Influence of Deposition Pressure on Properties of ZnO：Al Films Fabricated by RF Magnetron Sputtering

Transparent conductive aluminum doped zinc oxide（ZnO：Al,AZO） films were prepared on glass substrates by rf（radio frequency） magnetron sputtering from ZnO： 3wt% Al_2O_3 ceramic target. The effect of argon gas pressure（PAr） was investigated with small variations to understand the influence on the electrical, optical and structural properties of the films. Structural examinations using X-ray diffraction（XRD） and scanning electron microscopy（SEM） showed that the ZnO：Al thin films were（002） oriented. The resistivity values were measured by four-point probe with the lowest resistivity of 5.76×10^（-4） Ω？cm（sheet resistance=9.6 Ω/sq. for a thickness=600 nm） obtained at the PAr of 0.3 Pa. The transmittance was achieved from ultravioletvisible（UV-VIS） spectrophotometer, 84% higher than that in the visible region for all AZO thin films. The properties of deposited thin films showed a significant dependence on the PAr.

Electronic and optical properties of lithium niobate under high pressure: A first-principles study

We theoretically study the structural, electronic, and optical properties of lithium niobate under pressure using the plane-wave pseudopotential density functional theory by CASTEP code. It was found that there is a phase transition from the R3 c structure to the Pnma structure at a pressure of 18.7 GPa. The Pnma structure was dynamically stable according to the calculation of phonon dispersion. From the charge density distributions, there exist covalent interactions along the Nb–O bond. The hybridization between O 2p and Nb 4d orbital in the Pnma phase increases with increasing pressure, while it is not changed in the R3c phase. With increasing pressure, the average Nb–O bond length decreases and the Nb–O bond population increases, indicating the increased covalent character between Nb and O atoms under high pressure at Pnma phase, which leads to the increased hybridization between O 2p and Nb 4d orbitals. Furthermore, the optical dielectric function, refractive index, extinction coefficient, electron energy, loss and reflectivity are calculated.

Finite Element Analysis and Experiment on Viscous Warm Pressure Bulging of AZ31B Magnesium Alloy

Aiming at overcoming the low plasticity of magnesium alloy at room temperature, we researched viscous warm pressure bulging（VWPB） of AZ31B magnesium alloy based on the excellent thermal stability of viscous medium under the warm forming condition. The potential improvements of plastic deformation ability and forming quality of AZ31B magnesium alloy are expected with the aid of thermal characteristics of viscous medium. During bulging process the velocity field variation and pressure stress field distribution of viscous medium are observed at different temperatures through which the effect of temperature on the mechanical property of viscous medium and AZ31B magnesium alloy are analyzed. The results show that the formability of AZ31B magnesium alloy increases first and then decreases as the temperature increases and it is the best at 200 ℃. On the other hand, the viscous medium which can build non-uniform pressure stress field also exhibits a good flow property at elevated temperature, and it is helpful to improving the formability of AZ31B magnesium alloy.

Effect of Oxygen Partial Pressure on Epitaxial Growth and Properties of Laser-Ablated AZO Thin Films

Al-doped ZnO（AZO） thin films were grown on c-sapphire substrates by laser ablation under different oxygen partial pressures（P_（O2））.The effect of P_（O2） on the crystal structure,preferred orientation as well as the electrical and optical properties of the films was investigated.The structure characterizations indicated that the as-grown films were single-phased with a wurtzite ZnO structure,showing a significant c-axis orientation.The films were well crystallized and exhibited better crystallinity and denser texture when deposited at higher P_（O2）.At the optimum oxygen partial pressures of 10- 15 Pa,the AZO thin films were epitaxially grown on c-sapphire substrates with the（0001） plane parallel to the substrate surface,i e,the epitaxial relationship was AZO（000 1） // A1_2O_3（000 1）.With increasing P_（O2）,the value of Hall carrier mobility was increased remarkably while that of carrier concentration was decreased slightly,which led to an enhancement in electrical conductivity of the AZO thin films.All the films were highly transparent with an optical transmittance higher than 85%.

