Ho-Ion-Polymer/Graphene Heterojunctions Toward Room-Temperature Ferromagnets.

Organic ferromagnetic materials offer great promise for spintronic devices, carbon-based chips, and quantum communications, but remain as a challenging issue due to their low saturation magnetization and/or unsustainable ferromagnetic properties. To date, magnetic ion polymers have displayed paramagnetism without exception at room-temperature. In this study, it is reported for the first time that, owing to the structural restriction and charge exchange of Ho ion by polymer/graphene π-π stacking heterojunctions, holmium ion polymer composites exhibited typical hysteresis lines of ferromagnetic materials at room temperature. The room-temperature ferromagnetic ion polymer composite presented the highest saturation magnetization value of 3.36 emu g-1 and unprecedented sustainable ferromagnetism, compared to reported room-temperature organic ferromagnetic materials. Accordingly, prepared ferromagnetic composites also achieved impressive wave absorption properties, with a maximum reflection loss of as much as -57.32 dB and a broad absorption bandwidth of 5.05 GHz. These findings may promote the development of room-temperature organic ferromagnetic materials.

Fine mapping of powdery mildew and stripe rust resistance genes Pm5V/Yr5V transferred from Dasypyrum villosum into wheat without yield penalty.

KEY MESSAGE: The novel wheat powdery mildew and stripe rust resistance genes Pm5V/Yr5V are introgressed from Dasypyrum villosum and fine mapped to a narrowed region in 5VS, and their effects on yield-related traits were characterized. The powdery mildew and stripe rust seriously threaten wheat production worldwide. Dasypyrum villosum (2n = 2x = 14, VV), a relative of wheat, is a valuable resource of resistance genes for wheat improvement. Here, we describe a platform for rapid introgression of the resistance genes from D. villosum into the wheat D genome. A complete set of new wheat-D. villosum V (D) disomic substitution lines and 11 D/V Robertsonian translocation lines are developed and characterized by molecular cytogenetic method. A new T5DL·5V#5S line NAU1908 shows resistance to both powdery mildew and stripe rust, and the resistances associated with 5VS are confirmed to be conferred by seedling resistance gene Pm5V and adult-plant resistance gene Yr5V, respectively. We flow-sort chromosome arm 5VS and sequence it using the Illumina NovaSeq 6000 system that allows us to generate 5VS-specific markers for genetic mapping of Pm5V/Yr5V. Fine mapping shows that Pm5V and Yr5V are closely linked and the location is narrowed to an approximately 0.9 Mb region referencing the sequence of Chinese Spring 5DS. In this region, a NLR gene in scaffold 24,874 of 5VS orthologous to TraesCS5D02G044300 is the most likely candidate gene for Pm5V. Soft- and hard-grained T5DL·5V#5S introgressions confer resistance to both powdery mildew and stripe rust in diverse wheat genetic backgrounds without yield penalty. Meanwhile, significant decrease in plant height and increase in yield were observed in NIL-5DL·5V#5S compared with that in NIL-5DL·5DS. These results indicate that Pm5V/Yr5V lines might have the potential value to facilitate wheat breeding for disease resistance.

Highly Sensitive Multifunctional Electronic Skin Based on Nanocellulose/MXene Composite Films with Good Electromagnetic Shielding Biocompatible Antibacterial Properties.

Electronic skin has aroused extensive research interest due to high similarity with human skin. Realizing a multifunctional electronic skin that is highly consistent with skin functions and endowed with more other functions is now a more urgent need and important challenge. Here, we use 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized cellulose nanofibril (TOCN) dispersion and highly conductive Ti3C2TX dispersion to prepare TOCN/Ti3C2TX composite film through vacuum-assisted filtration. The obtained composite film imitating the nacre-like lamellar structure of natural shells has good mechanical properties (124.6 MPa of tensile strength). Meanwhile, the composite film also showed excellent electromagnetic shielding performance (36 dB), biocompatibility, and antibacterial properties. In addition, the piezoresistive sensor assembled from the composite film exhibited a high sensitivity (11.6 kPa-1), fast response and recovery time (≤10 ms), ultralow monitoring limit (0.2 Pa), and long-term stability (>10 000 cycles). It also could detect human daily activities such as finger bent, chewing, and so on.

Chitin/MoS2 Nanosheet Dielectric Composite Films with Significantly Enhanced Discharge Energy Density and Efficiency.

High-performance dielectric nanomaterials have received increasing attention due to their important applications in the field of energy storage. Among various dielectric materials, polymer nanocomposite is one of the most promising candidates. However, the problems of environmental pollution caused by polymer-based dielectric materials have been extensively studied in recent years, which need to be solved urgently, leading to the search for new biodegradable dielectric materials. Herein, we report composite materials based on biodegradable and renewable chitin and molybdenum disulfide (MoS2) nanosheets for the first time. The MoS2 nanosheets were first fabricated by glycerol/urea system and then KOH/urea aqueous solution was used to directly dissolve chitin at low temperature together with the dispersion of the MoS2 nanosheets in a simple green process. The two-dimensional MoS2 nanosheets possess high polarization strength, and a large specific surface area can enhance the interfacial polarization with chitin; meanwhile, it can serve as a charge breakdown barrier to hinder the propagation of electrical tree branches. The results also show that the dielectric constant and breakdown strength of the chitin/MoS2 nanocomposites were increased, while the dielectric loss remained low. When the MoS2 content was 5 wt %, the charge and discharge efficiencies of the composite film were more than 80%, and the breakdown strength also reached 350 MV m-1, thus resulting in a high discharge energy density of 4.91 J cm-3, which was more than twice of the neat chitin (2.17 J cm-3). Furthermore, the nanocomposite films exhibited good thermal stability. Therefore, these chitin-based nanocomposite films are promising as high-performance biomass-based dielectric capacitors.

Hydrophilic Magnetofluorescent Nanobowls: Rapid Magnetic Response and Efficient Photoluminescence.

Multifunctional integration based on a single nanostructure is emerging as a promising paradigm to future functional materials. In this paper, novel magnetofluorescence nanobowls built with ferroferric mandrel and quantum dots exoderm is reported. Magnetic mandrels are stacked into nanobowls though hydrophobic primary Fe3O4 nanocrystals dragged into anion polyelectrolyte aqueous solution via forced solvent evaporation. Bright luminescence core/shell/shell CdSe/CdS/ZnS quantum dots (QDs) are modified with cationic hyperbranched polyethylenimine (PEI). Through electrostatic interactions, positively charged PEI-coated QDs are anchored on the surface of magnetic mandrel. Under this method, the luminescence of QDs is not quenched by magnetic partners in the resultant magnetoflurescence nanobowls. Such magnetoflurescence nanobowls exhibit high saturation magnetization, superparamagnetic characteristics at room temperature, superior water dispersibility, and excellent photoluminescence properties. The newly developed magnetoflurescence nanobowls open a new dimension in efforts toward multimodal imaging probes combining strong magnetization and efficient fluorescence in tandem for biosensors and clinical diagnostic imaging.

Nitrogen-doped carbon dots from plant cytoplasm as selective and sensitive fluorescent probes for detecting p-nitroaniline in both aqueous and soil systems.

Nitrogen-doped carbon dots with excellent water- and ethanol-solubility were facilely prepared from plant cytoplasm via a one-step hydrothermal route and revealed as low-cost, label-free and highly sensitive and selective probes for detecting p-nitroaniline in both aqueous and soils owing to a proposed hydrogen-bonding effect.

Recent Progress of Functional Solvent-free Nanofluids: A Review.

Nanoparticles have aroused widespread interest because of their unique surface structure and nano effect, which presents novel characteristics like as sound, light, electricity, magnetism, and thermal properties. However, two critical defects have hindered their applications: (1) poor processability resulting from the high melting temperature (e.g., >1000 °C) for some inorganic nanoparticles; (2) the restriction of the nano effect caused by the easy aggregation of the nanoparticles. To solve those issues, solvent-free nanofluids (SNFs) with hard cores and flexible organic chains were successfully designed and fabricated at the beginning of the twenty-first century. The promising technology of SNFs not only solved the dispersion problem of nanomaterials but also imparted novel functionalization to nanoparticles. Up to now, many researchers have been devoted to developing diverse cores and flexible organic polymer chains to endow SNFs with particular functions, such as conductivity, fluorescence, lubricity, and so on. However, there are few review reports on the research progress in the fabrication and applications of functional SNFs. To gain a better understanding of SNFs, this paper presents an overall investigation into the development, fabrication, as well as the applications of functional SNFs.

Flexible and ultrasensitive piezoresistive electronic skin based on chitin/sulfonated carbon nanotube films.

