Search

CotA laccase was successfully expressed from Pichia pastoris. Magnetic reduced graphene oxide (MRGO) nanocomposite was synthesized and functionalized with iminodiacetic acid (IDA-NH2), and then chelated with Cu2+ for effective immobilization with His-tagged CotA laccase. The Cu2+-chelated MRGO (MRGO-IDA-Cu2+) showed 175 mg/g-support adsorption capacity. The immobilization of CotA laccase with MRGO-IDA-Cu2+ nano-hybrid composite was confirmed by Raman spectroscopy, Thermal Gravimetric Analysis, and X-ray diffraction. The use of nano-hybrid MRGO-IDA-Cu2+ composite to improve heavy oil recovery was investigated. The findings revealed that the interfacial tension between oil and water was reduced to ~ 90% of its original value, and the wettability was changed from the oil-wet state [θ = ∼ 115.2 − 124.5°] to the water-wet state [θ = ∼ 8.9 − 30.1°]. The increase of immobilized CotA laccase concentration and the ratio of nano-hybrid MRGO-IDA-Cu2+ composite decreases the value of interfacial tension (IFT) and contact angle (CA). The core-flooding studies revealed that the oil recovery process of 0.3 wt% nano-hybrid MRGO-IDA-Cu2+ composite was enhanced by 82.8%. Graphical Abstract

A stirring-assisted solution-based approach was developed to construct new 3D TiO2 hierarchical structures with excellent photocatalytic performance for the degradation of organic pollutants.

Precise control of value and dispersion characteristics of negative permittivity is still an unsolved problem in the practical application of random metamaterials. In this work, the ternary percolation nanocomposites (CNTs-GR-CCTO) were prepared via a low-temperature sintering process by using graphene (GR), carbon nanotubes (CNTs), and copper calcium titanate (CCTO). As the total carbon contents increased, the three-dimensional carbon network was formed, and negative permittivity is realized, which exhibits the Lorentz-type and Drude-type dispersion behaviors. The synergistic effect between GR and CNTs was studied in detail. While the GR sheets separate the CNTs, the CNTs also act as wires to connect the GR sheets. Controlled conductive paths were created by changing the ratio of CNTs to GR, achieving precise regulation of the negative permittivity, which is further certified by the equivalent circuit analysis. We provide a novel strategy for the precise regulation of negative permittivity of carbon-matrix metamaterials, which will greatly facilitate applications of metamaterials with negative permittivity. Precise regulation of weakly negative permittivity is achieved in CaCu3Ti4O12 metacomposites by synergistic effects of carbon nanotubes and graphene.

Simple biomolecule-based supramolecular nanomedicines hold great promise in cancer therapy, but their clinical translation is greatly hindered by low tumor-specificity and unsatisfactory antitumor performance. Herein, we developed an amino acid basedsupramolecular nanomedicine that could be co-activated by multiple stimuli in tumor tissue to trigger cascade catalytic reactions

As a typical lightweight material, carbon materials have great application prospects in fabricating microwave absorbers. In this work, the Fe3C@Fe/C composites with porous microstructure are obtained by a simple and environmentally friendly method with wasted cornstalks as raw materials. The reflection loss of absorbing composites reaches the minimum value which is less than −50 dB when the thickness is 1.13 mm, while widest effective absorbing bandwidth reaches 5.1 GHz when thickness is 1.50 mm. The stalk-made nanocomposites’ excellent absorbing ability is mainly credit to excellent impedance matching and attenuation characteristics of composites, which is further credit to a synergistic influence of the dielectric loss from the multiple interfaces in porous microstructure and magnetic loss from iron nanoparticles. A low-cost method to obtain microwave absorption materials and realize high-value utilization of agricultural waste to reduce pollution caused by burning cornstalks is put forward.

