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.     

Geopolymer assembly by emulsion templating: Emulsion stability and hardening mechanisms

This work investigates emulsion templating to synthesize hexadecane oil/geopolymer composites. In a system with hexadecane as the internal (dispersed) phase and an alkali activated continuous phase without added surfactant, adding aluminosilicate clay particles does not increase resistance against creaming or coalescence, while adding a surfactant (L35 or CTAB) stabilizes the solid-liquid interface. Infrared studies and rheological studies of the associated geopolymerization determined that the presence of the organic phase or surfactant has no significant effect on the geopolymerization kinetics, as determined by the change in time of the Si-O-T IR stretching frequency and the rheological moduli involved during the process. The stabilization of the organic template is reminiscent of Pickering emulsion even though we employ a much greater amount of inorganic material for geopolymer formation. Although the addition of surfactant has a significant effect on the behavior of the paste, the percolation of the network remains unmodified, highlighting the fact that the phenomenon is not dependent on viscosity. Finally, rheological measurements were used to obtain the mass fractal dimension of the as-made gel network, which is able to differentiate the interfacial effect between surfactant molecules with a slightly denser interphase when a cationic surfactant is used.     

ESD–RF co-design methodology for the state of the art RF-CMOS blocks

This paper describes an approach to design ESD protection for integrated low noise amplifier (LNA) circuits used in narrowband transceiver front-ends. The RF constraints on the implementation of ESD protection devices are relaxed by co-designing the RF and the ESD blocks, considering them as one single circuit to optimise. The method is applied for the design of 0.25 μm CMOS LNA. Circuit protection levels higher than 3 kV HBM stress are achieved using conventional highly capacitive ggNMOS snapback devices. The methodology can be extended to other RF-CMOS circuits requiring ESD protection by merging the ESD devices in the functionality of the corresponding matching blocks.     

Making polyurethane foams from microemulsions

A remarkable correlation exists between the degree of expansion of polyurethane foams and the structure of the reacting premixes. Polyurethane foams obtained from reacting premixes containing microemulsions are highly expanded. The expansion rate is proportional to the volume fraction of microemulsion in the premix. The stability of premixes with and without microemulsion is completely different suggesting distinct creaming mechanisms. We apply this idea to synthesize polyurethane foams from microemulsions successfully. This approach can be used to rationalize the design of polyurethane formulations leading to highly expanded foams.     

New regulations and rules for ATEX directives

This article deals with directive 94/9/EC which applies to products that exist in an oil and gas company under the responsibility of the electrical, instrumentation engineers. Directive 1999/92/EC applies to users and defines the minimum requirements for improving the safety and health protection of workers, is under the responsibility of the safety division (HSE). These new ATEX directives are called the "new approach," which aims to ensure free movement of the products to which it applies by removing barriers to trade. It also aims to improve the safety of products and users. The main advantage of the new approach is that it is no longer necessary to make an adaptation to technical developments in order to keep up with technical developments     

Jitter in ATM networks and its impact on peak rate enforcement

Cells arriving to an ATM network experience random delays due to queueing in upstream multiplexing stages, notably in customer premises. This is the phenomenon of jitter and the aim of the present paper is to study its influence on peak rate enforcement. We first introduce some general characterizations of jitter and then, describe two models of jittered flows based on simple queueing systems. We discuss the objectives of peak rate enforcement and study the impact of jitter on the dimensioning of jumping window and leaky bucket mechanisms. A useful synthetic characterization of jitter appears to be a remote quantile of the cell delay distribution expressed in units of the initial inter-cell interval.     

Shear mode coupling and tilted grain growth of A1N thin films in BAW resonators.

Polycrystalline A1N thin films were deposited by RF reactive magnetron sputtering on Pt(111)/Ti electrode films. The substrates were tilted by an angle ranging from 40 degrees to 70 degrees with respect to the target normal. A low deposition temperature and a high sputter gas pressure were found ideal for tilted growth. The resulting grain tilt angle amounts to about half the substrate tilt angle. For coupling evaluation, 5 GHz solidly mounted resonator structures have been realized. The tilted grain A1N films exhibited a permittivity in the 9.5-10.5 range and loss tangent of 0.3%. Two shear modes as well as the longitudinal mode could be clearly identified. The coupling coefficient k2(eff) of the fundamental thickness shear mode (TS0) was found to be about 0.5%, which is compatible with a c-axis tilt of about 6 degrees.     

Fabrication of a biocompatible flexible electroosmosis micropump

In in-vivo microsystems, one of the components is a biocompatible micropump in order to produce the necessary force to deliver the fluid from the inlet to the outlet. In this contribution, a flexible micropump is fabricated which is aimed to be suitable in drug delivery applications. It provides high degree of biocompatibility, since the only employed materials are implantation grade polydimethylsiloxane elastomer and gold for the electrical interconnects. The working principle of the micropump is based on transverse DC electroosmosis which is a new variant of conventionally applied high voltage DC electroosmosis. This new technique is based on topography irregularities introduced in the channel resulting in a non-uniform charge distribution. The advantage is to drive the micropump using a relatively low DC voltage of 10 V while getting an effective flow speed of 60 μm/s. In order to characterize the flow speed, dyed 3 μm beads are dispersed in the working fluid and their speed is measured by the line scanning technique using a confocal microscope. It is also observed that the flow has a helical profile which is an attractive feature for an efficient micro-mixer in active microfluidics and μ-TAS applications.