共查询到20条相似文献,搜索用时 31 毫秒
1.
R. N. Nurmukhametov V. I. Berendyaev L. V. Volkova E. V. Lunina A. M. Sergeev 《Journal of Applied Spectroscopy》2010,77(4):522-526
Absorption and fluorescence spectra and fluorescence quantum yields of solutions and transparent films of polyalkanesterimides
(PAEI) were studied. The molecular chain of the investigated polyalkanesterimides contains phthalimide repeating units and
–(CH2)n– fragments where n = 6 and 10. It is shown that the fluorescent properties of such polymers are the same as those of low-molecular-weight phthalimide
luminophores. The alkane fragments contained in the polymer chain have been concluded to prohibit a charge-transfer transition
and thereby enhance the polyalkanesterimide fluorescence intensity. 相似文献
2.
Yaacov Kopeliovich 《Letters in Mathematical Physics》2010,94(3):313-333
Let X be a general cyclic cover of
\mathbbCP1{\mathbb{CP}^{1}} ramified at m points, λ1... λ
m
. we define a class of non-positive divisors on X of degree g −1 supported in the pre images of the branch points on X, such that the Riemann theta function does not vanish on their image in J(X). We generalize the results of Bershadsky and Radul (Commun Math Phys 116:689–700, 1988), Nakayashiki (Publ Res Inst Math Sci 33(6):987–1015, 1997) and Enolskii and Grava (Lett Math Phys 76(2–3):187–214, 2006) and prove that up to a certain determinant of the non-standard periods of X, the value of the Riemann theta function at these divisors raised to a high enough power is a polynomial in the branch point
of the curve X. Our approach is based on a refinement of Accola’s results for 3 cyclic sheeted cover (Accola, in Trans Am Math Soc 283:423–449,
1984) and a generalization of Nakayashiki’s approach explained in Nakayashiki (Publ Res Inst Math Sci 33(6):987–1015, 1997) for general cyclic covers. 相似文献
3.
The use of two-photon excitation of fluorescence for detection of fluorescence resonance energy transfer (FRET) was studied for a selected fluorescent donor–acceptor pair. A method based on labeled DNA was developed for controlling the distance between the donor and the acceptor molecules. The method consists of hybridization of fluorescent oligonucleotides to a complementary single-stranded target DNA. As the efficiency of FRET is strongly distance dependent, energy transfer does not occur unless the fluorescent oligonucleotides and the target DNA are hybridized. A high degree of DNA hybridization and an excellent FRET efficiency were verified with one-photon excited fluorescence studies. Excitation spectra of fluorophores are usually wider in case of two-photon excitation than in the case of one-photon excitation [1]. This makes the selective excitation of donor difficult and might cause errors in detection of FRET with two-photon excited fluorescence. Different techniques to analyze the FRET efficiency from two-photon excited fluorescence data are discussed. The quenching of the donor fluorescence intensity turned to be the most consistent way to detect the FRET efficiency. The two-photon excited FRET is shown to give a good response to the distance between the donor and the acceptor molecules. 相似文献
4.
Qi Xiao Shan Huang Yushu Ge Zhike He Yi Liu Jiangong Liang 《Journal of fluorescence》2010,20(2):541-549
As one of nucleic acid molecular “light switch”, Ru(bipy)2(dppx)2+ is a good probe for the determination of double-helical DNA, which displays intense fluorescence when double-helical DNA
is present. However, the fluorescence of Ru(bipy)2(dppx)2+ is quenched when Ag+ is added to the Ru(bipy)2(dppx)2+-DNA system. Based on the quenching of the fluorescence of Ru(bipy)2(dppx)2+-DNA system by Ag+, a simple, rapid and specific method for Ag+ determination was proposed. In the optimum conditions, Ag+ concentration versus Ru(bipy)2(dppx)2+ fluorescence intensity gave a linear response in the range from 0.2 to 6.0 μM with a detection limit (3σ) of 3.2 × 10−8 M. The proposed method has been applied to determine the Ag+ in water samples and sulfadiazine silver cream successfully. Because of the intense fluorescence of Ru(bipy)2dppx2+ when DNA is present, the interaction between Ag+ and DNA was confirmed by fluorescence microscopy and the phenomenon of the fluorescence images agreed well with the results.
The possible mechanism of the reaction was also discussed by circular dichroism spectra and isothermal titration calorimetry. 相似文献
5.
