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A van der Waals (vdW) heterostructure is formed by combining multiple materials through vdW bonds. It can combine the advantages of electronic, optical, thermal, and magnetic properties of different 2D materials and has the potential to develop into the next generation of high‐performance functional devices. Herein, the current research advances of vdW heterostructures are reviewed. First, current fabrication methods and physical structures of vdW heterostructures are summarized. The 2D/nD (n = 0,1,2,3) mixed‐dimensional heterostructures are discussed in detail. Second, a new type of vdW heterostructure is introduced based on two‐dimensional electron gas with a nanoscale junction interface. Finally, the application prospects of vdW heterostructures in photoelectric and memory devices are further outlined by combing new applications in the neural networks. This review shows that vdW heterostructures have great advantages in high integration, energy harvesting, and logical operations, and it provides directions and suggestions for the future research and application of environmentally friendly, high‐performance, and smart functional devices. [ABSTRACT FROM AUTHOR]

With the development of Raman spectroscopy and the expansion of its application domains, conventional methods for spectral data analysis have manifested many limitations. Exploring new approaches to facilitate Raman spectroscopy and analysis has become an area of intensifying focus for research. It has been demonstrated that machine learning techniques can more efficiently extract valuable information from spectral data, creating unprecedented opportunities for analytical science. This paper outlines traditional and more recently developed statistical methods that are commonly used in machine learning (ML) and ML‐algorithms for different Raman spectroscopy‐based classification and recognition applications. The methods include Principal Component Analysis, K‐Nearest Neighbor, Random Forest, and Support Vector Machine, as well as neural network‐based deep learning algorithms such as Artificial Neural Networks, Convolutional Neural Networks, etc. The bulk of the review is dedicated to the research advances in machine learning applied to Raman spectroscopy from several fields, including material science, biomedical applications, food science, and others, which reached impressive levels of analytical accuracy. The combination of Raman spectroscopy and machine learning offers unprecedented opportunities to achieve high throughput and fast identification in many of these application fields. The limitations of current studies are also discussed and perspectives on future research are provided. [ABSTRACT FROM AUTHOR]

The electrochemical nitrite reduction reaction provides an alternative approach to offer sustainable ammonia source routes for repairing imbalances in the global nitrogen cycle. In this work, electrocatalysis is combined with enzymatic catalysis to provide an efficient and clean process for recoverable ammonia production. NO2− is reduced to NH3 by electroenzymatic cascade reduction reaction on a bioconjugate, in which 1‐butyl‐3‐methylimidazolium bromide (ILBMB) modified chloroperoxidase (CPO) is fixed on polyethyleneimine (PEI) modified multi‐walled carbon nanotubes (MWCNT) to from bioconjugate (CPO‐ILBMB/MWCNT‐PEI). 15N and 14N isotope labeling reveal that the NH3 species is derived from NO2− reduction. Density functional theory calculations identify that the FeII species in heme center of CPO serve as the key active site for NO2− reduction. The amino groups derived from MWCNT‐PEI not only serve as a bridge to covalently immobilize CPO but also enrich the NO2− ion at electrode/solution interface through electrostatic interactions. The low energy barrier of NO2− reduction and low adsorption free energy of the intermediate result in high Faradaic efficiency (96.4%), NH3 yield (112.7 mg h−1 mgCPO−1), and high selectivity in pH 5.0 solution. The highly efficient electroenzymatic reaction ensurespromising applications in the conversion of NO2− to NH3. [ABSTRACT FROM AUTHOR]

