Substitution Process and Valent State of Samarium Ion in Perovskite Binary Fluorides

The lattice sites occupied by samarmm ions in KMgF_3 were ascertained The relationship be-tween valent state of samarium ion in hosts and substituted lattice sites was mvestigated using fluorescentspectra.It is found that the valent state of samarium in different cationic lattice sites is different The internalrelation between the valent state of samarium ion and occupied lattice site was discussed     

ENZYMATIC PROCESSING OF CRUDE XYLOOLIGOMER SOLUTIONS OBTAINED BY AUTOHYDROLYSIS OF EUCALYPTUS WOOD

Liquors from the aqueous processing of Eucalyptus wood, containing soluble xylan-degradation products (mainly substituted xylooligomers) were subjected to the action of commercial enzyme complexes (Celluclast, Bioxilanasa-AXC, Econase^R HC 400, Cellulase T 4 and Hemicellulase 90) containing endo-xylanase, xylobiase and acetyl-xylan-esterase activities to assess their suitability to obtain either xylose-containing solutions (useful as fermentation media) or low-DP xylooligosaccharides (useful as food additives). Under selected conditions, the Celluclast, Bioxilanasa-AXC, Econase^R HC 400 and Cellulase T 4 complexes were able to convert into xylose up to 90% of the substituted xylooligosaccharides present in the autohydrolysis liquors. The enzyme Hemicellulase 90 allowed the conversion of up to 67% of the initial substituted xylooligosaccharides into low-DP oligosaccharides. The most remarkable finding was that a significant concentration of DP2 oligomers (that could be incorporated into functional foods as prebiotic ingredients) was achieved at a short reaction time.     

改性聚苯胺膜的气体分离性能及应用

论述了改性聚苯胺膜的气体透过性能。提出环取代聚苯胺膜由于自由体积增加而具有较大的透气系数。聚苯胺与聚酰亚胺预聚体的共混膜显示了比聚酰亚胺膜和聚苯胺膜更大的渗透系数，而分离系数介于二者之间。苯胺共聚物与乙基纤维素共混膜应用于空气分离，能将空气中氧体积分数从21％提高到46％，且具有中等的富氧空气流量和很好的稳定性，在医疗保健等领域具有很大的应用潜力。     

Defined vanadium phosphorus oxides and their use as highly effective catalysts in ammoxidation of methyl aromatics

The heterogeneous catalytic ammoxidation of methyl aromatics and methyl hetero aromatics is a preferred method for the synthesis of aromatic and hetero aromatic nitriles. The resulting nitriles are valuable intermediates for the production of dyestuffs, pesticides, pharmaceuticals and other chemical products. Usually, the ammoxidation is carried out using V-containing oxides (e.g. V/Ti, V/Sn, V/Mo) promoted by further transition metals as catalysts. However, we have shown recently that defined vanadium phosphates (VPO) revealed an excellent ammoxidation performance. The ammoxidation of toluene was used as model reaction. An intense characterisation of some VPO catalysts under pre-treatment and working conditions by the use of various in situ-methods has thrown more light in formation and stability of the used VPO solids as well as the effect of different reactants (ammonia, toluene) on VPO surface and bulk properties.     

Wet oxidation of phenol, cresols and nitrophenols catalyzed by activated carbon in acid and basic media

A commercial activated carbon, Industrial React FE01606A, was used as catalyst in the wet oxidation, in both acid and basic media, of phenolic pollutants, such as phenol, cresols and nitrophenols, currently found in industrial wastewaters. Reaction runs were carried out in a fixed-bed reactor (FBR) with concurrent upflow by feeding a 1000 mg L⁻¹ aqueous solution on each pollutant concurrently with a gas oxygen flow. Temperature and oxygen pressure of the reactor were set to 160 °C and 16 bar, respectively. The basic medium was maintained by using 500 ppm sodium bicarbonate as buffer reagent to keep the pH in the range 7–8. The initial pH 3.5 was set by adding sulphuric acid. Oxidation intermediates were identified and their distribution with respect to the pollutant oxidation progress was measured. Utilizing these results, oxidation routes for each phenolic compound were deduced. The intermediates produced were diverse in acid and basic media and their composition explains the evolution of the corresponding toxicity measured at the reactor effluent. While under acidic conditions hydroxybenzoic acids, dihydroxyl benzenes and quinones were obtained as primary products, these last two compounds (more toxic than the original pollutant) were not detected in basic conditions, and with such media lower toxicities at the reactor exit were obtained. Moreover, the catalyst was found to be stable in the time range studied (300 h).     

Synthesis and characterization of abundant Ni-doped LiNixMn2−xO4 (x = 0.1-0.5) powders by spray-drying method

The structure and electrochemical properties of LiNi_xMn_2−xO₄ cathode materials for lithium ion batteries were studied by the means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), cyclic voltammetry, and galvanostatic charge-discharge tests. The cathodes with different Ni contents (LiNi_xMn_2−xO₄, x = 0.1, 0.2, 0.3, 0.4, and 0.5) were synthesized by a spray-drying method and showed a single-phase spinel structure without any impurity. The amount of Ni has a large effect on the electrochemical characteristics. Capacity values of different voltage ranges (4- and 5-V ranges) change obviously with amount of Ni-doped. Also, the total discharge capacities increase with the Ni content, and all of them have good cycle stability.     

