Stable Linkage Research Articles

High-Voltage-Tolerant Covalent Organic Framework Electrolyte with Holistically Oriented Channels for Solid-State Lithium Metal Batteries with Nickel-Rich Cathodes.

By introducing lithiophilic groups and electrochemically stable quinolyl aromatic ring linkages, we prepared covalent organic frameworks (COFs) exhibiting a large band gap with an ultralow HOMO value (-6.2 eV under vacuum) and oxidative stability up to 5.6 V (versus Li+ /Li) as solid-state electrolytes (SSEs). The obtained flexible COF SSE thin films showed a holistically oriented arrangement along the (001) facet with remarkable ionic conductivity up to 1.5×10-4 S cm-1 at 60 °C and excellent mechanical strength with a high Young's modulus of 10.5 GPa. Molecular dynamic simulations showed that lithium ions are transmitted in this COF SSE by directional hopping paths with fast drift velocity. The COF SSE film was used to assemble all-solid-state lithium metal batteries with nickel-rich cathodes (NMC811). The batteries demonstrated stable cycling performance over 400 cycles, high coulombic efficiency (>99 %), and could also withstand abuse tests, such as folding.

High‐Voltage‐Tolerant Covalent Organic Framework Electrolyte with Holistically Oriented Channels for Solid‐State Lithium Metal Batteries with Nickel‐Rich Cathodes

AbstractBy introducing lithiophilic groups and electrochemically stable quinolyl aromatic ring linkages, we prepared covalent organic frameworks (COFs) exhibiting a large band gap with an ultralow HOMO value (−6.2 eV under vacuum) and oxidative stability up to 5.6 V (versus Li+/Li) as solid‐state electrolytes (SSEs). The obtained flexible COF SSE thin films showed a holistically oriented arrangement along the (001) facet with remarkable ionic conductivity up to 1.5×10−4 S cm−1 at 60 °C and excellent mechanical strength with a high Young's modulus of 10.5 GPa. Molecular dynamic simulations showed that lithium ions are transmitted in this COF SSE by directional hopping paths with fast drift velocity. The COF SSE film was used to assemble all‐solid‐state lithium metal batteries with nickel‐rich cathodes (NMC811). The batteries demonstrated stable cycling performance over 400 cycles, high coulombic efficiency (>99 %), and could also withstand abuse tests, such as folding.

An Ionic Liquid Medium Enables Development of a Phosphine-Mediated Amine-Azide Bioconjugation Method.

While a diverse set of design strategies have produced various chemical tools for biomolecule labeling in aqueous media, the development of nonaqueous, biomolecule-compatible media for bioconjugation has significantly lagged behind. In this report, we demonstrate that an aprotic ionic liquid serves as a novel reaction solvent for protein bioconjugation without noticeable loss of the biomolecule functions. The ionic liquid bioconjugation approach led to discovery of a novel triphenylphosphine-mediated amine-azide coupling reaction that forges a stable tetrazene linkage on unprotected peptides and proteins. This strategy of using untraditional media would provide untapped opportunities for expanding the scope of chemical approaches for bioconjugation.

An Overview of Recent Advances in Biomedical Applications of Click Chemistry.

Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is a modular and bio-orthogonal approach that is being adopted for the efficient synthesis of organic and bioorganic compounds. It leads to the selective formation of 1,4-disubstituted 1,2,3-triazole units connecting readily accessible building blocks via a stable and biocompatible linkage. The vast array of the bioconjugation applications of click chemistry has been attributed to its fast reaction kinetics, quantitative yields, minimal byproducts, and high chemospecificity and regioselectivity. These combined advantages make click reactions quite suitable for the lead identification and the development of pharmaceutical agents in the fields of medicinal chemistry and drug discovery. In this review, we have outlined the key aspects, the mechanistic details and merits and demerits of the click reaction. In addition, we have also discussed the recent pharmaceutical applications of click chemistry, ranging from the development of anticancer, antibacterial, and antiviral agents to that of biomedical imaging agents and clinical therapeutics.

