New insights into brazilwood lake pigments manufacture through the use of historically accurate reconstructions

A multi-analytical approach for the study of brazilwood and its lake pigments was carried out based on historically accurate reconstructions. Recipes for brazilwood lakes from the fifteenth century technical text Livro de como se fazem as cores and the Winsor & Newton nineteenth century colourman's archive were reproduced and compared. Both primary sources allowed for the successful preparation of brazilwood lake pigments with colours that vary from light pink to dark red. The main steps and ingredients for the manufacture of these pigments were common in both sources, particularly the addition of Al³⁺ in the form of alum, and calcium carbonate (chalk). Reconstructions revealed that the latter acts as a pH buffer and filler, controlling the pH at which the lake pigment precipitates. The main difference between the two sources is that the nineteenth century recipes give the quantities for all ingredients, the precise temperatures and time, and achieved higher relative pigment yields (75% versus 45%). Full chemical characterisation of the reconstructions provided detailed information on the individual steps in the pigment manufacture and revealed that the presence of calcium sulphate dihydrate (gypsum) in the final pigment was a result of its formation in situ. Infrared, reflectance, and fluorescence spectroscopy proved to be essential and complementary techniques: while infrared was used to characterise additives and binders, reflectance and fluorescence data were fundamental for identifying the chromophore. The pigments and paints produced can now be used as standards for the identification and investigation of brazilwood lake pigments found in artworks.     

烟草感染赤星病后几种酶的动态及其作用

对11个烤烟品种接种赤星病病原菌后,定期测定叶片的过氧化物酶(POD)同工酶、多酚氧化酶(PPO)、硝酸还原酶(NR)和抗坏血酸氧化酶活性,观察其变化规律．结果表明,相对抗赤星病强的品种,PPO活性上升;POD同工酶活性变幅大而快,接种初期活性稍有下降,然后增强,其中以阴极端2,4同工酶带增加较快,180 h由弱酶带变为强带;NR活性变化不大;抗坏血酸氧化酶活性提高．相反,抗赤星病弱的品种,PPO活性下降;POD同工酶变化不大,呈下降趋势;NR活性变幅大;抗坏血酸氧化酶在接种初期活性下降,84 h后回升．通过对不同品种的烟株接种赤星病菌后几种酶活性的测定,探察到一些抗病机理,也为进一步寻找筛选抗烟草赤星病的生化指标提供了参考．     

颜填料对不饱和聚酯树脂及原子灰固化的影响

考察和比较了一系列的原子灰颜填料的作用和功能及对原子灰固化的影响，发现重晶石粉料对不饱和聚酯树腊及原子灰的固化有明显的影响。     

天然甘蓝食用色素化学稳定性研究

蔬菜花色素是天然食用色素中的一个主要类别,属水溶性色素.甘蓝色素是蔬菜花色素中新近开发的一种.本文测定了甘蓝色素吸收光谱和其在溶液中呈现红紫色的适宜酸度条件,观察了不同pH对该色素的影响和这些添加剂存在下它的光照稳定性.为甘蓝色素的开发应用提供了依据.     

《小伙子布朗》的分层解读

《小伙子布朗》是霍桑的一部短篇小说,作者通过对主人公布朗一次黑夜林中之旅的记叙,表达了对人性的思考。本文从主人公布朗、小说本身、作者霍桑三个层面对对人性的善恶界限进行解读。     

糖蜜酒精废液所含色素及其提取研究现状

糖蜜酒精废液是利用制糖副产物糖蜜制造酒精所产生的废液,是一个庞大的污染源,对其进行综合治理以保护水资源和生态环境意义重大,在治理的同时回收能源和其他有用的物质,创造经济效益,符合低碳经济的政策和趋势。阐述了糖蜜酒精废液的性质、危害及其处理的现状,介绍了糖蜜酒精废液中的色素组成,以及分离提取糖蜜酒精废液中色素的主要方法。     

合成食用色素的性质及分析方法

介绍了6种常用的食用色素的性质及分析方法．     

布朗情感因素理论在第二语言教学中的运用

自上世纪后半叶以来，西方语言学界和心理学界对第二语言教学相继开展了深入的研究。其代表人物布朗提出了许多有价值的观点。本文在简要分析讨论布朗的理论要点的基础上，结合当前我国第二语言教学的实际情况，提出在我国的第二语言教学语境中如何运用布朗的理论，以便进一步提高第二语言教学的质量。     

布朗运动的发现及其所蕴涵的科学本质探析

对于如何在科学教育过程中实现科学本质教育这一目标,研究者提出了多种模式和观点。其中,在科学课程与教学中融合科学史,即 HPS 教育模式受到人们的重视。布朗运动的发现过程蕴含了丰富的科学本质观教育内容。从布朗运动的发现过程可以看出,要成为在某一领域有重要贡献的科学家,需要奉献、时间以及被相应的科学共同体认可的特殊技术和理论能力;一个科学问题的提出和研究,会受到社会文化和技术水平的影响;科学的本质就是一种探究过程,这种探究过程主要包括观察和提出问题、形成假设、实验求证、得出和交流结论四大基本步骤;科学应当是民主的,这种民主的主要表现之一就是所有的知识主张应当被公平对待,无论这些知识主张的来源如何,即普遍性与公正性标准;科学是不断发展的,布朗运动的发现直至解释经历了布朗的实验观察、古伊的定性研究、爱因斯坦的定量理论模型、贝兰的实验验证等几个阶段。所以,科学具有一种动态的品质,它的一个永恒不变的性质就是变化,就科学的理论内容而言,科学“永远是临时的”。     

Red pigment production by Penicillium purpurogenum GH2 is influenced by pH and temperature

The combined effects of pH and temperature on red pigment production and fungal morphology were evaluated in a submerged culture of Penicillium purpurogenum GH2, using Czapek-Dox media with d-xylose as a carbon source. An experimental design with a factorial fix was used: three pH values (5, 7, and 9) and two temperature levels (24 and 34 °C) were evaluated. The highest production of red pigment (2.46 g/L) was reached with a pH value of 5 and a temperature of 24 °C. Biomass and red pigment production were not directly associated. This study demonstrates that P. purpurogenum GH2 produces a pigment of potential interest to the food industry. It also shows the feasibility of producing and obtaining natural water-soluble pigments for potential use in food industries. A strong combined effect (p<0.05) of pH and temperature was associated with maximal red pigment production (2.46 g/L).