The Influence of LightPath Length on the Color of Flame-Fusion Synthetic Ruby

Colorimetric studies of different light path lengths from a new perspective of UV-Vis spectroscopy. The corrected ultraviolet-visible light spectrum was used to calculate the color of flame-fusion synthetic ruby, and the influence of light path length and standard light source on the color of flame-fusion synthetic ruby was studied. The results show that the L*, C*, h° under the A light source are higher than those under the D65 light source. In the ultraviolet-visible light spectrum, the strong absorption band of Cr3+ at 545nm is the main cause of the color of the ruby. As the length of the light path increases, the absorption peak area at 545nm also increases, the lightness L* decreases, and the hue angle h° increases. The chroma C* first increases as the length of the light path increases, and then begins to decrease under the influence of the continuous decrease in lightness. The color difference ΔE*ab reaches the maximum when the light path length is around 10mm, and the standard light source has the greatest influence on the color difference ΔE*ab. As the length of the light path continues to increase, the influence of the standard light source on the color difference\(\)ΔE*ab decreases.

Microstructure and Optical Properties of Nanostructural Thin Films Fabricated through Oxidation of Au–Sn Intermetallic Compounds

AuSn and AuSn2 thin films (5 nm) were used as precursors during the formation of semiconducting metal oxide nanostructures on a silicon substrate. The nanoparticles were produced in the processes of annealing and oxidation of gold–tin intermetallic compounds under ultra-high vacuum conditions. The formation process and morphology of a mixture of SnO2 and Au@SnOx (the core–shell structure) nanoparticles or Au nanocrystalites were carefully examined by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy (EDX). The annealing and oxidation of the thin film of the AuSn intermetallic compound led to the formation of uniformly distributed structures with a size of ∼20–30 nm. All of the synthesized nanoparticles exhibited a strong absorption band at 520–530 nm, which is typical for pure metallic or metal oxide systems.

Methanogenesis Potentials: Insights from Mineralogical Diagenesis, SEM and FTIR Features of the Permian Mikambeni Shale of the Tuli Basin, Limpopo Province of South Africa

Carbonaceous shale is more topical than ever before due to the associated unconventional resources of methane. The use of FTIR, SEM-EDX, and mineralogical analyses has demonstrated a promising approach to assess methanogenesis potentials in a more rapid and reliable manner for preliminary prospecting. Representative core samples from the borehole that penetrated the carbonaceous Mikambeni shale Formations were investigated for methanogenesis potentials. The absorption band stretches from 1650 cm−1 to 1220 cm−1 in wavenumber, corresponding to C-O stretching and OH deformation of acetic and phenolic groups in all studied samples, thereby suggesting biogenic methanogenesis. The CO2 was produced by decarboxylation of organic matter around 2000 cm−1 and 2300 cm−1 and served as a source of the carboxylic acid that dissolved the feldspar. This dissolution process tended to release K+ ions, which facilitated the illitization of the smectite minerals. The SEM-EDX spectroscopy depicted a polyframboidal pyrite structure, which indicated a sulfate reduction of pyrite minerals resulting from microbial activities in an anoxic milieu and causes an increase in alkalinity medium that favors precipitation of dolomite in the presence of Ca and Mg as burial depth increases. The contact diagenesis from the proximity of Sagole geothermal spring via Tshipise fault is suggested to have enhanced the transformation of smectite to chlorite via a mixed layer corrensite in a solid-state gradual replacement reaction pathway. The presence of diagenetic chlorite mineral is characteristic of low-grade metamorphism or high diagenetic zone at a temperature around 200 °C to 230 °C and corresponds to thermal breakdown of kerogen to methane at strong absorption band around 2850 cm−1 and 3000 cm−1, indicating thermal methanogenesis.

