CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Qiuqin Lin,Yuxiang Huang,Wenji Yu
In this study, two methods including a common method using high concentration of alkali solution and a mild extraction method at ambient conditions were used to extract cellulose from bamboo. The results showed that two methods affected the initial state of the cellulose. Celluloses obtained by the former was a hybrid of cellulose I and II while the latter was pure cellulose I. However, their heat treatment results indicated that the heat treatment (≤200 °C) would not change the aggregation structure of bamboo cellulose, but it will cause the change of intramolecular and intermolecular hydrogen bonds, and the break of glycosidic bonds in the amorphous region and part of the crystalline region of cellulose. Accordingly, the crystallinity of bamboo cellulose will decrease slightly after heat treatment. Finally, the macroscopic morphology change of bamboo cellulose caused by heat treatment was the thermal expansion in the width direction instead of distort.
研究领域:
材料科学
·
植物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SENSORS
·
2017
·Vol. 17
·期 4
·811
·
IF 2.677
Wei-Qiong Li,Bing Huang,Miao-Ling Huang,Lin-Lu Peng,Ze-Wen Hong,Ju-Fang Zheng,Wen-Bo Chen,Jian-Feng Li,Xiao-Shun Zhou
The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM) break junction. Conductance measurement of alanine gives out two conductance values at 10−1.85G0(1095 nS) and 10−3.7G0(15.5 nS), while similar conductance values are also observed for aspartic acid and glutamic acid, which have one more carboxylic acid group compared with alanine. This may show that the backbone of NH2–C–COOH is the primary means of electron transport in the molecular junction of aspartic acid and glutamic acid. However, NH2–C–COOH is not the primary means of electron transport in the methionine junction, which may be caused by the strong interaction of the Au–SMe (methyl sulfide) bond for the methionine junction. The current work reveals the important role of the anchoring group in the electron transport in different amino acids junctions.Keywords:amino acid;single-molecule junction;STM break junction;carboxylic acid;amine
研究领域:
生物物理学
·
分子电子学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
·
2020
·Vol. 55
·期 9
·3091-3103
·
IF 2.773
Zhen Wu,Hong Li,Yang Luo,Gang Chen,Juan Li,Yongde Wang,Yong Yang,Hongjun Tan
Pomelo ( Citrus maxima Merr.), known as a famous fruit and folk medicine, is widely cultivated in China. Nonedible pomelo tissues contain peels, seeds, and segment membranes, which generally being discarded. Polysaccharides relationships among different pomelo tissues remain uncertain. Four water-soluble polysaccharides, PPPs, PSPs, FPPs and SMPs, were extracted from pomelo peels, seeds, pulps and segment membranes, respectively. Molecular structure and conformation were investigated by a combination of chemical and instrumental analyses. PPPs and FPPs were consisted of Ara, GalA, GlcA, Rha, Glc, Xyl and Gal, while PSPs and SMPs did not contain GalA and Gal. The average molecular weight (Mw) of PPPs, PSPs, FPPs and SMPs was 4.604 × 10 5 , 10.85 × 10 5 , 5.795 × 10 5 and 16.06 × 10 5 Da, respectively. PPPs, PSPs and SMPs all showed totally spherical structures, while FPPs primarily comprised linear chains. The structures–bioactivities correlations analysis revealed that low-Mw polysaccharides had strong DPPH • , OH• scavenging and HeLa cells inhibiting activities. These data revealed that the bioactivities of pomelo tissues polysaccharides were not a function of a single factor but a combination of various characteristics.
研究领域:
植物化学
·
食品科学
·
药理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2010
·Vol. 117
·期 1
·235-242
·
IF 1.203
Hongtao Liu,Weilin Xu,Sanping Zhao,Jingjing Huang,Hongjun Yang,Yunli Wang,Chenxi Ouyang
Biomedical polyurethane (PU) and silk fibroin have similar molecular architecture in their primary and aggregate structure, both of which have imido bonds and microphase separation, and they have been employed as scaffold materials for biomedical applications. As the featured peptide sequence of silkworm silk protein, GlyAlaGlyAla (GAGA) tetrapeptide was synthesized by using traditional liquid-phase peptide synthesis method with Boc-protected alanine and glycine as starting materials, and was transformed to its derivative with two end-amido groups. The derivative was incorporated into the backbone of the classical synthetic copolyurethane as a chain extender to form a silk-inspired polyurethane. Elemental analysis showed the nitrogen content in the silk-inspired PU was higher than that in the butanediol-extended PU but lower than the theoretical value, indicating the chain extender containing GAGA was partially incorporated into the PU chain. The results from 1 H-nuclear magnetic resonance, Fourier transform infrared spectra, Raman scattering spectra and pyrolysis-gas chromatography/mass spectrometry qualitatively identified the primary structure of the silk-inspired polyurethane. This concept and strategy may allow the fabrication of a new class of thermoplastic polyurethane elastomer to mimic the structure and properties of silk fibers if in fiber form, which combines traditional synthetic polymer chains with peptide sequences. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2023