Thermoelectric properties and stability of the Re0.2Sr0.8CoO3-δ Re = Gd,Dy) complex cobalt oxides in the temperature range of 300‒800 K

Temperature dependences of the electrical resistivity and Seebeck coefficient of the Re_0.2Sr_0.8CoO_3?δ Re =?Gd, Dy) complex cobalt oxides in the temperature range of 300 – 800?K have been investigated. The effects of ordering in the cation and anion sublattices on the thermoelectric properties has been examined and their comparative analysis has been made. It was found that, in the investigated temperature range, the thermoelectric power factor of the ordered compounds significantly exceeds the analogous parameter of the disordered samples. The temperature dependence of the electrical resistivity was shown to obey the activation law. As the temperature increases, the samples undergo a semiconductor-semiconductor electronic transition with a decrease in the activation energy. The thermoelectric properties of all the samples are shown to be stable in the investigated temperature range. The maximum thermoelectric power factor of the ordered Dy_0.2Sr_0.8CoO_2.67 cobaltite at a temperature of 360?K has been obtained; it amounts to 0.23?µW/(cm·K²), which is a good parameter for this class of materials.     

Antimicrobial properties of co-doped tricalcium phosphates Ca3-2x(MˊMˊˊ)x(PO4)2 (M = Zn2+, Cu2+, Mn2+ and Sr2+)

The substituted (Ca²⁺/Cu²⁺), and co-substituted (Cu²⁺/Zn²⁺), (Cu²⁺/Sr²⁺), and (Sr²⁺/Mn²⁺) β-tricalcium phosphate (β-TCP)-based Ca_3-2x(MˊMˊˊ)_x(PO₄)₂ (M = Zn²⁺, Cu²⁺, Mn²⁺ and Sr²⁺) solid solutions have been synthesized using solid-state route. The powder X-ray diffraction study shows the formation of β-TCP-type structure as the main phase in all solid solutions. The crystal structures and chemical compositions were approved using Fourier-transform infrared (FT-IR) absorption spectra and energy-dispersive X-ray spectrometry (EDX) data, respectively. The unit cell parameters and volume of as-synthesized samples directly depend on the radius of the incorporated ions. The limits of the single-phase solid solutions were found based on the possible occupation of the crystal sites in β-TCP structure. For the divalent ions with small radii, such as Cu²⁺ or Zn²⁺, the limit composition was found as Ca_2.571Mˊ_0.429–xMˊˊ_x(PO₄)₂ for Mˊ and Mˊˊ – Cu²⁺ and Zn²⁺. The enlargement of the unit cell by incorporation of Sr²⁺ allows to extend the limit of solid solutions up to Ca_2.5Sr_0.5–xMˊ_x(PO₄)₂ for Mˊ – Cu²⁺ or Mn²⁺. The antibacterial properties were studied on 4 bacteria (S. aureus, P. aeruginosa, E. coli and E. faecalis) and 1 fungus (C. albicans). It has been showed that co-doped Ca_2.5Sr_0.25Cu_0.25(PO₄)₂ sample exhibits the highest antimicrobial activity resulting in 92%, 96% and 96% inhibition growth rate for S. aureus, P. aeruginosa and E. faecalis, respectively. The antimicrobial properties are strongly related to the occupation of the crystal sites in the β-TCP structure by doping ions.     

基于自然原子电荷的取代苯酚酸pK_a值预测

采用密度泛函理论(DFT)和B3LYP/3-21G+(d)基组,优化了20种单取代苯酚酸分子结构,发现羟基上氧原子的自然原子轨道电荷(NBO-O)值与其实验p Ka值之间存在良好的线性关系(R=-0.973 6),比其原子核拟合的静电势电荷(ESP-O)值相吻合的要好(R=-0.8998)。计算了20种典型未知pKa值取代苯酚酸的自然原子轨道电荷(NBO)参数,代入拟合的优势线性参数方程,发现与ACD/Lab 6.0软件预测得到的取代苯酚酸pKa值较接近,其最大偏差±0.200,且新方法可估测酚类分子的p Ka值至小数点后三位数。     

N-(取代苯基)马来酰亚胺对PVC的热稳定作用

N (取代苯基 )马来酰亚胺 (N RPMI)具有近似于马来酸 (酯 )有机锡的热稳定特性 ,既可大部分代替硬脂酸钡 (Ba St)硬脂酸镉 (Cd St)复合物中的 Cd St而不降低热稳定性 ,又可少量代替硬脂酸钙 (Ca St)硬脂酸锌 (Zn St)中的 Ca St以明显提高热稳定效能。复合 N RPMI Ba St Cd St体系的热稳定性随 N RPMI中取代基拉电子效应的增强而提高 ,而 N RPMI Ca St Zn St的热稳定性基本上不受 N RPMI中取代基的影响