important for the synthesis of many products of fine chemistry, and regarding the CO + NO reaction on Pt clusters, motivated by their potential use as catalysts for the conversion of those species in less harmful CO2 and N2 in internal combustion engines.
En primer lugar me gustaría agradecer al Ministerio de Economía y Competitividad de España (MINECO) por la financiación de esta tesis mediante el programa Severo Ochoa (SVP-2013-068146), incluyendo los costes adicionales de mi estancia de investigación (EEBB-I-17-12057).
Fernández Villanueva, E. (2019). Theoretical Study of the Geometrical, Electronic and Catalytic properties of Metal Clusters and Nanoparticles [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/135277
TESIS
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Acuña-Parés, Ferran. "Theoretical study of water oxidation and reduction mechanisms by aminopyridine first row transition metal catalysts." Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/398411.

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One of the major current scientific goals is the development of renewable energy sources. An effective alternative to fossil fuels consists in the conversion of the sunlight energy into chemical fuels. The molecular hydrogen from water is considered the most promising energy carrier. In the natural photosynthesis the solar energy is stored into the carbohydrate chemical bonds derived from water and CO2. The key step of this process is the photo-oxidation of H2O molecules into O2, which provides the protons and electrons needed to produce H2. A detailed knowledge of the reaction mechanisms results essential to enhance the catalytic performance and to ensure the compatibility of the water oxidation and proton reduction catalysts. In this thesis, the key steps of the water oxidation and proton reduction reactions catalyzed by a group of metal complexes and the catalysts structural features that benefit both processes are studied using computational tools
Un dels grans reptes actuals consisteix en el desenvolupament de fonts d'energia renovables. Una alternativa eficaç als combustibles fòssils consisteix en la conversió de l'energia solar en combustibles químics. L’hidrogen molecular provinent de l’aigua és considerat el portador d’energia més prometador. En la fotosíntesi natural l’energia solar és emmagatzemada en els enllaços químics dels carbohidrats obtinguts a partir d’aigua i CO2. L’etapa clau del procés és la foto-oxidació de l'aigua en O2, que aporta els protons i electrons necessaris per produir H2. El coneixement detallat del mecanisme de reacció resulta essencial per millorar el rendiment catalític i assegurar la compatibilitat dels catalitzadors d’oxidació de l’aigua i reducció de protons. En aquesta tesi, les etapes fonamentals del mecanisme de les reaccions d’oxidació de l’aigua o la reducció de protons catalitzades per un grup de complexos metàl·lics i les característiques estructurals dels catalitzadors que beneficien ambdues reaccions són estudiades utilitzant eines computacionals
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Books on the topic "Reaction Mechanism - Theoretical Study"

1

G, Compton R., and Hamnett A, eds. New techniques for the study of electrodes and their reactions. Amsterdam: Elsevier, 1989.

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P, Kundu Krishna, Acosta Waldo A, United States. National Aeronautics and Space Administration., and United States. Army Aviation Systems Command., eds. Jet-A reaction mechanism study for combustion application. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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P, Kundu Krishna, Acosta Waldo A, United States. National Aeronautics and Space Administration., and United States. Army Aviation Systems Command., eds. Jet-A reaction mechanism study for combustion application. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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Michael, Mortimer, Taylor Peter, Royal Society of Chemistry (Great Britain), and Open University, eds. Chemical kinetics and mechanism. Cambridge: Royal Society of Chemistry, 2002.

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Crowley, John N. A study of reaction mechanism by matrix isolation/FTIR spectroscopy. Norwich: University of East Anglia, 1987.

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United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., ed. An analytical study of the hydrogen-air reaction mechanism with application to scramjet combustion. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.

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United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., ed. An analytical study of the hydrogen-air reaction mechanism with application to scramjet combustion. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.

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Polischuk, Nikolay, and Dmitriy Kohman. The legal mechanism for the implementation of amnesty in the Russian Federation and the social consequences of its application. ru: INFRA-M Academic Publishing LLC., 2023. http://dx.doi.org/10.12737/1863097.

