Elastodynamic analysis of a thin layer bonded on a visco-elastic medium under combined in-plane and lateral pulse loads

An analytic solution of a thin layer bonded on a visco-elastic medium under the action of in-plane and lateral pulse loads is presented. The analysis is based on double integral transforms with respect to space and time. Representative examples are studied and discussed to determine the influence of the (a) damping and elastic coefficients of visco-elastic medium, and (b) in-plane compression and stretching of the thin layer on wave propagation.     

聚合物基片对柔性有机发光器件性能的影响

以聚合物基片柔性ITO膜为透明电极，制备了ITO／TPD／Alq3／Al结构柔性有机发光器件，并与在相同条件下制备的玻璃基片相同结构器件作了比较。研究了不同基片对有机材料及器件性能的影响，指出选择不易吸湿、耐温高、热胀系数小的聚合物材料，提高柔性ITO膜的附着力和导电性，结合柔性ITO膜的具体特性。优化有机层的蒸镀条件，是提高柔性有机发光器件发光亮度和稳定性的重要途径。     

A Necklace of Wulff Shapes

In a probabilistic model of a film over a disordered substrate, Monte-Carlo simulations show that the film hangs from peaks of the substrate. The film profile is well approximated by a necklace of Wulff shapes. Such a necklace can be obtained as the infimum of a collection of Wulff shapes resting on the substrate. When the random substrate is given by iid heights with exponential distribution, we prove estimates on the probability density of the resulting peaks, at small density.AMS subject classification: 60K35, 60K37, 82B24, 82B41     

新型衬底晶体LiGaO2的生长和结晶性质研究

氮化物长期以来被看作是在蓝光及紫外波段光电子应用中最有希望的材料[1].但在改进材料质量方面最大的困难是:缺乏一种能和GaN在晶格及热性能方面十分匹配的理想衬底材料[2].Al2O3被普遍认为可以作为GaN的衬底材料.这主要是由于它具有的结构、热性能好,和生长加工容易等特点.     

异硫氰酸荧光素标记抗体的固体基质室温磷光性质研究

研究了异硫氰酸荧光素（FITC）标记的羊抗人抗体（GAHAb-FITC)和兔抗羊抗体9RAGAb-FITC)，及其以三种免疫方式与人免疫球蛋白（IgG)反应所得免疫复合物在多种固体薄膜基质上发射室温磷光（RTP）的适宜条件及其光谱，强度和寿命等性质。研究发现，标记抗体及其免疫复合物保留了FITC优良的固体基质室温磷光性质，λ m0643em^(max)=525/650nm，其RTP强度与其浓度线性相关，并有很高的灵敏度，更为重要的是，免疫反应及其RTP检测能结合于同一基质，方便地相继完成，在聚酰胺膜（PM）上，以Pb(Ac)2为重原子微扰剂，稀释比为1：10（ψ）的GAHAb-FITC,RAGAb-FITC及其与人IgG形成的免疫复合物均能发射较强制 RTP信号并有较长的RTP寿命，本结果为建立相应的固体基质室温磷光免疫分析（SS-RTP-IA）新方法奠定了相应的实验基础。     

液相性质对制备硫化物纳米级粒子化膜的影响

研究氯化锌浓度，溶液酸碱度，离子强度等底液性质及反应温度对化学反应法在不溶膜上制备纳米级硫化锌粒子化膜的影响，得出了一些规律并加以初步的解释。     

Influence of aliphatic spacer group on adsorption mechanisms of phosphonate derivatives of l-phenylalanine: Surface-enhanced Raman, Raman, and infrared studies

