The transfer and fate of Pb from sewage sludge amended soil in a multi-trophic food chain: a comparison with the labile elements Cd and Zn

The contamination of agroecosystems due to the presence of trace elements in commonly used agricultural materials is a serious issue. The most contaminated material is usually sewage sludge, and the sustainable use of this material within agriculture is a major concern. This study addresses a key issue in this respect, the fate of trace metals applied to soil in food chains. The work particularly addresses the transfer of Pb, which is an understudied element in this respect, and compares the transfer of Pb with two of the most labile metals, Cd and Zn. The transfer of these elements was determined from sludge-amended soils in a food chain consisting of Indian mustard (Brassica juncea), the mustard aphid (Lipaphis erysimi) and a predatory beetle (Coccinella septempunctata). The soil was amended with sludge at rates of 0, 5, 10 and 20 % (w/w). Results showed that Cd was readily transferred through the food chain until the predator trophic level. Zn was the most readily transferred element in the lower trophic levels, but transfer to aphids was effectively restricted by the plant regulating shoot concentration. Pb had the lowest level of transfer from soil to shoot and exhibited particular retention in the roots. Nevertheless, Pb concentrations were significantly increased by sludge amendment in aphids, and Pb was increasingly transferred to ladybirds as levels increased. The potential for Pb to cause secondary toxicity to organisms in higher trophic levels may have therefore been underestimated

SIRT1 as a therapeutic target in inflammaging of the pulmonary disease

OBJECTIVE: Chronic inflammation and cellular senescence are intertwined in the pathogenesis of premature aging, which is considered as an important contributing factor in driving chronic obstructive pulmonary disease (COPD). SIRT1, a NAD(+)-dependent protein/histone deacetylase, regulates inflammation, senescence/aging, stress resistance, and DNA damage repair via deacetylating intracellular signaling molecules and chromatin histones. The present review describes the mechanism and regulation of SIRT1 by environmental agents/oxidants/reactive aldehydes and pro-inflammatory stimuli in lung inflammation and aging. The role of dietary polyphenols in regulation of SIRT1 in inflammaging is also discussed. METHODS: Analysis of current research findings on the mechanism of inflammation and senescence/aging (i.e., inflammaging) and their regulation by SIRT1 in premature aging of the lung. RESULTS: COPD is a disease of lung inflammaging, which is associated with the DNA damage response, transcription activation and chromatin modifications. SIRT1 regulates inflammaging via regulating FOXO3, p53, NF-κB, histones and various proteins involved in DNA damage and repair. Polyphenols and its analogs have been shown to activate SIRT1 although they have anti-inflammatory and antioxidant properties. CONCLUSIONS: Targeting lung inflammation and cellular senescence as well as premature lung aging using pharmacological SIRT1 activators or polyphenols would be a promising therapeutic intervention for COPD/emphysema

ITO-free carrier-selective contact for crystalline silicon solar cells

In this study, an indium tin oxide (ITO)-free carrier-selective contact (CSC) for crystalline silicon (c-Si) solar cells with a micro-grid metal electrode is reported. The ITO layer is crucial for collecting the carriers separated at the junction between CSC and n-Si because of the relatively low conductivity of CSC. However, previous research investigated the formation of ITO films via sputter deposition, which can lead to performance degradation of solar cells due to the parasitic absorption of the ITO layer and plasma damage at the CSC/Si junction during sputtering. Moreover, the use of ITO is hindered because of the rare indium metal. Herein, we investigate the carrier transport mechanism at the MoOx/n-Si junction to understand the reason for the poor performance of ITO-free devices. A majority of the carriers are limited because of a highly resistive carrier path, with a sheet resistance of 16 k Omega sq(-1) during carrier transport, leading to the severe degradation of fill factor (FF) and short-circuit current (J(sc)). To minimize the power loss during carrier transport, a micro-grid metal electrode that can effectively collect carriers separated at the MoOx/n-Si junction is applied. With this micro-grid electrode, the electrical losses of ITO-free solar cells can be minimized despite the highly resistive path of the MoOx/n-Si junction. Hence, the best device exhibits a power conversion efficiency of up to 17.0% without the ITO layer