氟化锂热释光探测器的剂量性能研究

目的 :了解我站使用的热释光探测器的剂量性能。方法 :使用热释光探测器为氟化锂 (LiF :Mg·Cu·P) ,经FJ 411型热释光退火炉 2 5 0℃退火后 ,封装在小塑料管中作为探测元件 ,元件经上海市计量测试研究院标准辐射场辐照 ,参照国家卫生标准GB 10 2 64 88规定的方法 ,用FJ 42 7A型热释光剂量仪测读。结果 :探测器探测阈、线性度 (剂量响应 )、能量响应、一批均匀性均可满足国家卫生标准GB 10 2 64 88的要求。结论 :我站使用的氟化锂 (LiF :Mg·Cu·P)

FJL-01 型三醋酸纤维素薄膜剂量计剂量学性能研究

研究了ＦＪＬ－０１型三醋酸纤维素薄膜剂量计的剂量学性能，并与国外同类产品作了比较。对于电子束辐照，ＦＪＬ－０１剂量计具有良好的剂量响应线性，Ｋ值稳定；剂量计量程为１０－３００ｋＧｙ；测量吸收剂量的总不确定度为８％（ｋ＝２）。

^(60)Coγ刀剂量性能的测量验证

６０Ｃｏγ刀剂量性能的测量验证周汝信张之彬王肖兰徐涛周建国为发展我国大型放射治疗设备，由深圳沃发医学新技术发展公司研制的国产第一台动态旋转聚焦式６０Ｃｏγ刀（ＯＵＲ－ＸＧＤ），根据立体定向原理，对人头颅内病变组织选择性地确定靶点，使用一次大剂量γ射线...

辐射变色薄膜剂量计的研制

以尼龙为基材、六羟基乙基副品红氰化物(hexahydroxyethyl pararosaniline cyanide,HPR-CN)为染料研制辐射变色薄膜剂量计。文章描述了该剂量计的工作原理、配方、物理性能及其剂量学性能测试结果。实验测试表明,自制的辐射变色薄膜剂量计具有较好的剂量学性能。文章对自制的辐射变色薄膜剂量计的性能与FWT-60辐射变色薄膜剂量计的性能进行了比较。

国产氟化锂片型热释光探测器性能比较研究

本文报道了对常用国产ＬｉＦ（Ｍｇ，Ｃｕ，Ｐ）和ＬｉＦ（Ｍｇ，Ｔｉ）两类片型热释光探测器的６种产品进行剂量学性能比较研究的结果。根据国家标准“个人和环境监测用热释光剂量测量系统”（ＧＢ１０２６４－８８）的技术要求和实际需要，比较了这几种探测器的热释发光曲线、相对灵敏度、探测阈、线性度、光子能量响应、一批的均匀性、重复性和稳定性等剂量学特性。

眼晶体、指环剂量计的部分剂量学性能实验测试研究

目的比较国产与进口眼晶体、指环剂量计的部分性能测试结果,掌握眼晶体、指环剂量计的部分剂量学性能指标。方法依据IEC 62387—2012和GBZ 128—2019中性能要求,分别使用国产和进口热释光探测器开展了眼晶体剂量计和指环剂量计在光子响应下的性能对比实验;测试进口眼晶体和指环剂量计在相同照射条件下照射2次的剂量响应偏差;测试进口指环剂量计和国产指环剂量计在相同照射条件下的线性响应区别。结果在眼晶体和指环剂量计中分别使用国产热释光探测器和进口热释光探测器照射相同剂量,线性相关系数均满足R^(2)>0.999;进口眼晶体剂量计和指环剂量计2次照射相同剂量的响应偏差最大值均小于10.0%。两种进口指环剂量计和一种国产指环剂量计照射相同剂量线性相关系数均满足R^(2)>0.99。结论国产探测器和进口探测器均能满足监测需要;进口指环剂量计和国产指环剂量计线性响应区别不明显;进口眼晶体剂量计和进口指环剂量计重复性满足剂量计的性能要求。

