一种染料的辐射脱色与辐射剂量分析

目的:观察在较小剂量γ射线作用导致的染料水溶液脱色与照射剂量的关系。方法:配制不同浓度的弱酸性艳红B染料水溶液,以γ线进行0 Gy~2000 Gy的梯度剂量照射,分别采集样品应用计算机色度分析技术测定记录其三基色色度值变化,进行数据处理,绘图分析,确定实验浓度,继续观察实验样品受温度和时间变化的影响。结果:随着试剂浓度及照射剂量的变化,三基色色度值出现了明显的相应规律性变化,其中红色和绿色色度值呈明确的此消彼长关系,蓝色色度变化不明显,室温环境存放四周时间的试验样本实验数据无明显差异。结论:结果说明0 Gy~2000 Gy的γ射线照射亦可导致与更大剂量致类似的辐射变色规律性变化。     

短葶飞蓬总黄酮含量变化研究

目的 研究短葶飞蓬总黄酮含量与生长发育和月份变化的关系，环境与遗传因素对总黄酮含量的决定作用。方法 测定同一月份不同生长发育期、同一生长发育期不同月份短葶飞蓬的总黄酮含量的器官分布，阳生和阴生生境下短葶飞蓬的总黄酮含量，不同花色短葶飞蓬的总黄酮含量。结果 短葶飞蓬的总黄酮主要分布于地上部分，而地上部分的总黄酮含量以盛花期员高，谢花期最低。4～6月盛花期短葶飞蓬各器官的总黄酮含量月份变化不显著。光照强度对短葶飞蓬总黄酮含量影响不大。短葶飞蓬的花色不能作为总黄酮含量的选择标记，遗传因素对个体间总黄酮含量差异起重要作用。结论 通过遗传育种提高短葶飞蓬总黄酮含量的前景是广阔的。     

Cell wall composition determines handedness reversal in helicoidal cellulose architectures of Pollia condensata fruits

Chiral asymmetry is important in a wide variety of disciplines and occurs across length scales. While several natural chiral biomolecules exist only with single handedness, they can produce complex hierarchical structures with opposite chiralities. Understanding how the handedness is transferred from molecular to the macroscopic scales is far from trivial. An intriguing example is the transfer of the handedness of helicoidal organizations of cellulose microfibrils in plant cell walls. These cellulose helicoids produce structural colors if their dimension is comparable to the wavelength of visible light. All previously reported examples of a helicoidal structure in plants are left-handed except, remarkably, in the Pollia condensata fruit; both left- and right-handed helicoidal cell walls are found in neighboring cells of the same tissue. By simultaneously studying optical and mechanical responses of cells with different handednesses, we propose that the chirality of helicoids results from differences in cell wall composition. In detail, here we showed statistical substantiation of three different observations: 1) light reflected from right-handed cells is red shifted compared to light reflected from left-handed cells, 2) right-handed cells occur more rarely than left-handed ones, and 3) right-handed cells are located mainly in regions corresponding to interlocular divisions. Finally, 4) right-handed cells have an average lower elastic modulus compared to left-handed cells of the same color. Our findings, combined with mechanical simulation, suggest that the different chiralities of helicoids in the cell wall may result from different chemical composition, which strengthens previous hypotheses that hemicellulose might mediate the rotations of cellulose microfibrils.

The brightest coloration in nature is produced by reflection from nanostructures on the length-scale of visible light wavelengths. A color-generating architecture that occurs repeatedly in nature is the organization of microfibrils into helicoids (1). Such structural color is produced by cellulose helicoids in plant tissues from ferns (2, 3) to monocots (4–6) and eudicots (7) and by chitinous helicoids in the exocuticle of insects (1, 8, 9).While the biological significance of this structural color is debated (1, 10, 11), the chirality of the helicoid has generally been considered a result of the intrinsic chirality of its constituent biomolecules. In all reports of helicoidal biomaterials, only left-handed chirality has been found, except in Pollia condensata (5), despite debate in wood helicoids (12). However, there is no indication of a mechanism by which left-handed structures could convey an evolutionary advantage in either mechanical or optical properties. First, under any nonrotational stress, there is no mechanical difference between structures of either handedness. Second, while structurally colored helicoids reflect circularly polarized light of the same chirality as their structure, there is very little evidence of terrestrial animal visual systems capable of detecting circularly polarized light and distinguishing the differences between reflectance of the two circular polarizations of light (13, 14). The only known exception to the left-handed chirality of reflective helicoidal architectures is reported in the epicarp of P. condensata fruits, in which cell walls composed of left- and right-handed helicoidal architectures are observed in different cells (5). The appearance of cell walls of opposite handednesses is surprising and begs the question why and how it should appear in this one species but not in other tissues.Several mechanisms have been proposed for forming the oriented microfibrils in helicoidal cell walls, via biological control (15, 16), physical forces (11, 17), and the use of hemicellulose to guide the cellulose orientation (18–21). Although constraints have been found in models of cell wall growth (6), the factors responsible for the control of handedness remain unknown. The chemical composition of the cell wall, and the interactions between cellulose and other polysaccharides within it, might play an important role in cell wall organization and chirality. Pioneering work by Reis et al. (22) has suggested the functional importance of hemicellulose in driving helicoidal architectures of cellulose in quince mucilage.Here, to investigate the structural origin of helicoidal chirality, we compared the optical and mechanical characteristics of helicoidal P. condensata cell walls with different handedness. We based our analysis on the observation that the polarization of the reflected light can be used to identify the chirality of each individual cell. We observed that left-handed and right-handed cells are not evenly distributed across the fruit surface: different areas in the epicarp are dominated by different chiralities. While most of the cells reflect light in the blue spectral region, we observed that right-handed helicoidal cells have a red-shifted reflection wavelength. By performing nanoindentation on cells with known handedness, we observed that left-handed helicoids on average have higher stiffness and hardness than right-handed ones. Furthermore, independently of handedness, we observed that helicoids reflecting the longest wavelengths have greater stiffness and hardness than cells reflecting shorter wavelengths.     

