Desirable Structure Research Articles

Fabrication of Hierarchically-Porous Diatomite Scaffolds for Dye Adsorption by a Dual-templating Approach

Compared to single-scale porous structures, multi-scale porous materials are distinguished by their unique hierarchical architecture composed of macro-, meso-, and micro-pores. These materials are widely adapted in nature and endowed with high surface area, improved transport efficiency, and reduced weight due to their structural design. Such characteristics lead to various applications, especially in filtration and adsorption. In this study, a dual-templating method integrating freeze casting and 3D-printing sacrificial templating techniques was employed to develop multi-scale porous scaffolds with pore sizes distributed across three distinct length scales. Gyroid, a type of triply periodic minimal surface (TPMS) structure, was selected for the millimeter-scale channel design because of their high permeability, non-tortuous fluid pathways, and interconnected pores. Moreover, periodic gyroid structures can be described by mathematical equations, allowing for the systematic designs of 3D models. By varying the volume fractions of the 3D-printed gyroid templates and the cooling rates during the freeze casting process, pore sizes at both millimeter and micrometer scales can be tuned to achieve desired structures. Furthermore, the smallest pores were provided by diatomites, the fossilized silica-based algae with inherent nanoscale pores, offering extremely high surface area and porosity. Permeability experiments were conducted to further explore the influence of multi-scale pores on fluid transportation properties. Results showed that scaffolds with three scales of pore sizes (millimeter, micrometer, and nanometer) exhibited up to 58 times increase in permeability compared to those with two scales of pore sizes (micrometer and nanometer). Additionally, by leveraging the inherent functional groups on diatomites, multi-scale porous scaffolds were used in methylene blue dye adsorption experiments, revealing a dye removal efficiency of 63%. In conclusion, this study integrated freeze casting and additive manufacturing methods for multi-scale porous ceramics with tunable structural features and functionalities, which can be applied in wastewater treatment, ultra-lightweight structural materials and other engineering fields.

The Inhibitory Effect of Low Phosphorus and Low Molecular Weight Terpolymer Scale Inhibitor on Calcium Scale in Oilfields

ABSTRACTThe study utilized itaconic acid (IA), N‐hydroxyethyl acrylamide (HEAA), and sodium hypophosphite (SHP) as starting materials for a free radical polymerization process. This process resulted in creating a new type of low‐phosphorus terpolymer scale inhibitor called P(IA‐HEAA‐SHP). Its primary application was as an effective scale inhibitor to block CaCO3 and CaSO4. FTIR, 1H‐NMR, and 13C‐NMR were used to characterize the synthesized copolymer structures, and it was confirmed that the synthesized products had the desired structures. The synthesis conditions have been optimized using the static scale inhibition approach, which involved adjusting the monomer ratio, initiator dosage, and reaction time. This resulted in the synthesis of polymeric scale inhibitors with outstanding scale inhibition properties. Additionally, GPC was employed to examine the correlation of the molecular weight of the polymers with their scale inhibition properties at various reaction times. The results showed that when the monomer ratio n(IA):n(HEAA) = 1.5:1, the SHP dosage mass fraction was 15%, the ammonium persulfate initiator dosage was 10%, the reaction temperature was 90°C, and the reaction time was 4 h. At a measured dose of 30 mg L−1, the scale inhibition impact on CaCO3 is 86.63%, while the scale inhibition impact on CaSO4 is 96.83%. The thermal properties of the copolymers, the crystal structure, and the micro‐morphology of the scale samples were analyzed by TGA, XRD, and SEM, and the scale inhibition mechanism was discussed in conjunction with the zeta potential analysis.

Rheology dependent pore structure optimization of high-performance foam concrete

Foam concrete encounters a fundamental challenge in balancing lightweight and high strength. Pore optimization is the key to address this problem. This study starts with rheology control to optimize the pore structure of foam concretes, thereby designing high-performance foam concrete (HPFC). X-ray computed tomography was employed to explore the relationship between rheology and pore characteristics, revealing the corresponding control mechanisms. The findings indicated that rheological parameters, particularly viscosity, significantly influenced pore size, uniformity, sphericity, fractal dimension and connectivity. Therefore, there was an optimal viscosity range (1.30 ± 0.15 Pa·s) for achieving the desirable pore structure. Mechanical analysis demonstrated that the viscosity could impact the balance of the added foams under dynamic and static conditions via drag force, resulting in changes to the pore structure. After pore optimization, the HPFCs exhibited high compressive strength (2–3 times higher than normal foam concrete at an equal density) and excellent durability comparable to high-performance concrete.

