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71.
Omer Andac Serkan Guney Yildiray Topcu Veysel T. Yilmaz William T. A. Harrison 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):m17-m20
Bis(pyridine‐2,6‐dimethanol‐N,O,O′)cobalt(II) disaccharinate dihydrate, [Co(C7H9NO2)2](C7H4NO3S)2·2H2O, (I), and bis(pyridine‐2,6‐dimethanol‐N,O,O′)copper(II) disaccharinate dihydrate, [Cu(C7H9NO2)2](C7H4NO3S)2·2H2O, (II), collectively [M(dmpy)2](sac)2·2H2O (where M is CoII or CuII, sac is the saccharinate anion and dmpy is pyridine‐2,6‐dimethanol), are isostructural. The [M(dmpy)2]2+ cations exhibit distorted octahedral geometry in which the two neutral dmpy species act as tripodal N,O,O′‐tridentate ligands. The crystal packing is determined by hydrogen bonding, as well as by weak pyridine–saccharinate π–π‐stacking interactions. 相似文献
72.
Invasion is a key property of tumour cells for building metastasis. A class of functionally related proteins called heat shock proteins (HSPs), the expression of which is increased when cells are exposed to elevated temperatures or other stress, play an important role in the invasion. In this paper we develop a mathematical model focusing on the effect of HSPs on the tumour cell migration. The resulting multiscale setting accounts both for the microscopic, intracellular level on which these proteins are acting and for the macroscopic level of the cell population. We prove the local existence of a unique positive solution and perform numerical simulations in order to illustrate the behaviour of cancer cells w.r.t. the fibre density of the tissue and the matrix degrading enzymes, along with the effect of HSPs. 相似文献
73.
Naumov P Topcu Y Eckert-Maksić M Glasovac Z Pavošević F Kochunnoonny M Hara H 《The journal of physical chemistry. A》2011,115(26):7834-7848
We report a solid-state photochemical rearrangement reaction by which aromatic N-chloroamides exposed to UV light or sunlight are rapidly and efficiently converted to chloroaromatic amides. The course, the intermediate (nascent chlorine vs dichlorine) and the outcome of the reaction depend on the excitation (exposure time, wavelength, and intensity) and on inherent structural factors (the directing role of the substituents and, as demonstrated by the different reactivity of two polymorphs of N-chlorobenzanilide, the supramolecular structure). The photolysis of the chloroamides provides facile photochemical access to arylamidyl radicals as intermediates, which in the absence of strong hydrogen bond donors are stabilized in the reactant crystals by C-H/N-Cl···π interactions, thus, providing insight into their structure and chemistry. Thorough theoretical modeling of the factors determinant to the stability and the nature of the spin-hosting orbital evidenced that although the trans-Π(||) state (Np spin) of the amidyls is normally preferred over the trans-Σ(⊥) configuration (Nsp(2) spin), stabilization by aromatic conjugation, steric and geometry factors, as well as by electronic effects from the substituents can decrease the Π-Σ gap in these intermediates significantly, resulting in similar and, in the case of the orthogonal amide-phenyl disposition, even reversed population of the unpaired electron in the two orbitals. Quantitative correlation established that the inverted occupational spin stability and the Π(N)-Σ(N) crossover are collectively facilitated by the conformation, valence angle, and disposition of the amide group relative to the aromatic system. The stabilization and detection of a trans-Σ(⊥) radical was experimentally accomplished by steric locking of the orthogonal trans-amide conformation with double ortho-tert-butyl substitution at the phenyl ring. The effects of the single para-phenyl substituents on the relative occupational stability of the arylamidyl radical states point out to non-Hammett behavior. By including cumulative electronic effects from multiple substitutions, four distinct families of the aromatic amidyl radicals were identified. The Π(∥) state is the most stable structure of the N-phenylacetamidyl radical and of most of the substituted arylamidyls, although the Σ(⊥) and Π(⊥) states can also be stabilized by introducing tert-butyl and nitro groups, respectively. 相似文献
74.