·Vol. 15
·期 4
·944
·
IF 5
Chi Jiang,Zhaohui Fei,Yingfei Hou
A reverse osmosis (RO) membrane with a high water permeance and salt rejection is needed to reduce the energy requirement for desalination and water treatment. However, improving water permeance while maintaining a high rejection of the polyamide RO membrane remains a great challenge. Herein, we report a rigid–flexible coupling strategy to prepare a high-performance RO membrane through introducing monoamine with a flexible aliphatic ring (i.e., piperidine (PPR)) into the interfacial polymerization (IP) system of trimesoyl chloride (TMC) and m-phenylenediamine (MPD). The resulted polyamide film consists of a robust aromatic skeleton and soft aliphatic-ring side chain, where the aliphatic ring optimizes the microstructure of polyamide network at a molecular level. The obtained membranes thereby showed an enhanced water permeance of up to 2.96 L·m−2h−1bar−1, nearly a 3-fold enhancement compared to the control group, meanwhile exhibiting an ultrahigh rejection toward NaCl (99.4%), thus successfully overcoming the permeability–selectivity trade-off limit. Furthermore, the mechanism of the enhanced performance was investigated by molecular simulation. Our work provides a simple way to fabricate advanced RO membranes with outstanding performance.Keywords:reverse osmosis;interfacial polymerization;molecular structure;high permeance
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2023
·Vol. 141
·期 10
·e55051
·
IF 3
Xiaoling Da,Zhaoyi Deng,Tong Wu,Ya Cao,Ming Xiang,Feng Yang
To study the effect of molecular structure on ethylene-vinyl alcohol copolymer (EVOH) thermal stability during processing, EVOH samples with different molecular weights and comonomer distributions were prepared by solubility fractionation from two different commercial materials, and then, the structure features of samples were characterized by 1 H-NMR, viscometry, differential scanning calorimetry, and, especially, successive self-nucleation and annealing. Their thermal stabilities were further analyzed by isothermal oxygen treatment and thermogravimetry. Attenuated total internal reflectance Fourier transform infrared spectroscopy and UV were used to obverse the structural changes in samples (the formation of chromogenic groups: CO and CC ). According to the results of isothermal oxygen treatment at 200°C, at the same ethylene content, low-molecular-weight samples have worse thermal stability, which were extremely easy to yellowing and form insoluble gel. To investigate the structure differences between the low-molecular-weight samples, it was found that long vinyl alcohol segments may not worsen the thermal stability in the conditions of the same ethylene content. But samples with a uniform distribution of ethylene segments and a certain length of ethylene segments will have better thermal stability, which makes it more difficult to form carbonyl even diketene conjugation structure.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ZEITSCHRIFT FUR KRISTALLOGRAPHIE-NEW CRYSTAL STRUCTURES
·
2018
·Vol. 233
·期 3
·359-360
·
IF 0.252
Qiang Xu,Yan Ling Zhao,Xiao Fang Luo,Ming Wei Zhou,Guo qiang Li
C 28 H 22 N 2 NiO 4 , tetragonal, P 4 1 2 1 2 (no. 92), a = 10.989(4) Å, c = 18.470(2) Å, V = 2230.4(16) Å 3 , Z = 4, R gt ( F ) = 0.0571, wR ref ( F 2 ) = 0.1382, T = 293(2) K.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
FOOD CHEMISTRY
·
2019
·
IF 5.399
Mengzhen Ding,Ting Zhang,Huan Zhang,Ningping Tao,Xichang Wang,Jian Zhong
As the differences of traditional and Pickering emulsions might have resulted from stabilizer structures, this study analyzes the effects of gelatin molecular structures (uncrosslinked molecules vs. crosslinked molecules) on the preparation, long-term storage, and dilution of fish oil-loaded traditional and Pickering emulsions. Both traditional and Pickering emulsions have three types of droplets with different sizes, and all the droplet sizes were exponentially decreased with the increase of stabilizer concentration. Pickering emulsions have slightly lower droplet sizes compared with traditional emulsions. Traditional emulsions have three different emulsion forms (liquid, redispersible emulsion gel, and unredispersible emulsion gel), whereas Pickering emulsions only have the liquid form. Emulsion creaming stability was dependent on stabilizer molecular structures and stabilizer concentrations. The two emulsions have similar and good dilution stability. This work demonstrates that gelatin molecular structures affect droplet size, emulsion forms, and creaming stability, but not droplet size types and emulsion dilution stability.
