Experimental and Numerical Study of Surface Roughness of Thin Brass Wire Processed by Different Dieless Drawing Processes

This paper examines the surface roughness of a thin brass wire (140–200 microns in diameter) after two dieless drawing (DD) processes, i.e., conventional dieless drawing (CDD) and incremental dieless drawing (IDD). In incremental dieless drawing, small increments in deformation were applied in several passes. It has been proven that the IDD process not only has a greater efficiency but also enables obtaining a wire with significantly lower surface roughness. The explanation for these effects is based on the results of the numerical modeling of both compared processes. The developed numerical model takes into consideration the initial roughness of the wire surface, shape and dimensions of grains, and their diversified mechanical properties. Nanoindentation measurements, microstructure, and plastometric studies allowed us to find the effective flow stress distribution in the grains. The IDD process was found to be much more stable and develop a much more uniform distribution of grain strain than the CDD process. More homogeneous deformation results in surface roughness reduction. Approximately 25–30% reduction in surface roughness of the wire produced by the IDD process was predicted by simulations and confirmed experimentally.

Economical droplet-based microfluidic production of [18F]FET and [18F]Florbetaben suitable for human use

Current equipment and methods for preparation of radiopharmaceuticals for positron emission tomography (PET) are expensive and best suited for large-scale multi-doses batches. Microfluidic radiosynthesizers have been shown to provide an economic approach to synthesize these compounds in smaller quantities, but can also be scaled to clinically-relevant levels. Batch microfluidic approaches, in particular, offer significant reduction in system size and reagent consumption. Here we show a simple and rapid technique to concentrate the radioisotope, prior to synthesis in a droplet-based radiosynthesizer, enabling production of clinically-relevant batches of [18F]FET and [18F]FBB. The synthesis was carried out with an automated synthesizer platform based on a disposable Teflon-silicon surface-tension trap chip. Up to 0.1 mL (4 GBq) of radioactivity was used per synthesis by drying cyclotron-produced aqueous [18F]fluoride in small increments directly inside the reaction site. Precursor solution (10 µL) was added to the dried [18F]fluoride, the reaction chip was heated for 5 min to perform radiofluorination, and then a deprotection step was performed with addition of acid solution and heating. The product was recovered in 80 µL volume and transferred to analytical HPLC for purification. Purified product was formulated via evaporation and resuspension or a micro-SPE formulation system. Quality control testing was performed on 3 sequential batches of each tracer. The method afforded production of up to 0.8 GBq of [18F]FET and [18F]FBB. Each production was completed within an hour. All batches passed quality control testing, confirming suitability for human use. In summary, we present a simple and efficient synthesis of clinically-relevant batches of [18F]FET and [18F]FBB using a microfluidic radiosynthesizer. This work demonstrates that the droplet-based micro-radiosynthesizer has a potential for batch-on-demand synthesis of 18F-labeled radiopharmaceuticals for human use.

Epidemiology: Gray Immunity Model Gives Qualitatively Different Predictions

Compartmental models like the SIR model that dynamically divide the host population in categories such as susceptible, infected and immune form the mainstream of epidemiological modelling. Effectively such models treat infection and immunity as binary variables. We show here that considering immunity as a continuous variable instead of binary and incorporating factors that bring about small changes in immunity lead to qualitatively different epidemiological predictions. The small immunity effects (SIE) constitute cross immunity by other infections, small increments in immunity by sub clinical exposures and slow decay in the absence of repeated exposure. The SIE model explains many epidemiological patterns observed during the Covid-19 pandemic that are not adequately explained by conventional models. In the SIE model repeated waves are possible without the need for new variants. Peak and decline of a wave much before reaching herd immunity threshold, low level apparently stable existence of the pathogen, new surges after variable and unpredictable gaps, new surge after vaccinating majority of population are the common features of the pandemic mimicked by simulations using the SIE model. The model further shows complex interactions of different interventions that can be contextually synergistic as well as antagonistic. As a result, interventions intended to arrest the transmission are not always effective and can turn counterproductive under some conditions. Interventions that are beneficial in the short run can be potentially hazardous in the long run. In the absence of empirical estimates of many parameters, the model may not be useful to make quantitative predictions at this stage but it certainly challenges traditional wisdom and currently held beliefs behind non-pharmaceutical interventions recommended to control the epidemic. We also suggest testable predictions to differentiate between the causal logic of the SIE model against the prevalent explanations for the same observed phenomena.

