Raman spectroscopy of holey nanographene C216

We report a detailed investigation by Raman spectroscopy of the holey nanographene C216, a hexagon-shaped disk with armchair edges (1.4 nm long), from which the central aromatic ring is missing. Density functional theory (DFT) calculations allow to assign the main features of the Raman spectra that have been recorded with several excitation wavelengths. In the Raman spectra, we observe signatures of the hole in the structure, several G and D modes, as well as their overtones and combinations-up to third order

Distribution of genes encoding resistance to macrolides, lincosamides, and streptogramins among methicillin-resistant Staphylococcus aureus strains isolated from burn patients

The increasing resistance to macrolide, lincosamide, and streptogramin B agents among methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem for the health community. This study aimed to investigate the prevalence of ermA, ermB, ermC, and msrA in MRSA strains isolated from burn patients in Ahvaz, southwest of Iran. A total of 76 isolates of S. aureus were collected from January to May 2017 from Taleghani Burn Hospital in Ahvaz. Among 76 S. aureus strains collected, 60 (78.9%) isolates were MRSA. The antimicrobial susceptibility testing for MRSA showed extreme high resistance rate to clarithromycin (100%) and azithromycin (100%), followed by erythromycin (98.3%). The PCR assay revealed that the frequency rates of msrA, ermA, and ermC genes were 23 (38.3%), 28 (46.7%), and 22 (36.7%), respectively. In addition, none of the MRSA isolates had the ermB gene. Because of the high prevalence of macrolide and lincosamide resistance found in MRSA isolates from infections of burn patients in Ahvaz, southwest of Iran, it is recommended that local periodic survey be performed for controlling the dissemination of antimicrobial resistance

Hexa-peri-benzocoronene with two extra K-regions in an ortho-configuration

There are three possible isomers for hexa-peri-hexabenzocoronene (HBC) with two extra K-regions, but only two of them have been reported, namely with the meta- and para-configurations. Herein, we describe the synthesis of HBC 4 with two extra K-regions in the ortho-configuration, forming a longer zigzag edge compared with the other two isomers. The structure of 4 was validated by laser desorption/ionization time-of-flight mass analysis and nuclear magnetic resonance spectra, as well as Raman and infrared spectroscopies supported by density functional theory calculations. The optical properties of 4 were investigated by UV/vis absorption and ultrafast transient absorption spectroscopy. Together with the analysis of aromaticity, the influence of the zigzag edge on the π-conjugation pathway and HOMO-LUMO gaps of the three isomers were investigated

Edge chlorination of hexa-peri-hexabenzocoronene investigated by density functional theory and vibrational spectroscopy

open7noWe investigate the molecular structure and vibrational properties of perchlorinated hexa-peri-hexabenzocoronene (HBC-Cl) by density functional theory (DFT) calculations and IR and Raman spectroscopy, in comparison to the parent HBC. The theoretical and experimental IR and Raman spectra demonstrated very good agreement, elucidating a number of vibrational modes corresponding to the observed peaks. Compared with the parent HBC, the edge chlorination significantly alters the planarity of the molecule. Nevertheless, the results indicated that such structural distortion does not significantly impair the π-conjugation of such polycyclic aromatic hydrocarbons.openMaghsoumi, Ali; Narita, Akimitsu; Dong, Renhao; Feng,  xinliang; Castiglioni, Chiara; Müllen, Klaus; Tommasini, MatteoMaghsoumi, Ali; Narita, Akimitsu; Dong, Renhao; Feng,  xinliang; Castiglioni, Chiara; Müllen, Klaus; Tommasini, MATTEO MARIA SAVERI

The effects of salinity stress on the growth and some physiological parameters of wheat (Triticum aestivum L.) seedlings

Salinity is one of the major abiotic stresses that adversely affects crop productivity and quality. In this study, an experiment was conducted to investigate the effects of salinity stress on some physiological parameters of wheat seedlings. Plants were subjected to three salt treatment i.e. 0 (control), 100, 150 mM NaCl under controlled conditions. Results showed that increasing salinity caused significant decrease in shoot and root length and dry weight and leaf area, but in contrast, malondialdehyde (MDA) content and catalase (CAT) and guaiacol peroxidase (GPX) activity were increased. Also, increasing salinity significantly decreased K+ and NO3- and significantly increased Na+ and Cl- content

Raman spectroscopy of holey nanographene C216

We report a detailed investigation by Raman spectroscopy of the holey nanographene C216, a hexagon-shaped disk with armchair edges (1.4 nm long), from which the central aromatic ring is missing. Density functional theory (DFT) calculations allow to assign the main features of the Raman spectra that have been recorded with several excitation wavelengths. In the Raman spectra, we observe signatures of the hole in the structure, several G and D modes, as well as their overtones and combinations—up to third order

How does cobalt phosphate modify the structure of TiO2 nanotube array photoanodes for solar water splitting?

TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 min. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 min, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) results, by depositing the electrocatalyst, nanotube walls have been spread and holes have been covered by CoPi. Correlation between observed change in surface morphology and Raman spectra of the samples along with electrocatalytic tests revealed how decoration time can influence structural properties and photoelectrochemical performance of the final CoPi/TNA photoanodes in solar water splitting system