BACKGROUND: Immobilization of enzymes on a nanocarrier can improve their stability, but is often accompanied by a reduction of the initial catalytic activity. Meanwhile, inevitable mass loss during centrifugal separation inhibits reusability. It is still a challenge to design and prepare an immobilized enzyme with both improved catalytic activity and reusability simultaneously. RESULTS: Core–shell magnetic microspheres (Fe3O4@mTiO2) with mesoporous structure were prepared and used to construct an enzymatic nanocomposite (CPO‐Fe3O4@mTiO2). This material can combine magnetic separability, photocatalytic property of TiO2 and enzymatic activity of chloroperoxidase (CPO) when applied in the degradation of aqueous organic contaminants diphenylamine and pesticide residue isoproturon. Moreover, CPO‐Fe3O4@mTiO2 showed good stability and reusability. It can keep 78.0% and 66.8% of its initial activity after incubation at 80 and 90 °C for 1 h, respectively, while free CPO only retained 18.3% and 6.9% of its original activity for the same conditions. After being used for eight cycles, CPO‐Fe3O4@mTiO2 can retain over 82.2% of activity. When applied in the degradation of isoproturon/diphenylamine in artificial wastewater, 60 μmol L−1 isoproturon can be completely degraded in 30 min; 82.2% of diphenylamine can be degraded at a concentration of 10 μmol L−1. Compared with the removal of aqueous contaminants using a porous adsorbent, CPO‐Fe3O4@mTiO2 can be regenerated 'online', obviating complicated procedures for regeneration. CONCLUSIONS: The results indicate that CPO‐Fe3O4@mTiO2 has potential for practical application in the treatment of wastewater. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Immobilization of enzyme on a solid support can improve its stability, however, this is often accompanied by a decrease of the initial catalytic activity. The design and preparation of immobilized enzyme with simultaneous high activity and stability is a challenge. RESULTS: A hierarchically porous metal organic framework H‐MOF(Zr) which was prepared by 'crystal defect' strategy was very stable in aqueous solution and possessed well‐defined, tunable and adjacent hierarchical pores. When using the H‐MOF(Zr) as support for enzyme immobilization, a single array of enzyme in a single mesoporous channel was achieved so as to avoid aggregation of the enzyme. Meanwhile the micropores can be utilized to concentrate substrates, resulting in a decrease in the mass transfer resistance of substrate compared with that in the bulk buffer due to the enzymes and substrates closely embedded on the same support. The prepared immobilized enzyme CPO/HRP@H‐MOF(Zr) was more stable at elevated temparatures, showing 58.2% enhanced activity compared with free enzymes at 70 °C for 1 h incubation. After 12 cycles, 70.7% of activity remained. When the CPO/HRP@H‐MOF(Zr) was applied in the treatment of wastewater containing isoproturon and 2,4‐dichlorophenol, complete degradation was achieved in only 15 min. CONCLUSION: Both high activity and stability under harsh reaction conditions give the CPO/HRP@H‐MOF(Zr) composites potential for practical application in wastewater treatment. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Sulfamethoxazole is found in surface and ground waters because it is usually not metabolized and simply passes through the human body after ingestion. This drug is difficult to degrade by conventional treatments and may cause environmental concerns. RESULTS A rapid and efficient enzymatic degradation of sulfamethoxazole by a heme peroxidase, chloroperoxidase ( CPO), was investigated in this work. The degradation efficiency of sulfamethoxazole reached 98.64% within 20 min at room temperature, atmospheric pressure and environment-friendly reaction conditions with an enzyme concentration of approximately 10−9 mol L−1. High performance liquid chromatography-mass spectrometry analysis was employed to identify the intermediates and final products. Moreover, chemical oxygen demand ( COD) measurements showed that pre-treatment by CPO-H2O2 oxidative degradation followed by existing bioremediation technologies can effectively improve the efficiency and thoroughness of decontaminating this drug from wastewater. The degradation efficiency was enhanced from 76.5% to 84.47%, and the COD removal increased from 29.72% to 51.32%. The eco-toxicity test using a green algae, Chlorella pyrenoidos, showed that the degraded products had lower toxicity than the parent drug. CONCLUSION CPO catalyzed oxidative degradation is a promising alternative for treatment of wastewater containing sulfonamide drugs. This enzymatic method is also suitable for treatment of other sulfonamide antibiotics. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The optically active C3 synthetic blocks are remarkably versatile intermediates for the synthesis of numerous pharmaceuticals and agrochemicals. This work provides a simple and efficient enzymatic synthetic route for the environment-friendly synthesis of C3 chiral building blocks. Chloroperoxidase (CPO)-catalyzed enantioselective halo-hydroxylation and epoxidation of chloropropene and allyl alcohol was employed to prepare C3 chiral building blocks in this work, including ( R)-2,3-dichloro-1-propanol (DCP*), ( R)-2,3-epoxy-1-propanol (GLD*), and ( R)-3-chloro-1-2-propanediol (CPD*). The ee values of the formed C3 chiral building blocks DCP*, CPD*, and glycidol were 98.1, 97.5, and 96.7%, respectively. Moreover, the use of small amount of imidazolium ionic liquid enhanced the yield efficiently due to the increase of solubility of hydrophobic organic substrates in aqueous reaction media, as well as the improvement of affinity and selectivity of CPO to substrate. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:724-729, 2015 [ABSTRACT FROM AUTHOR]

Discovering ways to control magnetic states by light is very attractive for prospective applications of optical–magnetic sensing and recording. Although several studies have demonstrated the light‐induced switching of magnetization, the magnetoresistance effect was seldom thought to depend on light illumination. A light‐induced magnetoresistance sign switching the resulting writable optical memory are described. A practical method is developed to form a p‐n junction at the interface of a p‐type amorphous carbon film and a quasi‐2D electron gas on an SrTiO3 surface. When illuminated, the as‐formed junction exhibits a clear transition from positive to negative magnetoresistance. A change of optical intensity influences the response time, but not the final value of the negative magnetoresistance. It is also found that, after a light pulse, the negative magnetoresistance state tends to persist, indicating a longstanding memory for an optical signal. This points to a new direction for studying light‐induced magnetoresistance switching, which could lead to the development of new memory devices. [ABSTRACT FROM AUTHOR]

The catalytic activities of chloroperoxidase (CPO) including halogenation, oxidation, and peroxidation were investigated in the presence of ammonium salts: tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), tetrapropylammonium bromide (TPABr), tetrabutylammonium bromide (TBABr), and cationic surfactants: dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr). All the mentioned activities were promoted in most cases. The highest modified activity (ABTS peroxidation) was 18.16 times higher in the presence of TMABr than that in pure buffer. The activity enhancement was strongly dependent on the concentration and the hydrophobic chain length of additives, and the structure of substrates. The kinetic parameters showed that the activation was mainly attributed to an increase in k(cat) due probably to a catalytically favorable conformation of CPO induced by the additives. Moreover, a lower K(m) and higher ratio of k(cat)/K(m) (specificity constant) was obtained, indicating that both the affinity and specificity of CPO to substrates were improved in the presence of additives., ((c) 2010 American Institute of Chemical Engineers)

The effects of several polyhydroxy compounds (glucose, fructose, gumsugar, galactose, trehalose, dextran, xylose, PEG200, glycerin) and surfactant (dioctyl sulfosuccinate sodium salt, AOT) on the catalytic activity and thermal stability of chloroperoxidase (CPO) in aqueous systems were investigated at various temperatures. A 25% superactivity was found in AOT solutions at 25 degrees C, and it could be maintained during the 882 h. PEG200 and glycerin were proven to be the most efficient stabilizer for CPO in temperatures ranging from 25 to 60 degrees C. Trehalose is more helpful than other sugars for extended storage of CPO. These results are promising in view of industrial applications of this versatile biological catalyst. The protective mechanism of various additives on CPO was discussed.