Effects of droplet size on the oxidative stability of oil-in-water emulsions

The effects of droplet size and emulsifiers on oxidative stability of polyunsaturated TAG in oil-in-water (o/w) emulsions with droplet sizes of 0.806±0.0690, 3.28±0.0660, or 10.7±0.106 μm (mean ± SD) were investigated. Hydroperoxide contents in the emulsion with a mean droplet size of 0.831 μm were significantly lower than those in the emulsion with a mean droplet size of 12.8 μm for up to 120 h of oxidation time. Residual oxygen contents in the headspace air of the vials containing an o/w emulsion with a mean droplet size of 0.831 μm were lower compared with those of the emulsion with a mean droplet size of 12.8 μm. Hexanal developed from soybean oil TAG o/w emulsions with smaller droplet size showed significantly lower residual oxygen contents than those of the larger droplet size emulsions. Consequently, oxidative stability of TAG in o/w emulsions could be controlled by the size of oil droplet even though the origins of TAG were different. Spin-spin relaxation time of protons of acyl residues on TAG in o/w emulsions measured by ¹H NMR suggested that motional frequency of some acyl residues was shorter in o/w emulsions with a smaller droplet size. The effect of the wedge associated with hydrophobic acyl residues of emulsifiers was proposed as a possible mechanism to explain differences in oxidative stability between o/w emulsions with different droplet sizes.     

导电碳黑连接TiO2和染料分子提高染料敏化太阳能电池的光电性能

通常,染料敏化纳米太阳能电池(dye-sensitized solar cells,DSSCs)使用纳米金属氧化物来作为光阳极,如纳米TiO2,作为N型半导体通过连接染料来建立光阳极的。在光阳极中金属氧化物连接染料使DSSC的吸收光谱扩展到可见光谱区。文章研究在光阳极中添加导电碳黑使其成为纳米TiO2和染料之间的纽带。实验中使用粉末涂敷法在透光率约90%导电玻璃上涂覆纳米TiO2层在450℃烧结30 min,自然冷却然后再浸在染料和碳黑的混合物中敏化制得光阳极。添加的导电碳黑起到催化剂的作用,有助于染料电子的激发和纳米TiO2导带的增加并且减小了复合阻抗。结果表明,添加0.05 g导电碳黑的DSSCs光电性能最佳。开路电压增加了约33.9%,短路电流密度从4.385 mA/cm2增加到7.637mA/cm2。     

Study of space-charge characteristics in polyethylene for power cable insulation by laser-induced pressure-pulse technique

By utilizing the laser induced pressure-pulse (LIPP) technique, the behavior of space charge in low-density polyethylene (LDPE) and crosslinked polyethylene (XLPE) films in contact with metal or carbon-loaded semiconducting layers was studied quantitatively to clarify the space-charge characteristics in power cables. Negative heterospace charge near the anode and positive space charge in the bulk were observed in unoxidized LDPE under the fields above 120 kV/mm. The amount of negative space charge increased with applied field, while positive space charge in the bulk disappeared with increasing applied field. This indicates that electron injection and ionization are enhanced by applied field. Prominent negative homospace charge was formed near the cathode in oxidized LDPE, which indicates that oxidation enhanced electron injection. The depth of charge centroid from the cathode became larger with increasing temperature. This indicates that the effective electron mobility increases with temperature. Negative space charge also was formed in the bulk in XLPE films with metal electrodes, which indicates that crosslinking enhanced electron injection. XLPE films with a carbon-loaded semiconducting layer showed both negative and positive homospace charges near the semiconducting layers, which indicates that both electrons and holes were injected from the semiconducting layer.     

Attachment of poly[(ethoxyhexylsilylene)oligothienylene]s to inorganic oxide surface

Poly[(ethoxyhexylsilylene)quarter- and -quinquethienylene]s (EHSxT, x = 4 and 5) were prepared by Stille-coupling reactions of bis(bromothienyl)ethoxyhexylsilane and bis(tributylstannyl)bi- and -terthiophenes, respectively. Treatment of indium tin oxide (ITO) and TiO₂ electrodes with solutions of EHSxT in chloroform at 40 °C led to the formation of the polymer-attached electrodes. An application of the EHS5T-attached TiO₂ electrode to dye-sensitized solar cell was examined.     

Electrochromism of nickel oxide thin film with polymer gel electrolyte

Polymer gel electrolytes were investigated for an electrochromic device (ECD) using nickel oxide thin film. Poly(ethylene oxide) (PEO) derivatives were cross‐linked and swelled in KOH–aqueous solution giving a hydrogel electrolyte. The ECD containing the uniformly cross‐linked hydrogel showed good result in electrochromic switching performance. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1305–1308, 2002     

一种新的基于PDF文档结构的信息隐藏算法

通过分析格式化文件PDF(Portable Document Format)文档的数据结构,提出了一种新的基于PDF文档结构的大容量信息隐藏算法。将秘密信息预处理后伪装成合法PDF对象的形式,以文件流的操作方式嵌入到载体文件中,并满足嵌入的信息不影响文件在阅读器、编辑器与打印机中的输出。实验实现了线性化PDF文档的信息隐藏与检测。理论分析与实验结果均表明,该算法具有较大的信息隐藏容量、很快的隐藏与检测速度及依赖于加密算法和密钥的安全性。