Wearable electronic skin has gained increasing popularity due to its remarkable properties of high flexibility, sensitivity, and lightweight, making it an ideal choice for detecting human physiological activity. In this study, we successfully prepared e-skin using regenerated chitin (RCH) and sulfonated carbon nanotubes (SCNTs). The e-skin demonstrated brilliant mechanical and sensing properties, exhibiting a sensitivity of 1.75 kPa-1 within the 0-5 kPa range and a fast response-recovery time of <10 ms. Furthermore, it displayed an ultra-low detection limit of 1.39 Pa (5 mg), exceptional stability (up to 11,000 cycles), and a remarkable mechanical strength, reaching up to 50 MPa. Moreover, the e-skin was fabricated through a simple and economical approach. With the popularity of micro sensing devices, the e-skin holds tremendous potential for various applications, including wearable electronic devices, health and sports monitoring, artificial intelligence and other fields.

Shearo-caloric effect enhances elastocaloric responses in polymer composites for solid-state cooling.

Room-temperature elastocaloric cooling is considered as a zero-global-warming-potential alternative to conventional vapor-compression refrigeration technology. However, the limited entropy and large-deformation features of elastocaloric polymers hinder the creation of the breakthrough in their caloric responses and device development. Herein, we report that the addition of a small amount of inorganic nanofillers into the polymer induces the aggregate of the effective elastic chains via shearing the interlaminar molecular chains, which provides an additional contribution to the entropy in elastocaloric polymers. Consequently, the adiabatic temperature change of -18.0 K and the isothermal entropy change of 187.4 J kg-1 K-1 achieved in the polymer nanocomposites outperform those of current elastocaloric polymers. Moreover, a large-deformation cooling system with a work recovery efficiency of 56.3% is demonstrated. This work opens a new avenue for the development of high-performance elastocaloric polymers and prototypes for solid-state cooling applications.

Fluxible nanoclusters of Fe3O4 nanocrystal-embedded polyaniline by macromolecule-induced self-assembly.

We have prepared Fe3O4 nanocrystal-embedded polyaniline hybrids with well-defined cluster-like morphology through macromolecule-induced self-assembly. These magnetic and electrically conductive composite nanoclusters show flowability at room temperature in the absence of any solvent, which offers great potential in applications such as microwave absorbents and electromagnetic shielding coatings. This macromolecule-induced self-assembly strategy can be readily applied on the fabrication of other ion oxide/conjugated polymer composites to achieve robust multifunctional materials.

High-performance dielectric film capacitors based on cellulose/Al2O3 nanosheets/PVDF composites.

The design and preparation of novel renewable biomass-based dielectric composites have drawn great attention recently. Here, cellulose was dissolved in NaOH/urea aqueous solution, and Al2O3 nanosheets (AONS) synthesized by hydrothermal method were used as fillers. Then the regenerated cellulose (RC)-AONS dielectric composite films were prepared by regeneration, washing and drying. The two-dimensional AONS had a better effect on improving the dielectric constant and breakdown strength of the composites, so that the RC-AONS composite film with 5 wt% AONS content reached an energy density of 6.2 J/cm3 at 420 MV/m. Furthermore, in order to improve the dielectric energy storage properties of cellulose films in high humidity environment, the hydrophobic polyvinylidene fluoride (PVDF) was innovatively introduced to construct RC-AONS-PVDF composite films. The energy storage density of the prepared ternary composite films could reach 8.32 J/cm3 at 400 MV/m, which was 416 % improvement against that of the commercially biaxially oriented polypropylene (2 J/cm3), and could be cycled for >10,000 times under 200 MV/m. Concurrently, the water absorption of the composite film in humidity was effectively reduced. This work broadens the application prospect of biomass-based materials in the field of film dielectric capacitor.

Alicyclic polyimides with large band gaps exhibit superior high-temperature capacitive energy storage.

Flexible polymer dielectrics for capacitive energy storage that can function well at elevated temperatures are increasingly in demand for continuously advancing and miniaturizing electrical devices. However, traditional high-resistance polymer dielectrics composed of aromatic backbones have a compromised band gap (Eg) and hence suffer from low breakdown strength and a huge loss at high temperatures. Here, based on the density functional theory (DFT) calculations, rigid and non-coplanar alicyclic segments are introduced into the polyimide backbone to overcome the incompatibility of a high glass transition temperature (Tg) and large Eg. Thanks to the large optical Eg (∼4.6 eV) and high Tg (∼277 °C), the all-alicyclic polyimide at 200 °C delivers a maximum discharge energy density (Ue) of 5.01 J cm-3 with a charge-discharge efficiency (η) of 78.1% at 600 MV m-1, and a record Ue of 2.55 J cm-3 at η = 90%, which is 10-fold larger than that of the state-of-art commercial polyetherimides (PEIs). In addition, compared with aromatic polyimides, the all-alicyclic polyimide possesses a better self-clearing characteristic due to a smaller ratio of carbon to hydrogen and oxygen, which facilitates its long-term reliability in practical applications.

