Novel hollow microspheres MnxCo3−xO4 (x = 1, 2) with remarkable performance for low-temperature selective catalytic reduction of NO with NH3

Journal of Sol-Gel Science and Technology - Hollow microspheres MnCo2O4 and CoMn2O4 have been synthesized by a facile solvothermal route followed by pyrolysis of the carbonate counterparts and...     

Synthesis of polysiloxanes containing trifluoroethylene aryl ether groups: The effect of promoters

Polysiloxanes with high molecular weight (M_n > 100 000, M_w/M_n < 2.2) containing various quantity of trifluoroethylene aryl ether groups were prepared by anion ring opening polymerization (AROP) in the presence of promoters including N,N‐dimethylformamide (DMF) and N‐methyl pyrrolidone (NMP). The structures of monomers and polymers were characterized by FTIR and NMR. It was found that the addition of promoter could significantly increase the polymerization rate, decrease the polymerization temperature, and increase the molecular weight of the polymer. When DMF as the promoter, the optimal conditions for polymerization were as follows: The polymerization temperature is 100°C, the amount of catalyst is 2.0%, and the molar ratio of promoter to catalyst is 160:1. The optimal conditions for polymerization using NMP as the promoter were as follows: The polymerization temperature is 75°C, the amount of catalyst is 2.0%, and the molar ratio of promoter to catalyst is 70:1, which indicated that NMP is more effective on AROP than DMF. Thermogravimetric analysis (TGA) showed that the polymer has good heat temperature resistance. Differential scanning calorimetry (DSC) showed that the introduction of NMP in bulk polymerization could improve the randomness of polymer structure, which leads to the disappearance of crystal peak and improve the low temperature resistance of polymer.     

新型斑蝥素羧酸衍生物的合成及其抗癌活性

以DMSO为溶剂,5-氟脲嘧啶(5-Fu)为修饰物,对去甲斑蝥素(2)酸酐环部分进行结构修饰,合成了一个新型的去甲斑蝥素羧酸衍生物(3),其结构经1H NMR和IR表征。采用L9(34)正交试验考察了原料比,反应温度,反应时间及溶剂用量对反应的影响。结果表明,在最佳反应条件[2 0.5 mmol,n(2)∶n(5-Fu)=1.2,于140℃反应6 h,DMSO用量15 mL]下制备的3收率为78.2%。采用MTT法研究了体外3对人肝癌细胞HepG2的抑制活性。结果表明,3在用药量为250μmol·L-1时对HepG2的抑制率为89.5%,其IC50为232.4μmol·L-1。     

Sensitive determination of organic acid preservatives in juices and soft drinks treated by monolith-based stir cake sorptive extraction and liquid chromatography analysis

A simple, efficient, and sensitive method for simultaneous determination of sorbic acid (SA), benzoic acid (BA), and cinnamic acid (CA) in juices and soft drinks was developed by stir cake sorptive extraction (SCSE) coupling to high-performance liquid chromatography with diode array detection. The SCSE based on polymeric ionic liquid-based monolith (PILM) as extractive medium was used to concentrate these three organic acid preservatives. Because hydrophobic and ion-exchange interactions co-contributed to the extraction, the PILM-SCSE exhibited a high extractive capability towards analytes. To obtain optimum extraction performance, several SCSE parameters were investigated and discussed, including desorption solvent, pH value, ionic strength in the sample matrix, and the extraction and desorption time. Under the optimized extraction conditions, limits of detection of 0.16, 1.08, and 0.18 μg/L (S/N?=?3) and quantification limits of 0.52, 3.42, and 0.61 (S/N?=?10) were obtained for SA, BA, and CA, respectively. The method also showed good linearity and reproducibility, as well as advantages such as simplicity, low cost, and high feasibility. Finally, the proposed method was successfully applied to the determination of SA, BA, and CA in real juices and soft drinks, and the recoveries ranged from 63.0 to 107 %.     

分部积分公式的一种证明

运用阿贝尔分部求和公式,给出定积分分部积分公式的一种新证明．     

关于排序不等式的一个简单证明

利用Abel变换,给出排序不等式的证明,并对等号成立问题作了进一步的讨论.     

A simple route to synthesize scales of aligned single-crystalline SiC nanowires arrays with very small diameter and optical properties

Scales of aligned single-crystalline SiC nanowires (SiCNWs) arrays with very small diameter were synthesized by a simple thermal evaporation of ZnS and carbon on silicon wafer. The as-received SiCNWs possess a uniform size distribution centered at approximately 8.0 nm, even with a minimum of approximately 3.0 nm. The highly oriented SiCNWs usually grew along [111] direction with a clean surface, very thin oxide shell, and small quantity of stacking faults. A crystalline tube-like SiC nanostructure is also obtained. The optical properties, including photoluminescence and Raman scattering spectra of the SiCNWs, were investigated, respectively. In the end, a growth model on basis of the experimental data is suggested.     

Alkaloids and citrinins from marine-derived fungus Nigrospora oryzae SCSGAF 0111

A new pyrrolidinone, nigrospine (1), a new indole alkaloid, nigrospin A (2) and two new citrinins, nigrospins B and C (3-4) were isolated from a culture broth of the marine-derived fungal strain Nigrospora oryzae SCSGAF 0111. Their structures were determined by spectroscopic analysis, and the absolute configurations of 1 and 2 were determined by the Mosher ester technique. Compound 1 contains a rare 2,3-dihydro-benzofuran[2,3-c]2-pyrrolidone skeleton.     

Synthesis, Crystal Structure and Cytotoxic Property of Bis(4-chlorobenzoato)bis[1-(2-aminoethyl)piperidine]disilver(I)

Abstract  

4-Chlorobenzoic acid reacts with silver oxide and 1-(2-aminoethyl)piperidine to give a dinuclear silver(I) complex, [Ag₂(C₇H₄ClO₂)₂(C₇H₁₆N₂)₂]. The complex was characterized by elemental analysis and X-ray diffraction. The complex crystallizes in the triclinic space group P−1 with unit cell dimensions a = 6.8550(10), b = 8.7370(10), c = 13.859(2) ?, α = 73.213(3), β = 87.945(3), γ = 77.050(3)°, V = 774.09(18) ?³, Z = 1, R ₁ = 0.0386, and wR ₂ = 0.0791. The dimeric Ag complex is located on an inversion center. The Ag atom in the complex is three-coordinated by two N atoms from two 1-(2-aminoethyl)piperidine ligands and by one O atom of a 4-chlorobenzoate ligand, forming a triangular coordination. In the crystal structure, the molecules are linked through intermolecular N–H···O hydrogen bonds, forming chains running along the a axis. The complex shows high cytotoxic property to both normal and carcinoma cells.     

A novel FOCAL technique based on BP-ANN

In this paper, the feed-forward back-propagation artificial neural network (BP-ANN) algorithm is introduced in the traditional Focus Calibration using Alignment procedure (FOCAL) technique, and a novel FOCAL technique based on BP-ANN is proposed. The effects of the parameters, such as the number of neurons on the hidden-layer and the number of training epochs, on the measurement accuracy are analyzed in detail. It is proved that the novel FOCAL technique based on BP-ANN is more reliable and it is a better choice for measurement of the image quality parameters.