一种大屏幕图文显示屏系统的设计

介绍了一种以ＰＣ机主板为核心的控制ＬＥＤ大屏幕显示屏的设计。数据传送采用ＤＭＡ方工，画面处理可直接在ＰＣ机上完成。     

Cell-specific internalization study of an aptamer from whole cell selection

Nucleic acid aptamers have been shown many unique applications as excellent probes in molecular recognition. However, few examples are reported which show that aptamers can be internalized inside living cells for aptamer functional studies and for targeted intracellular delivery. This is mainly due to the limited number of aptamers available for cell-specific recognition, and the lack of research on their extra- and intracellular functions. One of the major difficulties in aptamers' in vivo application is that most of aptamers, unlike small molecules, cannot be directly taken up by cells without external assistance. In this work, we have studied a newly developed and cell-specific DNA aptamer, sgc8. This aptamer has been selected through a novel cell selection process (cell-SELEX), in which whole intact cells are used as targets while another related cell line is used as a negative control. The cell-SELEX enables generation of multiple aptamers for molecular recognition of the target cells and has significant advantages in discovering cell surface binding molecules for the selected aptamers. We have studied the cellular internalization of one of the selected aptamers. Our results show that sgc8 is internalized efficiently and specifically to the lymphoblastic leukemia cells. The internalized sgc8 aptamers are located inside the endosome. Comparison studies are done with the antibody for the binding protein of sgc8, PTK7 (Human protein tyrosine kinase-7) on cell surface. We also studied the internalization kinetics of both the aptamer and the antibody for the same protein on the living cell surface. We have further evaluated the effects of sgc8 on cell viability, and no cytotoxicity is observed. This study indicates that sgc8 is a promising agent for cell-type specific intracellular delivery.     

Dual-salts of LiTFSI and LiODFB for high voltage cathode LiNi0.5Mn1.5O4

Journal of Solid State Electrochemistry - The LiNi0.5Mn1.5O4 has been investigated as promising because of its high operating voltage (4.7 V vs. Li+/Li) and decent specific capacity....     

Pillararene Host–Guest Complexation Induced Chirality Amplification: A New Way to Detect Cryptochiral Compounds

The contradiction between the rising demands of optical chirality sensing and the failure in chiral detection of cryptochiral compounds encourages researchers to find new methods for chirality amplification. Inspired by planar chirality and the host–guest recognition of pillararenes, we establish a new concept for amplifying CD signals of cryptochiral molecules by pillararene host–guest complexation induced chirality amplification. The planar chirality of pillararenes is induced and stabilized in the presence of the chiral guest, which makes the cryptochiral molecule detectable by CD spectroscopy. Several chiral guests are selected in these experiments and the mechanism of chiral amplification is studied with a non-rotatable pillararene derivative and density functional theory calculations. We believe this work affords deeper understanding of chirality and provides a new perspective for chiral sensing.     

地下爆炸气体输运的一种双孔隙度数学模型

考虑气体在压力驱动下的渗透、气体和岩体的热传导以及气体的扩散,建立了用于模拟地下爆炸气体输运的二维轴对称双孔隙度双渗透率数学模型,并编制了数值模拟程序;研究了参数在取值范围内变化对计算结果的影响。结果显示：泄漏到地表的气体随着裂隙区域圆心角的增大而先增大后减小,随裂隙渗透率的增大而增大,随介质孔隙度和孔隙渗透率的增大而减小。用该模型对一次砂砾岩中地下爆炸实验气体的泄漏行为进行了数值模拟。将数值模拟结果与气体泄漏实测结果进行对比,反推出当地介质的裂隙渗透率在4×10^-11 m2～5×10^-11 m2之间。利用反推得到的介质参数,可以对同类介质中地下爆炸气体泄漏行为进行预测。     

Toughening of ethylene-propylene random copolymer/clay nanocomposites: Comparison of different compatibilizers

