Dissertations / Theses on the topic 'Cation and Anion'

The investigation in this thesis focuses on the synthesis of cation-ordered perovskite phases by introducing anion vacancies into the structure. Complex cation-ordered phases Ba2YMO5 and Ba3YM2O7.5 (M = Fe, Co) have been synthesized using ceramic or citrate gel methods under flowing argon. Close inspection reveals that the structures are constructed from Y2M2O102 basic units which consist of two YO6 octahedra and two MO4 tetrahedra in a rock-salt type arrangement. In the structure of Ba2YMO5 (M = Fe, Co), the neighbouring Y2M2O102 units are connected with an equivalent one in the yz-plane with YO6 octahedra sharing an apex. In the structure of Ba3YM2O7.5 (M = Fe, Co), the basic units are connected to each other by the M2O7 dimers via a chain of Y – O – M – O – M – O – Y bonds. Complex cation ordering can be achieved by carefully controlling the anion vacancies and selecting the cations with different ionic radii. The anion vacancies present in Ba2YMO5 (M = Fe, Co) (space group P21/n) allow the intercalation of anions like O2- and F- into the lattice. The fluorination of Ba2YCoO5 leads to the formation of a new orthorhombic phase Ba2YCoO5F0.42 (space group Pbnm) in which the inserted fluoride ions are distributed in a disordered manner. In contrast, the topochemical oxidation of Ba2YFeO5 leads to the formation of a new orthorhombic phase Ba2YFeO5.5 (space group Pb21m), in which Fe4+ centres are located in 4-coordinate tetrahedral sites and 5-coordinate pyramidal sites, respectively. The polar structure of Ba2YFeO5.5 is confirmed by the observation of second-harmonic generation activity and pyroelectric behaviour. Ba2YFeO5.5 also exhibits a combination of ferromagnetic and antiferromagnetic behaviours at low temperature. LaCa2Fe2GaO8 adopts a six-layer structure consisting of an OOTLOOTR stacking sequence of layers of (Fe/Ga)O6 octahedra (O) and (Fe/Ga)O4 tetrahedra (T), related to that of the four-layer brownmillerite structure (space group Pbma). The chains of tetrahedra in the structure of LaCa2Fe2GaO8 exhibit a cooperative twisting distortion in which the twisting direction of the chains of tetrahedra alternates in adjacent tetrahedral layers. LaxSr2-xCoGaO5+δ (0.5 < x < 1) adopts brownmillerite structures which consist of octahedral and tetrahedral layers with mixed valence of Co2+/Co3+. The members with x = 0.5, 0.6 and 0.7 adopt structures with I2mb space group symmetry, in which all the tetrahedra twist in the same direction. The members with x = 0.8, 0.9 and 1.0 adopt structures with Imma space group symmetry, in which the chains of the tetrahedra twist in a disordered manner. A change in the Co3+ spin state from high spin (HS) to low spin (LS) is observed as the La/Sr ratio increases. The change of the Co3+ spin state can be rationalized on the basis of internal chemical pressure.

Les polyoxométallates et plus particulièrement les hétéropolymolybdates sont des composés très recherchés en catalyse, homogène ou hétérogène. A l'état solide, leur comportement réactif dépend de nombreux paramètres dont la nature des contre-ions présents, le type de molécules de solvatation, le système cristallin et leur evolution thermique. Plusieurs sels (sodium, potassium, alkyl(aryl)ammonium) des ions dodécamolybdophosphate (3-), vanadoundécamolybdophosphate (4-) et de structures apparentées (octadécamolybdophosphate (6-)) ont été préparés. Ils ont été étudiés en solution par polarographie et à l'état solide par spectrométries de vibration (infra-rouge, Raman) et spectrométrie RMN de 31P. Leur comportement thermique a été suivi par analyse thermique et les différentes phases décelées étudiées par RPE. Ces mesures ont permis d'identifier plusieurs types d'interactions susceptibles de rendre compte de la réactivité en oxydation sélective. Deux d'entre elles, interactions anion-anion et anion-cation, sont fortement dépendantes des arrangements cristallographiques et de leur évolution thermique. L'interaction anion-anion est attendue augmenter la stabilité de l'anion, alors que l'interaction anion-cation, antagoniste, est attendue la diminuer.

The fundamental bulk and surface electronic properties of a novel class of semiconductors, characterised by a significant mismatch between the size and electro-negativity of the cation and anion (SCAMS), have been investigated. The characteristic examples of CdO, In2O3, and InN were studied using high-resolution x-ray photoemission spectroscopy, infrared reflectivity, optical absorption spectroscopy, and single-field Hall effect measurements. The behaviour of not only defects, dopants and impurities, which dominate the bulk electronic properties, but also surface states was shown to depend on the position of a single energy level, the charge neutrality level (CNL), unifying bulk and surface electronic properties of semiconductors. For the materials studied, the CNL was shown to be located within the conduction band (0.39 eV, »0:65 eV, and 1.19 eV above the conduction band minimum (CBM) in CdO, In2O3, and InN, respectively; see figure) in contrast to the vast majority of semiconductors where the CNL lies within the fundamental band gap (as, for example, in the classic case of GaAs). In CdO, this was shown to lead to native defects, hydrogen impurities and surface states all being donors, even in already n-type material. The donor surface states result in electron accumulation at the CdO surface. Such an electron accumulation is also present at InN surfaces, and this was shown to exhibit a remarkable independence on surface orientation, and to lead to inversion layers at the surface of p-type InN. The changes in surface space-charge regions were investigated across the In(Ga,Al)N composition range, for both undoped and Mg-doped alloys. The influence of the CNL position on interface properties and conductivity in InN was considered. Electron accumulation was observed in In2O3, in contrast to previous reports. Muonium, and by analogy hydrogen, was also shown to be a shallow donor in this material. The location of the CNL above the CBM in SCAMS was used to explain many of their striking bulk electronic properties, such as why materials like In2O3 are able to be conducting despite being optically transparent, two normally contradictory properties. The conclusions drawn from these studies are applicable to a wide variety of other materials, in particular other SCAMS such as ZnO or SnO2. Surface electron accumulation is treated here mainly within a one-electron semi-classical approximation. The final section of this work moves beyond this, using angle-resolved photoemission spectroscopy measurements and theoretical calculations to consider both the quantized nature of an electron accumulation layer, and the influence of many-body effects.

Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared stretching frequency that can be easily observed, and their respective sizes can be observed while intercalated within the interlayer of the LDH. The ability of LDH to incorporate metal cations or any ions/molecules/complexes, that have a postive charge, have not been previously investigated, mainly due to the chemical and physical nature of LDH. The possibility of cationic incorporation with LDH would most likely occur by surface adsorption, lattice metal replacement, or by intercalation into the LDH interlayers. Although infrared spectroscopy finds it main use through the identification of the anions incorporated with LDH, it can also be used to study and identify the various active and inactive bending and stretching modes that the metal hydroxide layers have.

ZnO is an n-type semiconducting material with high optical transparency in the visible range (400 - 750 nm) of the electromagnetic spectrum. When doped with group 13 or 14 metal oxides, ZnO exhibits almost metallic electrical conductivity. ZnO thin films have been recognised as promising alternative material for the currently widely-used but expensive indium oxide in the form of indium tin oxide (ITO), in terms of their low cost and the high abundance of zinc. At the moment, even the best solution-processed ZnO films still can not compete for ITO replacement especially in solar energy utilization and OLED lighting applications, and the performance of ZnO films needs to be further improved. The objective of this work was to enhance the electrical and optical properties of spray pyrolysed ZnO thin films by simultaneous cation and anion doping. This was achieved by growing several series of undoped, single-doped, and co-doped ZnO thin films over a wide range of conditions, in order to understand the growth behaviour of undoped and doped ZnO, and to establish the optimum growth procedure. Spray pyrolysis process has advantages over vacuum-based techniques in terms of its low-cost, high deposition rate, simple procedure and can be applied for the production of large area thin films. Various techniques were employed to characterize the properties of the prepared thin films, and thus determine the optimum growth conditions (i.e. X-ray difiraction (XRD), Xray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), UV-Vis-NIR spectroscopy and Hall effect measurement). The growth of doped ZnO on glass substrates using Si and F as dopants, yielded highly conducting and transparent thin films. The co-doped thin films exhibited distinct widening of band gap upon increasing deposition temperature and doping concentration as a result of increasing electron concentration up to 4.8 x 10²⁰ cm^-3 upon doping with Si and F at the same time. The resistivity of the films deposited from Zn(acac)₂ · xH₂O solutions and at the optimum temperature of 450 °C, was found to decrease from 4.6 x 10^-2 Ωcm for the best undoped ZnO film to 3.7 x 10^-3 Ωcm, upon doping with 3% Si. The films co-doped with Si and F in the ratios of [Si] / [Zn]= 3 - 4 mol% and [F] / [Zn]=30 - 40 mol% were the most conducting (p ∼ 2.0 x 10^-3 Ωcm). The associated optical transmittance of co-doped ZnO was above 85% in the whole visible range. Results compare favourably with In-doped ZnO deposited under similar conditions. Si+F co-doped ZnO films offer a suitable replacement for ITO in many applications such as LCD and touch screen displays.

