Academic literature on the topic 'Reactivity ratios'
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Journal articles on the topic "Reactivity ratios"
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Scott, Gabriel, Dubé, and Penlidis. "Making the Most of Parameter Estimation: Terpolymerization Troubleshooting Tips." Processes 7, no. 7 (July 12, 2019): 444. http://dx.doi.org/10.3390/pr7070444.
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Multi-component polymers can provide many advantages over their homopolymer counterparts. Terpolymers are formed from the combination of three unique monomers, thus creating a new material that will exhibit desirable properties based on all three of the original comonomers. To ensure that all three comonomers are incorporated (and to understand and/or predict the degree of incorporation of each comonomer), accurate reactivity ratios are vital. In this study, five terpolymerization studies from the literature are revisited and the ‘ternary’ reactivity ratios are re-estimated. Some recent studies have shown that binary reactivity ratios (that is, from the related copolymer systems) do not always apply to ternary systems. In other reports, binary reactivity ratios are in good agreement with terpolymer data. This investigation allows for the comparison between previously determined binary reactivity ratios and newly estimated ‘ternary’ reactivity ratios for several systems. In some of the case studies presented herein, reactivity ratio estimation directly from terpolymerization data is limited by composition restrictions or ill-conditioned systems. In other cases, we observe similar or improved prediction performance (for ternary systems) when ‘ternary’ reactivity ratios are estimated directly from terpolymerization data (compared to the traditionally used binary reactivity ratios). In order to demonstrate the advantages and challenges associated with ‘ternary’ reactivity ratio estimation, five case studies are presented (with examples and counter-examples) and troubleshooting suggestions are provided to inform future work.
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El-Newehy, Mohamed H., Salem S. Al-Deyab, and Ali Mohsen Ali Al-Hazmi. "Reactivity Ratios for Organotin Copolymer Systems." Molecules 15, no. 4 (April 15, 2010): 2749–58. http://dx.doi.org/10.3390/molecules15042749.
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Peng, F. M. "The Reactivity Ratios of Acrylonitrile Copolymerization." Journal of Macromolecular Science: Part A - Chemistry 22, no. 9 (September 1985): 1241–69. http://dx.doi.org/10.1080/00222338508063331.
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Albert, Richard, and William M. Malone. "Semi-empirical calculation of reactivity ratios." Journal of Polymer Science: Polymer Symposia 42, no. 1 (March 8, 2007): 245–55. http://dx.doi.org/10.1002/polc.5070420127.
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O'Driscoll, K. F., and P. M. Reilly. "Determination of reactivity ratios in copolymerization." Makromolekulare Chemie. Macromolecular Symposia 10-11, no. 1 (October 1987): 355–74. http://dx.doi.org/10.1002/masy.19870100118.
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Liu, Yan, Runsheng Mao, Malcolm B. Huglin, and Paul A. Holmes. "Reactivity ratios in copolymerizations involving allyl methacrylate." Polymer 37, no. 8 (April 1996): 1437–41. http://dx.doi.org/10.1016/0032-3861(96)81142-6.
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Hauch, Emma, Xiaoqin Zhou, Thomas A. Duever, and Alexander Penlidis. "Estimating Reactivity Ratios From Triad Fraction Data." Macromolecular Symposia 271, no. 1 (September 2008): 48–63. http://dx.doi.org/10.1002/masy.200851106.
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van Herk, Alex M., and Bert Klumperman. "IUPAC Recommendations for Estimating Copolymerization Reactivity Ratios." Macromolecules 57, no. 11 (June 11, 2024): 5121–22. http://dx.doi.org/10.1021/acs.macromol.4c01156.
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Journal, Baghdad Science. "Copolymerazaion of N-vinyl-2-pyrrolidon with Acrylic Acid and Methylmethacrylate." Baghdad Science Journal 11, no. 1 (March 2, 2014): 123–27. http://dx.doi.org/10.21123/bsj.11.1.123-127.
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Low conversion copolymerization of N-vinyl-2-pyrrolidon M.W = (111.14) VP (monomer-1) has been conducted with acrylic acid AA and methymethacrylate MMA in ethanol at 70ºC , using Benzoyl peroxide BPO as initiator . The copolymer composition has been determined by elemental analysis. The monomer reactivity ratios have been calculated by the Kelen-Tudos and Finman-Ross graphical procedures . The derived reactivity ratios (r1 , r2 ) are : (0.51 , 4.85) for (VP / AA ) systems and (0.34 , 7.58) for (VP , MMA) systems , and found the reactivity ratios of the monomer AA , MMA is mor than the monomer VP in the copolymerization of (VP / AA) and (VP /MMA) systems respectly . The reactivity ratios values were used for microstructures calculation.
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Hamza, Rana R., Mahmoud A. Al-Issa, and Redha I. Al-Bayati. "Copolymerazaion of N-vinyl-2-pyrrolidon with Acrylic Acid and Methylmethacrylate." Baghdad Science Journal 11, no. 1 (March 2, 2014): 123–27. http://dx.doi.org/10.21123/bsj.2014.11.1.123-127.
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Low conversion copolymerization of N-vinyl-2-pyrrolidon M.W = (111.14) VP (monomer-1) has been conducted with acrylic acid AA and methymethacrylate MMA in ethanol at 70ºC , using Benzoyl peroxide BPO as initiator . The copolymer composition has been determined by elemental analysis. The monomer reactivity ratios have been calculated by the Kelen-Tudos and Finman-Ross graphical procedures . The derived reactivity ratios (r1 , r2 ) are : (0.51 , 4.85) for (VP / AA ) systems and (0.34 , 7.58) for (VP , MMA) systems , and found the reactivity ratios of the monomer AA , MMA is mor than the monomer VP in the copolymerization of (VP / AA) and (VP /MMA) systems respectly . The reactivity ratios values were used for microstructures calculation.
