Two-dimensional atomic crystal materials have attracted a wide range of research interests due to their excellent optical, electrical, mechanical, magnetic and thermal properties. In particular, two-dimensional atomic crystal materials can produce a large resistance change steadily under the micro-deformation. They can bear a greater elastic strain than the corresponding bulk material without causing breaking of the structures. The characteristic makes them have an important potential application for the high-performance strain sensors. Besides, they are expected to fabricate flexible integrated electronic devices which are appropriate for all kinds of working condition. At present, the studies related to two-dimensional atomic crystal materials have mainly concentrated on graphene, molybdenum disulfide and black phosphorus. In this review, we firstly introduce the basic properties of the three typical two-dimensional materials and explain theoretically their strain sensing characteristics based on their physical property and microstructure. Secondly, some important methods for preparing the 2D materials, such as micromechanical exfoliation, solution exfoliation and chemical vapor deposition (CVD), are summarized. Thirdly, the applications of the 2D materials in the strain sensing fields, such as health monitoring, wearable devices and electronic skin, are introduced in detailed. Finally, we present the future research direction and application prospect of two-dimensional materials.
Contents
1 Introduction
2 Basic physical properties of 2D materials
2.1 Graphene
2.2 MoS₂
2.3 Phosphorene
2.4 Theory explanation for strain sensing
3 Synthesis of 2D materials
3.1 Mechanical exfoliation methods
3.2 Solution methods
3.3 Chemical vapor deposition
4 Application in strain sensing
4.1 Graphene
4.2 MoS₂
4.3 Phosphorene
5 Conclusion

The development in computer science has brought a great impetus to the advance of human society. However, as the manufacturing process goes to the limit, there is an urgent need to find a new computing system to meet the growing demand for computing. DNA computing has attracted great attention due to its advantages in huge information storage, large scale parallelism and very low energy consumption. Many different models have been established ever since the experimental implementation of solving a 6 vertices Hamilton pathway problem by Adleman in 1994. In this paper, a brief introduction to the basic principles and experimental operations in DNA computing is first given, and the theories in this field are illustrated, including the DNA sequence design, complexity of different models and the proof of universal computing power. Moreover, the models regarded as breakthroughs in the field are summarized. All the models are classified based on the specific means in conducting the experiment, and reviewed according to different classes. More detailed descriptions are further set forth for a classical model in each class. At last, a prospect is made based on our work in this area.
Contents
1 Introduction
2 Principles and experimental operations of DNA computing
2.1 Principles of DNA computing
2.2 Experimental operations of DNA computing
3 Advances in DNA computing related theories
3.1 Principles of DNA sequence design
3.2 Universal computing power of DNA
4 Five kinds of DNA computing models
4.1 Parallel overlap assembly model
4.2 Sticker model
4.3 Splicing model
4.4 DNA Tile self-assembly model
4.5 Biochemistry signal based logic circuits model
5 Conclusion and outlook

Organic semiconductors, as the key component of organic feld-effect transistors (OFETs), determine the performance and stability of OFET devices directly. However, the overall development of n-type and ambipolar organic semiconductors still lags behind their p-type counterparts in terms of mobility, ambient stability, and so on. Thus, the design and synthesis of n-type and ambipolar organic semiconductors have become the focus of academic research for high-performance OFETs. In this review, high performance n-type and ambipolar small organic semiconductors are highlighted and their structure-property relationship is analyzed, which is aimed to provide some meaningful guidelines for designing high-performance n-type and ambipolar organic semiconductors.
Contents
1 Introduction
2 n-type small organic semiconductors
2.1 NDI and PDI-based small organic semiconductors
2.2 DPP-based small organic semiconductors
2.3 Small organic semiconductors containing thiophene or thiazole
2.4 Acene-based small organic semiconductors
3 Ambipolar small organic semiconductors
4 The principles for the design of high performance n-type and ambipolar small molecules
4.1 Molecular structure
4.2 HOMO and LUMO energy levels
4.3 Molecular arrangement
4.4 The introduction of substituent group
4.5 Other factors
5 Conclusion

