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共1034条结果
  • 1.

    【2hr】Building a Consistent and Reproducible Database for Adsorption Evaluation inCovalent–Organic Frameworks

    包量

    机译 建立一致且可重现的吸附评价数据库共价有机框架
    摘要：We present a workflow that traces the path from the bulk structure of a crystalline material to assessing its performance in carbon capture from coal’s postcombustion flue gases. This workflow is applied to a database of 324 covalent–organic frameworks (COFs) reported in the literature, to characterize their CO2 adsorption properties using the following steps: (1) optimization of the crystal structure (atomic positions and unit cell) using density functional theory, (2) fitting atomic point charges based on the electron density, (3) characterizing the pore geometry of the structures before and after optimization, (4) computing carbon dioxide and nitrogen isotherms using grand canonical Monte Carlo simulations with an empirical interaction potential, and finally, (5) assessing the CO2 parasitic energy via process modeling. The full workflow has been encoded in the Automated Interactive Infrastructure and Database for Computational Science (AiiDA). Both the workflow and the automatically generated provenance graph of our calculations are made available on the Materials Cloud, allowing peers to inspect every input parameter and result along the workflow, download structures and files at intermediate stages, and start their research right from where this work has left off. In particular, our set of CURATED (Clean, Uniform, and Refined with Automatic Trackingfrom Experimental Database) COFs, having optimized geometry and high-quality DFT-derivedpoint charges, are available for further investigations of gas adsorption properties. Weplan to update the database as new COFs are being reported.
  • 2.

    【2hr】Reticular Chemistry in All Dimensions

    包量

    机译 全方位的网状化学
    • 作者：Omar M. Yaghi
    • 刊名：ACS Central Science
    • 2019年第8期
    摘要：
  • 3.

    【2hr】A Conversation with Carson Bruns

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    机译 与卡森·布伦斯的对话
    • 作者：Carmen Drahl
    • 刊名：ACS Central Science
    • 2019年第2期
    摘要：
  • 4.

    【2hr】Turning Organic Waste into Hydrogen

    包量

    机译 将有机废物转化为氢气
    • 作者：XiaoZhi Lim
    • 刊名：ACS Central Science
    • 2019年第2期
    摘要：
  • 5.

    【2hr】A Conversation with Kenichiro Itami

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    机译 Akkoner Sachionui th Kenichiro Itami
    • 作者：Mark Peplow
    • 刊名：ACS Central Science
    • 2019年第1期
    摘要：
  • 6.

    【2hr】A “Broad Spectrum” Carbene Transferase for Synthesis of Chiral α-Trifluoromethylated Organoborons

    包量

    机译 一种“广谱”碳烯转移酶，用于合成手性α-三氟甲基化有机硼
    摘要：
  • 7.

    【2hr】Tackling Delhi’s Air Pollution Problem

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    机译 解决德里的空气污染问题
    • 作者：Prachi Patel
    • 刊名：ACS Central Science
    • 2019年第1期
    摘要：
  • 8.

    【2hr】Frontiers in Probing Alzheimer’s Disease Biomarkerswith Fluorescent Small Molecules

    包量

    机译 探索阿尔茨海默氏病生物标志物的前沿与荧光小分子
    摘要：Alzheimer’s disease (AD) is the most common form of dementia. The pathogenesis of the disease is associated with aggregated amyloid-β, hyperphosphorylated tau, a high level of metal ions, abnormal enzyme activities, and reactive astrocytes. This outlook gives an overview of fluorescent small molecules targeting AD biomarkers for ex vivo and in vivo imaging. These chemical imaging probes are categorized based on the potential biomarkers, and their pros and cons are discussed. Guidelines for designing new sensing strategies as well as the desirable properties to be pursued for AD fluorescence imaging are also provided.
  • 9.

    【2hr】Charge Transport Communication through DNA by Protein Fe–S Clusters: How Far Is Not Too Far?

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    机译 蛋白质Fe–S团簇通过DNA进行电荷传输通信：距离还不远？
    摘要：
  • 10.

