Proton sponge-functionalized silica as high performance adsorbents for solid-phase extraction of trace perfluoroalkyl sulfonates in the environmental water samples and their direct analysis by MALDI-TOF-MS

1,8-Bis(dimethylamino)naphthalene (DMAN), a classical 'proton sponge', was functionalized on silica particles as a novel solid-phase extraction (SPE) adsorbent (DMAN@silica) for extracting perfluoroalkyl sulfonates (PFSs). High reproducibility and excellent extraction capability for PFSs were obtained in a wide pH range (3.0~8.5). The adsorbed PFSs on DMAN@silica sorbents could be efficiently eluted by 1,8-bis(tetramethylguanidino)naphthalene (TMGN) solution which is a proton sponge with higher proton affinity than DMAN. The elution could be directly analyzed by MALDI-TOF-MS using TMGN as matrix. Clear mass spectra for the PFSs were obtained due to no matrix ions interference observed. Furthermore, a novel strategy based on the DMAN@silica-SPE enrichment, followed by MALDI-TOF-MS analysis, was proposed and applied for PFSs quantification in environmental water samples. The calibration curves of each of the target analytes showed a wide linear dynamic range of response (0.1-10 ng L(-1) for perfluorooctane sulfonate (PFOS), perfluorohexyl sulfonate (PFHxS) and perfluorobutylsulfonate (PFBS)), which were over 2 orders of magnitude. The detection limits for PFOS, PFHxS, and PFBS were 0.021, 0.016, and 0.013 ng L(-1), respectively (S/N = 3). Recoveries of PFOS, PFHxS, and PFBS are in the ranges of 92-104%, 95-102%, and 98-109% for spiked river water samples. These results indicated that the prepared DMAN@silica adsorbents could efficiently enrich PFSs and that the proposed method is reliable.     

Conical Diffraction from Approximate Dirac Cone States in a Superhoneycomb Lattice

Superhoneycomb lattice is an edge‐centered honeycomb lattice that represents a hybrid fermionic and bosonic system. It contains pseudospin‐1/2 and pseudospin‐1 Dirac cones, as well as a flat band in its band structure. In this paper, we cut the superhoneycomb lattice along short‐bearded boundaries and obtain the corresponding band structure. The states very close to the Dirac points represent approximate Dirac cone states that can be used to observe conical diffraction during light propagation in the lattice. In comparison with the previous literature, this research is carried out using the continuous model, which brings new results and is simple, direct, accurate, and computationally efficient.     

Temporally Correlated Narrowband Biphoton Interference Based on Mach–Zehnder Interferometer

Since early 1990s, Mach–Zehnder interferometer has been used to investigate the interference of biphoton wave packets. Due to subpicosecond time coherence of biphoton generated by spontaneous parametric downconversion process, some physical processes are ignored in the interferometer, most likely the biphoton time‐domain interference. Here, the two‐photon interference phenomenon based on the Mach–Zehnder interferometer is theoretically studied, where the correlated photon pairs are produced by the four‐wave mixing in atomic system. In particular, the quantum interference effect to effectively control the coherent time of two‐photon by adjusting the input delay is used. In the damped Rabi oscillation regime, two‐photon bunching and antibunching effects are observed. In addition, in the group‐delay regime, the interference between biphoton precursor, slow‐light wave packets and also in between the precursor and the slow‐light wave packets is observed, which had never been reported before. These results may have potential applications in the fields of biphoton shaping and quantum information processing.     

干摩擦条件下基体粗糙度对Cr-DLC薄膜摩擦磨损性能的影响

采用磁控溅射/等离子辅助气相沉积方法在不同粗糙度样品表面制备Cr掺杂类金刚石(Cr-DLC)薄膜,研究了干摩擦条件下,基体粗糙度对Cr掺杂类金刚石薄膜摩擦磨损性能的影响.结果表明:在低表面粗糙度样品上体现了Cr掺杂类金刚石薄膜良好的自润滑特性,平均摩擦系数在0.1以下,达到了油润滑条件的摩擦水平,磨损较小,磨损表面薄膜结构完整,未出现明显石墨化转变.在高表面粗糙度样品上,样品的平均摩擦系数提高了3~4倍,磨损剧烈,基体表面磨出了明显的沟槽,与其对摩的Si_3N_4球磨损严重.     

Large-Scale Shell Model for Nuclear Structure and Nuclear Astrophysics Studies

The study of neutron-rich nuclei near 132Sn is interesting and important for both nuclear  structure and nuclear astrophysics. For a considerably large model space allowing cross-shell excitations, a new effective Hamiltonian is determined by employing the extended pairing-plus-quadrupole model with monopole corrections. Calculations for two mass regions, for the north-east quadrant of 132Sn with Z > 50 and N > 82 and for the south-west quadrant with Z < 50 and N < 82, have been performed recently. The structure of these nuclei is analyzed in detail, and the role of the monopole corrections canbe clearly seen.     

Dynamic response and damage analysis of fiber-reinforced composite laminated plates under low-velocity oblique impact

Fiber-reinforced composite laminates (FRCL) is susceptible to the external impacting. Understanding the crack propagation and structural mechanical properties of the damaged FRCL under low-velocity oblique impact is of great value in practical application. A new analytical dynamic model is developed in this work to research the dynamic response and damage property of FRCL under oblique impacting. The displacement field and strain–displacement relations of the FRCL are established by utilizing higher-order shear plate theory. The matrix damage and fiber rupture in FRCL under oblique impacting are captured by an internal variable-based continuum damage constitutive relation. To accurately predict the oblique impacting force, an analytical dynamic impacting model is proposed basing on a developed contact model, where normal and tangential contact is coupled and solved simultaneously. The whole initial boundary value problem is iteratively solved by synthetically using finite differential method and Newmark-\(\beta \) method. The solving convergence and accuracy of the model is demonstrated and validated. Simulations show that the matrix damage is more easily to appear in FRCL under shear force due to oblique contact when under oblique impacting, and the damage profile is different from normal impacting. The dynamic responses of the FRCL plate under oblique impacting differ also greatly from normal impacting. The current research provides a theoretical basis for FRCL design and its engineering application when under low-velocity impacting.     

Unveiling the Link Between Fractional Schrödinger Equation and Light Propagation in Honeycomb Lattice

We suggest a real physical system — the honeycomb lattice — as a possible realization of the fractional Schrödinger equation (FSE) system, through utilization of the Dirac‐Weyl equation (DWE). The fractional Laplacian in FSE causes modulation of the dispersion relation of the system, which becomes linear in the limiting case. In the honeycomb lattice, the dispersion relation is already linear around the Dirac point, suggesting a possible connection with the FSE, since both models can be reduced to the one described by the DWE. Thus, we propagate Gaussian beams in three ways: according to FSE, honeycomb lattice around the Dirac point, and DWE, to discover universal behavior — the conical diffraction. However, if an additional potential is brought into the system, the similarity in behavior is broken, because the added potential serves as a perturbation that breaks the translational periodicity of honeycomb lattice and destroys Dirac cones in the dispersion relation.     

Effect of disperse dye structure on dye sorption onto PLA fiber

The effect of the structure of various disperse dyes on their percentage sorption onto polylactide (PLA) is explained using molecular modeling. The interaction energies between the dyes and PLA have been calculated, and a linear equation has been developed to predict the percentage sorption on PLA based on the dye-PLA interaction energy. The predicted percentage sorption for a dye is shown to agree with its experimentally obtained percentage sorption on commercial PLA fabric and on PLA fiber extruded in our laboratory. Within the dyes, the functional groups that form the strongest interactions with PLA are -N(C(2)H(4)OCOCH(3))(2), -(CO)(2)NC(3)H(6)OCH(3), -SO(2)NHC(6)H(5), -NO(2), -CN(NH)C(6)H(4), and -CH(CO)(2)C(6)H(4), and the groups that form the weakest interactions with PLA are -Br and -Cl.     

Simultaneous determination and pharmacokinetic study of oxymatrine and matrine in beagle dog plasma after oral administration of Kushen formula granule, oxymatrine and matrine by LC-MS/MS

A rapid, specific and sensitive LC-MS/MS method was developed for the determination of oxymatrine (OMT) and matrine (MT) in beagle dog plasma. The method was applied to study the pharmacokinetics of OMT and MT after oral administration of OMT, MT and Kushen formula granule (KFG) containing equivalent amounts of OMT and MT in a three-period crossover design. The analysis was carried out on an Acquity UPLC BEH C(18) column by linear gradient elution with 0.01% acetic acid-water-methanol as mobile phase. Detection was by positive ion electrospray ionization (ESI) mass spectrometry with multiple-reaction monitoring (MRM). Linear calibration curves were both obtained over the concentration range 15-2000 ng/mL, with a limit of quantification of 15 ng/mL. The matrix effect was minimized. The intra- and inter-day precisions (RSDs) were less than 12.4 and 14.7%, respectively, and the accuracy (RE) was from -2.1 to 2.7%. The validated method was used to determine the concentration-time profiles of OMT and MT. The results indicated that the absorption of OMT and MT after oral administration of KFG was significantly greater than that after oral administration of pure components.     

THE ANALYSIS OF INTERLAMINAR STRESSES FOR COMPOSITE LAMINATED SHALLOW SHELLS WITH INTERFACIAL DAMAGE

Based on the general six-degrees-of-freedom plate theory towards the accurate stress analysis and nonlinear theory of shallow shells, considering the damage effect of the interlaminar interface and using the variation principle, the three-dimensional non-linear equilibrium differential equations of the laminated shallow shells with interfacial damage are derived. Then, considering a simply supported laminated shallow shell with damage and under normal load, an analytical solution is presented by using finite difference method to obtain the interlaminar stresses. Numerical results show, the stiffness of the shell is weakened, greater absolute values of displacements as well as smaller interlaminar stresses are obtained by interfacial damage. When the interfacial damage is further increased, delamination occurs obviously under normal pulling load and pure shear slip occurs under normal pressure load. The portion of the load undertaken by the two sides of the interface is more different. Different mechanical behaviors are shown in both sides of the interface, and the discontinuation of stresses and displacements takes place in the interface.