桑叶中总生物碱的提取、抗氧化及抑菌性能研究

试验以桑叶为原料,采用超声辅助提取法提取总生物碱,在单因素试验基础上,采用正交试验对提取条件进行优化,并对桑叶生物碱进行抗氧化和抑菌活性研究。结果显示,桑叶中总生物碱最佳提取条件为乙醇体积分数50%、液料比25 mL/g、提取温度70℃、提取时间40 min;相同浓度下(0.2~1.0 g/L),桑叶中总生物碱对1,1-二苯基-2-三硝基苯肼(DPPH)和2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐(ABTS^(+))自由基的清除率最高分别可达85.5%和96.3%,其抗氧化性强于维生素C;桑叶总生物碱对细菌的抑制作用强于山梨酸和乙醇溶液,对金黄色葡萄球菌和大肠杆菌抑菌圈直径大于10 mm,对细菌具有较强的抑制作用。研究表明,可以将桑叶中总生物碱作为功能性饲料添加剂应用于动物养殖行业。

玫瑰红景天挥发性成分分析及其抗氧化和抗菌活性

目的:提取玫瑰红景天根茎中的挥发性物质,测试抗氧化和抗菌活性,为玫瑰红景天的综合利用提供科学依据。方法:采用水蒸气蒸馏法提取玫瑰红景天根茎中的挥发性物质,经GC-MS分离和鉴定,借助GC用系列正构烷烃对各组分进行定性,面积归一化法确定各组分的相对含量;通过H2O2/Fe^2+体系考察对羟基自由基的清除作用;用微量肉汤稀释法测定最小抑菌浓度(MIC)和平板转种法测定最小杀菌浓度(MBC)确定抗菌活性。结果:从玫瑰红景天挥发性物质中鉴定出53种化合物,主要组分有1-辛醇(42.72%)、香叶醇(29.85%)、苯乙醇(9.67%)、桃金娘烯醇(2.69%)、芳樟醇(1.89%)等,玫瑰红景天挥发性物质对羟基自由基有清除作用,其半抑制浓度IC50为0.0073 mg/m L,对抗菌试验所选的7个菌株均有抑制作用,对金黄色葡萄球菌ATTCC25925的MIC值是0.12 mg/m L、MBC值是0.36 mg/m L,对大肠杆菌ATCC25922的MIC值是0.58 mg/mL、MBC值是1.90mg/mL。结论:通过水蒸气蒸馏法提取得到的玫瑰红景天根茎挥发性物质的组分丰富多样,是一种天然的抗氧化、抗菌活性物质。

氯唑沙宗在不同溶剂中溶解度的测定与关联

氯唑沙宗是一种口服有效的中枢性骨骼肌松弛剂,通过固液相平衡实验可为其合成及纯化工艺中溶剂的选择提供基础数据。采用动态平衡法测定了288.15—318.15 K温度范围内氯唑沙宗在甲醇、乙醇、正丙醇、二氧六环、乙酸乙酯、四氢呋喃和乙腈中的溶解度。结果表明:氯唑沙宗在这7种溶剂中的溶解度均随温度的升高而增大,其中在四氢呋喃中的溶解度最大、乙腈中最小。采用Apelblat方程、λh方程、NRTL和Wilson模型对溶解度数据进行了关联,数据表明实验中的二元体系的关联结果都较好地与实验值相吻合,对比平均相对标准偏差,Wilson模型(平均RSD=0.69%)的关联结果是4种模型中最佳的。

“化工原理实验”教学改革的几点思考

“化工原理实验”是培养学生实验研究和实践操作等综合能力的实验课程,是化工及其相近专业重要的实践教学环节。以“化工原理实验”课程特点为切入点,从充分利用现代教育技术提高实验指导老师实践能力和构建化工实验实践教学体系等方面,探讨“化工原理实验”教学改革,构建课程体系,强化实验教学,培养综合能力,提高教学质量。

