“联用技术及元素形态”国际课程探索与实践*

充分利用线上教学的优势,对化学院本科生开设了“联用技术及元素形态”国际课程,避免了传统教学中组织、协调外籍/外地专家资源过程中必要的各种消耗,极大程度地整合教学资源、改善教学效果。在该课程的探索与实践过程中,学生们对痕量元素形态及基于等离子体质谱的各种联用技术产生了极大的兴趣,激发了他们的主动学习热情;教师之间及师生之间的沟通趋向更简单、更灵活、更实时,为后续线上线下混合式国际课程建设提供了良好的基础和借鉴。     

甲烷-二氧化碳重整制合成气与现代分析技术应用于探究性化工专业实验的设计与探索

以甲烷-二氧化碳重整制合成气为实例，设计探究性实验，将合成气的制备和现代分析技术应用于化工专业实验的教学实践中以提高学生的创新和实践能力。实验包括催化剂的制备，催化剂的性能评价和催化剂的表征等3大部分。采用工业最常用的浸渍法制备含有不同助剂的Ni/X/γ-Al2O3（X为Co，Fe，MgO，CeO2）催化剂，以甲烷-二氧化碳重整反应评价其催化性能，并采用XRD、H2-TPR、BET和TG对催化剂的微观结构进行表征。结合催化剂的性能评价结果和表征结果，探讨不同助剂对镍基催化剂性能的改善效果及机制。通过开设该实验，可以让学生了解化工学科的前沿知识以及现代分析技术的基本原理和用途，掌握专业的实验操作、数据处理和谱图绘制方法，提高学生的专业素养和综合能力。     

Binary neutron stars gravitational wave detection based on wavelet packet analysis and convolutional neural networks

This work investigates the detection of binary neutron stars gravitational wave based on convolutional neural network(CNN).To promote the detection performance and efficiency,we proposed a scheme based on wavelet packet(WP)decomposition and CNN.The WP decomposition is a time-frequency method and can enhance the discriminant features between gravitational wave signal and noise before detection.The CNN conducts the gravitational wave detection by learning a function mapping relation from the data under being processed to the space of detection results.This function-mapping-relation style detection scheme can detection efficiency significantly.In this work,instrument effects are con-sidered,and the noise are computed from a power spectral density(PSD)equivalent to the Advanced LIGO design sensitivity.The quantitative evaluations and comparisons with the state-of-art method matched filtering show the excellent performances for BNS gravitational wave detection.On efficiency,the current experiments show that this WP-CNN-based scheme is more than 960 times faster than the matched filtering.     

Determination of cobalt ion based on polyethyleneimine modified silver nanoclustersEI北大核心CSCD

PolyethyleneiminePEImodified silver nanoclustersAg NCswere synthesized through chemical reduction method by using PEI as stabilizerAgNO3 as silve source and ascorbic acid as reducing agentand it was applied to the detection of cobalt ions. It was found that the fluorescence of the silver nanoclusters was quenched by Co2+ for the aggregation of PEI-Ag NCs caused by the coordination between cobalt ion and amino group on polyethyleneimine. Under the optimized experimental conditionsthe fluorescence quenching degree of PEI-Ag NCs was piecewise linear with the concentration of cobalt ion in the range of 8.30×10-7-4.17×10-4 mol/L and the detection limit was 0.41 μµmol/L. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Some optimizations on detecting gravitational wave using convolutional neural network

This work investigates the problem of detecting gravitational wave (GW) events based on simulated damped sinusoid signals contaminated with white Gaussian noise. It is treated as a classification problem with one class for the interesting events. The proposed scheme consists of the following two successive steps: decomposing the data using a wavelet packet, representing the GW signal and noise using the derived decomposition coefficients; and determining the existence of any GW event using a convolutional neural network (CNN) with a logistic regression output layer. The characteristic of this work is its comprehensive investigations on CNN structure, detection window width, data resolution, wavelet packet decomposition and detection window overlap scheme. Extensive simulation experiments show excellent performances for reliable detection of signals with a range of GW model parameters and signal-to-noise ratios. While we use a simple waveform model in this study, we expect the method to be particularly valuable when the potential GW shapes are too complex to be characterized with a template bank.     

