热处理对竹材性能及变色的影响

总结了竹材在热处理方面的应用以及热处理对其物理力学性能和颜色的影响,并对竹材热处理技术在国内外的研究作了展望.     

二甲酚橙褪色光度法测定水样中的镁

本文作者研究了利用褪色光度法测量水样中微量镁的方法。结果表明:在一定条件下,方法的摩尔吸光系数为1 68×105L·mol-1·cm-1,精密度(RSD)为1 6%,回收率为93%～101%。     

喷气燃料脱色精制中颗粒白土失活加快的原因分析(Ⅱ)--喷气燃料馏分中有色成分的剖析及不同性质馏分油对白土脱色的影响

先用硅胶对大连石化分公司3号喷气燃料馏分油中的有色组分进行吸附,然后分别用二氯甲烷和甲醇两种脱附剂对已吸附有色组分的硅胶进行脱附,得到两种含有色组分的两种溶液.应用红外光谱和色-质联用分析法对富集的有色组分进行了分析鉴定.分析了不同时期喷气燃料馏分油的性质及其对颗粒白土吸附脱色性能的影响.结果表明,大连石化分公司3号喷气燃料馏分油中的有色组分主要成分为C8～C14醇类、酮类、苯酚、甲酚和多烷基酚类及一些多聚体化合物.脱硫醇塔前进料馏分油的性质差异很小,而脱硫醇塔后馏分油的性质变化很大,颜色显著加深.脱硫醇塔操作末期温度高而引起喷气燃料馏分中不稳定组分的氧化转化导致颜色变深.颗粒白土脱色处理赛氏色值高的喷气燃料馏分油明显比处理赛氏色值低的喷气燃料馏分油的效果要好.脱硫醇塔操作不当造成油品恶化是导致颗粒白土吸附脱色失活很快的主要原因.控制脱硫醇塔乃至蒸馏系统操作条件(特别是温度),对延长颗粒白土的使用时间至关重要.     

水煮莲藕漂白护色工艺研究

针对水煮莲藕容易褐变的现象,进行了漂白和护色试验, 最后优选出了最适的漂白护包方案:用0.15％低亚硫酸钠 溶液,在40℃的环境下,漂白60min;用0.40％M试剂或 0.20％柠檬酸+0.10％V_C+0.30％六偏磷酸钠+0.20％明矾溶 液护色处理2～3h。      

Activation Mechanisms of Pro-Phenoloxidase on Melanosis Development in Florida Spiny Lobster (Panulirus argus) Cuticle

Phenoloxidase (PO), pro-PO [1] and pro-PO [2], isolated from cuticular extracts of early premolt spiny lobster, resolved into doublets of molecular weights 156, 151, and 96.0, 93 kD, respectively. Trypsin-activated forms of pro-PO [1] and pro-PO [2] were 123 and 83.6 kD, respectively. Apparently melanosis of shell and hyperdermal tissue in lobsters was related to stage of molt. The pro-PO forms were activated in vitro by extracts of molting fluid which is secreted into the cuticle just before molt, and the activated PO co-migrated in SDS-PAGE with the endogenously activated PO. The molting fluid was hypothesized to be the source of the natural activator(s) of pro-PO.     

Review on tropical root and tuber crops. II. Physiological disorders in freshly stored roots and tubers

Tropical root and tubers, including cassava, sweet potato, yams, and aroids, have been reported to show an increase in respiratory activity after harvest and injury and subsequent storage in association with their deterioration. This leads to loss of water and carbohydrate. Cassava roots often show discoloration of the tissue with development of pigments in the xylem vessels (vascular streaking or primary/physiological deterioration). This has been established to be enzymatic in nature. Pruning the cassava stem, leaving about a 20‐ to 30‐cm stub prior to harvest, could delay the onset of primary deterioration. Sweet potato roots and yam tubers show a peak respiratory activity immediately or 1 d after harvest. The respiratory rate, however, declines during the subsequent storage period. Yam tubers show a further increase in respiratory activity at the breakage of dormancy occurring at the time of sprouting. Dormancy in yam tubers has been studied in some detail. Different species of yams vary in their dormancy period, a major factor that accounts for the variation in their storage life. Little information is available on the dormancy of sweet potato and aroids. Tropical roots and tubers exhibit “chilling injury” when stored at temperatures below a critical level. The critical cold‐storage temperatures range between 10 and 15°C for different tropical root and tuber crops.     

