Akhila, A. K.Babu, Suresh A. R.Anappara, Aji A.Renuka, N. K....
9页
查看更多>>摘要：The non-covalent interactions between graphene and aromatic fluorophores have generated highly sensitive fluorimetric turn-on sensors for various significant analytes. Herein, the supramolecular interaction between reduced graphene oxide and 7-Hydroxy-4-Methyl-8-Amino Coumarin is made use of for tracing Cu2+ at sub-zeptomole level with excellent selectivity among a collection of nineteen metal ions. The system enables quantification of the analyte in a commendably wide range, from micromolar to zeptomolar, a feature that almost all-optical sensors lack. Handy solid-state sensor strip fabricated using the above-mentioned supramolecular combination enabled visual recognition of Cu2+ ions at the molecular level. Based on the chemo recognition ability of the fluorophore, multiple Boolean logic devices operating at the molecular level are proposed. By screening pertinent coumarin derivatives, it is demonstrated that the selectivity and sensitivity of the sensors of this sort are decided by the number of pi- interaction centers of the fluorophores and the strength by which they interact with graphene, respectively, which will enable identification and modification of proper fluorophores for ultra-trace detection of contaminants of environmental relevance from aqueous solutions. (C) 2021 Elsevier B.V. All rights reserved.
Yoon, Tiem LeongYeap, Zhao QinTan, Chu ShanChen, Ying...
11页
查看更多>>摘要：A proof-of-concept medicinal herbs identification scheme using machine learning classifiers is proposed in the form of an automated computational package. The scheme makes use of two-dimensional correlation Fourier Transformed Infrared (FTIR) fingerprinting maps derived from the FTIR of raw herb spectra as digital input. The prototype package admits a collection of 11 machine learning classifiers to form a voting pool. A common set of oversampled dataset containing 5 different herbal classes is used to train the pool of classifiers on a one-verses-others manner. The collections of trained models, dubbed the voting classifiers, are deployed in a collective manner to cast their votes to support or against a given inference fingerprint whether it belongs to a particular class. By collecting the votes casted by all voting classifiers, a logically designed scoring system will select out the most probable guess of the identity of the inference fingerprint. The same scoring system is also capable of discriminating an inference fingerprint that does not belong to any of the classes the voting classifiers are trained for as the 'others' type. The proposed classification scheme is stress-tested to evaluate its performance and expected consistency. Our experimental runs show that, by and large, a satisfactory performance of the classification scheme of up to 90 % accuracy is achieved, providing a proof-of-concept viability that the proposed scheme is a feasible, practical, and convenient tool for herbal classification. The scheme is implemented in the form of a packaged Python code, dubbed the "Collective Voting" (CV) package, which is easily scalable, maintained and used in practice. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：An easy to make xanthene based optical probe synthesized, precise recognition towards mercury ion been achieved by the probe RP and can detect Hg2+ effectively in both for solid and liquid state with a vivid color change. The other tested ion showed no interference, visual and instrumental methods confirms the probe selectivity. Stoichiometry (1:1) confirmed by job's plot, plausible binding of Hg2+ ion with the probe confirmed by mass and NMR studies. Test strip prepared for the prompt onsite detection in aqueous medium with outstanding color variation in daylight. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Ce3+/Dy3+ and Ce3+/Sm3+ co-doped alumino-borophosphate glasses (CDABP/ CSABP) were prepared and characterized for luminescence and SHG efficiency properties. FT-IR and FT-Raman spectra have been utilized to identify different functional groups of Phosphate networks. Various optical properties such as, optical absorption, optical band gap energy (E-g), Urbach energy (Delta E) and linear refractive index (n) of the glasses were determined using UV-Vis spectrometer in the spectral range 200-1200 nm. Scanning Electron Microscopy/Energy Dispersive spectrometry (SEM/EDS) reveals information about the elemental compositional homogeneity as well as the surface morphology of the prepared glasses. Influences of a luminescence co-activator of Ce3+/Dy3+ and Ce3+/Sm3+ ions in alumina-borophosphate glasses were interpreted under the excitation wavelength of 300 nm. Two emission peaks detected at 426 nm (blue) and 574 nm (Yellow) in CDABP glass corresponding to the Dy3+, whereas three emission peaks traced at 558 nm (green), 598 nm (orange) and 652 nm, (red) in CSABP