Realizaram-se estudos potenciométricos, em combinação com medições espectrofotométricas, para caracterizar a espécie de íon manganês obtida a partir de oxidação coulométrica a corrente constante utilizando-se solução de Mn(II) (0,050 mol.L-1) em N3- (0,50 a 2,0 mol.L-1) e H+ (0,01 mol.L-1). Graficamente foi possível concluir que a espécie gerada é Mn(III) e obter os valores dos potenciais condicionais de redução, E0\'x, do par Mn(III)/Mn(II), em soluções tampão N3-/HN3, de concentração de N3- 0,50; 1,0; 1,5; 2,0 e 4,0 mol.L-1 e H+ 0,010 mol.L-1, sendo 0,468, 0,421, 0,396, 0,377 e 0,336 V (vs. ECS), respectivamente. Esses valores de E0\'x permitiram o cálculo das constantes de equilíbrio para os complexos no sistema Mn(III)/N3-, sendo: β1 = 1,23.105 M-1, β2 = 6,03.108 M-2, β3 = 2,37.1011 M-3, β4 = 1,54.1011 M-4 e β5 = 9,57.1011 M-5 (T = 25,0 ± 0,1 ºC, I = 2,0 mol.L-1 com NaClO4). Os valores calculados para as absortividades molares, em 430 nm, para as espécies [Mn(N3)3], [Mn(N3)4]- e [Mn(N3)5]2- foram 226, 3.680 e 6560 mol-1.L.cm-1, respectivamente. Para o estudo do cátion Co(II), foram efetuadas oxidações coulométricas da mesma forma e nas mesmas condições que para o cátion Mn(II). Os valores de E0\'x encontrados para o par Co(III)/Co(II) foram 0,400, 0,338, 0,302, 0,277 e 0,228 V (vs. ECS), para as concentrações de N3- 0,50; 1,0; 1,5; 2,0 e 4,0 mol.L-1 e H+ 0,010 mol.L-1. Com os valores de E0\'x obtidos para os pares Co(III)/Co(II) e Mn(III)/Mn(II), calcularam-se as constante de equilíbrio global, K, para a reação redox entre [Co(N3)n]3-n e [Mn(N3)n]2-n, encontrando-se os valores 7,1xl0-2, 4,0x10-2, 2,6x10-2, 2,0x10-2 e l,5x10-2, para os tampões acima descritos, respectivamente. Outros estudos revelaram a possível formação da espécies Mn(VI) quando KMnO4 e K2MnO4 são adicionados, separadamente, a uma solução tampão azoteto, por exemplo, N3- = 1,5 mol.L-1 e HN3 = 0,05 mol.L-1. / Spectrophotometric studies combined with coulometric generation of Mn(III), in presence of large excess of Mn(II), showed a maximum absorbance peak at 430 nm. The average molar absorptivity increases with azide concentration (0.44 to 3.9 mol.L-1) from 3,100 to 6,300 mol-1.L.cm-1, showing a stepwise complex formation. Potential measurements of the Mn(III)/Mn(II) system in several azide aqueous buffers solutions: 1.0x10-2 mol.L-1 HN3, (0.50 to 2.0 mol.L-1) N3- and 5.0x10-1 mol.L-1 Mn(II) and constant ionic strength 2.0 mol.L-1, kept with sodium perchlorate, leads to the conditional potential, E0\'x, in several azide concentrations at 25.0 ± 0.1 ºC (0.468, 0.421, 0.396, 0.377 e 0.336 V (vs. SCE) for the 0.50; 1.0; 1.5; 2.0 and 4.0 mol.L-1 N3- concentration, respectively). Considering the overall formation constants of Mn(II)/N3-, from former studies, and the potential, E0\'s = 1.063 V vs. SCE, for Mn(III)/Mn(II) system in non-complexing medium, it was possible to calculate the Fronaeus function, F0(L), and the following overall formation constants: β1 = 1.2x105 M-1, β2 = 6.0x108 M-2, β3 = (2.4±0.7)x1011 M-3, β4 = (1.5±0.5)x1011 M-4 and β5 = (9.6±.0.8)x1011 M-5 for the Mn(III)/N3- complexes. The molar absorptivity values, at 430 nm, found for the species [Mn(N3)3], [Mn(N3)4]- and [Mn(N3)5]2- were 226, 3,680 and 6,560 mol-1.L.cm-1, respectively. Similar studies with Co(II) in the same conditions, lead to the following conditional potentials, E0\'x, for the Co(III)/Co(II) system: 0.400, 0.338, 0.302, 0.277 e 0.228 V (vs. SCE). Using the E0\'x values obtained for both systems, Co(III)/Co(II) and Mn(III)/Mn(II), it was possible to calculate the equilibrium constant for the redox reaction between [Co(N3)n]3-n and [Mn(N3)n]2-n. The values found were 7.1xl0-2, 4.0x10-2, 2.6x10-2, 2.0x10-2 and 1.5x10-2, for 0.50; 1.0; 1.5; 2.0 and 4.0 mol.L-1 N3- concentration, respectively, in the same acidity (1.0x10-2 mol.L-1 HN3).

O objetivo deste trabalho foi determinar a influência do ferro e do manganês em uma liga de alumínio com 9% de silício (% em peso). Para isto, foram elaboradas duas famílias de liga Al-9%Si: uma com os teores de 0,1%, 0,4%, 0,8% e 1,2% de Fe e uma segunda liga de Al-9%Si-0,8%Fe com teores de 0,1%, 0,4% e 0,7% de Mn. Para a realização deste estudo, foram produzidos corpos de prova de tração fundidos em coquilha, segundo a norma ASTM B108. Os corpos de prova obtidos foram tracionados para avaliação das propriedades mecânicas, em seguida, foram submetidos a uma análise microestrutural por microscopia óptica (MO) e eletrônica de varredura (MEV). As superfícies de fratura dos corpos de prova tracionados foram também observadas por MEV com a finalidade de comparar o efeito das adições de Fe e Mn. O efeito da adição crescente de Fe na liga Al-9%Si foi observado no ensaio de tração que mostrou queda tanto nos limites de resistência e de escoamento como no alongamento, decorrentes da formação da fase β-Al5FeSi que apresentou morfologia em plaquetas, interrompendo a continuidade da matriz de alumínio. Para teores abaixo de 0,4% de Fe, ocorreu um ligeiro aumento da resistência mecânica que pode ser atribuído à formação da fase α-Al8Fe2Si, que apresentou morfologia tipo escrita chinesa, que não interrompe a continuidade da matriz. Com adição de teores crescentes de Mn na liga Al-9%Si-0,8%Fe ocorreu uma elevação do limite de resistência e do alongamento, mas uma queda do limite de escoamento, quando comparados com a mesma liga sem adição de Mn. Conclui-se que esse comportamento pode ser atribuído a mudança de morfologia do intermetálico de plaquetas para escrita chinesa que intercala a matriz dúctil com a fase frágil, devido a adição do Mn. / This study aims to determine the influence of iron and manganese in an aluminum alloy with 9% silicon (% by weight). Were prepared two families of alloy Al-9%Si: one with the content of 0.1%, 0.4%, 0.8% and 1.2% Fe and a second alloy of Al-9% Si-0,8%Fe content of 0.1%, 0.4% and 0.7% Mn. For this study, tensile specimens were produced in permanent mold casting according to ASTM B108. The specimens obtained were pulled for quantitative evaluation of the mechanical properties and were subjected to a qualitative metallographic evaluation. Qualitative analysis of the bodies of tensile fracture test was conducted in order to compare the effect of additions of Fe and Mn. The effect of incremental addition of Fe in the alloy Al-9% Si was observed in the tensile test that showed a decrease in both the tensile and elongation flow as resulting from the formation of β-Al5FeSi phase platelet morphology showed that interrupting the continuity of aluminum matrix. To levels below 0.4% Fe, there was a slight increase in strength can be attributed to the formation of α-Al8Fe2Si phase morphology presented in chinese script that does not interrupt the continuity of the matrix. With addition of increasing concentrations of Mn in the alloy Al-9% Si-0, 8% Fe was an increase in the tensile strength and elongation but fall of yield stress when compared to the same alloy without Mn addition. We conclude that this behavior can be attributed to a change in morphology of the intermetallic platelets to chinese writing interspersing the ductile matrix with brittle phase due to the addition of Mn.

No description available.

