Qiqihar University

Light-weight nanocomposites filled with carbon nanotubes (CNTs) are developed for their significant potentials in electromagnetic shielding and attenuation for wide applications in electronics, communication devices, and specific parts in aircrafts and vehicles. Specifically, the introduction of a second phase into/onto CNTs for achieving CNT-based heterostructures has been widely pursued due to the enhancement in either dielectric loss or magnetic loss. In this work, ferroferric oxide (Fe(3)O(4)) was selected as the phase in multiwalled carbon nanotube (MWCNT)-based composites for enhancing magnetic properties to obtain improved electromagnetic attenuation. A direct comparison between the two-phase heterostructures (Fe(3)O(4)/MWCNTs) and polyaniline (PANI) coated Fe(3)O(4)/MWCNTs, namely, three-phase heterostructures (PANI/Fe(3)O(4)/MWCNTs), was made to investigate the interface influences of Fe(3)O(4) and PANI on the complex permittivity and permeability separately. Compared to PANI/Fe(3)O(4)/MWCNTs, Fe(3)O(4)/MWCNTs exhibited enhanced magnetic properties coupled with increased dielectric properties. Interfaces between MWCNTs and heterostructures were found to play a role in the corresponding properties. The evaluation of microwave absorption of their wax composites was carried out, and the comparison between Fe(3)O(4)/MWCNTs and PANI/Fe(3)O(4)/MWCNTs with respect to highly efficient microwave absorption and effective absorption bandwidth was discussed.

With rapid development of 5G communication technologies, electromagnetic interference (EMI) shielding for electronic devices has become an urgent demand in recent years, where the development of corresponding EMI shielding materials against detrimental electromagnetic radiation plays an essential role. Meanwhile, the EMI shielding materials with high flexibility and functional integrity are highly demanded for emerging shielding applications. Hitherto, a variety of flexible EMI shielding materials with lightweight and multifunctionalities have been developed. In this review, we not only introduce the recent development of flexible EMI shielding materials, but also elaborate the EMI shielding mechanisms and the index for "green EMI shielding" performance. In addition, the construction strategies for sophisticated multifunctionalities of flexible shielding materials are summarized. Finally, we propose several possible research directions for flexible EMI shielding materials in near future, which could be inspirational to the fast-growing next-generation flexible electronic devices with reliable and multipurpose protections as offered by EMI shielding materials.

Abstract Vigorous development of 5G communication technologies can boost mobile networks yet bring in electromagnetic interferences and safety concerns in utilizing electronic devices. Particularly, 5G network can not only involve a low‐frequency band of n 78 (3.3–3.8 GHz) but also cover multi‐frequency bands of n 77 (3.3–4.2 GHz) and n 79 (4.4–5.0 GHz), displaying multiple electromagnetic radiations. Countless efforts have been devoted to investigating electromagnetic wave (EMW) absorbers with low‐ and multi‐band absorption properties. However, in terms of emerging materials and designs, few reports propose the mechanisms related to those properties. This perspective briefly reviews the impressive achievements of low‐ and multi‐frequency EMW absorbers and analyzes the design strategies that may enable low‐ and multi‐frequency absorption. Furthermore, the cutting‐edge mechanisms of corresponding electromagnetic responses, such as Snoek limit, quarter wavelength, and dielectric‐magnetic synergy effects are elaborated. Thus, this perspective can shed light on the new trends and ongoing challenges for EMW absorbers and further promote their practical application.

In this feature article, we report our recent progresses in fluorescent sensors of biological dyes from the viewpoint of supramolecular and bioorganic chemistry. For signalling fluorophores, we extended or created naphthalene-based ICT systems, e.g. amino-1,8-naphthalimides, amino-1,8-dicyanonaphthalenes and acenaphthopyrrol-9-carbonitriles. We also developed BODIPY derivatives with large Stokes shifts and high fluorescence quantum yields in polar solvents, and a rhodamine analogue working in strong competitive aqueous solution as well as its silaanthracene analogue with a bathochromic shift as large as 90 nm. For sensing mechanisms, we extended or developed the following methods to improve sensing: e.g. PET in a photogenerated electronic field, TICT promoted PET derived from aminoalkyl or piperazino aminonaphthalimides, and the translation/amplification effect of surfactant micelles or aggregation on fluorescent sensing. We also successfully designed deprotonation strengthened ICT, FRET-chemodosimeter sensing systems. For non-cyclic recognition receptors, naphthalimides with two or more side chains at their 4,5- or 3,4-positions, as a convenient and simple platform for ratiometric sensors, were created for the recognition of heavy and transition metallic cations; multi-armed polyamides with more side chains were innovated as a versatile platform for the sensing of metal ions with high affinity, selectivity and positive homotropic allosteric effects. We designed V-shape sensors of the bis(aminomethyl)pyridine receptor with two fluorophores to show high performance. Finally, the intracellular applications of the above sensors and dyes, e.g. imaging heavy and transition metal ions in cells, fluorescent marking of hypoxia of tumour cells, are also reviewed.

