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160. Meta analysis of heavy metal and pesticide pollution status of nine medicinal and edible substances

Author

BAO Huihui, JI Xiaoning, WU Nan, TANG Yu, LI Minglu, LI Qi, CAO Pei, ZHANG Lei, and LI Jianwen

Subjects
medicinal and edible substances, heavy metals, pesticides, meta-analysis, Food processing and manufacture, TP368-456, Nutrition. Foods and food supply, TX341-641
Abstract

ObjectiveTo evaluate the heavy metal and pesticide pollution status of nine medicinal and edible substances， including Eucommia ulmoides leaves， Codonopsis pilosula， Cistanche deserticola， Dendrobium candidum， Astragalus membranaceus， Panax quinquefolium， Gastrodia elata， Ganoderma lucidum， and Corni Fructus.MethodsPubMed， China National Knowledge Network （CNKI）， VIP， and Wanfang databases were searched to obtain research literature published from 2000 to 2022 on heavy metals， pesticides， and environmental pollutants in nine medicinal and edible substances. The literature was screened according to the inclusion and exclusion criteria， and the included studies were analyzed and pooled into estimates using meta-analysis.ResultsA total of 106 studies encompassing seven heavy metals， including lead （Pb）， cadmium （Cd）， mercury （Hg）， arsenic （As）， chromium （Cr）， copper （Cu）， and nickel （Ni）， and 42 pesticides， including organochlorine， pyrethroid， and organophosphorus， of nine types of medicinal and edible substances used as food collected from 23 provinces （municipalities） were comprehensively analyzed. The average heavy metal content in the medicinal and edible substances used as food was 0.22 mg/kg （95%CI： 0.13~0.39）， and the average heavy metal content of Eucommia ulmoides leaves was the highest （2.80 mg/kg， 95%CI： 0.75~10.37）， followed by Dendrobium candidum with an average value of 0.30 mg/kg （95%CI： 0.18~0.49）. The average value of heavy metals in the other medicinal and edible substances was lower than 0.30 mg/kg. Among the seven heavy metals analyzed， the Cu exhibited the highest content， followed by Cd and Pb. Subgroup analysis showed that the contents of the seven heavy metals in medicinal and edible substances collected from different locations had high heterogeneity （P

Published
2023
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186. Thermoelectric and stress distributions around a smooth cavity in thermoelectric material

Author

Lee, Zhaohang, Tang, Yu, and Zou, Wennan

Subjects
Physics - Applied Physics
Abstract

Thermoelectric materials have attracted more and more attention since they are friendly to the environment and have potentials for sustainable and renewable energy applications. As typically brittle semiconductors with low mechanical strength and always subjected to defects and damages, to clarify the stress concentration is very important in the design and implement of thermoelectric devices. The two-dimensional thermoelectric coupling problem due to a cavity embedded in an infinite isotropic homogeneous thermoelectric material, subjected to uniform electric current density or uniform energy flux, is studied, where the shape of the cavity is characterized by the Laurent polynomial, and the electric insulated and adiabatic boundary around the cavity are considered. The explicit analytic solutions of Kolosov-Muskhelishvili (K-M) potentials and rigid-body translation are carried out through a novel tactic. Comparing with the reported results, the new obtained are completely exact and possess a finite form. Some results of three typical cavities are presented to analyze the electric current densities (energy fluxes) and stresses around the tips. The main conclusions include: the distribution of thermoelectric field and stress at the tip obviously depends on the curvature of the contour and loading directions; for triangle and square with symmetrical tips, the maximum thermoelectric and stress concentration reach the maximum or minimum when the loading direction is parallel to or perpendicular to the symmetry axis of the tip, which is distinct to the extremum characteristics of pentagram with bimodal of curvature around the tip; the maximum thermoelectric and stress concentration appear near the maximum curvature point for most load directions, but not at the maximum curvature point., Comment: 21 pages, 13 Figures

Published
2021

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