An unprecedented electrochemical trifluoromethylation/SO2 insertion/cyclization process has been achieved in an undivided cell in an atom‐economic fashion. The protocol relies on tandem cyclization ...of N‐cyanamide alkenes by using Langlois’ reagent as a source of both CF3 and SO2 under direct anodically oxidative conditions, in which two C−C bonds, two C−X bonds (N−S and S−C), and two rings were formed in a single operation. This transformation enabled efficient construction of various trifluoromethylated cyclic N‐sulfonylimines from readily accessible materials.
Double agent: An electrochemical trifluoromethylation/SO2 insertion/cyclization process using an undivided cell proceeds in an atom‐economic fashion. Various trifluoromethylated cyclic N‐sulfonylimines can be readily accessed from readily available materials by using Langlois’ reagent as a source of both CF3 and SO2 in a single operation under direct anodically oxidative conditions.
•A thin walled tube filled with double arrowed gradient auxetic structure is proposed.•Analytical models are established to predict the dynamic characteristics of thin walled tubes filled with ...auxetic structures.•Compared to the numerical simulations, the analytical models are accurate to predict the dynamic responses.
In recent years, auxetic structures have been applied in the energy absorption field due to the unique mechanical properties. Inspired by foam filled structures, this study proposes a thin walled structure filled with double arrowed auxetic structure and investigates the energy absorption characteristics. The gradient configuration is introduced to improve the energy absorption performance. The effects of the gradients on the energy absorption are investigated. A theoretical model is also established to predict the energy absorption to quantify the energy dissipated due to thin walled tubes, gradient auxetic structures and their interactions. The accuracy of the theoretical model to predict the energy absorption characteristics is validated through the numerical simulations.
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As a trust machine, blockchain was recently introduced to the public to provide an immutable, consensus based and transparent system in the Fintech field. However, there are ongoing efforts to apply ...blockchain to other fields where trust and value are essential. In this paper, we suggest Gcoin blockchain as the base of the data flow of drugs to create transparent drug transaction data. Additionally, the regulation model of the drug supply chain could be altered from the inspection and examination only model to the surveillance net model, and every unit that is involved in the drug supply chain would be able to participate simultaneously to prevent counterfeit drugs and to protect public health, including patients.
Methanol synthesis by CO2 hydrogenation is a key process in a methanol‐based economy. This reaction is catalyzed by supported copper nanoparticles and displays strong support or promoter effects. ...Zirconia is known to enhance both the methanol production rate and the selectivity. Nevertheless, the origin of this observation and the reaction mechanisms associated with the conversion of CO2 to methanol still remain unknown. A mechanistic study of the hydrogenation of CO2 on Cu/ZrO2 is presented. Using kinetics, in situ IR and NMR spectroscopies, and isotopic labeling strategies, surface intermediates evolved during CO2 hydrogenation were observed at different pressures. Combined with DFT calculations, it is shown that a formate species is the reaction intermediate and that the zirconia/copper interface is crucial for the conversion of this intermediate to methanol.
Interface matters: A combination of solid‐state NMR and IR spectroscopies with DFT calculations unravels the nature of reaction intermediates in the hydrogenation of CO2 to methanol on Cu/ZrO2 catalysts, pointing out the specific role of the metal–support interface in the formation and conversion of formate into methoxy species.
Metal‐based materials with exceptional intrinsic conductivity own excellent electromagnetic interference (EMI) shielding performance. However, high density, corrosion susceptibility, and poor ...flexibility of the metal severely restrict their further applications in the areas of aircraft/aerospace, portable and wearable smart electronics. Herein, a lightweight, flexible, and anticorrosive silver nanowire wrapped carbon hybrid sponge (Ag@C) is fabricated and employed as ultrahigh efficiency EMI shielding material. The interconnected Ag@C hybrid sponges provide an effective way for electron transport, leading to a remarkable conductivity of 363.1 S m−1 and superb EMI shielding effectiveness of around 70.1 dB in the frequency range of 8.2–18 GHz, while the density is as low as 0.00382 g cm−3, which are among the best performances for electrically conductive sponges/aerogels/foams by far. More importantly, the Ag@C sponge surprisingly exhibits super‐hydrophobicity and strong corrosion resistance. In addition, the hybrid sponges possess excellent mechanical resilience even with a large strain (90% reversible compressibility) and an outstanding cycling stability, which is far better than the bare metallic aerogels, such as silver nanowire aerogels and copper nanowire foams. This strategy provides a facile methodology to fabricate lightweight, flexible, and anticorrosive metal‐based sponge for highly efficient EMI shielding applications.
Anticorrosive, ultralightweight, and flexible silver nanowire wrapped with carbon hybrid sponge is designed and employed as electromagnetic interference (EMI) shielding material with ultrahigh efficiency. The interconnected hybrid sponge shows superb EMI shielding effectiveness of 70.1 dB, while the density is as low as 0.00382 g cm−3, which are among the best performances for electrically conductive sponges/aerogels/foams by far.
Nanoparticles consisting of metal–organic frameworks (NMOFs) modified with nucleic acid binding strands are synthesized. The NMOFs are loaded with a fluorescent agent or with the anticancer drug ...doxorubicin, and the loaded NMOFs are capped by hybridization with a complementary nucleic acid that includes the ATP‐aptamer or the ATP‐AS1411 hybrid aptamer in caged configurations. The NMOFs are unlocked in the presence of ATP via the formation of ATP‐aptamer complexes, resulting in the release of the loads. As ATP is overexpressed in cancer cells, and since the AS1411 aptamer recognizes the nucleolin receptor sites on the cancer cell membrane, the doxorubicin‐loaded NMOFs provide functional carriers for targeting and treatment of cancer cells. Preliminary cell experiments reveal impressive selective permeation of the NMOFs into MDA‐MB‐231 breast cancer cells as compared to MCF‐10A normal epithelial breast cells. High cytotoxic efficacy and targeted drug release are observed with the ATP‐AS1411‐functionalized doxorubicin‐loaded NMOFs.
Stimuli‐responsive DNA‐functionalized metal–organic framework nanoparticles (NMOFs): The synthesis of NMOFs loaded with doxorubicin and capped with stimuli‐responsive DNAs that respond to biomarkers characteristic to cancer cells is described. By locking the drug‐loaded NMOFs with a DNA strand consisting of the AS1411 aptamer and the ATP aptamer, targeted permeation of the NMOFs into cancer cells, the ATP‐driven unlocking of the NMOFs, and drug release are demonstrated.
The synthesis of doxorubicin‐loaded metal–organic framework nanoparticles (NMOFs) coated with a stimuli‐responsive nucleic acid‐based polyacrylamide hydrogel is described. The formation of the ...hydrogel is stimulated by the crosslinking of two polyacrylamide chains, PA and PB, that are functionalized with two nucleic acid hairpins (4) and (5) using the strand‐induced hybridization chain reaction. The resulting duplex‐bridged polyacrylamide hydrogel includes the anti‐ATP (adenosine triphosphate) aptamer sequence in a caged configuration. The drug encapsulated in the NMOFs is locked by the hydrogel coating. In the presence of ATP that is overexpressed in cancer cells, the hydrogel coating is degraded via the formation of the ATP–aptamer complex, resulting in the release of doxorubicin drug. In addition to the introduction of a general means to synthesize drug‐loaded stimuli‐responsive nucleic acid‐based polyacrylamide hydrogel‐coated NMOFs hybrids, the functionalized NMOFs resolve significant limitations associated with the recently reported nucleic acid‐gated drug‐loaded NMOFs. The study reveals substantially higher loading of the drug in the hydrogel‐coated NMOFs as compared to the nucleic acid‐gated NMOFs and overcomes the nonspecific leakage of the drug observed with the nucleic‐acid‐protected NMOFs. The doxorubicin‐loaded, ATP‐responsive, hydrogel‐coated NMOFs reveal selective and effective cytotoxicity toward MDA‐MB‐231 breast cancer cells, as compared to normal MCF‐10A epithelial breast cells.
A stimuli‐responsive nucleic acid‐based hydrogel coating drug‐loaded metal–organic framework nanoparticles (NMOF) acts as an effective carrier for controlled drug release. This is exemplified with ATP (adenosine triphosphate)‐responsive hydrogel‐coated NMOFs loaded with doxorubicin. In the presence of ATP, overexpressed in cancer cells, the hydrogel coating is dissociated, resulting in the release of the drug. The hybrid NMOFs reveal selective cytotoxicity toward MDA‐MB‐231 breast cancer cells.
Multistability is the phenomenon of multiple coexistent stable states, which are highly sensitive to perturbations, initial conditions, system parameters, etc. Multistability has been widely found in ...various scientific areas including biology, physics, chemistry, climatology, sociology, and ecology. In a number of systems where multistability naturally exists, it is found to be undesirable because of the involuntary interwell or chaotic switching among dynamical states that disorder the systems and cause instability. However, in recent decades, researchers have identified numerous benefits of multistability and have devoted research efforts to artificially creating it for a wide range of applications, including signal processing, energy harvesting, composite structures and metamaterials, and micro-/nano-electromechanical actuators. This is because of the unique characteristics of multistability, such as rich potential structure, interwell dynamics, broadband nature, and alleviation of the input energy to sustain stable states, which may play different advantageous roles depending on their applications. In this review, we introduce how researchers create the key of multistability and utilize it to open a new world of theories, materials, and structures. We concentrate on developing histories from bistability to multistability in several potential applications. Different designs of digital and physical multistable systems, and their modeling, performance quantifiers, advantageous mechanisms, and improved techniques are reviewed and discussed in depth. Furthermore, we summarize the key issues and challenges of application-oriented multistability and the corresponding possible solutions, from the phenomenon itself to its realistic implementation. Finally, we provide the prospects for future studies on multistability in more developing research fields.
•The evolutionary history of bistability to multistability phenomena is reviewed.•Multistable signal processing/energy harvesting/composites/metamaterials are reviewed.•Benefits of multistability in various applications are discussed.•Issues and prospects are discussed to promote the utilization of multistability.
A hybrid nanoparticle, consisting of BaTiO3 nanoparticles tightly embedded in bronnitride (BN) nanosheets, has been fabricated based on a daring supposition that BN may act as a host to incorporate ...ferroelectric nanoparticles to improve insulation and polarization under a high electric field. Using the hybrids as fillers in poly(vinylidene fluoride) (PVDF) composites, a high electric breakdown strength (Eb ≈580 kV/mm), which is 1.76 times of the PVDF film, is obtained when the filler content is 5 wt%. A large displacement (9.3 µC/cm2 under 580 kV/mm) is observed so as to obtain a high discharged energy density (Ud ≈17.6 J/cm3) of the BT@BN/PVDF composites, which is 2.8 times of the PVDF film. The enhancement ratio of Eb achieved in this study demonstrates the highest among the reported results. This hybrid structure of fillers provides an effective way to adjust and improve the energy storage properties of the polymer‐based dielectrics.
BaTiO3@BN hybrids with the structure of barium titanate nanoparticles embedded in bronnitride nanosheets are fabricated, which act as fillers in poly(vinylidene fluoride)‐based composites. The electric breakdown strength and discharged energy density of the composites are significantly enhanced owing to the reduced surface charge density and the enhanced displacement.
•An analytical framework is developed to predict the elastic properties of irregular auxetic structures.•A finite element code is developed to validate the analytical predictions.•The effects of the ...degree of irregularity and geometric parameters on the elastic properties are investigated.
This paper presents an analytical framework with a bottom-up multi-step approach to predict the in-plane mechanical properties including the effective Young’s modulus and Poisson’s ratio in two directions. There are deviations for the analytical predictions with respect to the numerical results because of the simplifications of boundary conditions of the representative unit cell. To remedy the deviations, a modification coefficient is embedded to revise the analytical model. A finite element code for obtaining elastic properties of the irregular auxetic structures is developed to validate the revised analytical model. The good agreement between the revised analytical predictions and numerical results affirms the accuracy of the revised analytical model. It is noticeable that the effects of irregularity on the effective Young’s modulus are more prominent than on the Poisson’s ratio.
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