基于电纺NiI2/TPU纳米纤维膜的湿敏变色传感器的制备及性能

以热塑性聚氨酯(TPU)母粒、碘化镍为原料,通过静电纺丝法制备了基于碘化镍/热塑性聚氨酯(NiI2/TPU)纳米纤维膜,将NiI2/TPU纳米纤维膜贴合在聚酰亚胺(PI)基叉指电极上制得湿度传感器.对纳米纤维膜的表面形貌及微观结构进行了表征分析,并研究了该传感器基于颜色变化和电阻电容响应的湿度敏感特性.结果表明,由于碘化镍的颜色变化特性,随相对湿度(RH)从0增加到97％,NiI2/TPU纳米纤维膜显示了从橘红色到黄绿色的颜色转变.此外,该湿度传感器表现出快速的响应/回复时间(0.9 s/9.9 s)、较宽的湿度监测区间(0～97％RH)、较小的洄滞度(0.4％RH)以及优异的稳定性能(>30 d).     

三角枫在干燥条件下的诱发变色过程

三角枫是一种易变色的木材，干燥过程中的变色不易预防；若能使三角枫干燥后得到更为理想的颜色，则可获得更为广泛的应用。通过对三角枫在不同干燥工艺条件下变色过程的研究以及红外光谱与扫描电镜分析，得出了三角枫干燥过程中的最佳诱发变色条件和诱发变色机理。研究结果表明，三角枫在干燥过程中的诱发变色是可行的。三角枫干燥过程的诱发变色机理为：①高温、高湿加速了三角枫中多元酚类物质以及无色花色素与单宁等的氧化反应，使三角枫发生红色变色；②三角枫经饱和蒸汽处理，羟基-OH经氧化转化为羰基-C=O、羧基-COOH、酯基和酮基等，使三角枫发生变色。     

Kinetic aspects of dye-transfer inhibition by catalytic oxidation

Dye-transfer inhibition (DTI) during laundering can be achieved by catalytic bleaching of the migrating dyes in the wash-liquor. The rate of the bleaching reaction should be significantly higher than the rate of dye adsorption onto the acceptor fabric. Further, the stability of the catalyst should be high enough in order to bleach dye which is slowly released from colored fabrics during the entire wash-cycle. The performance of three managnese-salen (Mn-salen) complexes as DTI catalysts is discussed in terms of their activity and their stability. It is shown that a very high activity is compatible with a high stability, leading to excellent DTI effects. For less stable catalysts, the performance can be markedly improved by optimizing the catalyst and peroxide concentrations or by formulation in a polymer matrix.     

偏光片变色机理浅析

研究了太阳照射后液晶显示器（LCD）偏光片的变色现象,采用智能型氙灯老化试验机、广角/小角X射线散射结构分析仪（WAXS）、X?射线能量色散谱仪（EDS）和分光光度计等对偏光片的光学性能、耐候性能及表面元素等进行了测试和表征,并探讨了其变色机理。结果表明,105 ℃×1 h的高温测试后,聚乙烯醇（PVA）膜素子中I₃^-紫外吸收峰强度增加1倍;120 ℃×120 h测试后,I₃^-紫外吸收峰强度增加2倍,PVA?I₅^-吸收峰强度减弱,PVA?I₃^-吸收峰强度增加;碘系偏光片变色机理为PVA?I₅^-向PVA?I₃^-转化,随着I₃^-含量增加偏光片颜色逐步变成棕色;变色的碘系偏光片在高温高湿处理后可以恢复到原来的颜色,PVA?I₅^-与PVA?I₃^-之间在偏光片中可以互相转换;偏光片受太阳辐射变色问题与偏光片抗紫外性能及耐高温性能有关;通过优化偏光片原料与制造工艺以提高其中紫外吸收剂含量可以提升其抗紫外性能;增加偏光片中PVA?I₅^-含量以提升其耐高温性能可以解决太阳照射下碘系偏光片变色问题。