Distinctive structural motifs co‐ordinate the catalytic nucleophile and the residues of the oxyanion hole in the alpha/beta‐hydrolase fold enzymes

The alpha/beta‐hydrolases (ABH) are among the largest structural families of proteins that are found in nature. Although they vary in their sequence and function, the ABH enzymes use a similar acid–base‐nucleophile catalytic mechanism to catalyze reactions on different substrates. Because ABH enzymes are biocatalysts with a wide range of potential applications, protein engineering has taken advantage of their catalytic versatility to develop enzymes with industrial applications. This study is a comprehensive analysis of 40 ABH enzyme families focusing on two identified substructures: the nucleophile zone and the oxyanion zone, which co‐ordinate the catalytic nucleophile and the residues of the oxyanion hole, and independently reported as critical for the enzymatic activity. We also frequently observed an aromatic cluster near the nucleophile and oxyanion zones, and opposite the ligand‐binding site. The nucleophile zone, the oxyanion zone and the residue cluster enriched in aromatic side chains comprise a three‐dimensional structural organization that shapes the active site of ABH enzymes and plays an important role in the enzymatic function by structurally stabilizing the catalytic nucleophile and the residues of the oxyanion hole. The structural data support the notion that the aromatic cluster can participate in co‐ordination of the catalytic histidine loop, and properly place the catalytic histidine next to the catalytic nucleophile.     

城市食物-能源-水关联关系:概念框架与研究展望

食物、能源和水(Food, Energy and Water, FEW)是人类生存与发展不可或缺的基础性资源,且三者之间存在密切的关联关系(Nexus),即其中任何一项资源的生产与供给均依赖于另外两项资源。FEW关联关系作为应对全球人口增长、资源短缺和生态环境恶化等问题的系统性管理理念,已引起国际学术界与实践管理领域的广泛关注。然而,目前对FEW关联关系仍然缺乏统一和清晰的界定,现有研究大多是基于不同角度理解与量化"关联关系"。城市作为全球资源消费的主阵地,其FEW关联关系更为复杂,亟待建立针对城市生态系统的概念框架。对FEW关联关系的发展历程、概念表述以及研究方法等方面进行全面回顾和系统分析。在此基础上,从"资源依存"、"资源供给"和"系统集成"等3个视角构建了城市FEW关联关系的概念框架,并进一步阐述FEW关联关系未来研究的重点方向——"系统性表征"、"时空演化"与"协同管理",为城市优化资源配置,实现集成管理提供一种新思路和定量化的参考依据。     

山水林田湖草生态修复工程的社会-生态系统(SES)分析框架及应用——以浙江省钱塘江源头区域为例

“山水林田湖草生命共同体”是人与自然和谐共处的指导原则,也是人类实现可持续发展的有效实践路径。根据Ostrom提出的社会-生态系统（SES）框架,以浙江省钱塘江源头区域为研究区,构建集流域、陆地和人类活动为一体的社会-生态系统（SES）概念框架,为生态修复工程提供一个问题导向的分析策略。研究发现基于Ostrom构建的钱塘江源头区域山水林田湖草生态修复工程的SES框架,可以用来诊断关键问题、分析影响因素、设定行动情景和评估结果,从而形成完整的实施和解决问题策略。由诊断关键问题得出,该区域面临地质灾害多发、水土流失、环境污染、生物结构单一等多重问题,而人类活动如城市扩张、过度开发自然资源、污染物排放等则是造成社会-生态系统失衡的主要因素。通过行动情景设置将SES框架中涉及的影响因素、解决途径、评价标准、期望的成效以及反馈机制等进行梳理,对研究区的社会-生态系统进行全面分析。根据设立的评价体系对生态修复工程进行生态环境和社会经济效果的动态评估,并不断地根据评价结果进行修正以获得最佳的预期成效。该框架为解决钱塘江源头区域山水林田湖草生态修复工程所面临的问题提供了一个系统的解决方案,并可根据研究区的特点进行相应调整,是一个具有强适用性的社会-生态系统分析框架。     

Four three-dimensional lanthanide coordination polymer constructed from benzene-1,4-dioxydiacetic acid

Four crystalline lanthanide(III) three-dimensional (3D) coordination polymers {[La(BDOA)_1.5(H₂O)] · H₂O}_n (1), {[Nd(BDOA)_1.5(H₂O)] · H₂O}_n (2), [Tm(BDOA)_1.5(H₂O)]_n (3), [Yb(BDOA)_1.5(H₂O)]_n (4) were obtained under hydrothermal conditions and characterized by elemental analysis, IR, as well as single-crystal X-ray diffraction. Compounds 1 and 2 crystallize in the monoclinic system, space group P2₁/c, they are isostructural and exhibit the same 3²¹.4⁵⁷.5¹³ topological network constructed from different coordination modes of two BDOA ligands, whereas isostructural 3 and 4 crystallizes in the triclinic system, space group , it holds 3⁹.4²⁰.5⁷ topological architecture based on another two different coordination modes BDOA ligands. Moreover, a computational method is applied to evaluate the potential porosity of complex 1.     

