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273 results on '"Wang, Lin"'

2. A Linear Scaling Three Dimensional Fragment Method for Large Scale Electronic Structure Calculations

Author

Wang, Lin-Wang, Zhao, Zhengji, and Meza, Juan

Subjects
Materials science, Linear scaling 3D fragments large scale electronic structure internal electric field
Abstract

We present a novel linear scaling ab initio total energy electronic structure calculation method, which is simple to implement, easily to parallelize, and produces essentially the same results as the direct ab initio method, while it could be thousands of times faster. Using this method, we have studied the dipole moments of CdSe quantum dots, and found both significant bulk and surface contributions. The bulk dipole contribution cannot simply be estimated from the bulk spontaneous polarization value by a proportional volume factor. Instead it has a geometry dependent screening effect. The dipole moment also produces a strong internal electric field which induces a strong electron hole separation.

Published
2008

3. Spontaneous Superlattice Formation in Nanorods through Partial Cation Exchange

Author

Robinson, Richard D., Sadtler, Bryce, Demchenko, Denis O., Erdonmez, Can K., Wang, Lin-Wang, and Alivisatos, A. Paul

Subjects
Materials science, Inorganic, organic, physical and analytical chemistry, Condensed matter physics, superconductivity and superfluidity, cation exchange nanorod superlattice strain-mediated growth nanocrystals colloidal
Abstract

Lattice mismatch strains are widely known to control nanoscale pattern formation in heteroepitaxy, but such effects have not been exploited in colloidal nanocrystal growth. We demonstrate a colloidal route to synthesizing CdS-Ag2S nanorod superlattices through partial cation exchange. Strain induces the spontaneous formation of periodic structures. Ab initio calculations of the interfacial energy and modeling of strain energies show that these forces drive the self-organization. The nanorod superlattices exhibit high stability against ripening and phase mixing. These materials are tunable near-infrared emitters with potential applications as nanometer-scale optoelectronic devices.

Published
2008

5. Optical properties of ZnO/ZnS and ZnO/ZnTe heterostructures for photovoltaic applications

Author

Schrier, Joshua, Demchenko, Denis O., Wang, Lin-Wang, and Alivisatos, A. Paul

Subjects
Solar energy, Materials science, ZnO
Abstract

Although ZnO and ZnS are abundant, stable, environmentally benign, their band gap energies (3.44 eV, 3.72 eV) are too large for optimal photovoltaic efficiency. By using band-corrected pseudopotential density-functional theory calculations, we study how the band gap,optical absorption, and carrier localization can be controlled by forming quantum-well like and nanowire-based heterostructures ofZnO/ZnS and ZnO/ZnTe. In the case of ZnO/ZnS core/shell nanowires, which can be synthesized using existing methods, we obtain a band gap of 2.07 eV, which corresponds to a Shockley-Quiesser efficiency limitof 23 percent. Based on these nanowire results, we propose that ZnO/ZnScore/shell nanowires can be used as photovoltaic devices with organic polymer semiconductors as p-channel contacts.

Published
2008

6. Mechanical and electronic-structure properties of compressed CdSe tetrapod nanocrystals

Author

Schrier, Joshua, Lee, Byounghak, and Wang, Lin-Wang

Subjects
Materials science, Condensed matter physics, superconductivity and superfluidity, General and miscellaneous//mathematics, computing, and information science, nanoscience tetrapod nanocrystal CdSe ESCAN SEPM
Abstract

The coupling of mechanical and optical properties in semiconductor nanostructures can potentially lead to new types of devices. This work describes our theoretical examination of the mechanical properties of CdSe tetrapods under directional forces, such as may be induced by AFM tips. In addition to studying the general behavior of the mechanical properties under modifications of geometry, nanocrystal-substrate interaction, and dimensional scaling, our calculations indicate that mechanical deformations do not lead to large changes in the band-edge state eigenenergies, and have only a weak effect on the oscillator strengths of the lowest energy transitions.

Published
2008

7. A Linear Scaling Three Dimensional Fragment Method for Large Scale Electronic Structure Calculations

Author

Wang, Lin-Wang

Subjects
Materials science, Linear scaling 3D fragments large scale electronic structure internal electric field
Abstract

We present a novel linear scaling ab initio total energy electronic structure calculation method, which is simple to implement, easily to parallelize, and produces essentially the same results as the direct ab initio method, while it could be thousands of times faster.

Published
2007

8. Localized Electron States Near a Metal-Semiconductor Nanocontact

Author

Demchenko, Denis O. and Wang, Lin-Wang

Subjects
Condensed matter physics, superconductivity and superfluidity, Materials science, nanowire electronic structure nanocontact
Abstract

The electronic structure of nanowires in contact with metallic electrodes of experimentally relevant sizes is calculated by incorporating the electrostatic polarization potential into the atomistic single particle Schrodinger equation. We show that the presence of an electrode produces localized electron/hole states near the electrode, a phenomenon only exhibited in nanostructures and overlooked in the past. This phenomenon will have profound implications on electron transport in such nanosystems. We calculate several electrode/nanowire geometries, with varying contact depths and nanowire radii. We demonstrate the change in the band gap of up to 0.5 eV in 3 nm diameter CdSe nanowires and calculate the magnitude of the applied electric field necessary to overcome the localization.

Published
2007

9. Nonlocal exchange correlation in screened-exchange density functional methods

Author

Lee, Byounghak, Wang, Lin-Wang, Spataru, Catalin D., and Louie, Steven G.

Subjects
Condensed matter physics, superconductivity and superfluidity, Materials science, density functional theory screened-exchange method exchang-correlation
Abstract

We present a systematic study on the exchange-correlation effects in screened-exchange local density functional method. To investigate the effects of the screened-exchange potential in the band gap correction, we have compared the exchange-correlation potential term in the sX-LDA formalism with the self-energy term in the GW approximation. It is found that the band gap correction of the sX-LDA method primarily comes from the downshift of valence band states, resulting from the enhancement of bonding and the increase of ionization energy. The band gap correction in the GW method, on the contrary, comes in large part from the increase of the conduction band energies. We also studied the effects of the screened-exchange potential in the total energy by investigating the exchange-correlation hole in comparison with quantum Monte Carlo calculations. When the Thomas-Fermi screening is used, the sX-LDA method overestimates (underestimates) the exchange-correlation hole in short (long) range. From the exchange-correlation energy analysis we found that the LDA method yields better absolute total energy than sX-LDA method.

