Charged Sites Research Articles

Wettability alteration by Smart Water multi-ion exchange in carbonates: A molecular dynamics simulation study

Smart Water ions (Ca2+, Mg2+, and SO42−) have been found to alter the wettability of oil-wet calcite surfaces, however, the widely proposed multi-ion exchange mechanism has never been understood on a molecular scale. In this work, a new model calcite surface with steps and locally charged sites was developed, and its properties were studied by quantum chemical calculations and molecular dynamics simulations to investigate the origin of the oil-wetness and its reversal by the Smart Water ions at temperatures ranging from 300 to 400 K. The simulation results using the proposed surface model are consistent with experimental results reported in the literature, including the Smart Water ions acting as the potential determining ions, and the oil carboxylate adsorption causing oil-wetness. The wettability alteration involves initial surface binding of Ca2+, which facilitates adsorption of SO42−. The latter enables the detachment of the Ca2+-carboxylate complexes at elevated temperatures (>350 K) where the ionic hydration shells are weakened as suggested by the increased interaction energy from less than −100 to over −400 kJ/mol between Ca2+ and SO42−, rationalizing the observed temperature dependence of the Smart Water effect. Overall, the presented simulations with the newly developed model calcite surface provide important new insights into wettability alteration effect of Smart Water ions, which has important implications for the optimization of the injection brines for enhanced oil recovery.

Application of Hexagonal Fuzzy MCDM Methodology for Site Selection of Electric Vehicle Charging Station

In this paper, the application of hexagonal fuzzy multiple-criteria decision-making (MCDM) methodology for the site selection of electric vehicle charging stations is considered. In this regard, four factors and thirteen sub-factors have been taken into consideration for E-vehicle charging site selection. In this research, the geographic information system (GIS) has been incorporated with MCDM techniques. The fuzzy analytic hierarchy process (FAHP) is used to obtain a fuzzy weight of factors and sub-factors. MCDM tools fuzzy technique for order of preference by similarity to ideal solution (FTOPSIS) and fuzzy complex proportional assessment (FCOPRAS) have been used to rank the selected sites. A centroid-based method for defuzzification and distance measure between two hexagonal fuzzy numbers (HFN) has been developed for this paper. A practical example in Howrah, India, is considered to show the applicability and usefulness of the model. The results depict the suitability of the proposed research. Comparative and sensitivity analyses have been demonstrated to check the reliability, robustness and effectiveness of the proposed method.

Removal of thorium(IV) ions from aqueous solution by polyacrylamide-based monoliths: equilibrium, kinetic and thermodynamic studies

In this study, a series of macroporous polyacrylamide-based monoliths bearing negatively charged interaction sites were synthesized as adsorbents for effective removal of Th4+ from aqueous solutions. The effects of solution pH, contact time, monolith dosage, initial concentration, and temperature on adsorption process was studied. The Langmuir, Freundlich, and Dubinin–Raduskevich adsorption isotherms were applied to describe the adsorption data. The equilibrium data were best fitted with both Freundlich and Langmuir models. The experimental kinetic data were well described by the pseudo-second order kinetic. Thermodynamic studies revealed that the adsorption of Th4+ onto the synthesized monolith was an endothermic and spontaneous process.

Understanding the Ion Transport Behavior across Nanofluidic Membranes in Response to the Charge Variations

AbstractBiological pores regulate the cellular traffic of a diverse collection of molecules, often with extremely high selectivity. Given the ubiquity of charge‐based separation in nature, understanding the link between the charged functionalities and the ion transport activities is essential for designing delicate separations, with the correlation being comparatively underdeveloped. Herein, the effect of charge density from the impact of pore structure is decoupled using a multivariate strategy for the construction of covalent organic framework‐based membranes. How the density of charged sites in the nanofluidic membranes affect the ion transport activity with particular emphasis on Li+ and Mg2+ ions, relevant to the challenge of salt‐lake lithium mining is systematically investigated. Systematic control of the charge distribution produces membranes with numerous advantages, overcoming the long‐term challenge of Li+/Mg2+ separation. The top membrane exhibits an outstanding equilibrium selectivity for Li+ over Mg2+ and operational stability under diffusion dialysis and electrodialysis conditions (Li+/Mg2+ up to 500), qualifying it as a potential candidate for lithium extraction. It is anticipated that the developed nanofluidic membrane platform can be further leveraged to tackle other challenges in controlled separation processes.

