可控释放与农药缓释剂

讨论了可控释放的机理及可控释放在农业方面的应用并展望了其前景。     

利用导电复合水凝胶控制药物释放

传统的给药方法,输入到人体内药物量大且浓度降低速度快,纳米级对药物的可控释放进行研究,尤其导电复合水凝胶材料通过电信号刺激对药物实现可控释放,受到越来越多的关注。本文综述了近年来学术界对导电水凝胶的制备与改性,并且将其应用于药物释放方面的进展,为进一步将导电材料应用于控制药物释放方面的研究奠定基础。     

缓释型固体二氧化氯的研究及应用进展

缓释型固体二氧化氯因其释放周期较长、稳定性强、释放速率可控等优点迅速发展成为消毒剂领域的研究热点。论述了缓释型固体二氧化氯的制备方法、应用进展、目前存在的问题,以及未来缓释型固体二氧化氯的研究方向。     

环境响应型控制释放农药技术研究进展

具有精确控制释放模式的智能农药能对光敏感、热敏感、湿度敏感、土壤pH和酶活性等微生态环境变化做出响应;还介绍了利用纳米材料建立智能化、可控的农药释放技术;这些技术可以增加农药负载量,提高活性成分的分散性和稳定性,提高靶向性。     

PNIPAM改性纤维素球调控布洛芬释放

简要介绍了聚(N-异丙基丙烯酰胺)(PNIPAM)改性的纤维素球对药物的可控释放,该产物具有温度敏感和p H值敏感的特性。运用可逆加成-断裂链转移聚合反应,将PNIPAM链接到纤维素微球上,分别采用傅里叶变换红外光谱,扫描电子显微镜,透射电子显微镜,X射线光子能谱分析和热重分析等方法,证实了PNIPAM成功地链接到纤维素微球上。PNIPAM-纤维素微球的直径为1.2~2μm,具有良好的生物相容性,有利于用作药物载体控制药物释放。布洛芬被选择作为模型药物分子以测试PNIPAM-纤维素微球的药物负载和释放性能。结果表明,PNIPAM-纤维素球的布洛芬释放速度在25℃比在38℃快,在p H值7.4快于p H值4.0。由于PNIPAM-纤维素微球的热敏性和p H值敏感性,使得它可以广泛应用于可控的药物释放。     

铜微球对防污剂异噻唑酮的控释作用

生物污损使舰船航速降低，灵活性减弱，燃料消耗增加，壳体的腐蚀加速。常用的解决办法是用含毒性物质的防污漆，如含氧化亚铜、有机锡的防污漆，但它们用后严重污染海洋生态环境，使许多海洋生物发生畸变。可控释放技术由于释放速度和释放质量可以控制，在提高药效、降低环境污染方面具有独特优点。     

药物纳米胶囊的制备及其缓释研究

以石蜡为囊芯材料,Si O2为胶囊的囊壁材料,通过微乳法制备无晶型二氧化硅包裹苏丹红Ⅲ的缓释单分散纳米球形颗粒。用生物显微镜和电子扫描显微镜观察缓释球形态,用紫外-分光光度计测定其释药特性。结果表明:微乳法制备的缓释球光滑圆整、尺寸可控。微球释放时间可达80 h,具有显著的缓释作用。同时,研究了其释放药物速度与二氧化硅厚度、温度、蜡球尺寸等的关系,缓释球可通过控制药物的缓释速度达到可控的目的。     

稳定二氧化氯的研究进展及发展方向

介绍了二氧化氯的性质、作用，稳定性二氧化氯溶液及固体二氧化氯消毒剂在世界上的发展历程以及研究进展，对可控释放二氧化氯的研究进行了探讨。指出利用智能高分子材料的特殊性能，结合吸附控制理论、传递理论、反应工程等理论，二氧化氯的发展方向能够实现控制释放，使之具有普遍化意义及市场价值，以有利于环境保护，有利于建设节约型社会，有助于实现人类的可持续发展。     

中国农科院植保所发现农药控释新材料

正近日,中国农业科学院植物保护研究所农药化学与应用创新团队农药剂型与分析组创新发现了碳量子点修饰的双壳层介孔二氧化硅,可实现农药吡唑醚菌酯的高效负载、可控释放以及在病原菌体内的可视化研究,相关研究成果发表在《纳米尺度》(Nanoscale)上。根据有害生物发生规律、危害特点及环境条件,设计可合理调控活性成分释放速率的农药控制释放技术,是目前提高农药利用率最为有效的途径之一。     