Adsorption/reaction energetics measured by microcalorimetry and correlated with reactivity on supported catalysts: A review

The formations and transformations of the chemical bonds of reactants and intermediates on cata- lyst surfaces occur in conjunction with the evolution of heat during catalytic reactions. Measure- ment of this evolved heat is helpful in terms of understanding the nature of the interactions be- tween the catalyst and the adsorbed species, and provides insights into the reactivity of the catalyst. Although various techniques have previously been applied to assessments of evolved heat, direct measurements using a Tian-Calvet microcalorimeter are currently the most reliable method for this purpose. In this review, we summarize the relationship between the adsorption/reaction energetics determined by microcalorimetry and the reactivities of supported catalysts, and examine the im- portant role of microcalorimetry in understanding catalytic performance from the energetic point of view.

Coagulation behavior of polyaluminum chloride: Effects of pH and coagulant dosage

Coagulation mechanisms of polyaluminum chloride(PACl) at various dosages were studied using a conventional jar test at different final and initial pH values during treating kaolin suspension. The optimal final pH and dosages for PACl were obtained based on residual turbidity and zeta potential of flocs. The coagulation zones at various PACl dosages and solution p H values were developed and compared with those of alum. It is found that the optimal mechanism under acidic condition is charge neutralization, while alkaline condition will facilitate the coagulation of PACl. Both charge neutralization coagulation and sweep coagulation can achieve high coagulation efficiency under the alkaline condition ranging from final p H 7.0 to 10.0. Stabilization, charge neutralization destabilization, restabilization and sweep zones occur successively with increasing PACl dosages with the final p H values fixed at 7.0 and 8.0, but restabilization zone disappears at final p H 10.0. When the final p H is not controlled and consequently decreases with increasing PACl dosage, no typical sweep zone can be observed and the coagulant efficiency decreases at high PACl dosage. It seems that the final pH is more meaningful than the initial p H for coagulation. Charge neutralization coagulation efficiency is dominated by zeta potential of flocs and PACl precipitates. The charge neutralization and sweep coagulation zones of PACl are broader in the ranges of coagulant dosage and p H than those of alum. The results are helpful for us to treat water and wastewater using PACl and to understand the coagulation process of PACl.

Seven National Standards on Occupational Health Released

Seven national standards on occupational health have been released by National Health and Family Planning Commission of China recently, including 4 mandatory standards including GBZ 106-2016, Diagnosis for occupational radiation injuries of skin, GBZ 128-2002, Specification of individual monitoring for occupational external exposure, GBZ 129-2002, Specification of individual monitoring for occupational internal exposure, GBZ 207-2008, Testing criteria of personnel dosimetry performance, as well as 3 voluntary standards including GBZ/T 269-2016, Specification for radioactivity testing of total a and total 13 in urine, GB/T 18198- 2000, Estimation standards of personal cumulative exposure to radon decay products for miners, GBZ/T 271-2016, Criteria for use in preparedness and for a nuclear or radiological emergency, which will be implemented from November 1, 2016.

Relationship between impact of dose distribution and energy of radioactive ray for metal contraceptive ring

Objective： We studied the relationship between impact of dose distribution and energy of radioactive ray in teletherapy with contraceptive ring. Methods： The SI Virtual Water Phantom was used to monitor medium of dose. PTW ionization chamber was used to detect the dose. AP-PA （10 cmx 10 cm） and SAD technique were adopted. Monitoring dose of different locations with different energy of radioactive ray in AP and PA respectively with and without contraceptive ring, repeated 5 times. Results： Dose of with contraceptive ring was lower than that of without contraceptive ring in AP 6 MV- X-ray （P 〈 0.05）, while in PA was no obvious difference （P 〉 0.05）. Dose of except for the center was higher than that of without contraceptive ring in AP and PA 15 MV-X-ray （P 〈 0.05）. For locations, doses of the upper, the left and right were higher than that of the center in AP 6 MV-X-ray （P 〈 0.05）, while in PA was lower （P 〉 0.05）. In AP and PA 15 MV-X-ray, doses of the upper, the left and right was higher than that of the center （P 〈 0.05）. Conclusion： Metallic contraceptive ring would effect the dose distribution of radioactive ray, but influence degree related to locations of contraceptive ring and energy of radioactive ray.