    【2hr】Colocalization of m6A and G-Quadruplex-FormingSequences in Viral RNA (HIV, Zika, Hepatitis B, and SV40) SuggestsTopological Control of Adenosine N6-Methylation

    包量

    机译 m6A和G-四链体形成的共定位病毒RNA中的序列（HIV，寨卡病毒，乙型肝炎和SV40）提示腺苷N6-甲基化的拓扑控制
    摘要：This Outlook calls attention to two seemingly disparate and emerging fields regarding viral genomics that may be correlated in a way previously overlooked. First, we describe identification of conserved potential G-quadruplex-forming sequences (PQSs) in viral genomes relevant to human health. Studies have demonstrated that PQSs are highly conserved and can fold to G-quadruplexes (G4s) to regulate viral processes. Key examples include G4s as a countermeasure to the host’s immune system or G4-guided regulation of replication or transcription. Second, emerging data are discussed concerning the epitranscriptomic modification N6-methyladenosine (m6A) in viral RNA installed by host proteins in a consensus sequence favoring 5′-GG(m6A)C-3′. The proposed pathways by which m6A is written, read, and erased in viral RNA genomes and the impact this has on viral replication are described. The structural reason why certain sites are selected for modification while others are not is still mysterious. Finally, we discuss our new observations regarding these previous sequencing data that identifym6A installation within the loops of two-tetrad PQSs inthe RNA genomes of the Zika, HIV, hepatitis B, and SV40 viruses. Wehypothesize that conserved viral PQSs can provide a framework (sequenceand/or structural) for m6A installation. We also discussliterature sources suggesting that PQSs as sites of RNA modificationcould be a general phenomenon. We anticipate our observations willprovide ample opportunities for exciting discoveries regarding theinterplay between G4 structures and epitranscriptomic modificationsof RNA.
  • 11.

    【2hr】Amphiphile-Based Complex Fluids: The Self-AssemblyEnsemble as Protagonist

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    机译 基于两亲物的复杂流体：自组装合奏为主角
    摘要：
  • 12.

    【2hr】Therapeutic Protein PEPylation: The Helix of Nonfouling SyntheticPolypeptides Minimizes AntidrugAntibody Generation

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    机译 治疗性蛋白PEPylation：防污合成螺旋多肽使抗药性降至最低抗体生成
    摘要：Polymer conjugation is a clinically proven approach to generate long acting protein drugs with decreased immune responses. Although poly(ethylene glycol) (PEG) is one of the most commonly used conjugation partners due to its unstructured conformation, its therapeutic application is limited by its poor biodegradability, propensity to induce an anti-PEG immune response, and the resultant accelerated blood clearance (ABC) effect. Moreover, the prevailing preference of unstructured polymers for protein conjugation still lacks strong animal data support with appropriate control reagents. By using two biodegradable synthetic polypeptides with similar structural compositions (l-P(EG3Glu) and dl-P(EG3Glu)) for site-specific protein modification, in the current study, we systematically investigate the effect of the polymer conformation on the in vivo pharmacological performances of the resulting conjugates. Our results reveal that the conjugate l20K-IFN, interferon (IFN) modified with the helical polypeptide l-P(EG3Glu) shows improved binding affinity, in vitro antiproliferative activity, and in vivo efficacy compared to those modified with the unstructured polypeptide analogue dl-P(EG3Glu)or PEG. Moreover, l20K-IFN triggered significantlyless antidrug and antipolymer antibodies than the other two. Importantly,the unusual findings observed in the IFN series are reproduced ina human growth hormone (GH) conjugate series. Subcutaneously infused l20K-GH, GH modified with l-P(EG3Glu), evokes considerably less anti-GH and antipolymer antibodiescompared to those modified with dl-P(EG3Glu) orPEG (dl20K-GH or PEG20K–GH).As a result, repeated injections of dl20K-GH orPEG20K-GH, but not l20K-GH, resultin a clear ABC effect and significantly diminished drug availabilityin the blood. Meanwhile, immature mouse bone marrow cells incubatedwith the helical l20K-GH exhibit decreased druguptake and secretion of proinflammatory cytokines compared to thosetreated with one of the other two GH conjugates bearing unstructuredpolymers. Taken together, the current study highlights an urgent necessityto systematically reassess the pros and cons of choosing unstructuredpolymers for protein conjugation. Furthermore, our results also laythe foundation for the development of next-generation biohybrid drugsbased on helical synthetic polypeptides.
  • 13.

    【2hr】Heme and Nonheme High-Valent Iron and Manganese OxoCores in Biological and Abiological Oxidation Reactions

    包量

    机译 血红素和非血红素高价铁锰氧化物生物和生物氧化反应的核心
    摘要：Utilization of O2 as an abundant and environmentally benign oxidant is of great interest in the design of bioinspired synthetic catalytic oxidation systems. Metalloenzymes activate O2 by employing earth-abundant metals and exhibit diverse reactivities in oxidation reactions, including epoxidation of olefins, functionalization of alkane C–H bonds, arene hydroxylation, and syn-dihydroxylation of arenes. Metal–oxo species are proposed as reactive intermediates in these reactions. A number of biomimetic metal–oxo complexes have been synthesized in recent years by activating O2 or using artificial oxidants at iron and manganese centers supported on heme or nonheme-type ligand environments. Detailed reactivity studies together with spectroscopy and theory have helped us understand how the reactivities of these metal–oxygen intermediates are controlled by the electronic and steric properties of the metal centers. These studies have provided important insights into biological reactions, which have contributed to the design of biologically inspired oxidation catalysts containing earth-abundant metals like iron and manganese. In this Outlook article, we surveya few examples of these advances with particular emphasis in eachcase on the interplay of catalyst design and our understanding ofmetalloenzyme structure and function.
  • 14.

