Measurement of the neutron total cross section of carbon at the Back-n white neutron beam of CSNS

To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using ^235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.

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.

Chinese expert consensus on organ protection of transplantation(2022 edition)

Introduction Organ transplantation increases survival and improves qual-ity of life to many patients with end-stage organ failure.Or-gan shortage is a worldwide problem that restricts organ trans-plantation[1].Organ procurement and preservation as well as ischemia-reperfusion injury(IRI)after transplantation are the im-portant factors affecting prognosis of recipients.Since the de-velopment of organ transplantation technology in the 20th cen-tury,organ protection technology has been a most promising con-cept in this field.Organ preservation solutions such as the Collins solution,University of Wisconsin(UW)solution,and histidine-tryptophan-ketoglutarate(HTK)solution were developed sequen-tially[2],which developed rapidly in static cold storage(SCS)tech-niques.SCS remains the standard preservation technique for organ transplantation[2].

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.

Chinese Trauma Surgeon Association for management guidelines of vacuum sealing drainage application in abdominal surgeries-Update and systematic review

Vacuum sealing drainage (VSD) is frequently used in abdominal surgeries. However, relevant guidelines are rare. Chin ese Trauma Surge on Associati on orga nized a committee composed of 28 experts across China in July 2017, aiming to provide an evidence-based recommendation for the application of VSD in abdominal surgeries.Eleven questions regarding the use of VSD in abdominal surgeries were addressed:(1) which type of materials should be respectively chosen for the intraperitoneal cavity, retroperitoneal cavity and superficial incisions?(2) Can VSD be preventively used for a high-risk abdominal incision w让h primary suture?(3) Can VSD be used in severely contaminated/infected abdominal surgical sites?(4) Can VSD be used for temporary abdominal cavity closure under some special conditions such as severe abdominal trauma, infection, liver transplantation and intra-abdominal volume increment in abdominal compartment syndrome?(5) Can VSD be used in abdominal organ inflammation, injury, or postoperative drainage?(6) Can VSD be used in the treatment of intestinal fistula and pancreatic fistula?(7) Can VSD be used in the treatment of intra-abdominal and extra-peritoneal abscess?(8) Can VSD be used in the treatment of abdominal wall wounds, wound cavity, and defects?(9) Does VSD in crease the risk of bleeding?(10) Does VSD increase the risk of intestinal wail injury?(11) Does VSD increase the risk of peritoneal adhesion? Focusing on these questions, evidence-based recommendations were given accordingly. VSD was strongly recommended regarding the questions 2-4. Weak recommendations were made regarding questions 1 and 5-11. Proper use of VSD in abdominal surgeries can lower the risk of infection in abdominal incisions with primary suture, treat severely contaminated/infected surgical sites and facilitate temporary abdominal cavity closure.

用于深亚波长聚焦的极端透射弹性波超构表面

本文提出了由之字形单元组成的弹性波超构表面来实现对弯曲波的深亚波长尺度操控.通过遗传算法对单元进行参数优化,可以找到具有全透射率和全相位控制的单元,而其宽度仅为波长的1/5.结合传输模态和Kirchhoff薄板理论,发展了理论模型并解释了这些单元产生优越性能的原因.接着,设计了直线型和曲线型超构表面实现不同位置的弯曲波聚焦,其仿真结果都显示出了优异的性能,进一步加工制作直线型超构表面并进行实验测试,实验结果与仿真结果非常吻合,结果同时表明入射波能量在焦点处提高了6倍以上.本工作提出的超构表面可用于设计紧凑高效的弹性波器件.

The research of laser-based rapid measurement system for scintillator neutron detectors arrays

Purpose Scintillator Neutron Detectors Arrays(SNDA)were successfully installed at General Purpose Powder Diffractome-ter(GPPD)at the China Spallation Neutron Source(CSNS).The inhomogeneity of the detection efficiency in each detector module,which caused by the gain nonuniformity of the multi-anode photo-multiplier tubes(MA-PMTs)and the inconsistency of the wave-length shifting fibers in collecting scintillation photons,need to be mitigated before the installation.Methods An automated rapid measurement system based on the blue laser and the two-dimensional mobile platform was developed to calibrate the light response of each channel in detector modules.According to the test results of this system,the electronics threshold of each channel of the SNDA is adjusted.Before the installation of the all 40 SNDA modules in GPPD,the electronics thresholds of each channel are adjusted according to the measurement results of this rapid measurement system.Results and Conclusion Compared with the unadjusted detector module,the adjusted one obtained a better uniformity of the neutron detection efficiency.The inhomogeneity of the detection efficiency is improved from 27.4%to 10.9%.The test result of the diffraction peak of the standard sample Si showed that the adjusted SNDA works well in GPPD.