Obtenção e caracterização de filmes poliméricos a partir de poli(vinilpiridina)/cloreto de ferro(III)

TCC (graduação) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Curso de Química.O presente trabalho descreve a preparação e o estudo de propriedades físicoquímicas de filmes poliméricos formados pela classe de polímeros poli(vinilpiridina) e cloreto de ferro(III). Para tanto foram preparados compostos com os polímeros poli(2-vinilpiridina) (P2VP) e poli(4-vinilpiridina) (P4VP) e sal FeCl3.6H2O, em diferentes proporções de polímero e sal: 1:1, 2:1 e 4:1 (mol de unidade monomérica/mol de sal). A formação do composto ocorre através da interação entre o par eletrônico disponível no nitrogênio piridínico da poli(vinilpiridina) e os orbitais d da camada de valência do íon metálico Fe(III), interação esta caracterizada através de estudos de espectros vibracionais na região do infravermelho, que mostram um deslocamento significativo da banda de estiramento C-N para o P2VP e P4VP com a formação dos complexos metálicos. Os filmes poliméricos também foram estudados e caracterizados por técnicas de análise termogravimétrica. As curvas de termogravimetria mostram que há uma diminuição na temperatura onde se inicia a degradação térmica dos complexos quando comparados com os polímeros puros. As curvas de calorimetria exploratória diferencial mostram que há um aumento na temperatura de transição vítrea dos complexos, o que sugere uma maior rigidez da cadeia polimérica com a complexação. Medidas de absorção de água indicam que os complexos absorvem quantidades significativas de água e dependem da quantidade de íons Fe(III) na amostra. Medidas de condutividade elétrica dos filmes mostram que há um aumento significativo em relação à condutividade dos polímeros, embora ainda sejam características de material não condutor

Hole cleaning and wet-granular rheology of rock cutting beds: Impact of drilling fluid composition

Cuttings-beds formation is an issue that must be considered during all wellbore drilling operations. This problem increases at highly deviated or horizontal wells, where cuttings removal efficiency becomes one of the most critical elements for the whole drilling operations. Removal of drilled cuttings is done through circulating the drilling fluid and then separate out the cuttings at the surface. When the wellbore is inclined or horizontal, the cuttings tend to settle and form cuttings-beds. The consolidation strength of these cuttings-beds is normally unknown. Traditional studies on cuttings-bed removal usually focus on the final result: effective cuttings-bed removal. The scope of this study is to analyze the wetted cuttings-bed particle bonding strength and the stress required to break the formed bed, by means of granular rheology methodology. In other words, the strength required to erode a formed cuttings-bed is addressed independently. Wet-granular rheology techniques, complemented by Mohr-Coulomb envelop analysis has shown to be an effective approach to describe the cohesive strength of consolidated cuttings-bed and flowability of the particles within the beds. We have analyzed simulated cuttings-beds’ shear strength and flowability using quartz particles saturated with water, water-based drilling fluid and oil-based drilling fluid. The results showed that the interstitial fluid and its composition significantly impact the shear strength of the bed, conveying higher cohesion for water-based drilling fluid in comparison to oil-based drilling fluids.publishedVersio

Fundamentals and physical principles for drilled cuttings transport – Cuttings bed sedimentation and erosion

The increasing necessity of challenging wellbore structures and drilling optimization for improved hole cuttings cleaning has been growing along time. As a result, operator companies have been researching and applying different hole cleaning techniques. Some of these are applied as traditional rules of thumb but are not always suitable for the new and up-coming challenges. This may result in inefficient hole cleaning, non-productive times, pipe stocking and low rate of penetration (ROP), among other problems. Here are presented some results and improvements for hole cleaning optimization obtained by the different research groups. The different authors mainly focus on specific cuttings transport parameters and sometimes combination of some of them. For this reason, there has not been a study that takes into account all of the different factors at the same time to accurately predict the cuttings bed height, formation and erosion, critical fluid velocity and properties and other key parameters. Consequently, there is a lack of understanding about the relation between different factors, such as the cohesiveness of the drilled cuttings with the different interstitial drilling fluids within the cuttings-bed. This relation can be analyzed establishing a wet-granular approach to obtain more efficient cuttings transport mechanism in challenging conditions.publishedVersio

Wet Drilled Cuttings Bed Rheology

The cuttings transport efficiency of various drilling fluids has been studied in several approaches. This is an important aspect, since hole cleaning is often a bottleneck in well construction. The studies so far have targeted the drilling fluid cuttings’ transport capability through experiments, simulations or field data. Observed differences in the efficiency due to changes in the drilling fluid properties and compositions have been reported but not always fully understood. In this study, the cuttings bed, wetted with a single drilling fluid, was evaluated. The experiments were performed with parallel plates in an Anton Paar Physica 301 rheometer. The results showed systematic differences in the internal friction behaviors between tests of beds with oil-based and beds with water-based fluids. The observations indicated that cutting beds wetted with a polymeric water-based fluid released clusters of particles when external forces overcame the bonding forces and the beds started to break up. Similarly, it was observed that an oil-based fluid wetted bed allowed particles to break free as single particles. These findings may explain the observed differences in previous cutting transport studies.publishedVersio

Estudo computacional de complexos mononucleares de cobre (II) e zinco (II) com ligantes triazólicos

