A novel method for gamma spectrum analysis of low-level and intermediate-level radioactive waste

The uncertainty of nuclide libraries in the analysis of the gamma spectra of low-and intermediate-level radioactive waste(LILW)using existing methods produces unstable results.To address this problem,a novel spectral analysis method is proposed in this study.In this method,overlapping peaks are located using a continuous wavelet transform.An improved quadratic convolution method is proposed to calculate the widths of the peaks and establish a fourth-order filter model to estimate the Compton edge baseline with the overlapping peaks.Combined with the adaptive sensitive nonlinear iterative peak,this method can effectively subtracts the background.Finally,a function describing the peak shape as a filter is used to deconvolve the energy spectrum to achieve accurate qualitative and quantitative analyses of the nuclide without the aid of a nuclide library.Gamma spectrum acquisition experiments for standard point sources of Cs-137 and Eu-152,a segmented gamma scanning experiment for a 200 L standard drum,and a Monte Carlo simulation experiment for triple overlapping peaks using the closest energy of three typical LILW nuclides(Sb-125,Sb-124,and Cs-134)are conducted.The results of the experiments indicate that(1)the novel method and gamma vision(GV)with an accurate nuclide library have the same spectral analysis capability,and the peak area calculation error is less than 4%;(2)compared with the GV,the analysis results of the novel method are more stable;(3)the novel method can be applied to the activity measurement of LILW,and the error of the activity reconstruction at the equivalent radius is 2.4%;and(4)The proposed novel method can quantitatively analyze all nuclides in LILW without a nuclide library.This novel method can improve the accuracy and precision of LILW measurements,provide key technical support for the reasonable disposal of LILW,and ensure the safety of humans and the environment.

Strengthening iron enrichment and dephosphorization of high-phosphorus oolitic hematite using high-temperature pretreatment

The efficient development and utilization of high-phosphorus oolitic hematite is of great strategic significance for the sustainable supply of iron-ore resources in China.In this paper,the mechanism of high-temperature pretreatment for enhancing the effect of iron enrichment and dephosphorization in the magnetization roasting–leaching process was studied by X-ray diffraction(XRD),vibration sample magnetometer(VSM),scanning electron microscopy and energy dispersive spectrometry(SEM–EDS).Compared with the process without high-temperature pretreatment,the iron grade of the magnetic separation concentrate after high-temperature pretreatment had increased by 0.98%,iron recovery rate had increased by 1.33%,and the phosphorus content in the leached residue had decreased by 0.12%.High-temperature pretreatment resulted in the dehydration and decomposition of hydroxyapatite,the dehydration of limonite and the thermal decomposition of siderite,which can produce pores and cracks and weaken the compactness of the ore,improve the magnetization characteristics of roasted ore,and strengthen the iron enrichment and dephosphorization during the magnetization roasting and leaching process.

Efficient enrichment of nickel and iron in laterite nickel ore by deep reduction and magnetic separation

The process of deep reduction and magnetic separation was proposed to enrich nickel and iron from laterite nickel ores.Results show that nickel-iron concentrates with nickel grade of 6.96%,nickel recovery of 94.06%,iron grade of 34.74%,and iron recovery of 80.44% could be obtained after magnetic separation under the conditions of reduction temperature of 1275℃,reduction time of 50 min,slag basicity of 1.0,carbon-containing coefficient of 2.5,and magnetic field strength of 72 kA/m.Reduction temperature and time affected the possibility of deep reduction and reaction progress.Slag basicity affected the composition of slag in burden and the spilling and enriching rate of nickel-iron from a matrix to form nickel-iron particles.Nickel-iron particles were generated,aggregated,and grew gradually in the reduction process.Nickel-iron particles can be effectively separated from gangue minerals by magnetic separation.

Multi-scale impact crushing characteristics of polymetallic sulphide ores

The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead-zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated by mineral liberation analyzer(MLA) and drop weight test. The results show that both ores contain pyrrhotite, sphalerite, jamesonite, gangue mica and quartz except cassiterite. Cassiterite is closely associated with sulphide and quartz to form aggregates, which are mixed with each other in the form of intergrowth or symbiotic disseminated fine grains. Cassiterite has a significant impact on ore crushing characteristics. Ore hardness is negatively correlated with the product of crushing parameters of A and b, i.e. A×b, the effect of crushing energy on crushing fineness is related to crushing parameters A and b, and the influence degree increases with the increase of A. The influence degree increases with the increase of b when crushing energy ECS is less than 1 kW·h/t, and the influence degree decreases with the increase of b when crushing energy ECS is greater than 1 kW·h/t. The impact of crushing energy on crushing fineness is greater than that of ore particle size when the crushing energy is lower;on the contrary, the impact of ore particle size on crushing fineness is greater than that of crushing energy when crushing energy is higher.

