Trace gas sensing technologies are widely used in many applications, such as environmental monitoring, life science, medical diagnostics, and planetary exploration. On the one hand, laser sources ...have developed greatly due to the rapid development of laser media and laser techniques in recent years. Some novel lasers such as solid-state, diode, and quantum cascade lasers have experienced significant progress. At present, laser wavelengths can cover the range from ultraviolet to terahertz, which could promote the development of laser gas sensing technologies significantly. On the other hand, some new gas sensing methods have appeared, such as photothermal spectroscopy and photoacoustic spectroscopy. Laser spectroscopy-based gas sensing techniques have the advantages of high sensitivity, non-invasiveness, and allowing in situ, real-time observation. Due to the rapid and recent developments in laser source as well as the great merits of laser spectroscopy-based gas sensing techniques, this book aims to provide an updated overview of the state-of-the-art laser gas sensing technologies.
Optical gas sensing is one of the fastest developing research areas in laser spectroscopy. Continuous development of new coherent light sources operating especially in the Mid-IR spectral band ...(QCL—Quantum Cascade Lasers, ICL—Interband Cascade Lasers, OPO—Optical Parametric Oscillator, DFG—Difference Frequency Generation, optical frequency combs, etc.) stimulates new, sophisticated methods and technological solutions in this area. The development of clever techniques in gas detection based on new mechanisms of sensing (photoacoustic, photothermal, dispersion, etc.) supported by advanced applied electronics and huge progress in signal processing allows us to introduce more sensitive, broader-band and miniaturized optical sensors. Additionally, the substantial development of fast and sensitive photodetectors in MIR and FIR is of great support to progress in gas sensing. Recent material and technological progress in the development of hollow-core optical fibers allowing low-loss transmission of light in both Near- and Mid-IR has opened a new route for obtaining the low-volume, long optical paths that are so strongly required in laser-based gas sensors, leading to the development of a novel branch of laser-based gas detectors. This Special Issue summarizes the most recent progress in the development of optical sensors utilizing novel materials and laser-based gas sensing techniques.
A complement to Spectroscopic methods in mineralogy and geology, edited by Frank Hawthorne in 1988, vol. 18 of the Reviews in mineralogy series. This current work also updates many of the techniques ...mentioned in the original volume along with introducing new methods in spectroscopy that had developed in the past twenty-five years.
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•Concurrent green synthesis of N-CDs and ZnO@N-C hybrid by a hydrothermal method.•N-CDs used as a multicolour fluorescent probe for cell imaging without passivation.•ZnO@N-C utilized ...for the degradation of MB with a high rate constant of 0.0456min−1.•This green synthesized material could offer eco-friendly environmental applications.•Moreover, new avenue to synthesize metal oxide grafted carbon sheets was provided.
The hybrid composite of ZnO nanoparticles decorated nitrogen-doped graphitic carbon sheets (ZnO@N-C) alongside nitrogen-doped carbon dots (N-CDs) were synthesized by the direct hydrothermal method of peach fruit juice and ZnO nanoparticles (ZnO NPs). The synthesized ZnO@N-C hybrid composite and N-CDs were thoroughly characterized by various physicochemical techniques including powder X-ray diffraction (PXRD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray (EDX) spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and fluorescence spectroscopy. The ZnO NPs were dispersed in the graphitic carbon structure with an average size of 25±5nm. The chemical composition of C, O, N, and Zn within the ZnO@N-C hybrid composite exhibits enough graphitization. Methylene blue (MB)-degradation was estimated utilizing the ZnO@N-C hybrid composite, a maximum degradation efficiency of >95% was achieved in a neutral aqueous medium within 60min under UV-light irradiation. This maximum efficiency allows estimating the contribution of the heterogeneous and homogeneity of ZnO@N-C hybrid composite which is responsible for the MB-degradation. Moreover, the economic natural biosource or bio-waste was employed for the synthesis of ZnO@N-C hybrid composite and displays an excellent photocatalytic degradation under UV-light irradiation which is an alternate for other carbon-based metal oxides. In addition, the resulting N-CDs were utilized as a fluorescence probe for cellular imaging, owing to their tremendous properties such as bright fluorescence with high quantum yield, excellent water solubility, and good biocompatibility. The N-CDs displays a multicolour fluorescence based on their changing of excitation wavelength and these multicolour fluorescence emissions offered a multicolour cellular imaging which could be applicable for real biological system in the near future.
