Objective To develop a large-volume sample cassette in the shape of a formalin cup suitable for portable HPGe γ spectrometer, to determine the detection limits of the cassette at different detection times through fresh sample measurements, and to provide a reference for responding to and monitoring of nuclear and radiation emergencies. Methods According to the formula for calculation of detection limit described in the GB/T 16145—2022, ¹³¹I and ¹³⁷Cs were measured using the sourceless efficiency calibration software Angle and the portable HPGe γ spectrometer for the optimization of the large-volume sample cassette. Fresh salmon samples were measured using a formalin cup-shaped large-volume sample cassette. The detection times were 2, 4, 6, 8, 10, 19, 19, 22, and 24 hours. The relationship between detection time and detection limit was assessed. Results Using sample cassettes with 15 cm radius and 10 L volume, the simulated detection efficiency of the formalin cup-shaped large-volume sample cassette was 30%-46% higher and the detection limit was lower as compared with the cake-shaped large-volume sample cassette. The detection limit obtained by measuring fresh salmon samples decreased with the extension of the detection time. These results provided a reference for the detection limits of measuring fresh samples for nuclides of concern in nuclear contaminated water with different detection times. Conclusion The formalin cup-shaped large-volume sample cassette developed by combining the optimization of detection limit provides a geometry for quantitative analysis in on-site monitoring of γ nuclides in the case of emergencies. Measurement of fresh samples using the cassette with different detection times showed that 8-10 hours of detection was optimal in balancing the detection limit and the detection time.

Objective To further extend the application of coincidence summing correction factor transfer experiments through the analysis of relevant measurements. Methods The passive efficiency was simulated using BE5030 high-purity germanium (HPGe) γ-energy spectrometer equipped with LabSOCS, and the total efficiency was simulated using LabSOCS in GENIE 2000 spectrum analysis software, which was used for calculating the coincidence summing correction factor. The coincidence summing correction factor transfer experiments were performed using the measurements with the point source containing ¹³⁴Cs, ⁶⁰Co, and ¹³⁷Cs as well as the body source to obtain the coincidence summing correction factors of other HPGe γ-energy spectrometers. Results The coincidence summing correction factors for ¹³⁴Cs and ⁶⁰Co were obtained using the BE5030 γ-energy spectrum. In verification by certificate activity, the absolute value of the maximum deviation was within 3.53%. Using coincidence summing correction factor transfer experiments, these factors were transferred to other high-purity germanium γ spectrometers. In verification by certificate activity, the absolute value of the maximum deviation was within 5.86%. Conclusion The coincidence summing correction factors calculated using simulated total efficiency by calling LabSOCS in the GENIE 2000 spectrum analysis software are effective in correction, and can be used as correction factors in standard laboratories. Through coincidence summing correction factor transfer experiments, the coincidence summing correction of other high-purity germanium γ-energy spectrometers can be achieved, which broadens the application of coincidence summing correction method.

BACKGROUND:Numerous scholars have previously researched certain greater tuberosity fractures and the procedures used to treat them.Few researchers,however,have studied the comminuted split fracture of the greater tuberosity of the humerus(Liu-Gang type IV)with rotator cuff tear in great detail. OBJECTIVE:To compare the clinical therapeutic effect of open repair position modified calcaneal plate combined with suture anchors and proximal humeral internal locking system(PHILOS)plate in the treatment of comminuted fracture of split-type greater tuberosity of humerus combined with rotator cuff tears(Liu-Gang type IV). METHODS:Case data of 30 patients with comminuted fracture of split-type greater tuberosity of humerus combined with rotator cuff tears(Liu-Gang type IV)from May 2012 to May 2022 were retrospectively analyzed.They were divided into the modified calcaneal plate combined with suture anchor group(group A)and the PHILOS with#2 Johnson group(group B),with 15 cases in each group.Intraoperative blood loss,surgical time,and incision length of all patients were recorded.Pain visual analog scale score,Constant-Murley score,as well as shoulder joint abduction,forward flexion,external rotation,and dorsal expansion activities during the last follow-up(>1 year)were evaluated. RESULTS AND CONCLUSION:(1)The surgical incision length and operation time were shorter,and blood loss was less in group A than those in group B(P<0.05).(2)No significant difference in visual analog scale score and Constant-Murley score was detected between the two groups(P>0.05).(3)During the last follow-up,forward flexion in group A was better than that in group B(P<0.05).No significant difference in abduction,external rotation,and dorsal expansion was determined between group A and group B(P>0.05).(4)In terms of complications,there was 1 case of shoulder joint pain and discomfort in group A(7%),2 cases of subacromial impingement syndrome,2 cases of upward movement of nodules,and 2 cases of shoulder joint pain(40%)in group B.There were significant differences in complication rates between the two groups(P=0.031).(5)In summary,the modified calcaneal plate combined with suture anchors in the treatment of comminuted fracture of split-type greater tuberosity of humerus combined with rotator cuff tears(Liu-Gang type IV)could better restore the forward flexion function of the shoulder joint and has a small incision,less blood loss,shorter operation time and fewer complications.

