Tuning of band gaps for a two-dimensional piezoelectric phononic crystal with a rectangular lattice

In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic-electric coupling. The generalized eigenvalue equation is obtained by the relation of the mechanic and electric fields as well as the Bloch-Floquet theorem. The band structures of both the in-plane and anti-plane modes are calculated for a rectangular lattice by the planewave expansion method. The effects of the lattice constant ratio and the piezoelectricity with different filling fractions are analyzed. The results show that the largest gap width is not always obtained for a square lattice. In some situations, a rectangular lattice may generate larger gaps. The band gap characteristics are influenced obviously by the piezoelectricity with the larger lattice constant ratios and the filling fractions.

Band Gap Opening of Graphene by Noncovalent π-π Interaction with Porphyrins

Graphene has been recognized as a promising 2D material with many new properties. However, pristine graphene is gapless which hinders its direct application towards graphene-based semiconducting devices. Recently, various ways have been proposed to overcome this problem. In this study, we report a robust method to open a gap in graphene via noncovalent functionalization with porphyrin molecules. Two type of porphyrins, namely, iron protoporphyrin (FePP) and zinc protoporphryin (ZnPP) were independently physisorbed on graphene grown on nickel by chemical vapour deposition (CVD) resulting in a bandgap opening in graphene. Using a statistical analysis of scanning tunneling spectroscopy (STS) measurements, we demonstrated that the magnitude of the band gap depends on the type of deposited porphyrin molecule.The π-π stacking of FePP on graphene yielded a considerably larger band gap value (0.45 eV) than physisorbed ZnPP (0.23 eV). We proposed that the origin of different band gap value is governed due to the metallic character of the respective porphyrin.

ASTM E1268-19带状组织评定方法研究

介绍了美标ASTM E1268-19显微组织带状物级别或取向度的评级方法。采用ASTM E1268-19与GB/T13299—91试验方法,评定了热轧板卷试样的珠光体带状组织,并对ASTM E1268标准方法中检测视场的影响因素进行了分析。结果表明:增加检测视场数有利于提高定量评定结果的准确度;对于带状严重的组织,因其平行测量线容易全部落入单相组织内部或外部,对带状等级BR(banding rate)值的测量结果影响较大,针对此类情况,有必要增加检测视场数或测量线的数量,以提高BR的检测精度。

The Dust Comportment in the Latitudinal Band 10°North - 20°North in Africa: Emission and Deposition

The three measurement periods: the TOMS Nimbus-7 TOMSN7L3 v008 from 1978 to 1993, the TOMS EP TOMSEPL3 v008 from 1996 to 2005 and the OMI OMTO3d v003 from 2004 to 2008 have allowed the presence of dust to be observed in the 10°North to 20°North latitudinal band (10 - 20 band) of Africa. The 10 - 20 band has a permanent dust presence. The AERONET data show AOD peaks exceeding 2 in Senegal and Niger (on an AOD scale). The statistical study reveals intra-annual relationships in deposition. In Senegal, a significant deposition is observed.

A Narrow Band Chandra X-ray Analysis of SNR 3C 391

We present narrow-band and equivalent width （EW） images of the thermal composite supernova remnant （SNR） 3C 391 in the X-ray emission lines of Mg, Si and S using the Chandra ACIS Observational data. The EW images reveal the spatial distribution of the emission of the metal species Mg, Si and S in the remnant. They have a clumpy structure similar to that seen in the broadband diffuse emission, suggesting that they are largely of interstellar origin. We find an interesting finger-like feature protruding outside the southwestern radio border of the remnant, somewhat similar to the jet-like Si structure found in the famous SNR Cas A. This feature may possibly be the debris of the jet of ejecta from an asymmetrical supernova explosion of a massive progenitor star.

G6PD缺乏红细胞膜Band3蛋白阴离子转运功能的改变

目的 :探讨葡萄糖 - 6 -磷酸脱氢酶 (G6PD)缺乏红细胞膜Band3蛋白阴离子转运功能的改变及影响因素 .方法 :利用测定细胞在等渗氯化铵溶液中的溶血t1/2 来揭示正常与异常红细胞阴离子转运功能的改变及巯基还原剂的修复 .结果 :G6PD缺乏红细胞 ,Band3蛋白阴离子转运活性较正常对照明显减弱 ,而DTT或巯基乙醇可恢复其阴离子转运活性 .结论 :氧化通过修饰G6PD缺乏红细胞膜蛋白巯基来降低阴离子转运活性 ,这可能成为红细胞溶血的一个重要机制 。

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 ofⅢ-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 ofⅢ-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)andⅢ-N(Ⅲ=Al,Ga,In,Tl)are found to be very different from those of otherⅢ-Ⅴ binary compounds.

