Search

We demonstrate a three-axis atomic magnetometer capable of measuring the magnitude and direction of a magnetic field based on the spin self-sustaining method using a rubidium vapor. Vectorial capability is added by precise compensation in three components of the magnetic field since the Larmor precession frequency is stable and constant in this process. A mean sensitivity of 0.78 pT/ Hz in the measurement of the field magnitude and a sensitivity of 3.5 × 10 - 6 rad/ Hz in the measurement of direction are realized. The coherence lifetime of atomic spins is lengthened to 340 ms and the sensitivity improves with time following a much faster τ - 1 rule which enables the magnetometer to reach the quantum shot noise floor in a much shorter time.

Three dimensional (3D) MoS2/graphene hybrid aerogels have emerged as promising candidates for energy storage and conversion technologies. In this paper, a facile one-pot freeze-drying self-assembly approach combined with in-situ thermal decomposition-reduction method is proposed to construct 3D porous aerogels with MoS2 active materials anchored on graphene backbone, making a highly interconnected network with desirable structural stability. The constructed hybrid aerogels with the optimal MoS2/GS ratio delivered high specific capacities, excellent cycling stability (862.5 mAh g−1 after 200 cycles at 0.1 A g−1 with a capacity retention of 109.6%) and good rate capability (622, 563 and 480 mAh g−1 at 1, 2 and 3 A g−1, respectively), holding great promise to be used as anode materials of LIBs. More importantly, the current method is simple, low-cost, environmental friendly without any need for toxic reagents, suitable for scalable production and can be extended to prepare other graphene-based hybrid aerogels.

The usual way to present images from a scanning tunneling microscope (STM) is to take multiple images of the same area, to then manually select the one that appears to be of the highest quality, and then to discard the other almost identical images. This is in contrast to most other disciplines where the signal to noise ratio (SNR) of a data set is improved by taking repeated measurements and averaging them. Data averaging can be routinely performed for 1D spectra, where their alignment is straightforward. However, for serial-acquired 2D STM images the nature and variety of image distortions can severely complicate accurate registration. Here, we demonstrate how a significant improvement in the resolving power of the STM can be achieved through automated distortion correction and multi-frame averaging (MFA) and we demonstrate the broad utility of this approach with three examples. First, we show a sixfold enhancement of the SNR of the Si(111)-(7 × 7) reconstruction. Next, we demonstrate that images with sub-picometre height precision can be routinely obtained and show this for a monolayer of Ti2O3 on Au(111). Last, we demonstrate the automated classification of the two chiral variants of the surface unit cells of the (4 × 4) reconstructed SrTiO3(111) surface. Our new approach to STM imaging will allow a wealth of structural and electronic information from surfaces to be extracted that was previously buried in noise.

The experimental discovery and theoretical analysis of an epitaxial (2 \ifmmode\times\else\texttimes\fi{} 2) honeycomb $\mathrm{N}{\mathrm{b}}_{2}{\mathrm{O}}_{3}$ monolayer on a Au(111) surface is reported. The oxide monolayer is grown by Nb deposition and subsequent annealing in an oxidizing atmosphere. Scanning tunneling microscopy (STM) images show that the films form a well-ordered honeycomb lattice, and low energy electron diffraction patterns confirm that the films adopt a (2 \ifmmode\times\else\texttimes\fi{} 2) periodicity with respect to the Au(111) substrate. Density functional theory (DFT) modeling shows that the Nb atoms are located in Au(111) threefold hollow sites and the O atoms are located in on-top positions. DFT also demonstrates the existence of a strong interfacial interaction characterized by a large electron transfer towards the Au substrate, an increase of the Nb oxidation state, and substantial film rumpling. High-resolution STM images, supported by simulations, are able to discriminate between Nb atoms adsorbed in fcc or hcp hollow sites on the Au(111) substrate.