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The monograph is devoted to the legal mechanism of implementation and the social consequences of the application of amnesty. The conducted research makes it possible to really assess the effectiveness of the amnesty, as well as to determine the directions of its improvement. The formulated conclusions and proposals complement and develop theoretical and legal knowledge in the field under study. The author's classification of amnesties has been developed, which may predetermine the conduct of separate studies for each of the types. The concept of "relapse of amnestied persons" is formulated, the signs of the amnesty act are established, the priority of the penological (penal) component in the characterization of the personality of a potentially amnestied person is justified. Separate ways of improving the mechanism of amnesty implementation in the Russian Federation are highlighted, taking into account the experience of foreign countries and modern achievements of criminal law, criminology and penal enforcement law. For students, postgraduates and teachers of law schools and faculties, as well as a wide range of readers interested in amnesty issues.
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Scialpi, Angela, and Alessio Mengoni, eds. La PCR e le sue varianti. Florence: Firenze University Press, 2008. http://dx.doi.org/10.36253/978-88-6453-159-5.

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The book "La PCR e le sue varianti" is designed as a reference tool for those whose laboratory activities deal with methods based on nucleic acid amplification. The text provides the theoretical bases of the polymerase chain reaction (PCR) and its variants (e.g. RT-PCR, quantitative PCR, isothermic PCR) in a rapid and concise manner and describes the principal applications used for genetic identification and the study of genetic polymorphism, in the form of a protocol that can be easily consulted by the users.
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Karagodin, Valeriy, and Nikolay Karepanov. Features of investigation of fraud committed by Bank employees in the field of lending. ru: INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1064906.

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The monograph is devoted to the study of legal, theoretical and forensic issues that arise in the investigation of fraud committed by Bank employees in the field of lending. The features of their solution are defined, specific recommendations are developed aimed at forming an effective mechanism for investigating the analyzed type of crimes. The results of the studied practical material are presented. It is a complete scientific study and is intended for forensic scientists, law enforcement officers, teachers, graduate students and students of law schools and faculties who are interested in the problems of investigating certain types of crimes.
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Book chapters on the topic "Reaction Mechanism - Theoretical Study"

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García Melchor, Max. "The Negishi Reaction Mechanism." In A Theoretical Study of Pd-Catalyzed C-C Cross-Coupling Reactions, 59–88. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-01490-6_4.

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García Melchor, Max. "The Cu-Free Sonogashira Reaction Mechanism." In A Theoretical Study of Pd-Catalyzed C-C Cross-Coupling Reactions, 89–111. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-01490-6_5.

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García Melchor, Max. "An Asymmetric Suzuki-Miyaura Reaction Mechanism." In A Theoretical Study of Pd-Catalyzed C-C Cross-Coupling Reactions, 113–33. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-01490-6_6.

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Monge-Palacios, Manuel, Cipriano Rangel, Joaquin Espinosa-García, Hong Fu, and Minghui Yang. "Isotope effects on the dynamics properties and reaction mechanism in the Cl(2P) + NH3 reaction: a QCT and QM study." In Highlights in Theoretical Chemistry, 69–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-41272-1_9.

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Kabanda, Mwadham M., and Kgalaletso P. Otukile. "A Theoretical Study of the Preferred Reaction Mechanism Between Chloroacetic Acid and Thiourea." In Advances in Quantum Systems in Chemistry, Physics, and Biology, 119–42. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34941-7_7.

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Alagona, Giuliano, and Caterina Ghio. "Theoretical Calculations on an Enzyme Catalyzed Reaction Mechanism." In The Enzyme Catalysis Process, 345–55. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4757-1607-8_23.

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Li, Jie, Tianshuang Li, Hongliang Zhang, Jingkun Wang, Kena Sun, and Jin Xiao. "DFT Study on COS Oxidation Reaction Mechanism." In Light Metals 2019, 879–84. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05864-7_107.

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Cambeiro, Xacobe C., and Miquel A. Pericàs. "The Mechanism of the Pauson-Khand Reaction: Hypothesis, Experimental Facts, and Theoretical Investigations." In The Pauson-Khand Reaction, 23–48. Chichester, UK: John Wiley & Sons, Ltd, 2012. http://dx.doi.org/10.1002/9781119941934.ch2.

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Freindorf, Marek, Thomas Sexton, Elfi Kraka, and Dieter Cremer. "The mechanism of the cycloaddition reaction of 1,3-dipole molecules with acetylene: an investigation with the unified reaction valley approach." In Highlights in Theoretical Chemistry, 173–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-662-47051-0_16.

