Genome-wide scans for selection signatures in indigenous chickens reveal candidate genes associated with local adaptation.

Population growth and climate change pose challenges to the sustainability of poultry farming. The emphasis on high-yield traits in commercialized breeds has led to a decline in their adaptability. Chicken varieties adapted to the local environment, possessing traits that facilitate adaptation to climate change, such as disease resistance and tolerance to extreme weather conditions, can improve hybridization outcomes. In this study, we conducted an analysis of the population structure and genetic diversity of 110 chickens representing indigenous breeds from southern China and two different commercial breeds. Further, we performed comparative population genomics, utilizing nucleotide diversity and fixation statistics, to characterize genomic features of natural selection and to identify unique genetic traits and potential selection markers developed by indigenous breeds after adapting to the local environment. Results based on genetic diversity and population structure analyses showed that indigenous varieties exhibited high levels of genetic diversity. Commercial breeds that have been indigenously bred demonstrated higher levels of genetic diversity than those that have not, and breeds with different selection practices displayed significant differences in genetic structure. Additionally, we further searched for potential genomic regions in native chicken ecotypes, uncovering several candidate genes related to ecological adaptations affecting local breeds, such as IKBKB, S1PR1, TSHR, IL1RAPL1 and AMY2A, which are involved in disease resistance, heat tolerance, immune regulation and behavioral traits. This work provides important insights into the genomic characterization of ecotypes of native chicken in southern China. The identification of candidate genes associated with traits such as disease resistance, heat tolerance, immunomodulation, and behavioral traits is a significant outcome. These candidate genes may contribute to the understanding of the molecular basis of the adaptation of the southern native chicken to the local environment. It is recommended that these genes be integrated into chicken breeding programs to enhance sustainable agriculture and promote effective conservation and utilization strategies.

Genome-wide scans for selection signatures in indigenous pigs revealed candidate genes relating to heat tolerance.

Heat stress is a major problem that constrains pig productivity. Understanding and identifying adaptation to heat stress has been the focus of recent studies, and the identification of genome-wide selection signatures can provide insights into the mechanisms of environmental adaptation. Here, we generated whole-genome re-sequencing data from six Chinese indigenous pig populations to identify genomic regions with selection signatures related to heat tolerance using multiple methods: three methods for intra-population analyses (Integrated Haplotype Score, Runs of Homozygosity and Nucleotide diversity Analysis) and three methods for inter-population analyses (Fixation index (FST), Cross-population Composite Likelihood Ratio and Cross-population Extended Haplotype Homozygosity). In total, 1 966 796 single nucleotide polymorphisms were identified in this study. Genetic structure analyses and FST indicated differentiation among these breeds. Based on information on the location environment, the six breeds were divided into heat and cold groups. By combining two or more approaches for selection signatures, outlier signals in overlapping regions were identified as candidate selection regions. A total of 163 candidate genes were identified, of which, 29 were associated with heat stress injury and anti-inflammatory effects. These candidate genes were further associated with 78 Gene Ontology functional terms and 30 Kyoto Encyclopedia of Genes and Genomes pathways in enrichment analysis (P < 0.05). Some of these have clear relevance to heat resistance, such as the AMPK signalling pathway and the mTOR signalling pathway. The results improve our understanding of the selection mechanisms responsible for heat resistance in pigs and provide new insights of introgression in heat adaptation.

[Predictive value of left ventricular ejection fraction reserve assessed by SPECT G-MPI for major adverse cardiovascular event in patients with coronary artery disease].

