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1.
The refined theory of the electroviscous lift forces is presented for the case when the separation distance between the particle and the wall is larger than the double-layer thickness. The theory is based on the lubrication approximation for motion of a long cylinder near a solid wall in creeping flow. The approximate analytical formula for the lift force valid for Pe=1 is derived and compared with the results of numerical calculations performed for an arbitrary Peclet number. The resulting electrokinetic lift force exceeds by several orders of magnitude one predicted by the previously developed theories of the lift force. The results for the electroviscous drag force indicate that when the double layer is thin compared with the particle size, the electroviscous drag is only a small correction (at most 10%) to the hydrodynamic drag force acting on a neutral particle moving near the wall. Copyright 2000 Academic Press. 相似文献
2.
Quantum chemical evaluation of protein control over heme ligation: CO/O2 discrimination in myoglobin
Control of O2 versus CO binding in myoglobin (Mb) is tuned by a distal histidine residue through steric and H-bonding interactions. These interactions have been evaluated via Car-Parrinello DFT calculations, whose efficiency allows full quantum mechanical treatment of the 13 closest residues surrounding the heme. The small (8 degrees ) deviation of the Fe-C-O bond angle from linearity results from the steric influence of a distal valine residue and not the distal histidine. H-bond energies were evaluated by replacing the distal histidine with the non-H-bonding residue isoleucine. Binding energies for CO and O2 decreased by 0.8 and 4.1 kcal/mol for MbCO and MbO2, in good agreement with experimental H-bond estimates. Ligand discrimination is dominated by distal histidine H-bonding, which is also found to stabilize a metastable side-on isomer of MbO2 that may play a key role in MbO2 photodynamics. 相似文献
3.
Carré V Gaud O Sylvain I Bourdon O Spiro M Blais J Granet R Krausz P Guilloton M 《Journal of photochemistry and photobiology. B, Biology》1999,48(1):57-62
A series of neutral meso-arylglycosylporphyrins has been tested in order to evaluate their potency as antifungal agents against the yeast Saccharomyces cerevisiae. Photodynamic activity of these molecules results in intracellular damage as evidenced by the loss of clonogenicity and DNA fragmentation. The ability of these photosensitizers to permeate yeast cells is determined by microspectrofluorimetry and is correlated with their antifungal potency. Amphiphilic porphyrin derivatives are shown to exhibit the more pronounced photoactivity. 相似文献
4.
Venkateshrao S Yin J Jarzecki AA Schultz PG Spiro TG 《Journal of the American Chemical Society》2004,126(50):16361-16367
Resonance Raman (RR) spectra are reported for mesoporphyrin IX bound to the Fab fragment of the ferrochelatase antibody 7G12. Binding induces activation of a Raman band at 680 cm(-1), which is assigned to an out-of-plane porphyrin vibration, gamma15. This is exactly the predicted effect of distorting mesoporphyrin to the geometry of N-methylmesoporphyrin IX, the 7G12 hapten, based on DFT/CIS modeling of the RR spectrum. The modeling also shows that the pyrrole ring that is tilted out of the porphyrin plane bears a nitrogen lone pair, which is therefore available for coordination by an incoming metal ion. The 680 cm(-1) band intensity is approximately 3 times higher for the affinity-matured antibody than for the germline precursor antibody, while intermediate values are found for variants in which germline residues are mutated to mature residues or vice versa. Thus, RR spectroscopy reveals an evolution from weak substrate distortion in the germline antibody to strong substrate distortion in the affinity-matured antibody, and supports the view that catalysis involves a substrate strain mechanism. 相似文献
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Maya M. Zaharieva Lyudmila L. Dimitrova Stanislav Philipov Ivanka Nikolova Neli Vilhelmova Petar Grozdanov Nadya Nikolova Milena Popova Vassya Bankova Spiro M. Konstantinov Dimitrina Zheleva-Dimitrova Hristo M. Najdenski 《Molecules (Basel, Switzerland)》2022,27(1)
This study evaluated the in vitro antineoplastic and antiviral potential and in vivo toxicity of twelve extracts with different polarity obtained from the herbaceous perennial plant Geum urbanum L. (Rosaceae). In vitro cytotoxicity was determined by ISO 10993-5/2009 on bladder cancer, (T-24 and BC-3C), liver carcinoma (HEP-G2) and normal embryonic kidney (HEK-293) cell lines. The antineoplastic activity was elucidated through assays of cell clonogenicity, apoptosis induction, nuclear factor kappa B p65 (NFκB p65) activation and total glutathione levels. Neutral red uptake study was applied for antiviral activity. The most promising G. urbanum extract was analyzed by UHPLC–HRMS. The acute in vivo toxicity analysis was carried out following OEDC 423. The ethyl acetate extract of aerial parts (EtOAc-AP) exhibited the strongest antineoplastic activity on bladder cancer cell lines (IC50 = 21.33–25.28 µg/mL) by inducing apoptosis and inhibiting NFκB p65 and cell clonogenicity. EtOAc and n-butanol extracts showed moderate antiviral activity against human adenovirus type 5 and human simplex virus type I. Seventy four secondary metabolites (gallic and ellagic acid derivatives, phenolic acids, flavonoids, etc.) were identified in EtOAc-AP by UHPLC–HRMS. This extract induced no signs of acute toxicity in liver and kidney specimens of H-albino mice in doses up to 210 mg/kg. In conclusion, our study contributes substantially to the detailed pharmacological characterization of G. urbanum, thus helping the development of health-promoting phytopreparations. 相似文献
7.
T. Caspersson Gösta Widström C. C. Lucas E. J. King J. H. W. Lugg H. Barnes R. A. Peters H. Fujiwara E. Kataoka M. X. Sullivan W. C. Hess H. D. Baernstein N. Bulgakow O. Fürth A. Friedrich R. School F. Fromm L. Binet G. Weller Regine Kapeller-Adler Emil Fischer G. Kollmann Mary A. B. Brazier Morner E. Abderhalden O. Kestner Osborne H. D. Dakin E. Schultze K. Spiro P. A. Levene R. H. Aders O. Gerngross W. Deseke W. F. Koelker D. D. van Slyke A. Hynd M. G. Mc Farlane E. Montignie 《Analytical and bioanalytical chemistry》1935,100(1-2):50-60
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Edwards GS Pearlstein RD Copeland ML Hutson MS Latone K Spiro A Pasmanik G 《Optics letters》2007,32(11):1426-1428
A four-stage laser system was developed, emitting at a wavelength of 6450 nm with a 3-5 ns pulse duration, < or = 2 mJ pulse energy, and 1/2 Hz pulse repetition rate. The laser system successfully ablated rat brain tissue, where both the collateral damage and the ablation rate compare favorably with that previously observed with a Mark-III Free-Electron Laser. 相似文献
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