The development of materials with photocatalytic activity in a visible-light region is of great significance for solar energy utilization and clean energy production. In this paper, we designed a GaAs quantum dot (QD)/TiO2 heterojunction with high performance of visible-light photocatalytic hydrogen evolution based on first-principle calculations. The results show that six designed GaAs QDs are thermally stable at 300 K, and they have proper visible-light absorption except GaAs-12 QD. GaAs-20 QD maintains good stability at 350 K. Further investigations indicate that the interface Ga atoms in the GaAs-20/TiO2 heterojunction are active sites for photocatalytic reaction, and the type-II band alignment of the GaAs-20/TiO2 heterojunction can lead to effective separation of photoexcited electron–hole pairs. Moreover, the energy barrier of hydrogen production in GaAs-20/TiO2 is about 56% lower than that in TiO2, and oxygen vacancy in GaAs-20/TiO2 heterojunction could transform the hydrogen production from endothermic reaction into exothermic reaction, which has an obvious promotion effect on photocatalytic hydrogen evolution. In short, our calculations indicate that the GaAs-20/TiO2 heterojunction has high performance in visible-light photocatalytic hydrogen evolution. The GaAs quantum dot (QD)/TiO2 heterojunction with high performance of visible-light photocatalytic hydrogen evolution was designed based on first-principle calculations. The oxygen vacancy in the GaAs-20/TiO2 heterojunction could transform the hydrogen production from endothermic reaction into exothermic reaction.

Metamaterials with metal conductive phase always suffer from their high negative permittivity (epsilon-negative), the mechanism of negative permittivity is still need to be explored. Herein, we prepared iron (Fe)/epoxy composites by mechanical mixing and pressure forming. With the increase of Fe content, the conductive behavior changed from hopping conduction to metal-like conduction. The permittivity became negative when the iron content exceeded the percolation threshold (0.425), the negative permittivity was caused by the plasma oscillation of delocalized electrons in the iron conductive network. Besides, when the iron content was 50, 55, 60 or 70 vol%, the permittivity changed from negative to positive at certain frequency points, which is called epsilon-near-zero property. We used the Debye-Drude model to analyze this special dielectric behavior, and the fitting results are in good agreement with the experimental results. A transformation from capacitive to inductive was founded by using equivalent circuit analysis model, this suggests that the occurrence of negative permittivity is accompanied by the appearance of inductance and the negative permittivity behavior is inductance. The epsilon-near-zero and epsilon-negative property could be adjusted effectively by simply changing iron content. Our work provides an understanding guidance on the mechanism of epsilon-negative and epsilon-near-zero property and offers an efficient way to regulate the dielectric property.

With the rapid development of metamaterials, percolating composites with negative dielectric constant have become a research hotspot in recent years. In this work, Ti3AlC2-polyimide percolating composites were prepared by mechanical mixing and pressure forming, and their microstructure and dielectric properties were investigated in detail. By controlling the Ti3AlC2 content, an electrical percolation phenomenon appears with the formation of Ti3AlC2 conductive network. The conductive mechanism changed from hoping conduction to metal-like conduction. Above the percolation threshold (68%–72%), real permittivity changes from positive to negative and mainly due to the damped motion of the free electrons. The Drude model analysis showed that the negative permittivity resulted from the plasma-like oscillation of free electrons. The equivalent circuit analysis indicated that the generation of negative permittivity was closely related to the appearance of inductance. This work provided a simple and effective strategy for regulating negative permittivity and promoted its application.

Carbon-based composites have gained extensive attention as microwave absorbing materials due to the lighter weight compared with other materials. In this work, Co/C nanocomposites with Co nanoparticles uniformly distributed in amorphous carbon sheets are prepared by a freezing dry and carbothermic reduction process. Hierarchical porous microstructures (micropores, mesopores, macropores) are achieved by ice template and huge amounts of gas during carbothermal reduction. Excellent absorption performance is achieved at a very low Co/C content (10% and 15%), which is a great success to design ultralight absorbers. At 10% content level, the effective absorption bandwidth is 5.0 GHz with a thin thickness of 1.8 mm, while the absorption bandwidth is 4.7 GHz with a thin thickness of 1.5 mm at 15% Co/C content level. The excellent absorption performance is attributed to excellent impedance matching resulting from synergy of cobalt and carbon and strong interfacial polarization induced by the hierarchical porous microstructures. This work provides a new pathway of designing ultralight absorbers with the advantage of thin thickness and wide bandwidth. Excellent absorption performance is achieved at only 10% Co/C content level, a success to design ultralight absorbers.

