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991.
Chemical functionalization of C60 fullerene with one to six carbene (CH2) molecule(s) has been investigated using density functional theory. We have found that the reaction is regioselective so that a CH2 molecule prefers to be adsorbed atop a C–C bond which is shared between two hexagonal rings of the C60, releasing energy of ?3.95 eV. Singly occupied molecular orbital (SOMO) of the CH2 interacts with LUMO of the C60 via a [2 + 1] cycloaddition reaction. Energy of the reaction and work function of the system are decreased by increasing the number of adsorbed CH2 molecules. The HOMO/LUMO energy gap of C60 is slightly changed and the electron emission from its surface is facilitated upon the functionalization. 相似文献
992.
Mario?ThevisEmail author Andreas?Thomas Wilhelm?Sch?nzer 《Analytical and bioanalytical chemistry》2013,405(30):9655-9667
Urine samples have been the predominant matrix for doping controls for several decades. However, owing to the complementary information provided by blood (as well as serum or plasma and dried blood spots (DBS)), the benefits of its analysis have resulted in continuously increasing appreciation by anti-doping authorities. On the one hand, blood samples allow for the detection of various different methods of blood doping and the abuse of erythropoiesis-stimulating agents (ESAs) via the Athlete Biological Passport; on the other hand, targeted and non-targeted drug detection by means of chromatographic–mass spectrometric methods represents an important tool to increase doping control frequencies out-of-competition and to determine drug concentrations particularly in in-competition scenarios. Moreover, blood analysis seldom requires in-depth knowledge of drug metabolism, and the intact substance rather than potentially unknown or assumed metabolic products can be targeted. In this review, the recent developments in human sports drug testing concerning mass spectrometry-based techniques for qualitative and quantitative analyses of therapeutics and emerging drug candidates are summarized and reviewed. The analytical methods include both low and high molecular mass compounds (e.g., anabolic agents, stimulants, metabolic modulators, peptide hormones, and small interfering RNA (siRNA)) determined from serum, plasma, and DBS using state-of-the-art instrumentation such as liquid chromatography (LC)–high resolution/high accuracy (tandem) mass spectrometry (LC-HRMS), LC–low resolution tandem mass spectrometry (LC-MS/MS), and gas chromatography–mass spectrometry (GC-MS). 相似文献
993.
Mohammad Reza Hadjmohammadi S. Saman S. J. Nazari 《Journal of separation science》2013,36(23):3667-3672
The simultaneous isocratic separation of a mixture of five phenolic acids and four flavonoids (two important groups of natural polyphenolic compounds with very different polarities) was investigated in three different RPLC modes using a hydro‐organic mobile phase, and mobile phases containing SDS at concentrations below and above the critical micellar concentration (submicellar LC and micellar LC (MLC), respectively). In the hydro‐organic mode, methanol and acetonitrile; in the submicellar mode methanol; and in the micellar mode, methanol and 1‐propanol were examined individually as organic modifiers. Regarding the other modes, MLC provided more appropriate resolutions and analysis time and was preferred for the separation of the selected compounds. Optimization of separation in MLC was performed using an interpretative approach for each alcohol. In this way, the retention of phenolic acids and flavonoids were modeled using the retention factors obtained from five different mobile phases, then the Pareto optimality method was applied to find the best compatibility between analysis time and quality of separation. The results of this study showed some promising advantages of MLC for the simultaneous separation of phenolic acids and flavonoids, including low consumption of organic solvent, good resolution, short analysis time, and no requirement of gradient elution. 相似文献
994.
Hamid?Mofakham Rahim?Ghadari Ahmad?ShaabaniEmail author Milad?Pedarpour Sabrieh?Ghasemi 《Journal of the Iranian Chemical Society》2013,10(2):307-317
In this work, functionalized pyrimidine-2,4-dione-, benzo[g]-, and dihydropyrano[2,3-g]chromene derivatives have been synthesized via a Michael addition of 2-hydroxy-1,4-naphthoquinone or 2,5-dihydroxy-1,4-benzoquinone to the Knoevenagel condensation product of an aldehyde with Meldrum’s acid, dimedone or barbituric acid in the presence of a catalytic amount of l-proline under refluxing conditions in water in good to excellent yields. 相似文献
995.
