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The feather-like hierarchical zinc oxide (ZnO) was synthesized via successive ionic layer adsorption and reaction without any seed layer or metal catalyst. A possible growth mechanism is proposed to explain the forming process of ZnO feather-like structures. Meanwhile, the photo-electronic performances of the feather-like ZnO have been investigated with the UV-vis-NIR spectroscopy, I-V and I-tmeasurements. The results indicate that feather-like ZnO hierarchical structures have good anti-reflection and excellent photo-sensitivity. All results suggest that the direct growth processing of novel feather-like ZnO is envisaged to have promising application in the field of photo-detector devices.

LiNbO3/polycarbonate (LNO/PC) composite films with different concentration of LiNbO3 ferroelectric nanocrystals are prepared by spin coating method. The polarization and dielectric relaxation behaviors of LNO/PC composite films are characterized through in-situ transmission spectrum measurement. The LiNbO3 ferroelectric nanocrystals are prepared by hydrothermal method with rhombohedral structure and the average crystal size is about 50 nm. It’s found that 15%LNO/PC composite film has the largest orientation change with the ϕ value of 62% and slow dielectric relaxation, almost no decay after 6 h. Based on the literatures, we can proposed that the preferential orientation of LiNbO3 nanocrystals after poling is [001] direction. This suggests that in-situ transmittance measurement is a simple and effect way to evaluate the polarization and dielectric relaxation behaviors of ferroelectric nanocrystals/polymer systems.

Figure S1 The temporal evolution of spectral of MO photodecomposition by Zn-In-4. (DOC 571Â kb)

Hexagonal In2O3–ZnO heterostructural composites with high visible-light photocatalytic activity have been obtained by a one-step hydrothermal process. The microscopic analysis revealed that the In2O3–ZnO heterostructures were composed of In2O3 nanoparticles dispersed on the surface of ZnO nanodisks. Compared with pure ZnO nanodisks, the obtained In2O3–ZnO composites exhibit significantly enhanced photocatalytic activity for methylene blue degradation under visible light irradiation. The enhanced photocatalytic activity could be attributed to the formation of heterostructures, which might improve the separation of photogenerated electrons and holes.

With the renewed applications of millimeter wave technologies in remote sensing, radio astronomy, and quasi-optical (QO) systems have been widely used in various radiometer systems. Frequency selective surface (FSS) is one of the key components in a QO system, functioning as frequency separation. For a practical FSS component, small insertion loss and narrow transition band from pass band to stop band are preferred to maintain signal level and reject out-of-band noise, respectively. In addition, the bandwidth is also a concerned parameter. In this article, perforated array is used for the design and fabrication of FSS for a dual-channel QO system. The agreement between measurement and simulation is satisfactory. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2365–2369, 2014

Lead free piezoelectric ceramics of Y3+-doped Ba1−xCaxZr0.07Ti0.93O3 with x = 0.05, 0.10, and 0.15 were prepared. Composition and temperature-dependent structural phase evolution and electrical properties of as-prepared ceramics were studied systematically by X-ray diffraction, Raman spectroscopy, impedance analyzer, ferroelectric test system, and unipolar strain measurement. Composition with x = 0.10 performs a good piezoelectric constant d33 of 363 pC/N, coercive field Ec of 257 V/mm, remanent polarization Pr of 14.5 μC/cm2, and a Curie temperature Tm of 109°C. High-resolution X-ray diffraction was introduced to indicate presence of orthorhombic phase. Converse piezoelectric constant d33* of x = 0.10 composition performed better temperature stability in the range from 50°C to 110°C. That means decreasing orthorhombic–tetragonal phase transition temperature could be an effective way to enlarge its operating temperature range.

Spindle-like Ag/ZnO heterostructure composites were synthesized through a solution-based surface modification method, during which Ag nanoparticles were deposited on the surfaces of ZnO spindles prepared in advance. The obtained samples were characterized by XRD, SEM, TEM, XPS, PL and UV–vis absorption spectroscopy. The photocatalytic activity of the as-prepared spindle-like Ag/ZnO samples with different Ag contents was tested with the photocatalytic degradation of methylene blue. Results showed that the photocatalytic activity of Ag/ZnO was obviously improved compared with the pure ZnO, and the Ag/ZnO-2 sample prepared with an AgNO 3 concentration of 0.05 M had the highest photocatalytic activity. The Ag/ZnO heterostructure composites promoted the separation of photo-induced electrons and holes, which was proved by surface photovoltage spectroscopy.

In a book 《the unsolved problems in number theory[1]》 which came up with a conjecture"even numbers are the difference between two prime numbers[2]",this conjecture is an unsolved conjecture. In this paper,the author get the equivalent proposition of this conjecture,the theory is based on chandra symmetric matrix[3], this matrix has a specific character : if a nature number N is appear in the matrix,then 2N+1 is a composite number,if N is not in the matrix,then 2N+1 is a prime number.The author made the promotion of the matrix,and get the equivalent proposition of this conjecture:2mn + m + n+x and 2m + m+n if these two formulas can not expressed all nature numbers bigger than 4,then this conjecture is set up;if these two formulas can do it,then this conjecture is not set up; This expression can be the equivalent proposition of this conjecture.

All electrical manipulation of magnetization in an Y3Fe5O12 (YIG)/Pt system was crucial to develop magnon-based spintronic devices. In this study, we realized spin–orbit torque (SOT) switching in perpendicular YIG/Pt films. Perpendicular magnetic anisotropy of YIG was induced by strain from the bottom substrate and also influenced by the capping Pt layer and subsequent annealing. Besides, SOT efficiency of the YIG/Pt system was also measured. Damping-like torque with an efficiency of 0.98 Oe/(MA/cm2) was the dominating term to contribute to the SOT switching. This work was beneficial to construct electrically controllable magnon devices.

Submicrometer-scale ZnO composite aggregate arrays of nanorods and nanoparticles were prepared by simple wet-chemical route and studied as dye-sensitized solar cells (DSSCs) photoanodes. The ZnO composite aggregate arrays significantly improved the efficiency of DSSCs due to their relatively high surface area, fast electron transport, and enhanced light-scattering capability. A short current density ( J sc ) of 11.7 mA/cm 2 and an overall solar-to-electric energy conversion efficiency ( η ) of 3.17% were achieved for the ZnO composite aggregate DSSCs, which were much higher than those obtained for the monodisperse aggregate DSSCs ( J sc = 6.9 mA/cm 2 , η = 1.51%) and ZnO nanorod array DSSCs ( J sc = 4.2 mA/cm 2 , η = 0.61%).

Using the analysis of the evanescent surface plasmon polariton (SPP) mode at the GaN/Ag interface as basis, we propose a light-emitting diode (LED) structure with a plasmonic Ag nanostructure and sapphire grating to enhance external quantum efficiency. The 2D finite-difference time-domain method is used to study the spectral properties of the hybrid structure and the effects of structural parameters on light emission enhancement. The plasmonic Ag nanostructure couples recombination energy to the SPP modes at the GaN/Ag interface, whereas the sapphire grating scatters photons out of the LED chips with high extraction efficiency. Under optimal parameters, external quantum efficiency enhancement increases to approximately eighteen times the original value at a relatively long wavelength.

This paper presents a kind of a multichannel THz detector using lens-based bow-tie array. A hyperhemispherical silicon lens is employed to provide a focal plane; 8 bow-tie elements are arranged on the focal plane with careful design to show a performance of broadband, high gain, well compact, and easy assembling. These characteristics of the detector are preferred for detecting weak THz signal. Measured far field shows that the radiation pattern of each element is shifted angularly, by ≈9°, which can be used for THz imaging. Tested responsivity of the detector shows a good spectral performance from 260 to 400 GHz: respective values were ≥220 V/W, and the best NEP is achieved at about 60 pW/ . Besides that, the proposed antenna has advantages of simple structure, easy fabrication, and low cost.

