Investigation of peptoid chiral stationary phases varied in absolute configuration

Based on chiral N-(1-phenylethyl) glycines, a series of peptoid chiral stationary phases (CSPs) terminated with achiral alkyl group (diisopropyl, t-butyl or n-butyl) and varied in absolute configuration of selector were investigated with nine axially chiral analytes. It is very interesting to observe that selectors with heterogeneous configuration form, such as S-R-R, S-R-S, S-S-R, generally performed better than S-S-S selectors. Moreover, longer S-R-S-R-S selector did not outperform the S-R-S one obviously, with several separations declined. In addition to the result that the elution order of most enantiomers depends on the asymmetric center adjacent to the terminus of selector, we presume that the moieties around this chiral center are the most important absorbing sites for chiral discrimination; the terminal group and other chiral blocks in selector may assist enantiorecognition by constructing appropriate conformation. Various terminal alkyl groups also resulted in a few differences in enantioselectivity. (C) 2013 Published by Elsevier B.V

TiO2和氧化物修饰的介孔材料用于富集磷酸化多肽

Reversible protein phosphorylation regulate most cellular processes such as signal transduction, metabolic maintenance and cell cycle. Analysis of this modifications presents formidable challenges due to their low abundance and the signal suppression of non-phosphorylated peptides. Thus, it is vital to enrich phosphopeptides from the highly complicated mixture prior to mass spectrometry (MS) analysis. In this study, different titanium-metal oxide composites with monodisperse uniform microsphere (~ 3µm) were synthesized by sol-gel method. Among these, seven titanium-metal oxide composites including TiO2-ZrO2 and TiO2-Al2O3 provided efficient enrichment of phosphopeptides and show higher specificity for phosphopeptides when compared with the commercial TiO2. In addition, we synthesized metal oxide (MxOy) coated mesoporous cellular foam structure (MCF) according to reported procedure. These materials were characterized with X-ray diffraction patterns, scanning electron microscopy, N2 sorption and UV-visible diffuse reflectance spectra and found their high surface area, large pore size and highly dispersed matel ions on the mesoporous silica surface. Isolation of phosphopeptides by MxOy on the mesoporous silica surface was demonstrated to be very specific and selective using model phosphoproteins as the test samples. Compared to the commonly used enrichment methods, this phosphopeptides enrichment strategy is more efficient and effective for both single- and multi-phosphopeptides

Improvement of peptoid chiral stationary phases by modifying the terminal group of selector

The role of a terminal group of a peptoid selector in a chiral separation was investigated. Six chiral stationary phases (CSPs) with the terminal groups replaced by achiral alkyl groups (n-butyl, t-butyl and diisopropyl) and chiral groups ((1R, 2R)-2-aminocyclohexyl phenylcarbamate, N'-phenyl-L-proline amide and N'-phenyl-L-leucine amide) were synthesized. Achiral terminal groups with different steric hindrances did not broaden the enantioselectivity, but improved the separation factors for some analytes, probably due to the improvement of interactions between the analytes and peptoid chain. Introducing new chiral terminal groups proved an effective way to broaden the applicable spectrum of peptoid CSPs. (C) 2012 Elsevier B.V. All rights reserved

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements