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101.
Saad FA Buurma NJ Amoroso AJ Knight JC Kariuki BM 《Dalton transactions (Cambridge, England : 2003)》2012,41(15):4608-4617
The synthesis of a thiourea substituted derivative of tris(pyridyl-2-methyl)amine (TPA) is reported. Two of the three pyridine rings are substituted in the 6-position with benzoylthiourea groups. These thiourea groups undergo intramolecular hydrogen bonding to form six-membered rings which leaves one N-H group available to form hydrogen bonds with other molecules. This reports details how the complexation of this new ligand with transition metal ions yields complexes with differing geometries. Seven co-ordinate Mn(II) and Cd(II), six co-ordinate Ni(II) and five co-ordinate Co(II), Cu(II) and Zn(II) complexes have been isolated. 相似文献
102.
The electronic and photoconductivity properties of semiconducting chalcogenide glasses have been largely stimulated by attractive micro-electronic device applications. The present paper aims to study the effect of In additions on the steady state and transient photoconductivity of amorphous Inx(Se3Te1)100 ? x (0 ≤ x ≤ 10 at.%) chalcogenide films. It was found that, the Indium additions lead to the decrease of both the activation energies (ΔEdc in the dark and ΔEph for the photoelectrical conduction) and the optical band gap Eg that improved the electrical properties of these films. The photoconductivity increases while photosensitivity changes from 8.73 to 7.18 with the increase of In content. The exponential dependence of photocurrent on the light intensity suggests that, the recombination mechanism in these films is due to bimolecular recombination. The transient photoconductivity measurements stated that, the carrier lifetime decreased by the increase of the light intensity and In content. The obtained results were discussed in terms of the width of localized states (Mott and Davis model) and the chemical-bond approach. 相似文献
103.
Ashraf A. Aly Mohamed Ramadan Ashraf M. Mohamed Esam A. Ishak 《Journal of heterocyclic chemistry》2012,49(5):1009-1018
Diethyl azodicarboxylate and 3,4,5,6‐tetrachloro‐1,2‐benzoquinone react with cyclopentano‐ and cycloheptano‐fused thienopyrimidines to form the oxidative dimer of the starting material via S—S bond formation. Reaction of two equivalents of 2,2′‐(cyclohexa‐2′,5′‐diene‐1,4‐diylidene)dimalononitrile with thienopyrimidines afforded 3‐(4′,4′‐dicyanomethylene‐cycloalka[a]‐2,5‐dienyl)‐4‐oxo‐6,7,8,9‐tetrahydro‐5H‐cyclo‐hepta[4,5]‐[1,3]thiazolo[3,2‐a]‐thieno[2,3‐d]pyrimidin‐2‐ylidene‐2‐dicarbonitriles. The thioenopyrimidines react with 2‐[1,3‐dioxo‐1H‐inden‐2(3H)‐ylidene]malononitrile to produce 1,3,5′‐trioxo‐1,3,3′,5′‐tetrahydrospiro‐(indene‐2,2′‐thiazolo[2,3‐b]‐cycloalkyl[b]‐thieno[2,3‐d]pyrimidine)‐3′‐carbonitriles. However, the reaction of thienopyrimidines with 2,3‐dicyano‐1,4‐naphthoquinone proceeded to afford the fused cycloalkyl‐thieno form of naphtho[1,3]thiazolo[3,2‐a]thieno[2,3‐d]pyrimidine‐6.7,12‐triones. Reaction of 2‐hydrazino‐5,6,7,8‐tetrahydrobenzo[b]thieno[2,3‐d]pyrimidine‐4(1H)‐one with dimethyl acetylenedicarboxylate and ethyl propiolate, respectively, afforded cyclohexano‐fused (Z)‐dimethyl 2[(E)‐4‐oxo‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐2(1H)‐ylidene)hydrazono]succinate and thieno‐pyrimidinotriazine. Both oxidative dimers of thienopyrimidines showed high inhibition of Hep‐G2 cell growth compared with the growth of untreated control cells. Moreover, the cycloheptano‐fused thiazinothienopyrimidine indicates a promising specific antitumor agent against Hep‐G2 cells because its IC50 is < 20 μM. 相似文献
104.
Steven Vandebril Aly Franck Gerald G. Fuller Paula Moldenaers Jan Vermant 《Rheologica Acta》2010,49(2):131-144
The rheological properties of complex fluid interfaces are of prime importance in a number of technological and biological
applications. Whereas several methods have been proposed to measure the surface rheological properties, it remains an intrinsically
challenging problem due to the small forces and torques involved and due to the intricate coupling between interfacial and
bulk flows. In the present work, a double wall-ring geometry to measure the viscoelastic properties of interfaces in shear
flows is presented. The geometry can be used in combination with a modern rotational rheometer. A numerical analysis of the
flow field as a function of the surface viscoelastic properties is presented to evaluate the non-linearities in the surface
velocity profile at a low Boussinesq number. The sensitivity of the geometry, as well as its applicability, are demonstrated
using some reference Newtonian and viscoelastic fluids. Oscillatory and steady shear measurements on these reference complex
fluid interfaces demonstrate the intrinsic sensitivity, the accuracy, and the dynamic range of the geometry when used in combination
with a sensitive rheometer. 相似文献
105.