Studies of electrical properties of rocks under high temperature and pressure

Studies of the rocks′ electrical properties under high temperature and pressure have found favors in the geophysicist′s eyes, because those studies are becoming to be the important methods to understand the earth′s interior materials, their migration and evolution. This article introduces the development and significant of those studies from the measurements, instruments and affections, etc .

Structural and Transport Properties of the Weyl Semimetal NbAs at High Pressure

We perform a series of high-pressure synchrotron x-ray diffraction （XRD） and resistance measurements on the Weyl semimetal NbAs. The crystal structure remains stable up to 26 GPa according to the powder XRD data. The resistance of NbAs single crystal increases monotonically with pressure at low temperature. Up to 20 GPa, no superconducting transition is observed down to 0.3 K. These results show that the Weyl semimetal phase is robust in NbAs, and applying pressure may not be a good way to obtain a topological superconductor from Weyl semimetal NbAs.

Properties of Liquid Nickel along Melting Lines under High Pressure

We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting line indicate that the configuration change along melting lines decreases with increasing pressure. The calculated diffusion coefficients and viscosity by using entropy-scaling laws with modified parameters and ideal parameters are compared with those extracted from mean-square displacement or the Stokes-Einstein relation. The results suggest that the entropy-scaling laws hold well for coefficients and viscosity increase moderately with liquid nickel under high-pressure conditions, and the diffusion pressure along melting lines.

Dynamic rock tests using split Hopkinson （Kolsky） bar system - A review

Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsl^j bar systems, which include both split Hopkinson pressure bar （SHPB） and split Hopkinson tension bar （SHTB） systems. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system. This review aims to fully describe and critically assess the detailed procedures and principles of tech- niques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined, followed by the key loading techniques that are useful for dynamic rock tests with SHPB （i.e. pulse shaping, momentum-trap and multi-axial loading techniques）. Various measurement techniques for rock tests in SHPB （i.e. X-ray micro computed tomography （CT）, laser gap gauge （LGG）, digital image corre- lation （DIC）, Moir~ method, caustics method, photoelastic coating method, dynamic infrared thermog- raphy） are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements （i.e. dynamic compression, tension, bending and shear tests）, dynamic fracture measurements （i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity）, and dy- namic techniques for studying the influences of temperature and pore water.

Comparison of corneal biomechanical properties in normal tension glaucoma patients with different visual field progression speed

AIM：To compare the corneal biomechanical properties difference by ocular response analyzer（ORA） in normal tension glaucoma（NTG） patients with different visual field（VF） progression speed. METHODS：NTG patients with well-controlled Goldmann applanation tonometer（GAT） who routinely consulted Kitasato University Hospital Glaucoma Department between January 2010 and February 2014 were enrolled.GAT and ORA parameters including corneal compensated intraocular pressure（lOPcc）,Goldmann estimated intraocular pressure（lOPg）,corneal hysteresis（CH）,corneal resistance factor（CRF） were recorded.VF was tested by Swedish interactive threshold algorithm（SITA）-standard 30-2 fields.All patients underwent VF measurement regularly and GAT did not exceed 15 mm Hg at any time during the 3y follow up.Patients were divided into four groups according to VF change over 3y,and ORA findings were compared between the upper 25th percentile group（slow progression group） and the lower 25th percentile group（rapid progression group）.RESULTS：Eighty-two eyes of 56 patients were studied.There were 21 eyes（21 patients） each in rapid and slow progression groups respectively.GAT,lOPcc,lOPg,CH,CRF were 12.1＋1.4 mm Hg,15.8±1.8 mm Hg,12.8±2.0 mm Hg,8.4±1.1 mm Hg,7.9±1.3 mm Hg respectively in rapid progression group and 11.5±1.3 mm Hg,13.5±2.1 mm Hg,11.2±1.6 mm Hg,9.3±1.1 mm Hg,8.2±0.9 mm Hg respectively in slow progression group（P=0.214,〈0.001,0.007,0.017,0.413,respectively）.In bivariate correlation analysis,lOPcc,lOPcc-GAT and CH were significant correlated with m△MD（r =-0.292,-0.312,0.228 respectively,P =0.008,0.004,0.039 respectively）.CONCLUSION：Relatively rapid VF progression occurred in NTG patients whose lOPcc are rather high,CH are rather low and the difference between lOPcc and GAT are relatively large.Higher lOPcc and lower CH are associated with VF progression in NTG patients.This study suggests that GAT measures might underestimate the IOP in such patients.

