平均强度法对双能量伽马射线灰分计读数的影响

双能量伽马射线灰分计采用平均强度法引入的误差由厚度及灰分变化2个因素引起。在特定的，简化的变化模式下对这些偏移作解析近似，进而对2个因素引起的误差作了比较。结果表明，厚度变化的影响是主要的。因而，根据计数率水平确定采样时间能大大减小此误差。蒙特－卡罗法模拟的结果证实了这一论断。     

Effect of ionizing radiation on antinutritional features of velvet bean seeds (Mucuna pruriens)

Impact of gamma irradiation on the antinutritional constituents of seeds of Mucuna pruriens was assessed on exposing to doses of 2.5, 5.0, 7.5, 10, 15 and 30 kGy. Except for 2.5 kGy, the rest showed significant dose-dependent increase in phenolics. Tannin concentration did not differ significantly up to 7.5 kGy, while it significantly increased at higher doses. Excluding 2.5 kGy, the rest of the treatments showed significant decreases in the phytic acid and complete degradation was attained at 15 and 30 kGy. The l-DOPA concentration showed a dose-dependent decline. A trace amount of hemagglutination activity was seen on human erythrocytes in raw seeds, which was completely absent on irradiation (>5 kGy). Concentration of Polonium-210, a natural radionuclide falls within the admissible limits for consumption. As Mucuna seeds serve as food, feed or as pharmaceuticals, it may be necessary to set the ionizing radiation to a specific dose to retain optimum levels or to eliminate phenolics, tannins, phytic acid and L-DOPA. As irradiation is a physical and cold process, it may be ideal and emerge as an important technique to improve the nutritional or pharmaceutical quality of Mucuna seeds and its products.     

辽宁省环境陆地γ辐射剂量水平调查

按辽宁省面积均匀布点1462个,测量了各点的原野、道路和建筑物内的天然γ辐射剂量率(不包括宇宙射线贡献)和天然贯穿辐射剂量率(包括宇宙射线贡献)。全省原野、道路和室内的天然γ辐射剂量率数据,都呈对数正态分布,按面积加权的算术均值(括号内为几何均值)分别为6.12(5.86)、5.86(5.40)和10.22(9.90)×10~(-8)Gy·h~(-1);变化范围分别为(1.98—17.83)、(1.28—18.53)和(4.84—25.38)×10~(-8)Gy·h~(-1)各点道路与原野和室内与原野的天然γ辐射剂量率比值之算术均值分别为0.96和1.75;变化范围分别为0.28—2.42和0.80—4.71。全省原野天然贯穿辐射剂量率数据,既不呈正态分布,又不呈对数正态分布,其算术均值为9.89×10~(-8)Gy·h~(-1),变化范围为(5.74—21.63)×10~(-8)Gy·h~(-1)。     

氚β射线和~(60)COγ射线诱发小鼠外周血淋巴细胞微核细胞率及相对生物效应的研究

本文报道了雄性小鼠连续接受氚水或~(60)Coγ射线照射10天后,外周血淋巴细胞微核细胞率与累积吸收剂量的关系。各实验小鼠接受氚β射线内照射的累积吸收剂量分别为5.6、9.9、15.3、45.8、68.1拉德,~(60)Coγ射线外照射的累积吸收剂量分别为43、54、106、150、204和258拉德。结果表明,无论氚β射线还是~(60)Coγ射线,诱发的淋巴细胞微核细胞率随剂量增大而增加,关系式中含二次项。当氚的剂量为50拉德时,氚的 RBE 值为4.8。     

Evaluation of gamma rays influence on some biochemical and microbiological aspects in black truffles

The effects of two gamma-ray doses (1.5 kGy and 2.0 kGy) on some biochemical aspects and on the microbiological profile of black truffles was monitored, immediately after treatment and after 30 days of storage at 4 °C. Electrophoretic and chromatographic analyses of proteins and peptides, just like monitoring of polyphenol content, peroxides formation and microbial profile, allowed for the first time a better understanding of the mechanisms responsible for biochemical alterations and bacterial pattern in black truffles during their storage. Treatment at 1.5 kGy appeared to better preserve the characteristics of the fresh product. In 2.0 kGy-samples, the protein profile was characterised by a 20 kDa-polypeptide, which could be considered as an useful marker of the irradiation treatment and of the storage time of the product. MALDI-TOF mass spectrometry analysis did not permit a correct identification from tryptic peptides in databases, although the nano-ES/MS/MS analyses performed on the 10 kDa tryptic digest peptides showed an amino acidic sequence entirely contained in a protein of filamentous fungus Neurospora crassa.     

