Design and Synthesis of a New Terbium Complex-Based Luminescent Probe for Time-Resolved Luminescence Sensing of Zinc Ions

Luminescent probes/chemosensors based on lanthanide complexes have shown great potentials in various bioassays due to their unique long-lived luminescence property for eliminating short-lived autofluorescence with time-resolved detection mode. In this work, we designed and synthesized a new dual-chelating ligand {4′-[N,N-bis(2-picolyl)amino]methylene-2,2′:6′,2′-terpyridine-6,6′-diyl} bis(methylenenitrilo) tetrakis(acetic acid) (BPTTA), and investigated the performance of its Tb³⁺ complex (BPTTA-Tb³⁺) for the time-resolved luminescence sensing of Zn²⁺ ions in aqueous media. Weakly luminescent BPTTA-Tb³⁺ can rapidly react with Zn²⁺ ions to display remarkable luminescence enhancement with high sensitivity and selectivity, and such luminescence response can be realized repeatedly. Laudably, the dose-dependent luminescence enhancement shows a good linear response to the concentration of Zn²⁺ ions with a detection limit of 4.1 nM. To examine the utility of the new probe for detecting intracellular Zn²⁺ ions, the performance of BPTTA-Tb³⁺ in the time-resolved luminescence imaging of Zn²⁺ ions in living HeLa cells was investigated. The results demonstrated the applicability of BPTTA-Tb³⁺ as a probe for the time-resolved luminescence sensing of intracellular Zn²⁺ ions.     

Symmetrically glass-clad photonic crystal nanocavities with ultrahigh quality factors

We design and fabricate ultra-high-quality (Q) photonic nanocavities in a symmetrically glass-clad silicon (Si) two-dimensional (2D) photonic crystal (PhC) structure. We theoretically investigate the dependence of the refractive index of the glass on the Q factors for asymmetric and symmetric structures. We show that the index-symmetric distribution of the glass is a critical factor to realize ultrahigh Q factors for glass-clad 2D PhC structures. We fabricate symmetrically glass-clad Si PhC nanocavities and achieve a record Q factor of 1×10(6), comparable with the highest Q factors of nanocavities in air-bridge structures.     

A diffuse-interface method for two-phase flows with soluble surfactants

A method is presented to solve two-phase problems involving soluble surfactants. The incompressible Navier-Stokes equations are solved along with equations for the bulk and interfacial surfactant concentrations. A non-linear equation of state is used to relate the surface tension to the interfacial surfactant concentration. The method is based on the use of a diffuse interface, which allows a simple implementation using standard finite difference or finite element techniques. Here, finite difference methods on a block-structured adaptive grid are used, and the resulting equations are solved using a non-linear multigrid method. Results are presented for a drop in shear flow in both 2D and 3D, and the effect of solubility is discussed.     

Geometric conservation law and applications to high-order finite difference schemes with stationary grids

The geometric conservation law (GCL) includes the volume conservation law (VCL) and the surface conservation law (SCL). Though the VCL is widely discussed for time-depending grids, in the cases of stationary grids the SCL also works as a very important role for high-order accurate numerical simulations. The SCL is usually not satisfied on discretized grid meshes because of discretization errors, and the violation of the SCL can lead to numerical instabilities especially when high-order schemes are applied. In order to fulfill the SCL in high-order finite difference schemes, a conservative metric method (CMM) is presented. This method is achieved by computing grid metric derivatives through a conservative form with the same scheme applied for fluxes. The CMM is proven to be a sufficient condition for the SCL, and can ensure the SCL for interior schemes as well as boundary and near boundary schemes. Though the first-level difference operators δ₃ have no effects on the SCL, no extra errors can be introduced as δ₃ = δ₂. The generally used high-order finite difference schemes are categorized as central schemes (CS) and upwind schemes (UPW) based on the difference operator δ₁ which are used to solve the governing equations. The CMM can be applied to CS and is difficult to be satisfied by UPW. Thus, it is critical to select the difference operator δ₁ to reduce the SCL-related errors. Numerical tests based on WCNS-E-5 show that the SCL plays a very important role in ensuring free-stream conservation, suppressing numerical oscillations, and enhancing the robustness of the high-order scheme in complex grids.     

