Spatiotemporal dynamics induced by nonlocal competition in a diffusive predator-prey system with habitat complexity

Nonlinear Dynamics - In this paper, we study a delayed diffusive predator–prey model with nonlocal competition in prey and habitat complexity. The local stability of coexisting equilibrium is...     

Measured and Predicted Solubility Phase Diagrams of Quaternary Systems LiBr-NaBr-MgBr2-H2O and LiBr-KBr-MgBr2-H2O at 298.15 K

The stable phase equilibria of quaternary systems LiBr-NaBr-MgBr₂-H₂O and LiBr-KBr-MgBr₂-H₂O at 298.15 K were studied by both experimental measurement(isothermal solution saturation method) and theoretical prediction(Pitzer model). The solubilities of the saturated solution have been determined experimentally and two stable phase diagrams and relevant water diagrams of the two quaternary systems were obtained. Results show that quaternary system LiBr-NaBr-MgBr₂-H₂O is hydrate II type as NaBr and NaBr·2H₂O coexistence. Its phase diagram consists of only one invariant point, four univariant curves, and five crystallization fields. The quaternary system LiBr-KBr-MgBr₂-H₂O is a complex type as the double salt KBr·MgBr₂·6H₂O formed. In addition to this double salt, the three single salts LiBr·2H₂O, KBr and MgBr₂·6H₂O also crystallize. In this paper, the solubilities of phase equilibria in above quaternary systems were also calculated by the Pitzer's electrolyte solution model. All the needed parameters can be obtained from the literature or be fitted by experimental data. On the Basis of the experimental and calculated results, the phase diagram of the quaternary system was plotted for comparison. It shows that the calculation results are consistent with the experimental ones.     

羧基亚胺配体的合成及其促进Suzuki偶联反应的研究

合成了4种羧基亚胺配体并将其用于促进Suzuki偶联反应。通过考察配体结构、溶剂极性、碱强度和温度等因素对反应产率的影响,确定了羧基亚胺配体参与的钯催化Suzuki偶联反应的最佳条件为:催化剂的量为0.001(mol)%的Pd Cl2和0.002(mol)%的配体,以碳酸钾作碱,4m L乙醇水溶液(1∶1,体积比)作溶剂,反应温度为60℃,在空气条件下反应。结果表明,羧基亚胺配体能够有效促进Suzuki偶联反应;在合成的配体L1~L4中,具有适当的位阻和给电子基团的L2的催化活性最高,能够高效催化合成一系列联芳类化合物。     

Closed and open-ended stacking fault tetrahedra formation along the interfaces of Cu–Al nanolayered metals

Stacking fault tetrahedra (SFTs) are volume defects that typically form by the clustering of vacancies in face-centred cubic (FCC) metals. Here, we report a dislocation-based mechanism of SFT formation initiated from the semi-coherent interfaces of Cu–Al nanoscale multilayered metals subjected to out-of-plane tension. Our molecular dynamics simulations show that Shockley partials are first emitted into the Cu interlayers from the dissociated misfit dislocations along the Cu–Al interface and interact to form SFTs above the triangular intrinsic stacking faults along the interface. Under further deformation, Shockley partials are also emitted into the Al interlayers and interact to form SFTs above the triangular FCC planes along the interface. The resulting dislocation structure comprises closed SFTs within the Cu interlayers which are tied across the Cu–Al interfaces to open-ended SFTs within the Al interlayers. This unique plastic deformation mechanism results in considerable strain hardening of the Cu–Al nanolayered metal, which achieves its highest tensile strength at a critical interlayer thickness of ~4 nm corresponding to the highest possible density of complete SFTs within the nanolayer structure.     

氟喹诺酮-3-N-酰胺类衍生物的合成与抗肿瘤活性

为扩展氟喹诺酮由抗菌活性向抗肿瘤活性转化的结构修饰策略,利用药效团生物电子等排及其拼合和骨架迁越药物化学分子构建方法,以酰胺基作为氟喹诺酮C-3位羧基的生物电子等排体,氟喹诺酮骨架为酰胺基的功能修饰基,设计合成了氟喹诺酮-3-N-酰胺类目标化合物。其结构经元素分析和光谱数据确证。体外抗肿瘤实验结果表明,目标化合物对Hep-3B细胞和Capan-1细胞的抗增殖活性均显著强于母体环丙沙星的活性,尤其对Hep-3B细胞的抑制活性最强。因此,用酰胺基来替代C-3羧基有利于提高氟喹诺酮的抗肿瘤活性。     

