Cohort-specific serological recognition of SARS-CoV-2 variant RBD antigens

Background: Estimating the response of different cohorts (e.g. vaccinated or critically ill) to new SARS-CoV-2 variants is important to customize measures of control. Thus, our goal was to evaluate binding of antibodies from sera of infected and vaccinated people to different antigens expressed by SARS-CoV-2 variants. Methods: We compared sera from vaccinated donors with sera from four patient/donor cohorts: critically ill patients admitted to an intensive care unit (split in sera collected between 2 and 7 days after admission and more than ten days later), a NIBSC/WHO reference panel of SARS-CoV-2 positive individuals, and ambulatory or hospitalized (but not critically ill) positive donors. Samples were tested with an anti-SARS-CoV-2 IgG serological assay designed with microplates coated with a SARS-CoV-2 RBD recombinant antigen. The same sample sets were also tested with microplates coated with antigens harbouring RBD mutations present in eleven of the most widespread variants. Results: Sera from vaccinated individuals exhibited higher antibody binding (P<0.001) than sera from infected (but not critically ill) individuals when tested against the WT and each of 11 variants' RBD. The optical density generated by sera from non-critically ill convalescence individuals upon binding to variant's antigens was different (P<0.05) from that of the WT in some variants-noteworthy, Beta, Gamma, Delta, and Delta Plus variants. Conclusions: Understanding differences in binding and neutralizing antibody titers against WT vs variant RBD antigens from different donor cohorts can help design variant-specific immunoassays and complement other diagnostic and clinical data to evaluate the epidemiology of new variants. Key Words: COVID-19; SARS-CoV-2 vaccine; SARS-CoV-2 variants; RBD mutations; antibody specificity; critically ill, immunoassays, serology.

Biomechanical Assessment of Mobile-Bearing Total Knee Endoprostheses Using Musculoskeletal Simulation

The purpose of this computational study was to analyze the effects of different mobile-bearing (MB) total knee replacement (TKR) designs on knee joint biomechanics. A validated musculoskeletal model of the lower right extremity implanted with a cruciate-retaining fixed-bearing TKR undergoing a squat motion was adapted for three different MB TKR design variants: (I) a commercially available TKR design allowing for tibial insert rotation about the tibial tray with end stops to limit the range of rotation, (II) the same design without end stops, and (III) a multidirectional design with an additional translational degree-of-freedom (DoF) and end stops. When modeling the MB interface, two modeling strategies of different joint topologies were deployed: (1) a six DoF joint as a baseline and (2) a combined revolute-prismatic joint (two DoF joint) with end stops in both DoF. Altered knee joint kinematics for the three MB design variants were observed. The commercially available TKR design variant I yielded a deviation in internal-external rotation of the tibial insert relative to the tray up to 5° during knee flexion. Compared to the multidirectional design variant III, the other two variants revealed less femoral anterior-posterior translation by as much as 5 mm. Concerning the modeling strategies, the two DoF joint showed less computation time by 68%, 80%, and 82% for design variants I, II, and III, respectively. However, only slight differences in the knee joint kinematics of the two modeling strategies were recorded. In conclusion, knee joint biomechanics during a squat motion differed for each of the simulated MB design variants. Specific implant design elements, such as the presence of end stops, can impact the postoperative range of knee motion with regard to modeling strategy, and the two DoF joint option tested accurately replicated the results for the simulated designs with a considerably lower computation time than the six DoF joint. The proposed musculoskeletal multibody simulation framework is capable of virtually characterizing the knee joint dynamics for different TKR designs.

Regional and temporal variations affect the accuracy of variant-specific SARS-CoV-2 PCR assays

Monitoring the prevalence of SARS-CoV-2 variants is necessary to make informed public health decisions during the COVID-19 pandemic. PCR assays have received global attention, facilitating rapid understanding of variant dynamics because they are more accessible and scalable than genome sequencing. However, as PCR assays target only a few mutations, their accuracy could be compromised when these mutations are not exclusive to target variants. Here we show how to design variant-specific PCR assays with high sensitivity and specificity across different geographical regions by incorporating sequences deposited in the GISAID database. Furthermore, we demonstrate that several previously developed PCR assays have decreased accuracy outside their study areas. We introduce PRIMES, an algorithm that enables the design of reliable PCR assays, as demonstrated in our experiments that enabled tracking of dominant SARS-CoV-2 variants in local sewage samples. Our findings will contribute to improving PCR assays for SARS-CoV-2 variant surveillance.

Selection of parameters during shredding of corn stalks as an additive to the polymer

This paper presents the results of research on the process of grinding dried corn stalks to use them as polylactide filler. Shredding was carried out on a laboratory shredder with the use of a design variant based on discs with cylindrical holes. By selecting the design variant, the appropriate grinding speed and the material pressure on the shredder discs, the most favourable parameters in terms of the quality of the shredded product and low energy consumption were selected. The research was conducted to reduce the energy demand during the shredding process and to obtain the shredded material suitable for further processing steps.

Comparison of Common Ground Models for Human--Computer Dialogue

Common ground processes [26] can improve performance in communication tasks [72, 42, 43, 24], and understanding these processes will likely benefit human--computer dialogue interfaces. However, there are multiple proposed theories with different implications for interface design. Fusaroli and Tylén [40] achieved a direct comparison by designing two models: one based on alignment theory and the other based on complementarity theory that encapsulated interpersonal synergy and audience design. The current research used these models, extending them to differentiate between interpersonal synergy and audience design. Few studies have tested multiple common ground models against tasks representative of envisioned human--computer interaction (HCI) applications. We report on four such tests, which allowed examination of generalizability of findings. Results supported the complementarity models over the alignment model, and were suggestive of the audience design variant of complementarity, providing guidance for HCI design that differs from contemporary approaches.

Optimization design of elastomeric locks

This paper discusses the development of small boats made of polymeric composites in combination with metal skeleton based on detachable elastic connections. Lock material was polyethylene with hyperelastic properties of an elastomer. Static calculation is performed as per the finite-element method in plane formulation taking into account contact, geometric and physical non-linearity, as well as implementing a step-wise procedure. Design calculation is performed as per the research method approximating the sub-task (quadratic programming). The paper presents calculations for the process of inserting/extracting a rigid bar with round free flange to/from the lock, with determination of maximum responses, strains and stresses of the insert. Variation of geometric parameters yielded a design variant with minimum load on the insert and the same strength properties as the initial design. The study also yielded the analytical design methodology for elastic detachable connections that combines the solutions to non-linear contact problem and the optimization problem.

THE OPTIONS OF WASTE HEAT UTILIZATION IN A BUILDING OF MEDICAL PRODUCT’S MANUFACTURE

This article examines the possibilities of using waste heat in a building for the production of medical products. During the production, 6 compressors operate continuously, and the generated excess heat is removed through coolers or partially used in building heating, ventilation and domestic hot water production systems. The aim of this article is to model and evaluate the possibilities of using waste heat after performing the analysis of heat flow demand of all the engineering systems. The pinch method is used to achieve this goal. Heat flows and heat exchanger network are modelled using PinCH 3.0 software. The performed assessment shows that with the help of pinch analysis, in the analysed object it is possible to recover and use more than 20% of waste heat as compared to the initial design variant.