Ethylene/propylene-random-copolymer(PPR)/clay nanocomposites were prepared by two-stage melt blending. Four types of compatibilizers,including an ethylene-octene copolymer grafted maleic anhydride(POE-g-MA) and three maleic-anhydride-grafted polypropylenes(PP-g-MA) with different melt flow indexes(MFI),were used to improve the dispersion of organic clay in matrix.On the other hand,the effects of organic montmorillonite(OMMT) content on the nanocomposite structure in terms of clay dispersion in PPR matrix,thermal behavior and tensile properties were also studied. The X-ray diffraction(XRD) and transmission electron microscopy(TEM) results show that the organic clay layers are mainly intercalated and partially exfoliated in the nanocomposites.Moreover,a PP-g-MA compatibilizer(compatibilizer B) having high MFI can greatly increase the interlayer spacing of the clay as compared with other compatibilizers.With the introduction of compatibilizer D(POE-g-MA),most of the clays are dispersed into the POE phase,and the shape of the dispersed OMMT appears elliptic,which differs from the strip of PP-g-MA.Compared with virgin PPR,the Young’s modulus of the nanocomposite evidently increases when a compatibilizer C(PP-g-MA) with medium MFI is used.For the nanocomposites with compatibilizer B and C,their crystallinities(X_c) increase as compared with that of the virgin PPR. Furthermore,the increase of OMMT loadings presents little effect on the melt temperature(T_m) of the PPR/OMMT nanocomposites,and slight effect on their crystallization temperature(T_c).Only compatibilizer B can lead to a marked increases in crystallinity and T_c of the nanocomposite when the OMMT content is 2 wt%.     

Modification of the Interlayer in HTiNbO5 and its Physicochemical Characterization

Abstract

A layered titanoniobate, in which the interlayer of the metal oxide based on octahedral framework is pillared with silica, has been prepared from HTiNbO₅ by employing alkylamines (C_nH_2n+1NH₂, n = 4, 6, 8, 10) and tetraethylorthosilicate as interlayer exchange guests and a pillar precursor, respectively. The incorporated amine had bilayer arrangements in the interlayer space and their ammonium head groups pointed to the host (TiNbO5₅ ^?) layers. While the basal spacing of the compounds increased with the chain length of alkylamine. the inclination angle also increased. The intercalated structure facilitated the incorporation of tetraethylorthosilicate into the interlayers, and silica-pillared layered titanoniobate was obtained after calcination. The physicochemical properties of the resultant pillared compounds were characterized on the interlayer microstructure, nitrogen adsorption and UV-VIS absorption spectra.     

扫频光学相干层析成像系统的波数校正与相位测量研究

相位敏感光学相干层析成像(OCT)系统可以用于高灵敏度的相位探测,在细胞分析、材料检测等方面具有重要应用,但扫频光源的不稳定性会影响扫频OCT系统的相位测量精度.本文提出了一种基于马赫-曾德尔干涉仪(MZI)时域相位信息的波数校正方法.利用MZI时域包裹相位的互相关运算确定各采集波数序列的相对偏移量,鉴于时域包裹相位的非严格周期特征,可确定偏移量的大小不受限制.依据相对偏移量对各序列信号进行时域同步,并基于同步后的MZI时域解包裹相位实施待测干涉信号在位相域的等间隔重采样.基于所提出的波数校正方法,实施了各扫频序列波数偏移量的校正,开展了基于位相信息的光程重复性测量实验.结果表明,即使在不稳定扫频光源的前提下,也能获得高精度的相位测量结果.     

A friction contact stiffness model of fractal geometry in forced response analysis of a shrouded blade

To investigate the nonlinear vibration behavior of a shrouded blade with friction dynamic contact interface, a friction contact stiffness model is proposed to describe the friction force at different rough interfaces and different normal loads. In the proposed model, the friction contact interface is discretized to a series of friction contact pairs and each of them can experience stick, slip, or separate states. Fractal geometry is used to simulate the topography of contact surfaces. The contact stiffness is calculated using the Hertz contact theory and fractal geometry, which is related to contact interfaces parameters including normal load, roughness, Young??s modulus, and Poisson??s ratio. The trajectory tracking method is used to predict the friction force and it is not necessary to judge the transition condition among stick, slip, and separate states. It is suitable for complicated periodic motion of the contact interfaces. The forced response of a real shrouded blade is predicted using the proposed model and the multi-harmonic balance method. The effect of surface roughness, initial normal load, and contact area on the forced response of a shrouded blade is studied. It is shown that contact stiffness increases with normal load and fractal dimension. The resonant amplitude is sensitive to the initial normal load and contact surface roughness. The response can be influenced by the contact area, which is an important parameter for blade designers.     

A copper-carbodiimide approach to the phomopsin tripeptide side chain

A one-step copper-carbodimide elimination was used to provide the (E)-dehydroisoleucine moiety in the phomopsin side chain stereoselectively. An efficient approach to the phomopsin tripeptide side chain was developed to be used in the total syntheses of phomopsins A and B.