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Vergote, Thomas, Thomas Gathy, Fady Nahra, Olivier Riant, Daniel Peeters, and Tom Leyssens. "Mechanism of ketone hydrosilylation using NHC–Cu(I) catalysts: a computational study." In Highlights in Theoretical Chemistry, 135–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-41315-5_12.

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Conference papers on the topic "Reaction Mechanism - Theoretical Study"

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Ormachea, Carla, Mauro Cainelli, María Kneeteman, and Pedro Mancini. "Reaction Mechanism of Polar Diels-Alder Reactions Between 3-Nitrofuran and different Dienes. A Theoretical Study." In The 18th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2014. http://dx.doi.org/10.3390/ecsoc-18-e014.

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Fleisher, Mendel, E. Lukevics, L. Leite, D. Jansone, K. Edolfa, I. Liepina, and V. Stonkus. "Theoretical study of the ketonization reaction mechanism of acetic acid over SiO2." In The 13th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2009. http://dx.doi.org/10.3390/ecsoc-13-00148.

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Yusuf, Muhammad. "Theoretical Study on the Reaction Mechanism of Acetalization of 3-Chlorobenzaldehyde Catalyzed by Halogen Acid." In Proceedings of The 5th Annual International Seminar on Trends in Science and Science Education, AISTSSE 2018, 18-19 October 2018, Medan, Indonesia. EAI, 2019. http://dx.doi.org/10.4108/eai.18-10-2018.2287347.

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Maia, Thalita Vaneska Moreira, Denilma Maurício Cardoso da Silva, Andréa Claudia Oliveira Silva, and Régis Casimiro Leal. "Theoretical study of the reaction mechanism of triiodide ion (I3–) from iodine (I2) and iodide anion (I–)." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020155.

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This work studies the reaction mechanism of triiodide ion (I3–) from iodine (I2) and iodide anion (I–), furthermore it investigates the thermodynamic preference of formation of I3– in three different solvents. Through DFT calculations and using the continuous polarizable model (PCM) it was possible to determine the reaction mechanism, as well as to show that the formation of the triiodide ion, from iodine and iodide, is favored in solvents of less polarity.
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Semenikhin, A. S., A. S. Savchenkova, I. V. Chechet, S. G. Matveev, M. Frenklach, and A. M. Mebel. "BRIDGING NUCLEATION REACTIONS BETWEEN ACENAPHTHYLENE AND NAPHTHALENE: A THEORETICAL STUDY." In 9TH INTERNATIONAL SYMPOSIUM ON NONEQUILIBRIUM PROCESSES, PLASMA, COMBUSTION, AND ATMOSPHERIC PHENOMENA. TORUS PRESS, 2020. http://dx.doi.org/10.30826/nepcap9a-09.

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The formation of soot during combustion of hydrocarbon fuels is a rather complex process and one of its stages is nucleation. In recent years, the physical mechanism that takes into account the appearance of the initial soot nuclei has been increasingly studied. The main ideas and disadvantages of this mechanism were recently considered by M. Frenklach and A. Mebel, who also proposed a new chemical nucleation mechanism for pyrene dimerization.
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Shi, Shaoping, Daniel Lee, Sandra McSurdy, Michael McMillian, Steven Richardson, and William Rogers. "Theoretical Investigation of Autoignition of Combustible Gas Mixtures in Rapid Compression Machines." In ASME 2002 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/icef2002-489.