Angle-resolved photoemission spectroscopy (ARPES) has been used to study the electronic structure of InSe and CuIn.sub.5Se.sub.8 single crystals and determine the general patterns of its ...transformation after the introduction of copper. The main dispersion curves of valence bands in the studied multicomponent systems and the effective masses of majority carriers in CuIn.sub.5Se.sub.8 have been obtained. Joint theoretical and experimental research has allowed us to apply ARPES not only to single isolated states, but also to complex crystals with a large number of atoms in the unit cell (and, consequently, a large number of dispersion bands). It has been demonstrated that the neighborhoods of maxima and minima of dispersion curves E(k), which essentially define the set of experimental ARPES spectra, make the dominant contribution to the observed signal intensity. Keywords: electronic structure, chalcogenides, CuIn.sub.5Se.sub.8, InSe, effective masses, angle-resolved photoemission spectroscopy DOI: 10.1134/S0031918X18050083
The field-effect electron mobility of aqueous solution-processed indium gallium oxide (IGO) thin-film transistors (TFTs) is significantly enhanced by polyvinyl alcohol (PVA) addition to the precursor ...solution, a >70-fold increase to 7.9 cm²/Vs. To understand the origin of this remarkable phenomenon, microstructure, electronic structure, and charge transport of IGO:PVA film are investigated by a battery of experimental and theoretical techniques, including In K-edge and Ga K-edge extended X-ray absorption fine structure (EXAFS); resonant soft X-ray scattering (R-SoXS); ultraviolet photoelectron spectroscopy (UPS); Fourier transform-infrared (FT-IR) spectroscopy; time-of-flight secondary-ion mass spectrometry (ToF-SIMS); composition-/processing-dependent TFT properties; high-resolution solid-state ¹H, 71Ga, and 115In NMR spectroscopy; and discrete Fourier transform (DFT) analysis with ab initio molecular dynamics (MD) liquid-quench simulations. The 71Ga{¹H} rotational-echo double-resonance (REDOR) NMR and other data indicate that PVA achieves optimal H doping with a Ga···H distance of ∼3.4 Å and conversion from six- to four-coordinate Ga, which together suppress deep trap defect localization. This reduces metal-oxide polyhedral distortion, thereby increasing the electron mobility. Hydroxyl polymer doping thus offers a pathway for efficient H doping in green solvent-processed metal oxide films and the promise of high-performance, ultra-stable metal oxide semiconductor electronics with simple binary compositions.
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•Investigated the synthesis of CdS@TiO2 core-shell structure by solution phase and hydrothermal method.•Determined the changes in the physical and chemical properties of TiO2 on ...CdS.•The light adsorption shifts to the visible region was observed with increase in Cd molar ratio.•Investigated the degradation of the chlorophenols under visible light.
The presence of chlorophenols in various environmental media has become a human health concern. In this study, homogeneous cadmium sulfide (CdS) sub-microspheres were prepared through a solution phase and hydrothermal method, form cadmium acetate dihydrate and thiourea. CdS@TiO2 core-shell nanostructures were synthesized using the as prepared CdS (1:4), through two steps including the solution phase and hydrothermal methods. The prepared CdS sub-microspheres and CdS@TiO2 were characterized using a number of physico-chemical techniques such as X-ray diffraction (XRD), RAMAN spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–vis Diffuse Reflectance Spectroscopy (UV–vis DRS), Scanning Electron Microscopy (SEM), Transmission Electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The experimental results demonstrated that the morphology of the CdS sub-microspheres can be easily controlled by changing the ratio of cadmium acetate/thiourea. The SEM analysis revealed that the CdS sub-microspheres prepared by solution phase and hydrothermal methods possess an average size of around 149 and 470 nm respectively. The CdS sub-microspheres and CdS@TiO2 core-shell materials were evaluated for the visible light photocatalytic degradation of 2,4-dichlorophenol and 2,4,6-trichlorophenol. CdS@TiO2 showed up to 20% enhanced photocatalytic activity for the degradation of 2,4-DCP and 2,4,6-TCP compared to pure CdS. Up to 70% of 2,4-DCP and 2,4,6-TCP were removed in 6 h. The enhanced photoactivity can be attributed to the longer lifetime of photo-generated electron − hole pairs from the CdS@TiO2 compared to the pure CdS material.