研究领域:
食品科学
·
胶体化学
✓ 已验证
DOI
PubMed
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2024
·
IF 4.1
Ge Zhi-Qing,Yan Shuo,Pan Zu-Xiong,Lei Shan,Mao Xuan-Zhi,Zhao Chu,Wang Mo-Zhen,Ge Xue-Wu
The thermochromic mechanism and the structure-property regulation principle of reversible thermochromic polydiacetylene (PDA) materials have always been a challenging issue. In this work, a series of diacetylene monomers (m-PCDA) containing phenyl and amide or carboxyl groups were synthesized from 10,12-pentacosadiynoic acid (PCDA) through the esterification or amidation reactions. The effects of the number and the distribution of the functional groups in m-PCDA molecules on their solid-state polymerization capability, and the thermochromic mechanism of their corresponding polymers (m-PDA) were investigated and discussed in detail. The results show that the m-PCDA monomers containing both benzene ring and groups that can form hydrogen bonding interactions have strong intermolecular interaction, and are easy to carry out the solid phase polymerization under 254-nm UV irradiation to obtain the corresponding new thermochromic m-PDA materials. The thermochromic behavior of m-PDA depends on its melting process. The initial color-change temperature (blue to red) is determined by the onset melting temperature, and the temperature range in which reversible color recovery can be achieved by repeat heating-cooling treatment is determined by its melting range. According to the proposed thermochromic mechanism of PDA, various new PDA materials with precise thermochromic temperatures and reversible thermochromic temperature ranges can be designed and synthesized through the appropriate introduction of benzene ring and groups that can form hydrogen bonding interactions into the molecular structure of linear diacetylene monomer. This work provides a perspective to the precise molecular structure design and the property regulation of the reversible thermochromic PDA materials.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2025
·
IF 3.2
Panpan Yang,Yifei Wu,Kunxin Wang,Xiaole Zheng,Junxi Wan,Kun Wu,Jun Shi,Peiwei Hong,Li Yang
Polymers with high thermal conductivity are crucial for addressing the heat dissipation challenges associated with high-performance compact electronic devices. In this work, a series of high thermal conductivity polyesters (PEnx) were synthesized. Their molecular structure is regulated by introducing flexible chains with segments containing n methylene units between 2 and 8. The thermal diffusivity and thermal conductivity of a series of polyesters were studied in relation to their structure. As a result, the thermal diffusivity of polyesters rose from 0.173 to 0.334 mm2 s–1. PEn6 exhibits a thermal conductivity of 0.578 ± 0.0021 W/(m·K), which is 180% higher than PEn2 and three times higher than conventional thermoplastics. The enhanced thermal conductivity can be attributed to the regular molecular structure, which augments heat transfer by mitigating phonon scattering. Thus, it is possible to enhance both the heat absorption and thermal conductivity of the polymer by adjusting the number of methylene groups in the polyester. Meanwhile, the main diffraction peaks of all of the polyesters were around 20°, indicating their semicrystalline nature. Furthermore, PEn6 has excellent thermal stability with a T5% of 396.2 °C, Tmax of 431.1 °C, and residual carbon content of 6.47% at 800 °C.
研究领域:
材料科学
·
热物理学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Yijiao Xue,Tianchen Zhang,Linfeng Tian,Jiabing Feng,Fei Song,Zheng Pan,Guobo Huang,Meng Zhang,Yonghong Zhou,Pingan Song
Phosphoramides, as a kind of high-efficient fire retardants, have been designed in many structures and endowed exceptional fire retardancy to polylactide (PLA). However, due to ignorance of the structure-property correlation, the effect of phosphoramides' structure on the fire retardancy and mechanical properties of PLA is still unclear. Herein, a series of biobased phosphoramides (phosphoramide (V1), linear polyphosphoramide (V2) and hyperbranched polyphosphamide (V3)) were designed and incorporated into PLA, and the structural effect of phosphoramides on the fire-retardant and mechanical properties of PLA was deeply researched. Among three kinds of phosphoramides, the hyperbranched polyphosphoramide is more effective than the corresponding linear polyphosphoramide and phosphoramide in improving the fire-retardant and anti-dripping properties of PLA, and only linear polyphosphoramide shows a positive effect in the mechanical strength of PLA. This work provides a feasible strategy for creating mechanically robust and fire-retardant polymer composites by molecularly tailoring the structure of fire retardants and uncovering their structure-property relationship.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Processes
·
2021
·Vol. 9
·期 3
·404
·
IF 2.847
Maoyan An,Yinfei Liao,Yijun Cao,Xiaodong Hao,Longfei Ma
The mixed collector can improve low rank coal flotation efficiency, but its synergistic mechanism needs to be further explored. In this paper, oleic acid-dodecane (OA-D), oleic acid (OA), and dodecane (D) were employed to treat the low rank coal for revealing new synergistic mechanism of the mixed collector. First the surface free energy of the coal, the surface free energy of coal-water and coal-water-coal were calculated. Then wetting heat measurement, X-ray Photoelectron Spectroscopy (XPS) and FTIR were used to analyze synergistic mechanism of the mixed collector in depth. The results showed that OA-D obtained a higher combustible recovery than using OA and D, respectively. The essence of synergetic mechanism of OA-D was that they formed a relatively ordered “supramolecular structure” on the low rank coal surface, especially there were hydrophobic and van der Waals forces between the oleic acid chain and the dodecane chain that can promote the formation of a continuous collector film.Keywords:low rank coal;mixed collector;synergetic mechanism;supramolecular structure
研究领域:
矿物加工工程
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）