Boosting the synthesis of value-added aromatics directly from syngas via a Cr2O3 and Ga doped zeolite capsule catalyst

Even though the transformation of syngas into aromatics has been realized via a methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO₂ coating was combined with the methanol synthesis catalyst Cr₂O₃ to boost the synthesis of value-added aromatics, especially para-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C–C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas.

The single-pass conversion of syngas into para-xylene was realized using a bifunctional catalyst Cr₂O₃/Ga-ZSM-5@SiO₂. The Ga species facilitates the methanol consumption process by C–C coupling optimization, enhancing the yield of the target aromatics.     

Measurement of filtering efficiency of artificial radioactive aerosol filter membrane

Journal of Radioanalytical and Nuclear Chemistry - When monitoring radioactive aerosol in the atmosphere, choosing a filter membrane with better surface collection characteristics and filtering...     

Design of an on-line monitoring system for radioactive wastewater

An on-line monitoring system for radioactive wastewater was designed to discriminate the type and concentration of the radionuclides discharged from nuclear facilities. An HPGe semiconductor was used as the detector in the system for continuous monitoring by pumping wastewater. The minimum detectable activity for ¹³⁷Cs was 0.4 Bq L⁻¹ after 10 min of measuring wastewater with the system. The system can detect excessive radioactivity in the wastewater and quickly and effectively alert personnel. Based on the experimental measurements and the Monte Carlo simulation, the detection efficiency of the system was calibrated, and an efficiency curve was determined for the energy range from 50 to 2754 keV.

     

Adsorption behavior of 4-methoxypyridine on gold nanoparticles

We demonstrate a phase transfer method to create stable colloidal solutions of Au nanoparticles with 4-methoxypyridine ligands. We then investigate the adsorption behavior of 4-methoxypyridine onto gold surfaces by Raman spectroscopy, DFT calculations, and (1)H NMR. In contrast to unsubstituted pyridine and the frequently used (N,N-dimethylamino)pyridine (DMAP), a flat adsorption of 4-methoxypyridine on gold was found.     

Determination of sophoraflavanone G and kurarinone in rat plasma by UHPLC–MS/MS and its application to a pharmacokinetic study

This study aimed to develop and validate a simple and sensitive ultra high performance liquid chromatography tandem mass spectrometry method for the simultaneous determination of sophoraflavanone G and kurarinone in rat plasma by using rutin as the internal standard. Then, the developed method was applied to investigate the pharmacokinetics of sophoraflavanone G and kurarinone in rats after dosing the flavonoid extract from Sophora flavescens. Plasma samples were processed using a liquid–liquid extraction procedure with ethyl acetate. The analysis was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring with an electrospray ionization source in negative ionization mode. Quantitative ion transitions of m/z 423.2→161.2, 437.2→161.1, and 609.3→300.3 were monitored for sophoraflavanone G, kurarinone, and rutin, respectively. The calibration curves of the two analytes exhibited good linearity (r²>0.9923) over the range of 0.1–200 ng/mL for sophoraflavanone G and 0.1–1000 ng/mL for kurarinone. Relative standard deviations were less than 13.2% for the intra‐ and inter‐day precisions and no more than 12.6% for the recovery, showing good precision and satisfactory accuracy of the developed method. The validated method was successfully applied to the pharmacokinetic study of sophoraflavanone G and kurarinone after a single intravenous (25 mg/kg) and oral (500 mg/kg) administration of the flavonoid extract from S. flavescens, and the absolute bioavailability for sophoraflavanone G and kurarinone was about 36 and 17%, respectively.     

Manganese-catalyzed oxidative homo-coupling of aryl Grignard chlorides

Manganese-catalyzed homo-coupling of aryl magnesium chlorides to give biphenyls was successfully achieved using manganese chloride as catalyst. A variety of aryl magnesium chlorides were efficiently converted into the corresponding symmetrical biaryls using 10 mol% MnCl₂ as catalyst in the presence of a stoichiometric amount of 1,2-dichloroethane. Since the aryl chlorides, from which the Grignard reagents were prepared, are cheaper and more readily available that the corresponding bromides and iodides this procedure should become the method of choice for preparing symmetrical biaryls.     

Design of a calibration system for radioactive aerosol monitor

Journal of Radioanalytical and Nuclear Chemistry - A calibration system was designed to meet the calibration requirement of the radioactive aerosal monitors. The system consists of a radioactive...     

On a theorem of Chowla

Let be a finite field with q=p^felements, where p is a prime number and f is a positive integer. For a nonprincipal multiplicative character χ and a nontrivial additive character ψ on , it is well known that Gauss sum has absolute value . In this paper, we investigate when is a root of unity.     

天然植物复杂化学模式特征的分步提取法

在运用神经元计算技术对高维小样本复杂化学模式进行分类时,通过模式特征提取,降低输入变量维数,能使复杂的模式分类问题比较容易解决。根据模式类别相关分步分析思路,提出复杂化学模式特征分步提取法,可将原始模式数据中与类别指标相关较大的特征量有效地提取出来。应用于天然植物组效关系辨识结果表明,这种化学模式特征提取方法比经典主成分分析法更为实用可靠。     

Estimations on upper and lower bounds of solutions to a class of tensor complementarity problems

We introduce a class of structured tensors, called generalized row strictly diagonally dominant tensors, and discuss some relationships between it and several classes of structured tensors, including nonnegative tensors, Btensors, and strictly copositive tensors. In particular, we give estimations on upper and lower bounds of solutions to the tensor complementarity problem (TCP) when the involved tensor is a generalized row strictly diagonally dominant tensor with all positive diagonal entries. The main advantage of the results obtained in this paper is that both bounds we obtained depend only on the tensor and constant vector involved in the TCP;and hence, they are very easy to calculate.