Reductive decarboxylation of bicyclic prolinic systems: a new approach to the enantioselective synthesis of the Geissman-Waiss lactone. X-ray structure determination of a key lactone intermediate

Two concise and enantioselective syntheses of the necine base precursors (1R,5R)-N-Cbz and N-Boc-2-oxa-6-azabicyclo[3.3.0]octan-3-ones (Geissman-Waiss lactones) were carried out from two enantiomerically pure endocyclic five-membered enecarbamates with overall yields of 23% and 26%, respectively. The synthetic strategy made use of a highly effective and stereoselective [2+2]cycloaddition of enantiomerically pure endocyclic enecarbamates with dichloroketene, as well as an efficient decarboxylation step of a bicyclic alpha-amino acid employing Boger's acyl selenide protocol employing tributyltin hydride. Interesting aspects concerning the regiochemical outcome of Baeyer-Villiger oxidations of bicyclic cyclobutanones are also reported, in which the usual stereoelectronic bias of Baeyer-Villiger oxidation seems to be counterbalanced by steric effects on the putative Criegee intermediate.Duas sínteses do conhecido precursor de bases necínicas, (1R,5R)-N-Cbz e N-Boc 2-oxa-6-azabiciclo[3.3.0]octan-3-onas (lactonas de Geissman-Waiss) foram realizadas com rendimentos globais de 23% e 26%, em seis e cinco etapas respectivamente, a partir de enecarbamatos endocíclicos de cinco membros enantiomericamente puros. A estratégia sintética adotada está fundamentada em uma reação de cicloadição [2+2] eficiente e altamente estereosseletiva de enecarbamatos de cinco membros com diclorocetenos, assim como em uma eficaz descarboxilação de alfa-amino ácidos bicíclicos pelo método de Boger, que utiliza a redução de selenetos de acila por hidretos de estanho. Aspectos relativos a regiosseletividade da reação de oxidação de azabiciclo ciclobutanonas pelo método de Baeyer-Villiger são também descritos, com destaque para um potencial controle regioquímico advindo de aspectos estéreos em contraposição a aspectos estereoeletrônicos.2738Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Operacionalização do conceito de resiliência de forrageiras sob pastoreio rotativo aos distúrbios de mudanças climáticas

A resiliência de forrageiras sob pastoreio rotativo aos distúrbios de mudanças climáticas, em particular aos efeitos do déficit hídrico em veranicos, é um atributo básico para alcançar a sustentabilidade do sistema de produção de leite. Este trabalho apresenta um método baseado na dinâmica de sistemas para estimar os índices de resiliência: dureza, robustez, rapidez de recuperação e elasticidade. Um metamodelo para o manejo do ecossistema planta-animal foi adaptado para simular os efeitos dos distúrbios causados por veranicos no estoque de matéria seca dos piquetes. Os resultados dos experimentos in silico mostram diferenças entre as resiliências de dois cultivares de forrageiras para uma mesma magnitude de distúrbio e diferenças devido a época de ocorrência do déficit hídrico ser na fase de crescimento da forrageira ou na fase de uso dos piquetes pelos animais. O índice de rapidez de recuperação mostrou aderência conceitual para as condições de pastoreio rotativo, devido à premência de tempo na definição da entrada e saída dos animais nos piquetes. Concluiu-se que a operacionalização e avaliação da resiliência geram informações sobre a dinâmica do estoque de matéria seca ofertada para os animais e que estas informações são úteis para o planejamento do pastoreio rotativo

Influence of the contact–impact force model on the dynamic response of multi-body systems

