不同声音偏好的游客声景观主观评价差异——以丽江大研古镇为例*

古镇作为集自然景观与人文景观一体的景区，具有丰富的声音类型。本研究以大研古镇为例，通过实地调研探究不同声音偏好的游客对古镇声景观的主观评价差异。基于游客的声音偏好，将游客分为偏爱自然声和偏爱人工声两大类。通过因子分析提取游客声景观主观评价的5个主因子：大小、音质、效价、偏好和唤醒。进一步分析发现，这5个因子具有一定的层级性，其中从大小到唤醒代表声景观评价从声音的物理属性向声音的联想评价逐级提升。其中在低层级评价(大小、音质)中，偏好自然声的游客和偏好人工声的游客无显著差异，低层级评价具有稳定性；而在高层级评价(效价、偏好和唤醒)中，偏好人工声的游客更关注古镇声景观的淳朴性和遗产性。因此，游客对声景观的主观评价可视为一种指标，判断景区声景所处的评价阶段，从而为景区声景观改善提供更有针对性的建议。     

基于5-磺基水杨酸的单、双核铜(Ⅱ)三元混配配合物的合成及晶体结构

以5-磺基水杨酸和咪唑衍生物为配体合成了单核、双核结构的三元混配Cu(Ⅱ)配合物:[Cu(H₂biim)(Hssal)(H₂O)₂]·H₂O(1)和{[Cu(MeHbiim)(Hssal)(H₂O)]·0.5H₂O}₂(2)(H₃ssal=5-磺基水杨酸,H₂biim=2,2’-联咪唑,MeHbiim=N-甲基-2,2’-联咪唑),并利用元素分析、红外光谱、紫外-可见光谱、X-射线单晶衍射及热重分析等技术手段对其结构进行了表征。单晶结构解析表明配合物1属于单斜晶系,P2₁／C 空间群,Cu(Ⅱ)离子与1个5-磺基水杨酸根、2个水分子以及1个联咪唑分子形成五配位四角锥构型的单核配合物结构。配合物2属于正交晶系,P2(1)2(1)2(1)空间群,双核Cu(II)离子分别处于五配位四角锥和四配位平面四边形的几何构型的配位环境中,与配合物1不同,5-磺基水杨酸采取μ₂双-单齿配位模式。荧光光谱分析表明配合物2具有较强的荧光性。     

有机化学实验线上课程之扬长避短教学设计与实践篇

It has been two months since a boom of online education triggered by the epidemic in China. At present, we are keeping focus on how to optimize our online class. In the case of chemistry laboratory courses, there's not much that can be done to experimental operations through online teaching. While for the traditional teaching procedure, there is still room for improvement in terms of integrating research to teaching, interactivity, etc. This paper will present some design strategies for improving teaching the organic chemistry laboratory online. To be specific, it describes how teaching materials like the lesson plan and virtual lab were coordinated into the online teaching. And we will also discuss the holistic approach to a better outcome for students' active learning and integration research into teaching by redesigning multiple phases, such as the pre-laboratory preparation, live online class, experimental operations.     

MOFs-derived hierarchical porous carbon confining the monodisperse Ni and defective WOx for efficient and stable hydrogenolysis of cellulose to ethylene glycol

The one-pot catalytic conversion of cellulose into ethylene glycol (EG) is an attractive way of biomass utilization. However, low-cost, efficient, and stable catalysts are the premise and research challenges of industrial application. Herein, the magnetic recyclable W–Ni@C catalyst was synthesized by in-situ pyrolysis of Ni-MOFs impregnated with ammonium metatungstate. Compared with the Ni-W bimetallic catalysts prepared by the impregnation method and the sol–gel method, the W–Ni@C catalyst for cellulose hydrogenolysis reaction can achieve a higher ethylene glycol yield (67.1% vs 43.3% and 42.6%) and 100% of cellulose conversion rate. The uniformly dispersed Ni nanoparticles and abundant defective WO_x were formed in a reductive atmosphere generated in pyrolysis of Ni-MOFs, which was indispensable for the hydrogenolysis of cellulose into EG. Besides, the hierarchical porous carbon derived from organic ligands in Ni-MOFs reduces the mass transfer resistance while confining Ni nanoparticles and WO_x to prevent their leaching, effectively enhancing the stability of the W–Ni@C catalyst. Therefore, the remarkable catalytic performance, the simple and effective recovery method as well as satisfying stability would make W–Ni@C become a promising catalyst for the conversion of cellulose to EG.