The self-sustaining atomic magnetometer has the advantage of high sensitivity and long spin coherence lifetime, based on which we demonstrate a novel method to calibrate the magnetic coil constants precisely. Via non-destructive phase measurement and coherent optical pumping, the spin polarization of rubidium atoms is regenerated coherently and the Larmor precession signal is oscillating continuously. In this stable state, the calibrating capability is achieved by applying current to coils and scan the magnetic components along x- and y-direction. The magnetic field magnitude is obtained from precession frequency and the coil constants can be derived from the fitting equation directly. The constants of coils in the experiment are 246.010 ± 0.034 nT/mA and 197.452 ± 0.025 nT/mA in the x- and y-directions, respectively.

The spin self-sustaining atomic magnetometer has the advantage of 1/τ measurement and great development potential in many applications. In this paper, we investigated the main elements that affect the stability and accuracy of the self-sustaining magnetometer and proposed the methods to improve its performance based on the measurement results. The correlation coefficient between fluctuations of the magnetic field generated by coils and the spin Larmor precession frequency is 0.97, which mainly dominates the stability in a short term. The accuracy of the magnetometer is affected by the power and frequency of the pump light. The Larmor precession frequency coefficient related to the pump light power is 26 mHz/mW, and the effect on the Larmor precession frequency is minimized when the pump light frequency is red detuned by 200 MHz from the 85Rb transition D1 line F = 3 to F′ = 3. The 1/τ measurement time after these corrections can be extended to 10 s, and the sensitivity achieved is 149 fT/Hz, which is close to the quantum projection noise limit of the system.

International audience; Two-dimensional materials with a honeycomb lattice, such as graphene and hexagonal boron nitride, often contain local defects in which the hexagonal elements are replaced by four, five, seven, and eight-membered rings. An example is the Stone-Wales (S-W) defect, where a bond rotation causes four hexagons to be transformed into a cluster of two pentagons and two heptagons. A further series of similar defects incorporating divacancies results in larger structures of non-hexagonal elements. In this paper, we use scanning tunneling microscopy (STM) and density functional theory (DFT) modeling to investigate the structure and energetics of S-W and divacancy defects in a honeycomb (2 × 2) Ti 2 O 3 monolayer grown on an Au(111) substrate. The epitaxial rumpled Ti 2 O 3 monolayer is pseudomorphic and in a state of elastic compression. As a consequence, divacancy defects, which induce tension in freestanding films, relieve the compression in the epitaxial Ti 2 O 3 monolayer and therefore have significantly 2 lower energies when compared with their freestanding counterparts. We find that at the divacancy defect sites there is a local reduction of the charge transfer between the film and the substrate, the rumpling is reduced, and the film has an increased separation from the substrate. Our results demonstrate the capacity of the substrate to significantly influence the energetics, and hence favor vacancy-type defects, in compressively strained 2D materials. This approach could be applied more broadly, for example to tensile monolayers, where vacancy-type defects would be rare and interstitial-type defects might be favored.

We demonstrate a vector atomic magnetometer based on spin self-sustaining method with 1/τ property. The sensitivity of magnetic field magnitude and direction measurements are H z 0.64 p T / H z and 3.5 × 10 − 6 rad / Hz, respectively.

The atomic structures of two reconstructions, (√7 × √7)R19.1° and (√13 × √13)R13.9°, on the SrTiO3 (111) surface were determined using a combination of density functional theory and scanning tunneling microscopy data and APW + lo density functional theory minimizations and simulations. These reconstructions belong to the same structural family made up of an interconnected, single layer of edge-sharing TiO6 and TiO5[] octahedra. This family of reconstructions between 0.5 and 1.5 excess TiO2, representing the lowest-reported TiO2 coverages for reconstructions on this surface. This family is found to include the previously-solved (2 × 2)a reconstruction. They all follow a simple rule for surface composition, which serves as a tool for better understanding and predicting the structure of other reconstructions of arbitrary surface unit cell size on SrTiO3 (111). This reconstruction family and the calculations of surface energies for different hypothesis structures also shed light on the structure of Schottky defects observed on these reconstructed SrTO3 (111) surfaces.