A novel "naked-eye" and ratiometric fluorescent zinc sensor (AQZ) of carboxamidoquinoline with an alkoxyethylamino chain as receptor was designed and synthesized. AQZ shows good water solubility and high selectivity for sensing; about an 8-fold increase in fluorescence quantum yield and a 75 nm red-shift of fluorescence emission upon binding Zn2+ in buffer aqueous solution are observed. Moreover, AQZ can enter yeast cells and signal the presence of Zn2+.

3D Fe₃O₄-MWCNTs, a novel nanostructure, exhibited excellent microwave absorption due to the synergy of dielectric loss and magnetic loss and the enhancement effect of multiple interfaces.

CO methanation reaction over the Ni/Al2O3 catalysts for synthetic natural gas production was systematically investigated by tuning a number of parameters, including using different commercial Al2O3 supports and varying NiO and MgO loading, calcination temperature, space velocity, H2/CO ratio, reaction pressure, and time, respectively. The catalytic performance was greatly influenced by the above-mentioned parameters. Briefly, a large surface area of the Al2O3 support, a moderate interaction between Ni and the support Al2O3, a proper Ni content (20 wt %), and a relatively low calcination temperature (400 °C) promoted the formation of small NiO particles and reducible β-type NiO species, which led to high catalytic activities and strong resistance to the carbon deposition, while addition of a small amount of MgO (2 wt %) could improve the catalyst stability by reducing the carbon deposition; other optimized conditions that enhanced the catalytic performance included high reaction pressure (3.0 MPa), high H2/CO ratio (≥3:1), low space velocity, and addition of quartz sand as the diluting agent in catalyst bed. The best catalyst combination was 20–40 wt % of NiO supported on a commercial Al2O3 (S4) with addition of 2–4 wt % of MgO, calcined at 400–500 °C and run at a reaction pressure of 3.0 MPa. On this catalyst, 100% of CO conversion could be achieved within a wide range of reaction temperature (300–550 °C), and the CH4 selectivity increased with increasing temperature and reached 96.5% at a relatively low temperature of 350 °C. These results will be very helpful to develop highly efficient Ni-based catalysts for the methanation reaction, to optimize the reaction process, and to better understand the above reaction.

Abstract VB‐Group transition metal disulfides (TMDs) are considered excellent materials for electromagnetic wave (EMW) absorption because of their good conductivity and abundant active sites located at their edges and substrates, as compared with VIB‐Group TMDs. Herein, for the first time, EMW absorbers based on VB‐Group NbS 2 nanosheets by using a facile one‐step solvothermal method are successfully prepared. The minimum reflection loss (RL min ) can reach up to 43.85 dB with an effective absorption bandwidth of 6.48 GHz (11.52–18.00 GHz). The remarkable EMW absorption performance can also be reflected in the tunable frequency bands (C‐, X‐, and Ku‐bands), which is achieved by adjusting the contents of materials. Furthermore, the influence of the content of 2H‐phase and 1T‐phase in NbS 2 on the EMW absorption performance is systematically investigated. The hierarchical hollow‐sphere structure of NbS 2 promotes dielectric loss and the multiple reflection and absorption of EMW, and enhances the impedance matching and synergistic attenuation ability. This work demonstrates that the bottleneck of effective absorbing frequency band of single‐component dielectric EMW absorbing materials could be broken through, and paves a novel path towards developing broadband absorbing materials in EMW absorption.

Two-dimensional (2D) nanomaterials are categorized as a new class of microwave absorption (MA) materials owing to their high specific surface area and peculiar electronic properties. In this study, 2D WS2–reduced graphene oxide (WS2–rGO) heterostructure nanosheets were synthesized via a facile hydrothermal process; moreover, their dielectric and MA properties were reported for the first time. Remarkably, the maximum reflection loss (RL) of the sample–wax composites containing 40 wt% WS2–rGO was − 41.5 dB at a thickness of 2.7 mm; furthermore, the bandwidth where RL < − 10 dB can reach up to 13.62 GHz (4.38–18 GHz). Synergistic mechanisms derived from the interfacial dielectric coupling and multiple-interface scattering after hybridization of WS2 with rGO were discussed to explain the drastically enhanced microwave absorption performance. The results indicate these lightweight WS2–rGO nanosheets to be potential materials for practical electromagnetic wave-absorbing applications.

