Measurement of Binding Force between Microtubule-Associated Protein and Microtubule

Microtubule-associated proteins （MAPs） are important proteins in cells. They can regulate the organization, dynamics and function of microtubules. We measure the binding force between microtubule and a new plant MAP, i.e. AtMAP65-1, by dual-optical tweezers. The force is obtained to be 14.6 ± 3.5 pN from the data statistics and analysis. This force measurement is helpful to understand the function and mechanism of MAPs from the mechanical point of view and lays the groundwork for future measurements of the mechanical properties of other biological macro-molecules.

A New Mechanism Responsible for the Enhancement of Local Electric Field on the Surface of Emitting Carbon Nanotubes

Aligned carbon nanotube (CNRT) films exhibit excellent electron emission properties at very low fields. This has been attributed to the high aspect ratio of CNTs, I.e. Their emitting surface can have high local field due to geometrical enhancement. It is found that a new mechanism can be responsible for the enhancement of the local field on the emitting surface of CNTs. This results from the space charge in the vacuum gap, which is readily generated due to the high emission current density of CNTs. Details are given of both experimental and theoretical studies of this effect. The mechanism also accounts for the distinct nonlinearity in Fowler-Nordheim plots often observed with CNTs. The implication of the technical application of our findings is also included.

Transmittance and Refractive Index of the Lanthanum Strontium Aluminium Tantalum Oxide Crystal

The lanthanum strontium aluminium tantalum oxide(LSAT)crystal is grown by means of a floating or pulling method.Its optical transmittance,refractive indices in visible and near-infrared areas and its dispersion curve are reported.The transparence range of LSAT is from 0.45 to 4.2μm and its refractive index is 2.0244.

Analysis of Step Etching on SrTiO_(3) Substrates for the Step-Edge YBCO Josephson Junctions

A way to determine some important etching parameters in the step fabrication for highTc step-edge Josephson junctions is described based on an analysis of the dynamics of the etching process.The optimum thickness of the etch mask is defined with negligible recession of the mask edge during the etch.Under this condition,the equilibrium angle of the steps etched on the SrTiO_(3)(STO)substrate with an Nb mask has been calculated to be about 76°.With optimized mask thickness,its sharp sidewall and straight edge,high-quality steps on STO substrates with step height from 200-300 nm and step angle above 70°are made.Josephson junctions and dc-SQUIDs with high reproducibility and less parameter scatter are obtained on the step substrates.

Effects of Spherical Aberration on Optical Trapping Forces for Rayleigh Particles

The Trapping force on Rayleigh particles in an optical tweezers system with an oil immersion objective is calculated by an electromagnetic model.The results indicate that the stability of particles trapped will be affected by spherical aberration,which is caused by refractive difference between objective oil and water solution,when the specimen manipulated is suspended in a water solution.The trapping force and depth of potential well will decrease and the minimum of laser power for ensuring the stability of particles trapped will increase with the enhancing trapping depth.

Superconducting Properties of MgB_(2) Prepared by High Pressure and Ambient Pressure

The new superconductor MgB_(2) has been prepared by two ways: high pressure and ambient pressure synthesis. Their superconducting properties were measured and compared. It is found that the sample prepared by high pressure is much denser than that prepared under ambient pressure. Accordingly the high pressure sample has a very narrow transition width and a much higher bulk critical current density.

Power Law Behavior of the Zero Bias Tunneling Conductance:the New Evidence for d-Wave Symmetry

We report temperature-dependent behavior of the zero bias tunneling conductance(ZBTC),derived from tun neling spectroscopies on as-grown Bi_(2)Sr_(2)CaCu_(2)O_(8+δ)(Bi2212)single crystals taken with evaporated Zn and Pb planar junctions.At Tc the measured ZBTC shows a kink which gives an in situ measure of the superconducting transition temperature(T_(c)).Below T_(c),the T^(2)dependence of the ZBTC has been observed repeatedly as a new evidence of the d-wave symmetry in Bi2212.

