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Viabilidade neutronica de um conjunto critico termico-rapido destinado ao estudo de envoltorios de reatores rapidosGUTIERREZ RODRIGUES, VALDEMIR 09 October 2014 (has links)
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Environmental and Cost impact Analysis of Materials and Assemblies in Building ConstructionNirmal, Deepika 30 March 2012 (has links)
One of the new trends in the building construction industry is designing for environmental-friendly buildings, a.k.a. Green Buildings. Planners and designers are therefore trying to accommodate these new environmental practices into existing design criteria. Selection of building materials is one of the key decisions need to be made by building designers. However, due to the strong influence of costs on the building industry, making material-selection decisions solely based on their environmental impacts could be both inadequate and impractical. These factors therefore complicate the building design process, especially pertaining to material selection.
Accordingly, the present study is aimed at providing much needed support to the decision-making process of residential building design. To this end, the study evaluates and analyzes the environmental and cost impacts of several building assemblies and material alternatives for the building exterior walls. The Technique of Order Preference Similar to Ideal Solution (TOPSIS) is used to evaluate and rank different material alternatives used in walls based on their environmental impacts. In addition, the environmental data used in this study were extracted from commonly used databases that considered the lifecycle impacts of different residential building materials and assemblies. The environmental and cost impacts of several exterior wall assemblies are then aggregated for different building material alternatives to allow for an objective comparison of these assemblies and facilitate proper building design decision- making. The study results show that wood and exterior insulation finishing system (EIFS) provided the best environmental performance of wall structural and wall finishing materials, respectively. This research is expected to prove useful in supporting building design decision- making. In addition, this research can improve pre-construction estimation and support screening of building materials.
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School assemblies: The purposes, practices, and values as perceived by principals in California public high schoolsYoung, Flora Ann Mae 01 January 1992 (has links) (PDF)
Purpose. The purpose of this study was to determine the current practices and perceptions of public high school principals in California with regard to school assemblies. It also investigated the relationship between each school's frequency of assemblies and the variables: school enrollment, dropout rate, minority enrollment, and school performance. Procedure. Principals of all public comprehensive high schools in California with a student enrollment of 1,100 or greater were surveyed by mail. Data collected were statistically analyzed to yield frequency, rank, means, and standard deviation. The variables were analyzed by a Pearson Product Moment Correlation. Findings. Analysis of the data indicates that students in California public high schools, as reported by 88.3% of the respondents, are interested or enthusiastic about school assemblies. According to the respondents, an average of four assemblies per year and one pep/sports rally per month were held. Principals indicated that building school unity/enhancing student and faculty relationships was ranked first among the purposes of the assembly program, and the greatest benefits of school assemblies were to provide student recognition, build relationships, increase multicultural appreciation, and develop good audience behavior. The lack of money, time, and assembly facilities was reported to be the greatest obstacles in presenting assemblies. Principals confirmed that there has been a trend towards fewer assemblies. Conclusions and recommendations. School assemblies are a valuable administrative tool for promoting school unity, recognizing students, and extending classroom learning. The obstacles of time, assembly funding, and inadequate assembly facilities can be overcome with skillful planning and by the utilization of resources within the school and community. School assembly development should be an integral part of teacher and administrator training at the universities and in the school districts. Recommendations for future research include: development of a school assembly model for implementation, organization, presentation, and evaluation of a yearlong school assembly program; a comparison study between schools that have well-designed assembly programs and schools that do not; the replication of this study for elementary and middle schools; a similar survey of students' and teachers' perceptions of school assemblies.