Synthesis and evaluation of carbon nanotubes composite adsorbent for CO2 capture： a comparative study of CO2 adsorption capacity of single-walled and multi-walled carbon nanotubes

As a preliminary investigation towards obtaining carbon nanotube composite adsorbent for CO2 capture, in this study CO2 adsorption performance of three commercial carbon nanotubes （CNTs） one single-walled carbon nanotubes （SWCNTs）, and two （2） different multi-walled carbon nanotubes （referred to as A-MWCNTs and B-MWCNTs） were evaluated and compared. The purpose of this study was to compare the different types of CNTs and select the best to serve as the solid anchor in the development of a hydrophobic composite adsorbent material for CO2 capture. The N2 physi- sorption of the CNTs was conducted to determine their surface area, pore volume and pore size. In addition, morphology and purity of the CNTs were checked with Transmission Electron Microscopy and Raman Spectroscopy, respectively. The CO2 adsorption capacity of the CNTs was evaluated using Thermo-gravimetric analysis （TGA） at 1.1 bar, at operating temperature ranged from 25 to 55 ~C and at different CO2 feed flow rates, in order to evaluate the effects of these variables on the CO2 adsorption capacity. The results of CO2 adsorption with the TGA show that CO2 adsorption capacity for both SWCNTs and MWCNTs was the highest at 25 ~C. Changing the CO2 flowrates had no significant effect on the adsorption capacity of MWCNTs, but decreasing the CO2 flow rate resulted in the enhancement of the CO2 adsorption capacity of SWCNTs. Overall, it was found that the SWCNTs displayed the highest CO2 adsorption capacity （29.97 gCO2/kg ad- sorbent） when compared to the MWCNTs （12.09 gCO2/kg adsorbent）, indicating a 150% increase in adsorption capacity over MWCNTs.

Evaluating the influence of 6 MV and 15 MV photon beams on prostate intensity-modulated radiation therapy plans

Objective We aimed to determine the ef ects of low- and high-energy intensity-modulated radiation therapy （IMRT） photon beams on the target volume planning and on the critical organs in the case of prostate can-cer. Methods Thirty plans were generated by using either 6 MV or 15 MV beams separately, and a combination of both 6 and 15 MV beams. Al plans were generated by using suitable planning objectives and dose con-straints, which were identical across the plans, except the beam energy. The plans were analyzed in terms of their target coverage, conformity, and homogeneity, regardless of the beam energy. Results The mean percentage values of V70 Gy for the rectal wal for the plans with 6 MV, 15 MV, and mixed-energy beams were 16.9%, 17.8%, and 16.4%, respectively, while the mean percentage values of V40 Gy were 53.6%, 52.3%, and 50.4%. The mean dose values to the femoral heads for the 6 MV, 15 MV, and mixed-en-ergy plans were 30.1 Gy, 25.5 Gy, and 25.4 Gy, respectively. The mean integral dose for the 6 MV plans was 10% larger than those for the 15 MV and mixed-energy plans.Conclusion These preliminary results suggest that mixed-energy IMRT plans may be advantageous with respect to the dosimetric characteristics of low- and high-energy beams. Although the reduction of dose to the organs at risk may not be clinical y relevant, in this study, IMRT plans using mixed-energy beams exhibited better OAR sparing and overal higher plan quality for deep-seated tumors.

Comparison between Conventional and Improved Gas Engine-Driven VRF under Same Climate Conditions

This paper reports the on-site performance evaluation of conventional and improved gas engine-driven VRF （variable refrigerant flow） units and （abbreviated as GHP） units. The study aims to elucidate two actual GHP units by using the probe insertion method. There is a tendency to decrease energy efficiency compared to a high loading factor. GHP operation was almost all part load operation. This on-site evaluation indicates a clear difference between conventional and improved GHP.