Corona-Poled Porous Electrospun Films of Gram-Scale Y-Doped ZnO and PVDF Composites for Piezoelectric Nanogenerators.

For digging out eco-friendly and well-performed energy harvesters, piezoelectric nanogenerators are preferred owing to their effortless assembly. Corona-poling promotes output performance of either aligned or porous PVDF electrospun films and higher piezoelectric output was achieved by corona-poled porous PVDF electrospun films due to more poled electret dipoles in pores. Increasing the duration of electrospinning rendered more electret dipoles in PVDF porous electrospun films, resulting in higher piezoelectric output. Moreover, corona-poled PVDF/Y-ZnO porous electrospun films performed better than corona-poled PVDF/ZnO porous electrospun films because of the larger polar crystal face of Y-ZnO. Flexible piezoelectric polymer PVDF and high-piezoelectric Y-ZnO complement each other in electrospun films. With 15 wt% of Y-ZnO, corona-poled PVDF/Y-ZnO porous electrospun films generated maximum power density of 3.6 µW/cm2, which is 18 times that of PVDF/BiCl3 electrospun films.

Polyimide Nanodielectrics Doped with Ultralow Content of MgO Nanoparticles for High-Temperature Energy Storage.

Advanced polymer dielectrics with high energy density at elevated temperatures are highly desired to meet the requirements of modern electronic and electrical systems under harsh conditions. Herein, we report a novel polyimide/magnesium oxide (PI/MgO) nanodielectric that exhibits high energy storage density (Ue) and charge-discharge efficiency (η) along with excellent cycling stability at elevated temperatures. Benefiting from the large bandgap of MgO and the extended interchain spacing of PI, the composite films can simultaneously achieve high dielectric constant and high breakdown strength, leading to enhanced energy storage density. The nanocomposite film doped with 0.1 vol% MgO can achieve a maximum Ue of 2.6 J cm-3 and a η of 89% at 450 MV m-1 and 150 °C, which is three times that of the PI film under the same conditions. In addition, embedding ultralow content of inorganic fillers can avoid aggregation and facilitate its large-scale production. This work may provide a new paradigm for exploring polymer nanocomposites with excellent energy storage performance at high temperatures and under a high electric field.

Hydrangea-like nanocellulose microspheres with high dye adsorption and drug encapsulation prepared by emulsion method.

Currently, microspheres with high adsorption capacity play a crucial role in dye adsorption and drug loading. In this study, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCN) could be used to form nanocellulose microspheres by the emulsion method. The prepared hydrangea-like nanocellulose microspheres presented a stable three-dimensional network porous structure and exhibited excellent adsorption properties. The TOCN microspheres had a high adsorption capacity for methylene blue (MB) and methyl orange (MO) with the optimal adsorption capacity of 412.1 mg g-1 and 286.5 mg g-1 under neutral conditions, respectively. The TOCN microspheres displayed excellent adsorption selectivity on MB/MO mixed dyes, which could be used to selectively adsorb MB. Besides, the encapsulation rate of the positively charged drug doxorubicin hydrochloride (DOX) was as high as 93 %, and the drug loading capacity was as high as 34.5 %. Overall, our prepared nanocellulose microspheres had great potential for application in dye adsorption and drug delivery systems.

Porous cellulose composite aerogel films with super piezoelectric properties for energy harvesting.

The piezoelectric effect is one of the most promising electromechanical coupling processes for mechanical energy conversion and energy harvesting. However, natural polymer based piezoelectric materials are of poor piezoelectric performance. we developed flexible porous piezoelectric aerogel films based on TEMPO-oxidized cellulose nanofibrils (TOCN) and MoS2 nanosheets. Those aerogel films possessed large specific surface areas and abundant mesopores. Moreover, they exhibited very good piezoelectric properties when a field strength of 20 MV/m was used to polarize MoS2 nanosheets and air in the mesopores. When assembled to piezoelectric nanogenerators (PENGs), a TOCN/MoS2 aerogel film PENG containing 6 wt% of MoS2 exhibited the best output performance. It generated an open circuit voltage of 42 V and a short-circuit current of 1.1 µA, a maximum area power density of 1.29 µW/cm2 and a maximum volume power density of 0.143 µW/cm3. These features enable them to be promising piezoelectric materials for energy harvesting.

TOCN/copper calcium titanate composite aerogel films as high-performance triboelectric materials for energy harvesting.

