超声波辅助提取大新苦丁茶中总黄酮的工艺研究

以广西大新县苦丁茶作为原材料,采用超声波辅助提取总黄酮,以芦丁为对照品,用分光光度法检测总黄酮含量。通过单因素试验讨论料液比、乙醇浓度、超声时间、超声温度4个因素对总黄酮提取率的影响,通过正交试验确定最佳提取工艺。试验结果显示：超声波辅助提取法的最佳提取条件为料液比1∶25（g/mL）、乙醇浓度70%、超声时间15 min、超声温度50℃,此时总黄酮的提取率为0.772%。     

恩施州发电企业发展中存在的问题与对策

综述了恩施自治州50多年来水电开发的情况,分析了州内中小发电企业面临的困难,查明了企业发展缓慢的原因。提出了解决的对策。     

转型期地方本科院校工业分析实验教学改革探究

工业分析实验课程是一门应用型的专业核心课程,旨在培养学生的实践操作和创新能力。但在工业分析实验目前的教学中普遍存在教学方法单一、实验项目陈旧、实验方法与新国标存在差距、教学评价存在局限性等现象。为培养满足地方经济建设所需的应用型化学专业人才,对工业分析实验课程的实验内容进行更新,增加综合性设计性实验,改进教学方式和课程评价体系。     

机械活化木薯淀粉羧甲基化产物糊性质的研究(Ⅰ)

采用搅拌球磨机对木薯淀粉进行机械活化,以活化60min的木薯淀粉为原料,NaOH为催化剂,ClCH2COOH为醚化剂干法制备羧甲基淀粉,对羧甲基淀粉的溶解度,糊的透明度、冻融稳定性、抗老化能力、抗生物降解能力及表观黏度等性质进行研究。结果表明:机械活化木薯淀粉羧甲基化产物的溶解度大、糊的透明度好、抗生物降解能力强、黏度高,有较好的冻融稳定性及抗老化能力。     

GaN-on-Si blue/white LEDs: epitaxy, chip, and package

The dream of epitaxially integrating III-nitride semiconductors on large diameter silicon is being fulfilled through the joint R&D efforts of academia and industry, which is driven by the great potential of Ga N-onsilicon technology in improving the efficiency yet at a much reduced manufacturing cost for solid state lighting and power electronics. It is very challenging to grow high quality Ga N on Si substrates because of the huge mismatch in the coefficient of thermal expansion(CTE) and the large mismatch in lattice constant between Ga N and silicon, often causing a micro-crack network and a high density of threading dislocations(TDs) in the Ga N film.Al-composition graded Al Ga N/Al N buffer layers have been utilized to not only build up a compressive strain during the high temperature growth for compensating the tensile stress generated during the cool down, but also filter out the TDs to achieve crack-free high-quality n-Ga N film on Si substrates, with an X-ray rocking curve linewidth below 300 arcsec for both(0002) and(10N12) diffractions. Upon the Ga N-on-Si templates, prior to the deposition of p-Al Ga N and p-Ga N layers, high quality In Ga N/Ga N multiple quantum wells(MQWs) are overgrown with well-engineered V-defects intentionally incorporated to shield the TDs as non-radiative recombination centers and to enhance the hole injection into the MQWs through the via-like structures. The as-grown Ga N-on-Si LED wafers are processed into vertical structure thin film LED chips with a reflective p-electrode and the N-face surface roughened after the removal of the epitaxial Si(111) substrates, to enhance the light extraction efficiency. We have commercialized Ga N-on-Si LEDs with an average efficacy of 150–160 lm/W for 1mm~2 LED chips at an injection current of 350 m A, which have passed the 10000-h LM80 reliability test. The as-produced Ga N-on-Si LEDs featured with a single-side uniform emission and a nearly Lambertian distribution can adopt the wafer-level phosphor coating procedure, and are suitable for directional lighting, camera flash, streetlighting, automotive headlamps, and otherlighting applications.     

