Search

In this paper we report a chemical method named coordination reaction method to synthesize ZnO nanowire arreys. ZnO nanowires with the diameter about 80nm were successfully fabricated in the channels of the porous anodic alumina (PAA) template by the above coordination reaction method. The microstructures of ZnO/PAA assembly were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the ZnO nanowires can be uniformly assembled into the nanochannels of PAA template. The growth mechanism of ZnO nanowires and the conditions of the coordination reaction are discussed. Photoluminescence (PL) measurement shows that the ZnO/PAA assembly system has a blue emission band caused by the various defects of ZnO. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Shenkangling plays a role of Yishenhuoxue effect for the treatment of children with nephrotic syndrome. The aim of this study was to investigate the effects of Shenkangling intervention on the mitogen-activated protein kinase (MAPK) pathway in rats with Adriamycin-induced nephropathy (AN) and its underlying mechanism of action. Nephrosis was induced in healthy Sprague-Dawley rats by doxorubicin and the rats were untreated or treated with prednisone, simvastatin, Shenkangling, or a combination thereof. Using real-time PCR, the mRNA expression levels of Chemokine (C-X-C motif) ligand 16 (CXCL16), A Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), and ADAM17 in the renal tissues of these rats were found to be decreased by the various treatments compared to those in the untreated doxorubicin-induced nephrosis rats. To quantify the activation of the MAPK pathway, western blotting was used to detect the phosphorylation levels of MAPK pathway-associated proteins (p38, ERK1/2, SAPK/JNK) and nuclear factor (NF)-κB p65, which were reduced by the various treatments compared to those in the untreated doxorubicin-induced rats. Serum levels of transforming growth factor (TGF)-β1, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, quantified by ELISA, were decreased by the various treatments compared to the levels in the untreated doxorubicin-induced nephrosis rats. The rats treated with prednisone, simvastatin, and Shenkangling showed the best outcome. The Chinese medicine Shenkangling that is known for nourishing the kidney and promoting blood circulation reduced urinary protein levels, increased serum albumin levels, and reduced cholesterol levels by reducing the release of CXCL16, ADAM10, ADAM17, TGF-β1, TNF-α, IL-1β, IL- 6, and other inflammatory mediators and inhibiting the activation of the MAPK signaling pathway, thereby effectively improving the state of nephropathy in AN rats. These results indicate that Shenkangling can be used clinically to treat nephropathy.

A novel construction of microwave switchable lowpass filter based on electromagnetic bandgap (EBG) and cadmium sulfide (CdS) thin film is proposed. Linearly tapered slot-array EBG structure is well known for its exceptional stopband ability and compact physical size. When the illumination-sensitive CdS thin film is deposited on the perforations of the EBG structure, the stopband phenomenon induced by tapered slot-array can be controlled by optical means. Innovative “conductive islands” were introduced to reside in the center of each perforation in order to enhance the optical switching. It has been demonstrated in both simulation and experimental measurement that the transmission coefficient is switched from 31.3 to 5.6 dB at 13 GHz when the gap width between the conductive island and the perforation is 30 μm. As the gap width decreases, the insertion loss can be reduced. Simulation result indicates that the insertion loss can be improved to around 1 dB at 13 GHz when the gap width is decreased to 5 μm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2238–2242, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22665

Microwave photonic band-gap (PBG) structures are well known for their superior ability to generate a band stop effect at a certain frequency range. Together with the microstrip transmission line structure, PBG can be utilized as a filter exceptionally well since the periodic perforation patterns can be implemented easily in the ground plane. In this research work, square perforations of different dimensions are constructed in the ground plane of a microstrip transmission line to achieve a double band stop PBG structure. Thus, the transmission ability of the microstrip line is being blocked at different frequency ranges to create a bandpass filter. It is found that the bandpass frequency is strongly dependent on the dimension to period distance ratio. It is demonstrated in both simulation and measurement that the bandpass region can be created at high frequency above 10GHz.