Published
2007

10. Linear Scaling 3D Fragment Method for Large-Scale Electronic Structure Calculations

Author

Wang, Lin-Wang, Zhao, Zhengji, and Meza, Juan

Subjects
Materials science, spatial decomposition overlapping fragments 3D fragments linear scaling large-scale thousands of processors
Abstract

We present a linear scaling 3 dimensional fragment (LS3DF) method that uses a novel decomposition and patching scheme to do ab initio density functional theory (DFT) calculations for large systems. This method cancels out the artificial boundary effects that arise from the spatial decomposition. As a result, the LS3DF results are essentially the same as the original full-system DFT results with errors smaller than the errors introduced by other sources of numerical approximations. In addition, the resulting computational times are thousands of times smaller than conventional DFT methods, making calculations with 100,000 atom systems possible. The LS3DF method is applicable to insulator and semiconductor systems, which covers a current gap in the DOE's materials science code portfolio for large-scale ab initio simulations.

Published
2006

11. Single particle wavefunction localizations in bulged CdSe nanowires

Author

Zhao, Zhengji, Wang, Lin-Wang, and Wu, Fengmin

Subjects
Materials science, nanowire morphology EPM localization
Abstract

Using atomistic empirical pseudopotentials, we have calculated the electronic structures of CdSe nanowires with a bulged area. The localized state wavefunctions and their binding energies are calculated, and their dependences on the bulged area shape are analyzed. We find that both the binding energy and the wavefunction localization strongly depend on the bulged area shape, with the most compact shape produces the largest binding energy and strongest wavefunction localization. We also find that the top of the valence band state has a weaker localization than the bottom of the conduction band state due to an effective mass anisotropy.

Published
2006

12. The Use of Trust Regions in Kohn-Sham Total Energy Minimization

Author

Yang, Chao, Meza, Juan C., and Wang, Lin-wang

Subjects
Atomic and molecular physics, Materials science, Kohn-Sham equation Total energy minimization trust regions constrained optimization
Abstract

The Self Consistent Field (SCF) iteration, widely used for computing the ground state energy and the corresponding single particle wave functions associated with a many-electronatomistic system, is viewed in this paper as an optimization procedure that minimizes the Kohn-Sham total energy indirectly by minimizing a sequence of quadratic surrogate functions. We point out the similarity and difference between the total energy and the surrogate, and show how the SCF iteration can fail when the minimizer of the surrogate produces an increase in the KS total energy. A trust region technique is introduced as a way to restrict the update of the wave functions within a small neighborhood of an approximate solution at which the gradient of the total energy agrees with that of the surrogate. The use of trust region in SCF is not new. However, it has been observed that directly applying a trust region based SCF(TRSCF) to the Kohn-Sham total energy often leads to slow convergence.We propose to use TRSCF within a direct constrained minimization(DCM) algorithm we developed in \cite dcm. The key ingredients of theDCM algorithm involve projecting the total energy function into a sequence of subspaces of small dimensions and seeking the minimizer of the total energy function within each subspace. The minimizer of a subspace energy function, which is computed by TRSCF, not only provides a search direction along which the KS total energy function decreases but also gives an optimal "step-length" that yields a sufficient decrease in total energy. A numerical example is provided to demonstrate that the combination of TRSCF and DCM is more efficient than SCF.

Published
2006

13. Band gap bowing and electron localization of (GaxIn1-x)N

Author

Lee, Byounghak and Wang, Lin-Wang

Subjects
Materials science, III-nitride band gap bowing hole localization screened-exchange density functional method
Abstract

The band gap bowing and the electron localization of GaxIn1-xN are calculated using both the local density approximation (LDA) and screened-exchange local density functional (sX-LDA) methods. The calculated sX-LDA band gaps are in good agreement with the experimentally observed values, with errors of -0.26 and 0.09 eV for bulk GaN and InN, respectively. The LDA band gap errors are 1.33 and 0.81 eV for GaN and InN, in order. In contrast to the gap itself, the band gap bowing parameter is found to be very similar in sX-LDA and LDA. We identify the localization of hole states in GaxIn1-xN alloys along In-N-In chains. The predicted localization is stronger in sX-LDA.

Published
2006

14. Motif based Hessian matrix for ab initio geometry optimization of nanostructures

Author

Zhao, Zhengji, Wang, Lin-Wang, and Meza, Juan

Subjects
Materials science, geometry optimization motif Hessian matrix preconditioned CG nanostructures convergence acceleration atomic relaxation
Abstract

A simple method to estimate the atomic degree Hessian matrix of a nanosystem is presented. The estimated Hessian matrix, based on the motif decomposition of the nanosystem, can be used to accelerate ab initio atomic relaxations with speedups of 2 to 4 depending on the size of the system. In addition, the programing implementation for using this method in a standard ab initio package is trivial.

Published
2006

15. Electronic Structure of zinc-blende AlxGa1-xN; Screened-Exchange Study

Author

Lee, Byounghak and Wang, Lin-Wang

Subjects
Condensed matter physics, superconductivity and superfluidity, Materials science, density functional screened-exchange nitride
Abstract

We present a first principle investigation of the electronic structure and the band gap bowing parameter of zinc-blende \AlGaN using both local density approximation and screened-exchange density functional method. The calculated sX-LDA band gaps for GaN and AlN are 95 percent and 90 percent of the experimentally observed values, respectively, while LDA under estimates the gaps to 62 percent and 70 percent. In contrast to the gap itself, the band gap bowing parameter is found to be very similar in sX-LDA and LDA. Because of the difference in the conduction band structure, the direct to indirect band gap crossover is predicted to occur at different Al concentration.