Reservoir quality of fluvial sandstone reservoirs in salt-walled mini- basins： an example from the Seagull field, Central Graben, North Sea, UK

The Triassic fluvial sandstones of the Skagerrak Formation were deposited in a series of salt-walled mini-basins and act as important hydrocarbon reservoirs for several high-pressure, high-temperature（HPHT） fields in the Central Graben, North Sea. The HPHT reservoirs exhibit excellent reservoir quality considering their depth of burial and hence have been of high interest for hydrocarbon exploration. This research uses a multidisciplinary approach to assess the Skagerrak Formation fluvial reservoir quality from the Seagull field incorporating core analysis, petrography, electron microscopy, XRD analysis, fluid inclusion appraisal and burial history modelling. Halokinesis and salt withdrawal at the margin of the saltwalled mini-basin induced early disaggregation bands and fractures at shallow burial and led to increased influx of meteoric water and clay mineral infiltration from overlying sedimentation. The density of disaggregation bands correlates with the occurrence and magnitude of pore-filling authigenic clay minerals, concentrated along the margin of the saltwalled mini-basin. The fluvial channel sandstones of the Skagerrak Formation are subject to strong intra-basinal spatial reservoir quality variations despite diagenesis and low vertical effective stress having played a favourable role in arresting porosity loss.

First-principles study of the co-effect of carbon doping and oxygen vacancies in ZnO photocatalyst

Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnO_(x)C_(0.0625)(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity.

The electronic structure of Nb＿3Al/Nb＿3Sn, a new test case for flat/steep band model of superconductivity

In this work, we choose Nb3Al/Nb3Sn as a new test case for flat/steep band model of superconductivity. Based on the density functional theory in the generalized gradient approximation, the electronic structure of Nb3Al/ Nb3Sn has been studied. The obtained results agree well with those of the earlier studies and show clearly fiat bands around the Fermi level. The steep bands as characterized in this work locate around the M point in the first Brillouin zone. The obtained results reveal that Nb3Al/Nb3Sn fits more to the ＂Flat/steep＂ band model than to the van-Hove singularity scenario. The fiat/steep band condition for superconductivity implies a different thermodynamic behavior of superconductors other than that predicted from the conventional BCS theory. This observation sets up an indicator for selecting a suitable superconductor when its large-scale industrial use is needed, for example, in superconducting maglev system or ITER project.

Decay Study of the Neutron-Rich Nucleus ^(175)Er

The decay of the neutron-rich erbium isotope 175Er is studied by using the reaction176Yb（n,2p）175Er.A partial decay scheme is proposed on the basis of X-γ and γ-γ coincidencemeasurements,taking into account eight observed gamma rays.A ground rotational band is as-signed to 175Tm.Some systematic behaviors of 1/2+[411] ground rotational bands in odd-Athulium are described.The experimental and calculated decoupling parameters of these bandsare compared.

一种应用于移动通信的新型六频段天线

提出了一种新型六频段天线。该天线根据对称偶极子的结构,采用带有衍生臂的片状臂作为偶极子的两个极,其中每个极由对称L形矩形弯折长臂和宽边矩形末端半圆形臂构成。通过HFSS软件仿真优化,其能同时工作在CDMA/GSM/DCS/PCS/UMTS/WLAN6个频段上,且具有较好的辐射方向性,能满足移动通信对多频段天线的需求。并且还具有外形轮廓平薄,重量轻巧,易于调校的特点,在移动通信领域有很广泛的应用空间。

Development of DWDM Filter Manufacture

DWDM technology is developing rapidly. Thin film narrow bandpass filter plays an important role in this field. This article presents some achievements in developing the DWDM narrow bandpass filters and also describes the results achieved by us.

Global photometric analysis of Galactic HII regions

Total infrared fluxes are estimated for 99 HII regions around massive stars. The following wavebands have been used for the analysis： 8 and 24 μm, based on data from the Spitzer Space Telescope （IRAC and MIPS, respectively）; 70, 160, 250, 350 and 500 μm, based on data from the Herschel Space Observatory （PACS and SPIRE）. The estimated fluxes are used to evaluate the polycyclic aromatic hy- drocarbon （PAH） mass fraction （qPAH） and the intensity of ultraviolet emission in the studied objects. It is shown that the PAH mass fraction, qPAH, is much lower in these objects than the average Galactic value, implying effective destruction of aromatic particles in HII regions. Estimated radiation field inten- sities （U） are close to those derived for extragalactic HII complexes. Color indices [F24/F8], [F70/F24], [F160/F24] and [F160/F70] are compared to criteria proposed to distinguish between regions of ionized hydrogen and planetary nebulae. Also, we relate our results to analogous color indices for extragalactic complexes of ionized hydrogen.

