Biobased films prepared from NaOH/thiourea aqueous solution of chitosan and linter cellulose

In the present study, films based on linter cellulose and chitosan were prepared using an aqueous solution of sodium hydroxide (NaOH)/thiourea as the solvent system. The dissolution process of cellulose and chitosan in NaOH/thiourea aqueous solution was followed by the partial chain depolymerization of both biopolymers, which facilitates their solubilization. Biobased films with different chitosan/cellulose ratios were then elaborated by a casting method and subsequent solvent evaporation. They were characterized by X-ray analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermal analysis, and tests related to tensile strength and biodegradation properties. The SEM images of the biofilms with 50/50 and 60/40 ratio of chitosan/cellulose showed surfaces more wrinkled than the others. The AFM images indicated that higher the content of chitosan in the biobased composite film, higher is the average roughness value. It was inferred through thermal analysis that the thermal stability was affected by the presence of chitosan in the films; the initial temperature of decomposition was shifted to lower levels in the presence of chitosan. Results from the tests for tensile strength indicated that the blending of cellulose and chitosan improved the mechanical properties of the films and that an increase in chitosan content led to production of films with higher tensile strength and percentage of elongation. The degradation study in a simulated soil showed that the higher the crystallinity, the lower is the biodegradation rate.

Chitosan, sisal cellulose, and biocomposite chitosan/sisal cellulose films prepared from thiourea/NaOH aqueous solution

Environmentally friendly biocomposites were successfully prepared by dissolving chitosan and cellulose in a NaOH/thiourea solvent with subsequent heating and film casting. Under the considered conditions, NaOH/thiourea led to chain depolymerization of both biopolymers without a dramatic loss of film forming capacities. Compatibility of both biopolymers in the biocomposite was firstly assessed through scanning electron microscopy, revealing an intermediate organization between cellulose fiber network and smoothness of pure chitosan. DSC analyses led to exothermic peaks close to 285 and 315 degrees C for the biocomposite, compared to the exothermic peaks of chitosan (275 degrees C) and cellulose (265 and 305 degrees C), suggesting interactions between chitosan and cellulose. Contact angle analyses pointed out the deformation that can occur at the surface due to the high affinity of the;e materials with water. T(2) NMR relaxometry behavior of biocomposites appeared to be dominated by chitosan. Other properties of films, as crystallinity, water sorption isotherms, among others, are also discussed. (C) 2010 Published by Elsevier Ltd.

Temperature and common-ion effect on magnesium oxide (MgO) hydration

MgO based refractory castables draw wide technological interest because they have the versatility and installation advantages of monolithic refractories with intrinsic MgO properties, such as high refractoriness and resistance to basic slag corrosion. Nevertheless, MgO easily reacts with water to produce Mg(OH)(2), which is followed by a large volumetric expansion, limiting its application in refractory castables. In order to develop solutions to minimize this effect, a better understanding of the main variables involved in this reaction is required. In this work, the influence of temperature, as well as the impact of the chemical equilibrium shifting (known as the common-ion effect), on MgO hydration was evaluated. Ionic conductivity measurements at different temperatures showed that the MgO hydration reaction is accelerated with increasing temperature. Additionally, different compounds were added to evaluate their influence on the reaction rate. Among them, CaCl(2) delayed the reaction, whereas KOH showed an opposite behavior. MgCl(2) and MgSO(4) presented similar results and two other distinct effects, reaction delay and acceleration, which depended on their concentration in the suspensions. The results were evaluated by considering the kinetics and the thermodynamics of the reaction, and the mechanical damages in the samples that was caused by the hydration reaction. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Spatiotemporal Pattern Formation in the Oscillatory Electro-Oxidation of Sulfide on a Platinum Disk

Spatiotemporal pattern formation in the electrocatalytic oxidation of sulfide on a platinum disk is investigated using electrochemical methods and a charge-coupled device (CCD) camera simultaneously. The system is characterized by different oscillatory regions spread over a wide potential range. An additional series resistor and a large electrode area facilitate observation of multiple regions of kinetic instabilities along the current/potential curve. Spatiotemporal patterns on the working electrode, such as fronts, pulses, spirals, twinkling eyes, labyrinthine stripes, and alternating synchronized deposition and dissolution, are observed at different operating conditions of series resistance and sweep rate.