Electromagnetic bandgap structures are well known for their stopband features and can be applied at microwave frequencies. In this work, a wide stopband electromagnetic band-gap (EBG) structure design based on 2D tapered slot array is presented. Each tapered slot length is designed to provide stopband at a specific frequency to maximize the attenuation level. The tapered slot array is positioned in the ground plane of a microstrip transmission line structure. Thus, the overall 9-slot nonlinearly tapered array produces a wide stopband from 9.3 to 20 GHz with attenuation better than 25 dB, which is observed in both simulation and actual measurements. The nonlinearly tapered EBG structure can be applied as an efficient lowpass filter. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 31–34, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22038

Photonic band-gap (PBG) structures are utilized in microwave components as filters to suppress unwanted signals. In this work, rectangular perforations were created in the ground plane of a microstrip line to construct a PBG structure. A gold-coated alumina substrate was utilized to switch or tune the bandstop characteristics of this structure. It was demonstrated that the bandstop characteristics were switched off from −35 to −1 dB at 16 GHz. Tuning of the bandstop edge with a shift of 1.5 GHz was also shown. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 334–337, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20462

A novel microwave microelectromechanical systems switch with a coplanar waveguide structure has been developed. The switch consists of a freestanding metallic cantilever and an electromagnet. A permanent magnetic film was deposited on top of the cantilever. By supplying a dc current to the electromagnet, the magnetic field generated would attract or repel the permanent magnetic film on top of the cantilever, causing it to make or break contact with a bottom electrode. An all-electrodeposition method has been used to improve the mechanical properties of the cantilever. The deposition process of the cantilevers has been optimized to improve the adhesion of the cantilever to the substrate and to minimize the switching dc power. Using commercially available electromagnet, a voltage of 2 V (dc power of about 15 mW), is sufficient to actuate the switches. Similar switching power was observed using an improved hand wound electromagnet. The on-state dc resistance of the switches is generally less than 2 Ω. At 10 ...

Noise measurements were carried out on RF-sputtered Pb-doped 2223 phase BiSrCaCuO superconducting thin films. No definite relationship between noise and bias current was observed in the superconducting state, however, a square-current dependence of noise was found in the normal state. The magnitude of the noise in the BiSrCaCuO films at room temperature was one to five orders of magnitude larger than that in a normal metal. Near the tail of the resistance transition, noise peaks were observed that were 3–12 K below the maximum of the derivative resistance–temperature curve. Noise dependence on frequency shows an approximate 1/f relation in both normal and superconducting states. The origin of the noise in the normal state is believed to be due to thermal fluctuation or resistance fluctuation and the larger noise near zero TC is possibly caused by grain boundaries in the films.

Single target magnetron RF sputtering has been used to deposit moderately Pb doped BiSrCaCuO thin films on to unheated (100) MgO substrates. The phase formation after annealing for a short period of time (

On-board generation of a set of calibration standards was demonstrated within a microfluidic device designed to perform immunoassay. Electrokinetic flow was used to proportionally mix the antibody (Ab) to bovine serum albumin (BSA) and a diluting buffer, to provide varying Ab concentrations for downstream mixing with fluorescently labeled BSA (BSA*). Mixing ratios were determined from electrical impedance modeling of the fluidic network using P-SPICE software, and peak heights for the labeled species were analyzed relative to the concentration calculated from the model. For dilution and separation of fluorescently labeled amino acids, a linear calibration curve was obtained for mixing ratios of 0.118 to 7.46. A linear calibration curve was obtained for the immunoassay calibration using dilution ratios between 0.197 and 5.077. Deviations were observed at larger extremes, possibly due to leakage effects at intersections. Peak height reproducibility was +/- 3% for the immunoassay, using diluted monoclonal Ab in mouse ascites fluid as the analyte. Recovery for on-chip calibration was 92 +/- 6% versus calibrants prepared off-chip, indicating a small bias.