Dissertations / Theses on the topic "Reactivity ratios"
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Paz, Pazos Marta. "Synthesis and Characterization of Copolymers Based on 2,3,4,5,6-Pentafluorostyrene." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1134570748.
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Wiles, Kenton Broyhill. "Determination of Reactivity Ratios for Acrylonitrile/Methyl Acrylate Radical Copolymerization Via Nonlinear Methodologies Using Real Time FTIR." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34888.
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Reactivity ratios for the homogeneous free radical initiated copolymerization of acrylonitrile and methyl acrylate were measured by NMR on isolated, low conversion copolymers and by real time in situ FTIR. The system utilized azobisisobutyronitrile (AIBN) initiator in dimethyl formamide (DMF) at 62°. The FTIR technique allowed rapid generation of extensive copolymer compositions, which permitted application of nonlinear least squares methodology for the first time to this copolymer system. Thus, reactivity ratios at the 95% confidence level were determined to be 1.29 ± 0.2 and 0.96 ± 0.2 for acrylonitrile and methyl acrylate, respectively. The results are useful for the development of acrylonitrile (<90%) melt processable copolymer fibers and films, which could include precursors for carbon fibers.Master of Science
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Rosario, Astrid Christa. "The Chemistry of Dimethacrylate-Styrene Networks and Development of Flame Retardant, Halogen-Free Fiber Reinforced Vinyl Ester Composites." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/11228.
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One of the major classes of polymer matrix resins under consideration for structural composite applications in the infrastructure and construction industries is vinyl ester resin. Vinyl ester resin is comprised of low molecular weight poly(hydroxyether) oligomers with methacrylate endgroups diluted with styrene monomer. The methacrylate endgroups cure with styrene via free radical copolymerization to yield thermoset networks. The copolymerization behavior of these networks was monitored by Fourier Transform Infrared Spectroscopy (FTIR) at various cure conditions. Reactions of the carbon-carbon double bonds of the methacrylate (943 cm-1) and styrene (910 cm-1) were followed independently. Oligomers possessing number average molecular weights of 700 g/mole were studied with systematically increasing levels of styrene. The Mortimer-Tidwell reactivity ratios indicated that at low conversion more styrene was incorporated into the network at lower cure temperatures. The experimental vinyl ester-styrene network compositions deviated significantly from those predicted by the Meyer-Lowry integrated copolymer equation at higher conversion, implying that the reactivity ratios for these networks may change with conversion. The kinetic data were used to provide additional insight into the physical and mechanical properties of these materials.
In addition to establishing the copolymerization kinetics of these materials, the development of halogen free fiber reinforced vinyl ester composites exhibiting good flame properties was of interest. Flame retardant vinyl ester resins are used by many industries for applications requiring good thermal resistance. The current flame-retardant technology is dependent on brominated vinyl esters, which generate high levels of smoke and carbon monoxide. A series of halogen free binder systems has been developed and dispersed in the vinyl ester to improve flame retardance. The binder approach enables the vinyl ester resin to maintain its low temperature viscosity so that fabrication of composites via Vacuum Assisted Resin Transfer Molding (VARTM) is possible. The first binder system investigated was a polycaprolactone layered silicate nanocomposite, which was prepared via intercalative polymerization. Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) data indicated a mixed morphology of exfoliated and intercalated structures. The mechanical properties and the normalized peak heat release rates were comparable to the neat vinyl ester resin.
Alternative binder systems possessing inherent flame retardance were also investigated. A series of binders comprised of novolac, bisphenol A diphosphate, and montmorillonite clay were developed and dispersed into the vinyl ester matrix. Cone calorimetry showed reductions in the peak heat release rate comparable to the brominated resin.Ph. D.
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Barbosa, Natalia Bahia. "Copolimerização de estireno e VeoVa 10: determinação das razões de reatividade e estudo do processo de polimerização em emulsão." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-04102018-091517/.
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Neste trabalho foram determinadas as razões de reatividade para a copolimerização entre estireno e VeoVa-10 através de estudo experimental de copolimerização em solução em tolueno. Os parâmetros foram obtidos através do ajuste aos dados experimentais dos modelos de Mayo-Lewis e Meyer-Lowry, utilizando o critério dos erros-nas-variáveis (método dos mínimos quadrados não-linear que considera a existência de erros em todas as variáveis medidas). A metodologia experimental desenvolvida, de polimerização em solução em ampolas preparadas dentro de uma glove box e submetidas a temperatura de 80°C, resultou em baixa conversão dos monômeros, adequada para a estimação das razões de reatividade pelos modelos. As amostras foram analisadas quantitativamente por espectroscopia de infravermelho para determinar, ao longo da reação, a conversão e as frações molares de cada um dos monômeros na mistura, sendo a composição do copolímero obtida pelo consumo dos monômeros. Foram obtidos valores de razões de reatividade bastante diferentes (restireno = 49.926 e rVeoVa10 = 1,062), evidenciando que a copolimerização destes monômeros em batelada leva a grandes desvios de composição, com tendência à formação de dois homopolímeros. O mesmo sistema de copolimerização foi também estudado no processo de polimerização em emulsão, em processos batelada alimentada e batelada intermitente. A conversão global dos monômeros e a distribuição de diâmetro médio das partículas foram analisadas durante a reação através das amostras coletadas ao longo do processo. Os efeitos das estratégias de alimentação avaliados foram apenas preliminares, pois não apresentaram resultados conclusivos.In this work the reactivity ratios for the copolymerization between styrene and VeoVa-10 were determined through an experimental study of solution copolymerization in toluen. The parameters were obtained by fitting the experimental data with the Mayo-Lewis and Meyer-Lowry models using the error-in-variables criterion (non-linear least squares method that considers the existence of errors in all measured variables). The experimental methodology developed, solution polymerization in ampoules prepared in a glove box and reacted at 80 °C, resulted in low conversion of the monomers, suitable for estimation of the reactivity ratios by the models employed. The samples were analyzed quantitatively by infrared spectroscopy to determine, during the reaction, the conversion and the mole fractions of each monomer in the mixture, the composition of the copolymer being obtained by the consumption of the monomers. Very different reactivity ratios were obtained (rstyrene = 49.926 and rVeoVa10 = 1.062), showing that the batch copolymerization of these monomers leads to large composition drift, with a tendency to form two homopolymers. The same copolymerization system was also tested in emulsion polymerization process, in semi-continuous and intermittent batch modes. The overall conversion of the monomers and the mean particle diameter distribution were analyzed during the reaction through the samples collected throughout the process. The effects of the feeding strategies evaluated were only preliminary, as they did not present conclusive results.
