分光计调整方法的改进及白光色散研究

普通物理实验中使用分光计观察白光散射,测量三棱镜顶角,最小偏向角等。但在测量前需借助三棱镜调整分光计,有人通过理论分析发现传统的调节方法存在误调和误差,并提出了改进的实验调整方法。本文我们通过实验来验证该方法是否可行,并在实验中发现了其它的问题。     

Low temperature synthesis and luminescence investigations of YAG:Ce,Eu nanocomposite powder for warm white light-emitting diode

The preparation of the cerium and europium co-doped YAG materials as well as the study for their synthesis and emitting mechanism of the energy transfer between Ce³⁺ and Eu³⁺ were investigated in the present study. YAG:Ce³⁺, Eu³⁺ powders were synthesized using a high-energy ball milling method in different sintering temperature and atmosphere: air and H₂/N₂. The effects of the synthesis procedure on the crystallinity, morphology, structure, and luminescence spectra were examined by X-ray diffraction, field emission-scanning electron microscopy, and photoluminescence spectroscopy. The europium co-doped YAG:Ce³⁺ phosphors is improved the chromaticity coordinates.     

Reversible,Photoinduced Activation of P4 by Low‐Coordinate Main Group Compounds

Two unique systems based on low‐coordinate main group elements that activate P₄ are shown to quantitatively release the phosphorus cage upon short exposure to UV light. This reactivity marks the first reversible reactivity of P₄, and the germanium system can be cycled 5 times without appreciable loss in activity. Theoretical calculations reveal that the LUMO is antibonding with respect to the main group element–phosphorus bonds and bonding with respect to reforming the P₄ tetrahedron, providing a rationale for this unprecedented activity, and suggesting that the process is tunable based on the substituents.     

Bright White‐Light Emission from a Single Organic Compound in the Solid State

White‐light‐emitting materials and devices have attracted enormous interest because of their great potential for various lighting applications. We herein describe the light‐emitting properties of a series of new difunctional organic molecules of remarkably simple structure consisting of two terminal 4‐pyridone push–pull subunits separated by a polymethylene chain. They were found to emit almost “pure” white light as a single organic compound in the solid state, as well as when incorporated in a polymer film. To the best of our knowledge, they are the simplest white‐light‐emitting organic molecules reported to date.     

HPLC法同时测定黄酒中4种非法食品添加剂

建立高效液相色谱同时测定黄酒中安赛蜜、苯甲酸、山梨酸和糖精钠4种非法食品添加剂的方法。黄酒中的待测物质经提取后,采用C18柱分离,以甲醇–乙酸铵溶液为流动相进行洗脱,在波长230 nm处用高效液相色谱–二极管阵列检测器进行测定。安赛蜜、苯甲酸、山梨酸和糖精钠的质量浓度在0.5～200.0μg/mL范围内与其色谱峰面积的线性关系良好(r0.999 7),检出限为0.29～0.74μg/L。在0.5,1.0,2.5,5.0,7.5 mg添加水平时的平均回收率在95.6%～104.0%范围内,测定结果的相对标准偏差为0.3%～1.5%(n=6)。该方法操作简便,分离效果好,灵敏度高,结果稳定可靠,适合于黄酒中安赛蜜、苯甲酸、山梨酸和糖精钠的同时测定。     

离子液体为背景电解质的毛细管电泳-间接紫外检测法同时测定葡萄酒中无机阴离子和阳离子

以离子液体1-乙基-3-甲基咪唑对甲苯磺酸盐（[EMIm]TS）为背景电解质,采用双端进样方式,实现了毛细管电泳-间接紫外检测法同时分析测定葡萄酒中无机阳离子（K⁺、Ca²⁺、Na⁺、Mg²⁺和Li⁺）和阴离子（Cl^-、SO₄^2-和ClO₃^-）。[EMIm]TS作为电泳缓冲溶液的同时,其阳离子和阴离子分别作为样品中阳离子和阴离子组分的间接紫外检测的背景电解质。在最佳分析条件下,可在6.5 min内完成8种无机离子的同时分离检测,其线性范围为0.005~0.7 g/L,相关系数为0.963~0.995,检出限（S/N=3）为1.2~12.5 mg/L。该方法成功测定了3种不同品牌的市售葡萄酒中8种无机离子。在3个加标水平下,8种无机离子的回收率为90.1%~110.5%,相对标准偏差（RSD）≤ 4.8%。结果表明,该方法可应用于葡萄酒中无机阴、阳离子的同时分离检测,且方法简单、快速且结果可靠。     

Terroir Effect on the Phenolic Composition and Chromatic Characteristics of Mencía/Jaen Monovarietal Wines: Bierzo D.O. (Spain) and Dão D.O. (Portugal)