Improvement of electrochemical performance for Li-rich spherical Li1.3[Ni0.35Mn0.65]O2+x modified by Al2O3

The Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x microspheres are firstly prepared and subsequently transferred into the Al₂O₃-coated Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the Al₂O₃-coated Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x sample has a typical α-NaFeO₂ layered structure with the existence of Li₂MnO₃-type integrated component, and the Al₂O₃ layer is uniformly coated on the surface of the spherical Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x particles with a thickness of about 4 nm. Importantly, the Al₂O₃-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% Al₂O₃-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g^?1 at a rate of 0.1 C in the voltage of 2.0–4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% Al₂O₃-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% Al₂O₃-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g^?1 even at 10 C. Besides, the thin Al₂O₃ layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x .     

Density functional study of TaSin (n = 1-3, 12) clusters adsorbed to graphene surface

A plane-wave density functional theory (DFT) calculations have been performed to investigate structural and electronic properties of TaSi_n (n = 1-3, 12) clusters supported by graphene surface. The resulting adsorption structures are described and discussed in terms of stability, bonding, and electron transfer between the cluster and the graphene. The TaSi_n clusters on graphene surface favor their free-standing ground-state structures. Especially in the cases of the linear TaSi₂ and the planar TaSi₃, the graphene surface may catalyze the transition of the TaSi_n clusters from an isomer of lower dimensionality into the ground-state structure. The adsorption site and configuration of TaSi_n on graphene surface are dominated by the interaction between Ta atom and graphene. Ta atom prefers to adsorb on the hollow site of graphene, and Si atoms tend to locate on the bridge site. Further, the electron transfer is found to proceed from the cluster to the surface for n = 1 and 2, while its direction reverses as n > 2. For the case of TaSi, chemisorption is shown to prevail over physisorption as the dominant mode of surface-adsorbate interaction by charge density analysis.     

On Torsion—free Connections in Finsler Geometry

61.IntroductionI,etMbeasmoothnudimensionalmanifoldandTMdenoteitstangentt,undIe.AFinslerstructureonMisamapF:TM-[O, oo)whichhasthefollowingproperties:(a)FissmoothonTM\{o}.(b)F(x,ty)=ItlF(x,y).(jw,y)eTM\{O},tej{.(c)ThenXnmatr1x(ee(2',y))isposlt1vedefiniteforally/O.AFinslermanifoldisamanifoldwithaFinslerstructure.ItisquiteapparentthattheLevl-C1vitaconnectlonplaysanlmportantroleintheRieman-niangeon1etryofmanifolds.Thusnodoubt,itisnaturaltointreduceconnectionsinFinslergeometry.Manyconnec…     

A spontaneous combustion reaction for synthesizing Pt hollow capsules using colloidal carbon spheres as templates

Here we report a spontaneous combustion reaction in synthesizing Pt hollow capsules. In brief, Pt nanoparticles were loaded on the surface of colloidal carbon spheres by wet-chemical impregnation. When Pt-loaded carbon spheres were taken out of an argon-filled tube furnace at room temperature and exposed to air, they underwent spontaneous combustion. The internal carbon spheres templates were removed to leave nanostructured Pt hollow capsules. There are at least two critical conditions for the occurrence of the spontaneous combustion: the Pt particle size is below 5.8 nm, and the hydrogen content in the carbon spheres is above 2.570 wt %. Such a reaction is interesting for the preparation of metal hollow spheres and is also relevant with respect to removal of accumulated carbon on catalysts and for soot oxidation at room temperature.     

Synthesis of magnetic/luminescent alginate-templated composite microparticles with temperature-dependent photoluminescence under high-frequency magnetic field

Highly magnetic luminescent alginate-templated composite microparticles were successfully synthesized by a novel process combining emulsification and layer-by-layer self-assembly techniques. The composite microparticles were characterized by ζ-potential analyzer, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscope, fluorescence spectrophotometer, and vibrating sample magnetometer. Experimental observations indicated that the composite microparticles had excellent magnetic properties, and its photoluminescence could be precisely controlled by varying the number of deposition cycles of polyelectrolytes and CdTe/polyelectrolyte multilayers. Moreover, the composite microparticles could be heated up in a high-frequency magnetic field and demonstrated linear temperature-dependent photoluminescence over the range from room temperature to hyperthermia temperature. The composite microparticles are expected to be promising candidates for biomedical applications, such as immunoassay, biosensing and imaging, and cancer diagnosis and treatment.