Relative floatability as a criterion for evaluating the separation performance of phosphate from iron

This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impurities. The effects of pulp pH, solid content, reagents dosage(depressant, collector and co-collector) and conditioning time were investigated on the ratio of the modified rate constant of phosphate to the modified rate constant of iron(relative floatability). The results showed that a large dosage of depressant associated with a low value of collector resulted in a better relative floatability. Increasing the co-collector dosage, conditioning time and pH increased the relative floatability up to a certain value and thereafter resulted in diminishing the relative floatability. Meanwhile, the results indicated that increment of solid concentration increased the relative floatability in range investigated. It was also found that that maximum relative floatability(16.05) could be obtained in pulp pH, 9.32, solid percentage, 30,depressant dosage, 440 g/t, collector dosage, 560 g/t, co-collector dosage, 84.63 g/t and conditioning time,9.43 min.

Performance of dual-source CT with high pitch spiral mode for coronary stent patency compared with invasive coronary angiography

Objective To investigate the performance of dual-source computed tomography （DSCT） using high-pitch spiral fliPS） mode for coronary stents patency. Methods We conducted a prospective study on 120 patients with 260 previous stents implanted due to recurred suspicious symptoms of angina scheduled for invasive coronary angiography （ICA）, while DSCT were conducted using HPS mode. Results There was no significant impact of age, body mass index or heat rate （HR） on image quality （P 〉 0.05）, while HR variability had a slight impact on that （P 〈 0.05）. Sensitivity, specificity, positive predictive value （PPV）, negative predictive value （NPV） of DSCT in detection of in-stent restenosis （ISR） based per-patient were 92.3%, 96.7%, 88.9%, and 97.8%, respectively. And those based per-stent were 87%, 96.8%, 83.3%, and 97.7% with un-assessment stents, 97.4%, 99.5%, 97.4%, and 99.5% without un-assessment stents. There was significant differ- ence on sensitivity, specificity, PPV and NPV between diameter 〉 3.0 mm group （93.3%, 97.9%, 87.5%, and 98.9%） and diameter 〈 3.0 mm group （80%, 93.3%, 80.0%, and 93.3%） （P 〈 0.05）, and that between stent number 〉 3 group （82.3%, 77.8%, 66.7%, and 60%） with 〈 3 group （97.3%, 80%, 96.5%, and 75%）. The effective dose of DSCT （1.4 ± 0.5 mSv） is significantly less than that by invasive coronary angiography [4.0 ± 0.8 mSv （P 〈 0.01）]. Conclusion DSCT using HPS mode provides good diagnostic performance on stent patency with lower effective dose in patients with HR 〈 65 beats/rain.

Investigation of MQL-Employed Hard-Milling Process of S60C Steel Using Coated-Cermented Carbide Tools

The application of cutting fluids in machining brings out many benefits, but their use is accompanied by health and enviroment hazards. MQL （Minimum Quantity Lubricant） has become a preciously alternative solution for lubrication against dry machinning and flood cooling lubricant, and this is a step toward green machining. This paper presents a comprehensively experiemental study on investigation of MQL performance in hard milling of S60C steel for multiple responses, including surface quality, cutting forces and tool wear. Compared to dry milling, even-enhanced surfaces finish quality, 20% less cutting force （Ft） and almost 112% prolonged tool lifetime are achieved by using MQL with 5% Emulsion in hard milling. In addition, this study compared the performances of MQL milling by using 5% Emulsion to the peanut oil completely harmless to the enviroment. This encouraging result, therefore, reveals that the MQL-employed hard milling can enable significant improvement in productivity, product quality, and overall machining economy even after covering the additional cost of designing and implementing MQL system. Moreover, this study also shows the limitation of peanut oils employed in MQL and proposes the further research in novel additives to enhance the performance of cooling lubricant for vegetable oils.

