General Route Research Articles

Recrystallization‐Induced Laser Lift‐Off Strategy for Flexible Thermal Sensors with Near‐Limit Sensitivity

AbstractFlexible thermal sensors have attracted immense interest as an alternative to conventional rigid sensors in personal healthcare monitoring, biomedical applications, and human‐machine interaction. However, most metal‐based flexible thermal sensors exhibit low sensitivity, primarily resulting from electron scattering due to manufacturing defects. The heat‐intolerant polymer substrate hinders the pathway to improve the sensitivity of metal thin films through high‐temperature annealing. Herein, a recrystallization‐induced laser lift‐off strategy is proposed to overcome the contradiction between the flexible substrate and high‐temperature annealing. Systematically theoretical and experimental studies reveal the mechanism of thermal‐induced recrystallization in increasing the temperature coefficient of resistance (TCR) and the separation of sensors from rigid substrates. Valuable insights are acquired in the modulation of interface adhesion by altering the surface roughness of nickel. A critical temperature is provided to guide the detachment of the sensor. The fabricated thin‐film flexible thermal sensor achieves a TCR of 6.2‰°C−1, approaching the TCR limit of bulk material. This strategy opens a new general route for fabricating high‐temperature annealed sensors on flexible substrates.

Dynemicin A Derivatives as Potential Cancer Chemotherapeutics by Mutasynthesis.

The enediyne antitumor antibiotics have remarkable structures and exhibit potent DNA cleavage properties that have inspired continued interest as cancer therapeutics. Their complex structures and high reactivity, however, pose formidable challenges to their production and development in the clinic. We report here proof-of-concept studies using a mutasynthesis strategy to combine chemical synthesis of select modifications to a key iodoanthracene-γ-thiolactone intermediate in the biosynthesis of dynemicin A and all other known anthraquinone-fused enediynes (AFEs). By chemical complementation of a mutant bacterial producer that is incapable of synthesizing this essential building block, we show that derivatives of dynemicin can be prepared substituted in the A-ring of the anthraquinone motif. In the absence of competition from native production of this intermediate, the most efficient utilization of these externally-supplied structural analogues for precursor-directed biosynthesis becomes possible. To achieve this goal, we describe the required Δorf15 blocked mutant and a general synthetic route to a library of iodoanthracene structural variants. Their successful incorporation opens the door to enhancing DNA binding and tuning the bioreductive activation of the modified enediynes for DNA cleavage.

Regioselective Growth of Colloidal Crystals Induced by Depletion Attraction.

Colloidal crystals display photonic stopbands that generate reflective structural colors. While micropatterning offers significant value for various applications, the resolution is somewhat limited for conventional top-down approaches. In this work, a simple, single-step bottom-up approach is introduced to produce photonic micropatterns through depletion-mediated regioselective growth of colloidal crystals. Lithographically-featured micropatterns with planar surfaces and nano-needle arrays as substrates are employed. Heterogeneous nucleation is drastically suppressed on nano-needle arrays due to minimal particle-to-needles overlap of excluded volumes, while it is promoted on planar surfaces with large particle-to-plane volume overlap, enabling regioselective growth of colloidal crystals. This strategy allows high-resolution micropatterning of colloidal photonic crystals, with a minimum feature size as small as 10 µm. Stopband positions, or structural colors, are controllable through concentration and depletant and salt, as well as particle size. Notably, secondary colors can be created through structural color mixing by simultaneously crystallizing two different particle sizes into their own crystal grains, resulting in two distinct reflectance peaks at controlled wavelengths. The simple and highly reproducible method for regioselective colloidal crystallization provides a general route for designing elaborate photonic micropatterns suitable for various applications.