Refraction characteristics of phononic crystals

Some of the most interesting refraction prop- erties of phononic crystals are revealed by examining the anti-plane shear waves in doubly periodic elastic composites with unit cells containing rectangular and/or elliptical multi- inclusions. The corresponding band structure, group velocity, and energy-flux vector are calculated using a powerful mixed variational method that accurately and efficiently yields all the field quantities over multiple frequency pass-bands. The background matrix and the inclusions can be anisotropic, each having distinct elastic moduli and mass densities. Equifrequency contours and energy-flux vectors are read- ily calculated as functions of the wave-vector components. By superimposing the energy-flux vectors on equifrequency contours in the plane of the wave-vector components, and supplementing this with a three-dimensional graph of the corresponding frequency surface, a wealth of information is extracted essentially at a glance. This way it is shown that a composite with even a simple square unit cell con- taining a central circular inclusion can display negative or positive energy and phase velocity refractions, or simply performs a harmonic vibration （standing wave）, depending on the frequency and the wave-vector. Moreover, that the same composite when interfaced with a suitable homoge- neous solid can display： （1） negative refraction with negative phase velocity refraction; （2） negative refraction with pos- itive phase velocity refraction; （3） positive refraction with negative phase velocity refraction; （4） positive refraction with positive phase velocity refraction; or even （5） completereflection with no energy transmission, depending on the fre- quency, and direction and the wavelength of the plane-wave that is incident from the homogeneous solid to the interface. For elliptical and rectangular inclusion geometries, analyti- cal expressions are given for the key calculation quantities. Expressions for displacement, velocity, linear momentum, strain, and stress components, as well as the energy-flux and group velocity components are given in series form. The general results are illustrated for rectangular unit cells, one with two and the other with four inclusions, although any number of inclusions can be considered. The energy-flux and the accompanying phase velocity refractions at an inter- face with a homogeneous solid are demonstrated. Finally, by comparing the results of the present solution method with those obtained using the Rayleigh quotient and, for the lay- ered case, with the exact solutions, the remarkable accuracy and the convergence rate of the present solution method are demonstrated.

Design and Analysis of 120-μm Core Rod-Type Photonic Crystal Fiber for High Power 1.5-μm Band Amplifier

We report the design and analysis of a rod-type photonic crystal fiber with Er-Yb co-doped for the high power 1.5-μm band amplifier.The fiber structure is designed to be the 120-μm extreme large core diameter,300-μm inner cladding diameter,and 1.5-mm outer cladding diameter that ensure the single mode output during high power amplification.Both the continuous wave(CW) and pulsed amplification characteristics are analyzed based on the exact modeling and simulation under the designed geometry.The 4-mJ pulse energy and 400-kW peak power are obtained in theory,so the 1.5-μm band amplifier that achieves milojoule level pulse energy meanwhile keeping single mode is firstly designed.

BAND STRUCTURE OF ORGANIC SUPERCONDUCTOR β-(BEDT-TTF)_2I_3

Ⅰ. INTRODUCTIONThirty organic superconductors have been synthesized since the first organic superconductor （TMTSF）2PF6 was synthesized in 1980. According to their donors, they can be classified into four families, TMTSF, BEDT-TTF, DMET and Ni（dmit）2. The BEDT-TTF is the largest one in which there are many kinds of compounds with Tc

Radio Observations of Sgr B2

The 13C0 (J 1 - 0) map of the molecular cloud Sgr B2 reveals that the mass center of the molecular cloud nucleus does not coincide with that of compact HII regions which are likely to be the outcome of a shock on the cloud. We find evidence of cloud contraction probably resulting from cloud-cloud collision at subsonic speed.

A NOVEL APPROACH TO TESTING THE DYNAMIC SHEAR RESPONSE OF Ti-6Al-4V

Modifications were made on the traditional split Hopkinson pressure bar （SHPB） system to conduct dynamic shear tests. The shear response of Ti-6A1-4V was acquired at a shear strain rate of 104 s-1 by using this modified apparatus. The geometry as well as the clamping mode of the double-notch specimen was optimized by commercial FEM software ABAQUS, and the feasibility of the experiment set-up was validated. A shear stress calibration coeff^cient of γT = 1.03 and a shear strain calibration coefficient of γT- = 0.50 were obtained.We have employed high- speed photography to record the deformation process, especially the initiation and propagation of adiabatic shear band （ASB）, during the dynamic shear test. The frames show that the time duration from ASB initiation to its completion is less than 2 μs, from which we can estimate that the propagation speed of ASB within Ti-6A1-4V is more than 1250 m/s under such loading conditions. The temperature rise within ASB is also estimated to be △T2 ≈ 1460 ℃ based on energy balance. Such high temperature has led to softening of the material within the ASBs, and has intensified the shear localization and finally resulted in fracture of the material.

The characteristic periodicity analysis of the radio flux variability of quasar PKS 1510-089

A wavelet analysis method is introduced to study the possible periods of PKS 1510-089 in radio bands. By compiling the radio light curve of PKS 1510-089 at frequencies of 22 and 37 GHz from 1990 to 2005, and using the wavelet analysis method, the evidence of quasi-periodic activity in PKS 1510-089 was obtained. The results indicate that: (1) There are two stable outburst periods of T1=(1.80±0.06) yr and T2= (0.90±0.07) yr presenting in the isoplethal map of PKS 1510-089 at the radio band 37 GHz; (2) there is an outburst period of T1=(1.80±0.06) yr presenting at the radio band 22 GHz; (3) by the continuum of the isograms map, we find the primary period of PKS 1510-089 is T1=(1.80±0.06) yr, and the period of T2= (0.90±0.07) yr may be the half period. The above results are consistent with the reports of Xie et al. (2004, 2005, 2008), Wu et al. (2005) and Liu & Fan (2007), using the other methods. We can expect that the next burst will be in January 2011.