Objective: To evaluate the prognostic value of left ventricular ejection fraction (LVEF) reserve assessed by gated SPECT myocardial perfusion imaging (SPECT G-MPI) for major adverse cardiovascular event (MACE) in patients with coronary artery disease. Methods: This is a retrospective cohort study. From January 2017 to December 2019, patients with coronary artery disease and confirmed myocardial ischemia by stress and rest SPECT G-MPI, and underwent coronary angiography within 3 months were enrolled. The sum stress score (SSS) and sum resting score (SRS) were analyzed by the standard 17-segment model, and the sum difference score (SDS, SDS=SSS-SRS) was calculated. The LVEF at stress and rest were analyzed by 4DM software. The LVEF reserve (ΔLVEF) was calculated (ΔLVEF=stress LVEF-rest LVEF). The primary endpoint was MACE, which was obtained by reviewing the medical record system or by telephone follow-up once every twelve months. Patients were divided into MACE-free and MACE groups. Spearman correlation analysis was used to analyze the correlation between ΔLVEF and all MPI parameters. Cox regression analysis was used to analyze the independent factors of MACE, and the optimal SDS cutoff value for predicting MACE was determined by receiver operating characteristic curve (ROC). Kaplan-Meier survival curves were plotted to compare the difference in the incidence of MACE between different SDS groups and different ΔLVEF groups. Results: A total of 164 patients with coronary artery disease [120 male; age (58.6±10.7) years] were included. The average follow-up time was (26.5±10.4) months, and a total of 30 MACE were recorded during follow-up. Multivariate Cox regression analysis showed that SDS (HR=1.069, 95%CI: 1.005-1.137, P=0.035) and ΔLVEF (HR=0.935, 95%CI: 0.878-0.995, P=0.034) were independent predictors of MACE. According to ROC curve analysis, the optimal cut-off to predict MACE was a SDS of 5.5 with an area under the curve of 0.63 (P=0.022). Survival analysis showed that the incidence of MACE was significantly higher in the SDS≥5.5 group than in the SDS<5.5 group (27.6% vs. 13.2%, P=0.019), but the incidence of MACE was significantly lower in the ΔLVEF≥0 group than in theΔLVEF<0 group (11.0% vs. 25.6%, P=0.022). Conclusions: LVEF reserve (ΔLVEF) assessed by SPECT G-MPI serves as an independent protective factor for MACE, while SDS is an independent risk predictor in patients with coronary artery disease. SPECT G-MPI is valuable for risk stratification by assessing myocardial ischemia and LVEF.

[Predictive value of the proportion of hibernating myocardium in total perfusion defect on reverse remodeling in patients with HFrEF underwent coronary artery bypass graft].

Objective: To evaluate the predictive value of the proportion of hibernating myocardium (HM) in total perfusion defect (TPD) on reverse left ventricle remodeling (RR) after coronary artery bypass graft (CABG) in patients with heart failure with reduced ejection fraction (HFrEF) by 99mTc-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) combined with 18F-flurodeoxyglucose (FDG) gated myocardial imaging positron emission computed tomography (PET). Methods: Inpatients diagnosed with HFrEF at the Cardiac Surgery Center, Anzhen Hospital of Capital Medical University from January 2016 to January 2022 were prospectively recruited. MPI combined with 18F-FDG gated PET was performed before surgery for viability assessment and the patients received follow-up MPI and 18F-FDG gated PET at different stages (3-12 months) after surgery. Δ indicated changes (post-pre). Left ventricular end-systolic volume (ESV) reduced at least 10% was defined as RR, patients were divided into reverse remodeling (RR+) group and the non-reverse group (RR-). Binary logistic regression analysis was used to identify predictors of RR. Receiver operating characteristic (ROC) curve analysis was performed and the area under the curve (AUC) was calculated to assess the cut-off value for predicting RR. Additionally, we retrospectively enrolled inpatients with HFrEF at the Cardiac Surgery Center, Anzhen Hospital of Capital Medical University from January 2021 to January 2022 as the validation group, who underwent MPI and 18F-FDG gated PET before surgery. Echocardiography was performed before CABG and after CABG (3-12 months). In the validation group, the reliability of obtaining the cut-off value for the ROC curve was verified. Results: A total of 28 patients with HFrEF (26 males; age (56.9±8.7) years) were included in the prospective cohort. HM/TPD was significantly higher in the RR+ group than in the RR- group ((51.8%±17.9%) vs. (35.7%±13.9%), P=0.016). Binary logistic regression analysis revealed that HM/TPD was an independent predictor of RR (Odds ratio=1.073, 95% Confidence interval: 1.005-1.145, P=0.035). ROC curve analysis revealed that HM/TPD=38.3% yielded the highest sensitivity, specificity, and accuracy (all 75%) for predicting RR and the AUC was 0.786 (P=0.011). Meanwhile, a total of 100 patients with HFrEF (90 males; age (59.7±9.6) years) were included in the validation group. In the validation group, HM/TPD=38.3% predicted RR in HFrEF patients after CABG with the highest sensitivity, specificity and accuracy (82%, 60% and 73% respectively). Compared with the HFrEF patients in the HM/TPD<38.3% group (n=36), RR and cardiac function improved more significantly in the HM/TPD≥38.3% group (n=64) (all P<0.05). Conclusions: Preoperative HM/TPD ratio is an independent factor for predicting RR in patients with HFrEF after CABG, and HM/TPD≥38.3% can accurately predict RR and the improvement of cardiac function after CABG.

