Release kinetics of multi-nutrients from volcanic rock mining by-products: evidences for their use as a soil remineralizer

Great quantities of stone by-products are stored alongside different exploiting mines in south Brazil, which are becoming an unsustainable environmental issue. Powder materials of andesite and dacite rocks were obtained from two mining companies of Southern Brazil. The particle size classification of the materials was determined by sieving. The X-ray diffraction (XRD) technique was used to identify the mineral phases of the by-products and X-ray fluorescence (XRF) was applied to determine their chemical compositions. The concentrations of calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P) and silicon (Si) released by the by-products were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Dissolution rates of andesite and dacite rocks were measured in Milli-Q water, and in solutions of 0.1 mol L−1 citric acid, and Milli-Q water acidified with 0.5 mol L−1 acetic acid, as a function of reaction times at 24–96 h (short-term), and at 96–5760 h (long-term). The solutions were agitated continuously on a mechanical rotatory shaker at room temperature. The parabolic diffusion, simplified Elovich, and power function models were applied at both time slots of solid-solution reaction. The results indicated that the relationships of quantity of released multi-nutrients were well described by power equation: ln qt = ln a + b ln t. Dissolution rates were obtained based on the release of Ca, K, Mg, P and Si at a steady state under far from equilibrium conditions. Dissolution rates of both by-products were not affected, within the experimental uncertainty, by Milli-Q water. Although the by-products dissolution rates were unaffected by Milli-Q water, its rates are increased along the time. The dissolution of the by-products minerals was significantly affected by the pH of the solutions. The multi-elements release by both by-products in 0.1 mol L−1 citric acid solution was significantly larger than another solutions, indicating that exchangeable cations were readily available in citric acid solution. The results obtained from power function model in two reaction time intervals can contribute to estimate the multi-nutrients-supplying power of by-products to soil. The present study provides both to solving an environmental issue associated with Brazilian rock exploitation and to create an alternative for soil fertilization and a more sustainable agriculture

Top-tier advisors in M&A transactions : they used to matter

This master thesis investigates the effect of top-tier advisors on bidder returns, probability of completion and time to completion of M&A deals announced between January 1995 and December 2015. In this context, the fees received by top-tier advisors and their ability to identify and appropriate synergies are also subjected to study. Based on a sample of 6716 U.S. and cross border deals, we found that (1) after 2001 top-tier advisors are no longer associated with higher cumulative abnormal returns; (2) toptier advisors are neither significantly associated with higher probability of completion nor with shorter time to completion in acquisition of public targets; (3) top-tier advisors can indeed identify deals with larger synergies, butthey fail to appropriate them to the bidder firm; (4) top-tier advisors received higher fees on U.S. deals than non-top-tier advisors would have demanded for the same deals; (5) when considering the largest deals (Mega Deals), after 2001 it is found no support for the top-tier advisors superiority neither in U.S. nor in cross border deals.Esta tese investiga o efeito de consultores top em fusoes e aquisiçoes anunciadas entre janeiro de 1995 e dezembro de 2015. Neste ambito e estudado o retorno da empresa adquirente, a probabilidade de conclusao da transaçao, o tempo para a conclusao da transaçao, a capacidade de o consultor identificar sinergias e de as apropriar para a empresa licitante. Finalmente, e estudado o papel dos consultores top no caso especffico das grandes transaçoes. Com base numa amostra de 6716 transaçoes de alvos americanos e nao americanos, chegou-se a conclusoes de que (1) ap6s 2001 os consultores top nao estao associados a retornos acumulados superiores a consultores nao top (2) consultores top nao estao significativamente associados a uma maior probabilidade de conclusao da transaçao, assim como nao estao associados a um menor tempo para a concretizaçao de transaçoes no que se refere a alvos publicos (3) consultores top sao capazes de identificar negócios com maiores sinergias, no entanto, nao sao capazes de as apropriar para a empresa licitante (4) consultores top receberam maiores comissoes do que aquelas que seriam cobradas por consultores nao top nas mesmas transaçoes (5) no que se refere as grandes transaçoes, após 2001 nao sao encontradas evidencias da superioridade dos consultores top quer em alvos americanos, quer em alvos nao americanos

