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According to the environmental conditions of acid rain and fog in Dazu， Chongqing， the corrosion resistance of traditional gold glue paint used for gilding of cultural relics to wet polluted atmosphere was studied by a variety of simulated accelerated aging tests and combining with analytical methods such as infrared spectroscopy， contact angle， and morphology observation.Results showed that atmospheric acid rain pollution accelerated the impact of the alternating wet and dry environment of water on gold glue paint.Additionally， light， humidity and the alternating wet and dry environment of polluted atmosphere had varying degrees of influence on gold glue paint.Among them， the alternating dry and wet environment of polluted atmosphere possessed the most serious damage to the aging resistance of gold glue paint， which eventually led to the corrosion damage of gold gule paint materials.

Waterlogged archaeological wood samples may degrade during long-term immersion in microbial-activity environments, which causes its biodegradation. Simultaneous dynamic vapor sorption (SDVS) and two-dimensional correlation infrared (2D COS-IR) spectroscopy reveal the degradation inhomogeneity of waterlogged fir wood from the Shengbeiyu shipwreck. The waterlogged and reference wood exhibit type II sorption isotherms. The equilibrium moisture contents of waterlogged archaeological fir wood from a decay region (WFD) were 22.5% higher than those of waterlogged archaeological fir wood from a sound region (WFS). WFD exhibits a higher measurable sorption hysteresis than WFS, implying greater variation in the surface moisture content in the WFD region compared to the WFS region, which may compromise the dimensional stability of the shipwreck. 2D COS-IR spectra confirmed the inhomogeneous degradation of the waterlogged wood via numerous mechanisms. The efficacy of SDVS and 2D COS-IR spectroscopy in the evaluation of the degradation state of waterlogged wood was demonstrated. This study verifies the existence of hygroscopic and chemical differences between visually similar samples from the same shipwreck. [ABSTRACT FROM AUTHOR]

Alcohols are important products in chemical industry, but separating them from their aqueous solutions is very difficult due to the hydrophilic nature of alcohols. Based on molecular dynamics simulations, we observe a striking nanoscale drying phenomenon and suggest an energy-saving and efficient approach toward alcohol/water separation by using single-walled carbon nanotubes (SWNTs). We use various common linear alcohols including C1-C6 1-alcohols and glycerol for demonstration (the phenol is also used as comparison). Our simulations show that when SWNTs are immersed in aqueous alcohols solutions, although the alcohols concentration is low (1 M), all kinds of alcohols can induce dehydration (drying) of nanotubes and accumulate inside wide [(13, 13)] and narrow [(6, 6) or (7, 7)] SWNTs. In particular, most kinds of alcohols inside the narrow SWNTs form nearly uniform 1D molecular wires. Detailed energetic analyses reveal that the preferential adsorption of alcohols over water inside nanotubes is attributed to the stronger dispersion interactions of alcohols with SWNTs than water. Interestingly, we find that for the wide SWNT, the selectivity for 1-alcohols increases with the number of alcohol's carbon atoms (Ncarbon) and exhibits an exponential law with respect to Ncarbon for C1-C5 1-alcohols; for narrow SWNTs, the selectivity for 1-alcohols is very high for methanol, ethanol, and propanol, and reaches a maximum when Ncarbon = 3. The underlying physical mechanisms and the implications of these observations for alcohol/water separation are discussed. Our findings provide the possibility for efficient dehydration of aqueous alcohols (and other hydrophilic organic molecules) by using SWNT bundles/membranes. [ABSTRACT FROM AUTHOR]

Understanding the interaction between carbon nanotubes (CNTs) and biomolecules is essential to the CNT-based nanotechnology and biotechnology. Some recent experiments have suggested that the π-π stacking interactions between protein's aromatic residues and CNTs might play a key role in their binding, which raises interest in large scale modeling of protein-CNT complexes and associated π-π interactions at atomic detail. However, there is concern on the accuracy of classical fixed-charge molecular force fields due to their classical treatments and lack of polarizability. Here, we study the binding of three aromatic residue analogues (mimicking phenylalanine, tyrosine, and tryptophan) and benzene to a single-walled CNT, and compare the molecular mechanical (MM) calculations using three popular fixed-charge force fields (OPLSAA, AMBER, and CHARMM), with quantum mechanical (QM) calculations using the density-functional tight-binding method with the inclusion of dispersion correction (DFTB-D). Two typical configurations commonly found in π-π interactions are used, one with the aromatic rings parallel to the CNT surface (flat), and the other perpendicular (edge). Our calculations reveal that compared to the QM results the MM approaches can appropriately reproduce the strength of π-π interactions for both configurations, and more importantly, the energy difference between them, indicating that the various contributions to π-π interactions have been implicitly included in the van der Waals parameters of the standard MM force fields. Meanwhile, these MM models are less accurate in predicting the exact structural binding patterns (matching surface), meaning there are still rooms to be improved. In addition, we have provided a comprehensive and reliable QM picture for the π-π interactions of aromatic molecules with CNTs in gas phase, which might be used as a benchmark for future force field developments. [ABSTRACT FROM AUTHOR]

Huaguangjiao І is a Chinese ancient wooden shipwreck of South Song Dyansty (1127–1279 AD). Wood samples from Huaguangjiao І were analyzed in order to evaluate the preservation state of the waterlogged wood. Samples were studied from the anatomical, physical and chemical point of view. Thin slides of cross and longitudinal sections from samples were observed by optical microscope, micromorphological decay was classified into class 3 or class 4 according to the anatomical characters. Water content and basic density were measured. Maximum water content (MWC) of the wood samples is between 300% and 600%, residual basic density is about 50%. The proportion of the α-cellulose decreased to 25% of the normal value, and the content of the ash increased greatly. These results indicate the degradation of the wood is very high. In addition, there is a plenty of inorganic deposit in the wood structure. The inorganic compounds deposited in wood samples were analyzed by XRD and ICP qualitatively and quantitatively. The morphology and composition of the inorganic deposit was characterized through SEM-EDS, the majority were iron sulfide, including pyrite and marcasite (FeS 2 ), and fluorite (CaF 2 ). [ABSTRACT FROM AUTHOR]