钴盐沉淀—热分解法制备超细八面体四氧化三钴

提出了一种以硫酸钴、碳酸氢铵为原料,聚乙二醇为表面分散剂,采用钴盐沉淀—热分解法制备超细八面体Co3O4的方法。通过热重-差热分析仪、红外光谱分析仪、X射线衍射仪、场发射扫描电镜、激光粒度分析仪对前驱体碱式碳酸钴和产品Co3O4进行了分析和表征。结果表明:制备的Co3O4粉末呈八面体晶体形貌,粒度在亚微米至微米级,粒度分布均匀且范围窄,制备过程分散剂的添加消除了粉末的团聚现象。     

微波-超声波联合辅助下活性氧化锌的制备与表征

以NH3-NH4HCO3-H2O体系中所得锌氨溶液为原料,在微波与超声波辅助及常规加热下运用蒸氨法制备活性氧化锌前驱体,考察了锌溶液浓度和蒸发温度对前驱体粒度的影响,对前驱体表征结果表明：采用微波-超声波联合辐射法制备出产物的粒度和形貌更易于控制,对制备出活性氧化锌粉体进行了SEM、X衍射及纯度分析表征,结果表明微波及超声波的加入有利于获得均匀分散、平均粒径为2.3μm,纯度可达98%以上的活性氧化锌产品.     

电池级Co3O4的制备

研究了用碳铵直接沉淀氯化钴制备前躯体进而煅烧制备电池级Co3O4的工艺.主要考察了氯化钴溶液中钴离子浓度、溶液起始pH值、沉淀反应温度、沉淀反应时间等对前躯体粒度分布的影响,以及前躯体煅烧温度、煅烧时间对产物Co3O4颗粒形貌、粒度的影响.XRD研究表明,用该方法制备的前驱体粉末为无定形的碱式碳酸钴,经过煅烧后生成均匀分散的Co3O4粉末.XRD、SEM、粒度分布、振实密度等测试对煅烧产物进行了性能表证,结果显示产物具有标准Co3O4晶型结构,结晶良好,粉末具有规整的颗粒形貌,并且具有较好的分散性,平均粒径l～5 μm,振实密度2.1 g·cm-3,满足电池级Co3O4的要求.     

碳酸氢铵沉淀法制备超细Y_2O_3反应条件对粒度的影响

用共沉淀法制备超细Y2O3,研究了料液浓度、复合分散剂和体系反应温度对粒度的影响。在硝酸钇溶液中,加入PVA和SDBS分散剂,以NH4HCO3为沉淀剂,得到碳酸钇前驱体,过滤,120℃干燥,在700℃灼烧3h,制备出了分散性好、平均体积粒径为97.5nm的超细Y2O3粉体;得到了在硝酸体系中制备超细Y2O3的最佳工艺条件:硝酸钇的浓度为0.3mol/L,复合分散剂加入量3%,体系反应温度50℃~60℃。     

沉淀法制备微米四氧化三钴试验研究

研究了以氯化钴为钴源,采用碳酸钠、氢氧化钠、碳酸氢铵沉淀体系制备Co_3O_4。以碳酸氢铵为沉淀剂制备前驱体,煅烧后制得四氧化三钴。结果表明,物质的量比是影响前驱体物相的主要因素:碳酸氢铵与氯化钴物质的量比≤3∶1时,前驱体为碱式碳酸钴(Co(CO_3)_(0.5)(OH)·0.11H_2O);碳酸氢铵与氯化钴物质的量比为4.5∶1时,前驱体为碳酸钴(CoCO_3)和复合碱式碳酸钴((NH_4)_2Co_8(CO_3)_6(OH)_6·4H_2O)的混合物。采用该体系,在物质的量比4.5∶1,氯化钴质量浓度13 g/L、反应温度60℃、反应时间10 h条件下,所得Co_3O_4粉体粒度分布均匀且范围窄,D_(50)为9.08μm,形貌为类球形。     

水热法制备片状花簇Co_3O_4微纳结构超疏水表面及其性能

采用水热法在铝片基底表面成功制备了片状花簇Co3O4超疏水表面,利用X射线衍射和扫描电镜研究了前驱体及终端产物的成分结构和表面微观形貌;探讨了水热反应时间对Co3O4表面微观形貌结构的影响,详细分析了微观结构随反应时间的演变过程;结合Cassi-Baxter复合模型分析了Co3O4超疏水表面的润滑性能;利用强压水柱对Co3O4超疏水表面进行了抗冲击稳定性试验。结果表明,反应时间为10h时得到的片状花簇Co3O4超疏水表面的性能最佳,并具有良好的抗水冲击性能。     