氧化铟包覆镍锰酸锂正极材料的电化学性能研究

为改善镍锰酸锂的电化学性能,以硝酸铟(In(NO₃)₃·H₂O)为原料,通过高温固相法在镍锰酸锂电极材料表面包覆一层惰性氧化铟(In₂O₃),并研究不同In₂O₃包覆量对镍锰酸锂复合材料的电化学性能的影响。XRD测试结果显示,包覆氧化铟并不会改变正极材料LiNi_0.5Mn_1.5O₄自身结构。当包覆量为7%时,在0.1 mA的测试电流下首次放电比容量为134.21 mAh/g,明显高于未涂覆材料(115.65 mAh/g),100次循环后容量为128.4 mAh/g,容量保持率为95.67%;在0.5 mA的测试电流条件下,首次放电比容量为78.13 mAh/g, 100次循环后比容量为56.25 mAh/g,容量保持率为64.44%。In₂O₃包覆起到保护材料和促进离子传导的作用,可有效提高正极材料的电化学性能。     

机械活化木薯淀粉干法制备羧甲基淀粉的研究

研究了以机械活化60 min的木薯淀粉为原料,采用干法工艺制备羧甲基淀粉(CMS).探讨了机械活化时间、反应时间、反应温度、催化荆用量、醚化剂用量及体系含水量对木薯羧甲基淀粉取代度(DS)的影响.实验结果表明,机械活化对木薯淀粉的羧甲基化反应有显著的强化作用:木薯淀粉的DS随活化时间的延长而增大.活化60 min的样品在条件为反应时间120 min、ClCH2COOH与淀粉的摩尔比0.55、NaOH与淀粉的摩尔比0.55、反应温度60℃、体系含水量18%时制得的CMS的DS为0.88%,而在相同条件下,由原木薯淀粉制得的CMS的DS仅为0.23%.     

薛荔藤多酚提取工艺优化及其抗氧化活性

以广西崇左薛荔藤为原材料,采用超声辅助法提取薛荔藤多酚,通过正交试验设计优化提取工艺,并研究薛荔藤多酚对·OH、DPPH·及NO·的清除效果,探究其抗氧化活性。正交试验优化得到薛荔藤多酚最佳提取工艺：丙酮体积分数为70%、料液比为1∶35（g/mL）、提取温度为55℃,提取时间为60 min,在此条件下薛荔藤多酚得率为6.08%。薛荔藤多酚对·OH、DPPH·及NO·的清除能力与浓度呈正相关,在浓度为2.50 mg/mL时,对·OH的清除率达91.39%,表明薛荔藤多酚具有较好的抗氧化活性。     

Preparation of GaN-on-Si based thin-film flip-chip LEDs

GaN based MQW epitaxial layers were grown on Si(111) substrate by MOCVD using AIN as the buffer layer.High light extraction LEDs were prepared by substrate transferring technology in combination with thin-film and flip-chip design.The blue and white 1.1×1.1 mm~2 LED lamps are measured.The optical powers and external quantum efficiency for silicone encapsulated blue lamp are 546 mW,and 50.3%at forward current of 350 mA, while the photometric light output for a white lamp packaged with standard YAG phosphor is 120.1 lm.     

机械活化木薯淀粉干法制备氧化淀粉的研究

采用搅拌球磨机对木薯淀粉进行机械活化,以不同活化时间的木薯淀粉为原料、CuSO4为催化剂、H2O2为氧化剂干法制备氧化淀粉,并以羧基含量为评价指标,分别考察了活化时间、反应时间、反应温度、氧化剂用量、催化剂用量、pH值、体系含水量等因素对木薯淀粉氧化反应的影响.实验结果表明,机械活化对木薯淀粉的氧化反应有显著的强化作用,活化时间越长,木薯淀粉被氧化的程度越深,羧基含量越高.活化1 h的样品在制备条件为反应时间120 min、H2O2与淀粉的摩尔比0.586、催化剂CuSO4在淀粉中的质量分数0.03%、反应温度50℃、体系含水量27.37%、体系pH值等于5时制得的氧化淀粉羧基含量为0.81%,而在相同条件下,由原木薯淀粉制得的氧化淀粉羧基含量仅为0.26%.