Abstract With the rapid development of emerging industries and industrialization in China, soil nickel contamination has become a serious concern, with food being the primary source of nickel exposure to the human body. The level of nickel contamination in food is gennerally higher in developed regions of China. Among different food categories, grains, legumes and aquatic products exhibit relatively higher nickel content and detection rates. Currently in China, the methods for studying nickel dietary exposure risk are relatively conservative, primarily employing point assessment, simple distribution and probability assessment to calculate daily exposure levels among residents and quantifying cumulative exposure risks using the hazard index method. It is found that there is still a certain risk of dietary nickel among residents with younger age groups and under extreme conditions of high consumption or high pollution. Additionally, the cancer risk among the rural population is higher than that among the urban population. This article reviews the research progress on the current status of nickel contamination in Chinese food and the assessment of dietary exposure risk for residents, based on literature from databases such as CNKI and PubMed up to 2023, aiming at providing a reference for future research into nickel exposure and risk assessment in food.

Objective To investigate the effect of volume therapy with 6％ hydroxyethyl starch (HES) 130/0.4 on mesenteric microcirculation in a rabbit model of hypovolemia.Methods Sixty-four adult male rabbits,weighing 2.0-2.3 kg,were randomly divided into 4 groups( n =16 each):control group (group C),hypovolemia group (group HM),Ringer's solution group (group RS) and 6％ HES 130/0.4 group (group HES).The animals were anesthetized with sodiun pentobarbital 3.0-3.5 mg/kg.Femoral artery,femoral vein and right internal jugular vein were cannulated for MAP monitoring,blood withdrawing and fluid adminstration.Hypovolemia was induced by withdrawing blood from femoral vein of 30％ blood volume in 30 min in groups HM,RS and HES.In group C,no blood was withdrawed.In group RS,Ringer's solution 3 times of the volume of blood withdrawn was infused,while 6％ HES 130/0.4 equal volume of blood withdrawn was infused via right internal jugular vein immediately at the end of blood withdrawing.MAP and HR were recorded and femoral artery and femoral vein blood samples were taken before blood withdrawing (T0),immediately at the end of blood withdrawing(T1 ),immediately at the end of volume therapy(T2 ) and 30 min after volume therapy(T3 ).DO2,VO2 and ERO2 were calculated.Diameter and blood flow speed of microvessel were determined.Results Compared with group C,HR was significantly increased,MAP decreased,diameter and blood flow speed of microvessel were decreased at T1～3,DO2 was increased　at T1 in group HM.Compared with group HM,MAP was significantly increased at T2,HR decreased at T2,3,DO2and VO2 were increased at T1～3,diameter of arteriole was increased at T2 whlie decreased at T3,diameter of veinule　and blood flow speed of microvessel were increased at T2,3 in group RS,MAP was significantly increased at T2,HR　was decreased whlie DO2 and VO2 were decreased,VO2,ERO2,diameter and blood flow speed of microvessel were　increased at T2,3 in group HES.Compared with group RS,DO2,VO2 and ERO2 were significantly decreased at T3　in group HES.Conclusion Volume therapy with 6％ HES 130/0.4 can improve mesenteric microcirculation,organ perfusion and oxygen metabolic in a rabbit model of hypovolemia.

BACKGROUND: Inherent modal analysis and harmonic response analysis on the human normal lumbosacral vertebraehave been reported, but there is a lack of comparative research on their modal analysis results before and after pediclescrew fixation.OBJECTIVE: To explore the dynamic characteristics of human lumbosacral vertebrae using three-dimensional finiteelement method.METHODS: Finite element model of lumbosacral vertebrae (L1-S1) before and after pedicle screw fixation was developedand validated based on CT images, and the modal analysis and harmonic response analysis were then conducted.RESULTS AND CONCLUSION: (1) Representative nodes were selected at the spinous process segments of L1, L3 andL5, and numbered as A, B, and C, respectively. (2) The maximum displacement of each node in Y and Z directions oflumbosacral vertebral model after internal fixation was significantly decreased compared with those of the normallumbosacral vertebral model, suggesting that screw fixation system plays a protective role in lumbosacral vertebrae, andreduces its amplitude under external load, thus diminishing its sensitivity to external load. (3) The lumbosacral vertebralmodal analysis can provide basis for further study on dynamic analysis, and the parameters such as natural frequency,modal shape and vibration amplitude of the lumbar spine have been determined.

In the process of natural uranium purification and conversion, low-level uranium-containing radioactive wastes will be produced. On the basis of introducing the characteristics of wastes from natural uranium purification and conversion and their treatment, we review the main strategies and good practices of minimization of wastes from natural uranium purification and conversion, analyze the main problems in minimization of wastes from natural uranium purification and conversion in China, and propose corresponding improvement measures, which provides a reference for the implementation and management of minimization of wastes from natural uranium purification and conversion.