智能型水凝胶的研究进展

介绍了水凝胶的几种主要制备方法,重点介绍了对温度、pH值、光、电、磁、生物分子敏感的水凝胶的近期研究成果,概述了水凝胶在药物可控释放、酶的固定、生物支架材料、智能纺织品等方面的应用进展。     

煤炭地下气化高温井筒温度场研究

基于井筒与地层的传热情况,根据能量守恒及井筒传热原理,考虑物性参数随温度和压力变化,建立了生产井井筒的温度场预测模型,形成了求解算法和数学仿真模型,研究了温度场的影响因素。结果表明:产出气各物性沿井深分布差异较大,在分析时有必要耦合考虑;随着日产量和井底温度增加,井筒各段的温度均上升,其中日产量在30×10⁴ m³/d时,井口的产出气温度最高(686℃),井底温度在1000℃时,井口温度为588℃;井底压力对温度场影响很小,在工程应用中可忽略不计;随着井深增加,井口温度下降。     

晶须长径比对复合材料力学行为影响的模拟

在单向晶须增强树脂基复合材料的轴对称模型和已有研究成果基础上,利用有限元分析方法,研究该类复合材料中晶须长径比的变化对材料整体力学行为的影响.结果表明:1)晶须长径比对晶须应力作用明显大于对基体的影响;2)晶须的长径比h/r≤30时,随着晶须长径比的增大,发生在晶须端部处的集中应力急剧增加;但当长径比h/r≥30时,长径比的进一步增加对集中应力影响不大;3)随着晶须长径比的增大,界面剪切应力减小,分布曲线下移;但当长径比h/r≥30时,长径比的进一步增加对剪切应力影响不大;4)随着晶须长径比的增加,复合材料的拉伸强度逐渐增大.     

The service of the hearths of arc furnaces for melting stainless steels with the use of oxygen

Conclusions During the operation of arc furnaces specializing in the melting of stainless steels, chemical and phase changes occur in the magnesite hearths which lead to the formation of a single type structure in the monolith of rammed layer and upper courses of the structure.Petrographic studies showed that the monolith was formed as a result of phase inversions of the minerals of the hearth under the influence of the silicate constituents of the slag being produced, which partly settles to the bottom after discharge of the melt. These inversions greatly affect the physicochemical properties of the hearth and especially the refractoriness. The inversions which increase the refractoriness include the process of recrystallization of the periclase and chrome-spinel with the formation of strong and dense periclase-spinel growths in the upper layers of the hearth.The reduction in the refractoriness occurs owing to the formation of montichellite under the influence of calcium slag constituents and the gradual replacement of the forsterite by this silicate, and also the partial solution of periclase in the silicate melt.The thermal resistance of the hearth is favorably affected by the fact that the new silicate formations are distributed irregularly over the height of the hearth, and the nature of the distribution depends on their fluidity and temperature gradient in the hearth. In view of this consistency, the most refractory silicates, such as forsterite and mervenite, are localized in the upper strata of the hearth, and the montichellite, being the most fusible silicate, migrates to the lower layers.The result of all the processes and phase inversions taking place in the hearth is that the refractoriness of the most important layers of hearth (upper and middle) remains high during service. The reduction in refractoriness in the lower layer cannot greatly affect the life of the hearth since this layer is quite far away from the working region of the furnace and is in the low-temperature region.Large amounts of metals are detected only in the part of the hearth located in direct contact with the furnace bath; metal does not take a large part in the processes occurring in the hearth.The positive influence of the additions of chromite on the life of the hearth of electric furnaces determined during operation, can be explained by the fact that the chromite is essential for the formation of refractory chromespinel phases [2], contributes to the formation of periclase-spinel growths in the upper parts of the hearth, and accelerates the process of removing the less refractory silicates from the upper layers of the hearth to the lower [3].     

直缝式燃烧器W火焰锅炉新型二次风箱特性研究

为解决直流缝隙式燃烧器W火焰锅炉原设计的全通二次风大风箱由于锅炉炉膛宽度宽、风箱截面尺寸大等原因产生的炉膛中部缺风问题,华能上安电厂将4号锅炉原风箱改造为分隔型新型二次风箱。新型二次风箱改造完成后对其特性的试验研究表明,常规冷态通风时拱上、拱下各喷口及各风道区域之间风速偏差较小。单侧送风机运行且联络门关闭时,送风机停运侧各喷口风速明显低于送风机工作一侧,但通过拱上、拱下二次风门的调整,能有效缓解由于单侧送风机运行带来的喷口风速偏差。单侧送风机运行联络门开启的情况下,3个风道区域平均风速的偏差与正常双送风机运行时差别不大。与改造前相反,锅炉运行炉膛出口氧量已呈现中间高两头低的趋势,适当调整二次风箱风门开度后炉膛出口氧量分布趋于均衡,说明改造后的二次风箱风门能有效调节炉内二次风配风进而改变炉膛出口氧量分布。通过二次风箱风门开度的适当调整,能有效降低SCR入口NOx浓度,保证锅炉经济环保运行。     