工艺条件对溶液雾化氧化法制备Co_3O_4粉末的影响

以CoCl2·6H2O为原料,采用溶液雾化氧化法制备Co3O4粉末,对反应温度、溶液浓度、载气压力等工艺条件对产物粒子形貌及粒度分布的影响进行系统研究.结果表明,反应温度对Co3O4粉末的形貌和粒度都有影响,高温下粉末粒度较小,球形度较好,但温度过高会导致粒子团聚;COCl2·6H2O溶液的浓度对Co3O4粉末粒度也有影响,高浓度下所得Co3O4粉末的粒径较大;雾化压力增大,有利于得到颗粒分布均匀、分散性好的Co3O4粉末,但粉末粒度随之增大.在反应温度为850℃、CoCl2·6H2O溶液浓度为1.5 mol/L、雾化压力为1.5×10 5Pa的条件下,反应较完全,可制备物相单一的Co3O4粉末,产物为均匀分布的球形粉末,且粒度分布较窄.     

NaF掺杂的Ca3Co4O9粉体制备及其热电性能研究

本文以CaCO3、NaF、Co(NO3)2.6H2O、HNO3为原料,去离子水为溶剂,柠檬酸为螯合剂,采用自蔓延法制备了NaF掺杂的Ca3Co4O9(Ca3-xNaxCo4O9-xFx)(x=0,0.05,0.1,0.15,0.2,0.25)粉体。粉末的XRD表明图谱中主要衍射峰是Ca3Co4O9的特征峰,有极小部分CaF2存在。粉体的粒度分布在1～100μm之间,平均粒径为11.276μm。烧结试样的SEM显示NaF的掺杂能促进烧结。在温度473～973K下,烧结体热电性能的测试结果显示,随NaF掺杂量的增加,电导率和Seebeck系数先升高后降低。加入20%NaF的Ca3Co4O9烧结体在973K时seebeck系数和功率因子达到最大值,分别为220μV/K和4.39×10-4 W/mK2。     

草酸盐共沉淀前驱体的热分解过程

研究前驱体热分解过程对制定Ni-Co预合金粉末的制备工艺有一定的指导意义,故采用差热和热重分析法对草酸盐共沉淀前驱体(Ni0.7Co0.3C2O4·2H2O)在氩气和空气中的热分解过程进行研究,并对分解产物进行了物相分析和形貌观察.结果表明: 前驱体在这2种气氛下的热分解机制完全相同; 分解过程分2步进行,第1步脱去结晶水分子(Ni0.7Co0.3C2O4·2H2ONi0.7Co0.3C2O4 2H2O↑),第2步无水前驱体分解成Ni-Co合金粉末和CO2; 但是,最终的固体产物不同,因为在空气中,生成的Ni-Co合金粉末又与氧气反应,最终得到的固体产物是氧化物(NiO和Co3O4),而在氩气中,最终的固体产物仍然是Ni-Co合金粉末.     

共沉淀法制备Fe33Ni15Co2合金前驱体的热力学分析

分析了制备铁镍钴合金前驱体的Fe-Co-Ni-NH3-C2O2-4-H2O体系的热力学,计算了溶液体系中Fe(Ⅱ),Ni(Ⅱ),Co(Ⅱ)的浓度与pH的关系,确定了3种金属离子完全共沉淀的最佳pH为2.0.     

The pulmonary surfactant system: physiology, pathologies associated with its alteration and exogenous administration as therapeutic and diagnostic agent]

Pulmonary surfactant is a lipoproteic mixture synthesized and secreted by alveolar type II cells. Its principal property is to reduce the surface tension by lining on the alveolar surface. Surfactant deficiency is the major factor responsible for the respiratory distress syndrome of the newborn (RDS) and the adult respiratory distress syndrome (ARDS). Since 1980, the exogenous administration of surfactant for the treatment of these syndromes is being studied. In this work the exogenous surfactant preparations, the delivery techniques and the dosing schedule is discussed. The utilization of the exogenous natural surfactant (ENS) as precursor of a radiopharmaceutical labeled with 99mTc (99mTc-ENS) for aerial lung scintigraphy is also discussed.     

表面活性剂强化铜矿石浸出

为了解决铜矿石浸出速度慢、浸出率低的问题,在浸出液中加入表面活性剂进行摇瓶试验.通过测量浸出前后溶液表面张力以及铜浸出率,考察了三种不同类型的表面活性剂对铜矿石浸出的影响.研究发现溶液表面张力对矿石浸出影响较大,阴离子表面活性剂的强化浸出作用最为明显,铜浸出率达62.5%.在柱浸试验中,添加阴离子表面活性剂使铜浸出率提高了近10%.利用物理化学和渗流力学对表面活性剂强化浸出机理的分析表明,溶液表面张力和表面活性剂在矿石表面的吸附对矿石表面润湿作用影响较大,表面活性剂在浸出液的持久性也是影响浸出的因素之一.      