Two-dimensional (2D) materials with a surface hierarchy and heterostructure offer infusive opportunities as high-rate electrodes in energy-storage/-conversion technologies due to their largely exposed active sites and shortened diffusion distance that are beneficial for mass/ion transfer. However, these 2D materials are still difficult to be synthesized due to the lack of a rational approach to design a surficial hierarchical heterostructure on 2D nanostructures. Herein, we explore a top-down strategy for the simple synthesis of surface-engineered TiO2 nanosheets with a large surface area, abundant open pores and TiO2-B/anatase heterointerfaces under mild conditions. Benefiting from the structural features of high electrode/electrolyte contact areas and short Li+/electron transport pathways, the surface-engineered TiO2 nanosheet material, tested as the lithium-storage electrode, show fast lithium uptake/release properties. A specific capacity of 149 mA h g−1 is observed at a high rate of 10 A g−1, and long-term operating stability is shown by delivering 110 mA h g−1 at 6 A g−1 upon 1000 cycles. Furthermore, the as-assembled lithium-ion capacitor using surface-engineered TiO2 nanosheets exhibits high energy density at high rates and possesses very stable cycling performance (∼80% capacity retention at 4 A g−1 after 10 000 cycles). This study may pave a new way for designing novel 2D nanoarchitectures with a surface hierarchical structure for high-power energy-storage applications.

The clinical translation of chemodynamic therapy has been highly obstructed by the insufficient intracellular H2O2 level in diseased tissues. Herein, we developed a supramolecular nanozyme through a facile one-step cooperative coordination self-assembly of an amphipathic amino acid and glucose oxidase (GOx) in the presence of Fe2+. The results demonstrated that the supramolecular nanozyme possessed cascade enzymatic activity (i.e., GOx and peroxidase), which could amplify the killing efficacy of hydroxyl radicals (˙OH) via self-supplying H2O2, finally achieving synergistic starvation–chemodynamic cancer therapy in vitro. Additionally, this cascade nanozyme also exhibited highly effective antibacterial activity on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) without the need for additional H2O2. This work provided a promising strategy for the design and development of nanozymes for future biomedical applications.

A breakthrough in enhancing visible-light photocatalysis of wide-bandgap semiconductors such as prototypical titania (TiO

Hollow multishelled structures (HoMSs) enable material intriguing properties and diverse applications. However, constructing all-polymer HoMSs (p-HoMSs) remains a great challenge. Here, we first de...

Hydrogen production through photoelectrochemical (PEC) water splitting on photocatalyst is a green and clean method. In this study, we use density functional theory (DFT) calculations to find that the cage-like InP quantum dots (QDs) sensitized TiO2 is an effective photocatalyst for PEC water splitting under visible-light. A 16-ps first-principle molecular dynamics (FPMD) simulation results indicate that the cage-like InP-12, InP-16, InP-20, InP-24, InP-28, and InP-36 QDs are stable at room temperature (300 K). Furthermore, the calculated energy gaps of InP-16, InP-20, InP-24, InP-28, and InP-36 QDs are about 2.0 eV, which are suitable for visible-light absorption. Stable InP-20/TiO2 heterojunction structure was also obtained by FPMD simulation, and the electronic structure calculation result indicates that the InP-20/TiO2 heterojunction has a favorable type-II band aligment, which could prevent the recombination of photoexcited carriers. Finally, the possible reaction pathways of hydrogen production on InP-20/TiO2 heterojunction were investigated. It is found that energy barrier of hydrogen production of the InP-20/TiO2 is 2.56 eV lower than pure TiO2. Our calculations imply that InP QDs sensitized anatase TiO2 is an effective photocatalyst for visible-light PEC water splitting.