The collision between tomato plug seedlings and the planting device during basket transplanter function causes the seedlings’ root lump to lose some mass. To resolve this problem, we establish a contact mechanics model using Hertzian contact theoretical and Newtonian methods, enabling us to formally derive the maximum deformation of the root lump. The equation of motion describing the collision between the tomato plug seedling and planting device is constructed using the principles of impulse and momentum. Then, we identify the optimization function of contact angle θ—which consists of the maximum deformation of the root lump, the angular velocity of the tomato plug seedling, and the absolute velocity of the root lump—via multi-objective methods. When the angular velocity of the planting device is 1.05 rad/s or 1.15 rad/s, the optimal contact angle is 67°. Further, we examine the velocity of the tomato plug seedling after collision. A small plant height reduces the root lump’s mass loss; we found that 12-cm-tall tomato plug seedlings lose less root lump mass than taller seedlings. Finally, for angular velocities of 1.05 rad/s and 1.15 rad/s, we carry out of tomato plug seedling crush tests with the optimized parameters, achieving minimum root lump mass losses of 8.76% and 7.43%, respectively.

The absolute measurement of magnetic fields can be realized by monitoring the Larmor precession of atomic spins. Yet, this spin-precession magnetometer can only be put into use in weak magnetic fields and the sensitivity is limited by the coherence time beyond which, the uncertainty decreases as τ−1/2 rate. Now we demonstrate that the dynamic range of an atomic spin magnetometer can be extended to geomagnetic field magnitude with τ−1 property maintained based on the the self-sustaining method. A mean sensitivity of 20 pT/Hz and a frequency response bandwidth of 5 kHz are realized in a magnetic field of 10000 nT. More important applications in large magnetic fields can be enabled in virtue of the superiority using this self-sustaining magnetometer.The absolute measurement of magnetic fields can be realized by monitoring the Larmor precession of atomic spins. Yet, this spin-precession magnetometer can only be put into use in weak magnetic fields and the sensitivity is limited by the coherence time beyond which, the uncertainty decreases as τ−1/2 rate. Now we demonstrate that the dynamic range of an atomic spin magnetometer can be extended to geomagnetic field magnitude with τ−1 property maintained based on the the self-sustaining method. A mean sensitivity of 20 pT/Hz and a frequency response bandwidth of 5 kHz are realized in a magnetic field of 10000 nT. More important applications in large magnetic fields can be enabled in virtue of the superiority using this self-sustaining magnetometer.

Platinum (Pt)/carbon nanotube (CNTs) nanocomposites were fabricated on the basis of Pt precursors reduced by hydrogen plasma generated by microwave process. The Pt nanoparticles were uniformly dispersed on multi-walled CNTs. Such nanocomposites exhibit remarkable catalytic performance towards the oxidation of methanol. The concentration of methanol was determined by a chronoamperometric method by using the Pt/CNTs modified glass carbon electrode (Pt/CNTs/GCE) at an oxidation potential of 0.7 V against the saturated calomel electrode. The Pt/CNTs/GCE showed a good performance for detecting methanol because of the unique properties of CNTs which increased the active surface area of the electrode and accelerated the electro transfer. The linear detection range of methanol was determined to be from 2.0 × 10 –4 to 10.0 M in two slopes with a detection limit 5 × 10 –5 M at a signal-to-noise ratio of 3. The performance of the Pt/CNTs/GCE in terms of stability, linear range and detection limit shows its potential application for methanol detection.

We report progress of the self-sustaining magnetometer. The sensitivity follows a faster τ−1 rule rather than τ−1/2 rule with time, and it can be close to the shot noise limit in a much shorter time.

The gyroscope based on atomic technology has the potential to provide the end user a high-performance device in a small package with low-power. Generally, the atomic gyroscope detects the rotation or angular rate of the object by measuring the Larmor precession frequency of spins. However, the precision is limited by the shorter coherence time caused by relaxation effects, and since the nuclear spin precession is often used in detection for atomic gyroscope, longer polarization time limits its application environment. Presented in this paper is a self-sustaining gyroscope based on electron spins. By non-destructively measuring the phase of the Larmor precession and regenerating the coherence via optical pumping, the Larmor precession can persist indefinitely, and the system can quickly regain polarization to environmental variations. Magnetic field measurement has been accomplished by using the self-sustaining technology. The precision of the magnetometer increases with time following a much faster \( \tau^{{{ - }1}} \) rule rather than the traditional \( \tau^{{{ - }1/2}} \) rule. The mean sensitivity is close to the shot noise in 300 ms, and the magnetometer has a quick response to sudden magnetic change. The self-sustaining technology can hopefully improve the measurement precision and the response time of the atomic gyroscope.

