Heterostructure g-C3N4/Bi2MoO6 PVDF nanofiber composite membrane for the photodegradation of steroid hormone micropollutants.

Photocatalytic membrane reactors (PMRs) are a promising technology for micropollutant removal. Sunlight utilization and catalyst surface sites limit photodegradation. A poly(vinylidene fluoride) (PVDF) nanofiber composite membrane (NCM) with immobilized visible-light-responsive g-C3N4/Bi2MoO6 (BMCN) were developed. Photodegradation of steroid hormones with the PVDF-BMCN NCM was investigated with varying catalyst properties, operating conditions, and relevant solution chemistry under solar irradiation. Increasing CN ratio (0-65 %) enhanced estradiol (E2) degradation from 20 ± 10 to 75 ± 7 % due to improved sunlight utilization and photon lifetime. PVDF nanofibers reduced self-aggregation of catalysts. Hydraulic residence time and light intensity enhanced the photodegradation. With the increasing pH value, the E2 removal decreased from 84 ± 4 to 67 ± 7 % owing to electrical repulsion and thus reduced adsorption between catalysts and E2. A removal of 96 % can be attained at environmentally relevant feed concentration (100 ng.L-1) with a flux of 60 L.m-2.h-1, irradiance of 100 mW.cm-2, and 1 mg.cm-2 BMCN65 loading. This confirmed that heterojunction photocatalysts can enhance micropollutants degradation in PMRs.

The levels of male gametic mitochondrial DNA are highly regulated in angiosperms with regard to mitochondrial inheritance.

The mechanisms that regulate mitochondrial inheritance are not yet clear, even though it is 100 years since the first description of non-Mendelian genetics. Here, we quantified the copy numbers of mitochondrial DNA (mtDNA) in the gametic cells of angiosperm species. We demonstrate that each egg cell from Arabidopsis thaliana, Antirrhinum majus, and Nicotiana tabacum possesses 59.0, 42.7, and 73.0 copies of mtDNA on average, respectively. These values are equivalent to those in Arabidopsis mesophyll cells, at 61.7 copies per cell. On the other hand, sperm or generative cells from Arabidopsis, A. majus, and N. tabacum possess minor amounts of mtDNA, at 0.083, 0.47, and 1 copy on average, respectively. We further reveal a 50-fold degradation of mtDNA during pollen development in A. majus. In contrast, markedly high levels of mtDNA are found in the male gametic cells of Cucumis melo and Pelargonium zonale (1296.3 and 256.7 copies, respectively). Our results provide direct evidence for mitochondrial genomic insufficiency in the eggs and somatic cells and indicate that a male gamete of an angiosperm may possess mtDNA at concentrations as high as 21-fold (C. melo) or as low as 0.1% (Arabidopsis) of the levels in somatic cells. These observations reveal the existence of a strong regulatory system for the male gametic mtDNA levels in angiosperms with regard to mitochondrial inheritance.

Segmentation and three-dimension reconstruction of Chinese digitized human cerebrum.

OBJECTIVE: A 3D digitized visible model of human cerebrum was built to provide anatomical structure for making plans of cerebral surgical operation and realizing accurate simulation of cerebrum on computer. METHODS: Transverse sectional anatomy data of the cerebrum were chosen from the first Chinese visible human (one male and one female). Semi-automated segmentation and Photoshop software were selected to segment cerebral cortex, white matter, basal nuclei, lateral ventricle, hippocampus, etc. On personal computer, the segmented structures were reconstructed in 3D with volume rendering reconstruction and surface rendering reconstruction. RESULTS: Two accurately segmented images of the main structures of cerebrum were completed. The reconstructed structures can be displayed singly, in small groups or as a whole and can be continuously rotated in 3D space at different velocities. CONCLUSION: Combining volume-rendering reconstruction with surface rendering reconstruction overcomes the defects of surface rendering reconstruction that lack of internal anatomical information, which provides a new method for 3D reconstruction. The reconstructed cerebrum and the main internal structures are realistic, which demonstrates the natural shape and exact position of the structures. It provides an accurate model for the automated segmentation algorithmic study and provides a digitized anatomical mode of cerebrum.