Heavy metal characteristics of vegetables and their soils in Foshan City

Investigation of the vegetable garden soil in Foshan City 4 kinds of heavy metals Cu, Pb, Zn and Cd in the total and different forms of content, while also investigating a variety of vegetables and edible part of the Cd content. The results show that, Foshan City, the heavy metal content in vegetable field exceed the national and the background value of Guangdong Province, the pollution index to the maximum Cd, Cu, followed by, Cd elements of the highest validity coefficients. Foshan City, edible part of vegetables found excessive Cd, leafy soil Cd content and Cd the full amount of exchangeable manganese content and the amount of state showed a significant positive correlation. The state of heavy metal content of vegetable soil in Foshan city was investigated. The total content and available content of 4 heavy metal elements (Cd, Pb, Zn, and Cu) were analyzed and measured. The result indicated that the heavy metal content of vegetable soil in Foshan city was greater than the average in other areas throughout Guangdong Province or even the whole country. The valid coefficient of Cd element was the greatest. The content of Cd in vegetables was greater than the state vegetable sanitation standard. In different kinds of vegetables, the content of Cd in leaf-vegetable had very significant correlation with the content of different sort Cd in soil. which indicated that the content of Cd in vegetables was affected by the content of Cd in soil

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Absorbable Organic Halide (AOX) Reduction in Elemental Chlorine-Free (ECF) Bleaching of Bagasse Pulp from the Addition of Sodium Sulphide

A laboratory investigation was developed to confirm and to quantify the reductions in absorbable organic halide (AOX) discharge when sodium sulphide was added during elemental chlorine-free (ECF) bleaching of sugarcane bagasse pulp. After the chlorine dioxide bleaching stage, the pulp was sent directly into the extraction stage without washing. FTIR was employed to determine the breakage of chemical bonds in the pulp, and GC-MS was used to measure the composition of the bleaching effluent. The addition of sodium sulphide caused a reduction in AOX of up to 46.7%. The AOX reduction reached this maximum when the sodium sulphide was added 30 min after the start of the extraction stage and when the pH was higher than 12. FTIR spectroscopy showed that the phenolic lignin of the pulp was degraded by the sodium sulphide and that the syringyl lignin and C-O-C, C=O structure of the pulp holocellulose of the pulp was preserved during the extraction stage. The GC-MS showed that the chlorobenzene and chlorophenol contents decreased noticeably after the addition of sodium sulphide

Structural transformation of lignin from eucalyptus during chlorine dioxide bleaching

Enzymatic/mild acidolysis lignin was extracted from both unbleached and bleached eucalyptus pulp, and the difference in lignin structures was analyzed by nuclear magnetic resonance spectroscopy. The unbleached pulp lignin was chlorinated with chlorine dioxide, and the mechanism of adsorbable organic halide (AOX) formation was investigated. Chlorinated reaction products were detected by gas chromatography-mass spectrometry. There is a possibility of producing three different chlorobenzene or chlorophenol products from S/S lignin dimers that are connected with β-O-4 bonds. Based on quantum chemistry theory, three reaction pathways were investigated using molecular simulation techniques. The results showed that pathway 1 possessed the lowest reaction activation energy, which made it the most favored thermodynamically. The β-O-4 bond of the lignin dimer was cleaved. Following that scission, 2-chloro-3,5-dimethoxy-methyl benzene was the most likely product to be generated from the chlorination reaction of the syringyl unit. These results provide theoretical guidance for further reduction of AOX in chlorine dioxide bleaching.</jats:p