We demonstrate a method to stabilize laser frequency which can be continuously tuned over a range of 1.5 GHz. It is based on saturated absorption spectroscopy (SAS) generated by an external-cavity diode laser (ECDL) which is modulated by an electro-optic amplitude modulator (EO-AM). The spectra consist of not only the original peaks corresponding to resonant and crossover lines of 133Cs D2 line, but also signals introduced by sidebands from an EO-AM. Thus, the laser frequency can be locked to any point within the range of the spectra. Furthermore, the tuning range of the laser can be doubled compared to the coverage of common SAS by fixing the frequency of the pumping laser. The best stability of the locked laser induced by the EO-AM is 1.27 × 10−11 over an integrating time of 125 s. This method may be applied for more precise and flexible manipulation of atoms and molecules.

The electron beam welding of SiCp/101Al composites has been carried out. The influence of welding parameters on weldability and mechanical properties of the welded joints was discussed. The welding parameters were therefore optimised under the current experimental circumstance. Results show that only weak interfacial reaction between SiC particle and liquid aluminium occurred. Minute quantity brittle Al4C3 compounds and single phase Si were generated in the welded joint. The interfacial reaction between SiC particles and Al matrix could be greatly suppressed by adopting appropriate technique measures such as high welding speed and low heat input. The content of Al4C3 can be therefore greatly decreased in the welded joint. Moreover, modification welding and electron beam scanning could further improve the appearance of weld, and the welded joint with better quality could be obtained.

Epitaxial Fe/MgO/Fe magnetic tunnel junctions (MTJs) were grown on MgO(001) substrates by molecular beam epitaxy. The epitaxial structure has been characterized using in-situ reflection high energy diffraction, ex-situ X-ray diffraction, and high-resolution transmission electron microscopy. The magnetic and transport properties have been investigated using vibrating sample magnetometry and physical properties measurement system. The temperature dependence of the TMR ratio, whose value rises from 170% at room temperature to 318% at 10 K, is found to be nonlinear and is fitted using a model based on the effect of magnetic disorder of the electrodes on the spin polarized tunneling.

Using data samples collected with the BESIII detector operating at the BEPCII collider at 17 center-of-mass energies from 3.810 to 4.600 GeV, we perform a study of e(+)e(-) -> eta J/psi and pi(0)J/psi The Born cross sections of these two processes are measured at each center-of-mass energy. The measured energy-dependent Born cross section for e(+)e(-) -> eta J/psi shows an enhancement around 4.2 GeV. The measurement is compatible with an earlier measurement by Belle.

Using data samples collected with the BESIII detector at the BEPCII collider, we measure the Born cross section of e(+)e(-) -> p (p) over tilde at 12 center-of-mass energies from 2232.4 to 3671.0 MeV. The corresponding effective electromagnetic form factor of the proton is deduced under the assumption that the electric and magnetic form factors are equal (vertical bar G(E)vertical bar = vertical bar G(M)vertical bar). In addition, the ratio of electric to magnetic form factors, vertical bar G(E)/G(M)vertical bar, and vertical bar G(M)vertical bar are extracted by fitting the polar angle distribution of the proton for the data samples with larger statistics, namely at root s = 2232.4 and 2400.0 MeV and a combined sample at root s = 3050.0, 3060.0 and 3080.0 MeV, respectively. The measured cross sections are in agreement with recent results from BABAR, improving the overall uncertainty by about 30%. The vertical bar G(E)/G(M)vertical bar ratios are close to unity and consistent with BABAR results in the same q(2) region, which indicates the data are consistent with the assumption that vertical bar G(E)vertical bar = vertical bar G(M)vertical bar within uncertainties.

