LED微阵列投影系统设计

为满足便携式投影仪的市场需求,设计了一种基于LED微型阵列的投影系统。该系统由显示单元和投影物镜构成。采用尺寸为12 mm×9 mm的自发光LED微型阵列作为系统的显示单元,利用光学设计软件设计了投影物镜。投影物镜采用反远距光学结构,全视场角为80°,焦距为8 mm,属于强光、广角镜头。在空间频率20 lp/mm处,该物镜的调制传递函数大于0. 85,畸变小于2%,符合投影系统的设计要求。该投影系统具有体积小,结构简单,投影效果好,易加工等诸多优势,可为第三代投影技术的发展提供参考。     

新郑西亚斯东周玉器材料属性与加工工艺的科技分析

中国玉文化源远流长，治玉工艺经过各个时代的不断发展和完善，在一定程度上能反映古代社会生产力发展水平及文化、贸易、技术交流等信息。利用能量色散型X射线荧光光谱（EDXRF）、激光拉曼光谱（LRS）、超景深光学显微系统（OM）等分析技术，结合硅胶覆膜微痕复制技术，对河南省新郑西亚斯东周墓地出土的一批玉器进行科技分析。首先利用化学成分和物相结构分析技术确定了玉器材质的矿物属性，其次利用显微分析技术表征了玉器表面及穿孔内部和印模的加工痕迹，特别是阴刻纹饰和穿孔微痕特征，最后探讨了玉器样品的材料属性和加工工艺两者之间的联系。化学成分和物相结构分析结果表明，所分析的西亚斯东周玉器材质丰富，主要矿物组成有滑石、透闪石、水晶、云母等。玉器表面纹饰微痕特征分析表明，所分析玉器阴刻工艺采用了两种加工工具，分别是砣具和手持硬质工具。穿孔微痕分析特征表明，钻孔包括单面钻孔和双面/多面钻孔两种方式，钻孔工艺则有实心钻、管钻等。部分玉器钻孔形状和内部微痕特征表明，尽管均采用了实心钻工艺，但所采用的实心钻头在形状上存在差异，同时，也存在是否配合解玉砂进行钻孔的差异。不同材料属性的玉器采用了不同的加工工艺。滑石质玉器，莫氏硬度1，器型主要为玉片饰，其表面阴刻纹饰主要采用手持硬质工具进行刻画，钻孔主要采用了双面钻孔方式，并使用了实心钻头未添加解玉砂进行加工，钻头形状可能为圆锥状；云母质玉器，莫氏硬度2~3，器型主要为玉玦片饰，纹饰采用了砣具添加解玉砂的加工工艺，钻孔方式为单面钻孔，采用了管钻工艺。透闪石型玉器，莫氏硬度5~6，器型主要为玉片饰，表面纹饰采用砣具配合解玉砂砣刻，以双面钻孔的方式为主，钻孔工艺为实心钻头配合解玉砂工艺，钻头形状与滑石类样品一致，为圆锥状。水晶质玉器，莫氏硬度7，均为珠饰，表面无纹饰，钻孔方式为双面/多面钻孔，钻孔工艺为实心钻配合解玉砂工艺，且钻头可能为圆柱形。研究结果表明，玉器表面纹饰所采用的阴刻工艺和钻孔工艺，与玉器本身的材料属性、器型等存在密切关系。     

Synthetic Studies on Spirolides A and B: Formation of the Upper Carbon Framework Based on a Lewis Acid Template-Catalyzed Diels–Alder Reaction

The upper fragment of spirolides A and B, which are marine phycotoxins that exhibit strong antagonistic activities on nicotinic acetylcholine receptors, was constructed. The functionalized cyclohexene in spirolides was stereoselectively synthesized from the bicyclic lactone, which could be readily accessed by the Lewis acid template-catalyzed asymmetric Diels–Alder reaction of the pentadienol and methyl acrylate.     

Glycopeptides by Linch-Pin C−H Activations for Peptide-Carbohydrate Conjugation by Manganese(I)-Catalysis

Late-stage C−H glycosylations of structurally complex amino acids and peptides were accomplished by means of racemization-free manganese(I)-catalyzed C−H activation. Thus, glycosylative modifications proved to be viable by a linch-pin approach, featuring chemo- and site-selective C−H transformations. The peptide–saccharide conjugation provided modular access to structurally complex glycopeptides, likewise enabling the assembly of fluorescent-labelled glycopeptides.     

