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51.
Ahmadi F Jamali N Jahangard-Yekta S Jafari B Nouri S Najafi F Rahimi-Nasrabadi M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1004-1012
We report a multispectroscopic, voltammetric and theoretical hybrid of QM/MM study of the interaction between double-stranded DNA containing both adenine-thymine and guanine-cytosine alternating sequences and chloridazon (CHL) herbicide. The electrochemical behavior of CHL was studied by cyclic voltammetry on HMDE, and the interaction of ds-DNA with CHL was investigated by both cathodic differential pulse voltammetry (CDPV) at a hanging mercury drop electrode (HMDE) and anodic differential pulse voltammetry (ADPV) at a glassy carbon electrode (GCE). The constant bonding of CHL-DNA complex that was obtained by UV/vis, CDPV and ADPV was 2.1×10(4), 5.1×10(4) and 2.6×10(4), respectively. The competition fluorescence studies revealed that the CHL quenches the fluorescence of DNA-ethidium bromide complex significantly and the apparent Stern-Volmer quenching constant has been estimated to be 1.71×10(4). Thermal denaturation study of DNA with CHL revealed the ΔTm of 8.0±0.2°C. Thermodynamic parameters, i.e., enthalpy (ΔH), entropy (ΔS°), and Gibbs free energy (ΔG) were 98.45 kJ mol(-1), 406.3 J mol(-1) and -22.627 kJ mol(-1), respectively. The ONIOM, based on the hybridization of QM/MM (DFT, 6.31++G(d,p)/UFF) methodology, was also performed using Gaussian 2003 package. The results revealed that the interaction is base sequence dependent, and the CHL has more interaction with ds-DNA via the GC base sequence. The results revealed that CHL may have an interaction with ds-DNA via the intercalation mode. 相似文献
52.
Amikacin is a semisynthetic aminoglycoside antibiotic derived from kanamycin A that lacks a strong UV absorbing chromophore or fluorophore. Due to the physicochemical properties of amikacin and its related substances, CE in combination with capacitively coupled contactless conductivity detection (CE-C(4) D) was chosen. The optimized separation method uses a BGE composed of 20 mM MES adjusted to pH 6.6 by l-histidine and 0.3 mM CTAB that was added as flow modifier in a concentration below the CMC. Ammonium acetate 20 mg.L(-1) was used as internal standard. 30 kV was applied in reverse polarity on a fused silica capillary (73/48 cm; 75 μm id). The optimized separation was obtained in less than 6 min with good linearity (R(2) = 0.9996) for amikacin base. It shows a good precision expressed as RSD on relative peak areas equal to 0.1 and 0.7% for intraday and interday, respectively. The LOD and LOQ are 0.5 mg.L(-1) and 1.7 mg.L(-1) , respectively. 相似文献
53.
A nanoscale graphene oxide-peptide biosensor for real-time specific biomarker detection on the cell surface 总被引:1,自引:0,他引:1
Z Wang P Huang A Bhirde A Jin Y Ma G Niu N Neamati X Chen 《Chemical communications (Cambridge, England)》2012,48(78):9768-9770
A nanoscale RGD-pyrene-graphene oxide (GO) biosensor was prepared for real-time in situ detection of a cancer cell surface marker, integrin αvβ3. This nanoscale GO-based biosensor is simple, robust, sensitive and of high selectivity. It can also be adapted to other cancer cell surface marker evaluation systems. 相似文献
54.
Parviz Parvin Seyedeh Zahra Mortazavi Mohamad Nouri Korabaslo 《Optics & Laser Technology》2012,44(7):2161-2167
A storage ring free-electron laser (SR-FEL) is inherently a self-mode-locked optical system. The gain broadening due to electron energy spread affects the small signal gain in order to determine the output coupling. Here, the dependence of the small signal gain, the optimum output coupling, and pulse duration on both electron energy spread and loss of a Fabry–Perot resonator in UV SR-FEL were investigated. It was shown that the output coupling strongly affects the mode-locked pulse duration and the present picosecond pulses can be shortened to femtosecond ones using a proper low-loss resonator. 相似文献
55.
Carvalho AZ El-Attug MN da Silva JA Wolfs K D'Autry W Hoogmartens J Adams E Van Schepdael A 《Journal of separation science》2012,35(10-11):1336-1343
Sodium cysteamine phosphate is a prodrug derivative of cysteamine that can be used in cystinosis treatment. Although titrimetric assays are very well established and precise, iodimetric determination of sodium cysteamine phosphate requires considerably more carefulness and time from the analyst than usual. The possibility to assess sodium cysteamine phosphate by CE was evaluated by means of the quantification of its oxidation product, cystamine, which is a more suitable substance to be used as primary standard than sodium cysteamine phosphate. Apparently, this approach should be straightforward, but systematic differences between the results obtained with CE and titrimetric assays were noticed. MS and CE-MS were employed to aid in the investigation of the possible causes of imprecision of the sodium cysteamine phosphate titration and CE determination. For this purpose, a simple and inexpensive ESI source was constructed. It was observed that cystamine is not the final product of the cysteamine and/or sodium cysteamine phosphate iodine-oxidation and other species besides cystamine may be formed depending on the reaction conditions, which explains the difficulties observed in the sodium cysteamine phosphate quantification. 相似文献
56.