Flavin-tag: A Facile Method for Site-Specific Labeling of Proteins with a Flavin Fluorophore.

Site-specific protein labeling methods are highly valuable tools for research and applications. We present a new protein labeling method that allows covalent attachment of a chromo- and fluorogenic flavin (FMN) to any targeted protein using a short flavinylation peptide-tag. We show that this peptide can be as short as 7 residues and can be located at the N-terminus, C-terminus, or in internal regions of the target protein. Analogous to kinase-catalyzed phosphorylation, the flavin is covalently attached via a stable phosphothreonyl linkage. The site-specific covalent tethering of FMN is accomplished by using a bacterial flavin transferase. The covalent coupling of FMN was shown to work in Escherichia coli and Saccharomyces cerevisiae cells and could be performed in vitro, rendering the "Flavin-tag" method a powerful tool for the selective decoration of proteins with a biocompatible redox-active fluorescent chromophore.

Reverse-twisting of helicoidal shells to obtain neutrally stable linkage mechanisms

Mechanisms that consist of many elements and are potentially small sized, benefit from kinematic elementary units like revolute joints that are compliant and monolithic, and therefore could be produced without need for assembly. We present a novel concept of a compliant revolute joint that features low axis drift, high support stiffness and a large range of motion. The concept is based on a helicoidal shell of which a portion reverses its twist direction upon application of a rotation. The reversed region increases gradually, resulting in a constant reaction moment. Analytical, numerical, and experimental analyses are presented to reveal and quantify the constant-moment behaviour. Prototypes of the concept are employed in exemplary linkages to demonstrate the ability to create a large variety of neutrally stable compliant linkages, which require extremely low actuation forces and exhibit large ranges of motion.

Air-ozonolysis activation of polyolefins versus use of laden finishing to form contact-active nonwoven materials

Two synthetic approaches were explored for modification of the polyolefins polyethylene/polypropylene (PE/PP) to form contact-active nonwoven materials. In the first approach, polymer surfaces were activated by O2-free air-ozonolysis, and then the active agent (trimethoxysilyl) propyl-octadecyl-dimethyl-ammonium chloride (C18-TSA) was covalently bound. In the second approach, the active agent was directly conjugated to the commercial ‘finishing’ that was then applied to the polymer. The chemical, physical and microscopic properties of the modified polymers were comprehensively studied, and their active site density was quantified by fluorescein sodium salt-cetyltrimethylammonium chloride reaction. The antimicrobial activity of the prepared nonwovens against Bacillus subtilis (Gram-positive) and Salmonella enterica (Gram-negative), and their stability at various pHs and temperatures were examined. The two approaches conferred antimicrobial properties to the modified polymers and demonstrated stable linkage of C18-TSA. However, the performance of the nonwovens formed by the first approach was superior. The study suggests two feasible and safe pathways for the modification of polyolefins to form contact-active nonwoven materials that can be further applied in various fields, such as hygiene products, medical fabrics, sanitizing wipes, and more.

Anti-Periprosthetic Infection Strategies: From Implant Surface Topographical Engineering to Smart Drug-Releasing Coatings.

Despite advanced implant sterilization and aseptic surgical techniques, periprosthetic bacterial infection remains a major challenge for orthopedic and dental implants. Bacterial colonization/biofilm formation around implants and their invasion into the dense skeletal tissue matrices are difficult to treat and could lead to implant failure and osteomyelitis. These complications require major revision surgeries and extended antibiotic therapies that are associated with high treatment cost, morbidity, and even mortality. Effective preventative measures mitigating risks for implant-related infections are thus in dire need. This review focuses on recent developments of anti-periprosthetic infection strategies aimed at either reducing bacterial adhesion, colonization, and biofilm formation or killing bacteria directly in contact with and/or in the vicinity of implants. These goals are accomplished through antifouling, quorum-sensing interfering, or bactericidal implant surface topographical engineering or surface coatings through chemical modifications. Surface topographical engineering of lotus leaf mimicking super-hydrophobic antifouling features and cicada wing-mimicking, bacterium-piercing nanopillars are both presented. Conventional physical coating/passive release of bactericidal agents is contrasted with their covalent tethering to implant surfaces through either stable linkages or linkages labile to bacterial enzyme cleavage or environmental perturbations. Pros and cons of these emerging anti-periprosthetic infection approaches are discussed in terms of their safety, efficacy, and translational potentials.