Published
2006

16. A Constrained Optimization Algorithm for Total Energy Minimization in Electronic Structure Calculation

Author

Yang, Chao, Meza, Juan C., and Wang, Lin-Wang

Subjects
General and miscellaneous//mathematics, computing, and information science, Atomic and molecular physics, Materials science, electronic structure calculation total energy minimization nonlinear eigenvalue problems constrained optimization
Abstract

A new direct constrained optimization algorithm for minimizing the Kohn-Sham (KS) total energy functional is presented in this paper. The key ingredients of this algorithm involve projecting the total energy functional into a sequences of subspaces of small dimensions and seeking the minimizer of total energy functional within each subspace. The minimizer of a subspace energy functional not only provides a search direction along which the KS total energy functional decreases but also gives an optimal "step-length" to move along this search direction. A numerical example is provided to demonstrate that this new direct constrained optimization algorithm can be more efficient than the self-consistent field (SCF) iteration.

Published
2005

17. Electronic structure of Calcium hexaborides

Author

Lee, Byounghak and Wang, Lin-Wang

Subjects
Condensed matter physics, superconductivity and superfluidity, Materials science, density functional screened-exchange calcium hexaborides
Abstract

We present a theoretical study of crystal and electronic structures of CaB6 within a screened-exchange local density approximation (sX-LDA). Our ab initio total energy calculations show that CaB6 is a semiconductor with a gap of > 1.2 eV, in agreement with recent experimental observations. We show a very sensitive band gap dependence on the crystal internal parameter, which might partially explain the scatter of previous theoretical results. Our calculation demonstrates that it is essential to study this system simultaneously for both crystal structures and electronic properties, and that the sX-LDA provides an ideal method for this problem.

Published
2005

21. The prediction of spontaneous oil-water imbibition in composite capillary

Author

Wang Lin, Ma Feiying, Dawei Liu, and Yongming He

Subjects
Materials science, Capillary action, 020209 energy, Composite number, Energy Engineering and Power Technology, Geology, 02 engineering and technology, Mechanics, Radius, Geotechnical Engineering and Engineering Geology, Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, Cross section (physics), Viscosity, Fuel Technology, 020401 chemical engineering, Geochemistry and Petrology, 0202 electrical engineering, electronic engineering, information engineering, Oil water, Imbibition, Wetting, 0204 chemical engineering, Physics::Atmospheric and Oceanic Physics
Abstract

In view of the classical Lucas-Washburn equation, which can only describe the spontaneous imbibition of single wetted capillary, a tilted composite capillary model with circular cross section, composed of different wettability capillary wall was established. The model can describe the spontaneous oil-water imbibition of water-wet capillary, oil-wet capillary and mixed wetting capillary. Through numerical solution of the model equation, it is found that the component content of the capillary walls, the capillary radius and the oil-water viscosity ratio have great effects on the spontaneous oil-water imbibition. Effects of capillary inclination angle and inertia force on spontaneous oil-water imbibition are related to the capillary scale. Effects of capillary inclination angle and inertia force can be ignored in small radius capillary, while effects of inclination angle and inertia force can not be ignored in large radius capillary.

Published
2022

22. Application and analysis of multi-stage flash vaporization process in steam production in high-temperature heat pump system with large temperature difference

Author

Chen Jingkai, XU Jingyu, Wang Lin, Huang Lumeng, Zhang Yanting, Huang Zheng, and Zhang Hao

Subjects
Exergy, Materials science, business.industry, Mechanical Engineering, Evaporation, Boiler (power generation), Flash evaporation, Building and Construction, law.invention, Refrigerant, symbols.namesake, law, Vaporization, symbols, Carnot cycle, Process engineering, business, Heat pump
Abstract

The high-temperature heat pump steam system (HTHPS) is an effective way to replace the calcining boiler's steam. However, the large temperature span of the system leads to colossal exergy loss of refrigerant in expansion valves and other components. Therefore, it is hoped to adopt the dual-flash vaporization process to improve the system's steam production performance. In this paper, three thermodynamic models and exergy models of HTHPS with a double flash evaporation process are established. Furthermore, this paper uses the multivariate simulated annealing algorithm to calculate the optimal COP of the system. Then, by comparing the single-stage compression (SC) system and the quasi-two-stage compression (QTC) system, the influence of the dual-flash vaporization process on HTHPS is analyzed. The results show that under the same environment, the COP of the dual-flash vaporization process compression system is 23.8% 44.54% higher than that of the SC system. With the increase of the system temperature span, the flash steam supplemental process brings the system to improved thermodynamic performance. Moreover, the exergy model of the dual-flash system is closest to the reversed Carnot cycle, when the evaporation temperature is 50 °C and the condensing temperature is 110 °C.

Published
2022

23. Ambient-condition strategy for rapid mass production of crystalline gallium oxide nanoarchitectures toward device application.

Author

Zhang, Dongdong, Yu, Hao, You, Guiqin, Shao, Gang, Fang, Zhi, Liang, Zhao, Zhang, Tian, Hou, Huilin, Wang, Lin, Chen, Qiaochu, Teng, Jie, and Yang, Weiyou

Subjects
MASS production, ELECTROMAGNETIC wave reflection, ELECTROMAGNETIC wave absorption, GALLIUM, MATERIALS science
Abstract