One-dimensional wires are the most common building blocks in metamaterials. In this study, zero-dimensional nanoparticles connected by tunneling networks were used to construct metamaterials, thus providing a more flexible alternative for designing the geometrical configuration of metamaterials, particularly in nanodevices. The composites with nickel nanoparticles@MnO were prepared by a bio-gel derived strategy. Nickel nanoparticles were not connected geometrically, but the conductive network had been already formed, which was a tunneling-dominated percolative phenomenon demonstrated by the first-principles calculation. Negative permittivity was achieved in the composites, as the low-frequency plasmonic state could be generated in the tunneling nickel-networks. At the same time, negative susceptibility was observed due to the diamagnetism of the tunneling current loops. Electromagnetic simulations indicate that the composites have the potential for electromagnetic shielding (only 0.25 mm in thickness). It is believed that this study not only fills up the research gap in the influence of the tunneling effect on negative electromagnetic parameters but also opens up another way of preparing metamaterials by using zero-dimensional nanoparticles instead of one-dimensional wires.

Aptamers, referring to single-stranded DNA or RNA molecules can specifically recognize and bind to their targets. Based on their excellent specificity, sensitivity, high affinity, and simplicity of modification, aptamers offer great potential for pathogen detection and biomolecular screening. This article reviews aptamer screening technologies and aptamer application technologies, including gold-nanoparticle lateral flow assays, fluorescence assays, electrochemical assays, colorimetric assays, and surface-enhanced Raman assays, in the detection of foodborne pathogens. Although notable progress (more rapid, sensitive, and accurate) has been achieved in the field, challenges and drawbacks in their applications still remain to be overcome.

Ionic hydrogel-based resistance strain sensors (IRS-sensors) powered by direct current (dc) enable various wearable applications. However, the unclear signal transmission mechanism causes significant difficulty to solve the problem of their weak detection ability for subtle strain changes. Here, we have conducted a combined theoretical and experimental study to demonstrate that the signal transmission of dc-powered IRS-sensors is determined by the electrochemical redox process. The slow H+ reduction rate and chemical component change within the hydrogel account for their low sensitivity and signal-to-noise ratio (SNR). To address such a challenge, we have introduced Cu2+ into the hydrogels to enhance the cathodic reduction rate and the chemical stability of the IRS-sensors. The as-prepared IRS-sensors show high sensitivity, ultrahigh SNR, and excellent sensing reliability. Besides the inherent ultrawide sensing range (>1500%), the IRS-sensor can also provide recognizable electrical responses to the incredibly small strain (0.005%), which is 2 orders of magnitude lower than previous ones. They demonstrate precise and reliable monitoring for full-range human activities. This new strategy can be easily extended to other ionic hydrogels and electrodes as well as self-driving electrochemical electrodes for the fabrication of various high-performance self-powered IRS-sensors.

Vibrio infectious diseases spreading every day through aquatic food may be a life-threatening problem for people with weak immune and growing menace to society. It was estimated that the cost of foodborne diseases was approximately $5–6 billion per year. Traditional methods for Vibrio spp. sensing showed high accuracy but very low detection limit. Immunoassays and nucleic acid-based assays could provide results within 24 h, while they are expensive, labor-cost and tedious. Hence, it was urgently needed for the development of cost-effective, rapid and reliable alternative methods for real-time biosensing of Vibrio spp. Several biosensors have been established for the screening of Vibrio spp. in seafood and water. In this review, we have updated the advances in biosensing assays for screening of Vibrio spp., such as electrochemical, optical and novel nano-scaled aptamers based biosensors. Meanwhile, attentions have been paid on the principal concepts, applications, and examples that have been achieved up to determine Vibrio spp.

A facile way to simultaneously induce the formation and enhance the stability of graphene oxide liquid crystals (GO LCs) is reported. Sodium alginate (SA) with both inductive effect and stabilization effect was added into GO suspensions to prepare LCs at low concentration that could survive harsh conditions. Most importantly, different concentration zones of SA brought significantly different LCs degree and stability, which possessed distinct charge properties, rheological behaviors and chain morphology. Adding 0.5% SA located in entangled semi-dilute regime could induce the isotropic-nematic transition of GO at low concentration (