Experimental and DFT investigation of surface degradation of polyvinylidene fluoride membrane in alkaline solution

The degradation processes of polyvinylidene fluoride (PVDF) membranes in alkaline solutions were studied using FTIR, FT-Raman, XPS and density functional theory (DFT) simulations. The activation energies for the degradation paths were calculated by LST/QST search methods. The corresponding Gibbs free energies were calculated using a continuum solvation model. The analysis of the spectra indicates the presence of C=C bonds, hydroxyl and carbonyl groups on PVDF membranes. It can be inferred, from DFT calculations, that defluorination is the energetically favorable path, followed by the formation of C=C bonds. The subsequent hydroxylation and carbonyl formation experience higher activation barriers than the formation of C=C bonds. The results indicate that the theoretical calculations are in accordance with the experimental data.     

Hypertriton and light nuclei production at Λ-production subthreshold energy in heavy-ion collisions

High-energy heavy-ion collisions produce abundant hyperons and nucleons. A dynamical coalescence model coupled with the ART model is employed to study the production probabilities of light clusters, deuteron (d), triton (t), helion (³He), and hypertriton (_Λ³H) at subthreshold energy of Λ production (≈ 1 GeV per nucleon). We study the dependence on the reaction system size of the coalescence penalty factor per additional nucleon and entropy per nucleon. The Strangeness Population Factor (S₃ / (³He × (Λ/p))) shows an extra suppression of hypertriton comparing to light clusters of the same mass number. This model predicts a hypertriton production cross-section of a few μb in ³⁶Ar+³⁶Ar, ⁴⁰Ca+⁴⁰Ca and ⁵⁶Ni+⁵⁶Ni in 1 A GeV reactions. The production rate is as high as a few hypertritons per million collisions, which shows that the fixed-target heavy-ion collisions at CSR (Lanzhou/China) at Λ subthreshold energy are suitable for breaking new ground in hypernuclear physics.     

星载激光测距合作目标的光学设计

运行于空间轨道的角反射器由于受相对速度的影响,必须进行速差补偿。针对轨道高度为20000km的角反射器,确定了能够接受的直角面平面度;针对几何光学方法速差补偿的不准确,运用衍射原理,对速差补偿的效果按角差的不同进行搜索,得到了比较理想的结果,确定了角反射器的参数。     

Dependence of the interband transition and the activation energy on the ZnTe spacer thickness in CdTe/ZnTe double quantum dots

Photoluminescence (PL) measurements were carried out to investigate the interband transition and the activation energy in CdTe/ZnTe double quantum dots (QDs). While the excitonic peaks corresponding to the interband transition from the ground electronic subband to the ground heavy-hole (E₁-HH₁) in the CdTe/ZnTe double QDs shifted to higher energy with decreasing ZnTe spacer thickness from 30 to 10 nm due to transformation from CdTe QDs to Cd_xZn_1−xTe QDs, the peaks of the (E₁-HH₁) transitions shifted to lower energy with decreasing spacer thickness from 10 to 3 nm due to the tunneling effects of the electrons between CdTe double QDs. The decrease in the activation energy with decreasing ZnTe spacer thickness might originate from an increase in the number of defects in the ZnTe spacer. The present results can help improve the understanding of the interband transition and the activation energy in CdTe/ZnTe double QDs.     

Design and application of phase photon sieve

The imaging principle of Fresnel zone plate and photon sieve were analyzed in this paper. The design and fabrication of phase photon sieve were discussed. The feasibility of using phase photon sieve to realize nano-lithography was analyzed, a novel lithography experiment system based on phase photon sieve was presented, which not only has higher resolution and image contrast than the Fresnel zone plate lithography but also have higher diffractive efficiency than the amplitude photon sieve lithography.     

Bose-Einstein Condensation in Linear Sigma Model at Hartree Approximation

The BEG of charged pions is investigated in the framework of O（4） linear sigma model. By using Cornwall- Jackiw-Tomboufis formalism, we have derived the gap equations for the effective masses of the mesons at finite temperature and finite isospin density. The critical temperature and phase diagram of BEG are discussed in the non-chiral limit at Hartree approximation.