Experiments were conducted to investigate the effect of reducing dietary anion-cation balance (AC-balance), defined as meq $ sp circ$(Sodium + Potassium)-(Chloride + Sulfur) S, on calcium (Ca) metabolism. Reducing the dietary AC-balance from +314 to $-22$ (meq kg$ sp{-1}$ dry matter (DM)) did not affect plasma Ca level but reduced Ca retention mainly due to a 10-fold increase in urinary Ca excretion with similar rate of apparent absorption. It also decreased urine pH and titratable acidity. The response to induced hypocalcemia created by the infusion of 4.6% EDTA solution revealed that reducing dietary AC-balance from +354 to +37 (meq kg$ sp{-1}$DM) did not affect the volume of the compartment, within which there was rapid equilibration of free Ca but tended to increase the rate of Ca mobilization from it during the infusion. The Ca kinetic study with a four-compartment model indicated that reducing dietary AC-balance from +338 to $-127$ (meq kg$ sp{-1}$DM) during the eucalcemic period and from +429 to $-147$ (meq kg$ sp{-1}$DM) during an EGTA-infusion period (simulated lactational Ca loss) caused hypercalciuria and increased ionized form of plasma Ca. Increased true intestinal Ca absorption and reduced bone accretion were observed in the lowest AC-balance diet only during the EGTA-infusion period. There were no differences in the size of total exchangeable Ca pool but the amount of Ca movement between them tended to increase in reduced AC-balance diets during both periods. Results indicated that feeding reduced AC-balanced diet may have a beneficial role in preventing parturient paresis (milk fever) by increasing Ca flux through the exchangeable Ca pool and Ca mobilization capability.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.
Includes bibliographical references (p. 127-137).
The investigation of ordering and phase stability in the ZrO2-Y203 system involves two sets of calculations. The first set of calculations uses the cluster expansion method. A guide to the practical implementation of the cluster expansion outlines methods for defining a goal and choosing structures and clusters that best model the system of interest. The cluster expansion of the yttria stabilized zirconia system considers 447 configurations across the ZrO2-Y203 composition range. The effective cluster interaction for pair clusters show electrostatic repulsion between anions and little interaction between cations. Triplet anion terms largely modify the energy contributions of the pair terms. Separate cluster expansions using structures at single compositions show that cation clusters become more important at high yttria composition. The cluster expansion led to the discovery of three previously unidentified ordered ground state structures at 25, 29, and 33 % Y on the cubic fluorite lattice. The ground state with 33 % Y is stable with respect to the calculated energies of monoclinic ZrO2 and the Y4Zr3012 ground state. The ground states have the common ordering feature of yttrium and vacancies in [1 1 2] chains, and Monte Carlo simulations show that vacancy ordering upon cooling is contingent on cation ordering.
(cont.) The second set of calculations consider three driving forces for order: ionic relaxation, vacancy arrangements, and differences in Zr and cation dopant radii. Bond valence sums of fully relaxed and anion relaxed structures are nearly equal at all compositions. In supercells of ZrO2, the vacancy arrangement of the ground state with 25 % Y is more stable than arrangements maximizing the distance between vacancies or aligning vacancies in [1 1 1]. Comparing the YSZ ground state with structures of the same configuration with scandium replacing yttrium shows different stable phases on the convex hull between cubic ZrO2 and the dopant M203 phase. The change in the stability of the configurations may be a result of cation radius sizes. The factors suggest that the driving forces of phase stability depend on composition.
by Ashley P. Predith.
Ph.D.

Master of Science
Department of Animal Sciences and Industry
Barry J. Bradford
The transition from gestation to lactation requires numerous physiological and metabolic adaptations in order for the body to maintain relative homeostasis. For the modern dairy cow, the difficulty to meet these challenges is increased many-fold due to the large demand for energy and metabolites placed on the body by the high producing mammary gland. Milk fever or periparturient hypocalcemia can be defined as a failure of the calcium homeostatic mechanisms to maintain serum calcium around the time of calving. Though clinical cases may only arise in ≈ 5% of transition cows, subclinical rates are much higher. Animals suffering from even subclinical milk fever are much more susceptible to numerous other transition disorders. Preventing milk fever by formulation of the prepartum ration may be accomplished by decreasing the dietary cation anion difference (DCAD) which can be defined as the balance between positively and negatively charged ions in the diet. An experiment was designed to test 2 diets containing t products designed to deliver supplementary anions to the diet versus a control ration with no added anions. Total serum calcium and incidence of postpartum health disorders were not affected by prepartum dietary treatment. Though DCAD was drastically different between the control ration and the 2 anionic diets, the concentration of the strong cation potassium was low across all treatments which presumably prevented hypocalcemia with the onset of lactation. Though our diets contained low concentrations of potassium, many diets used by dairymen contain forages that are high in potassium and thus might benefit from the addition of anions. An experiment of an unrelated nature was conducted to observe the effects of 2 diets containing wet corn gluten feed (46 or 56% of DM) as the primary energy substrate and tallgrass prairie hay (14 or 20% of DM) as the sole source of physically effective fiber versus a control ration containing alfalfa and corn silage. The 20% tallgrass prairie hay diet resulted in milk components and efficiencies similar to those of the control ration, but production and income over feed cost did not match that of the control ration in this situation.

Here we investigate the organic ionic plastic crystal (OIPC) 1,2-bis[N-(N\'-hexylimidazolium-d2(4,5))]C2H4 2PF6- in one of its solid plastic crystal phases by means of multi-nuclear solid-state (SS) NMR and pulsed-field-gradient (PFG) NMR. We quantify distinct cation and anion diffusion coefficients as well as the diffusion activation energies (Ea) in this dicationic imidazolium-based OIPC. Our studies suggest a change in transport mechanism for the cation upon varying thermal and magnetic treatment (9.4 T), evidenced by changes in cation and anion Ea. Moreover, variable temperature 2H SSNMR lineshapes further support a change in local molecular environment upon slow cooling in B0. Additionally, we quantify the percentage of mobile anions as a function of temperature from variable temperature 19F SSNMR, where two distinct spectral features are present. We also comment on the pre-exponential factor (D0), giving insight into the number of degrees of freedom for both cation and anion as a function of thermal treatment. In conjunction with previously reported conductivity values for this class of OIPCs and the Stokes-Einstein relation, we propose that ion conduction is dominated by anion diffusion between crystallites (i.e., grain boundaries). Using our experimentally determine diffusion coefficient and previously reported PF6- hydrodynamic radius (rH), viscous (" = 4.1 Pa " s) ionic liquid (IL) is present with a cation rH of 0.34 nm. NMR measurements are very powerful in elucidating fundamental OIPC properties and allow a deeper understanding of ion transport within such materials.
Master of Science

The cation–π interaction has been long-established to play an important role in molecular recognition, supramolecular chemistry, and molecular biology. In contrast, its potential application in small-molecule catalysis, especially as a selectivity-determining factor in asymmetric synthesis has been overlooked until very recently. This dissertation begins with an extensive literature review on the state-of-the-art research on the application of cation–π interactions in non-enzymatic catalysis of organic and organometallic transformations. The research in this field has been largely inspired and guided by the related biosynthetic systems incorporating the same type of interactions.

