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61.
Mohd. Sajid Ali Mohd. Suhail Goutam Ghosh Mohammad Kamil Kabir-ud-Din 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,350(1-3):51-56
The interaction between bis(hexadecyldimethylammonium)hexane dibromide (16-6-16), bis(tetradecyldimethylammonium)hexane dibromide (14-6-14), their conventional counterparts cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) with polyvinylpyrrolidone (PVP) was investigated using the conductivity technique. The results show that gemini surfactants interact strongly with PVP as compared to conventional surfactants. The results also reveal that the surfactants with shorter hydrocarbon chain interact weakly as those of longer hydrocarbon chain. The interactions of 16-6-16 and 14-6-14 and their conventional counterparts with PVP were also studied using dynamic light scattering (DLS) measurements. We have also highlighted the effect of surfactant–polymer interactions on the dispersion force in the solution. Critical aggregation concentration (cac) and critical micelle concentration (cmc) were obtained using the conductivity data. The degrees of micelle ionization and free energies associated with aggregation, micellization, and transfer have also been evaluated and discussed. 相似文献
62.
Kamil I. Utegenov 《Journal of organometallic chemistry》2011,696(21):3408-3414
The addition of phosphines to the manganese allenylidene complexes Cp(CO)2MnCCC(Ph)R (R = H, Ph) proceeds selectively at the Cα atom to result in the α-phosphonioallenyl complexes Cp(CO)2Mn−-C(+PR31)CC(Ph)R. The protonation of the latter affords the η2-(1,2)-phosphonioallenes Cp(CO)2Mn{η2-(1,2)-HC(+PR31)CC(Ph)R}, rather than the phosphoniovinylcarbenes Cp(CO)2MnC(+PR31)-HCC(Ph)R. All complexes obtained are stereochemically rigid and do not isomerize into the η2-(2,3)-phosphonioallene isomers. 相似文献
63.
Fiammengo R Wojciechowski K Crego-Calama M Timmerman P Figoli A Wessling M Reinhoudt DN 《Organic letters》2003,5(19):3367-3370
[structure: see text] Water-soluble models of heme-protein active sites are obtained via the self-assembly of cationic porphyrins 1 and tetrasulfonato calix[4]arene 2 (K(1.2)() = 10(5) M(-)(1)). Selective binding of ligands either outside or inside the cavity of assemblies 1.2 via coordination to the zinc center has been observed. Small ligands such as 4-methylpyridine and 1-methylimidazole are encapsulated, while the bulkier caffeine is bound outside. Assemblies Co-1.2, in which the Zn porphyrin moiety has been replaced by a Co(II) porphyrin, can act as O(2) carriers. 相似文献
64.
Air/polymer distribution coefficients for polycyclic aromatic hydrocarbons by solid-phase microextraction sampling 总被引:2,自引:0,他引:2
Two methods to estimate distribution coefficients (K) between air and poly(dimethylsiloxane) (PDMS) coating of solid-phase microextraction (SPME) fibers for eight low molecular polycyclic aromatic hydrocarbons (PAHs) there are presented. The PDMS phases were used for determination of the coefficients according to equilibrium theory with help of a developed static calibration system (SCS). Another way to estimate the coefficients is based on the use of a linear relationship between the logarithm of the coefficients (log K) and linear temperature-programmed retention indexes (LTPRI) of the compounds without necessity to calibrate. The log K values for both of methods ranged from 5.2 (naphthalene) to 8.9 (pyrene) at 22 degrees C. Relative standard deviation (R.S.D.) of log K for each compound determined by static calibration was no more than 5.3%. R.S.D. of retention times for LTPRI indices did not exceed 0.28% for repeated injection. All experiments were implemented on a GC-MS system. 相似文献
65.
