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81.
The laser performance and related photophysical properties of two very soluble perylene dyes with long chain secondary alkyl groups were investigated in cyclohexane solution. With a dye laser as pump source a tuning range of 555–580 nm was obtained at an optimum concentration of 3×10–4 M. The quantum efficiencies (=0.29 and 0.21) were better than 1/2 that of rhodamine 6G. No photodegradation was observed over an excitation period of several hours. 相似文献
82.
The first and second dissociation constants of tartaric, maleic and phthalic acids have been determined using EMF method in water-ethanol mixed solvents, over a wide range of solvent composition (0-60 wt% ethanol) at six different temperatures (ranging from 30 to 55 degrees C at intervals of 5 degrees C). The thermodynamic parameters (DeltaG degrees , DeltaH degrees and DeltaS degrees ) for the first and the second ionization reactions were calculated from the well known equations. The results have been discussed in terms of the solute-solvent interactions and were compared with those of malic, malonic and succinic acids in the same mixed solvents. 相似文献
83.
Substituted 5-Antipyrinylazo-4-phenyl-2-aminothiazoles as Disperse Dyes for Dyeing Polyester Fabrics
Mohamed A. Metwally Amira Metwally Ebrahim Abdel-Galil Fathy A. Amer 《Monatshefte für Chemie / Chemical Monthly》2008,139(1):35-42
Summary. A series of some new substituted 5-antipyrinylazo-4-phenyl-2-aminothiazole disperse dyes was synthesized by diazocoupling
of 4-antipyrinyldiazonium chloride with aminothiazole derivatives. The synthesized dyes were characterized by UV-Vis absorption,
IR, 1H NMR, and MS spectroscopy. The dyes gave orange to reddish-violet shades with very good depth and levelness when applied
to polyester fabrics as disperse dyes and their fastness properties were evaluated on polyester fibers. Also the position
of color in CIELAB coordinates (L*, a*, b*, H*, and C*) was assessed. 相似文献
84.
Adel A.-H. Abdel-Rahman Amira K. F. Shaban Ibrahim F. Nassar Dina S. EL-Kady Nasser S. M. Ismail Samy F. Mahmoud Hanem M. Awad Wael A. El-Sayed 《Molecules (Basel, Switzerland)》2021,26(13)
New pyridine, pyrazoloyridine, and furopyridine derivatives substituted with naphthyl and thienyl moieties were designed and synthesized starting from 6-(naphthalen-2-yl)-2-oxo-4-(thiophen-2-yl)-1,2-dihydropyridine-3-carbonitrile (1). The chloro, methoxy, cholroacetoxy, imidazolyl, azide, and arylamino derivatives were prepared to obtain the pyridine-−C2 functionalized derivatives. The derived pyrazolpyridine-N-glycosides were synthesized via heterocyclization of the C2-thioxopyridine derivative followed by glycosylation using glucose and galactose. The furopyridine derivative 14 and the tricyclic pyrido[3′,2′:4,5]furo[3,2-d]pyrimidine 15 were prepared via heterocyclization of the ester derivative followed by a reaction with formamide. The newly synthesized compounds were evaluated for their ability to in vitro inhibit the CDK2 enzyme. In addition, the cytotoxicity of the compounds was tested against four different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549). The CDK2/cyclin A2 enzyme inhibitory results revealed that pyridone 1, 2-chloro-6-(naphthalen-2-yl)-4-(thiophen-2-yl)nicotinonitrile (4), 6-(naphthalen-2-yl)-4-(thiophen-2-yl)-1H-pyrazolo[3,4-b]pyridin-3-amine (8), S-(3-cyano-6-(naphthaen-2-yl)-4-(thiophen-2-yl)pyridin-2-yl) 2-chloroethanethioate (11), and ethyl 3-amino-6-(naphthalen-2-yl)-4-(thiophen-2-yl)furo[2,3-b]pyridine-2-carboxylate (14) are among the most active inhibitors with IC50 values of 0.57, 0.24, 0.65, 0.50, and 0.93 µM, respectively, compared to roscovitine (IC50 0.394 μM). Most compounds showed significant inhibition on different human cancer cell lines (HCT-116, MCF-7, HepG2, and A549) with IC50 ranges of 31.3–49.0, 19.3–55.5, 22.7–44.8, and 36.8–70.7 μM, respectively compared to doxorubicin (IC50 40.0, 64.8, 24.7 and 58.1 µM, respectively). Furthermore, a molecular docking study suggests that most of the target compounds have a similar binding mode as a reference compound in the active site of the CDK2 enzyme. The structural requirements controlling the CDK2 inhibitory activity were determined through the generation of a statistically significant 2D-QSAR model. 相似文献
85.