Chemistry and Chemical Biology

Dans cette thèse, nous avons étudié le comportement du contreion aluminate faiblement coordinant, [Al(OC(CF3)3)4] dans des processus catalytiques à base de métaux des cationiques comme les sels de gallium(I), d’indium à faible degré d'oxydation ainsi que des sels de lithium. Tout d’abord, nous avons étudié les transformations catalysées par [Ga][Al(OC(CF3)3)4], notamment pour la dihydroarylation des arènes, l'hydrogénation par transfert des alcènes en utilisant le 1,4-cyclohexadiène comme source d'hydrogène, la cyclisation hydrogénante en tandem des arènes et la cycloisomérisation des énynes. Par la suite, nous avons demontré que le catalyseur [In][Al(OC(CF3)3)4] était très sélectif pour favoriser l'ortho-alkylations d'anilines non protégées en présence des styrènes. Par extension nous avons appliqué ce dernier à l'hydroamination d’alcénylamines primaires et secondaires non protégées dans des conditions douces. Enfin, le complexe [Li][Al(OC(CF3)3)4] s'est révélé être un catalyseur efficace pour la synthèse de dérivés du styrène à partir de vinyl triflate et d'arènes par l'intermédiaire d'un cation vinylique. Nous avons prouvé que cet anion volumineux et inerte [Al(OC(CF3)3)4] était capable d'apprivoiser des cations hautement réactifs que ce soit des métaux cationiques ou des intermédiaires réactionnels, ouvrant ainsi de nouvelles perspectives en méthodologie de synthèse
In this thesis, we studied the behaviour of the weakly coordinating aluminate counterion, [Al(OC(CF3)3)4] in catalytic processes based on cationic metals such as gallium(I) and indium(I) salts with low oxidation state indium and lithium salts. Initially,, we have studied [Ga][Al(OC(CF3)3)4]-catalyzed transformations, especially for the dihydroarylation of arenes, the transfer hydrogenation of alkenes using 1,4-cyclohexadiene as hydrogen source, the tandem hydrogenation cyclization of arenes and enynes cycloisomerization. Subsequently, we showed that the [In][Al(OC(CF3)3)4] catalyst was highly selective in promoting ortho-alkylation of unprotected anilines in the presence of styrenes. By extension we applied the latter to the hydroamination of unprotected primary and secondary alkenylamines under mild conditions. Finally, the [Li][Al(OC(CF3)3)4] complex has proven to be an effective catalyst for the synthesis of styrene derivatives from vinyl triflate and arenes via a vinyl cation. We proved that this bulky and inert anion [Al(OC(CF3)3)4] was capable of taming highly reactive cations, both cationic metals and reaction intermediates, thus opening new perspectives in synthesis methodology

Fundamental understanding of water transport and morphology is critical for improving ion conductivity in polymer electrolyte membranes (PEMs). Herein, we present comprehensive water transport measurements comparing anion-exchange membranes (AEMs) based on ammonium-functionalized poly(phenylene oxide) and cation-exchange membranes (CEMs) based on sulfonated poly(ether sulfone). We investigate the influence of counter ions, alkyl side chain, and degree of functionalization on water transport in AEMs and CEMs using pulsed-field-gradient (PFG) NMR diffusometry. Water diffusion in both AEMs and CEMs exhibit specific trends as a function of water uptake (wt%), indicating morphological similarities across common chemical structures. Furthermore, restricted diffusion reveals micron-scale heterogeneity of the hydrophilic network in both CEMs and AEMs. We propose a model wherein the hydrophilic network in these membranes has micron-scale distributions of local nm-scale dead ends, leading to changes in tortuosity as a function of water content, counterion type, and polymer structure. We furthermore parse tortuosity into two regimes, corresponding to nm-to-bulk and µm-to-bulk ranges, which reveal the importance of multi-scale morphological structures that influence bulk transport. This study provides new insights into polymer membrane morphology from nm to µm scales with the ultimate goal of controlling polymeric materials for enhanced fuel cells and other separations applications
MS

Direct methanol fuel cells (DMFCs) are considered a clean source of electrical power for future energy demand, creating a potential to reduce our dependency on fossil fuels. Despite their advantages, including high energy density, efficiency and easy handling and distribution of fuel, the commercialization of DMFCs has suffered from some drawbacks, including methanol crossover and contamination of the system. Metal cation contaminants (such as Ni, Co, etc) introduced through the degradation of fuel cell components (bipolar plate and electro-catalyst layer) can significantly affect the Nafion-membrane properties and overall fuel cell performance. In the current study, a systematic approach is taken to characterize and identify the mechanism of the effect of metal solution contaminants on the activities of electro-catalysts of DMFCs. Cyclic voltammetry and rotating disk electrode (RDE) techniques were utilized in order to characterize the effect of various concentrations (i.e., 2x10-x M (x=1-7)) of six metal solution contaminants (i.e., Co, Ni and Zn with sulfate and nitrate as counter-anions) on the voltammetric properties and electro-catalytic activity of polycrystalline Pt during methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). The results showed a decrease in the MOR and ORR activities of Pt as the concentration of metal solution increased. The effect of counter-anion on the Pt activity was further investigated. The results showed that a combined effect of counter-anions and metal cations may be responsible for the decrease in the electro-catalytic activity of Pt. The effect of metal solution contaminants on the Nafion-ionomer of anode electro-catalysts was investigated using Nafion-coated Pt electrode. Voltammetric properties and MOR activities of Nafion-coated and bare Pt electrodes in the presence of Ni solution contaminants were characterized using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The overall results showed a significant negative effect of Ni solution contaminants on the electro-catalytic activity of bare Pt electrode as compared to the Nafion-coated Pt electrode. Based on the results, it appears that Nafion-ionomer film may interact with metal cations (through its sulfonate groups) and repel them away from the Pt active sites, partially inhibiting the negative effect of metal cations on the Pt activity of Nafion-coated Pt electrode. The effect of metal solution contaminants on the carbon-supported platinum nanoparticle (Pt/C) with various Nafion-ionomer distributions and contents (i.e., Nafion-incorporated Pt/C and Nafion-coated Pt/C electrodes) was further investigated. Cyclic voltammetry and EIS techniques were employed to characterize the effect of Ni solution contaminants on the voltammetric properties and MOR activities of Nafion-incorporated and Nafion-coated Pt/C electrodes. The overall results showed a stronger negative effect of Ni solution contaminants on the electro-catalytic activity of Nafion-incorporated Pt/C electrodes as compared to the Nafion-coated Pt/C electrodes. This further confirms previous observations showing the sulfonate groups of Nafion-ionomer film may attract the Ni metal cations, localize them away from the Pt active sites, and subsequently suppress the negative effect of cations on the activity of Nafion-coated Pt/C electrodes.

Although attractive interactions between π systems (π-π interaction) have been known for many years, understanding of its origin is still incomplete. Quantitative measuring of π-stacking is challenging due to the weak nature of the π-π interaction. This dissertation aims at elucidating a quantitative conformational analysis by NMR ring current anisotropy of an organic compound capable of intramolecular π-stacking in solution and studying charge effects on the stacking of π-systems. This dissertation offers four contributions to the area. (1) A general approach to four-state, conformational analysis based on the magnetic anisotropy of molecules undergoing fast dynamic exchange is described. (2) Study unveiled the importance of charges in the conformation of a dication in the solution. (3) Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized and studied. (4) Study unveiled ionic π-systems preferred face-to-face stacking due to strong cation-π and anion-cation attractions. A general protocol for the application of magnetic anisotropy to quantitative multi-state conformational analysis of molecules undergoing fast conformational exchange was suggested in the current study. The reliability of this method of conformational analysis was checked by the mass balance. VT-NMR was also conducted to study the enthalpic parameters. This technique can be further used to study canonical interactions such as ion pairing, hydrogen boning, and molecular recognition. In the current study, dependence of the probe conformations on the dispersive interactions at the aromatic edges between solvent and probes was tested by conformational distributions of the fluorinated derivatives (2b and 2c) of the probe molecule (1a). Solution and solid studies of these molecules put the previous conclusion drawn by the Cammers group in question. Current studies show that the dispersive interaction at the aromatic edge could not be the predominant force on the conformational changes in the probe molecule 1a during the fluoroalkanol perturbation. This study indicated that charges might be important in the formation of the folding conformations in the solution and solid state of 1a, 2b, and 2c. A contribution of this thesis was to prepare and study a conformational model that lacked charges. The previous molecules were charged. The solid-state structures of pyridinium-derived aromatic rings from the CSD (Cambridge Structural Database) were studied to investigate the π-π interaction between cationic π-systems in solid state. Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized to study the π-π interaction between two aromatic rings that carried opposite charges. This study showed that the interaction between ionic π-systems can be enhanced by cation-π and anion-cation attractions. The stackings of these π-systems introduce more overlap, closer packing and stronger atomic contact than that of the solid states of comparable neutral species. Cation-π and anion-cation attractions are synergistic in aromatic salts.