Alpha-Hemolysin Channel Interaction with Neutral Polymers

Polyethylene glycols (PEG) or dextran are among the neutral polymers used in single-channel conductance measurements to size the aqueous pore, to evaluate access resistance or to induce osmotic stress in polymer-excluded regions. The use of polymer partitioning into biological nanopores to size the aqueous pore of protein ion channels has become a common approach. While the basic principles of polymer behavior in restricted volumes are well established, little is known about the actual interaction of neutral polymer molecules with charged sites in membranes and channel proteins.

Theoretical Framework for Encapsulation of Inorganic B12N12 Nanoclusters with Alkaline Earth Metals for Efficient Hydrogen Adsorption: A Step Forward toward Hydrogen Storage Materials

The increasing demand for energy storage materials has gained considerable attention of scientific community toward the development of hydrogen storage materials. Hydrogen has become more important, as it not only works efficiently in different processes but is also used as an alternative energy resource whenever it is combined with a cell technology like fuel cell. Herein, efforts are being made to develop efficient hydrogen storage materials based on alkaline earth metal (beryllium, magnesium, and calcium)-encapsulated B12N12 nanocages. Quantum chemical calculations were performed using density functional theory (DFT) and time-dependent DFT at B3LYP/6-31G(d,p) and CAM-B3LYP/6-311+G(d,p) levels of theory for all the studied systems. The adsorption energies of Be-B12N12, Mg-B12N12, and Ca-B12N12 systems suggested that Mg and Ca are not fitted accurately in the cavity of nanocages because of their large size. However, H2 adsorbed efficiently on the metal-encapsulated systems with high adsorption energy values. Furthermore, dipole moment and QNBO (Charges-Natural Bond Orbital) calculations suggested that a greater charge separation is seen in H2-adsorbed metal-encapsulated systems. The molecular electrostatic potential analysis also unveiled the different charge sites in the studied systems and also demonstrated the charge separation upon hydrogen adsorption on metal-encapsulated systems. Partial density of states analysis was performed in the support of frontier molecular orbital distribution that indicates the narrow highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap in hydrogen-adsorbed metal-encapsulated systems. Results of all analyses and global descriptions of reactivity suggested that the designed H2-adsorbed metal-encapsulated B12N12 systems are efficient systems for designing future hydrogen storage materials. Thus, these novel kinds of systems for efficient hydrogen storage purposes have been recommended.

Solid-State Catalytic Hydrogen/Deuterium Exchange in Mexidol

The reaction between spillover hydrogen (SH) and mexidol upon high-temperature solid state catalytic isotope exchange (HSCIE) is studied experimentally and via DFT B3LYP and MP2 calculations. The distribution of isotopes and the activation energy of the reaction are determined via NMR spectro-scopy and mass spectrometry for samples of the deuterium-labeled mexidol obtained via HSCIE at 50–120°C. The DFT calculated activation energy of hydrogen transfer on the charged alumina cluster HH+(‒Al–O–)3(OH)6 is found to agree with the experimental data. A mechanism is proposed for HSCIE between the adsorbed compound and charged Bronsted acid sites formed on the surface of the support upon exposure to hydrogen spillover.