    【2hr】Oligomannose Glycopeptide Conjugates Elicit AntibodiesTargeting the Glycan Core Rather than Its Extremities

    包量

    机译 寡甘露糖糖肽结合有效抗体针对糖核而不是四肢
    摘要：Up to ∼20% of HIV-infected individuals eventually develop broadly neutralizing antibodies (bnAbs), and many of these antibodies (∼40%) target a region of dense high-mannose glycosylation on gp120 of the HIV envelope protein, known as the “high-mannose patch” (HMP). Thus, there have been numerous attempts to develop glycoconjugate vaccine immunogens that structurally mimic the HMP and might elicit bnAbs targeting this conserved neutralization epitope. Herein, we report on the immunogenicity of glycopeptides, designed by in vitro selection, that bind tightly to anti-HMP antibody 2G12. By analyzing the fine carbohydrate specificity of rabbit antibodies elicited by these immunogens, we found that they differ from some natural human bnAbs, such as 2G12 and PGT128, in that they bind primarily to the core structures within the glycan, rather than to the Manα1 → 2Man termini (2G12) or to the whole glycan (PGT128). Antibody specificity for the glycan core may result from extensive serum mannosidase trimming of the immunogen in the vaccinatedanimals. This finding has broad implications for vaccine design aimingto target glycan-dependent HIV neutralizing antibodies.
  • 15.

    【2hr】Energy-Transfer Editing in Lanthanide-Activated UpconversionNanocrystals: A Toolbox for Emerging Applications

    包量

    机译 镧系元素激活的上转换中的能量转移编辑纳米晶体：新兴应用的工具箱
    摘要：Advanced nanoscale synthetic techniques provide a versatile platform for programmable control over the size, morphology, and composition of nanocrystals doped with lanthanide ions. Characteristic upconversion luminescence features originating from the 4f–4f optical transitions of lanthanides can be achieved through predesigned energy transfer pathways, enabling wide applications ranging from ultrasensitive biological detection to advanced spectroscopic instrumentation with high spatiotemporal resolution. Here, we review recent scientific and technological discoveries that have prompted the realization of these peculiar functions of lanthanide-doped upconversion nanocrystals and discuss the mechanistic studies of energy transfer involved in upconversion processes. These advanced schemes include cross relaxation-mediated depletion, multipulse sequential pumping, and nanostructural configuration design. Our emphasis is placed on disruptive technologies such as super-resolution microscopy, optogenetics, nanolasing, and optical anticounterfeiting, which take full advantage of the upconversion nanophenomena in relation to lanthanide-dopednanocrystals.
  • 16.

    【2hr】Injectable Slippery Lubricant-Coated Spiky Microparticleswith Persistent and Exceptional Biofouling-Resistance

    包量

    机译 可注射的滑涂润滑剂的尖刺微粒持久且出色的生物污染阻力
    摘要：Injectable micron-sized particles have historically achieved promising applications, but they continued to suffer from long-term biofouling caused by the adhesions of biomolecules, cells, and bacteria. Recently, a slippery lubricant infusion porous substrate (SLIPS) exhibited robust antiadhesiveness against many liquids; however, they were constructed using a 2D substrate, and they were not suitable for in vivo applications, such as injectable biomaterials. Inspired by SLIPS, here, we report the first case of injectable solid microparticles coated with a lubricating liquid surface to continuously resist biofouling. In our design, microparticles were attached with nanospikes and fluorinated to entrap the lubricant. The nanospikes enabled the lubricant-coated spiky microparticles (LCSMPs) to anomalously disperse in water despite the attraction between the surfaces of the microparticles. This result indicated that the LCSMPs exhibited persistent anomalous dispersity in water while maintaining a robust lubricating surface layer. LCSMPs prevented the adhesion of proteins, mammalian cells, and bacteria, including Escherichia coli and Staphylococcusaureus. LCSMPs also reduced in vivo fibrosiswhile conventional microparticles were heavily biofouled. This technologyintroduced a new class of injectable anti-biofouling microparticleswith reduced risks of inflammation and infections.
  • 17.