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Molecular Investigations of Protein Assemblies Involved in Prokaryotic VirulenceMancl, Jordan Michael 15 August 2019 (has links)
Protein complexes mediate a diverse range of behavior in prokaryotic cells, yet the exact molecular mechanisms explaining how many of these complexes assemble and function remain unknown. This work focuses on understanding the molecular mechanisms of two different protein assemblies responsible for regulating virulence in the opportunistic pathogen Pseudomonas aeruginosa. P. aeruginosa utilizes type IV pili (T4P) to adhere to, and move along, surfaces. Assembly of T4P is powered by a dedicated cytoplasmic ATPase, PilB. The structural study of PilB from a related system (chapter 2) resulted in the formulation of the first model describing the mechanism of force generation resulting from ATP hydrolysis, which explains how T4P are assembled. Chapter 3 focuses on the RetS/GacS interaction, which is responsible for globally regulating virulence in P. aeruginosa. A comprehensive structural study reveals a dynamics of a novel regulatory interaction and the discovery of a potentially universal transmembrane signaling mechanism. / Doctor of Philosophy / Bacteria have threatened human health since the beginning of recorded history. With the development of antibiotics in the early twentieth century, the threat posed by bacterial infection was greatly lessened. However, decades of antibiotic mismanagement has led to the evolution of bacteria which are no longer vulnerable to these antibiotics. In order to combat this rising threat of resistant bacteria, we require a deeper understanding of how bacteria function and cause disease. Proteins play a crucial role in the diseases caused by bacteria, either by directly damaging host cells or regulating the expression of these damaging factors. By increasing our knowledge of the roles played by protein during bacterial infections, it will be possible to create new antibiotics while minimizing the risk of resistance. The work presented here grants a deeper understanding into how proteins work together to allow bacteria to survive inside the human body.
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Convivência democrática na escola: em foco, as rodas de diálogo de professores / Democratic coexistence in school focusing on teachers’ assembliesZanini, Maria Estela Benedetti 22 October 2018 (has links)
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Previous issue date: 2018-10-22 / This work is an engaged qualitative research whose objective was to describe and analyze the process of implementation and development of the teachers’ and managers’ assemblies in Colégio Bandeirantes. In this study, teachers' assemblies were analysed from their inception, in May 2017, until June 2018, in a total of ten meetings. Data analysis was carried out based on the collection, study and interpretation of the documents related to this process, the agenda/themes proposed for discussion in the teachers’ assemblies and the minutes of each assembly. The twenty-five themes that were proposed were organized in categories, a posteriori, using objective criteria, at the discretion of the researcher. In order to obtain the participation of a greater number of teachers, an open online platform (DemocracyOS) was used in the preparation of the agendas, which enabled the posting and voting of the themes to be discussed in each assembly. The teachers’ assemblies at Colégio Bandeirantes are part of a Positive Coexistence Plan that is being developed in the school and is organized in several interconnected and complementary actions involving teachers, managers, students and employees. The theorical references for this work were L. R. Almeida, U. F. Araújo, J. M. Puig, T. P. Vinha e L. R. P. Tognetta. It is believed that the assemblies are spaces for the resolution of conflicts that take place in the school environment, once teachers have the opportunity to express themselves in relation to the issues on the agenda, to express their opinions about them and to suggest solutions, thus, being implicated in solving the problems. The implementation of the assemblies also enables the exercise of otherness and cooperation, as well as providing an environment in which the educator feels he is being heard and valued in his concerns and anguishes, which contribute to interpersonal relationships being more respectful and to school environment being of better quality / Este trabalho é uma pesquisa qualitativa engajada que teve como objetivo descrever e analisar o processo de implantação e desenvolvimento das rodas de diálogo de professores e gestores do Colégio Bandeirantes. Nesse estudo, foram analisadas as rodas de diálogo de professores desde sua implantação, em maio de 2017, até junho de 2018, totalizando 10 encontros. A análise de dados foi realizada a partir de levantamento, estudo e interpretação de documentos referentes a esse processo – as pautas/temas propostos para discussão nas rodas de professores e as atas de registro de cada um desses encontros. Os 25 temas apresentados na análise foram organizados em categorias, à posteriori, utilizando critérios objetivos, de autoria da pesquisadora. A fim de conseguir a participação de um maior número de professores utilizou-se, na elaboração das pautas dos encontros, uma plataforma online e aberta – DemocracyOS – que possibilitou a publicação e a votação dos temas discutidos nas rodas de diálogo. As assembleias docentes no Colégio Bandeirantes constituem parte de um Plano de Convivência Positiva que vem sendo desenvolvido na escola e é organizado em diversas ações, interligadas e complementares, que envolvem professores, gestão, alunos e funcionários. Os referenciais teóricos para este trabalho foram L. R. de Almeida, U. F. Araújo, J. M. Puig, T. P. Vinha e L. R. P. Tognetta. Acredita-se que as rodas de diálogo são espaços para a resolução de conflitos que acontecem no ambiente escolar, pois os professores têm a oportunidade de se manifestar em relação aos assuntos pautados, colocar suas opiniões a respeito e sugerir encaminhamentos e, dessa maneira, implicam-se na solução dos problemas. A implantação das rodas de diálogo de professores também possibilita o exercício de alteridade e cooperação, além de propiciar um ambiente no qual o educador sente-se ouvido e acolhido em suas dúvidas e angústias, o que contribui para que as relações interpessoais sejam mais respeitosas e para que o clima escolar seja de melhor qualidade
