粒径及颗粒级配对离子型稀土二维入渗特性的影响

借助于数字图像技术开展离子型稀土二维入渗试验,通过可视化的数字图像刻画湿润体演化过程。湿润锋距离与注液时间呈现极显著的幂函数关系,随着细颗粒含量的增加,湿润锋距离逐渐减小,入渗曲线变平缓;在注液初期,水平方向湿润锋距离比垂直方向湿润锋距离大,随着注液时间推移,垂直方向湿润锋距离逐渐接近水平方向湿润锋距离。湿润锋运移速率呈现出三阶段的变化规律,在相同历时,湿润锋运移速率随着粗颗粒含量的增加而增大。定义向速比表征不同方向湿润锋运移速率的比值。在注液初期,水平方向湿润锋运移速率快,随着时间的推进,垂直方向湿润锋运移速率逐渐接近水平方向。建立稳定入渗率与特征粒径、不均匀系数和曲率系数的线性经验关系,为反演原地浸矿时的稳定入渗率提供理论依据。

风化壳淋积型稀土矿的土水特性

风化壳淋积型稀土矿的渗透特性直接影响原地浸矿的浸出效率。土水特征曲线是研究矿体渗透特性的重要基础,与许多因素具有关联性。为了研究不同因素对矿体土水特征曲线的影响,采用压力板仪进行土水特性试验,分析干密度、粒径和溶浸对稀土矿体土水特性的影响及其作用机理。结果表明,随着干密度的减小,孔隙率增大,矿体饱和含水量增加。采用同一基质吸力时,随着粒径的增加,矿体含水率逐渐减小,矿体持水能力降低。在相同体积含水率情况下,基质吸力与粒径大小成反比。采用同一基质吸力时,溶浸后矿体含水量比溶浸前矿体含水量降低,说明溶浸使得矿体持水能力减小。

A large area ^(3)He tube array detector with vacuum operation capacity for the SANS instrument at the CSNS

The small-angle neutron scattering(SANS)instrument,one of the first three instruments of the China Spallation Neutron Source(CSNS),is designed to probe the microscopic and mesoscopic structures of materials in the scale range 1–100 nm.A large-area ^(3)He tube array detector has been constructed and operates at the CSNS SANS instrument since August 2018.It consists of 120 linear position-sensitive detector tubes,each 1 m in length and 8 mm in diameter,and filled with ^(3)He gas at 20 bar to obtain a high detection efficiency.The ^(3)He tubes were divided into ten modules,providing an overall area of 1000 mm×1020 mm with a high count rate capability.Because each tube is installed independently,the detector can be quickly repaired in situ by replacing damaged tubes.To reduce air scattering,the SANS detector must operate in a vacuum environment(0.1 mbar).An all-metal sealing technique was adopted to avoid high-voltage breakdown by ensuring a high-voltage connection and an electronic system working in an atmospheric environment.A position resolution of 7.8±0.1 mm(full width at maximum)is measured along the length of the tubes,with a high detection efficiency of 81±2% at 2A.Operating over the past four years,the detector appears to perform well and with a high stability,which supports the SANS instrument to finish approximately 200 user scientific programs.

Changing trends and influencing factors of the quality of life of chemotherapy patients with breast cancer

Objective： To understand the changing trajectory of quality of life（QOL） during the treatment courses of breast cancer patients during chemotherapy and to investigate the factors in each treatment course that affect QOL.Methods： The M.D. Anderson Symptom Inventory Scale, the Hospital Anxiety and Depression Scale（HADS）, and the Functional Assessment of Cancer Therapy-Breast（FACT-B） scale were used to perform a survey on 174 breast cancer patients who received the TAC（docetaxel, Adriamycin, and cyclophosphamide） chemotherapy regimen before postoperative chemotherapy and 5-7 days after each chemotherapy course.Results： The QOL scores of the breast cancer patients were the lowest before the postoperative chemotherapy（81.2 ± 19.6） and the highest after the second chemotherapy course（94.5 ± 14.4）. After the fourth and fifth chemotherapy courses, the scores were much lower again, with values of 82.7 ± 13.9and 82.6 ± 13.1, respectively. The scores improved again after the sixth chemotherapy course（93.9 ± 18.7）. Furthermore, each treatment course had different related symptoms that affected the QOL of the patients.Conclusions： More attention should be paid to the changing trajectory of QOL of patients in all treatment courses and to the influence of treatment-related symptoms on the QOL of patients; moreover, interventions should be adopted by medical care personnel to increase QOL in cancer patients.

Compact lithium-glass neutron beam monitor for SANS at CSNS

A small-angle scattering neutron spectrometer for material research is under construction at the China Spallation Neutron Source. An intervening neutron beam monitor behind the sample is needed to measure the beam intensity in order to reduce the measurement uncertainty caused by beam fluctuation. Considering the mobility requirement and limited space, we proposed a compact monitor using a type of lithium-glass scintillator provided by China Building Materials Academy. Its performance was studied experimentally using ^(252)Cf and ^(60)Co sources.The neutron light yield of the selected scintillator was measured to be 5:3 × 10~3 photons/neutron. The feasibility of n-gamma discrimination using the charge comparison method was verified. By using the Geant4 toolkit, themonitor was modeled with precise physical processes including neutron tracking, scintillation, and optical photon transmission. The gamma sensitivity and detection efficiency were investigated in the simulation. It was concluded that a 0.5-mm-thick lithium-glass scintillator with natural lithium is an appropriate choice to satisfy both the neutron detection efficiency and gamma elimination requirements.