Barium peroxide was selected as oxidant in a fundamental physico-chemical study of binary pyrotechnic systems on account of its apparently simple decomposition stoichiometry. With this selection, the choice of fuel was governed by the requirements of a self-sustaining reaction at combustion temperatures below the melting point of the platinum/rhodium thermocouples (∼1760°C) used for recording temperature-time profiles during burning, and at burning rates not exceeding the response of the sensors used to monitor combustion. Both manganese and molybdenum metal powders satisfied the above requirements. Strontium peroxide was also available as an oxidant and so the combustion of binary metal/oxidant systems using both fuels and both BaO₂ and SrO₂ oxidants was investigated. The Mn/BaO₂, MoBaO₂ and Mn/SrO₂ systems burnt over a wide range of compositions, but the range of ignitable compositions for the Mo/SrO₂ system was very limited. The linear burning rates, for all these systems, ranged from 2 to 12 mm s⁻¹ and burning rates were increased by the use of smaller particle-sizes of fuel and greater loading pressures. Inert additives generally decreased the burning rate. Temperature-time profiles were recorded for all the compositions which sustained combustion. Kinetic parameters were estimated from the shapes of these profiles using procedures developed by Hill et al and Boddington and Laye. Activation energies derived from the profiles were low (3 to 40 kJ mol⁻¹) and support suggestions that reactions at high temperatures are controlled by diffusion processes. Thermal analysis was used to identify the processes occurring in the four systems. The main exothermic events were observed to correspond approximately with the onset of oxidant decomposition. A pre-ignition reaction was tentatively identified in the Mn/BaO₂ system. Oxidation of the metal fuels was generally incomplete, probably because of the formation of protective layers of product. Activation energies, derived from thermal analysis results, were in the range of from 70 to 720 kJ mol⁻¹. Ternary systems containing either mixed fuels or mixed oxidants were also examined. No interactions hetween the fuels or between the oxidants were observed. Other techniques used included bomb calorimetry, measurement of thermal conductivity, X-ray powder diffraction, infrared spectroscopy and scanning electron microscopy.

The prognosis for multiple myeloma (MM) and the activated B-cell subtype of diffuse large B-cell lymphoma (ABC DLBCL) is poor. Gene expression profiling studies have identified that the transcription factor, nuclear factor kappa B (NF-κB) is overexpressed and confers a poor prognosis in MM and ABC DLBCL. NF-κB regulates the transcription of genes involved in cell proliferation and survival. Thus, several groups have tried to identify and/or develop agents that target NF-κB to improve therapy and patient prognosis for MM and ABC DLBCL. Our laboratory has shown that the manganese porphyrin MnTE-2-PyP5+ inhibits NF-κB in a murine lymphoma cell culture model and enhances tumor cell death in combination with dexamethasone and cyclophosphamide, two agents that are routinely used to treat these neoplasms. MnTE-2-PyP5+ inhibits NF-κB by glutathionylating p65, a member of the NF-κB family. The objective of the following studies was to determine whether MnTE-2-PyP5+ enhances the chemotherapeutic response in human MM and ABC DLBCL cells that overexpress and depend on NF-κB for survival. The following studies demonstrate that MnTE-2-PyP5+ glutathionylates and inhibits NF-κB in human MM and ABC DLBCL cells. MnTE-2-PyP5+ also synergizes with several MM and DLBCL chemotherapeutics, including dexamethasone, cyclophosphamide, vincristine and bortezomib to enhance cell death. The data from these human cell lines will provide the basis for future studies to test MnTE-2-PyP5+ in animal models and for translating MnTE-2-PyP5+ to the clinic.

The north side of Cowichan Lake, Vancouver Island B.C. is underlain by volcanic rocks, sediments, and intrusives of Mesozoic age. The oldest rocks, Jurassic or Triassic flows known as the Sicker andesites, are conformably overlain by about 3000 feet of cherty tuffs, coarser pyroclastics, and small lenses of limestone known as the Sicker sediments. Cherty tuffs form the lower members of the Sicker sediments, felspathic tuffs the central members, and coarser pyroclastics the upper members. About 2000 or 3000 feet of basaltic and andesitic flows conformably overly the Sicker sediments. The Sicker andesites and sediments and younger flows are intruded by large dyke-like bodies of granodiorite or quartz monzonite, known as the Saanich granodlorite and correlated with the Coast Range intrusives. Upper Cretaceous shales sandstones and conglomerate unconformably overlie the volcanics and Intrusives. The Sicker series and overlying flows are tightly folded into overturned and asymmetrical northwesterly trending synclines and anticlines. The Cretaceous rocks are gently folded and dip north along a narrow belt on the north side of a down-faulted block. Manganese deposits occur in the lower cherty beds of the Sicker sediments as lens shaped bodies parallel to the bedding of the sediments. They are commonly in chert free from felspatnic material, and are always associated with jasper or jaspery sediments. The main manganese minerals are rhodonite, spessartite, an unidentified yellow manganese silicate, and small amounts of rhoaochrosite. Residual manganese oxides coat the surfaces of the deposits. Several features of the deposits, such as the fact that rhodonite commonly cross cuts and replaces the chert suggest that the deposits are of replacement origin. Other features such as their bedded appearance and the fact that they occur, at about the same horizon In the Sicker sediments indicate a sedimentary origin. Theoretical considerations support the view that the deposits are sedimentary and suggest that the replacement features were formed by metamorphism. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

