Preliminary Structural Data Revealed That the SARS-CoV-2 B.1.617 Variant's RBD Binds to ACE2 Receptor Stronger Than the Wild Type to Enhance the Infectivity

The evolution of new SARS-CoV-2 variants around the globe has made the COVID-19 pandemic more worrisome, further pressuring the health care system and immunity. Novel variations that are unique to the receptor-binding motif (RBM) of the receptor-binding domain (RBD) spike glycoprotein, i. e. L452R-E484Q, may play a different role in the B.1.617 (also known as G/452R.V3) variant's pathogenicity and better survival compared to the wild type. Therefore, a thorough analysis is needed to understand the impact of these mutations on binding with host receptor (RBD) and to guide new therapeutics development. In this study, we used structural and biomolecular simulation techniques to explore the impact of specific mutations (L452R-E484Q) in the B.1.617 variant on the binding of RBD to the host receptor ACE2. Our analysis revealed that the B.1.617 variant possesses different dynamic behaviours by altering dynamic-stability, residual flexibility and structural compactness. Moreover, the new variant had altered the bonding network and structural-dynamics properties significantly. MM/GBSA technique was used, which further established the binding differences between the wild type and B.1.617 variant. In conclusion, this study provides a strong impetus to develop novel drugs against the new SARS-CoV-2 variants.     

An Exemplar Imidazoline Surfactant for Corrosion Inhibitor Studies: Synthesis,Characterization, and Physicochemical Properties

An optimized one-pot recipe has been developed to synthesize a surfactant molecule, referred to as OMID, consisting of an imidazoline head group and aliphatic tail, which is an exemplar corrosion inhibitor for carbon steel in acidic solutions. As evidenced by gas chromatography, ¹H and ¹³C nuclear magnetic resonance, and Fourier-transform infrared data, a high-purity product was achieved without the use of either a solvent or catalyst. Critical micelle concentration values and corrosion inhibition efficiencies ( η %) were determined in aqueous solutions of hydrochloric acid and sulfuric acid using surface tensiometry and linear polarization resistance measurements, respectively. Hydrolysis of the imidazoline head group as a function of pH (0–11) was explored with ultraviolet–visible absorption spectroscopy. In addition, N 1s and C 1s X-ray photoelectron spectroscopy data were acquired from both surface-adsorbed OMID and a multilayer of the imidazoline head group of OMID. These latter data are highly relevant to those attempting to understand OMID inhibition chemistry.     

Determination of selectivity equations heavy and light product of petroleum on iron based catalysts in Fischer-Tropsch synthesis

The optimal control of selectivity is an important method to trigger catalyst activity in the Fischer-Tropsch synthesis to produce favorable products. The determination of a model that will show the extent of product dependence on various parameters is of great importance in the Fischer-Tropsch synthesis. Efforts to increase a product in industry can be economical. In this research, a comprehensive method was evaluated to create a selectivity model of catalyst Fe/Cu/K/SiO₂ of hydrocarbon products under conditions of temperature, pressure, and space velocity in a fixed-bed reactor. The response surface methodology was used in order to optimize process conditions and the relation of continuous functions between variables, so that the obtained model showed the selectivity of methane, light olefin hydrocarbons, heavy hydrocarbons products by factors such as temperature, pressure, and space velocity. A comparison of the models showed space velocity, among all the other factors, had a considerable effect on the increase selectivity of light hydrocarbons. On the other hand, the selectivity of methane indicates that temperature decrease parameter has the minimum effect on production. Whereas, the temperature rise cause reduces heavy hydrocarbons. The goal is to maximizing light hydrocarbon and minimizing methane and heavy hydrocarbon products.

• Highlights

• ? Comprehensive equations to achieve selectivity model of hydrocarbon products.

• ? The response surface methodology was used in order to optimize process conditions.

• ? The optimum products condition was obtained by using the obtained equations.

     

Human micro-vascular endothelial cell seeding on Cr-DLC thin films for mechanical heart valve applications

In this investigation, chromium modified diamond-like-carbon (Cr-DLC) films were studied for potential applications in mechanical heart valves. Three Cr- DLC samples were prepared using a magnetron sputtering technique employing an intensified plasma assisted processing (IPAP) system. The three samples consisted of the following Cr content: 1 at.%, 5 at.% and 10 at.%. The biological response of human micro-vascular endothelial cells (HMV-EC) seeded on Cr-DLC films was evaluated in terms of initial cell attachment and growth. The Cr-DLC films were characterized using Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), secondary ion mass spectroscopy (SIMS) and by the contact angle technique. Endothelial cell adhesion and growth was found to be affected by changing the Cr content of Cr-DLC films.     