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Starke, Sandra. "Multifunktionale (Meth)acrylat-Copolymere mit Phosphonsäurederivaten." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-189936.
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Ziel der Doktorarbeit war es, Copolymere mit phosphonsäurehaltigen Seitenketten zu entwickeln, die nachfolgend über polymeranaloge Umsetzungen in Terpolymere mit polymerisationsfähgen Gruppen umgewandelt werden sollten. Die Terpolymere können dann somit im Bereich der Schicht,- Lackindustrie eingesetzt werden.
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Khayat, Raymond. "Ingénierie macromoléculaire de polymères électroactifs fluorés." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0192.
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Les co-polymères et ter-polymères dérivés du poly(fluorure de vinylidène) ont suscité un intérêt croissant au cours des dernières années en raison de leur combinaison unique de haute électroactivité et d'excellentes propriétés mécaniques et chimiques. Cette étude vise à optimiser la conception de ces matériaux, en particulier du P(VDF-TrFE-CTFE) de type relaxeur-ferroélectrique, en renforçant le contrôle de leur architecture macromoléculaire. Deux stratégies ont été examinées pour améliorer les propriétés du terpolymère. La première stratégie implique le contrôle du séquençage des monomères lors de la terpolymérisation. Pour atteindre cet objectif, les rapports de réactivité des monomères pour la terpolymérisation du VDF, TrFE, et CTFE ont été déterminés, notamment à l’aide d’approches binaires et ternaires. Ces rapports de réactivités ont ensuite étés intégrés dans un modèle théorique simulant la réaction de polymérisation. En utilisant ce modèle, divers paramètres, tel que les taux d'alimentation en monomères, ont été optimisés pour ajuster les propriétés et l’homogénéité du terpolymère. L'issue de ces travaux se manifeste par l'obtention d'un polymère doté d'une distribution de composition plus homogène, offrant une cristallinité et permittivité relative augmentée, ainsi qu'un caractère relaxeur-ferroélectrique plus marqué. La seconde stratégie implique la fonctionnalisation du P(VDF-TrFE-CTFE) pour améliorer son comportement diélectrique. Cette approche comprend deux étapes : la première consiste à introduire des doubles liaisons sur le squelette polymérique à l’aide d’une base telle que l’éthylène diamine. La seconde étape consiste à utiliser ces doubles liaisons comme plateforme de fonctionnalisation pour une modification précise de l'architecture du polymère. En particulier, la réaction d’époxidation des doubles liaisons avec le mCPBA suscite un intérêt particulier au vu de l’amélioration significative des propriétés diélectriques observée, se manifestant par une augmentation de la permittivité relative et de la polarisation maximale, ainsi qu’une réduction de la polarisation rémanenteCo- and ter-polymers based on vinylidene fluoride have gained increasing attention in recent years owing to their unique combination of high electroactivity and excellent mechanical and chemical properties. Further advance in the design of these remarkable materials, and in particular for the relaxor-type P(VDF-TrFE-CTFE), is foreseen by an enhanced control of their macromolecular architecture. In this work, two strategies were investigated to enhance the functional properties of P(VDF-TrFE-CTFE). Firstly, an extended control of monomer sequencing during polymerization was pursued in order to improve the polymer homogeneity and final electroactive properties. To achieve this, the monomer reactivity ratios for VDF, TrFE, and CTFE terpolymerization were determined using diverse methodologies, including binary and ternary system approaches. These ratios were then implemented in a theoretical treatment to simulate the polymerization reaction. Utilizing this model, various parameters, including the monomer feeding rates, were optimized to achieve precise control over polymerization, resulting in polymers with narrower composition distributions. This refinement in composition homogeneity led to optimized polymer properties, including increased crystallinity, higher dielectric constant, and a more pronounced relaxor ferroelectric behavior. Secondly, a chemical post-modification strategy was employed to improve the dielectric behavior of P(VDF-TrFE-CTFE). This approach involved a two-step functionalization process. The initial step introduced double bonds on the polymer backbone using a base, such as ethylene diamine, following a dehydrochlorination mechanism. Subsequently, the formed "double bond" platform served as a site for precise post-modification of the P(VDF-TrFE-CTFE) architecture. A successful modification involved the reaction of the double bonds with mCPBA following an epoxidation reaction. This approach resulted in a significant improvement in dielectric properties, manifesting as higher relative permittivity, increased maximum polarization, and reduced remanent polarization
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Rivard, Tony. "Reactivity ratio estimation: Two case studies." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6388.
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Two separate case studies on polymerization kinetics were performed. These studies focused on the determination of reactivity ratios: important copolymerization kinetic parameters. They are used to predict multicomponent polymer composition directly and have an indirect influence on the prediction of polymerization rate and final properties. In some cases, these parameters can be very difficult to obtain using standard techniques. These standard methods involve low conversion experiments and measurement of the final polymer composition. The goal of the first study was to determine the reactivity ratios of a copolymer system that presents significant experimental challenges. The study involved a small polymer chain, called a macromonomer copolymerized with acrylic or methacrylic acid monomers. The second case study involved the styrene/butyl acrylate copolymer system. Firstly, the reactivity ratios were estimated in bulk and in toluene solution. Gel permeation chromatography (GPC) was used to determine the weight-average molecular weight of selected styrene/butyl acrylate copolymer samples. An additional investigation focused on the use of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry was completed. (Abstract shortened by UMI.)