glass corresponding to the Sm3+. The Influence of internal and external quantum efficiency (QE) on the glass's photoluminescence spectrum was measured. The CIE chromaticity obtained from the luminescence spectra, confirming that the CSABP glass emits white light. The colour purity (P-c) and excitation purity (Pe) of the glasses were investigated in order to quantify the quality of light emitted by them. The second harmonic generation (SHG) efficiency of the synthesized glasses was determined without the need of a thermal polling mechanism, and the magnitude was compared to that of Urea and KDP crystal reference samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Artworks are complex objects that merit study and preservation. Far-infrared spectroscopy in ATR mode appears to be a suitable technique for this purpose because it enables information to be obtained regarding the material's composition in a non-destructive way. The use of Far-infrared is especially interesting because most organic compounds do not absorb in this energy range, suggesting the possibility of identifying inorganic pigments. Based on works performed by two research groups from the University of Bologna and the University of Tartu, this study attempts to obtain additional information regarding the capabilities and limitations of Far-infrared spectroscopy when it is applied to objects as complex as artworks. This article first studies the capability of the technique for identifying pigments by following the stability of the position of their absorption bands when mixed with linseed oil, the minimum amount of pigment necessary to be detected and how this amount changes when it is part of a paint layer. The consequences of the pigment: linseed oil interaction and the ageing process are also studied through changes in the linseed oil signal absorptions related to the acid carboxylic and carboxylate bands. The entire study leads to the conclusion that Far-Infrared in ATR mode is an interesting option for the selective identification of some inorganic pigments, but their potential application depends on each case considered. (C) 2021 The Author(s). Published by Elsevier B.V.
查看更多>>摘要：A sensitive and direct spectrofluorimetric method was developed for simultaneous quantitation of two co-administered drugs, namely, alfuzosin hydrochloride (AFH) and vardenafil hydrochloride (VRH). Both drugs exhibited native fluorescence properties that could be exploited to assay them in biological fluids with high sensitivity. Spectrofluorimetric analysis of AFH and VRH is based on excitation of both drugs at 265 nm where emission spectra were recorded separately for AFH and VRH at 380 and 485 nm, respectively. Micellar trends in analytical chemistry were adopted to minimize both environmental and occupational hazards, using distilled water and sodium dodecyl sulphate (serves as a micellar medium that enhanced the sensitivity of AFH and VRH) for analysis of both drugs in their raw materials, tablets, and human biological fluids (plasma and urine). Linearity ranges were 1.0-16.0 and 10.0-700.0 ng mL(-1) for AFH and VRH, respectively. The proposed method was successfully assessed for analysis of AFH and VRH in spiked human plasma and urine samples over the following concentrations: 1.0-12.0 ng mL(-1) and 4.0-400.0 ng mL(-1) for both drugs, simultaneously with mean recoveries of 101.08 % and 102.06 % in plasma and 96.75 % and 92.8 % in urine. Statistical analysis of the practical results has proved quite good agreement and revealed there were no significant differences in the accuracy and precision with those obtained by the comparison methods. The proposed method was applied successfully to Prostetrol (R) and Powerecta (R) commercial tablets without interference with tablet additives. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Xanthine oxidase (XO) is a purine catabolic enzyme related to hyperuricemia and gout. Porphyra polysaccharide (PP) is a kind of sulfated polysaccharide with potent biological activity. Herein, the interaction mechanism between PP and XO was studied by enzyme kinetics and multi-spectroscopy methods for the first time. Inhibition kinetics assay showed that PP reversibly inhibited XO activity in a mixed competitive manner with an IC50 of 10.53 +/- 0.69 mg/ml. Fluorescence titration studies and thermodynamic parameter calculations revealed that PP could spontaneously bind to XO through hydrophobic interactions, with a class of binding site. Circular dichroism analysis demonstrated that PP induced secondary structure rearrangement and conformational change of XO. Molecular docking further revealed that PP inserted into the hydrophobic cavity of XO, occupying the catalytic center, leading to the inhibition of XO activity. This study may provide new insights into the inhibitory mechanism of PP as a promising XO inhibitor. (C) 2021 Elsevier B.V. All rights reserved.
