排序方式: 共有97条查询结果,搜索用时 859 毫秒
51.
Ahmet Bilgin Çiğdem Yağcı Ayşegül Mendi Ufuk Yıldız 《Journal of inclusion phenomena and macrocyclic chemistry》2010,67(3-4):377-383
Synthesis of metal-free and metallophthalocyanines bearing α-methylferrocenylmethoxy units was described. Precursor 3 required for the preparation of phthalocyanines 4–9, was synthsized by the nucleophilic aromatic substitution reaction between α-methylferrocenylmethanol and 4-nitrophthalonitrile in dry DMF. The metal-free phthalocyanine 4 was prepared from 4-(α-methylferrocenylmethoxy)phthalonitrile 3 in 1-pentanol with a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Metallophthalocyanines (M = Zn, Cu, Co, Ni and Pb) were prepared by cyclotetramerization reaction of phthalonitrile with appropriate materials. The phthalonitrile, metal-free and metallophthalocyanines were characterized by 1H and 13C NMR, FT-IR UV–Vis and mass spectral data, as well as elemental analyses, which were consistent with the proposed structures. 相似文献
52.
Burak Bilgin Patrick De Causmaecker Benoît Rossie Greet Vanden Berghe 《Annals of Operations Research》2012,194(1):33-57
A novel nurse rostering model is developed to represent real world problem instances more accurately. The proposed model is
generic in the sense that it allows modelling of essentially different problem instances. Novel local search neighbourhoods
are implemented to take advantage of the problem properties represented by the model. These neighbourhoods are used in a variable
neighbourhood search and in an adaptive large neighbourhood search algorithm. The performance of the solution method is evaluated
empirically on real world data. The proposed model is open to further extensions for covering personnel planning problems
in different sectors and countries. 相似文献
53.
We present an algorithm that prepares thermal Gibbs states of one dimensional quantum systems on a quantum computer without any memory overhead, and in a time significantly shorter than other known alternatives. Specifically, the time complexity is dominated by the quantity N(‖h‖/T), where N is the size of the system, ‖h‖ is a bound on the operator norm of the local terms of the Hamiltonian (coupling energy), and T is the temperature. Given other results on the complexity of thermalization, this overall scaling is likely optimal. For higher dimensions, our algorithm lowers the known scaling of the time complexity with the dimension of the system by one. 相似文献
54.
Tunay Bilgin 《Czechoslovak Mathematical Journal》2005,55(3):691-697
The definition of lacunary strongly convergence is extended to the definition of lacunary strong (A
σ
, p)-convergence with respect to invariant mean when A is an infinite matrix and p = (p
i
) is a strictly positive sequence. We study some properties and inclusion relations. 相似文献
55.
Yuefeng Liu Thierry Dintzer Ovidiu Ersen Cuong Pham-Huu 《Journal of Energy Chemistry》2013,22(2):279-289
A new hierarchical composite consisted of multi-walled carbon nanotubes (CNTs) layer anchored on macroscopic α-Al2O3 host matrix was synthesized and used as support for Fischer-Tropsch synthesis (FTS). The composite constituted by a thin shell of a homogeneous, highly entangled and structure-opened carbon nanotubes network and it exhibited a relatively high and fully accessible specific surface area of 76 m2·g?1, compared with that of 5 m2·g?1 of the original α-Al2O3 support. The metal-support interaction between carbon nanotubes surface and cobalt precursor and high effective surface area led to a relatively high dispersion of cobalt nanoparticles. This hierarchically supported cobalt catalyst exhibited a high FTS activity along with an extremely high selectivity towards liquid hydrocarbons compared with the cobalt-based catalyst supported on pristine α-Al2O3 or on CNTs carriers. This improvement can attribute to the high accessibility of composite surface area comparing with the macroscopic host structure alone or to the bulk CNTs where the nanoscopic dimension induced a dense packing with low mass transfer which favoured the problem of reactants competitive diffusion towards the cobalt active site. In addition, intrinsic thermal conductivity of decorated CNTs could help the heat dissipating throughout the catalyst body, thus avoiding the formation of local hot spots which appeared in high CO conversion under pure syngas feed in FTS reaction. Cobalt supported on CNTs decorated α-Al2O3 catalyst also exhibited satisfied high stability during more than 200 h on stream under relatively severe conditions compared with other catalysts reported in the literature. Finally, the macroscopic shape of such composite easily rendered its usage as catalyst support in a fixed-bed configuration without facing problems of transport and pressure drop as encountered with the bulk CNTs. 相似文献
56.
