The Precursor Phase of an X-class Flare: Magnetic Reconnection, Powering and Non-thermal Electrons

In this paper,we report three interesting phenomena that occurred during the precursor phase of the X1.6 class flare on 2014 September 10.(1) The magnetic reconnection initiating the flare occurs between one of the two J-shaped magnetic flux ropes that constitute a sigmoidal structure and the overlying sheared magnetic arcade that runs across the sigmoid over its middle part.The reconnection formed an erupting structure that ultimately leads to flare onset.Another J-shaped magnetic flux rope remains unaffected during the whole eruption.The phenomenon is revealed by the observation made by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory(SDO)at 94 and 131 A.(2) Being simultaneously with starting time of the precursor,photospheric vertical electric current(VEC) around the footpoint region of the overlying magnetic arcade underwent an obvious increase,as observed by the Helioseismic and Magnetic Imager(HMI) on board SDO.By only taking into account the VEC with current density over 3σ value(1σ:10 mA m^(-2)),we are able to pick out precursor-associated VEC increase starting from nearly the level of zero.We regard it as a kind of powering process for the magnetic reconnection between the two magnetic loops.(3) With high-resolution narrow-band Helium 10830 A images taken by Goode Solar Telescope at Big Bear Solar Observatory(BBSO),we observe a narrow absorption(dark) front that runs along the erupting magnetic structure(or the erupting hot channel) and moves in the direction of the eruption during the precursor phase.Assuming the excitation mechanism of Helium atoms along the absorption front by non-thermal electrons,the phenomenon shows that the interaction between the erupted hot channel and the overlying(or surrounding)magnetic field has yielded electron acceleration.

An insight of environmental contamination of arsenic on animal health

The main threats to human health from heavy metals are associated with exposure to lead,cadmium,mercury and arsenic.Exposure to arsenic is mainly via intake of food and drinking water,food being the most important source in most populations.Although adverse health effects of heavy metals have been known for a long time,exposure to heavy metals continues and is even increasing in some areas.Longterm exposure to arsenic in drinking-water is mainly related to increased risks of skin cancer,but also some other cancers,as well as other skin lesions such as hyperkeratosis and pigmentation changes.Therefore,measures should be taken to reduce arsenic exposure in the general population in order to minimize the risk of adverse health effects.Animal are being exposed to arsenic through contaminated drinking water,feedstuff,grasses,vegetables and different leaves.Arsenic has been the most common causes of inorganic chemical poisoning in farm animals.Although,sub-chronic and chronic exposure of arsenic do not generally reveal external signs or symptoms in farm animals but arsenic(or metabolites)concentrations in blood,hair,hoofs and urine are remained high in animals of arsenic contaminated zones.So it is assumed that concentration of arsenic in blood,urine,hair or milk have been used as biomarkers of arsenic exposure in field animals.