A simple and visual aptasensor has been established for the detection of the common seafood-borne pathogen Vibrio parahaemolyticus (V. parahaemolyticus). In this study, two specific aptamers were applied for V. parahaemolyticus enrichment. In the presence of the target, a “sandwich-type” complex of a-aptamer/target/c-aptamer/MBs was formed through specific recognition of the aptamer and corresponding target. Then, the cozmplex was used as template for strand displacement amplification (SDA), which combined with a lateral flow biosensor (SDA/LFB) to detect V. parahaemolyticus from pure cultures and spiked oyster homogenates. The entire process, including enrichment processing (20 min), SDA (30 min) and results (∼5 min), could be completed within 55 min. Under optimal conditions, the LOD of V. parahaemolyticus was as low as 10 cfu/ml by the naked eye and 5.6 cfu/ml by calculation for a pure culture. No cross-reactivity with other Vibrio species and non-Vibrio species was observed. Without the need for DNA extraction, the reduced handling and simpler equipment requirement render this assay suitable for the rapid screening of V. parahaemolyticus in clinical, food, and environmental samples.

Enterprises will be more flexible to organize production, more agile to meet individual customer custom in the age of Industry 4.0, which requires that the manufacturing enterprise training must comply with the trend and reform soon. Through investigating different types of manufacturing enterprises and analyzing typical case, manufacturing enterprises should analyze the main problems existing in the training system based on Industry 4.0. The research shows that the orientation of staff training will focus on intellectualization, the professional ability of employees will be transferred from a single structure to a compound structure structural transformation, staff training will be promoted from single ability to compound ability, the improvement of employees’ innovation ability will be the core of training the heart demands and lifelong education will be the core of the enterprise staff training system. The paper puts forward countermeasures and suggestions on employee training from training needs analysis, training plan, training courses, training teachers, training organization and implementation, training effect evaluation, training support and training achievement transformation.

In this biosensor system, metabolite residues were derived by using a previous B-CBA synthesis method to label a biotin moiety for enrichment by streptavidin coated magnetic beads. Antibodies specific for derivatives were conjugated with carboxyl-modified barcode DNAs which were used as templates for strand displacement amplification (SDA). The assay can detect trace levels of 7.20 ppt of SEM, 11.58 ppt of AHD, 7.24 ppt of AOZ and 2.31 ppt of AMOZ, respectively.

Enterprises will be more flexible to organize production, more agile to meet individual customer custom in the age of Industry 4.0, which requires the manufacturing enterprise training must comply with the trend and reform soon. Through investigating different types of manufacturing enterprises, and analyzing typical case, manufacturing enterprises should analyze the main problems existing in the training system based on Industry 4.0. The research shows that the orientation of staff training will focus on Intellectualization, the professional ability of employees will be transferred from a single structure to a compound structure structural transformation, staff training will be promoted from single ability to compound ability, the improvement of employees’ innovation ability will be the core of training the heart demands, lifelong education will be the core of the enterprise staff training system. The paper puts forward countermeasures and suggestions on employee training from training needs analysis, training plan, training courses, training teachers, training organization and implementation, training effect evaluation, training support, training achievement transformation.

Dietary consumption of functional foods enriched in anthocyanins benefit for human health by protection against far-ranging human diseases. Delphinidin-derived anthocyanins (valuable as blue pigments and antioxidants) are accumulated specifically in the fruits of Lycium ruthenicum but not in the fruits of Lycium barbarum, suggesting the differences of anthocyanin biosynthesis between the two species. In this study, anthocyanin profiling confirmed that anthocyanins were increasingly accumulated during fruit ripening in L. ruthenicum, and sharply increased at full expanded mature fruit, while no anthocyanin were detected at any stage of L. barbarum fruit development. Several genes involved in anthocyanin biosynthesis were characterized in L. ruthenicum and L. barbarum fruits. Expression profiling of these genes during fruit development showed a significant positive correlation between transcript abundance and anthocyanin accumulation in L. ruthenicum fruit. Meanwhile, transcripts in L. barbarum fruit were either undetectable or were downregulated during fruit ripening, before increasing slightly in the final stages of maturation. In addition, the ratio of LrF3'5H/LrF3'H transcription showed a gradual increase before 6 days after breaker (DAB) and a sharp enhancement at 10 DAB. Our results suggest that the expression patterns of both regulatory and structural genes and the transcriptional ratio of branch-node structural genes F3'5'H/F3'H may determine the phenotypic difference in anthocyanin biosynthesis between L. ruthenicum and L. barbarum fruits.

