Synthesis and structure of the tetradeca-iron(III) oxide–alkoxide cluster [Bu4N]2[Fe14O8(OCH2CH3)20Cl8]

The iron(III) oxide–alkoxide cluster, di-tetra-n-butylammonium octachloro-tetra(μ₃-oxo)-tetra(μ₄-oxo)- icosa(μ₂-ethoxo)-tetradeca-iron(III), has been isolated and its X-ray crystal structure determined.     

含手性膦配体MBPA和邻巯基吡啶配体PyS的过渡金属钯(Ⅱ)化合物的2D NMR研究

利用一维和二维NMR技术,对含手性膦配体MBPA和邻巯基吡啶配体PyS的过渡金属Pd(Ⅱ)化合物Pd(3-MBPA)(PyS)Cl)(1),Pd(2-MBPA)(PyS)Cl)(2)。进行~1H和~(13)C NMR谱分析,归属了所有的~1H和~(13)CNMR谱线,并对配体在配位前后的化学位移的变化作了简单讨论。     

New Hydrolytic Process for Producing Zirconium Dioxide, Tin Dioxide, and Titanium Dioxide Nanoparticles

Nanocrystalline ZrO₂, SnO₂, and TiO₂ were synthesized through a simple hydrolytic process based on the etherification of alcohols. The obtained products had good uniformity and were less aggregated than in other synthesis techniques. The synthesis of ZrO₂ and SnO₂ in this process was dependent mainly on the reaction temperature, whereas the morphologies of TiO₂ exhibited a dependence on the alcohols used.     

Physical chemistry of flavour

The sensation of flavour occurs when certain flavour-active molecules are released from food and are transported to stimulate sensors in the mouth and nose. The human brain integrates all the signals from the sensors and produces an overall flavour perception. The way in which flavour molecules are released from food during eating, and the manner in which they are retained during processing and storage, are all governed by various aspects of physical chemistry. This review describes some of the basic principles of partition, a key parameter in the physical chemistry of flavour. An overview of the theory and measurement of partition is given, along with some applications to model and real food systems.     

Defect and Mixed Conductivity in Nanocrystalline Doped Cerium Oxide

The results obtained from a study on the microstructure and the electrical properties of Gd-doped CeO₂ thin films were reported. Dense, nanocrystalline films on sapphire substrates are prepared using a polymeric precursor spin coating technique. The electrical conductivity was studied as a function of temperature and oxygen activity and correlated with the grain size. For nanocrystalline Gd-doped CeO₂ thin films, the ionic conductivity increased with decreasing activation energy as the grain size decreased. A conductivity model was developed to analyze P _O2 behavior of the electrical conductivity. Using the conductivity model, the hopping energy of electron conduction and the enthalpy of oxygen vacancy formation were determined for different microstructures.     

Reliability of III–V based heterojunction bipolar transistors

This paper reviews the reliability of III-V based heterojunction bipolar transistors (HBTs). These devices have many potential advantages over other solid-state microwave devices. However, because of the tradeoff between performance and reliability, they are not being used to any great extent in power microwave applications. In the type of III-V HBT device most fully developed, the AlGaAs/GaAs HBT, leakage currents play a major role in the dominant mode of degradation. Because low-frequency noise is related to these leakage currents it has been used extensively in the analysis of the performance and reliability limitations of these devices. The reliability of other types of III-V HBT devices, such as InGaP/GaAs and InP based devices, is also discussed.     

Effect of filtration on virgin olive oil stability during storage

The effect of filtration and dehydration on the stability and quality of virgin olive oil during storage at room temperature (25 °C) and under accelerated conditions (40 °C) was studied. Different types of monovarietal olive oil, namely unfiltered (UF), filtered (F) and filtered‐dehydrated (FD), were obtained from Arbequina, Colombaia, Cornicabra, Picual and Taggiasca cultivars. Results showed that filtration and dehydration decreased the rate of hydrolysis of the triacylglycerol matrix, especially at the higher temperature and in oils with a higher initial free acidity (e.g. free acidity of 0.82% and 0.63% in UF and FD Colombaia samples, respectively, after 8 months of storage), and delayed the appearance of rancid defects (e.g. UF and FD Arbequina samples lost extra‐virgin grade after 10 and 12 months of storage, respectively). The formation of simple phenols due to the hydrolysis rate of their secoiridoid derivatives was also greater in unfiltered olive oils (e.g. 174 μmol/kg and 137 μmol/kg in UF and FD Picual samples, respectively, after 8 months of storage). Thus, filtration and especially dehydration could help to prolong the shelf life of high‐quality and less stable olive oils like those obtained from the Arbequina and Colombaia varieties.     

渣油脱除金属杂质工艺研究

介绍了一种用酯类化合物脱除渣油中金属杂质的工艺及其工业试验情况 ,重点探讨了油水分离条件、药剂量和反应温度对脱除效果的影响。工业试验结果表明 ,使用该工艺可以脱除渣油中的大部分金属元素 ,尤其是较难脱除的镍、钒总脱除率达 70 %以上 ,钙、镁、铁总脱除率达 80 %以上。     

稀土—铁—氮化合物Sm2（FeM）Nx永磁材料

采用机械破碎与氢破碎和氮化处理方法制得了Sm_2Fe_(17)N_x化合物粉末和粉末压结体,研究了金属钐含量。过渡族元素(M=Co、Cr、V、Zr)部分取代铁对粉末压结体磁性能的影响和Sm_2Fe_(17)N_x化合物的稳定性。结果表明,铬能显著提高粉末的矫顽力,而钒能够改善退磁曲线方形度。低于600℃Sin_2(Fe_(1-y) M_y _(17)N_x粉末在真空、氩气、氮气中是稳定的;高于600℃Sm_2Fe_(17)N_x化合物将发生分解。