This paper presents a wire grid polarizer (WGP) working at the frequency ranges between 1 GHz to 500 GHz. The WGP is extensively used in polarization sensitive elements for separating different polarized signals at the same channel. The spacing pitch-to-width ratio should be chosen seriously for lower cross polarization levels in double polarizers. The influences between single and double layers WGP are also discussed simultaneously. The single layer simulation results of reflectance and transmittance coefficients are more than 0.96 in double polarization directions, which has been fabricated successfully. The double layers WGP can improve obviously the reflection coefficient and make the transmission coefficient oscillated.

This work presents the thermal analysis of a Schottky diode frequency doubler capable of providing over 30 mW at 160 GHz at room temperature. This analysis includes thermal modeling of its structure and characterization at different temperature conditions. The modeling of different Schottky diode multiplier chip layouts indicates that the analyzed circuit uses the optimum configuration from the thermal point of view. Finally, the performance predicted by a physics-based numerical electro-thermal model for Schottky diodes integrated into a circuit simulator based on the harmonic balance technique is also presented and compared with measured data on the 160 GHz frequency doubler.

The efficiency enhancement mechanism of the alkali-treated Si nanowire (SiNW) solar cells is discussed and analyzed in detail, which is important to control the useful photovoltaic process. All the results demonstrate that the photovoltaic performance enhancement of alkali-treated SiNW device steps from the formation of the good core-shell heterojunction, which consequently enhances the junction area, promotes fast separating and transporting of electron and hole pairs, and reduces the carrier surface combination. It also indicates that alkali treatment for SiNWs is a promising processing as an economical method for the formation of good core-shell SiNW/polymer heterojunction.

International audience; Orientation and temperature dependence of dielectric and electromechanical properties of Mn-doped (Li,Na,K)(Nb,Ta)O3 single crystals were investigated. Samples exhibited very low dielectric losses, with tanδ between 0.03 and 0.05 over a broad temperature range between room temperature and 480 °C. Influences of the crystallographic structure and external electric field on polarization and strain parameters are discussed. The orientation-dependent electrical properties were ascribed to the anisotropic polarization rotation in the crystals. Higher maximum polarization, coercive field, and negative strain were achieved when the electric field was oriented along one of the spontaneous polarization directions. The highest maximum unipolar strain of 0.42% (at 3 kV/mm) and the normalized strain d 33 * of 1391 pm/V were obtained in the [001]PC-oriented sample at 100 °C, which was much higher than the values obtained for the [110]PC-oriented sample. Further insight of the phase transition behavior is given by comparing the temperature-dependence of the small- and large-signal dielectric and piezoelectric properties. The observed changes are rationalized by the different increase rates of the dielectric permittivity and piezoelectric coefficients with temperature.

A series of centimeter-sized lead-free piezoelectric Li+- and Ta5+-modified (Na,K)NbO3 single crystals with an ABO3 perovskite structure was successfully grown by the top-seeded solution growth method. Effective segregation of the elements was considered in order to further develop the growth of Li+- and Ta5+-modified (Na,K)NbO3 single crystals. The crystallographic structure and electrical behaviour along the [001]PC orientation were studied. X-ray diffraction, Raman spectroscopy and dielectric studies reveal that the increase in Ta5+ content reduces the orthorhombic–tetragonal phase transition. Bipolar and unipolar strain curves were investigated at 2 kV mm−1. The highest bipolar and unipolar strains associated with a large-signal piezoelectric constant of 368 pm V−1 were achieved for Li0.02Na0.626K0.354Nb0.808Ta0.192O3. The asymmetric bipolar strain curves were observed and related to the existence of internal bias fields induced by defect dipoles, which were created during the crystal growth process.