Yata PK Shilpa M Nagababu P Reddy MR Kotha LR Gabra NM Satyanarayana S 《Journal of fluorescence》2012,22(3):835-847
The three Ru(II) complexes of [Ru(phen)2dppca]2+ (1) [Ru(bpy)2dppca]2+ (2) and [Ru(dmb)2dppca]2+ (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand
containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and
characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light
switches, as evidenced by UV-visible and luminescence titrations with Co2+ and EDTA, steady-state emission quenching by [Fe(CN)6]4− and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest
that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm,
the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA. 相似文献
6.
Anatoliy K. Prykarpatsky Nikolai N. Bogolubov 《International Journal of Theoretical Physics》2012,51(1):237-245
R. Feynman’s “heretical” approach (Dyson in Am. J. Phys. 58:209–211, 1990; Dyson in Phys. Today 42(2):32–38, 1989) to deriving the Lorentz force based Maxwell electromagnetic equations is revisited, the its complete legacy is argued both
by means of the geometric considerations and its deep relation with the vacuum field theory approach devised (Prykarpatsky
et al. in Int. J. Theor. Phys. 49:798–820, 2010; Prykarpatsky et al. in Preprint ICTP, 2008, ). Being completely classical, we reanalyze the Feynman’s derivation from the classical Lagrangian and Hamiltonian points
of view and construct its nontrivial relativistic generalization compatible with the vacuum field theory approach. 相似文献
7.
O. V. Sizova V. I. Baranovskii A. I. Panin N. V. Ivanova 《Foundations of Physics Letters》2002,15(1):471-479
The dynamics of the intramolecular electron transfer from Ru(II) to Ru(III) in binuclear mixed-valence complexes [NH3)5Ru -L-Ru(NH3)5]5+
(L = N2, pyz, bipy, pym, bpa) is analyzed by the semiempirical CINDO + CI method.
Translated from ZhurnalStruktumoi Khimii, Vol. 39, No. 4, pp. 579–590, July–August, 1998. 相似文献
8.
A. Romannikov 《Foundations of Physics》2011,41(8):1331-1337
A relation between physical consequences of the so-called Ehrenfest’s Paradox and the radial electric field E
r
(r) in the classical quasi-neutral tokamak plasma is shown. Basic author’s approach to the relativistic nature of the tokamak
E
r
(r) has been described in Romannikov (J. Exp. Theor. Phys. 108:340–348, 2009). The experiment which can resolve the Ehrenfest’s Paradox is presented. 相似文献
9.
Su-Juan Qin 《International Journal of Theoretical Physics》2012,51(9):2714-2718
A controlled quantum secure direct communication protocol (Zhang et al. in Int. J. Theor. Phys. 48:2971–2976, 2009) by using four particle cluster states was proposed recently. Yang et al. presented an attack with fake entangled particles (FEP attack) and gave an improvement (Yang et al. in Int. J. Theor. Phys. 50:395–400, 2010). In this paper, we reexamine the protocol’s security and discover that, Bob can also take a different attack, disentanglement attack, to obtain Alice’s secret message without controller’s permission. Moreover, our attack strategy also works for Yang’s improvement. 相似文献
10.
Building on our earlier work (Misra and Shukla, Nucl. Phys. B 827:112, 2010; Phys. Lett. B 685:347–352, 2010), we show the possibility of generating “light” fermion mass scales of MeV–GeV range (possibly related to the first two generations
of quarks/leptons) as well as eV (possibly related to first two generations of neutrinos) in type IIB string theory compactified
on Swiss-Cheese orientifolds in the presence of a mobile space-time filling D3-brane restricted to (in principle) stacks of fluxed D7-branes wrapping the “big” divisor Σ
B
. This part of the paper is an expanded version of the latter half of Sect. 3 of a published short invited review (Misra,
Mod. Phys. Lett. A 26:1, 2011) written by one of the authors [AM]. Further, we also show that there are no SUSY GUT-type dimension-five operators corresponding
to proton decay, and we estimate the proton lifetime from a SUSY GUT-type four-fermion dimension-six operator to be 1061 years. Based on GLSM calculations in (Misra and Shukla, Nucl. Phys. B 827:112, 2010) for obtaining the geometric K?hler potential for the “big divisor,” using further the Donaldson’s algorithm, we also briefly
discuss in the first of the two appendices the metric for the Swiss-Cheese Calabi–Yau used, which we obtain and which becomes
Ricci flat in the large-volume limit. 相似文献
11.
