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61.
Incipient separation over wall irregularities in a steady two dimensional flow field of a perfect fluid which has transonic speed characteristics has been investigated considering viscous-inviscid interactions at high Reynolds number. The aim of this work is to investigate dependence of the critical hump height (when a well attached flow over rigid body surface turns into a separated one) on the Karman–Guderley parameter which characterizes of the local flow field. The analysis of the flow field starts with the so-called inspection analysis of the flow properties and then the interaction problem has been constructed using the asymptotic analysis of triple-deck structure of interaction region. Finally, a method based on a semi-direct solution of governing equations of the transonic interaction problem has been used to obtain the numerical solution of the problem. 相似文献
62.
63.
In this paper, we establish several inequalities for some differantiable mappings that are connected with the Riemann-Liouville fractional integrals. The analysis used in the proofs is fairly elementary. 相似文献
64.
İzzet Amour Morkan Ayşe Uztetik Morkan Çiğdem Tuç Engin Kendi 《Journal of chemical crystallography》2008,38(7):541-545
Abstract Pentacarbonyl(4-methylpyridine)chromium(0) complex was isolated from n-hexane solution as yellow plate-like crystals and characterized by using X-ray crystallography. It crystallizes in the orthorhombic
system with the space group Cmcm and Z = 4. The unit cell parameters are a = 11.737(1) ?, b = 12.857(2) ?, c = 8.465(1) ?. The single crystal X-ray structure of the complex shows that the coordination sphere around the chromium central
atom is slightly distorted octahedron, involving the 4-methylpyridine (4-mp), ligand as a monodentate N-donor ligand and five
carbonyl groups. The four equatorial CO groups in the complex, with the Cr–C2 distance of 1.886 Ǻ, are slightly bent away
from the 4-methylpyridine ligand with the N–Cr–C2 angle of 91.69°. The pyridine ring plane makes an angle of 135.17° with
the Cr–N–CO bond axis. The thermal analysis (differential thermal analysis and thermal gravimetry) and IR spectra of the complex
indicated that the compound undergoes complete decomposition to form the Cr2O3 as the final decomposition product.
Index Abstract The crystal structure of pentacarbonyl(4-methylpyridine)chromium(0) complex has been determined and its thermal behavior has
also been studied.
相似文献
65.
A series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides were synthesized as N-heterocyclic carbene (NHC) precursors. These compounds were used to synthesize of the PEPPSI-type palladium NHC complexes. The structures of all compounds were characterized by 1H NMR, 13C NMR, FT-IR spectroscopy and elemental analyses. The catalytic activity of the PEPPSI-type palladium–NHC complexes has been evaluated with respect to the Suzuki-Miyaura cross-coupling reactions of phenyl boronic acid with various aryl halides in aqueous media. 相似文献
66.
The epoxy resins containing imine bonding were prepared from hydroxyl substituted Schiff base monomers in two steps. At the first step, hydroxyl substituted Schiff base monomers were synthesized via condensation reaction. At the second step, epoxy resins were synthesized from the reaction between Schiff base monomers and epichlorohydrine (EPC). Then curing processes of epoxy resins were achieved by p-phenylenediamine compound. The structures of resulting compounds were confirmed by FT-IR, UV-Vis and 1H-NMR. TG-DTA and DSC measurements were performed for thermal characterizations of the compounds. Chemical resistances of the cured epoxy-amine systems were determined for coating applications in acidic, alkaline and organic solvents. HCl (10%, aqueous solution), NaOH (10%, aqueous solution), DMSO, DMF, N-methylpyrrolidone, ethanol, THF and acetone were used for corrosion tests. Chemical resistance data of the synthesized epoxy resins demonstrated that they have good chemical resistance against various acid, alkaline and common organic solvents. Surface morphologies of epoxy resin and the cured epoxy resin were determined with scanning electron microscopy (SEM) measurements. Also, optical band gap (Eg) values of Schiff base monomers and epoxy resins were calculated from UV-Vis measurements. 相似文献
67.