Urchin-like InP architectures were synthesized by hydrothermal route at 160 °C. The products were characterized with scanning electron microscopy, X-ray diffraction, spectrofluorometry. Results show that the hollow urchin-like InP microspheres with diameters of 40–70 μm were composed by numerous microrods with a diameter of about 0.5–2 μm. The obtained InP samples were of high purity zinc blende (cubic) structure. According to the analysis on the effects of reaction time on the morphologies, a possible formation mechanism of hollow urchin-like InP architectures was proposed. The optical properties of the urchin-like InP hollow microspheres were also investigated at room temperature, and results show that the urchin-shape InP microspheres displayed a strong emission at 599 nm, which is quite different from that observed in all previous reports related to the InP nano/micro structures.

Novel worm-like Ag/ZnO core–shell heterostructural composites were fabricated using a two-step chemical method. As-prepared silver nanowires were soaked in a solution of zinc acetate and triethanolamine to form worm-like Ag/ZnO core–shell composites under ultrasonic irradiation. Samples were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, and UV–vis spectrophotometer. The results show that the core–shell composites are composed of single-crystal Ag nanowires serving as the core, on which dense ZnO particles grow as the shell. The surface plasmon absorption band of Ag/ZnO composites is distinctly broadened and red shifted to monometallic Ag nanowires. The PL intensity of Ag/ZnO heterostructural composites varies and has the minimum intensity for the sample prepared with Ag of 2.8 atom %. Moreover, photocatalytic tests show that the Ag/ZnO composites ...

SrBi2Ta2O9 ceramics with various excess Bi2O3 content were synthesized by conventional solid state method. The effects of excess Bi3+ content on structure and electrical properties were investigated. XRD analysis indicated that a typical bismuth layer polycrystalline structure was gained. Plate-like grains with different size were observed by SEM. With the occurrence of a liquid phase during sintering process, the excess Bi2O3 content greatly influenced densification and grain size of as-prepared ceramics, which determine microstructure and electrical properties of these samples to some extent. The results also found that the electrical properties were consistent with grain size. The sample with 5% excess Bi2O3 could exhibit a better hysteresis loop, with relative density and dielectric constant of about 96.8% and 149, respectively. (C) 2012 Elsevier B.V. All rights reserved.

A 166/332GHz frequency doubler based on a Schottky diode has been designed and measured. It uses a diode chip with two Schottky varactor diodes in a balanced configuration, flip-chip mounted to a 50um thick quartz filter substrate. The doubler uses a fixed tune split waveguide block designed for ease of assembly. Measurements show a peak efficiency around 4.7% at 332.8GHz, with 1.2 mW output power at room temperature.

International audience; Lead-free piezoelectric materials attract more and more attention owing to the environmental toxicity of lead-containing materials. In this work, we review our first attempts of single crystal grown by the top-seeded solution growth method of BaTiO3 substituted with zirconium and calcium (BCTZ) and (K0.5Na0.5)NbO3 substituted with lithium, tantalum, and antimony (KNLSTN). The growth methodology is optimized in order to reach the best compositions where enhanced properties are expected. Chemical analysis and electrical characterizations are presented for both kinds of crystals. The compositionally-dependent electrical performance is investigated for a better understanding of the relationship between the composition and electrical properties. A cross-over from relaxor to ferroelectric state in BCTZ solid solution is evidenced similar to the one reported in ceramics. In KNLSTN single crystals, we observed a substantial evolution of the orthorhombic-to-tetragonal phase transition under minute composition changes.

Millimeter wave radiometry is fast becoming a more widespread technique in imaging and non-destructive testing due to its inherent benefits over the visible spectrum. Transparency to most non-conductive materials combined with better spatial resolution of objects are a few underlining features of using millimeter waves. This paper describes the characterization of two broadband, planar Schottky diode based radiometer modules centered at 94 GHz and 183 GHz. The 94 GHz radiometer is built using a W-band fundamental mixer configuration while the 183 GHz radiometer uses a sub-harmonic mixer. The local oscillator scheme consisting of a 30 GHz source which is frequency tripled to 90 GHz is common to both radiometers. The frequency tripler has measured conversion efficiency of 10%. The IF bandwidth for the fundamental mixer is about 18 GHz while the sub-harmonic mixer is 10 GHz. The double-sideband mixer noise temperature for both front end mixers was measured to be around 600 K with a conversion loss of approximately 5–6 dB. Radiometer characterization for noise equivalent temperature difference will also be presented.