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Návrh robotizovaného pracoviště pro montáž kabelových svazků / Design of robotic cell for cable assemblyCikánek, Pavel January 2014 (has links)
This thesis is created in cooperation with ABB. The aim of this work is to design and implement technical modifications in an already existing robotic workplace where a production of cable assemblies is situated. These modifications are important so that the cable assemblies made by a robot would be confirmed by a production control. The work is divided into five parts. The first one is devoted to the analysis of a current state of a cable assembly production. In the second part the causes of a reject production are discussed. The third section describes some possible ways of corrections of problems connected with the workplace. The fourth part describes an implementation of selected technical modifications. In the last section used technical modifications are evaluated.
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Estudo da viabilidade neutronica de um conjunto subcritico de torioKOSAKA, NANAMI 09 October 2014 (has links)
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Designing Active Smart Features to Provide Nesting Forces in Exactly Constrained AssembliesPearce, Eric 07 May 2003 (has links) (PDF)
Ever since the design and manufacture of products moved from the craftsman era where individual craftsman designed and manufactured the entire product, to the mass production era, where skilled laborers were crafting interchangeable parts or in some cases single features on interchangeable parts, variation in assemblies has been a major concern to designers, manufacturers, and in a more subtle way, customers. Variation, in the end, affects quality, performance and the cost of products. One particular type of design that is particularly robust to variation is an exactly constrained design. Several researchers have recently explored the topic of exact constraint design. An exactly constrained design is one in which each degree of freedom is constrained by a single constraint until the desired degrees of freedom for the design is attained. One attractive advantage of exactly constrained designs is that they are robust to variation. However, exactly constrained designs often require nesting forces to maintain the configuration of the design. This research develops a method for designing features that will supply robust nesting forces such that the advantages of the exactly constrained design are preserved. The method developed in this work takes advantage of a proven method for tolerance analysis and enhances this method to include the analysis of these features that supply nesting forces. Along with the enhancement, principles are developed that aid this analysis. All the examples provided in this work are verified using comparisons to Monte Carlo simulations. The comparisons show good results, typically less than 2% difference from the Monte Carlo simulations, verifying that this method accurately predicts variation and allows for the robust design of features that supply the nesting forces in exactly constrained assemblies.
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Serendipitous Assembly Of 3d Metal-Ion Polyclusters : Structures, Magnetic Behavior And Theoretical StudiesMukherjee, Sandip 07 1900 (has links) (PDF)
The last two decades have seen extensive growth in interest in metal-ion assemblies, especially for building new polynuclear exchange-coupled magnetic systems. However, the concept of designing polynuclear extended structures has still not matured to the level of retro-synthetic approach developed for the organic and pharmacological molecules. Although some progress has been made with secondary building units (SBUs) in metal-organic-frameworks (MOFs), the control seems to be just an illusion when it comes to bridging ligands such as the azide ion. When it is asserted that the azido ligand is versatile in its bridging capabilities, what is actually meant is that it would be difficult to predict or control its bridging properties, or in other words, the azido based polynuclear complexes are difficult to pre-design. However, this kind of serendipity is not always bad news for the chemists. For example, the azido ligand has been shown to mediate magnetic exchanges between paramagnetic metals in a predictable fashion (usually depending upon the bonding geometries). Therefore, it is a well-respected ligand in polynuclear assemblies of paramagnetic ions. Serendipitous assemblies offer new magnetic structures that we may not otherwise even think about synthesizing. Similarly, there are other ligands, such as alkoxido, oximato, carboxylato etc. which also behave like azide. These ligands are very important in the study of magnetic exchanges to develop an understanding of the underlying mechanisms in molecular magnetism. Serendipitous assemblies have also led to systems like single molecule magnets (SMMs), which have enriched the field with potential applications in computing and have also been used for the confirmation of the quantum magnetic properties like tunneling phenomenon, spin decoherence etc.
