Proposed light sources for illuminating in Xuan paper and silk artwork with organic and inorganic pigments by evaluating color shifts in museum

Artworks based on Xuan paper or silk and painted by organic or inorganic pigments are highly responsive to light due to their materials and manufacturing technologies. They belong to the highest level of light responsive exhibits stipulated by International Commission on Illumination (CIE) and are vulnerable to fading and discoloration caused by radiation from light sources. The choice of light sources is the key of protection for artworks. It is indispensible and urgent to choose the lowest damage light sources according to the material characteristics of artworks. In this article, long-term irradiation of typical light sources on various substrates and pigments was used as experimental method, and CIE DE2000 color difference formula was used as the evaluation index. The laws of the influence of different light sources on the color change of various materials were obtained, and the relative damage coefficients of light sources were calculated. Finally, eight kinds of light sources suitable for illuminating responsive artworks with typical material combinations were proposed. However, there are some limitations in the study, because the ancient Chinese Xuan paper and silk used as experimental objects in the experiment are yellowish. Thus, the models derived in this article are not suitable for choosing reasonable display light sources for other works of art. However, suitable light sources for different materials could be obtained by the calculation method used in this article.     

Photocatalytic degradation and heat reflectance recovery of waterborne acrylic polymer/ZnO nanocomposite coating

This work aims to clarify the photocatalytic degradation mechanism and heat reflectance recovery performance of waterborne acrylic polymer/ZnO nanocomposite coating. To fabricate the nanocomposite coating, ZnO nanoparticles (nano-ZnO) were dispersed into acrylic polymer matrix at the various concentrations from 1 to 6% (by total weight of resin solids). The photocatalytic degradation of nanocomposite coating under ultraviolet (UV) light irradiation has been investigated by monitoring its weight loss and chemical/microstructural/morphological changes. As the topcoat layer, its heat reflectance recovery has been evaluated under UV/condensation exposure by using an artificial dirty mixture of 85 wt% nanoclay, 10 wt% silica particles (1–5 μm), 1 wt% carbon black, and 2 wt% engine oil. After 108-cycle UV/condensation exposure, infrared spectra and weight loss analysis indicated that the maximal degradation for nanocomposite coating is observed at 1 wt% nano-ZnO. On the other hand, after 96 hr of UV light exposure, the nanocomposite coating with1 wt% nano-ZnO could restore effectively the reflective index of solar-heat reflectance coating (from 58.45 to 80.78%). Finally, the photodegradation mechanism of this waterborne acrylic polymer coating has been proposed as the UV-induced formation of CC CO conjugated double bonds. As a result, its self-cleaning phenomenon can be achieved as the recovery of heat reflectance.     

Improved stability of volume resistivity in carbon black/ethylene-vinyl acetate copolymer composites by employing multi-walled carbon nanotubes as second filler

Semiconductive polymer shielding layers of power cable require stable volume resistivity to protect the insulation layer from stress enhancements when carbon black (CB)/polymer composite undergoes thermal cycles. For the CB-filled polymer composites, CB would often re-aggregate when temperature is close to the melting point of polymer matrix, so that the conductive network would be destroyed. Re-distribution of CB and re-formation of conductive CB network under thermal cycles might be the main reason for the instability of volume resistivity. In this work, the re-aggregation of CB in the CB/polymer composites was disclosed. Besides, a small amount of multi-walled carbon nanotubes (MWNTs) was employed as cofiller with CB to improve the stability of volume resistivity of the polymer composites under thermal cycles. The total weight fraction of conductive fillers (CB or CB cofilled with MWNTs) was set as 35 wt%. Compared with the polymer composites loaded with CB solely, the volume resistivity of the composites filled with CB-MWNTs was much more stable with changing temperature. This can be attributed to the enhancement of conductive networks when the MWNTs are employed as second conductive filler.     

带式输送机的技术现状及发展趋势

介绍国内外带式输送机的发展现状,并对平面转弯带式输送机、圆管带式输送机和气垫带式输送机的工作原理及特点进行概述。对比分析国内外带式输送机在技术参数和控制系统上的差距,指出未来输送机应向大型化、宽范围、个性化、节能和低污染等方面发展。     

中药肾脏毒性与四气、五味及归经相关性研究

研究中药肾脏毒性与四气、五味及归经的关系。以专著和文献中报道的肾脏毒性中药及一般中药为研究对象,以《中药大辞典》记载的药性理论为主要依据,用χ~2检验统计分析肾脏毒性中药的四气、五味及归经分布规律,并分析其相关性。结果显示肾脏毒性中药四气顺序依次为:温性、寒性热、凉、平性,一般中药四气顺序依次为:热性、凉性温性、寒性平性。肾脏毒性中药五味分布规律顺序依次为:苦味、辛味甘味酸味、咸味,一般中药五味分布规律顺序依次为:苦味、甘味辛味酸、咸味。肾脏毒性中药归经顺序依次为:肝经肺、肾、大肠、心、脾、胃经三焦、膀胱、胆、小肠、心包经,一般中药归经顺序依次为:肝经肺、肾、心、脾、胃经大肠经膀胱经胆、小肠、三焦、心包经。结果表明肾脏毒性中药及一般中药在四气、五味及归经方面都有明显的差别。肾脏毒性中药与一般中药之间的四气、五味及归经分布也存在明显的差别。     