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In any theoretical investigation of ignition processes in natural gas reciprocating engines, physical and chemical mechanisms must be adequately modeled and validated in an independent manner. The Rapid Compression Machine (RCM) has been used in the past as a tool to validate both autoignition models as well as turbulent mixing effects. In this study, two experimental cases were examined. In the first experimental case, the experimental measurements of Lee and Hochgreb (1998a) were chosen to validate the simulation results. In their experiments, hydrogen/oxygen/argon mixtures were used as reactants. In the simulations, a reduced chemical kinetic mechanism consisting of 10 species and 19 elementary reactions coupled to a CFD software, Fluent 6, was used to simulate the autoignition. The ignition delay from the simulation agreed very well with that from the experimental data of Lee and Hochgreb, (1998b). In the second case, experimental data derived from an RCM with two opposed, pneumatically driven pistons (Brett et al., 2001) were used to study the autoignition of methane/oxygen/argon mixtures. The reduced chemical kinetic mechanism DRM22, derived from the GRI-Mech reaction scheme coupled to Fluent 6, was applied in the simulations. The DRM22 scheme included 22 species and 104 reactions. When methane/oxygen/argon mixture were simulated for the RCM, the ignition delay deviated about 15% from the experimental results. The simulation approaches as well as the validation results are discussed in detail in this paper. The paper also discusses an evaluation of reduced reaction models available in the literature for subsequent Fluent modeling.
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Bhopatkar, Neelesh S., Heng Ban, and Thomas K. Gale. "Prediction of Mercury Speciation in Coal-Combustion Systems." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15502.

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This study is a part of a comprehensive investigation, to conduct bench-, pilot-, and full-scale experiments and theoretical studies to elucidate the fundamental mechanisms associated with mercury oxidation and capture in coal-fired power plants. The objective was to quantitatively describe the mechanisms governing adsorption, desorption, and oxidation of mercury in coal-fired flue gas carbon, and establish reaction-rate constants based on experimental data. A chemical-kinetic model was developed which consists of homogeneous mercury oxidation reactions as well as heterogeneous mercury adsorption reactions on carbon surfaces. The homogeneous mercury oxidation mechanism has eight reactions for mercury oxidation. The homogeneous mercury oxidation mechanism quantitatively predicts the extent of mercury oxidation for some of datasets obtained from synthetic flue gases. However, the homogeneous mechanism alone consistently under predicts the extent of mercury oxidation in full scale and pilot scale units containing actual flue gas. Heterogeneous reaction mechanisms describe how unburned carbon or activated carbon can effectively remove mercury by adsorbing hydrochloric acid (HCI) to form chlorinated carbon sites, releasing the hydrogen. The elemental mercury may react with chlorinated carbon sites to form sorbed HgCl. Thus mercury is removed from the gas-phase and stays adsorbed on the carbon surface. Predictions using this model have very good agreement with experimental results.
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Wang, Songtao, Xiaoqing Qiang, Weichun Lin, Guotai Feng, and Zhongqi Wang. "A Study of Parameter Selection Principle and Internal Flow Mechanism in a Multi-Stage Low-Reaction Axial Flow Compressor." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50554.

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A subsonic multi-stage highly loaded, low-reaction, boundary layer suction axial flow compressor design concept was proposed in this paper and its feasibility was studied from theoretical analysis. This design concept could greatly raise the single stage pressure ratio while keeping the compressor efficiency in a high level. The distribution principle of total pressure ratio and static pressure ratio in a multi-stage low-reaction compressor was studied as well as the selection principle of reaction, diffusion factor and other total parameters. Considering the design feature of this new type of compressor, the internal flow in a large geometry turning angle cascade was studied in order to establish the relation between geometry parameters and surface pressure distribution. The relation between surface pressure distribution and profile loss, trailing edge loss, etc was also studied in this paper. By using this design concept combined with the boundary layer suction method, a certain eleven stages axial compressor’s count was reduced to seven. The numerical simulation was done in the last two stages which had typical flow characteristics. The simulation result proved that the multi-stage low-reaction axial flow compressor design concept was feasible.
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Wen, Zhengcheng, Jiangrong Xu, Zhihua Wang, and Kefa Cen. "Theoretical Study on the Mechanism and Kinetic of the Reactions between Elemental Mercury and Oxidizing Radicals." In 2011 Asia-Pacific Power and Energy Engineering Conference (APPEEC). IEEE, 2011. http://dx.doi.org/10.1109/appeec.2011.5747700.

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WU, ZHIJIAN, FUQIANG BAN, and RUSSELL J. BOYD. "THEORETICAL STUDY ON THE REACTION MECHANISMS OF THE IMIDE FORMATION IN AN N-(O-CARBOXYBENZOYL)-L-AMINO ACID." In Proceedings of the International Symposium on Solid State Chemistry in China. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776846_0077.

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Reports on the topic "Reaction Mechanism - Theoretical Study"

1

Rice, Betsy M., William Mattson, John Grosh, and S. F. Trevino. A Molecular Dynamics Study of Detonation. 2. The Reaction Mechanism. Fort Belvoir, VA: Defense Technical Information Center, March 1996. http://dx.doi.org/10.21236/ada305237.