酸性湖蓝溶液的辐射剂量效应研究

目的 尝试利用三基色方法技术进行液体辐射化学剂量学研究。方法 配制不同浓度的酸性湖蓝A试剂水溶液,进行1.5~13.5 kGy不同剂量的γ射线照射,分别采集样品应用快速色度分析技术测定记录其三基色度值变化,进行数据处理,绘图分析。结果 显示随着试剂浓度及照射剂量的改变,三基色色度出现了明显的规律性变化,其中红色和蓝色色度值呈明显的此消彼长关系,绿色色度变化较小。结论 初步结果说明将电离辐射变色现象与计算机色度分析技术结合可开展新的辐射剂量学研究。     

硬胶囊中混合色素的HPLC测定

用甲醇－０．０２ｍｏｌ／Ｌ醋酸铵为流动相，以ＨＰＬＣ梯度法分离硬胶囊中的５种色素，以外标法定量。样品经赛璐玢膜透析处理，透析液直接进样。５种色素具有良好的线性行为，回收率在９５．５９％～１０１．７５％之间。日内差异＜２．８０％，日间差异＜３．２２％。     

Some observations on temporal coding of color vision: psychophysical results

Direction reversal of Benham's disk changes the observed colors, yet leaves constant the magnitude-frequency spectrum of the stimulus, changing only the phase relations between temporal frequencies. Hence, human color channels must be selectively responsive to stimulus temporal phase information.This question was further tested by applying to the eye electrical stimuli composed of sequences of frequency-modulated corneo-positive and negative pulses, which bypass at least some stages of the light-to-spike transfer function. Stimuli with a fast-slow corneonegative pulse frequency sequence elicited phosphenes in the range of yellow to green, for the four subjects tested. Stimuli with a slow-fast sequence elicited red-magenta, again for all four subjects.Convolution of previously derived Benham's disk-like signals for green-yellow and red-magenta with a published impulse function for the visual system resulted in output functions which were compatible with the frequency-time envelopes of the above electrical signals, providing independent support for the results.     

HPLC测定合成色素的干扰峰辨别研究

目的:建立HPLC测定合成色素的干扰峰辨别方法。方法:采用其最佳可见光区检测波长测定峰面积与254 nm波长下测定峰面积的比值来辨别干扰物质。结果:在实验条件下,波长选择紫外区选用国标法波长254 nm,可见区选用波长柠檬黄428 nm,日落黄484 nm,苋菜红、胭脂红525 nm。结论:方法应用于食品中色素干扰物的辨别,结果满意。     

SPE-HPLC测定小儿氨酚黄那敏颗粒中4种合成色素

目的 建立小儿氨酚黄那敏颗粒剂中合成色素的SPE-HPLC测定方法。方法 使用SPE固相萃取柱对合成着色剂进行净化、富集;采用高效液相色谱法测定含量,色谱柱为C₁₈柱(Inertsil ODS-3 C₁₈,4.6?250 mm,5 μm);以甲醇–0.02 mol. L_-1乙酸铵溶液为流动相,梯度洗脱;检测波长为各自的最大吸收波长(柠檬黄428 nm,日落黄521 nm,胭脂红509 nm,苋菜红483 nm);柱温30 ℃;进样量10 μL;流速1.0 mL.min_-1 。结果 柠檬黄、日落黄、苋菜红和胭脂红在0.05 μg.mL_-1～4 μg.mL_-1范围内呈良好线性关系(r≥0.9995),平均回收率分别为98.0%、97.9%、98.6%和99.3%,RSD＜0.9%。结论 该法操作简便、准确、重复性好,可用于同时测定小儿氨酚黄那敏颗粒中的4中合成色素。     

冠心病患者左心室功能的超声检测

目的探讨超声心动图对冠心病（CHD）患者左室功能的检测。方法收集因临床诊断为冠心病或疑诊冠心病而行冠状动脉造影（CAG）的170例患者，且均在同期内（间隔小于2周）行超声心动图检查，分为两组，其中冠心病患者89例，对照组81例，应用二维、M型及多普勒超声检测其左室容量变化及左室瓣口血流情况，据此判断左室的收缩舒张功能，并进行比较。结果冠心病患者的左室收缩和舒张功能指标较对照组有显著差异（P〈0.05，P〈0．01）。结论超声心动图心功能指标能较好地评估冠心病患者的心功能状态：     

数字舌图的色彩校正方法研究

在舌诊客观化的研究中,舌色的真实还原是一个关键的技术环节。本文运用ICC色彩特性文件对数字图像进行了色彩校正,实验结果表明,此方法能够有效的校正数字图像的色偏,是一种行之有效的色彩还原方法。