超导金属小粒子的顺磁磁化率

从约化BCS哈密顿量出发, 采用配分函数的路径积分表示方法, 在静态路径近似(SPA)方法下, 考虑准粒子的热涨落以及能级的统计效应对超导纳米粒子的电子磁化率的影响, 计算了弱磁场中的超导金属小粒子的顺磁磁化率, 并做了分析.

用随机矩阵理论计算常规超导金属纳米粒子的磁化率

从约化BCS哈密顿量岀发,考虑随机矩阵理论中高斯正交系综和高斯辛系综所对应的电子能级分布,用配分函数的静态路径积分表示方法,计算了常规超导金属纳米粒子正常超导相变临界区域附近的磁化率,得到了量子效应、奇偶效应、小尺寸效应导致超导金属纳米粒子的磁化率偏离块状超导体的磁化率的性质曲线.

应用氮基超导金属结合剂热等静压金刚石工具

为使氮基超导超硬材料工具能够适应现代制造科技及经济的发展 ,必须首先研究材料元素成分与价态、能量分布及其物相组成、微观结构及其微细变化、显微结构及其缺陷 ,进而控制材料工具形成、结构、性能和应用的内在联系及其变化规律 ,为工具改进韧性和研究预定性能的新型超硬材料工具建立分子设计的基础。

超导金属玻璃Zr_(78)Co_(22)的结晶化动力学研究

综合利用x射线小角散射、广角衍射、场离子显微镜等测量,并结合超导临界温度和显微硬度的观测,研究了金属玻璃Zr_(78)Co_(22)的结构及其结构弛豫和结晶化过程.结果表明,淬态金属玻璃Zr_(78)Co_(22)中存在明显的相分离,其中一个相的组分似乎趋向于纯Zr,另一相的组分则与ZO_4Co 接近.在结构弛豫过程中,主要是拓扑短程序发生了变化,它受成核长大机理支配.当核的数量足够多时,两相均匀一致地长大.

采用CaO精炼获得高纯金属及合金的进展

本文分析了使用 ＣａＯ 坩蜗进行精炼的机制；列举了 ＣａＯ 坩涡精炼过程在电子学、超导母合金等领域的一些成功的例子；总结了在先进结构材料（包括航空和航海仪器铸件、用于航空发动机上的高温合金铸件）方面的应用；展望了ＣａＯ坩埚精炼的前景。总之，ＣａＯ坩埚精炼在高纯金属及合金的发展方面具有良好的应用前景。

Energy Level of Three-Mode Harmonic Oscillator for Coordinate Operators Satisfying Cyclic Commutative Relations Obtained by IEO Method

Eigenvalue-solution to those Hamiltonians involving non-commutative coordinates is not easily obtained. In this paper we apply the invariant eigen-operator （IEO） method to solving the energy spectrmn of the three-mode harmonic oscillator in non-commutative space with the coordinate operators satisfying cyclic commutative relations, [X1, X2] = [X2, X3]=[X3, X1] = iθ, and this method seems effective and concise.

Heat Generation by Electric Current in Normal-Metal-Molecular Quantum Dot-Superconductor System

We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derived and studied in detail. The superconducting lead influences the heat generation significantly. An obvious step appears in Q - eV characteristics and the iocation of this step is related with the phonon frequency ωo. The heat generations exhibit very different behaviour in the condition eV 〈 △ and eV 〉 △ due to different tunneling mechanism. From the study of Q - eVg curves, there is an extra peak as eV 〉 △. The difference in this two cases is also shown in Q - ωo curve, an extra peak emerges as eV 〉 △.

Endoscopic ultrasound-guided choledochoduodenostomies with fully covered self-expandable metallic stents

AIM:To investigate the long-term outcomes of endoscopic ultrasound-guided choledochoduodenostomy(EUS-CDS) with a fully covered self-expandable metallic stent(FCSEMS).METHODS:From April 2009 to August 2010,15 patients with distal malignant biliary obstructions who were candidates for alternative techniques for biliary decompression due to a failed endoscopic retrograde cholangiopancreatography(ERCP) were included.These 15 patients consisted of 8 men and 7 women and had a median age of 61 years(range:30-91 years).The underlying causes of the distal malignant biliary obstruction were pancreatic cancer(n = 9),ampulla of Vater cancer(n = 2),renal cell carcinoma(n = 1),advanced gastric cancer(n = 1),lymphoma(n = 1),and duodenal cancer(n = 1).RESULTS:The technical success rate of EUS-CDS with an FCSEMS was 86.7%(13/15),and functional success was achieved in 100%(13/13) of those cases.In two patients,the EUS-CDS failed because an FCSEMS with a delivery device could not be passed into the common bile duct.The mean duration of stent patency was 264 d.Early adverse events developed in three patients(3/13,23.1%),including self-limited pneumoperitoneum in two patients and cholangitis requiring stent reposition in one patient.During the follow-up period(median:186 d,range:52-388 d),distal stent migration occurred in four patients(4/13,30.8%).In 3 patients,the FCSEMS could be reinserted through the existing choledochoduodenal fistula tract.CONCLUSION:EUS-CDS with an FCSEMS is technically feasible and can lead to effective palliation of distal malignant biliary obstructions after failed ERCP.

