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101.
Zoltán Sebestyén Zoltán May Kati Réczey Emma Jakab 《Journal of Thermal Analysis and Calorimetry》2011,105(3):1061-1069
The goal of this study was to clarify the effect of alkaline pretreatments on the thermal decomposition and composition of
industrial hemp (Cannabis sativa L.) samples. Thermogravimetric/mass spectrometric measurements (TG/MS) have been performed, on untreated, hot water washed,
and alkali-treated hemp samples. The main differences between the thermal decomposition of the samples are interpreted in
terms of the different alkali ion contents which have been determined using inductively coupled plasma-optical emission spectroscopy
(ICP-OES) method. Principal component analysis (PCA) has been used to find statistical correlations between the data. Correlations
have been obtained between the parameters of the thermal decomposition and the alkali ion content as well as the altered chemical
structure of the samples. The differences in the thermal behavior of the samples are explained by the different K+ and Na+ contents and the changed structure of the hemicellulose component of the samples due to the pretreatments. The more alkali
ions remain in the hemp samples after the alkali treatment, the more ash, char and lower molecular products are formed during
thermal decomposition. 相似文献
102.
Kati Medina-Dzul David Muñoz-Rodríguez Yolanda Moguel-Ordoñez Cristian Carrera-Figueiras 《Chemical Papers》2014,68(11):1474-1481
The excessive application of organophosphate pesticides (OPPs) in crop fields close to hives and its application in beekeeping practices are potential sources of contamination of propolis. Pesticides were extracted from raw propolis by matrix solid-phase dispersion. Because of the complex chemical composition of propolis, binary solvent mixtures based on acetonitrile and a relatively non-polar solvent in different proportions were tested for the selective elution of OPPs. The effect of mixed solvents on clean-up was evaluated by GC-MS and the main interfering compounds co-eluted with pesticides were identified. In addition, three volumes of the solvent mixture and the volume of the sample were evaluated in an experimental factorial design. The final experimental conditions were 1 mL of dissolved propolis and 8 mL of acetonitrile/dichloromethane (g4 r = 25: 75). Mean recoveries ranged from 55 % to 96 % (relative standard deviation < 8 %) with an inter-day precision lower than 24 %. The proposed method was applied to the analysis of real samples obtained from local beekeepers. 相似文献
103.
Kati Finzel Joel Davidsson Igor A. Abrikosov 《International journal of quantum chemistry》2016,116(18):1337-1341
Based on the Kohn–Sham Pauli potential and the Kohn–Sham electron density, the upper bound of the Pauli kinetic energy is tested as a suitable replacement for the exact Pauli kinetic energy for application in orbital‐free density functional calculations. It is found that bond lengths for strong and moderately bound systems can be qualitatively predicted, but with a systematic shift toward larger bond distances with a relative error of 6% up to 30%. Angular dependence of the energy‐surface cannot be modeled with the proposed functional. Therefore, the upper bound model is the first parameter‐free functional expression for the kinetic energy that is able to qualitatively reproduce binding curves with respect to bond distortions. © 2016 Wiley Periodicals, Inc. 相似文献
104.
Synthesis of 1‐(p‐Sulphophenyl)‐3‐methyl‐5‐pyrazolone Based Acid Dyes and Their Applications on Leather
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Ghulam Hussain Nasir Abbas Makshoof Ather Misbah Ul Ain Khan Aamer Saeed Rashid Saleem Ghulam Shabir 《中国化学会会志》2016,63(8):645-652
A new series of pyrazolone based azo acid dyes (3a–g) has been synthesized starting from 1‐(p‐sul‐phophenyl)‐3‐methyl‐5‐pyrazolone (1). The synthetic methodology included the nitrosation of p‐sulphophenyl methyl pyrazolone followed by reduction, diazotization and coupling with Naphthol AS derivatives (2a–f), in alkaline medium to yield different acid dyes. Multichromic metal complexes of these dyes (5a–f, 6a–f and 7a–f) with 3d transition metals Chromium, Iron and Copper were also synthesized. The structures of all of newly synthesized compounds were confirmed by analytical data and spectroscopic techniques. The synthesized dyes were applied on leather to assess their light fastness, wash fastness and rubbing fastness and were shown to exhibit high values of 4–5 for majority of dyes. 相似文献
105.
