From Permeation to Cluster Arrays: Graphene on Ir(111) Exposed to Carbon Vapor.

Our scanning tunneling microscopy and X-ray photoelectron spectroscopy experiments along with first-principles calculations uncover the rich phenomenology and enable a coherent understanding of carbon vapor interaction with graphene on Ir(111). At high temperatures, carbon vapor not only permeates to the metal surface but also densifies the graphene cover. Thereby, in addition to underlayer graphene growth, upon cool down also severe wrinkling of the densified graphene cover is observed. In contrast, at low temperatures the adsorbed carbon largely remains on top and self-organizes into a regular array of fullerene-like, thermally highly stable clusters that are covalently bonded to the underlying graphene sheet. Thus, a new type of predominantly sp2-hybridized nanostructured and ultrathin carbon material emerges, which may be useful to encage or stably bind metal in finely dispersed form.

Molecular modeling of some commercially available antiviral drugs and their derivatives against SARS-CoV-2 infection.

Numerous prior studies have identified therapeutic targets that could effectively combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, including the angiotensin-converting enzyme 2 (ACE2) receptor, RNA-dependent RNA polymerase (RdRp), and Main protease (Mpro). In parallel, antiviral compounds like abacavir, acyclovir, adefovir, amantadine, amprenavir, darunavir, didanosine, oseltamivir, penciclovir, and tenofovir are under investigation for their potential in drug repurposing to address this infection. The aim of the study was to determine the effect of modifying the functional groups of the aforementioned antivirals in silico. Using the genetic optimization for ligand docking algorithm on software Maestro (version 11.1), the modified antivirals were docked onto ACE2 receptor, RdRp, and Mpro. Using QuickProp (Maestro v11.1), PASS (prediction of activity spectra for the substances), and altogether with SwissADME, the ADMET (absorption, distribution, metabolism, excretion, and toxicity) of the modified antivirals, as well as their bioavailability and the predicted activity spectra, were determined. Discovery studio software was used to undertake post-docking analysis. Among the 10 antivirals, N(CH3)2 derivative of darunavir, N(CH3)2 derivative of amprenavir and NCH3 derivative of darunavir exhibited best binding affinities with ACE2 receptor (docking scores: -10.333, -9.527 and -9.695 kJ/mol, respectively). Moreover, NCH3 derivative of abacavir (-6.506 kJ/mol), NO2 derivative of didanosine (-6.877 kJ/mol), NCH3 derivative of darunavir (-7.618 kJ/mol) exerted promising affinity to Mpro. In conclusion, the results of the in silico screenings can serve as a useful information for future experimental works.

Serum melatonin level in ankylosing spondylitis: is it increased in active disease?

In the recent years, the role of melatonin (MLT) in the pathogenesis of inflammatory arthritis has been investigated, and the serum levels of MLT have been evaluated, but clinical study concerning MLT and ankylosing spondylitis (AS) is little reported in literature. We aimed to investigate the serum levels of MLT and their relation with the disease activity parameters of patients with AS. Forty AS patients and 40 healthy controls (matched for age and sex with the patients) participated in this study. Demographic and clinical data were collected and assessed. Disease activity of AS patients was assessed clinically according to the Bath AS Disease Activity Index (BASDAI), while AS functional impairment was assessed using the Bath AS Functional Index (BASFI). Serum samples were collected from all subjects to evaluate serum MLT, ESR, and CRP. Serum MLT levels were significantly increased in AS patients as compared to healthy controls (95% CI: 4.63, 8.77, P < 0.001). ESR and CRP are significantly higher in the AS patients compared with the controls (P < 0.001). AS patients with active disease had significantly higher ESR (P = 0.0151), CRP (P = 0.0124), and BASFI (P = 0.0016). Also, the MLT serum level in AS patients with BASDAI ≥40 was 39.7 ± 6.2 pg/ml compared with 35.2 ± 3.5 pg/ml in AS patients with BASDAI <40 (95% CI: 1.22, 7.78, P = 0.0106). Also, serum MLT level was significantly higher in the AS patients with enthesopathy than those without enthesopathy. Serum MLT levels were correlated with the duration of morning stiffness, BASDAI, BASFI, and CRP but not with ESR or duration of the disease. Serum levels of MLT were significantly increased in AS patients as compared to healthy controls. MLT levels correlated positively with BASDAI, BASFI, duration of morning stiffness, and CRP levels. Thus, it seems that MLT levels reflect the disease activity in AS patients.