This work deals with contact–impact force models for both spherical and cylindrical contact surfaces. The incorporation of the friction phenomenon, based on the Coulomb friction law, is also discussed together with an effective computational strategy, which includes the automatic step size selection procedure. Impacts within a revolute clearance joint in a basic slider–crank mechanism are used as an example to compare the different contact force models. The collision is a prominent phenomenon in manymulti-body systems such as mechanisms with intermittent motion, kinematic discontinuities, and clearance joints. As a result of an impact, the values of the system state variables change very fast, eventually looking like discontinuities in the system velocities and accelerations. The impact is characterized by large forces that are applied and removed in a short time period. The knowledge of the peak forces developed in the impact process is very important for the dynamic analysis of multibody systems and it has consequences in the design process. The model for the contact–impact force must consider the material and geometric properties of the colliding surfaces, consider information on the impact velocity, contribute to an efficient integration, and account for some level of energy dissipation. These characteristics are ensured with a continuous contact force model, in which the deformation and contact forces are considered as continuous functions.FEDER - Project POCTI/2001/EME/38281.Fundação para a Ciência e a Tecnologia (FCT)

Modelling Deformations in Car Crash animation

In this paper, we present a prototype of a deformation engine to efficiently model and render the damaged structure of vehicles in crash scenarios. We introduce a novel system architecture to accelerate the computation, which is traditionally an extremely expensive task. We alter a rigid body simulator to predict trajectories of cars during a collision and formulate a correction procedure to estimate the deformations of the collapsed car structures within the contact area. Non-linear deformations are solved based on the principle of energy conservation. Large plastic deformations resulting from collisions are modelled as a weighted combination of deformation examples of beams which can be produced using classical mechanics

Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications.

BACKGROUND: Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea. METHOD: The advent of 3D tomography is proven as a significant advancement to further characterize corneal shape beyond front surface topography, which is still relevant. While screening tests for ectasia had been limited to corneal shape (geometry) assessment, clinical biomechanical assessment has been possible since the introduction of the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, USA) in 2005 and the Corvis ST (Oculus Optikgerate GmbH, Wetzlar, Germany) in 2010. Direct clinical biomechanical evaluation is recognized as paramount, especially in detection of mild ectatic cases and characterization of the susceptibility for ectasia progression for any cornea. CONCLUSIONS: The purpose of this review is to describe the current state of clinical evaluation of corneal biomechanics, focusing on the most recent advances of commercially available instruments and also on future developments, such as Brillouin microscopy.(undefined)info:eu-repo/semantics/publishedVersio

Psychosocial Determinants of Presenteeism at the Workplace in the Pre - COVID-19 Era in A Southern European Country - The Mediating Role of Mental Health and Wellbeing

Introduction: The impact of organizational stressors on presenteeism at individual and organizational levels, mediated by workers Psychological Wellbeing (PWB) acting as a buffering effect, in the pre-COVID-19 era, is reported. We hypothesize that individual wellbeing is the pathway through which organizational stress affects presenteeism. Methods: A study was conducted between November 2012 and June 2013 and data correspond to a nonrandomised sample of 405 employees at a private financial institution in Lisbon area. The Portuguese version of ASSET (A Shortened Stress Evaluation Tool), a self- report instrument validated for the Portuguese population, measuring individual’s perceptions regarding stress, and Psychological Wellbeing (PWB) at work, was applied. ASSET’s Work Relationships (WR), Aspects of the Job (YJ), Overload (OL), Control (CL), Job Security (JS), Resources and Communication (RC) and Work-Life Balance (WLB) dimensions were used, and PWB of ASSET health scale was used as mediator. Presenteeism was obtained with an item measure from the World Health Organization’s Health and Work Performance Questionnaire. Mediation analysis was tested using Structural Equation Modelling with AMOS software.info:eu-repo/semantics/publishedVersio

