Recent progress on fabrication, spectroscopy properties, and device applications in Sn-doped CdS micro-nano structures

One-dimensional semiconductor materials possess excellent photoelectric properties and potential for the construction of integrated nanodevices. Among them, Sn-doped CdS has different micro-nano structures, including nanoribbons,nanowires, comb-like structures, and superlattices, with rich optical microcavity modes, excellent optical properties, and a wide range of application fields. This article reviews the research progress of various micrometer structures of Sn-doped CdS, systematically elaborates the effects of different growth conditions on the preparation of Sn-doped CdS micro-nano structures, as well as the spectral characteristics of these structures and their potential applications in certain fields. With the continuous progress of nanotechnology, it is expected that Sn-doped CdS micro-nano structures will achieve more breakthroughs in the field of optoelectronics and form cross-integration with other fields, jointly promoting scientific, technological, and social development.

Binary molten salt in situ synthesis of sandwich-structure hybrids of hollowβ-Mo2C nanotubes and N-doped carbon nanosheets for hydrogen evolution reaction

Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.

Novel Even Beam Splitters Based on Subwavelength Binary Simple Periodic Rectangular Structure

In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.

Superamphiphobic, light-trapping FeSe2 particles with a micro-nano hierarchical structure obtained by an improved solvothermal method

Wettability and the light-trapping effect of FeSe2 particles with a micro-nano hierarchical structure have been inves- tigated. Particles are synthesized by an improved solvothermal method, wherein hexadecyl trimetbyl ammonium bromide （CTAB） is employed as a surfactant. After modifying the particles with heptadecafluorodecyltrimethoxy-silane （HTMS）, we find that the water contact angle （WCA） of the FeSe2 particles increases by 6.1~ and the water sliding angle （WSA） decreases by 2.5~ respectively, and the diffuse reflectivity decreases 29.4% compared with similar FeSe2 particles synthe- sized by the conventional method. The growth process of the particles is analyzed and a growth scenario is given. Upon altering the PH values of the water, we observe that the superhydrophobic property is maintained quite consistently across a wide PH range of 1-14. Moreover, the modified particles were also found to be superoleophobic. To the best of our knowledge, there is no systematic research on the wettability of FeSe2 particles, so our research provides a reference for other researchers.

Investigation on Surface Plasmon Polaritons and Localized Surface Plasmon Production Mechanism in Micro-Nano Structures

The simulation mechanism of surface plasmon polaritons(SPPs)and localized surface plasmon(LSP)in different structures was studied,including the Au reflection grating(Au grating),Au substrate with dielectric ribbons grating(Au substrate grating),and pure electric conductor(PEC)substrate with Au ribbons grating(Au ribbons grating).And the characteristics of the Smith-Purcell radiation in these structures were presented.Simulation results show that SPPs are excited on the bottom surface of Au substrate grating grooves and LSP is stimulated on the upper surface both of Au ribbons grating grooves and Au grating grooves.Owing to the irreconcilable contradiction between optimizing the grating diffraction radiation efficiency and optimizing the SPPs excitation efficiency in the Au substrate grating,only 40-times enhancement of the radiation intensity was obtained by excited SPPs.However,the LSP enhanced structure overcomes the above problem and gains much better radiation enhancement ability,with about 200-times enhancement obtained in the Au ribbons grating and more than 500-times enhancement obtained in the Au grating.The results presented here provide a way of developing miniature,integratable,tunable,high-power-density radiation sources from visible light to ultraviolet rays at room temperature.

Binary ABR flow control over ATM networks with uncertainty using discrete-time variable structure controller

A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A discrete-time system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality （LMI）. In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate （ACR） and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.

Low-strain binary hexacyanoferrate nanocuboids with concentration-gradient structure towards fast and durable energy storage

The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(y)Mn_(1-y)[Fe(CN)_(6)]·nH_(2)O(KFeMnHCF)nanocuboid,with the concentration-gradient(CG)structure is designed as a high-performance cathode for AKIB.Internal the CG-KFeMnHCF nanocuboids,the manganese content gradually decreases from the interior to the surface and the iron content changes reverse,resulting in the concentration-gradient structure.Both experimental and finite element simulation(FEA)results demonstrate the lower internal stress and better mechanical characteristics of CG structured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes.Meanwhile,the electrochemical testing and theoretical calculation(DFT)results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity,potassium migration and electrochemical kinetics.Taken both advantages from the well-designed architecture and optimized crystal structure,the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aqueous potassium ion system.In particular,the CG-KFe_(0.31)Mn_(0.69)HCF achieves the best comprehensive properties among all the samples.The full AKIBs based on CG-KFe_(0.31)Mn_(0.69)HCF cathode achieves the high energy density(83 Wh kg^(-1)),superior power density,high capacity retention(83%)over high-rate long-term cycles,good adaptation to a wide temperature range(-20 to 40℃)and high reliability even under outside deformations.Therefore,this work not only provides a new clue to design the highperformance cathode,but also promotes the applications of AKIBs for diverse electronics and wide working environments.