Water Chemistry beneath Graphene: Condensation of a Dense OH-H2O Phase under Graphene.

Room temperature oxygen hydrogenation below graphene flakes supported by Ir(111) is investigated through a combination of X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations using an evolutionary search algorithm. We demonstrate how the graphene cover and its doping level can be used to trap and characterize dense mixed O-OH-H2O phases that otherwise would not exist. Our study of these graphene-stabilized phases and their response to oxygen or hydrogen exposure reveals that additional oxygen can be dissolved into them at room temperature creating mixed O-OH-H2O phases with an increased areal coverage underneath graphene. In contrast, additional hydrogen exposure converts the mixed O-OH-H2O phases back to pure OH-H2O with a reduced areal coverage underneath graphene.

In Silico Screening of Natural Products as Potential Inhibitors of SARS-CoV-2 Using Molecular Docking Simulation.

OBJECTIVE: To explore potential natural products against severe acute respiratory syndrome coronavirus (SARS-CoV-2) via the study of structural and non-structural proteins of human coronaviruses. METHODS: In this study, we performed an in-silico survey of 25 potential natural compounds acting against SARS-CoV-2. Molecular docking studies were carried out using compounds against 3-chymotrypsin-like protease (3CLPRO), papain-like protease (PLPRO), RNA-dependent RNA polymerase (RdRp), non-structural protein (nsp), human angiotensin converting enzyme 2 receptor (hACE2R), spike glycoprotein (S protein), abelson murine leukemia viral oncogene homolog 1 (ABL1), calcineurin-nuclear factor of activated T-cells (NFAT) and transmembrane protease serine 2. RESULTS: Among the screened compounds, amentoflavone showed the best binding affinity with the 3CLPRO, RdRp, nsp13, nsp15, hACE2R. ABL1 and calcineurin-NFAT; berbamine with hACE2R and ABL1; cepharanthine with nsp10, nsp14, nsp16, S protein and ABL1; glucogallin with nsp15; and papyriflavonol A with PLPRO protein. Other good interacting compounds were juglanin, betulinic acid, betulonic acid, broussooflavan A, tomentin A, B and E, 7-methoxycryptopleurine, aloe emodin, quercetin, tanshinone I, tylophorine and furruginol, which also showed excellent binding affinity towards a number of target proteins. Most of these compounds showed better binding affinities towards the target proteins than the standard drugs used in this study. CONCLUSION: Natural products or their derivatives may be one of the potential targets to fight against SARS-CoV-2.

Antidiarrheal, antimicrobial and antioxidant potentials of methanol extract of Colocasia gigantea Hook. f. leaves: evidenced from in vivo and in vitro studies along with computer-aided approaches.

BACKGROUND: Colocasia gigantea, locally named as kochu is well-known due to its various healing power. This research is to investigate the antidiarrheal, antimicrobial and antioxidant possibilities of the methanol soluble extract of Colocasia gigantea. METHODS: The antidiarrheal investigation was performed by using in vivo castor oil-induced diarrheal method whereas in vitro antimicrobial and antioxidant investigation have been implemented by disc diffusion and DPPH scavenging method respectively. Moreover, in silico studies were followed by molecular docking analysis of several secondary metabolites that were appraised with Schrödinger-Maestro v11.1 and Biovia Discovery Studio. RESULTS: The induction of plant extract (200 and 400 mg/kg, b.w, p.o) has minimized the castor oil mediated diarrhea by 16.96% (p < 0.01) and 38.89% (p < 0.001) respectively compared to control group. The methanol extract of C. gigantea showed mild sensitivity against almost all the tested strains but it shows high consistency of phenolic content and yielded 67.68 µg/mL of IC50 value in the DPPH test. In the PASS prediction, selected isolated compounds have demonstrated significant antidiarrheal and antimicrobial activity following the Lipinski drug rules which have ascertained efficacy with the compounds in molecular docking study. CONCLUSION: The results of this scientific research reflects that the methanol soluble extract of C. gigantea is safe and may provide possibilities of alleviation of diarrhea along with being a potential wellspring of antioxidant and antimicrobial agents which can be considered as an alternate source for exploration of new medicinal products in near future.

