Applications of generalized integral transform technique in the rapid solidification of metallic metals in the planar flow casting process / Aplicações da técnica de transformação integral generalizada na solidificação rápida de metais metálicos no processo de fundição em fluxo planar

The Planar Flow Casting (PFC) is a single-stage fast solidification technique to produce thin metallic ribbons. The objective of this research is to develop a mathematical model to analyze the phenomenon of heat transfer and phase change during the formation of the puddle, to determine the interface position and velocity and the temperature profile. The applied methodology consists of the use of the energy balance, where the equations of the energy (liquid and solid phases), and the equation of the interface are transformed through the Generalized Integral Transform Technique (GITT) being solved by the NDSolve routine of the Matemathica. This tool was capable to solve problem, can study the fast cooling of metals and obtain ribbons of thickness controlled by the speed of the wheel and for the heat transfer coefficient. Considering that the height of the pool is very small and the process time is very short, many eigenvalues were used to obtain the solution convergence. The results of the temperature distribution along the length of the puddle, the evolution of the solidification front and the interface velocity were compared with existing results in the literature, obtaining good harmony.

Analysis of the forced convection in the bidimensional laminar flow in circular ducts in primitive variable by GITT.

In this study the forced convection in the laminar flow in simultaneous developing is studied by applying the Generalized Integral Transform Technique to provide a hybrid analytical solution for the fields of velocity, pressure and temperature in circular ducts. The Continuity, Navier-Stokes, Poisson and Energy equations are formulated using primitive variables,knowing that the Poisson Equation was obtained from some mathematical manipulation made on the Navier-Stokes equations. The integral transformation is done in the Momentum equation in x, Poisson and energy equations, and the resulting equations are solved using the IMSL, DBVPFD subroutines and recovering the original potential for each profile studied. In this way it is possible to find a solution to the system by means of an expansion in terms of convenient eigenfunctions, to circular ducts, the eigenfunctions will be Bessel functions. In the following, some results from a practical point of view will be calculated and exhibited graphically such as: The Nusselt number, the f Re value, the study of the convergence profile of the velocity field, the mean velocity, the temperature, the mean temperature, pressure and the mean pressure in the middle of the duct will be analyzed. The results will be compared with the ones found in the literature to validate and adjust the model.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESNo presente trabalho a convecção forçada interna no escoamento laminar em desenvolvimento simultâneo é estudada aplicando a Técnica da Transformada Integral Generalizada para produzir um solução híbrida para os campos de velocidade, pressão e temperatura em dutos circulres. As equações da Continuidade, de Navier-Stokes, de Possion e da Energia são formuladas utilizando variáveis primitivas, sabendo-se que a equação de Poisson foi obtida a partir de algumas manipulações matemáticas feitas na equação de Navier-Stokes. A transformação integral é aplicada nas equações da quantidade de movimento na direção x, de Poisson e na equação da energia, e as equações resultantes são resolvidas com a subrotina numérica do IMSL, DBVPFD recuperando o potencial original para cada perfil em estudo. Assim é possível encontrar uma solução para o sistema de equações em termos de um expansão de autofunções, que para dutos circulares, as autofunções serão funções de Bessel. Em seguida resultados de interesse prático são calculados e exibidos graficamente como: número de Nusselt e f Re e estudos da convergência dos perfis de velocidade,velocidade média, temperatura, temperatura média, pressãoo e pressão média no centro do duto são analisados. Os resultados são comparados com os dados disponíveis na literatura para validação e ajustes do modelo