Using a sample of 1.31 billion J/psi events accumulated with the BESIII detector at the BEPCII collider, we report the observation of the decay J/psi -> phi pi(0), which is the first evidence for a doubly Okubo-Zweig-Iizuka suppressed electromagnetic J/psi decay. A clear structure is observed in the K+K- mass spectrum around 1.02 GeV/c(2), which can be attributed to interference between J/psi -> phi pi(0) and J/psi -> K+K- pi(0) decays. Due to this interference, two possible solutions are found. The corresponding measured values of the branching fraction of J/psi -> phi pi(0) are [2.94 +/- 0.16(stat) +/- 0.16(syst)] x 10(-6) and [1.24 +/- 0.33(stat) +/- 0.30(syst)] x 10(-7).

The complex natural resonances (poles) of complex radar targets are usually extracted frommeasured signature, and have low precision because of being extremely sensitive to noise. In numerically methods to calculate targets' poles, the method of moment (MoM) combined with contour integration is a smart one and widely used. But that method is limited to simple shaped or revolution objects. For complex shaped targets by that method, the number of poles in contour is incorrectly estimated, and the results are inaccurate. In this paper, a domain difference method for searching complex targets' poles on complex plane is proposed on the criterion, that the second-order differenced logarithm of determinant of coefficient matrix from MoM is local maximum. Numerical results of a conducting sphere are presented to demonstrate the accuracy and capability of the proposed method. Lastly, the poles of a missile model and a plane model are calculated, and compared with those from the Matrix-Pencil (MP) method.

The Raman spectra for single-walled carbon nanotubes (SWNTs) at different temperatures are studied. We find that the G peak position shifts to low frequency with increasing temperature. The variation rate of the peak frequency as a function of temperature is a factor of 2~3 larger than the corresponding G peak frequency variation rates of multiwalled carbon nanotubes and highly ordered pyrolytic graphite from room temperature to 673 K. The line shapes of the RBM features are also found to be sensitive to temperature. The softening of the interatomic force constant due to thermal expansion of C-C bonds and the relaxation of the weak van der Waals interaction between the SWNTs in a bundle with increasing temperature are suggested to be the main origins of the reversible spectral variations.

A novel biosensor, comprised of electrode of gold/multi-walled carbon nanotubes–glucose oxidase (Au/MWNTs–GOD), has been developed. The MWNTs were produced by microwave plasma enhanced chemical vapor deposition. The enzyme of GOD was immobilized using MWNTs. Performance and characteristics of the fabricated glucose biosensor were assessed with respect to response time, detection limit, pH value and storage stability. The results show that the fabricated biosensor is sensitive and stable in detecting glucose, indicating that MWNTs are a good candidate material for the immobilization of enzyme in glucose biosensor construction. Keywords: Carbon nanotubes, Biosensor, Enzyme immobilization, Glucose, Glucose oxidase

In this paper, we studied the effects of oxygen (O2) and nitrogen (N2) on the growth of carbon nanotubes (CNTs) prepared using microwave plasma-enhanced chemical vapor deposition (MPECVD). CNTs were prepared with 20–100-nm-sized Ni catalyst grains under three different groups of plasma conditions. Scanning electron microscopy (SEM) results show that the quality of CNTs is improved and number density greatly increased with addition of N2 and O2 in the process. The morphology and Ni composition strongly suggest that the grain size and composition of the Ni catalyst can be modified by the N2 and O2 plasma pretreatments. A nitride-enhanced growth mechanism is also discussed.

We demonstrate an atomic magnetic gradiometer based on self-sustaining Larmor precession. By coherent optical pumping, we measure the phase of the Larmor precession directly and observe that the gradiometer shows a 1/τ improvement in magnetic field gradient uncertainty over time τ. Since the measurement gives frequency signals, the gradiometer can be easily implemented by mixing and filtering the different frequency signals from two adjacent magnetometers. A gradient sensitivity of 186 fT/Hz/cm-1) is realized, which is close to the shot-noise limit. In a noisy environment, the gradiometer can still maintain its 1/τ behavior by suppressing 90% of the common-mode noise. This method should be widely applicable to the measurement of magnetic field gradients owing to its simplicity and outstanding performance.

