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81.
Anastasia N. GeorgopoulouConstantinos G. Efthymiou Constantina PapatriantafyllopoulouVassilis Psycharis Catherine P. RaptopoulouManolis Manos Anastasios J. TasiopoulosAlbert Escuer Spyros P. Perlepes 《Polyhedron》2011,30(18):2978-2986
The synthetic investigation of the NiII/M(NO3)3·6H2O/di-2-pyridyl ketone [(py)2CO] tertiary reaction system in EtOH has yielded triangular Ni2M cationic complexes (M = lanthanide, Y). The reaction between Ln(NO3)3·6H2O, Ni(ClO4)2·6H2O, (py)2CO and base (1:3:3:3) in EtOH under gentle heating gave the isostructural complexes [Ni2Ln{(py)2C(OEt)(O)}3{(py)2C(OH)(O)}(NO3)(H2O)](ClO4)2 (Ln = Gd, 2; Ln = Tb, 3) in high yields. The ligands (py)2C(OEt)(O)− and (py)2C(OH)(O)− are the monoanions of the hemiketal and gem-diol derivatives of (py)2CO, respectively, formed in situ in the presence of the metal ions. The cations of 2 and 3 consist of one 8-coordinate LnIII and two distorted octahedral NiII atoms in an essentially isosceles, triangular arrangement capped by a central μ3-Ο− atom of the unique 3.3011 (Harris notation) (py)2C(OH)(O)− ligand. Each metal-metal edge is bridged by the deprotonated O atom of one 2.2011 (py)2C(OEt)(O)− ligand. The isostructural complexes [Ni2M{(py)2C(OEt)(O)}4(NO3)(H2O)]2[M(NO3)5](ClO4)2 (M = Y, 4 ; M = Tb, 5 ; M = Dy, 6) were prepared by the 1:1 reaction of the mononuclear “metalloligand” [Ni(O2CMe){(py)2CO}{(py)2C(OH)2}](ClO4) (1) and M(NO3)3·6H2O in EtOH under mild heating in moderate to good yields. The structures of the dications of 4-6 are similar to those in 2 and 3, the only difference being the replacement of the unique 3.3011 (py)2C(OH)(O)− ligand of the latter by one 3.3011 (py)2C(OEt)(O)− group in the former. The YIII, TbIII and DyIII atoms in [M(NO3)5]2− are coordinated by five bidentate chelating nitrato groups. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the ligands. Variable temperature, solid-state direct current magnetic susceptibility and magnetization studies were carried out on dried samples of 2-4. The data indicate ferromagnetic Ni?Ni and Ni?Gd exchange interactions, and an ST = 11/2 ground state for 2. Complex 3 is characterized by a high-spin ground state while the ferromagnetic Ni?Ni interaction for 2 is independently supported by the study of 4. No out-of-phase, alternating current susceptibility signals have been detected for 3 that would be indicative of SMM behavior. 相似文献
82.
Josef Jan?a V��ra Halabalov�� Vladim��r Pol��?ek Martin Va?ina Anastasia Yu. Menshikova 《Analytical and bioanalytical chemistry》2011,399(4):1481-1491
The behavior of microparticles exposed to gravitational and lift forces and to the velocity gradient in flow velocity profile formed in microfluidic conduits is studied from the viewpoint of the transient period (the relaxation) between the moment at which a particle starts to be transported by the hydrodynamic flow and the time at which it reaches an equilibrium position, characterized by a balance of all active forces. The theoretical model allowing the calculation of the relaxation time is proposed. The numerical calculus based on the proposed model is compared with the experimental data obtained under different experimental conditions, namely, for different lengths of microfluidic channels, different average linear velocities of the carrier liquid, and different sizes and densities of the particles used in the study. The results are important for the optimization of microfluidic separation units such as microthermal field-flow fractionation channels in which the separation or manipulation of the microparticles of various origin, synthetic, natural, biological, etc., is performed under similar experimental conditions but by applying an additional thermodynamic force. Figure
Trajectory of a particle transported by fluid flow in microfluidic channel and undergoing the effect of external filed force and lift force. 相似文献
83.