[Urine metabolomics study of hepatocellular carcinoma].

Objective: To investigate the urinary small molecular metabolites and their metabolic characteristics of patients with hepatocellular carcinoma (HCC). Methods: High throughput ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was used to detect the small molecular metabolites in urine of healthy control (n=10), patients with hepatic hemangioma (n=10) and patients with HCC (n=10). The orthogonal projections to latent structures-discriminant analysis (OPLS-DA), hierarchical cluster analysis of multivariate analysis and univariate analysis were used to analyze the differential metabolites of the three groups. Results: The metabolic profiles of the three groups showed that the total of 381 differential metabolites were identified and divided into 96 up-regulated metabolites and 285 down-regulated metabolites. There were 55 urinary metabolites specifically related to HCC. Twenty-one of them were significantly up-regulated, including Acetyl-DL-Leucine, Ala Asp, HoPhe-Gly-OH, while 34 were significantly down-regulated, including Selenocystathionine, Met Trp Met Cys, Valsartan acid and so on. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differential metabolites were mainly enriched in glutamine/glutamate metabolism, lysine biosynthesis, tricarboxylic acid cycle and purine metabolism. Conclusions: The occurrence of HCC is accompanied by the abnormalities of multiple metabolites and metabolic pathways. The analysis of the characteristic metabolic profile of urine in patients with HCC is helpful to find metabolic markers and potential therapeutic targets for liver cancer.

[Causal inference methods and its application in the study of health effects of air pollution].

The adverse health effects of air pollution remains a daunting public health problem globally. The research of the health effects of air pollution provides important evidence for ambient air quality standard establishments and air pollution interventions. In recent years, causal inference has been gradually introduced into the observational study of environmental epidemiology, which provides more statistical method options for the study of causal relationships between air pollution and population health effects. Controlling confounders in observational studies is a major challenge for causal inference. This study introduces the causal inference methods for the identification and control of confounding factors currently used in the study of air pollution and population health effects, in order to provide methodological reference and basis for the causal inference study of air pollution and population health effects in China.

[A multicenter, randomized, double-masked, placebo-controlled trial of compound wild chrysanthemum eye masks for mild and moderate dry eye].