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Tang, Chau N. "Copolymerization and Characterization of Vinylaromatics with Fluorinated Styrenes." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1207773730.
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Double, Kit Spenser. "Reactivity to Confidence Ratings During Reasoning and Problem Solving." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18588.
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Confidence ratings are one of the most frequently used measures of metacognition. Is has traditionally been assumed that confidence ratings can be elicited from individuals without affecting their underlying cognitive and metacognitive processes. Recently, research has challenged this assumption by demonstrating changes in cognitive performance in reaction to providing self-report measures of metacognition, so-called reactivity. The purpose of this thesis was to extend these findings by examining reactivity to confidence ratings in reasoning and problem-solving tasks. After introducing theory relevant to metacognition and reactivity in Chapter 1, Chapter 2 provides a meta-analysis of reactivity to judgements of learning. This meta-analysis indicated that positive reactivity (a facilitation of cognitive performance) occurs in response to related, but not unrelated word-pairs. Chapter 3 presents one of the first empirical studies of reactivity to confidence ratings, demonstrating that confidence ratings benefit performance on an IQ test, but reactivity is moderated by trait-like self-confidence. In Chapter 4 the effect of eliciting confidence ratings on metacognitive monitoring and control is examined. The results show that collecting confidence ratings impairs metacognitive monitoring. Additionally, metacognitive control is affected, in that confidence ratings prompt participants to focus on short-term performance, rather than long-term performance. Chapter 5 shows that the word ‘confident’ may prime pre-existing beliefs about one’s competence, which results in reactivity effects. Finally, Chapter 6 evaluates reactivity to prospective confidence ratings. The results indicate that eliciting prospective confidence ratings facilitates performance on a cognitive task. Implications for the measurements of metacognition and the use of confidence ratings in research, as well as the potential use of confidence ratings as an educational intervention are discussed in Chapter 7.
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Quaglio, Ana Elisa Valencise [UNESP]. "HSP70, heparanase e HPRT participam da resposta inflamtória intestinal induzida por TNBS em ratos." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/91646.
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A Doença Inflamatória Intestinal (DII) engloba, fundamentalmente, duas doenças distintas: a Doença de Crohn (DC) e a Retocolite Ulcerativa (CU), ambas caracterizadas por uma inflamação crônica do intestino, com períodos de exacerbação seguidos de intervalos prolongados de remissão dos sintomas. Apesar da DII ser objeto de pesquisa há várias décadas, a sua etiologia ainda é desconhecida e a principal limitação no entendimento dos mecanismos fisiopatológicos desta doença é a disponibilidade de modelos experimentais adequados que mimetizem o caráter crônico e de recidiva da DII em humanos e que possam ser de baixo custo, reprodutível, fácil de induzir e que apresente características clínicas e histopatológicas, respostas terapêuticas e mediadores inflamatórios similares ao que ocorre com a doença em humanos. Dentre os vários modelos experimentais disponíveis, o modelo de colite induzida por ácido trinitrobenzenosulfônico (TNBS) em ratos tem sido considerado o mais adequado para a avaliação de novos fármacos, assim como aquele que melhor mimetiza esta doença em humanos. Assim sendo, a caracterização do papel de diferentes mediadores do processo inflamatório intestinal neste modelo permitiria a determinação de novos alvos terapêuticos, assim como geraria informações importantes da fisiopatologia desta doença. Neste sentido, o presente projeto teve como objetivo determinar a participação da HSP70, Heparanase e HPRT, mediadores do processo inflamatório intestinal em humanos, na fase aguda do processo inflamatório intestinal induzido TNBS em ratos, assim como estudar os efeitos de fármacos das três principais classes farmacológicas usadas no tratamento da DII em humanos, os aminossalicilatos (sulfassalazina), os glicocorticóides (prednisolona) e os imunomoduladores (azatioprina) sobre esses mediadores. Este estudo demonstrou que HSP70, Heparanase...
The idiopatic inflammatory bowel diseases comprise two types of chronic intestinal disorders: Crohn’s disease and ulcerative colitis that are characterized by a chronic inflammation of the intestine, with periods of remission and reactivation of the inflammatory process. Although IBD is the subject of research for several decades, its etiology remains unknown, and the major limitation to understanding the IBD pathophysiology is the availability of experimental models that mimic the chronic and relapse of human IBD. Is still important that experimental models can be inexpensive, reproducible, easy to induce and present clinical and histopathological features, therapeutic responses and inflammatory mediators similar to what occurs in humans. Among experimental models available, the model of colitis induced by trinitrobenzenesulphonic acid (TNBS) in rats has been considered the most suitable for the evaluation of new drugs, as well as the one that best mimics the disease in humans. Therefore, the involvement of different IBD mediators in this experimental model would allow the determination of new therapeutic targets, as well as generate important information on the pathophysiology of this disease. In light of this, the aim of present study was to determine the participation of HSP70, Heparanase and HPRT, mediators of intestinal inflammatory process in humans, in acute phase of inflammatory process induced by TNBS in rats, as well as, to study the effects of drugs of the three main classes used in the treatment of human IBD, i.e., aminosalicylates (sulphasalazine), glucocorticoids (prednisolone) and immunomodulators (azathioprine) on these mediators. This study showed that HSP70, Heparanase and HPRT participate as mediators of intestinal inflammation induced by TNBS since these mediators are increased in colitic animals when compared to healthy animals... (Complete abstract click electronic access below)
Books on the topic "Reactivity ratios"
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Balog, Daniel J., Robert Koffman, and Joseph M. Helms. Acupuncture. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190205959.003.0006.