• Mild and Controllable Fabrication of crystalline Ga 2 O 3 nanostructures. • Kilogram-scale Output of the Ga 2 O 3 nanostructures. • Deep Insight on Growth Mechanism of the Ga 2 O 3 nanostructures. • Interesting Device Applications of the Ga 2 O 3 nanostructures. Currently, the synthesis of nanostructures still encounters two grand challenges: one is the often-required high temperatures and/or high pressures, and the other is the scalable fabrication. Here, to break through such bottlenecks, we demonstrate an ambient-condition strategy for rapid mass production of fourth-generation semiconductor Ga 2 O 3 nanoarchitectures assembled by single-crystalline nanosheets in a controlled manner based on sonochemistry. Their growth is fundamentally determined by the introduced ethanediamine in rationally designed source materials, which could not only protect the metal Ga against reacting with H 2 O into GaOOH, but facilitate the reaction of Ga with OH· radicals for target crystalline Ga 2 O 3 nanostructures. As a proof of concept for applications, the as-fabricated Ga 2 O 3 nanoarchitectures exhibit superb performances for electromagnetic wave absorption with a reflection loss value of 52.2 dB at 8.1 GHz, and ammonia sensing with high sensitivity and selectivity at room temperature, representing their bright future to be commercially applied in modern devices. [Display omitted] A sonochemistry strategy was reported for mass production of crystalline γ-Ga 2 O 3 nanoarchitectures under ambient condition with a high yield of 88% and kilogram-scale output in a controlled manner, excluding the assistance of externally applied high temperatures and high pressures as often-required in reported works. The as-synthesized Ga 2 O 3 nanoarchitectures exhibit superb performances for electromagnetic wave absorption and ammonia sensing with high sensitivity and selectivity at room temperature. The present work could be a significant progress in materials science and technology, to enable the rapid and scalable production of crystalline nanostructures under mild conditions toward practical applications. [ABSTRACT FROM AUTHOR]

Published
2023
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25. State‐of‐charge estimation technique for lithium‐ion batteries by means of second‐order extended Kalman filter and equivalent circuit model: Great temperature robustness state‐of‐charge estimation

Author

Hang Zhang, Fang Yanyan, Yi Cui, Qiang Zhang, Shen Xueling, Yun Fengling, Weicheng Xu, Wang Lin, Wang Linshu, and Xin Zhang

Subjects
Materials science, TK7800-8360, chemistry.chemical_element, Order (ring theory), Ion, Extended Kalman filter, State of charge, chemistry, Robustness (computer science), Control theory, Equivalent circuit, Lithium, Electrical and Electronic Engineering, Electronics
Abstract

The present work focuses on the state‐of‐charge (SOC) estimation of a lithium‐ion battery in terms of a second‐order extended Kalman filter (EKF). First, an equivalent circuit model is introduced to describe the performance of lithium‐ion batteries. The model parameters are then identified through hybrid pulse power characterization experiments conducted over a wide range of temperatures (−10 to 55°C). A two‐dimensional mathematical relationship is established with respect to the SOC and temperature based on a dual‐fifth polynomial expression. The main effects and sensitivities of the SOC and temperature on the parameters are analysed according to the principle of variance analysis and partial derivatives. An estimation algorithm is developed, which combines the two‐dimensional parameter model and second‐order EKF. Finally, the proposed approach is validated compared to other estimation schemes through discharge experiments under extreme temperatures and dynamic loading profiles, which yields experimental results that estimate the SOC with an absolute error of less than 4.5% under harsh conditions. This not only demonstrates that it can characterize dependency of the model parameters on the operating conditions and address the uncertainty of model parameters, but also verifies the advantage of present method at low temperatures especially at sub‐zero temperatures.

Published
2021

26. Influence of sizes on tribological properties and tribofilm formation of lanthanum borate nanospheres in soybean oil

Author

Jiang Wu, Boshui Chen, Wang Lin, Jianhua Fang, and Kecheng Gu

Subjects
food.ingredient, Materials science, Mechanical Engineering, chemistry.chemical_element, 02 engineering and technology, Surfaces and Interfaces, Tribology, 021001 nanoscience & nanotechnology, Soybean oil, Surfaces, Coatings and Films, Metal, 020303 mechanical engineering & transports, food, Adsorption, 0203 mechanical engineering, chemistry, Chemical engineering, visual_art, Lanthanum, Lubrication, visual_art.visual_art_medium, 0210 nano-technology, Boron
Abstract

Vegetable oils exhibit excellent lubrication properties owing to their polar functional groups, which are liable to adsorb on the metal surfaces to form adsorption film and tribofilm. Additionally, nanoparticles play significant roles in enhancing the tribological performances of base oils by means of forming a tribofilm between friction parts. However, little work has been done on clarifying the interaction of nanoparticles and vegetable oils in the film-forming process. In this paper, two varieties of lanthanum borate nanospheres with average diameters of 50 nm (named LBN-1) and 105 nm (named LBN-2) were synthesized. The morphologies, size distribution, and chemical compositions of the nanospheres were characterized using a scanning electron microscopy, dynamic light scattering, Fourier transform infrared, and X-ray diffraction. The tribological characteristics of soybean oils with lanthanum borate nanospheres were evaluated by a four-ball tribo-tester. The tribological performances of soybean oils were obviously improved by lanthanum borate nanospheres. The focused-ion beam/transmission electron microscope analyses results revealed a uniform tribofilm containing LBN-1 was formed, contributing to excellent friction-reducing and anti-wear performances. Whereas the tribofilm of soybean oil/LBN-2 was uneven in thickness and contained more wear debris. The outcome of this work provides significant insights into the tribofilm formation for metal surfaces lubricated with vegetable oils containing different sizes of lanthanum borate nanoparticles.

Published
2021

27. Highly Efficient MoS2 Nanocatalysts for Slurry-Phase Hydrogenation of Unconventional Feedstocks into Fuels

Author

Congxin Wang, Wei Qu, Zhendong Pan, Han Jianqiang, Donge Wang, Huaijun Ma, Zheng Anda, Wang Lin, and Zhijian Tian

Subjects
Fuel Technology, Materials science, Chemical engineering, General Chemical Engineering, Phase (matter), Hydrogenation reaction, Slurry, Energy Engineering and Power Technology, Nanomaterial-based catalyst, Catalysis
Abstract

Highly active MoS2 catalysts were developed by tuning the precursors and synthesis solvents to upgrade unconventional feedstocks into light fuels through the slurry-phase hydrogenation reaction. A ...