Contents by Keyword

Other Index

Contents by Keyword     

Fog-Sec: Secure end-to-end communication in fog-enabled IoT network using permissioned blockchain system

The technological integration of the Internet of Things (IoT)-Cloud paradigm has enabled intelligent linkages of things, data, processes, and people for efficient decision making without human intervention. However, it poses various challenges for IoT networks that cannot handle large amounts of operation technology (OT) data due to physical storage shortages, excessive latency, higher transfer costs, a lack of context awareness, impractical resiliency, and so on. As a result, the fog network emerged as a new computing model for providing computing capacity closer to IoT edge devices. The IoT-Fog-Cloud network, on the other hand, is more vulnerable to multiple security flaws, such as missing key management problems, inappropriate access control, inadequate software update mechanism, insecure configuration files and default passwords, missing communication security, and secure key exchange algorithms over unsecured channels. Therefore, these networks cannot make good security decisions, which are significantly easier to hack than to defend the fog-enabled IoT environment. This paper proposes the cooperative flow for securing edge devices in fog-enabled IoT networks using a permissioned blockchain system (pBCS). The proposed fog-enabled IoT network provides efficient security solutions for key management issues, communication security, and secure key exchange mechanism using a blockchain system. To secure the fog-based IoT network, we proposed a mechanism for identification and authentication among fog, gateway, and edge nodes that should register with the blockchain network. The fog nodes maintain the blockchain system and hold a shared smart contract for validating edge devices. The participating fog nodes serve as validators and maintain a distributed ledger/blockchain to authenticate and validate the request of the edge nodes. The network services can only be accessed by nodes that have been authenticated against the blockchain system. We implemented the proposed pBCS network using the private Ethereum 2.0 that enables secure device-to-device communication and demonstrated performance metrics such as throughput, transaction delay, block creation response time, communication, and computation overhead using state-of-the-art techniques. Finally, we conducted a security analysis of the communication network to protect the IoT edge devices from unauthorized malicious nodes without data loss.     

Implementation of the time-modulated process to produce diamond films using microwave-plasma and hot-filament CVD systems

A newly developed process called time-modulated chemical vapour deposition (TMCVD) was employed to deposit smooth polycrystalline diamond films onto silicon substrates using both microwave plasma CVD (MPCVD) and hot-filament CVD (HFCVD) systems. The distinctive feature of the TMCVD process, which separates it from the conventional diamond CVD process, is that it pulses methane (CH₄) at different flow rates for different time durations into the vacuum reactor during the entire diamond CVD process. Generally, both MPCVD and HFCVD systems produced results that displayed similar trends, except that the growth rate results obtained using the two CVD systems were conflicting. In comparison to the conventional CVD diamond films, the time-modulated films, deposited using both MPCVD and HFCVD techniques, were generally found to be (i) smoother, (ii) consisted of smaller diamond crystallites and (iii) displayed approx. similar film quality. The diamond-carbon phase purity of the as-grown films was assessed using Raman spectroscopy. In addition, the surface roughness, Ra, values of the deposited films were obtained using surface profilometry.     

Mushroom varieties found in the Himalayan regions of India: Antioxidant,antimicrobial, and antiproliferative activities

Food Science and Biotechnology - This study evaluates the antioxidant, antimicrobial, and antiproliferative activities of mushroom varieties (Agaricus bisporus, Pleurotus ostreatus, and Coprinus...     

Biodiesel production from green seaweed Ulva fasciata catalyzed by novel waste catalysts from Pakistan Steel Industry

This research article is based on the biodiesel synthesis from the marine green macroalga Ulva fasciata, collected from the coast of Karachi, Pakistan using new and the most potential waste catalysts from Pakistan Steel Industry.The oil was extracted with n-hexane then it was analyzed by GC, TLC and by the examination of fuel properties.The metal analysis of catalysts was carried out by chemical tests and flame atomic absorption spectroscopy(FAAS). The thermal treatment of catalysts at 1500–1700 °C during various processes in steel manufacturing industry converted the metals to metal oxides. The presence of CaO, MgO and ZnO in these catalysts made them highly reactive for biodiesel synthesis. The basicity of waste industrial catalysts was calculated to know their basic strength. The transesterification of U. fasciata oil was performed by fast stirring using 9:1 molar ratio of methanol/oil in the presence of seven different waste industrial catalysts for 6 h at 80–100 °C. The solid catalysts were easily separated from product for re-use. In addition, the rate of reaction in the presence of these catalysts was found to be quite feasible. The waste brown dust from the steel converter gave the highest yield(88%) of biodiesel. The production of biodiesel was confirmed by TLC examination and fuel properties in comparison with the ASTM standards.     

Human microvascular endothelial cell seeding on Cr-DLC thin films for heart valve applications

In this investigation, Cr-modified diamond-like carbon (Cr-DLC) films were studied for potential applications in mechanical heart valves. Three Cr-DLC samples were prepared using a magnetron sputtering technique employing an intensified plasma-assisted processing (IPAP) system. The three samples consisted of the following Cr contents: 1, 5, and 10 at.%. The biological response of human microvascular endothelial cells (HMV-EC), seeded on Cr-DLC films, was evaluated in terms of initial cell attachment and growth. The Cr-DLC films were characterized using Raman spectroscopy, x-ray diffraction, scanning electron microscopy, secondary ion mass spectroscopy, and by the contact angle technique. Endothelial cell adhesion and growth were found to be affected by changing the Cr content of Cr-DLC films. This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in St. Paul, MN.