Facile and scalable functionalization of carbon nanofibers for oxygen reduction reaction: Role of nitrogen precursor and non-ionic dispersant

The surface modification of carbon nanomaterials with heteroatoms improves their electrocatalytic activity for oxygen reduction reaction (ORR). The present work reports the surface modification of carbon nanofiber (CNF) with poly(diallyldimethylammonium) chloride (PDDA) and Triton X-100. PDDA behaves as an electron-acceptor, and the intermolecular charge transfer from CNF to PDDA creates delocalized positive charge sites at the edge and basal plane sites of CNF. Triton X-100 disperses CNF, but also acts as a masking agent to obstruct the intermolecular charge transfer between CNF and PDDA. The surface modification of CNF with (PDDA+Triton X-100) is characterized in terms of FESEM, TEM, EDX, Raman, FTIR and TGA. The electrocatalytic activity of the conjugated systems (CNF+PDDA and CNF+Triton X-100+PDDA) is investigated in terms of cyclic voltammetry and linear sweep voltammetry. The reduction of oxygen at PDDA-CNF occurs via a more efficient four-electron (n=3.9) pathway in 0.1M KOH and exhibits a limiting diffusion current density of 3.23mAcm−2, which is closer to the Pt/C electrode (3.41mAcm−2). PDDA-CNF even outperforms PDDA-CNT or graphene for the ORR performance owing to their special morphological features. This study thus provides a facile and viable strategy for the scalable production of CNF based ORR electrocatalysts.

How Does Bridging Core Modification Alter the Photovoltaic Characteristics of Triphenylamine-Based Hole Transport Materials? Theoretical Understanding and Prediction.

Perovskite solar cells have gained immense interest from researchers owing to their good photophysical properties, low-cost production, and high power conversion efficiencies. Hole transport materials (HTMs) play a dominant role in enhancing the power conversion efficiencies (PCEs) and long diffusion length of holes and electrons in perovskite solar cells. In hole transport materials, modification of π-linkers has proved to be an efficient approach for enhancing the overall PCE of perovskite solar cells. In this work, π-linker modification of a recently synthesized H-Bi molecule (R) is achieved with novel π-linkers. After structural modifications, ten novel HTMs (HB1-HB10) with a D-π-D backbone are obtained. The structure-property relationship, and optoelectronic and photovoltaic characteristics of these newly designed hole transport materials are examined comprehensively and compared with reference molecules. In addition, different geometric parameters are also examined with the assistance of density functional theory (DFT) and time-dependent DFT. All the designed molecules exhibit narrow HOMO-LUMO energy gaps (Eg =2.82-2.99 eV) compared with the R molecule (Eg =3.05 eV). The designed molecules express redshifting in their absorption spectra with low values of excitation energy, which in return offer high power conversion efficiencies. Further, density of states and molecular electrostatic potential analysis is performed to locate the different charge sites in the molecules. The reorganizational energies of holes and electrons are found to have good values, suggesting that these novel designed molecules are efficient hole transport materials for perovskite solar cells. In addition, the low binding energy values of the designed molecules (compared with R) offer high current charge density. Finally, complex study of HB9:PC61 BM is also undertaken to understand the charge transfer between the molecules of the complex. The results of all analyses advocate that these novel designed HTMs are promising candidates for the construction of future high-performance perovskite solar cells.

Visible-light-driven graphene supported Cu/Pd alloy nanoparticle-catalyzed borylation of alkyl bromides and chlorides in air

A highly efficient photocatalytic protocol for borylation of alkyl bromides and chlorides with graphene supported Cu/Pd alloy nanoparticles as a heterogeneous catalyst is reported. This photocatalytic system operates with visible light in air, providing a wide range of primary and secondary alkyl halides with B2pin2 or B2neop2 in high yields at low temperatures, thereby demonstrating its broad utility and functional group tolerance. The high performance is attributed to a synergistic effect of localized surface plasmon resonance (LSPR) of Cu and charge transfer from Cu to Pd due to the alloy surface charge heterogeneity. Transfer of energetic electrons from Pd to electrophilic alkyl halides lead to the formation of the alkyl radicals, which quickly react with a nucleophilic adduct of a diboron compound with base adsorbed on the positively charged Cu sites to form the corresponding borylation product.

The role of counterions in ionic liquid crystals.