Upper Critical Field and Irreversibility Line Determined by Transport Measurement of the New Superconductor MgB_(2)

Resistive transitions of the new superconductor MgB_(2) are carried out under magnetic fields from 0 to 8 T.It is found that the irreversibility field Hirr(T)and the upper critical field Hc2(T)obtained are very close to those determined in the magnetic measurement.By using the Arrhenius activation lawρ=ρ0exp(-U/kBT),the activation barrier U has been determined by the low dissipation part of R(T)curves.It is found that U■kBT manifests a very weak thermal activation and thermal fluctuation effect.This may further indicate that the flux dynamics near Hirr(T)is induced by strong quantum fluctuation and tunneling of vortices.

Enhancement of Curie Temperature and Magnetoresistance in the Perovskit es La_(2/3)Ca_(1/_3)Mn_(1-x)Si_(x)O_(3)

Structural,magnetic,and transport properties of perovskite La_(2/3)Ca_(1/_3)Mn_(1-x)Si_(x)O_(3)(x=0,0.025,0.05)have been studied.The incorporation of Si decreases the overall resistivity,but obviously increases the Curie temperature(TC),metal-insulator transition temperature(TP),and the magnetoresistance ratio MR(defined as[R(0)-R(H)]/R(0))near room temperature.Comparing with La_(2/3)Ca_(1/_3)MnO_(3)the TC,TP,and MR of the sample with x=0.05 increase by 30,45K,and 20%,respectively.Lattice effects may play a more important role than the magnetic dilution in the case of low Si substitution.

Mie Potential and Equation of State of Zr_(48)Nb_(8)Cu_(14)Ni_(12)Be_(18) Bulk Metallic Glass

The linear expansion of Zr_(48)Nb_(8)Cu_(14)Ni_(12)Be_(18) bulk metallic glass(BMG)with excellent glass forming ability and high thermal stability is investigated by a dilatometry method.The average expansion coefficient is α TG=1.04 × 10^(-5) K^(-1)(300-656 K)for the BMG and α TG=1.11 × 10^(-5) K^(-1)(356~890 K)for the crystallized alloy.The Mie potential as well as the equation of state of the BMG and its corresponding crystallized state are determined from the thermal expansion and ultrasonic data,and the differences among them are phenomenologically explained.

Structure Effect of Squarylium Cyanine Dyes on Third-Order Optical Nonlinearities in Ground and Excited States

A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing.For the ground state,the molecular hyperpolarizabilityγg increases with the red-shift of the absorption peakλabmax,of the squaraine with different substituents,whereas for the excited-state molecular hyperpolarizabilityγe,the nonlinear enhancementγe/γg decreases,which may indicate that in the excited state the electron accepting-donating ability of different substituents changes in the reverse order compared with the order in the ground state.

Optical properties of the direct-coupled Y-branch filters by using photonic crystal slabs

We fabricated a new type of two-dimensional photonic crystal slab filter. The resonant cavities were directly put into the waveguide arms. The optical transmissions of the filters were measured and the results show that the optimized two-channel filters give good intensity distribution at the output ports of the waveguide. A minimum wavelength spacing of 5 nm of the filter outputs is realized by accurately controlling the size of the resonant cavities.

Fabrication of Colloidal Photonic Crystals with Heterostructure by Spin-Coating Method

Colloidal photonic crystal heterostructures, composed of two opaline photonic crystal films of silica spheres with different diameters, are fabricated by a two-step spin-coating method. Scanning electron microscopy （SEM） and UV-vis spectrophotometer are used to characterize the heterostructures. The SEM images show good ordering of the two-layer colloidal crystals constituting the heterostructures. The transmission spectra measured from the （111） plane in the heterostructure show that the composite colloidal photonic crystals have double photonic stop bands. Furthermore, when the sizes of the silica spheres used for fabricating the composite photonic crystal are slightly different, the transmission spectrum shows that the composite photonic crystals have more extended bandgap than that of the individual photonic crystals due to partial overlapping of its two photonic stop bands.

Infrared Absorption of Phase Separated La0.67-xPrxCa0.33MnO3

Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the Mn-O bond, together with a shift of peak position, is observed below the Curie temperature. These features weaken and even disappear as the samples are warmed up to the Curie temperature, which indicates that this anomaly may be a result of phase separation in the compounds.

