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91.
Three dinuclear and one mononuclear copper(II)-1,10-phenanthroline ternary complexes, [Cu(L1)(phen)(OH)]2 (1), [Cu(L2)(phen)(OH)]2·3H2O (2), [Cu(L3)(phen)(OH)]2 (3) and [Cu(L4)2(phen)(H2O)] (4), with thiadiazole sulfonamide derivative ligands: HL1 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)naphthalene-1-sulfonamide), HL2 (N-(5-ethylthio)-1,3,4-thiadiazol-2-yl)-4-methylbenzenesulfonamide), HL3 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide) and HL4 (N-(5-ethyl-1,3,4-thiadiazol-2-yl)-4-methylbenzenesulfonamide) have been synthesized and characterized. In the four complexes each copper atom is five-coordinated. The structure of complexes 1, 2 and 3 consists of a dimeric unit with a C2 symmetry axis, where both coppers are bridged by two hydroxo anions. Magnetic measurements show that the dimer complexes are ferromagnetic according to the Cu–O–Cu angles. Cleavage experiments using pUC18 plasmid DNA in the presence of H2O2/ascorbic acid as an activating agent show that the title complexes are potent artificial chemical nucleases, the order of efficiency being 3 > 2 ∼ 1 > 4. Control cleavage experiments indicated that the dimer complexes are stronger artificial nucleases than the [Cu(phen)2]2+ complex under the same experimental conditions, while the monomer 4 has a lower nuclease activity than the [Cu(phen)2]2+ complex. The inhibition of the cleavage process in the presence of reactive oxygen intermediate scavengers suggests that the hydroxyl radical and the superoxide anion are reactive species for the breakage of the DNA strands. 相似文献
92.
Elena Olaret Jana Ghitman Horia Iovu Andrada Serafim Izabela‐Cristina Stancu 《先进技术聚合物》2020,31(4):645-653
Although widely used as implantable materials due to their mechanical properties, metal devices show several disadvantages, such as the lack of cellular binding sites, antibacterial properties, or lubricant properties. To this end, the development of engineered surfaces through protein coatings has been largely investigated. Due to their natural origin and complex structure which allows the formation of hydrogels, mucins have been proposed and investigated as effective coatings for metallic implants. The present study evaluates the ability of porcine gastric mucin (PGM) to form stable coatings on a model metal surface, using three buffers with different pH values, ranging from acid to alkaline, as dispersion media. Considering its large number of hydroxyl groups and its ability to form hydrogen bonds with the protein, tannic acid (TA) was used as cross‐linker. In addition to coatings' thickness and elasticity assessed through Quartz Crystal Microbalance with Dissipation monitoring (QCM‐D), the study also evaluates the interactions between PGM and TA at various pH values of the dispersion media through DLS. The corroborated results show that the neutral pH allows the best interactions between PGM and TA leading to the formation of a stable, less elastic coating when compared with that obtained using as dispersion media the other two investigated buffers. Moreover, the hydrophilicity and mechanical properties of the dried coatings were assessed through contact angle measurements and nanoindentation, respectively. 相似文献
93.
94.
Re-examination of dynamical ionic polarizabilities in water solutions leads to the formulation of a solution function r(c), which combines the indices of refraction and mass densities of solutions. We show that this function should be independent of ionic concentration if the composite polarizabilities of hydrated solute clusters are constant. Using existing experimental data for a number of aqueous salt and organic solutions, we find that the r(c) function is either constant or varies linearly with concentration, in most cases with negligible slope. We use this function to compare ionic polarizabilities of crystals and aqueous solutions and to highlight how solute polarizabilities at infinite dilution scale with the electronic valence shell of cations and anions. The proposed r(c) function can be used generally to verify the consistency of experimental measurements and of simulation results, and it provides a test of assumptions in current theories of ionic polarizabilities. 相似文献
95.
Consider a quantum dot coupled to two semi-infinite one-dimensional leads at thermal equilibrium. We turn on adiabatically a bias between the leads such that there exists exactly one discrete eigenvalue both at the beginning and at the end of the switching procedure. For a specific adiabatic limit scenario, it is shown that the expectation in the final bound state strongly depends on the history of the switching procedure. On the contrary, the contribution to the final steady-state corresponding to the continuous spectrum has no memory, and only depends on the initial and final values of the bias. 相似文献
96.
Horia Chiriac Nicoleta Lupu Laurentiu Stoleriu Petronel Postolache Alexandru Stancu 《Journal of magnetism and magnetic materials》2007
In this paper we present the results of applying the first-order reversal curves (FORC) diagram experimental method to the analysis of the magnetization processes of NdFeB-based permanents magnets. The FORC diagrams for this kind of exchange spring magnets show the existence of two magnetic phases—a soft magnetic phase and a hard magnetic one. Micromagnetic modeling is used for validating the hypotheses regarding the origin of the different features of the experimental FORC diagrams. 相似文献
97.
New magnetic organic–inorganic composites based on hydrotalcite-like anionic clays for drug delivery
The structural “memory effect” of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin–hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments. 相似文献
98.
Briet Philippe Cornean Horia D. Zagrebnov Valentin A. 《Journal of statistical physics》2004,116(5-6):1545-1578
It has been known since the paper(26) and then due to a rigorous result(3) that the answer to the question in the title is negative for a three-dimensional “ideal gas of charged bosons”. The present paper adds a new rigorous result in this direction. We show that the answer to the question becomes positive, if this “ideal gas of charged bosons” is simultaneously embedded in an appropriate periodic external potential. We prove that it is true for the Perfect Bose Gas (PBG), as well as for the Imperfect Bose Gas with a Mean-Field repulsive particle interaction. 相似文献
99.
Horia D. Cornean 《Journal of Functional Analysis》2007,247(1):1-94
We consider the long time behavior of a quantum particle in a 2D magnetic field which is homogeneous of degree −1. If the field never vanishes, above a certain energy the associated classical dynamical system has a globally attracting periodic orbit in a reduced phase space. For that energy regime, we construct a simple approximate evolution based on this attractor, and prove that it completely describes the quantum dynamics of our system. 相似文献
100.
Horia M. Nizam El‐Din 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1209-1215
Hydrogels based essentially on N‐isopropylacrylamide (NIPAAm) and different ratios of ethylene glycol dimethacrylate (EGDMA) monomer were synthesized by gamma radiation copolymerization. The thermal decomposition behavior of NIPAAm/EGDMA hydrogels was determined by thermogravimetric analysis (TGA). The effect of temperature and pH on the swelling behavior was also studied. The results showed that the ratio of EGDMA in the comonomer feeding solution has a great effect on the yield product, gel fraction and water content in the final hydrogel. In this regard, it was observed that the increase of EGDMA ratio decreased these properties. The TGA study showed that all the compositions of NIPAAm/EGDMA hydrogels displayed higher thermal stability than the hydrogel based on pure PNIPAAm hydrogel. The swelling kinetics in water showed that pure PNIPAAm and NIPAAm/EGDMA hydrogels reached equilibrium after 6 h. However, NIPAAm/EGDMA hydrogels show swelling in water lower than pure PNIPAAm. The results showed that the swelling character of pure PNIPAAm and NIPAAm/EGDMA hydrogels was affected by the change in temperature within the temperature range 25–40°C, and showed a reversible change in swelling in the pH range 4–7 depending on composition. 相似文献