Mechanism of deformation in rock mass surrounding intersection of mine shaft and salt bed

A bed of rock salt in Komsomolsky Mine occurs in sedimentary strata enclosing cage and skip shafts. When water enters rock salt via underground excavations, boreholes and fractures, rock salt can dissolve and wash out, and voids appear in rock mass. Voids at the lining and rock interface should be eliminated so that never re-appear or grow during shaft operation. Materials used to eliminate voids should ensure stable mechanical linkage both with enclosing rocks and lining. Assessment and analysis of geomechanical processes induced by leaching need monitoring of deformations in a shaft. To this effect, one of the simplest and most informative methods is arrangement of an observation station directly in the shaft lining to measure varying distances between check points. The article briefly describes activities aimed to eliminate voids using different composition grouts. From the analysis of monitoring data, the deformation mechanism is described, and the interaction between different deformation stages and grouting steps is determined. The authors appreciate participations of experts M. P. Sergunin, I. A. Shishkina, A. K. Ustinov, V. V. Tsatskin, V. S. Orlov.

Реализация структуры прецедентного имени (на примере имён персонажей драмы У. Шекспира «Макбет» в Британском национальном корпусе и корпусе современного американского английского языка)

The article aims to investigate the peculiarities of the precedent name structure actualization on the material of the British National Corpus and the Corpus of Contemporary American English. Such components of the precedent name structure as relevant features (appearance, character, precedent situation) and attributes are under analysis. The frequency of the reference to each component of the precedent name structure has been calculated. It turned out that the precedent names of Shakespeare's “Macbeth” are most often actualized through the connection with the precedent situation and the least often – through character. 3 types of connections were identified between the precedent name and a proper name as its source: 1) full similarity of appearance / character / precedent situation between the original text and modern fiction from the corpora; 2) partial similarity of the features; 3) imaginativeness of the features. It has been discovered that when there is no direct connection between the appearance / character / precedent situation / attribute of the bearer of a precedent name and the bearer of the original proper name, the meaningful recurrence of a precedent name is ensured by a stable associative linkage and the invariant evaluation.

Nitrosyl linkage photoisomerization in heteroleptic fluoride ruthenium complexes derived from labile nitrate precursors

Four complexes with trans-ON–Ru–F coordinate were synthesized from their nitrate precursors. Upon light irradiation, complexes I–III show reversible formation of highly stable linkage isomers MS2 which leads to a higher photogeneration temperature of MS1.

Surface molecular design of organic–inorganic mesoporous hybrid materials for CO2 capture

In the present work, a series of organic–inorganic hybrids was designed by using different solvents on 3-aminopropyltriethoxysilane (APTS) grafting on SBA-15. Different characterization techniques were used to evaluate how distinct solvents drive the surface architecture, amine loading, APTS-SBA-15 linkage configuration, surface area and pore volume. FT-IR and 29Si MAS NMR confirmed APTS grafting on SBA-15 surface. Elemental analysis showed that N loading varied from 2.09% up to 5.21%, while the range of C/N ratios (2.69–4.34) indicated that the number of bonds formed between APTS and SBA-15 (linkage configuration) remained between 2 (C/N = 4.3) and 3 (C/N = 2.6). N2 physisorption and TGA data showed that textural properties and APTS content on the synthesized materials were simultaneously dependent on N loading and linkage configuration. The presented data showed that the hybrids properties can be correlated with the solvent polarity, more specifically with the interaction between the inorganic matrix surface and the solvent during grafting. A new approach was presented using the solvent eluent strength to rationalize such correlation. Among all tested solvents, cyclohexane rendered the adsorbent with the highest N loading (5.21%) and more stable linkage configuration (C/N = 4.34). CO2 capture tests showed that the increase of amine loading and surface density improves not only the hybrid capacity to chemisorb CO2, but also its adsorption efficiency. CO2 capture capacities varied from 25 up to 516 µmol CO2 g−1. The correlation between adsorption capacity and N content for the synthesized APTS-SBA-15 hybrids was best fitted by a power function.

