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991.
分析AD590设计数字温度计的工作原理,通过简单改进提高实验的精度,并扩展了设计数字温度计的应用空间。 相似文献
992.
993.
A photochemically induced fluorescence system combined with second-order chemometric analysis for the determination of the anticonvulsant carbamazepine (CBZ) is presented. CBZ is a widely used drug for the treatment of epilepsy and is included in the group of emerging contaminant present in the aquatic environment. CBZ is not fluorescent in solution but can be converted into a fluorescent compound through a photochemical reaction in a strong acid medium. The determination is carried out by measuring excitation–emission photoinduced fluorescence matrices of the products formed upon ultraviolet light irradiation in a laboratory-constructed reactor constituted by two simple 4 W germicidal tubes. Working conditions related to both the reaction medium and the photoreactor geometry are optimized by an experimental design. The developed approach enabled the determination of CBZ at trace levels without the necessity of applying separation steps, and in the presence of uncalibrated interferences which also display photoinduced fluorescence and may be potentially present in the investigated samples. Different second-order algorithms were tested and successful resolution was achieved using multivariate curve resolution-alternating least-squares (MCR-ALS). The study is employed for the discussion of the scopes and yields of each of the applied second-order chemometric tools. The quality of the proposed method is probed through the determination of the studied emerging pollutant in both environmental and drinking water samples. After a pre-concentration step on a C18 membrane using 50.0 mL of real water samples, a prediction relative error of 2% and limits of detection and quantification of 0.2 and 0.6 ng mL−1 were respectively obtained. 相似文献
994.
Catalytic conversion of synthesis gas (CO+H2) into hydrocarbons, also known as Fischer-Tropsch (FT) synthesis, is a crucial reaction for the transformation of non-petroleum carbon resources such as coal, natural gas, shale gas, coal-bed gas and biogas, as well as biomass into liquid fuels and chemicals. Many factors can influence the catalytic behavior of a FT catalyst. This review highlights recent advances in understanding some key catalyst factors, including the chemical state of active phases, the promoters, the size and the microenvironment of active phase, which determine the CO conversion activity and the product selectivity, particularly the selectivity to C5+ hydrocarbons. 相似文献
995.
《Helvetica chimica acta》2018,101(3)
Here we present a novel active surface that demonstrates pH responsiveness and can be used as a platform for designing ‘smart labels’. To generate our active surfaces, we immobilized polymer nanocompartments onto glass surfaces using thiol–ene chemistry. Prior to surface attachment, a pH responsive model dye was encapsulated within nanocompartments at two different pH values. We confirmed the attachment and distribution of dye‐loaded polymersomes and established the pH responsiveness of the active surface construct. The strategy presented here was carefully chosen to obtain small sized functional surfaces from commercially available materials that can be easily integrated into intelligent packaging systems. The ability to miniaturize such smart labels, while still being able to detect their response to the environment, is a crucial step towards developing active surfaces suitable for food packaging applications. 相似文献
996.
997.
Balasubramanian Sridhar Jagadeesh Babu Nanubolu Krishnan Ravikumar 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1164-1169
Lamotrigine, an antiepileptic drug, has been complexed with three aromatic carboxylic acids. All three compounds crystallize with the inclusion of N,N‐dimethylformamide (DMF) solvent, viz. lamotriginium [3,5‐diamino‐6‐(2,3‐dichlorophenyl)‐1,2,4‐triazin‐2‐ium] 4‐iodobenzoate N,N‐dimethylformamide monosolvate, C9H8Cl2N5+·C7H4IO2−·C3H7NO, (I), lamotriginium 4‐methylbenzoate N,N‐dimethylformamide monosolvate, C9H7Cl2N5+·C8H8O2−·C3H7NO, (II), and lamotriginium 3,5‐dinitro‐2‐hydroxybenzoate N,N‐dimethylformamide monosolvate, C9H8Cl2N5+·C7H3N2O7−·C3H7NO, (III). In all three structures, proton transfer takes place from the acid to the lamotrigine molecule. However, in (I) and (II), the acidic H atom is disordered over two sites and there is only partial transfer of the H atom from O to N. In (III), the corresponding H atom is ordered and complete proton transfer has occurred. Lamotrigine–lamotrigine, lamotrigine–acid and lamotrigine–solvent interactions are observed in all three structures and they thereby exhibit isostructurality. The DMF solvent extends the lamotrigine–lamotrigine dimers into a pseudo‐quadruple hydrogen‐bonding motif. 相似文献
998.
Enantiomerically pure methyl 3-fluoro-5-methyladamantane-1-carboxylate was obtained by the separation of its racemate, which was prepared from methyladamantane-1-carboxylate in three steps in 86% overall yield. From the resulting pure enantiomers, a new optically active adamantane compound was prepared by the substitution of a fluorine atom with a phenyl group. Both enantiomers of 3-amino-5-methyladamantane-1-carbooxylic acid were also prepared. 相似文献
999.
Speciation, i.e. identification and quantification, of surface species on heterogeneous surfaces by infrared spectroscopy is important in many fields but remains a challenging task when facing strongly overlapped spectra of multiple adspecies. Here, we propose a new methodology, combining state of the art instrumental developments for quantitative infrared spectroscopy of adspecies and chemometrics tools, mainly a novel data processing algorithm, called SORB-MCR (SOft modeling by Recursive Based-Multivariate Curve Resolution) and multivariate calibration. After formal transposition of the general linear mixture model to adsorption spectral data, the main issues, i.e. validity of Beer–Lambert law and rank deficiency problems, are theoretically discussed. Then, the methodology is exposed through application to two case studies, each of them characterized by a specific type of rank deficiency: (i) speciation of physisorbed water species over a hydrated silica surface, and (ii) speciation (chemisorption and physisorption) of a silane probe molecule over a dehydrated silica surface. In both cases, we demonstrate the relevance of this approach which leads to a thorough surface speciation based on comprehensive and fully interpretable multivariate quantitative models. Limitations and drawbacks of the methodology are also underlined. 相似文献
1000.
By combining the decision process of ant colony optimization (ACO) with the multistage decision process of image segmentation
based on active contour model (ACM), an algorithm called finite grade ACO (FACO) for image segmentation is proposed. This
algorithm classifies pheromone into finite grades and updating of the pheromone is achieved by changing the grades and the
updated quantity of pheromone is independent from the objective function. The algorithm that provides a new approach to obtain
precise contour is proved to converge to the global optimal solutions linearly by means of finite Markov chains. The segmentation
experiments with ultrasound heart image show the effectiveness of the algorithm. Comparing the results for segmentation of
left ventricle images shows that the ACO for image segmentation is more effective than the GA approach and the new pheromone
updating strategy appears good time performance in optimization process. 相似文献