Allene is a kind of compounds containing 1, 2-propadiene structure. In recent years, allenes and their derivatives have attracted many researchers' interest due to the unique nature. A variety of unsaturated compounds can react with allenes or their derivatives in a variety of cycloaddition reactions to prepare indole, pyridine, furan and other cyclic compounds. The recent progress in the cycloaddition reactions of allenic compounds catalyzed by different catalysts is summarized, including [4+2], [3+2], [2+2], [1+2+2], [2+2+2], [4+3], and [4+2+2] cycloaddition reactions, and the future development of allenic compounds is prospected.
Contents
1 Introduction
2[4+2] cycloaddition of allenes
2.1[4+2] cycloadditions of allenes with unsaturated ketones
2.2[4+2] cycloadditions of allenes with butadienes
2.3[4+2] cycloadditions of allenes with alkynes
2.4[4+2] cycloadditions of allenes with alkenes
2.5[4+2] cycloadditions of allenes with hydroxylamines
3[3+2] cycloaddition of allenes
3.1[3+2] cycloadditions of allenes with imines
3.2[3+2] cycloadditions of allenes with ketones
3.3[3+2] cycloadditions of allenes with alcohols
3.4[3+2] cycloadditions of allenes with butadienes
3.5[3+2] cycloadditions of allenes with aziridines
3.6[3+2] cycloadditions of allenes with alkenes
4[2+2] cycloaddition of allenes
4.1[2+2] cycloadditions of allenes with allenes
4.2[2+2] cycloadditions of allenes with alkenes
5[1+2+2] cycloaddition of allenes
6[2+2+2] cycloaddition of allenes
6.1[2+2+2] cycloadditions of allenes with alkynyl and cyanogens
6.2[2+2+2] cycloadditions of allenes with alkenyls
6.3[2+2+2] cycloadditions of allenes with isocyanates
6.4[2+2+2] cycloadditions of allenes with triazines
7[4+3] cycloaddition of allenes
8[4+2+2] cycloaddition of allenes
9 Conclusion

o-Aminobenzamide compounds are a class of molecules containing bifunctional groups. The amide bonds in their molecules are not only the basic constituent units of peptides and proteins, but also the structural units which are indispensable to regulate the life activity. The amide and amino groups in the molecules have good reactivities, so most of the compounds have biological and pharmacological activities in medicine, pesticides, organic synthesis and other fields with a wide range of applications. In this paper, the progress of the synthesis of o-aminobenzamide compounds is reviewed. The main approaches to o-aminobenzamide compounds are introduced with o-aminobenzoic acids, o-aminobenzoyl halides, o-aminobenzoates, isatoic anhydrides, o-halobenzoic acid and their derivatives, quinazolinones, benzamides, benzynes, indazole salts, N-substituted anilines as raw materials, respectively, and the advantages and disadvantages of each method are analyzed. Finally, the synthesis of these compounds is summarized and the prospect of their development is prospected.
Contents
1 Introduction
2 Synthesis of o-aminobenzamide compounds
2.1 From o-aminobenzoic acids
2.2 From o-aminobenzoyl halides
2.3 From o-aminobenzoates
2.4 From isatoic anhydrides
2.5 From o-halobenzoic acids and their derivatives
2.6 From quinazolinones
2.7 From benzamides
2.8 From benzynes
2.9 From indazole salts
2.10 From N-substituted anilines
3 Conclusion