Meral Topcu Sulak Elif Erhan Bülent Keskinler 《Applied biochemistry and biotechnology》2010,160(3):856-867
Polyvinylferrocene (PVF) was used as a mediator for the fabrication of a horseradish peroxidase (HRP)-modified electrode to detect phenol derivatives via a composite polymeric matrix of conducting polypyrrole (PPy). Through an electropolymerization process, enzyme HRP was entrapped with PPy in a three-electrode system onto a glassy carbon electrode previously covered with PVF, resulting in a composite polymeric matrix. Steady-state amperometric measurements were performed at ?200 mV vs. Ag/AgCl in aqueous phosphate buffer containing NaCl 0.1 M (pH 6.8) in the presence of hydrogen peroxide. The response of the HRP-modified PVF electrode was investigated for various phenol derivatives, which were 4-chlorophenol, phenol, catechol, hydroquinone, 2-aminophenol, pyrogallol, m-cresol, and 4-methoxyphenol. Analytical parameters for the fabricated PVF electrode were obtained from the calibration curves. The highest sensitivity was obtained from the calibration of 4-chlorophenol as 29.91 nA/μM. The lowest detection limit was found to be 0.22 μM (S/N?=?3) for catechol, and the highest detection limit was found to be 0.79 μM (S/N?=?3) for 4-methoxyphenol among the tested derivatives. The biosensor can reach 95% of steady-state current in about 5 min. The electrode is stable for 2 months at 4 °C. 相似文献
75.
Selçuk Demir Günay Kaya Kantar Yıldıray Topcu Qiaowei Li 《Transition Metal Chemistry》2012,37(3):257-263
The complexes [Co(C4H4O4)]n (1) and [Zn(im)2(C4H4O4)]n
(2) (C4H4O4 = succinate dianion, suc; im = imidazole) have been synthesized solvothermally and characterized by elemental analysis, IR,
TG–DTA, and single-crystal X-ray diffraction techniques. Complex 1 is the first anhydrous member of the cobalt succinate family and has high thermal stability under a static air atmosphere,
up to 425 °C, and complex 2 is a 1D coordination polymer. In addition, a new synthesis method and some properties of the known [Co(HCOO)2·2H2O]n (3) complex are reported. After in situ synthesis of 3 via decomposition of DMF at 140 °C, it was found that complex 3 can adsorb some solvents repeatedly and is selective for H2O. 相似文献
76.
Meral Eral 《光谱学快报》2013,46(4):431-440
The feasibility of determining uranium in natural waters for uranium exploration using dibenzoil methane (DBM) by the adsorption of U(VI) on ferric hydroxide, was investigated. The yields of coprecipitation were determined by a Scintrex UA-3 laser fluorimetric uranium analyser using standard uranium solutions. After dissolving the coprecipitate, uranium was selectively separated by carbonate precipitation and determined with DBM. Fe(OH)3 - DBM method was controlled using both standard solutions and uranium analyser measurements of some natural water samples taken from Northern Ege Region where detailed radiometric investigation has been going on. The advantage of this method 相似文献
77.
Meccanica - Increasing application of composite structures in engineering field inherently speed up the studies focusing on the investigation of non-homogeneous bodies. Due to their capability on... 相似文献
78.
Blewitt G LoSecco JM Bionta RM Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,55(20):2114-2117
79.
Meral G. Babaoğlu Serap Safran Özlem Çiçek Hasan Ağıl Ercan Ertekin Md.Shahriar A. Hossain Ekrem Yanmaz Ali Gencer 《Journal of magnetism and magnetic materials》2012
The effect of aromatic hydrocarbon (benzene, C6H6) addition on lattice parameters, microstructure, critical temperature (Tc), critical current density (Jc) of bulk MgB2 has been studied. In this work only 2 mol% C6H6 addition was found to be very effective in increasing the Jc values, while resulting in slight reduction of the Tc. Jc values of 2 mol% C6H6 added MgB2 bulks reached to 1.83×106 A/cm2 at 15 K and 0 T. Microstructural analyses suggest that Jc enhancement is associated with the substitution of carbon with boron and which also results in the smaller MgB2 grain size. The change in the lattice parameters or the lattice disorder is claimed as a cause of the slight reduction in the Tc by carbon addition. We note that our results show the advantages of C6H6 addition include homogeneous mixing of precursor powders, avoidance of expansive nanoadditives, production of highly reactive C, and significant enhancement in Jc of MgB2, compared to un-doped samples. 相似文献
80.