Experiments were conducted to investigate the effects of formulating rations using different ingredients and of manipulating the cation-anion balance of the rations on production, acid-base status, metabolism of macrominerals and renal function of dairy cows. The effects of dietary cation-anion balance were studied during early, mid and late lactation as well as during the dry period. Feeding an alfalfa-haylage based diet vs a corn silage based diet, both having the same cation-anion balance did not affect the voluntary consumption, milk yield or milk composition of cows in early lactation. The acid-base status of the animals was not affected by dietary treatment. The lower urinary bicarbonate concentration observed with the alfalfa haylage-based diet was not associated with a lower total urinary bicarbonate excretion since urine volume was significantly higher than when cows were fed the corn silage-based diet. Manipulating dietary cation-anion balance, however, resulted in changes in acid-base status at all stages of lactation studied. Urinary bicarbonate concentration and total daily excretion were increased by a higher dietary cation-anion balance at all stages of lactation. Similar effects of dietary cation-anion balance on urinary bicarbonate did not, however, translate into similar changes in production or intake by cows at differing stages of lactation. Cows in early and mid lactation seemed to have benefited more from a highly positive dietary cation-anion balance than cows in late lactation or dry period.

Foram utilizadas 8 vacas Holandesas em lactação, distribuídas em um quadrado latino (4x4), replicado, conduzidos durante o verão, por um período de 72 dias. O objetivo desse trabalho foi estudar quatro níveis de dietas catiônicas, sobre a IMS, produção, composição e propriedades físico-químicas do leite, pH urinário, temperatura corporal e parâmetros ácido-base do sangue, em vacas após o pico de lactação. Para a manipulação do BCAD, foram adicionadas diferentes concentrações de bicarbonato de sódio nas dietas, obtendo-se os seguintes tratamentos: +150, +250, +400 e +500mEq/kg MS. A temperatura corporal das vacas não foi afetada pelo balanço cátion-aniônico da dieta. O bicarbonato, o pH, o CO2 total e a pCO2 do sangue aumentaram linearmente com o aumento do BCAD. A concentração de cálcio no sangue apresentou resposta quadrática, com maior valor para o menor BCAD. As concentrações de sódio e potássio do sangue não foram modificadas significativamente pelo BCAD e a concentração de cloro diminuiu linearmente com o aumento do BCAD. O aumento do BCAD resultou em aumento da ingestão de matéria seca e produção de leite. Não houve diferença significativa para as variáveis: porcentagem de gordura, densidade e índice crioscópico, do leite. O pH do leite aumentou linearmente e a acidez apresentou resposta cúbica, com o aumento do BCAD. Conclui-se que a manipulação do BCAD afeta o equilíbrio ácido-base das vacas, mesmo dentro de variação positiva. Devido ao aumento da IMS e da produção de leite, verificou-se efeito benéfico do uso de dietas catiônicas, para vacas após o pico de lactação.
Eight lactating Holsteins cows were distributed in 4 x 4 replicated Latin square, during the summer, for a period of 72 days. The objective of this research was to study the effect of four cationic diets levels, on the dry matter intake, milk production, composition, and physico-chemical parameters, urinary pH, body temperature and blood acid-base parameters, in cows, after the lactation peak. For DCAB manipulation were added different concentrations of sodium bicarbonate in the diets and the following treatments were obtainned: +150, +250, +400 e +500mEq/kg DM. The cows body temperature was not affected by dietary cation-anion balance. Blood bicarbonate, pH, total CO2 and pCO2 increased linearly with the increase of dietary CAB. Calcium concentration in the blood decreased quadratically with dietary CAB increased. Sodium and potassium concentration in the blood were not modified significantly with the DCAB and concentration of chloride decreased linearly with increase of DCAB. Increasing BCAD resulted in higher DM intake and milk yield. The diets did not affect milk fat percentage, density and crioscopic index. Milk pH increased linearly and acidity decreased cubically with the increase of dietary CAB. It was concluded that DCAB manipulation affected the acid-base status of cows, even inside of positive variation. Due to the increase of DM intake and milk yield, it was verified a beneficial effect of the cationic diets for cows after the lactation peak.

Os efeitos do balanço cátion-aniônico da dieta (BCAD) na degradabilidade ruminal da MS e PB do farelo de soja, degradabilidade ruminal da MS e amido do fubá de milho, foram estudados em dois experimentos com diferentes proporções de volumoso:concentrado (experimento 1 - 60:40; experimento 2 - 40:60), em 12 bezerros Holandeses (peso médio de 91,55kg e de 117,62kg respectivamente), portadores de cânulas ruminais, realizados no Campus Administrativo de Pirassununga/SP, na FZEA/USP. Os períodos experimentais foram de 35 dias, sendo 14 dias de adaptação dos animais às gaiolas e às dietas e 21 dias de colheita de dados, com 15 dias de descanso. O delineamento foi o inteiramente casualizado, com três tratamentos e quatro repetições em ambos os experimentos. Para a manipulação do BCAD, foram adicionados sulfato de amônio e bicarbonato de sódio, obtendo-se os seguintes tratamentos no experimento 1: -123, +218 e +341 mEq/kg MS; e no experimento 2: -127, +207 e +397 mEq/kg MS. Utilizou-se silagem de milho como fonte de volumoso. Os níveis de BCAD influenciaram as degradabilidades ruminais da MS e PB do farelo de soja com a proporção de volumoso:concentrado de 60:40 (P<0,10). As degradabilidades ruminais da MS e amido do fubá de milho com a proporção volumoso:concentrado de 60:40, não foram afetadas pelos níveis de BCAD (P>0,10), assim como as degradabilidades ruminais da MS e PB do farelo de soja, MS e amido do fubá de milho com a proporção volumoso:concentrado de 40:60 (P>0,10).
The DCAB effects on dry matter (DM) and crude protein (CP) degradability of soybean meal and DCAB effects on DM and corn meal degradability were investigated in two trials with different rate of roughage:concentrate (experiment 1: 60:40, experiment 2: 40:60). Twelve Holstein calves with ruminal cannula were used in each experiment (91,55 kg and 117,62 kg of mean weight, respectively). Both experiments were conducted at FZEA/USP, Pirassununga/SP. The experimental periods were constituted by 35 days (14 days adaptation and 21 days data collection) with 15 days of interval. It was used completely design, with three treatments and four repetitions. For DCAB manipulation were added ammonium sulfate and sodium bicarbonate in order to achieve the following values: experiment 1: -123, +218, +341 mEq/kg DM, experiment 2: -127, +207, +397 mEq/kg DM. The diet was based on corn silage as forage. The DCAB ratios affected DM and soybean meal CP degradabilities when 60:40 roughage:concentrate ratio were used (P<0,10). DM and corn meal degradabilities were not affected by DCAB ratios (P>0,10), as well as DM and soybean meal CP degradabilities when 40:60 roughage:concentrate ratio were used P<0,10).

O efeito do balanço cátion-aniônico da dieta (BCAD) no desempenho, balanço macromineral (cálcio, fósforo, sódio e potássio), na fermentação ruminal , pH urinário e na concentração sérica de cálcio, foi estudado utilizando-se 25 ovinos machos, da raça Santa Inês, por um período de 75 dias. O delineamento experimental foi em blocos ao acaso, com cinco tratamentos. Para a manipulação do BCAD foram adicionados sulfato de amônio e bicarbonato de sódio, obtendo-se os seguintes tratamentos: -160, -40, 140, 250 e 500 mEq/kg MS. O aumento do BCAD resultou em aumento da IMS, aumento em ganhos diários e eficiência alimentar (P<0,05). O pH ruminal, pH urinário e o volume urinário aumentaram com aumento do BCAD (P<0,05). O perfil de ácidos graxos ruminais não foi afetado pelo BCAD. O BCAD influenciou o metabolismo macromineral principalmente o de cálcio, com a diminução do BCAD o cálcio sérico aumentou. Dietas aniônicas aumentaram a excreção urinária de cálcio, entretanto a retenção não foi afetada.
The dietary cation-anion balance (DCAB) effect in performance, macromineral (calcium, phosphorus and sodium) balance, urinary pH and calcium serum concentration, was studied in 25 males sheeps, from Santa Ines breed, during 75 days. The design used was randomized complete blocks, with five treatments. For DCAB manipulation were added ammonium sulfate and sodium bicarbonate in order to achieve the values: -160, -40, 140, 250 e 500 meq/kg DM. Increasing the DCAB resulted in higher DMI, daily gains and feed efficiency (P<0,05). Rumen pH, urine pH and urine volume increased as DCAB increased (p<0,05). Ruminal VFA profile was not affected by DCAB. The DCAB affected the calcium metabolism, decresing the DCAB the serum calcium increased. Dietary anionic increased urinary excretion of calcium, however calcium retention was not effect.

