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1.
丝织品是由丝蛋白质组成,高温、高湿及污染物等因素会使其结构发生变化。为了科学地评估博物馆中污染气体对丝织品结构的影响,采取人工模拟实验制备二氧化氮、二氧化硫、乙酸和氨气常见博物馆污染气体环境,利用傅里叶红外光谱(FTIR)从丝蛋白质肽链结构、二级结构等方面探讨4种污染气体对丝织品蛋白质结构的影响。实验结果表明,二氧化氮老化30 h后样品的红外光谱在1 382 cm-1波数附近出现甲基对称变角振动吸收峰,而其他气体老化50 d的丝织品仍未产生甲基对称变角振动,说明二氧化氮对丝织品破坏最严重。所有污染气体老化后,样品的红外光谱在975和999 cm-1丝蛋白-Gly-Ala-和-Gly-Gly-肽链(一级)结构特征吸收峰处均有不同程度减弱,但碱性气体氨气较酸性气体减弱更明显。傅里叶红外光谱技术结合酰胺Ⅲ带(1 330~1 200 cm-1)去卷积和高斯拟合法研究表明,50 d氨老化后仅引起丝蛋白质非结晶区的轻微变化,α-螺旋、无规卷曲、β-折叠含量变化幅度较小,丝蛋白二级结构变化较小。相比而言,酸性气体对丝蛋白二级结构影响更加显著,出现β-折叠相对含量大幅降低、无规卷曲相对含量明显增加,其结晶区遭受严重破坏。在4种气体中,二氧化氮对丝织品二级结构影响最显著,老化30 h后β-折叠相对含量由原始值30.36%降低至18.12%,约降低40%。相应的二氧化氮对丝织品强度破坏最严重,在β-折叠含量降低的同时,材料的力学强度出现了显著降低。利用波数在1 700和1 640 cm-1红外光谱吸收峰的比值(A1 700/1 640)和波数在1 620和1 514 cm-1红外光谱吸收峰的比值(A1 620/1 514)判断样品的老化方式,实验结果表明二氧化氮、二氧化硫、氨气老化样品的方式主要为氧化老化,而乙酸老化的样品则发生氧化老化和水解老化两种老化方式。随着老化时间的延长,4种气体中二氧化氮老化样品的A1 620/1 514比值增加最多、氧化最严重。推断与二氧化氮的强氧化性有关,也与二氧化氮使丝织品产生显著的甲基对称变角振动有关。建议博物馆应严格监测和控制二氧化氮气体浓度。该研究为制定合理的丝织品文物存放环境提供科学依据,对丝织品文物的保护具有重要意义。 相似文献
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The Effect of the Spacer of Bis(biurea) Ligands on the Structure of A2L3‐type (A=anion) Phosphate Complexes 下载免费PDF全文
Prof. Biao Wu Dr. Shaoguang Li Prof. Yibo Lei Prof. Huaiming Hu Dr. Nader de Sousa Amadeu Prof. Dr. Christoph Janiak Dr. Jennifer S. Mathieson Dr. De‐Liang Long Prof. Leroy Cronin Prof. Xiao‐Juan Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2588-2593
By tuning the length and rigidity of the spacer of bis(biurea) ligands L, three structural motifs of the A2L3 complexes (A represents anion, here orthophosphate PO43?), namely helicate, mesocate, and mono‐bridged motif, have been assembled by coordination of the ligand to phosphate anion. Crystal structure analysis indicated that in the three complexes, each of the phosphate ions is coordinated by twelve hydrogen bonds from six surrounding urea groups. The anion coordination properties in solution have also been studied. The results further demonstrate the coordination behavior of phosphate ion, which shows strong tendency for coordination saturation and geometrical preference, thus allowing for the assembly of novel anion coordination‐based structures as in transition‐metal complexes. 相似文献
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Microchimica Acta - Inspired by water-soluble sacrificial template strategies, we have synthesized crystals of silver chloride (AgCl) consisting of a well-defined cubic exterior and a hollow... 相似文献
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Cai Meng Zhou Tian-Hong Li Ya-Nan Lv Lei Xu Kang-Zhen 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2237-2245
Journal of Thermal Analysis and Calorimetry - Two new interesting compounds, ethanedial-1,2-bis-(2-(1-amino-2,2-dinitroethenyl))hydrazone (EDNH) and 3-dinitromethyl-1,2,4-triazine (DNTA), were... 相似文献
7.