Evaluation of gas wettability and its effects on fluid distribution and fluid flow in porous media

The special gas wettability phenomenon of reservoir rocks has been recognized by more and more researchers.It has a significant effect on efficient development of unconventional reservoirs.First,based on the preferentially gas-covered ability and surface free energy changes,definition and evaluation methods have been established.Second,a method for altering rock wettability and its mechanisms have been studied,surface oriented phenomena of functional groups with low surface energy are the fundamental reason for gas wettability alteration of rock.Third,the effect of gas wettability on the surface energy,electrical properties and dilatability are investigated.Last,the effects of gas wettability on capillary pressure,oil/gas/water distribution and flow are investigated with capillary tubes and etchedglass network models.The gas wettability theory of reservoir rocks has been initially established,which provides theoretical support for the efficient production of unconventional reservoirs and has great significance.

Dynamic Mechanical Characteristics and Damage Evolution Model of Granite

By using the technique of the split Hopkinson pressure bar（ SHPB）,impact tests at different stress wavelengths（ 0. 8-2. 0 m） and strain rates（ 20-120 s^（-1）） were conducted to study the dynamic mechanical properties and damage accumulation evolution lawof granite. Test results showthat the dynamic compressive strength and strain rate of granite have a significantly exponential correlation;the relationship between peak strain and strain rate is approximately linear,and the increase of wavelengths generally makes the level of peak strain uplift. The multiple-impacts test at a lowstrain rate indicates that at the same wavelength,the cumulative damage of granite shows an exponential increasing form with the increase of strain rate; when keeping the increase of strain rate constant and increasing the stress wavelength,the damage accumulation effect of granite is intensified and still shows an exponential increasing form; under the effect of multiple impacts,the damage development trend of granite is similar overall,but the increase rate is accelerating. Therefore the damage evolution model was established on the basis of the exponential function while the physical meaning of parameters in the model was determined. The model can reflect the effect of the wave parameters and multiple impacts. The validity of the model and the physical meaning of the parameters were verified by the test,which further offer a reference for correlational research and engineering application for the granite.

Forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by CNTs based on MCST with temperature-variable material properties

In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.

Effect of nitrogen pressure on optical properties and microstructure of diamond-like carbon films grown by pulsed laser deposition

The effect of nitrogen pressure on optical properties of hydrogen-free diamond-like carbon (DLC) films deposited by pulsed laser ablation graphite in different background pressures of nitrogen is reported. By varying nitrogen pressures from 0.05 to 15.00 Pa, the photoluminescence is gradually increased and optical transmittance is gradually decreased. Atomic force microscopy (AFM) is used to observe the surface morphology of the DLC films. The results indicate that the surface becomes unsmoothed and there are some globose particles on the films surface with the rise of nitrogen pressures. The microstructure of the films is characterized using Raman spectroscopy.

A Review on the Regulation of Magnetic Transitions and the Related Magnetocaloric Properties in Ni-Mn-Co-Sn Alloys

In Ni-Mn-X（X=In,Sn,Sb） ferromagnetic shape memory alloys,a ferromagnetic transition from paramagnetic to ferromagnetic austenite and a martensitic transformation from ferromagnetic austenite to weak magnetic martensite occur in some particular composition ranges,in which abundant physical properties have been observed by the abrupt change of magnetization and resistivity around their transition temperatures in these alloys.Therefore,tuning the martensitic transformation temperature（TM） and enlarging the workingtemperature interval for Ni-Mn-X（X=In,Sn,Sb） alloys,are of great importance.In the present paper,we will focus on the effect of external factors,including pre-deformation,annealing,and high pressure annealing,on the magnetic transitions and the related magnetocaloric properties in Ni-Mn-Co-Sn ferromagnetic shape memory alloys.Our approaches and the main results in this particular field will be reviewed.