Effect of Gold Nanoparticles on Optoelectronic Properties of Thermally Reduced Graphene Oxide

Gold nanoparticles (AuNPs)-decorated reduced graphene oxide (rGO) is a compelling material from both aspects of processing and functionality. This paper presents an alternative method to prepare and alter the optoelectronic properties of the AuNPs-rGO hybrid film. Au was sputtered for a duration of 0–60 s on graphene oxide (GO) film before subjected to thermal reduction at 700∘C. The surface of rGO was decorated by spherical AuNPs with a mean particle size of around 10[Formula: see text]nm due to the solid-state dewetting process. The surface plasmon resonance (SPR) of AuNPs around 550[Formula: see text]nm was intense when the Au sputter duration exceeded 20[Formula: see text]s. Remarkably, the AuNPs layer retarded the de-oxygenation of GO during thermal annealing. The AuNPs-rGO hybrid film with long-duration Au sputtering exhibited low optical constants and thicker rGO film. The AuNPs also played the role in lowering the bandgap, increasing the lattice disorder and assisting the high-energy photon absorption in the thermally reduced rGO film. The sample of 30[Formula: see text]s and 40[Formula: see text]s Au sputtering was optimum to obtain the lowest sheet resistance of 59[Formula: see text]k[Formula: see text]/sq and 56[Formula: see text]k[Formula: see text]/sq, respectively. The sheet resistance was bargained between de-oxygenation retardation and doping by the AuNPs. Both samples of 30 s and 40 s Au sputtering were having a unique and satisfyingly strong absorption band around 260[Formula: see text]nm, 350[Formula: see text]nm and 555[Formula: see text]nm corresponding to [Formula: see text]* transition, [Formula: see text]* transition and SPR of AuNPs, respectively. Such properties are desirable in several applications such as a transparent electrode and optoelectronic sensor.

Synthesis of Zinc Oxide nanoparticles using Chrysopogonzizanioidesgrass extract, its applications in Photodegradation and Antimicrobial Activity

Zinc oxide nanoparticles (ZnONPs) were synthesized using Zinc nitrate hexahydrate as an oxidizer and Chrysopogonzizanioides (Vetiver) grass as a novel fuel. The X Ray Diffraction pattern as well as the Rietveld refinement showed a single-phase wurtzite structure. The average crystallite size and the lattice strain were estimated using Williamson-Hall plot. A very small value of lattice strain indicates that there is no strain and the crystal lattice is very stable. Thepresence of various functional groups in the plant extract and the Zinc –Oxygen bonding in the ZnONPs were confirmed by FTIR. The surface morphology was investigated using SEM and it showed nanorod like structure. The elemental mapping was carried out using EDAX. The EDAX spectrum suggests formation of ZnO nanorods along with high proportion of carbon and low proportion of Si as well as K might have resulted from the rich organic profile of Chrysopogon zizanioidesgrass extract. Within the UV- Visible Spectrum at 300 nm, the highly blue shifted strong absorption band was observed due to the strong quantum confinement effect. The band gap was observed to be 3.628 eV. The photodegradation of RB2 dye was studied over ZnONPs catalyst and it showed excellent photocatalytic activity. The catalyst was active up to five cycles without losing much of its efficiency. Further antimicrobial activity was tested against broad range of micro-organisms namely Staphylococcus aureus, Escherichia coli and much prevalent human fungal pathogen Candida albicans. The Minimum inhibitory concentration (MIC) for each micro-organism was determined using broth micro dilution assay.

Electrochemical Biosensor Based on Furosemide-Gold Nanoparticles for The Determination of Dopamine for Practical Applications

In this study, by taking the advantage of the facile & controlled synthesis of furosemide derived gold nanoparticles (Fr-AuNps) for rapid and sensitive amperometric determination of dopamine (DP). The one-step synthesis of FrAuNps was carried out at room temperature without the use of strong reducing agents. The synthesized Fr-AuNps were studied by UV-Vis spectroscopy, and a strong absorption band for gold nanoparticles was observed at 520 nm. Transmission electron micrographs (TEM) revealed the average particle size below 100 nm. HRTEM showed excellent crystalline features as prepared gold nanoparticles. The electrochemical behavior of gold nanoparticles was examined by cyclic voltammetry (CV) which demonstrated the enhanced electrocatalytic kinetics activity towards the oxidation of dopamine. The presented dopamine biosensor exhibited a linear response for the dopamine in the range of 0.25 to 7 µM. The calculated the detection limit found to be 18.3 nM and limit of quantification 61.5 nM respectively. The proposed dopamine biosensor was successfully employed for the quantification of trace amount of dopamine from human serum and the obtained results are very satisfactory.