Mourad Hrizi Maatoug Hassine Mohamed Abdelwahed Nejmeddine Chorfi 《Mathematical Methods in the Applied Sciences》2019,42(18):6083-6100
The aim of this work is to reconstruct the location and geometry of a cavity embedded in a linear isotropic material Ω via an exterior boundary measurement of the displacement field. The considered problem is governed by the linear elasticity system. This inverse problem of geometry reconstruction (ie, location and shape) is formulated as a topology optimization one and solved by minimizing a Kohn‐Vogelius type functional with the help of the topological sensitivity method. Some numerical results are presented using a noniterative geometric algorithm. 相似文献
86.
87.
We study the effects of the semiconductor laser noise on the generated beat signal, in Coherent Optical Domain Reflectometry device. By using a general laser noise analytical model, based on Volterra non-linear treatment of laser rate equations, we find a novel general expression of the beat photocurrent. We show that the coherence and the incoherence cases are observed for a different delay time intervals than the ones known in literature. We show that the coherence domain corresponds to a delay time lower than the half of the laser coherence time τ0<1/2τc, and the incoherence domain corresponds for τ0>2τc. An original shape of the beat signal autocorrelation function affected by the laser noises is obtained. 相似文献
88.
A new norcembrane, designated sinularectin 3, was isolated from the Kenyan soft coral Sinularia erecta. Sinularectin is a chlorinated highly oxygenated norcembrane with an unprecedented functionalisation of the cembrane isopropyl group. The structure of sinularectin was elucidated by interpretation of the HRESMS results as well as 1D and 2D NMR spectra. 相似文献
89.
Beitz T Laudien R Löhmannsröben HG Kallies B 《The journal of physical chemistry. A》2006,110(10):3514-3520
In this work, ion mobility (IM) spectra of more than 50 aromatic compounds were recorded with a laser-based IM spectrometer at atmospheric pressure. IM spectra of PAH in the laser desorption experiment show a high complexity resulting from the occurrence of monomeric, dimeric, and oligomeric cluster ions. The mobilities of all compounds were determined in helium as drift gas. This allows the calculation of the diffusion cross sections (Omega(calc)) on the basis of the exact hard sphere scattering model and their comparison with the experimentally determined diffusion cross sections (Omega(exp)). Extended Omega(exp)/Omega(calc) and Omega(exp)/mass correlations were performed in order to gain insight into conformational properties of cationic alkyl benzenes and internal rotation of phenyl rings in aromatic ions. This is demonstrated with some examples, such as the evaluation of the dihedral angle of the ions of 9,10-diphenylanthracene, o- and m-terphenyl, and 1,2,3- and 1,3,5-triphenylbenzene. Furthermore, sandwich and T-structures of dimeric PAH cations are discussed. The analysis was extended to oligomeric ions with up to nine monomer units. Experimental evidence is presented suggesting the formation of pi-stacks with a transition toward modified pi-stacks with increasing cluster size. The distance between monomeric units in dimeric and oligomeric ions was obtained. 相似文献
90.
Wanas AS Matsunami K Otsuka H Desoukey SY Fouad MA Kamel MS 《Chemical & pharmaceutical bulletin》2010,58(12):1596-1601
From the EtOAc and 1-BuOH fractions, three new ursane-type and four new lupane-type triterpenes, along with nine known glycosides and glycosyl esters of lupane-type were isolated from the leaves of Schefflera actinophylla. All the isolated compounds were obtained for the first time from this plant. The structures of the new triterpenes were determined through a combination of spectroscopic and chemical analyses. 相似文献