Published
2021

29. A new efficient deep-red-emission phosphor Al2O3:Cr3+/Y3Al5O12:Ce3+ for plant growth

Author

Takatoshi Seto, Yuhua Wang, and Wang Lin

Subjects
0106 biological sciences, Plant growth, Materials science, Analytical chemistry, Oxide, Quantum yield, Phosphor, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Emission intensity, Inorganic Chemistry, chemistry.chemical_compound, chemistry, Excited state, 0210 nano-technology, Excitation, 010606 plant biology & botany, Visible spectrum
Abstract

Two new types of inexpensive mixed phosphors, Al2O3:Cr3+/YAG:Ce3+ and Al2O3:Cr3+/(Ba,Sr)2SiO4:Eu2+, were designed and synthesized using a high-temperature solid-state method. The emission intensity under blue excitation was reported to be of the order of Al2O3:Cr3+/YAG:Ce3+ > Al2O3:Cr3+/(Ba,Sr)2SiO4:Eu2+ > Al2O3:Cr3+. By adding YAG:Ce3+ to Al2O3:Cr3+, the excitation spectrum of the new phosphor was changed; blue excitation corresponding to 4f → 5d transition appeared because of the good overlap between the yellow emission of YAG:Ce3+ and the yellow excitation of Al2O3:Cr3+. The emission intensity of deep red (696 nm) under excitation at 460 nm demonstrates a significant enhancement and the quantum yield increases to 1.45 times that of Al2O3:Cr3+. Moreover, the new phosphor can be excited by light in a range between 325 and 650 nm, which could be considered as the widest excitation in the visible light region of the known deep red oxide phosphors. The temperature dependency of the emission under blue excitation is unique (I150 °C/I25 °C = 84%), which is much better than that of yellow excitation and that at 400 nm. The reflection-emission spectrum recorded under white light from a Xe lamp resembling sunlight demonstrated that the new phosphor has provided a strong deep-red light. The above results indicated that the new phosphor provides a comprehensive assistance in promoting plant growth both under a combination with a blue LED chip and under the Sun.

Published
2021

30. A versatile synthetic approach to tunable dual-emissive Pdots with very small-size based on amphiphilic block copolymers for cell imaging

Author

Ding Yuanyuan, Wang Lin, Ziqiang Lei, Liu Meina, Lai Shoujun, Wang Kailong, Guan Xiaolin, Jinhui Tong, and Yang Xueqin

Subjects
Materials science, Fluorophore, Quenching (fluorescence), Biocompatibility, Nanotechnology, Fluorescence, chemistry.chemical_compound, chemistry, Polymerization, Amphiphile, Materials Chemistry, Copolymer, General Materials Science, Biosensor
Abstract

Fluorescent polymer dots (Pdots) are a new type of efficient fluorophores with superior optical properties. However, their practical applications in bioimaging and biosensing are being hampered by their potential toxicity, poor water-solubility and the aggregation caused quenching effect. Herein, we report an effective strategy for the preparation of a series of new small-size aggregation-induced emission (AIE) active non-conjugated Pdots, which were self-assembled from three amphiphilic block copolymers, 4s-TPE-PCL-b-PNIPAM-Eu(III) (TPNE), 4s-TPE-PCL-b-PAA-Eu(III) (TPAE) and 4s-TPE-PCL-b-PVP-Eu(III) (TPVE). All of the blocks were synthesized by free-radical polymerization using a macroazoinitiator containing AIE fluorophore tetraphenylethene (TPE), poly(e-caprolactone) (PCL) segment and azo group, respectively. The obtained TPNE, TPAE and TPVE Pdots had small diameters down to 5 nm and good monodispersity. The Pdots not only exhibited well-separated dual-wavelength emission by 430 and 615 nm upon excitation at 360 and 395 nm, but also displayed thermo-tunable and pH-dependent fluorescence properties, excellent photostability, good water-solubility, good biocompatibility, favorable photoreversibility and noncytotoxicity. More interestingly, the as-prepared three kinds of Pdots displayed reversibly distinct dual-color (blue-red) fluorescence in the targeted three cancer cells (HepG2, A549 and HeLa cells) by merely tuning the excitation wavelength, indicating their potential applications as sensor and multicolour imaging agents in cell biology and diagnostics.

Published
2021

33. The synergistic effect of carbon materials on properties of copper-based friction materials

Author

Lin Xueyang, Liao Ning, Xiong Xiang, Chen Jie, Liu Rutie, Li Zhengzhou, and Wang Lin

Subjects
Materials science, Mechanical Engineering, Metallurgy, Petroleum coke, Iron oxide, Oxide, chemistry.chemical_element, Tribology, Copper, Surfaces, Coatings and Films, chemistry.chemical_compound, General Energy, chemistry, Powder metallurgy, Graphite, Carbon
Abstract

Purpose This study aims to investigate the effect of combined use of granular graphite and petroleum coke on the properties of copper-based friction materials and the friction and wear mechanisms. Design/methodology/approach Copper-based friction materials with different proportions of petroleum coke and granular graphite were prepared by using powder metallurgy. The friction surfaces were analyzed. Findings Changing the ratio of petroleum coke/granular graphite affects the formation of oxides and sulfides on the surface of the materials. Increasing the petroleum coke promotes the production of metal sulfide and sulfate in the friction materials and reduces coefficient of friction (COF) and wear. Increasing petroleum coke also increases the amount of carbonic oxide (CO) released during the braking process and promotes the reduction process of iron oxide on the friction surface. Originality/value The synergistic effect of carbon materials on copper-based friction materials was studied in terms of the tribological chemical reaction. This research provides useful information for the selection of carbon materials in friction materials. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0075/

Published
2020

34. Effect of the Pore Structure on Adsorption and Diffusion Migration of Different Rank Coal Samples

Author

Guixin Zhang, Li Zhiqiang, Wang Lin, Xiangjun Chen, and Jun Liu

Subjects
Materials science, Rank (linear algebra), business.industry, General Chemical Engineering, Structure (category theory), Energy Engineering and Power Technology, Thermodynamics, 02 engineering and technology, 021001 nanoscience & nanotechnology, Fuel Technology, Adsorption, 020401 chemical engineering, Coal, 0204 chemical engineering, Diffusion (business), 0210 nano-technology, business, Pressure diffusion
Abstract

Existing experimental equipment was used to conduct high-temperature and -pressure diffusion tests on four coal samples with different low, middle, and high ranks. Then, the characteristics of the ...