Tunneling Conductance in a Normal Metal/Ferromagnetic Superconductor Nano-Junction at a Finite Temperature

In this study, we investigate the tunneling conductance at a finite temperature in a normal metal/ferromagnetic superconductor nano-junction where the ferromagnetic superconductor （FS） is in three different cooper pairing states： spin singlet s-wave pairing （SWP）, spin triplet opposite spin pairing （OSP）, and spin triplet equal spin pairing （ESP） while including Fermi wave mismatch （FWM） and effective mass mismatch （EMM） in two sides of the nano-junction. We find that the conductance shows clearly different behaviors all depending on the symmetries of cooper pairing in a manner that the conductance spectra shows a gap-like structure, two interior dips structure and zero bias peak for SWP, OSP, and ESP, respectively. Also, the effective FS gap （Δeff） is a linear and decreasing function of exchange field. The slope of （Δeff） versus exchange field for OSP is twice the SWP. Thus, we can determine the spin polarization of N/FS nano-junction based on the dependence of （Δeff） to exchange field.

Screening-Dependent Study of Superconductivity in 3d-Transition Metals Binary Alloys Superconductors

In the present article, we report the screening-dependent study of the superconducting state parameters （SSPs）, viz. electron-phonon coupling strength A, Coulomb pseudopotential μ^＊, transition temperature TC, isotope effect exponent a, and effective interaction strength No V of 3d-band transition metals binary alloys superconductors have been made extensively in the present work using a model potential formalism and employing the pseudo-alloy-atom （PAA） model for the first time. Five local field correction functions proposed by Hartree （H）, Taylor （T）, Ichimaru-Utsumi （IU）, Farid et al. （F） and Sarkar et al. （S） are used in the present investigation to study the screening influence on the aforesaid properties. The present results of the SSPs obtained from H-screening are found in qualitative agreement with the available experimental data wherever exist.

Josephson Effect in FS/I/N/I/FS Tunnel Junctions

The Bogoliubov de Gennes equation is applied to the study of coherence effects in the ferromagnetic superconductor/insulator/normal metal/insulator/ferromagnetic/superconductor （FS/I/N/I/FS） junction. We calculated the Josephson current in FS/I/N/I/FS as a function of exchange field in ferromagnetic superconductor, temperature, and normal metal thickness. It is found that the Josephson critical current in FS/I/N/I/FS exhibits oscillations as a function of the length of normal metal. The exchange field always suppresses the Josephson critical current Ip for a parallel configuration of the magnetic moments of two ferromagnetic superconductor （FS） electrodes. In the antiparallel configuration, the Josephson critical current IAv at the minimum values of oscillation increases with the exchange field for strong barrier strength and at low temperatures.

A 150 mV-1.2 V Fully-Integrated DC-DC Converter for Thermal Energy Harvesting

With the increasing use of low voltage portable devices and wireless systems, energy harvesting has become an attractive approach to overcome the problems associated with battery life and power source. Among the different types of microenergy scavengers, the TEG （thermoelectric generators） are one of the most commonly used one. Unfortunately, due to the very small amount of voltage delivered by the TEG, an efficient DC/DC （direct current/direct current） conversion and power management techniques are needed. In this paper, a CMOS （complementary metal oxide semiconductor） fully-integrated DC/DC convener for energy harvesting applications is presented. The startup-voltage of the converter is about 140 mV, the output voltage exceeds 1.5 V, with a 20% power efficiency at least. The architecture for boosting such extremely low voltages is based on an ultra-low-voltage oscillator cross connected to two phase charge pump. The overall circuit does not require any external components and can be fully integrated in a standard CMOS low voltage technology. A test-chip has been designed in UMC （united microelectronics corporation） 180 nm CMOS process.

Advancement in Materials for Supercapacitors

As future improvement to the energy density and power density of supercapacitors relies on the availability of new materials, worldwide research has been undertaken to address this need. The recent advancement in new materials used for fabricating supercapacitors is reviewed in this paper. Among the newly emerged materials covered in this review are the activated graphene, conductive polymers, CNT （carbon nantotubes）, AC （activated carbons）, carbon additives and metal oxides for EDLC （electric double layer capacitors） and pseudocapacitors applications.

