化妆品及香精中27种香料的气相色谱-质谱检测方法

建立了气相色谱-质谱同时检测化妆品及香精中27种香料的方法。采用甲醇作为提取溶剂，经弱极性毛细管柱分离，用气相色谱-质谱检测，离子源为电子轰击离子（EI）源。该方法对麝香二甲苯、羟基香茅醛和羟异己基3-环己烯基甲醛的检出限分别为1.2、15和15 mg/kg，其余香料的检出限为3.0 mg/kg。27种香料在相应的线性范围内线性关系良好，相关系数均大于等于0.996。在3个加标浓度下，麝香二甲苯的回收率为73.3%~76.1%，其余为81.5%~118%，相对标准偏差小于10%。采用建立的方法对69份香精或标示含香料化妆品进行检测，全部样品都检测出含有一种或多种香料。该方法适用于化妆品及香精中27种香料的测定。     

N-Doped Carbon Nanofibers Encapsulating CoO@Co9S8 Nanoparticles: Preparation from S-Rich Co32 Coordination Cluster Precursors by Electrospinning and Application for Superior Li-ion Storage

Thiacalixarene-supported Co₃₂nanoclusters encapsulated in polyacrylonitrile nanofibers(Co₃₂@PAN-NFs) by electrospinning have been utilized as precursors to fabricate N-doped CoO@Co₉S₈ carbon nanofibers(CoO@Co₉S₈@CNFs) for superior Li-ion storage. The S-rich Co₃₂ clusters capped by organic sheets afforded the well dispersed cobalt oxide/sulfide nanoparticles embedded in carbon nanofiber composites by direct calcination. The N-doped CoO@Co₉S₈@CNFs nanocomposites have been utilized as anode materials for lithium ion battery with the reversible capabilities being of 1051.8, 967.6, 894.7, 782.7, 669.5 and 525.4 mA·h/g at 0.1, 0.2, 0.5, 1, 2 and 3 A/g, respectively. The CoO@Co₉S₈@CNFs also showed a relatively high stable capacity of 551.7 mA·h/g at the current density of 1 A/g after 200 cycles of rate experiments. The as-obtained N-doped CoO@Co₉S₈@CNFs nanocomposites exhibited superior reversible capacity, rate performance, Coulomb efficiency(74.5% vs. 63.9%) and cyclic stability comparing with the CoO@Co₉S₈@C derived from simple annealing of Co₃₂ templates.     

Characterisation of Graphs which Underlie Regular Maps on Closed Surfaces

It is proved that a graph K has an embedding as a regular mapon some closed surface if and only if its automorphism groupcontains a subgroup G which acts transitively on the orientededges of K such that the stabiliser G_e of every edge e is dihedralof order 4 and the stabiliser G of each vertex is a dihedralgroup the cyclic subgroup of index 2 of which acts regularlyon the edges incident with . Such a regular embedding can berealised on an orientable surface if and only if the group Ghas a subgroup H of index 2 such that H is the cyclic subgroupof index 2 in G. An analogous result is proved for orientably-regularembeddings.     

A new curvularin glycoside and its cytotoxic and antibacterial analogues from marine actinomycete Pseudonocardia sp. HS7

Five curvularin macrolides (1–5) were isolated from the cultured broth of marine actinomycete Pseudonocardia sp. HS7 that was obtained from the cloacal aperture of sea cucumber Holothuria moebii. The structures of these isolates were characterized as (11S,15R)-11-hydroxycurvularin (1), (11R,15R)-11-hydroxycurvularin (2), curvularin-7-O-α-D-glucopyranoside (3), trans-dehydrocurvularin (4) and curvularin (5) based on their NMR and HRESIMS data as well as chemical degradation. Compound 3 is a new macrolide with a rare α-D-glucopyranose substituent. Compounds 1–4, 5a and 5c (the acyl products of 5), suppressed the proliferation of all six tested cancer cell lines and 4 is the most active compound with IC₅₀ values ranging from 0.59 to 3.39 μM. The 11-hydroxycurvularins 1 and 2 also showed antibacterial activity inhibiting the growth of Escherichia coli.     

W s,n s $W^{s,\frac {n}{s}}$ -maps with positive distributional Jacobians

Potential Analysis - We extend the well-known result that any $f \in W^{1,n}({\Omega }, \mathbb {R}^{n})$ , ${\Omega } \subset \mathbb {R}^{n}$ with strictly positive Jacobian is actually...     

