Space phase matching and self-frequency-doubling red laser in Nd:GdCOB crystal

By using the calculation theory of the phase-matching direction and effective nonlinear coefficient of frequency doubling in biaxial crystal, we calculate the effective nonlinear coefficients at different frequency-doubling phase-matching directions of the three main fluorescent lines (936, 1060, 1331 nm) of Nd:GdCOB crystal. The space distribution curves of effective nonlinear coefficient are drawn. Two crystal specimens are cut at the optimal type I phase matching angles: for specimen 1, θ=65°, Φ=34.6° (the first octant); for specimen 2, θ=66.5°, Φ=145.5° (the second octant). When pumped by Datachroom-5000 pulsed dye laser, the output self-frequency-doubling red laser in specimen 2 is 0.62 mJ, and the corresponding conversion efficiency is 2.5%. Under the same pumping condition, the output red laser of specimen 1 is much smaller than that of specimen 2, which is well in agreement with the theoretical calculation.     

Protein-induced leakage and membrane destabilization of phosphatidylcholine and phosphatidylserine liposomes

By using spectroscopic and colloidal chemistry methods we studied the interactions of globular proteins with phospholipid membranes in relation to protein-promoted membrane fusion. We considered the effect of protein sorption on the destabilization of phosphatidylcholine and phosphatidylserine liposome membranes. Experimentally, we injected the proteins into fluorophore-quencher embedded liposome dispersions and recorded the leakage of fluorophore-quencher from the liposomes' inner compartment, which is due to the protein-induced destabilization of the phospholipid membranes. The release of fluorophore-quencher strongly depends on the protein concentration. The existence of monovalent and polyvalent cations also influences the protein-induced membrane destabilization by affecting the hydrophobic and electrostatic interactions.     

Pump angle and position effects on laser emission from quasicrystal microcavity by nine-beam interference based on holographic polymer-dispersed liquid crystals

We demonstrate pump angle and position effects on lasing from all organic quasicrystal fabricated by nine-beam interference. The output wavelengths of lasing are experimentally investigated with different pump angles. The underlying mechanism is explained by the photonic band edge simulated by finite-difference time-domain method. Additionally, the position effect on lasing is also demonstrated, and the emission characteristics of lasing are studied. The mirrorless laser is featured by low cost, and simple fabrication, which enables quasicrystal based on holographic polymer-dispersed liquid crystal an all organic miniature lasing devices.     

高分子染料的进展

高分子染料是一类本身固有颜色的高分子化合物，它兼有染料和高聚物的双重性质。因此既可作为色料也可作为高聚物而应用于许多领域。本文较详细阐述了聚合染料的种类，合成方法及应用情况。     

What is the basic chromophore of a dye?

Taking the 4,5-diphenyl-substituted 2-dimethylamino-3-azacyclopentadienone (4) as an example its colour has been discussed in relation to different basic chromophores (parent chromophores). The parent chromophore can be defined either as the structure which has nearly the same absorption wavelength as the dye under consideration or as the substructure which is electronically most closely related to the dye. In the case of4 both considerations lead to different results. Based on the correlation diagram between the electronic states involved in the electronic excitation the long-wavelength absorption of4 is better understood in terms of the merocyanine parent chromophore than in terms of a betainic substructure, which should have the same colour as4 and is the parent chromophore according toKlessinger. This conclusion is drawn fromPPP configuration analysis of the wavefunctions of4 relative to different molecular substructures. The molecular geometry predicted by the geometry-optimized MINDO/3 and QCFF/Pi calculations provided additional arguments in favour of the cyclomerocyanine structure of4. In respect to the colour4 belongs to a new series of cyclic-conjugated chromophoric systems.     

Synthesis of NiO coated chitosan-cenosphere buoyant composite for enhanced adsorptive removal of methylene blue

The objective of the present study is to utilize fly ash cenosphere to remove methylene blue (MB) from the water streams. Nickel oxide is a typical semiconductor used as proficient adsorbent material for degradation of dye with environment friendly applications due to its excellent chemical stability and high catalytic activity. The chitosan cenosphere buoyant composite coated with NiO was synthesized with hydrothermal grafting reaction using silane coupling agent and epichlorohydrin as a cross-linking reagent. The batch adsorption experiments were carried out with a cationic dye, methylene blue as a representative organic pollutant to investigate the adsorptive capabilities of the composite as adsorbent. The influence of pH (2-12), initial concentration of dye (50–200 mg/L), temperature (37–47 °C) and contact time (0–24 h) were taken as parameters in the study. On the relative elimination of MB, the effect of time and temperature were investigated. The adsorption kinetics for MB was correlated and found to observe the pseudo-second order kinetic model, whereas the equilibrium adsorption isotherm follows the Langmuir model (R² > 0.99). The results indicate that the floating fly ash cenosphere coated with NiO proved to be more responsive for enhanced degradation of methylene blue.     

