Construction Of Core Research Articles

A construction of core–shell dual zeolite imidazole skeleton derived composite to facilitate photocarrier separation and distribution of active sites for photocatalytic water oxidation

Limited by the severe carrier recombination and insufficient active sites of the catalyst, achieving efficient photocatalytic water oxidation remains a major challenge. Herein, a core–shell zeolite imidazole skeleton (ZIF) based material with rich active sites in its interior is obtained by in-situ growth carbonization two steps method. According to characterization, performance testing and photoelectric experiments, it is confirmed that the ZIF67@ZIF8-2-800 material has good photogenerated carrier separation efficiency and surprising O2 production. The reason for the performance improved is that ZIF8 as a shell prevents the agglomeration of active sites CoO in the carbonization process of ZIF67. Theoretical calculations reveal that the core–shell structure has a favorable influence on the separation of photogenerated carriers. The N atom acts as an electron transport mediator, transferring electrons from the CoO core to the NC shell, while the holes remain in the CoO to participate in the photocatalytic water oxidation reaction.

Microfluidic Construction of Polypyrrole-Coated Core–Sheath Polyaniline/Graphene Hybrid Fibers with Excellent Properties for Wearable Supercapacitors

Microfluidic Construction of Polypyrrole-Coated Core–Sheath Polyaniline/Graphene Hybrid Fibers with Excellent Properties for Wearable Supercapacitors

Nanoengineering Liquid Metal Core–Shell Nanostructures

AbstractNanoengineering the composition and morphology of functional nanoparticles endows them to perform multiple tasks and functions. An intriguing strategy for creating multifunctional nanomaterials involves the construction of core–shell nanostructures, which have enabled promising applications in biomedicine, energy, sensing, and catalysis. Here, a straightforward nanoengineering approach is presented utilizing liquid metal nanoparticles and galvanic replacement to create diverse core–shell nanostructures. Controlled nanostructures including liquid metal core‐gold nanoparticle shell (LM@Au), gold nanoparticle core‐gallium oxide shell (Au@Ga oxide), and hollow Ga oxide nanoparticles are successfully fabricated. Remarkably, these investigations reveal that LM@Au exhibits exceptional photothermal performance, achieving an impressive conversion efficiency of 65.9%, which is five times that of gold nanoparticles. By leveraging the high photothermal conversion efficiency and excellent biocompatibility of LM@Au, its promising application in hyperthermia cancer therapy is demonstrated. This simple yet powerful nanoengineering strategy opens new avenues for the controlled synthesis of complex core–shell nanostructures, advancing various fields beyond biomedicine.

Construction of core–shell coordination sponge-Fe0@Cu-Pd trimetal for high efficient activation of room-temperature dissolved ambient oxygen toward synergistic catalytic degradation of tetracycline and p-nitrophenol

Room-temperature ambient air is cheap and easy to obtain, hence the application of room-temperature ambient air as sole oxidant for pollutant degradation is extremely fascinating. In this work, core–shell coordination sponge-Fe0@Cu-Pd trimetal catalyst was synthesized via a simple step displacement plating process employing first displacement of Cu and the subsequent displacement of Pd, and applied as heterogeneous catalyst for synergistic catalytic degradation of composite pollutants including TC and PNP. The prepared s-Fe0@Cu-Pd trimetal sample was characterized with XRD, SEM, TEM, VSM and XPS. The characterization results revealed the obtained s-Fe0@Cu-Pd trimetal sample was a 20 ∼ 30 nm core–shell spherical morphology composed of Fe0 aggregates core wrapped by a Cu-Pd shell layer. The obtained sponge-Fe0@Cu-Pd trimetal catalyst could efficiently activate room-temperature dissolved ambient oxygen and achieve the largest TC removal rate of 99.08 % and PNP removal rate of 97.16 % as well as the biggest removal rate constant of 8.76 min−1 for TC degradation and 7.55 min−1 for PNP degradation within 60 min at experimental conditions: [TC] = 30 mg/L, [PNP] = 30 mg/L, [Catalyst] = 25.52 g/L, pH = 3, 298 K ascribed to the strongest oxidation and reduction ability confirmed by CV characterizations, the lowest charge transfer and contact resistance affirmed by EIS measurements, the strongest O2 activation ability verified by O2-TPD characterizations and DFT analyses, the largest external surface area and mesoporous volume validated by Nitrogen adsorption and desorption characterizations as well as the synergistic catalysis effect for wrapped Cu and Pd. Quenching experiments and EPR characterizations revealed that •OH, •O2−, 1O2 and •H are all the reactive species and meanwhile •O2− served as the main reactive oxygen species. Furthermore, possible mechanisms of TC and PNP degradation via sponge-Fe0@Cu-Pd trimetal catalyst were proposed.

First Asymmetric Total Synthesis of Salinosporamides D and I Using Memory of Chirality and Dynamic Kinetic Resolution

The first total synthesis of (–)‐salinosporamide D was achieved using d‐serine as the sole chiral source. This approach stands out for its application of the principles of memory of chirality and dynamic kinetic resolution in the intramolecular aldol reaction of serine‐derived oxazolidines. These strategies enabled the rapid construction of a pyrrolidinone core and installation of contiguous stereocenters. The key intermediate was readily obtained, culminating the asymmetric total synthesis of salinosporamide D. The total synthesis of salinosporamides A and I was also achieved using the same chemistry.

Construction of core–shell MOF@COF hybrid materials as highly efficient light-responsive oxidase-like nanozymes for colorimetric detection of glutathione

In this work, a novel and light-responsive nanozyme, with enzyme-like characteristics, was synthesized based on core–shell MOF@COF hybrid materials. The donor–acceptor type COF (as shell) synthesized by 1,3,6,8-tetrakis(4-aminophenyl)pyrene (Py, donor) and thieno[3,2-b]thiophene-2,5-dicarbaldehyde (Tt, acceptor) was wrapped on the NH2-Cu-MOF (robust catalyst, as core) through a sequential growth strategy. Surprisingly, with visible-light irradiation, the core–shell Cu-MOF@Py-Tt hybrid materials exhibited extremely high oxidase-like enzymatic catalytic activity attributing to the high separation efficiency of photogenerated carriers in core–shell hybrid materials and the shell with the characteristics of large π-conjugated and D-A electronic structure. With the light-control catalytic activity, Cu-MOF@Py-Tt can form the O2•- that can catalyze the TMB to blue color. Consequently, a light-control, sensitive and rapid colorimetric method for determination of glutathione (GSH) was designed based on light-responsive oxidase mimic of core–shell Cu-MOF@Py-Tt with the linear range of 0.2–70 μM and limit of detection of 0.17 μM. The proposed method demonstrated the future potential of core–shell MOF@COF hybrid materials to obtain excellent nanozyme activity.

Total syntheses and antibacterial evaluations of cudraflavones A-C and related Flavones

The total syntheses of the natural prenylated flavones cudraflavones A–C (1–3), artoheterophyllin D (28) and artelasticin (29) are reported, along with the evaluations of their antibacterial activities. The key steps of the synthesis involved a Baker-Venkataraman rearrangement and an intramolecular cyclization for the construction of the flavone core and the regioselective formation of the pyran and isopentenyl scaffolds. The tested natural flavones 1–3 and 27–29 exhibited potent activity against S. aureus ATCC 29213, S. epidermidis ATCC 14990, E. faecalis ATCC 29212 and B. subtilis ATCC 6633 with MIC values ranging from 0.125 μg/mL to 16 μg/mL. Compound 3 displayed the strongest potency, with MIC values in the range between 0.125 and 1 μg/mL, as a potential candidate to combat G+ bacterial infections. Preliminary mechanism of action studies suggested that this compound killed bacteria by disrupting bacterial membrane integrity.

Accessing Dihydropyrrolo[3,4‐b]indol‐1(2H)‐ones via Pd‐Catalyzed Intramolecular Aminocarbonylative Ring Closure

AbstractPresent in a number of small molecule derivatives that display a wide range of biological activities, the dihydropyrrolo[3,4‐b]indol‐(2H)‐one (DHPI) core represents an underexplored heterocyclic scaffold. Given the pharmaceutical potential of the DHPI motif, the development of synthetic methodologies that permit their expedient assembly would be highly desirable. Herein, we describe a novel strategy for the construction of the DHPI core from 3‐iodo‐1H‐indolyl substrates, employing an unprecedented Pd‐catalyzed intramolecular aminocarbonylative ring closure. The compatibility of our optimized protocol with various functional groups is highlighted through the synthesis of a range of diversely substituted DHPI derivatives in up to 90 % isolated yield.

Multicomponent digital core construction and three-dimensional micro-pore structure characterization of shale

The components and pore structure of shale are complex due to the heterogeneous distribution of organic matter and the complex distributions of the minerals. The digital core, possessing the advantages of being economical and reusable, can be widely used to directly characterize the three dimensional (3D) micro-pore structure and to numerically simulate its physical properties. During construction of a digital shale core, it is a challenge to solve the multicomponent segmentation for the digital shale core, the contradiction between the sample size and image resolution, and the identification of the pore types in the 3D pore space. Therefore, an automatic workflow based on the gray gradient-maximum entropy-3D morphology was developed. The gray gradient-maximum entropy algorithm was used to segment each sub-image of focused ion beam scanning electron microscope images to generate segmented images. On this basis, the pore size distribution was optimized via 3D morphological erosion. Based on the concept of pore clusters, the organic and inorganic pores were identified using the 3D morphological method for the first time. The construction of a multicomponent digital shale core was realized. The 3D micro-pore structure of the organic and inorganic pores was characterized by pore connectivity, heterogeneity, and pore size distribution. The accuracy of the proposed method was verified using low-temperature N2 adsorption experiment data. The results of this study provide new insight into the multicomponent digital shale core construction and lay the foundation for the characterization of the petrophysical properties and micro-/nano-scale fluid flow simulations of shale.

Engagement of intrinsic disordered proteins in protein-protein interaction.

Proteins from the intrinsically disordered group (IDP) focus the attention of many researchers engaged in protein structure analysis. The main criteria used in their identification are lack of secondary structure and significant structural variability. This variability takes forms that cannot be identified in the X-ray technique. In the present study, different criteria were used to assess the status of IDP proteins and their fragments recognized as intrinsically disordered regions (IDRs). The status of the hydrophobic core in proteins identified as IDPs and in their complexes was assessed. The status of IDRs as components of the ordering structure resulting from the construction of the hydrophobic core was also assessed. The hydrophobic core is understood as a structure encompassing the entire molecule in the form of a centrally located high concentration of hydrophobicity and a shell with a gradually decreasing level of hydrophobicity until it reaches a level close to zero on the protein surface. It is a model assuming that the protein folding process follows a micellization pattern aiming at exposing polar residues on the surface, with the simultaneous isolation of hydrophobic amino acids from the polar aquatic environment. The use of the model of hydrophobicity distribution in proteins in the form of the 3D Gaussian distribution described on the protein particle introduces the possibility of assessing the degree of similarity to the assumed micelle-like distribution and also enables the identification of deviations and mismatch between the actual distribution and the idealized distribution. The FOD (fuzzy oil drop) model and its modified FOD-M version allow for the quantitative assessment of these differences and the assessment of the relationship of these areas to the protein function. In the present work, the sections of IDRs in protein complexes classified as IDPs are analyzed. The classification "disordered" in the structural sense (lack of secondary structure or high flexibility) does not always entail a mismatch with the structure of the hydrophobic core. Particularly, the interface area, often consisting of IDRs, in many analyzed complexes shows the compliance of the hydrophobicity distribution with the idealized distribution, which proves that matching to the structure of the hydrophobic core does not require secondary structure ordering.

Study and analysis of sandwich panels for use in the construction of cabin roofs used on construction equipment

Sandwich panels have been of great interest in recent years due to the tendency of the engineers to replace heavy and rigid structures with light structures that allow good energy absorption and good deformation values. One of the areas that needs these panels is the cabin design used on construction equipment. These cabins are used in environments where there is a danger that various objects may hit the structure of their roof, thus endangering the health or life of operators. The aim of this study is to replace the classic cabin roofs with lighter roofs and better material properties. A first objective of this work is to adapt different types of cells and analyse them in terms of energy absorption while a compressive force is applied. The best result in terms of values obtained have been further used in the construction of the sandwich plates core. The second objective is the static analysis of sandwich plates that contain cells and walls of different thicknesses. Simulations of hitting the sandwich plate with a moving object, by creating a simulation with a finite element method, were performed. The results are compared, and the most favourable one was implemented in the construction of the construction machine. As a final objective of this paper, the dynamic analysis with the help of the finite element analysis used to validate the purpose is presented.

Total Synthesis of Nagelamide W.

Herein, we report the total synthesis of nagelamide W (1), a pyrrole imidazole alkaloid of the nagelamide family isolated in 2013. The key approach in this work involves the construction of the 2-aminoimidazoline core of nagelamide W from alkene 6 through a cyanamide bromide intermediate. The synthesis of nagelamide W was accomplished with an overall yield of 6.0%.

General Approach to Enantiopure 1-Aminopyrrolizidines: Application to the Asymmetric Synthesis of the Loline Alkaloids.

The synthesis of a range of loline alkaloids is reported. The C(7) and C(7a) stereogenic centers for the targets were formed by the established conjugate addition of lithium (S)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl 5-benzyloxypent-2-enoate, ensuing enolate oxidation to give an α-hydroxy-β-amino ester, and then formal exchange of the resultant amino and hydroxyl functionalities (via the intermediacy of the corresponding aziridinium ion) to give an α-amino-β-hydroxy ester. Subsequent transformation gave a 3-hydroxyprolinal derivative which was converted to the corresponding N-tert-butylsulfinylimine. Mannich-type reaction with the enolate derived from O-Boc protected methyl glycolate then formed the remaining C(1) and C(2) stereogenic centers for the targets. The 2,7-ether bridge was formed by a displacement reaction, completing construction of the loline alkaloid core. Facile manipulations then gave a range of loline alkaloids, including loline itself.

An experimental investigation on the effect of nano-graphene oxide on the maximum peeling force of Al/GFRP laminates

The effect of adding different percentages of nano-graphene oxide (NGO) into the epoxy resin on the mechanical properties of NGO/epoxy and maximum peeling force of fiber-metal laminates (FMLs) with composite cores are investigated in this paper. Three different percentages of NGO including 0.1, 0.35 and 0.50 weight percentages (wt. %) are used to fabricate the tensile test samples of NGO/epoxy. Hand lay-up method is used to fabricate FML specimens with glass fiber reinforced plastic (GFRP) core and aluminum faces. Tensile tests are examined and the Young’s modulus and ultimate stress of NGO/epoxy samples are determined. It is found that after adding of 0.1 wt. % of NGO into the epoxy resin, the ultimate tensile strength decreased by 13.4% from 25.3 to 21.9 MPa. Moreover, using peeling test, the separation force between aluminum faces of Al/GFRP laminates are obtained. Based on the results, when 0.1 wt. % of NGO is mixed with the epoxy, the maximum peeling force of FML increases by 16% and amounts to 4 N/mm. Based on the results, when NGO is used next to micro fibers in the construction of composite core, they have an effective role on the interlayer adhesion of fibrous composites.

Modulation of Hot Electrons via Interface Engineering of Au@ZnIn2S4/MXene for Efficient Photoelectrochemical Seawater Splitting under Visible Light

Interface engineering in hybrid plasmonic metal/semiconductor heterostructures is an efficient approach to enhance the catalytic performance of photocatalysts and photoelectrochemical cells in harvesting and converting sunlight, especially in the range of visible light. Plasmon-induced hot electron injection plays a crucial role in the transfer of plasmonic energy from a plasmonic metal to semiconductor in a plasmonic metal/semiconductor system. Herein, the efficient injection and utilization of hot electrons are achieved by fabrication of a Au@ZnIn2S4/Ti3C2 (Au@ZIS/Ti3C2) system, in which the core–shell Au@ZIS nanoparticles with well-defined interfaces are anchored on the 2D Ti3C2 surface. The core–shell Au@ZIS nanostructure is first constructed by a cation exchange reaction method. The well-defined interface of the Au core and ZIS shell optimizes the electron transfer pathway and greatly promotes the extraction of hot electrons from Au to ZIS. Furthermore, the electrons concentrated on ZIS can be further transferred to Ti3C2 owing to its excellent electron mobility and conductivity, leading to highly efficient separation and transfer of electrons through a two-step transfer process. The activities of photoelectrochemical (PEC) seawater splitting demonstrate that the integration of Au and ZIS into an optimized core–shell structure and its further modification by Ti3C2 results in a drastic improvement in PEC activity. Therefore, Au@ZIS/Ti3C2 shows the highest photocurrent density and smallest charge transfer resistance among various samples, accompanied by 6.5 and 10.8 orders of enhancement in PEC H2 evolution compared to reference samples of ZIS/Ti3C2 and Au/Ti3C2. Elaborate design and construction of core–shell plasmonic metal@semiconductor nanostructure with a well-defined interface and 2D MXene support would provide a feasible and promising method to enhance the performance of PEC seawater splitting.

Development of a Concise Process for the Synthesis of the Azaindazole Core of the CD73 Inhibitor AB680

AB680 is a highly potent small-molecule CD73 inhibitor discovered and developed by Arcus Biosciences, currently in clinical trials for the treatment of pancreatic cancer. Herein, we report a concise synthesis of 4,6-dichloro-1H-pyrazolo[3,4-b]pyridine 3, which is the central azaindazole core of AB680. The process consists of four synthetic operations and three isolations, including a PMB-protected pyrazole formation, a telescoped two-step cyclization and aromatization sequence, and finally a one-pot PMB deprotection and chlorination to furnish 3. This chemistry was successfully scaled up to provide >200 g of 3 in 44% overall yield and 97.6% HPLC purity. Overall, the route developed toward 3 represents an efficient construction of an azaindazole core, which is a synthetically challenging yet prevalent structural motif.

A facile construction of bifunctional core–shell–shell structured magnetic metal–organic frameworks for detection and removal of tetracycline

The sensitive detection and efficient removal of tetracycline (TC) residues are of great significance for improving food safety and preventing environmental pollution. Herein, a bifunctional core–shell–shell magnetic metal–organic framework was constructed (denoted as Fe3O4@PDA@Eu-MOF) by layer-by-layer self-assembly. The Fe3O4@PDA@Eu-MOFs possessed the merit of superparamagnetism, unique porous structure, and large specific surface area, which could offer abundant multiaffinity sites for improving the capture ability of materials for TC (Qm = 144.9 mg/g). It was worth mentioning that the Fe3O4@PDA@Eu-MOF showed excellent optical properties, which could be employed as a fluorescence sensor for TC detection over a wide detection range (0.01–25 mg/L) and low detection limit (2 μg/L). Moreover, the practical feasibility of Fe3O4@PDA@Eu-MOF for TC sensing was also investigated in milk and honey. In this work, the synthesis method of a novel core–shell–shell structured magnetic MOF might have broader application prospects.

Analysis of the Impact of Design Parameters on the Power Density of the New Design of the Cogging Machine

The cogging machine is a new design of a machine with permanent magnets, which combines the advantages of a machine with transverse flux (TFM), eliminating its disadvantages. The biggest advantage of TFM machines is their high torque density, which varies with the design parameters. The developed machine retains these advantages while simplifying the construction of the stator core, which is the biggest disadvantage of TFM machines. This article presents the results of an analysis of the power density of the developed cogging machine as a function of a number of pole pairs and the basic design parameters. Analyses were carried out on the basis of the derived analytical equations, which make the generated torque depend on the construction parameters. Thanks to the derived dependencies, one can easily examine the effects of modifying the machine structure. The results presented in the article prove that the developed design of the cogging machine is competitive in relation to machines with permanent magnets existing on the market.

Organocatalytic (Z/E)-Selective Synthesis of 3-Vinylnaphthofurans via a Formal (3 + 2) Cycloaddition.

A formal (3 + 2) cycloaddition of 1,4-enediones with 2-naphthols was established under the catalysis of trifluoromethanesulfonic acid as an organocatalyst, leading to the efficient synthesis of structurally diverse 3-vinylnaphthofurans with high yields and excellent (Z/E)-selectivities (up to 96% yield, all >20:1 Z/E). This formal (3 + 2) cycloaddition involved a cascade reaction process, and the intramolecular hydrogen bond in the structure of 3-vinylnaphthofurans should play an important role in controlling the (Z/E)-selectivity of the newly formed vinyl group. Moreover, this class of 3-vinylnaphthofurans was discovered to have an axial chirality. This work provides an organocatalytic approach for constructing multi-substituted vinylnaphthofurans via a cascade reaction with excellent control of the (Z/E)-selectivity, which will serve as a useful strategy for synthesizing vinylnaphthofurans via in situ construction of the furan core and formation of the vinyl group.

A Visible-Light-Induced α-Aminoalkyl-Radical-Mediated Halogen-Atom Transfer Process: Modular Synthesis of Phenanthridinone Alkaloids.

A halogen-atom transfer (XAT) strategy utilizing α-aminoalkyl radicals allows the generation of aryl radicals at room temperature, which is applied for intramolecular cyclization reactions en route to biologically relevant alkaloids. Starting from simple halogen-substituted benzamides under visible light irradiation in the presence of an organophotocatalyst (4CzIPN) and nBu3N allows the modular construction of the phenanthridinone core, which gives facile access to drug analogs and alkaloids, e.g., from the Amaryllidaceae family. The reaction pathway most likely involves a quantum mechanical tunneling enabled transfer event to achieve aromatization-halogen-atom transfer.