Zsófia Kádár Truus De Vrije Miriam A. W. Budde Zsolt Szengyel Kati Réczey Pieternel A. M. Claassen 《Applied biochemistry and biotechnology》2003,107(1-3):557-566
The main objective of this study was to develop a system for the production of “renewable” hydrogen. Paper sludge is a solid
industrial waste yielding mainly cellulose, which can be used, after hydrolysis, as a feedstock in anaerobic fermentation
by (hyper)thermophilic organisms, such as Thermotoga elfii and Caldicellulosiruptor saccharolyticus. Tests on different medium compositions showed that both bacteria were able to produce hydrogen from paper sludge hydrolysate,
but the amount of produced hydrogen and the requirement for other components differed. Hydrogen production by T. elfii strongly depended on the presence of yeast extract and salts. By contrast, C. saccharolyticus was less dependent on medium components but seemed to be inhibited by a component present in the sludge hydrolysate. Utilization
of xylose was preferred over glucose by C. saccharolyticus. 相似文献
106.
107.
Hakala K Nuutinen JM Straub T Rissanen K Vainiotalo P 《Rapid communications in mass spectrometry : RCM》2002,16(17):1680-1685
Eleven differently substituted 3,4-dihydro-2H-1,3-benzoxazine resorcarenes were studied by electrospray ionisation (ESI) and matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry, using Fourier transform ion cyclotron resonance (FT-ICR) and time-of-flight (TOF) mass spectrometers, respectively. Under ESI conditions it was possible to transfer the intact resorcarenes from solution to the gas phase, yielding [M + H](+) and [M + 2H](+) ions as the main ions observed. Energy increase of the ions induced ready decomposition through successive eliminations of four CH(2)NR groups. Ion-molecule reactions showed that the ionising proton was situated somewhere inside the molecule and could not be reached with neutral reagent gases. In the host-guest complexation experiments, the benzoxazine resorcarenes studied turned out to be poor hosts for alkali metal and ammonium ions. In MALDI experiments, 2,5-dihydroxybenzoic acid proved to be the best matrix for these compounds. However, the intensity of the [M + H](+) ions was low for all compounds, and extensive fragmentation with consecutive elimination of CH(2)NR groups was observed. 相似文献
108.
Analysis of neonicotinoids from plant material by desorption atmospheric pressure photoionization‐mass spectrometry
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109.
In the current work, phenolic acids were analysed and their radical scavenging activity evaluated by CE, including the quantification of overlapping peaks by applying the multivariate curve resolution (MCR) method. To investigate radical scavenging activity, the solution of phenolic acids was treated with a stable free 2,2-diphenyl-1-picrylhydrazyl radical of different concentrations and the radical scavenging activity of the reaction mixture was monitored. The radical scavenging reaction was also applied to wheat bran extracts. The overlapping peaks on the electropherograms of both mixtures of standard compounds and extracts of different wheat bran varieties were resolved by using the MCR method, assuming that the overlapping compounds have different UV spectra. MCR enabled the insufficient resolution between syringic and ferulic acids to be effectively resolved. 相似文献
110.
Nik Akmar Rejab Mohamadariff Othman Wan Fahmin Faiz Wan Ahmad Mohd Fadzil Ain Zainal Arifin Ahmad 《Journal of Sol-Gel Science and Technology》2011,57(2):172-177
In this paper, we report the application of Neodymium (Nd) doped barium titanate thin films (Ba1-xNdx) TiO3 with x = 0 and 0.07 as dielectric resonator antenna. The films were prepared using the sol–gel method and dip-coating technique.
Barium acetate, titanium (IV) isopropoxide and neodymium (III) acetate hydrate were used as precursors while glacial acetic
acid and acetylacetone were used as solvents. Si wafers were used as a substrate with dipping times varying from 10, 30, and
50 s. The 0.07 films were >800 nm thick and crystallized after being annealed at 800°C for 30 min. The films were tested as
dielectric resonator antenna. It was found that, on the actual antenna circuit, the resonant frequency decreased as the (Ba0.93Nd0.07) TiO3 films thickness increased (from 0.8379, to 5.4525 μm). All samples resonate in the range of 8.68–8.83 GHz with quasi omni-directional
radiation patterns. 相似文献