A facile green approach to the synthesis of Bi2WO6@V2O5 heterostructure and their photocatalytic activity evaluation under visible light irradiation for RhB dye removal

Bismuth tungsten oxide and vanadium pentoxide (Bi₂WO₆/V₂O₅) heterostructures are produced by a green synthesis approach using Azadirachta indica extract for photocatalytic performance. The hydrothermal method at temperatures between 120 °C and 140 °C is used to synthesize Bi₂WO₆. Bi₂WO₆ and V₂O₅ phases are formed in pure orthorhombic wells according to the XRD pattern. The SEM displays V₂O₅ nanorods, Bi₂WO₆ hierarchical microspheres that resemble flowers at 120 °C, and particles with a particle-like character at 140 °C. In V₂O₅, the asymmetric stretching vibrations of the triplely coordinated oxygen (chain oxygen) bonds and the vibration of the doubly coordinated oxygen (bridge oxygen) bonds are responsible for a peak at 611 cm^?1. In FTIR spectra between 600 and 1600 cm^?1, the major absorption bands in Bi₂WO₆ are attributed to the W-O stretching, Bi-O stretching, and W-O-W bridging stretching modes. Bi₂WO₆@V₂O₅ at 120 °C has the lowest bandgap energy (2.32 eV) and optical electronegativity (0.62), as well as the highest refractive index (2.57), extinction coefficient (2.21), and dielectric constant (ε_r = 0.72 and ε_i = 11.4) among all samples, making it a suitable material for photocatalysis. Rhodamine blue (RhB) dye degradation is used to measure the photocatalytic activity (PCA) of certain materials. The results showed that heterostructure V₂O₅@Bi₂WO₆ synthesized at 120 °C is more attractive among all samples due to high degradation of RhB dye under sunlight irradiation in 90 min.     

Achiral Dichroic Dyes-mediated Circularly Polarized Emission Regulated by Orientational Order Parameter through Cholesteric Liquid Crystals

It is noteworthy that cholesteric liquid crystal (CLC) platforms have been witnessed in high-performance circularly polarized luminescence (CPL) behaviors through the highly organized chiral co-assembled arrangement of achiral dyes. However, most CPL-active design strategies are closely relative to the helix co-assembly structure of CLC rather than achiral dyes. Herein, we developed an intriguing regulation strategy for CPL-active CLC materials. They were regulated using the orientational order parameter (S_F) of achiral dichroic dyes as an incisive probe for the order arrangement degree of achiral dyes in CLC media. The I-shaped phenothiazine derivative PHECN dye (S_F=0.30) emitted a strong CPL signal (|g_lum|=0.47). In contrast, the T-shaped derivative (PHEBen) dye (S_F=0.09) showed a weak circular polarization level (|g_lum|=0.07) at similar CLC textures. Most interestingly, this kind of dichroic PHECN dye with a higher S_F could greatly improve the contrast ratio of CPL (Δg_lum=0.47) and emission intensity (ΔFL=46.0 %) at direct-current electric field compared with the T-shaped PHEBen (Δg_lum=0.07 and ΔFL=1.0 %) in CLC. This work demonstrates that an induced CPL emission can be mediated using achiral dichroic dye, which will open a new avenue for developing excellent CPL-active display materials.     

基于泡沫铜的多孔碳均匀负载Cu3P纳米颗粒的制备及其光催化降解染料性能北大核心CSCD

为了开发活性高、易回收的光催化剂,采用多步热解法制备了基于泡沫铜的多孔碳均匀负载Cu_(3)P纳米颗粒。在泡沫铜(FC)基底原位生长铜基金属-有机框架晶态材料(Cu-MOF),通过热解处理使得泡沫铜表面覆盖了均匀负载于碳材料的Cu_(2)O/Cu纳米颗粒(Cu_(2)O/Cu@NPC@FC-400)。对该材料进行磷化处理得到目标光催化剂Cu_(3)P@NPC@FC-400。利用X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)、紫外-可见漫散射光谱(UV-Vis DRS)、X射线光电子能谱(XPS)和扫描电子显微镜(SEM)等表征材料的组成和形貌。以罗丹明B(Rh B)溶液作为模拟废水,探究其光催化性能及机理。结果发现,Cu_(3)P@NPC@FC-400材料对罗丹明B染料具有良好的光催化性能,在3 h内染料去除率可达94%。该材料便于回收,循环利用10次后,光催化活性保持不变。此外,该材料对于含有7种染料的复杂体系也具有优异的光降解性能。该催化剂具有稳定性高、回收简便的优势,可用于处理含有多种染料的废水。     

三甲川菁染料敏化TiO2纳米结构电极的光电化学

研究了三甲川菁染料敏化ＴｉＯ２ 纳米结构电极的光电化学行为．结果表明,使用该染料敏化可显著提高ＴｉＯ２ 纳米结构电极的光电流,使电极的吸收波长红移至可见光区,光电转换效率得到明显改善,ＩＰＣＥ值最高可达１２－１ ％ ．