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2013.Neste trabalho foram estudados complexos mononucleares de cobre(II) ou zinco(II) coordenados a ligantes triazólicos contendo anéis do tipo 1,2,3- e 1,2,4-triazol. O presente trabalho é baseado em métodos teóricos de estrutura eletrônica enraizados no formalismo da Teoria do Funcional da Densidade (DFT). A ideia central deste trabalho é propor novas estruturas para complexos de cobre(II) e zinco(II) contendo ligantes triazólicos, obter suas estruturas otimizadas (o que corresponde a mínimos na superfície de energia potencial) e investigar sua estrutura eletrônica. No presente estudo, destaca-se a natureza da ligação química metal-ligante. Esta é investigada sob o prisma da decomposição de carga (CDA) e energia (EDA). Detalhes adicionais referentes à ligação metal-ligante, tal como doação e retrodoação, também são investigados empregando-se análise de orbital natural de ligação (NBO) e a teoria quântica de átomos em moléculas (QTAIM). Deste modo, é possível prever, de forma teórica, a elaboração de novos complexos e investigar sua estrutura eletrônica e natureza de suas ligações químicas. Abstract : In this study, mononuclear copper(II) or zinc(II) complexes coordinated to the triazole ligands containing 1,2,3- and 1,2,4-triazole rings were studied. The present study is based on theoretical methods of electronic structure rooted in the formalism of Density Functional Theory (DFT). The central idea of this work is to propose new structures of copper(II) and zinc(II) complexes containing triazole ligands, providing their optimal structures (corresponding to minima on the potential energy surface) and investigating their electronic structure. In the present study, the nature of metal-ligand chemical bonding is highlighted. It is investigated in the light of charge (CDA) and energy (EDA) decomposition analyses. Additional details regarding the metal-ligand bonding such donation and back-donation processes are also investigated by employing natural bond orbital (NBO) analysis and the quantum theory of atoms in molecules (QTAIM). In this way, it is possible to predict, in a theoretical fashion, to propose new complexes and to investigate their electronic structure and the nature of their chemical bonds

Optimum design and sequential treatment allocation in an experiment in deep brain stimulation with sets of treatment combinations

In an experiment including patients who underwent surgery for deep brain stimulation electrode placement, each patient responds to a set of 9 treatment combinations. There are 16 such sets, and the design problem is to choose which sets should be administered and in what proportions. Extensions to the methods of nonsequential optimum experimental design lead to identification of an unequally weighted optimum design involving 4 sets of treatment combinations. In the actual experiment, patients arrive sequentially and present with sets of prognostic factors. The idea of loss due to Burman is extended and used to assess designs with varying randomization structures. It is found that a simple sequential design using only 2 sets of treatments has surprisingly good properties for trials with the proposed number of patients

Randomizing a clinical trial in neuro-degenerative disease

The paper studies randomization rules for a sequential two-treatment, two-site clinical trial in Parkinson’s disease. An important feature is that we have values of responses and five potential prognostic factors from a sample of 144 patients similar to those to be enrolled in the trial. Analysis of this sample provides a model for trial analysis. The comparison of allocation rules is made by simulation yielding measures of loss due to imbalance and of potential bias. A major novelty of the paper is the use of this sample, via a two-stage algorithm, to provide an empirical distribution of covariates for the simulation; sampling of a correlated multivariate normal distribution is followed by transformation to variables following the empirical marginal distributions. Six allocation rules are evaluated. The paper concludes with some comments on general aspects of the evaluation of such rules and provides a recommendation for two allocation rules, one for each site, depending on the target number of patients to be enrolled

Wet-granular rheology to measure cuttings-bed strength

Drilled cuttings-bed formation is a natural process during wellbore drilling operations, although it is not desired. To optimally remove the drilled cuttings out of the wellbore it is important to break the formed beds. Wet-granulated material such as the drilled cuttings behave differently depending on the applied stress and particle concentration, it can behave as solid when is at rest or under low energy input, or it can flow like a fluid when a certain energy is reached. Here it is studied how a wetting fluid can modify the motion and properties of the cuttings-bed by using powder rheology.publishedVersio

Safety perception in patients with advanced idiopathic Parkinson’s disease – a qualitative study

BackgroundA fundamental cornerstone of quality of healthcare is patient safety, which many people with life-limiting illnesses feel is being compromised. Perceptions of impaired safety are associated with the occurrence of psychological distress and healthcare utilization. However, little is known about how people with idiopathic Parkinson’s disease (iPD) perceive their own safety toward the end of life. The aim of our study was therefore to investigate factors that influence the perception of safety of patients with advanced iPD.MethodsWe conducted semi-structured interviews with a purposeful sample of 21 patients with advanced iPD. Participants were recruited at the neurology department of a tertiary care hospital in Germany between August 2021 and June 2022. Data were analyzed using reflexive thematic analysis.ResultsiPD-patients reported relevant impairment of their safety. While most participants expressed safety concerns based on the manifestation of disease, our analysis identified enablers and barriers to establishing safety in patients with advanced iPD, in 10 additional domains: relationship to the disease, informedness, self-perception, utilization of support and care structures, healthcare professionals and structures, treatment, social interaction, social security, spirituality, and environment.ConclusionThis study provides new insights into safety perceptions of patients with advanced iPD, which extend well beyond the physical realm. The findings suggest that clinicians and policy makers should consider a holistic and multidisciplinary approach to assessing and improving patients’ safety taking into account the enablers and barriers identified in this study

Presence of women on the editorial boards of the language and linguistics journals in Spain

Many international studies have pointed out the under-representation of women on Editorial Boards of both Science and Social Science journals. Their presence as Editorial Board members is relevant as they influence and reflect the policies of the journal itself. This study analyses the participation of women on the Editorial Boards of the Spanish Language and Linguistics journals in SCOPUS. To this end, 54 journals indexed in SCOPUS were analysed, thus discriminating the gender of all members and the role that each member plays on the Editorial Board. The results show no significant differences in the participation of men and women in these Editorial Boards. It was not found any evidence of gender bias in these journals