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611.
Solid state and solution 51V and 13C NMR studies on four fundamental bisperoxovanadium complexes containing bidendate donor ligands were reported, together with DFT calculations of structural and NMR parameters. The 51V solid-state NMR characterization of the four complexes with [VO(O2)2L]n− anion {abbr. bpVL, where L = oxalic acid dianion (ox), pyridine-2-carboxylic acid (pic), bipyridine (bipy), and 1,10-phenanthroline (phen)} show that the ligands have a significant effect on the electric-field gradient tensor, with the quadrupolar coupling constant ranging from 4.0 to 5.8 MHz. The experimental and theoretical results suggest that the vanadium center of bpVpic, bpVphen and bpVbipy in solid state and aqueous solution are all seven-coordinated except that bpVox is six-coordinated in aqueous solution. The steric space hindrance of the organic ligands and the bonding between vanadium with the coordination influences the activity of bpVL complexes. 相似文献
612.
As a result of the spread of TYLCV on tomato crops, reliable and rapid diagnostic tools to identify and isolate new sources
of infection are necessary. We tested several methods, based both on antibodies and on nonradioactive DNA probes. Indirect
plate-trapping ELISA was only effective in detecting the virus in purified preparations, but not in crude extracts. Dot-ELISA
with chemiluminescence detection gave satisfactory results when young stems were directly squashed on membranes. A digoxigenin-labeled
probe, detected with chemiluminescence, was used in leaf squashes and dot blots. Best results were obtained with dot blots
of total nucleic acids prepared with a fast and safe procedure. TYLCV DNA was readily and reliably detected in spots corresponding
to 15 μg fresh weight. When weak signals were observed, total extracts were analyzed by Southern blotting, to confirm the
presence of viral DNA forms. 相似文献
613.
Kalpesh D. Mahajan Qirui Fan Jenny Dorcéna Gang Ruan Dr. Jessica O. Winter 《Biotechnology journal》2013,8(12):1424-1434
Quantum dots (QDs) have great promise in biological imaging, and as this promise is realized, there has been increasing interest in combining the benefits of QDs with those of other materials to yield composites with multifunctional properties. One of the most common materials combined with QDs is magnetic materials, either as ions (e.g. gadolinium) or as nanoparticles (e.g. superparamagnetic iron oxide nanoparticles, SPIONs). The fluorescent property of the QDs permits visualization, whereas the magnetic property of the composite enables imaging, magnetic separation, and may even have therapeutic benefit. In this review, the synthesis of fluorescent–magnetic nanoparticles, including magnetic QDs is explored; and the applications of these materials in imaging, separations, and theranostics are discussed. As the properties of these materials continue to improve, QDs have the potential to greatly impact biological imaging, diagnostics, and treatment. 相似文献
614.
Quantum chemical study of the inhibition of the corrosion of mild steel in H2SO4 by some antibiotics
Nnabuk O. Eddy Udo J. Ibok Eno E. Ebenso Ahmed El Nemr El Sayed H. El Ashry 《Journal of molecular modeling》2009,15(9):1085-1092
The inhibition efficiency of some antibiotics against mild steel corrosion was studied using weight loss and quantum chemical
techniques. Values of inhibition efficiency obtained from weight loss measurements correlated strongly with theoretical values
obtained through semi empirical calculations. High correlation coefficients were also obtained between inhibition efficiency
of the antibiotics and some quantum chemical parameters, including frontier orbital (E
HOMO and E
LUMO), dipole moment, log P, TNC and LSER parameters (critical volume and dipolar-polarisability factor), which indicated that these parameters affect
the inhibition efficiency of the compounds. It was also found that quantitative structure activity relation can be used to
adequately predict the inhibition effectiveness of these compounds. 相似文献
615.
616.
The fluorescence emission spectrum of Synechocystis sp. PPC6803 cells, at room temperature, displays: i) significant bandshape variations when collected under open (F0) and closed (FM) Photosystem II reaction centre conditions; ii) a marked dependence on the excitation wavelength both under F0 and FM conditions, due to the enhancement of phycobilisomes (PBS) emission upon their direct excitation. As a consequence: iii) the ratio of the variable and maximal fluorescence (FV/FM), that is a commonly employed indicator of the maximal photochemical quantum efficiency of PSII (Φpc, PSII), displays a significant dependency on both the excitation and the emission (detection) wavelength; iv) the FV/FM excitation/emission wavelength dependency is due, primarily, to the overlap of PSII emission with that of supercomplexes showing negligible changes in quantum yield upon trap closure, i.e. PSI and a PBS fraction which is incapable to transfer the excitation energy efficiently to core complexes. v) The contribution to the cellular emission and the relative absorption-cross section of PSII, PSI and uncoupled PBS are extracted using a spectral decomposition strategy. It is concluded that vi) Φpc, PSII is generally underestimated from the FV/FM measurements in this organism and, the degree of the estimation bias, which can exceed 50%, depends on the measurement conditions. Spectral modelling based on the decomposed emission/cross-section profiles were extended to other processes typically monitored from steady-state fluorescence measurements, in the presence of an actinic illumination, in particular non-photochemical quenching. It is suggested that vii) the quenching extent is generally underestimated in analogy to FV/FM but that viii) the location of quenching sites can be discriminated based on the combined excitation/emission spectral analysis. 相似文献
617.
The intracellular channel of information transmission was analyzed from the point of view of complexity. The most important steps in the transfer of information within a cell are the folding, transport and recognition of proteins. It was shown that the large number of conformational degrees of freedom that proteins possess can paradoxically lead to an information channel with an exponentially small capacity. To resolve this paradox, a model, which assumes a quantum collective behavior of biologically important molecules, was proposed. Experiments to test the quantum nature of the intracellular transfer of information were also proposed. 相似文献
618.
Atrazine is a common agricultural pesticide which has been reported to occur widely in surface drinking water, making it an environmental pollutant of concern. In the quest for developing sensitive detection methods for pesticides, the use of quantum dots (QDs) as sensitive fluorescence probes has gained momentum in recent years. QDs have attractive and unique optical properties whilst coupling of QDs to molecularly imprinted polymers (MIPs) has been shown to offer excellent selectivity. Thus, the development of QD@MIPs based fluorescence sensors could provide an alternative for monitoring herbicides like atrazine in water. In this work, highly fluorescent CdSeTe/ZnS QDs were fabricated using the conventional organometallic synthesis approach and were then encapsulated with MIPs. The CdSeTe/ZnS@MIP sensor was characterized and applied for selective detection of atrazine. The sensor showed a fast response time (5 min) upon interaction with atrazine and the fluorescence intensity was linearly quenched within the 2–20 mol L?1 atrazine range. The detection limit of 0.80 × 10?7 mol L?1 is comparable to reported environmental levels. Lastly, the sensor was applied in real water samples and showed satisfactory recoveries (92–118%) in spiked samples, hence it is a promising candidate for use in water monitoring. 相似文献
619.
620.