Mohammad Ali Taher Maryam Fayazi Behjat Pooramiri Masoud Ghanei-Motlagh Ali Dorehgiraee 《Journal of the Iranian Chemical Society》2013,10(1):151-159
A new solvent polymeric membrane (PME) and coated graphite (CGE) electrodes based on 3-amino-2-mercapto-3H-quinazolin-4-one as a suitable carrier for La(III) ion are described. The sensors exhibited a Nernstian response for La(III) ion over a wide concentration range (3.0 × 10?7 to 1.0 × 10?1 M for PME and 1.0 × 10?7 to 1.0 × 10?1 M for CGE) with a slope of 20.1 ± 0.3 (PME) and 23.4 ± 0.4 (CGE) mV decade?1. The lower detection limits by PME and CGE were 2.0 × 10?7 and 7.1 × 10?8 M, respectively. The potentiometric response of the proposed electrodes was independent of the pH of the test solution in the pH range 3.0–9.0 with a fast response time (<10 s). The applications of prepared sensors were demonstrated in the determination of lanthanum ions in spiked water sample and also utilized for indirect determination of fluoride content of two mouth wash preparation samples. 相似文献
996.
Mohammad Abbasi Mohammad Reza Mohammadizadeh Zeinab Khatoon Taghavi 《Journal of the Iranian Chemical Society》2013,10(2):201-205
An efficient and odorless synthesis of disulfides from alkyl halides using thiourea and elemental sulfur in the presence of sodium carbonate in wet polyethylene glycol (PEG 200) at 40 °C without contamination by higher polysulfides has been developed. This procedure was then extended to preparation of disulfides from alkyl tosylates at 70 °C. 相似文献
997.
Ranjith?Munigunti Symon?Gathiaka Orlando?Acevedo Rajnish?Sahu Babu?Tekwani Angela?I?CalderónEmail author 《Chemistry Central journal》2013,7(1):175
Background
The compounds 1,4-napthoquinone (1,4-NQ), bis-(2,4-dinitrophenyl)sulfide (2,4-DNPS), 4-nitrobenzothiadiazole (4-NBT), 3-dimethylaminopropiophenone (3-DAP) and menadione (MD) were tested for antimalarial activity against both chloroquine (CQ)-sensitive (D6) and chloroquine (CQ)-resistant (W2) strains of Plasmodium falciparum through an in vitro assay and also for analysis of non-covalent interactions with P. falciparum thioredoxin reductase (PfTrxR) through in silico docking studies.Results
The inhibitors of PfTrxR namely, 1,4-NQ, 4-NBT and MD displayed significant antimalarial activity with IC50 values of?<?20 μM and toxicity against 3T3 cell line. 2,4-DNPS was only moderately active. In silico docking analysis of these compounds with PfTrxR revealed that 2,4-DNPS, 4-NBT and MD interact non-covalently with the intersubunit region of the enzyme.Conclusions
In this study, tools for the identification of PfTrxR inhibitors using phenotyphic screening and docking studies have been validated for their potential use for antimalarial drug discovery project.998.
999.
Maria V. Dinu Maria Cazacu Ecaterina S. Dr?gan 《Central European Journal of Chemistry》2013,11(2):248-258
The mechanical, rheological, thermal, and surface behaviors of three polyacrylamide/dextran (PAAm/Dx) semi-interpenetrating polymer network (semi-IPN) hydrogels, prepared at 22°C, 5°C and ?18°C, were investigated. The results were compared with those obtained on cross-linked PAAm without Dx synthesized under the same conditions. Hydrogels prepared at the lowest temperature were the most mechanically stable. The thermal stability of the semi-IPN hydrogels is slightly lower than the corresponding PAAm gels, irrespective of preparation temperature. The water vapor sorption capacity depended on the presence of Dx as well as preparation temperature, which determines the network morphology. 相似文献
1000.
Joanna Augustynowicz Anna M. Ko?ton Agnieszka M. Baran Anna M. Kostecka-Guga?a Wojciech W. Lasek 《Central European Journal of Chemistry》2013,11(2):295-303
The present work focused on the qualitative and quantitative analysis of Cr detoxification strategy of aquatic cosmopolitan plant Callitriche cophocarpa. This plant species has just been described in the context of its unusual accumulation potential of Cr. The emphasis of the work was placed on the redox reaction Cr(VI)→Cr(III) which is considered to be remediation mechanism of highly reactive and mobile Cr(VI) ions. Plants were immersed for 5 days in 1 mM of Cr(VI) (potassium dichromate) or 1 mM of Cr(III) (chromium sulphate) solutions in semi-natural conditions. Cr was effectively removed from the solution up to the extent of ca.58% or 35% of the starting amount, in the case of Cr(III) and Cr(VI), respectively. No plant-induced Cr(VI) reduction accompanying Cr accumulation was observed in Cr(VI) solutions except from the apparent one, noticed at the fourth day of incubation. On the contrary to these results, according to the method of electron paramagnetic resonance spectroscopy (L-band EPR), biphasic signal of Cr(V) attending Cr(VI) to Cr(III) reduction was detected inside the plant tissue every day of investigations. Our results show that phytoextraction but not phytostabilization is the main strategy of Cr detoxification by C. cophocarpa in aquatic systems. 相似文献