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People who acquire posttraumatic stress disorder (PTSD) after experiencing a traumatic event endure a constellation of debilitating symptoms, including intrusion, avoidance, negative mood alteration, and marked increases in reactivity. They have difficulty falling or staying asleep, and often have comorbid physical and pain-related diagnoses secondary to their trauma. Despite evolving definitions and measures, estimates of prevalence of lifetime PTSD in U.S. population have remained quite consistent since the advent of theDiagnostic and Statistical Manual of Mental Disorders(DSM), third edition, revised (III-R). In civilian populations, lifetime DSM-III-R PTSD prevalence rates of 9.2%; DSM, fourth edition, PTSD prevalence rates of 6.8%; and DSM, fifth edition, PTSD estimate rates of 5.4% have been reported. In U.S. military populations, prevalence rates as high as 17% after combat deployments have been reported. Importantly, persons with PTSD experience higher prevalence of other psychiatric and physical comorbid conditions, including mood, substance use, and pain disorders.
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Richebé, Philippe, and Cyril Rivat. The effects of morphine on the CNS. Edited by Paul Farquhar-Smith, Pierre Beaulieu, and Sian Jagger. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198834359.003.0017.
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The 1973 paper by Jacquet and Lajtha, was a pivotal report in understanding the effects of opioids on nociception, as it investigated the effects of morphine on different brain structures. To do this, the authors used a microinjection technique that allowed them to specifically target subcortical sites. The animals used in this study were rats, and evaluation of the nociceptive threshold was based on the behavioural reaction to electrical shock. Two reactions were evaluated: flinch or jump responses. The main result was that, depending on the dose and the site of injection, morphine produced either an increase in nociceptive threshold (analgesia), or a decrease in the nociceptive threshold (hyperalgesia). The authors also reported severe effects characterized by hyper-reactivity and violent uncontrolled jumping in stereotyped circular leaps when morphine was administered in the periaqueductal grey matter.
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Moerdler, Scott, and Xingxing Zang. PD-1/PDL-1 Inhibitors as Immunotherapy for Ovarian Cancer. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190248208.003.0010.
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Programmed death 1 (PD-1), a member of the B7-CD28 immunoglobulin superfamily, and its ligands PD-L1/PD-L2 inhibit T-cell activation. They also play a key role in the tumor microenvironment, allowing for cancer immune escape. PD-1 is induced on a variety of immune cells, including tumor-infiltrating lymphocytes (TILs), while PD-L1 is found on many types of solid tumors including ovarian cancer and some TILs. The use of immunocheckpoint inhibitors like anti-PD-1 and anti-PD-L1 therapies has been shown to reactivate the immune system to attack tumor cells. Ovarian cancers have been shown to be responsive to anti-PD-1 and anti-PD-L1 therapies, though immunocheckpoint inhibitors are not enough. Current research is evaluating combination therapies to improve response rates.
Book chapters on the topic "Reactivity ratios"
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Hagiopol, Cornel. "Estimation of Reactivity Ratios." In Copolymerization, 19–100. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4183-7_2.
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Mayr, H. "Rate Constants and Reactivity Ratios in Carbocationic Polymerizations." In Ionic Polymerizations and Related Processes, 99–115. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4627-2_7.
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Heuts, Johan P. A., Michelle L. Coote, Thomas P. Davis, and Lloyd P. M. Johnston. "The Measurement and Meaning of Radical Reactivity Ratios." In ACS Symposium Series, 120–44. Washington, DC: American Chemical Society, 1998. http://dx.doi.org/10.1021/bk-1998-0685.ch008.
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Siah, Lay-Foong, V. G. Kumar Das, and Seng-Neon Gan. "Copolymerisation of Substituted Tributyltin Cinnamates with Styrene. Syntheses, Reactivity Ratios, Relative Reactivities, NMR and Mössbauer Assignments and Thermal Analysis." In Main Group Elements and their Compounds, 267–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-52478-3_25.
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Du, Z., A. F. Sarofim, J. P. Longwell, and L. Tognotti. "The CO/CO2 Ratio in the Products of the Carbon-Oxygen Reaction." In Fundamental Issues in Control of Carbon Gasification Reactivity, 91–106. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3310-4_5.
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Fyfe, C. A., H. Grondey, Y. Feng, H. Gies, and G. T. Kokotailo. "The Impact of NMR Spectroscopy in Molecular Sieve Characterization -I: Low SI/Al Ratio Materials." In Zeolite Microporous Solids: Synthesis, Structure, and Reactivity, 225–45. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2604-5_11.
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Dove, P. M. "Chapter 6. KINETIC AND THERMODYNAMIC CONTROLS ON SILICA REACTIVITY IN WEATHERING ENVIRONMENTS." In Chemical Weathering Rates of Silicate Minerals, edited by Arthur F. White and Susan L. Brantley, 235–90. Berlin, Boston: De Gruyter, 1995. http://dx.doi.org/10.1515/9781501509650-008.
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Ulrichs, K. "Characterization of Pancreas Islet-Cell Reactivity with Various Immune Sera." In Microsurgical Models in Rats for Transplantation Research, 215–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-61657-0_35.
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Kaplan-Trahan, A. C., A. P. Belian, M. Croce, D. C. Henzlova, P. Jansson, G. Long, G. E. McMath, et al. "Spent Fuel Measurements." In Nondestructive Assay of Nuclear Materials for Safeguards and Security, 605–37. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-58277-6_21.
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AbstractThis chapter describes the methods used to measure spent nuclear fuel. The first section describes the properties of typical reactor fuel: geometry, burnup, initial enrichment, and cooling time. Neutron multiplication in the assembly is discussed. The measurement methods are divided into gamma-based methods, neutron-based methods, and other methods. A particularly important gamma-based method is passive gamma emission tomography. The neutron-based methods range from the relatively simple passive neutron fork, passive neutron albedo reactivity and differential dieaway to the complex active methods. The other methods are Cerenkov viewing devices, curium/plutonium ratio and calorimetry.
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Saxena, Mohit Raj, and Rakesh Kumar Maurya. "Impact of Fuel Premixing Ratio and Injection Timing on Reactivity Controlled Compression Ignition Engine." In Combustion for Power Generation and Transportation, 277–96. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-3785-6_13.