Deformation and Fracture of β‐Silicon Nitride Micropillars

Room‐temperature deformation and fracture behaviors under microcompression of single crystal β‐silicon nitride (Si₃N₄) micropillars were investigated. Pillars were fabricated by focused ion beam (FIB) in large Si₃N₄ grains, located close to the basal and prismatic orientations, selected by electron backscatter diffraction (EBSD). The micromechanical test and the damage characterization were performed by nanoindentation and scanning electron microscopy (SEM), respectively. The elastic, plastic, and fracture properties, such as Young's modulus, yield stress, and rupture stress are considerably influenced by the pillar orientation. The activation of the type slip system was identified in case of basal oriented micropillars.     

Effect of the compatibility on dielectric performance and breakdown strength of poly(vinylidene fluoride)/low‐density polyethylene blends

Immiscible polymer blends with high dielectric constant (ε) and improved breakdown strength (E_b) performance were obtained by composing poly(vinylidene fluoride) (PVDF) with low‐density polyethylene (LDPE) or the LDPE grafted with maleic anhydride (LDPE‐g‐MAH) through melt‐blending way. The dielectric properties of these blends were emphasized for considering the compatibility effect on the energy storage application. Interface morphology, co‐continuity behavior, and grafted ratio were simultaneously investigated to detect the compatibility enhancement after introducing MAH. Results showed that the MAH positively improved the dielectric properties. Both the measured E_b of PVDF/LDPE and PVDF/LDPE‐g‐MAH blends showed a minimum value at v^PVDF = 50 vol % because of the worst compatibility; meanwhile, higher E_b of PVDF/LDPE‐g‐MAH than that of PVDF/LDPE blend was observed owing to the better compatibility. For considering the effect interface morphology on the dielectric performance, layer‐structure films composing with pure PVDF and LDPE layers were further constructed and studied. It was revealed that the layered structure could be treated as a helpful way to improve ε and E_b for immiscible polymer blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42507.     

Reduced sedimentation of barium titanate nanoparticles in poly(vinylidene fluoride) films during solution casting by surface modification

Reduced sedimentation of barium titanate (BaTiO₃, BT) nanoparticles during solution casting to prepare the BT/poly(vinylidene fluoride) (PVDF) films is systematically investigated by surface modification of the BT nanoparticles. The surface of BT nanoparticles is hydroxylated by hydrogen peroxide (H₂O₂) or aminated by γ‐aminopropyl triethoxysilane (γ‐APS). It is found that the compatibility between the fillers and polymer matrix is remarkably improved by such surface treatments. As a result, the agglomeration and sedimentation of BT nanoparticles in the BT/PVDF composite films are significantly reduced, which is supported by morphology observation. Better dielectric properties such as higher dielectric constant, higher breakdown strength, and lower dielectric loss are also obtained for the composite films with surface‐modified fillers than those with raw fillers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42662.     

Catalytic Upgrading of Phenolic Oil by Etherification with Methanol

Catalytic etherification of phenolic oil with methanol was investigated to decrease the polarity and acidity of the product oil. The catalyst KH₂PO₄/activated alumina (AA) provided the best performance due to its excellent dehydration and anti‐coking property. When catalyzed by KH₂PO₄‐AA, the content of aryl ethers increased with rising temperature during the early stage but decreased at 500 °C. Alkoxy phenols had an inhibiting effect on etherification of alkyl phenols due to adsorption competition. Aryl ethers were mostly generated from alkyl phenols, while alkoxy phenols also contributed by simultaneous conversion to dialkoxybenzenes and diphenols, with a higher selectivity to diphenols. This explained the reduced alkoxy phenols and more generated alkyl phenols and aryl ethers at 350 °C.     

Discovery of a Short‐Chain Dehydrogenase from Catharanthus roseus that Produces a New Monoterpene Indole Alkaloid

Plant monoterpene indole alkaloids, a large class of natural products, derive from the biosynthetic intermediate strictosidine aglycone. Strictosidine aglycone, which can exist as a variety of isomers, can be reduced to form numerous different structures. We have discovered a short‐chain alcohol dehydrogenase (SDR) from plant producers of monoterpene indole alkaloids (Catharanthus roseus and Rauvolfia serpentina) that reduce strictosidine aglycone and produce an alkaloid that does not correspond to any previously reported compound. Here we report the structural characterization of this product, which we have named vitrosamine, as well as the crystal structure of the SDR. This discovery highlights the structural versatility of the strictosidine aglycone biosynthetic intermediate and expands the range of enzymatic reactions that SDRs can catalyse. This discovery further highlights how a sequence‐based gene mining discovery approach in plants can reveal cryptic chemistry that would not be uncovered by classical natural product chemistry approaches.