Driving matrix liquid crystal displays

Liquid crystal displays had a humble beginning with wrist watches in the seventies. Continued research and development in this multi-disciplinary field have resulted in displays with increased size and complexity. After three decades of growth in performance, LCDs now offer a formidable challenge to the cathode ray tubes (CRT). A major contribution to the growth of LCD technology has come from the developments in addressing techniques used for driving matrix LCDs. There are several approaches like passive matrix addressing, active matrix addressing and plasma addressing to drive a matrix display. Passive matrix LCD has a simple construction and uses the intrinsic non-linear characteristic of the LCD for driving. Departure from conventional line by line addressing of a passive matrix has resulted in improved performance of the display. Orthogonal functions have played a crucial role in the development of passive matrix addressing. Simple orthogonal functions that are useful for driving a matrix LCD are introduced. The basics of driving several rows simultaneously (multi-line addressing) are discussed by drawing analogies from multiplexing in communication. The impact of multi-line addressing techniques on the performance of the passive matrix LCDs in comparison with the conventional technique will be discussed.     

On the governing equations for the compressing process and its coupling with other processes

As a continuation of a recent linear analysis by Mao et al.(Acta Mech Sin,2010,26:355),in this paper we propose a general theoretical formulation for the compressing process in complex Newtonian fluid flows,which covers gas dynamics,aeroacoustics,nonlinear thermoviscous acoustics,viscous shock layer,etc.,as its special branches.The principle on which our formulation is based is the maximally natural and dynamic Helmholtz decomposition of the Navier-Stokes equation,along with the kinematic Helmholtz decompos...     

Chemistry of sulfonyl isocyanates and sulfonyl isothiocyanates. XI. Cyclizations with epoxides

4-Toluenesulfonyl isocyanate cyclized with 1,2-epoxy-3-phenoxypropane and 2,3-epoxypropyl 4-methoxyphenyl ether, respectively, to give 3-(4-toluenesulfonyl)-5-phenoxymethylene-2-oxazolidone ( I ) and 3-(4-toluenesulfonyl)-5-(4-methoxyphenoxymethylene)-2-oxazolidone ( II ). Compounds I and II were hydrolyzed in 2 M sodium hydroxide solution to the corresponding uncyclized hydroxy amides, VII and VIII. Compound I was remarkably stable toward 6 M hydrochloric acid and amines. Styrene oxide, 1,2-epoxybutane, 3-chloro-1,2-epoxypropane, and 1-methoxy-2-methylpropylene oxide reacted with the isocyanate to afford 3-(4-toluene-sulfonyl)-4-phenyl-2-oxazolidone (III), 3-(4-toluenesulfonyl)-4-ethyl-2-oxazolidone ( IV ), 3-(4-toluenesulfonyl)-5-chloromethyl-2-oxazolidone ( V ), and 3-(4-toluenesulfonyl)-4,4-dimethyl-5-methoxy-2-oxazolidone ( VI ), respectively. The yield of VI was constant over a temperature range of 25–90°.     

Fast quantitative determination of melamine and its derivatives by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A simple, sensitive and fast method for the determination of melamine and its derivatives in milk powder using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was developed. Neither time-consuming sample preparation, nor special target plates, or other extra equipment are necessary. The common matrix sinapinic acid (SA) was used with a dried-droplet preparation. Detection limits (signal-to-noise (S/N) ratio = 3) for standard solutions of melamine, ammeline and cyanuric acid were 10, 25 and 10 μg/L, respectively. The limit of quantification (LOQ) for melamine was 25 μg/L and excellent linearity (R(2): 0.9990) was maintained over the range of 10-2000 μg/L. Ammeline and cyanuric acid were analyzed with an LOQ of 50 μg/L and also excellent linearity (R(2): 0.9997 and R(2): 0.9998). Good accuracy and precision were obtained for all concentrations within the range of the standard curve. The developed method was successfully used for the determination of melamine, ammeline and cyanuric acid in milk powder samples with a simple sample preparation. The LOQ of melamine was 0.5 μg/g. Ammeline and cyanuric acid were detectable at 0.5 and 5 μg/g. This method showed excellent accuracy, precision and linearity and significantly reduces the needed analysis time, as only approximately 10 s/sample measuring time is required. To the authors' knowledge, this is the first published method to quantify melamine and derivatives by MALDI-TOF-MS.     

Phosphorylation site localization in peptides by MALDI MS/MS and the Mascot Delta Score

Owing to its broad biological significance, the large-scale analysis of protein phosphorylation is more and more getting into the focus of proteomic research. Thousands of phosphopeptides can nowadays be identified using state-of-the-art tandem mass spectrometers in conjunction with sequence database searching, but localizing the phosphate group to a particular amino acid in the peptide sequence is often still difficult. Using 180 individually synthesized phosphopeptides with precisely known phosphorylation sites (p-sites), we have assessed the merits of the Mascot Delta Score (MD score) for the assignment of phosphorylation sites from tandem mass spectra (MS/MS) generated on four different matrix-assisted laser desorption ionization (MALDI) mass spectrometers including tandem time-of-flight (TOF/TOF), quadrupole time-of-flight, and ion trap mass analyzers. The results show that phosphorylation site identification is generally possible with false localization rates of about 10%. However, a comparison to previous work also revealed that phosphorylation site determination by MALDI MS/MS is less accurate than by ESI-MS/MS particularly if several and/or adjacent possible phosphorylation acceptor sites exist in a peptide sequence. We are making the tandem MS spectra and phosphopeptide collection available to the community so that scientists may adapt the MD scores reported here to their analytical environment and so that informatics developers may integrate the MD score into proteomic data analysis pipelines.     

Chemistry of sulfonyl isocyanates and sulfonyl isothiocyanates. XII. Cyclizations with epoxides

4-Toluenesulfonyl isothiocyanate reacted with 1,2-epoxy-3-phenoxypropane and 2,3-epoxypropyl 4-methoxyphenyl ether to give, respectively, 3-(4-toluenesulfonyl)-5-phenoxymethylene-2-oxazolidmethione ( I ) and 3-(4-toluenesulfonyl)-5-(4-methoxyphenoxymethylene)-2-oxazolidinethione ( II ) in high yields. The sulfonyl isothiocyanate reacted further with styrene oxide to give a mixture of oxazolidinethiones from which a solid III was isolated. The structure of III is either the 4- or 5-phenyl derivative of 3-(4-toluenesulfonyl)-2-oxazolidinethione. Reactions of the isothiocyanate with 3-chloro-1,2-epoxypropane and 1,2-epoxybutane afforded, respectively, 3-(4-toluenesulfonyl)-5-chloromethyl-2-oxazolidinethione ( IV ) and 3-(4-toluenesulfonyl)-4-ethyl-2-oxazolidinethione ( V ). Evidence for structures was by pmr, ir, and elemental analyses.