In-situ observations of phase transformations in titanium

An in-situ laser-scanning confocal microscopy study has been undertaken on the phase transformations in highpurity titanium. Observations of the β-Ti to α-Ti were observed to proceed with a pronounced Widmanstätten plate morphology due to the large β-Ti grain size. An anomalous transformation was also observed, with the α-Ti growing with a defined ledge-like surface relief. The observed transformation morphologies are discussed with reference to the crystallography of the regions, analyzed using electron-backscatter diffraction.     

阿斯巴甜衍生物甜味剂的合成研究

在成功合成纽甜的基础上,以肉桂醛与阿斯巴甜为原料制备了3-苯基丙烷衍生物为取代基的阿斯巴甜衍生物甜味剂的模拟化合物,并且依据此合成工艺,以4-甲氧基肉桂醛和阿斯巴甜为原料,制得甜度与纽甜相当的3-(4-甲氧基苯基)-丙基阿斯巴甜,产率为66.0%。此合成工艺简单、产率高,对研究3-苯基丙烷衍生物为取代基的阿斯巴甜衍生物甜味剂的合成具有积极的意义。     

Yttrium doping of Ba0.5Sr0.5Co0.8Fe0.2O3-δ part II: Influence on oxygen transport and phase stability

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) in its cubic perovskite phase has attracted much interest for potential use as oxygen transport membrane (OTM) due to its very high oxygen permeability at high temperatures. However, performance degradation due to a sluggish phase decomposition occurs when BSCF is operated below 840?°C. Partial B-site substitution of the transition metal cations in BSCF by larger and redox-stable cations has emerged as a potential strategy to improve the structural stability of cubic BSCF. In this study, the influence of yttrium doping (0…10?mol-%) on oxygen transport properties and stability of the cubic BSCF phase is assessed by in situ electrical conductivity relaxation (ECR) and electrical conductivity measurements during long-term thermal annealing both at 700?°C and 800?°C. Detailed phase analysis is performed by scanning electron microscopy (SEM) after long-term annealing of the samples in air at different temperatures.     

Enzymatic Synthesis of l‐Ascorbyl Fatty Acid Esters Under Ultrasonic Irradiation and Comparison of Their Antioxidant Activity and Stability

A series of novel l ‐ascorbyl fatty acid esters were synthesized by catalization of Novozym^® 435 under ultrasonic irradiation and characterized by infrared spectroscopy, electrospray ionization mass spectra, and nuclear magnetic resonance. Their properties especially antioxidant activity and stability were investigated. The results showed that the reducing power, the scavenging activity of hydroxyl radical and 2,2‐diphenyl‐1‐picrylhydrazyl radical were decreased with the increase of the number of carbon atoms in fatty acid. The hydroxyl radical scavenging activity and reducing power of l ‐ascorbyl saturated fatty acid esters were better than that of tert‐butylhydroquinone. The induction period in lipid oxidation of l ‐ascorbyl saturated fatty acid esters and tert‐butylhydroquinone were longer than that of l ‐ascorbyl unsaturated fatty acid esters and l ‐ascorbic acid both in soybean oil and lard. Besides, the l ‐ascorbyl fatty acid esters showed different stabilities in different conditions by comparing with l ‐ascorbic acid, and the l ‐ascorbyl saturated fatty acid esters were more stable than l ‐ascorbyl unsaturated fatty acid esters in ethanol solution.     

In Situ Characterization of Lattice Structure Evolution during Phase Transformation of Zr‐2.5Nb

The α–β phase transformation behavior of Zr‐2.5Nb (in mass%) has been characterized in real time during an in situ neutron diffraction experiment. The Zr‐2.5Nb material in the current study consists, at room temperature, of α‐Zr phase (hcp) and two β phases (bcc), a Nb rich β‐Nb phase and retained, Zr rich, β‐Zr(Nb) phase. It is suggested that this is related to a quench off the equilibrium solubility of Nb atoms in the Zr bcc unit cells. Vegard's law combined with thermal expansion is applied to calculate the composition of the β‐phase, which is compared with the phase diagram, revealing the system's kinetic behavior for approaching equilibrium.     

Current developments at ISES

The International Solar Energy Society has been experiencing an extraordinary period of change of late, in this article, Rian Van Staden, new Executive Director of ISES highlights current developments and initiatives at the organisation.     

尼泊金十二酯合成工艺研究

对羟基苯甲酸与正十二醇在对甲苯磺酸催化下,以苯为溶剂,直接酯化合成尼泊金十二酯,其最佳的反应条件为:对羟基苯甲酸与正十二醇摩尔比1∶3,反应时间为4h,反应温度为130～140℃,催化剂与对羟基苯甲酸的摩尔比为0.07∶1,产率90.1%。     

规则螺旋碳纳米管的制备及其结构的研究

以钛片为催化剂，通过乙炔气体在７５０℃下热解制备了规则螺旋的碳管，这些规则的螺旋碳管直径约为２００ｎｍ，规则螺旋碳管的形成与钛片的预处理有关，在盐酸处理过的钛片表面上所生长的碳管几乎都是规则螺旋形状的。