Electronic Structure of AIB2-type U-Si Binary Intermetallic Compounds by Hybrid Density Functional Calculations

In this paper the electronic structure of A1B2-type USi2 has been explored using DFT, DFT＋U and hybrid functional （HSE） methods. It reveals that c/a has great effect on the electronic structure, particularly theforbitals, and there exists strong hybridization between the Si-p and U-d orbitals in A1B2-type USi2. These calculations uncover that there exists similarities on the crystal structure and the electronic structure between AIB2-type USi2 and UaSis. Present calculations provide a further insight on the U3Si5, a heavy-fermion system.

Potential application of functional micro-nano structures in petroleum

This paper takes micro-nano motors and metamaterials as examples to introduce the basic concept and development of functional micro nano structures, and analyzes the application potential of the micro-nano structure design and manufacturing technology in the petroleum industry. The functional micro-nano structure is the structure and device with special functions prepared to achieve a specific goal. New functional micro-nano structures are classified into mobile type(e.g. micro-nano motors) and fixed type(e.g. metamaterials), and 3 D printing technology is a developed method of manufacturing. Combining the demand for exploration and development in oil and gas fields and the research status of intelligent micro-nano structures, we believe that there are 3 potential application directions:(1) The intelligent micro-nano structures represented by metamaterials and smart coatings can be applied to the oil recovery engineering technology and equipment to improve the stability and reliability of petroleum equipment.(2) The smart micro-nano robots represented by micro-motors and smart microspheres can be applied to the development of new materials for enhanced oil recovery, effectively improving the development efficiency of heavy oil, shale oil and other resources.(3) The intelligent structure manufacturing technology represented by 3 D printing technology can be applied to the field of microfluidics in reservoir fluids to guide the selection of mine flooding agents and improve the efficiency of mining.

Synthesis and electrochemical performance of micro-nano structured Li Fe1-xMnxPO4/C(0≤x≤0.05)cathode for lithium-ion batteries

Micro-nano structured Li Fe（1-x）MnxPO4/C（0≤x≤0.05）cathodes were prepared by spray drying,followed by calcination at 700°C.The spherical Li Fe（1-x）MnxPO4/C（0≤x≤0.05）particles with the size of 0.5 to5.0μm are composed of lots of nanoparticles of 20 to 30 nm,and have the well-developed interconnected pore structure.In contrast,when Mn doping content is 3 mol%（x=0.03）,the Li Fe（0.97）Mn（0.03）PO4/C demonstrates maximum specific surface area of 31.30 m^2/g,more uniform pore size and relatively better electrochemical performance.The initial discharge capacities are 161.59,157.04 and 153.13 m Ah/g at a discharge rate of 0.2,0.5 and 1 C,respectively.Meanwhile,the discharge capacity retentions are～100%after 120 cycles.The improved electrochemical performance should be attributed to higher specific surface,smaller polarization voltage,and a high Li~＋diffusion rate due to the micro-nano porous structure and lattice expansion produced by Mn doping.

Design and implementation of binary tree data structure based on DNA computing

The designing,encodings and an instance of simulation of a binary tree for DNA computer were proposed,which utilizes the method of biology to complete inserting and deleting of the binary tree. Firstly,DNA encodings for storage and all elements of the binary tree were completely given out. Then, the implementations of all bio-operations in DNA computer were described. Finally, to prove the feasibility of this method, an actual binary tree with detailed nucleotide encodings was introduced. The process of an algorithm implemented on this binary tree was demonstrated. Based on this method, more other data structures in DNA computer can be developed.

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in aqueous solutions and its applications in binary and ternary aqueous solutions

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.

Micro-nanostructural designs of bifunctional electrocatalysts for metal-air batteries

Water-based rechargeable metal-air batteries play an important role in the storage and conversion of renewable electric energy.However,the sluggish kinetics of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)have limited the practical application of rechargeable metal-air batteries.Most of reviews were focused on single functional electrocatalysts while few on bifunctional electrocatalysts.It is indispensable but challenging to design a bifunctional electrocatalyst that is active and stable to the two reactions.Recently,attempts to develop high active bifunctional electrocatalysts for both ORR and OER increase rapidly.Much work is focused on the micro-nano design of advanced structures to improve the performance of bifunctional electrocatalyst.Transition-metal materials,carbon materials and composite materials,and the methods developed to prepare micro-nano structures,such as electrochemical methods,chemical vapor deposition,hydrothermal methods and template methods are reported in literatures.Additionally,many strategies,such as adjustments of electronic structures,oxygen defects,metal-oxygen bonds,interfacial strain,nano composites,heteroatom doping etc.,have been used extensively to design bifunctional electrocatalysts.To well understand the achievements in the recent literatures,this review focuses on the micro-nano structural design of materials,and the related methods and strategies are classed into two groups for the improvement of intrinsic and apparent activities.The fine adjustment of nano structures and an in-depth understanding of the reaction mechanism are also discussed briefly.