Land Financialization, Uncoordinated Development of Population Urbanization and Land Urbanization, and Economic Growth: Evidence from China

In recent years, it has become common practice for Chinese local governments to inject land assets into financing platform companies and use them as mortgage or credit guarantees to obtain bank loans and issue urban investment bonds, which is known as “land financialization”. This study investigates the impact and mechanism of land financialization on the uncoordinated development of population urbanization and land urbanization in China. Theoretical analysis and empirical analysis results based on the data of prefecture-level cities in China from 2006 to 2015 demonstrate that land financialization by local governments is a significant cause of the uncoordinated development of population urbanization and land urbanization, and the pressure of urban economic development will strengthen this negative impact. Extended analysis further reveals that in areas where population urbanization and land urbanization are uncoordinated, land financialization, while promoting urban spatial expansion, will lower land use efficiency and have an inverted U-shaped influence on economic growth due to a weak agglomeration effect. The above conclusion shows that urbanization driven by debt-based investment is unsustainable. Efforts should be made to establish a financialization system that propels sound urbanization and to build a stable input linkage between land financialization and the supply of urban public service.

Bamboo like SiC Nanowires Grown in a Dual-Temperature Zone Reaction System Enhance the Oxidation and Thermal Shock Resistance of SiC Coatings

The life of high temperature coating mainly depends on its oxidation resistance and bonding strength with the substrate. SiCnws / SiC coatings were prepared by a self-made two temperature reaction system and chemical vapor deposition method. The oxidation resistance of the composite coating at 900 ℃ and 1500 ℃ and the thermal shock resistance at 1500 ℃ were studied. The fracture toughness and bonding strength of the composite coating were increased by 53.8% and 9.8 times, respectively, due to the stable mechanical linkage effect between the bamboo like SiC nanowires with special nodes and SiC. Due to the healing effect of glass phase SiO2, the weight loss rate of bamboo like SiCnws / SiC coating sample after oxidation at 900 ℃ for 30 h is about 5.28%, and that after isothermal oxidation at 1500 ℃ for 60 h is only 0.74%. In addition, bamboo like SiCnws can effectively alleviate the thermal expansion coefficient mismatch between SiC coating and substrate. After 25 thermal shock cycles, the final oxidation weight loss rate of composite coating is only 2.03%.

A rational entry to cyclic polymers via spontaneous and selective cyclization reactions

This focus review describes the status quo of synthetic routes to cyclic compounds and cyclic polymers via spontaneous cyclization processes using (1) rotaxane chemistry and (2) dynamic covalent chemistry. Systems with rotaxane-based structures undergo spontaneous and selective cyclization of two self-complementary molecules and a macromolecular rotaxane switch, where the relative position of each component can be controlled, which results in a topology change from linear to cyclic. Systems based on dynamic covalent chemistry use exchange reactions of bis(2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS) units that behave as stable linkages at r.t. and exchange disulfide bonds upon heating. Controlling the dynamic nature of BiTEMPS-based low-molecular-weight compounds and polymers thus provides cyclic topologies via spontaneous and selective cyclization processes. This focus review describes the synthetic routes to cyclic compounds and cyclic polymers via spontaneously occurring cyclization processes using (1) rotaxane chemistry and (2) dynamic covalent chemistry. Systems with rotaxane-based structures proceed via the spontaneous and selective cyclization of two self-complementary molecules and a macromolecular rotaxane switch, which results in a topology change from linear to cyclic. Systems based on dynamic covalent chemistry use exchange reactions of bis(2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS) units. Controlling the dynamic nature of BiTEMPS-based molecules provides cyclic topologies via spontaneously and selectively occurring cyclization processes.