Ergogenic Capacity of a 7-Chinese Traditional Medicine Extract in Aged Mice

The ergogenic properties of a 7-Chinese traditional medicine water extract (Ligustrum lucidum ait, LLA), which is composed of the essences of Lycii fructus, Crataegi fructus, Phyllanthi fructus, Chrysanthemi flos, Coicis semen, Ganoderma lucidum, and Zizyphi fructus, were studied using aged mice. Mice were chronically (one month) administered LLA (0.1% and 1%) in the drinking water. Mice pre-treated with LLA showed a good appetite;however, they exhibited a lower rate of body weight increase compared to control mice. In mice subjected to the rotarod test, 1% LLA treatment provided effective adaption to fatigue and significantly increased the duration of mice on the rotarod. In locomotor activity test, 1% LLA potentiated mice mobility and significantly increased rearing behavior. In the antioxidant experiment, 1% LLA treatment significantly increased superoxide dismutase activity in the spleen and liver glutathione levels. These findings suggest that LLA may be utilized as an antifatigue agent, which may function through its antioxidant activity.

Development of 3He-filled linear position-sensitive detector for neutron scattering instruments at CSNS

Background Helium-3-filled linear position-sensitive detectors(LPSDs)have been widely applied to neutron scattering instruments in recent decades owing to the high detection efficiency,the excellent neutron/gamma discrimination,and the ability to construct the detector with large area coverage.More than 65%of neutron instruments at the China Spallation Neutron Source(CSNS)require ^(3)He LPSDs for the building of the detector system.The detector of a neutron scattering instrument is normally an array detector composed of a large number of ^(3)He LPSDs.However,no appropriate substitute detector is available for the ^(3)He LPSD for operation over a short period,and its specifications need to be customized to satisfy the requirements of different instruments.This necessitates the development of ^(3)He LPSDs with different specifications for building and upgrading the detectors of neutron scattering instruments at CSNS.Purpose To meet the general requirements specified by the neutron instruments at CSNS,a ^(3)He LPSD was developed and its performances were investigated by using the neutron beam.Methods The neutron beam experiments for this ^(3)He LPSD,including measurements of counting rate plateau curve,position calibration,and position resolution along the tube path,were carried out at the beamline-20 of CSNS.To evaluate its performance in the instrument operation,a detector module made of this ^(3)He LPSD has been installed in the multi-physics instrument(MPI),and the comparison test with the commercial ^(3)He LPSD has been conducted at neutron scattering experiments.Results and conclusion The experimental measurements for this ^(3)He LPSD based on the neutron beam showed that it satisfies the requirements for use in neutron scattering instruments.It reaches a plateau slope of 2.6%/100 V with a plateau range from 1750 to 1950 V and attained a minimal position resolution of 5.3 mm(FWHM),superior to the one achieved by the commercial ^(3)He LPSD.In addition,this ^(3)He LPSD detector module applied to the MPI has been working steadily for half of year and is available for use in experiments.These results provide a sound basis for the subsequent construction and upgradation of the detector of neutron scattering instruments at CSNS.

Test of a ^(3)He neutron detector readout electronics prototype for CSNS multipurpose physics neutron diffractometer

Background Large areas of 3He neutron detector array and corresponding readout electronics are used in the MPI built at China Spallation Neutron Source(CSNS)to measure the position and flight time of scattered neutrons,and MPI has a high requirement for the position resolution of 3He neutron detector.A 3He neutron detector readout electronics prototype composed of two front-end boards and one digital readout board is designed to meet the above requirements.Purpose Testing the whole readout electronics system before its mass production to ensure it can run correctly and fulfill the functional and performance requirements.Methods The test of the readout electronics prototype is implemented in the laboratory,and a signal generator is used to generate electronic signals instead of actual neutron signals.The position resolution test of the readout electronics prototype with 3He tubes is carried out in the No.20 beamline measurement room of CSNS.Results and Conclusion The functional and performance tests in the laboratory state that the readout electronics prototype can fulfill the readout requirements.The typical value of charge resolution is 0.85 fC;the integral nonlinearity of charge is 0.094%in the input charge range from 100 to 800 fC.The position resolution test result of the prototype with 3He tubes is better than the design requirement of 10 mm and also quite good compared with that of some other commercial products.These tests provide a reliable basis for the mass production of the readout electronics prototype.

Simulation and optimization of the boron-lined MWPC neutron detectors

Purpose Boron-lined gas detectors are prospective alternatives to helium-3-based neutron detectors.For boron-lined multiwire proportional chamber(MWPC)with neutron grazing incident angle geometry,high neutron detection efficiency and 3D position sensitive can be realized.In this paper,a multi-layer boron-lined MWPC was studied.Methods Influences of the boron coating thickness,coating layer numbers and neutron incident angle on the neutron detection efficiency were studied and optimized with Geant4 simulation.The output signal properties including induced signal width on the readout plane,the time resolution and gas gain uniformity of the detector were studied with Garfield program.Results and conclusion The results show that the neutron detection efficiency can be significantly increased by using neutron grazing incident geometry.For 4 layers of 10B4Cwith thickness of 1μm,the neutron detection efficiency can reach to 54.56%,49.17%and 44.36%when neutron incident angle is 6°,8°and 10°,respectively.For detector with curved geometry,the gas gain is nonuniform among the anode wires,and using separate high voltage for each anode wire or wires group can effectively reduce the nonuniform of the gas gain.The results of this work can be used to optimize the detector design.