Investigations incorporated in this thesis work led to several novel strategies for using serendipity as an advantage and build unprecedented structural topologies with interesting new molecular-magnetic properties. All the reported complexes were thoroughly analyzed through elemental analysis, spectroscopy, X-ray structure determination (both single crystal & powder diffractions) and variable temperature magnetic susceptibility measurements. In a few suitable cases, model structures obtained from the X-ray structures were also employed to study the magnetic exchange mechanisms through density functional theory (DFT) calculations and simulations.
CHAPTER 1 of the thesis presents a general review on the ever-growing field of metal-ion assembly. In particular, the importance of the ‘serendipitous approach’ to build new and interesting metal-ion clusters and polyclusters is highlighted. This chapter also describes the basic concepts of exchange-based molecular magnetism as applied to the metal-ion assemblies.
CHAPTER 2 describes the concept of using lower molar proportions of blocking bidentate chelating ligands in the neutral copper(II)-azido systems, which increases the number of coordination sites for the versatile azido bridges to assemble the metal-ions in higher dimensions, based on smaller cluster units. Syntheses, structures and magnetic properties of ten novel complexes are described in this chapter: [Cu3(tmen)2(N3)6]n (1), [Cu4(Me-hmpz)2(N3)8]n (2), [Cu4(men)2(N3)8]n (3), [Cu6(deen)2(N3)12]n (4), [Cu6(aem)2(N3)12]n (5), [Cu6(dmeen)2(H2O)2(N3)12]n (6), [Cu6(N,N'-dmen)2(N3)12]n (7), [Cu6(hmpz)2(N3)12]n (8), Cu5(N,N-dmen)2(N3)10]n (9), and [Cu5(N,N'-dmen)5(N3)10]n (10) [tmen = N,N,N',N'-tetramethylethylenediamine, Me-hmpz = 1-methylhomopiperazine, men = N-methylethylenediamine, deen = N,N'-diethylethylenediamine, aem = 4-(2-aminoethyl)morpholine, dmeen = N,N-dimethyl-N'-ethylethylenediamine, N,N'-dmen = N,N'-dimethylethylenediamine, hmpz = homopiperazine, N,N-dmen = N,N-dimethylethylenediamine].
Most of these complexes have simple oligonuclear basic building units (Scheme 1), such as trinuclear (1), tetranuclear (2, 3) and hexanuclear (4-8), but the overall arrangements of these cluster units in higher dimensions vary widely and serendipitously. For example, the hexanuclear complexes 4-7, although having almost identical basic structures, assemble in three- (4, 5) or two- (6, 7) dimensions with different connectivity among the basic structures. However, complex
9 is made from two different building units (Cu2 and Cu3). Complex 10, although having metal to blocking molar ratio 1:1, presents an unprecedented 1D structure for such complexes. Analysis of the magnetic susceptibility data for complexes 1-9 using theoretical exchange models for fitting is also described. Density functional theory (DFT, B3LYP) was employed to further analyze the experimental magnetic data for complexes 1, 2, 3 and 9 to better understand the magnetic exchange mechanisms in such systems.