The role of HBF(4) in electro-catalysis: Arsenic contamination and anion adsorption

We present in this work a comprehensive investigation of the role played by dissolved tetrafluoroboric acid on the electrochemical response of a polycrystalline platinum electrode in acidic media. HBF(4) from two different suppliers was employed and characterized in terms of the amount of arsenic contamination by Inductively Coupled Plasma-Optical Emission Spectroscopy. The effect of different amounts of HBF(4) on the voltammetric profile of the Pt vertical bar HClO(4)(aq) interface was investigated by means of electrochemical quartz crystal nanobalance (EQCN). Despite the comparable cyclic voltammograms, the presence of arsenic in one of the two HBF(4) used resulted in dramatic variations in the mass change profile, which evidences the deposition/dissolution of arsenic prior to the surface oxidation. For the arsenic-free HBF(4), its effect on the mass change profile was mainly associated to anion adsorption. The impact of dissolved HBF(4) on the electro-oxidation of formic acid was rationalized in terms of two contributions: current enhancement at low potentials due to the arsenic-assisted formic acid electro-oxidation and inhibition at high potentials due to anion adsorption. (C) 2011 Elsevier B.V. All rights reserved.

Modeling precipitation and its effect on recrystallization during hot strip rolling of niobium steels

Using a physically based model, the microstructural evolution of Nb microalloyed steels during rolling in SSAB Tunnplåt’s hot strip mill was modeled. The model describes the evolution of dislocation density, the creation and diffusion of vacancies, dynamic and static recovery through climb and glide, subgrain formation and growth, dynamic and static recrystallization and grain growth. Also, the model describes the dissolution and precipitation of particles. The impeding effect on grain growth and recrystallization due to solute drag and particles is accounted for. During hot strip rolling of Nb steels, Nb in solid solution retards recrystallization due to solute drag and at lower temperatures strain-induced precipitation of Nb(C,N) may occur which effectively retard recrystallization. The flow stress behavior during hot rolling was calculated where the mean flow stress values were calculated using both the model and measured mill data. The model showed that solute drag has an essential effect on recrystallization during hot rolling of Nb steels.

Homogenization of Precipitation Hardening Nickel Based Superalloys

Allvac 718 Plus and Haynes 282 are relatively new precipitation hardening nickel based superalloys with good high temperature mechanical properties. In addition, the weldability of these superalloys enhances easy fabrication. The combination of high temperature capabilities and superior weldability is unmatched by other precipitation hardening superalloys and linked to the amount of the γ’ hardening precipitates in the materials. Hence, it is these properties that make Allvac 718 Plus and Haynes 282 desirable in the manufacture of hot sections of aero engine components. Studies show that cast products are less weldable than wrought products. Segregation of elements in the cast results in inhomogeneous composition which consequently diminishes weldability. Segregation during solidification of the cast products results in dendritic microstructure with the segregating elements occupying interdendritic regions. These segregating elements are trapped in secondary phases present alongside γ matrix. Studies show that in Allvac 718Plus, the segregating phase is Laves while in Haynes 282 the segregating phase is not yet fully determined. Thus, the present study investigated the effects of homogenization heat treatments in eliminating segregation in cast Allvac 718 Plus and Haynes 282. Paramount to the study was the effect of different homogenization temperatures and dwell time in the removal of the segregating phases. Experimental methods used to both qualify and quantify the segregating phases included SEM, EDX analysis, manual point count and macro Vickers hardness tests. Main results show that there is a reduction in the segregating phases in both materials as homogenization proceeds hence a disappearance of the dendritic structure. In Allvac 718 Plus, plate like structures is observed to be closely associated with the Laves phase at low temperatures and dwell times. In addition, Nb is found to be segregating in the interdendritic areas. The expected trend of increase in Laves as a result of the dissolution of the plate like structures at the initial stage of homogenization is only detectable for few cases. In Haynes 282, white and grey phases are clearly distinguished and Mo is observed to be segregating in interdendritic areas.

Skilsmässor och separationer : Betydelsen av rollspecialisering och jämställdhet

Divorces and separations: the impact of role specialisation and equality At the same time as women made their large scale entrance on the labour market divorce rates increased in most western societies. This combination of societal trends was widely understood from the perspective of the specialization and trading model, which implies undermined marital stability through decreasing interdependency between husband and wife. We argue the need to acknowledge the new roles, and perceptions of these roles, men and women have in order to explain differences in separation and stability among couples. When both partners are expecting to be in paid labour and share housework responsibilities, specialisation could actually be a risk factor for cohabitational dissolution. This article uses a ten year longitudinal database of all Swedish cohabiting first time parents in 1993. The analyses generally support what could be labelled a role balance model on separation rather than the specialization model. Looking at the father’s participation in childcare this was quite clear, where the man’s outtake of parental leave for the first child was shown to be related to reduced hazards of separation. In the same way equal distribution of the household labour market incomes between the partners was related to lower hazards of separation.