New pyridinium-functionalized metalloporphyrins MEtPpBr4 (M = Zn2+, Co2+, Ni2+, Cu2+; EtPp = 5, 10, 15, 20-tetra(4-(3-(N-ethyl-4-pyridyl)pyrazolyl)phenyl)porphyrin) were synthesized as bifunctional catalysts for the cycloaddition reactions of epoxides and CO2. The effects of catalyst loading, CO2 pressure, reaction temperature and time on catalytic activity were investigated. ZnEtPpBr4 ( 1 ) and CoEtPpBr4 ( 2 ) exhibited efficient activities in the cycloaddition reactions of various epoxides with CO2 as at 120 °C under 2 MPa of CO2 pressure without solvent. Most of corresponding cyclic carbonates could be obtained in almost quantitative yields and > 99.9% selectivity with molar ratio of epoxide/catalyst 2222 after 8 hr of reaction. 相似文献
8.
Dr. Yong-Zhi Li Gang-Ding Wang Hong-Yun Yang Prof. Lei Hou Prof. Yao-Yu Wang Prof. Zhonghua Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16402-16407
To develop efficient adsorbent materials for storage and separation of C2H2, an unprecedented supercage MOF, [Me2NH2]⋅[Zn3(ALP)(TDC)2.5]⋅3.5DMF⋅2 H2O ( 1 ) was constructed through medicinal molecule allopurinol (ALP) and S-containing 2,5-thiophenedicarboxylic acid (H2TDC). 1 contains a novel linear trinuclear cluster that is composed by ALP and carboxylates and forms a final uncommon 5-connected yfy topological framework. The framework possesses three types of interlinked cages decorated by rich functional sites, and reveals not only high adsorption capacity for C2H2 but also excellent selective separation for C2H2/CO2 and C2H2/CH4 at 298 K. Dynamic breakthrough experiments on C2H2/CO2 (1:1) mixture and C2H2/CH4 (1:1) mixture also demonstrated the potential of the material to separate C2H2 from CO2 or CH4 mixtures. Molecular simulations were also studied to identify the different CO2- and C2H2- binding sites in 1 , such as carboxylate groups, S atoms and carbonyl groups. 相似文献
9.
《中国化学快报》2023,34(11):108617
Fluorescent materials that respond to multiple stimuli have broad applications ranging from sensing and bioimaging to information encryption. Herein, we report the design and synthesis of a single-fluorophore-based amphiphile DCSO, which shows temperature-, solvent-, humidity-, and radiation-dependent fluorescence. DCSO consists of a dicyanostilbene (DCS) group as a rigid hydrophobic core with oligo(ethylene glycol) (OEG) chains at both ends as a flexible hydrophilic periphery. The DCS group acts as a highly efficient fluorophore, while the OEG chain endows the molecule with thermo-responsiveness. Fluorescent colors can vary from blue to green to yellow in response to external stimuli. On the basis of light radiation, we demonstrate that this system can be applied to time-dependent information encryption, in which the correct information can only be read at a specific time under irradiation. This work further demonstrates the usefulness and application of single-fluorophore-based luminescent materials with multiple stimuli-responsive functions. 相似文献
10.
Guangyue Xu Xiang Zhang Zhuoya Dong Wanying Liang Tianci Xiao Huiyong Chen Yanhang Ma Yang Pan Yao Fu 《Angewandte Chemie (International ed. in English)》2023,62(44):e202305915
Non-oxidative dehydrogenation of propane is a highly efficient approach for industrial preparation of propene that is commonly catalyzed by noble Pt or toxic Cr catalysts and suffers from coking. In this work, ferric catalyst confined in a zeolite framework was synthesized by a hydrothermal procedure. The isolated Fe in the framework formed distorted tetrahedra, which were beneficial for the selective dehydrogenation of propane and reached over 95 % propene selectivity and over 99 % total olefins selectivity. This catalyst had a silanol-free structure and was oxygen tolerant, hydrothermally stable, and coke free, with a deactivation constant of 0.01 h−1. This study provided guidance for the synthesis of structural heteroatomic zeolite and efficient propane non-oxidative dehydrogenation over early transition metals. 相似文献