Previous theoretical studies of calamitic (i.e., rod-like) ionic liquid crystals (ILCs) based on an effective one-species model led to indications of a novel smectic-A phase with a layer spacing being much larger than the length of the mesogenic (i.e., liquid-crystal forming) ions. In order to rule out the possibility that this wide smectic-A phase is merely an artifact caused by the one-species approximation, we investigate an extension that accounts explicitly for cations and anions in ILCs. Our present findings, obtained by grand canonical Monte Carlo simulations, show that the phase transitions between the isotropic and the smectic-A phases of the cation-anion system are in qualitative agreement with the effective one-species model used in the preceding studies. In particular, for ILCs with mesogens (i.e., liquid-crystal forming species) carrying charged sites at their tips, the wide smectic-A phase forms, at low temperatures and within an intermediate density range, in between the isotropic and hexagonal crystal phases. We find that in the ordinary smectic-A phase, the spatial distribution of the counterions of the mesogens is approximately uniform, whereas in the wide smectic-A phase, the small counterions accumulate in between the smectic layers. Due to this phenomenology, the wide smectic-A phase could be interesting for applications, which hinge on the presence of conductivity channels for mobile ions.

Further Step toward a Comprehensive Understanding of the Effect of Surfactant Additions on Altering the Impact Dynamics of Water Droplets.

The addition of surfactants to pure water for specific applications has made controlling the impact dynamics of surfactant-laden droplets a complex phenomenon. This work investigates the influence of the molecular weight (MW), concentration, and ionic nature of the surfactants as well as the substrate surface characteristics on the impact dynamics of surfactant-laden droplets using a high-speed camera at 10 000 frames per second. Sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used as anionic, cationic, and nonionic surfactants, respectively. We used hydrophilic glass slides, hydrophobic polytetrafluoroethylene, and superhydrophobic alkyl ketene dimer (AKD) as substrates. The results show that the efficiency of the surfactant addition in increasing the maximum spreading diameter is significantly influenced by the molecular weight and ionic nature of the solutions as well as the nonwettability of the substrate. Among all of the surfaces examined, the concentration and ionic nature of the solutions were found to be more dominant parameters in determining the energy dissipation in the retraction phase of the droplet impact on the superhydrophobic AKD surfaces. As the concentration decreases or positive charges are present in the solution, it is more likely to observe a similar retraction dynamic to pure water when the droplet hits the superhydrophobic AKD having negatively charged surface sites. Finally, in terms of the impact outcomes of the surfactant-laden droplets on the superhydrophobic AKD, it is shown that the influence of the surfactant addition is more noticeable at lower Weber numbers, where the droplet tries to rebound by overcoming the energy loss that occurred in the spreading.

Binding of tetracycline on soil phyllosilicates with Cd(II) as affected by pH and mineral type

Antibiotics often coexist with heavy metals in contaminated soils, making their behaviors more complicated than their individual presences. Sorption to soil components deeply affects the mobility, bioavailability, and fate of contaminants. However, limited studies have investigated the cosorption characteristics of tetracycline (TC) and heavy metals to typical soil minerals, particularly phyllosilicates. This study investigates the effect of Cd(II) on TC sorption by kaolinite (Kao, 1:1-type) and montmorillonite (Mont, 2:1-type) via isothermal adsorption, coupled with X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Isothermal results show that TC sorption on both kaolinite (Kao, 1:1-type) and montmorillonite (Mont, 2:1-type) is little affected by Cd(II) at pH 4.5 but increases significantly at pH 8.5. The overall effect of Cd(II) on TC sorption depends on the intensities of two positive processes, i.e., (1) the formation of soluble Cd-TC complex increases sorption compared to free TC molecules and (2) the formation of a ternary clay-Cd-TC complex at clay variable edge sites increases sorption, and one negative process, i.e., competition of Cd(II) with cationic and zwitterionic TC species at the permanently charged sites decreases sorption. XRD analyses demonstrate that TC intercalates into the interlayer (d001 = 18.7 A) of Mont as one monolayer parallel molecule both with and without Cd(II) but adsorbs predominately on external surface of Kao. FTIR results suggest a flat-lying horizontal configuration of adsorbed TC molecules on clays, accompanied by a strong complexation between the carbonyl and amino groups of TC molecules and the surfaces. Besides, the presence of Cd(II) more or less facilitates this complexation. We propose that Cd(II) can significantly promote TC adsorption on clay minerals at alkaline pH rather than acidic pH. TC and Cd(II) interact intensely and form strong surface complexation on clay surfaces. Hence, coexistence with Cd(II) may lower the mobility and thus the bioavailability of TC in alkaline soils, which provides a new direction for soil remediation by regulating soil pH using alkaline materials.