Thermoelectric materials are one kind of functional materials which can directly realize the interconversion of thermal energy and electrical energy and have a promising application prospect in the fields of thermoelectric refrigeration and power generation. Currently, the low conversion efficiency limits the applications of thermoelectric materials. How to improve and optimize the thermoelectric figure of merit becomes very important in the current research. Cu₂Se-based phonon liquid thermoelectric materials are one new type of high performance thermoelectric materials with extremely low thermal conductivity by their special crystal structure, the researches of which have greatly promoted the development of thermoelectric materials. Cu₂Se undergoes a structural phase transition at high temperature, where the Cu atoms become the freely migrating liquid-like Cu ions. This special liquid-like behavior of Cu ions leads to the lower lattice thermal conductivity of materials by strong phonon scattering. In this paper, the Cu₂Se-based phonon liquid thermoelectric materials are focused on. The basic properties, special crystal structure and applications of Cu₂Se are summarized. The research achievements, preparation methods as well as the performance optimization means of Cu₂Se-based thermoelectric materials are introduced elaborately. Finally, the future research aspects and new ideas for improving the performance of phonon liquid thermoelectric materials are also analyzed and prospected.
Contents
1 Introduction
2 Properties of Cu₂Se and Cu₂Se-based phonon liquid thermoelectric materials
2.1 Properties of Cu₂Se
2.2 The concept of Cu₂Se-based phonon liquid thermoelectric materials
3 Development of Cu₂Se-based phonon liquid thermoelectric materials
3.1 Preparation methods of Cu₂Se-based phonon liquid thermoelectric materials
3.2 Performance optimization means of Cu₂Se-based phonon liquid thermoelectric materials
4 Conclusion

Magnetic Fe₃O₄ nanomaterials, possessing unique physicochemical properties such as quantum size effect, surface interfacial effect, electrical properties and magnetic properties, have attracted intensive research interest and shown potential applications in many fields (such as enviroment, energy) during the past years. In this review, some methods for preparing Fe₃O₄ in recent years are summarized, including precipitation method, thermal decomposition method, hydrothermal method, microemulsion method and sol-gel method. The advantages and disadvantages of various preparation methods are compared. As for the application of Fe₃O₄ nanomaterials, the article firstly summarizes their application as adsorbent for removal of heavy metal ions and organic pollutants from wastewater. The application of Fe₃O₄ nanomaterials in catalysis, including Fe₃O₄ nanomaterials acting active species and acting as supports for active species (such as noble metal nanoparticles, transition metal oxide, as well as metallic organic compounds) is also overviewed in detail. While applied in environment treatment and chemical catalysis, the largest advantage of Fe₃O₄ nanomaterials is that they can be easily separated by magnetic separation. Furthermore the application of Fe₃O₄ nanomaterials in energy storage (such as lithium-ion batteries and super capacitors) and biomedicine (tumor diagnosis and treatment, immobilized enzyme and immunoassay) are also discussed in brief. Finally, some problems in the preparation of Fe₃O₄ nanomaterials and their future research directions are outlined.
Contents
1 Introduction
2 Synthesis strategies of Fe₃O₄ nanomaterials
2.1 Precipitation method
2.2 Hydrothermal method
2.3 Thermal decomposition
2.4 Sol-gel method
2.5 Microemulsion method
2.6 Other methods
3 Applications of Fe₃O₄ nanomaterials
3.1 Environmental treatment
3.2 Chemical catalysis
3.3 Energy storage
3.4 Biomedical
3.5 Other applications
4 Conclusion

Membrane-based separation technologies, as one of the most effective and efficient technologies, have been widely used in many fields including wastewater treatment, seawater desalination, electronic, chemical and pharmaceutical industries, etc. due to their inherent advantages such as energy-saving and cost-effective features. Membrane fouling, however, especially the irreversible biofouling, has strong negative effects on the operational sustainability and the cost-efficiency of membrane process, thus hampering the application of membrane technology. In this review, the formation process and features of membrane biofouling are summerized, and then recent advances of antibacterial membranes development are reviewed. Three strategies including anti-adhesion strategy, active antibacterial strategy and programmed combination antibacterial strategy are highlighted for mitigating the membrane biofouling. In particular, the preparation method, antibacterial mechanism as well as practical problems of these three strategies are comprehensively discussed and analyzed. Finally, the future prospect and new insights are proposed to develop antibacterial membrane for future work.
Contents
1 Introduction
2 The formation process, characteristics and harmfulness of microbial fouling
3 The construction strategies of filtration membranes with antibacterial performance
3.1 The construction strategies of anti-adhesive filtration membranes with biofouling resistance
3.2 The construction strategies of active anti-bacterial filtration membranes with biofouling resistance
3.3 The construction strategies of programmed combination antibacterial filtration membranes with biofouling resistance
4 Conclusion and outlook