    【2hr】Lipid-Dependent Alternating Access Mechanism of aBacterial Multidrug ABC Exporter

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    机译 脂质依赖的交替访问机制细菌多药ABC出口商
    摘要：By undergoing conformational changes, active membrane transporters alternate between an inward-facing (IF) and an outward-facing (OF) state to transport their substrates across cellular membrane. The conformational landscape of membrane transporters, however, could be influenced by their environment, and the dependence of the alternating access mechanism on the lipid composition has not been understood at the molecular level. We have performed an extensive set of microsecond-level all-atom molecular dynamics (MD) simulations on bacterial ATP binding cassette (ABC) exporter Sav1866 in six different phosphocholine (PC) and phosphoethanolamine (PE) lipid membrane environments. This study mainly focuses on the energetically downhill OF-to-IF conformational transition of Sav1866 upon the ATP hydrolysis. We observe that the transporter undergoes large-scale conformational changes in the PE environment, particularly in the POPE lipids, resulting in an IF-occluded conformation, a transition that does not occur when the transporter is embedded in any of the PC lipid bilayers. We propose that the PElipids facilitate the closing of the protein on the periplasmic sidedue to their highly polar headgroups that mediate the interactionof the two transmembrane (TM) bundles by a network of lipid–lipidand lipid–protein hydrogen bonds. POPE lipids in particularfacilitate the closure of periplasmic gate by promoting a hinge formationin TM helices and an interbundle salt bridge formation. This studyexplains how the alternating access mechanism and the flippase activityin ABC exporters could be lipid-dependent.
  • 18.

    【2hr】Computational Evolution of Threonine-Rich β-HairpinPeptides Mimicking Specificity and Affinity of Antibodies

    包量

    机译 苏氨酸丰富的β-发夹的计算进化模仿抗体特异性和亲和力的肽
    摘要：The development of recognition molecules with antibody-like properties is of great value to the biotechnological and bioanalytical communities. The recognition molecules presented here are peptides with a strong tendency to form β-hairpin structures, stabilized by alternate threonines, which are located at one face of the peptide. Amino acids at the other face of the peptide are available for interaction with the target molecule. Using this scaffold, we demonstrate that recognition molecules can efficiently be designed in silico toward four structurally unrelated proteins, GFP, IL-1β, IL-2, and IL-6. On solid support, 10 different antibody-mimetic recognition molecules were synthesized. They displayed high affinity and no cross-reactivity, as observed by fluorescence microscopy. Stabilized variants were readily obtained by incorporation of azido acids and propargylglycine followed by cyclization via the Cu(I)-catalyzed alkyne–azide cycloaddition reaction. As this new class of antibody mimics can be designed toward essentially any protein, the concept is believed to be useful to a wide range of technologies.Here, their use in protein separation and in the detection of proteinsin a sandwich-type assay is demonstrated.
  • 19.

    【2hr】Transferable Machine-Learning Model of the ElectronDensity

    包量

    机译 电子的可转移机器学习模型密度
    摘要：The electronic charge density plays a central role in determining the behavior of matter at the atomic scale, but its computational evaluation requires demanding electronic-structure calculations. We introduce an atom-centered, symmetry-adapted framework to machine-learn the valence charge density based on a small number of reference calculations. The model is highly transferable, meaning it can be trained on electronic-structure data of small molecules and used to predict the charge density of larger compounds with low, linear-scaling cost. Applications are shown for various hydrocarbon molecules of increasing complexity and flexibility, and demonstrate the accuracy of the model when predicting the density on octane and octatetraene after training exclusively on butane and butadiene. This transferable, data-driven model can be used to interpret experiments, accelerate electronic structure calculations, and compute electrostatic interactions in molecules and condensed-phase systems.
  • 20.

    【2hr】A Biocatalytic Platform for Synthesis of Chiral α-Trifluoromethylated Organoborons

    包量

    机译 合成手性α-三氟甲基化有机硼的生物催化平台。
    摘要：There are few biocatalytic transformations that produce fluorine-containing molecules prevalent in modern pharmaceuticals. To expand the scope of biocatalysis for organofluorine synthesis, we have developed an enzymatic platform for highly enantioselective carbene B–H bond insertion to yield versatile α-trifluoromethylated (α-CF3) organoborons, an important class of organofluorine molecules that contain stereogenic centers bearing both CF3 and boron groups. In contrast to current “carbene transferase” enzymes that use a limited set of simple diazo compounds as carbene precursors, this system based on Rhodothermus marinus cytochrome c (Rma cyt c) can accept a broad range of trifluorodiazo alkanes and deliver versatile chiral α-CF3 organoborons with total turnovers up to 2870 and enantiomeric ratios up to 98.5:1.5. Computational modeling reveals that this broad diazo scope is enabled by an active-site environment that directs the alkyl substituent on the heme CF3-carbene intermediate toward the solvent-exposed face, thereby allowing the protein to accommodate diazo compounds with diverse structural features.
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