We studied Cd, Cr, As, Ni, Mn, Pb, and Hg in three agricultural areas of Hunan province and determined the potential non-carcinogenic and carcinogenic risks for residents. Soil and brown rice samples from Shimen, Fenghuang, and Xiangtan counties were analyzed by atomic absorption spectroscopy. Soil levels of Cd and Hg were greatest, followed by As and Ni. The mean concentrations of heavy metals in brown rice were Cd 0.325, Cr 0.109, As 0.344, Ni 0.610, Mn 9.03, Pb 0.023, and Hg 0.071 mg/kg, respectively. Cd and Hg had greater transfer ability from soil to rice than the other elements. Daily intake of heavy metals through brown rice consumption were estimated to be Cd 2.30, Cr 0.775, As 2.45, Ni 4.32, Pb 0.162, Mn 64.6 and Hg 0.503 µg/(kg·day), respectively. Cd, Hg and As Hazard Quotient values were greater than 1 and Cd, Cr, As and Ni Cancer Risk values were all greater than 10−4. The total non-carcinogenic risk factor was 14.6 and the total carcinogenic risk factor was 0.0423. Long-term exposure to heavy metals through brown rice consumption poses both potential non-carcinogenic and carcinogenic health risks to the local residents.

In past decades, terahertz radiation, which locates between microwave and far‐infrared light in the electromagnetic spectrum, has attracted more and more attention. Various passive and active components such as absorbers, filters, polarizers, and focusing lenses have been developed for manipulating terahertz radiation. With the further evolution of metamaterials and metasurfaces, unprecedented freedom is gained for flexibly controlling terahertz waves, including focusing, deflection, beam steering, polarization conversion, and generation of orbit angular momentum. Among them, terahertz beam steering has become the focus of considerable interest owing to its significance for wireless communication, high‐resolution imaging, and radar applications. In this paper, first the conventional terahertz beam steering technologies are reviewed, including mechanical scanning, phased array, frequency scanning antennas, and multibeam switching technology. Then, the reconfigurable metasurface routes based on semiconductor active components, phase transition materials, electrically tunable materials, and micro‐electromechanical technology are summarized and the respective performances for terahertz beam steering are discussed. Moreover, programmable metasurfaces with digitalized description of metasurfaces and real‐time manipulations of radiation patterns are also illustrated in detail. Finally, a summary of the present terahertz beam steering technologies is provided and an outlook for the future is discussed.

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Poor wound healing affects millions of people worldwide each year and needs better therapeutic strategies. Synechococcus elongatus PCC 7942 is a naturally occurring photoautotrophic cyanobacterium that can be easily obtained and large-scale expanded. Here, we investigated the therapeutic efficacy of this cyanobacterium in a mouse model of acute burn injury and whether the secretion of extracellular vesicles (EVs), important mediators of cell paracrine activity, is a key mechanism of the cyanobacterium-induced regulation of wound healing. Methods : The effects of Synechococcus elongatus PCC 7942 on burn wound healing in mice under light or dark conditions were evaluated by measuring wound closure rates, histological and immunofluorescence analyses. A series of assays in vivo and in vitro were conducted to assess the impact of the cyanobacterium on angiogenesis. GW4869 was used to interfere with the secretion of EVs by the cyanobacterium and the abilities of the GW4869-pretreated and untreated Synechococcus elongatus PCC 7942 to regulate endothelial angiogenesis were compared. The direct effects of the cyanobacterium-derived EVs ( S. elongatus -EVs) on angiogenesis, wound healing and expressions of a class of pro-inflammatory factors that have regulatory roles in wound healing were also examined. Results : Synechococcus elongatus PCC 7942 treatment under light and dark conditions both significantly promoted angiogenesis and burn wound repair in mice. In vitro , the cyanobacterium enhanced angiogenic activities of endothelial cells, but the effects were markedly blocked by GW4869 pretreatment. S. elongatus -EVs were capable of augmenting endothelial angiogenesis in vitro , and stimulating new blood vessel formation and burn wound healing in mice. The expression of interleukin 6 (IL-6), which has an essential role in angiogenesis during skin wound repair, was induced in wound tissues and wound healing-related cells by S. elongatus -EVs and Synechococcus elongatus PCC 7942. Conclusion : Synechococcus elongatus PCC 7942 has the potential as a promising strategy for therapeutic angiogenesis and wound healing primarily by the delivery of functional EVs, not by its photosynthetic activity. The promotion of IL-6 expression may be a mechanism of the cyanobacterium and its EVs-induced pro-angiogenic and -wound healing effects.

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Microcystins (MCs) classified as hepatotoxic and carcinogenic are the most commonly reported cyanobacterial toxins found in the environment. Microcystis sp. possessing a series of MC synthesis genes (mcyA-mcyJ) are well documented for their excessive abundance, numerous bloom occurrences and MC producing capacity. About 246 variants of MC which exert severe animal and human health hazards through the inhibition of protein phosphatases (PP1 and PP2A) have been characterized. To minimize and prevent MC health consequences, the World Health Organization proposed 1 µg/L MC guidelines for safe drinking water quality. Further the utilization of bacteria that represent a promising biological treatment approach to degrade and remove MC from water bodies without harming the environment has gained global attention. Thus the present review described toxic effects and bacterial degradation of MCs.

Microcystin-LR (MC-LR) and microcystin-RR (MC-RR) are the two most common microcystins (MCs) present in fresh water posing a direct threat to public health because of their hepatotoxicity. A novel MC-degrading bacterium designated MC-LTH1 capable of degrading MC-LR and -RR was isolated, and the degradation rates and mechanisms of MC-LR and -RR for this bacterium were investigated. The bacterium was identified as Bordetella sp. and shown to possess a homologous mlrA gene responsible for degrading MCs. To the best of our knowledge, this is the first report of mlrA gene detection in Bordetella species. MC-LR and -RR were completely degraded separately at rates of 0.31 mg/(L h) and 0.17 mg/(L h). However, the degradation rates of MC-LR and -RR decreased surprisingly to 0.27 mg/(L h) and 0.12 mg/(L h), respectively, when both of them were simultaneously present. Degradation products were identified by high performance liquid chromatography coupled with time-of-flight mass spectrometry. Adda (m/z 332.2215, C20H29NO3) commonly known as a final product of MC degradation by isolated bacteria was detected as an intermediate in this study. Linearized MC-LR (m/z 1013.5638, C49H76N10O13), linearized MC-RR (m/z 1056.4970, C49H77N13O13), and tetrapeptide (m/z 615.3394, C32H46N4O8) were also detected as intermediates. These results indicate that the bacterial strain MC-LTH1 is quite efficient for the detoxification of MC-LR and MC-RR, and possesses significant bioremediation potential.