A Note on the Effect of Microwave Heating on Iodine-Catalyzed Acetylation of Wood

The effect of microwave heating on the iodine-catalyzed acetylation of rubberwood with acetic anhydride has been investigated. Microwave radiation was used as the heating source for modifying specimens saturated with acetic anhydride in bulk solution (excess of reagent) and impregnated specimens (limited supply of anhydride). Extent of modification of wood was expressed in terms of weight percent gain (WPG) and modification was characterized using FTIR spectroscopy. In bulk solution, microwave radiations were primarily absorbed by anhydride solutions for heating purposes and a moderate WPG was obtained. However, when microwave heating was used to modify impregnated wood specimens under no excess of anhydride, a significant enhancement in degree of modification was achieved within a few minutes. The modified wood exhibited good anti-swelling efficiency.     

The inkjet printing process for Lyocell and cotton fibres. Part 1: The significance of pre-treatment chemicals and their relationship with colour strength, absorbed dye fixation and ink penetration

A statistical study of the outcome of inkjet printing, using a reactive dye based ink, on three cellulosic fabrics, namley Lyocell (standard Tencel and Tencel A100) and cotton, pre-treated with urea, migration inhibitor, penetration agent and alkali is reported. Colour strength (as Integ value), absorbed dye fixation and ink penetration were analysed as main responses. A full factorial design method was applied to study the effect of the level of each ingredient in the pre-treatment formulation on the responses, together with the steaming time used for dye fixation. The interactions between variables were also evaluated. The statistically significant variables were determined for each response and contour plots constructed for the most significant interactions to assess where the optimum responses might be achieved.     

微波辐射处理对玉米淀粉颗粒非晶化的影响

采用微波辐射的手.段处理原玉米淀粉,考察了分散剂种类,淀粉与分散剂的质量比及微波处理的温度对淀粉非晶化的影响。用偏光显微镜观测处理后淀粉的颗粒结构,结合X射线衍射曲线验证淀粉颗粒结构的变化,利用扫描电镜观測颗粒保持的状态。结果表明:当分散剂为水,淀粉与水分的质量比为3:4时,原玉米淀粉可以均匀的转变为非晶颗粒态淀粉。     

微波消解-电感耦合等离子体质谱法测定花椒中稀土元素

目的 建立电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry, ICP-MS)测定花椒中Sc、Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu 16种稀土元素含量。方法 采用微波消解技术结合硝酸-过氧化氢体系进行样品预处理,通过在线加入Rh、Re内标元素进行基体干扰的校正,通过ICP-MS的动能歧视效应(kinetic energy discrimination, KED)消除可能存在的多原子离子干扰,以国家标准物质绿茶(GBW 10052)进行方法准确度验证。结果 16种稀土元素在0.05-10 μg/L的范围内具有良好的线性关系,线性相关系数R²≥0.999,各元素的检出限在0.045-1.282 μg/kg之间,平均回收率为89.7%-107.5%,相对标准偏差(relative standard deviations, RSD)为0.2%-4.7%。实际样品分析结果表明,花椒中16种稀土元素均有检出,含量范围为0.178-2058 μg/kg。结论 方法分析速度快,准确度高,灵敏度好,可应用于花椒中稀土元素的测定。     

微波功率GaAs MESFET本征元件与偏置关系分析

提出了一种分析和了解微波功率 Ga As MESFET非线性效应的方法。主要是采用解析优化方法 ,提取 MESFET器件在不同偏置点下的本征元件 ,并结合器件的应用类型 ,对本征元件与偏置的关系进行了系统化的分析。分析的结论有助于提高微波功率 Ga As MESFET器件设计和应用的准确性     

微波消解-丁二酮肟沉淀分离-EDTA返滴定法测定含镍生铁中镍

含镍生铁是不锈钢冶炼重要原材料,准确快速检测含镍生铁中镍含量对不锈钢冶炼质量控制及成本控制至关重要,而使用丁二酮肟重量法测定含镍生铁中镍需使用大量酸溶解样品,有时还需要对不溶性残渣进行熔融处理,过程繁琐。实验利用微波消解法处理含镍生铁样品,并通过丁二酮肟沉淀分离法使含镍生铁中镍与钴、铜有效分离,再使用EDTA返滴定法测定镍,最终建立了含镍生铁中镍含量的测定方法。使用5个含镍生铁标准样品进行验证,当镍质量分数为5%～20% 时,测定结果的相对标准偏差(RSD,n=7)为0.14%～0.33%;通过t检验法进行显著性检验,测定结果与标准值之间无显著性差异。分别按照实验方法和国标方法GB/T 31924—2015《含镍生铁 镍含量的测定 丁二酮肟重量法》对同一个含镍生铁样品进行检验,使用t检验对两种方法得到的结果进行统计分析,结果表明两种方法检验结果无显著性差异。     

番茄红素提取效果的进一步研究

研究在不同提取温度、时间、料液比、pH值等因素下从番茄中提取番茄红素的提取效果．用正交表设计实验，优化最佳提取条件．实验中确定的最佳工艺条件是：温度为50℃，pH值为6，料液比为1：6，时间为2h，若使用微波辐射法，在微波功率为200W、萃取时间为80s、料液比为1：3的条件下，能得到最好效果．最佳工艺条件的确定为进一步开发这种功能性天然色素奠定了基础．     

低温法制备TiO_2薄膜及其光催化处理皮革废水的研究

采用微波辅助低温法在玻璃表面制备锐钛矿结构的二氧化钛薄膜,并与传统溶胶凝胶法制备的薄膜进行了对比。通过X射线衍射(XRD)和扫描电子显微镜(SEM)分析技术,对其物相及显微结构进行了表征;在波长为254nm的紫外灯照射下,对TiO2薄膜光催化降解皮革废水前后COD值变化作了研究,探讨了不同光催化条件、皮革废水初始COD浓度及pH值对COD去除率的影响。结果表明:与传统溶胶凝胶法制备的薄膜相比,微波辅助低温制备的薄膜光催化效果更好。当废水初始COD值在750～1500mg/L之间、pH值为4.0、在25℃紫外灯照射10.0h时,光催化效果最佳,COD去除率高达80.1%。     

微波辐射下纳米银粒子的制备及表征

以硝酸银为银源,六亚甲基四胺为还原剂,聚乙烯吡咯烷酮为表面活性剂和稳定剂,在微波辐射下制备出平均粒径约30nm的纳米银颗粒。利用X射线衍射仪、透射电子显微镜对样品的晶体结构和形貌进行表征;用红外吸收光谱对样品结构组成进行定性分析;用紫外-可见分光光度法研究样品的光学性能。结果表明:该法简单、快捷,所制备的纳米银粒子为纯立方晶型的多晶,其粒径小,分布窄,分散性好。     

Effects of Different Drying Methods on the Quality of Squid Cubes

The effects of three different drying methods (e.g., intermediate infrared-assisted convection drying, low-frequency (915 MHz) microwave drying, and hot-air drying) on the quality of squid cubes were investigated. The quality parameters used to evaluate the drying efficiency were color, shrinkage, rehydration ratio, and hardness of the final dried products. The results showed that intermediate infrared-assisted convection drying and low-frequency microwave drying have the advantages over hot-air drying in terms of drying rate, shrinkage percentage, and rehydration ratio. Low-frequency microwave-dried samples displayed a puffed structure and their hardness was the highest. The intermediate-wave infrared-assisted convection drying, at 60°C, was identified as the best method for squid-cube drying in this study.