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991.
Preparation of a novel sorptive stir bar based on vinylpyrrolidone‐ethylene glycol dimethacrylate monolithic polymer for the simultaneous extraction of diazepam and nordazepam from human plasma 下载免费PDF全文
Mahsa Torabizadeh Zahra Talebpour Nuoshin Adib Hassan Y. Aboul‐Enein 《Journal of separation science》2016,39(7):1316-1325
A new monolithic coating based on vinylpyrrolidone‐ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The polymerization step was performed using different contents of monomer, cross‐linker and porogenic solvent, and the best formulation was selected. The quality of the prepared vinylpyrrolidone‐ethylene glycol dimethacrylate stir bars was satisfactory, demonstrating good repeatability within batch (relative standard deviation < 3.5%) and acceptable reproducibility between batches (relative standard deviation < 6.0%). The prepared stir bar was utilized in combination with ultrasound‐assisted liquid desorption, followed by high‐performance liquid chromatography with ultraviolet detection for the simultaneous determination of diazepam and nordazepam in human plasma samples. To optimize the extraction step, a three‐level, four‐factor, three‐block Box–Behnken design was applied. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for diazepam (36–1200 ng/mL) and nordazepam (25–1200 ng/mL), with correlation coefficients of 0.9986 and 0.9968 and detection limits of 12 and 10 ng/mL, respectively. The intra‐ and interday recovery ranged from 93 to 106%, and the relative standard deviations were less than 6%. Finally, the proposed method was successfully applied to the analysis of diazepam and nordazepam at their therapeutic levels in human plasma. The novelty of this study is the improved polarity of the stir bar coating and its application for the simultaneous extraction of diazepam and its active metabolite, nordazepam in human plasma sample. The method was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of diazepam and nordazepam in biological fluids. 相似文献
992.
Surface Charge‐Transfer Doping of Graphene Nanoflakes Containing Double‐Vacancy (5‐8‐5) and Stone–Wales (55‐77) Defects through Molecular Adsorption 下载免费PDF全文
The adsorption of six electron donor–acceptor (D/A) organic molecules on various sizes of graphene nanoflakes (GNFs) containing two common defects, double‐vacancy (5‐8‐5) and Stone–Wales (55‐77), are investigated by means of ab initio DFT [M06‐2X(‐D3)/cc‐pVDZ]. Different D/A molecules adsorb on a defect graphene (DG) surface with binding energies (ΔEb) of about ?12 to ?28 kcal mol?1. The ΔEb values for adsorption of molecules on the Stone–Wales GNF surface are higher than those on the double vacancy GNF surface. Moreover, binding energies increase by about 10 % with an increase in surface size. The nature of cooperative weak interactions is analyzed based on quantum theory of atoms in molecules, noncovalent interactions plot, and natural bond order analyses, and the dominant interaction is compared for different molecules. Electron density population analysis is used to explain the n‐ and p‐type character of defect graphene nanoflakes (DGNFs) and also the change in electronic properties and reactivity parameters of DGNFs upon adsorption of different molecules and with increasing DGNF size. Results indicate that the HOMO–LUMO energy gap (Eg) of DGNFs decreases upon adsorption of molecules. However, by increasing the size of DGNFs, the Eg and chemical hardness of all complexes decrease and the electrophilicity index increases. Furthermore, the values of the chemical potential of acceptor–DGNF complexes decrease with increasing size, whereas those of donor–DGNF complexes increase. 相似文献
993.