Effect of preparation conditions on the properties of microspheres prepared using an emulsion-solvent extraction process

Methylaluminoxane microspheres were prepared using a hydrocarbon-in-perfluorocarbon-emulsion solvent extraction process. The effect of the preparation conditions on the size of the microspheres was investigated. As expected, the size of the microspheres decreased with increasing stirring speed. At low surfactant concentrations the size of the microspheres was independent of the surfactant concentration. However, the size of the microspheres decreased as the surfactant concentration was further increased. The size of the microspheres was not only affected by the surfactant concentration but also by the volume ratio of the dispersed phase to the continuous phase. At a low volume ratio of the phases the effect of the surfactant on the size of the microspheres was larger than the effect of the increased volume ratio of the phases. At high volume ratios of the phases the effect of the volume ratio of phases on the size of the microspheres became more significant than the effect of the surfactant. A slow solidification increased the formation of non-spherical microspheres.     

The role of the symmetry and the flexibility of the anion on the characteristics of the nanostructures and the viscosities of ionic liquids☆

The transport properties of ionic liquids (ILs) are crucial properties in view of their applications in electrochem-ical devices. One of the most important advantages of ILs is that their chemical–physical properties and conse-quently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the“rigidity”, the order, and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be con-trolled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion.     

纳米填料/橡胶体系在贮存中的结构形态变化Ⅱ.结构变化的影响因素及其对性能的影响

综述了纳米填料／橡胶复合体系在熔融态或高弹态贮存停放过程中,影响其结构形态变化的因素,以及贮存停放对复合体系流变性能、物理机械性能和导电性能的影响,并评述了相关的理论模型。纳米填料／橡胶复合体系在熔融贮存过程中的结构变化主要受橡胶的黏度、填料特性及其用量、填料与橡胶之间的相互作用以及加工性能的影响。填料网络结构的絮凝程度强化使复合体系流变性能、动态力学性能降低,但导电性能提高。相关的填料聚集动力学和填料絮凝模型大部分是唯象模型。     

复合材料风扇叶片榫头铺层设计及加工制造

碳纤维复合材料风扇叶片榫头段是铺层数量最多、递减铺层最集中的部位,榫头的铺层质量影响叶片的低周疲劳强度。为完成叶片榫头段的铺层设计,基于铺层设计准则,建立了一种适用于航空发动机复合材料风扇叶片榫头段铺层设计的方法。根据铺层高度大小将铺层分为结构层和插入层,在结构层铺层设计中考虑了高度递减层的角度与铺放位置。在插入层铺层设计中,考虑了单组插入层铺层数量、单组插入层内部铺层顺序及铺层角度、单组插入层形成的坡度、相邻插入层之间的错开距离等五个方面的因素,确定了单组插入层的结构及其在榫头的分布。根据设计方案对榫头进行加工制造,成型的榫头试样件厚度检测质量良好,证实了该铺层设计方法的可行性。     

转炉一次除尘新OG系统高效喷淋塔喷嘴布置方式对喷淋特性的影响

采用离散相模型对新OG系统高效喷淋塔入口段及主体段喷嘴的布置方式进行数值模拟,考察了喷嘴喷射方向和喷淋层数对雾化场气流分布和降温效果的影响。结果表明,喷嘴的喷射方向和塔内的喷淋层数对雾化场的气流分布和降温效果影响较大;喷淋塔入口段采用逆流喷射时,出口截面的速度分布最均匀且降温效果最好;高效喷淋塔的主体段的喷淋层数为5时,塔内烟气的速度流场较均匀,且中心区域的气流速度为2~4 m/s,有助于延长气体与液滴的作用时间;随喷淋层数增加,塔内温度梯度变化增大,水蒸气质量分数分布与温度分布对应,塔内的平均湍动能逐渐增高。     

聚丙烯气相反应器工艺参数的计算和控制

以液相本低聚合和气相聚合组合式聚丙烯（PP）装置生产多相共聚PP产品为例，推导出了多相共聚PP生产中气相反应器工艺参数之间的关系式，并讨论了工艺参数对产品性能的影响，通过控制气相反应器的乙烯进料量与气相比，改变产品的抗冲击性能，乙烯含量越高，产品的抗冲击性能越好，刚性越差，无定形二聚物的含量越高，产品的抗冲击性能越好，但刚性相对降低。