A quantum-chemical calculation of the prodan molecule and its complexes in water for the geometry of the ground and fluorescent
states is carried out. To describe the fluorescent state, changes in the electronic state (population) on bonds and atoms
during transition of the molecule into an excited state are taken into account. A model of interaction of the prodan molecule
with a polar proton-donor solvent (water) is suggested. It is shown that interaction with the ionic forms (H3O+ provides an explanation for the sensitivity of prodan to the solvent (displacement of the fluorescence bands). The nature
of the electronic excited states of the prodan molecule and its complexes has been investigated. The constants of the rates
of radiative and nonradiative processes and the fluorescence quantum yields have been calculated.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 330–334, May–June, 2005. 相似文献
12.
Nucleosome Dynamics as Studied by Single-pair Fluorescence Resonance Energy Transfer: A Reevaluation
Accessibility of nucleosomal DNA to protein factor binding is ensured by at least three mechanisms: post-synthetic modifications
to the histones, chromatin remodeling, and spontaneous unwrapping of the DNA from the histone core. We have previously used
single-pair fluorescence resonance energy transfer (spFRET) experiments to investigate long-range conformational fluctuations
in nucleosomal DNA (Tomschik M, Zheng H, van Holde K, Zlatanova J, Leuba SH in Proc Natl Acad Sci USA 102(9):3278–3283, 2005). Recent work has drawn attention to a major artifact in such studies due to photoblinking of the acceptor fluorophore. We
have now used formaldehyde-crosslinked nucleosomes and imaging in the presence of Trolox, an efficient triplet-state quencher
that suppresses photoblinking, to reevaluate our previous conclusions. Careful analysis of the data indicates that most of
the events previously characterized as nucleosome ‘opening’ must have corresponded to photoblinking. There is, nevertheless,
evidence for the existence of infrequent, rapid opening events. 相似文献
13.
We begin with a review and analytical construction of quantum Gaussian process (and quantum Brownian motions) in the sense
of Franz (The Theory of Quantum Levy Processes, [math.PR], 2009), Schürmann (White noise on bioalgebras. Volume 1544 of Lecture Notes in Mathematics. Berlin: Springer-Verlag, 1993) and others, and then formulate and study in details (with a number of interesting examples) a definition of quantum Brownian
motions on those non-commutative manifolds (a la Connes) which are quantum homogeneous spaces of their quantum isometry groups
in the sense of Goswami (Commun Math Phys 285(1):141–160, 2009). We prove that bi-invariant quantum Brownian motion can be ‘deformed’ in a suitable sense. Moreover, we propose a non-commutative
analogue of the well-known asymptotics of the exit time of classical Brownian motion. We explicitly analyze such asymptotics
for a specific example on non-commutative two-torus Aq{\mathcal{A}_\theta} , which seems to behave like a one-dimensional manifold, perhaps reminiscent of the fact that Aq{\mathcal{A}_\theta} is a non-commutative model of the (locally one-dimensional) ‘leaf-space’ of the Kronecker foliation. 相似文献
14.
A novel ligand with double sulfinyl groups, bis(benzylsulfinyl)methane, was synthesized by a new method and its two lanthanide
(III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis,
IR, TG-DSC, 1HNMR and UV spectra. The results indicated that the composition of these complexes was REL2.5(ClO4)3·3H2O (RE = Tb (III), Dy (III), L = C6H5CH2SOCH2SOCH2C6H5). The FT-IR results revealed that the perchlorate group was bonded with the lanthanide ion by the oxygen atoms, and the coordination
was bidentate. The fluorescent spectra illustrated that both the Tb (III) and Dy (III) complexes displayed characteristic
fluorescence in solid state, especially for the Tb (III) complex, the peak of 5D4 → 7 F5 of the Tb (III) ion in 544 nm was stronger than that of others. It indicated that the Tb (III) complex could emit purer green
fluorescence. By analysis fluorescence and phosphorescence spectra, it was found that the ligand had the advantage to absorb
energy and transfer it to the Tb (III) and Dy (III) ions. The phosphorescence spectra and fluorescence lifetimes of the complexes
were also measured. 相似文献
15.
In this paper, we generalize the Kirchhoff-Sobolev parametrix of Klainerman and Rodnianski (Hyperbolic Equ. 4(3):401–433,
2007) to systems of tensor wave equations with additional first-order terms. We also present a different derivation, which better
highlights that such representation formulas are supported entirely on past null cones. This generalization of (Hyperbolic
Equ. 4(3):401–433, 2007) is a key component for extending Klainerman and Rodnianski’s breakdown criterion result for Einstein-vacuum spacetimes in
(J. Amer. Math. Soc. 23(2):345–382, 2009) to Einstein-Maxwell and Einstein-Yang-Mills spacetimes. 相似文献
16.