The travel imagination and the hybrid reality in the wake of colonialism

The “traveling imagination,” is of paramount importance to both western and postcolonial travelers. Since both groups create “travel imaginations” by extensive reading, the nature of the books that inform them must directly affect their travels. A westerner, for example, who reads only colonial-era accounts has the “travel imagination” of a different generation. If all perspectives were represented equally in libraries, the “travel imagination” of a given person would be entirely his/her own. But usually the “traveler’s imagination” is biased by prevailing opinion. Libraries are not democracies, and sometimes extensive reading only indoctrinates the reader with the biases of the canon. Perhaps the following generalization will be helpful. Westerners are able to create “traveling imaginations,” based on the books they trust. But postcolonials, who have reason to be suspicious of what they read, have complicated “traveling imaginations.” Sometimes postcolonial travelers base their “traveling imaginations” on what they read, and sometimes, in opposition to what they read. The books discussed in this thesis, In Patagonia, The Cruise of the Shark, The Happy Isles of Oceania, A Passage to England and The Enigma of Arrival, were first published in, 1977, 1939, 1992, 1971 and 1987, respectively, in what Ali Behdad calls the “age of colonial dissolution.” Perhaps it would be more accurate to say these books are set in the “age of colonial demolition.” For the most part, the empires in these texts are in ruins, or at least in the process of being dismantled. In fact, two of the authors, Nirad Chaudhuri and V.S. Naipaul are canonical post-colonial thinkers.

Oxford movement: its themes and their significance

In retrospective, the Oxford movement of nineteenth century England provides one with an interesting study of the struggles between the spiritual and secular worlds. However, repeated abstraction in an interpretation of its significance has tended to distort accurate understanding of its historical development. Often this also has resulted n a misinterpretation of the nature of its major themes and their significance to the world. For these reasons, this study has attempted to describe the origin, maturity, and dissolution of the series of events which strictly speaking may be considered to be the Oxford movement. In conclusion, liberty has been taken to comment on the nature of the Movement's themes and their significance in their own age and to man today.

Efeitos quimicos do recuo do cromo em alguns complexos hexacoordenados no estado solido

Os efeitos químicos do recuo do 51Cr formado pela reação (n,y) foram investigados nos compostos: [Cr(NH3) 5ONO] (NO3)2, [Cr(NH3) 5NO3] (NO3)2 e [Cr(NH3)5 NCS] (NO3)2, irradiados no estado sólido. Após dissolução dos cristais, os fragmentos resultantes da irradiação foram analisados por cromatografia com resina trocadora de íons e eletroforese em papel. A distribuição inicial das espécies é discutida em termos da formação de complexos polinucleares e da não ocorrência de conversão interna em compostos de cromo (III). Os efeitos de reversão térmica indicam uma considerável influência do oxigênio atmosférico e de defeitos cristalinos no comportamento químico das espécies.

Cinética e mecanismo da dissolução do ferro em solução aquosa de acetato de sódio

Estudou-se o comportamento eletroquímico do ferro em solução aquosa de acetato de sódio 1M em valores de pH próximos a neutralidade. Foram utilizadas diferentes técnicas de pertubação de potencial, quais sejam a voltametria cíclica e a impedância. Os ensaios foram realizados com eletrodos rotatórios de disco e eletrodos rotatórios de disco e anel. Observou-se o papel preponderante da concentração de acetato na dissolução do ferro que aliado ao pH da solução são os fatores determinantes da cinética deste processo. Evidenciou-se a ocorrência de reações consecutivas e paralelas neste estudo. O mecanismo catalítico presente na dissolução do ferro em meio de acetato cresce de importância a medida que os potenciais se tornam mais anódicos. E proposto que o mecanismo reacional apresenta quatro espécies adsorvidas,quais sejam: [FeOHAc]-ada, FeOHada [Fe(OH)2Ac]-ada e [Fe(OH)sAc]-2ada,sendo esta última a espécie precursora da passivação.

A complexidade do processo de sucessão em empresas familiares: um estudo de caso da libel linhares distribuidora de bebidas em Rosário – Maranhão.

