Zinkkomplexe mit neutralen N-Donorliganden als Katalysatoren der Ringöffnungspolymerisation von Lactid

Polylactide is a biobased and biodegradable plastic which, due to its favourable material properties, posseses the potential to compete against petrochemical-based plastics in many fields of application. Catalysts that are suitable for the production of polylactide under industrial conditions are rare. In the present work zinc complexes with neutral N-donor ligands that combine the necessary robustness towards air and moisture with high polymerisa-tion catalysis are used. By means of the class of guanidine quinoline hybrid ligands the ligand’s basicity was examined, because this feature plays a significant role in the polymerization catalysis. Using experimental and density functional theoretical studies the polymerization mechanism with this catalyst class could be elucidated. The polymerization proceeds via a coordination-insertion mechanism during which the neutral but highly nucleophilic guanidine function induces the ring-opening of the lactide. The influence of the catalyst structure on the stereoselectivity in lactide polymerization was studied by density functional theoretical, mechanistical calculations using the example of aluminium-based complexes and by experimental polymerization studies using the example of tin-based catalysts, with the result, that a high steric demand at suitable positions of the ligand could lead to a high influence on the stereoselectivity. With the objective of increasing the stereoselectivity of the guanidine quinoline catalysts, the ligands were modified by introduction of sterically demanding substituents. The resulting zinc complexes show activity in the lactide polymerization and with bis(chelate)-complexes an enrichment of heterotactic enchainments could be observed in the resulting polymer. Also zinc complexes with further guanidine ligands and other classes of neutral N-donor ligands (oxalic amidines, diamines and triazapentadienes) were successfully applied as catalysts of the lactide polymerization. Thus, the concept of obtaining robust and catalytically active zinc complexes could be confirmed for several classes of neutral N-donor ligands.Polylactid ist ein biobasierter und biologisch abbaubarer Kunststoff, der aufgrund seiner hervorragenden Materialeigenschaften das Potenzial besitzt, auf fossilen Ressourcen basierende Kunststoffe in vielen Anwendungsbereichen zu ersetzen. Katalysatoren, die auch für die Herstellung von Polylactid unter industriellen Bedingungen geeignet sind, sind rar. In der vorliegenden Arbeit werden Zinkkomplexe mit neutralen N-Donorliganden in der Lactidpolymerisation eingesetzt, die die notwendige Robustheit gegenüber Luft und Feuchtig-keit aufweisen und gleichzeitig aktive Katalysatoren darstellen. Anhand der Klasse der Guanidin-Chinolin-Hybridliganden wurde die Basizität der Liganden untersucht, da diese bei der Polymerisationskatalyse eine entscheidende Rolle spielt. Durch experimentelle und dichtefunktionaltheoretische Studien konnte der Polymerisationsmechanismus mit dieser Katalysatorklasse aufgeklärt werden. Die Polymerisation verläuft über einen Koordinations-Insertions-Mechanismus, bei dem die neutrale aber stark nukleophile Guanidinfunktion die Ringöffnung des Lactids induziert. Der Einfluss der Katalysatorstruktur auf die Stereoselektivität in der Lactidpolymerisation wurde durch dichtefunktionaltheoretische, mechanistische Berechnungen am Beispiel von aluminiumbasierten Komplexen und durch experimentelle Polymerisationsstudien anhand von zinnbasierten Katalysatoren untersucht, mit dem Ergebnis, dass ein hoher sterischer Anspruch an geeigneten Positionen der Liganden einen hohen Einfluss auf die Stereoselektivität aufweisen kann. Mit dem Ziel, die Stereoselektivität der Guanidin-Chinolin-Katalysatoren zu erhöhen, wurden die Liganden durch die Einführung sterisch anspruchsvoller Substituenten modifiziert. Die resultierenden Zinkkomplexe zeigen Aktivität in der Lactidpolymerisation und bei Bis(chelat)-Komplexen konnte eine Anreicherung von heterotaktischen Sequenzen in den Polymeren beobachtet werden. Auch Zinkkomplexe mit weiteren Guanidinliganden und anderen Klassen neutraler N-Donorliganden (Oxalamidine, Diamine und Triazapentadiene) wurden erfolgreich als Ka-talysatoren der Lactidpolymerisation eingesetzt. Dadurch konnte das Konzept, mit neutralen Liganden robuste und katalytisch aktive Zinkkomplexe zu erhalten, für mehrere N-Donor-Ligandenklassen bestätigt werden