Epidemiology: Gray Immunity Model Gives Qualitatively Different Predictions

Compartmental models like the SIR model that dynamically divide the host population in categories such as susceptible, infected and immune form the mainstream of epidemiological modelling. Effectively such models treat infection and immunity as binary variables. We show here that considering immunity as a continuous variable instead of binary and incorporating factors that bring about small changes in immunity lead to qualitatively different epidemiological predictions. The small immunity effects (SIE) constitute cross immunity by other infections, small increments in immunity by sub clinical exposures and slow decay in the absence of repeated exposure. The SIE model explains many epidemiological patterns observed during the Covid-19 pandemic that are not adequately explained by conventional models. In the SIE model repeated waves are possible without the need for new variants. Peak and decline of a wave much before reaching herd immunity threshold, low level apparently stable existence of the pathogen, new surges after variable and unpredictable gaps, new surge after vaccinating majority of population are the common features of the pandemic mimicked by simulations using the SIE model. The model further shows complex interactions of different interventions that can be contextually synergistic as well as antagonistic. As a result, interventions intended to arrest the transmission are not always effective and can turn counterproductive under some conditions. Interventions that are beneficial in the short run can be potentially hazardous in the long run. In the absence of empirical estimates of many parameters, the model may not be useful to make quantitative predictions at this stage but it certainly challenges traditional wisdom and currently held beliefs behind non-pharmaceutical interventions recommended to control the epidemic. We also suggest testable predictions to differentiate between the causal logic of the SIE model against the prevalent explanations for the same observed phenomena.

Theoretical aspects of obtaining a helical surface from a thin strip during sheet stamping

В статье рассмотрены теоретические аспекты получения винтовой поверхности из тонкой полосы при листовой штамповке. Также предложена модель для расчета компонентов напряженно-деформированного состояния полосы и отдельных технологических параметров. Для удобства расчетов предполагается, что полоса имеет достаточную длину и угол закручивания по всей длине полосы одинаков. Несмотря на значительные упрощения геометрического характера, задача о кручении полосы остается сложной, вследствие двумерности напряженного состояния, геометрической и физической нелинейности процесса деформирования. Ее дальнейшее решение целесообразно основывать на методе конечных элементов, ориентируясь на применение ЭВМ. Для замыкания системы уравнений, описывающих поведение дискретной модели полосы на шаге нагружения, необходимо связать напряжения и малые приращения деформаций в середине каждого элемента. Для этого используем теорию пластического течения, пренебрегая упругими составляющими деформаций вследствие их малости по сравнению с большими пластическими деформациями. The article deals with the theoretical aspects of obtaining a helical surface from a thin strip during sheet stamping. A model is also proposed for calculating the components of the stress-strain state of the strip and individual technological parameters. For convenience of calculations, it is assumed that the strip has a sufficient length and the angle of twisting along the entire length of the strip is the same. Despite significant geometric simplifications, the problem of band torsion remains complex due to the two-dimensionality of the stress state, the geometric and physical nonlinearity of the deformation process. Its further solution should be based on the finite element method, focusing on the use of computers. To close the system of equations describing the behavior of the discrete band model at the loading step, it is necessary to relate the stresses and small increments of deformations in the middle of each element. To do this, we use the theory of plastic flow, neglecting the elastic components of deformations due to their smallness in comparison with large plastic deformations.