The development of high-performance cellulose-based triboelectric nanogenerators (TENG) has been a subject widely concerned by researchers. Here, we prepared a composite aerogel film based on TEMPO-oxidized cellulose nanofiber (TOCN) and copper calcium titanate (CaCu3Ti4O12, CCTO) nanoparticles. Under their comprehensive effects of the enhanced dielectric performance, the TOCN/CCTO-20 composite film with 20 % CCTO content based TENG device showed the best output performance of an open circuit voltage of 152 V, a short circuit current of 33.8 µA and a power density of 483 mW/m2, which were 3.37, 4.07 and 3.71 times higher than that of the pure TOCN based TENG device, respectively. In addition, effects of external force conditions, aerogel film size parameters and the agglomeration state of high filler content on the output performance were also studied. These results indicated that the TOCN/CCTO composite aerogel films can be used as efficient and low-cost cellulose-based triboelectric positive materials for energy harvesting.

Solid-state cooling by elastocaloric polymer with uniform chain-lengths.

Although the elastocaloric effect was found in natural rubber as early as 160 years ago, commercial elastocaloric refrigeration based on polymer elastomers has stagnated owing to their deficient elastocaloric effects and large extension ratios. Herein, we demonstrate that polymer elastomers with uniform molecular chain-lengths exhibit enormous elastocaloric effects through reversible conformational changes. An adiabatic temperature change of -15.3 K and an isothermal entropy change of 145 J kg-1 K-1, obtained from poly(styrene-b-ethylene-co-butylene-b-styrene) near room temperature, exceed those of previously reported elastocaloric polymers. A rotary-motion cooling device is tailored to high-strains characteristics of rubbers, which effectively discharges the cooling energy of polymer elastomers. Our work provides a strategy for the enhancement of elastocaloric effects and could promote the commercialization of solid-state cooling devices based on polymer elastomers.

Combination of retinoids and narrow-band ultraviolet B inhibits matrix metalloproteinase 13 expression in HaCaT keratinocytes and a mouse model of psoriasis.

Matrix metalloproteinase13 (MMP13) can be released by keratinocytes and fibroblasts and involved in the pathogenesis of skin disorders. Retinoic acid derivative drugs include tazarotene and acitretin. Tazarotene/acitretin and narrow-band ultraviolet B (NB-UVB) irradiation are common treatment options for psoriasis. However, their impact on MMP13 expression in the context of psoriasis has yet to be determined. The expression of MMP13 was analyzed in patients with psoriasis. The effects of tazarotene/acitretin and NB-UVB on MMP13 expression were also investigated in a mouse model of psoriasis. Human HaCaT keratinocytes were exposed to acitretin or NB-UVB and then assayed for cell proliferation and MMP13 expression levels. We showed that patients with psoriasis had increased levels of MMP13 protein in skin lesions and serum samples. Exposure to acitretin and NB-UVB irradiation alone or in combination led to reduction of cell proliferation and MMP13 expression in HaCaT cells. Consistently, tazarotene treatment or NB-UVB irradiation attenuated imiquimod-induced psoriasis-like dermatitis and decreased MMP13 expression in a mouse model. Based on these from HaCaT keratinocytes cells and animal experiments, we suggest that tazarotene/acitretin and NB-UVB irradiation can inhibit the expression of MMP13 in HaCaT keratinocytes and psoriasis mouse models. Blockade of MMP13 activity may have therapeutic potential in improving symptoms of psoriasis.

Effect of Stretching on Crystalline Structure, Ferroelectric and Piezoelectric Properties of Solution-Cast Nylon-11 Films.

Compared to polyvinylidene fluoride (PVDF) and its copolymers, castor-oil-derived nylon-11 has been less explored over the past decades, despite its excellent piezoelectric properties at elevated temperatures. To utilize nylon-11 for future sensor or vibrational energy harvesting devices, it is important to control the formation of the electroactive δ' crystal phase. In this work, nylon-11 films were first fabricated by solution-casting and were then uniaxially stretched at different stretching ratios (SR) and temperatures (Ts) to obtain a series of stretched films. The combination of two-dimensional wide-angle X-ray diffraction (2D-WAXD) and differential scanning calorimetry (DSC) techniques showed that the fraction of the δ' crystal phase increased with the stretching ratio and acquired a maximum at a Ts of 80 °C. Further, it was found that the ferroelectric and piezoelectric properties of the fabricated nylon-11 films could be correlated well with their crystalline structure. Consequently, the stretched nylon-11 film stretched at an SR of 300% and a Ts of 80 °C showed maximum remanent polarization and a remarkable piezoelectric coefficient of 7.2 pC/N. A simple piezoelectric device with such a nylon-11 film was made into a simple piezoelectric device, which could generate an output voltage of 1.5 V and a current of 11 nA, respectively.