油酸/PSt/TiO_2复合纳米微球的制备

纳米复合材料是近年来化学、物理及材料科学研究最活跃的领域之一 .有机 -无机复合纳米微球的制备和性能研究是这一研究领域的一个重要分支 .有机 -无机复合纳米微球兼有有机材料、无机材料和纳米材料的特性 ,特别是“球形”结构使其具有微观的“滚动”特性而倍受摩擦学工作者的青睐 .目前聚合物纳米微球的摩擦学性能研究已取得了重要进展 [1～ 4 ] .段标等 [3,5]认为聚合物微球的润滑机理是在摩擦过程中 ,微球进入摩擦表面 ,因其弹性和球形 ,而起到一定的滚动作用 ;高载荷下 ,微球变形并在摩擦表面形成聚合物润滑膜 .然而有关聚合物 /无机…     

消除挤压机误动作的差错控制编码

运用数据传输的差错控制原理,以TON－92铝材挤压机单片机控制系统为研究对象,具体介绍了串行数据传输的误码纠正方法,给出了能检测每帧中2位以上误码且能纠正1位误码的Hamming码与奇偶校验码混合的编码与解码的工作程序。     

Preparative and scaled‐up separation of high‐purity α‐linolenic acid from perilla seed oil by conventional and pH‐zone refining counter current chromatography

α‐Linolenic acid is an essential omega‐3 fatty acid needed for human health. However, the isolation of high‐purity α‐linolenic acid from plant resources is challenging. The preparative separation methods of α‐linolenic acid by both conventional and pH‐zone refining counter current chromatography were firstly established in this work. The successful separation of α‐linolenic acid by conventional counter current chromatography was achieved by the optimized solvent system n‐heptane/methanol/ water/acetic acid (10:9:1:0.04, v/v), producing 466 mg of 98.98% α‐linolenic acid from 900 mg free fatty acid sample prepared from perilla seed oil with linoleic acid and oleic acid as by‐products. The scaled‐up separation in 45× is efficient without loss of resolution and extension of separation time. The separation of α‐linolenic acid by pH‐zone refining counter current chromatography was also satisfactory by the solvent system n‐hexane/methanol/water (10:5:5, v/v) and the optimized concentration of trifluoroacetic acid 30 mM and NH₄OH 10 mM. The separation can be scaled up in 180× producing 9676.7 mg of 92.79% α‐linolenic acid from 18 000 mg free fatty acid sample. pH‐zone refining counter current chromatography exhibits a great advantage over conventional counter current chromatography with 20× sample loading capacity on the same column.     

Bengal gram seed husk as an adsorbent for the removal of dyes from aqueous solutions – Column studies

A continuous fixed bed (column) study was carried out by using seed husk of Bengal gram (Cicer arietinum) (SHBG) as a biosorbent for the removal of direct dye, Congo red (CR) from aqueous solutions. The effects of important factors, such as the value of initial pH, the flow rate, the influent concentration of CR, bed depth, particle size of SHBG, foreign ions and regeneration of CR were studied. The effect of similar type of direct dyes like direct turquoise blue 86 (DTB) and direct black 38 (DB) on the adsorption of CR in column containing SHBG is also studied by keeping other parameters constant. The studies confirmed that the breakthrough curves were dependent on flow rate, initial dye concentration, size of SHBG, initial pH of solution of CR and bed depth. The bed depth service time analysis (BDST) model was applied at different bed depths to predict the breakthrough curves. The model is found suitable for describing the biosorption process of the dynamic behaviour of the SHBG column and the data were in good agreement with BDST model. When the flow rate was 0.67 mL/min and the influent concentration of CR was mg L⁻¹, the column capacity was 6.572 mg g⁻¹. The removal capacity of SHBG was more in case of CR (6.572 mg g⁻¹) compared to other similar direct dyes of DTB (1.984 mg g⁻¹) and DB (1.612 mg g⁻¹). The removal of CR was enhanced in the presence of foreign ion potassium (8.308 mg g⁻¹) and decreased in the presence of calcium (5.58 mg g⁻¹). 120 ml of acetone is required for the completion of regeneration of the column and the total amount of CR recovered in this case. All the results suggested SHBG as a potential adsorbent for removal of CR from aqueous solution so that the rate of bio-sorption process is rapid.     

Phenomenological modeling and intensification of texturing/grinding-assisted solvent oil extraction: case of date seeds (Phoenix dactylifera L.)

Accelerated Solvent Extraction (ASE) and Dynamic Maceration (DM) were used with n-hexane to study the extraction of oil from date seed powders with different particle sizes. The intensification was studied with instant controlled pressure drop (DIC) as texturing pretreatment. DM yields increased from 4.57% to 10.49 ± 0.05% dry–dry basis (ddb) when particle size decreased from 1.4 to 0.2 mm. For coarsely grounded seed powder, ASE oil yields were 11.35 ± 0.05% ddb and 14.15% ddb for untreated and DIC date-seeds, respectively. Optimized DIC pretreatment allowed the smallest particle size powder to get 15.2 ± 0.05% ddb as ASE yields, while the 2-h DM yields increased from 4.67 to 11.62 ± 0.05% ddb for particle size decreased from 1.4 to 0.2 mm, respectively. Fundamental analysis of various powders was achieved through washing–diffusion phenomenological model. DIC texturing implied higher washing stage, with relative starting accessibility %δY_s of 70% against 55% for untreated particles. Consequently, the diffusion stage time was dramatically reduced, without great modification of effective diffusivity D_eff value. Therefore, DIC ground seeds greatly enhanced the mass transfer mechanism. The evaluation of starting accessibility δY_s enables to establish an empirical relationship between δY_s and particle diameter δY_s = f(D). Finally, DIC texturing did not imply any modification of the lipid profile.     