含吲哚的吡唑并[3,4-d]嘧啶衍生物的设计合成及其生物活性研究

利用药物设计中的生物活性基团拼接原理,设计合成了13个含吲哚的吡唑并[3,4-d]嘧啶衍生物.目标化合物均经核磁共振氢谱(1H NMR)、核磁共振碳谱(13C NMR)和高分辨质谱仪(HRMS)进行了结构确证.对4株肿瘤细胞(HeLa、MGC-803、MCF-7、BEL-7404)的体外抗增殖活性实验结果表明,目标化合物均表现出一定的抗肿瘤活性,MCF-7、MGC-803肿瘤细胞株敏感度高于HeLa和BEL-7404.其中, 6-[(6-甲氧羰基吲哚-3-基)硫基]-1-苯基-吡唑并[3,4-d]嘧啶-4-酮(5m)表现出较好的体外肿瘤抑制活性,对MCF-7、MGC-80和HeLa细胞的IC50均小于30μmol·L^-1,对MCF-7的IC50值为(4.02±0.92)μmol·L^-1,优于对照药物依托泊苷(10.1±0.62μmol·L^-1)和羟喜树碱(5.93±0.56μmol·L^-1).拓扑异构酶抑制实验结果表明,此类化合物对TopoII有选择性抑制活性,所有化合物对TopoⅡ表现出不同程度抑制活性,对Topo Ⅰ未表现出抑制活性.     

A note on Alberti’s Luzin-type theorem for gradients

Ricerche di Matematica - We give a “soft” proof of Alberti’s Luzin-type theorem in Alberti (J Funct Anal 100:110–118, 1991), using elementary geometric measure theory and...     

Global Weak Rigidity of the Gauss–Codazzi–Ricci Equations and Isometric Immersions of Riemannian Manifolds with Lower Regularity

We are concerned with the global weak rigidity of the Gauss–Codazzi–Ricci (GCR) equations on Riemannian manifolds and the corresponding isometric immersions of Riemannian manifolds into the Euclidean spaces. We develop a unified intrinsic approach to establish the global weak rigidity of both the GCR equations and isometric immersions of the Riemannian manifolds, independent of the local coordinates, and provide further insights of the previous local results and arguments. The critical case has also been analyzed. To achieve this, we first reformulate the GCR equations with div-curl structure intrinsically on Riemannian manifolds and develop a global, intrinsic version of the div-curl lemma and other nonlinear techniques to tackle the global weak rigidity on manifolds. In particular, a general functional-analytic compensated compactness theorem on Banach spaces has been established, which includes the intrinsic div-curl lemma on Riemannian manifolds as a special case. The equivalence of global isometric immersions, the Cartan formalism, and the GCR equations on the Riemannian manifolds with lower regularity is established. We also prove a new weak rigidity result along the way, pertaining to the Cartan formalism, for Riemannian manifolds with lower regularity, and extend the weak rigidity results for Riemannian manifolds with corresponding different metrics.     

Hamiltonian embeddings from triangulations

A Hamiltonian embedding of K_n is an embedding of K_n in a surface,which may be orientable or non-orientable, in such a way thatthe boundary of each face is a Hamiltonian cycle. Ellinghamand Stephens recently established the existence of such embeddingsin non-orientable surfaces for n = 4 and n 6. Here we presentan entirely new construction which produces Hamiltonian embeddingsof K_n from triangulations of K_n when n 0 or 1 (mod 3). We thenuse this construction to obtain exponential lower bounds forthe numbers of nonisomorphic Hamiltonian embeddings of K_n.     

“绿氢”工业化碱性催化剂研究现状及未来展望

电解水制氢技术的发展对于加快实现全球碳中和目标具有重要意义。然而,碱性介质中缓慢的析氢/析氧反应动力学过程目前是阻碍该技术发展的瓶颈问题。基于此,本文首先综述了碱性环境下析氢反应与析氧反应不同的动力学理论机制,总结了针对改善动力学反应过程的理论设计策略。随后,介绍了目前电解水催化剂的设计理念及方向。对新兴的“绿氢”技术而言,探索在高电流密度下高性能电催化剂对这项技术在工业化应用推广中起着核心作用。同时,大规模合成策略是辅助合成工业电极的关键技术。进一步,我们在推进“绿氢”工业化应用的基础上总结了目前常用三种电解槽,介绍了目前电解槽设计的局限性及对应解决方案。总之,深入研究适用于碱性环境中的工业电催化剂、商业膜或电解槽的设计,提高对工业设计原则的理解,对于获得效率更高、安全性更高、实用性更强的工业电解槽具有重要意义。