Full textConference papers on the topic "Reactivity ratios"
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Safari, Habibollah, and Mona Bavarian. "Enhancing Polymer Reaction Engineering Through the Power of Machine Learning." In Foundations of Computer-Aided Process Design, 367–72. Hamilton, Canada: PSE Press, 2024. http://dx.doi.org/10.69997/sct.157792.
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Copolymers are commonplace in various industries. Nevertheless, fine-tuning their properties bears significant cost and effort. Hence, an ability to predict polymer properties a priori can significantly reduce costs and shorten the need for extensive experimentation. Given that the physical and chemical characteristics of copolymers are correlated with molecular arrangement and chain topology, understanding the reactivity ratios of monomers�which determine the copolymer composition and sequence distribution of monomers in a chain�is important in accelerating research and cutting R&D costs. In this study, the prediction accuracy of two Artificial Neural Network (ANN) approaches, namely, Multi-layer Perceptron (MLP) and Graph Attention Network (GAT), are compared. The results highlight the potency and accuracy of the intrinsically interpretable ML approaches in predicting the molecular structures of copolymers. Our data indicates that even a well-regularized MLP cannot predict the reactivity ratio of copolymers as accurately as GAT. This is attributed to the compatibility of GAT with the data structure of molecules, which are graph-representative.
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Takeda, Satoshi, Takanori Kitada, Eiji Hoashi, and Takafumi Okita. "Evaluation of Expansion Reactivity Based on Reactivity Coefficient for Sodium-Cooled Fast Reactor." In 2024 31st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/icone31-132277.
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Abstract In this paper, formulas for evaluating expansion reactivity based on reactivity coefficients in sodium-cooled fast reactors are derived, and the approximation errors used in the derivation are also evaluated. This research provides formulas for both Z-axis expansion reactivity and radial expansion reactivity. These reactivities are separated into the effect of change in geometric shape and that of change in the cross-section. Since the major approximation in the present derivation is the separation of effects due to geometric shape changes and cross-sectional area changes, the approximation error due to this separation was evaluated using results of neutron transport calculations for fast reactor. This evaluation was performed for two geometries with different ratios of the reactor core’s height to diameter. The results show that the approximation error is less than 20 pcm. Therefore, it can be expected that expansion reactivity can be accurately evaluated using reactivity coefficients.
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Hariharan, Deivanayagam, Brian Gainey, Ziming Yan, Sotirios Mamalis, and Benjamin Lawler. "Experimental Study of the Effect of Start of Injection and Blend Ratio on Single Fuel Reformate RCCI." In ASME 2019 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/icef2019-7208.
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Abstract A new concept of single-fuel RCCI has been proposed through the catalytic partial oxidation reformation of diesel fuel. The reformed fuel mixture is then used as the low reactivity fuel and diesel itself is used as the high reactivity fuel. In this paper, two selected reformates mixture from the reformation of diesel were selected for further analysis. Each reformate fuel mixture contained a significant fraction of inert gases (89% and 81%). The effects of the difference in the molar concentrations of the reformate mixtures were studied by experimenting with diesel as the direct injected fuel in RCCI over a varying start of injection timings and different blend ratios (i.e., the fraction of low and high reactivities fuels). The reformate mixture with the lower inert gas concentration had earlier combustion phasing and shorter combustion duration at any given diesel start of injection timing. The higher reactivity separation between reformate mixture and diesel, compared with gasoline and diesel, causes the combustion phasing of reformate-diesel RCCI to be more sensitive to the start of injection timing. The maximum combustion efficiency was found at a CA50 before TDC, whereas the maximum thermal efficiency occurs at a CA50 after TDC. The range of energy-based blend ratios in which reformate-diesel RCCI is possible is between 25% and 45%, limited by ringing intensity (RI) at the low limit of blend ratios, and COV of IMEP and combustion efficiency at the high limit. Intake boosting becomes necessary due to the oxygen deficiency caused by the low energy density of the reformate mixtures as it displaces intake air.
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Nishimura, Satoshi, Hirokazu Ohta, and Nobuyuki Ueda. "Analytical Evaluation of Core Bowing Reactivity in the 4S Reactor." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75223.
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The 4S (super-safe, small and simple) reactor is a sodium-cooled small fast reactor. The core reactivity is controlled by moving the reflectors installed around the core, and the reactor has a fixed absorber at the core center to accomplish a long core lifetime. To evaluate core bowing behavior and the resulting reactivity feedback in the 4S reactor, an analytical evaluation was conducted under various core power to flow ratios (P/F). The core bowing reactivity under the BOC (beginning of core life) condition becomes increasingly negative with increasing P/F up to 2.0, then becomes less negative with increasing P/F from 2.0 to 3.0, and finally becomes positive at P/F = 3.0. The bowing reactivity under the EOC (end of core life) condition becomes increasingly negative with increasing P/F up to 1.5, then becomes less negative then positive with increasing P/F from 1.5 to 3.0; the core bowing reactivity is positive when P/F ≥ 2.0. These results are mainly caused by the following two mechanisms originating from the structural characteristics of the 4S reactor: - a decrease in neutron absorption by the fixed absorber due to the radial displacement of the inner core subassemblies (under the BOC condition); - a decrease in neutron streaming caused by the small gaps between the outer core subassemblies and the reflectors due to core radial expansion (under the EOC condition).
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Guethe, Felix, Marta de la Cruz Garci´a, and Andre´ Burdet. "Flue Gas Recirculation in Gas Turbine: Investigation of Combustion Reactivity and NOX Emission." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59221.
