Passive neutron multiplicity device for^(240)Pu measurement based on FPGA

A passive neutron multiplicity measurement device,FH-NCM/S1,based on field-programmable gate arrays(FPGAs),is developed specifically for measuring the mass of plutonium-240(^(240)Pu)in mixed oxide fuel.FH-NCM/S1 adopts an inte-grated approach,combining the shift register analysis mode with the pulse-position timestamp mode using an FPGA.The optimal effective length of the^(3)He neutron detector was determined to be 30 cm,and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations.After fabricating the device,calibration measurements were per-formed using a^(252)Cf neutron source;a detection efficiency of 43.07%and detector die-away time of 55.79μs were observed.Nine samples of plutonium oxide were measured under identical conditions using the FH-NCM/S1 in shift register analysis mode and a plutonium waste multiplicity counter.The obtained double rates underwent corrections for detection efficiency(ε)and double gate fraction(f_(d)),resulting in corrected double rates(D_(c)),which were used to validate the accuracy of the shift register analysis mode.Furthermore,the device exhibited fluctuations in the measurement results,and within a single 20 s measurement,these fluctuations remained below 10%.After 30 cycles,the relative error in the mass of^(240)Pu was less than 5%.Finally,correlation calculations confirmed the robust consistency of both measurement modes.This study holds specific significance for the subsequent design and development of neutron multiplicity devices.

Microstructure,mechanical properties and wear resistance of SiC_(p)/AZ91 composite prepared by vacuum pressure infiltration

SiC_(p)/AZ91 composites were prepared by vacuum pressure infiltration.The microstructure,mechanical properties and wear resistance of composite were studied.Results indicated that SiC particles were uniformly distributed in the metal matrix and had a good interface bonding with the metal matrix.Mg_(17)Al_(12) preferably precipitated near the SiC particles,and high-density dislocations were induced by the mismatch of the coefficient of thermal expansion(CTE)between the SiC particle and the AZ91 matrix,thereby accelerating the aging precipitation of the matrix.Compared with AZ91 alloy,the addition of SiC particles improves the hardness and compressive strength of the composite,which is mainly due to the load transfer strengthening and grain refinement strengthening mechanisms.Furthermore,a stable support surface-protecting matrix formed during the wear process because of the excellent wear resistance of SiC.

Dense copper azide synthesized by in-situ reaction of assembled nanoporous copper microspheres and its initiation performance

Copper azide with high density was successfully synthesized by in-situ reaction of nanoporous copper(NPC)precursor with HN_(3) gaseous.NPC with pore size of about 529 nm has been prepared by electroless plating using polystyrene(PS)as templates.The copper shells thickness of NPC was controlled by adjusting the PS loading amount.The effects of copper shell on the morphology,structure and density of copper azide were investigated.The conversion increased from 87.12%to 95.31%when copper shell thickness decrease from 100 to 50 nm.Meanwhile,the density of copper azide prepared by 529 nm NPC for 24 h was up to 2.38 g/cm^(3).The hollow structure of this NPC was filled by swelling of copper azide which guaranteed enough filling volume for keeping the same shape as well as improving the charge density.Moreover,HNS-IV explosive was successfully initiated by copper azide with minimum charge thickness of 0.55 mm,showing that copper azide prepared has excellent initiation performance,which has more advantages in the application of miniaturized explosive systems.

Various Silver Nanostructures on Sapphire Using Plasmon Self-Assembly and Dewetting of Thin Films

Silver(Ag) nanostructures demonstrate outstanding optical, electrical, magnetic, and catalytic properties and are utilized in photonic, energy, sensors, and biomedical devices.The target application and the performance can be inherently tuned by control of configuration, shape, and size of Ag nanostructures. In this work, we demonstrate the systematical fabrication of various configurations of Ag nanostructures on sapphire(0001) by controlling the Ag deposition thickness at different annealing environments in a plasma ion coater. In particular, the evolution of Ag particles(between 2 and 20 nm),irregular nanoclusters(between 30 and 60 nm), and nanocluster networks(between 80 and 200 nm) are found be depended on the thickness of Ag thin film. The results were systematically analyzed and explained based on the solid-state dewetting,surface diffusion, Volmer–Weber growth model, coalescence,and surface energy minimization mechanism. The growth behavior of Ag nanostructures is remarkably differentiated at higher annealing temperature(750 ℃) due to the sublimation and temperature-dependent characteristic of dewetting process.In addition, Raman and reflectance spectra analyses reveal that optical properties of Ag nanostructures depend on their morphology.

