Dual Illumination Enhances Transformation of an Engineered Green-to-Red Photoconvertible Fluorescent Protein

The molecular mechanisms for the photoconversion of fluorescent proteins remain elusive owing to the challenges of monitoring chromophore structural dynamics during the light-induced processes. We implemented time-resolved electronic and stimulated Raman spectroscopies to reveal two hidden species of an engineered ancestral GFP-like protein LEA, involving semi-trapped protonated and trapped deprotonated chromophores en route to photoconversion in pH 7.9 buffer. A new dual-illumination approach was examined, using 400 and 505 nm light simultaneously to achieve faster conversion and higher color contrast. Substitution of UV irradiation with visible light benefits bioimaging, while the spectral benchmark of a trapped chromophore with characteristic ring twisting and bridge-H bending motions enables rational design of functional proteins. With the improved H-bonding network and structural motions, the photoexcited chromophore could increase the photoswitching-aided photoconversion while reducing trapped species.     

空心球状C@SnO2@SnS2的制备及光催化去除Cr（Ⅵ）性能研究

将SnO2负载在碳球上通过不完全烧结的方法得到含有大量碳的空心状C@SnO2,随后加入TAA(硫代乙酰胺),利用离子交换法在水热过程中制备了具有不同硫化程度的空心结构的C@SnO2@SnS2三元复合物。利用XRD、FESEM、TEM、XPS、UV-Vis DRS、PL等测试手段对合成样品进行表征,并测试了其光催化去除Cr(VI)的性能。结果表明,C、SnO2和SnS2三者之间的协同作用以及空心结构的形貌显著增强了SnO2的光催化性能,其中CSS-2样品对Cr(VI)具有最佳的去除能力,太阳光照射120 min后对Cr(VI)的去除率高达98.8%。     

新型离子型配合物的合成、晶体结构及性质

利用水热法合成了4-(N,N′-双(4-羧基苄基)氨基)苯磺酸（H₃L）的两个离子型配合物：[Mn(phen)₂(H₂O)₂]?(HL)?(H₂O)₄（1）和[Zn(phen)₂(H₂O)₂]?(HL)?(H₂O)₆（2, phen =邻菲罗啉）,其结构经FL、 IR、元素分析、X-射线单晶衍射、 X-射线粉末衍射和TG表征。结果表明：化合物1属于单斜晶体,P2₁/c空间群,晶胞参数a=11.997(1) Å, b=22.978(1) Å, c=18.093(1) Å, β=92.749(3)°, V=4981.8(3) ų, Z=4。化合物2属于单斜晶体,P2₁/c空间群,晶胞参数a=11.861(1) Å, b=22.816(1) Å, c=18.251(1) Å, β=92.832(5)°, V=4932.8(5) ų,Z=4。化合物2有较好的荧光性质;初始分解温度为80 ℃。      

Unraveling Dual Aggregation‐Induced Emission Behavior in Steric‐Hindrance Photochromic System for Super Resolution Imaging

Unprecedented dual aggregation‐induced emission (AIE) behavior based on a steric‐hindrance photochromic system is presented, with incorporation one or two bulky aryl groups, resulting in different flexibleness. The dual AIE behavior of open and closed isomers can be explained by restriction of intramolecular rotation (RIR), restriction of intramolecular vibration (RIV), and intermolecular stacking. The large bulky benzothiophene causes restricted rotation, enhancing the emission of open form in solution and weak π–π molecular packing, thereby efficiently enhancing the luminescence performance in the solid state. With incorporation of two large bulky benzothiophene groups, BBTE possesses the most outstanding AIE activity, undergoing highly efficient and reversible off‐to‐on fluorescence in film upon alternating UV and visible light irradiation along with excellent fatigue resistance. The off‐to‐on fluorescent photoswitch is successfully established in super resolution imaging.     

Asymmetric Hydrogenation of Unfunctionalized Tetrasubstituted Acyclic Olefins

Asymmetric hydrogenation has evolved as one of the most powerful tools to construct stereocenters. However, the asymmetric hydrogenation of unfunctionalized tetrasubstituted acyclic olefins remains the pinnacle of asymmetric synthesis and an unsolved challenge. We report herein the discovery of an iridium catalyst for the first, generally applicable, highly enantio‐ and diastereoselective hydrogenation of such olefins and the mechanistic insights of the reaction. The power of this chemistry is demonstrated by the successful hydrogenation of a wide variety of electronically and sterically diverse olefins in excellent yield and high enantio‐ and diastereoselectivity.     