Published
2020

35. Research on dynamic compression properties and deformation mechanism of Ti6321 titanium alloy

Author

Cheng Xingwang, Ning Zixuan, Wang Lin, Cheng Huanwu, Liu Anjin, Zhou Zhe, Ali Tayyeb, Liu Xiaopin, Zhang Binbin, and Xu Xuefeng

Subjects
lcsh:TN1-997, Materials science, 02 engineering and technology, Slip (materials science), 01 natural sciences, Biomaterials, 0103 physical sciences, Dynamic compression properties, Composite material, lcsh:Mining engineering. Metallurgy, 010302 applied physics, Deformation mechanism, technology, industry, and agriculture, Metals and Alloys, Twin, Split-Hopkinson pressure bar, Strain rate, 021001 nanoscience & nanotechnology, Surfaces, Coatings and Films, Ceramics and Composites, Hardening (metallurgy), Titanium alloy, Deformation (engineering), 0210 nano-technology, Crystal twinning, Electron backscatter diffraction
Abstract

This research reports detailed investigations on the dynamic compression properties and the deformation mechanism in Ti6321 titanium alloy subjected to high strain rate loading by using the split Hopkinson pressure bar (SHPB). Microstructures of deformed samples were analyzed by scanning electron microscopy (SEM) with an electron backscatter diffraction (EBSD) detector and transmission electron microscopy (TEM). The experimental results demonstrate that with the increase of strain rate, the strength of Ti6321 titanium alloy increases significantly, which indicates the phenomenon of strain rate hardening. Due to twinning, the initial plastic deformation mechanism is by twin shear, the twins' interface is straight, continuous, and symmetrically distributed. The majority of twins are found at low strain stage (the strain range of 0.03 ∼ 0.06), which justifies the early initiation and contribution of twins in plastic deformation of the material. It also indicates that during plastic deformation twinning dominates the dynamic deformation mechanism. As the strain (e) increases further (when the strain is greater than 0.06), the number of twins also increases up to ɛ = 0.20. After that, the dynamic deformation mechanism started shifting from twinning deformation to dislocation slip.

Published
2020

36. Photo-Degradation Performance for RhB under Visible Light Irradiation

Author

Wang Lin, Zou Leideng, Zhang Zhi-Yong, Zhang Haibo, and Liu Cheng

Subjects
010302 applied physics, Pollution, Photo catalytic, Materials science, Abundance (chemistry), media_common.quotation_subject, Visible light irradiation, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Photochemistry, 01 natural sciences, Electronic, Optical and Magnetic Materials, Control and Systems Engineering, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, Degradation (geology), Electrical and Electronic Engineering, 0210 nano-technology, Photodegradation, Earth (classical element), media_common
Abstract

MoS2 is a promising photo-catalyst for the degradation of organic pollution due to its large surface area, low cost, easy preparation, and earth abundance. However, their limited quantity of active...

Published
2020

37. Spontaneous Gas-Water Imbibition in Mixed-Wet Pores

Author

Yong Ming He, Wang Lin, Fei Ying Ma, Hong Hui Wang, and Yi Hang Xiao

Subjects
Materials science, Chemical engineering, Imbibition, Geotechnical Engineering and Engineering Geology
Published
2020

38. Lithium-ion cell inconsistency analysis based on three-parameter Weibull probability model

Author

Wang Linshu, Shi-Gang Lu, Wang Lin, Jian-Tao Wang, Fang Yanyan, Hang Zhang, and Zhao Ting

Subjects
Battery (electricity), Materials science, 020502 materials, Metals and Alloys, Phase (waves), 02 engineering and technology, Mechanics, Internal resistance, Condensed Matter Physics, Symmetry (physics), 0205 materials engineering, Dispersion (optics), Materials Chemistry, Physical and Theoretical Chemistry, Ohmic contact, Weibull distribution, Voltage
Abstract

The inconsistency of lithium-ion cells degrades battery performance, lifetime and even safety. The complexity of the cell reaction mechanism causes an irregular asymmetrical distribution of various cell parameters, such as capacity and internal resistance, among others. In this study, the Newman electrochemical model was used to simulate the 1C discharge curves of 100 LiMn2O4 pouch cells with parameter variations typically produced in manufacturing processes, and the three-parameter Weibull probability model was used to analyze the dispersion and symmetry of the resulting discharge voltage distributions. The results showed that the dispersion of the voltage distribution was related to the rate of decrease in the discharge voltage, and the symmetry was related to the change in the rate of voltage decrease. The effect of the cells’ capacity dominated the voltage distribution thermodynamically during discharge, and the phase transformation process significantly skewed the voltage distribution. The effects of the ohmic drop and polarization voltage on the voltage distribution were primarily kinetic. The presence of current returned the right-skewed voltage distribution caused by phase transformation to a more symmetrical distribution. Thus, the Weibull parameters elucidated the electrochemical behavior during the discharge process, and this method can guide the prediction and control of cell inconsistency, as well as detection and control strategies for cell management systems.

Published
2020

39. Luminescent Properties of CaWO4∶Eu3+ Phosphors Doped with Mg2+ or Zn2+

Author

赵海琴 Zhao Hai-qin, 王林香 Wang Lin-xiang, and 孙德方 Sun De-fang

Subjects
Radiation, Materials science, business.industry, Doping, Optoelectronics, Phosphor, Condensed Matter Physics, Luminescence, business, Electronic, Optical and Magnetic Materials
Published
2020

40. Luminescent Properties of Dy3+, Ce3+ Co-doped Y3Al5O12 Phosphors

Author

王 霞 Wang Xia, 孙德方 Sun De-fang, 李 晴 Li Qing, and 王林香 Wang Lin-xiang

Subjects
Radiation, Materials science, Chemical engineering, Phosphor, Condensed Matter Physics, Luminescence, Co doped, Electronic, Optical and Magnetic Materials
Published
2020