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Flue gas recirculation (FGR) is a promising technology for the optimization of post-combustion CO2 capture in natural gas combined cycle (NGCC) plants. In this work, the impact of FGR on lean gas turbine premix combustion is predicted by analytical and numerical investigations as well as comparison to experiments. In particular the impact of vitiated air condition and moderate increase of CO2 concentration into combustion reactivity and NOx emission is studied. The influence of inlet pressure, temperature and recirculated NOx are taken as parameters of this study. Two different kinetic schemes are used to predict the impact that FGR has on the combustion process: the GRI3.0 and the RDO6_NO, which is a newly compiled mechanism from the DLR Stuttgart. The effects of the FGR on the NOx emissions are predicted using a chemical reactor network including unmixedness as presumed probability density function (PDF) to account for real effects. The magnitude and ratio of prompt to post-flame thermal NOx changes with the FGR-ratio producing less post flame NOx at reduced O2 content. For technical mixtures (i. e. an industrial fuel injector), NOx emission can be expected to be lower with the vitiation of the oxidizer. This is due to several effects: at low O2 concentration, the highest possible adiabatic flame temperatures for stoichiometric conditions decreases resulting in lower NOx when averaged over all mixing fractions. Further effects result from lower post flame NOx production and the role of “reburn” chemistry, actually reducing NOx (recirculated from the exhaust), which might become relevant for the high recirculation ratios, where parts of the flame would operate at rich stoichiometry at given unmixedness. Therefore in general for each combustor technical mixing could decrease NOx with respect to perfect mixing at high FGR-ratio assuming the engine can still be operated. Although the findings are quite general for gas turbines the advantage that reheat engines have in terms of operation are highlighted. For reheat engines this can be understood as an extension of the “reheat concept” and used as the next step in the goal to achieve minimal emissions at increasing power. In addition, NOx emission obtained in FGR combustion reduces even further when the engine pressure ratio increases, making the concept particularly well suited for reheat engines.
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Hsieh, Chang-Lung, Hao-Tzu Lin, Show-Chuyan Chiang, Chunkuan Shih, Jong-Rong Wang, and Tung-Li Weng. "LAPUR5.2 BWR Stability Analysis in Chinshan Nuclear Power Plant." In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89587.
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Boiling water reactors have the unique coupling mechanisms between neutronic and two-phase flow thermal-hydraulic behaviors and may induce instability by unstable power/flow oscillations. At each core reload design, it is important to employ decay ratio for the purpose of analyzing system stability and determining its operating boundary. Making use of LAPUR5.2 and SIMULATE-3 codes, we have established a methodology to conduct such analysis. Comparisons made with vendor’s STAIF results indicated good agreements in decay ratios for Chinshan Nuclear Power Plant Unit 2 Cycle 21 reload design. This research focuses on the parametric sensitivity effect on the variation of decay ratio for different power/flow operating points. Based on the result of sensitivity studies, we presented fractional changes of decay ratios by varying certain important parameters under different power/flow points. It is concluded that density reactivity coefficient, gap conductance and recirculation loop gain on high operating power/flow points have larger fractional change of decay ratio.
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Mueller, Florian, and Michael Guenthner. "Comparison of Premixed Fuel and Premixed Charge Operation for Propane-Diesel Dual-Fuel Combustion." In 16th International Conference on Engines & Vehicles. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-24-0059.
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<div class="section abstract"><div class="htmlview paragraph">With the rising popularity of dual-fuel combustion, liquefied petroleum gas (LPG) can be utilized in high-compression diesel engines. Through production from biomass (biomass to liquid, BtL), biopropane as a direct substitute for LPG can contribute to a reduction in greenhouse gas emissions caused by combustion engines. In a conventional dual-fuel engine, the low reactivity fuel (LRF) propane is premixed with the intake air to form a homogeneous mixture. This air-fuel mixture is then ignited by the high reactivity fuel (HRF) in the form of a diesel pilot injection inside the cylinder. In the presented work, this premixed charge operation (PCO) is compared to a method where propane and diesel are blended directly upstream of the high-pressure pump (premixed fuel operation, PFO) in variable mixing ratios for different engine loads and speeds. Furthermore, the effects of internal and external exhaust gas recirculation are investigated for each operating mode. The results show that PCO allows higher propane ratios of up to 75 % at low loads, while PFO enables higher percentages of propane at medium and high loads (up to 50 %), allowing for a “reactivity on demand” approach. In addition, PFO shows significantly lower emissions of unburned hydrocarbons (-98.3 %) and carbon monoxide (-94.6 %) compared to PCO while soot emissions are reduced in both cases. The use of EGR allows nitrogen oxide emissions to be lowered to similar levels for both operation modes and shows benefits concerning unburned hydrocarbon (-73.5 %) and carbon monoxide (-62.9 %) emissions in PCO.</div></div>
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Ekoto, Isaac W., Benjamin M. Wolk, William F. Northrop, Nils Hansen, and Kai Moshammer. "Tailoring Charge Reactivity Using In-Cylinder Generated Reformate for Gasoline Compression Ignition Strategies." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9458.
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In-cylinder reforming of injected fuel during an auxiliary negative valve overlap (NVO) period can be used to optimize main-cycle combustion phasing for low-load Low-Temperature Gasoline Combustion, where highly dilute mixtures can lead to poor combustion stability. The objective of this work is to examine the effects of reformate composition on main-cycle engine performance for a research gasoline. A custom alternate-fire sequence with nine pre-conditioning cycles was used to generate a common exhaust temperature and composition boundary condition for a cycle-of-interest. Performance metrics such as main-period combustion stability and total cycle efficiency were collected for these custom cycles. The NVO-produced reformate stream was also separately collected using a dump valve apparatus and characterized in detail using both gas chromatography and photoionization mass spectroscopy. To facilitate gas sample analysis, sampling experiments were conducted using a five-component gasoline surrogate (iso-octane, n-heptane, ethanol, 1-hexene, and toluene) that matched the molecular composition, 50% boiling point, and ignition characteristics of the research gasoline. For the gasoline, it was found that the most advanced NVO start-of-injection (SOI) led to the most advanced main-cycle 10% burn angle. The effect was more pronounced as the fraction of total fuel injected in the NVO period increased. With the most retarded NVO SOI, shorter residence times and piston spray impingement limited the opportunity for injected fuel decomposition. For the gasoline surrogate, the most advanced NVO SOI had reduced reactivity relative to more intermediate NVO SOI, which was attributed to rapid in-cylinder mixing that led to a large amount of fuel quench in the piston crevice. For all NVO periods, combustion phasing advanced as the main-period fueling decreased. Slower kinetics for leaner mixtures were offset by a combination of increased bulk-gas temperature from higher charge specific heat ratios and increased fuel reactivity due to higher charge reformate fractions.
