Dust is a crucial component of galaxies in modifying the observed properties of galaxies. Previous studies have suggested that dust reddening in star-forming galaxies is correlated with star formation rate (SFR), luminosity, gas-phase metallicity (Z), stellar mass (M*) and inclination. In this work we investigate the fundamental relations between dust reddening and physical properties of galaxies, and obtain a well-defined empirical recipe for dust reddening. The empirical formulae can be incorporated into semi-analytical models of galaxy formation and evolution to estimate the dust reddening and facilitate comparison with observations.

The Sinian and Cambrian systems within the Yangtze stratigraphic province represent continuous deposits, and the strata above and below the Sinian–Cambrian boundary are rich in fossils. From all the relevant boundary sections, the Meishucun section in Jinning County, Yunnan Province serves as the stratotype section for the Sinian–Cambrian boundary and is the Chinese candidate for the global stratotype section and point for the Precambrian–Cambrian boundary. The present paper, with the various charts and tables, elaborates on several typical Sinian–Cambrian boundary sections and the distribution of fossils in them.

In accordance with the characteristics of biological evolution, three biotas can be recognized for the period from the Late Sinian to the Early Cambrian. The first biota appeared in the Late Sinian, characterized by the presence of the soft-bodied metazoans; the second biota occurred during the Meishucun Stage of the early Cambrian, and is characterized by the appearance and prevalence of small shelly fossils from many different phyla; and the third biota came into existence during the Qiongzhusi Stage of the Early Cambrian; it is characterized by the first appearance and prevalence of trilobites.

The Meishucun Stage of the Lower Cambrian can be divided into three fossil zones. The Sinian–Cambrian boundary is placed at the base of the first Anabarites–Circotheca–Protohertzina zone. According to isotopic dating by the Rb–Sr whole-rock isochron technique, the age of the Sinian–Cambrian boundary is inferred to be 610±10 Ma.

According to photoionization calculations, the broad emission-line (BEL) spectrum depends not only on the physical conditions of line-emitting gas, but also on the spectral shape of incident ionizing continuum, especially from the UV to X-ray. Analysis of emission-line spectra and their correlations with the continuum, therefore, provide a way of probing the anisotropy of ionizing continuum on the BLR scale, which is predicted by current models. Previous works have concentrated on explaining the Baldwin effect, an inverse correlation between equivalent width and continuum luminosity. In this contribution, we present the results of an analysis of 75 AGNs which have well-determined soft X-ray spectral parameters from ROSAT and UV line and continuum measurements.