Unveiling surface charge on chalcogen atoms toward the high aspect-ratio colloidal growth of two-dimensional transition metal chalcogenides.

Controlling surface energies of each facet is essential for the anisotropic growth of two-dimensional transition metal chalcogenides (TMCs). However, it is a challenge due to stronger binding energies of ligand head groups to the edge facets compared to the planar facets. Herein, we demonstrate that the adsorption of ligands on metal positions can induce partial electron localization on the chalcogen sites, and then accelerate metal-chalcogen bond formation for enhanced anisotropic growth of nanosheets. And only in the case of trioctylphosphine oxide (TOPO)-adsorbed nanosheets, surface polarization can be unveiled on the surface of the colloidal nanosheets due to restricted development of nonpolar ligand shells by the steric effects of the ligands. Moreover, density functional theory (DFT) calculation results reveal that the decrease of surface energy on the (100) edge facets as well as the increase on the (001) basal facets by the adsorption of triorganylphosphine oxide also contribute to the preferentially lateral growth. As a result, various 2D TMCs, including MoSe2, WSe2, and SnSe2 synthesized with TOPO, show enhanced anisotropic growth.

Effect of medium properties on the transport of cadmium in saturated porous medium

ABSTRACT The presence of different soils composition complicates the transport behaviors of Cd(II) and thus makes it challenging to predict Cd(II) fate and transport. In this study, montmorillonite modified sand, humic acid modified sand and ferrihydrite modified sand were used as medium to explore the effect of modified sand content, pH and ionic strength (IS) on Cd(II) transport. The results revealed that the adsorption capacity of modified sand for Cd(II) was montmorillonite-coated sand>humic acid-coated sand>ferrihydrite-coated sand>quartz sand. While the increase of the coated sand content limited the transport ability of Cd(II) in sand columns. In addition, high IS and low pH promoted the mobility of Cd(II). The specific surface area, surface charge and adsorption sites of coated sand were the factors affecting the transport of Cd(II). This work provides new information on the transport and spread of Cd(II) in the soil and thus to better prevent Cd(II) from polluting the environment.

Phosphorylation of a chronic pain mutation in the voltage-gated sodium channel Nav1.7 increases voltage sensitivity

Mutations in voltage-gated sodium channels (Navs) can cause alterations in pain sensation, such as chronic pain diseases like inherited erythromelalgia. The mutation causing inherited erythromelalgia, Nav1.7 p.I848T, is known to induce a hyperpolarized shift in the voltage dependence of activation in Nav1.7. So far, however, the mechanism to explain this increase in voltage sensitivity remains unknown. In the present study, we show that phosphorylation of the newly introduced Thr residue explains the functional change. We expressed wildtype human Nav1.7, the I848T mutant, or other mutations in HEK293T cells and performed whole-cell patch-clamp electrophysiology. As the insertion of a Thr residue potentially creates a novel phosphorylation site for Ser/Thr kinases and because Nav1.7 had been shown in Xenopus oocytes to be affected by protein kinases C and A, we used different nonselective and selective kinase inhibitors and activators to test the effect of phosphorylation on Nav1.7 in a human system. We identify protein kinase C, but not protein kinase A, to be responsible for the phosphorylation of T848 and thereby for the shift in voltage sensitivity. Introducing a negatively charged amino acid instead of the putative phosphorylation site mimics the effect on voltage gating to a lesser extent. 3D modeling using the published cryo-EM structure of human Nav1.7 showed that introduction of this negatively charged site seems to alter the interaction of this residue with the surrounding amino acids and thus to influence channel function. These results could provide new opportunities for the development of novel treatment options for patients with chronic pain.