Moldagem de Trabalho em Prótese Fixa

Introduction: molding is a fundamental step in a prosthetic rehabilitation treatment. It is the transfer of the clinical situation to the dental laboratory. There are numerous molding materials. Among them, we highlight the elastomers, which are non-aqueous elastic materials. They are: silicone polymerized by addition, silicone polymerized by condensation, polyether and polysulfide. The objective of this work is to present what is in the most updated literature pertinent to the subject, which includes a new reality for impressions of work in fixed prosthesis. Methodology: the bibliographic survey was carried out using the electronic databases SciELO, Bireme and PubMed, using the keywords dental prosthesis; dental impression materials; dental impression technique and fixed prosthesis. Articles that included information relevant to the proposed theme were included. Result: Regarding the dimensional stability of these materials, the most stable is the addition silicone, followed by polyether, polysulfide and, finally, condensation silicone. For the use of these materials, the dentist must have some impression techniques: impression technique with individual cap, repackaging or double printing technique, repacking technique with the use of previous relief and simultaneous or double mixing technique. Conclusion: there is no consensus in the literature that elucidates which material and, mainly, the technique that should be recommended for performing the work impression. To minimize the issue, the professional must define which technique will be followed according to his ability, respecting his limitations and security regarding the procedure.Introducción: el moldeo es un paso fundamental en un tratamiento de rehabilitación protésica. Es la transferencia de la situación clínica al laboratorio dental. Existen numerosos materiales de moldeo. Entre ellos, destacamos los elastómeros, que son materiales elásticos no acuosos. Son silicona polimerizada por adición, silicona polimerizada por condensación, poliéter y polisulfuro. El objetivo de este trabajo es presentar lo que se encuentra en la literatura más actualizada pertinente al tema, que incluye una nueva realidad para las impresiones del trabajo en prótesis fija.Metodología: la encuesta bibliográfica se realizó utilizando las bases de datos electrónicas SciELO, Bireme y PubMed, utilizando las palabras clave prótesis dental; materiales de impresión dental; Técnica de impresión dental y prótesis fija. Se incluyeron artículos que incluían información relevante para el tema propuesto.Resultado: en relación con la estabilidad dimensional de estos materiales, el más estable es la silicona de adición, seguida de poliéter, polisulfuro y, finalmente, silicona de condensación. Para el uso de estos materiales, el dentista debe tener algunas técnicas de impresión: técnica de impresión con tapa individual, reempaquetado o técnica de doble impresión, técnica de reempaque con el uso de alivio previo y técnica de mezcla simultánea o doble.Conclusión: no existe consenso en la literatura que aclare qué material y, principalmente, la técnica que debe recomendarse para realizar la impresión de trabajo. Para minimizar el problema, el profesional debe definir qué técnica se seguirá según su capacidad, respetando sus limitaciones y seguridad con respecto al procedimiento.Introdução: a moldagem é uma etapa fundamental em um tratamento reabilitador protético. Ela é a transferencia da situação clínica para o laboratório de prótese dentária. Existem inúmeros materiais de moldagem. Dentre eles, destacam-se os elastômeros, que são materiais elásticos não aquosos. São eles: silicone polimerizado por adição, silicone polimerizado por condensação, poliéter e polissulfeto. O objetivo deste trabalho é apresentar o que há na literatura mais atualizada pertinente ao assunto, o que inclui uma nova realidade para impressões de trabalho em prótese fixa. Metodologia: o levantamento bibliográfico foi realizado por meio das bases de dados eletrônicas SciELO, Bireme e PubMed, mediante os descritores prótese dentária; materiais para moldagem odontológica; técnica de moldagem odontológica e prótese fixa. Foram inclusos artigos que apresentassem informações pertinentes ao tema proposto. Resultado: em relação à estabilidade dimensional desses materiais, o mais estável é o silicone de adição, seguido do poliéter, do polissulfeto e, por fim, do silicone de condensação. Para a utilização desses materiais, o dentista deve deter algumas técnicas de moldagem: técnica de moldagem com casquete individual, técnica de reembasamento ou dupla impressão, técnica de reembasamento com a utilização de alívio prévio e técnica simultânea ou dupla mistura. Conclusão: não há um consenso na literatura que elucida qual o material e, principalmente, a técnica que deve ser preconizada para a realização da moldagem de trabalho. Para minimizar a questão, o profissional deve definir qual técnica será seguida de acordo com a sua habilidade, respeitando as suas limitações e seguranças com relação ao procedimento

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research