Zahra Alimohammadi Keyvani Prof. Dr. Shant Shahbazian Prof. Dr. Mansour Zahedi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):5003-5009
The “atoms in molecules” structures of 225 unsubstituted hydrocarbons are derived from both the optimized and the promolecule electron densities. A comparative analysis demonstrates that the molecular graphs derived from these two types of electron densities at the same geometry are equivalent for almost 90 % of the hydrocarbons containing the same number and types of critical points. For the remaining 10 % of molecules, it is demonstrated that by inducing small perturbations, through the variation of the used basis set or slight changes in the used geometry, the emerging molecular graphs from both densities are also equivalent. Interestingly, the (3, ?1) critical point between two “non‐bonded” hydrogen atoms, which triggered “H?H bonding” controversy is also observed in the promolecule densities of certain hydrocarbons. Evidently, the topology of the electron density is not dictated by chemical bonds or strong interactions and deformations induced by the interactions of atoms in molecules have a quite marginal role, virtually null, in shaping the general traits of the topology of molecular electron densities of the studied hydrocarbons, whereas the key factor is the underlying atomic densities. 相似文献
994.
DSC-measurements show in a simple and convincing manner that the precipitation of the metastableS-phase in an Al-2.1% Cu-1.3% Mg alloy is enhanced in the presence of lattice defects (dislocation loops, helices, dislocations), but is little influenced by pre-existing GPB-zones.
We are greatly indebted to Centre de Recherches de Voreppe S. A. for the preparation of the alloy. 相似文献
Zusammenfassung DSC-Untersuchungen zeigen auf einfache und überzeugende Weise, da\ die Bildung der metastabilen S-Phase in einer Al-Cu-Mg-Legierung (Al-2.1%, Cu 1.3 %Mg) in Gegenwart von Gitterdefekten (Versetzungsringe, Wendeln, Versetzungen) gesteigert, aber durch vorherige GPB-Zonen nur wenig beeinflu\t wird.
We are greatly indebted to Centre de Recherches de Voreppe S. A. for the preparation of the alloy. 相似文献
995.
Zahra Azarkamanzad Faezeh Farzaneh Mahboobeh Maghami Jim Simpson Mohammad Azarkish 《应用有机金属化学》2018,32(3)
The 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) undergoes hydrolysis in the presence of VO(SO4) in an alkaline solution, affording mainly the bis(2‐pyridyl carbonyl)amid ) VO2 complex, designated as [VO2(bpca)]. Single‐crystal X‐ray crystallography revealed that the coordination of V in complex is a distorted square‐pyramid coordinated with three nitrogen of bis(2‐pyridyl carbonyl)amid ) ligand and two binding oxygen atoms. The prepared complex which successfully supported on modified Fe3O4 nanoparticles using tetraethylorthosilicate (TEOS) and (3‐aminopropyl)trimethoxysilane(APTMS)was designated as Fe3O4@SiO2@APTMS@[VO2(bpca)] complex (nanocatalyst). The complex and nanocatalyst were characterized by means of FT‐IR, XRD, VSM, SEM and TEM. The catalytic activity of [VO2(bpca)] complex and Fe3O4@SiO2@APTMS@complex as catalysts 1 and 2 were evaluated by the epoxidation of geraniol , 3‐methyl‐2‐buten‐1‐ol , trans‐2‐hexen‐1‐ol and 1‐octen‐3‐ol with 70–98% conversions and 95–100% selectivities. Based on the obtained results, the heterogeneity and reusability of the catalyst seems promising. In addition, the in vitro antibacterial activity of [VO2 (bpca)] complex have also been evaluated and compared to the activities of other vanadium complexes, tptz ligand and two standard antibacterial drugs, Nalidixic acid and Vancomycin. 相似文献
996.