Fabrication of YBCO superconducting microarray by sol-gel process using photosensitive metal chelates

We used yttrium acetate, barium acetate, and copper acetate as the starting materials, benzalacetone (BzAcH) as chemical modifier, and methanol (MEOH) as solvent to synthesize a stable fluorine-free YBCO precursor sol. The coated YBCO gel film using this precursor sol exhibited photosensitivity to UV irradiation at a wavelength of 330 nm. After the subsequent exposing, the YBCO gel film showed a decreased solubility in several organic solvents. Based on the photosensitivity of the YBCO/BzAcH gel film, YBCO superconducting microarray with the pitch of 5 μm was fabricated by irradiating the gel film with UV light through a mask, followed by leaching the unirradiated area in a mixture solvent of methanol and n-butyl alcohol with the volume ratio of 1:1. After proper heat treatment the x-ray diffraction result showed that the as-prepared arrays were highly c-axis oriented and with a high T c by this new photosensitive sol-gel process.

A possible new family of unconventional high temperature superconductors

We suggest a new family of Co[Ni-based materials that may host unconventional high temperature superconductivity （high-To）. These materials carry layered square lattices with each layer being formed by vertex-shared transition metal tetrahedra cation-anion complexes. The electronic physics in these materials is determined by the two dimensional layer and is fully attributed to the three near degenerated t2g d-orbitals close to a d7 filling configuration in the d-shell of CoJNi atoms. The electronic structure meets the necessary criteria for unconventional high Tc materials proposed recently by us to unify the two known high-Tc families, cuprates and iron-based superconductors. We predict that they host superconducting states with a d-wave pairing symmetry with Tc potentially higher than those of iron-based superconductors. These materials, if realized, can be a fertile new ground to study strongly correlated electronic Physics and provide decisive evidence for superconducting pairing mechanism.

A possible family of Ni-based high temperature superconductors

We suggest that a family of Ni-based compounds, which contain [Ni_2M_2O]~2à(M = chalcogen) layers with an antiperovskite structure constructed by mixed-anion Ni complexes, Ni M_4O_2, can be potential high temperature superconductors(high-Tc) upon doping or applying pressure. The layer structures have been formed in many other transitional metal compounds such as La_2B_2Se_2O_3(B = Mn, Fe, Co). For the Ni-based compounds, we predict that the parental compounds host collinear antiferromagnetic states similar to those in iron-based high temperature superconductors. The electronic physics near Fermi energy is controlled by two egd-orbitals with completely independent in-plane kinematics. We predict that the superconductivity in this family is characterized by strong competition between extended s-wave and d-wave pairing symmetries.

Advances in single-particle detection for DNA sensing

Rapid, accurate and sensitive detection of particular DNA sequence is critical in fundamental biomedical research and clinical diagnostics. However, conventional approaches for DNA assay often suffer from cumbersome procedures, long analysis time and insufficient sensitivity. Recently, single-particle detection technology has emerged as a powerful tool in the biosensing area due to its significant advantages of ultrahigh sensitivity, low sample-consumption and rapid analysis time. Especially, the introduction of novel nanomaterials has greatly promoted the development of single-particle detection and its applications for DNA sensing. In this review, we summarize the recent advance in single-particle detection strategies for DNA sensing, and focus mainly on metallic nanoparticle-and semiconductor quantum dot-based single-particle detection. We highlight the emerging trends in this field as well.

Conductive Ni3(HITP)2 MOFs thin films for flexible transparent supercapacitors with high rate capability

The flexible transparent supercapacitors have been considered as one of the key energy-storage components to power the smart portable electronic devices.However,it is still a challenge to explore flexible transparent capacitive electrodes with high rate capability.Herein,conductive Ni3(HITP)2(HITP=2,3,6,7,10,11-hexaiminotriphenylene)thin films are adopted as capacitive electrodes in flexible transparent supercapacitors.The Ni3(HITP)2 electrode possesses the excellent optoelectronic property with optical transmittance(T)of 78.4%and sheet resistance(Rs)of 51.3Ωsq-1,remarkable areal capacitance(CA)of 1.63 mF cm^-2and highest scan rate up to 5000 mV s-1.The asymmetric Ni3(HITP)2//PEDOT:PSS supercapacitor(T=61%)yields a high CA of 1.06 mF cm^-2at 3μA cm-2,which maintains 77.4%as the current density increases by 50 folds.The remarkable rate capability is ascribed to the collaborative advantages of low diffusion resistance and high ion accessibility,resulting from the intrinsic conductivity,short oriented pores and large specific areas of Ni3(HITP)2 films.

Intrinsic superconducting transport properties of ultra-thin Fe_(1+y)Te_(0:6)Se_(0:4) microbridges

We investigated the superconducting properties of Fe_(1+y)Te_(0:6)Se_(0:4) single-crystalline microbridges with a width of 4 m and thicknesses ranging from 20.8 to 136.2 nm. The temperature-dependent in-plane resistance of the bridges exhibited a type of metalinsulator transition in the normal state. The critical current density(J_c) of the microbridge with a thickness of 136.2 nm was82.3 kA/cm^2 at 3K and reached 105 kA/cm^2 after extrapolation to T = 0 K. The current versus voltage characteristics of the microbridges showed a Josephson-like behavior with an obvious hysteresis. These results demonstrate the potential application of ultra-thin Fe-based microbridges in superconducting electronic devices such as bolometric detectors.