Unveiling pharmacological studies provide new insights on Mangifera longipes and Quercus gomeziana.

Mangifera longipes and Quercus gomeziana both is an ethnomedicinally important Asian herb that has been known for numerous healing activity of tribal people. The present research aims to investigate the phytochemical analysis with in vitro, in vivo possibilities of the soluble ethanol extract of M. longipes root (EEMLR) and Q. gomeziana leaves (EEQGL) by an experimental approach. The plant extract of EEMLR and EEQGL was found secondary metabolites, notably steroids, glycosides, tannins, flavonoids, saponins, gums, and alkaloids. Additionally, the extract showed significant activity in antioxidant, antipyretic, anti-inflammatory, membrane stabilization, cytotoxic, thrombolytic, and analgesic activities while no response in antibacterial activity. Our findings reveal that soluble ethanol extract of EEMLR and EEQGL is safe, which can be an effective source for exploring new medicinal products. This research's outcomes may provide potentials for mitigating pyrexia, inflammation, pain, cellular toxicity, and coagulation.

Pharmacological insights and prediction of lead bioactive isolates of Dita bark through experimental and computer-aided mechanism.

Dita bark (Alstonia scholaris (L.) R. Br.) is an ethnomedicine used for the management of various ailments. This study aimed to investigate the biological properties of methanol extract of A. scholaris bark (MEAS), through in vivo, in vitro and in silico approaches alongside its phytochemical profiling. Identification and nature of the bioactive secondary metabolites were studied by the established qualitative tests and GC-MS analysis. The antidepressant activity was determined by forced swimming test (FST) and tail suspension test (TST) in mice. The anti-inflammatory and thrombolytic effect was evaluated using inhibition of protein denaturation technique and clot lysis technique, respectively. Besides, computational studies of the isolated compounds and ADME/T analysis were performed by Schrödinger-Maestro (v11.1) software, and PASS prediction was conducted through PASS online tools. The GC-MS analysis revealed the presence of several secondary metabolites in MEAS. Treatment with MEAS revealed a significant reduction of immobility time in a dose-dependent manner in FST and TST. Besides, MEAS showed substantial anti-inflammatory effects at the higher dose (400 µg/mL) as well as revealed notable clot lysis effect as compared to control. In the case of computer-aided investigation, all compounds meet the condition of Lipinski's rule of five. PASS study also predicted for all compounds, and among these safe compound furazan-3-amine showed the most spontaneous binding energy for both antidepressant and thrombolytic activities, as well as 5-dimethylamino-6 azauracil, found promising for anti-inflammatory activity. Taken together, the investigation concludes that MEAS can be a potent source of antidepressant, anti-inflammatory, and thrombolytic agents.

Formation and Nature of Carbon-Containing Tribofilms.

Minimizing friction and wear at a rubbing interface continues to be a challenge and has resulted in the recent surge toward the use of coatings such as diamond-like carbon (DLC) on machine components. The problem with the coating approach is the limitation of coating wear life. Here, we report a lubrication approach in which lubricious, wear-protective carbon-containing tribofilms can be self-generated and replenishable, without any surface pretreatment. Such carbon-containing films were formed under modest sliding conditions in a lubricant consisting of cyclopropanecarboxylic acid as an additive dissolved in polyalphaolefin base oil. These tribofilms show the same Raman D and G signatures that have been interpreted to be due to the presence of graphite- or DLC films. Our experimental measurements and reactive molecular dynamics simulations demonstrate that these tribofilms are in fact high-molecular weight hydrocarbons acting as a solid lubricant.