Sirous Nouri Rezvan Mohebbi Dolat Abad Morteza Bahram 《Journal of the Iranian Chemical Society》2012,9(3):397-405
In the present work the adsorption of aromatic compound, namely ??-naphthol (BN) by two granular activated carbons, one untreated and the other treated with HNO3 carried out under controlled conditions. The effects of experimental parameters on adsorption process such as pH, contact time and adsorbent dosage have been investigated. Experimental design methodology was applied to optimize the removal of ??-naphthol. The effect of various experimental parameters was investigated using five-level three-factorial central composite design (CCD). The relationship between the parameters and the response for model optimization was found and optimum conditions were obtained by CCD. In the optimum conditions obtained by response surface modeling, 100% BN was adsorbed on the carbons. Treatment with HNO3 led to a decrease in the point of zero charge and the adsorption capacity (Q max) of the activated carbon. The adsorption capacity of the carbons was determined using Freundlich and Langmuir homogenous equation. The variation of the model parameters with the solution pH was also studied. The fitted parameters obtained from both models showed the Q max value decrease with increasing of pH. 相似文献
57.
Khalili Shahla Khorasani Saied Nouri Razavi Seyed Mohammad Hashemibeni Batool Tamayol Ali 《Applied biochemistry and biotechnology》2019,187(4):1193-1203
Applied Biochemistry and Biotechnology - Treatments of skin injuries caused by trauma and diseases are among the most considerable medical problems. The use of scaffolds that can cover the wound... 相似文献
58.
Pedram Hanafizadeh Amirmohammad Sattari Seyed Erfan Hosseini-Doost Arash G. Nouri Mehdi Ashjaee 《Meccanica》2018,53(10):2461-2483
The effect of orifice shape on the mechanism of bubble formation in gas–liquid two-phase flow is investigated experimentally with three different orifice geometries regarding a circle, a square, and a triangle with same cross-sectional areas. The liquid and gas phases are purified water at 20 °C and air at room temperature, respectively. Gas is injected at the rate of 50–1200 mlph into a stagnant pool of liquid in distances of 5, 10, and 15 cm below the liquid surface. The position, velocity, and acceleration of bubbles are measured at bubbles’ centers of mass (CM) and the effects of these parameters on the bubble volume are investigated. Moreover, the forces acting on a bubble are balanced and the effects of geometry and gas flow rate on each force are presented. In addition, the changes of the acting forces versus time are plotted and discussed for a specific condition. Results show the bubbles formed with the square and circular orifice cross-sectional areas have the most and least volumes at detachment, respectively. 相似文献
59.
Azadeh Jafari Alireza Chitsaz Reza Nouri Timothy N. Phillips 《Theoretical and Computational Fluid Dynamics》2018,32(6):789-803
The challenge for computational rheologists is to develop efficient and stable numerical schemes in order to obtain accurate numerical solutions for the governing equations at values of practical interest of the Weissenberg number. This study presents a new approach to preserve the symmetric positive definiteness of the conformation tensor and to bound the magnitude of its eigenvalues. The idea behind this transformation lies with the matrix logarithm formulation. Under the logarithmic transformation, the eigenvalue spectrum of the new conformation tensor varies from infinite positive to infinite negative. However reconstructing the classical formulation from unbounded eigenvalues does not achieve meaningful results. This enhanced formulation, expressed in terms of the hyperbolic tangent, overcomes the failure of alternative formulations by bounding the magnitude of eigenvalues in a manner that positive definite is always satisfied. In order to evaluate the capability of the hyperbolic tangent formulation, we performed a numerical simulation of FENE-P fluid in a rectangular channel in the context of the finite element method. Under this new transformation, the maximum attainable Weissenberg number increases by 21.4% and 112.5% compared to the standard log-conformation and classical constitutive equation, respectively. 相似文献
60.
Anne Nouri Christian Schmeiser 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1996,47(4):553-566
Streamers are ionization waves in gas discharge devices, modelled here as travelling wave solutions of a drift-diffusion model for the transport of electrons and ions. The existence of a certain type of small amplitude streamers is proved by applying results from the theory of singularly perturbed ordinary differential equations. Global information is obtained from a large activation energy analysis.
Zusammenfassung Streamer sind lonisierungswellen in Gasentladungsröhren, die hier durch wandernde Wellenlösungen eines Drift-Diffusionsmodelles für den Transport von Elektronen und Ionen beschrieben werden. Die Existenz von Wellen eines bestimmten Typs mit kleiner Amplitude wird mit Hilfe von Resultaten über singulär gestörte gewöhnliche Differentialgleichungen bewiesen. Globale Information liefert eine Störungsanalyse für große Aktivierungsenergie.相似文献