Objective: To investigate the clinical efficacy and safety of compound wild chrysanthemum eye masks for mild and moderate dry eye. Methods: In this double-masked, multicenter, placebo-controlled, randomized trial, middle-aged and elderly patients with mild and moderate dry eye were enrolled from six hospitals (Xiamen Eye Center of Xiamen University, China-Japan Friendship Hospital, Peking Union Medical College Hospital, Wangjing Hospital of China Academy of Chinese Medical Sciences, Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine and Hebei Eye Hospital). The patients were assigned to the compound wild chrysanthemum eye mask group and the eye mask simulator group based on the random number table. Subjective symptoms of dry eye, visual acuity, break-up time (BUT), Schirmer Ⅰ test, and corneal fluorescent staining were evaluated in all patients before treatment and at 1 and 2 weeks after treatment. All adverse reactions during the treatment and follow-up were recorded. Results: A total of 120 patients were enrolled. Among them, 112 subjects were included for statistical analyses after the exclusion of 8 subjects who were lost for follow-up or had an adverse event, with an age of (54.26±7.44) years. All the indicators were equally comparable between the two groups. Before treatment and at 1 and 2 weeks after treatment, the median (lower quartile, upper quartile) of total score of questionnaires in the eye mask group was 14.50 (10.00, 19.00), 9.00 (5.00, 14.00) and 7.00 (4.00, 10.00), respectively, and that in the control group was 14.00 (9.00, 22.50), 12.00 (6.00, 20.00) and 10.00 (3.50, 17.00), respectively. The score decreased significantly in both groups after 1 week (t=9.1604, S=398.00; P<0.01) and 2 weeks (S=681.00, 575.50; P<0.05) of treatment. The total score of questionnaires in the eye mask group was significantly lower than that in the control group (Z=3.27, 2.81; P<0.05) after treatment. After 1 week of treatment, the average BUT of the eye mask group was (5.71±2.31) s, which was significantly longer than that before treatment (5.06±2.00) s (S =208.50, P<0.05). But there was no significant difference in the control group (S=150.00, P>0.05). After 2 weeks of treatment, there was statistically significant difference in BUT between the two groups (S=407.00, t=3.07; P<0.01). After 1 week of the treatment, the amount of tear secretion in the eye mask group [(6.88±4.78) mm] was significantly larger than that before treatment (S=196.50, P<0.05), while the control group [(6.80±5.85) mm] showed no significant difference (S=55.00, P<0.05). After 2 weeks of the treatment, the amount increased significantly to (7.43±4.86) mm and (7.29±4.56) mm, respectively, in both groups (t=-3.29, -2.26; P<0.05). The difference in the average BUT, Schirmer Ⅰ test result and corneal fluorescent staining between both groups was not statistically significant at each time point. Five mild adverse events occurred, including 2 adverse events (2 times, 3.51%) in the eye mask group and 3 adverse events (4 times, 5.36%) in the control group. Conclusions: Compound wild chrysanthemum eye masks can effectively improve the symptoms and physical signs of mild and moderate dry eye and can be used as an auxiliary treatment. (Chin J Ophthalmol, 2021, 57: 601-607).

[Often misdiagnosed primary pleural epithelioid hemangioendothelioma: a clinicopathological analysis of five cases].

Objective: To investigate the clinicopathological features, diagnosis and differential diagnosis of primary pleural epithelioid hemangioendothelioma (EHE). Methods: Five cases of pleural EHE diagnosed from 2012 to 2019 in the Shanghai Pulmonary Hospital of Tongji University, China, were collected. They were subjected to review of clinical and image data, reevaluation of histological sections, immunohistochemistry study, clinical follow up and literature review. Results: There were 1 male and 4 females (male to female ratio of 1∶4). The age ranged 19‒58 years, with a median age of 52 years. There was no smoking history in all 5 cases. Clinical manifestations included chest distress, chest pain, cough and hemoptysis. CT scan showed pleural effusion, pleural thickening, multiple pleural nodules and pneumothorax. All of the 5 cases were diagnosed based on thoracoscopic biopsies, which were performed for the suspicion of malignancy in 3 cases and for the suspicion of tuberculosis upon the failure of anti-tuberculosis treatment in 2 cases. Histologically, the tumors grew in the mesenchyme, forming cords, nests and solid sheets. The tumor cells were round, oval, short spindle, and polygonal in shape. They were epithelioid and had abundant cytoplasm and prominent nucleoli. Blister cells (vacuoles in cytoplasm) could be seen, and for mednewly-generated vessel lumen. Mucoid degeneration and collagenization were common in the tumor stroma. The positive-stainin grate was 5/5 for vimentin, 5/5 for D2-40, 4/5 for CD31, 4/5 for ERG, 4/5 for CAMTA1, 2/5 for CD34 and 2/5 for CKpan. WT1, calretinin and CK5/6 were all negative. The follow-up time ranged from 4‒18 months. During the follow-up, 4 patients were treated with chemotherapy (2 patients died, and 2 survived with tumor), and 1 patient lost to the follow-up. Conclusions: Primary pleural EHE is rare. Its imaging and clinical features are very similar to those of tuberculosis. The correct diagnosis relies on pathological biopsy. Tumor cells are epithelioid. When CD34 is negative and D2-40 is positive, it is easy to be misdiagnosed as malignant mesothelioma. The combination of CD31, ERG and CAMTA1, which have high specificity of EHE, is helpful for the differential diagnosis.