The pollution of antimony (Sb) species in natural waters has drawn more and more attention due to their high cumulative toxicity and carcinogenicity. In recent years, it is highly in demand to develop efficient and economical technologies to address the increasing pollution of antimony all over the world. Iron-based composite materials (e.g. Fe⁰, Fe₃O₄, and FeMnO_x) have become a research hotspot in the field of antimony treatment based on their various advantages, including high adsorption capacity, easy separation and recycling, safety and environmental friendliness, etc. This article summarizes the preparation, modification and application of iron-based composite materials based on zero-valent iron, ferric oxide and iron bimetallic oxide for the removal of Sb(Ⅲ) and Sb(Ⅴ) in water. The adsorption mechanisms of Sb(Ⅲ) and Sb(Ⅴ) by different iron-based composite materials are emphatically discussed. The effects of temperature, pH and co-existing ions on the Sb adsorption of iron-based composite materials are also investigated, to find the optimal adsorption condition. Finally, some primary issues about antimony removal are proposed and the outlook of key developing trends on the antimony removal by iron-based composite materials are presented.
Contents
1 Introduction
2 The removal of Sb by zero-valent iron based composite materials
2.1 The physical modification of nano-Fe⁰
2.2 The loading modification of nano-Fe⁰
2.3 The stabilization modification of nano-Fe⁰
3 The removal of Sb by ferric oxide based composite materials
3.1 The composite materials based on magnetic Fe₃O₄
3.2 The composite materials based on ferric oxide hydrate
4 The removal of Sb by iron bimetallic oxide based composite materials
4.1 Iron and manganese oxides
4.2 Other iron bimetallic oxides
5 Conclusion

Nickel-cobalt bimetallic sulfide (NiCo₂S₄) has a typical AB₂O₄ spinel structure. The conductivity of NiCo₂S₄ is two orders of magnitude higher than that of NiCo₂O₄, and its conductivity is 1.25×10⁶ S·m^-1at room temperature. In addition, NiCo₂S₄ provides a more efficient redox reaction than the corresponding one-component sulfide, and has great potential for its unique nanostructures and electrochemical properties. In this paper, the preparation of NiCo₂S₄ nanostructures and its application in electrochemical energy conversion and storage are reviewed. The morphology, physicochemical properties and synthesis methods of NiCo₂S₄ nano materials are introduced. Pretreatment conditions, preparation methods and growth matrix will have an effect on the morphology and properties of NiCo₂S₄ nanostructures. NiCo₂S₄ with different nanostructures (such as nanoneedles, nanowires, nanorods, nanotubes, nanocapses, nanosheets, nanostructures and hierarchical structures) can be prepared by a variety of methods (such as hydrothermal method and solvent heat method, low temperature synthesis method, anion exchange method, steam conversion method, electrodeposition method, coprecipitation method and self-assembly, etc.). Among them, hydrothermal and solvothermal are the most commonly used methods because they have the characteristics of low cost, easy handling and suitable for large scale manufacturing. The application status of NiCo₂S₄ nano materials in electrocatalysis, supercapacitors and lithium ion batteries is summarized. This paper analyzes and compares the preparation process, method and application of different nanostructures, hoping to promote the development of NiCo₂S₄ nano materials in the field of electrochemical energy conversion and storage. The development and application direction of NiCo₂S₄ nano materials are proposed.
Contents
1 Introduction
2 Preparation of NiCo₂S₄ nanostructures
3 Electrochemical application of NiCo₂S₄ nanostructures
3.1 Electrochemical catalysis:bifunctional electrocatalysts
3.2 Pseudocapacitive properties:supercapacitors
3.3 New electrode materials:anode material for Li-ion batteries
4 Conclusion