42. Tool Wear in Disc Milling Grooving of Aircraft Engine Blisk

Author

Yang Feng, Yaoyao Shi, Tao Zhao, Hongmin Xin, Wu Huawei, and Wang Lin

Subjects
0209 industrial biotechnology, Flank, Materials science, Mechanical Engineering, Computational Mechanics, Processing efficiency, Mechanical engineering, Tool wear rate, 02 engineering and technology, Spall, 020303 mechanical engineering & transports, 020901 industrial engineering & automation, 0203 mechanical engineering, Mechanics of Materials, Disc cutter, Diffusion wear, Tool wear
Abstract

Disc milling is a new technology applied to machine blisk, which can improve the processing efficiency of blisk 3–4 times compared to the existing technology. However, the tool wear rate is very fast because of big milling force and high temperature during disc milling process, so the tool life is seriously reduced. In the study, in order to study how to enhance tool life, the disc milling experiment of blisk is designed. First, the tool life curve is plotted according to the average flank wear growth. Then, the wear morphology of disc cutter is detected with scanning electron microscope. Last, the corresponding mechanisms are analyzed with an X-ray energy-dispersive spectrometer. Experiment results show that the wear differentiation of left/right blade is found because of the overhanging installation way and staggered structure of disc cutter, and 84% channels can be done before disc cutter is blunt. The wear morphology mainly has spalling, crack and flank wear. The corresponding wear mechanisms mainly have adhesion wear, oxidation wear and diffusion wear. The search results will provide experimental support and theoretical basis to how to enhance tool life.

Published
2019

44. Spatiotemporal Characteristics of Radio Frequency Dielectric Barrier Glow Discharge at Atmospheric Pressure

Author

Qiang Chen, Chen Chen, Sun Rui, Zhongwei Liu, Jiazhen Sun, Sen Li, Jie Pan, and Wang Lin

Subjects
Technology, Materials science, QH301-705.5, QC1-999, chemistry.chemical_element, Dielectric, Dielectric barrier discharge, dielectric barrier discharge, law.invention, Electron avalanche, atmospheric pressure, law, General Materials Science, Biology (General), Instrumentation, QD1-999, Fluid Flow and Transfer Processes, Glow discharge, Argon, Atmospheric pressure, Process Chemistry and Technology, Physics, discharge mode, General Engineering, Engineering (General). Civil engineering (General), Cathode, Computer Science Applications, Chemistry, chemistry, Radio frequency, Atomic physics, TA1-2040
Abstract

In this paper, argon was used in radio frequency (13.56 MHz) dielectric barrier discharge (rf-DBD) at atmospheric pressure. The IV curve was recorded after gas breakdown, and discharge photos were captured by ICCD camera. Discharges of α mode and γ mode were observed based on IV curve and ICCD photos. As the existence of negative glow in γ mode, the luminescence intensity of different position of the discharge gap was analyzed. It was found that in the α mode, the electron avalanche occurs from negative to positive and negative glow appeared after the discharge changed into γ mode. In every half cycle, the peak position of negative glow is 13 ± 1 ns later than that of electron avalanche on cathode surface.

Published
2021
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45. Electrochemical Performance of Aluminum Doped Ni1−xAlxCo2O4 Hierarchical Nanostructure: Experimental and Theoretical Study

Author

Sanjay R. Mishra, Ram K. Gupta, Jonghyun Choi, Deepa Guragain, Wang Lin, Xiao Shen, Felio Perez, and Romakanta Bhattarai

Subjects
hydrothermal, Ni1−xAlxCo2O4, Materials science, Band gap, Process Chemistry and Technology, Chemical technology, Doping, Analytical chemistry, Bioengineering, electrochemical, TP1-1185, Electrochemistry, Capacitance, cyclic voltammetry, Cobaltite, chemistry.chemical_compound, Chemistry, chemistry, Electrode, Chemical Engineering (miscellaneous), Density functional theory, the specific capacitance, Current density, QD1-999
Abstract

For electrochemical supercapacitors, nickel cobaltite (NiCo2O4) has emerged as a new energy storage material. The electrocapacitive performance of metal oxides is significantly influenced by their morphology and electrical characteristics. The synthesis route can modulate the morphological structure, while their energy band gaps and defects can vary the electrical properties. In addition to modifying the energy band gap, doping can improve crystal stability and refine grain size, providing much-needed surface area for high specific capacitance. This study evaluates the electrochemical performance of aluminum-doped Ni1−xAlxCo2O4 (0 ≤ x ≤ 0.8) compounds. The Ni1−xAlxCo2O4 samples were synthesized through a hydrothermal method by varying the Al to Ni molar ratio. The physical, morphological, and electrochemical properties of Ni1−xAlxCo2O4 are observed to vary with Al3+ content. A morphological change from urchin-like spheres to nanoplate-like structures with a concomitant increase in the surface area, reaching up to 189 m2/g for x = 0.8, was observed with increasing Al3+ content in Ni1−xAlxCo2O4. The electrochemical performance of Ni1−xAlxCo2O4 as an electrode was assessed in a 3M KOH solution. The high specific capacitance of 512 F/g at a 2 mV/s scan rate, 268 F/g at a current density of 0.5 A/g, and energy density of 12.4 Wh/kg was observed for the x = 0.0 sample, which was reduced upon further Al3+ substitution. The as-synthesized Ni1−xAlxCo2O4 electrode exhibited a maximum energy density of 12.4 W h kg−1 with an outstanding high-power density of approximately 6316.6 W h kg−1 for x = 0.0 and an energy density of 8.7 W h kg−1 with an outstanding high-power density of approximately 6670.9 W h kg−1 for x = 0.6. The capacitance retention of 97% and 108.52% and the Coulombic efficiency of 100% and 99.24% were observed for x = 0.0 and x = 0.8, respectively. First-principles density functional theory (DFT) calculations show that the band-gap energy of Ni1−xAlxCo2O4 remained largely invariant with the Al3+ substitution for low Al3+ content. Although the capacitance performance is reduced upon Al3+ doping, overall, the Al3+ doped Ni1−xAlxCo2O4 displayed good energy, powder density, and retention performance. Thus, Al3+ could be a cost-effective alternative in replacing Ni with the performance trade off.