O comércio atacadista e a estruturação da periferia urbana de Uberlândia (MG)

This study is a spatial process analyze engendered by wholesaler self-service stores and wholesaler in a retail scale in the Uberlândia urban mesh, mainly in suburban areas. Since its foundation, Uberlândia city implemented infrastructures for supporting the supply chain logistics activities, such as: train station, highways and warehouses. The local companies’ creation which works with wholesaler commerce and telecommunication (after 50’s), these ones consolidates Uberlândia as a city polo. Therefore, different kind of wholesale companies establishing in the city, such as self-service wholesales and third-party logistics, with a expressive expansion and diversification after 2010 years. After 2005 was observed, as well, the duplication and road resurfacing, access way building, viaduct, trenches, furthermore ring roads. For the research development were done bibliographic searches, websites and official files searches, field survey for the photographic record and collecting data. The dissertation was divided in four chapter that show, respectively: theoretical and historic aspects from wholesalers section and city development; characterization about Uberlândia-MG and their relationships with the trade and stocks distribution; the flows analysis in the areas of influence of each self-service wholesalers and their relationship to the configurational structure in town; and, finally, the changes in morphology and use and occupation of the soil around of the selfservice wholesalers and the consequences in the life of the city relationships and the daily urbanite.Dissertação (Mestrado)O presente trabalho consiste na análise dos processos espaciais engendrados pelos estabelecimentos atacadistas de autosserviço e atacarejos na malha urbana de Uberlândia, mais precisamente em áreas periféricas. O municipio de Uberlândia-MG desenvolveu-se tendo como uma de suas principais atividades econômicas o comércio e distribuição de mercadorias, assim, desde sua gênese uma série de infraestruturas, tais como: estação ferroviária, estradas e armazéns foram implantadas na cidade para dar suporte à realização destas atividades. A criação de empresas de capital local no ramo do comércio atacadista e das telecomunicações (a partir da década de 1950), consolidaram o caráter de cidade polo de Uberlândia. Consequentemente, empresas de outras modalidades do atacado passaram a se instalar na cidade, como os atacadistas de autosserviço e operadores logísticos, com uma vultosa ampliação e diversificação do ano de 2010 em diante. A partir de 2005 observou-se, também, a duplicação e recapeamento de rodovias, construção de alças de acesso, viadutos, trincheiras, além da conclusão de trechos do anel viário. Para o desenvolvimento da pesquisa foram realizados levantamentos bibliográficos, em websites e documentos oficiais, além de pesquisas de campo para registro fotográfico e levantamento de dados, por meio de fichas e questionários e, por fim, o tratamento estatístico e cartográfico dos dados coletados. A dissertação encontra-se dividida em quatro capítulos que abordam, respectivamente: aspectos teóricos e históricos do setor atacadista e do desenvolvimento das cidades; caracterização da área de estudo (Uberlândia-MG) e sua relação com o comércio e distribuição de mercadorias; a análise dos fluxos das áreas de influência de cada um dos atacadistas de autosserviço e sua relação com a estrutura configuracional da cidade; e, por fim, as alterações na morfologia e no uso e ocupação do solo no entorno dos atacadistas de autosserviço e as consequências na vida de relações da cidade e no cotidiano dos citadinos

Identification of mercury and nanoparticles in roots with different oxidation states of an abandoned coal mine