Henryk Malak Ignacy Gryczynski Joseph R. Lakowicz Gerald J. Meyers Felix N. Castellano 《Journal of fluorescence》1997,7(2):107-112
We examined the intensity and anisotropy decays of DNA labeled with two ruthenium metalligand complexes, [Ru(bpy)2(dppz)]2+ and [Ru(phe)2(dppz)]2+. Both complexes display high emission anisotropies in the absence of rotational diffusion, making them suitable probes for
rotational motions. When bound to DNA, these complexes display decay times as long as 294 ns, providing long-lived probes
of DNA dynamics. The decay times of both complexes were rather insensitive to dissolved oxygen. We examined anisotropy decays
of these complexes bound to B-form DNA. The anisotropy decays revealed correlation times near 10, 50, and several hundred
nanoseconds, suggesting that these probes are sensitive to a wide range of DNA motions. The use of metalligand complexes should
allow resolution of both the torsional and bending motions of DNA, the latter of which has been mostly inaccessible using
shorter-lived fluorescent probes bound to DNA.
Dedicated to Professor Robert F. Steiner upon his retirement 相似文献
17.
1-(4-Aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties
of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy,
circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes
bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal
complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant
activity and be better than standard antioxidants like vitamin C and mannitol.
Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10-5 M, [DNA]=(0-1) ×10-5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(εa – εf) versus [DNA] for the titration of DNA with the complex. 相似文献
18.
Peter Nyman 《International Journal of Theoretical Physics》2010,49(1):1-9
In this paper we continue to study so-called “inverse Born’s rule problem”: to construct a representation of probabilistic
data of any origin by a complex probability amplitude which matches Born’s rule. The corresponding algorithm—quantum-like
representation algorithm (QLRA)—was recently proposed by A. Khrennikov (Found. Phys. 35(10):1655–1693, 2005; Physica E 29:226–236, 2005; Dokl. Akad. Nauk 404(1):33–36, 2005; J. Math. Phys. 46(6):062111–062124, 2005; Europhys. Lett. 69(5):678–684, 2005). Formally QLRA depends on the order of conditioning. For two observables (of any origin, e.g., physical or biological) a and b, b|a- and a|b conditional probabilities produce two representations, say in Hilbert spaces H
b|a
and H
a|b
. In this paper we prove that under “natural assumptions” (which hold, e.g., for quantum observables represented by operators
with nondegenerate spectra) these two representations are unitary equivalent. This result proves the consistency of QLRA. 相似文献
19.
Applying the well-known Feynman-Kac formula of inhomogeneous case, an interesting and rigorous mathematical proof of generalized
Jarzynski’s equality of inhomogeneous multidimensional diffusion processes is presented, followed by an extension of the second
law of thermodynamics. Then, we explain its physical meaning and applications, extending Hummer and Szabo’s work (Proc. Natl.
Acad. Sci. USA 98(7):3658–3661, [2001]) and Hatano-Sasa equality of steady state thermodynamics (Phys. Rev. Lett. 86:3463–3466, [2001]) to the general multidimensional case. 相似文献
20.
In this paper, we study the macroscopic limit of a new model of collective displacement. The model, called PTWA, is a combination
of the Vicsek alignment model (Vicsek et al. in Phys. Rev. Lett. 75(6):1226–1229, 1995) and the Persistent Turning Walker (PTW) model of motion by curvature control (Degond and Motsch in J. Stat. Phys. 131(6):989–1021,
2008; Gautrais et al. in J. Math. Biol. 58(3):429–445, 2009). The PTW model was designed to fit measured trajectories of individual fish (Gautrais et al. in J. Math. Biol. 58(3):429–445,
2009). The PTWA model (Persistent Turning Walker with Alignment) describes the displacements of agents which modify their curvature
in order to align with their neighbors. The derivation of its macroscopic limit uses the non-classical notion of generalized
collisional invariant introduced in (Degond and Motsch in Math. Models Methods Appl. Sci. 18(1):1193–1215, 2008). The macroscopic limit of the PTWA model involves two physical quantities, the density and the mean velocity of individuals.
It is a system of hyperbolic type but is non-conservative due to a geometric constraint on the velocity. This system has the
same form as the macroscopic limit of the Vicsek model (Degond and Motsch in Math. Models Methods Appl. Sci. 18(1):1193–1215,
2008) (the ‘Vicsek hydrodynamics’) but for the expression of the model coefficients. The numerical computations show that the
numerical values of the coefficients are very close. The ‘Vicsek Hydrodynamic model’ appears in this way as a more generic
macroscopic model of swarming behavior as originally anticipated. 相似文献