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202 results on '"He, Junming"'

11. Biocompatible Synthesis of Macrocyclic Thiazol(in)e Peptides.

Author

He, Junming and Nitsche, Christoph

Subjects
*PEPTIDES, *DRUG discovery, *PEPTIDE synthesis, *SOLID-phase synthesis, *AMINOACETONITRILE, *THIAZOLES
Abstract

Macrocyclic peptides containing a thiazole or thiazoline in the backbone are considered privileged structures in both natural compounds and drug discovery, owing to their enhanced bioactivity, stability, and permeability. Here, we present the biocompatible synthesis of macrocyclic peptides from N‐terminal cysteine and C‐terminal nitrile. While the N‐terminal cysteine is incorporated during solid‐phase peptide synthesis, the C‐terminal nitrile is introduced during cleavage with aminoacetonitrile, utilizing a cleavable benzotriazole linker. This method directly yields the fully functionalized linear peptide precursor. The biocompatible cyclization reaction occurs in buffer at physiological pH and room temperature. The resulting thiazoline heterocycle remains stable in buffer but hydrolyzes under acidic conditions. While such hydrolysis enables access to macrocyclic peptides with a complete amide backbone, mild oxidation of the thiazoline leads to the stable thiazole macrocyclic peptide. While conventional oxidation strategies involve metals, we developed a protocol simply relying on alkaline salt and air. Therefore, we offer a rapid and metal‐free pathway to macrocyclic thiazole peptides, featuring a biocompatible key cyclization step. [ABSTRACT FROM AUTHOR]

Published
2024
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37. Research on LED multi-sector stable display model in variable rotational speed

Author

Ma Dong, Dong Jun, Xu Panpan, Ma Fan, He Junming, and Lang Luhong

Subjects
Computational Mathematics, Variable (computer science), Control theory, Computer science, 0103 physical sciences, General Engineering, Rotational speed, 010103 numerical & computational mathematics, 0101 mathematics, 010301 acoustics, 01 natural sciences, Multi sectoral, Computer Science Applications
Abstract

To solve the display distortion caused by the motor rotational speed changes in the long-term operation of the rotating LED multi-sector display system, the model for LED multi-sector stable display (MSSD) in variable rotational speed is proposed based on the principle of visual persistence. The stepping motor subdivision driving technology is applied to the rotating LED multi-sector display, and the equal precision frequency measurement method is used for accurate rotational speed measurement. Then the innovation adaptive kalman filter (IAKF) is researched to further enhance the robustness to eliminate noise pollution, and the relationship between the modification value caused by rotational speed and the LED linear array minimum refresh time is analysed. The rotating LED MSSD system based on LED linear array rotated by stepping motor is provided. The test results reveal the relationship between rotational speed and the LED linear array minimum refresh time, and show that the lighting position of the LED can be synchronized with the lighting state during the rotational speed fluctuation, and the error can be controlled to a low level via LED linear array minimum refresh time correction. The designed model can effectively eliminate the distortion of the rotating LED multi-sector display screen caused by the changes of the motor rotational speed, and has a very stable display effect.

Published
2021

38. Conservation and Restoration of Mangroves in Response to Invasion of Spartina alterniflora Based on the MaxEnt Model: A Case Study in China.

Author

Cui, Lina, Berger, Uta, Cao, Minmin, Zhang, Yaqi, He, Junming, Pan, Lianghao, and Jiang, Jiang

Subjects
MANGROVE plants, SPARTINA alterniflora, CONSERVATION & restoration, OCEAN temperature, BIOLOGICAL invasions, CURRENT distribution
Abstract

In China, the invasion of Spartina alterniflora is an important driver for the decrease of mangrove area and ecological service functions related to this habitat. In the past few decades, S. alterniflora clearing and mangrove restoration projects have mainly focused on the areas where it is already changed but ignored the potential distribution areas. This study suggested that implementation of mangrove protection prior to the areas with the threat of S. alterniflora invasion could greatly improve protection efficiency and save costs. Thus, using Maximum Entropy Modeling (MaxEnt), we estimated the potential spatial distribution of both mangroves and S. alterniflora in China, considering the current distribution data, topographical, sediments, sea surface temperature and bioclimatic variables. What's more, we identified and calculated the potential distributed areas in each province. We aimed to explore (i) the key factors determining the distribution of mangrove and Spartina alterniflora along the coastline and (ii) the hotspots of their competitive occurrence, including S. alterniflora invasion areas and mangroves degradation areas, in order to support mangrove conservation. The model showed that the distance to the coastline and the topography play important roles in the distribution of S. alterniflora, while mangroves were more sensitive to the range of the annual sea surface temperature. Our results furthermore confirm that S. alterniflora has a wider potential distribution area (~10,585 km2) than mangroves (~9124 km2) at the coastline of China; and predict the provinces Zhangzhou, Quanzhou, Zhanjiang, Beihai and Wenzhou as hotspots for the competition between mangroves and S. alterniflora. We propose that priority should be given to the protection or restoration of mangrove plants in those areas which are co-suitable for mangroves and S. alterniflora. In these areas, management measures should be conducted that hinder S. alterniflora invasions or clear existing S. alterniflora plants, firstly. This study provides guidance for the management of native species by preventing biological invasion. [ABSTRACT FROM AUTHOR]

Published
2023
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49. Design and preparation of the WO3 hollow spheres@ PANI conducting films for room temperature flexible NH3 sensing device

Author

Wang Caileng, Geyu Lu, Peng Sun, Siqi Li, Ao Liu, Xishuang Liang, Jing Wang, Zijie Yang, Liupeng Zhao, Rui You, Xu Yan, Fangmeng Liu, and He Junming

Subjects
Materials science, Metals and Alloys, Nanotechnology, Heterojunction, 02 engineering and technology, Substrate (electronics), 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Hydrothermal circulation, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, chemistry, Polymerization, Polyaniline, Materials Chemistry, Polyethylene terephthalate, SPHERES, Electrical and Electronic Engineering, 0210 nano-technology, Selectivity, Instrumentation
Abstract

The development of room temperature NH3 sensors with flexible substrate can fulfill the future demands of high NH3 sensing performance under the premise of lower energy consumption and safety circumstance in wearable electronics field. The polyaniline and a serious of WO3 hollow spheres@ polyaniline hybrid were successfully synthesized via a combined route of simple hydrothermal method and in-situ chemical oxidative polymerization. The room temperature NH3 sensors were fabricated by assembling WO3 hollow spheres@ polyaniline hybrid on flexible polyethylene terephthalate (PET) films. The NH3 sensing properties of the fabricated devices demonstrated that the device utilizing 10 mol% WO3 hollow spheres@ polyaniline (PAWHs 10) hybrid exhibited the best sensing performance to 100 ppm NH3 (response value at 25) at 20 °C. Moreover, the PAWHs10 hybrid sensor also achieved excellent NH3 selectivity, ppb-level detection limit (1.67–500 ppb NH3), and good response/recovery rates (136 s/130 s) at 20 °C. The enhanced sensing performance of incorporation of polyaniline and WO3 hollow spheres was mainly attributed to the hollow structure of WO3 and the formation of p-n heterojunction between PANI and WO3 hollow spheres.

Published
2019

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