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Pope, David P. Combined Theoretical and Experimental Study of a New Mechanism of Yielding with Application to the Brittle-Ductile Transition. Fort Belvoir, VA: Defense Technical Information Center, June 2001. http://dx.doi.org/10.21236/ada403571.

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Banin, Amos, Joseph Stucki, and Joel Kostka. Redox Processes in Soils Irrigated with Reclaimed Sewage Effluents: Field Cycles and Basic Mechanism. United States Department of Agriculture, July 2004. http://dx.doi.org/10.32747/2004.7695870.bard.

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The overall objectives of the project were: (a) To measure and study in situ the effect of irrigation with reclaimed sewage effluents on redox processes and related chemical dynamics in soil profiles of agricultural fields. (b) To study under controlled conditions the kinetics and equilibrium states of selected processes that affect redox conditions in field soils or that are effected by them. Specifically, these include the effects on heavy metals sorption and desorption, and the effect on pesticide degradation. On the basis of the initial results from the field study, increased effort was devoted to clarifying and quantifying the effects of plants and water regime on the soil's redox potential while the study of heavy metals sorption was limited. The use of reclaimed sewage effluents as agricultural irrigation water is increasing at a significant rate. The relatively high levels of suspended and, especially, dissolved organic matter and nitrogen in effluents may affect the redox regime in field soils irrigated with them. In turn, the changes in redox regime may affect, among other parameters, the organic matter and nitrogen dynamics of the root zone and trace organic decomposition processes. Detailed data of the redox potential regime in field plots is lacking, and the detailed mechanisms of its control are obscure and not quantified. The study established the feasibility of long-term, non-disturbing monitoring of redox potential regime in field soils. This may enable to manage soil redox under conditions of continued inputs of wastewater. The importance of controlling the degree of wastewater treatment, particularly of adding ultrafiltration steps and/or tertiary treatment, may be assessed based on these and similar results. Low redox potential was measured in a field site (Site A, KibutzGivat Brenner), that has been irrigated with effluents for 30 years and was used for 15 years for continuous commercial sod production. A permanently reduced horizon (Time weighted averaged pe= 0.33±3.0) was found in this site at the 15 cm depth throughout the measurement period of 10 months. A drastic cultivation intervention, involving prolonged drying and deep plowing operations may be required to reclaim such soils. Site B, characterized by a loamy texture, irrigated with tap water for about 20 years was oxidized (Time weighted average pe=8.1±1.0) throughout the measurement period. Iron in the solid phases of the Givat Brenner soils is chemically-reduced by irrigation. Reduced Fe in these soils causes a change in reactivity toward the pesticide oxamyl, which has been determined to be both cytotoxic and genotoxic to mammalian cells. Reaction of oxamyl with reduced-Fe clay minerals dramatically decreases its cytotoxicity and genotoxicity to mammalian cells. Some other pesticides are affected in the same manner, whereas others are affected in the opposite direction (become more cyto- and genotoxic). Iron-reducing bacteria (FeRB) are abundant in the Givat Brenner soils. FeRB are capable of coupling the oxidation of small molecular weight carbon compounds (fermentation products) to the respiration of iron under anoxic conditions, such as those that occur under flooded soil conditions. FeRB from these soils utilize a variety of Fe forms, including Fe-containing clay minerals, as the sole electron acceptor. Daily cycles of the soil redox potential were discovered and documented in controlled-conditions lysimeter experiments. In the oxic range (pe=12-8) soil redox potential cycling is attributed to the effect of the daily temperature cycle on the equilibrium constant of the oxygenation reaction of H⁺ to form H₂O, and is observed under both effluent and freshwater irrigation. The presence of plants affects considerably the redox potential regime of soils. Redox potential cycling coupled to the irrigation cycles is observed when the soil becomes anoxic and the redox potential is controlled by the Fe(III)/Fe(II) redox couple. This is particularly seen when plants are grown. Re-oxidation of the soil after soil drying at the end of an irrigation cycle is affected to some degree by the water quality. Surprisingly, the results suggest that under certain conditions recovery is less pronounced in the freshwater irrigated soils.
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TITOVA, E. HISTORIOGRAPHIC REVIEW ON THE TOPIC OF THE STUDY OF MIGRATION PROCESSES IN THE RUSSIAN FAR EAST AT THE BEGINNING OF THE XXI CENTURY. Science and Innovation Center Publishing House, 2021. http://dx.doi.org/10.12731/2077-1770-2021-13-4-2-34-53.