三观教育在工业催化课程思政建设中的探讨与实践

工业催化课程是化学专业的一门选修课,也是化学工程与工艺专业的重要专业课之一。文章将思政元素引入课程教学中,以三观教育为切入点,分别从工业催化知识点与思政元素相结合、催化科学前沿问题讨论和创新实践能力三方面,介绍如何将思政教育有机融入课程内容设置和课堂讲授等环节,力求培养学生具有正确的世界观、价值观和人生观,充分发挥专业课程的德育功能,切实提高本科教学质量。

植酸提取的研究进展

植酸在食品、冶金、化工及医药等诸多领域有着广泛的应用。本文对脱脂米糠中提取、纯化植酸的工艺研究进展进行了综述,探讨了目前研究中存在的问题,并且提出了植酸提取方法今后研究及应用的发展方向。

地方高校“化工原理”课程的教学改革探究

以新工科背景下的化学工程教育认证要求为基准,以地方高校本科化学工程与工艺专业学生特点为抓手,明确“化工原理”课程目标;以项目教学法为引导,积极探索以课程单元目标产出导向的目标导向制、翻转课堂等教学方法、模式改革,积极探索行之有效的课程教学过程质量监控方法,形成厚基础、创新型化工应用型人才的培养模式。

功能型氟硅聚合物涂层的研究进展

氟硅聚合物涂层是一种以有机硅、氟改性有机硅或有机氟为基体的材料,具有表面能低、稳定性高、易加工等特点,广泛应用于国防军事、轻工、机械、化工、医学等领域。综述了近年来氟硅聚合物常用的合成方法,如原子转移自由基聚合(ATRP)法、阴离子开环聚合法、硅烷偶联剂法、硫醇–烯点击法等,采用上述方法合成的氟硅聚合物,因其有序的氟/硅–碳排列,使得制备的涂层材料具有润湿性低和稳定性高等特点,在防污、抗菌等领域有着巨大的应用前景。同时,综述了不同维度材料修饰的氟硅聚合物涂层的研究进展,如一维材料(纳米线、纳米管等)、二维材料(片状硫化铜、石墨烯、MXene、氮化硼等)和三维材料(CeO_(2)、SiO_(2)、Fe_(3)O_(4)等颗粒及微胶囊)。对不同维度材料在防覆冰、抗菌、导电、导热、红外隐身、光催化、自修复等领域的应用和作用机制进行了分析。此外,综述了有机链段(聚氨酯、环氧树脂、聚甲基丙烯酸甲酯等)改性的氟硅聚合物涂层在医学、防污、自修复等领域的应用,并对其作用机制进行了分析。最后,对氟硅聚合物涂层研究中存在的问题进行了归纳,并对其发展方向进行了展望。

M-(Sm, Pr, Ga)掺杂TiO_2带隙及电子结构的第一原理研究（英文）

采用密度泛函理论对M-(Sm、Pr、Ga)掺杂锐钛矿型TiO_2能带和电子性质进行了系统的理论研究.计算结果表明,通过Sm和Pr的掺杂可以降低TiO_2的带隙进而使其产生吸收边红移,通过Ga的掺杂能使带隙稍增加.这主要是由于Sm和Pr的掺杂使Sm和Pr上的4f层电子与原子相邻O原子上的2p层电子相互作用,形成的杂质能级影响了Ti-O的能带结构,从而降低带隙,提高TiO_2的可见光吸收性能.

超声波辅助提取紫甘蓝色素及稳定性研究

以紫甘蓝鲜叶为原料,通过超声波辅助提取紫甘蓝色素,在探究紫甘蓝色素提取的单因素试验基础上,设计正交试验寻找出紫甘蓝色素提取的最优条件,并进一步探究温度、光照、蔗糖、食盐、金属离子以及防腐剂对紫甘蓝色素稳定性的影响。试验结果表明,紫甘蓝色素提取的最优条件为:以蒸馏水为提取剂,控制料液比为1∶6(g/mL),提取pH值为2,提取温度为50℃,提取时间为50 min,在该工艺条件下紫甘蓝色素的提取效果较为显著。紫甘蓝色素稳定性试验结果表明,在日光光照、温度过高以及添加苯甲酸钠防腐剂的条件下会破坏紫甘蓝色素的稳定性,蔗糖、食盐可以与紫甘蓝色素一同使用,对稳定性影响不明显,金属离子Mg^(2+)、Cu^(2+)对紫甘蓝色素的稳定性无明显影响,Fe^(2+)、Na^(+)、K^(+)、Zn^(2+)对紫甘蓝色素的稳定性有促进作用,而Fe^(3+)则会降低紫甘蓝色素的稳定性,并使色素溶液颜色变为棕色。该研究结果可为紫甘蓝鲜叶在食用调味品中的利用提供理论参考。

Diode-Laser-Array Single-End-Pumped 5W Nd:YVO_(4)/KTP Continuous-Wave Solid-State Green Laser

Continuous-wave radiation of 5W at 532 nm was produced with an Nd:YVO_(4)/KTP intracavity&equency-doubled laser end-pumped by a diode-laser-array at pump power of 17.2 W,giving optical conversion efRciency of 29.1%.The output power stability was measured to be better than 1.5%in short term operation.The pump-induced thermal lensing was also measured,showing good agreement with the performance of the laser.

Thermal Lens Determination of End-Pumped Solid-state Lasers by a Simple Direct Approach

The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal.There exists a critical point between stable state and unstable state at which the thermal focal length equals the distance from the center of the crystal to one end mirror.Based on this fact,a new method for measuring the thermal focal length of the laser crystal has been presented and applied to a Nd^(3+):YVO_(4) crystal at various absorbed pump power levels up to 10 W.The results have shown to be in good agreement with theoretical calculation.

Anisotropy of Nonlinear-Optical Property of RCOB (R = Gd, Y) Crystal

The nonlinear-optical coefficients of RCOB(R=Gd,Y)crystals are measured.The spatial distribution of deff effective nonlinear-optical coefficient is determined subsequently.Our experiments show that the maximum deff occurs at the second quadrant.The second-harmonic-generation efficiency reaches 48%for a 6 mm-long,(113.2°,47.4°)-cut GdCOB,and 41.5%for a 5mm-long,(113°,36.5°)-cut YCOB,respectively.The intracavity frequency doubling of GdCOB is reported for the first time.

交联阳离子淀粉制备及金属离子吸附研究

以玉米淀粉为原料,制备交联淀粉和交联阳离子淀粉,对重金属离子进行吸附。结果表明,交联淀粉制备的最优条件为:NaOH用量0.3 g,六偏磷酸钠用量0.16 g,反应温度55℃,反应时间150 min。在此条件下,沉降积达到最小值为0.75 mL,交联淀粉的交联度最佳。交联阳离子淀粉对Cu^(2+)、Zn^(2+)、Cd^(2+)、Hg^(2+)均有很好的吸附能力,对Cu^(2+)吸附率达93.0%,Zn^(2+)吸附率达72.5%,Cd^(2+)吸附率达80.1%,Hg^(2+)吸附率达92.5%。

Effect of Strontium Ion on the Growth and Second-Harmonic Generation Properties of GdCa_(4)O(BO_(3))_(3) Crystal

Large sized and optical quality GdCa_(4)O(BO_(3))_(3)(GdCOB)crystal with calcium partially substituted by strontium(Sr)ions was grown for the first time.The x-ray powder diffraction shows that the Sr ion has an effect on the cell parameters of the GdCOB crystal Second-harmonic generation(SHG)experiments were performed on the Sr:GdCOB and GdCOB crystals along the spatial phase-matching direction.The results show that the cw green laser output power is 1.04 W when the laser diode pump power is 10 W in the Nd:YVO_(4)/Sr:GdCOB intracavity laser.Considering the slope efficiency of Nd:YVO_(4) and the fundamental laser in cavity,the intracavity SHG conversion efficiency of the GdCOB crystal is 21%while it is 24%for the Sr:GdCOB crystal,the SHG conversion efficiency is improved by 14%.The effect of the Sr ions on the nonlinearity of the GdCOB crystal is also discussed by using the anion group theory.

加筋土桥台筋材轴力计算方法的对比与分析

加筋土桥台具有成本低廉、施工简便、台下放坡占地需求小、对不均匀沉降适应性强等优势,近年来在中外交通工程中广泛应用于跨线桥和涵洞桥等短跨度桥梁的建设中。加筋土桥台筋材的受力计算是结构设计中的重点。本文针对某高速公路试验段的非承重加筋土桥台设计方案,分别采用基于极限平衡理论的《土工合成材料应用技术规范》方法和改进K刚度法,以及基于极限状态理论的荷载和抗力系数方法计算了工作应力下格栅的轴力。结果显示通过改进K刚度法计算的格栅轴力明显小于另外两种方法的结果。文章还对结果进行了分析,并讨论了三种计算方法在设计中的应用前景。

The Laser Action of a Yb:CLNGG Crystal with an Efficiency Approaching Its Quantum Defect Imposed Limit

Continuous-wave laser operation is demonstrated at room temperature with a new disordered Yb:CLNGG crystal.A maximum output power of 5.05 W is generated with 7.8 W of pump power absorbed in the crystal,resulting in an optical-to-optical efficiency of 65%,whereas the slope efficiency is determined to be 92%,approaching the limit imposed by the quantum defect in the laser emission process.

Growth and Second-Harmonic-Generation Properties of Tm^(3+), Yb^(3+), Bi^(3+) and Li^(+) Doped GdCa_(4)O(BO_(3))_(3) Crystals

The rare-earth ions(Yb^(3+),Tm^(3+))and Li^(+),Bi^(3+)ions doped GdCa_(4)O(BO_(3))_(3) crystals were grown using the Czochralski pulling method.The second-harmonic-generation conversion efficiencies of the GdCOB:Yb and GdCOB:Tm crystals are 31.3%and 33.3%,respectively,while the undoped GdCOB crystal is 27.9%.The conversion efficiencies of Yb^(3+),Tm^(3+)doped GdCOB are improved by 12%and 19%,respectively,compared to that of the undoped one.The conversion efficiencies of Li^(+),Bi^(3+)doped GdCOB crystals are 33%and 38.3%,which are improved by 15%and 37%as compared to that of the undoped crystal.The results are discussed using the anion group theory.

Thermal Lensing Measurement and Laser Performance of End-Pumped Lightly Doped Nd:GdVO_(4) Crystal

The thermal lensing effect generated in an end-pumped lightly doped Nd:GdVO4 crystal was found to be considerably weaker than that in Nd:YVO4 having the same Nd3+ concentration. Consequently, the laser performance of Nd:GdVO4 at high pump powers over 20 W was found to be superior to that of Nd:YVO4. TEM00 mode cw radiation of 14.3 W at 1.06μm was achieved with an optical conversion efficiency of 55%, and average slope efficiency of 62%.

Self-Frequency Doubling Laser Performance of Nd:GdCOB Crystal with a Phase-Matching Angle Out of the Principal Plane

The self-frequency doubling laser performance of Nd:GdCOB crystal cut in phase-matching direction(θ=66.3°,Ф=134.4°)was compared with the crystal cut in the direction of(θ=90°,Ф=46°).Results show that the former has a higher second-harmonic conversion efficiency than the latter.Using Ti:sapphire laser as pumping source,a maximum of 11.3mW of green light has been obtained with an incident power of 520mW.This corresponds to an optical-optical conversion efficiency of 2.2%.Laser threshold for self-frequency doubling operation is measured to be 1 mW.To our knowledge,this is the lowest threshold achieved so far.