Rules of acupuncture point selection in the treatment of rheumatoid arthritis through data mining

Objective:To explore the rules of acupuncture point selection in thetreatment of rheumatoid arthritis by applying data mining and modern Statistical software.Methods:We retrieved literature from China hownet(CNKI),VIP database(VIP),Wanfang,PubMed,MEDLINE,Embase database from the founding of the database to February 1,2020.The main information of meridians and acupoints were entered into Excel,SPSS22.0 was used to extract data and do clustering analysis.Results:Quchi,Zusanli,Hegu,Yanglingquan,Xiyan were often chosen for electropuncture treatment of rheumatoid arthritis.Most of the acupoints are located in the large intestine channel of hand yangming bladder meridian or bladder channel of foot Taiyang,Shaoyang gallbladder channel of foot,stomachmeridian of foot Yangming,the energizer meridian and concentrated in the upper and lower extremities.The frequency of use of five Shu points,crossing point,source point,lowerconfluent and eight meeting points acupoints is higher.Cluster analysis can divide the included acupoints into 5 clusters.Conclusion:Quchi,Zusanli,Hegu,Yanglingquan,Xiyan are often chosen for electropuncture treatment of rheumatoid arthritis.Most of the selected acupoints aremostly distributed in the acupoints which are located in the large intestine channel of hand yangming bladder meridian or bladder channel of foot Taiyang,Shaoyang gallbladder channel of foot,Stomach meridian of foot Yangming,and the energizer meridian.

A novel missense mutation of NR5A1 c.46T>C (p.C16R) in a Chinese infant with ambiguous genitalia

Dear Editor,46,XY disorders/differences of sex development(DSD)includes a broad spectrum of disorders caused by genetic mutations,changes in the production of testicular hormones,or altered peripheral responses to testicular hormones,resulting in varying degrees of undervirilization.1.2 Infants with 46,XY DSD might exhibit a variety of ambiguous genital phenotypes,and the management of these individuals can prove challenging.

Efficient quantum dot infrared solar cells with enhanced lowenergy photon conversion via optical engineering

Infrared(IR)solar cells are promising devices for improving the power conversion efficiency(PCE)of conventional solar cells by expanding the utilization region of the sunlight spectrum to near-infrared range.IR solar cells based on colloidal quantum dots(QDs)have attracted extensive attention due to the widely tunable absorption spectrum controlled by dot size and the unique solution processibility.However,the trade-off in QD solar cells between light absorption and photo-generated carrier collection has limited the further improvement of PCE.Here,we present high-performance PbS QD IR solar cells resulting from the combination of boosted light absorption and optimized carrier extraction.By constructing an optical resonance cavity,the light absorption is significantly enhanced in the range of 1,150–1,300 nm at a relatively thin photoactive layer.Meanwhile,the thin photoactive layer facilitates efficient carrier extraction.Consequently,the PbS QD IR solar cells exhibit a highly efficient photoelectric conversion in the IR region,resulting in a high IR PCE of 1.3%which is comparable to the highest value of solution-processed IR solar cells based on PbSe QDs.These results demonstrate that constructing an optical resonance cavity is a reasonable strategy for effective conversion of photons in the devices aiming at light in a relatively narrow wavelength range,such as IR solar cells and narrow band photodetectors.

Structural characterization of steam-heat treated Tectona grandis wood analyzed by FT-IR and 2D-IR correlation spectroscopy

The properties of wood can be improved through steam-heat treatment.There are many studies about mechanical properties of steam-heat treated wood,but very few studies are on the aspects of chemical modifications.In this study,FT-IR spectra combined with SD-IR spectra,correlation coefficients and 2DIR spectra are employed to analyze the chemical modifications of teak[Tectona grandis L.F.） wood during steam-heat treatment under treatment temperatures from 120 ℃ to 220 ℃ at intervals of 20 ℃.Acetic acid,which is produced during steam-heat treatment,acts as a catalyst of condensation and degradation reactions of wood components.The changes of wood components are more and more intense with increasing the treatment temperature.The sensitivity of wood samples to thermal perturbation rises initially with increasing treatment temperature before falling back.The steam-heat treated wood under180℃ is the most sensitive.