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1.
Ashot S. Gevorkyan 《Foundations of Physics》2011,41(3):509-515
Spontaneous transitions between bound states of an atomic system, “Lamb Shift” of energy levels and many other phenomena in
real nonrelativistic quantum systems are connected within the influence of the quantum vacuum fluctuations (fundamental environment (FE)) which are impossible to consider in the limits of standard quantum-mechanical approaches. The joint system “quantum
system (QS) + FE” is described in the framework of the stochastic differential equation (SDE) of Langevin-Schr?dinger (L-Sch)
type, and is defined on the extended space R
3
⊗
R
{ξ}, where R
3 and R
{ξ} are the Euclidean and functional spaces, respectively. The density matrix for single QS in FE is defined. The entropy of
QS entangled with FE is defined and investigated in detail. It is proved that as a result of interaction of QS with environment
there arise structures of various topologies which are a new quantum property of the system. 相似文献
2.
Shaolin Liao Ronald J. Vernon 《International Journal of Infrared and Millimeter Waves》2007,28(6):479-490
The newly developed Taylor-Interpolation-FFT (TI-FFT) algorithm dramatically increases the computational speeds for millimeter
wave propagation from a planar (cylindrical) surface onto a “quasi-planar” (“quasi-cylindrical”) surface. Two different scenarios
are considered in this article: the planar TI-FFT is for the computation of the wave propagation from a plane onto a “quasi-planar” surface and the cylindrical TI-FFT is for the computation of wave propagation from a cylindrical surface onto a “quasi-cylindrical” surface. Due to the
use of the FFT, the TI-FFT algorithm has a computational complexity of O(N
2 log2
N
2) for an N × N computational grid, instead of N
4 for the direct integration method. The TI-FFT algorithm has a low sampling rate according to the Nyquist sampling theorem.
The algorithm has accuracy down to −80 dB and it works particularly well for narrow-band fields and “quasi-planar” (“quasi-cylindrical”)
surfaces. 相似文献
3.
A new anthracene-based fluorescent PET sensor 1 with a tridentate ionophore of amide/β-amino alcohol displays very good selectivity and sensitivity for Fe3+ (K
a = 1.6 × 103 M−1) and Hg2+ (K
a = 2.1 × 103 M−1) in CH3CN–H2O (3:7, v/v) with detection limit of 1 μM. More fluorescence enhancement was observed when 1 selectively detected Fe3+ or Hg2+ in CH3CN and its detection limit was up to 0.03 μM. 相似文献
4.
A Novel Hg<Superscript>2+</Superscript> Selective Ratiometric Fluorescent Chemodosimeter Based on an Intramolecular FRET Mechanism 总被引:1,自引:0,他引:1
A irreversible Hg2+ selective ratiometric fluorescence probe FR, a fluorescein fluorophore linked to a rhodamine B hydrazide by a thiourea spacer, was designed and synthesized. The developed
probe FR exhibited great ratiometric fluorescence enhancement and remarkable yellow-magenta color change toward Hg2+ with excellent selectivity in aqueous acetone solution, and the ratiometric fluorescence response to Hg2+ was not interfered by other metal cations including Fe3+, Co2+, Ni2+, Cr3+, Zn2+, Pb2+, Cd2+, Ca2+, Mg2+, Ba2+ and Mn2+. The linear range and the detection limit of this supposed ratiometric fluorescence method for Hg2+ were 0.0–10.0 × 10−6 and 5 × 10−8 M, respectively. 相似文献
5.
Condensation product (L) of salicylaldehyde and semicarbazide behaves as a fluorescent sensor for Cd2+ ion, in 1:1 DMSO:H2O, over Mn2+, Fe2+, Ni2+, Co2+, Cu2+, Pb2+ and Hg2+ ions. The emission peak of L at λmax = 520 nm, on excitation with 420 nm wavelength photons, showed an enhancement in intensity of ca 60-fold when interacted with Cd2+ ion. The intensity was however found to remain unaltered when interacted with metal ions—Mn2+, Fe2+, Ni2+, Co2+, Cu2+, Pb2+ and Hg2+. The intensity increases by approximately 20 fold on interaction with Zn2+ ion. The increase in the fluorescent peak can be explained on the basis of photo induced electron transfer (PET) mechanism.
A 1:1 complexation between Cd2+ and L with log β = 4.25 has been proved. 相似文献
6.