A new process is optimized and presented for the recovery and regeneration of LiFePO₄ from spent lithium-ion batteries (LIBs).

Abstract Multiple relaxation behaviors are promising for broad frequency band and strong electromagnetic wave (EMW) absorption based on polarization‐controlled electromagnetic (EM) attenuation. However, rational selection of materials and structure manipulation through tunable substitution or phase control are challenging toward optimization of EMW absorption. Herein, bi‐metallic organic frameworks (B‐MOFs) with various morphologies are employed as EMW absorbers. Remarkably, the polar units can be enhanced by introducing Ni‐metal nodes into the Cu‐coordinated MOFs, rendering the B‐MOFs with self‐polarized properties and consecutive multifrequency EMW absorption behaviors. The maximum reflection loss of acetylene black (ACET) filled NiCu‐MOFs can reach –40.54 dB together with a wide bandwidth (&lt;‐10 dB) of 5.87 GHz at a thickness of 2.5 mm. As a counterpart of the Ni/Cu/C derivatives, significantly increased broad band absorption (6.93 GHz) and multifrequency absorbing and polarization characteristics are also maintained in bimetal coexisting carbonized architectures as prepared by calcination of CuNi‐MOFs. This work demonstrates that the performance of effective absorbing frequency band can be enhanced in multi‐metallic organic frameworks‐based architectures, and paves a novel avenue for developing broadband and strong EMW absorbers.

The development of sustainable and efficient absorbents for oil and organic pollutants cleaning is an attractive and challenging work. Here, novel superhydrophobic microfibrillated cellulose aerogels (HMFCAs) with high lipophilicity, ultralow density (≤5.08 mg/cm3), superior porosity (≥99.68%) as well as extremely high mechanical stability were successfully prepared from microfibrillated cellulose aerogels (MFCAs) via a facile and environmentally friendly silanization reaction in liquid phase. The superhydrophobicity of the as-prepared HMFCAs (water contact angle as high as 151.8°) was attributed to the formation of polysiloxane on the surface of HMFCAs by the silanization reaction. The HMFCAs exhibited excellent oil/water selective absorption capacity with oil absorption up to 159 g/g. The reusability experiment showed that the adsorption capacity still exceeded 92 g/g for pump oil after 30 absorption cycles, demonstrating its superior reusability. Our work paves the way for the development of sustainable and efficient absorbents toward oils and organic pollutant removal applications.

The construction of structures with multiple interfaces and dielectric/magnetic heterostructures enables the design of materials with unique physical and chemical properties, which has aroused intensive interest in scientific and technological fields. Especially, for electromagnetic (EM) wave absorption, enhanced interface polarization and improved impedence match with high Snoek's limitation could be achieved by multiple interfaces and dielectric/magnetic heterostructures, respectively, which are benificial to high-efficiency electromagnetic wave absorption (EWA). However, by far, the principles in the design or construction of structures with multiple interfaces and dielectric/magnetic heterostructures, and the relationships between those structures or heterostructures and their EWA performance have not been fully summarized and reviewed. This article aims to provide a timely review on the research progresses of high-efficency EM wave absorbers with multiple interfaces and dielectric/magnetic heterostructures, focusing on various promising EWA materials. Particularly, EM attenuation mechanisms in those structures with multiple interfaces and dielectric/magnetic heterostructures are discussed and generalized. Furthermore, the changllenges and future developments of EM wave absorbers based on those structures are proposed.

With the development of artificial intelligence, big data classification technology provides the advantageous help for the medicine auxiliary diagnosis research. While due to the different conditions in the different sample collection, the medical big data is often imbalanced. The class-imbalance problem has been reported as a serious obstacle to the classification performance of many standard learning algorithms. SMOTE algorithm could be used to generate sample points randomly to improve imbalance rate, but its application is affected by the marginalization generation and blindness of parameter selection. Focusing on this problem, an improved SMOTE algorithm based on Normal distribution is proposed in this paper, so that the new sample points are distributed closer to the center of the minority sample with a higher probability to avoid the marginalization of the expanded data. Experiments show that the classification effect is better when use proposed algorithm to expand the imbalanced dataset of Pima, WDBC, WPBC, Ionosphere and Breast-cancer-wisconsin than the original SMOTE algorithm. In addition, the parameter selection of the proposed algorithm is analyzed and it is found that the classification effect is the best when the distribution characteristics of the original data was maintained best by selecting appropriate parameters in our designed experiments.

