Fabrication of Pre-tilted Vertical Alignment Layers for High-Speed Liquid Crystal Display Using Bi-functional Photoreactive Monomers

Abstract

To enable recent 3D and moving picture applications, liquid crystal displays (LCD) must exhibit fast response and wide viewing angle characteristics. Pre-tilted vertical alignment layers for high-speed LCD were fabricated using bi-functional photoreactive monomers. The monomers can be confined to the polyimide layer and photo-polymerized by UV exposure under voltage. Response characteristics of photo-controlled alignment films according to the structure were investigated. Vertical alignment properties were evaluated using a polarizing optical microscope, and electro-optical characteristics were compared through the voltage-transmittance curve and response time measurement. Faster response speed could be obtained by using photoreactive monomers having a long alkyl chain.     

An efficient high-speed counter-current chromatography method for the preparative separation of sesquiterpenoids from the rhizomes of Cyperus rotundus L. combined with evaluation of the anti-inflammation activity in vitro and molecular docking

Cyperus rotundus L. has been extensively used in ancient medication for the treatment of different disorders worldwide, in which sesquiterpenes are the most representative components. In this study, sesquiterpenes were effectively purified by two-dimensional counter-current chromatography in combination with continuous injection and inner-recycling mode with a solvent system of n-hexane/ethyl acetate/methanol/water (1:0.2:1:0.2, v/v/v/v). For one-dimension separation, continuous injection mode was used with three times injection and the inner-recycling mode was adopted for the separation of two mixtures for two-dimensional separation. Finally, four sesquiterpenoids, including scariodione ( 1 ), cyperenoic acid ( 2 ), scariodione ( 3 ), and α-cyperone ( 4 ), were obtained with purities over 98%. Mass spectrometry and nuclear magnetic resonance were applied to identify their structures. The results from the anti-inflammation effect with zebrafish demonstrated that cyperenoic acid exhibited stronger anti-inflammation activity. Molecular docking results suggested that cyperenoic acid possessed lower binding energies –9.4545 kcal/mol with 1CX2 to form formed hydrogen bond interaction with ARG120. In general, all the obtained findings proved that the strong anti-inflammation capacity of cyperenoic acid can have the potential of being adopted for treating diseases resulting from inflammation.     

Development of a general separation strategy by countercurrent chromatography using sanshools from Zanthoxylum bungeanum oleoresin as a case study

Three kinds of sanshools were separated from Zanthoxylum bungeanum oleoresin by high-speed countercurrent chromatography. Sanshools are a series of amide compounds extracted from the Zanthoxylum bungeanum. Due to similar structures, polarities, and dissociation constants, it was challenging to select an appropriate solvent system for their complete separation by countercurrent chromatography. To address this challenge, a solvent-system-selection strategy was proposed to identify a relatively suitable solvent system. Additionally, a separation procedure incorporating multi-elution modes selection was established to separate similar compounds in a logical order. Ultimately, a solvent system comprising n-hexane:ethyl acetate:methanol:water in a ratio of 19:1:1:5.67 was selected. Three amide compounds with high purity were obtained through the use of recycling elution mode to improve separation resolution: hydroxy-ε-sanshool (8.4 mg; purity: 90.64%), hydroxy-α-sanshool (326.4 mg; purity: 98.96%), and hydroxy-β-sanshool (71.8 mg; purity: 98.26%) were obtained from 600 mg sanshool crude extract. The summarized solvent-system-selection strategy and separation procedure incorporating multi-elution modes may instruct countercurrent chromatography users, particularly novices, seeking to separate compounds with highly similar chemical properties.     

Biphasic alcoholysis coupled with high-speed countercurrent chromatography for high performance on separating phorbol from Croton tiglium Linn extracts

Phorbol is a tetracyclic diterpenoid found in Euphorbia tirucalli, Croton tiglium, and Rehmannia glutinosa, and is nuclear of various phorbol esters. The rapid obtaining of phorbol with high purity highly contributes to its application, such as synthesizing phorbol esters with designable side chains and particular therapeutic efficacy. This study introduced a biphasic alcoholysis method for obtaining phorbol from croton oil by using polarity imparity organic solvents in both phases and established a high-speed countercurrent chromatography method for simultaneous separation and purification of phorbol. The optimized operation conditions of biphasic alcoholysis were a reaction time of 91 min, a temperature of 14°C, and a croton oil-methanol ratio of 1:30 (g:ml). The phorbol during the biphasic alcoholysis was 3.2-fold higher in content than that obtained in conventional monophasic alcoholysis. The optimized high-speed countercurrent chromatography method was using the ethyl acetate/n-butyl alcohol/water at 4.7:0.3:5 (v:v:v) with Na₂SO₄ at 0.36 g/10 ml as the solvent system, using the mobile phase flow rate of 2 ml/min, the revolution of 800 r/min, under which the retention of the stationary phase was achieved at 72.83%. The crystallized phorbol following high-speed countercurrent chromatography was obtained as high purity of 94%.     

