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91.
A novel method for the simultaneous determination of six benzodiazepines (BZDs) and four tricyclic antidepressants (TCAs) in biological fluids by HPLC with UV detection at 240 nm has been developed. After a deproteinization step biological fluids were analyzed by direct injection. SPE on Nexus cartridges was also applied. Since two compounds, namely imipramine and diazepam, were coeluting, a sequential SPE protocol has been developed. BZDs were eluted by a mixture of methanol/ACN(1:1), followed by the elution of TCAs with methanol. Separation was performed on a Kromasil C8 column (250 x 64 mm(2) id, 5 microm) using a mobile phase of 0.05 MCH3COONH4/ACN/methanol (initial composition 55:15:30 v/v/v) at a flow rate of 1.0 mL/min delivered by a gradient program within 15 min. Colchicine was used as the internal standard (4 ng/microL). The method was linear for all analytes up to 20 ng/lL, with coefficients of regression between 0.996 and 0.99996. LODs and LOQs were 0.08-1.17 and 0.28-3.91 ng/lL, respectively. Recovery was in the range of 92.8-108.7% for within-day and 91.9-109.9% for between-day assays, with RSD values lower than 10.0% for all matrices. 相似文献
92.
Issa Yavari S. Zahra Sayyed-Alangi Maryam Sabbaghan Rahimeh Hajinasiri Nasir Iravani 《Monatshefte für Chemie / Chemical Monthly》2008,139(9):1025-1028
An efficient one-pot synthesis of functionalized thioureas is described via three-component reaction of benzoyl isothiocyanates, secondary amines, and alkyl propiolates in the presence of triphenylphosphine
(20 mol%).
Correspondence: Issa Yavari, Chemistry Department, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran 相似文献
93.
Mohsan Nawaz Faiza Jan Iftikhar Musa Kaleem Baloch Wajid Rehman Iftikhar Ahmad 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(13):2169-2172
Single-phase giant magnetoresistance (GMR) compounds were prepared by doping the parent compound, NdMnO3, with Sr at Nd sites. The resistivity of the doped samples showed two prominent regions (Δρ/ΔT < 0, insulating and Δρ/ΔT > 0, metallic). The doped samples exhibited an enhancement in double exchange (DE) interactions causing an increase in T
c (transition temperature). Magnetic field decreased the resistance of all the samples because of the suppression of spin fluctuations
and an increase in disorder in the system. The polaron and variable range hopping (VRH) models were good for studying the
transport mechanism of electrons and understand their behavior at T > T
c. 相似文献
94.
Shaik Inayath Basha Atta Ur Rehman Hammad R. Khalid Md. Abdul Aziz Jung-Hoon Kim 《Chemical record (New York, N.Y.)》2023,23(10):e202300054
Three-dimensional (3D) geopolymer printing (3DGP) technology is a rapidly evolving digital fabrication method used in the construction industry. This technology offers significant benefits over 3D concrete printing in terms of energy saving and reduced carbon emissions, thus promoting sustainability. 3DGP technology is still evolving, and researchers are striving to develop high-performance printable materials and different methods to improve its robustness and efficiency. Carbon-based nanomaterials (CBNs) with beneficial properties have a wide range of applications in various fields, including as concrete/geopolymer systems in construction. This paper comprehensively reviews the research progress on carbon-based nanomaterials (CBNs) used to develop extrusion-based 3D geopolymer printing (3DGP) technology, including dispersion techniques, mixing methods, and the materials′ performance. The rheological, mechanical, durability, and other characteristics of these materials are also examined. Furthermore, the existing research limitations and the prospects of using 3DGP technology to produce high-quality composite mixtures are critically evaluated. 相似文献
95.
Akhtar Hayat Amina Rhouati Rupesh K. Mishra Gustavo A. Alonso Muhammad Nasir Georges Istamboulie 《International journal of environmental analytical chemistry》2016,96(3):237-246
Herein, we reported a titanium oxide (TiO2) modified activated carbon nanocomposite that showed advantageous characteristics in terms of electro-conductivity, catalytic activity and surface area. The designed nanocomposite was employed to modify the screen printed carbon electrode transducer surface in the construction of an electrochemical sensor. The electrode surface modification was characterised by cyclic voltammetry and impedimetric studies. The modified transducer surface was subsequently used for the detection of four phenolic endocrine disruptors, p-nitrophenol, hydroquinone, catechol and 1-naphtol. Under optimal conditions, TiO2 modified activated carbon sensor was evaluated by differential pulse voltammetry showing a good linearity with correlation coefficients higher than 0.99. It showed, in parallel, a high sensitivity where the detection limits were 348 ng/L, 110.1 ng/L, 3.3 ng/L and 7.2 µg/L for the respective studied compounds (S/N = 3). Finally, we validated the method with river water samples, and good recovery values were obtained showing the potential application of the reported biosensor. 相似文献
96.
Open‐Pore Two‐Dimensional MFI Zeolite Nanosheets for the Fabrication of Hydrocarbon‐Isomer‐Selective Membranes on Porous Polymer Supports 下载免费PDF全文
Han Zhang Prof. Qiang Xiao Prof. Xianghai Guo Prof. Najun Li Prashant Kumar Neel Rangnekar Mi Young Jeon Prof. Shaeel Al‐Thabaiti Prof. Katabathini Narasimharao Prof. Sulaiman Nasir Basahel Prof. Berna Topuz Frank J. Onorato Prof. Christopher W. Macosko Prof. K. Andre Mkhoyan Prof. Michael Tsapatsis 《Angewandte Chemie (International ed. in English)》2016,55(25):7184-7187
Two‐dimensional zeolite nanosheets that do not contain any organic structure‐directing agents were prepared from a multilamellar MFI (ML‐MFI) zeolite. ML‐MFI was first exfoliated by melt compounding and then detemplated by treatment with a mixture of H2SO4 and H2O2 (piranha solution). The obtained OSDA‐free MFI nanosheets disperse well in water and can be used for coating applications. Deposits made on porous polybenzimidazole (PBI) supports by simple filtration of these suspensions exhibit an n‐butane/isobutane selectivity of 5.4, with an n‐butane permeance of 3.5×10?7 mol m?2 s?1 Pa?1 (ca. 1000 GPU). 相似文献
97.
A novel antimicrobial flavonoid from the stem bark of Commiphora pedunculata (Kotschy & Peyr.) Engl.
Nasir Tajuddeen Muhammad S. Sallau Aliyu M. Musa Sani M. Yahaya James D. Habila Abdullahi Musa Ismail 《Natural product research》2016,30(10):1109-1115
A new flavonoid, 2-(3,5-dihydroxy-4-methoxy-phenyl)-3,5-dihydroxy-8,8-dimethyl-2,3-dihydro-8H-pyrano[3,2]chromen-4-one, together with previously reported epicatechin was isolated from the ethyl acetate soluble fraction of the methanol extract of the stem bark of Commiphora pedunculata. The structures of these compounds were elucidated based on extensive analysis of their spectral data, including 1 and 2D NMR. The compounds were active against 9 out of 12 tested microorganisms including a resistant strain; vancomycin-resistant entrococci (VRE), Escherichia coli, Staphylococcus aureus and Candida albicans. The zones of inhibition ranged between 22 and 34 mm against the microorganisms. The minimum inhibitory concentration was as low as 6.25 μg/mL against Shigella dysentriae, Bacillus cereus and S. aureus while the minimum bactericidal concentration was as low as 50 μg/mL against Pseudomonas aeruginosa, VRE and C. albicans. This is the first report of the isolation of the compound. 相似文献
98.
Muhammad Imran Abdul Qudair Baig Haidar Ali Shafiq Ur Rehman 《Periodica Mathematica Hungarica》2016,73(1):100-119
Topological indices are numerical parameters of a graph which characterize its topology and are usually graph invariant. In QSAR/QSPR study, physico-chemical properties and topological indices such as the Randi?, the atom-bond connectivity (ABC) and the geometric-arithmetic (GA) indices are used to predict the bioactivity of chemical compounds. Graph theory has found a considerable use in this area of research. In this paper, we study poly honeycomb networks which are generated by a honeycomb network of dimension n and derive analytical closed results for the general Randi? index \(R_\alpha (G)\) for different values of \(\alpha \), for a David derived network \((\textit{DD}(n))\) of dimension n, a dominating David derived network \((\textit{DDD}(n))\) of dimension n as well as a regular triangulene silicate network of dimension n. We also compute the general first Zagreb, ABC, GA, \(\textit{ABC}_4\) and \(\textit{GA}_5\) indices for these poly honeycomb networks for the first time and give closed formulas of these degree based indices in case of poly honeycomb networks. 相似文献
99.
100.