Exciting H2 Molecules for Graphene Functionalization.

Hydrogen functionalization of graphene by exposure to vibrationally excited H2 molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H2 molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H2 dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H-H bond. The first reacting H2 molecule must contain considerable vibrational energy to overcome the dissociative adsorption barrier. However, this initial adsorption further activates the surface resulting in reduced barriers for dissociative adsorption of subsequent H2 molecules. This enables functionalization by H2 molecules with lower vibrational energy, yielding an avalanche effect for the hydrogenation reaction. These results provide an example of a catalytically active graphene-coated surface and additionally set the stage for a re-interpretation of previous experimental work involving elevated H2 background gas pressures in the presence of hot filaments.

Symmetry-Driven Band Gap Engineering in Hydrogen Functionalized Graphene.

Band gap engineering in hydrogen functionalized graphene is demonstrated by changing the symmetry of the functionalization structures. Small differences in hydrogen adsorbate binding energies on graphene on Ir(111) allow tailoring of highly periodic functionalization structures favoring one distinct region of the moiré supercell. Scanning tunneling microscopy and X-ray photoelectron spectroscopy measurements show that a highly periodic hydrogen functionalized graphene sheet can thus be prepared by controlling the sample temperature (Ts) during hydrogen functionalization. At deposition temperatures of Ts = 645 K and above, hydrogen adsorbs exclusively on the HCP regions of the graphene/Ir(111) moiré structure. This finding is rationalized in terms of a slight preference for hydrogen clusters in the HCP regions over the FCC regions, as found by density functional theory calculations. Angle-resolved photoemission spectroscopy measurements demonstrate that the preferential functionalization of just one region of the moiré supercell results in a band gap opening with very limited associated band broadening. Thus, hydrogenation at elevated sample temperatures provides a pathway to efficient band gap engineering in graphene via the selective functionalization of specific regions of the moiré structure.

Interface controlled oxidation states in layered cobalt oxide nanoislands on gold.

Layered cobalt oxides have been shown to be highly active catalysts for the oxygen evolution reaction (OER; half of the catalytic "water splitting" reaction), particularly when promoted with gold. However, the surface chemistry of cobalt oxides and in particular the nature of the synergistic effect of gold contact are only understood on a rudimentary level, which at present prevents further exploration. We have synthesized a model system of flat, layered cobalt oxide nanoislands supported on a single crystal gold (111) substrate. By using a combination of atom-resolved scanning tunneling microscopy, X-ray photoelectron and absorption spectroscopies and density functional theory calculations, we provide a detailed analysis of the relationship between the atomic-scale structure of the nanoislands, Co oxidation states and substrate induced charge transfer effects in response to the synthesis oxygen pressure. We reveal that conversion from Co(2+) to Co(3+) can occur by a facile incorporation of oxygen at the interface between the nanoisland and gold, changing the islands from a Co-O bilayer to an O-Co-O trilayer. The O-Co-O trilayer islands have the structure of a single layer of ß-CoOOH, proposed to be the active phase for the OER, making this system a valuable model in understanding of the active sites for OER. The Co oxides adopt related island morphologies without significant structural reorganization, and our results directly demonstrate that nanosized Co oxide islands have a much higher structural flexibility than could be predicted from bulk properties. Furthermore, it is clear that the gold/nanoparticle interface has a profound effect on the structure of the nanoislands, suggesting a possible promotion mechanism.

Serum leptin in Egyptian patients with fibromyalgia syndrome: relation to disease severity.