Hemorrhage is common in surgery, and excessive bleeding is the main reason for trauma death. Effective control of bleeding is becoming more and more important in military and civilian trauma. In this work, oxidized cellulose nanocrystal/alginate composite films and sponges were successfully prepared and their usages as the hemostatic materials were investigated. Carboxyl functionalization on the cellulose nanocrystal surface not only played a fundamental role in the structural of composites, but also contributed to absorb plasma and stimulate erythrocytes and platelets. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra showed that the carboxyl groups were successfully introduced on the cellulose nanocrystal surface by TEMPO-mediated oxidization. The oxidized cellulose nanocrystals (TOCN)/alginate (SA) composites were in the presence of Ca2+ solution cross-linking. Physical properties tests results indicated that the ultrahigh porosity (sponge), surface homogeneity (film), water absorption ability, and chemical stability of TOCN-30/SA composite sponge, as well as TOCN-30/SA composite film, were all increased after ionic cross-linking, compared to the SA sponge and film, respectively. In vitro evaluation of the hemostatic effect, hemostatic time, and the blood loss in two injury models exhibited that TOCN-30/SA composite sponge had the most excellent hemostatic efficiency and could be biodegraded completely without inflammatory reaction after three weeks. In addition, the potential hemostatic mechanism of TOCN/SA composites was discussed.

was discussed.

Hydrothermally prepared vertical multilayer WS₂ nanosheets on the surface of few-layer MoS₂ for the ultra-sensitive NO₂ detection at room temperature.

The laminated transition metal disulfides (TMDs), which are well known as typical two-dimensional (2D) semiconductive materials, possess a unique layered structure, leading to their wide-spread applications in various fields, such as catalysis, energy storage, sensing, etc. In recent years, a lot of research work on TMDs based functional materials in the fields of electromagnetic wave absorption (EMA) has been carried out. Therefore, it is of great significance to elaborate the influence of TMDs on EMA in time to speed up the application. In this review, recent advances in the development of electromagnetic wave (EMW) absorbers based on TMDs, ranging from the VIB group to the VB group are summarized. Their compositions, microstructures, electronic properties, and synthesis methods are presented in detail. Particularly, the modulation of structure engineering from the aspects of heterostructures, defects, morphologies and phases are systematically summarized, focusing on optimizing impedance matching and increasing dielectric and magnetic losses in the EMA materials with tunable EMW absorption performance. Milestones as well as the challenges are also identified to guide the design of new TMDs based dielectric EMA materials with high performance.

Accurately tailoring electromagnetic (EM) materials for achieving high-performance EM interference (EMI) shielding is significantly imperative with increasing EM pollution worldwide. Green EMI shielding materials are attracting extensive attention because of the less additional environmental hazard caused by the lower secondary reflection. However, the conflict between high efficiency and eco-friendly nature makes green EMI shielding still challenging. In this work, a new strategy of turning a guest into a host is developed for the first time, and a unique WS2–rGO architecture of mountain-like wall is constructed successfully achieving efficient and green EMI shielding. The shielding efficiency (SE) is over 20 dB in the investigated frequency range (2–18 GHz) and the maximum was 32 dB with an endearing green index (gs ≈ 1.0). The efficient and green EMI SE is ascribed to the multilevel structure and intrinsic dielectric properties of the WS2–rGO architecture, including the synergy of relaxation and conduction, multi-scattering between the interface and void, and the equivalent wedge effect. These results demonstrate that the WS2–rGO architecture is a promising candidate in EM transducers, microwave imaging, EM protection, and energy devices.

Bioavailability of bioactive peptides (BAPs) represents the amount of peptides absorbed through normal pathways, after oral intake, and distributed in target tissues to exhibit bioactive properties. The small intestine is the primary location of the gastrointestinal tract where peptide absorption mainly occurs. BAPs are beneficial to health upon reaching their physiological sites of action without structural changes. Despite the rapid and dynamic evolvement of research into food peptides, there is still a knowledge gap regarding their bioaccessibility and bioavailability for systemic circulation to targeted organs. Beside the digestive actions of endogenous proteases and peptidases, chemical and nutritional compositions of the food matrix and their physical forms (e.g., liquid, puree, gel, solid) are also critical factors that can influence the interactions, digestibility, bioaccessibility and bioavailability of BAPs. Detailed understanding of such food matrix factors can be explored for enhancing the bioavailability of BAPs and achieving their positive health effects.