After a brief review of CuInSe2 films prepared using an electrophoretic technique, results obtained by an electrochemical deposition method will be described. The electrophoretic technique, which is simple, was first investigated and found to be unsuitable for CuInSe2-film deposition. Using the electrochemical deposition method, we obtained uniform and homogeneous CuInSe2 films. The quality of the films was then determined by scanning electron microscopy, electron-probe microanalysis, X-ray diffraction, and secondary-ion mass spectroscopy. Heterojunction cells of the form CdS–CuInSe2 were finally fabricated using the electrodeposited films. The devices showed an active-area AM1 short-circuit current density of more than 30 mA∙cm−2 and a Voc of about 0.2 V.

In the present work, thin films of CdZnSO and ZnSO have been deposited on glass substrates from targets of mixed ZnO and CdS (or ZnS) powder by using a radio frequency magnetron sputtering method. It was found that the crystalline quality of the pure materials (ZnO, CdS, or ZnS) was better than the crystalline quality for an intermediate composition. The lattice parameters of these materials were also found to vary with the composition. By using a target containing 40% ZnO and 60% CdS, we obtained films with lattice parameters very near those of the semiconductor CuInSe2.

Using both Al–CuInSe2 Schottky junctions and CdS–CuInSe2 heterojunctions fabricated on electrodeposited p-type CuInSe2 films, we have investigated some properties of CuInSe2. From current–voltage and capacitance–voltage measurements carried out on these devices, it was found that the electronic quality of the CuInSe2 film surface was improved after the deposition of the CdS layer. In addition, it was observed that the electronic properties of the heterojunctions were dependent on the In/Cu ratio in the electrodeposited CuInSe2 films. Using a film with In/Cu = 1.1, we successfully fabricated a cell with an active-area conversion efficiency of 5.2%. Post-fabrication air heat treatment at 180 °C on the CdS–CuInSe2 devices was found to result in an increase in the charge-carrier concentration in the electrodeposited CuInSe2 films.

Thin films of Tl‐Ba‐Ca‐Cu‐O with different atomic ratios and a thickness of about 2 μm have been prepared by a sequential thermal evaporation method on alumina substrates followed by a heat treatment in an environment containing O2 and Tl. The results showed that films with a superconducting onset temperature of about 120 K and a zero resistance temperature of 85 K can be obtained with the following Tl:Ca:Ba:Cu ratios: 2:2:2:3 or 2:2:2:4. Films with a superconducting transition onset at 115 K and a zero resistance temperature of 74 K were also obtained by heating Tl‐free multilayer films in the environment containing O2 and Tl. It was also found that this new material was more resistant to water.

Polycrystalline films of Y‐Ba‐Cu‐O with a thickness of about 20–40 μm have been prepared on alumina substrates using a paint‐on method. The liquid source used was obtained by mixing powder of Y2O3, BaCO3, and CuO in liquid triethanolamine. Several Y‐Ba‐Cu‐O films with an onset temperature of about 100 K and a zero resistance temperature of 85 K have been obtained after a short heat treatment at 1000 °C in flowing O2.

Using a rf sputtering method with a single Ca‐Ba‐Cu‐O target (Ca:Ba:Cu=2:2:3), thin films with a thickness of about 1 μm have been deposited on ZrO2 and Si substrates. Diffusion experiments showed that the resistivity can be largely reduced by treating the films in an environment containing O2 and Tl. Treatment experiments at different temperatures further showed that the resistivity was affected by the temperature. By treating at 730 °C for about 1 h, a film on ZrO2 with a transition temperature of about 110 K has been obtained. Zero resistance was achieved at 75 K.