[Association between brain glucose metabolism and cardiac dysfunction in patients with ischemic heart disease undergoing (18)F-FDG PET/CT imaging].

Objective: To evaluate the relationship between the brain glucose metabolism and left ventricular function parameters, and to explore the cerebral glucose metabolism reduction regions in patients with ischemic heart disease (IHD). Methods: A total of 110 consecutive IHD patients who underwent gated (99)Tc(m)-sestamibi (MIBI) SPECT/CT myocardial perfusion imaging, gated (18)F-fluorodeoxyglucose (FDG) PET/CT myocardial and brain glucose metabolic imaging within three days in Beijing Anzhen Hospital from April 2016 to October 2017, were enrolled in this study. Left ventricular functional parameters of SPECT/CT and PET/CT including end-diastolic volume (EDV), end-systolic volume (ESV) and left ventricular ejection fraction (LVEF) were analyzed by QGS software. Viable myocardium and myocardial infarction region were determined by 17-segment and 5 score system, and the ratio of viable myocardium and scar myocardium was calculated. According to the range of viable myocardium, the patients were divided into viable myocardium<10% group (n=44), viable myocardium 10%-<20% group (n=36) and viable myocardium≥20% group (n=30). Pearson correlation analysis was used to analyze the correlation between the range of viable myocardium and scar myocardium and the level of cerebral glucose metabolism. Brain glucose metabolism determined by the mean of standardized uptake value (SUV(mean)) was analyzed by SPM. The ratio of SUV(mean) in whole brain and SUV(mean) in cerebellum were calculated, namely taget/background ratio (TBR). Differences in cerebral glucose metabolism among various groups were analyzed by SPM. Results: There were 101 males, and age was (57±10) years in this cohort. The extent of viable myocardium and the extent of scar, LVEF evaluated by SPECT/CT and PET/CT were significantly correlated with TBR (r=0.280, r=-0.329, r=0.188, r=0.215 respectively,all P<0.05). TBR value was significantly lower in viable myocardium<10% group, compared with viable myocardium 10%-<20% group (1.25±0.97 vs. 1.32±0.17, P<0.05) and viable myocardium≥20% group (1.25±0.97 vs. 1.34±0.16, P<0.05). Furthermore, in comparison with viable myocardium≥20% group, the hypo-metabolic regions of viable myocardium<10% group were located in the precuneus, frontal lobe, postcentral gyrus, parietal lobe, temporal lobe, and so on. Conclusions: There is a correlation between impaired left ventricular function and brain glucose metabolism in IHD patients. In IHD patients with low myocardial viability, the level of glucose metabolism in the whole brain is decreased, especially in the brain functional areas related to cognitive function.

Doping effect and fluorescence quenching mechanism of N-doped graphene quantum dots in the detection of dopamine.