On the influence of gamma prime upon machining of advanced nickel based superalloy

Whilst gamma prime (γ′) phase is the strengthening phase in Ni-based superalloys its influence on machining has been seldom investigated. This paper reports for the first time on the effect of γ′ upon machining of Ni-based superalloys when cutting with parameters yielding different cutting temperature intervals which lead to strengthening/softening effects on the workpiece (sub)surface. In-depth XRD, SEM/FIB, EBSD analysis and unique micro-pillar testing in the workpiece superficial layers indicated that with the increase of γ′ fraction the grain plastic deformation significantly decreased, while specific cutting energy can switch from low to high values influenced by the real cutting temperature.     

CIS片上系统中伽玛校正的低功耗设计

为了实现CMOS图像传感器(CIS)片上系统(SoC)中伽玛(γ)校正的低功耗设计,同时又保证校正的精度,提出一种查找表和直线拟合相结合的γ校正技术。算法对灰度值较低的像素使用直接查找表方法校正,对于γ曲线上升缓慢部分的像素采用分段直线拟合的方法。在直线分段时,使用外层分段与内层分段相结合的方法,达到了分段优化的目的。算法保证了图像校正精度,与使用完全查找表法相比,误差在0.5 pixel之内。基于该方法设计了一个8 bit输入/8 bit输出的VLSI模块,通过FPGA对模块进行了验证,模块占用723个LE和195个LC寄存器,比完全查找表法减少了硬件资源耗费,实现了低功耗设计。系统最大工作频率可达148 MHz,完全满足实时处理的需求。     

Effects of gamma irradiation on fourth-instar Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)

Effects of gamma irradiation on fourth-instar Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) larvae in infested dates (Boufeggous variety) were assessed. Larvae were exposed to different gamma irradiation doses ranging from 300 to 900 Gy. Feeding, pupation, adult emergence and survival were very sensitive to ionizing irradiation. When irradiated at a dose of 300 Gy and higher, food consumption and weight gain were significantly affected, in a dose-dependent manner. Twenty days after irradiation, the weight loss at doses of 300, 450 and 600 Gy was 42%, 47% and 49%, respectively. At doses of 750 and 900 Gy, the weight of larvae diminished by 51% and 54%, respectively. In contrast, the controls gained 20% in weight. Development of larvae to the pupal stage was not prevented completely but none of the pupae emerged as adults. At 300 Gy, 21% of larvae survived 44 d after irradiation and successfully pupated. An absorbed dose of 450, 600, 750 or 900 Gy applied to larvae caused 100% mortality by 44, 38, 38 and 22 d post-treatment, respectively. The minimum dose required to prevent damage from feeding and adult emergence was 300 Gy while doses required to cause death were ?450 Gy.     

Evaluation of e-beam, γ- and X-ray treatment on the chemistry and safety of polymers used with pre-packaged irradiated foods: a review

Polymers used to package food intended for irradiation must currently receive separate US FDA approvals for e-beam, gamma and X-radiation. The three forms of irradiation have virtually indistinguishable effects on polymers held in vacuum. However, in air, irradiation damage is favoured by slow dose rates, such as that characteristic of gamma irradiation. Irrespective of irradiation type, theory and existing polymer irradiation literature both suggest that radiolytic products in food contact polymers should not present a health hazard due to migration into the foods they contain. Equations are presented which calculate the FDA allowable content of radiolytic products to achieve 'threshold of regulation' clearance and conversion of radiolytic yield values (G-values) into ppb concentration in the treated polymer in conformance with FDA practice. An approach to quantifying the functional barrier of a polymer is discussed.     

Determination of AKR-2 leakage beam and verification at iron and water arrangements

In this paper computational procedures and the experimental determination of the AKR-2 (Technical University Dresden) beam parameters are described. The calculations were performed using the MCNPX code (Pelowitz, 2002) and the nuclear data libraries ENDF/B VI.2., ENDF/B VII.0., JEFF 3.1., JENDL 3.3 and BROND 3. The nuclear data were processed using the NJOY code (MacFarlane and Muir, 1994). The measurements were performed with a two-parameter stilbene spectrometer (Bures et al., 2002).