In this paper, flower-like Cu 2 NiSnS 4 (CNTS) nanoparticles were successfully synthesized by a facile solvothermal method for the first time. The as-synthesized CNTS nanoparticles were characterized with X-ray diffraction (XRD), energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), transmission election microscopy (TEM) and UV–vis–NIR spectroscopy. The CNTS semiconductor nanoparticles possessed pure cubic structure with size of the flowers around 400 nm in diameter. The UV–vis–NIR spectroscopy showed strong light absorption in the visible light region with band gap of 1.41 eV, suggesting its potential application in the field of thin film solar cells.

The structure and photo-doping effect on Sr 2 FeMoO 6 are investigated using the X-ray powder diffraction and positrons annihilation technique, respectively. Anti-site defect is about 8.8%, can be estimated directly from the XRD pattern, which is well consistent with that of obtained from the XRD refinements. The integral intensity ratio of the reflection (1 0 1) and the reflections (2 0 0) and (1 1 2) may used to estimate the concentration of the anti-site defect. The positron annihilation lifetime in Sr 2 FeMoO 6 is sensitive to photo-doping. The average lifetime and the electron density n e vary with photo-doping.

A method of designing high performance millimeter wave quasi-optical Faraday rotators (QOFR) is reported in this paper. First, the dielectric and magnetic parameters for the ferrite sample are determined by fitting theoretical curves to the measured data. These fitted parameters are then used in a precise numerical model to predict the rotation angle and insertion loss of the QOFR. Finally, the parameters of the QOFR are optimized according to the requirements of devices. Examples are given showing the performance of the QOFR with an isolation better than 20 dB and an insertion loss less than 0.6 dB from 75 GHz to 95 GHz.

This paper presents the design and performance of a x2x2 frequency multiplier chain from 40 to 160 GHz. The input power at 40 GHz is 500 mW with a final output power of 35 mW at 158 GHz. The 3 dB bandwidth at the output frequency is over 10%. The results demonstrate good agreement between the modeled and measured data. The work described in this paper involved extensive thermal modelling of the structure including the diode and filter circuits; this analysis allows good power handling performance for high power applications.

This paper describes the development and characterisation of broadband radiometers centered at 94 and 183 GHz for passive millimeter wave imaging and NDT applications. The W-band radiometer has been built and tested using both fundamental and sub-harmonic mixer configurations. The 183 GHz radiometer uses a sub-harmonic mixer at the front-end and has an LO that is common with the fundamentally pumped W-band receiver. In this case the LO is supplied via a ∼30 GHz source which is frequency tripled to 90 GHz with a conversion efficiency of around 10 %. The IF bandwidth for both fundamental and sub-harmonic W-band mixers is about 18 GHz while the 183 GHz mixer is 12 GHz. The room temperature DSB mixer noise temperature was measured to be around 500 K with a conversion loss of approximately 5 dB for 94 GHz and 183 GHz channels. NETD results for these radiometers are also presented.

Using a combination of scanning electron microscopy and X-ray diffraction techniques, the mechanism for ZnO formation was studied by simply heating an aqueous solution containing zinc salts and ammonium hydroxide to 85 °C. Growth of ZnO occurred via the initial precipitation of stable e-Zn(OH)2 microcrystals and subsequent formation of ZnO under these conditions. By monitoring an intermediate growth stage, phase transformation from e-Zn(OH)2 to ZnO was found to take place either via a dissolution–reprecipitation mechanism or via an in situ crystallization transformation mechanism that involves dehydration and internal atomic rearrangements. These findings may contribute to control the synthesis of ZnO in liquid media.