Element doping is recognized as a powerful way to modify surface defect structure and further enhance the fluorescence performance of graphene quantum dots (GQDs). N-doped, S-doped and S, N co-doped GQDs were synthesized to explore the influence of element doping on fluorescence sensing of dopamine (DA) biomolecules. Two interesting works are found, one is that the N-doped GQDs with urea as N source are more effective than the S-doped and S,N co-doped GQDs, characterized by the higher quantum yield (QY) up to 78% and sensitive fluorescence quenching performance to DA. The other is that the N-doped GQDs with ethylenediamine as N source have the highest QY up to 95%, however, exhibits no quenching performance to DA. This abnormal observation is discussed based on the microstructure analysis. Under the optimal reaction condition, the N-doped GQDs exhibit a dual linear relationship of quenching intensity with DA concentration in the range of 10-3000 nM and 3000-7000 nM with detection limits of 3.3 and 611 nM, respectively. The quenching mechanism of N-doped GQDs toward DA is explored from the view of N chemical states, biomolecule structure of DA homologues and redox reaction of DA.

The SNP-set based association study identifies ITGA1 as a susceptibility gene of attention-deficit/hyperactivity disorder in Han Chinese.

Genome-wide association studies, which detect the association between single-nucleotide polymorphisms (SNPs) and disease susceptibility, have been extensively applied to study attention-deficit/hyperactivity disorder (ADHD), but genome-wide significant associations have not been found yet. Genetic heterogeneity and insufficient genomic coverage may account for the missing heritability. We performed a two-stage association study for ADHD in the Han Chinese population. In the discovery stage, 1033 ADHD patients and 950 healthy controls were genotyped using both the Affymetrix Genome-Wide Human SNP Array 6.0 and the Illumina Infinium HumanExome BeadChip. The genotyped SNPs were combined to generate a powerful SNP set with better genomic coverage especially for the nonsynonymous variants. In addition to the association of single SNPs, we collected adjacent SNPs as SNP sets, which were determined by either genes or successive sliding windows, to evaluate their synergetic effect. The candidate susceptibility SNPs were further replicated in an independent cohort of 1441 ADHD patients and 1447 healthy controls. No genome-wide significant SNPs or gene-based SNP sets were found to be associated with ADHD. However, two continuous sliding windows located in ITGA1 (P-value=8.33E-7 and P-value=8.43E-7) were genome-wide significant. The quantitative trait analyses also demonstrated their association with ADHD core symptoms and executive functions. The association was further validated by follow-up replications for four selected SNPs: rs1979398 (P-value=2.64E-6), rs16880453 (P-value=3.58E-4), rs1531545 (P-value=7.62E-4) and rs4074793 (P-value=2.03E-4). Our results suggest that genetic variants in ITGA1 may be involved in the etiology of ADHD and the SNP-set based analysis is a promising strategy for the detection of underlying genetic risk factors.

Development of the radial neutron camera system for the HL-2A tokamak.

A new radial neutron camera system has been developed and operated recently in the HL-2A tokamak to measure the spatial and time resolved 2.5 MeV D-D fusion neutron, enhancing the understanding of the energetic-ion physics. The camera mainly consists of a multichannel collimator, liquid-scintillation detectors, shielding systems, and a data acquisition system. Measurements of the D-D fusion neutrons using the camera have been successfully performed during the 2015 HL-2A experiment campaign. The measurements show that the distribution of the fusion neutrons in the HL-2A plasma has a peaked profile, suggesting that the neutral beam injection beam ions in the plasma have a peaked distribution. It also suggests that the neutrons are primarily produced from beam-target reactions in the plasma core region. The measurement results from the neutron camera are well consistent with the results of both a standard (235)U fission chamber and NUBEAM neutron calculations. In this paper, the new radial neutron camera system on HL-2A and the first experimental results are described.

Inhibitory effects of a dendritic cell vaccine loaded with radiation-induced apoptotic tumor cells on tumor cell antigens in mouse bladder cancer.

