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41.
Esra Dilek Nesrin Dogancay Bulent Caglar Onur Sahin Ahmet Tabak 《Journal of Coordination Chemistry》2017,70(16):2833-2852
The mononuclear six metal(II) complexes ([Co(mef)2(3-pic)2(CH3OH)2] (1), [Ni(mef)2(3-pic)2(CH3OH)2] (2), [Cu(mef)2(3-pic)2] (3), [Co(mef)2(4-pic)2] (4), [Ni(mef)2(4-pic)2] (5), and [Cu(mef)2(4-pic)2] (6) with mefenamic acid and picoline ligands were synthesized, characterized, and their carbonic anhydrase inhibitory activities were evaluated. The six complexes were characterized by elemental analysis, FT-IR spectroscopy, and thermal analyses. The crystal structures of 1, 3, and 6 were determined by X-ray crystallography. The complexes have octahedral geometry. In 1, the mefenamato ligand behaved as monodentate whereas in 3 and 6, the mefenamato ligand acted as a bidentate ligand. Complexes 3 and 6 consist of the mefenamate and 4-picoline ligands. In 1, unlike the other complexes, methanol acted as a ligand and was involved in the coordination. Carbonic anhydrase I and II isoenzymes were purified from human erythrocytes. The in vitro effects of mefenamic acid, 3-picoline, 4-picoline, and the six metal(II) complexes on these isoenzymes were evaluated. 相似文献
42.
Directional coupling between the even- and odd-parity modes of two parallel dissimilar linear defect waveguides in a square photonic crystal of cylindrical air holes in dielectric background is numerically demonstrated. Projected band-structure computations through the plane-wave expansion method reveal that high-efficiency coupling can be achieved in a frequency range of approximately 9 % extent around the central frequency. Coupling occurs if one row of spacing is maintained between the waveguides supporting even and odd modes, which are composed of annular air holes with outer radii equal to the photonic crystal’s scatterer radii and inner radii of 0.19 and 0.44 periods, respectively. Extinction ratio for coupling from the even to odd mode at the central frequency is 4.0 dB. Coupling length calculated through finite-difference time-domain simulations is approximately 25 periods at the central frequency, in agreement with the estimation through band diagram. Unidirectional light transmission is also demonstrated through finite-difference time-domain simulations, provided that waveguide and coupling lengths are equal. Forward and reverse transmittances of 71 and 0.3 %, respectively, are achieved at the central operation frequency in a 25-period system. 相似文献
43.
Bulent Ozbas Shigeyuki Toki Benjamin S. Hsiao Benjamin Chu Richard A. Register Ilhan A. Aksay Robert K. Prud'homme Douglas H. Adamson 《Journal of Polymer Science.Polymer Physics》2012,50(10):718-723
The effects of functionalized graphene sheets (FGSs) on the mechanical properties and strain‐induced crystallization of natural rubber (NR) are investigated. FGSs are predominantly single sheets of graphene with a lateral size of several hundreds of nanometers and a thickness of 1.5 nm. The effect of FGS and that of carbon black (CB) on the strain‐induced crystallization of NR is compared by coupled tensile tests and X‐ray diffraction experiments. Synchrotron X‐ray scattering enables simultaneous measurements of stress and crystallization of NR in real time during sample stretching. The onset of crystallization occurs at significantly lower strains for FGS‐filled NR samples compared with CB‐filled NR, even at low loadings. Neat‐NR exhibits strain‐induced crystallization around a strain of 2.25, while incorporation of 1 and 4 wt % FGS shifts the crystallization to strains of 1.25 and 0.75, respectively. In contrast, loadings of 16 wt % CB do not significantly shift the critical strain for crystallization. Two‐dimensional (2D) wide angle X‐ray scattering patterns show minor polymer chain alignment during stretching, in accord with previous results for NR. Small angle X‐ray scattering shows that FGS is aligned in the stretching direction, whereas CB does not show alignment or anisotropy. The mechanical properties of filled NR samples are investigated using cyclic tensile and dynamic mechanical measurements above and below the glass transition of NR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
44.
45.
Bulent Ozbas Christopher D. O'Neill Richard A. Register Ilhan A. Aksay Robert K. Prud'homme Douglas H. Adamson 《Journal of Polymer Science.Polymer Physics》2012,50(13):910-916
We demonstrate the use of functionalized graphene sheets (FGSs) as multifunctional nanofillers to improve mechanical properties, lower gas permeability, and impart electrical conductivity for several distinct elastomers. FGS consists mainly of single sheets of crumbled graphene containing oxygen functional groups and is produced by the thermal exfoliation of oxidized graphite (GO). The present investigation includes composites of FGS and three elastomers: natural rubber (NR), styrene–butadiene rubber, and polydimethylsiloxane (PDMS). All of these elastomers show similar and significant improvements in mechanical properties with FGS, indicating that the mechanism of property improvement is inherent to the FGS and not simply a function of chemical crosslinking. The decrease in gas permeability is attributed to the high aspect ratio of the FGS sheets. This creates a tortuous path mechanism of gas diffusion; fitting the permeability data to the Nielsen model yields an aspect ratio of ~1000 for the FGS. Electrical conductivity is demonstrated at FGS loadings as low as 0.08% in PDMS and reaches 0.3 S/m at 4 wt % loading in NR. This combination of functionalities imparted by FGS is shown to result from its high aspect ratio and carbon‐based structure. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
46.