Numerical simulation of far field patterns of integrated lens antenna consisting of planar wideband clover leaf shaped dipole antenna is carried out in the presented work. W band performance of planar antenna is obtained by FEM based HFSS shows wide band behavior, symmetric patterns and circular polarization. Lens mounted feed's characterization is modeled using ray tracing inside lens and diffraction theory is used to calculate far field outside lens. Lens coupled clover leaf antenna's performance obtained by proposed hybrid method showed reduction of substrate mode loss and resulting in high broadside gain as well as directivity. Lens dimension's optimization is also carried out in this work.

Background Cycling is commonly prescribed for knee osteoarthritis, but previous literature on biomechanics during cycling and the effects of acute intervention on osteoarthritis patients does not exist. Due to their altered knee kinematics, osteoarthritis patients may be at greater risk of osteoarthritis progression or other knee injuries during cycling. This study investigated the effects of reduced foot progression (toe-in) angles on knee joint biomechanics in subjects with medial compartment knee osteoarthritis. Methods Thirteen osteoarthritis and 11 healthy subjects participated in this study. A motion analysis system and custom instrumented pedal was used to collect 5 pedal cycles of kinematic and kinetic data in 1 neutral and 2 toe-in conditions (5° and 10°) at 60 RPM and 80 W. Findings For peak knee adduction angle, there was a 61% (2.7°) and a 73% (3.2°) decrease in the 5° and 10° toe-in conditions compared to neutral in the osteoarthritis group and a 77% (1.7°) and 109% (2.4°) decrease in the healthy group for the 5° and 10° conditions, respectively. This finding was not accompanied by a decrease in pain or peak knee abduction moment. A simple linear regression showed a positive correlation between Kelgren–Lawrence score and both peak knee adduction angle and abduction moment. Interpretation For individuals who cycle with increased knee adduction angles, decreasing the foot progression angle may be beneficial for reducing the risk of overuse knee injuries during cycling by resulting in a frontal plane knee alignment closer to a neutral position.

A ferroelectric field effect in the bulk heterojunction was found when an external electric field (EEF) was applied on the active layer of polymer solar cells (PSCs) during the annealing process of the active layer spin-coated with poly (3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM). For one direction field, the short circuit current density of PSCs was improved from 7.2 to 8.0 mA/cm2, the power conversion efficiency increased from 2.4 to 2.8%, and the incident photon-to-current conversion efficiency increased from 42 to 49% corresponding to the different EEF magnitude. For an opposite direction field, the applied EEF brought a minus effect on the performance mentioned above. EEF treatment can orientate molecular ordering of the polymer, and change the morphology of the active layer. The authors suggest a explanation that the ferroelectric field has been built in the active layer, and therefore it plays a key role in PSCs system. A needle-like surface morphology of the active film was also discussed.

The paper presents novel cross bow tie antenna for terahertz focal plane arrays. A hybrid approach of FEM, Geometric optics and physical optics is adopted for observing effect of dielectric lens on radiation patterns. A comparative analysis has been carried out by observing radiation patterns by HFSS, FEKO and hybrid method.

This paper presents a novel hybrid method to simulate complex antenna system, which comprises a planar bow-tie antenna and an extended hemispherical lens. It utilizes Ansoft High-Frequency Structure Simulator (HFSS) to simulate the planar antenna, which is preferred for complicated structure. Ray-tracing is used to illuminate the lens surface with the radiation from the planar antenna (computed via HFSS), and Fresnel transmission coefficients is employed to compute the fields across the boundary between lens and the air. The rebuilt far-field pattern after lens is calculated by integrating the current distribution on lens surface. The comparison between this hybrid method and commercial software, such as HFSS and CST, are made at 100GHz. For higher frequency, which is difficult to simulate using HFSS or CST, the hybrid method shows a potential to predict the far-field pattern by comparing with test results.