The morphology and composition of roots with different degrees of oxidation as a function of time were evaluated aiming to identify possible hazardous elements and nanoparticles. The roots were obtained from an abandoned coal mine located in the city of Criciúma, Santa Catarina, Brazil. From the roots, analyses were performed to identify nanoparticles (NPs) and ultrafine particles (UFPs), containing possible hazardous elements (PHEs) that cause potential environmental risks and impacts on human health. The identification of nanoscale materials requires greater robustness, so advanced integrated techniques have been used. The characterization of different types of roots was done by using focused ion beam (FIB), to evaluate nano-compound assemblies with high-resolution transmission electron microscopy/energy dispersive spectroscopy (HR-TEM/EDS). The results showed the presence of NPs containing Hg, Co, Cr, Ni, and V. The presence of these elements has increased consistently with the increase of C concentration in the roots, suggesting that the PHEs were gradually released from organic matter and inorganic minerals of coal. However, even with their decrease in roots, it was found that these elements still remained in the soil in significant quantities, even after 15 years of inactivation of the coal mine

Nanoparticles and interfaces with toxic elements in fluvial suspended sediment

Studies examining nanoparticles (NPs) and hazardous elements (HEs) contained in suspended sediments (SSs) are vital for watershed administration and ecological impact evaluation. The biochemical consequence of titanium-nanoparticles (Ti-NPs) from SSs in Colombia's Magdalena River was examined utilizing an innovative approach involving nanogeochemistry in this study. In general, the toxicity and the human health risk assessment associated with the presence of some Ti-NPs + HEs in SSs from riverine systems need to be determined with a robust analytical procedure. The mode of occurrence of Ti-NPs, total Ti and other elements contained within SSs of the Magdalena River were evaluated through advanced electron microscopy (field emission scanning electron microscope-FE-SEM and high resolution transmission electron microscope-HR-TEM) coupled with an energy dispersive X-ray microanalysis system (EDS); X-Ray Diffractions (XRD); and inductively coupled plasma-mass pectrometry (ICP-MS). This work showed that enormous quantities of Ti-NPs were present in the river studied and that they displayed diverse eochemical properties and posed various possible ecological dangers. Ti-NP contamination indices must be established for measuring the environmental magnitudes of NP contamination and determining contamination rank among rivers. Finally, SS contamination guidelines must be recommended on an international level. This study contributes to the scientific understanding of the relationship of HE and Ti-NP dynamics from SSs in riverine systems around the world

Analysis of the influence of thickness on fire reaction performance in polyisocyanurate core sandwich panels

Sandwich panels (also known as insulated panels) have been traditionally used for industrial buildings and warehouses, but nowadays are being increasingly a favorable choice in building construction, mainly in wall cladding and roofing systems. This paper presents the results of an experimental and statistical comparative analysis of Fire Reaction development in sandwich panels consisting of steel sheeting and Polyisocyanurate (PIR) foam core. All these PIR core sandwich panels with joints kept the same dimensions (1000 mm × 1500 mm) + (500 mm × 1500 mm), but different thicknesses (30, 50, 100 and 150 mm). Five Single Burning Item (SBI) tests were carried out on individual PIR sandwich panels with vertical joints and their results were compared between themselves. It was possible to observe through an analysis of variance that there is an influence of the sample thickness in the individual results of the SBI test parameters; however, this variability has no significant influence on the Fire Reaction performance of the samples. Overall, the importance of these alternative sandwich panels is the increase in performance in the constructive processes and the offered comfort through its thermal insulation characteristics

PUBLIC VALUE AND IT CAPACITY IN AN UNSTABLE ENVIRONMENT: CASE STUDY IN GOVERNMENT AGENCY

This study addresses, in a qualitative method, the explanation of how technical artifacts are socially constructed, providing IT flexibility, allowing operational capacity to generate public value. One of the premises of the Public Value Operational Capacity points out that flexibility is a fundamental aspect for success in government agencies. The study consists of a qualitative analysis of the revealing single-case study method. A preliminary analysis indicates a deficiency in the social constructions of IT artifacts, considering that the objectives in government organization are constantly changing due to changes in public policy. As a result, this study helps bridge the gap through a theoretical perspective on IT flexibility by providing an intuitive approach to IT management and public value management. From a practical point of view, we believe the results of this study will offer several management implications for IT and public policy managers