Endothelialization of PDMS-based microfluidic devices under high shear stress conditions

Microfluidic systems made out of polydimethylsiloxane (PDMS) offer a platform to mimic vascular flow conditions in model systems at well-defined shear stresses. However, extracellular matrix (ECM) proteins that are physisorbed on the PDMS are not reliably attached under high shear stress conditions, which makes long-term experiments difficult. To overcome this limitation, we functionalized PDMS surfaces with 3-aminopropyltriethoxysilane (APTES) by using different surface activation methods to develop a stable linkage between the PDMS surface and collagen, which served as a model ECM protein. The stability of the protein coating inside the microfluidic devices was evaluated in perfusion experiments with phosphate-buffered saline (PBS) at 10−40 dynes/cm2 wall shear stress. To assess the stability of cell adhesion, endothelial cells were grown in a multi-shear device over a shear stress range of 20−150 dynes/cm2. Cells on the APTES-mediated collagen coating were stable over the entire shear stress range in PBS (pH 9) for 48 h. The results suggest that at high pH values, the electrostatic interaction between APTES-coated surfaces and collagen molecules offer a very promising tool to modify PDMS-based microfluidic devices for long-term endothelialization under high shear stress conditions.

Serine-Selective Bioconjugation.

This Communication reports the first general method for rapid, chemoselective, and modular functionalization of serine residues in native polypeptides, which uses a reagent platform based on the P(V) oxidation state. This redox-economical approach can be used to append nearly any kind of cargo onto serine, generating a stable, benign, and hydrophilic phosphorothioate linkage. The method tolerates all other known nucleophilic functional groups of naturally occurring proteinogenic amino acids. A variety of applications can be envisaged by this expansion of the toolbox of site-selective bioconjugation methods.

Beyond the Interweb

A discussion of the BangleJS watch is the launching point for a discussion of the need to have networks not be tied to their topologies and hardware. It is argued that once we understand best-efforts and recognize that we do not need special-networks, we are ready to embrace the potential. We get abundant opportunity to innovate. We need stable linkages rather than domain names that expire every year. The IEEE can take a concrete step in that direction by offering names that are stable, like bit.ly does, but for devices. Perhaps an IoT.IEEE domain. We need to pay for the facilities as common infrastructure rather than depending upon a provider making a profit by limiting transport to subscribers in good standing. We need protocols that are transparent rather than ones like Bluetooth. By taking a user-centric view and creating a simple experience we now take video conferencing for granted. Let us heed this lesson and move on rather than be limited by network-centric thinking.

Recent advances in the acid-catalyzed conversion of lignin

As the only natural aromatic high molecular compound that was obtained from a renewable resource, lignin is resistant to conversion due to its complex structure and stable linkages. The catalytic conversion of lignin via acid catalysts leading to a high yield of phenolic monomers has gained great interest due to its potential for producing biofuels and chemicals. However, up to now, the acid-catalyzed conversion of lignin has not yet been comprehensively summarized. In order to fill this gap, mechanism analysis and influential factors of the acid catalysis process and the latest studies and advancements on the catalytic conversion of lignin via various types of acid catalysts, such as mineral acids, organic acids, acidic ionic liquids, immobilized liquid acids, metal salts, metal oxides, heteropoly acids, and zeolites, are systematically outlined and discussed. Although many exciting results have been achieved, the sufficient utilization of lignin by this technology still faces enormous challenges. To improve the technical feasibility, intensive investigations on improving the solubility, catalytic activity, stability, reusability, and designability of the acid catalysts are crucially important and imperative.

Targeted self-destruction.

Altered glycosylation helps cancer cells evade immune destruction, and targeted remodeling of glycans in vivo offers the ability to reprogram immune responses. A stable chemical linkage between an antibody and neuraminidase enables the targeted destruction of self-associated sialic acids to enhance antitumor immunity.