Plant cell walls are composed of cellulose microfibrils embedded in a cross-linked-net of matrix polysaccharides and co-polymerized with lignin. The study presented the genotypic variations of cell wall composition, biohydrogen production, and lignocellulose degradation ratio in a collection of 102 Miscanthus sinensis (M. Sinensis, hereafter) accessions collected from a wide geographical range in China. Significant variations were observed for the determined traits, cellulose content, hemicellulose content, cellulose and hemicellulose degradation efficiency, and biohydrogen yield. The cellulose, hemicellulose, and lignin contents ranged from 30.20-44.25, 28.97-42.65, and 6.96-20.75%, respectively. The degradation ratio of cellulose and hemicellulose varied from 2.08% to 37.87% and from 14.71% to 52.50%, respectively. The feedstock was fermented to produce biohydrogen, and the production varied from 14.59 to 40.66ml per gram of Miscanthus biomass. The expression profile of three cellulose synthase (MsCesA) genes was initially established to indicate the genotypic difference among the M. sinensis accessions. Pearson's correlations were conducted to reveal the perplexing relationship between the tested traits, biohydrogen yield, cell wall composition and their degradation efficiency. In addition, the relationship pattern, between the test traits and the geographic factors corresponding with the original place, was investigated. The result showed that the significant variation among the M. sinensis genotypes is the result of natural selection in different environments of their original habitats. Improvement in cell wall composition and structure and enhancement of lignocellulose degradation ratio could significantly increase sustainable bioenergy production.

Keywords: Sci-tech enterprise;Independent innovation;Influencing factors Abstract: By investigative research and field surveys on sci-tech enterprises in Ningbo, this paper focuses on analysis of restricted factors of independent innovations of sci-tech enterprises based on case examples. Method of a constitutive SEM (structural equation model) is applied, examining effects of these factors. In the end, suggestions on validity of independent innovation of domestic sci-tech enterprises are given.

Artemisinin isolated from the aerial parts of Artemisia annua L. is a promising and potent antimalarial drug which has a remarkable activity against chloroquine-resistant and chloroquine-sensitive strains of Plasmodium falciparum, and is useful in treatment of cerebral malaria. Because the low content (0.01-1 %) of artemisinin in A. annua is a limitation to the commercial production of the drug, many research groups have been focusing their researches on enhancing the production of artemisinin in tissue culture or in the whole plant of A. annua. This review mainly focuses on the progresses made in the production of artemisinin from A. annua by biotechnological strategies including in vitro tissue culture, metabolic regulation of artemisinin biosynthesis, genetic engineering, and bioreactor technology.

An in situ regeneration system for rice calli comprised of a callus growth stage and two regeneration stages was developed. After the first stage of regeneration, the medium is changed and the calli are immobilized in polyurethane foam supports, in each of which 3–5 regenerated plantlets develop from the immobilized calli during the second stage. While no significant change in callus size was observed during the first stage of regeneration, in the second stage callus enlargement and shoot regeneration predominated. In the light of these findings, calli were immobilized in the second stage after medium exchange. The use of 10-mm support cubes with an average pore size of 3.6 mm resulted in the most efficient immobilization and in situ regeneration. Medium exchange after 15 d gave the largest number of support cubes with shoots. When rice calli were cultivated in support cubes placed in 60 ml second-stage medium in a 500-ml flask, the immobilization ratio was 83%, and 82% of the support cubes contained 3–5 regenerated plantlets after 25 d. The shoot lengths of the regenerated plantlets obtained from the in situ regeneration culture were longer than those from a suspension culture. When support cubes with 3–5 regenerated plantlets were transferred from the flask to 1 4 MS solid medium supplemented with 10 g/l sorbitol and 5 g/l sucrose, the regenerated plantlets developed quickly into plants with a length above 10 cm after 10 d.