Optical fibers by butyl methacrylate reactive extrusion

51 p.A process for a poly(butyl methacrylate) optical fibers production by reactive extrusion was developed. The reactive system was adapted to the reduced reaction time in the extruder combining concepts based on the free volume theory and a kinetic model for mass polymerization a butyl methacrylate. A kinetic model was proposed and the reaction evolution was simulated at different temperature and initiator concentration. This allowed the choice of reaction conditions in adequation with reactive extrusion technical limitations. Reactive extrusion experiments were carried out in a twin-screw extruder and the effect of the different kinetic and process conditions on the reaction were analyzed in relation with the residence time distribution measured by an UV fluorescence method. Some optical properties of poly(butyl methacrylate) fibres were reported

Consequences of gestational diabetes mellitus on neonatal cardiovascular health: MySweetHeart Cohort study

Hyperglycaemic disorders of pregnancy are associated with offspring cardiovascular alterations. MySweetHeart cohort study aimed to assess the effect of maternal gestational diabetes (GDM) on offsprings' cardiovascular health. Newborns underwent clinical and echocardiographic examinations between 2016 and 2020. Compared to mothers without GDM (n = 141), mothers with GDM (n = 123) were more likely to have had GDM in previous pregnancies and had higher weight, BMI, blood glucose, and HbA1c. Newborns of both groups showed similar clinical characteristics. Echocardiography was performed on the 3rd (interquartile range, IQR, 2nd-4th) day of life in 101 offsprings of mothers without and 116 offsprings of mothers with GDM. Left ventricular (LV) mass was similar. Children born to mothers with GDM had a thicker posterior LV wall (z-score +0.15, IQR -0.38/0.62, versus +0.47, IQR -0.11/+1.1, p = 0.004), a smaller end-systolic (1.3 mL, IQR 1.0-1.5 mL, versus 1.4 mL, IQR 1.2-1.8 mL, p = 0.044) but a similar end-diastolic LV volume. They also had shorter tricuspid valve flow duration and aortic valve ejection time, lower tricuspid E-wave and pulmonary valve velocities. Newborns of mothers with or without GDM had similar clinical characteristics and LV mass. However, some echocardiographic differences were detected, suggesting an altered myocardial physiology among infants of mothers with GDM. ClinicalTrials.gov (NCT02872974). Hyperglycaemic disorders of pregnancy are known to be associated with offspring cardiovascular alterations. Clinical characteristics and estimated left ventricular (LV) mass were similar in children issued from mothers with and without gestational diabetes (GDM). Children born to mothers with GDM had a thicker posterior LV wall and a smaller end-systolic LV volume. Although LV mass is not different, myocardial physiology may be altered in these infants. Further studies should investigate the endothelial function of this population and the cardiovascular evolution of these children over time

Datamama, bringing pregnancy research into the future: design, development, and evaluation of a citizen science pregnancy mobile application

Background: Pregnancy mobile applications (apps) have grown in popularity over the past decade, with some being used to promote study recruitment or health behaviors. However, no app serves as an all-in-one solution for collecting general data for research purposes and providing women with useful and desirable features. Aim: To create and develop a Swiss pregnancy mobile app as an innovative means to collect research data and provide users with reliable information. Methods: Determining the key features of the app involved a review of the literature and assessment of popular apps in the Swiss AppStore. A team of engineers developed the app, which includes a pregnancy timeline, questionnaires for data collection, medical and psychological articles and a checklist with appointment reminders. The content was written and reviewed by healthcare providers considered experts in the topics adressed. The questionnaires are distributed based on the user’s gestational age, by a chatbot. The project was authorized by the ethics commission in the canton of Vaud. An online survey of ten questions, advertised on Datamama’s home screen, was conducted to assess the users’ use of the app (27.11- 19.12.2022). Results: A review of 84 articles and 25 popular apps showed the need for a comprehensive pregnancy app. The development of Datamama took 2 years and included the creation of 70 medical and psychological articles and 29 questionnaires covering 300 unique variables. Six months after the launch, there were 800 users with a 73% average participation rate in the questionnaires. Sixty-five women completed the survey, with 70.8% using the app once to multiple times per week. The primary reason for using the app was to help research by answering the questionnaires, followed by access to reliable medical information. The reason most frequently ranked first for using the app was to help research by answering the questionnaires (42/65, 67% of women rated it first), followed by access to reliable medical information (34/65, 54% women rated it second). Women rated the information as clear, understandable, and interesting with a trust rating in data handling at 98.5%. The average grade for recommending the app was 8/10, with suggestions for increasing the amount of medical content and tailoring it based on gestational age. Conclusion: Datamama is the first pregnancy app to address the needs of both patients and researchers. Initial feedback from users was positive, highlighting future challenges for success. Future work will consist in improving the app, validating the data and use it to answer specific pregnancy-related research questions

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

A nearly optimal preconditioning based on recursive red-black orderings

Considering matrices obtained by the application of a five-point stencil on a 2D rectangular grid, we analyse a preconditioning method introduced by Axelsson and Eijkhout, and by Brand and Heinemann. In this method, one performs a (modified) incomplete factorization with respect to a so-called ‘repeated’ or ‘recursive’ red–black ordering of the unknowns while fill-in is accepted provided that the red unknowns in a same level remain uncoupled.Considering discrete second order elliptic PDEs with isotropic coefficients, we show that the condition number is bounded by [MATHEMATICAL SCRIPT CAPITAL O](nmath image) where n is the total number of unknowns (½ log2(√(5) − 1) = 0.153), and thus, that the total arithmetic work for the solution is bounded by [MATHEMATICAL SCRIPT CAPITAL O](n1.077). Our condition number estimate, which turns out to be better than standard [MATHEMATICAL SCRIPT CAPITAL O](log2n) estimates for any realistic problem size, is purely algebraic and holds in the presence of Neumann boundary conditions and/or discontinuities in the PDE coefficients.Numerical tests are reported, displaying the efficiency of the method and the relevance of our analysis. © 1997 John Wiley & Sons, Ltd.FLWINinfo:eu-repo/semantics/publishe

Incomplete factorization preconditioning may lead to multigrid like speed of convergence

info:eu-repo/semantics/publishe

Preparation of unsaturated poly(-caprolactone) with a new titanium alkoxide

International audienceTitanium alkoxides are widely used in the ring-opening polymerization of epsilon-caprolactone. In this study, functional poly(epsilon-caprolactone) was synthesized with a new titanium initiator by a two-step procedure: First, the titanium initiator, with an unsaturated group, was prepared by a classical organic reaction between 2-hydroxyethylmethacrylate or 2-allyloxyethanol with titanium tetrapropoxide; then, we initiated the polymerization of the epsilon-caprolactone monomer in a glass reactor or twin-screw extruder. By means of NMR spectroscopy, the structures of the initiators and polymers were determined. When 2-hydroxyethylmethacrylate was used, there was a side reaction (transesterification) during the preparation of the initiator, and so it was impossible to obtain the expected product. With 2-allyloxyethanol, the designed titanium initiator was synthesized with high purity, and the allyl moiety remained intact after the polymerization of epsilon-caprolacton

Synthesis of poly(ε-caprolactone)-block-poly(n-butyl acrylate) by combining ring-opening polymerization and atom transfer radical polymerization with Ti[OCH2CCl3]4 as difunctional initiator: I. Kinetic study of Ti[OCH2CCl3]4 initiated ring-opening polymerization of ε-caprolactone

International audienceA new titanium alkoxide, Ti[OCH2CCl3]4, designed to combine the ring-opening polymerization (ROP) of 3-caprolactone and atom transfer radical polymerization (ATRP) of n-butyl acrylate, was synthesized through the ester-exchange reaction of titanium n-propoxide and 2,2,2-trichloroethanol. The mechanism and kinetics of Ti[OCH2CCl3]4 initiated bulk polymerization of 3-caprolactone were studied. The results demonstrate that the polymerization proceeds through the coordination-insertion mechanism and all the four alkoxide groups in Ti[OCH2CCl3]4 share a similar activity in the initiation. The determined polymerization activation energy is 70 kJ/mol. The polymerization process can be well predicted by the obtained kinetic parameters. Furthermore, PCL synthesized with Ti[OCH2CCl3]4 can be used as the macroinitiator in ATRP of n-butyl acrylate to synthesize poly(3-caprolactone)-block-poly(n-butyl acrylate) (PCL-b-PBA) copolymer