非离子型表面活性剂对风化壳淋积型稀土矿浸出过程的影响

为了缓解风化壳淋积型稀土矿浸取过程存在的浸取周期长、浸出剂用量大和稀土拖尾等问题,以非离子型表面活性剂为助浸剂,氯化镁为浸出剂,对稀土浸出过程进行研究,研究复配浸出剂溶液性质,分析浸矿前后矿物粒径分布,探讨表面活性剂的促渗机理。研究结果显示,加入表面活性剂后,稀土浸出率提高,渗透速度加快,溶液的表面张力和接触角均减小,黏度增大,矿物颗粒的中值粒径明显减小,矿物表面Zeta电位增大,其中加入吐温40后稀土浸出率提高至86.38%,表面张力减小19.00%,接触角减小53.19%,溶液黏度减小4.29%,溶液性质变化最大。加入表面活性剂后可使溶液更容易润湿矿物,进入孔隙的阻力变小,扩散层厚度减小,黏土矿物的膨胀受到抑制,使得溶液浸出稀土的效果更好,其中吐温40对溶液浸出稀土的渗流效果影响最大,助渗效果最好。     

Analytical and Numerical Modeling Assessment of Capillary Barrier Performance Degradation due to Contaminant-Induced Surface Tension Reduction

Analytical and numerical models of capillary barrier performance commonly use hydraulic characteristics measured using pure water. However, the potential exists for an infiltrating solution to have a surface tension lower than that of pure water due to the presence of surface-active contaminants (surfactants). A lower surface tension solution may impact capillary barrier performance due to the dependence of capillarity on surface tension. An existing analytical solution for capillary diversion length (L) was modified to include the effect of surface tension reduction on steady-state capillary barrier performance during uniform and constant infiltration. The L for a surfactant-contaminated system was found to be less than for a pure water system and equal to L for a pure water system multiplied by the relative surface tension. Numerical modeling using HYDRUS-2D also showed that diversion was less in the surfactant-contaminated system and that the difference in the performance of the two systems was due to the fact that the fine layer in the capillary barrier retains less liquid when wetted with surfactant solution.     

溶胶-凝胶法制备95多品氧化铝纤维

以结晶氯化铝、铝粉和硅溶胶为主要原料,用溶胶-凝胶法制备95多晶氧化铝纤维.研究了PEG的加入量和胶体黏度对纤维平均直径和单丝拉伸强度的影响,并对不同温度烧成的纤维单丝拉伸强度和比表面积进行了对比.结果表明:当PEG加入质量分数为4%、胶体黏度为30 Pa·s时,纤维平均直径为3.7 μm,且拥有较好的强度;纤维的比表...     

Preparation of nanoscaled yttrium oxide by citrate precipitation method

The nano-Y_2O_3 was prepared from YCl_3 by the citrate precipitation method. The precursor powders were prepared by 0.1 mol/L YCl_3 solution and 0.1 mol/L hydrochloric acid in the presence of 1% surfactant PEG2000, which was dried via an ethanol azeotropic distillation method. The effects of reaction temperature, precursor concentration, hydrochloric acid concentration, surfactant, and calcination temperature on the mean sizes of nano-Y_2O_3 were studied. It was found that the highest yield of precursor was about 70% at the p H value of 5.0, and the yield decreased rapidly at the p H value below 4 or over 6. The reaction temperature revealed no effect on the size of precursor. The optimized precursor concentration and hydrochloric acid concentration were both 0.1 mol/L. Several typical analytic techniques such as particle size analyzer, X-ray diffraction(XRD), thermogravimetric and differential thermal analyses(TG-DTA) and scanning electron microscopy(SEM) were used to determine the characteristics of the prepared nano powders. Homogeneous torispherical nano-Y_2O_3 with the smallest size(20 nm) could be obtained by calcining the precursor powders at 800 oC for an hour.     

