Vaporization and caloric studies on sodium niobate

Thermodynamic studies of a polycrystalline sodium niobate (NaNbO₃) under equilibrium conditions by the method of Knudsen effusion mass spectrometry (KEMS) were conducted in the temperature range 1250–1485 K. The vaporization of pure Na₂O(c) was investigated at temperatures of 900–1165 K. Thermodynamic quantities of sublimation enthalpy, activity, and entropy were derived from the partial pressures of gaseous Na, Na₂O, and O₂ over the sodium niobate and pure sodium oxide reference samples. The sublimation enthalpy of Na from NaNbO₃(c) at T=1370 K was ${\mathrm{\Delta }}_{\mathrm{sub}}{H}_{1370K}^0(\mathrm{Na})=465\pm 9\mathrm{kJ}{\mathrm{mol}}^{-1}$. Heat capacity measurements under constant pressure ($C_{\mathrm{p}\left(T\right)}^0$) by Dynamic Scanning Calorimetry (DSC) in the temperature range 298–1450 K resulted in six polynomial equations for each branch of the five transitions. Below the first phase transition at 639 K the $C_{\mathrm{p}\left(T\right)}^0$ values increased from 97 to 123 J mol⁻¹ K⁻¹. Beyond this transition and up to the third one at 792 K, $C_{\mathrm{p}\left(T\right)}^0$ gently inclined from about 120 to a maximum value of 123 J mol⁻¹ K⁻¹. Finally, beyond the fifth transition at 907 K it approximated to an almost constant value of 115 J mol⁻¹ K⁻¹. The enthalpy and the entropy values were calculated from the $C_{p\left(T\right)}^0$ polynomials and from the vaporization studies. The enthalpy of the five transitions in sodium niobate, ${\mathrm{\Delta }}_{\mathrm{trs}}{H}_{298}^0\left({\mathrm{NaNbO}}_3(\mathrm{c})\right)$ were measured by drop calorimetry. Deduced from empirical and experimental approaches, the heat of reaction for oxides was ${\mathrm{\Delta }}_{\mathrm{r}}{H}_{298}^0\left({\mathrm{NaNbO}}_3(\mathrm{c})\right)$=$-94.3\pm 7$ kJ mol⁻¹ and the heat of formation was ${\mathrm{\Delta }}_{\mathrm{f}}{H}_{298}^0\left({\mathrm{NaNbO}}_3\left(\mathrm{c}\right)\right)$=$-1250.8\pm 7$ kJ mol⁻¹. The thermodynamic activity of Na₂O in sodium niobate was temperature dependent, and its values varied from 2.6×10⁻³ to 8.3×10⁻⁴ in the range 1100–1250 K. NaNbO₃(c) has a long-term stability in the temperature range including the transition to cubic phase at 907 K.     

Review KEMS 2012 till 2017

Review on the main results on high temperature behavior of inorganic systems and materials obtained by the Knudsen effusion mass spectrometry (KEMS) during last five years is presented. The available information on vaporization processes and thermodynamic properties of these systems found recently is discussed with the indication of its great importance for the developing of advanced high temperature materials that may be used in the various fields of modern technologies such as space, nuclear and optical industries.     

In-situ formation of graphene–lead oxide composite and its use in trace arsenic detection

Reduced graphene oxide–lead dioxide composite is formed when EGO coated surface is electrochemically reduced along with lead ions in the solution. This composite has been shown to be an excellent material for low level detection of arsenic. Various functional groups present on EGO, in a wide pH range of 2–11, are responsible for the favorable interaction between metal ion and the modified electrode surface and subsequent trace level detection. X-ray photoelectron spectroscopy and Raman spectroscopic techniques confirm the formation of composite and its composition. Thin layer of lead dioxide along with reduced exfoliated graphene oxide has been shown to be responsible for the enhanced activity of the surface. The detection limit of arsenic is found to be 10 nM. This study opens up the possibility of using the composites for sensing applications and possibly simultaneous detection of arsenic and lead.     

空气氧化法制备氧化铁黄晶种的工艺条件研究

通过考察汽液固三相反应器内由Fe(OH)_2制备氧化铁黄晶种的工艺条件,对影响氧化铁黄晶种生成速率的因素进行了研究和探讨,并对实验数据进行拟合得出实验范围内各因素对平均反应速率影响的关系式。结果表明,常温下,在三相反应器内,增加空气流量、液相流量、原料液浓度及反应压力,降低Fe(OH)2胶体颗粒粒径,均有利于氧化铁黄晶种的生成。实验获得的拟合参数对今后氧化铁黄颜料工艺条件的优化和反应器的设计具有一定的指导意义。     