Detection of microarray protein biomolecules by oblique-incidence reflectivity difference technique without labelling agents

This paper reports that the detection to the protein in microarray format is carried out by oblique-incidence reflectivity difference （OI-RD） analysis without any labelling agents. The OI-RD intensities not only depend on the protein structure, but also vary with the protein concentration. The results indicate that this method should have potential application in detection of biochemical processes. The high throughout and in situ detection can be achieved by this method with further improving of the experimental system.

Measurement of R Line Fluorescence in Ruby Using the Diamond Anvil Cell at Low Temperature

Using our custom-built high-pressure cryostat we have performed the measurements of the R line fluorescence of ruby in the diamond anvil cell from room temperature down to 90K.The maximum pressure was 11.1 GPa.By computer curve fitting,different equations have been found for functions of wavenumber versus temperature between ambient pressure and 2.7 GPa.The changes of the shape and linewidth of R lines were observed.

Observation of Rydberg Series in Sodium Vapour by Two-Photon Resonant Nondegenerate Four-Wave Mixing

We apply two-photon resonant nondegenerate four-wave mixing with a resonant intermediate state for the obser- vation of Rydberg states in sodium vapour. The broadening and shift of the sodium 3S- 11D transition perturbed by argon are investigated. This technique can achieve Doppler-free resolution of narrow spectral structures of Rydberg levels if lasers with narrow bandwidths are employed.

Strong Quantum Fluctuation of Vortices in Bulk Samples of the New Superconductor MgB_(2)

By using transport and magnetic measurement,the upper critical field H_(c2)(T)and the irreversibility line Hirr(T)has been determined.A big separation between H_(c2)(0)and Hirr(0)has been found showing the existence of a quantum vortex liquid state induced by quantum fluctuation of vortices in the new superconductor MgB_(2).Further investigation on the magnetic relaxation shows that both the quantum tunneling and the thermally activated flux creep depends weakly on temperature.However,when the melting field Hirr is approached,a drastic rise of the relaxation rate is observed.This may indicate that the melting of the vortex matter at a finite temperature is also induced by the quantum fluctuation of vortices.

Effects of Current-Injection on Superconductivity of YBa_2Cu_3O_(7-δ) in La_(0.8)Te_(0.2)MnO_3/YBa_2Cu_3O_(7-δ)Bilayer

La_(0.8)Te_(0.2)MnO_3/YBa_2Cu_3O_(7-δ)(F/S)bilayers were fabricated by electrophoretic technique. The thickness of La_(0.8)Te_(0.2)MnO_3 is ~70 μm, the dimensions of YBa_2Cu_3O_(7-δ) superconductor are 5 mm×10 mm×0.5 mm. The image of cross-sectional profile was measured by scanning electron microscopy (SEM). Standard four-probe method was used for YBa_2Cu_3O_(7-δ) superconducting resistance measurements. Either 1 mA current is injected from S layer to F layer ((+I_(inj))) or from F layer to S layer (-I_(inj)),the normal resistance is lower than that without current injection. The critical transition temperature is higher than that without current injection.

Simulation of magnetization behaviours of Sm(Co,Fe,Cu,Zr)z magnet with low Cu content

The effects of microstructure, cell orientation and temperature on magnetic properties and the coercivity mechanism in Sm（Co,Fe,Cu,Zr）z with low Cu content are studied by using the micromagnetic finite element method in this paper. The simulations of the demagnetization behaviours indicate that the pinning effect weakens gradually with the thickness of cell boundary decreasing and strengthens gradually with the cell size decreasing. Because of the intergrain exchange coupling, the coercivity mechanism is determined by the difference in magnetocrystalline anisotropy between the cell phase and the cell boundary phase. And the coercivity mechanism is related to not only the cells alignment but also temperature. With temperature increasing, a transformation of the demagnetization mechanism occurs from the domain pinning to the uniform magnetization reversal mode and the transformation temperature is about 650 K.