Protein folding studies have provided important insights about the key role of non-covalent interactions in protein structure and conformational stability. Some of these interactions include salt bridges, cation-π, and anion-Ï€ interactions. Understanding these interactions is crucial to developing methods for predicting protein secondary, tertiary, quaternary structure from primary sequence and understanding protein-protein interactions and protein-ligand interactions. Several studies have described how the interaction between two amino acid side chains have a substantial effect on protein structure and conformational stability. This is under the assumption that the interaction between the two amino acids is independent of surrounding interactions. We are interested in understanding how salt bridges, cation-π, and anion-π interactions affect each other when they are in close proximity. Chapter 1 is a brief introduction on noncovalent interactions and noncovalent interaction cooperativity. Chapter 2 describes the progress we have made measuring the cooperativity between noncovalent interactions involving cations, anions and aromatic amino acids in a coiled-coil alpha helix model protein. Chapter 3 describes cooperativity between cation, anion, and nonaromatic hydrophobic amino acids in the context of a coiled-coil alpha helix. In chapter 4 we describe a strong anion-π interaction in a reverse turn that stabilizes a beta sheet model protein. In chapter 5 we measure the interaction between a cysteine linked maleimide and two lysines in a helix and show that it is a general strategy to stabilize helical structure.

This thesis is comprised of three parts. The first part concerns the investigation of the topochemical reduction of LaSrNiRuO₆ in order to prepare LaSrNiRuO₄ via anion deintercalation. The second part discusses the oxide-for-hydride anion exchanges performed in SrV_1-xTi_xO₃, and the resulting SrV_1-xTi_xO_2-yH_1+y reduction products. Finally, the results from redox-neutral topochemical cation exchange reactions conducted in the three-dimensional perovskite structure of NaTaO₃ are presented along with the characterisation of a novel product of composition Ni_0.5TaO₃. The topochemical reduction of LaSrNiRuO₆ using CaH2 was carried out to produce a novel extended oxide phase with composition LaSrNiRuO₄. This phase is composed of sheets of apex-linked Ni¹⁺O₄ and Ru²⁺O₄ squares in a checkerboard ordered arrangement. To the best of our knowledge, this material is the first example of a B-cation ordered infinite-layer oxide phase. The low oxidation states of the transition-metal cations are confirmed by DFT calculations from which a spin moment S = ½ is determined for the nickel while the ruthenium centres adopt an intermediate-spin S = 1 configuration. LaSrNiRuO4 behaves paramagnetically at room temperature. However, upon cooling (T < 250 K) a phase transition is observed in which the nickel spins interact ferromagnetically, while the ruthenium cations appear to undergo a change in spin configuration to a diamagnetic spin state. A possible explanation is given for this observation based on an ordered arrangement of local Jahn-Teller distortions. While investigating the preparation of LaSrNiRuO₄, it was observed that different samples of the LaSrNiRuO₆ starting materials exhibited markedly different reactivity. The observed differing reactivity is inconsistent with the crystal structure and composition of the LaSrNiRuO₆ samples, from which all the materials are identical. Careful investigation of the X-ray diffraction data collected from the LaSrNiRuO6 materials revealed that the reactivity of the samples is a consequence of the microstructure. By quenching or slow-cooling the materials during their synthesis, the size of the crystalline domains formed is affected and this in turn is observed to define the extent to which the topochemical deintercalation of oxide anions takes place. A mechanism to explain this effect is presented in which the greater 'plasticity' of small crystalline domains helps to limit the influence of lattice strain during the reaction. Similar with the observations for the LaSrNiRuO₆ phases, it was found that the reactivity of SrV_0.95Ti_0.05O₃ samples towards topochemical oxide-for-hydride exchange is also determined by the characteristics of the starting materials. The cooling rate can lead to phase segregation in SrV_0.95Ti_0.05O₃ samples which in turn affects the reduction behaviour. A modification of the energy profile for the oxide-for-hydride exchange in SrV_1-xTi_xO₃ phases is proposed on the basis of the electronic configuration that the transition-metal cations adopt upon reduction (d²,V³⁺ and d¹,Ti³⁺). Finally, topochemical exchange reactions can also be carried out between cations in complex transition metal oxides when the mobility of the species to be exchanged is sufficiently greater with respect to the host lattice. The preparation of Ni_0.5TaO₃ from exchange of Na⁺ by Ni²⁺ in NaTaO3 represents a synthetic approach not yet widely explored in the long-standing challenge that the preparation of magnetoelectric multiferroic materials represents. The topochemical reactions studied in this work highlight the possibility of directing and modifying the product phases, by tuning features of the reagents. This is in contrast with the limited control available in thermodynamic processes.

This thesis deals with the diffusion of ions in compactedbentonite clay. Laboratory experiments were performed toexamine in detail different processes that affect thediffusion. To demonstrate that the results obtained from thelaboratory investigations are valid under in situ conditions,two different kinds of in situ experiments were performed. Laboratory experiments were performed to better understandthe impact of ionic strength on the diffusion of Sr2+ and Cs+ions, which sorb to mineral surfaces primarily by ion exchange.Furthermore, surface related diffusion was examined anddemonstrated to take place for Sr2+ and Cs+ but not for Co2+,which sorbs on mineral surfaces by complexation. The diffusion of anions in bentonite clay compacted todifferent dry densities was also investigated. The resultsindicate that anion diffusion in bentonite clay consists of twoprocesses, one fast and another slower. We ascribe the fastdiffusive process to intralayer diffusion and the slow processto diffusion in interparticle water, where anions are to someextent sorbed to edge sites of the montmorillonite. Two different types of in situ experiments were performed,CHEMLAB and LOT. CHEMLAB is a borehole laboratory, where cation(Cs+, Sr2+ and Co2+) and anion (I- and TcO4-) diffusionexperiments were performed using groundwater from a fracture inthe borehole. In the LOT experiments cylindrical bentoniteblocks surrounding a central copper rod were placed in a 4 mdeep vertical borehole. The borehole was then sealed and theblocks are left for 1, 5 or>>5 years. When the bentonitewas water saturated the central copper rod is heated tosimulate the temperature increase due to radioactive decay ofthe spent fuel. Bentonite doped with radioactive Cs and Co wasplaced in one of the lower blocks. Interestingly, the redox-sensitive pertechnetate ion (TcO4-)which thermodynamically should be reduced and precipitate asTcO2·nH2O, travelled unreduced through the bentonite.However, at some spots in the clay, the Tc activity wasconsiderably higher. We ascribe these activity peaks toiron-containing minerals in the bentonite, by which Tc(VII) hasbeen reduced to Tc(IV) and precipitated. The cations Sr2+, Cs+and Co2+, as well as the anion I-, behaved in the CHEMLABexperiments as expected from laboratory studies. Three experiments in the LOT series are completed. The firsttwo diffusion experiments in LOT were less successful, thefirst due to the fact that saturation of the bentonite was notobtained during the experimental period and the radionuclidesdid not move at all. In the second, the uptake of the bentoniteparcel was less successful. Water from the drilling flushedaway large pieces of the top part of the bentonite and thelower part of the test parcel was super-saturated with waterand expanded when released from the rock. The activity distribution in the second experiment wasanalysed. The Co2+ profile looked as we had expected, while Cs+had spread more than our calculations indicated. However, thethird experiment was successful from emplacement, watersaturation and heating to uptake. The activity distribution forboth cations was as expected from laboratory studies. Altogether the three different types of experiments give auniform picture of radionuclide diffusion in bentonite clay forthe ions investigated.
QC 20100621