Published
2021

46. High Flux Reactor Review and Reactivity Control Analysis

Author

Xu Wei, Wang Lin, and Xie Fei

Subjects
High flux, Materials science, Nuclear engineering, Testing equipment, Reactivity (chemistry)
Abstract

For over 60 years, research reactors have provided the world with a versatile tool to test materials and promote irradiation research, as well as to produce radioisotopes for medical treatments. The High Flux Reactor (HFR), as a water moderated and cooled, beryllium-reflected reactor has awarded more attention in recent years. There is a wide range of designs and applications for HFRs that based on their own situation to meet research requirements. For the purpose of reducing the volume and mass of the reactor, as well as ensuring the safety operation, it is necessary to determine the most effective reactivity control scheme, and analyze the corresponding reactivity insertion accidents. This paper is going to investigate typical high flux reactors within the same type with HFETR, summarize general description and characteristics, the uses of the high flux reactor, and reactivity control mechanisms. In addition, the associated reactivity insertion accidents were presented and analyzed. The analysis result will provide some references to further design and construction of high flux reactor.

Published
2021

47. Development of antimicrobial packaging materials by incorporation of gallic acid into Ca2+ crosslinking konjac glucomannan/gellan gum films

Author

Wang Lin, Lin Lishan, Gong Jingni, Jie Pang, Ruo-Jun Mu, Jishuai Sun, Yu Du, and Chunhua Wu

Subjects
0303 health sciences, Materials science, Composite number, Plasticizer, 02 engineering and technology, General Medicine, 021001 nanoscience & nanotechnology, Biochemistry, Gellan gum, Contact angle, 03 medical and health sciences, chemistry.chemical_compound, chemistry, Structural Biology, Thermal stability, Gallic acid, Fourier transform infrared spectroscopy, 0210 nano-technology, Molecular Biology, 030304 developmental biology, Nuclear chemistry, Antibacterial agent
Abstract

Antibacterial films were prepared by incorporating konjac glucomannan (KGM) and gellan gum (GG) as a matrix, glycerin as a plasticizer, CaCl2 as a cross-linking agent, and gallic acid as a natural antibacterial agent. Structure was analyzed by using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Thermal stability of the blends was higher than pure GG, due to Ca2+ crosslinking between GG and KGM. Water contact angle and water vapor permeability were analyzed to determine hydrophobicity of films. Morphological studies revealed that surface compactness and homogeneity of blended films increased with KGM content. The addition of KGM improved the mechanical strength of films significantly. Moreover, KGM improved the release capacity of the blended films, while enhancing antimicrobial activity against Escherichia coli and Staphylococcus aureus. The antioxidant properties of gallic acid embedded in films were measured. Composite films containing 70 wt% KGM (Ca-KG7) displayed the best properties. These findings suggest an alternative method for synthesis of GG-based packaging films with improved properties.

Published
2019

48. Quasi-Single-Layer MoS2 on MoS2/TiO2 Nanoparticles for Anthracene Hydrogenation

Author

Zhendong Pan, Donge Wang, Wang Lin, Zheng Anda, Congxin Wang, Han Jianqiang, Li Jiahe, Wei Qu, Huaijun Ma, and Zhijian Tian

Subjects
Anthracene, chemistry.chemical_compound, Materials science, chemistry, Chemical engineering, Tio2 nanoparticles, Stacking, General Materials Science, Layer (electronics), Single layer, Nanomaterial-based catalyst, Catalysis
Abstract

Developing highly dispersed few stacking layer MoS2 nanocatalysts with high exposure of active sites is still a challenge in improving their catalytic activities. Herein, we report a facile strateg...

Published
2019

49. The microstructure and the mechanical property of AZ91D solidified under GPa-grade high-pressure

Author

Wang Lin, Xu Chang, Zhang Ning, Sun Heng, Lin Xiaoping, and Zhao Shengshi

Subjects
010302 applied physics, Diffraction, Mechanical property, Materials science, Mechanical Engineering, Alloy, 02 engineering and technology, engineering.material, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, 01 natural sciences, Corrosion, Solid solution strengthening, Mechanics of Materials, High pressure, 0103 physical sciences, engineering, General Materials Science, Electronic microscopy, Composite material, 0210 nano-technology
Abstract

High-pressure (2–4 GPa) solidified AZ91D alloy was prepared and the microstructure was investigated by X-ray energy diffraction and scanning electronic microscopy. The room-temperature comp...

Published
2019

50. Preparation and characterization of konjac glucomannan-based bionanocomposite film for active food packaging

Author

Wu Chunhua, Zhiming Yan, Cailing Tong, Wang Lin, Jie Pang, Yu Du, Yuanzhao Li, and Yaqin Hu

Subjects
Materials science, 010304 chemical physics, Hydrogen bond, General Chemical Engineering, Nanoparticle, 04 agricultural and veterinary sciences, General Chemistry, Microstructure, 040401 food science, 01 natural sciences, Chitosan, Matrix (chemical analysis), chemistry.chemical_compound, 0404 agricultural biotechnology, chemistry, Chemical engineering, Rheology, 0103 physical sciences, Fourier transform infrared spectroscopy, Thermal analysis, Food Science
Abstract

Novel active bionanocomposite films were prepared by incorporating chitosan(CS)/gallic acid (GA) nanoparticles (CGNPs) into a konjac glucomannan (KGM) film. CGNPs with a GA loading efficiency of 78 ± 2.3% were obtained through ionotropic gelation method, and they presented a spherical morphology with a diameter range of 80–100 nm. The influences of the CGNPs content on the structural, morphological, mechanical, barrier, thermal and antimicrobial properties of KGM/CGNPs films were discussed. The rheological results of film-forming solutions revealed that the CGNPs interacted with KGM through hydrogen bonds in a bionanocomposite matrix, which was coincidence with the fourier transform infrared spectroscopy, X-ray diffraction and thermal analysis results. The microstructure of the films showed that the introduced 5–10% CGNPs appeared to be homogeneously dispersed within the KGM film matrix, thereby reducing the free volume of the composite matrix, and improving the final bionanocomposite films' mechanical, and barrier properties significantly (p

Published
2019

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