In the present study, the buffering effect of magnetite nanoparticles (Fe3O4) dispersed in an aqueous solution on the local pH value is investigated. It manifests itself in the fact that when some amount of acid or base is added to the solution then the solution near the nanoparticles surface becomes, respectively, less acidic and less alkaline than it is expected. It is the result of both the local electrostatic field, which represents the electric double layer at the surface of magnetic nanoparticles and the magnetic field around the nanoparticles. The magnetite nanoparticles exhibit very low toxicity and they are becoming increasingly important for new biomedical applications related to their effects on chemical reactions in body tissues and cells. The question arises, how strong are these effects at the nanoscale? The strength of the buffering property of magnetite nanoparticles is investigated both theoretically and experimentally by the direct measurement of the local pH value of a magnetic nanoparticles suspension. The theoretical model is based on stochastic equations describing the ions diffusing in the neighborhood of the electric double layer of the magnetic material. The electric double layer is modeled with the help of the Poisson–Boltzmann model. It is directly shown that both the electrostatic field and the magnetic field are responsible for the observed local changes of the pH value with respect to the bulk pH value. 相似文献
66.
Sulaiman Wadi Harun Nizam Tamchek Mohd Kamil Abd-Rahman Prabakaran Poopalan Harith Ahmad 《Optical Review》2003,10(3):133-135
A multiwavelength Brillouin/erbium fibre laser (BEFL) which operates in the long wavelength (L-band) region is demonstrated for potential applications in an L-band wavelength division multiplexing (WDM) communication system. The laser configuration consists of a long erbium-doped fibre to enable L-band amplification where two 3-dB couplers take a portion of the generated BEFL signal and re-inject it into the single mode fibre to seed a cascaded BEFL line in the same direction as the first BEFL line. A stable and strong laser comb of up to five lines with 10-GHz spacing has been obtained with a Brillouin pump (BP) of 9.2 mW and a 980 nm pump of 92 mW. The BEFL has shown a broad tuning range with a tuning characteristic for line #1 which is flat over a range greater than 9.9 nm. 相似文献
67.
Strachan JD Adler H Alling P Ancher C Anderson H Anderson JL Ashcroft D Barnes CW Barnes G Batha S Bell MG Bell R Bitter M Blanchard W Bretz NL Budny R Bush CE Camp R Caorlin M Cauffman S Chang Z Cheng CZ Collins J Coward G Darrow DS DeLooper J Duong H Dudek L Durst R Efthimion PC Ernst D Fisher R Fonck RJ Fredrickson E Fromm N Fu GY Furth HP Gentile C Gorelenkov N Grek B Grisham LR Hammett G Hanson GR Hawryluk RJ Heidbrink W Herrmann HW Hill KW Hosea J Hsuan H Janos A Jassby DL Jobes FC 《Physical review letters》1994,72(22):3526-3529
68.
Tijen Tanyalcin Diler Aslan Yusuf Kurtulmus Nalan Gökalp Kamil Kumanlioğlu 《Accreditation and quality assurance》2000,5(9):383-387
In this study the reference intervals for folate and vitamin B12 were estimated according to the National Committee for Clinical Laboratory Standards Approved Guideline C28-A and International
Federation of Clinical Chemistry recommendations. The study included 155 women and 124 men between ages 18–40. The health
status was confirmed by history, physical examination and a questionnaire. The central 95% reference intervals of serum folate
and vitamin B12 for women, determined non-parametrically, were found to be 3.9–18.1 ng/ml and 101–666.7 pg/ml, respectively.
The reference values of serum folate and vitamin B12 for men were also found to be 2,5–17.6 ng/ml and 100–699.57 pg/ml, respectively.
We did not observe subclass differences between females and males.
Received: 15 April 2000 · Accepted: 15 April 2000 相似文献
69.
Kamil Kaminski Marian Paluch R. Wrzalik Jerzy Ziolo Radoslav Bogoslovov C. Michael Roland 《Journal of polymer science. Part A, Polymer chemistry》2008,46(11):3795-3801
The polymerization and crosslinking of tetraethylene glycol dimethacrylate were induced by high pressure. The product was analyzed by both swelling experiments and broadband dielectric spectroscopy to determine the structure, with IR measurements used to follow the extent of reaction and its temperature dependence. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3795–3801, 2008 相似文献
70.