Einleitung: Die Kationen-Anionen Bilanz (DCAB) des Futters modifiziert den Säure-Basen Status von Tieren und findet Anwendung in der Prävention von Milchfieber bei Kühen, MMA bei Sauen und Urolithiasis bei Haustieren. Durch die Veränderung des Kationen-Anionen-Verhältnisses in Futterrationen können biologische Prozesse beeinflusst werden, der Stickstoffmetabolismus. Ziel der Untersuchung: Die vorliegende Studie befasst sich mit der Frage, ob eine kaliumbedingte Variation der DCAB des Futters für wachsende Schweine einen Einfluss auf bestimmte Parameter des Säure-Basen-Haushaltes und möglicherweise auch auf die Stickstoffbilanz hat. Materialien und Methoden: Dem Versuch standen insgesamt 38 männlich kastrierte Mastschweine (Dreirassen-Kreuzung von Pietrain x Deutsches Edelschwein x Deutsche Landrasse) mit einem Einstallungsalter von ca. 12 Wochen und einer Lebendmasse von 17,3 kg bis 30,3 kg zur Verfügung. In randomisierter Reihenfolge erfolgte die Zuteilung der Schweine zu den acht Versuchsfuttern; Rohproteingehalt von 140 g kg-1 Futter und 200 g kg-1 Futter, sowie je 4 g, 10 g, 14 g oder 20 g Kalium kg-1 Futter. Die Versuchsfutter wiesen eine konstante Konzentration an Natrium und Chlorid auf. Die Hauptfutterkomponenten waren Mais und Weizen. Die beiden Rohproteingehalte wurden durch unterschiedliche Sojaextraktionsschrot- und Maisklebermengen gewonnen. Über Kaliumhydrogencarbonat (KHCO3) und Kaliumchlorid (KCl) resultierte die Einstellung der genannten Kaliumkonzentrationen sowie der vier DCAB-Stufen von -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1, und 342 mEq kg-1 Futter. In einer Adaptionsphase von 15 Tagen gewöhnten sich die Scheine an das Versuchsfutter und die Umgebung. Die Einstallung erfolgte in Einzelboxen und die Versuchstiere erhielten Wasser ad libitum. Während der anschießenden zwei Bilanzphasen von je fünf Tagen wurden die Schweine in Bilanzkäfigen gehalten. Zwischen den beiden Bilanzphasen kam es zu einer fünftägigen Pause ohne Änderung der Fütterung. In der Bilanzzeit wurden der gesamte Harn und Kot der Tiere gesammelt sowie der dazugehörige pH-Wert kontinuierlich bestimmt. Harn- und Kotaliquots wurden für Stickstoff- und Elektrolytanalysen einbehalten. Jede fünftägige Bilanz endete mit der Gewinnung einer Blutprobe von jedem Schwein aus der Vena jugulares zur Bestimmung von Kalium, Natrium, Chlorid, pH-Wert, Hydrogencarbonat, Basenüberschuss und Aminosäuren. Ergebnisse: Kalium hat einen Einfluss auf den Harn pH-Wert. Analog zur steigenden Kaliumaufnahme (DCAB↑) wurden die Harn pH-Werte basischer (-125 mEq kg-1 Futter = Ø 5,93; 342 mEq kg-1 Futter = Ø 8,37). Die Blut pH-Werte, die im Durchschnitt bei 7,21 lagen, wie auch die Hydrogencarbonat- und Basenüberschusskonzentration, reagierten aufgrund der renalen Kompensation nicht wesentlich auf die unterschiedlichen DCAB im Futter. Die dazugehörigen Kot pH-Werte waren bei -125 mEq kg-1 Futter und 66 mEq kg-1 Futter um 0,16 höher als bei den anderen beiden DCAB-Stufen. Die Stickstoffaufnahme variierte zwischen 0,90 g kg-1KM d-1 und 1,22 g kg-1KM d-1 aufgrund der beiden Rohproteingehalte (14 und 20 %) in den Versuchsrationen. Eine Senkung der DCAB im Futter bewirkte eine Verbesserung der Stickstoffverdaulichkeit von 86,1 % auf 89,9 % (p<0,05). Hingegen zeigten die Diäten mit der kaliumärmsten Konzentration die höchsten renalen Stickstoffexkretionen von 442 mg kg-1KM d-1 gegenüber den anderen drei Kaliumkonzentrationen (345 mg kg-1KM d-1). In Folge dessen ergibt sich eine Stickstoffretentionssteigerung mit zunehmender DCAB im Futter. Jedoch wurde bei 66 mEq kg-1 Futter (Kalium 10 g kg-1 Futter) die höchste Stickstoffretention von 643 mg kg-1KM d-1 festgestellt. Die Untersuchung der Blutproben ergab keine Beeinflussung der Summe aller Aminosäuren, die bei ø 44,66 mg dl-1 lag. Die Summe der essentiellen Aminosäuren war bei einer DCAB von 66 mEq kg-1 Futter im Blut geringer als bei den übrigen Variationen. Einige Parameter der Elektrolytbilanzen waren zwischen den Futtervariationen verschieden: Bei dem Versuchsfutter mit einer DCAB von -125 mEq kg-1 Futter (Kalium 4 g kg-1 Futter) schieden die Schweine Na: 2,83 mg kg-1KM d-1 und Cl: 1,54 mg kg-1KM d 1 weniger mit dem Kot und Na: 7,05 mg kg-1KM d-1 weniger mit dem Harn aus gegenüber den weiteren Versuchsgruppen. Die renale Chloridexkretion zeigte keine Variabilität. Die renale, als auch die fäkale Kaliumausscheidung nahm analog zur DCAB des Futters zu (DCAB im Futter: -125 mEq kg-1; 66 mEq kg-1; 168 mEq kg-1; 342 mEq kg-1; K-Abgabe in mg kg-1KM d-1, renal: 74,0; 273,3; 431,1; 609,1; fäkal: 24,5; 31,2; 32,6; 44,0). In der Gesamtheit betrachtet ergibt sich für die Natrium- und Chloridretention keine richtungsweisende Beeinflussung im Zusammenhang mit der DCAB der Versuchsrationen. Die Kaliumretention hingegen stieg von 66,5 mg kg-1KM d-1 (-125 mEq kg-1 Futter) auf 167,0 mg kg-1KM d-1 (342 mEq kg-1 Futter) an, was nicht von den Kaliumkonzentrationen im Blut wiedergegeben wurde. Entsprechendes gilt für die Natrium- und Chloridkonzentrationen im Blut. Schlussfolgerungen: In der Alkalisierung des Harns zeigt sich, dass der DCAB des Futters Einfluss auf den Säure-Basen Status nimmt. Der systemische pH-Wert blieb aufgrund der Puffersysteme des Organismuses weitestgehend unberührt. Durch die KHCO3-Zulagen wurde das intragastrale bzw. das intestinale pH-Milieu verändert, was sich in der schlechteren Verdaulichkeit von Stickstoff bei höherer DCAB wiederspiegelt. Die Stickstoffretention steht in keinem Zusammenhang mit der Stickstoffverdaulichkeit. Mit dem DCAB von 66 mEq kg-1 Futter bzw. K: 10 g kg-1 Futter wurde die beste Retention für Stickstoff beobachtet. Die täglichen Gewichtszunahmen und die Futterverwertungen der Versuchsschweine konnten dies allerdings nicht reflektieren. Anzumerken sei, dass für einen eindeutigen Effekt auf die tägliche Zunahme eine längere Beobachtungsphase notwendig wäre (Sprung der täglichen Zunahmen von 520 g für -125 mEq kg-1 Futter auf das Niveau von 692 g für 66 mEq kg-1 Futter und mehr). Eine Empfehlung in Anlehnung an diese Studie wäre ein DCAB-Wert um die 66 mEq kg-1 Futter. Wird dieser Wert erhöht sinkt die Stickstoffverdaulichkeit auf der anderen Seite verschlechtert sich die Stickstoffretention bei Verringerung der DCAB
Initiation: The dietary cation-anion balance (DCAB) of the feed modifies the acid-base balance and is used in the prevention of milk fever in cows, MMA in sows and urolithiasis in pets. The modification of the cation-anion ratio in diets can take an impact on biological processes inducting nitrogen metabolism. Objectives of investigations: This study objectively clarifies, whether potassium-based variation of the DCAB of the food has an influence on certain parameters of the nitrogen balance and the acid-base balance. Materials and Methods: The trial covered a total of 38 male castrated pigs (three racial crossing Pietrain x Large White x German Landrace) with a housing-age of approximately 12 weeks and a live weight of 17.3 kg to 30.3 kg. In randomized order, the pigs were allocated to the eight experimental feed: crude protein content of 140 g per kg feed and 200 g per kg feed, as well as 4, 10, 14 or 20 g of potassium per kg feed. The sodium and chloride concentrations in the feed were kept constant. The main food components were corn and wheat. The two crude protein levels were determined by various soybean meal and corn gluten quantities. Potassium hydrogen carbonate (KHCO3) and potassium chloride (KCl) were used to establish the four DCAB levels of -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1, and 342 mEq kg-1 feed. In an adaptation period of 15 days pigs were accustomed to food and environment. They were kept in individual pens and were given water ad libitum. During the following two trial phases of five days each, the pigs were kept in balance cages. Between the two trial periods, there was a break of five days (no diet change). During the trial period all urine and excrement of the animals was collected, and the respective pH-value was continuously measured. Aliquots of urine and faeces were used in nitrogen and electrolyte analyses. At the end of each five-day record a blood sample from the jugular vein was taken from each pig for determination of potassium, sodium, chloride, pH-value, hydrogen carbonate, base excess, and amino acids. Results: Potassium has a significant influence on renal pH values. Analogous to increasing potassium intake (DCAB ↑), the urine pH value turned more basic (-125 mEq kg-1 feed = 5.93; 342 mEq kg-1 feed = 8.37). The blood pH levels, which averaged at 7.21, as well as the hydrogen carbonate concentration and base excess concentration, did not respond to the different DCAB in the feed because of the renal compensation. The associated feces pH values at -125 mEq kg-1 feed and 66 mEq kg-1 feed were higher by 0.16 than at the other two DCAB levels. The nitrogen intake varied between 0.90 g kg-1BM d-1 and 1.22 g kg-1BM d-1, based on both crude proteins (14 % and 20 %) in the experimental feeds. A reduction of DCAB in the feed resulted in an improvement of the nitrogen digestibility from 86.1 % to 89.9 % (< 0.05). However, diets with the lowest concentration of potassium showed the highest renal nitrogen excretions of 442 mg kg-1BM d-1 compared to the other three concentrations of potassium (345 mg kg-1BM d-1). As a consequence, nitrogen retention increases with increasing DCAB in the feed. However, the highest nitrogen retention of 643 mg kg-1KM d-1 was found with a 66 mEq kg-1 diet (potassium 10 g kg-1 feed). The examination of blood samples revealed no influence on the sum of the amino acids, which was 44.66 mg dl-1. The sum of the essential amino acids was reduced at a DCAB of 66 mEq kg-1 in blood, similar to the other variations. Some parameters of the electrolyte balances were different between the feed variations: In the experimental diet with a DCAB of -125 mEq kg-1 diet (potassium 4 g kg-1 feed), the pigs eliminated Na: 2.83 mg kg- 1BM d-1 and Cl: 1.54 mg kg– 1BM d-1 less in the feces and Na: 7.05 mg kg- 1KM d-1 less in the urine with respect to the other experimental groups. Renal chloride excretion showed no variability. The renal and fecal excretion of potassium increased proportionally to the DCAB of the feed (DCAB in the feed: -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1; 342 mEq kg-1; K output in mg kg- 1BM d-1, renal: 74.0; 273.3; 431.1; 609.1; fecal: 24.5; 31.2; 32.6; 44.0). When viewed against the totality of results for the sodium and chloride retention, there were no trend-setting influences in connection with the DCAB of the experimental diets. The potassium retention, however, increased from 66.5 mg kg- 1BM d-1 (-125 mEq kg-1 feed) to 167.0 mg kg- 1BM d-1 (342 mEq kg -1 feed), which was not reproduced from the potassium concentrations in the blood. The same applied to the sodium and chloride concentrations in the blood. Conclusions: The alkalization of the urine shows that the DCAB of the feed influences the acid-base status. The systemic pH remained largely unaffected due to the buffer systems of the organism. The intragastric, respectively the intestinal, pH medium was changed by the addition of potassium hydrogen carbonate, which is reflected in the poorer digestibility of nitrogen at higher DCAB. The nitrogen retention is not related to the nitrogen digestibility. The best retention of nitrogen was observed with the DCAB of 66 mEq kg-1 feed (K: 10 g kg-1 feed). The daily weight gain and feed utilizations of the pigs certainly could not reflect this. It should be noted, however, that a longer observation period would be necessary for a clear effect on daily gain (jump of the daily weight gain from 520 g of -125 mEq kg-1 feed to the level of 692 g for 66 mEq kg-1 feed and more). A recommendation based on this study would be a DCAB value of 66 mEq kg-1 feed. If this value increases, the nitrogen digestibility decreases; on the other hand, the nitrogen retention deteriorated with reducing DCAB