Aim A pulsed strong magnetic fields generator is designed. Methods A large value capacitor is used to store electric energy, coil is used for produce magnetic field, main control circuit control charge, sampling, discharge, etc. Results The generator provides a pulsed magnetic field with the amplitude of intensity from 0.1T~2T and variable time interval of pulse from 4s ~1min. It is not only to be operated easily but also performs reliably. Discussion The generator will be applied in special clinical diagnosis, therapy and other purpose.

Aligned carbon nanotubes (CNTs) which were always perpendicular to the surface of substrate were synthesized on geometrically different surface through microwave plasma chemical vapour deposition (MWPCVD) at the low temperature of 550 °C. Growth was performed in a flowing mixture of CH 4 and H 2 . Scanning electron microscopy (SEM) shows that the vertically aligned growth occurred under the effect of plasma. When the substrate was not contacted with plasma, only randomly entangled CNTs had grown on the substrate. The research results demonstrate that the electrical self-bias imposed on the surface is the primary mechanism responsible for the alignment of CNTs.

Using a data sample containing 1.06x10^8 psi' events collected with the BESIII detector at the BEPCII electron-positron collider, we search for a light exotic particle X in the process psi' -> pi^+ pi^- J/psi, J/psi -> gamma X, X -> mu^+ mu^-. This light particle X could be a Higgs-like boson A^0, a spin-1 U boson, or a pseudoscalar sgoldstino particle. In this analysis, we find no evidence for any mu^+mu^- mass peak between the mass threshold and 3.0 GeV/c^2. We set 90%-confidence-level upper limits on the product-branching fractions for J/psi -> gamma A^0, A^0 -> mu^+ mu^- which range from 4x10^{-7} to 2.1x10^{-5}, depending on the mass of A^0, for M(A^0), 7 pages, 3 figures, submitted to Physical Review D

The electronic structure and properties of carbon nanotubes (CNTs) strongly depend on their diameter and chirality. The well controlled CNTs diameter is becoming one of the challenges for their applications in microelectronics. In this paper, the patterned CNTs were produced by microwave plasma enhanced chemical vapor deposition technique using a metal catalyst of nickel. The correlation between the CNT diameter and the grain sizes of the nickel catalyst was examined. The experimental results show that nickel films converted to nickel particles when they were heated up. The diameter of CNTs increases with increasing grain sizes of the nickel particles, indicating that the CNT diameter can be controlled by controlling the grain sizes of the nickel catalyst.

The subtle electronic properties and large electroactive surface of carbon nanotubes (CNTs) suggest that they have the ability to promote electron-transfer and favor electrocatalytic behavior in electrochemical reactions when they are employed as an electrode. In this paper, CNT-modified gold electrodes for glucose biosensor have been fabricated using multi-walled carbon nanotubes. The CNT-based electrode exhibits a strong and stable amperometric response toward glucose even at a low potential of +0.35 V versus Ag/AgCl in comparison with the glassy carbon-based electrode.

Thermal conductivity of multiwalled carbon nanotubes (CNT's) prepared using a microwave plasma chemical vapor deposition system is investigated using a pulsed photothermal reflectance technique. We find that the average thermal conductivity of carbon nanotube films, with the film thickness from 10 to 50 \ensuremath{\mu}m, is around 15 W/m K at room temperature and independent of the tube length. Taking a small volume filling fraction of CNT's into account, the effective nanotube thermal conductivity could be $2\ifmmode\times\else\texttimes\fi{}{10}^{2}\mathrm{W}/\mathrm{m}\mathrm{}\mathrm{K},$ which is smaller than the thermal conductivity of diamond and in-plane graphite by a factor of 9 and 7.5, respectively.

This paper describes the performance of the GM/PT hybrid refrigerator with the different opening of the orifice valve, the working frequency and the volume of the regenerator, and also presents some useful conclusions that can be used for design and further study of the GM/PT hybrid refrigerator.