Association between COVID-19, mobility and environment in São Paulo, Brazil

BackgroundBrazil, the country most impacted by the coronavirus disease 2019 (COVID-19) on the southern hemisphere, use intensive care admissions per day, mobility and other indices to control quarantines and prevent the transmissions of SARS-CoV2.In this study we quantified the associations between residential mobility index (RMI), air pollution, meteorology, and daily cases and deaths of COVID-19 in São Paulo, BrazilObjectivesTo estimate the associations between daily residential mobility index (RMI), air pollution, and meteorology, and daily cases and deaths for COVID-19 in São Paulo, Brazil.MethodsWe applied a semiparametric generalized additive model (GAM) to estimate: 1) the association between residential mobility index and cases and deaths due to COVID-19, accounting for ambient particulate matter (PM2.5), ozone (O3), relative humidity, temperature and delayed exposure between 3-21 days and 2) the association between exposure to for ambient particulate matter (PM2.5), ozone (O3), accounting for relative humidity, temperature and mobility.ResultsWe found an RMI of 45.28% results in 1,212 cases (95% CI: 1,189 to 1,235) and 44 deaths (95% CI: 40 to 47). Reducing mobility 5% would avoid 438 cases and 21 deaths. Also, we found that an increment of 10 μg·m-3 of PM2.5 risk of 1.140 (95% CI: 1.021 to 1.274) for cases and of 1.086 (95% CI: 1.008 to 1.170) for deaths, while O3 produces a relative risk of 1.075 (95% CI: 1.006 to 1.150) for cases and 1.063 (95% CI: 1.006 to 1.124) for deaths, respectively.DiscussionWe compared our results with observations and literature review, finding well agreement. These results implicate that authorities and policymakers can use such mobility indices as tools to support social distance activities and assess their effectiveness in the coming weeks and months. Small increments of air pollution pose a risk of COVID-19 cases.ConclusionSpatial distancing is a determinant factor to control cases and deaths for COVID-19. Small increments of air pollution result in a high number of COVID-19 cases and deaths. PM2.5 has higher relative risks for COVID-19 than O3.

Fast Clinical, but Long-Term, Biochemical Remission after Waterhouse–Friderichsen Syndrome

Background. The Waterhouse–Friderichsen Syndrome (WFS) is a course of bacterial meningitis with a lethality rate that is still high today. One hallmark of the clinical course is intravascular coagulopathy. This causes hemorrhagic infarctions in the adrenal glands, rapidly causing a primary adrenal insufficiency. Only few reports highlight the course of the remaining adrenal insufficiency or adrenal restitution in survivors. Case Presentation. After 3 weeks in an intensive care unit, a 45-year-old male survived WFS with necroses on the legs and forefeet and with primary adrenal insufficiency confirmed by the ACTH stimulation test. The substitution therapy with hydrocortisone and fludrocortisone could be gradually discontinued after nine months due to a further positive clinical course. Although the patient reported good mental and physical performance further on, the cortisol response in ACTH testing showed tiny incremental rises of the stimulated serum cortisol, but to reach a formally normal level, it took about five years. Discussion. The report demonstrates a case with a relatively fast clinical remission. A remission of the corticotrophic response occurred in small increments during an observational period of five years. The data suggest that not only a clinical remission is possible but also a complete biochemical remission, although this process may take a much longer timespan.

Kurbskii and the Historians

This chapter focuses on Prince Andrei Mikhailovich Kurbskii, who was descended from the princes of Yaroslavl´ and was remotely connected to the family of the Tsaritsa Anastasia. It covers Kurbskii's successful military career, of which he served both in the sieges of Kazan´ and in the Livonian war a year before his flight to Poland-Lithuania on April 30, 1564. It also cites History of Ivan IV which documents Kurbskii's own accounts of his military career. The chapter examines the interpretations by three of the most influential Russian historians: Karamzin, Solov´ev, and Kliuchevskii in relation to Kurbskii's role in Russian history. It explores fine points of interpretation and small increments of meaning that the three Russian historians had laid over or injected into the words of the Kurbskii statements.