AIM: Recently, a large body of studies has focused on the leptin levels in psychiatric disorders. This study aimed to measure serum leptin levels in fibromyalgia syndrome (FMS) due to a significantly higher prevalence of psychiatric disorder and to determine the relationship between leptin and FMS. METHODS: The present study was a cross-sectional descriptive study. Fifty FMS female patients and 50 healthy females serving as a control group were included. Serum samples tested for serum leptin levels were determined by a specific enzyme-linked immunosorbent assay (ELISA). RESULTS: Serum leptin levels were significantly lower in FMS patients compared to the control group. The mean serum leptin in patients with FMS was 7.1 ± 6.8 ng/mL compared to 9.4 ± 4.5 ng/mL in the controls (mean difference, -2.48, 95% CI: -4.78, -0.18, P = 0.035). Serum leptin level is inversely correlated with visual analogue scale (VAS) of pain (P = 0.016), VAS of fatigue (P = 0.002), VAS of global severity (P = 0.011), VAS of anxiety (P = 0.027), global self-rating index (P = 0.020), Health Assessment Questionnaire score (P = 0.016), fibromyalgia impact questionnaire (FIQ) (P = 0.025), Beck Depression Inventory (P = 0.002), tender points (TPs) count (P = 0.041), TPs score (P = 0.015), and Pittsburg Sleep Quality Index (P = 0.006). Mean serum leptin levels were also significantly lower in FMS patients with post-exertion pain (P = 0.010), depression (P = 0.029), mood disturbance (P = 0.018), anxiety (P = 0.030), short memory difficulties (P = 0.017), sleep disturbance (P = 0.028), restless leg syndrome (P = 0.016), temperomandibular joint syndrome affection (P = 0.043), palpitation (P = 0.022), and irritable bowel syndrome (P = 0.028) than those without. CONCLUSION: We found a significant decrease in serum leptin in FMS patients compared to controls and this decrease correlated with disease severity.

Hepatitis C virus genotype distribution in Egyptian diabetic patients: a preliminary study.

BACKGROUND AND STUDY AIMS: There is controversy regarding whether a specific hepatitis C virus (HCV) genotype is associated with diabetes mellitus. This study aimed to investigate HCV genotype distribution in diabetics and its relation to some clinical and laboratory variables in HCV-positive diabetic versus non-diabetic Egyptians in East Delta. PATIENTS AND METHODS: The study included 100 HCV-positive patients of which 66 were diabetic in addition to 35 healthy adults as a control group. Clinical assessment, laboratory measurements of plasma glucose, insulin, C-peptide, C-reactive protein (CRP), tumour necrosis factor-α (TNF-α) and liver functions (alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT)) as well as HCV genotype determination were done, and AST/platelet ratio index (APRI) and Homoeostasis Model of Assessment-Insulin Resistance (HOMA-IR) were calculated. RESULTS: The main results were the presence of HCV genotype 3, in 31.8% of the diabetic group and in 26.5% of the non-diabetic group, while the remainder of cases had genotype 4, the predominant genotype in Egypt. This is the first report of the presence of HCV genotype 3 in about 30% of an Egyptian cohort. However, there was no significant difference in genotype distribution between both groups. Further, there were significantly higher values of HOMA-IR, insulin and C-peptide in HCV-positive groups in comparison to the control group, while TNF-α was significantly higher in the HCV-positive diabetic group. However, there were no significant differences between both genotypes regarding these parameters. CONCLUSION: Although this study reveals for the first time the presence of HCV genotype 3 in a significant percentage of a group of Egyptian patients, where the majority were diabetic, the association between diabetes and certain HCV genotypes could not be confirmed on the basis of our findings. Hence, taking into consideration the impact of such a finding on the treatment decisions of those patients, further studies are warranted to explore these findings to a greater extent.

Oxygen intercalation under graphene on Ir(111): energetics, kinetics, and the role of graphene edges.

Using X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM) we resolve the temperature-, time-, and flake size-dependent intercalation phases of oxygen underneath graphene on Ir(111) formed upon exposure to molecular oxygen. Through the applied pressure of molecular oxygen the atomic oxygen created on the bare Ir terraces is driven underneath graphene flakes. The importance of substrate steps and of the unbinding of graphene flake edges from the substrate for the intercalation is identified. With the use of CO titration to selectively remove oxygen from the bare Ir terraces the energetics of intercalation is uncovered. Cluster decoration techniques are used as an efficient tool to visualize intercalation processes in real space.