CHAPTER 3 continues with the same concepts developed in the previous chapter using multidentate neutral and anionic co-ligands. Using lower molar proportions of these multidentate ligands, seven novel complexes have been synthesized (keeping the initial metal to ligand ratio as 2:1): [Cu4(L1)2(N3)8]n (11), [Cu4(L2)2(N3)8]n (12), [Cu4(L3)2(N3)8]n (13), [Cu4(L4)2(N3)8]n (14), [Cu9(L5)4(N3)18]n (15), [Cu4(L6)2(H2O)2(N3)6] (16) and [Cu4(L7)2(N3)6]n (17) [where L1-5 are the condensation products of 2-pyridinecarboxaldehyde and 2-{2-(methylamino)ethyl}pyridine (L1),
N,N-diethylethylenediamine (L2), N,N-dimethylethylenediamine (L3), N-methylethylenediamine (L4), N,N,2,2-tetramethylpropanediamine (L5); HL6 and HL7 are the condensation products of 2-hydroxy-3-methoxybenzaldehyde with N,N-diethylethylenediamine (HL6), and N-ethylethylenediamine (HL7)]. The ligand L1 is particularly interesting, as it is a hemiaminal ether (usually considered to be unstable intermediates in the reactions of aldehydes and secondary amines in alcoholic solvents), and was found to be trapped in 11. Although 11-13 have identical tetranuclear basic structures (with the rare simultaneous end-on and end-to-end bridges between two neighbouring metal-ions, Scheme 2) and extend in one-dimension. However, 13 is differently organized from the other two complexes. For 14, the bridging structure among the peripheral copper(II) ions changes to double end-on (Scheme 2), and the resulting structure extends in two dimensions. However, with L5, metal to ligand ratio is 9:4 (under similar conditions and initial molar proportions of the components) in 15, which can be seen as two different fragments: [Cu4(L5)4(N3)6]2+ and [Cu5(N3)12]2- linked alternately to give an overall 1D structure. HL6 and HL7 have one ionisable phenolic group that replaces one azido anion and generates two pockets for the metal atoms. These monoanionic ligands give tetranuclear complexes (16 and 17) with basic structures resembling (Scheme 2) to 11-14. While 17 is 1D in nature, two coordinated water molecules prevent the structure of 16 to grow and results in a discrete cluster.
The variable temperature magnetic properties of these complexes were thoroughly analyzed through experimental and theoretical (DFT) studies.
CHAPTER 4 reports the use of a pyridyl substituted propanediolate ligand in the assembly of two novel 1D heterometallic complexes: [Mn3Na(L)4(CH3CO2)(MeOH)2](ClO4)2∙3H2O (18) and [Mn3Na(L)4(CH3CH2CO2)(MeOH)2](ClO4)2∙2MeOH∙H2O (19) [LH2 = 2-methyl-2-(2-pyridyl)propane-1,3-diol, Scheme 3]; both featuring octahedral MnIV ions linked alternately to one trigonal prismatic MnII ion and even more interestingly to one trigonal prismatic NaI ion (Scheme 3). The complexes are essentially identical in structure and magnetic behavior, showing a weak ferromagnetic interaction among the neighboring manganese ions. DFT studies on a model complex supports the S = 11/2 ground spin state, deduced from dc and ac susceptibility measurements.
CHAPTER 5 illustrates the use of a few dicarboxylates as potential bridging ligands to assemble tri- and hexanuclear MnIII-clusters. With the salicylaldoximate (salox) as the [MnIII3O(salox)3]+, triangle-generating moiety and keeping the reaction conditions (solvent, base, reaction time and crystallization process) identical, four new extended complexes that differ both in their basic and higher dimensional organizations are reported. When 1,3-phenylenediacetate (phda) is used (in EtOH), in the resulting complex [MnIII6O2(salox)6(EtOH)4(phda)]n∙(saloxH2)n∙(2H2O)n (20), a single type of MnIII6 clusters are linked by the dicarboxylate (interestingly the complex crystallizes with uncoordinated saloxH2 molecules). However, when two differently substituted isophthalate linkers (5-iodoisophthalate and 5-azidoisophthalate) are used, two almost identical complexes [MnIII6O2(salox)6(MeOH)5(5-I-isoph)]n∙(3MeOH)n (21) and [MnIII6O2(salox)6(MeOH)4(H2O)(5-N3-isoph)]n∙(4MeOH)n (22) are isolated, with two different types of Mn6 clusters (Scheme 4) linked alternately in one dimension. More interestingly, use of another substituted isophthalate (5-nitroisophthalate) produced a heteronuclear complex [MnIII3NaO(salox)3(MeOH)4(5-NO2-isoph)]n∙(MeOH)n(H2O)n (23) with only MnIII3 triangles as the basic cluster assembled in two dimensions. Temperature and field dependent dc and ac susceptibility measurements show that the complexes 20-22 behave as non-interacting single molecule magnets with ground spin state S = 4. Complex 23 is dominantly antiferromagnetic with a ground spin state S = 2. The magnetic behaviours of these complexes are also supported by theoretical calculations (DFT) on models generated from the crystal structures.
