The normalized second-order
correlation of the emission fields from a driven four-level atomic
ensemble is investigated theoretically by using the state vector
method. The violation of Cauchy-Schwarz inequality, which indicates
the establishment of non-classical correlation between two emission
fields, has been found. The effects of various decays and time delay
on the correlation are discussed in detail, which are helpful in
finding the ways to obtain high non-classical correlation. This
technique for the generation of non-classical light is operable
based on the current experimental technology and will lead to some
potential applications in quantum information science. 相似文献
We study the transverse momentum dependence of the anisotropic flow v2 for π, K, nucleon, Λ, Ξ and Ω for Au+Au collisions at within two independent string-hadron transport approaches (RQMD and UrQMD). Although both models reach only 60% of the absolute
magnitude of the measured v2, they both predict the particle-type dependence of v2 as observed by the RHIC experiments: v2 exhibits a hadron-mass hierarchy in the low pT region and a number-of-constituent-quark (NCQ) dependence in the intermediate pT region. The failure of the hadronic models to reproduce the absolute magnitude of the observed v2 indicates that transport calculations of heavy-ion collisions at RHIC must incorporate interactions among quarks and gluons
in the early, hot and dense phase. The presence of an NCQ scaling in the string-hadron model results suggests that the particle-type
dependences observed in heavy-ion collisions at intermediate pT might be related to the hadronic cross sections in vacuum rather than to the hadronization process itself. 相似文献
We study theoretically the properties of a thin film of a semiconductor embedded in the interface of two kinds of single-negative materials. At some frequencies the structure with suitable size is equivalent to an effective (near) zero-index medium. The coupling of exciton resonance in the semiconductor and the interface mode in a zero-index medium leads to Rabi splitting. Compared with Rabi splitting observed in cavities, the splitting modes in zero-index media are robust against the scaling change of the length and direction of incident wave. 相似文献
We report on the dynamics of photodegradation and subsequent recovery of two-photon fluorescence in a dye-doped polymer. The energy dependence suggests that photodegradation is a linear process, while recovery is entropic. Such recovery could be useful to high-intensity devices such as two-photon absorbers, which can be used in many applications. 相似文献
The phenomenon of stochastic resonance in a bistable system with time-delayed feedback driven by non-Gaussian noise is investigated. Combining the small time delay approximation, the path-integral approach and the unified colored noise approximation, a general approximate Fokker–Planck equation of a stochastic system is obtained. The effects of the parameter q indicating the departure from the Gaussian noise, the delay time τ , and the correlation time τ0 of the non-Gaussian noise on the quasi-steady-state probability distribution function (SPD) and the signal-to-noise ratio (SNR) are discussed. It is found that the number of peaks in SPD and the reentrant transition between one peak and two peaks and then to one peak again in the curve of SNR depends on the parameter q, the delay time τ , and the noise correlation time τ0. 相似文献
The accurate dissociation energy and harmonic frequency for the highly excited 2^1Пu state of dimer ^7Li2 have been calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space. The calculated results are in excellent agreement with experimental measurements. The potential energy curves at numerous basis sets for this state are obtained over a wide internuclear separation range from about 2.4a0 to 37.0a0. And the conclusion is gained that the basis set 6-311++G(d,p) is a most suitable one. The calculated spectroscopic constants De, Re, ωe, ωeχe, ae and Be at 6-311++G(d,p) are 0.9670 eV, 0.3125 nm, 238.6 cm^-1, 1.3705 cm^-1, 0.0039 cm^-1 and 0.4921 cm^-1, respectively. The vibrational levels are calculated by solving the radial SchrSdinger equation of nuclear motion. A total of 53 vibrational levels are found and reported for the first time. The classical turning points have been computed. Comparing with the measurements, in which only the first nine vibrational levels have been obtained so far, the present calculations are very encouraging. A careful comparison of the present results of the parameters De and We with those obtained from previous theories clearly shows that the present calculations are much closer to the measurements than previous theoretical results, thus representing an improvement on the accuracy of the ab initio calculations of the potentials for this state. 相似文献
A new carbazole functionalized Schiff base CBM was synthesized and characterized. CBM can selectively recognize Cu2+ via UV–vis and fluorescence signal among common biologically relevant metal ions. When Cu2+ was added to CBM, there was a significant enhancement at the maximum absorption wavelength of 393 nm and with a distinct blue shift. The maximum emission peak was significantly attenuated by a factor of about 15 times at 535 nm and the blue shift of emission wavelength was observed. When other metal ions were added, there was no remarkable change at the maximum absorption and emission peak. Under the illumination of 365 nm ultraviolet lamp, the color of the CBM solution changed from light blue to dark blue after the addition of Cu2+. The combination mechanism of CBM with Cu2+ was nicely explored by density functional theory studies. The probe CBM has good cell permeability, fluorescence electron microscopy experiments show that CBM can be used as a fluorescent probe to detect the presence or absence of Cu2+ in Hela cells. Furthermore, the probe CBM can also be used for the detection of copper ions in actual water samples. 相似文献
Indoleamine 2,3-dioxygenase (IDO), an immune checkpoint protein, can cause the depletion of tryptophan (Trp) and accumulation of its metabolite of kynurenine (Kyn) in cancer cells, and generates the immunosuppressive microenvironment that supports tumor cell growth. A novel immunoregulatory prodrug micelle based on polyethylene glycol-derivatized an IDO-selective inhibitor of 1-methyltryptophan (1-MT), PEG-Fmoc-1-MT, was developed for inhibiting the IDO activity of the conversion of Trp to Kyn in tumor microenvironments. To investigate the 1-MT distribution and Trp/Kyn ratios in mice tumors with PEG-Fmoc-1-MT prodrug micelles treatment, a HPLC–MS/MS method for simultaneous determination of 1-MT and IDO biomakers of Trp and Kyn in mouse tumors was developed and validated. Triple-quadrupole mass spectrometry with positive electrospray ionization as source ionization in multiple reaction monitoring at m/z 219.0?→?160.1, 205.0?→?118.2, 209.0?→?146.1 and 249.3?→?148.3 was used for determination of 1-MT, Trp, Kyn and matrine (internal standard). The method demonstrated good linearity at the concentrations ranging from 10 to 10,000 ng/mL and lower limits of quantitation of 1 ng/mL for 1-MT, Trp and Kyn, respectively. The validated method was successfully applied to 1-MT tumor biodistribution and Trp/Kyn ratio studies in 4T1 tumor bearing mice i.v. with PEG-Fmoc-1-MT prodrug micelles. The mice tumors with PEG-Fmoc-1-MT prodrug micelles treatment exhibited higher 1-MT accumulation and lower Trp/Kyn ratio, in comparison with those of mice with 1-MT solution treatment. The developed PEG-Fmoc-1-MT prodrug micelles could be a promising IDO immunoregulatory prodrug micelles for cancer immunotherapy.
The ketene silyl acetal derived from ethyl 2-benzyltetrahydroisoquinoline-1-carboxylate undergoes a rapid oxidation reaction with N-bromosuccinimide to form 3,4-dihydroisoquinolinium ion, which reacts with Grignard reagents to give 1,1-disubstituted tetrahydroisoquinolines in good yields. 相似文献