籽晶尺寸对宝石级金刚石单晶生长的影响

本文在国产六面顶压机上,在5.6 GPa, 1250—1450℃的高压高温条件下,分别选用边长0.8, 1.5和2.2 mm三种尺寸的籽晶,系统开展了Ib型宝石级金刚石单晶的生长研究.文中系统考察了籽晶尺寸对宝石级金刚石单晶生长的影响.首先,考察了籽晶尺寸变化对宝石级金刚石单晶裂晶问题带来的影响.研究得到了籽晶尺寸变大,裂晶出现概率增加的晶体生长规律.其次,在25 h的生长时间内,考察了上述三种尺寸籽晶生长金刚石单晶时,生长时间与单晶极限生长速度的关系.得到了选用大尺寸籽晶,可以提高优质单晶合成效率、降低合成成本的研究结论.借助扫描电子显微镜和光学显微镜,对三种尺寸籽晶生长金刚石单晶的表面形貌进行了标定.最后,傅里叶微区红外测试,对三种尺寸籽晶生长宝石级金刚石单晶的N杂质含量进行了表征.研究得到了选用大尺寸籽晶实现快速生长金刚石的同时,晶体的N杂质含量会随之升高的晶体生长规律.     

连续偏振光谱的稻种发芽率检测方法研究

针对目前传统稻种发芽率检测方法周期长、精度低的问题,提出新颖的基于连续偏振光谱技术实现稻种发芽率快速、无损检测的方法。以不同老化天数稻种为检测目标,10 min为检测时间点,使用起偏器将光纤准直光源调制成线偏振光垂直入射稻种浸出液,而后以5°为间隔旋转检偏器,并通过光纤光谱仪检测透射的光谱,对检测的偏振光谱通过归一化预处理后,根据不同发芽率稻种检测时偏振角及波长的贡献给出特征偏振角和特征波长,特征偏振角为0°,5°和25°,特征波长为576,620和788 nm,将获取的连续偏振光谱以特征偏振角和特征波长处的透射率为输入,构建稻种发芽率检测模型。分别比较运用偏最小二乘法回归(partial least squares regression,PLSR)、BP神经网络(back propagation neural network,BPNN)、径向基神经网络(radial basis function neural network,RBFNN)三种建模方法建立稻种发芽率检测模型。分别用老化天数为0,2,4,6 d的稻种,在不同的偏振角共测量1 520组实验数据,其中912组数据作为校正集,608组数据作为预测集,建模结果表明三种模型预测精度较高,其中RBFNN模型预测精度最高,其相关系数r为0.976,均方误差RMSE为0.785,平均相对误差MRE为0.85%。表明利用连续偏振光谱技术通过多维度光谱信息能够有效实现稻种发芽率的快速、准确检测。     

葫芦脲用作固相微萃取涂层新材料

本文对葫芦脲(CB)作为一种新型固相微萃取(SPME)涂层材料进行了研究并用于中药白豆蔻的气相色谱分析测定.本文采用的CB SPME涂层制备方法简便、快速,并具有良好的热稳定性和重复性.CB[6]SPME萃取得到的主要成分与水蒸气蒸馏（SD）法基本一致,并且CB[6]SPME对色谱后流出的目标成分的相对峰面积比明显高于SD法和商品SPME萃取材料PDMS/CAR和PDMS/DVB,这可能是由于葫芦脲的特殊分子结构及其与组分分子间选择性作用所致.葫芦脲作为一种新型SPME涂层材料具有很大的研究潜力和应用前景.     

化学溶液法制备涂层导体过渡层La2Zr2O7厚膜的研究

为制备高质量的双轴织构La2Zr2O7(LZO)涂层导体过渡层,本文采用化学溶液法(Chemical solution deposition,简称CSD法),以乙酰丙酮镧和乙酰丙酮锆为溶质,丙酸为溶剂配制成前驱盐溶液,在立方织构的Ni-5 at;W基底上用快速一步法退火工艺制备了LZO种子层及双层LZO厚膜.SEM观察种子层呈岛状均匀排列,符合种子层形貌特点.XRD结果显示0.06 mol/L浓度种子层上制备的LZO厚膜具有很强的双轴立方织构,其中(222)面Phi扫描和(400)面摇摆曲线半高宽值分别为6.37°和5.82°.SEM观察发现120 nm厚的LZO薄膜表面平整,无裂纹,为后续沉积YBCO提供了很好的模板.     

种子溶胀法制备单分散高交联聚苯乙烯微球

以分散聚合法制得平均粒径为1.80μm的聚苯乙烯微球为种子,与溶胀剂和单体、交联剂的混合物经二步溶胀聚合法,制备了单分散高交联聚苯乙烯微球。讨论了单体浓度和醇水比对种球的影响,以及溶胀剂的种类、溶胀剂浓度、交联剂浓度、溶胀温度和搅拌速度等因素对交联聚苯乙烯微球粒径及分散系数的影响。用扫描电子显微镜、离心式粒度分析仪及DSC分析测试技术对微球的外观形貌、粒径大小及分布和玻璃化转变温度分别进行了表征。结果表明,当溶胀剂质量分数为25%、交联剂质量分数为23%、溶胀温度30℃、搅拌速度为150r/min时,可制得平均粒径为6.20μm且单分散性较好的高交联聚苯乙烯微球。