微塑料  生菜  聚苯乙烯微球  吸收  积累  健康风险  microplastics  lettuce  polystyrene microbeads  uptake  accumulation  human health risk  Microplastic (MP, 100 nm-5 mm) may present an attributable risk to ecosystem and human health, and its pollution has become a global environmental concern. Despite a wealth of information on the accumulation of MPs in aquatic species, there is no information on the uptake and accumulation of MPs by higher plants. Terrestrial edible plants are directly exposed to MPs when agricultural soil was applied with organic manure, sewage sludge as fertilizer or plastic mulching. In this paper, the uptake of two sizes of polystyrene (PS) microbeads (0.2 and 1.0 mum) and then their distribution and migration in an edible plant lettuce were firstly investigated based on laboratory experiments. We used fluorescent markers to track PS microbeads in plant tissues and found fluorescence to be a sensitive and reliable detection method. Sections from untreated control lettuce showed no autofluorescence. When roots were treated with fluorescently labeled PS microbeads, the microbeads could be identified by its fluorescence. Our main study investigated the uptake of 0.2 mum beads, as few luminescence signals were observed in lettuce roots for 1.0 mum beads in our experiment. We observed that 0.2 mum fluorescent microbeads were extracellularly trapped in the root cap mucilage (which is a highly hydrated polysaccharide) and a dark green tip (which was typical of lettuce roots exposed to label PS beads) was usually visible to the naked eye. Confocal images revealed that the PS luminescence signals were mainly located in the vascular system and on the cell walls of the cortex tissue of the roots, indicated that the beads passed through the intercellular space via the apoplastic transport system. Once inside the central cylinder, the 0.2 mum PS beads were transferred from the roots to the stems and leaves via the vascular system following the transpiration stream. We also observed that the PS beads adhered to one another and self-assembled systematically into grape-like and (chain) string-like clusters in the intercellular space of the root and stem vascular tissue of lettuce plant. In contrast to the root and stem, PS beads were dispersed in the leaf tissue. Here, for the first time we provide evidence of the adherence, uptake, accumulation, and translocation of submicrometer MPs within an edible plant. Our findings highlight the previously underappreciated human exposure pathway to MPs through the consumption of contaminated crops and emphasize the need for new management strategies to control the release of MPs waste products into the terrestrial environment. Ultimately, the potential impacts of low range sized MPs on food safety of crop plants and human health need to be urgently considered.  

Glacial HisTories From The East Antarctic Ice Sheet (Eais) Provide Keys To UnderstAndIng Correlations Between The Eats And Global Climate. They Are Especially Helpful In The Assessment Of Global Sea Level Change  And As a Means Of Quantifying The Magnitude Of pAst Glacial Activity And The RAte At Which Ice Responded To climAte Change. Given The Significance Of Eais Glacial hisTories  It Is Imperative That More Glacial Chronologic Data For thIs Region Be Obtained  Especially For The Mid-to-lAte Pleistocene. We Report Cosmogenic Be-10 Surface Exposure DAtIng Results From Glacially Transported Cobbles Embedded In Blue-ice moraIne MAterial At Mount hardIng  The Grove Mountains  Eais. Forty Exotic Cobbles Sampled AlOng Two PrOfiles (a And b) On This Blue-ice MoraIne Present Apparent Exposure-ages RangIng From 7.2 To 542.2 Ka. We Explore This Scattered Dataset By UsIng PrIncipal compOnent Analysis (Pca) To Identify Statistically Significant Trends In The Data. We Identify a correlatiOn betWeen Exposure-age And Distance Of The Cobbles From Mount hardIng. In prOfile a  Cobbles Further From Mount HardIng Yield Older Exposure-ages Than Those That Are Relatively Close. In Profile b  Cobbles Closer To Mount HardIng Are Found To Have Relatively Older Exposure-ages. In Term Of Glacial hisTory We Suggest That The Direction Of Ice Flow Changed durIng The Period From Similar To 60 To 200 Ka  And That Multiple Glacial Fluctuations Occurred In The Mid-late Pleistocene. (c) 2016 Elsevier Ltd. All Rights Reserved.  

Skull metastasis from hepatocellular carcinoma (HCC) is reported rarely. In addition  solitary skull metastasis as the first symptom of HCC is reported even less. Here  we reported a case of solitary skull metastasis as the first symptom of HCC and reviewed the literature on skull metastasis. A 49-year-old male patient was admitted to Jinjiang Hospital of Quanzhou Medical College with a painless parietal-occipital scalp mass  and he denied any history of hepatic disease. A cranial computed tomography demonstrated a hypervascular enhancement with osteolytic change in the right parietal-occipital region  cranial magnetic resonance imaging indicated a highly enhanced and osteolytic skull tumor  and abdominal computed tomography showed a huge tumor in the liver. The other examinations showed no other metastases. Laboratory data showed no liver dysfunction while hepatitis B surface antigen was positive  and alpha fetal protein level was high. A craniectomy was performed and the mass was totally removed. The histological diagnosis was skull metastasis from HCC. The patient was subsequently treated by transcatheter arterial chemoembolization. In a review of published literature  the incidence of skull metastasis from HCC in the period between 1990 and 2011 has significantly increased. The misdiagnosis rate of skull metastases as the first symptom from HCC was high. Therefore  it is necessary to give each patient with a scalp mass that has invaded the skull a liver ultrasound or computed tomography scan. On the other hand  we found that metastases that occurred in the calvaria site were more frequent than those that occurred in the skull base and facial skeleton. This may be worthy of further investigation in the future.  

Compounds of isotactic polypropylene (iPP) and beta-nucleating agent were used to investigate the relationship between the development of beta phase and molecular weight in iPP under quiescent crystallization conditions by using wide angle X-ray diffraction and differential scanning calorimetry techniques. In all cases  the dependency of the formation of beta phase in iPP on molecular weight of iPP at a defined crystallization temperature range was found. The iPP with high molecular weight possessed a wide range of crystallization temperature in inducing rich beta phase. However  poor or even no beta phase was obtained for the samples with low molecular weight in the same range. In addition  an upper critical crystallization temperature of producing dominant beta phase was found at 125 degrees C. Beyond this temperature  a phenomenon of prevailing alpha phase became obvious. (C) 2014 Wiley Periodicals  Inc.  

住房需求  住房供给  联立方程  Abstract  This  paper  addresses  the  issue  of  demand  and  supply  for  residential  housing  in  urban  China  since  the  late  1980s  when  the  urban  housing  market  became  commercialized.  We  start  with  the  basic  premise  that  the  standard  theory  of  demand  for  and  supply  of  consumer  durable  goods  is  applicable  to  urban  housing  in  China  after  the  market  for  housing  was  established.  In  a  simultaneous  equations  framework  we  provide  estimates  of  income  and  price  elasticities  of  demand  and  price  elasticity  of  supply.  Analysis  of  aggregated  annual  data  from  1987  to  2006  shows  that  the  rapid  increase  of  urban  residential  housing  can  be  well  explained  by  the  forces  of  demand  and  supply  i.e.  growth  in  income  and  change  in  construction  cost  determines  the  aggregated  movement  in  housing  price  to  a  large  extent.  We  have  found  the  (long-run)  income  elasticity  of  demand  for  urban  housing  to  be  about  1  and  the  price  elasticity  of  demand  to  be  between  -0.5  and  -0.6.   The  price  elasticity  of  supply  of  the  total  stock  of  housing  is  about  0.83.  Keywords:  housing  demand  housing  supply  simultaneous  equations