Herein, the preparation of a dendritic cell (DC) vaccine with radiation-induced apoptotic tumor cells and its immunological effects on bladder cancer in C57BL/6 mice was investigated. We used radiation to obtain a MB49 cell antigen that was sensitive to bone marrow-derived DCs to prepare a DC vaccine. An animal model of tumor-bearing mice was established with the MB49 mouse bladder cancer cell line. Animals were randomly allocated to an experimental group or control group. DC vaccine or phosphate-buffered saline was given 7 days before inoculation with tumor cells. Each group consisted of 2 subgroups in which tumor volume and the survival of tumor-bearing mice were recorded. Tumor volumes and average tumor masses of mice administered DC vaccine loaded with radiation-induced apoptotic cells were significantly lower than those in the control group (P < 0.01). Survival in the experimental group was also longer than that in the control group, and 2 mice survived without tumor formation. In the DC vaccine group, 2 mice were alive without tumor growth after 30 days, and no tumor was observed at 30 days after subcutaneous inoculation of MB49 cells. The DC vaccine loaded with radiation-induced apoptotic tumor cells had an anti-tumor effect and was associated with increased survival in a bladder cancer model in mice.

Design of a magnetic shielding system for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak.

The novel neutron spectrometer TOFED (Time of Flight Enhanced Diagnostics), comprising 90 individual photomultiplier tubes coupled with 85 plastic scintillation detectors through light guides, has been constructed and installed at Experimental Advanced Superconducting Tokamak. A dedicated magnetic shielding system has been constructed for TOFED, and is designed to guarantee the normal operation of photomultiplier tubes in the stray magnetic field leaking from the tokamak device. Experimental measurements and numerical simulations carried out employing the finite element method are combined to optimize the design of the magnetic shielding system. The system allows detectors to work properly in an external magnetic field of 200 G.

Data acquisition system with pulse height capability for the TOFED time-of-flight neutron spectrometer.

A new time-of-flight neutron spectrometer TOFED has been constructed for installation at Experimental Advanced Superconducting Tokamak. A data acquisition system combining measurements of flight time and energy from the interaction of neutrons with the TOFED scintillators has been developed. The data acquisition system can provide a digitizing resolution better than 1.5% (to be compared with the >10% resolution of the recoil particle energy in the plastic scintillators) and a time resolution <1 ns. At the same time, it is compatible with high count rate event recording, which is an essential feature to investigate phenomena occurring on time scales faster than the slowing down time (≈100 ms) of the beam ions in the plasma. Implications of these results on the TOFED capability to resolve fast ion signatures in the neutron spectrum from EAST plasmas are discussed.

Light output function and assembly of the time-of-flight enhanced diagnostics neutron spectrometer plastic scintillators for background reduction by double kinematic selection at EAST.

The 2.5 MeV neutron spectrometer TOFED (Time-Of-Flight Enhanced Diagnostics) has been constructed to perform advanced neutron emission spectroscopy diagnosis of deuterium plasmas on EAST. The instrument has a double-ring structure which, in combination with pulse shape digitization, allows for a dual kinematic selection in the time-of-flight/recoil proton energy (tof/Ep) space, thus improving the spectrometer capability to resolve fast ion signatures in the neutron spectrum, in principle up to a factor ≈100. The identification and separation of features from the energetic ions in the neutron spectrum depends on the detailed knowledge of the instrument response function, both in terms of the light output function of the scintillators and the effect of undesired multiple neutron scatterings in the instrument. This work presents the determination of the light output function of the TOFED plastic scintillator detectors and their geometrical assembly. Results from dedicated experiments with γ-ray sources and quasi-monoenergetic neutron beams are presented. Implications on the instrument capability to perform background suppression based on double kinematic selection are discussed.

Design of the radiation shielding for the time of flight enhanced diagnostics neutron spectrometer at Experimental Advanced Superconducting Tokamak.

A radiation shielding has been designed to reduce scattered neutrons and background gamma-rays for the new double-ring Time Of Flight Enhanced Diagnostics (TOFED). The shielding was designed based on simulation with the Monte Carlo code MCNP5. Dedicated model of the EAST tokamak has been developed together with the emission neutron source profile and spectrum; the latter were simulated with the Nubeam and GENESIS codes. Significant reduction of background radiation at the detector can be achieved and this satisfies the requirement of TOFED. The intensities of the scattered and direct neutrons in the line of sight of the TOFED neutron spectrometer at EAST are studied for future data interpretation.