Kerim Serbest Hakan Kayi Mustafa Er Kemal Sancak smail Deirmenciolu 《Heteroatom Chemistry》2008,19(7):700-712
Four new mononuclear metal complexes with a mononucleating Schiff base ligand containing two thiadiazoles units have been synthesized. The ligand and metal complexes were characterized by elemental analyses, IR, 1H, and 13C NMR, UV–vis, ESR, electrospray ionization mass spectra, and magnetic susceptibility measurements. Electronic spectra, magnetic susceptibility measurement, and molecular modeling studies support octahedral geometry around the Ni(II), Cu(II), and Zn(II) ions. The magnetic properties were investigated, and ferromagnetic coupling is observed in Cu(II) and Ni(II) complexes. In addition, total energy and heat of formation calculated for conformers of the Schiff base ligand by the semiempirical AM1 calculations have shown that E,Z‐isomer of the ligand is more stable (about 5.3 kcal/mol) than E,E‐ and Z,Z‐isomers. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:700–712, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20496 相似文献
68.
Duygu İNCİ 《应用有机金属化学》2020,34(12):e6016
NOO-type tridentate Schiff base, N-salicylidene-2-aminobenzoic acid, (H2L), and its ternary Cu (II) complex containing H2L Schiff base and 4,7-dimethyl-1,10-phenanthroline (4,7-dmphen), [Cu(4,7-dmphen)(H2L)]27H2O, have been synthesized and characterized by CHN analysis, ESI-MS, FTIR, and single-crystal X-ray diffraction techniques. The interaction of alone H2L Schiff base ligand and ternary Cu (II) complex with biomacramolecules {calf thymus DNA (CT-DNA) and bovine serum albumin (BSA)} has been investigated by electronic absorption and fluorescence spectroscopy. The experimental results indicate that H2L Schiff base ligand and ternary Cu (II) complex bind to CT-DNA by means of a moderate intercalation mode. Furthermore, the fluorescence quenching mechanism between H2L Schiff base ligand and ternary Cu (II) complex with BSA possesses a static quenching process. Radical scavenging activity of H2L Schiff base ligand and ternary Cu (II) complex was measured in terms of EC50, using the DPPH and H2O2 methods. Biomacromolecule interactions and scavenging activity studies revealed that ternary Cu (II) complex yielded better results than H2L Schiff base ligand alone. 相似文献
69.
Palladium(II)‐N‐heterocyclic carbene complexes: synthesis,characterization and catalytic application 下载免费PDF全文
N‐Heterocyclic carbenes (NHCs) are of great importance and are powerful ligands for transition metals. A new series of sterically hindered benzimidazole‐based NHC ligands (LHX) ( 2a , 2b , 2c , 2d , 2e , 2f ), silver–NHC complexes ( 3a , 3b , 3c , 3d , 3e , 3f ) and palladium–NHC complexes ( 4a , 4b , 4c , 4d , 4e , 4f ) have been synthesized and characterized using appropriate spectroscopic techniques. Studies have focused on the development of a more efficient catalytic system for the Suzuki coupling reaction of aryl chlorides. Catalytic performance of Pd–NHC complexes and in situ prepared Pd(OAc)2/LHX catalysts has been investigated for the Suzuki cross‐coupling reaction under mild reaction conditions in aqueous N,N‐dimethylformamide (DMF). These complexes smoothly catalyzed the Suzuki–Miyaura reactions of electron‐rich and electron‐poor aryl chlorides. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Emine
zge Karaca Osman ifti lknur
zdemir Gül Yakali Muhittin Aygün Nevin Gürbüz smail
zdemir 《应用有机金属化学》2019,33(7)
Platinum (II) complexes bearing N‐heterocyclic carbene (NHC) ligands have been widely used in catalytic chemistry, but there are very few reports of biological properties of this type of complexes. A series of [PtCl2(NHC)(PEt3)] complexes were synthesized. The structures of all compounds were characterized by 1H‐NMR, 13C‐NMR, IR and elemental analysis techniques, which supported the proposed structures. The single crystal structures of complexes 1a and 1e were determined. The title complexes show slightly distorted square‐planar coordination around the platinum (II) metal center. The cytotoxic properties of the platinum (II)–NHC complexes have been assessed in various human cancer lines, including cisplatin‐sensitive and resistant cells. IC50 values of these four complexes were determined by the MTS‐based assay on three human cell lines—brain (SHSY5Y), colon (HTC116) and liver (HEP3B). These complexes have been highlighted cancer therapeutic agent with unique structures and functions. 相似文献