Surface Functionalization of g‐C3N4: Molecular‐Level Design of Noble‐Metal‐Free Hydrogen Evolution Photocatalysts

A stable noble‐metal‐free hydrogen evolution photocatalyst based on graphite carbon nitride (g‐C₃N₄) was developed by a molecular‐level design strategy. Surface functionalization was successfully conducted to introduce a single nickel active site onto the surface of the semiconducting g‐C₃N₄. This catalyst family (with less than 0.1 wt % of Ni) has been found to produce hydrogen with a rate near to the value obtained by using 3 wt % platinum as co‐catalyst. This new catalyst also exhibits very good stability under hydrogen evolution conditions, without any evidence of deactivation after 24 h.     

Spectrophotometric Determination of 8-Hydroxyquinoline (Oxine) in Aqueous Solution by Azo Dye Formation with Diazotized p-Aminoacetophenone

Abstract

A sensitive spectrophotometric method for the determination of oxine in aqueous solution is investigated. It is based on the reaction of the analyte with diazotized p-aminoacetophenone to form, in the presence of sodium hydroxide, an intense cherry-red water-soluble and stable azo dye which shows maximum absorption at 520 nm. The linear absorbance plot with the concentration indicates that Beer's law is adhered over the range 10–100μg of oxine in a final volume of 25 ml, i.e., 0.4–4 ppm, with a molar absorptivity of 3.37 × 10⁴ 1mol^?1 cm^?1, a relative error of +0.44 to –1.12%, and a relative standard deviation of 0.54–2.9%, depending on the level of analyte concentration. The optimum conditions affecting the color reaction and interference due to foreign organic compounds have been examined.     

A STUDY OF A FULLY COUPLED TWO-PARAMETER SYSTEM OF SEQUENTIAL FRACTIONAL INTEGRO-DIFFERENTIAL EQUATIONS WITH NONLOCAL INTEGRO-MULTIPOINT BOUNDARY CONDITIONS

In this article, we discuss the existence and uniqueness of solutions for a coupled two-parameter system of sequential fractional integro-differential equations supplemented with nonlocal integro-multipoint boundary conditions. The standard tools of the fixed-point theory are employed to obtain the main results. We emphasize that our results are not only new in the given configuration, but also correspond to several new special cases for specific values of the parameters involved in the problem at hand.     

Ginger Essential Oils-Loaded Nanoemulsions: Potential Strategy to Manage Bacterial Leaf Blight Disease and Enhanced Rice Yield

The bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious rice diseases, causing huge yield losses worldwide. Several technologies and approaches have been opted to reduce the damage; however, these have had limited success. Recently, scientists have been focusing their efforts on developing efficient and environmentally friendly nanobactericides for controlling bacterial diseases in rice fields. In the present study, a scanning electron microscope (SEM), transmission electron microscope (TEM), and a confocal laser scanning microscope (CLSM) were utilized to investigate the mode of actions of ginger EOs on the cell structure of Xoo. The ginger EOs caused the cells to grow abnormally, resulting in an irregular form with hollow layers, whereas the dimethylsulfoxide (DMSO) treatment showed a typical rod shape for the Xoo cell. Ginger EOs restricted the growth and production of biofilms by reducing the number of biofilms generated as indicated by CLSM. Due to the instability, poor solubility, and durability of ginger EOs, a nanoemulsions approach was used, and a glasshouse trial was performed to assess their efficacy on BLB disease control. The in vitro antibacterial activity of the developed nanobactericides was promising at different concentration (50–125 µL/mL) tested. The efficacy was concentration-dependent. There was significant antibacterial activity recorded at higher concentrations. A glasshouse trial revealed that developed nanobactericides managed to suppress BLB disease severity effectively. Treatment at a concentration of 125 μL/mL was the best based on the suppression of disease severity index, AUDPC value, disease reduction (DR), and protection index (PI). Furthermore, findings on plant growth, physiological features, and yield parameters were significantly enhanced compared to the positive control treatment. In conclusion, the results indicated that ginger essential oils loaded-nanoemulsions are a promising alternative to synthetic antibiotics in suppressing Xoo growth, regulating the BLB disease, and enhancing rice yield under a glasshouse trial.     

