A sensitive EPR dosimetry system based on sulfamic acid

There is a need for a sensitive dosimeter using electron paramagnetic resonance spectroscopy (EPR) for use in medical applications, since with this method non-destructive read-out and dose archival could be achieved. Sulfamic acid as a possible detector substance was investigated before and after irradiation, its EPR spectra were recorded and analyzed, some dosimetric characteristics were studied: microwave power saturation behavior, the effect of modulation amplitude on peak-to-peak signal intensity and the line width. Energy-dependence parameters were compared to soft tissue and alanine, and the response to ionizing radiation was studied, also the decay behavior along 133 days after irradiation is presented. It is found that sulfamic acid possesses high-sensitivity and reasonable signal stability which may make it useful as a sensitive dosimeter for medical applications.     

A beam optics study of the biomedical beam line at a proton therapy facility

A biomedical beam line has been designed for the experimental area of a proton therapy facility to deliver mm to sub-mm size beams in the energy range of 20-50 MeV using the TRANSPORT/TURTLE beam optics codes and a newly-written program. The proton therapy facility is equipped with a 230 MeV fixed-energy cyclotron and an energy selection system based on a degrader and slits, so that beam currents available for therapy decrease at lower energies in the therapeutic beam energy range of 70-230 MeV. The new beam line system is composed of an energy-degrader, two slits, and three quadrupole magnets. The minimum beam sizes achievable at the focal point are estimated for the two energies of 50 and 20 MeV. The focused FWHM beam size is approximately 0.3 mm with an expected beam current of 20 pA when the beam energy is reduced to 50 MeV from 100 MeV, and roughly 0.8 mm with a current of 10 pA for a 20 MeV beam.     

Optical and electrical characterization of r.f. sputtered ITO films developed as art protection coatings

Transparent and conductive tin-doped indium oxide (ITO) films have been prepared by r.f. plasma sputtering technique in Ar and Ar + O₂ gas mixture. The influence of the deposition conditions, film thickness, and substrate heating, as well as the post-annealing treatment on the optical and electrical properties of the ITO films has been investigated.The present study has extended the optical behaviour characterization of the ITO films in a wide UV-VIS-IR spectral region in addition to the comprehensive optical studies of this material at shorter wavelengths.The optical constants: refractive index (n), extinction (k) and absorption (α) coefficient, and the optical band gap (E_go) have been calculated for the ITO films in the spectral range between 350 and 2500 nm. A combination of several well-known theoretical models has been applied to describe precisely the complex optical behaviour of ITO films in separate spectral parts. In this approach, a good overlapping between the experimental and the simulated spectra in the whole investigated spectral region has been achieved.The deposition conditions and the optical and electrical properties of the ITO films have been optimized with respect to the requirements for their applications in art protection coatings.     

清苑县南水北调配套工程运行风险评价

南水北调配套工程运行风险评估体系属于复杂的系统问题,其模糊性在评估中应予以考虑。基于模糊识别理论,采用非线性模型对清苑县南水北调配套工程运行风险进行评价。结果表明,清苑县南水北调配套工程运行风险等级介于2级与3级之间,略偏于2级,属于低风险等级。评价过程与评价结果不仅可为清苑县南水北调配套工程的安全管理提供参考意义,而且表明非线性模型在南水北调配套工程运行风险评价中具有良好的适用性。     

河南省水资源承载力评价

选择10项指标,采用主成份分析法对河南省水资源承载能力进行了定量评价,结果表明,河南省水资源承载力的主要影响因素是人口与经济、城市发展和水资源开发利用,特别是国内生产总值、固定资产值和总人口对水资源承载力的影响最大;对比不同城市,济源市、三门峡市、鹤壁市、驻马店市和漯河市等具有较强的水资源承载能力,而郑州市、洛阳市、新乡市和许昌市等则承受着较大的水资源压力。     

土壤环境中阴极保护电位对涂层的影响

通过电化学测试手段,研究了土壤中涂覆有涂层的钢样在不同阴极电位下的阴极极化行为,并探讨析氢阴极还原反应对涂层的影响,从而为阴极保护限制电位的确定提供依据。     

农产品、食品安全检测方法与仪器

农产品和食品安全问题已是世人十分关注的大问题,本文论叙了食品安全监测体系的技术支撑,即检测方法和仪器中的四个问题:1)在基质复杂的样品中检测组分很多、含量很低的有毒、有害残留物的复杂性;2)当今对检测方法和仪器的要求;3)检测方法和仪器的现状,包括国际上得到确认的检测方法;4)对检测方法和仪器发展趋势的预测.     

回转式电火花展成加工及其成形运动分析

本文介绍了回转式电火花展成加工的原理及特点，并对该加工方法的成形运动分析进行了较深入地探讨，给出了计算机仿真的结果。     

氮化ZnO/Ga2O3薄膜合成GaN纳米管

利用射频磁控溅射法在Si(111)衬底上先溅射ZnO中间层,接着溅射Ga2O3 薄膜,然后ZnO/Ga2O3薄膜在管式炉中常压下通氨气进行氮化,高温下ZnO层在氨气的气氛中挥发,而Ga2O3薄膜和氨气反应合成出GaN纳米管.X射线衍射(XRD)测量结果表明利用该方法制备的GaN具有沿c轴方向择优生长的六角纤锌矿结构.利用傅里叶红外光谱(FTIR)研究了所制备样品的光学性质.利用透射电子显微镜(TEM)和选区电子衍射(SAED)观测了样品的形貌和晶格结构.