Two indole-based fluorescent chemosensors 1 and 2 were prepared and investigated characteristic features with transition metal ions. Sensors 1 and 2 were selective for Hg2+ ion, among a series of metal ions, in aqueous ethanol (H2O–EtOH, 1:2, v/v) with association constants of 5.74 × 103 and 4.46 × 103 M−1 and detection limits of 7.4 and 6.8 μM, respectively. Computational results revealed that sensor 1 or 2 with Hg2+ ion formed 1:1 complex with a central, sandwich-coordinated Hg2+ ion. Computational calculations provided evidence that a sandwich-coordinated Hg2+ ion center was formed and the polyoxyethylene spacer acted as a scaffold for bringing functional ligands into a suitable
geometry. 相似文献
7.
Two highly photostable yellow–green emitting 1,8-naphthalimides 5 and 6, containing both N-linked hindered amine moiety and a secondary or tertiary cation receptor, were synthesized for the first time. Novel compounds
were configured as “fluorophore–spacer–receptor” systems based on photoinduced electron transfer. Photophysical characteristics
of the dyes were investigated in DMF and water/DMF (4:1, v/v) solution. The ability of the new compounds to detect cations was evaluated by the changes in their fluorescence intensity
in the presence of metal ions (Cu2+, Pb2+, Zn2+, Ni2+, Co2+) and protons. The presence of metal ions and protons was found to disallow a photoinduced electron transfer leading to an
enhancement in the dye fluorescence intensity. Compound 5, containing secondary amine receptor, displayed a good sensor activity towards metal ions and protons. However the sensor
activity of dye 6, containing a tertiary amine receptor and a shorter hydrocarbon spacer, was substantially higher. The results obtained indicate
the potential of the novel compounds as highly photostable and efficient “off–on” pH switchers and fluorescent detectors for
metal ions with pronounced selectivity towards Cu2+ ions. 相似文献
8.
We previously applied the electrochromic modulation of excited-state intramolecular proton-transfer (ESIPT) reaction for the
design of novel 3-hydroxyflavone (3-HF) derivatives as fluorescent probes for measuring the dipole potential, ΨD, in lipid bilayers (Klymchenko et al., Proc. Natl. Acad. Sci. USA, 2003, 100, 11219). In the present work, this method was revisited to take into account the influence of the bilayer hydration on the
emission ratiometric response of 3-HF probes. For this reason, it was necessary to deconvolute the whole fluorescence spectra
into three bands corresponding to the non H-bonded forms, normal N* and tautomer T* forms, both participating to the ESIPT reaction, and to the H-bonded H–N* form, excluded from this reaction. This allowed us to determine the pure N*/T* intensity ratio, without any contribution from the H–N* form emission depending essentially on the bilayer hydration. This new approach allowed us to confirm the correlation we
obtained between the response of 3-HF probes on dipole potential modifications and the corresponding response of the reference
fluorescent probe di-8-ANEPPS, thus further confirming the potency of 3-HF probes as excellent emission ratiometric probes
to measure dipole potential in lipid membranes. 相似文献
9.
A new fluorescent probe 3, has been developed for the detection of Fe(III) in water based samples. The design of 3 involved the incorporation of Fe(III) binding sites observed in naturally occurring Siderophores into a synthetic sensing
assembly. The probe, containing two Schiff base receptors connected to a mesitylene platform, was prepared in two steps. The
dipodal sensor displayed good selectivity for Fe(III) when tested against other physiological and environmentally important
metal ions, in HEPES buffered solution at pH 7.0, through a quenching of the fluorescent intensity. Stern-Volmer analysis
of this quenching interaction indicated a 1:1 (host : guest) binding stoichiometry between the probe and Fe(III). The association
constant, K
a
calculated using the Benesi-Hildebrand equation was found to be 3.8 × 104 M−1. Crucially, the sensor was capable of measuring Fe(III) competitively in solutions containing both Fe(III) and Cu(II). Thus,
the adoption of Fe(III) binding sites found in nature, into synthetic luminescent assemblies has proven an effective design
strategy for the development of new Fe(III) probes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
11.
G.S. Neugschwandtner R. Schwödiauer S. Bauer-Gogonea S. Bauer 《Applied Physics A: Materials Science & Processing》2000,70(1):1-4
Large piezoelectric d33 coefficients around 600 pC/N are found in corona-charged non-uniform electrets consisting of elastically “soft” (microporous
polytetrafluoroethylene PTFE) and “stiff” (perfluorinated cyclobutene PFCB) polymer layers. The piezoelectric activity of
the two-layer fluoropolymer stack exceeds the d33 coefficient of the ferroelectric ceramic lead zirconate titanate (PZT) by more than a factor of two and that of the ferroelectric
polymer polyvinylidene fluoride (PVDF) by a factor of 20. Soft piezoelectric materials may become interesting for a large
number of sensor and transducer applications, in areas such as security systems, medical diagnostics, and nondestructive testing.
