RFI measurements and mitigation for FAST

Radio Frequency Interference(RFI)mitigation is essential for supporting the science output of Five-hundred-meter Aperture Spherical radio Telescope(FAST)due to its high sensitivity.In order to protect FAST from RFI,an Electromagnetic Compatibility(EMC)study has been carried out and the operation of a Radio Quiet Zone(RQZ)is ongoing.RFI measurements of the telescope instruments and monitoring of the active radio services outside the site have revealed the radiation properties of the RFI sources.Based on the measurement results and theoretical analysis,various EMC methods have been implemented for the telescope to decrease the RFIs.Meanwhile,the main RFI sources in the FAST RQZ,such as mobile stations,broadcast stations and navigation instruments,have been identified,and the technical measures have been adopted to protect the quiet radio environment around the site.The early science outputs of FAST have demonstrated the efficiency of RFI mitigation methods.

EMC design for actuators in the FAST reflector

An active reflector is one of the three main innovations incorporated in the Five-hundredmeter Aperture Spherical radio Telescope（FAST）.The deformation of such a huge spherically shaped reflector into different transient parabolic shapes is achieved by using 2225 hydraulic actuators which change the position of the 2225 nodes through the connected down tied cables.For each different tracking process of the telescope,more than 1/3 of these 2225 actuators must be in operation to tune the parabolic aperture accurately and meet the surface error restriction.This means that some of these actuators are inevitably located within the main beam of the receiver,and Electromagnetic Interference（EMI）from the actuators must be mitigated to ensure the scientific output of the telescope.Based on the threshold level of interference detrimental to radio astronomy described in ITU-R Recommendation RA.769 and EMI measurements,the shielding efficiency（SE）requirement for each actuator is set to be 80 d B in the frequency range from 70 MHz to 3 GHz.Therefore,Electromagnetic Compatibility（EMC）was taken into account in the actuator design by measures such as power line filters,optical fibers,shielding enclosures and other structural measures.In 2015,all the actuators had been installed at the FAST site.Till now,no apparent EMI from the actuators has been detected by the receiver,which demonstrates the effectiveness of these EMC measures.

Hepatoprotective Effect of Guava (<i>Psidium guajava</i>L.) Leaf Extracts on Ethanol-Induced Injury on Clone 9 Rat Liver Cells

Guava (Psidium guajava L.), a tropical fruit, belongs to Myrtaceae family. Leaves and fruits of guava have been reported to have an anti-diarrheal, hypoglycemic, lipid lowering, anti-bacterial in addition to antioxidant activities. The aim of this study was to investigate several guava leaf extract cytotoxic effects on healthy clone 9 liver cells and its hepatoprotective effects on ethanol-induced heap-toxicity. It was discovered that when the clone 9 liver cells were treated with guava (Psidium guajava Linn.) extracts for 24 hours, there was no retardation of growth as well as when ethanol and acetone extracts at low concentrations 100 μg/mL and 50 μg/mL were administered however cytototoxic effects were detected at higher concentrations. Water and hot water extracts in concentrations lower than or equal to 500 μg/mL revealed no cytotoxic effects. Injury induction to healthy clone 9 liver cells using 5% alcohol concentration for 30 minutes revealed the hepatoprotective properties of guava (Psidium guajava Linn.) extracts. This was significant in concentrations of 100 μg/mL or lower for ethanol and all concentrations for hot water extracts. Hot water extracts showed higher hepatoprotective and lower cytotoxic properties than other extracts.

First application of large reactivity measurement through rod drop based on three-dimensional space–time dynamics

Abstract Reactivity measurement is an essential part of a zero-power physics test,which is critical to reactor design and development.The rod drop experimental technique is used to measure the control rod worth in a zero-power physics test.The conventional rod drop experimental technique is limited by the spatial effect and the difference between the calculated static reactivity and measured dynamic reactivity;thus,the method must be improved.In this study,a modified rod drop experimental technique that constrains the detector neutron flux shape function based on three-dimensional space–time dynamics to reduce the reactivity perturbation and a new method for calculating the detector neutron flux shape function are proposed.Correction factors were determined using Monte Carlo N-particle transport code and transient analysis code for a pressurized water reactor at the Ulsan National Institute of Science and Technology and Xi’an Jiaotong University,and a large reactivity of over 2000 pcm was measured using the modified technique.This research evaluated the modified technique accuracy,studied the influence of the correction factors on the modification,and investigated the effect of constraining the shape function on the reactivity perturbation reduction caused by the difference between the calculated neutron flux and true value,using the new method to calculate the shape function of the detector neutron flux and avoiding the neutron detector response function(weighting factor)calculation.

Study on anti-inflammatory mechanism and effects of Flemingia Roxb.exAit extract intervene acute gouty arthritis in rats

Objective:To investigate the effect and anti-inflammatory mechanism the effect of Flemingia Roxb.exAit extract on acute gouty arthritis.Methods:Sixty SD rats were randomly divided into 6 groups by weight,control and model group,(100、150、200 mg/kg)of Flemingia Roxb.exAit extract group and colchicine group.The rats of each group were given by intragastric for 7 days of continuous administration,meanwhile,there were given 0.9%NaCl solution instead as control and model group.The acute gouty arthritis model was constructed through right ankle joint cavity injection of sodium urate crystal solutionon day 5 after 1 h,but rats in the negative control group were injected with 0.9%NaCl solution into the articular cavity of the right foot.The general condition of rats and the degree of joint swelling,and the gait was observed after constructed model.To detected the joint fluid IL-1β、TNF-α、IL-6 indicators,and the expression of NLRP3,Caspase-1 protein in ankle joint tissue for 2 hours after the last administration.Results:Groups of Flemingia Roxb.exAit extract could markedly reduce the joint swelling on acute gouty arthritis rat model,improve gait in a dose-dependent manner,high dose group of Flemingia Roxb.exAit extract did particularly well(Pjoint swelling<0.01;Pgait<0.05),close to the therapeutic effect colchicine group.Further mechanism studies show that the joint fluid IL-1β、TNF-α、IL-6 level was reduced by Flemingia Roxb.exAit extract group,the expressions of NLRP3、Caspase-1 protein of Flemingia Roxb.exAit extract group was decreased observbly than model group,but the most obvious is that high dose group as well as colchicine group(PNALP3<0.01;PCaspase-1<0.01).Conclusion:Flemingia Roxb.exAit extract has the effect of treating acute gouty arthritis and its mechanism may be related toinhibiting NLRP3 inflammasome activation and inhibiting inflammatory response.

Effects of water extracts of Davallia formosana on ovariectomized mice

Objective： The Taiwan Residents native fern, Davallia formosana, is used to treat bone diseases in traditional Chinese medicine, but, very few animal tests to verify. To study how this fern and its active components alter bone metabolism. Methods： The effects of low and high doses of D. formosana water extracts （DFW, 50 and 200 mg/（kg·d）） and （-）-epicatechin-3-O-D-allopyranoside isolates of DFW （ECAP, 0.06 and 2.5 mg/（kg·d）） on protein lev- els of important indicators of osteoclast and osteoblast activities were examined. Ovariectomized mice were used as a model of osteoporosis. Bone morphogenetic protein 2 （BMP-2）, collagen 1 （COL-1）, alka- line phosphatase （ALP）, runt-related transcription factor 2 （RUNX2）, osteocalcin （OCN）, and osteopontin （OPN） were analyzed using western blotting of femur tissue. Interleukin （IL）-1β and tumor necrosis fac- tor （TNF）-a were measured in the serum, and hematoxylin and eosin staining were used to assess bone morphology. Results： Treatment with DFW or ECAP significantly induced BMP-2, COL-l, ALP, RUNX2, OCN, and OPN protein expression, indicating stimulation of osteogenesis. The treatments also reduced IL-1β and TNF- expression, indicating inhibition of osteoclastogenesis. In histological examinations, mice treated with DFW or ECAP had more bone trabeculae. The results demonstrate that DFW and ECAP inhibit osteo- clast differentiation and promote osteoblast differentiation, and effectively ameliorate ovariectomy （OVX）- induced osteoporosis. Conclusion： ECAP is a major component of DFW, which may have therapeutic potential for the treatment of diseases associated with excessive osteoclastic and insufficient osteogenic activity. ECAP may not be the specific active molecule because it is unstable in the stomach. However, the major active molecule needs to be confirmed using a relevant pharmacological model.