Pharmaceutical residues in environmental waters and wastewater: current state of knowledge and future research 总被引:4,自引:0,他引:4
Pollution from pharmaceuticals in the aquatic environment is now recognized as an environmental concern in many countries.
This has led to the creation of an extensive area of research, including among others: their chemical identification and quantification;
elucidation of transformation pathways when present in wastewater-treatment plants or in environmental matrices; assessment
of their potential biological effects; and development and application of advanced treatment processes for their removal and/or
mineralization. Pharmaceuticals are a unique category of pollutants, because of their special characteristics, and their behavior
and fate cannot be simulated with other chemical organic contaminants. Over the last decade the scientific community has embraced
research in this specific field and the outcome has been immense. This was facilitated by advances in chromatographic techniques
and relevant biological assays. Despite this, a number of unanswered questions exist and still there is much room for development
and work towards a more solid understanding of the actual consequences of the release of pharmaceuticals in the environment.
This review tries to present part of the knowledge that is currently available with regard to the occurrence of pharmaceutical
residues in aquatic matrices, the progress made during the last several years on identification of such compounds down to
trace levels, and of new, previously unidentified, pharmaceuticals such as illicit drugs, metabolites, and photo-products.
It also tries to discuss the main recent findings in respect of the capacity of various treatment technologies to remove these
contaminants and to highlight some of the adverse effects that may be related to their ubiquitous existence. Finally, socioeconomic
measures that may be able to hinder the introduction of such compounds into the environment are briefly discussed. 相似文献
84.
Maffeo D Velkov Z Misiakos K Mergia K Paulidou A Zavali M Mavridis IM Yannakopoulou K 《Journal of colloid and interface science》2011,358(2):369-375
The monitoring of the antibacterial agent triclosan binding at nanomolar concentration from an aqueous solution by employing a well-packed monolayer with a predetermined single orientation made of specifically synthesized 2,3-dimethyl-6-(undec-10-enamide)-6-deoxy-β-cyclodextrin (DMBUA) on a silicon wafer (Si/SiO(2)) coated with a novolac resin is reported. A white light reflectance spectroscopy (WLRS) setup was used for the real-time monitoring of the DMBUA deposition and triclosan binding processes. Film thicknesses obtained by WLRS were in very good agreement with the ones measured by X-ray reflectivity (XRR) experiments. Triclosan binds strongly to the DMBUA monolayer (logK(assoc)=6.68). NMR studies in aqueous solution indicated that the chlorophenolyl ring rather than the dichlorophenyl ring is preferentially inserted into DMBUA cups. The current detecting system that requires no tedious surface chemistry, no thiolated cyclodextrins, no gold surfaces, and no expensive equipment may be useful in capturing small molecules and may permit various applications, e.g., preparation of antimicrobial surfaces. 相似文献
85.
Acid-base interaction between transition-metal hydrides: dihydrogen bonding and dihydrogen evolution
86.
87.
Russian Physics Journal - The flow of current in a gas gap between a concave plasma cathode and a positive electrode is considered. A simplified theoretical model is used to obtain the conditions... 相似文献
88.
Conclusions A new scheme of synthesis was devised for 3-ethyl-4-p-methoxypheny1-2-methy1-3-cyclohexene-1-carboxylic acid — an analog of dehydrodoisynolic acid with a deeyclized ring B —in which the key stage is the diene condensation of 3-ethyl-2-p-methoxyphenyl-1,3-pentadiene with acrylic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 624–628, March, 1967. 相似文献
89.
90.
G. V. Levina 《Fluid Dynamics》1985,20(3):344-347
In this article the author discusses the results of a numerical investigtion of peristaltic flow at finite Reynolds numbers and finite wave numbers and amplitudes of the traveling wave at the channel walls. The limits of applicability of the data of the asymptotic analysis carried out [6] by means of separate expansions in powers of the Reynolds number and the wave number are determined. It is shown that with increase in the Reynolds number the possibility of transition, under certain conditions, to the flow structure corresponding to nonaxial trapping is preserved.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 11–15, May–June, 1985.The author wishes to thank E. M. Zhukhovitskii for his interest in the work. 相似文献