Scale-Up Preparation of Crocins I and II from Gardenia jasminoides by a Two-Step Chromatographic Approach and Their Inhibitory Activity Against ATP Citrate Lyase

Crocins are highly valuable natural compounds for treating human disorders, and they are also high-end spices and colorants in the food industry. Due to the limitation of obtaining this type of highly polar compound, the commercial prices of crocins I and II are expensive. In this study, macroporous resin column chromatography combined with high-speed counter-current chromatography (HSCCC) was used to purify crocins I and II from natural sources. With only two chromatographic steps, both compounds were simultaneously isolated from the dry fruit of Gardenia jasminoides, which is a cheap herbal medicine distributed in a number of countries. In an effort to shorten the isolation time and reduce solvent usage, forward and reverse rotations were successively utilized in the HSCCC isolation procedure. Crocins I and II were simultaneously obtained from a herbal resource with high recoveries of 0.5% and 0.1%, respectively, and high purities of 98.7% and 99.1%, respectively, by HPLC analysis. The optimized preparation method was proven to be highly efficient, convenient, and cost-effective. Crocins I and II exhibited inhibitory activity against ATP citrate lyase, and their IC₅₀ values were determined to be 36.3 ± 6.24 and 29.7 ± 7.41 μM, respectively.     

Optical Analysis and Qualitative Discrimination of Vortex-Flame Interaction in a Plane Premixed Shear Layer

To obtain practical schemes of vortex–flame interactions, a series of organized eddies formed in the plane premixed shear layer is investigated, instead of a single vortex ring or a single vortex tube. The plane premixed shear layer is first formed between two parallel uniform propane–air mixture streams. For getting clear qualitative pictures of vortex–flame interactions in the plane premixed shear layer, two extreme ignition points are assigned; one is assigned at the center of an organized eddy where the vortex motion plays an important role, the other at the midpoint between two adjacent organized eddies where the rolling-up motion prevails. A premixed flame is initiated by an electric discharge at one of the two assigned points and propagates either in the large scale organized eddy or along the interface between two uniform mixture streams. Propagation and deformation processes of the flame are observed using the simultaneously two-directional and high-speed Schlieren photography. The tangential velocity of organized eddy and the equivalence ratio of premixed shear flow are varied as two main parameters. The outline of propagating flame after the midpoint ignition is numerically analyzed by superposing the flame propagation having a constant burning velocity on the vortex flow field simulated with the discrete vortex method. The results obtained show that there exists another type of vortex–flame interaction in the plane shear layer in addition to the vortex bursting, and that it is caused by the rolling-up motion particular to the coherent structure in the plane shear layer and is simply named the vortex boosting. It is qualitatively concluded therefore that, in the ordinary turbulent premixed flames formed in the plane premixed shear layer, these two fundamental vortex-flame interactions get tangled with each other to augment the propagation velocity. An empirical expression which qualitatively takes into account of the effects of both vortex and chemical properties is finally proposed.     

聚晶立方氮化硼刀具切削高锰钢的磨损机制

在半精加工试验条件(切削深度ap=0．5mm，进给量f=0．3mm／r，干切)下研究了聚晶立方氮化硼刀具切削奥氏体高锰钢时的磨损机制，用WDH-Ⅱ型光电温度计测量了切削温度，用工具显微镜测量后刀面磨损量，进而考察了切削时间和切削速度对后刀面磨损量的影响，采用S-250MK型扫描电子显微镜观察刀具前、后刀面的磨损形貌和组成变化．结果表明：当切削温度为400～750℃时，聚晶立方氮化硼刀具同高锰钢中的γ相及其析出相(Fe，Mn)3C之间产生严重的机械磨损；当切削温度超过800℃时，聚晶立方氮化硼刀具同高锰钢单一γ相之间产生扩散磨损；聚晶立方氮化硼刀具适合于高速切削.     

硬度及冲击韧性对高钒高速钢磨损稳定性的影响

通过改变热处理工艺获得不同硬度及冲击韧性、含钒10%的高钒高速钢试样,提出了磨损稳定性的概念及采用磨损稳定性因子(K)量化磨损稳定性的方法,研究了硬度和冲击韧性对高钒高速钢的磨损稳定性影响.结果表明:随着硬度增加,磨损稳定性及其耐磨性提高;随着冲击韧性提高,虽然耐磨性降低,但磨损稳定性有所提高.在本文试验条件下,随着残余奥氏体变化量(△A)增加,高钒高速钢的磨损稳定性下降.     

FJZ-1000型超高速转镜分幅相机及其应用

FJZ-1000型超高速转镜分幅相机最高摄影幅频为1107幅/s，画幅总数160幅，尺寸7.5 mm10 mm。光学系统中新加入场镜以使相机的所有画幅均完整成像，使相机摄影频率全面达到标称值的技术指标。配备了新型数字化微机控制台，使相机的操作更加方便，并且实现了两台气动相机的联合拍摄，与脉冲X光机也进行了联动实验。相机达到了设计技术性能指标，实验取得了满意的结果。     

Background oriented schlieren for flow visualisation in hypersonic impulse facilities

Experiments to demonstrate the use of the background-oriented schlieren (BOS) technique in hypersonic impulse facilities are reported. BOS uses a simple optical set-up consisting of a structured background pattern, an electronic camera with a high shutter speed and a high intensity light source. The visualization technique is demonstrated in a small reflected shock tunnel with a Mach 4 conical nozzle, nozzle supply pressure of 2.2 MPa and nozzle supply enthalpy of 1.8 MJ/kg. A 20° sharp circular cone and a model of the MUSES-C re-entry body were tested. Images captured were processed using PIV-style image analysis to visualize variations in the density field. The shock angle on the cone measured from the BOS images agreed with theoretical calculations to within 0.5°. Shock standoff distances could be measured from the BOS image for the re-entry body. Preliminary experiments are also reported in higher enthalpy facilities where flow luminosity can interfere with imaging of the background pattern. A version of this paper was presented at the 25th International Symposium on Shock Waves in Bangalore in July 2005.