New Guanidine-Pyridine Copper Complexes and Their Application in ATRP

The guanidine hybrid ligands, (tetramethylguanidine)methylenepyridine (TMGpy) and (dimethylethyleneguanidine)methylenepyridine (DMEGpy), were proven to be able to stabilize copper complexes active in the solvent-free polymerization of styrene at 110 degrees C using 1-phenylethylbromide as the initiator. The polymerization proceeded after first-order kinetics, and polystyrenes with polydispersities around 1.2 could be obtained. Using the ligand, DMEGpy, three new copper guanidine-pyridine complexes could be synthesized and structurally characterized. Their structural characteristics are discussed

New Guanidine-Pyridine Copper Complexes and Their Application in ATRP

The guanidine hybrid ligands, (tetramethylguanidine)methylenepyridine (TMGpy) and (dimethylethyleneguanidine)methylenepyridine (DMEGpy), were proven to be able to stabilize copper complexes active in the solvent-free polymerization of styrene at 110 degrees C using 1-phenylethylbromide as the initiator. The polymerization proceeded after first-order kinetics, and polystyrenes with polydispersities around 1.2 could be obtained. Using the ligand, DMEGpy, three new copper guanidine-pyridine complexes could be synthesized and structurally characterized. Their structural characteristics are discussed

PERFIL PROTEICO DO LÍQUIDO FOLICULAR COLETADO DE OVÁRIOS EM DIFERENTES FASES DO CICLO ESTRAL DE BOVINOS.

O microambiente do gameta feminino é o líquido folicular e, portanto as proteínas presentes no líquido folicular devem interferir na qualidade do oócito. Com o objetivo de verificar o perfil proteico do líquido folicular de folículos de diferentes fases do ciclo estral de bovinos este experimento foi delineado. Para tanto, os líquidos foliculares provenientes de ovários de vacas de abatedouro foram alocados em 5 diferentes fases do ciclo estral, levando em conta a presença ou ausência do corpo lúteo (CL) e sua caracterização morfológica. “Pools” de líquido folicular foram coletados de folículos de 2 a 7 mm de ovários em 5 diferentes fases do ciclo estral (1=CL inicial, hemorrágico; 2=CL em desenvolvimento; 3=CL maduro; 4=CL em regressão e 5=ausência de CL). O perfil proteico foi avaliado por eletroforese em gel de poliacrilamida e determinado em porcentagens nas amostras de cada fase. Os polipeptídeos de 35, 32, 30 e 18 KDa variam consideravelmente nas amostras de diferentes fases do ciclo estral. O polipeptídeo de mesmo peso molecular que o IGFBP-2 está mais presente nas amostras de líquido folicular ao final do ciclo estral. Maior número de polipeptídeos é observado em folículos antrais pequenos de ovários em que o CL está em regressão

Wood colorimetry of lauraceae species native to Brazil

Considering the complexity and difficulty of identifying forest species, wooden disks were collected to verify the potential of colorimetry to distinguish native species from Araucaria Forest stands of the Lauraceae family. The following species were used: Nectandra megapotamica, Ocotea indecora, Ocotea diospyrifolia and Ocotea puberula. Nees, to provide data on these species that grow naturally in Santa Catarina state, southern Brazil, enriching a robust database that can be practically applied in the commercialization of native woods. Visible spectra and colorimetric parameters were obtained from each anatomical surface and the results were evaluated by comparing the mean of each species regarding radial trunk position and anatomical surface. The data were also submitted to principal component analysis and performance of discriminant models (k-NN, SVM and ANN) for species discrimination with raw and second-derivative data. In general, colorimetric data presented different behavior, and chromatic coordinates a* and b* had higher potential for distinguishing the species. According to the mean spectra, Ocotea indecora had reflectance values different from the other species. By principal component analysis, raw data indicated the separation only of Ocotea indecora, while second-derivative data allowed better distinction of species. In all discrimination models, second-derivative data produced the best results. Thus, the use of colorimetry has potential for wood distinction of the Lauraceae species evaluated, improving the oversight of illegally traded timber

Building Expertise on FAIR Through Evolving Bring Your Own Data (BYOD) Workshops: Describing the Data, Software, and Management-focused Approaches and Their Evolution

Since 2014, “Bring Your Own Data” workshops (BYODs) have been organised to inform people about the process and benefits of making resources Findable, Accessible, Interoperable, and Reusable (FAIR, and the FAIRification process). The BYOD workshops’ content and format differ depending on their goal, context, and the background and needs of participants. Data-focused BYODs educate domain experts on how to make their data FAIR to find new answers to research questions. Management-focused BYODs promote the benefits of making data FAIR and instruct project managers and policy-makers on the characteristics of FAIRification projects. Software-focused BYODs gather software developers and experts on FAIR to implement or improve software resources that are used to support FAIRification. Overall, these BYODs intend to foster collaboration between different types of stakeholders involved in data management, curation, and reuse (e.g. domain experts, trainers, developers, data owners, data analysts, FAIR experts). The BYODs also serve as an opportunity to learn what kind of support for FAIRification is needed from different communities and to develop teaching materials based on practical examples and experience. In this paper, we detail the three different structures of the BYODs and describe examples of early BYODs related to plant breeding data, and rare disease registries and biobanks, which have shaped the structure of the workshops. We discuss the latest insights into making BYODs more productive by leveraging our almost ten years of training experience in these workshops, including successes and encountered challenges. Finally, we examine how the participants’ feedback has motivated the research on FAIR, including the development of workflows and software

AVALIAÇÃO DE FRATURAS RADICULARES POR MEIO DE TOMOGRAFIA COMPUTADORIZADA DE FEIXE CÔNICO

The objective of this article is to critically review the current literature on the evaluation of root fractures using cone beam computed tomography. Electronic databases, such as PubMed, Scopus and Web of Science, were consulted to obtain published articles. In short, the assessment of root fractures using cone beam computed tomography (CBCT) represents an essential tool in contemporary dental practice. The diagnostic accuracy, detailed treatment planning and post-treatment follow-up provided by TCFC are fundamental to ensuring strategic and urgent results for patients. However, it is crucial to consider the limitations and challenges associated with the use of this technology, as well as to continue investing in research and development to further improve the diagnostic and therapeutic capacity in the evaluation of root fractures, always providing the best possible care to patients.O objetivo deste artigo é revisar criticamente a literatura atual sobre a avaliação de fraturas radiculares por meio da tomografia computadorizada de feixe cônico. Realizou-se uma extensa revisão da literatura para identificar estudos relevantes acerca da avaliação de fraturas radiculares por meio de tomografia computadorizada de feixe cônico. Bases de dados eletrônicas, como PubMed, Scopus e Web of Science, foram consultadas para obter artigos publicados. Em suma, a avaliação de fraturas radiculares por meio da tomografia computadorizada de feixe cônico (TCFC) representa uma ferramenta essencial na prática odontológica contemporânea. A precisão diagnóstica, o planejamento de tratamento detalhado e o acompanhamento pós-tratamento fornecido pela TCFC são fundamentais para garantir resultados eficazes e satisfatórios para os pacientes. No entanto, é crucial reconhecer as limitações e desafios associados à utilização dessa tecnologia, bem como continuar investindo em pesquisa e desenvolvimento para aprimorar ainda mais a capacidade diagnóstica e terapêutica na avaliação de fraturas radiculares, visando sempre proporcionar o melhor cuidado possível aos pacientes

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic