Two new holostan-type triterpenoid oligoglycosides, named parvimosides A (1) and B (2), were isolated from the warty sea cucumber Stichopus parvimensis (syn. Parastichopus parvimensis). Their structures and total assignments of the proton and carbon signals were established on the basis of spectral evidence, mainly 1H and 13C 1D and 2D NMR spectroscopy including DEPT, COSY, TOCSY, NOESY/ROESY, ...

Eight phospholipidic classes from bovine brain cortex and soybean were prepared and purified by preparative high-performance and liquid chromatography, and their molecular species were identified by negative ion fast atom bombardment mass spectrometry using the 'surface precipitation' method. Its main advantages are: (i) clear-cut and abundant diagnostic ions for structural elucidation of the s...

Thirty three compounds were obtained from the bulbs of Urginea maritima (Liliaceae). The compounds were identified by means of fast atom bombardment mass spectrometry (FAB-MS), nuclear magnetic resonance (1H-NMR), (13C-NMR), nuclear overhauser effects (NOE) and two dimensional (2D) NMR. Ten of them were new natural compounds. Nine were bufadienolides and only one was lignan in these compounds.

Energy evaluation using fast Fourier transforms (FFTs) enables sampling billions of putative complex structures and hence revolutionized rigid protein-protein docking. However, in current methods, efficient acceleration is achieved only in either the translational or the rotational subspace. Developing an efficient and accurate docking method that expands FFT-based sampling to five rotational c...

Most state-of-the-art protein-protein docking algorithms use the Fast Fourier Transform (FFT) technique to sample the six-dimensional translational and rotational space. Scoring functions including shape complementarity, electrostatics, and desolvation are usually exploited in ranking the docking conformations. While these rigid-body docking methods provide good performance in bound docking, us...

Protein structural fluctuation, typically measured by Debye-Waller factors, or B-factors, is a manifestation of protein flexibility, which strongly correlates to protein function. The flexibility-rigidity index (FRI) is a newly proposed method for the construction of atomic rigidity functions required in the theory of continuum elasticity with atomic rigidity, which is a new multiscale formalis...

Two 11(15-->1)abeotaxanes having a tetrahydrofuran ring along the carbon atoms C-2, C-3, C-4, C-20 were identified for the first time from the needles of the Canadian yew, Taxus canadensis. The compounds could be identified as 4alpha,10beta,13alpha-triacetoxy-15-benzoyloxy-2alpha,20beta-epoxy-11(15-->1)abeotax-11-ene-5alpha,7beta,9alpha-triol (1) and 4alpha,7beta,9alpha,10beta,15-pentaacetoxy-2...

The Fast Auroral Snapshot Explorer (FAST), with its 83 inclination orbit and 4000 km apogee, is ideally suited for investigation of the high latitude perturbations to the geomagnetic field. These data can be used to determine fieldaligned currents, but here we emphasize the perturbations themselves, rather than their spatial gradient. This allows us to more readily visualize the forces applied ...

Monte Carlo and molecular dynamics simulations were done with three recent water models TIP4P/2005 (Transferable Intermolecular Potential with 4 Points/2005), TIP4P/Ice (Transferable Intermolecular Potential with 4 Points/ Ice) and TIP4Q (Transferable Intermolecular Potential with 4 charges) combined with two models for methane: an all-atom one OPLS-AA (Optimal Parametrization for the Liquid St...

Fast and accurate solutions of large-scale electromagnetics problems involving homogeneous dielectric objects are considered. Problems are formulated with the electric and magnetic current combined-field integral equation and discretized with the Rao-Wilton-Glisson functions. Solutions are performed iteratively by using the multilevel fast multipole algorithm (MLFMA). For the solution of large-...