Padmarajiah Nagaraja Mohammed Fawaz Silwadi Akheel Ahmed Syed 《Mikrochimica acta》2000,135(3-4):185-189
A new, simple, and sensitive spectrophotometric method for the determination of certain tricyclic antidepressants, belonging
to the dibenzazepine class of drugs, has been developed. The proposed method is based on the reaction of imipramine hydrochloride
(IPH), desipramine hydrochloride (DPH), clomipramine hydrochloride (CPH), trimipramine maleate (TPM) or opipramol (OPP) with
iron(III), and subsequent reaction with ferricyanide in an acetic acid medium, to yield a blue product, with maximum absorption
at 720–730 nm.
Received January 24, 2000 相似文献
106.
Marisa Phelan Fawaz Aldabbagh Per B. Zetterlund Bunichiro Yamada 《Macromolecular theory and simulations》2005,14(2):109-116
Summary: A detailed investigation of chain transfer to polymer during free radical ring‐opening polymerization of the eight‐membered disulfide monomer 2‐methyl‐7‐methylene‐1,5‐dithiacyclooctane (MDTO) is presented. It has been shown that extensive chain transfer to polymer occurs involving both poly(MDTO) radicals and cyanoisopropyl radicals. Significant decreases in molecular weight were observed when cyanoisopropyl radicals were generated in the presence of poly(MDTO) in the absence of monomer. The molecular weight distribution (MWD) obtained from polymerization of MDTO in the presence of pre‐added poly(MDTO) was markedly different from that obtained without pre‐added polymer. A kinetic model was constructed in an attempt to quantitatively describe the chain transfer to polymer process based on the addition fragmentation chain transfer mechanism. It was found however that the simulated MWDs were considerably broader than the experimental MWDs, which were similar to the Schulz‐Flory distribution.
107.
Li-Chun Bian Zouheir Fawaz Kamran Behdinan 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(11):809-821
The maximum energy release rate criterion, i.e., G
max
criterion, is commonly used for crack propagation analysis. This fracture criterion is based on the elastic macroscopic strength
of materials. In the present investigation, however, the G
max
criterion has been modified in order to accommodate the consideration of plastic strain energy. This modified criterion is
extended to study the fatigue crack growth characteristics of mixed-mode cracks. To predict crack propagation due to fatigue
loads, a new elasto–plastic energy model is presented. This new model includes the effects of material properties such as
strain hardening exponent n, yield strength σ
y
, and fracture toughness and stress intensity factor ranges. The results obtained are compared with those obtained using the
commonly employed crack growth law and the experimental data. 相似文献
108.
The effect of heat treatment on the optical and electrical properties of Ge15Sb10Se75 and Ge25Sb10Se65 thin films in the range of annealing temperature 373-723 K has been investigated. Analysis of the optical absorption data indicates that Tauc's relation for the allowed non-direct transition successfully describes the optical processes in these films. The optical band gap (Egopt.) as well as the activation energy for the electrical conduction (ΔE) increase with the increase of annealing temperature (Ta) up to the glass transition temperature (Tg). Then a remarkable decrease in both the Egopt. and ΔE values occurred with a further increase of the annealing temperature (Ta>Tg). The obtained results were explained in terms of the Mott and Davis model for amorphous materials and amorphous to crystalline structure transformations. Furthermore, the deduced value of Egopt. for the Ge25Sb10Se65 thin film is higher than that observed for the Ge15Sb10Se75 thin film. This behavior was discussed on the basis of the chemical ordered network model (CONM) and the average value for the overall mean bond energy 〈E〉 of the amorphous system GexSb10Se90−x with x=15 and 25 at%. The annealing process at Ta>Tg results in the formation of some crystalline phases GeSe, GeSe2 and Sb2Se3 as revealed in XRD patterns, which confirms our discussion of the obtained results. 相似文献
109.
Castellanos AJ Urbina-Villalba G García-Sucre M 《The journal of physical chemistry. B》2006,110(6):2751-2754
A mesoscopic model for the liquid/vapor interface previously developed for nonpolar fluids [J. Phys. Chem. A 2003, 107, 875; 2003, 107, 883] is extended to the case of polar associated compounds. The interfacial energy is factorized in two terms: one corresponding to association depending on the hydrogen bonds density, the other corresponding to the nonpolar contribution. This last term is treated in the framework of the corresponding states formalism similar to the one used in the case of nonpolar fluids [J. Phys. Chem. B 2004, 108, 5951]. The model yields a generalized behavior of the association factor as a function of the dielectric constant for the treated fluids. The calculated surface tension shows a mean error of about 1% for seven compounds having different multivalent H-bond characters. 相似文献
110.
Ahmed M. A. El-Sayed Mohamed A. E. Aly 《Journal of Applied Mathematics and Computing》2002,9(2):525-533
The fractional order evolutionary integral equations have been considered by the first author in [6], the existence, uniqueness and some other properties of the solution have been proved. Here we study the continuation of the solution and its fractional order derivative. Also we study the generality of this problem and prove that the fractional order diffusion problem, the fractional order wave problem and the initial value problem of the equation of evolution are special cases of it. The abstract diffusion-wave problem will be given also as an application. 相似文献