A new coumarin from Wikstroemia indica （L.） C. A. Mey

A new coumadn was obtained from the stems and roots of Wikstroemia indica (L.) C.A.Mey.Its structure was elucidated as methyl 3-(2-hydroxy-4-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yloxy) phenyl) propanoate by spectroscopic methods.     

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety ofα,β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl_3 in aqueous media to afford the corresponding products in good to excellent yields.     

Synthesis and biological evaluation of novel steroid-linked nitrogen mustards

Two novel steroid-linked nitrogen mustard conjugates 1a and 1b were synthesized by using estrogenic acid 4 coupled with aniline mustard 8 and phenol mustard 13 in an esterification or amidation procedure. Preliminary cytotoxic screening on cancer cell lines in vitro showed that, the steroid-ester linked nitrogen mustard conjugate la exhibited obvious increasing of activities.     

Oxyphyllones A and B,novel sesquiterpenes with an unusual 4,5-secoeudesmane skeleton from Alpinia oxyphylla

Two novel 4,5-secoeudesmane sesquiterpenoids,oxyphyllones A(1) and B(2) were isolated from the fruits of Alpinia oxyphylla.Their structures were established by spectroscopic methods including 1D and 2D NMR spectra.These two compounds are the first example of naturally occurring sesquiterpenoids with a 4,5-secoeudesmane skeleton in the family of Zingiberaceae and oxyphyllone A(1) is the first 4,5-secoeudesmane type of 13-norsesquiterpenoid.Compounds 1 and 2 exhibited no cytotoxicities against three cancer...     

Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry

The inclusion interaction between berberine hydrochloride(BRH) and cucurbit[7](CB[7]) has been studied by spectro-fluorimetry. The result showed that CB[7]interaction with BRH to form a stable inclusion complex with an association constant of 9.57×10~4 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of B RH in inclusion complex,a spetrofluorimetric method with high sens...     

Cardiac T2 measurements in patients with iron overload: a comparison of imaging parameters and analysis techniques

Measurement of cardiac T2 has emerged as an important tool to noninvasively quantify cardiac iron concentration in order to detect preclinical evidence of toxic levels and titrate chelation therapy. However, there exists variation among practitioners in cardiac T2 measurement methods. This study examines the impact of different imaging parameters and data analysis techniques on the calculated cardiac R2 (1/T2) in patients at risk for cardiac siderosis. The study group consisted of 36 patients with thalassemia syndromes who had undergone clinical magnetic resonance imaging assessment of cardiac siderosis using a standardized protocol and who were selected to yield a broad range of cardiac R2 values. Cardiac R2 measurements were performed on a 1.5-T scanner using an electrocardiogram-gated, segmented, multiecho gradient echo sequence obtained in a single breath-hold. R2 was calculated from the signal intensity versus echo time data in the ventricular septum on a single midventricular short-axis slice. There was good agreement between R2 measured with a blood suppression prepulse (black blood technique) and without (mean difference 6.0 ± 10.7 Hz). The black blood technique had superior within-study reproducibility (R2 mean difference 1.6 ± 8.6 Hz versus 2.7 ± 14.6 Hz) and better interobserver agreement (R2 mean difference 3.4 ± 8.2 Hz versus 8.3 ± 16.5 Hz). With the same minimum echo time, the use of small (1.0 ms) versus large (2.2 ms) echo spacing had minimal impact on cardiac R2 (mean difference 0.3 ± 8.7 Hz). The application of a region-of-interest-based versus a pixel-based data analysis also had little effect on cardiac R2 calculation (mean difference 8.4 ± 6.9 Hz). With black blood images, fitting the signal curve to a monoexponential decay or to a monoexponential decay with a constant offset yielded similar R2 values (mean difference 3.4 ± 8.1 Hz). In conclusion, the addition of a blood suppression prepulse for cardiac R2 measurement yields similar R2 values and improves reproducibility and interobserver agreement. The findings regarding other variations may be helpful in establishing a broadly accepted imaging and analysis technique for cardiac R2 calculation.     

Adaptive numerical algorithms in space weather modeling

Space weather describes the various processes in the Sun–Earth system that present danger to human health and technology. The goal of space weather forecasting is to provide an opportunity to mitigate these negative effects. Physics-based space weather modeling is characterized by disparate temporal and spatial scales as well as by different relevant physics in different domains. A multi-physics system can be modeled by a software framework comprising several components. Each component corresponds to a physics domain, and each component is represented by one or more numerical models. The publicly available Space Weather Modeling Framework (SWMF) can execute and couple together several components distributed over a parallel machine in a flexible and efficient manner. The framework also allows resolving disparate spatial and temporal scales with independent spatial and temporal discretizations in the various models.Several of the computationally most expensive domains of the framework are modeled by the Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code that can solve various forms of the magnetohydrodynamic (MHD) equations, including Hall, semi-relativistic, multi-species and multi-fluid MHD, anisotropic pressure, radiative transport and heat conduction. Modeling disparate scales within BATS-R-US is achieved by a block-adaptive mesh both in Cartesian and generalized coordinates. Most recently we have created a new core for BATS-R-US: the Block-Adaptive Tree Library (BATL) that provides a general toolkit for creating, load balancing and message passing in a 1, 2 or 3 dimensional block-adaptive grid. We describe the algorithms of BATL and demonstrate its efficiency and scaling properties for various problems.BATS-R-US uses several time-integration schemes to address multiple time-scales: explicit time stepping with fixed or local time steps, partially steady-state evolution, point-implicit, semi-implicit, explicit/implicit, and fully implicit numerical schemes. Depending on the application, we find that different time stepping methods are optimal. Several of the time integration schemes exploit the block-based granularity of the grid structure.The framework and the adaptive algorithms enable physics-based space weather modeling and even short-term forecasting.     

Studies of silicon–nitrogen ring formation from tetrachlorodisilanes

The addition of n equiv of MesNHLi (n = 1, 2, 3, 4) and m equiv of 12-crown-4 (m = 0.1, 1, 2, 3, 4) to (RsiCl₂)₂ (R = Mesityl; t-Butyl) in THF at −78°C resulted in higher yields and improved selectivities of cyclodisilazanes and azadisilacyclopropanes. The reaction of 2 equiv of MesNDLi with (MesSiCl₂)₂ ( I ) yielded cis-2-chloro-1,2,3,4-tetramestylcyclodisilazane ( 2a ) with 95% Si H deuteration. 2a was quantitatively chlorinated with retention of stereochemistry by N-chlorosuccinimide to give the cis dichlorocyclodisilazane ( 3 ). Variable-temperature ¹H NMR studies from −70°C to 25°C in d₈-THF were performed on 1 , 2a , 2b , and 3 . 1 exhibited little variation throughout the temperature range, whereas 2a , 2b , and 3 showed several rotational isomers. trans-2,3-Bis(mesitylamino)-1,2,3-trimesitylazadisilacyclopropane was shown to isomerize to the cis isomer in the presence of n-BuLi or MesNHLi. The molecular structures of 1 and 3 were determined by X-ray crystallography. Compound 1 crystallized in the monoclinic space group P2₁/c, with cell parameters a = 16.599(2) Å b = 14.633(2) Å, c = 16.945(2) Å, β = 92.044(13)°, V = 4113.1(8) ų, Z = 8, d (calcd) = 1.409 g/cm³, and R = 6.88%. Compound 3 ° C₆H₆ crystallized in the orthorhombic space group Pbca, with cell parameters a = 17.906(4) Å, b = 13.918(3) Å, c = 31.700(6) Å, V = 7900(3) ų, Z = 8, d (calcd) = 1.194 g/cm³, and R = 7.52%.