ACE2, the Receptor that Enables Infection by SARS-CoV-2: Biochemistry,Structure, Allostery and Evaluation of the Potential Development of ACE2 Modulators

Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein.     

Synergistic antimicrobial effect of lactocin AL705 and nisin combined with organic acid salts against Listeria innocua 7 in broth and a hard cheese

The effectiveness of antimicrobial mixtures against Listeria innocua 7, used as a L. monocytogenes surrogate, was investigated in broth and a food system. Synergistic effects were found for nisin (Nis), potassium sorbate (PS), calcium propionate (CP) and sodium lactate (SL), Nis + PS being the most effective binary mixture that exhibited listericidal activity in broth. To assess the effect of adding lactocin AL705 (AL705) to Nis + organic acid salt combinations, tridimensional isobolograms were generated. Sub-MIC combinations of the antimicrobials exerted bactericidal activity against L. innocua 7 after AL705 addition to the binary mixtures. However, when applied on Sardo cheese contaminated with L. innocua 7 (initial inoculum 4.45 ± 0.06 CFU g⁻¹), only Nis + PS + AL705 produced count reductions respect to the control, reaching 3.04 ± 0.35 CFU g⁻¹ counts after 15 days at 15 °C. Ternary combinations containing AL705 showed potential to reduce antimicrobial usages for L. innocua 7 inhibition.     

The Simulation of Impact Loads on Beam-type Structures using a Pseudo-dynamic Procedure

Abstract:  This study proposes an alternate method for the analysis of beams with solid cross-section or built as a framed structure and subjected to transverse impact loads from an external striker. The procedure used in the analysis is a combination of two essential tools using pseudo-dynamic techniques. The method reported here involves only one degree of freedom for the structure modelling and assumes an elastic contact between an external striker and the beam structure, which in reality does not happen. As only one degree of freedom is considered in the analysis, some important limitations are inherent to the method proposed here. Essentially, there is the difficulty of modelling the displacement field associated with the transient structure behaviour accurately, as a consequence of fast-rate impact loads. Another difficulty faced by the method refers to a local structure behaviour associated with contact loads. The present method can deal with large displacements in transversely loaded beams associated to a collapse mechanism having a simple geometry and defined with precision from a single parameter. This ensures reasonable accuracy in the evaluation of the strain energy absorbing capacity of transversely impacted beam structures using a single degree of freedom model in a pseudo-dynamic procedure.     

Influence of Cu<Superscript>2+</Superscript> ions on structural and magnetic properties of NiZn ferrites

The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology. The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and possible applications of such materials. A strong correlation between the substituent content and resulting properties has been observed, thus allowing preparation of material with the properties tailored for any particular application.     

Laser Induced Periodic Structures on Polymer Surfaces

Subhalf micron (0.2 nm) space and amplitude linear periodic structures and an array of dot images are obtained with the Nd:YAG laser irradiation on Kapton polyimide films, poly(ethylene terephthalate) films, spin-coated polyimide films and others. Different from the excimer laser irradiation, which requires a polarizer, our solid state Nd:YAG laser source provides polarized beams without a polarizer with advantage over excimer laser irradiation. AFM and SEM studies have been carried out. XPS studies of laser exposed areas indicate no significant chemical reactions took place on exposed areas.     

Strength of short concrete columns confined with CFRP sheets

The confinement of concrete columns provided by carbon fibre reinforced plastic (CFRP) sheets can be an efficient technique for their structural strengthening. The principal advantages of this technique are the high strength-to-weight ratio, good fatigue properties, non-corroding characteristics of the CFRP, and the facility of its application. An experimental research program, that included tests on 54 short column specimens, was carried out to investigate the gain in strength and ductility of concrete columns externally confined by CFRP wrapping. The variables studied were the column cross section shape (circular, square and rectangular) and the amount of confinement expressed in the number of CFRP sheet layers applied to the models (one or two layers). On the basis of the obtained results, equations were proposed to calculate the confined concrete strength and the ultimate confined concrete strain as a function of the confining lateral stress for each of the cross section geometry used, circular, square and rectangular. The estimations given by these equations and by those from formulas encountered in the literature were compared with the experimental ones and general conclusions were, finally, drawn.

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Résumé Le confinement de colonnes de béton assuré par des feuilles de plastique renforcé par des fibres de carbone (CFRP) peut être une technique efficace pour leur comportement structural. Les principaux avantages de cette technique sont la haute relation résistance-poids, des bonnes propriétés de fatigue, les caractéristiques non-corrosives du CFRP, et la facilité de leur application. Un programme expérimental comprenant des essais sur 54 colonnes courtes fut entrepris en vue de déterminer le gain de résistance et de ductilité de colonnes en béton confinées sur le plan externe en les recouvrant de feuilles de CFRP. Les variables étudiées étaient la forme de la section transversale (circulaire, carrée et rectangulaire), et la quantité de renforcement, mesurée par le nombre de feuilles de CFRP appliquées aux modèles (une ou deux couches). En prenant comme base les résultats obtenus, des équations ont été proposées pour calculer la résistance du béton confiné et sa déformation spécifique ultime en fonction de la contrainte latérale de confinement, pour chaque forme de section transversale utilisée, circulaire, carrée et rectangulaire. Les estimations données par ces équations et celles données par des formules trouvées dans la litérature ont été comparées avec les résultats expérimentaux et des conclusions générales ont finalement été établies.