Objective Real-time monitoring of cytokine secretion at the single immunocyte level, based on the concept of immune cells, sociology has been recently reported. However, the relationships between glioma-initiating cells (GICs) and host immune cells and their mutual interactions in the tumor microenvironment have not been directly observed and remain unclear. Methods The dual fluorescence tracing technique was applied to label the co-cultured GICs and host macrophages (Mø), and the interactions between the two types of cells were observed using a live cell imaging system. Fusion cells in the co-culture system were monocloned and proliferated in vitro and their social interactions were observed and recorded. Results Using real-time dynamic observation of target cells, 6 types of intercellular conjunction microtubes were found to function in the transfer of intercellular information between GICs and Mo; GICs and host Mø can fuse into hybrid cells after several rounds of mutual interactions, and then these fusion cells fused with each other; Fusion cells generated offspring cells through symmetrical and asymmetrical division or underwent apoptosis. A “cell in cell” phenomenon was observed in the fusion cells, which was often followed by cell release, namely entosis. Conclusions Preliminary studies revealed the patterns of cell conjunction via microtubes between GICs and host Mø and the processes of cell fusion, division, and entosis. The results revealed malignant transformation of host Mø, induced by GICs, suggesting complex social relationships among tumor-immune cells in gliomas.

The platform of Remote Measure and Control System is designed and constructed by LabVIEW and MATLAB, applying DataSocket and ActiveX, and takes the steam turbine speed control and single inverted pendulum systems which have complex dynamic characteristics as examples. In process of developing above real-time remote monitoring and control projects, fuzzy-immune-PID control of the turbine governing system based on compound chaos optimization strategy is considered, and T-S model double closed-loop fuzzy control is proof-tested in inverted pendulum. The results show that the novel platform not only establishes a real-time simulation environment to verify the application of scientific research, but also makes the local laboratory hardware accessible in long distances.

A bonded rhomb sample geometry is used to study the spin-dependent absorption characteristics of an intersubband transition in the conduction band of a GaAs/AlGaAs quantum well. Optical saturation experiments, using linearly and circularly polarized beams, were compared to measure the population relaxation time of the upper subband and the degree to which spin polarization is occurring in the electron population. In sharp contrast to previous interband absorption studies, the intersubband data are consistent with a picture in which the angular momentum of the incident photons appears to bypass the electron system completely and instead exerts a direct torque on the crystal lattice.

This paper investigates the impact of electrode geometry on the performance of polymer solar cells (PSCs). The negative electrodes with equal area (0.09 cm2) but different shape (round, oval, square and triangular) are evaluated with respect to short-circuit current density, open-circuit voltage, fill factor and power conversion efficiency of PSCs. The results show that the device with round electrodes gives the best photovoltaic performance; in contrast, the device with triangular electrodes reveals the worst properties. A maximum of almost a 19% increase in power conversion efficiency with a round electrode is obtained in the devices compared with that of the triangular electrode. To conclude, the electrode boundary curvature has a significant impact on the performance of PSCs. The larger curvature, i.e. sharper electrodes edges, perhaps has a negative effect on exciton separation and carrier transport in photoelectric conversion processes.

Monodispersed ZnO microspheres were synthesized through ultrasonic irradiation using zinc acetate as a Zn source and triethanolamine as the structure-directing and alkalinity control agent. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermo-gravimetric analyses were used to describe the as-prepared products and understand the formation mechanism. The results indicate that the morphology of the products is strongly dependent on the precursor Zn5(OH)8Ac2·2H2O. As the reaction time increased, the precursor, Zn5(OH)8Ac2·2H2O, decomposed into ZnO nanoparticles and simultaneously, ZnO nanoparticles assembled into a spherical structure under ultrasonic irradiation until the precursor, Zn5(OH)8Ac2·2H2O, completely disappeared. UV-vis absorption measurements of the as-prepared products at different stages show that the absorption peaks became sharper and blue-shifted from 422 to 364 nm with the change of composition and morphology. Photoluminescence (PL) measurements show that the intensity of the UV emission increased and that the wavelength first red-shifted and then blue-shifted with the increase of the reaction time, which may be related to the size and crystallinity of the ZnO particles.