Graphical abstract

     

Amorphous Manganese–Cobalt Nanosheets as Efficient Catalysts for Hydrogen Evolution Reaction (HER)

Catalysis Surveys from Asia - A facile and efficient electrocatalyst for hydrogen evolution reaction (HER) to produce hydrogen is very important for future energy. In this paper, amorphous...     

The analysis study on nonlinear iterative methods for inverse problems

In this paper, the nonlinear iterative methods, which are different from the classical algorithms, to solve inverse problems are presented. Our methods by denoting some parameters and some properties of the algorithm in both noise and noiseless cases are studied. Finally, the convergence of the sequence generated by the algorithm without noise is discussed.     

Turn-on Circularly Polarized Luminescence in Chiral Indium Chlorides by 5s2 Metal Centers

Introducing chirality into the metal-halide hybrids has enabled many emerging properties including chiroptical activity, spin-dependent transport, and ferroelectricity. However, most of the chiral metal-halide hybrids to date are non-emissive, and the underlying mechanism remains elusive. Here, we show a new strategy to turn on the circularly polarized luminescence (CPL) in chiral metal-halide hybrids. We demonstrate that alloying Sb³⁺ into chiral indium-chloride hybrids dramatically increases the photoluminescence quantum yield in two new series of chiral indium-antimony chlorides. These materials exhibit strong CPL signals with tunable energy and a high dissymmetry factor up to 1.5×10⁻². Mechanistic studies reveal that the emission originates from the self-trapped excitons centered in 5s² Sb³⁺. Moreover, near-ultraviolet pumped white light is demonstrated with a polarization up to 6.0 %. Our work demonstrates new strategies towards highly luminescent chiral metal-halide hybrids.     

Nickel-Catalyzed Markovnikov-Selective Hydrodifluoromethylation of Alkynes Using BrCF2H

A Markovnikov-selective hydrodifluoromethylation of alkynes with BrCF₂H via nickel catalysis is described. This protocol proceeds via a migratory insertion of nickel hydride to alkyne followed by a CF₂H-coupling, enabling straightforward access to diverse branched CF₂H-alkenes with high efficiency and exclusive regioselectivity. The mild condition applies to a wide array of aliphatic and aryl alkynes with good functional group compatibility. Mechanistic studies are presented to support the proposed pathway.     

Hybrid Double Perovskite Derived Halides Based on Bi and Alkali Metals (K,Rb): Diverse Structures,Tunable Optical Properties and Second Harmonic Generation Responses

Double perovskites (DP) have attracted extensive attention due to their rich structures and wide application prospects in the field of optoelectronics. Here, we report 15 new Bi-based double perovskite derived halides with the general formula of A₂BBiX₆ (A=organic cationic ligand, B=K or Rb, X=Br or I). These materials are synthesized using organic ligands to coordinate with metal ions with a sp³ oxygen, and diverse structure types have been obtained with distinct dimensionalities and connectivity modes. The optical band gaps of these phases can be tuned by changing the halide, the organic ligand and the alkali metal, varying from 2.0 to 2.9 eV. The bromide phases exhibit increasing photoluminescence (PL) intensity with decreasing temperature, while the PL intensity of iodide phases changes nonmonotonically with temperature. Because the majority of these phases are non-centrosymmetric, second harmonic generation (SHG) responses are also measured for selected non-centrosymmetric materials, showing different particle-size-dependent trends. Our findings give rise to a series of new structural types to the DP family, and provide a powerful synthetic handle for symmetry breaking.