Work has been done to investigate properties of polycrystalline CdZnSO thin films prepared by sputtering. It was found that the magnitude of the diffraction peaks decreased progressively as the ZnO content was increased from 0% to 70% and increased as the ZnO content was further increased from 70% to 100%. The value of the d spacing of the CdZnSO films was also found to be affected by the ZnO content. The absorption edge was examined by transmission measurements and a rapid increase from 2.6 to about 3.2 eV was found in the range from 60% to 80% ZnO.

Junctions of CuInSe2/CdS have been investigated using an admittance spectroscopy technique to obtain information on electrically active states in CuInSe2. The junctions studied were fabricated using electrodeposited p‐type CuInSe2 films. The admittance experiments were carried out over a temperature range from 80 to 300 K with a frequency range from 1 to 100 kHz. In devices fabricated using CuInSe2 films with an In/Cu ratio of 1.10, peaks were observed in the conductance‐temperature curves with an activation energy of about 50 meV. Characteristic peaks with an activation energy of about 160 meV were found in the devices fabricated using CuInSe2 films with an In/Cu ratio of about 1.25.

Schottky junctions have been fabricated by evaporating aluminum on electrodeposited p‐type polycrystalline CuInSe2 thin films. The devices showed a rectification effect with an ideality factor of about 2 in the low‐forward‐voltage region. Results of carrier concentration obtained from C‐V measurements of the Schottky devices were found to be consistent with those for CdS/CuInSe2 heterojunctions fabricated on the same substrates. The apparent diffusion potential and carrier concentration of the Al/CuInSe2 Schottky junctions were both found to increase after a short heat treatment at 200 °C in air.

During the study of the formation of TlBaCaCuO from rf‐sputtered Ba‐Ca‐Cu‐O films (Ba:Ca‐Cu=2:2:3 in target) it was found that the rf‐sputtered materials were relatively unstable in water, in photoresist developer, and even in room atmosphere. To overcome the severe undercutting effect during the chemical etching process resulting from the instability, a Cu protective layer with a thickness of 100–150 A was adopted for the fine‐line patterning. Using a positive photoresist technique, 3‐μm lines have been successfully produced. Lines with a width of 150 μm also have been produced on ZrO2 substrates and superconductivity was observed after a heat treatment in an environment containing O2 and Tl gas.

Polycrystalline Y‐Ba‐Cu‐O thin films with a thickness of about 1 μm have been deposited on alumina substrates. The deposition was made by first sequentially evaporating Y/Ba/Cu layers followed by a heat treatment in an environment containing oxygen. The treated films were polycrystalline, and the electrical results showed an onset temperature of about 100 K and a zero‐resistance temperature of 78 K for the films treated at 850 °C for 2 h in oxygen.

Bulk Y‐Ba‐Cu‐O samples containing Si with nominal compositions of Y:Ba:Cu:Si=1:2:3:x (x=0.2, 0.4, and 0.6) have been prepared by adding SiO2 to the source materials. After a relatively short heat treatment, the resistance transition characteristics of the samples were found to improve as the SiO2 content was increased. Results from ac susceptibility measurements also showed improved values as the SiO2 content was increased. However, as the solid‐state reaction was carried out at a lower temperature but for a longer time, the sample resistance increased and the superconductivity was found to degrade.

For the high TC system of TlBaCaCuO1, it is specially interesting to investigate the formation of films from sputtered BaCaCuO2. In such experiments, a Tl-free target of BaCaCuO is used for the film deposition and therefore the contamination problem of the vacuum system can be avoided. Using such rf sputtered BaCaCuO films, it is necessary to carry out oxidation and Ti diffusion to form the final compound. In this paper, some of the experimental results on the deposition of BaCaCuO thin films are first described. Variation of composition in the BaCaCuO films with the heat treatment is then presented.

Indium‐doped zinc oxide films have been prepared by rf magnetron sputtering, using ZnO targets containing up to 10 wt. % In2O3. Room temperature resistivity of the deposited films was found to decrease by about four orders of magnitude as the In2O3 content was increased from 0 to 10 wt. %.