Incorporating a D-A-D-Type Benzothiadiazole Photosensitizer into MOFs for Photocatalytic Oxidation of Phenylsulfides and Benzylamines.

Oxidation and removal of highly toxic sulfides and amines are particularly important for environmental and human security but remain challenging. Here, incorporating an excellent photosensitizer, donor-acceptor-donor (D-A-D)-type 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic (H2L), into metal-organic frameworks (MOFs) has been manifested to promote the charge separation, affording four three-dimensional (3D) MOFs (isostructural 1-Co/1-Zn with Co2/Zn2 units, and 2-Gd/2-Tb with Gd/Tb-cluster chains) as photocatalysts in the visible light-driven air-O2-mediated catalytic oxidation and removal of hazardous phenylsulfides and benzylamines. Impressively, structure-property correlation illustrated that the transition metal centers assembled in MOFs play an important role in the photocatalytic activity, and we can conclude that 1-Zn can be a robust heterogeneous catalyst possessing good light adsorption and fast charge separation in oxidation removal reactions of both benzylamines and phenylsulfides under visible light irradiation and room temperature with excellent activity/selectivity, stability, and reusability.

Multiple fluorescence response behaviors towards antibiotics and bacteria based on a highly stable Cd-MOF.

The abuse of antibiotics has triggered the rise of drug-resistance bacteria, which has seriously threatened public health globally. As a result, carrying out efficient and accurate antibiotic and bacteria identification are quite significant but challenge. Herein, an unprecedented Cd-MOF-based sensor, [CdL]n [1, H2L = 4-(2-methyl-1H-benzo[d]imidazol-1-yl) isophthalic acid] with multiple fluorescence response behaviours towards antibiotics and bacteria was developed. Single-crystal X-ray diffraction revealed that 1 is a mesomeric 2D bilayer, which is comprised of two opposite chiral mono-layers, each assembled by left-handed or right-handed helixes. More interestingly, 1 represented multiplex detection capability towards antibiotics and bacteria through two detection behaviors: toward nitro-antibiotics and chlortetracycline (CTC) via fluorescent quenching, while toward Staphylococcus albus (S. albus) via fluorescent enhancement. Remarkably, 1 showed a low limit of detection (LOD, 47 CFU/mL) accompanied with specificity in the detection of S. albus compared to other bacteria, such as Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli. In addition, the LOD could reach to ppm level for nitro-antibiotics and CTC. Moreover, the practical application of 1 was further reinforced through the detection of nitro-antibiotics and CTC, as well as S. albus in fetal calf serum and river water.

[Diversity of Zooplankton and Niche Characteristics of Keystone Species in the Weihe River Based on eDNA].

Environmental DNA(eDNA), a new tool for monitoring the biodiversity of aquatic ecosystems, is able to analyze characteristics of biodiversity from a microscopic perspective. Based on eDNA data collected from the Weihe River, diversity indexes, non-metric multidimensional scaling, cluster analysis, and correlation network analysis were employed to explore the diversity and community structure of zooplankton focusing on the niche differentiation of keystone species and environmental adaptability. The eDNA approach identified three types of zooplankton including Rotifera, Cladocera, and Copepoda, among which the dominant species was Brachionus calyciflorus. The zooplankton community shows significant differences in species composition, abundance, diversity and spatial distribution characteristics(P<0.01). The average values of the Chao1 index, ACE index, Shannon index, and Simpson index were 22.25, 22.38, 2.32, and 0.68, respectively. The downstream biodiversity is significantly higher than in the upstream area. Non-metric multidimensional scale analysis and hierarchical cluster analysis further showed that the zooplankton community structure shows distinct regional differences. The keystone species in the community have a high degree of connection with other species, with a high node degree, centrality, and modularity. The niche breadth(Bi) of the operational taxonomic units(OTUs) of the keystone species varied from 0.38 to 0.80. The medium niche species accounted for 63% of all keystone species. The average niche overlap index(Qik) was 0.72, and the degree of overlap was generally high. RDA analysis further identified that water environmental variables were closely related to changes in the zooplankton community structure and niche differentiation. For example, total nitrogen and water temperature were the main limiting factors, which play important roles in shaping the zooplankton community structure.

[Effects of invertebrate bioturbation on vertical hydraulic conductivity of streambed for a river].

Streambed hydraulic conductivity is a key factor influencing water exchange between surface water and groundwater. However, the streambed invertebrate bioturbation has a great effect on the hydraulic conductivity. In order to determine the impact of invertebrate bioturbation on streambed hydraulic conductivity, the investigation of invertebrate bioturbation and in-situ test of vertical hydraulic conductivity of streambed are simultaneously conducted at five points along the main stream of the Weihe River. Firstly, correlation between the streambed vertical hydraulic conductivity and grain size distribution is analyzed. Secondly, type and density of the invertebrate and their correlation to hydraulic conductivity are determined. Finally, the effect of invertebrate bioturbation on the streambed hydraulic conductivity is illustrated. The results show that the vertical hydraulic conductivity and biological density of invertebrate are 18.479 m x d(-1) and 139 ind x m(-2), respectively for the Caotan site, where sediment composition with a large amount of sand and gravel particles. For Meixian site, the sediment constitutes a large amount of silt and clay particles, in which the vertical hydraulic conductivity and biological density of invertebrate are 2.807 m x d(-1) and 2 742 ind x m(-2) respectively. Besides, for the low permeability of four sites (Meixian, Xianyang, Lintong and Huaxian), grain size particles are similar while the vertical hydraulic conductivity and biological density of invertebrate are significantly different from one site to another. However, for each site, the vertical hydraulic conductivity closely related to biological density of invertebrate, the Pearson correlation coefficient is 0.987. It can be concluded that both grain size particles and invertebrate bioturbation influence sediment permeability. For example, higher values of streambed hydraulic conductivity from strong permeability site mainly due to the large amount of large-size particles and that from low permeability site is the main results from higher biological density of invertebrate. Large amount of grain size particles can expand pore space and the invertebrate bioturbation can destroy clogging sediment and enhance sediment permeability.

[Macrobenthos community structure and its relationships with environmental factors in Weihe River basin, Northwest China].

In October 2011, an investigation was conducted on the macrobenthos at 45 sampling sites in the Weihe River basin of Northwest China. A total of 116 macrobenthos species were collected, of which, 91 species (78.4%) were aquatic insects, 12 species (10.3%) were mollusks, 9 species (7.8%) were annelids, and 4 species (3.4%) were crustaceans. According to the species composition and relative abundance of macrobenthos, the 45 sampling sites could be divided into three groups by using two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA). In the first group, Serratella sp., Hydropsyche sp., and Antocha sp. were the indicator species. In the second group, Tabanus sp., Alotanypus venustus, one species of Pelecorhynchidae, Liodessus sp., and Limnodrilus hoffmeistteri were the indicator species. In the third group, Ephemera nigroptera and Polypylis hemisphaerula were the indicator species. The canonical correspondence analysis (CCA) indicated that 'cobble + boulder' type substrate, current velocity, water conductivity, water depth, and water total nitrogen content had significant effects on the spatial distribution of macrobenthos in Weihe River basin.