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Outer-sphere interactions in metal solvent extraction systemsHealy, Mary Rose January 2017 (has links)
This work aims to define the modes of action of a series of metal extraction ligands with particular focus on how these depend on the formation of supramolecular assemblies. Though solvent extraction processes are well established industrially often the understanding, particularly of the metal coordination chemistry, is less so. A greater understanding of a variety of solvent extraction systems can lead to the development of stronger and more specific extractants. Chapter 2 examines the role of inter-ligand interactions in the extraction of copper by phenolic oximes and pyrazoles. Computational methods are used to understand the importance of inter-ligand outer-sphere interactions in square-planar copper complexes. It is shown that functionalisation at different positions on the phenol ring can either stabilise or destabilise the copper complex and it is possible to predict the strength of extractants from DFT calculations. Substitution ortho to the phenolic oxygen in the oximes and pyrazoles can have a major effect of enhancing the strength of extractants by “buttressing” the H-bonding between ligands. However, in the amino-methyl substituted oximes buttressing is so strong that is has an adverse effect on complex formation. Crystal structures are confirmed by both ENDOR EPR spectroscopy and DFT structures. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)- phenols (X = H, OMe, Br and NO2) was synthesised and characterised (X = H, OMe, Br and NO2) and the copper extractant found to be 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)- 1H-pyrazol-3-yl)-phenol extractants. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. Studies also showed that substitution can affect not only complex stability through inter-ligand interactions through hydrogen bonding in the outer-sphere but also the strength of metal-ligand bonds. Chapter 3 looks at synergistic solvent extraction systems: where more than one extractant works together to provide additional strength and selectivity. Combinations of neutral N and O donor ligands with carboxylic, phosphinic and sulfonic acids were studied by solvent extraction, crystallographic and computational methods. Crystal structures and DFT-optimised structures show that ligands and acid form pseudo-tridentate ligands where both the neutral ligand and the deprotonated acid are coordinated directly to the metal centre with inter-ligand hydrogen bonding allowing for a more flexible backbone than a classic tridentate system. Although synergistic extractions systems often utilise carboxylic acids many of the structures show the similarities with systems containing phosphinic acids and it was shown experimentally that some extraction systems show greater synergism with phosphinic than carboxylic acid in the recovery of nickel. Chapter 4 deals with the extraction of molybdenum with commercial phosphinic acid extractant Cyanex 600. The propensity for molybdenum to form oxo clusters in aqueous solutions and the influence pH in both the speciation of the Mo species and extraction conditions contributes to a complex extraction profile. The pH dependence of extraction shows that different mechanisms operate at low (pH < 0) and high (pH > 0) pH. The extraction curve shows a conventional S-curve between pH 0 and 1.5 and slope analysis within this pH range gives a value very close to two but identification of structures which match this profile is complex. Maximum pH extraction is see at ~ pH 1.5. ESMS studies identified very similar species in the organic phase despite the variation seen in the S-curve. A survey of the structures of metal complexes of phosphinate ligands suggests that molybdenum-phosphinate complexes can often form cubane-like structure and negative ion ESMS data supports the concept of cluster formation in the organic phase. A common feature of the spectra are tetra- tri- and bi-metal- oxo species and spectra show a large number of peaks. It is very probable that the extraction of molybdenum(VI) with phosphinic acids is a dynamic system as extraction is influenced by the molybdenum speciation in the aqueous phase which is in turn influenced by both the pH and the molybdenum concentration both of which change over the course of a conventional extraction.
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