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71.
A series of organotin(IV) complexes of the general formula RxSnCl4?x.L (where R=Me, n?Bu, Ph; x = 2 or 3; L = pyrazole or pyrazol-5-one) have been prepared and characterized by elemental analyses, IR and NMR spectroscopy. The ligands used were found to coordinate with R3SnCl species as monodentate ligands via the more reactive nitrogen atom, to give pentacoordinate tin complexes, whilst they may coordinate with R2SnCl2 species as bidentate ligands through the N–N linkage to give hexacoordinate tin complexes. These were demonstrated mainly by spectroscopic data. The tautomeric behaviour of organotin complexes of pyrazol-5-one ligands in inert (CDCl3) and donor (DMSO-d6) solvents were also studied. The complexes were screened against six species of bacteria. 相似文献
72.
Sannay Mohamad 《Acta Appl Math》2003,76(2):117-135
Convergence dynamics of Hopfield-type neural networks subjected to almost periodic external stimuli are investigated. In this article, we assume that the network parameters vary almost periodically with time and we incorporate variable delays in the processing part of the network architectures. By employing Halanay inequalities, we obtain delay independent sufficient conditions for the networks to converge exponentially toward encoded patterns associated with the external stimuli. The networks are guaranteed to have exponentially hetero-associative stable encoding of the external stimuli. 相似文献
73.
Laili Mahmoudian Jonas Melin Mohamad Reza Mohamadi Keiko Yamada Michio Ohta Noritada Kaji Manabu Tokeshi Mats Nilsson Yoshinobu Baba 《Analytical sciences》2008,24(3):327-332
We have developed a new method for a fast and precise analysis of circle-to-circle amplification (C2CA) product for specific gene detection by microchip electrophoresis. In this method, we have added a new enzymatic step to the C2CA reaction, which could be carried out isothermally at 37 degrees C. Compared to the original single-stranded DNA, the double-stranded DNA that is produced by this enzymatic reaction is more reliable for analysis by microchip electrophoresis. C2CA product was detected within 55 s with high reproducibility by this method which was successfully applied to the detection of 10-ng genomic DNA of the pathogenic bacteria Vibrio. cholerae within 110 s. Purification was found to be an indispensable step for the analysis of the C2CA product of genomic DNA samples. 相似文献
74.
Jacques Lalevée Mohamad El‐Roz Xavier Allonas Jean Pierre Fouassier 《Journal of polymer science. Part A, Polymer chemistry》2008,46(6):2008-2014
New systems for the visible‐light‐induced polymerization of cationic resins working through a free‐radical‐promoted process are presented. They are based on a photoinitiator (camphorquinone, isopropylthioxanthone, Eosin), a silane, and a diphenyl iodonium salt, the new compound being the silane. The overall efficiency is strongly affected by the silane structure. The rates of polymerization and final percent conversion are noticeably higher than those obtained in the presence of already studied reference systems. Moreover, contrary to previously investigated free‐radical‐promoted cationic polymerizations, oxygen does not inhibit the process and an unusual enhancement of the polymerization kinetics is found in aerated conditions: such an observation seems to have never been reported so far. The excited state processes and the role of oxygen as revealed by laser flash photolysis are discussed. The particular behavior of the silyl radicals is outlined. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2008–2014, 2008 相似文献
75.
We study the filling invariants at infinity div
k
for Hadamard manifolds defined by Brady and Farb [ Trans. Am. Math. Soc. 350(8) (1998), 3393–3405]. Among other results, we give a positive answer to the question they posed: whether these invariants
can be used to detect the rank of a symmetric space of noncompact type. 相似文献
76.
I.J Mohamad L.Zammit Mangion E.F Lambson G.A Saunders 《Journal of Physics and Chemistry of Solids》1982,43(8):749-759
Simultaneous visual observation and monitoring of the ultrasonic signals show that acoustic emission (AE) produced as Pb5Ge3O11c-plate crystals undergo the ferroelectric hysteresis cycle results from domain wall nucleation and collapse. AE activity takes place predominantly at applied electric fields large enough to bring a crystal substantially towards its saturation polarisation. A notable feature observed in Pb5Ge3O11 and Pb5?xBaxGe3O11 alloys is the existence of an abrupt threshold electric field, denoted by E∞ in the high gain limit, for production of AE: as the electric field is increased beyond the threshold value, the amount of AE observed increases by several orders of magnitude. E∞ depends linearly on the inverse of the c-plate sample thickness (1/d) and also upon sample temperature—falling to a minimum at about 70°C for Pb5Ge3O11 and then rising steeply as the Curie temperature (178°C) is approached. E∞ is also dependent on the rate of change of the applied electric field and as this is increased extrapolates to the high frequency limit of the coercive field. Measurements of crystal polarisation indicate a one-to-one correspondence between AE and the electrical Barkhausen pulses which occur during polarisation reversal—further evidence for domain nucleation and collapse as the source of AE. Optical and AE studies made simultaneously on gadolinium molybdate add confirmation that these particular processes are responsible for the AE produced by ferroelectric crystals. 相似文献
77.
Jacques Laleve Nicolas Blanchard Mohamad‐Ali Tehfe Jean Pierre Fouassier 《Macromolecular rapid communications》2011,32(11):838-843
The use of decatungstate in combination with silanes to generate silyl radicals under green fluorescence bulb irradiation as well as sunlight exposure is described. The mechanisms are investigated by ESR and laser flash photolysis experiments. The high potential of this reaction is evidenced here when using a decatungstate/silane/diphenyl iodonium salt combination as an initiating system for the ring opening photopolymerization of epoxides.
78.
Zhenkun Huang Sannay Mohamad Chunhua Feng Guorong Cai 《Applied Mathematical Modelling》2010,34(1):80-91
This paper presents new dynamical behavior, i.e., the coexistence of 2N domains of attraction of N-dimensional nonautonomous neural networks with time-varying delays. By imposing some new assumptions on activation functions and system parameters, we construct 2N invariant basins for neural system and derive some criteria on the boundedness and exponential attractivity for each invariant basin. Particularly, when neural system degenerates into periodic case, we not only attain the coexistence of 2N periodic orbits in bounded invariant basins but also give their domains of attraction. Moreover, our results are suitable for autonomous neural systems. Our new results improve and generalize former ones. Finally, computer simulation is performed to illustrate the feasibility of our results. 相似文献
79.
Mohamad Akbar Ali 《Molecular physics》2013,111(20):2149-2158
Cyclic [n]paraphenyleneacetylenes ([n]CPPAs) are potentially useful compounds for molecular electronics. In this article, a homodesmotic reaction scheme coupled with density functional theory has been used to estimate theoretically strain energies and heats of formation of [n]CPPAs. Calculations have been done for a series of [n]CPPAs, containing up to ten phenylacetylene units. Strain energies of [n]CPPAs decrease, while heats of formation increase steadily with the increase in the number of phenylacetylene units using homodesmotic reaction schemes. B3LYP and mPW1PW91 functionals have been used with the Pople basis set 6-31G* to analyze the trends. The results are sensitive to the scheme of homodesmotic reaction chosen, thereby necessitating careful chemical consideration before spending considerable computational resources for higher [n]CPPAs not considered here. Computational estimates for the ring diameter of [n]CPPAs and absolute entropy have also been obtained here. The HOMO-LUMO gaps of the belt shaped [n]CPPAs show an odd–even difference. In addition, the HOMOs of the [3]CPPA, [5]CPPA, [7]CPPA and [9]CPPA are doubly degenerate. 相似文献
80.