Study on the Preparation of Estrone Molecularly Imprinted Polymers and Their Application in a Quartz Crystal Microbalance Sensor via a Computer-Assisted Design.

Computer simulations are widely used for the selection of conditions for the synthesis of molecularly imprinted polymers and can rapidly reduce the experimental cycle time and save labor and materials. In this paper, estrone molecularly imprinted polymers (E1-MIPs) are designed at the M062X/6-311+G(d,p) level with itaconic acid (IA) as the functional monomer. The imprinted molar ratio between E1 and IA was optimized, cross-linkers and solvents were screened, and the nature of interactions between E1 and IA was explored. The simulated results showed that pentaerythritol triacrylate was the best cross-linker. Meanwhile, when the imprinted molar ratio between E1 and IA was 1:4, the E1-IA complex had the largest amount of hydrogen bonds, the lowest binding energy, and the strongest stability. Using the simulation results as guidance, the E1-MIPs were prepared to modify the electrons of a quartz crystal microbalance (QCM) sensor. The experimental studies showed that the E1-MIPs-QCM sensor had the highest adsorption capacity to E1 in comparison with their analogues, and the lowest detection value of the sensor was 16.00 µg/L. The computer simulations and experimental studies could provide guidance for synthesize novel E1-MIPs materials. It also could provide important references and directions for the application of E1-MIPs.

Preparation of a quartz microbalance sensor based on molecularly imprinted polymers and its application in formaldehyde detection.

Quartz crystal microbalances (QCMs) have been widely used in the food industry, environmental monitoring, and biomedicine. Here, a molecularly imprinted QCM sensor was prepared and used for formaldehyde detection. Using polyvinyl chloride as the embedding material and tetrahydrofuran as the solvent, a QCM electrode was modified with HCHO molecularly imprinted polymers (HCHO-MIPs). The detection conditions of the sensor were optimized, and its selectivity was investigated. The theoretical calculation results revealed that the acrylamide and pentaerythritol triacrylate were potential candidate functional monomer and cross-linking agent, respectively, in the preparation of HCHO-MIPs with high adsorbability, superselectivity, and stability. According to the calculated results, a sensor had been prepared. When the pH was 7, the added mass of the HCHO-MIPs (or NIPs) was 20 mg, and the amount of PVC coating was 20 µL, the sensor exhibited good adsorption, selectivity, repeatability, high sensitivity, high accuracy, and a short response time. The lowest detection limit was 10.72 ng mL-1. The sensor exhibited higher selectivity for HCHO than for propionaldehyde and benzaldehyde. The HCHO contents in fresh shrimp samples were detected using the sensor for four cycles, and the detection rates were in the range of 97.56-98.60%. This study provided a theoretical and experimental basis for the rapid detection of HCHO.

Chiral-Directing-Group-Assisted Rhodium(III)-Catalyzed Asymmetric Addition of Inert Arene C-H Bond to Aldimines with Subsequent Intramolecular Cyclization.

By using a chiral directing group, an asymmetric rhodium(III)-catalyzed C-H bond addition to aldimines followed by intramolecular cyclization to form chiral isoindolinones has been achieved (up to 68 % yield, up to 93 % ee). A three-component variant that resembles Mannich reaction was also realized (41 % yield, 83 % ee). Product elaborations and preliminary mechanistic studies were described.

Migration dynamics of an important rice pest: The brown planthopper (Nilaparvata lugens) across Asia-Insights from population genomics.

INTRODUCTION: Brown planthoppers (Nilaparvata lugens) are the most serious insect pests of rice, one of the world's most important staple crops. They reproduce year-round in the tropical parts of their distribution, but cannot overwinter in the temperate areas where they occur, and invade seasonally from elsewhere. Decades of research have not revealed their source unambiguously. METHODS AND RESULTS: We sequenced the genomes of brown planthopper populations from across temperate and tropical parts of their distribution and show that the Indochinese peninsula is the major source of migration into temperate China. The Philippines, once considered a key source, is not significant, with little evidence for their migration into China. We find support for immigration from the west of China contributing to these regional dynamics. DISCUSSION: The lack of connectivity between the Philippine population and the mainland Chinese populations explains the different evolution of Imidacloprid resistance in these populations. This study highlights the promise of whole-genome sequence data to understand migration when gene flow is high-a situation that has been difficult to resolve using traditional genetic markers.

Dynamic shift effect on bistability in nonlinear optical microcavities.

The shift of optical cavity modes oscillates due to the time-varying refractive index under Kerr nonlinearity. To reveal its impact on bistability, we present a time-average approach that includes this dynamic shift characteristic in the expression of nonlinear transmission. It predicts the monotonous decrease of the maximum transmission with the increase of the frequency detuning. Also, the frequency detuning to start bistability should be corrected as about 2. Our analyses are supported by the simulations based on the finite-difference time-domain technique.