Objective:To recommend reference composition for sourceless efficiency calibration of food gamma spectrometry by analyzing the composition of common foods based on a combination of sourceless efficiency calibration and active validation.Methods:Thirty common types of food samples in countrywide monitoring of radioactively contaminated foods were analyzed to statistically determine the reference composition of grains and vegetables. Combined with the parameters provided for white quinoa standard source, LabSOCS was applied to carry out the simulation of sourceless efficiency for its different compositions, and to calculate its measured activity, and analyzing its relative deviation to the those given in the certificate.Results:The analytical result of these 30 types of food samples showed that the five elements C, H, O, N and S accounted for 77.0%-93.7% of the food composition, being the main component of these samples. By applying white quinoa′s components and grain-based reference components to the simulation of the sourceless efficiency of white quinoa standard sources, the relative deviations of activity calculations to their certificated activities were in the range of 0.37%-5.86% and 0.38%-5.87% in absolute value, respectively.Conclusions:The white quinoa′s composition and the grain reference composition were applied to the sourceless efficiency simulation of the white quinoa standard source, and the relative deviation of the calculated measured activity to the activity of the standard source certificate was basically identical, so that if the gamma spectrometry-based sourceless efficiency simulation is used to measure the unknown composition of the food samples and it is inconvenient to carry out the analysis of the food samples′ compositions, especially in the case of emergency, it can be referred to the use of the reference compositions obtained in the present study.

Objective:To understand the contamination risk, drug resistance and virulence characteristics of cooked food pathogens in Tianjin.Methods:Pathogenic bacteria were isolated and identified in cooked food sold in Tianjin from 2019 to 2021, drug susceptibility test and whole genome sequencing were conducted for the isolates, and multilocus sequence typing, drug resistance gene, phenotype and virulence gene were analyzed for the data.Results:Ten pathogenic bacteria were isolated from 245 cooked food samples collected. The ST types of 7 Salmonella strains were ST40, ST198, ST14, ST13 and ST155. The two strains of Vibrio parahaemolyticus were ST647 and ST2622 respectively. One strain of Cronobacter sakazakii was ST8 type. All the 6 isolates were drug-resistant, and 3 of them were multidrug-resistant (MDR). A total of 63 drug-resistant genes were predicted in 10 isolates. Two Salmonella strains were ampicillin-chloramphenicol-streptomycin-sulfamethoxazole-tetracycline resistant (MDR-ACSSuT), and both Salmonella strains carried gyrA double mutations (S83F, D87N) and parC mutations (S80I). Vibrio parahaemolyticus mainly carries blaCARB and tet (35) genes, while Cronobacter sakazakii carries only one resistance gene blaCSA-1. A total of 163 virulence genes were predicted from 10 isolates. Conclusions:In this study, pathogenic bacteria are repeatedly detected in quail eggs, warning that other eggs besides chicken eggs should also pay special attention to the risk of contamination. The isolates in this study are all of the prevalent ST type with widespread drug resistance, and MDR-ACSSuT strains should be paid attention to. The key role of gyrA double mutation (S83F, D87N) and parC mutation (S80I) in the development of quinolone resistance should not be ignored. T3SS (typeⅢ secretory system) and T6SS (typeⅥ secretory system) are important virulence gene clusters of Salmonella and Vibrio parahemolyticus.