Nous avons etudie: les proprietes d'electrochimie, de photochimie et de complexation d'anions d'une serie de recepteurs bases sur un motif ressemblant au methylviologene, le cation 2,7-diazapyrenium; les syntheses et les proprietes de complexation d'une serie de cyclointercalants, incorporant l'element plan, le naphthalene diimide; les proprietes photophysiques d'un recepteur heteroditopique, contenant un groupement intercalant et un element macrocyclique polyammonium et sa capacite de complexer des nucleotides phosphates dans une orientation preferentielle. La photocoupure des acides nucleiques par des cations diazapyreniums a ete clairement demontree par des methodes biochimiques. Deux reactifs cyclointercalants ayant des sus-unites porphyriniques montrent une photocoupure preferentielle des acides nucleiques simple brin. Ces memes composes sont capables d'inactiver certains virus sans endommager leurs cellules hotes

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Dois experimentos envolvendo 1280 pintos machos Cobb 500, foram conduzidos para avaliar as possíveis interações entre condicionamento termo precoce e balanço eletrolítico da dieta sobre o desempenho de frangos de corte, bem como estudar os efeitos do estresse térmico agudo e crônico. No d 8, as aves foram transferidas para 32 boxes, com raspas de madeira e resíduo desidratado de acerola (proporção ½ a ½ ) como cama, mantendo os mesmos tratamentos com oito repetições cada. Os dados da Exp. 1 (stress agudo) e 2 (stress crónico) foram combinados num arranjo fatorial 2x2x2 (com e sem condicionamento térmico precoce (CTP); dieta com e sem equilíbrio eletrolítico (EE); e estresse térmico agudo ou crônico. A dieta com EE foi calculada como mEq / kg para a Na + K-Cl e o valor da relação (K + Cl) / Na, com 300 mEq / kg e uma proporção de 3: 1, respectivamente. As aves foram alimentadas com: (1) uma dieta tradicional (176 mEq / kg e a relação de 3,36: 1) sem CTP; (2) dieta tradicional com CTP; (3) dieta com EE e sem CTP e (4) dieta com EE e CTP. Ração e água foram fornecidas ad libitum. Metade das aves foram expostas a 36 °C durante 24 horas com a idade de 5, enquanto que a outra metade não foi exposto a CTP. Na idade de 38 d, metade dos pintos foram termicamente desafiados por estresse térmico agudo de 36 °C durante 6h e com a idade de 35 a 39 d, outra metade dos pintos foram termicamente desafiado por um estresse térmico crônico de 32 °C por 6h. O consumo de ração, peso corporal (PC), a umidade das fezes e deposição de gordura abdominal foram determinadas a 46 d de idade e taxa de conversão alimentar ajustado foi calculado através da inclusão de PC da mortalidade. Coordenadas tricromáticas (L*, a*, e b*) foram medidos no músculo do peito, às 24h. Nenhum efeito de interação foi encontrado com nenhum dos parâmetros avaliados. Assim, não existe sinergismo para qualquer um dos traços. Houve aumento expressivo da mortalidade [(3,06-65,62%) / P <0,0001] de estresse agudo. O EE aumentou a umidade nas fezes (P = 0,0202). Os conteúdos de lipídios dos tecidos abdominais foram afetados pela exposição ao calor e diminuiu significativamente (P <0,0001) para crônica (53.9g) versus estresse agudo (127.5g). Além disso, um efeito significativo (P <0,0001) valores mais elevados foi encontrado em carne para aguda (66,4 e 23,2) versus o estresse crônico (57,6 e 17,6), em L* e b*, respectivamente. Os resultados sugerem que as aves submetidas a estresse agudo estão sujeitos a síndrome do músculo pálida aves.
Two experiments involving 1280 male Cobb 500 chicks were conducted to evaluate the possible interactions between early thermal conditioning and electrolyte balance of the diet on the performance of broiler chickens, as well as studying the effects of acute and chronic heat stress. On d 8, the broilers were transferred to 32 floor pens with wood shavings as litter while maintaining the same treatments with eight replicates each. The data from Exp. 1 (acute stress) and 2 (chronic stress) were combined in a 2x2x2 factorial arrangement [with and without early thermal conditioning (ETC)]; diet with and without electrolyte balance (EB); and acute or chronic heat stress. The diet with EB was calculated as mEq/kg for Na+K-Cl and the value the ratio (K+Cl)/Na, with 300 mEq/kg and a ratio the 3:1, respectively. The birds were fed: (1) a traditional diet (176 mEq/kg and a ratio the 3.36:1) without ETC; (2) traditional diet with ETC; (3) diet with EB and without ETC and (4) diet with EB and ETC. Feed and water were supplied ad libitum. Half of birds were exposed to 36°C for 24h at the age of 5, whereas the remaining half was not exposed to ETC. At the age of 38 d, half chicks were thermally challenged by an acute heat stress of 36°C for 6h or at the age of 35 to 39 d, another half chicks were thermally challenged by a chronic heat stress of 32°C for 6h. Feed intake, body weight (BW), moisture of feces and abdominal fat deposition were determined at 46 d of age and adjusted feed conversion ratio was calculated by including BW of mortality. Trichromatic coordinates (L*, a*, and b*) were measured on the breast muscle at 24h. No interaction effects were found for any of the parameters evaluated. Thus, there is no synergism for any of the traits. There was expressive increase of mortality [(3.06 to 65.62%) / P<0.0001] from acute stress. The EB increased moisture of feces (P=0.0202). Lipid contents of abdominal tissues was affected by heat exposure with significantly decreased (P<0.0001) to chronic (53.9g) versus acute stress (127.5g). Also, a significant effect (P<0.0001) values higher was found in meat for acute (66.4 and 23.2) versus chronic stress (57.6 and 17.6) on L* and b*, respectively. The results suggest that birds submitted to acute stress are subject to pale poultry muscle syndrome.

