Thallium (TI) is a very toxic heavy metal. As a part of ongoing investigations, the mobility, sources and fate of TI were investigated for sediments from a watershed in the northern part of the Pearl River, South Chin...
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Thallium (TI) is a very toxic heavy metal. As a part of ongoing investigations, the mobility, sources and fate of TI were investigated for sediments from a watershed in the northern part of the Pearl River, South China, whose catchment has been seriously impacted by large-scale Pb Zn smelting activities onshore. A wide dispersion of severe TI contamination was observed throughout the depth profiles. A modified IRMM (Institute for Reference Materials and Measurements, Europe) sequential extraction procedure of a selected depth profile uncovered an exceptionally high enrichment of TI in geochemically-mobile fractions (i.e., weak-acid-exchangeable, reducible and oxidizable fractions), on average 5.94 +/- 2.19 mg/kg (74.6% +/- 5.1% of the total TI content) not only in the surface sediments but also in deep sediments. The proximal quantitative source apportionment using Pb isotopic fingerprinting technique indicated that a majority (80%-90%) of TI contamination along the depth profiles is anthropogenically derived from the Pb Zn smelting wastes. The results highlight the pivotal role of smelting activities in discharging huge amounts of geochemically-mobile TI to the sediments down to approximately 1 m in length, which is quantitatively evidenced by Pb isotopic tracing technique. Lead isotopes combined with distribution of TI and Pb contents identified a potential marker for a point source from the Pb Zn smelter in the river catchment, which also provides a theoretical framework for source apportionment of metal contamination in a larger river/marine system and in other sulfide mining/smelting areas likewise. (C) 2018 Elsevier Ltd. All rights reserved.
Norovirus (NoV), a major food-borne virus, causes non-bacterial acute gastroenteritis in humans. Berries are generally harvested from low-growing bushes by hand and are minimally processed before being sold to consume...
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Norovirus (NoV), a major food-borne virus, causes non-bacterial acute gastroenteritis in humans. Berries are generally harvested from low-growing bushes by hand and are minimally processed before being sold to consumers. Therefore, the consumption of berries has been linked to numerous food-borne gastroenteritis outbreaks caused by NoV in many countries. We performed a survey of NoV contamination in commercial fresh/frozen berry fruits collected from 2016 to 2017 in the Heilongjiang Province, the main berry-producing area in China, using a TaqMan-based real-time reverse transcription-PCR assay. Among 900 frozen and 900 fresh domestic retail berry samples, the prevalence of NoV was 9% (81/900) and 12.11% (109/900), including 35.80% (29/81) and 29.36% (32/109) of genotype GI alone, 54.32% (44/81) and 60.55% (66/109) of GII alone, and 9.88% (8/81) and 10.09% (11/109) of both GI and GII, respectively. No NoV was detected among the 677 frozen berry samples for export. Thus, the occurrence of NoV contamination was significantly higher in domestic berries than in exported berries and higher in fresh berries than in frozen berries. This study highlights the need for further risk surveillance for NoV contamination in berries produced in the Heilongjiang Province and recommends region-extended monitoring of retail berries for NoV.
Although the Transformer model has outperformed traditional sequence-to-sequence model in a variety of natural language processing (NLP) tasks, it still suffers from semantic irrelevance and repetition for abstractive...
Although the Transformer model has outperformed traditional sequence-to-sequence model in a variety of natural language processing (NLP) tasks, it still suffers from semantic irrelevance and repetition for abstractive text summarization. The main reason is that the long text to be summarized is usually composed of multi-sentences and has much redundant information. To tackle this problem, we propose a selective and coverage multi-head attention framework based on the original Transformer. It contains a Convolutional Neural Network (CNN) selective gate, which combines n-gram features with whole semantic representation to obtain core information from the long input sentence. Besides, we use a coverage mechanism in the multi-head attention to keep track of the words which have been summarized. The evaluations on Chinese and English text summarization datasets both demonstrate that the proposed selective and coverage multi-head attention model outperforms the baseline models by 4.6 and 0.3 ROUGE-2 points respectively. And the analysis shows that the proposed model generates the summary with higher quality and less repetition.
Detonation Nanodiamonds (DNDs) are known to have sp(3) core, sp(2) shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing...
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Detonation Nanodiamonds (DNDs) are known to have sp(3) core, sp(2) shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp(3) content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness. Published by AIP Publishing.
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