Objective To correct the counting loss of ³⁷Ar below the activity threshold during the measurement of the absolute activity of the inert radioactive gas ³⁷Ar using the proportional counter filled with gas. Methods Monte Carlo simulation with Geant4 was performed to establish a proportional counter model and output the energy deposition spectrum of ³⁷Ar, which were used to simulate and analyze the causes and correction of counting loss. Results The photon detection efficiency was only 38.7% at 60 kPa. The counting loss was mainly caused by the wall effect produced by the photons, which could be reduced by increasing the gas pressure and corrected by extrapolation. The influence of wall effect at 100 kPa was 4.4%, and the deviation between simulation and experiment was < 0.6%. Conclusion A factor could be calculated by Geant4 simulation for the correction of counting loss, thus achieving the accurate measurement of ³⁷Ar activity by proportional counter.

Objective:To compare the clinical effectiveness between arthroscopic hollow screws combined with a suture anchor, hollow screws and proximal humerus internal locking system (PHILOS) in the treatment of split-type fractures of humeral greater tuberosity.Methods:A retrospective study was conducted to analyze the 54 patients with split-type fracture of humeral greater tuberosity who had been admitted to Department of Joint Surgery, Hospital of Traditional Chinese Medicine, Affiliated to Southwest Medical University from May 2015 to August 2020. There were 17 males and 37 females with an age of (58.4±12.1) years. According to different treatment methods, they were divided into 3 groups. Group A of 18 cases was treated with arthroscopic hollow screws combined with a suture anchor, group B of 18 cases with hollow screws, and group C of 18 cases with PHILOS. The length of surgical incision, and range of shoulder motion, visual analogue scale (VAS), and American Shoulder and Elbow Surgeons (ASES) score at the last follow-up were recorded and compared between the 3 groups.Results:There was no statistically significant difference in the preoperative general information between the 3 groups, indicating the 3 groups were comparable ( P>0.05). The surgical incision in group A [(0.7±0.1) cm] was the shortest, followed by (5.0±1.4) cm in group B, and (12.8±2.1) cm in group C, showing statistically significant differences in pairwise comparison ( P<0.05). In the 3 groups at the last follow-up, respectively, the shoulder forward flexion was 159.7°±13.4°, 154.9°±16.2°, and 160.5°±12.9°, and the shoulder abduction 149.6°±11.3°, 142.4°±12.0°, and 145.1°±10.4°, showing no statistically significant difference among the 3 groups ( P>0.05); the external rotation was 41.1°±8.1°, 38.1°±7.8° and 43.7°±6.2°, showing a statistically significant difference between groups B and C ( P<0.05); the dorsal extension was T 12 (L 5 to T 6), T 12 (L 5 to T 7), and T 12 (L 3 to T 6), showing no statistically significant difference among the 3 groups ( P>0.05). There was no statistically significant difference among the 3 groups in the VAS score or ASES score at the last follow-up ( P>0.05). Respectively, there were 2, 6, and 4 patients in groups A, B and C who developed complications, showing statistically significant differences between the 3 groups ( P<0.05). Conclusions:In the treatment of split fractures of humeral greater tuberosity, arthroscopic hollow screws combined with a suture anchor, hollow screws and PHILOS can all relieve pain and restore joint function of the shoulder. However, arthroscopic hollow screws combined with a suture anchor are the most recommendable due to their advantages in minimally invasiveness and reduction in complications.

