Chemical Constituents of Hedysarum gmelinii

To study the chemical constituents of Hedysarum gmelinii. Methods Theconstituents were separated and purified by different methods of chromatography, and theirstructures were elucidated by DR, MS and NMR. Results Eight compounds were isolated from Hedysarumgmelinii, including three triteipenoids, two flavonoids and two other compounds. Their structureswere identified as squasapogenol (1), soyasapogenol (2), lupeol (3), 3, 9-dihydroxy coumestan (4),3-hydroxy-9-me-thoxy pterocarpan (5), β-sitosterol (6), palmatic acid (7), and hexadecanoic acid 2,3-dihydroxypropyl ester (8). Conclusion All the compounds have been isolated from this plant forthe first time. Compounds 1 — 4 and 8 were obtained from this genus for the first time. The NMRdata of 1 are reported for the first time.

The New Flavonoids from Polygonum sphaerostachyum(Polygonaceae)

Two novel flavone glycosides, 3′_hydroxy_5,4′_dimethoxy_6,7_methylenedioxyflavone_3_O_[β_D_xylopyranosyl(1→6)]_β_D_glucopyranoside (1) and 5,4′_dimethoxy_3′_isopropenylacetyl_6,7_methylenedioxyflavone_3_O_[β_D_xylopyranoxyl(1→6)]_β_D_glucopyranoside (2), were isolated from Polygonum sphaerostachyum Meisn., and their structures were deduced by spectral and chemical methods. This is the first report on the isolation of flavone glycosides from P. sphaerostachyum.

An Elliptical Wind Field Model of Typhoons

An elliptical wind field model of typhoons is put forward based on the characteristics of the typhoon wind fields occurring in the Yellow Sea and Bohai Sea. By contrasting it with the circular typhoon wind field model, it is found that the elliptical model can adequately represent the real wind field and trace the process of a typhoon storm surge. The numerically simulated results of storm surges by using the elliptical model are in good agreement with the observations and markedly better than those by using the circular model.

Mechanism of formation of sliding ground fissure in loess hilly areas caused by underground mining

Based on a shallow-buried coal seam covered with thick loose layers in hilly loess areas of western China,we developed a mechanical model for a mining slope with slope stability analysis, and studied the mechanism of formation and development of a sliding ground fissure by the circular sliding slice method.Moreover, we established a prediction model of a sliding fissure based on a mechanical mechanism,and verified its reliability on face 52,304, an engineering example, situated at Daliuta coal mine of Shendong mining area in western China. The results show that the stress state of a mining slope is changed by its gravity and additional stress from the shallow-buried coal seam and gully terrain. The mining slope is found to be most unstable when the ratio of the down-sliding to anti-sliding force is the maximum, causing local fractures and sliding fissures. The predicted angles for the sliding fissure of face 52,304 on both sides of the slope are found to be 64.2° and 82.4°, which are in agreement with the experimental data.