Photocrosslinkable Biomaterials for 3D Bioprinting: Mechanisms, Recent Advances, and Future Prospects

Constructing scaffolds with the desired structures and functions is one of the main goals of tissue engineering. Three-dimensional (3D) bioprinting is a promising technology that enables the personalized fabrication of devices with regulated biological and mechanical characteristics similar to natural tissues/organs. To date, 3D bioprinting has been widely explored for biomedical applications like tissue engineering, drug delivery, drug screening, and in vitro disease model construction. Among different bioinks, photocrosslinkable bioinks have emerged as a powerful choice for the advanced fabrication of 3D devices, with fast crosslinking speed, high resolution, and great print fidelity. The photocrosslinkable biomaterials used for light-based 3D printing play a pivotal role in the fabrication of functional constructs. Herein, this review outlines the general 3D bioprinting approaches related to photocrosslinkable biomaterials, including extrusion-based printing, inkjet printing, stereolithography printing, and laser-assisted printing. Further, the mechanisms, advantages, and limitations of photopolymerization and photoinitiators are discussed. Next, recent advances in natural and synthetic photocrosslinkable biomaterials used for 3D bioprinting are highlighted. Finally, the challenges and future perspectives of photocrosslinkable bioinks and bioprinting approaches are envisaged.

MXene Manipulating the Electronic and Photoelectric Properties of a Fullerene-Layered Heterojunction.

An in-depth study of the substrate effect is crucial for optimizing and designing the performance of two-dimensional (2D) materials in practical applications. Fullerene monolayers (FMs), a new pure carbon system successfully prepared recently, have prompted renewed interest in the question of whether FMs might be exploited to create carbon-based functional materials with improved performance. Here, the electronic structure of a MXene-supported FM was investigated by first-principles calculations. Various band offset types, including types I, II, and III, exist in the FM/M2X heterostructures, which are determined by the energy level arrangement of individual layers. Interestingly, strain also plays an important role in the band offset of the FM/M2X heterostructures. From the selection of a specific substrate and introduction of proper strain in the substrate, the desired band structure can be obtained. Our results offer profound physical insights into the mechanism of electronic structure tuning of FM by substrates.

Electron transport and quantum phase transitions in cumulene-connected C80H20 fulleryne: DFT and tight-binding studies

Molecular bridges are opening up exciting new applications in diverse fields, improving the efficiency of conductive inks, enhancing the performance of devices such as organic light-emitting diodes and low-cost solar cells, and advancing the development of highly sensitive sensors, chemical reactions, drug delivery systems, and more. In this paper, we study the electron transport properties of a C80H20 fulleryne (dodecahedryne) connected to two cumulene electrodes. Using density functional theory (DFT), we determine the optimal molecular bridge structure. Based on the IR vibration spectra, different stable phases of the molecular bridge are obtained. The corresponding tight-binding (TB) parameters of the cage are obtained by assigning appropriate values of the length and type of bonds for the fulleryne cage through matching the HOMO-LUMO gap between the DFT calculations and the TB parameters. The electron transport for the desired structures is investigated using the obtained tight-binding parameters and the non-equilibrium Green's function (NEGF) method. Finally, it is concluded that among the five possible configurations for the cumulene-dodecahedryne -cumulene molecular bridge, only one specific configuration—where the electrodes are one edge apart—exhibits metallic behavior, while other positions act as insulators. In addition, the system exhibits quantum phase transitions from metal to semiconductor and from insulator to metal in the presence of critical electric fields. The ability to control quantum phase transitions in these molecular systems can be leveraged to develop qubits for quantum computing. The unique properties can be utilized to design advanced molecular electronic devices.

Interactive 3D structural design in virtual reality using preference-based topology optimization

Innovative load-bearing structures often emerge from a fine balance between creative forms and engineering principles. While preference-based topology optimization methods have advanced structural design by considering designers’ geometric preferences, they struggle with visualizing and editing complex 3D details crucial for diverse design options. To overcome this bottleneck, here we propose the improved bidirectional evolutionary structural optimization considering subjective preferences (ISP-BESO) method. This method introduces a similarity constraint that enables precise control over subjective preferences in optimized structures. Then, a design exploration strategy is proposed by integrating virtual reality (VR) with topology optimization for the interactive creation of desirable 3D structures. The strategy employs VR sculpting to offer immersive visualization and real-time feedback, guiding material redistribution during optimization. This workflow can iteratively produce innovative and efficient structures. Adjusting target similarity in ISP-BESO steers designs toward performance-driven or preference-driven outcomes. A museum design example demonstrates the practical potential of this strategy.

Atomic Fabrication of 2D Materials Using Electron Beams Inside an Electron Microscope.

Two-dimensional (2D) materials have garnered increasing attention due to their unusual properties and significant potential applications in electronic devices. However, the performance of these devices is closely related to the atomic structure of the material, which can be influenced through manipulation and fabrication at the atomic scale. Transmission electron microscopes (TEMs) and scanning TEMs (STEMs) provide an attractive platform for investigating atomic fabrication due to their ability to trigger and monitor structural evolution at the atomic scale using electron beams. Furthermore, the accuracy and consistency of atomic fabrication can be enhanced with an automated approach. In this paper, we briefly introduce the effect of electron beam irradiation and then discuss the atomic structure evolution that it can induced. Subsequently, the use of electron beams for achieving desired structures and patterns in a controllable manner is reviewed. Finally, the challenges and opportunities of atomic fabrication on 2D materials inside an electron microscope are discussed.

The Role of Artificial Intelligence in the Ethical Relationship of Virtual Cadavers

Dear Editors, The advancement of technology has led to a transformation in medical education. At this stage, the ethical considerations surrounding the use of cadavers in medical education are particularly intriguing. Nowadays, it is possible to digitally recreate real cadavers with virtual content. Such materials are referred to as virtual cadavers in the literature. Just like with real cadavers, the use of images of donors in virtual cadavers is subject to ethical permissions. At this point, the use of artificial intelligence tools comes to the forefront. The use of cadavers in medical education has been a traditional method for many years. The use of cadavers in medical education is a critical component for students to develop their understanding of human anatomy and clinical skills. Cadaver dissection provides medical students with the opportunity to learn the structure of the human body in detail, allowing them to translate theoretical knowledge into practical application. Additionally, it provides students with the opportunity for clinical experience. The use of cadavers in medical education helps students develop professional skills by providing them with practical experience on a real body (Erbay et al., 2015). Cadavers are obtained from human donors. In our country, there are various problems regarding cadaver donation rates. Cadaver donation is extremely low in our country, making it difficult for medical faculty students to access cadavers (Şeker et al., 2013). On average, there is only one cadaver for every 20 students studying at medical faculties in our country. It is even challenging to find 1-2 cadavers in departments of anatomy (Kürkçüoğlu et al., 2021). Additionally, there are issues arising from the irreversible nature of procedures performed on cadavers. Due to such reasons, studies related to virtual cadavers in digital environments have become increasingly important. Virtual cadavers represent an important solution brought about by technology in the field of medicine and generally in health education. Through the use of virtual cadavers, procedures that are difficult or even impossible to perform repeatedly on real cadavers can be achieved. Additionally, virtual cadaver modeling eliminates the possibility of tissue degradation. Desired tissues, systems, and structures can be modeled in a manner closely resembling reality. In addition to providing unlimited repetition capabilities, virtual cadavers revolutionize the use of cadavers by offering access at any desired time (Gürcan, 2018). The development of virtual cadavers poses certain challenges. For instance, the use of programs like Unity and Blender is necessary in the process of developing organs and structures. Besides the requirement of knowing how to use such programs, extensive hours are needed to create a model. Additionally, if virtual cadaver images are intended to be realistic, there are also some issues to address. The usage and dissemination of virtual cadaver contents obtained from real cadaver images on the internet are subject to ethical considerations. Just like with real cadavers, obtaining permission from the legal heirs of the donor is necessary when using images of donors in virtual cadavers. Artificial intelligence (AI) was first defined in 1956. McCarthy (2004) defined artificial intelligence as the task of creating human-like intelligent machines and intelligent computer programs (Arslan, 2020). AI has become increasingly popular in recent times, both as natural language processing models and in the field of image processing. With the use of AI tools, it is possible to generate visual and textual content without the need for detailed software and programming knowledge. It is even possible to create videos consisting of unreal images but resembling real ones. At this stage, the use of AI tools is considered important for virtual cadavers. By using AI visual generation tools, content that can be used in virtual cadavers can be easily created. Thus, virtual cadaver examples that are indistinguishable from real cadaver images but do not belong to a real person can be obtained. At this point, it is important for medical education and healthcare professionals to ethically examine this situation.

Chromium oxide nanoparticles in‐situ immobilized onto nitrogen‐doped carbon plates with boosted catalytic activity toward nitrogen reduction reaction

AbstractA chromium oxide‐based nanocomposite (Cr2O3@NC) is designed and prepared via a simple pyrolysis route with Cr‐based metal organic framework (MOF) as a template. The research results indicate that Cr2O3 nanoparticles have an average size of ~70 nm and are in situ formed and imbedded onto the Cr‐based MOF‐derived 2D N‐doped carbon microplates. When employed as an inexpensive electrocatalyst for nitrogen reduction reaction (NRR) to synthesize ammonia, Cr2O3@NC demonstrates an improved and stable catalytic activity in comparison with bare Cr2O3. A large ammonia production rate of 29.42 μg mg−1cat h−1 under a lower potential of −0.4 V versus reversible hydrogen electrode (RHE) can be acquired with a Faradic efficiency of 9.89% in sodium sulphate solution. Additionally, a satisfactory selectivity can also be achieved without hydrazine byproduct. The greatly promoted catalytic activity of Cr2O3@NC is regarded to be concerned with its desirable structures such as 2D planar topological structure with expanded active surface area, abundant catalytic sites, and effective combination with conductive carbon.

Emergent Research Trends on the Structural Relaxation Dynamics of Molecular Clusters: From Structure-Property Relationship to New Function Prediction.

ConspectusMolecular clusters (MCs) are monodispersed, precisely defined ensembles of atom collections featured with shape-persistent architectures that can deliver certain functions independently. Their molecular compositions and surface functionalities can be tailored feasibly in a predefined manner, and they can be applied as basic structural units to be engineered into materials with desirable hierarchical structures and enriched functions. The chemical systems also offer great opportunities for the design and fabrication of soft structural materials without the chain topologies of polymers. The bulks of MC assemblies demonstrate viscoelasticity that is used to be considered as the unique feature of polymers, while the MC systems are distinct from polymers since their elasticities are resilient even at temperatures 100 K above their glass transition temperatures. The understanding of their anomalous viscoelasticity and the extended studies of general structure-property relationships are desired for the development of new chemical systems for emergent functions and the possibilities to resolve the intrinsic trade-offs of traditional materials.Meanwhile, general macroscopic functions or properties of materials are related to the transportation of mass, momentum, and/or energy, and they are basically realized or directed by the motions of structural units at different length scales. Structural relaxation dynamics research is critical in quantifying motions ranging from fast bond deformation, bond break/formation, and diffusion of ions and particles to the cooperative motions of structure units. Due to the advancement of measurement technology for relaxation dynamics (e.g., quasi-elastic scattering and broadband dielectric spectroscopy), the structural relaxation dynamics of MC materials have been probed for the first time, and their multiple relaxation modes across several temporal scales were systematically studied to bridge the correlation between molecular structures and macroscopic functions. The fingerprint information from dynamics studies, e.g., the temperature dependence of relaxation time and certain property, e.g., ion conductivity, was proposed to quantify the structure-property relationship, and the microscopic mechanism on the mechanical properties, ion conduction, and gas absorption and separation of MC materials can be fully understood.In this Account, to elucidate the uniqueness of MC materials, especially in comparison with polymers, four topics are mainly summarized: structural features, relaxation dynamics characterization techniques, relaxation dynamics characteristics, and quantified understanding of the structure-property relationship. The capability for new function prediction from relaxation dynamics studies is also introduced, and the typical example in impact resistant materials is provided. The Account aims to prove the significance of relaxation dynamics characterization for material innovation, while it also confirms the potential of MCs for functional material fabrications.

Conversion of Carbon Dioxide into Molecular-based Porous Frameworks.

ConspectusThe conversion of carbon dioxide (CO2) to value-added functional materials is a major challenge in realizing a carbon-neutral society. Although CO2 is an attractive renewable carbon resource with high natural abundance, its chemical inertness has made the conversion of CO2 into materials with the desired structures and functionality difficult. Molecular-based porous materials, such as metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs), are designable porous solids constructed from molecular-based building units. While MOF/COFs attract wide attention as functional porous materials, the synthetic methods to convert CO2 into MOF/COFs have been unexplored due to the lack of synthetic guidelines for converting CO2 into molecular-based building units.In this Account, we describe state-of-the-art studies on the conversion of CO2 into MOF/COFs. First, we outline the key design principles of CO2-derived molecular building units for the construction of porous structures. The appropriate design of reactivity and the positioning of bridging sites in CO2-derived molecular building units is essential for constructing CO2-derived MOF/COFs with desired structures and properties. The synthesis of CO2-derived MOF/COFs involves both the transformation of CO2 into building units and the formation of extended structures of the MOF/COFs. We categorized the synthetic methods into three types as follows: a one-step synthesis (Type-I); a one-pot synthesis without workup (Type-II); and a multistep synthesis which needs workup (Type-III).We demonstrate that borohydride can convert CO2 into formate and formylhydroborate that serve as a bridging linker for MOFs in the Type-I and Type-II synthesis, representing the first examples of CO2-derived MOFs. The electronegativity of coexisting metal ions determines the selective conversion of CO2 into formate and formylhydroborate. Formylhydroborate-based MOFs exhibit flexible pore sizes controlled by the pressure of CO2 during synthesis. In pursuit of highly porous structures, we present the Type-I synthesis of MOFs from CO2 via the in situ transformation of CO2 into carbamate linkers by amines. The direct conversion of diluted CO2 (400 ppm) in air into carbamate-based MOFs is also feasible. Coordination interactions stabilize the intrinsically labile carbamate in the MOF lattice. A recent study demonstrates that the Type-III synthesis using alkynylsilane precursors enables the synthesis of highly porous and stable carboxylate-based MOFs from CO2, which exhibit catalytic activity in CO2 conversion. We also extended the synthesis of MOFs from CO2 to COFs. The Type-III synthesis using a formamide monomer affords stable CO2-derived COFs showing proton conduction properties. The precise design of CO2-derived building units enables expansion of the structures and functionalities of CO2-derived MOF/COFs. Finally, we propose future challenges in this field: (i) expanding structural diversity through synthesis using external fields and (ii) exploring unique functionalities of CO2-derived MOF/COFs, such as carriers for CO2 capture and precursors for CO2 transformation. We anticipate that this Account will lay the foundation for exploring new chemistry of the conversion of CO2 into porous materials.

Machine learning – enabled inverse design of shell-based lattice metamaterials with optimal sound and energy absorption

ABSTRACT Currently, the development in shell-based lattice, is increasingly focused on multifunctionality, with growing interest in combining sound and energy absorption. However, few studies have explored the multi-objective inverse design process. Herein, we propose a new approach using machine learning (ML) to optimise both the mechanical and acoustic performances of shell-based lattices. Firstly, the K-Nearest Neighbour and Artificial Neural Network are employed to predict the properties of different configurations. Then the non-dominated sorting genetic algorithm is employed to generate the desired structures. Finally, the lightweight metamaterials generated achieve optimal multifunctional performances (an energy absorption capacity of 50% higher than typical Gyroid structure and a sound absorption coefficient near 1 at specific frequency band). Besides, the potential trade-off phenomenon of mechanical and acoustic properties is also presented by our work. Overall, this work presents a new concept to use ML and genetic algorithm for multi-functional inverse design for shell lattice metamaterials.