LaGaO_3基钙钛矿型固体电解质氧离子导电能力的QSPR研究

本文从文献中收集了多个钙钛矿结构的掺杂LaGaO_3系列氧离子导体电解质材料样本,以导电率的对数Ln(?)为目标,使用各种机器学习方法进行回归分析,包括多元线性回归(MLR)、偏最小二乘法(PLS)和支持向量回归(SVR),建立了Ln(?)与其分子结构参数之间的定量模型。结果表明:SVR方法所得导电率Ln(?)的留一法预报结果与实验最相符,计算值与实验值的相关系数为0.911。使用独立测试集预报的计算值和实验值的相关系数为0.880。此外还用建立的模型对La_(1-x)Sr_xGa_(1-y)Mg_yO_3掺杂体系的导电率进行了预报,根据预报结果做出的等高面图显示的优区与实验所得结果一致。     

Assessment of reconfiguration schemes for Reconfigurable Manufacturing Systems based on resources and lead time

Reconfigurable manufacturing equipment is developed to meet the growing demand for more agile production. Agile manufacturing technology can improve the turnover of a company if it enables fast market introduction for volume production. Modular reconfiguration, defined as changing the structure of the machine, enables larger variation of products on a single manufacturing system; these solutions are called Reconfigurable Manufacturing Systems (RMS). The quality of RMS, and the required resources to bring it to reliable production, is largely determined by a swift execution of the reconfiguration process. This paper proposes a method to compare alternatives for the ways to implement reconfiguration. Three classes of reconfiguration are defined to distinguish the impact of the proposed alternatives. The procedure uses a recently introduced index method for development of RMS process modules, based on the Axiomatic Design methodology. Weighting factors are used to calculate the resources and lead time needed to implement the reconfiguration process. Application of the method leads to quick comparison of alternatives in the early stage of development. Successful execution of the method was demonstrated for the manufacturing process of a 3D measuring probe.     

基于ICA的卵巢癌质谱数据分析

卵巢癌蛋白质谱数据属于高通量数据,含有大量冗余信息,且许多重要信息都包含在高阶信息中,而独立成分分析可以从高阶信息中提取有用特征。将传统的独立成分分析融入卵巢癌蛋白质谱数据的特征提取中,并利用类信息机制监督独立成分分析过程。仿真实验结果表明,独立成分分析和监督式独立成分分析在卵巢癌蛋白质谱数据集研究过程中取得了良好的效果,识别率可达98%。     

基于质谱测控系统的GPIB驱动程序开发

从目前国内质谱测控系统软件的使用情况出发,分析该系统软件的不足,基于面向对象的思想、WinDriver向导等,开发质谱测控系统下的Windows平台GPIB总线驱动,并设计与上层接口的动态链接库和类,解决了软件移植性和“更新换代”等方面的问题,为质谱测控系统和其他智能测控系统软件底层驱动的开发提供了一个很好的实例。     

镍镧复合氧化物的掺杂及其气敏性能研究

用共沉淀法制备了镍镧复合氧化物并对其进行三价、四价离子系列掺杂。研究了掺杂物的气敏性能。实验结果表明,SiO2,TiO2,SnO2,Al2O3,SbCl3等掺杂的复合氧化物,均对乙醇有较高的气敏性,而对汽油、H2及LPG等气敏性较低。其中TiO2掺杂量为4%(摩尔分数)的镍镧复合氧化物对乙醇的气敏性能最好。探讨了Si,Ti,Sn,Al,Sb等离子的价态,离子半径及复合氧化物的形成条件等与气敏性能的关系,研究了工作温度,被测气体浓度对元件气敏性能及对气体选择性的影响。     

基于Hadoop的海量数据存储平台设计与开发

随着北部湾海洋生态资源的开发和利用,海量海洋科学数据飞速涌现出来,利用海量数据存储平台合理管理和存储这些科学数据显得极为重要.这里提出了一种基于分布式计算技术进行管理和存储海量海洋科学数据方法,构建了海量海洋科学数据存储平台解决方案,采用Linux集群技术,设计开发一个基于Hadoop的海量数据存储平台.系统由五大模块组成,有系统管理模块、并行加载存储模块、并行查询模块、数据字典模块、备份恢复模块,能够实现存储海量海洋科学数据.系统模块实现结果表明,该系统安全可靠、易维护、具有良好的可扩展性.     

基于氧化石墨烯和不规则金纳米颗粒的吗啡传感器的研制

该文按照Hummers方法制备出氧化石墨,然后在水中进行超声,剥离出氧化石墨烯.利用氧化石墨烯、不规则的金纳米颗粒和壳聚糖修饰玻碳电极制成电化学传感器,并将其用于海洛因代谢物吗啡的直接电化学测定.考察了pH、工作电位等条件对传感器测定吗啡的影响.结果表明在电位为0.70 V条件下该传感器检测吗啡的线性范围为1.0×10...     