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Jahanbin, Ali, and Mehrdad Boroushaki. "Development of a Software for Calculation of Kinetic Parameters of PWR Reactors." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30160.
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In this research, new software package for neutronic calculations, especially kinetic parameters of PWR reactors, has been developed. The program used to link the WIMS-D5, BORGES and CITVAP nuclear codes has been written in Visual C# programming language. This software was used for calculation of kinetic parameters of WER-1000 and NOK Beznau reactors. The ratios (βeff)i/(βeff)core of parameters, which are an important input data for the reactivity accident analysis, were also calculated. The results were compared with final safety analysis report (FSAR) and published documents.
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Ding, Haoran, Yongqing Xu, Linyi Xiang, Qiyao Wang, Cheng Shen, Cong Luo, and Liqi Zhang. "Synthesis of CeO2 Supported BaCoO3 Perovskites for Chemical-Looping Methane Reforming to Syngas and Hydrogen." In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3246.
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In order to reduce the hotspots in partial oxidation of methane, CeO2 supported BaCoO3 perogvskite-type oxides were synthesized using a sol-gel method and applied in chemical-looping steam methane reforming (CL-SMR). The synthesized BaCoO3-CeO2 was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS results suggested that the obtained BaCoO3 was pure crystalline perovskite, its crystalline structure and lattice oxygen could regenerate after calcining. The reactivity of perovskite-type oxides in CL-SMR was evaluated using a fixed-bed reactor. Gas production rates and H2/CO ratios showed that the optimal reaction temperature was about 860 °C and the properly reaction time in fuel reactor was about 180s when Weight Hourly Space Velocity (WHSV) was 23.57 h−1. The syngas production in fuel reactor were 265.11 ml/g, hydrogen production in reforming reactor were 82.53 ml/g. (CSPE)
Reports on the topic "Reactivity ratios"
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Moore, Brian, Timothy Haddad, Rene Gonzalez, and Constance Schlaefer. Reactivity Ratios of Isobutyl POSS-Styrene and Styrene Monomers. Fort Belvoir, VA: Defense Technical Information Center, March 2004. http://dx.doi.org/10.21236/ada422517.
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Linker, Taylor, and Timothy Jacobs. PR-457-18204-R02 Variable Fuel Effects on Legacy Compressor Engines Phase V Engine Control Enhancement. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), July 2020. http://dx.doi.org/10.55274/r0011729.
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Variations in natural gas composition not only change bulk properties like heating value and adiabatic flame temperature, but also affect the reactivity of the gas during combustion in legacy compressor engines. Gas blends with high amounts of non-methane hydrocarbons are more reactive and alter combustion phasing in ways which can negatively affect engine operation and NOx emissions. These issues have and will continue to become more prevalent as natural gas production continually shifts towards shale resources. This work investigates the impacts of changing fuel composition on engine operation and emissions, as well as on fundamental fuel properties. Several fuel sweep datasets from different legacy engines are used to help draw broad conclusions about the impact of fuel speciation depending on engine type and operating condition. Further, the relationship between this engine behavior and fundamental fuel properties is explored. The response of engine operation and emissions to changing fuel reactivity is also observed in the context of the trapped equivalence ratio control method. A correction to the method which accounts for fuel reactivity effects on NOx is proposed and assessed with available data.
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Hedrick and Jacobs. PR-457-14201-R01 Variable Natural Gas - Composition Effects and Control Methods for Two-Stroke Engines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 2015. http://dx.doi.org/10.55274/r0010027.
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Literature is reviewed for the impacts of variable natural gas composition on two-stroke lean burn pipeline compressor engines. Information gathered for these engines can be simplified for development of control algorithms in four-stroke and richer burning engines. Data shows that geospatial, geological, and transient hydraulic effects cause composition variations that adversely affect engine emissions, efficiency, rated performance, and operational safety considering auto-ignition effects. In order to compensate for these changes in composition, better engine control schemes can help meet desired performance goals. For specific gas compositions combusting at a fixed air-fuel ratio, the laminar flame speed, adiabatic flame temperature, and ignition delay relate to and allow the prediction of the mixture�s reactivity, thermal availability, and auto-ignition tendency. Predicting changes in these combustion parameters, as caused by changes in fuel composition, is essential to the success of control development for variable composition engine operation. In addition to addressing the associated combustion effects resulting from variable fuel composition, an overview of sensor technologies is presented for use in control applications.
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Cao, Yan, and Yousry Gohar. Numerical Studies of the On-Line Reactivity Monitoring Techniques in Subcritical Systems: Revisit of the Area-Ratio Method, the Neutron Source-Modulation Method, and the Flux-to-Current Ratio Method. Office of Scientific and Technical Information (OSTI), August 2023. http://dx.doi.org/10.2172/1998585.
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Stone, A. T. Reductive mobilization of oxide-bound metals: The role of reductant capacity and reductant reactivity in determining mobilization rates in soils and sediments. Office of Scientific and Technical Information (OSTI), October 1990. http://dx.doi.org/10.2172/6161755.
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Shenker, Moshe, Paul R. Bloom, Abraham Shaviv, Adina Paytan, Barbara J. Cade-Menun, Yona Chen, and Jorge Tarchitzky. Fate of Phosphorus Originated from Treated Wastewater and Biosolids in Soils: Speciation, Transport, and Accumulation. United States Department of Agriculture, June 2011. http://dx.doi.org/10.32747/2011.7697103.bard.
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Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.