Kamel, Rasha M.Mohamed, Shaimaa K.Mahmoud, Marwa A.
8页
查看更多>>摘要：A new fluorescent sensing microtiter plate (MTP) was developed for high sensitivity monitoring of anthracene in seawater samples. For this purpose, two ternary complexes of Tb(III) ions with dibenzoyl-methane and neocuproine [Tb(DBM)(2)(MePhen)] or with dibenzoylmethane and bathocuproine [Tb(DBM)(2)(PhMePhen)] were synthesized. Elemental analysis, energy dispersive X-ray analysis, X-ray diffraction, infrared and ultraviolet-visible emission, and thermal analysis were conducted on the Tb (III) complexes. The limits of detection (D-L) were 0.14 and 1.05 mu mol L-1 for [Tb(DBM)(2)(MePhen)] and [Tb(DBM)(2)(PhMePhen)], respectively. [Tb(DBM)(2)(PhMePhen)] MTP is embedded in a membrane made of cellulose acetate. The first high-throughput anthracene sensor MTP, based on [Tb(DBM)(2)(PhMePhen)] sensor showed a linear range, from 0.2 to 20 mu umol L-1. [Tb(DBM)(2)(PhMePhen)] MTP was validated for accurate and precise monitoring of anthracene using gas chromatography. The selectivity of the [Tb(DBM)(2)(PhMePhen)] MTP toward anthracene was examined. The data indicated that [Tb(DBM)(2)(PhMePhen)] MTP is suitable for rapid and direct detection of anthracene. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Near-infrared (NIR) photothermal therapy is an effective partner to the chemotherapy of tumors with the merits of high therapeutic ability and slight side effect on normal tissues. Herein, we synthesized gold nanorods and assembled them with L-cysteine reduced graphene oxide (AuNR@Lcyst-rGO) for efficient photothermal therapy. The high therapeutic efficacy of AuNR@Lcyst-rGO can be due to the high photothermal effect of gold nanorods and reduced graphene oxide, and the synergistic effect of them. The nontoxicity of L-cysteine also guarantees the comfortable biocompatibility of reduced graphene oxide, which is essential for the photothermal absorber used in human tissue. The results demonstrate that assembly of gold nanorods with reduced graphene oxide (AuNR@Lcyst-rGO) is a promising photothermal agent with high efficient NIR-triggered photothermal therapy efficiency, excellent stability, superior biocompatibility. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Sr3LiSbO6 phosphors were prepared by high temperature solid state reaction method. The crystal phase, morphology and optical properties were characterized by X-ray powder diffraction spectroscopy, scan-ning electronic microscope, absorption and photoluminescence (PL) spectra. The XRD Rietveld refinement was performed to obtain the detailed crystal structure of Sr3LiSbO6. The electronic structure was analyzed by density functional theory (DFT) calculation. Sr3LiSbO6 possessed indirect band structure and the band-gap were determined to be 3.17 eV. Self-activated far-red emissions at 630-800 nm were detected under the excitation at 340 nm, which was proposed to originate from the transition between interstitial oxygen defective state to six hybrid 4d(105)s(0) states of Sb5+ according to the results of PL spectra of samples annealed at different atmospheres. The PL intensity can be significantly enhanced by 2.9 times after doping 2 mol% Gd3+ ions in Sr3LiSbO6. The internal quantum efficiency of Sr3LiSbO6:2 mol%Gd3+ was determined to be 25.2%. The influence of the Gd3+ doping on the self-activated PL lifetimes of Sr3LiSbO6 and the thermal quenching property of Sr3LiSbO6:2 mol%Gd3+ was studied. (C) 2021 Elsevier B.V. All rights reserved.
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