Supramolecular Chemistry: Host–Guest Molecular Complexes

In recent times, researchers have emphasized practical approaches for capturing coordinated and selective guest entrap. The physisorbed nanoporous supramolecular complexes have been widely used to restrain various guest species on compact supporting surfaces. The host–guest (HG) interactions in two-dimensional (2D) permeable porous linkages are growing expeditiously due to their future applications in biocatalysis, separation technology, or nanoscale patterning. The different crystal-like nanoporous network has been acquired to enclose and trap guest molecules of various dimensions and contours. The host centers have been lumped together via noncovalent interactions (such as hydrogen bonds, van der Waals (vdW) interactions, or coordinate bonds). In this review article, we enlighten and elucidate recent progress in HG chemistry, explored via scanning tunneling microscopy (STM). We summarize the synthesis, design, and characterization of typical HG structural design examined on various substrates, under ambient surroundings at the liquid-solid (LS) interface, or during ultrahigh vacuum (UHV). We emphasize isoreticular complexes, vibrant HG coordination, or hosts functional cavities responsive to the applied stimulus. Finally, we critically discuss the significant challenges in advancing this developing electrochemical field.     

In situ green synthesis of biocompatible ginseng capped gold nanoparticles with remarkable stability

We report herein an unprecedented one-step green synthesis of gold nanoparticles (G-AuNps), using naturally occurring Korean red ginseng root (Panax ginseng C.A. Meyer) without any special reducing/capping agents. The AuNps generated through this ginseng-mediated process did not aggregate suggesting that the phytochemicals present in them serve as excellent coatings on the nanoparticles and thus, provide robust shielding from aggregations. The ginseng-generated AuNps exhibit remarkable in vitro stability in various buffers including: cysteine, histidine, saline, sodium chloride and a host of pH ranges. Furthermore, the phytochemical coatings on the G-AuNps rendered them nontoxic as demonstrated through detailed cytotoxicity assays using WST-8 counting kit, performed on normal cervical cells lines. The present study opens up a new possibility of conveniently synthesizing AuNps using natural products which will be useful in optoelectronic and biomedical applications.     

Simple zeropotent paramedial groupoids are balanced

This short note is a continuation of [1] and [2] and its purpose is to show that every simple zeropotent paramedial groupoid containing at least three elements is strongly balanced in the sense of [4].     

Electrical detection of germination of viable model Bacillus anthracis spores in microfluidic biochips

In this paper, we present a new impedance-based method to detect viable spores by electrically detecting their germination in real time within microfluidic biochips. We used Bacillus anthracis Sterne spores as the model organism. During germination, the spores release polar and ionic chemicals, such as dipicolinic acid (DPA), calcium ions, phosphate ions, and amino acids, which correspondingly increase the electrical conductivity of the medium in which the spores are suspended. We first present macro-scale measurements demonstrating that the germination of spores can be electrically detected at a concentration of 10(9) spores ml(-1) in sample volumes of 5 ml, by monitoring changes in the solution conductivity. Germination was induced by introducing an optimized germinant solution consisting of 10 mM L-alanine and 2 mM inosine. We then translated these results to a micro-fluidic biochip, which was a three-layer device: one layer of polydimethylsiloxane (PDMS) with valves, a second layer of PDMS with micro-fluidic channels and chambers, and the third layer with metal electrodes deposited on a pyrex substrate. Dielectrophoresis (DEP) was used to trap and concentrate the spores at the electrodes with greater than 90% efficiency, at a solution flow rate of 0.2 microl min(-1) with concentration factors between 107-109 spores ml(-1), from sample volumes of 1-5 microl. The spores were captured by DEP in deionized water within 1 min (total volume used ranged from 0.02 microl to 0.2 microl), and then germinant solution was introduced to the flow stream. The detection sensitivity was demonstrated to be as low as about a hundred spores in 0.1 nl, which is equivalent to a macroscale detection limit of approximately 10(9) spores ml(-1). We believe that this is the first demonstration of this application in microfluidic and BioMEMS devices.