Orientador: Guilherme de Paula Nogueira
Cooientador: Garcia Neto, Manoel
Banca: Marcelo Vasconcelos Meireles
Banca: Antonio Celso Pezzato
Resumo: Dois experimentos envolvendo 1280 pintos machos Cobb 500, foram conduzidos para avaliar as possíveis interações entre condicionamento termo precoce e balanço eletrolítico da dieta sobre o desempenho de frangos de corte, bem como estudar os efeitos do estresse térmico agudo e crônico. No d 8, as aves foram transferidas para 32 boxes, com raspas de madeira e resíduo desidratado de acerola (proporção ½ a ½ ) como cama, mantendo os mesmos tratamentos com oito repetições cada. Os dados da Exp. 1 (stress agudo) e 2 (stress crónico) foram combinados num arranjo fatorial 2x2x2 (com e sem condicionamento térmico precoce (CTP); dieta com e sem equilíbrio eletrolítico (EE); e estresse térmico agudo ou crônico. A dieta com EE foi calculada como mEq / kg para a Na + K-Cl e o valor da relação (K + Cl) / Na, com 300 mEq / kg e uma proporção de 3: 1, respectivamente. As aves foram alimentadas com: (1) uma dieta tradicional (176 mEq / kg e a relação de 3,36: 1) sem CTP; (2) dieta tradicional com CTP; (3) dieta com EE e sem CTP e (4) dieta com EE e CTP. Ração e água foram fornecidas ad libitum. Metade das aves foram expostas a 36 °C durante 24 horas com a idade de 5, enquanto que a outra metade não foi exposto a CTP. Na idade de 38 d, metade dos pintos foram termicamente desafiados por estresse térmico agudo de 36 °C durante 6h e com a idade de 35 a 39 d, outra metade dos pintos foram termicamente desafiado por um estresse térmico crônico de 32 °C por 6h. O consumo de ração, peso corporal (PC)... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Two experiments involving 1280 male Cobb 500 chicks were conducted to evaluate the possible interactions between early thermal conditioning and electrolyte balance of the diet on the performance of broiler chickens, as well as studying the effects of acute and chronic heat stress. On d 8, the broilers were transferred to 32 floor pens with wood shavings as litter while maintaining the same treatments with eight replicates each. The data from Exp. 1 (acute stress) and 2 (chronic stress) were combined in a 2x2x2 factorial arrangement [with and without early thermal conditioning (ETC)]; diet with and without electrolyte balance (EB); and acute or chronic heat stress. The diet with EB was calculated as mEq/kg for Na+K-Cl and the value the ratio (K+Cl)/Na, with 300 mEq/kg and a ratio the 3:1, respectively. The birds were fed: (1) a traditional diet (176 mEq/kg and a ratio the 3.36:1) without ETC; (2) traditional diet with ETC; (3) diet with EB and without ETC and (4) diet with EB and ETC. Feed and water were supplied ad libitum. Half of birds were exposed to 36°C for 24h at the age of 5, whereas the remaining half was not exposed to ETC. At the age of 38 d, half chicks were thermally challenged by an acute heat stress of 36°C for 6h or at the age of 35 to 39 d, another half chicks were thermally challenged by a chronic heat stress of 32°C for 6h. Feed intake, body weight (BW), moisture of feces and abdominal fat deposition were determined at 46 d of age and adjusted feed conversio... (Complete abstract click electronic access below)
Mestre

This study focuses on the development of novel two-stage esterification-transesterification synthesis of biodiesel from used cooking oil (UCO) using novel heterogeneous catalysts. The esterification of the UCO was investigated using three types of ion exchange resins catalysts including Purolite D5081, Purolite D5082 and Amberlyst 15. Of all the catalysts investigated, Purolite D5081 resin showed the best catalytic performance and was selected for further optimisation studies. From the optimisation study, it was found that the external and internal mass transfer resistance has negligible effect on the esterification reaction. At the optimum reaction conditions, Purolite D5081 achieved 92% conversion of FFA. During reusability study, the conversion of FFA dropped by 10% after each cycle and it was found that progressive pore blockage and sulphur leaching were dominant factors that decreased the catalytic performance of the Purolite D5081 catalyst. A kinetic modelling for FFA esterification was carried out using Purolite D5081 as a catalyst. Three types of kinetic models were investigated i.e. pseudo homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHHW). Experimental data obtained from the batch kinetic studies was successfully represented by the PH model and a good agreement between experimental and calculated values was obtained. The activation energy for esterification and hydrolysis reaction was found to be 53 and 107 kJ/moL. The transesterification of pre-treated cooking oil (P-UCO) was investigated using various types of heterogeneous catalysts including Purolite CT-122, Purolite CT-169, Purolite CT-175, Purolite CT-275, Purolite D5081, Diaion PA306s and Cs-supported heteropolyacids catalysts. Of all the catalysts investigated, Diaion PA306s catalyst showed the highest conversion of triglycerides and was selected for further optimisation studies. At the optimum reaction conditions, Diaion PA306s achieved ca. 75% of triglycerides conversion. During the reusability study, Diaion PA306s catalyst gave a similar conversion of triglycerides after being reused once. Therefore, it was concluded that the resin can be used several times without losing catalytic activity. Several purification methods have been investigated and dry washing method was chosen as the best alternative for biodiesel purification.

Owing to the scarcity of lithium, discovering alternatives for lithium in rechargeable batteries is a critical requirement. Sodium is an ideal candidate for this purpose. The absence of exceptional cathode materials in sodium-ion batteries is a bottleneck in realizing the above objective. This study focused on synthesizing novel transition metal oxide cathode materials for sodium-ion batteries and improving their electrochemical properties. The outcomes of this study emphasized the importance of novel material compositions as well as the role of smart cation substitution, anion redox reaction, electrochemical activation and the effect of the combination of strategies in achieving next-generation high-capacity cathodes.

Differents procedes electromembranaires sont concus et etudies pour regenerer de la soude a partir de solutions de carbonate de sodium. En presence d'especes oxydables en faibles quantites, la regeneration s'effectue avec une cellule a une seule membrane permselective echangeuse de cations. Pour eviter l'oxydation de ces especes, par exemple le sulfure (na#2s) de la liqueur verte du procede kraft, le procede electromembranaire le plus adapte par sa simplicite et par sa capacite de fonctionnement sur le long terme, est constitue d'un electrolyseur a deux membranes echangeuses de cations, precede d'un reacteur d'acidification pour le degagement des gaz; dans la boucle reacteur-compartiment central de la cellule d'electrolyse, circule une solution de sulfate de sodium acidifiee. Une autre configuration de l'electrolyseur du procede est envisagee et testee avec une membrane echangeuse d'anions et une membrane echangeuse de cations suivant le procede classique d'electro-electrodialyse du sulfate de sodium. Ce procede est aussi compare a un electrolyseur a deux membranes echangeuses de cations avec introduction directe de la solution de carbonate et de sulfure de sodium dans le compartiment central ou se produit le degagement des gaz. Les membranes echangeuses de cations et plus particulierement les membranes echangeuses d'anions, separant le compartiment anodique du compartiment central de l'electrolyseur, sont etudiees par la methode des radiotraceurs et par spectrometrie raman. Ces procedes produisent de la soude qui peut etre aussi concentree que dans le procede chlore-soude a membrane et de l'hydrogene relativement pur dont l'utilisation par une anode a hydrogene est testee. Finalement, si les problemes d'environnement remettent en cause le procede bien etabli du four a chaux, la rentabilite de ces differents procedes devra etre reconsideree

The problem with which this research is concerned is the determination of inorganic anions and cations with single injection ion chromatography. Direct detection of the separated analyte ions occurs after the analyte ions have passed through ion-exchange resins where they are separated according to their affinity for the ion-exchange resin active sites. The techniques involve the use of essentially a non-suppressed ion chromatographic system followed by a suppressed ion chromatographic system. With this system it is possible to accomplish both qualitative and quantitative determinations.