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The article provides an overview of scientific research on the study of migration processes in the Far Eastern regions. The problems of migration, the state mechanism for regulating migration issues, and the peculiarities of interethnic interactions are very topical topics not only at the regional, but also at the national level. In the Russian Federation, studies on these topics have appeared relatively recently. Due to the fact that at the end of the 20th century there was a surge in the ethnic self-awareness of the peoples of the country, together with the intensification of socio-economic transformation processes, there are sharp, often radical, changes in the field of interethnic interactions, in particular, the growth of armed interethnic conflicts, an increase in migration outflows or inflows. etc. Modern scientific research in the field of migration processes is practice-oriented, that is, they are aimed at the implementation of narrow applied problems, there is also an increase in the accumulation of an updated extensive theoretical and methodological base. In particular, studies, for example, concerning the topic of interethnic interactions, are directly related to the topic of ethnic tolerance, which has also become very popular and in demand in the last decade for specialists from various scientific fields - psychologists, ethnographers, lawyers, etc.
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Chapman and Toema. PR-266-07209-R01 Phase 2 - Assessment of the Robustness and Transportability of the Gas Turbine Model. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2010. http://dx.doi.org/10.55274/r0010719.

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This report presents the modeling study of a gas turbine combustor based on first engineering principles to fully characterize the nitrogen oxides (NOx) and carbon monoxide emissions (CO). The model is mainly focused on the emissions from the widely used lean-premixed, dry low-NOx combustor. The combustor is divided into several zones where each zone can be considered as a plug-flow reactor. Each of these zones is assumed to have a uniform pressure, temperature and perfect mixing between combustion species. The temperature of each zone is calculated using mass and energy balances along with heat transfer through the combustor liner. The emissions are calculated using well-know pollutant reaction schemes such as the Zeldovich mechanism in addition to other well-established semi-empirical correlations.
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Asenath-Smith, Emily, Emma Ambrogi, Eftihia Barnes, and Jonathon Brame. CuO enhances the photocatalytic activity of Fe₂O₃ through synergistic reactive oxygen species interactions. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42131.

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Iron oxide (α-Fe₂O₃, hematite) colloids were synthesized under hydrothermal conditions and investigated as catalysts for the photodegradation of an organic dye under broad-spectrum illumination. To enhance photocatalytic performance, Fe₂O₃ was combined with other transition-metal oxide (TMO) colloids (e.g., CuO and ZnO), which are sensitive to different regions of the solar spectrum (far visible and ultraviolet, respectively), using a ternary blending approach for compositional mixtures. For a variety of ZnO/Fe₂O₃/CuO mole ratios, the pseudo-first-order rate constant for methyl orange degradation was at least double the sum of the individual Fe₂O₃ and CuO rate constants, indicating there is an underlying synergy governing the photocatalysis reaction with these combinations of TMOs. A full compositional study was carried out to map the interactions between the three TMOs. Additional experiments probed the identity and role of reactive oxygen species and elucidated the mechanism by which CuO enhanced Fe₂O₃ photodegradation while ZnO did not. The increased photocatalytic performance of Fe2O3 in the presence of CuO was associated with hydroxyl radical ROS, consistent with heterogeneous photo-Fenton mechanisms, which are not accessible by ZnO. These results imply that low-cost photocatalytic materials can be engineered for high performance under solar illumination by selective pairing of TMOs with compatible ROS.
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Kharadzhian, Natalia, Larysa Savchenko, Karyna Safian, Yuliia Kulinka, and Oksana Mykolaivna Kopylova. Future Professional Education Specialists’ Mastering of Project Methodology of Creating Pedagogical Situations in the Service Sector. [б. в.], August 2020. http://dx.doi.org/10.31812/123456789/4142.

