Structural stability of SARS-CoV-2 virus like particles degrades with temperature.

SARS-CoV-2 is a novel coronavirus which has caused the COVID-19 pandemic. Other known coronaviruses show a strong pattern of seasonality, with the infection cases in humans being more prominent in winter. Although several plausible origins of such seasonal variability have been proposed, its mechanism is unclear. SARS-CoV-2 is transmitted via airborne droplets ejected from the upper respiratory tract of the infected individuals. It has been reported that SARS-CoV-2 can remain infectious for hours on surfaces. As such, the stability of viral particles both in liquid droplets as well as dried on surfaces is essential for infectivity. Here we have used atomic force microscopy to examine the structural stability of individual SARS-CoV-2 virus like particles at different temperatures. We demonstrate that even a mild temperature increase, commensurate with what is common for summer warming, leads to dramatic disruption of viral structural stability, especially when the heat is applied in the dry state. This is consistent with other existing non-mechanistic studies of viral infectivity, provides a single particle perspective on viral seasonality, and strengthens the case for a resurgence of COVID-19 in winter.

Structural stability of SARS-CoV-2 degrades with temperature.

SARS-CoV-2 is a novel coronavirus which has caused the COVID-19 pandemic. Other known coronaviruses show a strong pattern of seasonality, with the infection cases in humans being more prominent in winter. Although several plausible origins of such seasonal variability have been proposed, its mechanism is unclear. SARS-CoV-2 is transmitted via airborne droplets ejected from the upper respiratory tract of the infected individuals. It has been reported that SARS-CoV-2 can remain infectious for hours on surfaces. As such, the stability of viral particles both in liquid droplets as well as dried on surfaces is essential for infectivity. Here we have used atomic force microscopy to examine the structural stability of individual SARS-CoV-2 virus like particles at different temperatures. We demonstrate that even a mild temperature increase, commensurate with what is common for summer warming, leads to dramatic disruption of viral structural stability, especially when the heat is applied in the dry state. This is consistent with other existing non-mechanistic studies of viral infectivity, provides a single particle perspective on viral seasonality, and strengthens the case for a resurgence of COVID-19 in winter. STATEMENT OF SCIENTIFIC SIGNIFICANCE: The economic and public health impact of the COVID-19 pandemic are very significant. However scientific information needed to underpin policy decisions are limited partly due to novelty of the SARS-CoV-2 pathogen. There is therefore an urgent need for mechanistic studies of both COVID-19 disease and the SARS-CoV-2 virus. We show that individual virus particles suffer structural destabilization at relatively mild but elevated temperatures. Our nanoscale results are consistent with recent observations at larger scales. Our work strengthens the case for COVID-19 resurgence in winter.

Hindwings of insects as concept generator for hingeless foldable shading systems.

Hingeless shading systems inspired by nature are increasingly the focus of architectural research. In contrast to traditional systems, these compliant mechanisms can reduce the amount of maintenance-intensive parts and can easily be adapted to irregular, doubly curved, facade geometries. Previous mechanisms rely merely on the reversible material deformation of composite structures with almost homogeneous material properties. This leads to large actuation forces and an inherent conflict between the requirements of movement and the capacity to carry external loads. To enhance the performance of such systems, current research is directed at natural mechanisms with concentrated compliance and distinct hinge zones with high load-bearing capacity. Here, we provide insights into our biological findings and the development of a deployable structure inspired by the Flexagon model of hindwings of insects in general and the hierarchical structure of the wing cuticle of the shield bug (Graphosoma lineatum). By using technical fibre-reinforced plastics in combination with an elastomer foil, natural principles have been partially transferred into a multi-layered structure with locally adapted stiffness. Initial small prototypes have been produced in a vacuum-assisted hot press and sustain this functionality. Initial theoretical studies on test surfaces outline the advantages of these bio-inspired structures as deployable external shading systems for doubly curved facades.

An integrated Shannon's Entropy-TOPSIS methodology for environmental risk assessment of Helleh protected area in Iran.

This study aims to use integrated Shannon's Entropy-TOPSIS methodology for environmental risk assessment of the Helleh protected area in Iran. In this research, first, with regard to field visits, interview with natives of the area, and investigation of the environment of the study area, the risks existing in the region were identified. Then, for final identification of the risks, the Delphi method was applied. Analysis and prioritization of risks of the area of Helleh were performed by multi-criteria decision-making methods of Shannon's Entropy and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). In this research, risks were assessed by three criteria of severity, probability of occurrence, and vulnerability. Twenty six of the risks were identified which were specified in two groups, natural events and environmental risks. The environmental ones were classified into four groups: physicochemical, biological, social-economic, and cultural. Results of the research showed that the construction of the Rayis-Ali-Delvari Dam at the upper part of the study area threatens the wetland. Water supply for the dam 75 km away from the area with concession of 0.9999 holds the first priority of risk-generating factors. Of the managerial workable solutions suggested controlling the risks, the stopping of the pumping of water from the wetland and observation of hunting season length and permissible type and number of hunting in the area can be mentioned.

Substrate recognition by gelatinase A: the C-terminal domain facilitates surface diffusion.

An investigation of gelatinase A binding to gelatin produced results that are inconsistent with a traditional bimolecular Michaelis-Menten formalism but are effectively accounted for by a power law characteristic of fractal kinetics. The main reason for this inconsistency is that the bulk of the gelatinase A binding depends on its ability to diffuse laterally on the gelatin surface. Most interestingly, we show that the anomalous lateral diffusion and, consequently, the binding to gelatin is greatly facilitated by the C-terminal hemopexin-like domain of the enzyme whereas the specificity of binding resides with the fibronectin-like gelatin-binding domain.