‘Mencía’/‘Jaen’ it’s an important red grape variety, exclusive of the Iberian Peninsula, used in wine production namely in Bierzo D.O. and Dão D.O., respectively. This work evaluates the effect of the two different “terroirs” on the phenolic composition and chromatic characteristics of ‘Mencía’/‘Jaen’ monovarietal wines produced at an industrial scale in the same vintage. Using Principal Component Analysis (PCA), Partial Least Squares-Discrimination Analysis (PLS-DA), and Orthogonal PLS-DA (OPLS-DA) it was found that peonidin-3-coumaroylglucoside, petunidin-3-glucoside, malvidin-3-coumaroylglucoside, peonidin-3-glucoside, malvidin-3-acetylglucoside, malvidin-3-glucoside, and ferulic acid were the phenolic compounds with the highest differences between the two regions. PLS regression allowed to correlate the differences in lightness (L*) and redness (a*) of wines from ‘Jaen’ and ‘Mencía’ to differences in colored anthocyanins, polymeric pigments, total pigments, total anthocyanins, cyanidin-3-acetylglucoside, delphinidin-3-acetylglucoside, delphinidin-3-glucoside, peonidin-3-coumaroylglucoside, petunidin-3-glucoside and malvidin-3-glucoside in wines, and the colorless ferulic, caffeic, and coutaric acids, and ethyl caffeate. The wines a* values were more affected by colored anthocyanins, ferulic acid, total anthocyanins, delphinidin-3-acetylglucoside, delphinidin-3-glucoside and petunidin-3-acetylglucoside, and catechin. The positive influence of ferulic acid in the a* values and ferulic, caffeic, coutaric acids, and ethyl caffeate on the L* values can be due to the co-pigmentation phenomena. The higher dryness and lower temperatures during the September nights in this vintage might explain the differences observed in the anthocyanin content and chromatic characteristics of the wines.     

The Optimization of a Novel Hydrogel—Egg White-Alginate for 2.5D Tissue Engineering of Salivary Spheroid-Like Structure

Hydrogels have been used for a variety of biomedical applications; in tissue engineering, they are commonly used as scaffolds to cultivate cells in a three-dimensional (3D) environment allowing the formation of organoids or cellular spheroids. Egg white-alginate (EWA) is a novel hydrogel which combines the advantages of both egg white and alginate; the egg white material provides extracellular matrix (ECM)-like proteins that can mimic the ECM microenvironment, while alginate can be tuned mechanically through its ionic crosslinking property to modify the scaffold’s porosity, strength, and stiffness. In this study, a frozen calcium chloride (CaCl₂) disk technique to homogenously crosslink alginate and egg white hydrogel is presented for 2.5D culture of human salivary cells. Different EWA formulations were prepared and biologically evaluated as a spheroid-like structure platform. Although all five EWA hydrogels showed biocompatibility, the EWA with 1.5% alginate presented the highest cell viability, while EWA with 3% alginate promoted the formation of larger size salivary spheroid-like structures. Our EWA hydrogel has the potential to be an alternative 3D culture scaffold that can be used for studies on drug-screening, cell migration, or as an in vitro disease model. In addition, EWA can be used as a potential source for cell transplantation (i.e., using this platform as an ex vivo environment for cell expansion). The low cost of producing EWA is an added advantage.     

Urea Biosensor Based on Electrochromic Properties of Prussian Blue

Prussian blue (PB) is an electrochromic material, which can be used as a signal transducer in the formation of optical urea biosensors. The previous researches in electrochromic properties of PB demonstrated the optical PB response to ammonium ions, which occurs when ammonium ions are interacting with PB layer at a constant 0.2 V vs Ag|AgCl|KCl_sat potential. In this work PB optical dependence on ammonium ions concentration was applied in the formation of electrochromic urea biosensor. Biosensor was formed by modifying the optically transparent indium tin oxide (ITO) coated glass electrode (glass/ITO) with Prussian blue layer and immobilizing urease (glass/ITO/PB‐urease). Calibration curve showed the linear dependency (R²=0.995) between the change of maximal absorbance (ΔA) and urea concentration in concentration range varying from 3 mM to 30 mM. The highest sensitivity (4 ΔA M^?1) of glass/ITO/PB‐urease biosensor is in the concentration range from 7 mM to 30 mM. It was determined that working principle of the glass/ITO/PB‐urease biosensor is not related to pH changes occurring during enzymatic hydrolysis of urea.     

Multicomponent Organic Metal Halide Hybrid with White Emissions

Zero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)₄PbMn_0.69Sn_0.31Br₈, in which the organic cation N‐benzylhexamethylenetetrammonium (HMTA⁺, C₁₃H₁₉N₄⁺) cocrystallizes with PbBr₄^2?, MnBr₄^2?, and SnBr₄^2?. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.