A Three‐Minute Synthesis and Purification of Ibuprofen: Pushing the Limits of Continuous‐Flow Processing

In a total residence time of three minutes, ibuprofen was assembled from its elementary building blocks with an average yield of above 90 % for each step. A scale‐up of this five‐stage process (3 bond‐forming steps, one work‐up, and one in‐line liquid–liquid separation) provided ibuprofen at a rate of 8.09 g h^?1 (equivalent to 70.8 kg y^?1) using a system with an overall footprint of half the size of a standard laboratory fume hood. Aside from the high throughput, several other aspects of this synthesis expand the capabilities of continuous‐flow processing, including a Friedel–Crafts acylation run under neat conditions and promoted by AlCl₃, an exothermic in‐line quench of high concentrations of precipitation‐prone AlCl₃, liquid–liquid separations run at or above 200 psi to provide solvent‐free product, and the use of highly aggressive oxidants, such as iodine monochloride. The use of simple, inexpensive, and readily available reagents thus affords a practical synthesis of this important generic pharmaceutical.     

卵巢癌、成熟型畸胎瘤与正常血液样本中挥发性组分的研究

采用顶空固相微萃取(HS-SPME)与气相色谱-质谱(GC-MS)联用技术,对12例卵巢癌、17例成熟型畸胎瘤与16例正常血液样本的挥发性组分进行研究,对影响提取效果的实验因素进行了优化.在最优条件下共检出28种挥发性组分,以各组分峰面积为变量,用SIMCA-P软件进行偏最小二乘判别分析(PLS-DA),3组样本被明显区分.同时,依据PLS-DA载荷图得到8种具有显著性差异的标志物,其中己醛、蘑菇醇的变化与其在肝癌、肺癌患者血液中的变化一致,可作为诊断卵巢癌和成熟型畸胎瘤的挥发性生物标志物.     

Review of the role and methodology of high resolution approaches in aroma analysis

Analysis of the odour complexity in food and beverage products demands high resolution approaches for distinguishing individual aroma-impact compound(s), and for assessing their contribution to the global aroma of a sample. This paper aims to review current applications incorporating different advanced separation methodologies, and their roles in achieving high resolution aroma analysis. This includes prior low resolution gas chromatography–olfactometry (GC–O) with fractionation procedures using chemical manipulation, adsorption chromatography and ion exchange separation. Innovative multidimensional gas chromatography (MDGC) arrangements that are appropriately designed with olfactometry are of specific focus here. The revelation of resolved components using these integrated approaches provides significantly improved knowledge of aroma composition in samples.     

Optimal design of experiments applied to headspace solid phase microextraction for the quantification of vicinal diketones in beer through gas chromatography-mass spectrometric detection

Vicinal diketones, namely diacetyl (DC) and pentanedione (PN), are compounds naturally found in beer that play a key role in the definition of its aroma. In lager beer, they are responsible for off-flavors (buttery flavor) and therefore their presence and quantification is of paramount importance to beer producers. Aiming at developing an accurate quantitative monitoring scheme to follow these off-flavor compounds during beer production and in the final product, the head space solid-phase microextraction (HS-SPME) analytical procedure was tuned through experiments planned in an optimal way and the final settings were fully validated. Optimal design of experiments (O-DOE) is a computational, statistically-oriented approach for designing experiences that are most informative according to a well-defined criterion. This methodology was applied for HS-SPME optimization, leading to the following optimal extraction conditions for the quantification of VDK: use a CAR/PDMS fiber, 5 ml of samples in 20 ml vial, 5 min of pre-incubation time followed by 25 min of extraction at 30 °C, with agitation. The validation of the final analytical methodology was performed using a matrix-matched calibration, in order to minimize matrix effects. The following key features were obtained: linearity (R² > 0.999, both for diacetyl and 2,3-pentanedione), high sensitivity (LOD of 0.92 μg L⁻¹ and 2.80 μg L⁻¹, and LOQ of 3.30 μg L⁻¹ and 10.01 μg L⁻¹, for diacetyl and 2,3-pentanedione, respectively), recoveries of approximately 100% and suitable precision (repeatability and reproducibility lower than 3% and 7.5%, respectively). The applicability of the methodology was fully confirmed through an independent analysis of several beer samples, with analyte concentrations ranging from 4 to 200 g L⁻¹.