A exigência pelo mercado de empresas competitivas vem se tornando cada vez maior, em vista das constantes mudanças que acontecem a cada instante no mundo globalizado. Gerenciar uma empresa é uma tarefa complexa, e essa tarefa torna-se ainda mais delicada quando trata-se de uma empresa familiar. Administrar uma empresa onde os funcionários participam do dia-a-dia da família, por pertencerem a ela, pode muitas das vezes confundir a constituição desses espaços, gerando no ambiente empresarial crises que possam ter origem a partir da incapacidade do gestor em separar os dois ambientes, ou mesmo da dificuldade em separar seu lado emotivo de cunho familiar das atividades profissionais da empresa. Aliado à essas dificuldades surge um dos maiores problemas do empreendimento familiar, a questão da sucessão, momento que é crucial para muitas empresas e reflete na sua permanência no mercado ou mesmo na sua dissolução e falência. Nasce daí a preocupação com o planejamento sucessório, ainda não tratado com a devida importância que lhe é devida por algumas empresas. Apresenta-se aqui um Estudo de Caso, de uma empresa que vem se desenvolvendo de maneira eficiente, porém poderia está bem melhor se não estivesse passando por uma crise na sucessão, resultado da ausência de um planejamento pelos seus fundadores. Busca-se aqui retratar o problema da sucessão, e assim demonstrar que esse processo deve ser pensado e analisado, se possível desde os primeiros anos de vida da empresa, visto que período suficiente há para essa elaboração.

Inimigos públicos: crimes corporativos e necrocorporações

As corporações estão presentes em todos os lugares e em quase todos os aspectos de nossas vidas, porém, elas podem ser perigosas para a sociedade, protagonizando ações com impactos negativos para consumidores, trabalhadores, meio ambiente e comunidades. Nesta tese, lançamos nosso olhar sobre o lado sombrio das corporações, explorando dois crimes corporativos cometidos no Brasil por duas corporações transnacionais da indústria química, uma indústria predominada por grandes corporações operando em forma de oligopólios, dentro de um setor altamente estratégico por produzir insumos para a produção da maioria dos bens de consumo. Nosso objetivo é compreender os crimes corporativos para além da perspectiva funcionalista predominante na literatura sobre o tema. Para tanto, realizamos uma pesquisa qualitativa, com base na perspectiva crítica, focalizando dois casos ocorridos há mais de quatro décadas, no Brasil. Para reunir material empírico, entrevistamos ex-trabalhadores e trabalhadores das corporações protagonistas dos crimes, ex-moradores da comunidade atingida pelos crimes e especialistas, como advogados e profissionais da saúde, que se envolveram nos casos. As entrevistas foram do tipo narrativa, tendo sido gravadas e, posteriormente, transcritas para análise. Além das entrevistas, reunimos diversos documentos sobre os casos, como a cobertura jornalística, relatórios técnicos, sentenças e acórdãos. Analisamos o material empírico buscando reconhecer que os crimes corporativos ocorreram como uma extensão das organizações e de seu modo de organizar, e não como infortúnio ou efeitos colaterais não intencionais. Como principais resultados, desenvolvemos os conceitos de necrocorporação e crimes corporativos contra a vida. Nossa análise estendeu-se sobre as articulações engendradas pelas corporações; a produção da morte; e o poder, o consentimento e a resistência. Em ambos os casos analisados, os crimes foram cometidos na busca pelos objetivos corporativos, provocando a morte e doenças, bem como outros danos irreversíveis ao meio ambiente e à comunidade. Nossos resultados apontam para a necessidade de uma mudança no modo de pensar quanto às relações entre governos, sociedade e corporações, iniciando-se pela dissolução desse modelo de organização de negócios.

Apuração de haveres na sociedade limitada: uma análise crítica da jurisprudência

Esta dissertação tem por objetivo investigar a apuração de haveres nas sociedades limitadas a partir da análise da jurisprudência, notadamente para compreender o alcance da liberdade de contratar das partes, estabelecido, entre outras normas, no artigo 1.031 do Código Civil. Para tanto, analisaram-se os julgados do STJ, disponíveis no sítio eletrônico da corte e, da mesma forma, os do TJSP, dada a relevância econômica do estado e a existência de câmaras especializadas em direito empresarial, entre o período de 2010 a 2014. Tentou-se construir uma tipologia das questões que compõem o julgamento das cláusulas de apuração de haveres, como, por exemplo, distinção entre forma de apuração e forma de pagamento; e, igualmente, dos fundamentos usados pelos tribunais para afastar ou aplicar as cláusulas. Na segunda seção, fez-se uma análise crítica dos argumentos jurisprudenciais, sob a forma de defesa daqueles que, a nosso sentir, devem validar as cláusulas de apuração de haveres, quais sejam: boa-fé objetiva, função social e os constantes na literatura americana do capital lock in. Além disso, pontua-se sobre o emprego, a nosso sentir, inadequado do “enriquecimento sem causa”, como também da conveniência de se fazer uma aplicação ponderada dos princípios, especialmente quando contrariam uma regra jurídica positivada. Por fim, antes de concluir, comentou-se sobre a forma de apuração de haveres construída pela jurisprudência, a qual denomina-se, neste trabalho, dissolução total simulada.