New cerebrosides from the marine sponge Oceanapia sp.

New cerebrosides containing N-acetylglucosamine were isolated from the marine sponge Oceanapia sp. Some of them contain n-and iso-C₁₈-and iso-C₁₉-phytosphingosines N-acylated by n-C_16:0, n-C_17:0, and n-C_18:0 fatty acids, some other are derivatives of iso-and anteiso-C₁₇-,-C₁₈-, and-C₁₉-phytosphingosines N-acylated by long-chain (C₂₄-C²⁸) α-hydroxy acids. The structures of these compounds were determined by NMR spectroscopy, MALDI-TOF mass spectrometry, and by chemical transformations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 895–899, May, 2006.     

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...     

Determination of absolute stereochemistry of natural alicyclic glycosides by 1H NMR spectroscopy without application of chiral reagents--an indication

A study has been made of the 1H NMR spectra of peracetylated beta-glucopyranosides and alpha-arabinopyranosides obtained by reaction of D- and L-glucoses, and L- and D-arabinoses with either (R)- or (S)-2-octanols. The obtained and literature data show that 1H NMR spectra may be used to determine the absolute configuration of the aglycone moieties of some alicyclic glycosides without the need to synthesize derivatives with chiral reagents, as long as the absolute configuration of their monosaccharide moiety is known or vice versa. Spectra of marine steroid glycosides and their acetates containing glycosylated side chains as alicyclic fragments were also examined. It was shown that analysis of 1H NMR spectra for the determination of the absolute configuration is more applicable in the cases when glycosides have the same substitution in the D-ring of the aglycone moiety.     

Oceanalin A, a hybrid alpha,omega-bifunctionalized sphingoid tetrahydroisoquinoline beta-glycoside from the marine sponge Oceanapia sp

[reaction: see text] The novel antifungal compound oceanalin A, an unprecedented "hybrid sphingolipid", was isolated from the marine sponge Oceanapia sp. The structure was elucidated using NMR and MS spectral analysis and chemical degradation. Oceanalin A exhibits in vitro antifungal activity against Candida glabrata with an MIC of 30 mug/mL.     

New meroterpenoids from the marine sponge Aka coralliphaga

Three new sulfated meroterpenoids containing sesquiterpene and hydroquinone moieties, namely siphonodictyal A sulfate (1), akadisulfate A (2) and akadisulfate B (3), along with the known siphonodictyal B3 and bis(sulfato)-cyclosiphonodictyol A were isolated from the sponge Aka coralliphaga. Their structures were elucidated on the basis of spectroscopic data. Akadisulfate B and siphonodictyal B3 showed a radical-scavenging activity comparable with that of the known lipophylic antioxidant BHT.     

Three new aaptamines from the marine sponge Aaptos sp. and their proapoptotic properties

Three new aaptamine-type alkaloids, 2,3-dihydro-2,3-dioxoaaptamine (1), 6-(N-morpholinyl)-4,5-dihydro-5-oxo-demethyl(oxy)aaptamine (2) and 3-(methylamino)demethyl(oxy)aaptamine (3), along with known aaptamines were isolated from the sponge Aaptos sp. Their structures were determined on the basis of detailed analysis of their 1D and 2D NMR spectroscopic and mass spectral data. The isolated compounds induced apoptosis in human leukemia THP-1 cells.