Anesthetic effect of dexmedetomidine in high intensity focused ultrasound treatment of uterine fibroids

Objective: To study the effect of dexmedetomidine in high intensity focused ultrasound treatment of uterine fibroids on pain degree, pain mediator and stress mediator secretion as well as stress signal molecule expression. Methods: 78 patients with uterine fibroids who received high intensity focused ultrasound treatment in Shaanxi Second Provincial People's Hospital between February 2015 and February 2018 were selected as the research subjects and randomly divided into the Dex group who accepted dexmedetomidine + fentanyl + midazolam anesthesia and the control group who accepted fentanyl + midazolam anesthesia. The pain degree was assessed 1 day and 3 d after surgery;the secretion of pain mediators and stress mediators in serum as well as the expression levels of stress signaling molecules in peripheral blood were measured before surgery and 3 d after surgery. Results: 1 d and 3 d after surgery, the NRS pain scores of Dex group were significantly lower than those of control group;3 d after surgery, serum SP, BK, 5-HT, IL-6, IL-8, NE, COR, ACTH and MDA contents as well as peripheral blood NF-κB, p38MAPK, NOX4 and Nrf2 expression of both groups of patients were higher than those before surgery whereas serum SOD and HO-1 contents as well as peripheral blood Keap1 expression were lower than those before surgery, and serum SP, BK, 5-HT, IL-6, IL-8, NE, COR, ACTH and MDA contents as well as peripheral blood NF-κB, p38MAPK, NOX4 and Nrf2 expression of Dex group 3 d after surgery were lower than those of control group whereas serum SOD and HO-1 contents as well as peripheral blood Keap1 expression were higher than those of control group. Conclusion: The application of dexmedetomidine in high intensity focused ultrasound treatment of uterine fibroids can reduce the degree of postoperative pain and stress response.

Process-driven susceptibility assessment of glacial lake outburst debris flow in the Himalayas under climate change

Global warming is causing glaciers to retreat and glacial lakes to expand in the Himalayas,which amplifies the risk of glacial lake outburst debris flows(GLODFs)and poses a significant threat to downstream lives and infrastructures.However,the complex interplay between GLODF occurrences and associated indicators,coupled with the lack of a comprehensive susceptibility indicator system that considers the entire GLODF process,presents a substantial challenge in assessing GLODF susceptibility in the Himalayas.This study proposes a process-driven GLODF susceptibility assessment indicator system responding to climate change that considers the complete process of GLODF formation,incorporating relevant parameters about upstream,themselves,and downstream of glacial lakes.Furthermore,to mitigate subjective factors associated with traditional evaluation methods,we developed three novel hybrid machine-learning models by integrating classic machine-learning algorithms with the whale optimization algorithm(WOA)to delineate the distribution of GLODF susceptibility in the Himalayas.All the hybrid models effectively predicted the GLODFs occurrence,with the WOA-SVC model demonstrating the highest prediction accuracy.Approximately 34%of the catchments exhibit high and very high susceptibility levels,primarily concentrated along the north and south sides of the Himalayan ridge,particularly in the eastern and central Himalayas.Indicators capturing the physical formation process of hazards,such as topographic potential(highest relative importance value of 40%),can precisely identify GLODF.A total of 128 catchments pose potential transboundary threats,with 24 classified as having a very high susceptibility level and 25 as having a high susceptibility level.Notably,the border region between China and Nepal is a prominent hotspot for transboundary threats of GLODF.These findings can provide valuable clues for disaster prevention,mitigation,and cross-border coordination in the Himalayas.

A theoretical study of the effect and mechanism of FeN_(3)-doped biochar for greenhouse gas mitigation

Paddy fields are a major emission source of greenhouse gases(GHGs)[for instance,methane(CH_(4)),nitrous oxide(N_(2)O),and carbon dioxide(CO_(2))]among agricultural fields.Biochar has been deemed a potential candidate for the reduction of GHGs in paddy fields.However,there is no consistent conclusion that biochar can simultaneously reduce emissions of CH_(4),N_(2)O,and CO_(2).Herein,we proposed the FeN_(3)-doped biochar(FG)as an excellent material for GHGs restriction in paddy fields via the first-principles calculation.The computation results indicated that the FG exhibited satisfactory adsorption ability for CH_(4),CO_(2),and N_(2)O,which improved the adsorption energies to−1.37,−1.54,and−2.91 eV,respectively.Moreover,the density of state(DOS)analyses revealed that the factor responsible for FeN_(3)-doped biochar to exhibit excellent adsorption ability was the occurrence of drastic energy up-or down-shift of the electron for Fe d,C p,O p,or N p orbital upon adsorption of CH_(4),CO_(2),or N_(2)O.Our study suggested an advanced modified biochar material for reducing the GHGs emissions in paddy fields,in addition to exploring the adsorption properties and mechanisms of FeN_(3)-doped biochar for GHGs mitigation,which provided a strategy to explore biochar modification and efficient emission reduction materials.

Survival benefit of pancreatic metastasectomy of clear cell renal cell carcinoma

The clear cell renal cell carcinoma(ccRCC)appears to have a predilection for metastasizing to the pancreas/11 In the recent years,there are increasing numbers of clinical series from Europe and the United States that demonstrate encouraging survival results of pancreatic metastasectomy,121 but there are a few clinical data or only some case reports from East Asian population,[3] and there are no specific guidelines regarding the appropriate management.The objective of this study was to present our experience of pancreatic metastasectomy from ccRCC by reporting the peri-operative and survival outcome.