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The article reveals the problems of mastering by future specialists of the project methodology of creating pedagogical situations in higher education institutions as a means of improving the quality of education. Objectives of the article: to determine the influence of the project method on the creation of pedagogical situations in the process of teaching students; the choice of logic and mechanism of design actions depends on the purpose and the initial conceptual position regarding the subject reincarnates; to study the influence of pedagogical situations on the quality of education in the higher pedagogical school; to diagnose the implementation of the projects method and pedagogical situations in the process of education at the university. The project method provides the presence of a problem that requires integrated knowledge and research for its solution. The results of the planned activities should have practical, theoretical and cognitive significance. Modeling of pedagogical situations is the process of formation of situations-models which simulate the state and dynamics of the educational process and fix the contradiction between the achieved and desired in the personality development in a certain time interval. During the forming experiment, pedagogical situations were used to form the professional competence of the future specialist.
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Kalman, Joseph, and Maryam Haddad. Wastewater-derived Ammonia for a Green Transportation Fuel. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2021.2041.

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The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.
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Kalman, Joseph, and Maryam Haddad. Wastewater-derived Ammonia for a Green Transportation Fuel. Mineta Transportation Institute, July 2022. http://dx.doi.org/10.31979/mti.2022.2041.

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The energy-water nexus (i.e., availability of potable water and clean energy) is among the most important problems currently facing society. Ammonia is a carbon-free fuel that has the potential to reduce the carbon footprint in combustion related vehicles. However, ammonia production processes typically have their own carbon footprint and do not necessarily come from sustainable sources. This research examines wastewater filtration processes to harvest ammonia for transportation processes. The research team studied mock wastewater solutions and was able to achieve ammonia concentrations above 80%(nanofiltration) and 90% (reverse osmosis). The research team also investigated the influence of transmembrane pressure and flow rates. No degradation to the membrane integrity was observed during the process. This research used constant pressure combustion simulations to calculate the ignition delay times for NH3-air flames with expected impurities from the wastewater treatment processes. The influence of impurities, such as H2O, CO, CO2, and HCl, were studied under a range of thermodynamic conditions expected in compression ignition engines. The team observed carbon monoxide and water vapor to slightly decrease (at most 5%) ignition delay time, whereas HCl, in general, increased the ignition delay. The changes to the combustion chemistry and its influence of the reaction mechanism on the results are discussed. The experimental wastewater treatment study determined that reverse osmosis produced higher purity ammonia. The findings of the combustion work suggest that ignition delays will be similar to pure ammonia if HCl is filtered from the final product.
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10

Finkelstain, Israel, Steven Buccola, and Ziv Bar-Shira. Pooling and Pricing Schemes for Marketing Agricultural Products. United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568099.bard.

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In recent years there has been a growing concern over the performance of Israel and U.S. agricultural marketing organizations. In Israel, poor performance of some marketing institutions has led to radical reforms. Examples are the two leading export industries - citrus and flowers. In the U.S., growth of local market power is eliminating competitive row product prices which served as the basis for farmer cooperative payment plans. This research studies, theoretically, several aspects of the above problem and develops empirical methods to assess their relative importance. The theoretical part deals with two related aspects of the operation of processing and marketing firms. The first is the technological structure of these firms. To this end, we formalize a detailed theory that describes the production process itself and the firm's decision. The model accounts for multiple products and product characteristics. The usefulness of the theory for measurement of productivity and pricing of raw material is demonstrated. The second aspect of the processing and marketing firm that we study is unique to the agricultural sector, where many such firms are cooperatives. In such cooperative an efficient and fair mechanism for purchasing raw materials from members is crucial to successful performances of the firm. We focus on: 1) pricing of raw materials. 2) comparison of employment of quota and price regimes by the cooperative to regulate the quantities, supplied by members. We take into consideration that the cooperative management is subject to pressure from member farmers. 3) Tier pricing for raw materials in order to ensure efficiency and zero profits at the cooperative level. This problem is examined in both closed and open cooperatives. The empirical part focuses in: 1) the development of methodologies for estimating demand for differentiated products; 2) assessing farmers response to component pricing; 3) measurement of potential and actual exploitation of market power by an agricultural marketing firm. The usefulness of the developed methodologies are demonstrated by several application to agricultural sub-sectors, including: U.S. dairy industry, Oregon wine industry, Israeli Cotton industry and Israeli Citrus industry.
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