Objective:To measure the influencing factors associated with the analysis of 226Ra gamma spectra in order to obtain more acurate and precise measuring result on a basis of further optimizing the gamma spectrometry method for 226Ra activity. Methods:A laboratory-based HPGe gamma spectrometer was used to carry out the studies on tracking measurement of sample sealing time, measurement of background fluctuation with lead shielding, analytical method, and selection of characteristic gamma ray energy peak of its daughter nuclides in 226Ra measurement. Results:After the sample was sealed for 12 d, the decay products of 226Ra- 222Rn basically reached equilibrium. The day and night fluctuations of 222Rn in the shielded lead room were obvious but had no obvious regularity. The way of filling nitrogen into the shielded lead room could reduce or avoid the influence of background fluctuations. For 31 soil samples measured after 23 days of sealing, the result of using the efficiency curve method showed that the 226Ra result calculated from the 351.9 keV energy peak were generally higher than the 609.3 keV energy peak, and the higher ratio ranged from 8.0% to 20.7%. The result of relative comparison method showed that the deviation ratio of the two peaks ranged from -4.1 % to 10.3 %. Conclusions:It is recommended to consider the uncertainty attributed from decay equilibrium about 4 % of measured at 12 d after the sample is sealed. When filling nitrogen through the shielded lead chamber to avoid background fluctuations, attention must be paid to the matching relationship between the volume of the lead chamber and the nitrogen filling flow. When the efficiency curve method is used to analyze the activity of 226Ra, the 214Bi ( 609.3 keV ) energy peak has the effect of cascade coincidence addition, so 214Bi(609.3 keV) energy peak should be avoided. When the relative comparison method is used to analyze the activity of 226Ra, both two energy peaks of 214Pb ( 351.9 keV ) and 214Bi ( 609.3 keV ) can be used.

Objective To optimize the Marinelli beaker with the simulation of Laboratory Sourceless Object Calibration Software (LabSOCS), to investigate the detection efficiency of HPGe detector in measuring noble gas, and to provide a reference for the measurement and optimization of noble gas effluent from nuclear power plants. Methods LabSOCS was used to establish a Marinelli beaker model to investigate the relationship of gamma ray detection efficiency of noble gas with gas components, gas density, size and volume of the Marinelli beaker, and the shape of source container. Results The gas components had little effect on the detection efficiency of the noble gas in the Marinelli beaker. The gas density had a relatively great effect on the detection efficiency of low-energy gamma ray. The Marinelli beaker of appropriate height and radius enabled the HPGe detector to get better measurement results. For the BE5030 HPGe detector, the highest detection efficiency of the Marinelli beakers of different volumes were observed at the location where the radius/height ratio was 0.7, and the optimal values of height and radius were given for the Marinelli beakers of different volumes. Conclusion Choosing Marinelli beaker of the appropriate size can improve the detection efficiency of noble gas in the effluent from nuclear power plants.

Objective To apply InSpector 1000 portable γ spectrometer and its corresponding supporting software to the monitoring of thyroid ¹³¹I activity of radiation workers, and to estimate the internal radiation dose of medical staff in nuclear medicine department. Methods The spectrometer was calibrated and taken to participate in the 2018 thyroid radioactive iodine intercomparison program initiated by Lawrence Livermore National Laboratory in the United States to ensure the accuracy of the measurement; the spectrometer was used to measure ¹³¹I activity ofthe radiation workers of the nuclear medicine departments of two grade-A tertiary hospitals in Beijing and Jinan to verify the feasibility of the method. Results The InSpector 1000 portable γ spectrometer was qualified for international intercomparison. Measurement results from the grade-A tertiary hospital in Beijing showed that the thyroid ¹³¹I activity of each of 10 radiation workers was below the detection limit (33.30 Bq). Measurement results from the grade-A tertiary hospital in Jinan showed that the thyroid ¹³¹I activities of the 4 radiation workers were 64.05 Bq, 160.77 Bq, 416.67 Bq, below the detection limit (35.18 Bq) respectively, and of 3 of the 4 subjects ¹³¹I was detected in the thyroid, and their corresponding thyroid accumulative organ doses were 0.70 μSv, 1.77 μSv, and 4.58 μSv, respectively. Conclusion InSpector 1000 portable γ spectrometer has a strong feasibility for thyroid ¹³¹I monitoring of radiation workers in nuclear medicine. The spectrometer has a good application prospect in the field of radiation monitoring, and can play an important role in the field of radiation protection and nuclear emergency detection.