Chromosomal disorders and male infertility

Male factor infertility is considered a complex disorder with a largely unknown etiology that affects about 7% of men. In general, genetic abnormalities account for 15%-30% of condition and Y chromosome microdeletions are also frequent. The study, based on our casuistic, aimed at contributing to a better understanding of the genetic causes of infertility. A group of 410 idiopathic infertile men with non-obstructive azoospermia, oligozoospermia, or unknown semen quality (based on clinical evaluation and/or sperm counts) was retrospectively selected. Conventional karyotype was performed in all samples; Y microdeletion screen was performed in 247 samples. Forty two abnormal karyotypes (10.2%) were found, indicating an elevated frequency of chromosome abnormalities among the selected infertile men, as compared to that of newborn populations (≈0.4%). This frequency is higher than that reported in most similar studies that pointed to frequencies ranging from 2.2%-14.3%. Klinefelter´s syndrome was the most common chromosome disorder (4.9%). There were 18 cases with 47,XXY karyotype and 2 cases of mosaicism involving lines 47,XXY and 46,XY. Reciprocal translocations were identified in 10 cases (2.4%), particularly in men with unknown semen quality. Overall, reciprocal translocations have been found in approximately 1% of the infertile men and more commonly in azoospermics than in oligozoospermics. However, this type of association was not found in the present study. On the other hand, Y microdeletions were identified in 16/247 cases (6.5%), more frequently in azoospermics (13.3%, corresponding to 8/60 azoospermics). Among these 8 cases, 7 presented deletions at the AZFc region. The marked presence of chromosomal abnormalities and Y microdeletions enphasizes the relevance of studying both factors in infertile men to improve genetic counseling, to allow the development of appropriate therapies, and to expand the knowledge about the ethiology of male infertility

Possibilidade de reuso/reciclo direto ou indireto de efluentes gerados em entrepostos de pescado.

O consumo de água na indústria de alimentos é considerado elevado e seu reaproveitamento é complexo, pois não existem parâmetros estabelecidos. Fazer a opção pelo reuso, ainda que não seja de forma direta é uma das alternativas que apresenta uma possibilidade de minimização no consumo de água e na geração de efluentes. Portanto, neste estudo objetivou-se conhecer as correntes de efluentes gerados, avaliar o potencial de reuso e reciclo sem ou com recondicionamento, de forma a habilitar um tratamento ótimo para cada tipo de resíduo. Para tanto, análises de qualificação do efluente, adotando-se parâmetros físicos, químicos e biológicos foram adotados, bem como a verificação e aplicação das possibilidades de reciclo e reuso diretos e indiretos de efluentes. Como resultado foi encontrado um efluente com alta carga orgânica, mas passível de reuso indireto. A possibilidade de reciclo e reuso de efluentes diretos para o uso no frigorífico de pescado, descartada. Como resultado foi verificado que o constituinte básico de efluentes da indústria de pescado é material orgânico, e ao aderir o método de segregação, a possibilidade de reuso indireto é considerada, já o reuso direto foi descartado

Structural and functional characteristics of rat hearts with and without myocardial infarct. Initial experience with doppler echocardiography

OBJECTIVE: To assess by Doppler echocardiography the structural and functional alterations of rat heart with surgical induced extensive myocardial infarction. METHODS: Five weeks after surgical ligature of the left coronary artery, 38 Wistar-EPM rats of both sexes, 10 of them with extensive infarction, undergone anatomical and functional evaluation by Doppler echocardiography and then euthanized for anatomopathological analysis. RESULTS: Echocardiography was 100% sensible and specific to anatomopathological confirmed extensive miocardial infarction. Extensive infarction lead to dilatation of left ventricle (diastolic diameter: 0.89cm vs.0.64cm; systolic: 0.72cm vs. 0.33cm) and left atrium (0.55cm vs. 0.33cm); thinning of left ventricular anterior wall (systolic: 0.14cm vs. 0.23cm, diastolic: 0.11cm vs. 0.14cm); increased mitral E/ A wave relation (6.45 vs. 1.95). Signals of increased end diastolic ventricle pressure, B point in mitral valve tracing in 62.5% and signs of pulmonary hypertension straightening of pulmonary valve (90%) and notching of pulmonary systolic flow (60%) were observed in animals with extensive infarction. CONCLUSION: Doppler echocardiography has a high sensitivity and specificity for detection of chronic extensive infarction. Extensive infarction caused dilatation of left cardiac chambers and showed in Doppler signals of increased end diastolic left ventricular pressure and pulmonary artery pressure.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL