Dimensional Network Structure Research Articles

Bulk transparent supramolecular glass enabled by host–guest molecular recognition

Supramolecular glass is a non-covalently cross-linked amorphous material that exhibits excellent optical properties and unique intrinsic structural features. Compared with artificial inorganic/organic glass, which has been extensively developed, supramolecular glass is still in the infancy stage, and itself is rarely recognized and studied thus far. Herein, we present the development of the host–guest molecular recognition motifs between methyl-β-cyclodextrin and para-hydroxybenzoic acid as the building blocks of supramolecular glass. Non-covalent polymerization resulting from the host–guest complexation and hydrogen bonding formation enables high transparency and bulk state to supramolecular glass. Various advantages, including recyclability, compatibility, and thermal processability, are associated with dynamic assembly pattern. Short-range order (host–guest complexation) and long-range disorder (three dimensional polymeric network) structures are identified simultaneously, thus demonstrating the typical structural characteristics of glass. This work provides a supramolecular strategy for constructing transparent materials from organic components.

α-PW11Fe(Co/Ni)/BC derived carbon fiber based nanocomposites for high efficiency electromagnetic wave absorption via synergistic effects of polarization and conductance

In order to enhance the wave-absorbing performance of dielectric/carbon fiber based wave-absorbing materials and explore the dissipative mechanism of electromagnetic wave (EMW), this study utilizes liquid diffusion of K4PW11O39Fe(III)(H2O) (α-PW11Fe), K5PW11O39Co(II)(H2O) (α-PW11Co), K5PW11O39Ni(II)(H2O) (α-PW11Ni) and bacterial cellulose (BC), as well as high temperature carbonization strategy to prepare polycrystalline polyphase transition metals and their compounds with three dimensional porous conductive network structure loaded carbon fiber based nanocomposites wave-absorbing materials. By changing the element type, drying mode and filling amount, we can achieve the tunability of electromagnetic parameters and absorbing properties. Impressively, the best synthesized sample 20 %-α-PW11Ni/BC derived carbon fiber based nanocomposites has excellent EMW absorption properties, with a maximum reflection loss (RL) of -68.1 dB at 2.6 mm matching thickness. The effective absorbing bandwidth (EAB) is 7.2 GHz, and the RL less than -10 dB in the frequency band of 2.2–5.0 mm thickness is 5.3 to 18.0 GHz. The excellent absorbing performance is attributed to the synergy of polarization and conductance, balanced impedance matching, good interface/dipole polarization, and multiple reflections and scattering. Therefore, the prepared composite has a broad application prospect in the field of EMW absorption, and provides a new idea for the design of new efficient absorbing materials.

Influence of styrene-acrylic emulsion additions on the electrical and self-sensing properties of CNT cementitious composites

Carbon nanotube (CNT) cementitious composite sensors are considered as an effective method for monitoring the health of building structures owing to their good self-sensing properties. However, previous studies have shown that the high electrical conductivity imparted by CNTs to cement-based materials can increase the risk of steel corrosion. To overcome this drawback and further enhance the piezoresistive performance of the material, a new method has been proposed in this study to improve the self-sensing properties of CNT-cement composites by incorporating styrene-acrylic emulsion (SAE) in them. The results show that the electrical resistivity of CNT-cement composites increases significantly with the addition of SAE, which is attributed to the polymer film hindering the mutual contact of the CNTs and ion migration. In addition, the piezoresistive properties of the composite sensor are significantly improved owing to the CNT/SAE three- dimensional network structure of the conductive system established in the cement matrix. The CNT-cement composite sensor containing 10 wt% SAE exhibits the best self-sensing properties and can reach a stress sensitivity of 22.1 × 10–3 MPa−1. The utilization of polymers as reinforcement for CNT-cementitious materials presents an economical and efficient approach for fabricating piezoresistive stress sensors intended for SHM applications.

Octylamine regulating the mechanical robustness of natural rubber by involving in the construction of crosslinking network

The formation of three dimensional network structure is critical in determining mechanical properties of natural rubber (NR). Consequently, it is vital to regulate crosslinking network of NR by controlling vulcanization process. Inspired by our previous studies on contribution of non-rubber components (NRCs) to the excellent properties of NR, we find octylamine in NRCs decreases the activation energy (Ea) of vulcanization from 82.73 kJ/mol to 44.34 kJ/mol, thereby reducing vulcanization time from 18.67 min to 2.71 min. From microscopic perspective, octylamine tends to coordinate with zinc ions to improve dispersion of ZnO in NR. And octylamine promotes ring-opening reaction of S8 to favor formation of polysulfide intermediates.Therefore, the incorporation of octylamine remarkably improves vulcanization efficiency, which contributes to the formation of a more homogeneous network with higher crosslinking density, enhancing remarkably the strength and toughness of NR. As a result, the tensile strength and fracture energy of samples are as high as 31.15 MPa and 68.88 kJ/m2, respectively. In addition, even with a 60 % reduction in ZnO content, the NR samples still maintain high vulcanization efficiency and excellent mechanical properties after the addition of octylamine, which provides a green and feasible way to alleviate the environmental pollution caused by ZnO.

3D conductive molecular framework derived MnO2/N, P co-doped carbon as sulfur hosts for high-performance lithium‑sulfur batteries

The practical application of lithium-sulfur (LiS) batteries is impeded by the shuttle effect and slow redox reaction kinetics, resulting in rapid capacity decay and low Coulombic efficiency. Three dimensional (3D) carbon-based network structure is used as sulfur host due to its special properties, such as high porosity and high conductivity. In this work, 3D MnO2/N, P co-doped carbon (3D MnO2/NPC) composites were achieved via freeze-drying MnO2/polyaniline composite aerogel followed by carbonizing process. The strongly polar MnO2 skeleton can provide sufficient adsorption capacity to anchor polysulfide and the heteroatom-doped carbon can compensate for the poor conductivity of MnO2 to guarantee the participation of rapid electrochemical reactions. As a result, the MnO2/NPC/S cathode demonstrates an initial specific discharge capacity of 1189 mAh g−1 at 0.2 C and a high rate capability of 569.2 mAh g−1 at 5 C, as well as excellent long-term cycling performance with the capacity decay rate of 0.033 % per cycle for 1000 cycles at 1 C. Moreover, the cathode exhibits excellent cycling stability even at a high sulfur loading of 6 mg cm−2.

Dual-Functional Ln-OFs for Efficient Luminescence Sensing and Photoreduction of Cr(VI) without Additional Photosensitizers and Cocatalysts

Six isostructural stable lanthanide metal–organic Frameworks (Ln-OFs), namely, [Ln(ADBA)(HCOO)(DMF)] (Ln = Sm(1), Tb(2), Dy(3), Ho(4), Er(5), Eu(6), H2ADBA = 4,4′-(anthracene-9,10-diyl)dibenzoate, DMF = N,N-dimethylformamide), have been successfully obtained by the solvothermal method based on an aromatic carboxylic acid ligand H2ADBA. 1–6 have a similar three dimensional (3D) network structure with pts topology based on dinuclear metallic clusters {Ln2}. 1–6 all have excellent chemical and thermal stabilities, which is beneficial to carrying out fluorescence sensing and achieving catalytic reactions. 1–6 show admirable fluorescent properties in aqueous solution and can quickly and efficiently detect Fe3+, Cr2O72–, and nitrofurazone (NZF) with high selectivity and excellent sensitivity. Remarkably, upon completion of detection, the Cr2O72– ion in wastewater can be reduced into Cr3+ by photocatalyst 1, which is ascribed to its broad-range visible-light absorption and recyclable stability. During the reduction process, ethanol is an optimal hole scavenger; 1 shows an excellent convert efficiency (99%), a high rate constant (k) of 0.066 min–1, and a high Cr(VI) reduction rate of 0.158 mgCr(VI)·g–1cata·min–1 at pH = 2. Furthermore, photocatalyst 1 can be reused for three cycles without significant loss of catalytic activity. Until now, it is the first example to report that the photocatalytic reduction of Cr(VI) is achieved only by using 3D rare earth MOFs without additional photosensitizers and cocatalysts. The reasonable mechanisms of luminescence sensing and photocatalytic reaction were also investigated systematically via indispensable testing technologies and theoretical simulated calculation.

Engineering Dirac cones and topological flat bands with organic molecules

We investigated polyhedral \ensuremath{\pi}-conjugated molecules with threefold rotation symmetry, which can be suitable building blocks for both Dirac cones and a topological flat-band system. The two dimensional network structures of such molecules can be characterized by intra- and intermolecular interactions. We constructed tight binding models of these structures by systematically changing the intra- $({t}_{0})$ and intermolecular $({t}_{1})$ transfer integrals as independent parameters. The degree of freedom for the interactions provides a topological flat band and a massless or massive Dirac cone. We analyzed the topological features and origins of the flat band and Dirac cone of a molecule-based triangular lattice.

Copper(II) and zinc(II) complexes bridged by benzenoid aromatic oxocarbon and dicarboxylate dianions

A novel series of Cu(II) and Zn(II) complexes were constructed through the bridging croconate (C5O5)2−, squarate (C4O4)2− and 2,5-pyridine-dicarboxylate (Py2,5-dc)2− dianions. These include pent- [Cu5(epdmpy)4(C5O5)2(H2O)6](ClO4)6‧12H2O (1) and tri-nuclear [Cu3(bepza)2(Py2,5-dc)2(ClO4)2(H2O)2]‧2H2O (4), dinuclear [Zn2(MeDPA)2(C4O4)(H2O)4](ClO4)2 (7), and 1-D- coordination polymers (CPs) catena-{[Cu2(bpzpy)2(C5O5)](ClO4)2‧MeOH} (2) and catena-{[Zn(4,4′-bipy)(H2O)4](C5O5)(H2O)} (6) as well as the mononuclear [Cu(HBph2,2′-dc)(pmdien)]ClO4 (5) have been synthesized and spectroscopically characterized as well as by single crystal X-ray crystallography. The reaction of aqueous solution Cu(ClO4)2, pymeea and C5O52− resulted in the unprecedently bis(oxalato) [Cu2(Pymeea)2(C2O4)(ClO4)2(H2O)2] (3). In these complexes, (C5O5)2−, squarate (C4O4)2− and (Py2,5-dc)2− ligands display a variety of coordination bonding modes. In complexes 1 and 2 the croconato is binding as 1,2-bidentate-3-monodentate but in addition 5-mono-dentate semi-coordinate bonding was detected for 2, whereas in 6 as counter dianion. The bonding mode in the squarato 7 was achieved through the trans μ1,3-mono-dentate. In the di-carboxylato compounds, only five-membered chelate ring was formed in 5via one of the carboxylate groups, whereas in 4 bridging was conducted through a mono-carboxylate and five-membered chelate ring including the second carboxylate and pyridyl nitrogen. In complexes 1–5 and 7, hydrogen bonds of type OH⋯O and/or NH⋯O are connecting the complex cations with the perchlorate anions/ligands to generate different dimensional supramolecular network structures, whereas in 6, the 3D network was formed through hydrogen bonding between the coordinated aqua and lattice water molecules. Non-covalent ring⋯ring interactions were also observed between pyridyl rings in complexes 1, 6 and 7, and between pyrazolyl rings as well as pyridyl ring in 2.

Use of Exploratory Graph Analysis in Inspecting the Dimensionality of the Revised University of California Los Angeles (R-UCLA) Loneliness Scale Among Older Adults.

Exploratory graph analysis (EGA) based on network theory has been introduced as a highly reliable and effective method to assess scales' dimensionality. We estimated the dimensional network structure of the Revised University of California Los Angeles Loneliness Scale using EGA among a cross-sectional cohort of Korean older adults living alone (N = 1,041). We also evaluated the stability of estimates using a bootstrap version of EGA (bootEGA) and verified the overall fit structure using confirmatory factor analysis (CFA). EGA revealed a two-dimensional structure of the scale initially. The bootEGA result revealed that Item 4 ("I do not feel alone") did not sufficiently load on any dimension, and Item 20 ("There are people I can turn to") was replicated in two or more dimensions. Removing these items resulted in better stability of the dimensions, leading to excellent structural consistency. CFA confirmed a satisfactory fit of the improved structure. [Research in Gerontological Nursing, 16(1), 15-20.].

Performance of Lithium Ion Battery with Graphene Microstructure in Cathode

Lithium-ion battery is a promising energy source with high output voltage, large energy density, low auto discharge, and no memory effect. Graphene, as a dimensional carbon material, has excellent electrical conductivity, strong mechanical properties, a large specific surface area, which has been widely applied in lithium-ion battery for modifying the cathode material of lithium secondary batteries, thus significantly promoting the flow performance, conductivity, and cycling stability of Li secondary batteries. In this review, we discussed the excellent properties of various cathode materials based on graphene with different microstructures including three dimensional network structure, Core/Shell structure, layered structure, porous structure, and sandwich structure, which could provide motivations for improving the performance of the lithium-ion battery.

Adjusting the interfacial property and emulsifying property of cellulose nanofibrils by ultrasonic treatment combined with gelatin addition

In this work, the effect of different ultrasonic power (0, 15%, 45%, and 75%) and different gelatin concentration (0, 0.5%, 1.0%, and 1.5%, w/v) on the interfacial property and emulsifying property of cellulose nanofibrils (CNF) obtained by ball milling treated were studied. Results showed that ultrasonic treatment destroyed the original structure and amorphous region of CNF, exposed more hydroxyl (0.692–0.736) and hydrophobic regions, and increased the crystallinity (61.40%–69.10%) and wettability (41.5°–65.6°) of CNF. The improved wettability promoted its adsorption at the oil-water interface, increased the interaction of CNF at the interface and then improved the stability of the interfacial film dominated by elasticity (5.78 mN/m-16.36 mN/m). Furthermore, gelatin was added by two step emulsification to further improve the stability of CNF-stabilized emulsion due to the poor stability. At a lower gelatin concentration (0.5%), the gelatin was mainly adsorbed in continuous phase and accompanied by slight interfacial adsorption. With the increase of gelatin concentration (1.0%–1.5%), the more gelatin was gradually adsorbed on the interface to replace CNF, formed the gelatin dominated interfacial film, and accompanied by the formation of a tight three dimensional network structure due to the improvement of the entanglement between gelatin and CNF (CLSM), and then significantly ( p < 0.05) increased the rheological properties, water holding capacity (WHC, 58.81%–73.28%) and stability of the emulsion. Therefore, this study could provide a theoretical basis for the regulation of interfacial property and emulsifying property of CNF. • Ultrasonic treatment improved the interfacial property of CNF. • The CNF treated by ultrasonic (75%) showed the most stable interfacial film. • The addition of gelatin could obviously enhance the emulsifying property of CNF. • Gelatin could cooperate with CNF to form a compact three dimensional network. • The CNF/gelatin-stabilized emulsion showed great stability.

Fabrication of Superhydrophobic/Superoleophilic Bamboo Cellulose Foam for Oil/Water Separation.

Water is an indispensable strategic resource for biological and social development. The problem of oily wastewater pollution originating from oil spillages, industrial discharge and domestic oil pollution has become an extremely serious international challenge. At present, numerous superwetting materials have been applied to effectively separate oil and water. However, most of these materials are difficult to scale and their large-scale application is limited by cost and environmental protection. Herein, a simple, environmentally friendly strategy including sol-gel, freeze-drying and surface hydrophobic modification is presented to fabricate a bamboo cellulose foam with special wetting characteristics. The bamboo cellulose foam is superhydrophobic, with a water contact angle of 160°, and it has the superoleophilic property of instantaneous oil absorption. Owing to the synergistic effect of the three-dimensional network structure of the superhydrophobic bamboo cellulose foam and its hydrophobic composition, it has an excellent oil-absorption performance of 11.5 g/g~37.5 g/g for various types of oil, as well as good recyclability, with an oil (1,2-dichloroethane) absorption capacity of up to 31.5 g/g after 10 cycles. In addition, the prepared cellulose-based foam exhibits an outstanding performance in terms of acid and alkali corrosion resistance. Importantly, owing to bamboo cellulose being a biodegradable, low-cost, natural polymer material that can be easily modified, superhydrophobic/superoleophilic bamboo cellulose foam has great application potential in the field of oily wastewater treatment.

Solid–Waste–Derived Geopolymer–Type Zeolite–like High Functional Catalytic Materials Catalyze Efficient Hydrogenation of Levulinic Acid

Three common solid wastes (waste incineration fly ash, sewage sludge, and polluted soil) were the raw materials used in the synthesis of a geopolymer–type zeolite–like product, which was then used as a catalyst carrier to prepare a nickel hydrogenation catalyst for the catalytic hydrogenation of levulinic acid to γ–valerolactone. Under optimum synthesis conditions, the synthesized geopolymer zeolite has excellent structure and performance. The characterization results show that the composites have a three–dimensional network structure, and the pore structure is homogeneous mesoporous or microporous. In this work, the results of catalytic hydrogenation show that the yield of γ–valerolactone can achieve up to 94% using the synthesized catalyst, which is comparable to that of commercial catalysts and the concentrations of typical polluting heavy metals of Cu, Zn, Pb, and Cd in the reaction solution were all below the emission concentration limit (Class I standard) after five cycles of reaction. In summary, this geopolymer–type zeolite–like catalyst is cheap and has excellent performance; it is, therefore, expected to be widely used in catalysis instead of commercial carriers.

Preparation of ε-polylysine and hyaluronic acid self-assembled microspheres loaded bacterial cellulose aerogels with excellent antibacterial activity

ε-Polylysine (ε-PL) is a broad antibacterial polymer. In this work, ε-PL and hyaluronic acid (HA) were self-assembled into microspheres and loaded into regenerated bacterial cellulose (RBC) to prepare RBC/HA/ε-PL aerogels. The RBC/HA/ε-PL aerogel showed a three- dimensional network structure with high porosity. The antibacterial activity of the prepared RBC/HA/ε-PL aerogel against E. coli, C. albicans and S. aureus was carried out by bacterial growth evaluation, bacteria fluorescent stain, bacterial morphology observation and the leaked protein determination. The results showed that RBC/HA/ε-PL aerogel exhibited excellent antibacterial performance by destroying the cell membranes. This work provides a novel and green material prepared by natural polymers, with potential applications in antibacterial materials area.

Enhanced electromagnetic microwave absorption of SiC nanowire-reinforced PDC-SiC ceramics catalysed by rare earth

Rare earth elements can modulate the dielectric constant of materials and significantly improve their dielectric properties. Herein, SiCnws/SiC ceramics were prepared through polymer derived ceramics (PDCs) technology with rare earth Sc particles as the catalyst. The Sc particles promote the precipitation of SiC and C from the matrix. Furthermore, the SiCnws, grown via the vapour-liquid-solid (VLS) mechanism, construct the three dimensional (3D) network structure to improve impedance matching and loss characteristics. Remarkably, the SiCnws/SiC ceramics minimum reflection coefficient (RCmin) achieved a value of −33.2 dB at 9.4 GHz with a thickness of 2.75 mm, and the effective absorption bandwidth (EAB) was 4.2 GHz covering the whole X band. When microwaves permeated into the SiCnws/SiC ceramics, those trapped in the 3D network structure underwent a variety of microwave energy dissipation processes, including multiple reflections, scattering, and interface and dipole polarisation. Consequently, SiCnws-reinforced PDC-SiC ceramics catalysed by rare earth emerge as a promising new approach to enhance electromagnetic (EM) wave absorption performance.

Plant extract delivery and antibacterial properties of nano bacterial cellulose in the presence of dendrimer, chitosan, and herbal materials

This study mainly aimed to evaluate the antibacterial impact of bacterial cellulose (BC) including dendrimer, chitosan, Henna, Green tea and Malva sylvestris in various bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. The produced bacterial cellulose was evaluated by antimicrobial (AATCC 25923 and AATCC 27853), cytotoxicity, swelling, drug delivery, scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy tests. Antibacterial activity raised with increasing concentration of herbals and the most of antimicrobial effect belonged to G. tea. Cytotoxic test demonstrated that all of the samples did not have cytotoxic effect and viability percent for sample of BC with Henna, G. tea, and M. sylvestris extract were respectively 95.87%, 94.69% and 90.64%. Among the samples, the G. tea sample has the most swelling. In addition, delivery of the drug in water and phosphate buffer medium was the controlled release. Additionally, the most of the release related to the herbal drug Henna. SEM results showed BC with a highly porous three dimensional network structure. The considerable role of chitosan and dendrimer was evident in drug uptake and release. FTIR analysis demonstrated the presence of active groups in BC structure.

Effect of agar hydrogel and magnesium ions on the biomimetic mineralization of calcium carbonate

Here, agar hydrogel was selected as diffusion medium and template to control the biomimetic mineralization of calcium carbonate (CaCO3). Due to three dimensional network structures and abundant functional groups (such as, hydroxyl groups), Ca2+ ions were uniformly distributed in the network and electrostatically attracted. The diffusion speed and range of CO32− ions were mediated by the concentration of hydrogel medium. Under the synergistic effect of Mg2+ ions, the crystal CaCO3 was induced by gas phase diffusion method in the hydrogel system. The results showed that the concentrations of Mg2+ ions and agar hydrogel had no obvious effect on the calcite phase of CaCO3, but the morphologies and sizes changed with concentrations of medium and Mg2+ ions. Attribute to template effect, the crystallization behavior and growth rate of CaCO3 crystals were regulated. Since Mg2+ ions were easily adsorbed on the surfaces of unit cell, the unique structure of CaCO3 was precisely controlled. This study provides a useful reference and inspiration for the understandings of the contributions of ion supply rate in bio-mineralization and hydrogel medium in biomimetic mineralization.

Ultrafast Microfiber Humidity Sensor Based on Three Dimensional Molybdenum Disulfide Network Cladding

We demonstrate an ultrafast humidity micro-fiber sensor based on molybdenum disulfide (MoS2) cladding with three dimensional network structure. The high surface-to-volume rations and porous mesh structure improve the interaction of between MoS2 and water molecules, further enhancing the performance of the humidity sensor. The results demonstrated that the sensor can perform in a wide relative humidity (RH) range between 10%RH to 90%RH with rapid dynamic behavior (response and recovery time are 0.090 and 0.130 s respectively). The sum of response and recovery time (total time) is 0.220 s, which is the fastest in the reported MoS2-based humidity sensors. The sensitivity of this sensor is up to -1.501 dB/%RH in the RH range (77%RH–90%RH). Such a high performance RH sensor will have a wide range of application potential in chemical processing, various medical diagnostics, and so on.

Combined multiple random features least mean square algorithm for online applications

The multikernel least mean square (MKLMS) algorithm is a classical algorithm of multikernel adaptive filters due to its simplicity. However, the linear growth network structure is a main challenge of MKLMS. To address this issue, a novel multiple random features least mean square (MRFLMS) algorithm is proposed by approximating multiple Gaussian kernels with the multiple random features method. In addition, a combined weight transfer strategy is adopted in MRFLMS to develop another combined multiple random features least mean square (CMRFLMS) algorithm to alleviate the influence of step-size on filtering performance and convergence rate. CMRFLMS with a fixed dimensional network structure can provide comparable performance and faster convergence rate than MKLMS. Simulations on prediction of synthetic and real non-linear system identification illustrate the superiorities of the proposed CMRFLMS algorithm from the aspects of filtering accuracy, convergence rate, and tracking performance.

A bionic cellulose nanofiber-based nanocage wound dressing for NIR-triggered multiple synergistic therapy of tumors and infected wounds

Tumor recurrence and drug-resistant bacterial infection are the main reasons that wounds heal with difficulty after skin tumor treatment. The near infrared- (NIR-) and pH-responsive, bionic, cellulose nanofiber-based (CNF-based) nanocage wound dressing with biocompatibility, bioviscosity, and shape adaptability is designed for dual NIR-triggered photothermal therapy of tumor and infection-induced wound healing. The wound dressing with the intertwining three dimensional (3D) nanocage network structure is skillfully constructed using NIR-responsive cellulose nanofibers and pH-responsive cellulose nanofibers as the skeleton, which endows the dressing with a high drug-loading capacity of doxorubicin (400 mg·g-1), and indocyanine green (25 mg·g-1). Moreover, the NIR- and pH-responsive bionic “On/Off” switches of the dressing enable a controllable and efficient drug release onto the wound area. The dual NIR-triggered wound dressing with excellent photothermal conversion performance possesses good antibacterial properties against Escherichia coli, Staphylococcus aureus, and drug-resistant Staphylococcus aureus. It could effectively eliminate bacterial biofilms and kill A375 tumor cells. Interestingly, the bionic wound dressing with shape adaptability could adapt and treat irregular postoperative skin tumor wounds and drug-resistant bacterial infection via the synergistic therapy of photothermal, photodynamic, and chemotherapy, which provides an ideal strategy for clinical intervention.