棉纤维细胞壁的微纤丝螺旋角及其与花后生长天数的关系

应用X射线衍射分峰法测量了棉纤维细胞壁的平均微纤丝螺旋角,该方法基于(002)衍射强度-方位角扫描曲线由两个相同的高斯曲线叠加而成的假定。测量结果表明:在花后5～50天内,细胞壁S_2,层的平均微纤丝螺旋角随花后生长天数的增加而逐渐变小。     

毛竹材微纤丝角变异规律研究

利用了X射线衍射技术对不同高度、不同竹龄、在垂周方向不同位置的毛竹材微纤丝角变化规律进行了研究。结果表明,在竹壁径向上,由外而内,微纤丝角大致呈先增大后减小的变化趋势,至靠近竹黄处微纤丝呈现最小值,且最大值与最小值间差异为4.17°。从基部往上,微纤丝角有略微增大,最大差异只有0.15°。毛竹材的微纤丝角从0.5年至6年呈先增大后减小的变化趋势,5个竹龄的毛竹材微纤丝角之间的差异最大值仅0.52°。最后通过方差分析表明,高度、竹龄以及垂周方向上的位置对毛竹材微纤丝角的影响显著。     

速生意大利杨木防腐与强化复合改性

采用氨溶烷基铜铵(ACQ)防腐剂与脲醛树脂(UF)调制成的相溶复合改性剂,对速生意大利杨木进行一次性真空浸渍处理,使处理材力学性能提高并达到强防腐等级.优化工艺参数为:浸渍压力0.6 MPa、加压2 h、ACQ与UF的体积比为4∶1.处理后主要力学性能指标均提高22.46%以上.对浸渍材进行表面密实化优化工艺处理(压缩率为20%),各项力学性能指标均比素材提高52%以上.对浸渍材与ACQ处理材抗水、酸、碱抽提的抗流失性进行对比试验,前者比后者固着率提高0.84%以上.应用X射-线荧光光谱仪的Cu2+跟踪法,定量分析了浸渍材复合改性剂的含量分布和改性效果.     

Cone beam computed tomography and intraoral radiography for diagnosis of dental abnormalities in dogs and cats

The development of veterinary dentistry has substantially improved the ability to diagnose canine and feline dental abnormalities. Consequently, examinations previously performed only on humans are now available for small animals, thus improving the diagnostic quality. This has increased the need for technical qualification of veterinary professionals and increased technological investments. This study evaluated the use of cone beam computed tomography and intraoral radiography as complementary exams for diagnosing dental abnormalities in dogs and cats. Cone beam computed tomography was provided faster image acquisition with high image quality, was associated with low ionizing radiation levels, enabled image editing, and reduced the exam duration. Our results showed that radiography was an effective method for dental radiographic examination with low cost and fast execution times, and can be performed during surgical procedures.     

Sulphur speciation and turnover in soils: evidence from sulphur K-edge XANES spectroscopy and isotope dilution studies

Sulphur K-edge X-ray absorption near edge structure (XANES) spectroscopy was used to quantify S species in humic substance extracts from ten soils from the UK, China and New Zealand, which differ in land use and agricultural management. XANES spectroscopy showed the presence of most reduced (sulphides, disulphides, thiols and thiophenes), intermediate (sulphoxides and sulphonates) and highly oxidised S (ester sulphates) forms, with the three groups representing 14-32%, 33-50% and 22-53% of the organic S in the humic substance extracts, respectively. Land use had a profound influence on the relative proportions of S species. Well-drained arable soils generally had a higher proportion of organic S present in the most oxidised form than the grassland soils collected nearby, whereas paddy soils showed a more reduced profile due to episodic flooding. In the Broadbalk Classical Experiment at Rothamsted, reversion of an arable system to grassland or woodland in the 1880s resulted in an increase of the most reduced and intermediate S species at the expense of the most oxidised S species. Long-term applications of farmyard manure to an arable plot also shifted S species from the most oxidised to the intermediate and the most reduced species. Sulphur immobilisation and gross mineralisation were determined in seven soils using the ³⁵S isotope dilution method. Gross mineralisation during a 53-day incubation correlated more closely with the amounts of the most reduced and intermediate S species than with the most oxidised S species, suggesting that the former (C-bonded S) were the main source of organic S for mineralisation in the short-term.     

pH对针铁矿表面磷酸盐吸附的化学形态的影响

Chemical forms of the phosphate adsorbed on goethite surfaces and characteristics of the coordinate groups which exchange with P on goethite surfaces in solutions with different pll values were investigated.Results showed that the chemical forms of P on goethite surfaces changed from the dominance of monodentate corrdination to that of bidentate one with increasing pH of the solution.By influencing types of phosphate ions in solutions,pH affected the chemical forms of P on goethite surfaces,The amount of OH^- displaced by phosphae on goethite surfaces was the most at pH 7.0,the second at pH 9.0,and the least at pH 4.5.     

X射线强度直接计数法无损检测木材生长轮密度

文中初步探讨了X射线强度直接计数法无损连续检测木材生长轮密度的理论。作者主要根据X射线服从指数衰减规律,采用按一定步长移动的扫描方式,并结合应用D/max-3B型X射线衍射仪(日本)提出了试样制作要求和试验方法。通过实验对兴安落叶松、杉木等进行了测试,其结果与称重法比较基本一致。这一研究表明,应用X射线强度直接计数法,优于X射线照像法和γ射线强度直接计数法,它简化了测试过程,提高了检测速度,是一种检测木材密度的有效手段,可用于木材科学研究和生产实践。     

STUDY OF DETERMINING THE DEGREE OF GRAPHITIZING OF COKE WITH X-RAY DIFFRACTION METHOD

In the paper, the process of determining the degree of graphiti-zing of metallurgy coke with X-ray diffraction method was discussed. The extrapolation was used in order to obtain the interplanar distance. of (002) crystaloface of metallurgy coke. The finding showed that the dmax. wasn''t 3.44A, butO4.31A. A rational formula which could be used to characterize the degree of gra-phitizing of metallurgy coke was found.     

软X射线检验杉木等种子发芽率的研究

用HY—35型软X射线仪对杉木、马尾松、柳杉种子进行摄影,确定各树种种子X光片的判读等级,对照各树种等级标准,判读出各级的粒数百分率,从而估算出杉木、马尾松和柳杉等种子发芽率。     

超声联合钼靶X线检查在乳腺良恶性肿瘤鉴别诊断中的应用

目的评价超声联合钼靶X线检查在乳腺良恶性肿瘤鉴别诊断中的应用价值。方法经病理证实的168个乳腺肿瘤术前均行超声及钼靶X线检查,评估两种诊断方法及联合应用的灵敏度、特异度、阳性预测值、阴性预测值及诊断符合率。结果 168个乳腺肿瘤中,良性113个,恶性55个。除钼靶对恶性肿瘤钙化的显示率高于超声之外（P〈0.01）,两者在其余指标的检测差异均无统计学意义（P〉0.05）。二者联合诊断乳腺良恶性肿瘤的特异度、阳性预测值及符合率均优于单用超声、钼靶,差异均有统计学意义（P〈0.01或0.05）。结论超声和钼靶X线联合应用可显著提高乳腺肿瘤的诊断符合率。