The role of lipids in pulmonary surfactant

Pulmonary surfactant is composed of approx. 90% lipids and 10% protein. This review article focusses on the lipid components of surfactant. The first sections will describe the lipid composition of mammalian surfactant and the techniques that have been utilized to study the involvement of these lipids in reducing the surface tension at an air-liquid interface, the main function of pulmonary surfactant. Subsequently, the roles of specific lipids in surfactant will be discussed. For the two main surfactant phospholipids, phosphatidylcholine and phosphatidylglycerol, specific contributions to the overall surface tension reducing properties of surfactant have been indicated. In contrast, the role of the minor phospholipid components and the neutral lipid fraction of surfactant is less clear and requires further study. Recent technical advances, such as fluorescent microscopic techniques, hold great potential for expanding our knowledge of how surfactant lipids, including some of the minor components, function. Interesting information regarding surfactant lipids has also been obtained in studies evaluating the surfactant system in non-mammalian species. In certain non-mammalian species (and at least one marsupial), surfactant lipid composition, most notably disaturated phosphatidylcholine and cholesterol, changes drastically under different conditions such as an alteration in body temperature. The impact of these changes on surfactant function provide insight into the function of these lipids, not only in non-mammalian lungs but also in the surfactant from mammalian species.     

气相异辛醇影响溴化锂溶液传质特性研究

通过溴化锂溶液传质性能测试装置,研究了气相异辛醇添加量对溴化锂溶液表面张力的影响,以及在降膜吸收的过程中气相异辛醇的添加量和溶液的流量对传质系数的影响。结果表明：气相异辛醇的添加对溴化锂溶液的表面张力和传质系数均有明显影响,表面张力随异辛醇添加量的增加而减小,传质系数的变化规律与其相反。气相异辛醇分子在溶液表面的吸附作用降低了溶液表面张力梯度,从而引起的Marangoni效应,是对流传质强化比增大的重要原因。     

Dynamic surface tension of surfactant TA: experiments and theory

A bubble surfactometer was used to measure the surface tension of an aqueous suspension of surfactant TA as a function of bubble area over a range of cycling rates and surfactant bulk concentrations. Results of the surface tension-interfacial area loops exhibited a rich variety of phenomena, the character of which varied systematically with frequency and bulk concentration. A model was developed to interpret and explain these data and for use in describing the dynamics of surface layers under more general circumstances. Surfactant was modeled as a single component with surface tension taken to depend on only the interfacial surfactant concentration. Two distinct mechanisms were considered for the exchange of surfactant between the bulk phase and interface. The first is described by a simple kinetic relationship for adsorption and desorption that pertains only when the interfacial concentration is below its maximum equilibrium value. The second mechanism is "squeeze-out" by which surfactant molecules are expelled from an interface compressed past a maximum packing state. The model provided good agreement with experimental measurements for cycling rates from 1 to 100 cycles/min and for bulk concentrations between 0.0073 and 7.3 mg/ml.     

Pulmonary lung surfactant synthetic peptide concentration-dependent modulation of DPPC and POPG acyl chain order in a DPPC:POPG:palmitic acid lipid mixture

Lung surfactant-associated protein interaction with lipid matrices and the effects on lipid thermotropic phase behavior are areas of active research. Many studies limit the lipids to a single or two-component system. The current investigation utilizes a three-lipid component matrix (DPPC:POPG:palmitic acid) to investigate the impact of a synthetic surfactant protein B fragment (SP-B 53-78 DiACM) on the dynamic surface activity of the lipid admixture as measured by a Wilhelmy surface balance. Also, the modulation of the individual lipid acyl chain order by the peptide within the lipid matrix is studied through the use of thermal perturbation FTIR spectroscopy. The data clearly demonstrate a concentration-dependent effect of the peptide on the surface activity with an improvement in the dynamic surface tension diagram characteristics (decreased surface tension and increased collapse plateau) especially at low, 0.36 M%, peptide concentrations. These effects are diminished upon further addition of the peptide. FTIR spectral data demonstrate that the peptide addition results in a significant increase in the acyl chain order of the DPPC and POPG components as measured by the position of the methylene stretching vibrational bands. DPPC is most sensitive to the peptide presence, while the palmitic acid is least affected. The transition temperatures of the individual lipids are also increased with the addition of the peptide. The presence of POPG in the matrix achieves the surface activity similarly seen with natural lung surfactant relative to a DPPC/palmitic acid lipid matrix alone. Its presence increases the sensitivity of the DPPC acyl chains to the presence of the peptide. These effects on the chain order are most probably related to the increased acyl chain fluidity which POPG imparts to the lipid matrix because of the presence of the cis double bond. The phosphatidylglycerol headgroup also adds a negative charge to the lipid matrix which enhances the peptide-lipid interaction. Although the palmitic acid is minimally affected by the peptide, its presence, as suggested by surface balance measurements, results in the establishment of a stable lipid film with DPPC, capable of achieving low surface tension values.