The nature of phosphonopeptides containing N-terminal l-phenylalanine (l-Phe), namely l-Phe-dl-NH-CH(CH(CH₃)₂)-PO₃H₂ (A), l-Phe-l-NH-CH(CH₃)-PO₃H₂ (B), and l-Phe-dl-NH-CH(CH₂CH₂COOH)-PO₃H₂ (C) (Fig. 1 presents molecular structure of these molecules), adsorbed on electrochemically roughened and colloidal silver surfaces has been explored by surface-enhanced Raman spectroscopy (SERS). To reveal adsorption mechanism of these species on the basis of their SERS spectra at first Fourier-transform Raman (FT-RS) and absorption infrared (FT-IR) spectra of non-adsorbed molecules were measured. Examination of enhancement, frequency shifts, and changes in relative intensities of SERS bands due to adsorption and surface roughens variation reveals that the tilted compounds adsorb on the electrochemically roughened silver substrate in similar way, while they behave differently on the colloidal silver surface. A stronger enhancement of in-plane ring vibrations of the l-Phe ring, i.e., ν₃ and ν_18b (B₂), over these of the A₂ symmetry in all SERS spectra on the electrochemically roughened silver substrate suggests that the ring interacts with this surface adopting slightly deflect orientation from the perpendicular one. Also, enhancement of PO and -CH₂-/-CH₃ fragments vibrations points out that they are involved in adsorption process on this substrate. This conclusion was drawn on the basis of the enhancement of 1274-1279 and 1138-1152 (ν(PO)), 1393-1400 (δ(CH) + ρ_b(CNH₂) + ν(C-C_O) + δ(CH₃)), ∼1455 (δ(CCH₃/CCH₂) + ρ_b(CH₃/CH₂), and 1505-1512 cm⁻¹ (δ(CH₂) + Phe(ν_19a)) bands. Although a relative intensity ratio of these bands in the presented SERS spectra is different. On the other hand, on the colloidal silver nanoparticles, the aromatic ring of all molecules is lying flat or takes almost parallel orientation to this surface. Besides, A interacts also via P-terminal group (568, 765, 827, 1040, and 1150 cm⁻¹), whereas B mainly through NH₂-C-(CO)-CNH-(712 and 1255 cm⁻¹). In the case of C, it adsorbs on the silver colloidal surface mainly through the aromatic ring of l-Phe, while other fragments of the molecule are in close proximity to this surface as comes off the weak enhancement of bands due to the aliphatic vibrations.     

Adsorption mechanism of physiologically active l-phenylalanine phosphonodipeptide analogues: Comparison of colloidal silver and macroscopic silver substrates

Here we present SERS spectra of several l-phenylalanine (Phe) phosphonodipeptides, i.e., l-Phe-l-Ala-PO₃H₂ (MD1), l-Phe-l-Val-PO₃H₂ (MD2), l-Phe-β-Ala-CH(OH)-PO₃H₂ (MD3), l-Phe-l-Ala-CH(OH)-PO₃H₂ (MD4), l-Ala-(3,4-dimethoxy)-l-Phe-PO₃H₂ (MD5), and l-Ala-(3,4-dimethoxy)-(des-CH₂)-l-Phe-PO₃H₂ (MD6), immobilized on electrochemically roughened silver electrodes. These spectra are analyzed by theoretical calculations using density functional theory (DFT) at the B3LYP level with 6-31++G∗∗ basis set. In addition, these spectra are compared with SERS spectra of these species adsorbed on a colloidal silver surface. We showed that on the macroscopic silver substrate, the Phe aromatic ring of MD3 and MD4 is oriented vertically, while for MD1 it almost “stands up” on this surface. In the other three cases, the Phe ring adopts a tilted orientation in regard to the substrate. We also find that the phosphonate , methyl/methane, or dimethoxy groups of MD1, MD2, MD3, MD5, and MD6 are involved in the interaction of these phosphonodipeptides with the electrochemically roughened surface. This phenomenon is clearly seen for -CH₂-/-CH₃/-OCH₃ moieties as well as for the group that adsorbs on the macroscopic silver substrates mainly via the PO fragment. We also showed that MD4 binds to the macroscopic silver substrate through the hydroxyl, amine, and phosphonate groups, while the methylene/methane moieties are remote from this surface. We found that studied phosphonodipeptides often adsorb differently on the macroscopic silver substrate and on the colloidal silver nanoparticles. For example, MD1 adopts an almost vertical orientation on the electrochemically roughened silver substrate and is tilted or close to flat on the silver nanoparticles.     

High gain and circularly polarized substrate integrated waveguide cavity antenna array based on metasurface

Two substrate integrated waveguide (SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38% (4.05 GHz-5.95 GHz) and AR bandwidth of 24.9% (4.4 GHz-5.65 GHz). The bandwidth of the high gain antenna can reach 42.7% (3.95 GHz-6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.     

Two‐Dimensional Boron Monolayers Mediated by Metal Substrates

Two‐dimensional (2D) materials, such as graphene and boron nitride, have specific lattice structures independent of external conditions. In contrast, the structure of 2D boron sensitively depends on metal substrate, as we show herein using the cluster expansion method and a newly developed surface structure‐search method, both based on first‐principles calculations. The preferred 2D boron on weaker interacting Au is nonplanar with significant buckling and numerous polymorphs as in vacuum, whereas on more reactive Ag, Cu, and Ni, the polymorphic energy degeneracy is lifted and a particular planar structure is found to be most stable. We also show that a layer composed of icosahedral B₁₂ is unfavorable on Cu and Ni but unexpectedly becomes a possible minimum on Au and Ag. The substrate‐dependent 2D boron choices originate from a competition between the strain energy of buckling and chemical energy of electronic hybridization between boron and metal.