Natural and anthropogenic radioactivity levels and the associated radiation hazard in the soil of Oodalia Tea Estate in the hilly region of Fatickchari in Chittagong,Bangladesh

Radioactivity in the soil of a tea garden in the Fatickchari area in Chittagong, Bangladesh, was measured using a high-resolution HPGe detector. The soil samples were collected from depths of up to 20 cm beneath the soil surface. The activity concentrations of naturally occurring ²³⁸U and ²³²Th were observed to be in the range of 27 ± 7 to 53 ± 8 Bq kg⁻¹ and 36 ± 11 to 72 ± 11 Bq kg⁻¹, respectively. The activity concentration of ⁴⁰K ranged from 201 ± 78 to 672 ± 81 Bq kg⁻¹, and the highest activity of fallout ¹³⁷Cs observed was 10 ± 1 Bq kg⁻¹. The average activity concentration observed for ²³⁸U was 39 ± 8 Bq kg⁻¹, for ²³²Th was 57 ± 11 Bq kg⁻¹, for ⁴⁰K was 384 ± 79 Bq kg⁻¹ and for ¹³⁷Cs was 5 ± 0.5 Bq kg⁻¹. The radiological hazard parameters (representative level index, radium equivalent activity, outdoor and indoor dose rates, outdoor and indoor annual effective dose equivalents, and radiation hazard index) were calculated from the radioactivity in the soil.     

高纯度茄尼醇的精制工艺研究

目的:提供一种高纯度茄尼醇的精制工艺.方法:利用各种柱层析方法,通过HPLC对含量进行监测来实现工艺的优化.结果:发现HPD600型树脂结合氧化铝柱层析有很好的纯化效果,配合乙腈重结晶可使含量达到97%以上.同时,运用保温夹套柱,减少了样品粘连造成的影响.结论:本研究对工业化生产有重要的参考价值.     

高纯镁在体内定量载荷下的降解行为

目的定量研究力学载荷对高纯镁在体内降解的影响。方法将直径2 mm、长14 mm的圆柱状高纯镁(99. 99 wt.%)试件装配到聚醚醚酮(PEEK)制成的圆环上。PEEK环可使镁试件分别处于3种应力状态:无应力、压应力[(6. 2±0. 6) MPa]和拉应力[(4. 6±0. 1) MPa]。将不同应力状态的试件植入SD大鼠背部皮下4周后取出。通过试件失重、剩余体积、表面形貌和周围软组织染色分析高纯镁的降解行为。结果植入大鼠皮下的高纯镁试件均出现降解,并且被胶原纤维囊包裹。受到压、拉应力的试件与无应力试件在失重和剩余体积上无显著差别。在各应力状态下的试件都趋于均匀腐蚀。结论在体内皮下环境中,PEEK环对高纯镁施加4～6 MPa压、拉应力对高纯镁降解行为无明显影响。研究结果为镁基可降解植入物的设计与临床应用提供理论依据。     

Grain Growth Mechanism of Lamellar-Structure High-Purity Nickel via Cold Rolling and Cryorolling during Annealing

High-purity (99.999%) nickel with lamellar-structure grains (LG) was obtained by room-temperature rolling and cryorolling in this research, and then annealed at different temperatures (75 °C, 160 °C, and 245 °C). The microstructure was characterized by transmission electron microscopy. The grain growth mechanism during annealing of the LG materials obtained via different processes was studied. Results showed that the LG high-purity nickel obtained by room-temperature rolling had a static discontinuous recrystallization during annealing, whereas that obtained by cryorolling underwent static and continuous recrystallization during annealing, which was caused by the seriously inhibited dislocation recovery in the rolling process under cryogenic conditions, leading to more accumulated deformation energy storage in sheets.     

Bonding efficacy and side effects of the high purity glyceryl mono-methacrylate

The purpose of this study was to examine the efficacy of experimentally developed high purity glyceryl mono-methacrylate (GM) as a dentine primer and to evaluate the possibility of allergic reaction. The efficacy of experimental dentine primers was evaluated by measuring the polymerization contraction gap width and the tensile bond strength. Allergic reaction was evaluated by the guinea-pig maximization test. The skin reaction was evaluated according to the criteria of the International Contact Dermatitis Research Group. Contraction gap formation was completely prevented and the tensile bond strength was not significantly affected by priming with GM on high-purity GM. The allergic response decreased when high-purity GM was employed as the challenger. It was concluded that the clinical use of the high-purity GM is beneficial as the delayed allergic reaction could be avoided with no detrimental effect on the dentine bonding.     