Structural, mechanical, and electronic properties of 25 kinds of Ⅲ–Ⅴbinary monolayers: A computational study with first-principles calculation

Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound according to the atomic number in the periodic table is defined, and based on the definition, the 25 kinds of Ⅲ–V binary compounds are exactly located at a symmetric position in a symmetric matrix. The mechanical properties and band gaps are found to be very dependent on relative radius, while the effective mass of holes and electrons are found to be less dependent. A linear function between Young’s modulus and formation energy is fitted with a linear relation in this paper. The change regularity of physical properties of B–V(V = P, As, Sb, Bi) and Ⅲ–N(Ⅲ = Al, Ga, In, Tl) are found to be very different from those of other Ⅲ–V binary compounds.

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO_4-H_2O and NaF-H_2O binary solutions and NaClO_4-NaF-H_2O ternary solution

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.

Generalized model for laser-induced surface structure in metallic glass

The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated.We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid.A generalized model is presented to describe the special morphology,which fits the experimental result well.It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples.The greater the viscosity is,the shorter the amplitude and the wavelength are.

A new strength criterion for structured soils

Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soils in many aspects, especially in their strength properties, Thus, the influence of soil structure （bonding and fabric） on the mechanical properties of structured soils cannot be correctly described, By analyzing the breakage mechanism of natural soils, the structured soils can be conceptualized as binary medium materials consisting of bonded blocks and weakened bands. On this basis, a new strength criterion is pro- posed for structured soils, The expressions of the strength criterion on both meridian and deviator planes are given to describe the strength properties of structured soils on these planes. The proposed strength criterion is compared with available test data under conventional and true triaxial stress conditions in the literature. It is observed that the proposed strength criterion agrees well with the test data.

Rock mass structural recognition from drill monitoring technology in underground mining using discontinuity index and machine learning techniques

A procedure to recognize individual discontinuities in rock mass from measurement while drilling(MWD)technology is developed,using the binary pattern of structural rock characteristics obtained from in-hole images for calibration.Data from two underground operations with different drilling technology and different rock mass characteristics are considered,which generalizes the application of the methodology to different sites and ensures the full operational integration of MWD data analysis.Two approaches are followed for site-specific structural model building:a discontinuity index(DI)built from variations in MWD parameters,and a machine learning(ML)classifier as function of the drilling parameters and their variability.The prediction ability of the models is quantitatively assessed as the rate of recognition of discontinuities observed in borehole logs.Differences between the parameters involved in the models for each site,and differences in their weights,highlight the site-dependence of the resulting models.The ML approach offers better performance than the classical DI,with recognition rates in the range 89%to 96%.However,the simpler DI still yields fairly accurate results,with recognition rates 70%to 90%.These results validate the adaptive MWD-based methodology as an engineering solution to predict rock structural condition in underground mining operations.

Prediction of the solidification structure of casting and heterogeneous nucleation

The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooledcopper chill in an adiabatic mold. The location of columnar to equiaxed transition (CET) in thesolidified alloy ingot was measured. A numerical simulation for grain structure formation based onthe Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloywas evaluated by producing similar structure with the experimental one. The frequency ofheterogeneous nucleation was expressed as a probabilistic function with an exponential form ofundercooling that deter-mines the probability of nucleation event in the simulation. The value ofthe exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloyvaried with initial Si content.

Reservoir micro structure of Da'anzhai Member of Jurassic and its petroleum significance in Central Sichuan Basin, SW China

Based on the qualitative study of microscopic reservoir features using core analysis,cast and fluorescence thin sections inspection,scanning electron microscope(SEM)and field emission scanning electron microscope(FESEM)and quantitative examination of pore size and geometry using mercury injection,nano-CT and nitrogen adsorption,reservoir rock of Da’anzhai Member were divided into 9 types,while storage spaces were divided into 4 types and 14 sub-types.The study shows that sparry coquina is the most promising reservoir type.Pores that smaller than 1μm in diameter contribute 91.27%of storage space volume.Most of them exhibit slot-like geometry with good connectivity.By building up storage space models,it was revealed that micron scale storage spaces mainly composed of fractures and nanometer scale pores and fractures form multi-scale dual porosity system.Low resource abundance,small single well controlled reserve,and low production are related to the nano-scale pore space in Da’anzhai Memer,whereas the dual-porosity system composed of pores and fractures makes for long-term oil yield.Due to the existence of abundant slot-like pore space and fractures,economic tight oil production was achieved without stimulations.