Copper bis(thiosemicarbazone) Complexes with Pendent Polyamines: Effects of Proton Relays and Charged Moieties on Electrocatalytic HER

AbstractA series of new bis(thiosemicarbazonato) Cu(II) complexes with pendent polyamines, diacetyl‐(N, ‐dimethylethylenediaminothiosemicarbazonato)‐(N’‐methyl‐3‐thio‐semicarbazonato)butane‐2,3‐diimine)‐copper(II) (Cu‐1), diacetyl‐bis(N‐dimethylethylenediamino‐3‐thiosemicarbazonato)butane‐2,3‐diimine)‐copper(II) (Cu‐3), and their cationic derivatives Cu‐2 and Cu‐4, have been synthesized and fully characterized by spectroscopic, electrochemical, and X‐ray diffraction methods. Complexes Cu‐1–Cu‐4 are analogues of Cu(ATSM), which contains a similar N2S2 donor core with terminal non‐coordinating amines. Substitution of the methyl group(s) of the terminal amines of H2ATSM with N,N‐dimethylethylenediamine followed by alkylation generates a charged quaternary amine in the ligand framework. The charged site tunes the redox potentials of the complexes with minimal changes in their physical and electronic properties. The HER activity of all four copper complexes were evaluated in acetonitrile with glacial acetic acid. All of the complexes have lower HER overpotentials than Cu(ATSM), which is attributed to charge effects. The pendent amines of Cu‐1 and Cu‐3 have the lowest HER overpotential as the pendent tertiary amine also serves as a proton relay to enhance proton rearrangement under catalytic conditions. Complex Cu‐3 showed the highest activity with a TOF of 12 × 103 s−1, an overpotential of 0.65 V, and faradaic efficiency of 100 %.

Synthesis, structure, Hirshfeld surface analysis and theoretical studies of 2-aminobenzo[d]thiazol-3-ium 4-aminobenzenesulfonate hydrate

Abstract Single crystals of 2-aminobenzo[d]thiazol-3-ium 4-aminobenzenesulfonate hydrate (ATASH) was grown by slow evaporation of a mixed solvent system ethanol-water (1:1, v/v) containing equimolar quantities of 4-aminobenzene-1-sulfonic acid and 2-aminobenzothiazole. The crystal structure was elucidated by single-crystal X-ray diffraction analysis and the crystal belongs to the monoclinic system with centric space group P21/c. The vibrational patterns of the title compound have been investigated by FT-IR spectroscopy. The band gap energy was estimated by the application of the Kubelka–Munk algorithm. The existence of N H•••O, O H•••O and π•••π staking interactions assists to attain the crystal cohesion. Factors associated with the size, shape, charge density distribution and site of chemical reactivity of the ATASH have been obtained by mapping electron density with electrostatic potential. The molecular surface and bonding interactions are analyzed by fingerprint plots via the Hirshfeld surface. Theoretical calculations were performed by the density functional theory method.

Heparan sulfate consumption as a potential mechanism of intra-cardiac thrombosis in SARS-CoV-2 infection