γ‐Glutamylcysteine‐ and Cysteinylglycine‐Directed Growth of Chiral Gold Nanoparticles and their Crystallographic Analysis

Chiral optical metamaterials with delicate structures are in high demand in various fields because of their strong light–matter interactions. Recently, a scalable strategy for the synthesis of chiral plasmonic nanoparticles (NPs) using amino acids and peptides has been reported. Reported herein, 3D chiral gold NPs were synthesized using dipeptide γ‐Glu‐Cys and Cys‐Gly and analyzed crystallographically. The γ‐Glu‐Cys‐directed NPs present a cube‐like outline with a protruding chiral wing. In comparison, the NPs synthesized with Cys‐Gly exhibited a rhombic dodecahedron‐like outline with curved edges and elliptical cavities on each face. Morphology analysis of intermediates indicated that γ‐Glu‐Cys generated an intermediate concave hexoctahedron morphology, while Cys‐Gly formed a concave rhombic dodecahedron. NPs synthesized with Cys‐Gly are named 432 helicoid V because of their unique morphology and growth pathway.     

Rapid measurements of curcumin from complex samples coupled with magnetic biocompatibility molecularly imprinted polymer using electrochemical detection

Curcumin widely exists in food, and rapid selective and accurate detection of curcumin have great significance in chemical industry. In this experiment, a new magnetic biocompatibility molecularly imprinted polymer was prepared with nontoxic and biocompatible Zein to adsorb curcumin selectively. The polymer has high biocompatibility, good adsorption capacity, and specific adsorption for curcumin. Combined with portable electrochemical workstations, the polymer can be used to detect curcumin rapidly and cost‐effectively. Using curcumin as a template and Zein as the crosslinking agent, the polymers were synthesized on the surface of Fe₃O₄ particles for solid phase extraction. The experimental results showed that the polymer reached large adsorption capacity (32.12 mg/g) with fast kinetics (20 min). The adsorption characteristic of the polymer followed the Langmuir isotherm and pseudo‐second‐order kinetic models. Hexacyanoferrate was used as electrochemical probe to generate signals, and the linear range was 5–200 µg/mL for measuring curcumin. The experimental analysis showed that the polymer was an ideal material for selective accumulation of curcumin from complex samples. This approach has been successfully applied to the determination of curcumin in food samples with electrochemical detection, indicating that this is a feasible and practical technique.     

A new rotation method for constructing orthogonal Latin hypercube designs

Latin hypercube designs(LHDs) are very popular in designing computer experiments. In addition,orthogonality is a desirable property for LHDs, as it allows the estimates of the main effects in linear models to be uncorrelated with each other, and is a stepping stone to the space-filling property for fitting Gaussian process models. Among the available methods for constructing orthogonal Latin hypercube designs(OLHDs),the rotation method is particularly attractive due to its theoretical elegance a...     

Thermal Hysteresis Accompanying Incommensurate-Commensurate Phase Transition in Mixed Crystals (K1-xCsx)2ZnCl4

The mixed crystal (K_1-xCs_x)₂ZnCl₄ with x = 0, 0.001, 0.01, 0.1, and 0.2 with optical quality has been grown by the Czochralski method. Using the Atomic Absorption Spectroscopy (AAS) and Energy Dispersive Spectroscopy (EDS), we determined the amount of Cs ion included in the mixed crystal. By using of DTA and DSC, we observed the change of T_c and T_i. The thermal hysteresis in the dielectric constants show strong dependence on the thermal process and on the amount of impurity which are explained by the influence of the thermal process and impurity, respectively on the creation, annihilation, and growth of discommensuration (DC).     

太阳光对液晶显示器件光学特性的影响

太阳光对液晶显示器件的影响主要表现在它对其液晶显示器件光稳定性和寿命的影响,从而引起液晶显示器件的迅速老化。通过用分光光度计测量经过不同时间太阳光辐照后液晶显示器件的光谱特性,研究长时间阳光辐照对液晶显示器件的光学性能的影响,分析其光学性能的变化。结果表明, B组普通计算器液晶显示器和C组电话液晶显示器两组液晶片的光学特性类似,品质较好;而A组台式计算器液晶显示器液晶片的老化问题明显比B, C两组严重,品质较差。液晶显示器件长时间受阳光辐照,液晶结构会相应发生变化,光学性能也发生相应变化,表现为液晶表面变黄发黑,其光谱透射特性明显下降。这与液晶材料及制作工艺有关。