Rheological Properties of Recycled Aggregate Concrete Using Superplasticizers

The mechanical properties of recycled aggregates concrete from demolition have been studied for several years. It has been documented that rheological properties of these concrete are generally affected by use of recycled aggregates. They could present mechanical properties less affected by the presence of recycled aggregates if the initial concrete were of good quality. However, manufacturing problems, mainly attributed to the angular character of these aggregates and to the granulometry of recycled sand, limit their industrial use. The worth point of this study consists in the optimization of the concrete formulation using specific admixture, adapted to this aggregates in order to facilitate its manufacturing. It shows that the new generation of superplasticizers containing some copolymer polycarboxylate makes it possible to significantly improve the fluidity of the recycled aggregates concrete in its fresh state. The aim of this research is to control rheologica] properties of fresh recycled aggregates concrete with fine and coarse recycled aggregates to limit the negative influence of aggregates on mechanical properties of concrete.

CTLD—J4000型能量鉴别式个人剂量计的剂量学实验研究

目的 了解能量鉴别式剂量计的剂量学性能。方法 选用个人剂量检测机构使用较多的一类能量鉴别式剂量计（CTLD-J4000型）进行一系列线性标准曲线、平均光子辐射能量和入射角的相对响应的研究分析其剂量学性能，并使用能量鉴别剂量计进行能量鉴别研究。结果 CTLD-J4000型能量鉴别剂量计线性相关性较好、平均光子辐射能量响应偏差±20％以内，入射角的相对响应偏差最大为10％，利用厂家给出的能量鉴别参考值在一定程度上可以实现能量鉴别的需求。结论 对于相同能量下照射不同剂量值和相同能量相同剂量照射不同角度的情况厂家给出的参考值与实际测量值存在一定的不一致的问题，尚需要通过进一步的实验找出不同剂量值和照射角度影响测量结果的规律。

Research trend of cascade heat pumps

Most commercial and industrial facilities require very low temperatures for refrigeration and high temperatures for space heating and hot water purposes. Single stage heat pumps have not been able to meet these temperature demands and have been characterized by low capacities and coefficient of performance(COP). Cascade heat pump has been developed to overcome the weaknesses of single stage heat pumps. This study reviews recent works done by researchers on cascade heat pumps for refrigeration, heating and hot water generation. Selection of suitable refrigerants to meet the pressure and temperature demands of each stage of the cascade heat pump has been discussed. Optimization of design parameters such as intermediate temperature(low stage condensing and high stage evaporating temperatures), and temperature difference in the cascade heat exchanger for optimum performance of the cascade heat pump has been reviewed. It was found that optimising each design parameter of the cascade heat pump is necessary for maximum system performance and this may improve the exergetic efficiency, especially of cascade refrigeration systems, by about 30.88%. Cascade heat pumps have wider range of application especially for artificial snow production, in the supermarkets,for natural gas liquefaction, in drying clothes and food and as heat recovery system. The performance of cascade heat pumps can be improved by 19% when coupled with other renewable energy sources for various real time applications. Also, there is the need for much research on refrigerant charge amount of cascade heat pumps, refrigerant-refrigerant heat exchangers to be used as cascade heat exchanger, cascade heat pumps for simultaneous cooling, heating and hot water generation and on the use of variable speed compressors and their control strategies in matching system capacity especially at part load conditions.

Black phosphorus quantum dot/g-C_3N_4 composites for enhanced CO_2 photoreduction to CO

The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, black phosphorus quantum dots（BPQDs） were successfully dispersed on a graphitic carbon nitride（g-C3N4） support via a simple electrostatic attraction approach, and the activities of BP@g-C3N4 composites were evaluated for photocatalytic CO2 reduction. The BP@g-C3N4 composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2 reduction to CO（6.54 μmol g^-1h^-1 at the optimum BPQDs loading of 1 wt%） compared with pure g-C3N4（2.65 μmol g^-1h^-1）. This work thus identifies a novel approach towards metal free photocatalysts for CO2 photoreduction.