Cardiac injury occurs in up to 36% of hospitalized patients with COVID-19.1.Lala A. Johnson K.W. Januzzi J.L. et al.Prevalence and impact of myocardial injury in patients hospitalized with COVID-19 infection.J Am Coll Cardiol. 2020; 76 (533 LP - 546)https://doi.org/10.1016/j.jacc.2020.06.007Crossref Scopus (384) Google Scholar Exact mechanism of cardiac injury in COVID-19 is not well understood, but may relate to direct cardiomyocyte damage, coronary plaque destabilization, cytokine inflammatory response, and intracoronary microthrombi formation. Lindner et al.2.Lindner D. Fitzek A. Bräuninger H. et al.Association of cardiac infection with SARS-CoV-2 in confirmed COVID-19 autopsy cases.JAMA Cardiol. 2020; (Published online July 27)https://doi.org/10.1001/jamacardio.2020.3551Crossref PubMed Scopus (423) Google Scholar in an autopsy study identified SARS-CoV-2 RNA in the myocardium in 24 of 39 autopsy cases. However, none of the 39 patients had myocarditis. Plasma pro-inflammatory cytokine levels were increased in 16 patients, suggesting cytokine response as a plausible cause of cardiac injury in COVID-19. Early reports identified ACE2 as a receptor for the SARS-CoV-2. Clausen et al.3.Clausen T.M. Sandoval D.R. Spliid C.B. et al.SARS-CoV-2 infection depends on cellular heparan sulfate and ACE2.Cell. 2020; (Published online September 142020.07.14.201616)https://doi.org/10.1016/j.cell.2020.09.033Abstract Full Text Full Text PDF PubMed Scopus (531) Google Scholar have recently identified heparan sulfate as a co-receptor for ACE2, whereby SARS-CoV-2 binds to heparan sulfate, a negatively charged polymer, through a positively charged site adjacent to the ACE2 binding domain. Heparan sulfate is ubiquitously expressed in mammalian tissues, and ACE2 is broadly expressed in the arterial, capillary, and venous endothelial cells. Heparan sulfate also interacts with antithrombin, which subsequently undergoes conformation change, resulting in the generation of the active form of antithrombin. The active form of antithrombin inhibits the procoagulant factors Xa and thrombin (IIa) (Fig. 1). Additionally, Gue et al.4.Gue Y.X. Gorog D.A. Reduction in ACE2 may mediate the prothrombotic phenotype in COVID-19.Eur Heart J. 2020; 41: 3198-3199https://doi.org/10.1093/eurheartj/ehaa534Crossref PubMed Scopus (14) Google Scholar suggested that reduction in ACE2 activity may increase vascular permeability resulting in increased expression of tissue factor in subendothelial cells, leucocytes, and platelets with subsequent activation of coagulation and thrombosis. As SARS-CoV-2 binds heparan sulfate and ACE2 for cellular entry, it is possible that the high expression of ACE2 in the heart would facilitate an interaction between SARS-CoV-2 and heparan sulfate, leading to heparan sulfate consumption. A lower level of heparan sulfate would lead to a reduction in antithrombin activation creating a hypercoagulable state. Heparan sulfate also mediates antithrombin's anti-inflammatory activity.5.Liu J. Pedersen L.C. Anticoagulant heparan sulfate: structural specificity and biosynthesis.Appl Microbiol Biotechnol. 2007; 74: 263-272https://doi.org/10.1007/s00253-006-0722-xCrossref PubMed Scopus (108) Google Scholar Loss of antithrombin's anti-inflammatory activity can potentially lead to endothelialitis and subsequent endothelial injury and intra-cardiac thrombus formation. We believe that heparan sulfate consumption during SARS-CoV-2 cellular entry might play a role in the thrombotic events associated with COVID-19 infection.

Nitrogen-doped carbon-coated nanodiamonds for electrocatalytic applications

Nitrogen-doped carbon hybridized nanodiamond (N-doped C@ND) materials have been developed and used as an electrocatalytic for oxygen reduction reactions (ORRs). The polymerized ionic liquids are employed to modify NDs and then subjected to thermal annealing at 600 °C, resulting in a high concentration of N-doped (9.33 at.%) carbon frameworks attached on the ND surface. This N-doped C@ND material provides a highly active mesoporous structure (4 nm pore) with a high surface area (366 m2 g−1) and allows for enhancement of catalytic performance compared to pure NDs. The N-doped C layers altered the electroneutrality of NDs, creating favourable charged sites for oxygen adsorption, thus weakening the O–O bond strength to facilitate ORR activity. Having a predominant four-electron transfer pathway with a total electron transfer number of 3.44–3.88 in the potential region of 0.1–0.8 VRHF, the N-doped C@ND-based catalyst materials performed well as a catalyst for the ORR in the alkaline medium. This affordable material and simple process will find potential application in clean energy generation and storage, durable fuel cells and metal–air batteries.