Pamukoglu M. Yunus Kirkan Bulent Senyurt Mustafa 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(1):343-352
The biosorption of radioactive Th(IV) ions in the aqueous solutions onto the modified powdered waste sludge (MPWS) has been examined. In this context, the parameters affecting biosorption of Th(IV) from aqueous solutions has been examined by using MPWS biosorbent in Box Behnken statistical experimental design. The structure of MPWS biosorbent was characterized by using SEM and BET techniques. According to the experimental design results, MPWS and Th(IV) concentrations should be kept high to achieve the maximum efficiency in Th(IV) biosorption. On the other hand, MPWS, which is also used as a biosorbent, is an economical, effective and natural biosorbent.
相似文献47.
Kozarova A Sliskovic I Mutus B Simon ES Andrews PC Vacratsis PO 《Journal of the American Society for Mass Spectrometry》2007,18(2):260-269
Regulation of the redox state of protein disulfide isomerase (PDI) is critical for its various catalytic functions. Here we describe a procedure utilizing isotope-coded affinity tag (ICAT) technology and mass spectrometry that quantitates relative changes in the dynamic thiol and disulfide states of human PDI. Human PDI contains six cysteine residues, four present in two active sites within the a and a' domains, and two present in the b' domain. ICAT labeling of human PDI indicates a difference between the redox state of the two active sites. Furthermore, under auto-oxidation conditions an approximately 80% decrease in available thiols within the a domain was detected. Surprisingly, the redox state of one of the two cysteines, Cys-295, within the b' domain was altered between the fully reduced and the auto-oxidized state of PDI while the other b' domain cysteine remained fully reduced. An interesting mono- and dioxidation modification of an invariable tryptophan residue, Trp-35, within the active site was also mapped by tandem mass spectrometry. Our findings indicate that ICAT methodology in conjunction with mass spectrometry represents a powerful tool to monitor changes in the redox state of individual cysteine residues within PDI under various conditions. 相似文献
48.
A new tetradentate diimine–dioxime ligand containing a donor set of N4, and its homo-, heterodinuclear and homotrinuclear copper(II) complexes were prepared and characterized on the basis of their elemental analysis, FT-IR, 1H and 13C NMR spectra, molar conductivity and magnetic moment measurements. The extraction ability of N,N′′-bis[1-biphenyl-2-hydroxyimino-1-ethylidene]-diethylenetriamine was also evaluated in chloroform by using several transition metal picrates such as Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cd(II) and Hg(II). It has been seen that the ligand shows strong binding ability toward the copper(II) ion. Moreover, the catalytic activities of the complexes for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The synthesized complexes display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity. The interaction between these complexes and DNA has also been investigated by agarose gel electrophoresis. We found that the homo- and heterodinuclear copper complexes can cleave supercoiled pBR322 DNA to nicked and linear forms. The dinuclear complexes including phenanthroline (2–4), with H2O2 as a co-oxidant, exhibited the strongest cleaving activity. 相似文献
49.
Splitting of light waves by a two-dimensional photonic crystal associated with source size and dispersion relation of photonic crystal at a wavelength of 1,550 nm without disturbing periodicity is numerically demonstrated via finite-difference time-domain simulations. Split branches in either polarization state make plus or minus 45° with the [11] direction and propagate in a self-collimated manner with equal amplitude and phase. Sixty-four percent of total transmittance is attained provided that the waves are coupled and collected through appropriate planar waveguides. Alternatively, approximately 50 % total transmittance for both polarizations can be obtained by application of an anti-reflection coating layer at the input face. Polarization-independent beam splitting occurs in a narrow range around the target wavelength, while its transverse-magnetically polarized sub-harmonic can also be split. The photonic crystal can also operate as a polarizing splitter at oblique incidence. 相似文献
50.
Ren Zhang Gurpreet Singh Alei Dang Lu Dai Michael R. Bockstaller Bulent Akgun Sushil Satija Alamgir Karim 《Macromolecular rapid communications》2013,34(20):1642-1647
Sharp dynamic thermal gradient (∇T ≈ 45 °C mm−1) field‐driven assembly of cylinder‐forming block copolymer (c‐BCP) films filled with PS‐coated gold nanoparticles (AuNPs; dNP ≈ 3.6 nm, φNP ≈ 0–0.1) is studied. The influence of increasing AuNP loading fraction on dispersion and assembly of AuNPs within c‐BCP (PS‐PMMA) films is investigated via both static and dynamic thermal gradient fields. With φNP increasing, a sharp transition from vertical to random in‐plane horizontal cylinder orientation is observed due to enrichment of AuNPs at the substrate side and favorable interaction of PMMA chains with gold cores. Furthermore, a detachable capping elastomer layer can self‐align these random oriented PMMA microdomains into unidirectional hybrid AuNP/c‐BCP nanolines, quantified with an alignment order parameter, S.