Accepted: 9 November 1999 / Published online: 3 December 1999 相似文献
12.
Proteoliposomes carrying reconstituted yeast plasma membrane H+-ATPase in their lipid membrane or plasma membrane vesicles are model systems convenient for studying basic electrochemical
processes involved in formation of the proton electrochemical gradient (ΔμH
+) across the microbial or plant cell membrane. Δψ- and pH-sensitive fluorescent probes were used to monitor the gradients
formed between inner and outer volume of the reconstituted vesicles. The Δψ-sensitive fluorescent ratiometric probe oxonol
VI is suitable for quantitative measurements of inside-positive Δψ generated by the reconstituted H+-ATPase. Its Δψ response can be calibrated by the K+/valinomycin method and ratiometric mode of fluorescence measurements reduces undesirable artefacts. In situ pH-sensitive fluorescent probe pyranine was used for quantitative measurements of pH inside the proteoliposomes. Calibration
of pH-sensitive fluorescence response of pyranine entrapped inside proteoliposomes was performed with several ionophores combined
in order to deplete the gradients passively formed across the membrane. Presented model system offers a suitable tool for
simultaneous monitoring of both components of the proton electrochemical gradient, Δψ and ΔpH. This approach should help in
further understanding how their formation is interconnected on biomembranes and even how transport of other ions is combined
to it. 相似文献
13.
A novel artificial anion chemosensor 1 based on 2, 2′-di (4-nitrophenylurea-β-N-yl) -1, 1′-binaphthyl is designed and synthesized for sensing anions including halide ions and oxoanions. The fluorescent
emission of the binaphthyl of receptor 1, forming the hydrogen bonding with anions as the sensing mechanism, is monitored in DMSO for detecting anions. In brief,
while most of the anion chemosensors are switch-off fluorescent chemosensor, or non-fluorescent sensor, receptor 1 exhibits obviously the switch-on emission during the complexation with H2PO4−. 相似文献
14.
Hellmut Baumgärtel 《International Journal of Theoretical Physics》2011,50(7):2002-2008
To asymptotic complete scattering systems {M
++V,M
+} on H+:=L2(R+,K{\mathcal{H}}_{+}:=L^{2}(\mathbf{R}_{+},{\mathcal{K}}, d
λ), where M
+ is the multiplication operator on H+{\mathcal{H}}_{+} and V is a trace class operator with analyticity conditions, a decay semigroup is associated such that the spectrum of the generator
of this semigroup coincides with the set of all resonances (poles of the analytic continuation of the scattering matrix into
the lower half plane across the positive half line), i.e. the decay semigroup yields a “time-dependent” characterization of
the resonances. As a counterpart a “spectral characterization” is mentioned which is due to the “eigenvalue-like” properties
of resonances. 相似文献
15.
T. Schlathölter M.W. Newman T.R. Niedermayr G.A. Machicoane J.W. McDonald T. Schenkel R. Hoekstra A.V. Hamza 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):323-327
The emission of small (hydrogenated) carbon cluster ions CnHm
+
(n
=2-22) upon highly charged Xeq+ (q
=20-44) impact on C84 surfaces is studied by means of time-of-flight secondary ion mass spectrometry. The respective stage of hydrogenation/protonation
of a certain carbon cluster ion Cn
+
is a strong indication for its geometrical structure. From the cluster ion yield as a function of cluster size it can be
concluded, that the hydrogenation takes place after the initial carbon cluster formation. The carbon clusters seem to be emitted
as an entity in agreement with “equilibrium” and “shock wave” models.
Received 4 February 2000 相似文献
16.
