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We consider goodness of fit tests for the Rayleigh distribution with grouped data. New Kolmogrov–Smirnov type tests are suggested and compared with the traditional chi-square and likelihood ratio tests. The results show that some of the suggested tests have a good power performance as compared with the traditional ones. 相似文献
3.
Resistivity and low field ac susceptibility measurements are made on R: 123 superconducting samples with different rare earth elements R. The order parameter dimensionality OPD is deduced from resistivity versus temperature plot using the Aslamazov and Larkin expression, while the analysis of the temperature dependence of ac susceptibility is done employing Beans’ critical state model and with the help of the Ravi expression. With increasing R, the critical temperatures Tc are nearly kept constant (∼90 K), while the crossover temperatures To are shifted to lower values. Moreover, the superconducting order parameter OPD is shifted toward 2D behavior. On the other hand, the values of superconducting volume fraction fg decrease with increasing ac field amplitude Hm for all samples and it is higher in Er: 123 sample than in Nd: 123 sample. Although the values of critical current density Jc at the peak temperature Tm are nearly unchanged with increasing R, the values of Jc(T), at T<Tm and T>Tm, are found to be dependent on the chosen R. The correlation between the above calculated parameters against R is also mentioned. 相似文献
4.
El-Sawaf Ayman K. West Douglas X. El-Bahnasawy Ramadan M. El-Saied Fathy A. 《Transition Metal Chemistry》1998,23(3):227-232
The synthesis and characterization of complexes of iron(III), cobalt(II) and cobalt(III) with 4-formylantipyrine N(4)-methyl-, N(4)-dimethyl-, and 3-piperidylthiosemicarbazones are reported. Elemental analyses, molar conductivities, magnetic measurements
and spectral (i.r., electronic and e.s.r.) studies have been used to elucidate the nature of the metal complexes. The i.r.
spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands, either in the thione or thiolato form.
Different stereochemistries are proposed for the various cobalt(II) complexes on the basis of spectral and magnetic studies.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
6.
Ayman Ben Mabrouk Hamid Kaddami Sami Boufi Fouad Erchiqui Alain Dufresne 《Cellulose (London, England)》2012,19(3):843-853
The microstructure and chemical composition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and
delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrystals and microfibrillated
cellulose (MFC). The former correspond typically to the elementary crystallite units of the cellulose fibers, with a rod-like
morphology and an aspect ratio of about 20. The latter, mechanically disintegrated from oxidized bleached fibres, presents
an entangled fibrillar structure with widths in the range 5-20 nm. The reinforcing potential of the ensuing nanoparticles
was investigated by casting a mixture of acrylic latex and aqueous dispersion of cellulose nanoparticles. Thermo-mechanical
analysis revealed a huge enhancement of the stiffness above the glass transition of the matrix. Significant differences in
the mechanical reinforcing capability of the nanoparticles were reported. 相似文献
7.
Synthesis,spectroscopic characterization,thermal behaviour,in vitro antimicrobial and anticancer activities of novel ruthenium tricarbonyl complexes containing monodentate V‐shaped Schiff bases 下载免费PDF全文
The interaction of Ru3(CO)12 with a novel family of monodentate V‐shaped Schiff base ligands (L1–4; L1: (E)‐1‐(4‐((4‐bromobenzylidene)amino)phenyl)ethanone, L2: (E)‐1‐(3‐(4‐(dimethylamino)benzylideneamino)phenyl)ethanone, L3: (E)‐1‐(4‐(4‐(dimethylamino)benzylideneamino)phenyl)ethanone, L4: (E)‐1‐(3‐(3,4‐dimethoxybenzylideneamino)phenyl)ethanone) in air under atmospheric pressure afforded the novel complexes [Ru(CO)3(L1–4)2]. The parent ligands and their complexes were characterized using elemental analyses and spectroscopic techniques. In addition, the structure of the representative ligand L1 was determined using single‐crystal X‐ray analysis. The stereochemistry and theoretical optimization of the three‐dimensional geometry of the ligands and their complexes were justified. In vitro antimicrobial screening against bacterial stains Escherichia coli and Staphylococcus aureus and fungus Candida albicans was conducted. Cytotoxicity of the compounds as anti‐tumour agents was evaluated against liver carcinoma (HepG2), breast carcinoma (MCF7) and colon carcinoma (HCT‐116) cell lines relative to cisplatin and doxorubicin. The complexes showed variable in vitro cytotoxic activities against the three studied cell lines, with IC50 values less than those of cis‐platin, and thus appear to be building blocks for promising anti‐tumour agents. 相似文献
8.
Abdulnasir A. Majeed Mostafa M.H. Khalil Ahmed Fetoh Ayman A. Abdel Aziz G.M. Abu El‐Reash 《应用有机金属化学》2021,35(1)
In this work, (Z)‐N‐benzoyl‐N′‐(1H‐1,2,4‐triazol‐3‐yl)carbamimidothioic acid and its Mn(II), Co(II), Cu(II) and Cd(II) complexes were introduced for the first time. This carbonyl thiourea ligand was prepared by the reaction of 1H‐1,2,4‐triazol‐3‐amine with benzoyl isothiocyanate. The structural elucidation of these compounds was performed using elemental analysis and spectral and magnetic measurements. Octahedral structures of all complexes, except Cd(II) complex with a tetrahedral geometry, were confirmed by applying DFT structural optimization. The thermal decomposition behaviour of metal complexes of carbonyl thiourea ligand is discussed. The calculation of kinetic parameters for prepared complexes (Ea, A, ΔH*, ΔS* and ΔG*) of all thermal degradation stages has been evaluated using two comparable approaches. Antimicrobial and ABTS‐antioxidant studies indicated potent activity of Cd(II) complex compared with the other investigated compounds. The cytotoxic activity of the prepared compounds was investigated in vitro. The results indicated potent activity of Mn(II) complex against both HePG2 (liver carcinoma) and MCF‐7 (breast carcinoma) cancer cells. 相似文献
9.
Abdel-Kader Maged Saad Alam Prawez Alqarni Mohammed Hamed Salkini Mohamad Ayman 《平面色谱法杂志一现代薄层色谱法》2017,30(3):211-215
JPC – Journal of Planar Chromatography – Modern TLC - A novel, simple, and sensitive high-performance thin-layer chromatography (HPTLC) method has been successfully developed and... 相似文献
10.
Rasha A. M. Faty Hoda A. R. Hussein Ayman M. S. Youssef 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1484-1490
3-Ethyl 2-amino-4-methyl-5-phenyl thiophene carboxylate 1 was used as a starting material to synthesize 2a,b via coupling with malononitrile or acetyl acetone, respectively. When heated, under reflux in sodium ethoxide solution, 2a,b give 3a,b. On the other hand, when compounds 3a,b were heated under reflux in ethanol with hydrazine hydrate, thiourea, or 1,1-phenylenediamine hydrochloride and a catalytic amount of piperidine 4a,b, 5a,b and 6a,b, were produced, respectively. The new compounds were tested for their antimicrobial activity. Compounds 2a–6b showed antibacterial activities, and 2a,2b and 4b showed antifungal activities. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献