Homoisoflavonoids from Ophiopogon japonicus

Phytochemical study on the root tubers of Ophiopogon japonicus resulted in the isolation and identification of 13 homoisoflavonoids, including three new compounds, 8‐formyl‐7‐hydroxy‐5,4′‐dimethoxy‐6‐methylhomoisoflavone ( 1 ), 6‐formylisoophiopogonone B ( 2 ), and 8‐formylophiopogonanone B ( 4 ), and the ten known homoisoflavonoids 3 , and 5 – 13 . The absolute configurations of 8‐formylophiopogonanone B ( 4 ) and 8‐formyl‐7‐hydroxy‐5,4′‐dimethoxy‐6‐methylhomoisoflavanone ( 5 ) were confirmed by time‐dependent density‐functional‐theory (TD DFT) calculations of their theoretical electronic circular dichroism (ECD) spectra. The structure of the formerly reported ‘6‐aldehydoisoophiopogonone B’ was revised to 8‐formylophiopogonone B ( 3 ). All compounds were evaluated for their cytotoxic activities against the human‐lung‐tumor A549 cell line, and compounds 3, 9, 10 , and 13 exhibited promising antiproliferative activities with IC₅₀ values of 10.01, 6.40, 0.84, and 1.66 μM , respectively.     

Hydrothermal Synthesis of SrMoO4:Eu3+, Sm3+ Phosphors and Their Enhanced Luminescent Properties Through Energy Transfer

Eu³⁺ and Sm³⁺ co-doped SrMoO₄ phosphors have been successfully prepared via a simple surfactant-free hydrothermal method. The as-prepared phosphors present dumbbell-like agglomerates and comprise of many nanoparticles of 150–300 nm in diameter. Eu³⁺ and Sm³⁺ co-doped SrMoO₄ phosphors display all the characteristic excitations and emissions of Eu³⁺ and Sm³⁺. The introduction of Sm³⁺ can generate a strong excitation line at 403 nm, originating from the ⁶H_5/2 → ⁴K_11/2 transition of Sm³⁺, which significantly broadened the excitation region for matching the near ultraviolet light emitting diodes (～400 nm). And Sm³⁺ ions can transfer the absorbed energy to Eu³⁺ ions efficiently, so the intensity of the main emission peak at 614 nm due to ⁵D₀ → ⁷F₂ transition of Eu³⁺ are strengthened by the co-doping of Sm³⁺. The doping concentration of Eu³⁺/Sm³⁺ was optimized. In addition, the possible energy transfer mechanism has been investigated and is discussed in detail.     

Au-In-based Hermetic Sealing for MEMS Packaging for Down-Hole Application

Hermetic sealing of micro-electro mechanical systems (MEMS) sensors for down-hole application requires high-quality void-free bonds, with metallic hermetic sealing being widely used for this purpose. As most of the MEMS sensors cannot withstand high temperatures, transient liquid phase (TLP) bonding is promising for metallic sealing applications, since the re-melting temperature of the bond is much higher than the bonding temperature. In this paper, major issues involving TLP bonding, including non-uniform diffusion kinetics across the interface and the formation of intermetallic compounds prior to bonding for fast reactive metallic systems like Au-In, have been addressed by using diffusion barriers. The performance of various diffusion barriers that include Ti, Ni, and Pt has been evaluated. Ni has been determined to be a prospective candidate, since it averts diffusion to a certain extent prior to TLP bonding. The mechanical strength and hermeticity of the Au-In joints have also been characterized after aging at 300 °C up to 500 h. No major changes in the thermo-mechanical properties of the AuIn and AuIn₂ phases were observed and, hence, these phases are concluded to be thermally stable at this temperature regime. Improvements in hermeticity were confirmed when subjected to high-temperature thermal aging.     

基于USRP的DVB-T接收机实现

为提高地面数字电视广播(DVB-T)接收机的实现灵活性,基于由通用软件无线电外设(Universal Software Radio Peripheral,USRP)和通用计算机组成的软件无线电平台,实现DVB-T接收机。接收机以USRP作为射频前端,在通用计算机中完成全部基带信号处理、视频解码与显示等。测试结果表明,接收机可实现对DVB-T信号的接收,为接收机算法开发、验证与评估提供了更为灵活的方法。     

Enhancement of magnetoresistance sensitivity in Co/Cu/NiFe trilayers by softening the Co hard layer

Co/Cu/NiFe trilayers were prepared by sputtering without magnetic field applied. We have found that the Co(2 nm)Cu(1 nm)NiFe(2 nm) trilayer using Ta as buffer layer exhibits an enhanced magnetoresistance (MR) sensitivity by a factor of more than 6 and a low saturation field of 9.3 Oe. Experimental results have demonstrated that the low saturation field is attributed to the softening of the Co layer by depositing the Co(2 nm)Cu(1 nm)NiFe(2 nm) sandwich on Ta layer. The decrease of the coercivity of the Co layer also plays an important role in the enhancement of MR sensitivity by reducing the effective coercivity of the NiFe layer, which is discussed in terms of the change in interlayer coupling.     

酞菁铜薄膜的折射率及吸收特性

通过真空镀膜法在单晶硅制备了酞菁铜薄膜，在波长扫描和入射角可变全自动椭圆偏振光谱仪上研究了ＣｕＰｃ薄膜的椭偏光谱并分析了其电子结构。     

一种用于半导体激光器的高精度温控仪

利用温度传感器AD590和运算放大器LM358构成放大电路，用半导体致冷器做控温元件，研制了一种用于半导体激光器温度控制用的高精度温控仪，控制精度达0.1℃。     

数字网格技术在BOSS 3.0的数据比对能力的研究与实践

利用网格（datagrid）技术实现BOSS中用户数据的比对分析,本文提供了一种高效低成本的解决方式。     

A new series of two-photon polymerization initiators: Synthesis and nonlinear optical properties

Four photopolymerization initiators with D-π-D (D, donor; π, conjugation system) structure have been synthesized by solvent-free reaction and characterized by ¹H NMR spectroscopy, IR and elemental analysis. The one-photon and two-photon excited fluorescence have been investigated in different solvents. Experimental results of the one-photon and two-photon absorption cross sections show different trends in OPA and TPA ability with different substitution groups in donor units.     

“Click” chemistry for in situ formation of thermoresponsive P(NIPAAm‐co‐HEMA)‐based hydrogels

The strategy for in situ chemical gelation of poly(N‐isopropylacrylamide‐co‐hydroxylethyl methacrylate) [P(NIPAAm‐co‐HEMA)]‐based polymers was demonstrated. Two types of new P(NIPAAm‐co‐HEMA) derivatives with alkyne and azide pendant groups, respectively, were prepared. When the solutions of the two derivatives were mixed together, a crosslinking reaction, a type of Huisgen's 1,3‐dipolar azide‐alkyne cycloaddition, in the presence of Cu(I) catalyst occurs. The morphology, equilibrium swelling ratio, swelling kinetics, and temperature response kinetics of the in situ gelated hydrogels were studied. In comparison with the conventional PNIPAAm hydrogel, because of the spatial hindrance of polymeric chains, the resulted hydrogels had a macroporous structure as well as a fast shrinking rate. The strategy described here presents a potential alternative to the traditional synthesis techniques for the in situ formation of thermoresponsive hydrogels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5263–5277, 2008