基于氧化石墨烯/聚吡咯-铟锡氧化物微电极的细胞阻抗生物传感器构建及细胞粘附增殖行为检测

构建一种基于氧化石墨烯/聚吡咯-铟锡氧化物GO/PPy-ITO（Graphene Oxide/Polypyrrole-Indium Tin Oxide）微电极的细胞阻抗生物传感器并用于细胞粘附增殖行为学检测。ITO微电极采用光刻技术对感光干膜绝缘层蚀刻而成,通过一步法电聚合技术在ITO微电极表面沉积GO/PPy纳米复合膜制备GO/PPy-ITO微电极;形状测量激光显微镜和扫描电子显微镜分别对GO/PPy表面粗糙度和拓扑形貌进行表征;电化学循环伏安法及阻抗谱表征GO/PPy-ITO微电极的电化学性质;人肺癌细胞株A549粘附、铺展和增殖实验考察GO/PPy界面的生物相容性;以GO/PPy-ITO微电极作为传感电极,利用电化学阻抗谱技术对A549细胞的粘附增殖行为进行检测。结果显示,ITO微电极表面上电沉积的GO/PPy纳米复合物表面平整,分布大量的微孔结构;电化————————————学实验结果显示GO/PPy-ITO微电极比裸ITO微电极具有更低的阻抗特征和更高的电化学活性;GO/PPy比纯PPy膜更能促进A549细胞粘附、铺展和增殖;GO/PPy-ITO微电极表面A549细胞的粘附增殖行为改变电极系统的阻抗谱特征,通过对阻抗谱数据进行等效电路拟合分析获得细胞粘附增殖行为学信息。本文发展的GO/PPy-ITO微电极兼具优良的电化学性质和细胞生物相容性,基于该电极系统构建的细胞阻抗生物传感器可用于细胞病理生理学行为、药物筛选等研究领域。     

Characterization of aluminium nitride and aluminium oxide thin films sputter-deposited on organic substrates

In microsystems technology, passivation layers are generally required to protect micro devices and functional elements against environmental impact, particularly against corrosion, thus increasing reliability and lifetime to acceptable values. In this work, the use of sputter-deposited aluminium oxide and aluminium nitride thin films on flexible polyimide foils was investigated, aiming at the protection of flow sensitive elements. Due to a high defect density located at the interface between the passivation layer and the organic substrate, the adhesion of pure aluminium oxide thin films was found to be poor when applying a combination of mechanical stress (e.g. bombardment with water droplets) and thermal cycling as an accelerated ageing procedure. A bi-layer consisting of aluminium nitride and aluminium oxide, however, shows a defect-free interface to the organic substrate resulting in an enhanced adhesion. In addition, no structural failure can be detected after applying the aging procedure, making this bi-layer approach well suited for the targeted application.     

Gold nanoparticle film grown on quartz fiber and its application as a microsensor of nitric oxide

A simple electroless plating method for growing a gold nanoparticle (GNP) film on a quartz fiber by chemical liquid deposition was reported. The gold film coated quartz fiber possessed good conductivity and mechanical property, and can be used as a novel gold fiber microelectrode (GFME). Being electropolymerized with niacinamide (NA) and further coated by Nafion for GFME, a disposable nitric oxide (NO) electrochemical microsensor was fabricated. This microsensor exhibited high sensitivity based on the catalytic effect of GNPs and polyniacinamide (PNA) toward the oxidation of NO. A good linear relationship between the amperometric response of the microsensor and the concentration of NO in the range of 7.2 × 10⁻⁹–1.8 × 10⁻⁵ mol L⁻¹ was achieved, along with a low detection limit of 3.6 nmol L⁻¹ (S/N = 3). In vivo detection of NO release from mice liver indicated that this microsensor had a promising application in the field of biomedical analysis.     

High-performance liquefied petroleum gas sensing based on nanostructures of zinc oxide and zinc stannate

Toxic and combustible gas detection plays a major role in environmental air quality monitoring. Real-time monitoring of hazardous gases and signal of accidental leakages is of great importance owing to the concern for safety requirements in industries and household applications. A simple and economical method for the fabrication of highly sensitive zinc oxide (ZnO) nanorods based gas sensors for detecting low concentrations of Liquefied Petroleum Gas (LPG) was studied in this work. Platinum (Pt) nanoparticles were deposited on the sensing medium which acts as catalysts to improve the sensor performance. The change in electrical resistance of the metal oxide semiconductor for varying concentrations of LPG was measured. Maximum response of 59% was achieved for 9000 ppm LPG at 250 °C. Further to improve the sensing performance of the sensor towards LPG, surface modification of ZnO nanorods using zinc stannate (Zn₂SnO₄) microcubes was performed. High response of 63% was observed for 3000 ppm LPG at 250 °C. Significant improvement in response of the sensor with Zn₂SnO₄ microcubes on ZnO nanorods was observed when compared to sensor with ZnO nanorods.     

云计算环境下并行分布式数据挖掘平台研究

网络技术在带给人们大量信息的同时,也极大地增加了人们从海量数据中发现有用知识的难度,而解决这一问题的努力促进了数据挖掘技术的出现和快速发展。云计算是能够提供动态资源池、虚拟化和高可用性的计算平台,云计算开发平台可被用来开发高性能应用程序。研究云计算环境下并行分布式数据挖掘平台的3个层次,依下而上为分布式计算层,知识发现平台层以及用户应用层。