Advancing the utilization of 2D materials for electrocatalytic seawater splitting

AbstractApplying catalysts for electrochemical energy conversion holds great promise for developing clean and sustainable energy sources. One of the main advantages of electrocatalysis is its ability to reduce conversion energy loss significantly. However, the wide application of electrocatalysts in these conversion processes has been hindered by poor catalytic performance and limited resources of catalyst materials. To overcome these challenges, researchers have turned to two‐dimensional (2D) materials, which possess large specific surface areas and can easily be engineered to have desirable electronic structures, making them promising candidates for high‐performance electrocatalysis in various reactions. This comprehensive review focuses on engineering novel 2D material‐based electrocatalysts and their application to seawater splitting. The review briefly introduces the mechanism of seawater splitting and the primary challenges of 2D materials. Then, we highlight the unique advantages and regulating strategies for seawater electrolysis based on recent advancements. We also review various 2D catalyst families for direct seawater splitting and delve into the physicochemical properties of these catalysts to provide valuable insights. Finally, we outline the vital future challenges and discuss the perspectives on seawater electrolysis. This review provides valuable insights for the rational design and development of cutting‐edge 2D material electrocatalysts for seawater‐electrolysis applications.image

Highly-Branched PtCu Nanocrystals with Low-Coordination for Enhanced Oxygen Reduction Catalysis.

Low-coordination platinum-based nanocrystals emanate great potential for catalyzing the oxygen reduction reactions (ORR) in fuel cells, but are not widely applied owing to poor structural stability. Here, several PtCu nanocrystals (PtCu NCs) with low coordination numbers were prepared via a facile one-step method, while the desirable catalyst structures were easily obtained by adjusting the reaction parameters. Wherein, the Pt1Cu1 NCs catalyst with abundant twin boundaries and high-index facets displays 15.25 times mass activity (1.647 A mgPt -1 at 0.9 VRHE) of Pt/C owing to the abundant effective active sites, low-coordination numbers and appropriate compressive strain. More importantly, the core-shell and highly developed dendritic structures in Pt1Cu1 NCs catalyst give it an extremely high stability with only 17.2% attenuation of mass activity while 61.1% for Pt/C after the durability tests (30 000 cycles). In H2-O2 fuel cells, Pt1Cu1 NCs cathode also exhibits a higher peak power density and a longer-term lifetime than Pt/C cathode. Moreover, theoretical calculations imply that the weaker adsorption of intermediate products and the lower formation energy barrier of OOH* in Pt1Cu1 NCs collaboratively boost the ORR process. This work offers a morphology tuning approach to prepare and stabilize the low-coordination platinum-based nanocrystals for efficient and stable ORR.

Evaluating the effects of insoluble date fruit (Phoenix dactylifera L.) fibers on meat analogue patties composed of pea and wheat protein isolates

This study aimed to evaluate the effects of date pomace fibers (DF) on the physicochemical properties of plant-based ground patty analogues. Previously optimized pea and wheat protein isolates were incorporated with varying concentrations of DF, i.e., 0 %, 2.5 %, 5 %, 7.5 %, and 10 % w/w. The addition of DF increased water retention in the patties, leading to subsequent changes in the patty structure. Frequency sweep results confirmed that the presence of DF contributed to structural stability, where patties exhibited more solid-like characteristics and stronger internal bonds, which also increased hardness from ∼65 g to 160–175 g. This could positively correlate with the brittleness of the patties, where large deformation results showed that high DF formulations were more brittle, which reduced springiness, as evident in DF7.5 (from ∼2 mm in DF0 to 1.89 mm in DF7.5). The microstructure revealed that high DF content increased patty fibrousness and led to a uniform structure. Therefore, high DF concentrations seemed to positively impact the analogue structure. DF also contributed to patty analogue color by imparting brown–red tones which may result in a closer appearance to conventional beef patties. This study establishes a foundation for further studies to be conducted on determining the optimum DF concentration that yields patty analogues with desirable structure as well as appearance.

Controllable Preparation of a Cu NCs@Zn-MOF Hybrid with Dual Emission Induced by an Ion Exchange Strategy for the Detection of Explosives.

The precise synthesis of Cu NCs is a highly desirable and controllable route for the preparation of desired structures and properties, which facilitates the rational design of valuable probes for fluorescence sensing and the understanding of structure-property relationships. Herein, an ion-exchange strategy combined with a bottom-up synthetic approach was utilized in the synthesis process of Cu NCs for the first time, which achieved the controllable synthesis of Cu NCs and in situ anchoring of Cu NCs on the support material HPU-14. The as-prepared Cu NCs@HPU-14-4h not only had a good peroxidase-like property but also exhibited stable dual-emitting fluorescence at 470 and 620 nm. Notably, the peroxidase-like property endowed Cu NCs@HPU-14-4h with the capability of highly sensitive colorimetric detection of H2O2 in a linear concentration from 0.1 to 140 μM (detection limit of 86.7 nM), and a change in the fluorescent color from red to blue could be observed by the naked eye. Furthermore, due to the large overlap between the absorption of 2,4,6-trinitrophenol (TNP) and the excitation band of Cu NCs@HPU-14-4h, TNP could also be detected from 27 types of analogs and common ions with a limit of detection of 68 nM. Finally, a portable hydrogel probe with efficient wipe sampling was fabricated by polyvinyl alcohol (PVA) comprising Cu NCs@HPU-14-4h with the aim of on-site visualization of different explosives. Consequently, the current study not only provides a new idea for the precise synthesis of Cu NCs and their controllable anchoring on support materials but also offers an effective method for predicting H2O2 and TNP.

A K2C2O4/nano-CaCO3 dual-templated method to prepare rich nitrogen-doped hierarchical porous carbon with excellent lithium storage performance

Three-dimensional interconnected porous carbon with diverse guest element doping is considered one of the most promising anode materials in lithium-ion batteries (LIBs) owing to their large lithium storage capacity and the acceleration effects on the electrochemical kinetics. However, the regulation of desirable pore structure and guest element amount and species for high energy density and stable cycling performance is still challenging. Herein, sucrose-based hierarchical N-doped porous carbon (SHC-750) is prepared via a facile one-step carbonization/activation process at 750 °C for 1 h. The K2C2O4 and nano-CaCO3 are employed as the dual activating-agent/template, and the urea is used as an N source. Benefiting from the hierarchical porous structure, abundant defects, and high amount of N/O-containing functional groups with a multi-chemical state, SHC-750 delivers an excellent reversible specific capacity (1051.2 mAh/g at 0.1 A/g and) and great cycling stability. Moreover, SHC-750 exhibits fast lithium ions diffusion kinetics, which is attributed to the special ordered and hierarchical pore structure. This work provides a new pathway for the preparation and application of 3D interconnected porous carbon materials in the field of electrodes.

THE SIGNIFICANCE OF THE ACQUISITION OF GERMAN FOR THE SOCIAL IDENTITY OF ROMANIAN NATIVE SPEAKERS: A CASE STUDY IN THE CONTEXT OF THE EVANGELICAL HONTERUS CONGREGATION IN KRONSTADT/BRAȘOV

The present article shows the results of a case study that was carried out among Romanian native speakers who take part with their children in the culturaleducational program of the Protestant community in Kronstadt/Brașov. The aim was to find out what meanings the Romanian parents ascribe to the acquisition of the German language and which desirable identities structure their investment in learning German. To answer the research question individual interviews with Romanian parents were conducted between September 2019 and February 2020 in Kronstadt/Brașov and a questionnaire was distributed to a sample of twenty-two Romanian native speakers who see the events organized by the Honterus community as a favorable environment for their children to practice the German language.

Arsenene/Ti2CO2 Heterojunction as a Promising Z‐Scheme Photocatalyst for Overall Water Splitting

AbstractIn order to address imminent energy and environmental challenges, photocatalytic water splitting emerges as a promising way for harnessing solar radiation to generate clean chemical energy. 2D arsenene (β‐As) has notable catalytic activity in hydrogen production. Based on first principles calculations and non‐adiabatic molecular dynamics (NAMD) simulations, the β‐As/Ti2CO2 heterojunction is predicted to be a promising Z‐scheme photocatalyst for overall solar water splitting. It has a desirable energy band structure with the valence band maximum of Ti2CO2 and the conduction band minimum of β‐As well below and above the redox potentials of H2O. Both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can proceed spontaneously under light irradiation. NAMD simulations confirm that it is a Z‐scheme photocatalyst with fast electron–hole combination dynamics. Instead of by intrinsic electric field, such a fast electron–hole combination is driven by a large nonadiabatic coupling. The heterojunction exhibits strong optical absorption in the visible and ultraviolet regions. The estimated solar‐to‐hydrogen (STH) efficiency limit of β‐As/Ti2CO2 reaches 32%, which is the highest among all β‐As based junctions reported in the literature. These results suggest that β‐As/Ti2CO2 is a promising photocatalyst for achieving overall water splitting.