HD‐Net: A hybrid dynamic spatio‐temporal network for traffic flow prediction

AbstractAccurately predicting traffic flow is crucial for intelligent transportation systems (ITS). In recent years, many deep learning‐based prediction models have been widely applied in traffic flow prediction, and various spatio‐temporal networks have been proposed. However, most of the existing models follow a general technical route to extract the spatio‐temporal features, which lack the capacity of extracting the important historical information with the high spatial and temporal correlations dynamically and deeply. How to develop a well‐performance traffic flow prediction model for a complex transportation network is still facing some challenges. In this paper, a hybrid dynamic spatio‐temporal network (HD‐Net) for traffic flow prediction is proposed. In HD‐Net, the authors first extract the dynamic spatio‐temporal features using dynamic graph convolution and bidirectional gate recurrent uni (BiGRU). Subsequently, the authors extract the important features with high spatial and temporal correlations from the obtained dynamic spatio‐temporal features using an auto‐correlation mechanism from a local perspective, and self‐attention mechanism from a global perspective, respectively. Extensive experiments have been conducted on two real‐world traffic datasets. The experimental results demonstrate that the proposed HD‐Net outperforms the baselines in the field of capturing the dynamic and important spatio‐temporal features with high correlations.

Probing fractional statistics in quantum simulators of spin liquid Hamiltonians

Recent advances in programmable quantum devices brought to the fore the intriguing possibility of using them to realise and investigate topological quantum spin liquid phases. This new and exciting direction brings about important research questions on how to probe and determine the presence of such exotic, highly entangled phases in a noisy quantum environment. One of the most promising tools is investigating the behaviour of the topological excitations, and in particular their fractional statistics. In this work we put forward a generic route to achieve this, and we illustrate it in the specific case of \mathbb{Z}_2ℤ2 topological spin liquids implemented with the aid of combinatorial gauge symmetry. We design a convenient architecture to study signatures of fractional statistics via quasiparticle interferometry, and we assess its robustness to diagonal and off-diagonal disorder, as well as to dephasing - effects that are generally pervasive in current quantum programmable devices. Interestingly, when turned on its head, our scheme provides a remarkably clear test of the “quantumness” of these devices, with robust signatures that crucially hinge on quantum coherence and quantum interference effects, and cannot be mimicked by classical stochastic processes.

Ligating Catalytically Active Peptides onto Microporous Polymers: A General Route Toward Specifically-Functional High Surface Area Platforms.

A versatile post-synthetic modification strategy to functionalize a high surface area microporous network (MPN-OH) by bio-orthogonal inverse electron-demand Diels-Alder (IEDDA) ligation is presented. While the polymer matrix is modified with a readily accessible norbornene isocyanate (Nor-NCO), a series of functional units presenting the robust asymmetric 1,2,4,5-tetrazine (Tz) allows easy functionalization of the MPN by chemoselective Nor/Tz ligation. A generic route is demonstrated, modulating the internal interfaces by introducing carboxylates, amides or amino acids as well as an oligopeptide d-Pro-Pro-Glu organocatalyst. The MPN-Pz-Peptide construct largely retains the catalytic activity and selectivity in an enantioselective enamine catalysis, demonstrates remarkable availability in different solvents, offers heterogeneous organocatalysis in bulk and shows stability in recycling settings.

Synthesis and investigation of mixed Zn–Ni spinel nanoparticles for microwave applications

Nickel ferrite solid solutions remain one of the main materials for a whole range of applications, including microwave equipment and components, the requirements for parameters and homogeneity of materials are constantly increasing. In this work, Ni1–xZnxFe2O4 nanoparticles with an average diameter of 12.5 nm were successfully synthesized by the microwave-assisted urea method. The temperature of a single-phase product formation was 400 °C, which is lower compared to more common precipitation from aqueous solution methods or solid-state route. Ni1–xZnxFe2O4 materials demonstrate high saturation magnetization and low coercive force. The magnetization changes with increasing Zn concentration and reaches the maximum at x = 0.5. Also, the increase in zinc content leads to an increase in the lattice parameters. The average size of ferrite nanoparticles synthesized by the microwave-assisted urea method is smaller compared to ferrites synthesized earlier by the co-precipitation method. Also, lower treatment temperatures provide higher stoichiometry, and homogeneity of materials while magnetization difference is negligible. These research results provide a general and effective route to synthesize other nanostructures for a variety of microwave components.

Unprecedented, catalyst‐free, and rapid one‐pot, three‐component green synthesis of substituted 3‐hydroxy‐2‐oxindoles in water

AbstractAn efficient, unprecedented, catalyst‐free, and rapid synthesis of substituted 3‐hydroxy‐2‐oxindoles is described by the one‐pot, three‐component reaction of hydrazine hydrate, ethyl acetoacetate, and isatins in water. The reported protocol is a green and general route for the simple preparation of new heteroaromatic substituted 3‐hydroxy‐2‐oxindoles in quantitative yields under very mild reaction conditions by using simple, cheap, and readily available materials. The developed method is effectively applicable to a variety of isatin substrates. Operational simplicity, mild and greener reaction conditions, short reaction time, a wide scope of substrates, good isolated yields of the products, and environmentally benign reaction medium are the distinctive features of the present method.

Controlled-Radical Polymerization of α-Lipoic Acid: A General Route to Degradable Vinyl Copolymers.

Here, we present the synthesis and characterization of statistical and block copolymers containing α-lipoic acid (LA) using reversible addition-fragmentation chain-transfer (RAFT) polymerization. LA, a readily available nutritional supplement, undergoes efficient radical ring-opening copolymerization with vinyl monomers in a controlled manner with predictable molecular weights and low molar-mass dispersities. Because lipoic acid diads present in the resulting copolymers include disulfide bonds, these materials efficiently and rapidly degrade when exposed to mild reducing agents such as tris(2-carboxyethyl)phosphine (Mn = 56 → 3.6 kg mol-1). This scalable and versatile polymerization method affords a facile way to synthesize degradable polymers with controlled architectures, molecular weights, and molar-mass dispersities from α-lipoic acid, a commercially available and renewable monomer.

Flash-Thermal Shock Synthesis of Single Atoms in Ambient Air.

Single-atom catalysts feature interesting catalytic activity toward applications that rely on surface reactions such as electrochemical energy storage, catalysis, and gas sensors. However, conventional synthetic approaches for such catalysts require extended periods of high-temperature annealing in vacuum systems, limiting their throughput and increasing their production cost. Herein, we report an ultrafast flash-thermal shock (FTS)-induced annealing technique (temperature > 2850 °C, <10 ms duration, and ramping/cooling rates of ∼105 K/s) that operates in an ambient-air environment to prepare single-atom-stabilized N-doped graphene. Melamine is utilized as an N-doping source to provide thermodynamically favorable metal-nitrogen bonding sites, resulting in a uniform and high-density atomic distribution of single metal atoms. To demonstrate the practical utility of the single-atom-stabilized N-doped graphene produced by the FTS method, we showcased their chemiresistive gas sensing capabilities and electrocatalytic activities. Overall, the air-ambient, ultrafast, and versatile (e.g., Co, Ni, Pt, and Co-Ni dual metal) FTS method provides a general route for high-throughput, large area, and vacuum-free manufacturing of single-atom catalysts.

Universal pathway towards metal sulfides decorated 3D porous Ti3C2Tx MXene aerogel for vapor-phase mercury removal