Ioana Fechete Bertrand DonnioOvidiu Ersen Thierry DintzerAmel Djeddi François Garin 《Applied Surface Science》2011,257(7):2791-2800
Highly ordered W-MCM-48 mesoporous materials containing isolated W atoms in tetrahedral framework positions were successfully synthesized following the S+I− pathway, up to a Si/W of 40. When tungsten content was increased up to a Si/W of 20, the ordered cubic structure was only partially maintained, and for a Si/W of 10 an amorphous phase was obtained. Highly isolated tetrahedral framework tungsten atoms in the W-MCM-48 with a Si/W of 40, have been identified by UV-vis band at 225 nm, IR-TF band at 970 cm−1 and XRD. The W 4f XPS results suggest that the tungsten atoms exist in two oxidation states, W4+ and W5+. The morphology of the samples varies as a function of tungsten content. The W-MCM-48 samples with a Si/W ratio of 40 existed as crystals with a unique crystalline morphology consisting of cubes truncated rhombic dodecahedrons belonging to the cubic Ia3d space group, while the samples with a Si/W ratio of 20 exhibited a different morphology consisting of spheres and cubes truncated by rhombic dodecahedrons. A comparison of samples with Si/W of ∞, Si/W of 40 and Si/W of 20 was performed using the conversion of MCP carried out at 450 °C under H2. 相似文献
57.
A novel series of N′‐(substituted benzylidene)‐2‐(5,6‐dichloro‐2‐methyl‐1H‐benzimidazol‐1‐yl)acetohydrazides and N′‐(1‐(substituted phenyl)ethylidene)‐2‐(5,6‐dichloro‐2‐methyl‐1H‐benzimidazol‐1‐yl)acetohydrazides were synthesized and then studied for their urease inhibitory activities using thiourea as a standard drug. All newly synthesized compounds were found to exhibit potent inhibitory properties against urease enzyme in the range of IC50 = 0.0155 ± 0.0039–0.0602 ± 0.0071 μM, when compared with the thiourea as standard (IC50 = 0.5115 ± 0.0233 μM). All target molecules were characterized by 1H‐NMR, 13C‐NMR, IR, and electrospray ionization mass spectrometry. 相似文献
58.
Bilgin MD al Akhras MA Khalili M Hemmati H Grossweiner LI 《Photochemistry and photobiology》2000,72(1):121-127
Lutetium (III) texaphyrin photosensitizes postirradiation or "delayed" photohemolysis (DPH) of human and bovine red blood cells at 730 nm by a Type-2 pathway mediated by singlet molecular oxygen. The DPH rate increases with increasing incubation temperature and with the second power of the incident fluence. The experimental DPH curves are in good agreement with a multi-hit kinetics model based on target theory. 相似文献
59.
Enzymatic oxidative polymerization of para‐imine functionalized phenol catalyzed by horseradish peroxidase
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Enzymatic oxidative polymerization of a new para‐imine functionalized phenol derivative, 4‐(4‐hydroxybenzylideneamino)benzoic acid (HBBA), using horseradish peroxidase enzyme and hydrogen peroxide oxidizer has been investigated in an equivolume mixture of an organic solvent (acetone, methanol, ethanol, dimethylformamide, 1,4‐dioxane, and tetrahydrofuran) and phosphate buffer (pH = 5.0, 6.0, 6.8, 7.0, 7.2, 8.0, and 9.0) at different temperatures under air for 24 h. The resulting oligomer, oligo(4‐(4‐hydroxybenzylideneamino)benzoic acid) [oligo(HBBA)], was characterized using ultraviolet–visible, Fourier transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR), cyclic voltammetry, size exclusion chromatography, differential scanning calorimetry, and thermogravimetric analyses. Polymerization involved carbon dioxide and hydrogen elimination from the monomer, and terminal units of the oligomer structure consisted of phenolic hydroxyl (–OH) groups at the ends. The polymer is mainly composed of a mixture of phenylene and oxyphenylene units according to 1H NMR and FT‐IR analyses. Effects of solvent system, temperature and buffer pH on the polymerization have been investigated in respect to the yield and molecular weight (Mn) of the product. The best condition in terms of the highest molecular weight (Mn = 3000 g/mol, DP ~ 15) was achieved in an equivolume mixture of 1,4‐dioxane/pH 5.0 phosphate buffer condition at 35°C. Electrochemical characterization of oligo(HBBA) was investigated at different scan rates. The resulting oligomer has also shown relatively high thermal stability according to thermogravimetric analysis. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
60.
Haijun Peng Dr. Jésus Raya Dr. Fanny Richard Dr. Walid Baaziz Prof. Ovidiu Ersen Dr. Artur Ciesielski Prof. Paolo Samorì 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19770-19777
Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have attracted enormous attention in recent years. Recently, MOF@COF are emerging as hybrid architectures combining the unique features of the individual components to enable the generation of materials displaying novel physicochemical properties. Herein we report an unprecedented use of aza-Diels–Alder cycloaddition reaction as post-synthetic modification of MOF@COF-LZU1, to generate aza-MOFs@COFs hybrid porous materials with extended π-delocalization. A a proof-of-concept, the obtained aza-MOFs@COFs is used as electrode in supercapacitors displaying specific capacitance of 20.35 μF cm−2 and high volumetric energy density of 1.16 F cm−3. Our approach of post-synthetic modification of MOFs@COFs hybrids implement rational design for the synthesis of functional porous materials and expands the plethora of promising application of MOFs@COFs hybrid porous materials in energy storage applications. 相似文献