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91.
Journal of Algebraic Combinatorics - We study those multiplicative subgroups of $${\mathbb F}_{2^n}^*$$ which are Sidon sets and/or sum-free sets in the group $$({\mathbb F}_{2^n},+)$$ . These... 相似文献
92.
This paper presents a chemometrics-assisted optimization study to improve the separation of tocopherol (-T) and tocotrienol (-TT) homologues on a C30 stationary phase in reversed-phase HPLC. The HPLC settings were optimized using a central composite design and the response surface methodology. Flow rate, column temperature, and mobile phase composition were chosen as independent variables. Peak resolution (Rs), analysis time (tR), and peak symmetries of the tocopherol isomers were chosen as response variables. Optimum performance in terms of Rs was obtained at a flow rate of 0.31 mL min?1, a temperature of 8.70 °C, and % B content (methyl tert-butyl ether: methanol: water, 80:18:2, v/v/v) in the mobile phase of 38.12%. The analysis of variance and regression analysis gave adjusted R2 values of 0.9841 for Rs, 0.9850 for tR-(α-T), 0.9853 for tR-(β-T), and 0.9204 for the peak symmetry of β-T. This confirms the good agreement of experimental data with predicted values. The close eluting peaks of β-/γ-tocol could be baseline separated at the optimized conditions at a minimized analysis time. Empirical second-order polynomial models were derived that gave statistically high significances (P?<?0.0001). Hence, the models can be successfully employed to predict the optimum separation conditions of co-eluting peaks of β-/γ-tocols. The optimized method was successfully applied to determine the individual tocol homologues in various cold pressed edible oils. Total contents ranged from 15 to almost 2600 mg tocol kg?1 oil. 相似文献
93.
Aïcha Arfaoui Fatma Saâdi Asma Bourafai Aziez Hammouda Chebbi Catherine Fressigné Julien Legros 《合成通讯》2018,48(6):705-713
An efficient coupling reaction of allyl bromides with various alcohols as nucleophiles activated by triethylamine, leading to functionalized vinyl ethers in good yields and with full stereoselectivity. 相似文献
94.
Balram P. Baranwal Talat Fatma Rinkoo D. Gupta Tarkeshwar Gupta 《Transition Metal Chemistry》2007,32(4):501-506
Oxo-centered, trinuclear, mixed-ligand complexes of chromium(III) have been synthesized by stepwise substitutions of acetate
ions of [Cr3O(OOCMe)4(OOCR)3] · 3MeOH (1) and the isolated products of the type [Cr3O(OOCMe)2 (SB)(OOCR)3]PF6 · 3MeOH (2), [Cr3O(OOCMe)(SB)2(OOCR)3]PF6 · 3MeOH (3) and [Cr3O(SB)3(OOCR)3]PF6 · 3MeOH (4) [where R = C13H27 and HSB = C6H4(OH)CHNC6H4Cl] have been characterized by a full battery of complementary physico–chemical methods including spectral (infrared, electronic,
FAB mass and powder XRD) studies, elemental and thermogravimetric analyses, molar conductance and magnetic susceptibility
measurements. The infrared spectra suggest the bridging nature of both carboxylate and Schiff base anions along with ν
asym(Cr3O) vibrations in the complexes. The trinuclear nature of the complexes has been assessed from FAB mass data. Electronic spectra
and magnetic moment values were consistent with chromium(III) ion present in an octahedral environment which was supported
by their powder X-ray diffraction data. Cyclic voltammetric data of complex (4) indicate a reversible oxidation wave and an irreversible reduction wave in the range − 1.2–0.6 V. The decomposition pathway
of all the complexes has been discussed on the basis of thermogravimetric analysis data. Conductance data indicate the monocationic
nature of the complexes and their plausible structure has been established on the basis of above physico–chemical studies. 相似文献
95.
A photocatalytic degradation method was developed for polychlorobiphenyl (PCB) and organochloride pesticide (OCP) discrimination and quantification. A mixture of Aroclor 1260 and p,p′-DDT was irradiated at 254 nm by UV lamp (40 W) in the presence of TiO2 (30 mg mL−1 non-aqueous solution). Comparison of gas chromatograms showed that p,p′-DDT signals decreased significantly after irradiation, while Aroclor 1260s chromatograms did not show any difference before and after irradiation. Detection limits were 0.30 mg L−1 and 0.15 mg L−1 for p,p′-DDT and Aroclor 1260, respectively. The method was applied to spiked egg samples, the recoveries were found as 72% for DDT and 82.01% for Aroclor 1260. 相似文献
96.
Serpil Takaç Fatma Gül Boyac San Emine Kavdr 《Reaction Kinetics and Catalysis Letters》2005,85(2):291-298
Summary Bi-doped TiO2photocatalysts have been prepared by a sol-gel method. The samples were examined by the methods of XRD, HRTEM and XPS. The
photocatalytic activity of the catalysts was evaluated through the photocatalytic oxidation of p-nitroaniline (NO2C6H4NH2) in air. 相似文献
97.
Beyrul Canbaz Cem Onem Fatma Aydogmus K. Gediz Akdeniz 《Chaos, solitons, and fractals》2012,45(2):188-191
Recently we have investigated the role of the coupling constant in the evolution of the two dimensional spinor-type instantons (Thirring Instantons [1]) in phase space [2] via Heisenberg ansatz. In this paper we study the stability of bifurcation points of the Thirring Instanton’s behaviours in phase space. 相似文献
98.
Hümeyra Paaolu Ahmet Karada Fatma Tezcan Orhan Büyükgüngr 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(2):m93-m94
In the novel transition metal isothiocyanate complex of N‐(2‐hydroxyethyl)ethylenediamine (hydet‐en) with copper, [Cu(NCS)2(C4H12N2O)], the Cu atom lies in a distorted square‐pyramidal environment, coordinated by four N atoms in the basal plane and an apical O atom. The hydet‐en ligand is N,N,O‐tridentate, in contrast to the disposition in previously studied complexes, while the isothiocyanate ions act as N‐atom donor ligands. The monomeric units are linked to one another by hydrogen bonds. 相似文献
99.
Rajkumar Tulsawani Lorena S Kelly Nigar Fatma Bhavanaben Chhunchha Eri Kubo Anil Kumar Dhirendra P Singh 《BMC neuroscience》2010,11(1):125
Background
The ability to respond to changes in the extra-intracellular environment is prerequisite for cell survival. Cellular responses to the environment include elevating defense systems, such as the antioxidant defense system. Hypoxia-evoked reactive oxygen species (ROS)-driven oxidative stress is an underlying mechanism of retinal ganglion cell (RGC) death that leads to blinding disorders. The protein peroxiredoxin 6 (PRDX6) plays a pleiotropic role in negatively regulating death signaling in response to stressors, and thereby stabilizes cellular homeostasis. 相似文献100.
The C–S coupling reactions of aryl benzenesulfonates with phenylmagnesium bromide in THF:toluene (7:10) at 90 °C have been
studied. A Hammett-type kinetic study of the leaving group effect of aryloxy groups provides a conclusive support for a two
step addition-elimination mechanism in which C–S bond formation is rate determining step. 相似文献