Formation Mechanism of High-Purity Ti2AlN Powders under Microwave Sintering

In the present study, high-purity ternary-phase nitride (Ti₂AlN) powders were synthesized through microwave sintering using TiH₂, Al, and TiN powders as raw materials. X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were adopted to characterize the as-prepared powders. It was found that the Ti₂AlN powder prepared by the microwave sintering of the 1TiH₂/1.15Al/1TiN mixture at 1250 °C for 30 min manifested great purity (96.68%) with uniform grain size distribution. The formation mechanism of Ti₂AlN occurred in four stages. The solid-phase reaction of Ti/Al and Ti/TiN took place below the melting point of aluminum and formed Ti₂Al and TiN_0.5 phases, which were the main intermediates in Ti₂AlN formation. Therefore, the present work puts forward a favorable method for the preparation of high-purity Ti₂AlN powders.     

来曲唑联合高纯度尿促性素对多囊卵巢综合征患者助孕以及生殖激素变化的影响

目的探讨来曲唑联合高纯度尿促性素对多囊卵巢综合征(PCOS)患者助孕以及生殖激素变化的影响。方法选取PCOS不孕患者152例,按随机数字表法分组,对照组76例予以氯米芬联合高纯度尿促性素治疗,研究组76例予以来曲唑联合高纯度尿促性素治疗,比较2组排卵周期相关指标、卵泡发育及子宫内膜情况、血清生殖激素水平以及妊娠结局。结果研究组排卵率、单卵泡排卵率均显著高于对照组(P0.05)。与对照组比较,研究组平均治疗周期较低,注射人绒毛膜促性腺激素(h CG)日成熟卵泡数、子宫内膜厚度较高,治疗后血清LH、FSH、E2水平显著较高,血清T水平显著较低(P0.05)。研究组临床妊娠率显著高于对照组,自然流产率及多胎妊娠率显著低于对照组(P0.05)。结论来曲唑联合高纯度尿促性素对PCOS患者的助孕效果较好,能够调节相关生殖激素分泌,促进卵泡发育、排出及子宫内膜生长,提高临床妊娠率,改善妊娠结局。     

FACSAria流式细胞仪无菌操作分选高纯度细胞亚群

BGC823细胞瞬时转染绿色荧光蛋白(GFP)质粒2d后,用FACSAria流式细胞仪分选GFP阳性和阴性BGC823细胞亚群,检测其分选纯度并培养分选后细胞,观察其无菌生长状态;商品化FITC直标抗体孵育SMMC7721细胞后,FACSAria流式细胞仪分选FITC阳性和阴性细胞亚群.将所有分选的细胞进行培养检测无菌状态,并观察细胞生长情况.FACSAria流式细胞仪分选得到的GFP阳性细胞群的分选纯度达99.6％,GFP阴性细胞群的分选纯度达98.8％,同时激光共聚焦荧光显微镜显示分选后的GFP阳性细胞明显富集;分选后的BGC823细胞和SMMC7721细胞常规培养,细胞均无污染且生长状态良好.     

Research Status of High-Purity Metals Prepared by Zone Refining

The zone refining method is a physical method for effectively purifying metals. Increasing yield and reducing impurity content have always been the focus of its research. This article systematically summarizes the relevant research on the production of high-purity metals by zone refining, including mechanisms, parameter optimization, zone refining types, analysis methods, limitations, and future development directions, and it provides relevant theoretical foundations for the production of high-purity metals as well.     

固相法制备高纯超细氢氧化镁的工艺

以自制的六氨氯化镁为原料,采用常温固相法制备了高纯超细氢氧化镁。对固相法制备高纯超细氢氧化镁的工艺条件进行了研究,得到优化的制备工艺条件为:M gC l2.6NH3和M gC l2.6H2O摩尔比1∶1,球磨速度350 r/m in,球磨时间15 m in,球料比5∶1、充填率52%,磨介1份10 mm大球和2份6 mm小球。对制得的超细氢氧化镁进行化学组成分析,结果表明:氢氧化镁含量在99.7%左右,杂质含量低于0.3%。粒度分析表明产品平均粒径为158 nm,变异系数(CV)为0.194。