A 2D [Fe-bistetrazole] coordination polymer exhibiting spin-crossover properties

The reaction of 1,3-bis(tetrazol-1-yl)-2-propanol (btzpol) with Fe(BF₄)₂ · 6H₂O in acetonitrile yields the remarkable 2D coordination polymer [Fe^II(btzpol)_1.8(btzpol-OBF₃)_1.2](BF₄)_0.8 · (H₂O)_0.8(CH₃CN) (1). This compound has been structurally characterized using an X-ray single-crystal synchrotron radiation source. The iron(II) centers are bridged by means of double btzpol bridges along the c direction, and by single btzpol bridges along the b direction. The reaction of part of the ligand with the counterion has forced the compound to crystallize in this extended two dimensional structure. The compound shows spin-transition properties, both induced by temperature and light, with T_1/2 = 112 K and T(LIESST) = 46 K, respectively. The relaxation of the metastable high-spin state created by irradiation is exponential, following an Arrhenius type behavior at high temperature, and dominated by a temperature independent tunneling process at lower temperatures.     

Self-assembly of two fluorescent supramolecular frameworks constructed from unsymmetrical benzene tricarboxylate and bipyridine

Two new supramolecular compounds, [Ag(4,4′-bipy)]_n [Ag(HBTC)]_n (1) and [Cu(H₂BTC)(2,2′-bipy)] (2) (HBTC/H₂BTC = 1,2,4-benzenetricarboxylate, 4,4′-bipy/2,2′-bipy = 4,4′/2,2′-bipyridine), have been synthesized and characterized by elemental analyses, IR spectra, ultraviolet-visible diffuse reflection integral spectra (UV-Vis DRIS), fluorescent spectra, thermogravimetric analysis and single crystal X-ray diffraction analysis. It is noteworthy that there were two kinds of one-dimensional stairs-chain including cationic [Ag(4,4′-bipy)]_n chain and anionic [Ag(HBTC)]_n chain in 1. Furthermore, a two-dimensional double layer supramolecular framework was constructed through coordination bonds, hydrogen bonds, π-π stacking interactions and Ag?O weak coordinative interactions. The one-dimensional supramolecular chain of 2 was built from combining mononuclear [Cu(H₂BTC)(2,2′-bipy)] by inter- and intra-molecular hydrogen bonding interactions. Additionally, the two complexes exhibit intense blue or olivine luminescence at room temperature.     

Radiolarian skeleton: Morphology of spines,internal framework,and primary sphere

The morphology and evolution of the internal framework, primary inner sphere, and various spines of radiolarian skeletons are considered. A new scheme of successive stages of spine formation is offered. The convergent similarity of radiolarian spines and sponge spicules are discussed.     

企业生物多样性信息披露: 调查、分析与建议

近年来我国每年发布《企业社会责任报告》近2,000份, 有相当比例包含生物多样性内容。但长期以来, 披露内容的实质性与可信度严重不足, 亟需引导、规范和审核。本文探讨建立我国企业生物多样性信息公开透明机制, 旨在解决两个主要问题: 一是风险规避, 二是资源调动。本文根据《生物多样性公约》相关规定, 首先梳理企业生物多样性信息披露国内外进展, 指出存在内容碎片化, 科学指标缺失, 结果难以比较, 投入产出、同业及历史数据缺乏比对分析等不足。其次, 采用5个生物多样性指标, 进一步对《企业社会责任报告评估指数》研究发现: 不同行业差异化明显、金融机构催化作用凸显、重视纳入制度战略框架、报告内容同质化严重、定性描述多于定量分析、货币化核算方法缺失、资金投入信息披露保守、未经第三方独立审核等特点。最后, 提出提高企业透明度的4项建议: (1)加强顶层设计纳入, (2)改进环境政策指引, (3)优化金融激励措施, (4)强化公司能力建设。这将为政府和金融部门量化生态影响, 管控投资风险, 实施扩大生物多样性融资决策提供支持。     

国家公园体制背景下中国自然保护地体系变迁--基于多源流理论分析

随着经济社会的发展,中国自然保护地体系经历了由以自然保护区为主体向以国家公园为主体的重要变迁。应用多源流理论分析了中国自然保护地体系变迁。从内在逻辑、民主化程度和变量控制三个方面分析了多源流理论在中国保护地变迁研究中的适用性;从问题源流、政治源流和政策源流三个方面分析了中国自然保护地体系变迁的主要影响因素,梳理了变迁的逻辑路线,总结了变迁的内容,变迁内容包括管理客体、管理主体和管理手段三个方面。结果表明:中国自然保护地体系变迁是问题源流、政治源流和政策源流共同作用的必然结果,表现在问题源流中的指标数据和问题反馈促进了政策源流中政策建议和方案的提出,而焦点事件与政治源流中执政理念的冲突对变迁起到了重要的催化作用;政策源流存在渐进式完善过程,尤其是国家公园体制试点对政策源流的发展起到关键作用。此次变迁的逻辑路径主要包含三股源流的相互作用,通过引入国家公园重塑中国自然保护地体系,促进其系统性、整体性和协同性发展。