Masood Fereidoonnezhad Hamid R. Shahsavari Elaheh Lotfi Mojgan Babaghasabha Motahareh Fakhri Zeinab Faghih Zahra Faghih M. Hassan Beyzavi 《应用有机金属化学》2018,32(3)
The reaction of [(Me2S)AuCl] with an equimolar amount of benzyl isocyanide (PhCH2NC) ligand led to the formation of complex [(PhCH2NC)AuCl] ( 1 ). The solid‐state structure of 1 was determined using the X‐ray diffraction method. Through a salt metathesis reaction, the chloride ligand in 1 was replaced by pyrimidine‐2‐thiolate (SpyN?) to afford the complex [(PhCH2NC)Au(η1‐S‐Spy)] ( 2 ), which was characterized spectroscopically. The cytotoxic activities of 1 and 2 were evaluated against three human cancer cell lines: ovarian carcinoma (SKOV3), lung carcinoma (A549) and breast carcinoma (MCF‐7). Complex 2 showed higher cytotoxicity than cisplatin against SKOV3 and MCF‐7 cancer cell lines. It showed a strong anti‐proliferative activity with IC50 of 7.80, 6.26 and 6.14 μM, compared with that measured for cisplatin which was 7.62, 12.36 and 11.47 μM, against A549, SKOV3 and MCF‐7 cell lines, respectively. The induction of cellular apoptosis by 2 was also studied on MCF‐7 cell line. Our results indicated that 2 could induce apoptosis in cancerous cells in a dose‐dependent manner. 相似文献
997.
Zahra Dehghani Firouzabadi Ali Mohammad Haji Shabani Mohammad Hassan Ehrampoush Elaheh Nourbala Tafti 《International journal of environmental analytical chemistry》2018,98(6):555-569
A novel magnetic dispersive solid phase extraction method using magnetic multi-walled carbon nanotubes modified with 5-mercapto-3-phenyl-1,3,4-thiadiazole-2-thione potassium salt (bismuthiol II) (MMWCNTs@Bis) as the sorbent was developed for the separation and preconcentration of inorganic selenium (IV) prior to its determination by electrothermal atomic absorption spectrometry. The prepared MMWCNTs@Bis sorbent was characterised by Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer and X-ray diffraction. Total selenium was determined after reduction of Se(VI) to Se(IV) by addition of hydrochloric acid and heating the mixture in a boiling water bath. Se(VI) concentration was determined from the difference between the amounts of total selenium and Se(IV). Under the optimised experimental conditions, an enhancement factor of 196 and a detection limit (based on 3Sb/m) of 0.003 µg L?1 was obtained for aqueous samples. The relative standard deviation at 0.1 µg L?1 concentration level of Se(IV) (n = 6) was found to be 5.2 and 7.7% for intra- and inter-day analysis, respectively. The method was successfully applied to the determination of inorganic selenium species in water and total selenium in food samples. 相似文献
998.
999.
Zahra Hassani Mohammad Reza Islami Arman Moradi Moazameh Yazdi Rouh-Alamini 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):568-577
Stabilized phosphorus ylides were obtained from the three-component reaction between dialkyl acetylenedicarboxylate and sulfur compounds such as pyridine-2-thione, 2-furylmethanethiol, ethanedithioamide, and N-phenyl-1,2,4-triazole-3-thiol in the presence of triphenylphosphine in excellent yields. 相似文献
1000.
Mohammad Mazloum-Ardakani Zahra Dehghani Alireza Khoshroo 《Journal of the Iranian Chemical Society》2018,15(5):1061-1068
In this paper, the use of molecular self-assembled monolayers of 5-(1,3-dithiolan-2-eyl)-3-methyl banzen-1,2-diol (DMD) on gold nanoparticles was described (DMD-AuNPs). The redox properties of modified electrode at various scan rates were investigated by cyclic voltammetry. A pair of well-defined quasi-reversible redox peaks of DMD were obtained at the modified electrode. Dramatically enhanced electrocatalytic activity was exemplified at the DMD-AuNPs, as an electrochemical sensor to investigate the electro-oxidation of isoprenaline (IP). With this modified electrode, the oxidation potential of the IP was shifted about 235 mV toward a less positive potential value than that of an unmodified electrode. The values of electron transfer coefficients (α = 0.5), catalytic rate constant (ks = 9.2 s?1) and diffusion coefficient (D = 8.9 × 10?5 cm2 s?1) were calculated for IP. The response of catalytic current with IP concentration showed a linear relation in the range from 0.5 to 800 µM with a detection limit of 0.21 µM. Finally, this modified electrode was used for the determination of IP in IP injections. 相似文献