A highly selective dual-channel Hg2+ chemosensor based on an easy to prepare double naphthalene Schiff base

Science China Chemistry - A non-sulfur chemosensor based on an easy to prepare double naphthalene Schiff base is reported for the colorimetric and fluorometric dual-channel sensing of Hg2+ ions by...     

Selective preconcentration of trace thorium from aqueous solutions with Th(IV)-imprinted polymers prepared by a surface-grafted technique

A novel ion-imprinted adsorbent for selective solid phase extraction of thorium(IV) based on the surface of silica gel was prepared by a surface-grafted technique with methacrylic acid (MAA) as a functional monomer. After removal of Th(IV) ions with 3?mol?L^?1 HCl solution, the obtained imprinted particles for Th(IV) exhibited specific recognition and relatively rapid kinetic process. The maximum static and total dynamic adsorption capacity of the ion-imprinted polymers (IIPs) for Th(IV) was 33.2 and 17.3?mg?g^?1, respectively. A comparison of the selectivity coefficient of the imprinted polymers with that of non-imprinted polymers showed that the imprinted matrix for Th(IV)/U(VI), Th(IV)/Ce(III), Th(IV)/La(III) and Th(IV)/Zr(IV) was 58.8, 107, 106.4 and 151.7 times greater than non-imprinted matrix, respectively. With a series of samples loading flow rate of 3?mL?min^?1 for preconcentration, an enrichment factor of 14.6 and the detection limit of 0.59?µg?L^?1 were obtained. The relative standard deviation of the method under optimum conditions was 2.1% (n?=?7). The developed method was successfully applied to the determination of trace Th(IV) in real water samples with satisfactory results.     

Synthesis and characterization of intrinsic high‐barrier polyimide derived from a novel diamine monomer containing rigid planar moiety

A new diamine monomer containing rigid planar fluorenone moiety, 2,7‐bis(4‐aminophenyl)‐9H‐fluoren‐9‐one, was synthesized through Suzuki coupling reaction. Then it was reacted with pyromellitic dianhydride to obtain a polyimide (FOPPI) via a conventional two‐step polymerization process. The prepared FOPPI exhibits excellent barrier properties, with the oxygen transmission rate and water vapor transmission rate low to 3.2 cm³·m^?2·day^?1 and 2.9 g·m^?2·day^?1, respectively. The results of wide angle X‐ray diffractograms, positron annihilation lifetime spectroscopy, and molecular dynamics simulations reveal that the excellent barrier properties of FOPPI are mainly ascribed to the crystallinity, high chain rigidity, and low free volume, which are resulted from the rigid planar moiety. FOPPI also shows outstanding thermal stability and mechanical properties with a glass transition temperature up to 420 °C, 5% loss temperature of 607 °C, coefficient of thermal expansion of 1.28 ppm K^?1, and tensile strength of 150.8 MPa. The polyimide has an attractive potential application prospect in the flexible electronics encapsulation area. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2373–2382     

HL-2Aװ��3.7GHz LHCDϵͳ������Ч�ʲ�������

The power measurement method for 3.7GHz LHCD system on HL-2A was introduced. It is found by HFSS simulation that the impact of backward wave phase on the measurement of forward power may be suppressed if the isolation of directional coupler is more than 30dB. After improving the system, the total transmission line efficiency of the LHCD system can reach 89% with maximum power 1.5MW in 2016 experiment campaign.     

Studies on Carbohydrates X. A New Method for the Preparation of Isopropylidene Saccharides

Cabohydrates reacting with acetone in the presence of molecular sieve and p—toluene sulfonic acid provided a simple, convenient, high yield and good selective process for preparation of isopropylidene carbohydrates.     

Two 2D uranyl coordination complexes showing effective photocatalytic degradation of Rhodamine B and mechanism study

Two new hydrostable two-dimensional(2 D) uranyl coordination complexes [(UO_2)_5(μ_3-O)_2(nbca)_2].7 H_2O(1) and [(UO_2)_3(nbca)_2(H_2O)_3]·2 H_2O(2)(H_3 nbca=5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized.Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds.The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets.There are UO_8 hexagonal bipyramids and UO_7 pentagonal bipyramids in 1 while only U07 pentagonal bipyramids in 2.Photocatalytic degradation of rhodamine B(RhB) in aqueous solution was studied.Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min.Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation.The photocurrent density of 2 is more stable than that of 1,which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.