Meso-pyrrolyl BODIPY based colorimetric optical sensor for Cu2+ ions

A simple meso-pyrrolyl BODIPY-Schiff base conjugate was synthesized by reacting ([Formula: see text]-formylpyrrolyl) BODIPY with 2-aminophenol in ethanol at reflux followed by recrystallization from CH2Cl2/petroleum ether, affording the conjugate in 72% yield. The conjugate was thoroughly characterized by HR-MS, 1D and 2D NMR and X-ray crystallographic techniques. The X-ray structure of the meso-pyrrolyl BODIPY-Schiff base conjugate revealed that the meso-pyrrole and the phenyl substituents were deviated by an angle of [Formula: see text] and [Formula: see text], respectively, from the plane of the BF2-dipyrrin core. The absorption spectrum of the conjugate was similar to the ([Formula: see text]-formylpyrrolyl) BODIPY with a strong absorption band at 508 nm, whereas the fluorescence of the ([Formula: see text]-formylpyrrolyl) BODIPY was completely quenched in the BODIPY-Schiff base conjugate. Furthermore, cation sensing studies revealed that the conjugate has a specific sensing ability for the Cu(II) ion even in the presence of the other metal ions, as verified by the visual, absorption and mass spectral studies. The DFT optimized structure revealed that the Cu(II) ion was bound to pyrrolic nitrogen, imine nitrogen, phenolic oxygen and two water molecules in a distorted square pyramidal fashion. TD-DFT studies accounted well for the absorption spectra of the BODIPY-Schiff base conjugate and its Cu[Formula: see text] bound complex.

Investigating Methylene Blue Adsorption and Photocatalytic Activity of ZnO/CNC Nanohybrids

Nanohybrids of zinc oxide/cellulose nanocrystals (ZnO/CNCs) were successfully prepared by using a low cost and green method for adsorption and photocatalytic degradation of methylene blue (MB). CNCs have been derived through the hydrolysis reaction by citric/hydrochloric acid from the pure cellulose isolated from Vietnamese Nypa fruticans trunk. The influence of the Zn2+ ion concentration on the morphology, microstructure, and thermal properties as well as the photocatalytic activity of the ZnO/CNC nanohybrids was investigated in detail. Analyses of FTIR spectra, XRD, and SEM indicated that the ZnO nanocrystals with the size of 50 nm formed and loaded on the surface of CNC. Based on the DRS spectra and the nitrogen adsorption–desorption isotherms (BET) analysis, the absorption of ultraviolet light with a strong absorption band around 400 nm was found for all the ZnO/CNC nanohybrids, and the values of specific surface areas (SBET) of materials can be controlled by changing the concentration ratio of Zn2+ ion and CNC. The TGA analysis demonstrated that the ZnO loading samples (ZnO/CNC) had the thermal degradation onset temperature higher than that of neat CNC. The effect of MB removal showed the results which were contributed not only by the adsorption ability of CNC but also by the photocatalytic activity of ZnO. The photocatalytic efficiency significantly depended on the content of ZnO loading. The maximum degradation of MB was about 95% in 150 min for the ZnO/CNC-1.0 sample in which the concentration ratio of zinc-precursor Zn(NO3)2·6H2O and CNC was 1.0.

Remote Sensing of Atmospheric Methane with IR OPO Lidar System

A differential absorption lidar (DIAL) system designed on the basis of optical parametric oscillators (OPO) with nonlinear KTiOAsO4 (KTA) and KTiOPO4 (KTP) crystals is described. The crystals allow laser radiation tuning in the infrared region (IR) wavelength region. The measurements in the 3.30–3.50 μm spectral range, which includes a strong absorption band of methane, are carried out. Lidar backscattered signals in the spectral band 3.30–3.50 μm has been measured and analyzed along the horizontal path in the atmosphere. Based on the experimental results, CH4 concentrations ~2.085 ppm along a 800 m surface path are retrieved in the spectral range under study with a spatial resolution of 100 m.