During the last decades, X-ray absorption spectroscopy (XAS) has become an indispensable method for probing the structure and composition of heterogeneous catalysts, revealing the nature of the ...active sites and establishing links between structural motifs in a catalyst, local electronic structure, and catalytic properties. Here we discuss the fundamental principles of the XAS method and describe the progress in the instrumentation and data analysis approaches undertaken for deciphering X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. Recent usages of XAS in the field of heterogeneous catalysis, with emphasis on examples concerning electrocatalysis, will be presented. The latter is a rapidly developing field with immense industrial applications but also unique challenges in terms of the experimental characterization restrictions and advanced modeling approaches required. This review will highlight the new insight that can be gained with XAS on complex real-world electrocatalysts including their working mechanisms and the dynamic processes taking place in the course of a chemical reaction. More specifically, we will discuss applications of in situ and operando XAS to probe the catalyst’s interactions with the environment (support, electrolyte, ligands, adsorbates, reaction products, and intermediates) and its structural, chemical, and electronic transformations as it adapts to the reaction conditions.
In this paper, we propose a facile and mild route to prepare size-tunable silver nanoparticles (Ag NPs) and their finishing application on fabrication of antibacterial cotton fabrics. The as-prepared ...Ag NPs, with an average particles size of 2.3 nm, show the minimal inhibitory concentration of 7.8 µg/mL and the minimum bactericidal concentration of 15.6 µg/mL, respectively. In this study, sodium citrate served as a stabilizing agent to prevent Ag NP agglomeration in the synthesis process, and citric acid acted as a binder to fix Ag NPs on the cotton fabrics through chemical bonds in the finishing process. The results of Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy demonstrate that Ag NPs have been fixed and well dispersed on the cotton fabric surface. Ag contents in the hybrid fabrics were measured by the techniques of inductively coupled plasma atomic emission spectroscopy and UV-vis, and the antibacterial properties of hybrid fabrics were tested by the shake flask and agar diffusion plate method. It is found that the Ag NP coated cotton fabrics exhibit excellent antimicrobial activities against both the Gram-negative bacterium of Escherichia coli (E. coli) and the Gram-positive bacterium of Staphylococcus aureus (S. aureus). The percentages of reduction bacteria remain at 91.8% and 98.7% for S. aureus and E. coli, respectively, even after 50 cycles of consecutive laundering, which indicates that the antibiotic performance of the as-fabricated hybrid fabrics is also durable.
DNA is present in body in the form of a double helix. Each strand is composed of a combination of four nucleotides. Within a strand these nucleotides are connected through phosphodiester linkages. ...Display omitted
•DNA is the molecular target for many anticancer drugs.•Drug–DNA interaction.•Various types of Drug–DNA interaction.•Various techniques used for the study of Drug–DNA interaction.
The present paper review the drug–DNA interactions, their types and applications of experimental techniques used to study interactions between DNA and small ligand molecules that are potentially of pharmaceutical interest. DNA has been known to be the cellular target for many cytotoxic anticancer agents for several decades. Understanding how drug molecules interact with DNA has become an active research area at the interface between chemistry, molecular biology and medicine. In this review article, we attempt to bring together topics that cover the breadth of this large area of research. The interaction of drugs with DNA is a significant feature in pharmacology and plays a vital role in the determination of the mechanisms of drug action and designing of more efficient and specifically targeted drugs with lesser side effects. Several instrumental techniques are used to study such interactions. In the present review, we will discuss UV–Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The applications of spectroscopic techniques are reviewed and we have discussed the type of information (qualitative or quantitative) that can be obtained from the use of each technique. Not only have novel techniques been applied to study drug–DNA interactions but such interactions may also be the basis for the development of new assays. The interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases.
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