Wen-Zhong Zhu Qiu-Yue Lin Mei Lu Rui-Ding Hu Xiao-Liang Zheng Jian-Ping Cheng Yun-Yun Wang 《Journal of fluorescence》2009,19(5):857-866
Three novel complexes [Nd(L)(NO3)(H2O)2]·NO3·2H2O (HL1 = N-pyrimidine norcantharidin acylamide acid, C12H13N3O4; HL2 = N-pyridine norcantharidin acylamide acid, C13H14N2O4; HL3 = N-phenyl norcantharidin acylamide acid, C14H15NO4) were synthesized. HL1, HL2 and HL3 are the ligand of complex(1), complex(2) and complex(3), respectively. Their structures were characterized by elemental analysis, conductivity measurement, infrared spectra and
thermogravimetric analysis. The DNA-binding properties of the complexes have been investigated by fluorescence spectroscopy
and viscosity measurements. The results suggest that the complexes can bind to DNA by partial intercalation. The liner Stern-Volmer
quenching constant Ksq values are 3.3(±0.21)(1), 1.7(±0.19)(2) and 0.9(±0.04)(3), respectively. Complex (1) and (2) have been found to cleave pBR322 plasmid DNA at physiological pH and temperature. The test of antiproliferation activity
indicates that complex(1) has strong antiproliferative ability against the SMMC7721 (IC50 = 131.7 ± 23.4 μmol·L−1) and A549 (IC50 = 128.4 ± 19.9 μmol·L−1) cell lines. The inhibition rates of complex(2) (IC50 = 86.3 ± 11.3 μmol·L−1) are much higher than that of NCTD (IC50 = 115.5 ± 9.5 μmol·L−1) and HL2 (111.0 ± 5.7 μmol·L−1) against SMMC7721 cell lines. 相似文献
17.
A simple colorimetric and ratiometric fluorescent anion sensor 1, was rationally designed and synthesized by facile one-step
condensation on basis of the mechanism of intramolecular charge transfer (ICT). The sensor 1 shows more highly and selectively
ability to F− that induced the color changes from little yellow to purple, absorption-transferred to long wavelength and emission-transferred
to short wavelength. Accordingly, 1H NMR analysis reveals that the F−-induced colorimetric and fluorometric responses of 1 are simply driven by hydrogen bonding interaction between the NH protons
and F− ions. 相似文献
18.
We analyse, within the “flavoured” leptogenesis scenario of baryon asymmetry generation, the interplay of “low energy” CP-violation,
originating from the PMNS neutrino mixing matrix U, and “high energy” CP-violation, which can be present in the matrix of neutrino Yukawa couplings, λ, and can manifest itself only in “high” energy scale processes. The type I see-saw model with three heavy right-handed Majorana
neutrinos having a hierarchical spectrum is considered. The “orthogonal” parameterisation of the matrix of neutrino Yukawa
couplings, which involves a complex orthogonal matrix R, is employed. In this approach the matrix R is the source of “high energy” CP-violation. Results for normal hierarchical (NH) and inverted hierarchical (IH) light neutrino
mass spectrum are derived in the case of decoupling of the heaviest right-handed Majorana neutrino. It is shown that taking
into account the contribution to Y
B
due to the CP-violating phases in the neutrino mixing matrix U can change drastically the predictions for Y
B
, obtained assuming that only “high energy” CP-violation from the R-matrix is operative in leptogenesis. In the case of the IH spectrum, in particular, there exist significant regions in the
corresponding parameter space where the purely “high energy” contribution in Y
B
plays a subdominant role in the production of baryon asymmetry compatible with the observations.
Also at Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria. 相似文献
19.
We study zero-temperature, stochastic Ising models σ
t
on Z
d
with (disordered) nearest-neighbor couplings independently chosen from a distribution μ on R and an initial spin configuration chosen uniformly at random. Given d, call μ type ℐ (resp., type ℱ) if, for every
x in Z
d
, σ
x
t
flips infinitely (resp., only finitely) many times as t→∞ (with probability one) – or else mixed type ℳ. Models of type ℒ and ℳ exhibit a zero-temperature version of “local non-equilibration”.
For d=1, all types occur and the type of any μ is easy to determine. The main result of this paper is a proof that for d=2, ±J models (where μ=αδ
J
+(1-α)δ-
J
) are type ℳ, unlike homogeneous models (type ℐ) or continuous (finite mean) μ's (type ℳ). We also prove that all other noncontinuous
disordered systems are type ℳ for any d≥ 2. The ±J proof is noteworthy in that it is much less “local” than the other (simpler) proof. Homogeneous and ±J models for d≥ 3 remain an open problem.
Received: 3 November 1999 / Accepted: 10 April 2000 相似文献
20.
J. H. Brewer D. R. Harshman R. Keitel S. R. Kreitzman G. M. Luke D. R. Noakes R. E. Turner E. J. Ansaldo 《Hyperfine Interactions》1986,32(1-4):677-682
Strongly hydrogen-bonded diamagnetic “FμF” centres are formed by theμ
+ in a wide variety of fluoride crystals. Hydrogen atoms are expected to form similar “FHF” complexes. Through the “motional narrowing” of the zero-field muon relaxation function in NaF, we have observed an Arrhenius
temperature dependence of the dissociation rate of theFμF complex, yielding a binding energy of 1700 (200) K for theμ
+ in theFμF centre. 相似文献