This study examined the effects of low to moderate doses of manganese (0, 250, or 750 _g per day from PD 1-21) on a comprehensive battery of behaviors in rats during the neonatal period, preweanling period, and in adulthood.

Doctor Educationis / Energy storage technologies are rapidly being developed due to the increased awareness of global warming and growing reliance of society on renewable energy sources. Among various electrochemical energy storage technologies, high power supercapacitors and lithium ion batteries with excellent energy density stand out in terms of their flexibility and scalability. However, supercapacitors are handicapped by low energy density and batteries lag behind in power. Supercapatteries have emerged as hybrid devices which synergize the merits of supercapacitors and batteries with the likelihood of becoming the ultimate power sources for multi-function electronic equipment and electric/hybrid vehicles in the future. But the need for new and advanced electrodes is key to enhancing the performance of supercapatteries. Leading edge technologies in material design such as nanoarchitectonics become very relevant in this regard. This work involves the preparation of vanadium pentoxide (V2O5), pristine and zinc doped lithium manganese silicate (Li2MnSiO4) nanoarchitectures as well as their composites with hydroxylated graphene (G-ol) and carbon nanotubes (CNT). / 2023-12-02

This thesis reports the development of a novel drug delivery system consisting of hollow nanoparticles, formed from manganese dioxide (δ-MnO2) sheets, that are coated with polydopamine and folic acid to selectively target cancer cells. The biodegradability and colloidal stability of the uncoated hollow nanoparticles were investigated in comparison to solid MnO2 nanoparticles and graphene oxide sheets. The MnO2 hollow nanoparticles degraded at a faster rate and seem to have a higher surface area and better colloidal dispersion than solid MnO2 nanoparticles. Xanthan gum was proven to improve colloidal dispersion of these hollow nanoparticles and were used for further cell studies. In this study, cancer and healthy cells were treated with coated hollow nanoparticles, and results indicate that this novel hollow nanoparticle may preferentially target and kill cancer cells. Particle aggregation has shown to be toxic to cells. Further studies with this novel drug delivery system may lead to a groundbreaking solution to targeted cancer therapy. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

The submitted paper covers manganese comprehensively. The introduction provides an overview of its basic physical and chemical properties. Its compounds are discussed individually, including their preparation, production, and practical uses. Furthermore, a list of analytical methods in which manganese is involved in the form of its compounds as reagents is included. The same section includes an overview of analytical methods whereby manganese and its compounds are detected, primarily in water industry processes. Attention is paid to manganese as a non-negligible constituent of the various parts of the environment. The section on manganese’s biogenic properties is interesting from the viewpoint of its toxicity as well as its role as an important biogenic element, indispensable primarily for mammals. The subsequent chapters discuss the various methods which are suitable, under specific conditions, for separation in the treatment of surface and underground water aimed at producing drinking, process, or industrial water, where a minimal concentration of this metal is required. The impact of the physical/chemical conditions which influence the efficiency of separation in a manner ranging from non-negligible to principal, is discussed further on. Given the specifics of treatment of surface [and] underground water, the chapters provide more details on the processes suitable for specific types of matrix and specific conditions. Next chapters sum up many years of the author’s observations and experiences in the various parts of the water management system, from the raw water source to treatment to distribution, focusing on surface and underground water separately. Last chapter describes the construction of a water treatment plant model, its launch and calibration, and the tests focused on separating manganese by way of coagulation using aluminium and iron sulphate.