An online monitoring and real-time simulation system for icing of transmission lines is designed using sensing technology with a coplanar multipoint capacitance. A sensor is used in the system to detect changes in the metal electrode capacitance at various positions surrounding transmission lines and verify the ice thickness on the analog lines. Using theoretical analysis and simulations of coplanar electrode fields and capacitors, as well as freezing tests of the system at low temperatures, we found that the system could be quite useful for monitoring the ice thickness of transmission lines.

A new carbon network is prepared using microwave plasma enhanced chemical vapor deposition(MPCVD) under the plasma of a mixture of methane, hydrogen and nitrogen at 720 °C. The Field Emission Scanning Electronic Microscopy(FESEM) images show that the carbon nanotubes are self-organized into carbon networks, which is different from the previously reported carbon nanotube ropes or nanofibers. The carbon networks are about 1 micron in diameter, more than 10 microns in length and composed of hundreds of carbon nanotubes with the diameter from 20 to 100 nm. Energy Dispersive X-Ray(EDX) results confirm that the network is carbon in nature, with a small amount of Ni which was used as catalyst.

The authors have developed a simple technique which permits fabrication of Josephson junctions in high-Tc epitaxial thin films. The junctions demonstrate both DC and AC Josephson effects in LN temperatures. The critical current decreases linearly with external microwave current, and is proportional to (Tc-T)32/.

By employing high-temperature superconducting quantum interference device (SQUID) magnetometers, we have assembled a second-order gradiometer for magnetocardiography (MCG) in unshielded environment. With this high-temperature superconductor (HTS) SQUID system, we demonstrated its diagnostic relevance for MCG in terms of signal-to-noise ratio, spatial resolution, frequency bandwidth, rejection of environmental disturbances, and long-term stability. The electronically balanced gradiometer consists of three HTS radio-frequency SQUIDs with superconducting coplanar resonators, mounted in axial gradiometric arrangement with a baseline of 7.5 cm. The system achieves a common mode rejection for axial homogeneous fields of about 10(4) without any mechanical balancing, and a white noise about 130 fT/root Hz at 77 K, with an 8x8 mm(2) flux pickup area. MCG maps above volunteers' chests have been recorded in unshielded environment in a bandwidth of about 130 Hz. We showed the influence of several notch filters (suppressing the power line frequency) on the quality of the MCG signals. (C) 2000 American Institute of Physics. [S0003-6951(00)03307-6].

Data sets were collected with the BESIII detector at the BEPC II collider at the center-of-mass energy of root s=3.650 GeV during May 2009 and at root s=3.773 GeV from January 2010 to May 2011. By analyzing the large angle Bhabha scattering events, the integrated luminosities of the two data sets are measured to be (44.49 +/- 0.02 +/- 0.44) pb(-1) and (2916.94 +/- 0.18 +/- 29.17) pb(-1), respectively, where the first error is statistical and the second error is systematic.

A large enhancement of anomalous Hall resistivity was obtained in the perpendicular [Co/Pt]3 multilayers sandwiched by MgO/CoO hybrid bilayers. For example, the saturation Hall resistivity (ρxy) is greatly increased, which is 250% and 67% larger than that in pure [Co/Pt]3 multilayers and that in [Co/Pt]3 multilayers sandwiched by pure MgO layers, respectively. Meanwhile, the perpendicular magnetic anisotropy in the multilayers with MgO/CoO hybrid bilayers was enhanced. The large enhancement of ρxy originates from the modified metal/oxide interfacial structures, together with improved crystallization of core [Co/Pt]3 multilayers, due to the insertion of hybrid bilayers.

Poly(3-alkylthiophene) formed regular, layered arrays and showed liquid crystalline structures in the solid state. To elucidate the nanophase segregation in poly(3-alkylthiophene)/fullerene blends, X-ray diffraction, atomic force microscopy, scanning electron microscopy, and polarized optical microscopy were conducted. The effect of side-chain influence on the photovoltaic properties of solution-processed poly(3-alkylthiophene)lfullerene blends has been studied in this paper. Side chains investigated here include butyl, hexyl, and dodecyl groups. It shows that the photovoltaic performance is strongly affected by the length of side groups, which alters the morphology of the photoactive layer due to changes in solvent solubility, miscibility, and fullerene diffusion rate in the blends.