Utilization of monolithic mineral sulfide-based sorbent for the fix-bed elemental mercury (Hg0) removal is regarded as a predominant predicament in the field of Hg0 abatement. In this work, a general and facile route was exploited to establish CuS particles decorated 3D porous Ti3C2Tx MXene aerogel via divalent Cu2+ cations induced assembly combined with subsequent high-temperature sulfurization treatment, during which, uniform CuS particles were homogeneously anchored throughout the Ti3C2Tx substrate. The obtained 3D CuS/Ti3C2Tx MXene aerogel exhibited satisfactory textural property, hierarchical pore structure and strong interaction between Ti3C2Tx MXene and CuS. Meanwhile, the inherent restacking of Ti3C2Tx MXene nanosheet and serious agglomeration of CuS can also be effectively avoided in the formation of aerogel. Those structural advantages originating from this novel gelation process favorably contributes to satisfactory Hg0 mass transfer and sufficient utilization of CuS active ligands, which largely strengthens Hg0 removal performance and broadens the fix-bed application of mineral sulfides. Consequently, the Hg0 capture capacity and adsorption rate of CuS/Ti3C2Tx MXene aerogel reached 90596.4 g m−3 and 120.64 g m−3 min−1, respectively, far outbalancing those of the reported in-situ selenized copper foam with excellent Hg0 removal activity. The impressive Hg0 sequestration performance is attributed to its relatively large specific surface area, layered pore channel, and highly dispersed CuS particles, largely boosting Hg0 mass transfer and following sequestration. Moreover, other mineral sulfides/Ti3C2Tx MXene aerogels can also be constructed by just replacing divalent metal cations, which makes the initial effort towards the fix-bed utilization of mineral sulfides-based aerogel for vapor-phase Hg0 immobilization.

Stochastic analysis of chemical reactions in multi-component interacting systems at criticality

We numerically and analytically investigate the behavior of a non-equilibrium phase transition in the second Schlögl autocatalytic reaction scheme. Our model incorporates both an interaction-induced phase separation and a bifurcation in the reaction kinetics, with these critical lines coalescing at a bicritical point in the macroscopic limit. We construct a stochastic master equation for the reaction processes to account for the presence of mutual particle interactions in a thermodynamically consistent manner by imposing a generalized detailed balance condition, which leads to exponential corrections for the transition rates. In a non-spatially extended (zero-dimensional) setting, we treat the interactions in a mean-field approximation, and introduce a minimal model that encodes the physical behavior of the bicritical point and permits the exact evaluation of the anomalous scaling for the particle number fluctuations in the thermodynamic limit. We obtain that the system size scaling exponent for the particle number variance changes from at the standard non-interacting bifurcation to at the interacting bicritical point. The methodology developed here provides a generic route for the quantitative analysis of fluctuation effects in chemical reactions occurring in multi-component interacting systems.

Interfacial Supra-Assembly of Copolymer Nanoparticles Enables the Formation of Nanocomposite Crystals with a Tunable Internal Structure.

It is highly desirable but technically challenging to precisely control the spatial composition and internal structure of crystalline nanocomposite materials, especially in a one-pot synthetic route. Herein, we demonstrate a versatile pathway to tune the spatial distribution of guest species within a host inorganic crystal via an incorporation strategy. Specifically, well-defined block copolymer nanoparticles, poly(methacrylic acid)x-block-poly(styrene-alt-N-phenylmaleimide)y [PMAAx-P(St-alt-NMI)y], are synthesized by polymerization-induced self-assembly. Such anionic nanoparticles can supra-assemble onto the surface of larger cationic nanoparticles via an electrostatic interaction, forming colloidal nanocomposite particles (CNPs). Remarkably, such CNPs can be incorporated into calcite single crystals in a spatially controlled manner: the depth of CNPs incorporation into calcite is tunable. Systematic investigation indicates that this interesting phenomenon is governed by the colloidal stability of CNPs, which in turn is dictated by the PMAAx-P(St-alt-NMI)y adsorption density and calcium ion concentration. This study opens up a general and efficient route for the preparation of a wide range of crystalline nanocomposite materials with a controlled internal composition and structure.

Large-scale assembly of isotropic nanofiber aerogels based on columnar-equiaxed crystal transition

Ice-templating technology holds great potential to construct industrial porous materials from nanometers to the macroscopic scale for tailoring thermal, electronic, or acoustic transport. Herein, we describe a general ice-templating technology through freezing the material on a rotating cryogenic drum surface, crushing it, and then re-casting the nanofiber slurry. Through decoupling the ice nucleation and growth processes, we achieved the columnar-equiaxed crystal transition in the freezing procedure. The highly random stacking and integrating of equiaxed ice crystals can organize nanofibers into thousands of repeating microscale units with a tortuous channel topology. Owing to the spatially well-defined isotropic structure, the obtained Al2O3·SiO2 nanofiber aerogels exhibit ultralow thermal conductivity, superelasticity, good damage tolerance, and fatigue resistance. These features, together with their natural stability up to 1200 °C, make them highly robust for thermal insulation under extreme thermomechanical environments. Cascading thermal runaway propagation in a high-capacity lithium-ion battery module consisting of LiNi0.8Co0.1Mn0.1O2 cathode, with ultrahigh thermal shock power of 215 kW, can be completely prevented by a thin nanofiber aerogel layer. These findings not only establish a general production route for nanomaterial assemblies that is conventionally challenging, but also demonstrate a high-energy-density battery module configuration with a high safety standard that is critical for practical applications.

Synthetic Strategies for Quinoline Based Derivatives as Potential Bioactive Heterocycles.

Quinoline derivatives are an important class of heterocyclic compounds and possess various applications in synthetic organic chemistry, medicinal chemistry, material chemistry and natural product chemistry. This review article describes the different quinoline derivatives having antimalarial, analgesic, anti-inflammatory, antineoplastic, antibacterial, antifungal, antiviral, anthelmintic, antiprotozoal, cardiovascular, CNS and other useful bioactivities. We have delineated the general synthetic routes for the synthesis of many bioactive quinoline based heterocycles. In addition to this, we have also discussed the crucial synthetic routes as well as their mechanistic paths for the formation of bioactive quinoline derivatives. The study shows that substitution at the 4 and 8- position of quinoline is more crucial for bioactivity as compared to other positions.

Inspired by game theory: A spatial confinement strategy for narrow-pore distribution porous carbons toward high-performance supercapacitors

This work suggests how understanding the Gibbs free energy evolution mechanism recorded for solid activators at high temperatures can provide a simple and general route to targeted tuning in preparing porous carbons. We show that based on a novel spatial confinement strategy, it is likely to target-produce pine sawdust (PS)-derived porous carbons characterized by higher specific surface area than analogous conventionally porous carbons but similar average pore size and pore size distribution (PSD). Notwithstanding the increased specific surface area and total pore volume of PS-derived porous carbon prepared under spatial confinement forces compared to conventional porous carbon, the pore structures recorded for PS-derived porous carbon obtained under spatial confinement forces arise from narrow pores, which leads to a sharp growth in specific capacitance over a range. Specifically, the texture properties can be tuned by various spatial confinement forces, bypassing the activation process tuning, template, sequential activation, and trial-and-error methods. Notably, PC-40-850 achieved higher specific capacitance values. Encouragingly, PC-40-850 offered excellent cycle stability accompanied by great energy density values (e.g., 29.31 Wh/kg upon 499.99 W/kg). Specifically, PC-40-850 realized a surface area-normalized electrical double-layer capacitance of 65.93 mF/m2. Excellent manufacturability and variable narrow-pore distribution permit the spatial confinement strategy to produce numerous advanced and multistage porous carbons for matching specific applications.

Silicon nitride nanoparticles-based radiative charge recombination chemiluminescence for the highly selective and sensitive detection of diquat

Diquat (DQ) is widely applied in the agriculture industry to ensure crop yield and quality, but this compound poses a serious hazard to human beings. The design of an efficient sensing platform for DQ is essential for food safety and environmental protection. Here, we developed a radiative charge recombination chemiluminescence (CL) using silicon nitride nanoparticles (Si3N4 NPs) as luminophore via hypochlorite (NaClO) activation for DQ quantification. With more active sites (N-Cl) on the surface of Si3N4 NPs, Si3N4 NPs displayed specific CL performance toward DQ. Accordingly, a new CL system for DQ detection was fabricated with satisfactory linearity (10–200 μg/L) and detection limit (6.1 μg/L), relative standard deviation (RSD) was lower than 1%. This new CL assay does not respond to other pesticides, and no interferences from metal ions that have been reported before in the DQ CL sensors. The CL mechanism was proposed that Si3N4 NPs act as the catalyst to accelerate the generation of superoxide radical (O2·−) from DQ, and then the radiative charge recombination of Si3N4 NPs occurs between the O2·− and exogenous holes for extraordinary CL emission. This work provides a general route for the construction of nanoparticle CL probe, which will aid in the monitoring of pollutants.

A General Synthesis of Crystal Phase Controllable Aerogels for Efficient Hydrogen Evolution.

Amorphous/crystalline (a/c) hetero-phase structures are considered as a class of efficient electrocatalysts for hydrogen evolution reaction (HER), but it remains a substantial challenge to obtain the specific phase by phase-selective synthesis. In this work, a general route for the preparation of various heterogeneous aerogels (RuB, PtB, PdB, and RhB) consisting of amorphous and crystalline phases is presented through a controlled NaBH4 reduction method. The prepared a/c-RuB aerogel exhibits better HER performance due to their desirable compositional and structural advantages such as more exposed active sites, optimized electronic structure, and interfacial synergistic effects. It requires only a low overpotential of 39mV to reach a density of 10mA cm-2 and also exhibits excellent stability. This work provides a new phase-selective synthesis strategy for the design and development of advanced hetero-phase electrocatalysts.

Oxidative Cleavage and Fluoromethylthiolation of C═C Bonds: A General Route toward Mono-, Di-, and Trifluoromethylthioesters from Alkenes.

A novel oxidative cleavage and fluoromethylthiolation reaction of C═C bonds has been developed that represents the first and general method for the preparation of mono-, di-, and trifluoromethylthioesters from alkenes. The protocol features excellent product selectivity and substrate suitability. Various observations suggested that the protocol proceeded via a two-step radical process and that aldehyde was the key intermediate. What's more meaningful is that this route provides a new direction for converting alkenes into higher-value-added carbonyl-containing chemicals.

Robust and highly efficient electrocatalyst based on ZIF-67 and Ni2+ dimers for oxygen evolution reaction: In situ mechanistic insight

Electrochemical water splitting is a straightforward process that involves two distinct reactions: the oxygen evolution reaction (OER) which produces oxygen (O2) and the hydrogen evolution reaction (HER) which generates hydrogen (H2). However, in the whole process, the OER is a bottleneck as it requires more energy than a four-electron reaction involving critical raw materials (such as RuO2 or IrO2) as electrocatalysts. Therefore, here, we address the challenge of erratic kinetics/limited durability of OER in water electrolysis. In this paper, we demonstrate that the deposition of ultrasmall amounts of nickel(II) nitrate in zeolitic imidazolate framework-67 (ZIF-67) can be used as a general approach to enhance the electrocatalytic performance of the framework. We investigated the influence of Ni(NO3)2·x6H2O loading on ZIF-67 (from 0.1 to 0.0001 M) and found that ZIF-67 enriched with only 0.001 M of Ni(NO3)2·x6H2O (ZIF-67 0.001Ni) exhibited massive promotion in OER. The ZIF-67 0.001Ni showed a large specific surface area of 2577 m2 g−1, a low overpotential of 299 mV, a lower Tafel slope of 94.1 mA dec−1, and an outstanding overpotential retention of 99.8% (at 50 mA cm−2). By conducting electron paramagnetic resonance (EPR) measurements, we also discovered that the 0.001 M of Ni(NO3)2·x6H2O loading in ZIF-67 introduces Ni2+ dimers, which contribute to the enhanced electroactivity of the modified ZIF-67. This phenomenon was further revealed during density-functional theory (DFT) calculations, which allowed us to identify different possible forms of Ni2+ dimers and modeling of active centers. Along with in situ experiments, we provide mechanistic insight into the OER mechanism under alkaline conditions and found that it follows the lattice oxygen mechanism (LOM). Our study proposes a facile and efficient room-temperature route to boost the electrochemical performance of ZIF-67 in OER. For the first time, we demonstrate that modifying ZIF-67 with an ultrasmall amount of different nickel(II) salts opens a general route to enhance its electroactivity during water-splitting reactions.