Search

The aim of the present study was to confirm the effect of Tanshinone IIA (TAN) on the prevention of AF in chronic heart failure (CHF), and to elucidate the underlying electrophysiological mechanisms for the antiarrhythmic effects of TAN at the level of the atrium in an experimental model of CHF. In 10 female rabbits, CHF was induced by rapid ventricular pacing, leading to a significant decrease in ejection fraction in the presence of a dilated left ventricle and atrial enlargement. Twelve rabbits were sham-operated and served as controls. Isolated hearts were perfused using the Langendorff method. Burst pacing was used to induce AF. Monophasic action potential recordings showed an increase of atrial action potential duration (aAPD) and effective refractory period (aERP) in CHF hearts compared with sham hearts. Infusion of acetylcholine (1 μm) and isoproterenol (1 μm) led to AF in all failing hearts and in 11 sham hearts. Simultaneous infusion of TAN (10 μm) remarkably reduced inducibility of AF in 50% of sham and 50% of failing hearts. TAN had no effect on aAPD but significantly increased aERP, leading to a marked increase in atrial post-repolarization refractoriness. Moreover, TAN application moderately increased interatrial conduction time. TAN has been shown to be effective in reducing the inducibility of AF in an experimental model of AF. The antiarrhythmic effect is mainly due to prolongations of atrial post-repolarization refractoriness and a moderate increase in interatrial conduction time. [ABSTRACT FROM AUTHOR]

Inductively coupled plasma dry etching of epitaxially grown aluminum nitride (AlN) film using Cl 2 /BCl 3 /Ar mixture has been investigated. The etch rate of AlN increases significantly with the addition of BCl 3 , and an etch rate as high as 258 nm/min has been demonstrated. High selectivity of AlN over Ni mask has been realized, and the etch rate of Ni is almost zero for lower bias voltage. By optimizing the etching parameters, grain formation due to crystallographic orientation dependent etching has been suppressed, and smooth etched surfaces and nearly vertical sidewalls are obtained. The root-mean-square roughness of the etched surface is measured to be 0.77 nm, which is almost the same as that of the as-grown surface. These results are suitable for the fabrication of low-loss AlN waveguides and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: Control of mixed convection (combined forced and natural convection) in a lid-driven square cavity is performed using a short triangular conductive fin. A numerical technique is used to simulate the flow and temperature fields. The vertical walls of the cavity are differentially heated. Both the top lid and the bottom wall are adiabatic. The fin is located on one of the motionless walls of the cavity. Three different cases have been studied based on the location of the fin. In this context, Cases I, II and III refer to the fin on the left, bottom and right walls, respectively. Results are presented for +x and −x directions of the top lid in horizontal axis and different Richardson numbers as Ri =0.1, 1.0 and 10.0. It is observed that the triangular fin is a good control parameter for heat transfer, temperature distribution and flow field. [ABSTRACT FROM AUTHOR]

Abstract: Conjugate heat transfer by mixed convection and conduction in lid-driven enclosures with thick bottom wall has been studied by a numerical method. The enclosure is heated from the bottom wall isothermally. Temperature of the top moving wall, which has constant flow speed, is lower than that of the outside of bottom wall. Vertical walls of the enclosure are adiabatic. Governing parameters are solved for a wide range of Richardson numbers (0.1≤ Ri ≤10), ratio of height of bottom wall to enclosure height (0.1≤ h/H ≤0.5) and thermal conductivity ratio (0.01≤ λ f/λ s ≤10). Obtained results showed that heat transfer decreases with increasing of λ f/λ s ratio, Richardson number and thickness ratio of the wall. Flow strength is affected for only higher values of λ f/λ s ratio. [Copyright &y& Elsevier]

NiCrAlO/Al 2 O 3 solar selective coating prepared by direct current (DC) magnetron sputtering and water boiling is demonstrated in this paper. Firstly, the coating consisting of tandem layers of Au/NiCrAl/Al with different NiCr volume fractions in NiCrAl sublayers is deposited solely by DC magnetron sputtering. Then the coating is boiled by deionized water and dehydrated by vacuum heating. The surface morphology, the depth distributions and relative chemical states of elements of the coating are characterized by scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It is found that Al in the coating is totally oxidized while most of NiCr and Au keep metallic after water boiling and vacuum dehydration, which forms the effective solar selective coating consisting of Au/NiCrAlO/Al 2 O 3 with different metallic NiCr volume fractions. High near normal solar absorptance of 0.964 and low near normal thermal emittance of 0.066 are demonstrated by the reflectance measured by UV-VIS-IR spectrometer. The combination of DC magnetron sputtering and water boiling is very promising for fabrication of solar selective coating based on the dielectric aluminum oxide, as it is environmentally friendly and circumvents the radio frequency (RF) magnetron sputtering which needs RF automatic matching. • NiCrAlO/Al 2 O 3 coating prepared by DC magnetron sputtering and water boiling. • Al is oxidized to dielectric while NiCr keep metallic after water boiling. • High solar absorptance of 0.964 and low thermal emittance of 0.066. [ABSTRACT FROM AUTHOR]

Highlights • Nano-crystalline Si thin film was fabricated by Si-Al co-sputtering and thermal annealing. • p+-n thin film Si solar cell was fabricated by sputtering and thermal annealing in three steps. • A model was proposed for describing aluminum-induced crystallization by co-sputtering (AICCS). • It was shown that AICCS is simpler and eco-friendlier than aluminum layer exchange (ALILE). Abstract Fabrication of nano-crystalline thin film solar cell by co-sputtering of silicon and aluminum, and metal induced crystallization is reported in this paper. After a brief introduction on magnetron sputtering and aluminum-induced crystallization techniques, it discusses the drawbacks of "aluminum induced layer exchange" concept as the common method for fabricating poly-Si thin films; and proposes Si-Al co-sputtering as a simple alternative fabrication method. Then a three-steps process is introduced for the fabrication of "Al electrode/n-Si wafer/p-Si thin film/Al electrode" solar cell. Material and electrical characterizations of the fabricated p-Si thin films are done by Raman spectroscopy, X-ray diffraction, optical microscopy, scanning electron microscopy and Hall Effect measurement to study the crystallization ratio, grain size, morphology, carrier density and mobility of the prepared films, respectively. The best fabricated samples show a crystallization ratio of 88% and the largest grain size of 68 nm. The hole concentration in the films is in the order of 1018 to 1019 cm−3 with a maximum mobility value of 17 cm2/V s. Then, photovoltaic properties of the fabricated solar cells are determined by under dark and illumination J-V curves, and external quantum efficiency measurements. Dark J-V curve of the best sample represents an ideality factor of 1.39, rectification ratio of 1993 at ±1 V and reverse saturation current density of 62.1 nA/cm2 which confirms the formation of a good p-n junction. The illuminated J-V curve under AM1.5G conditions exhibits a photovoltaic conversion efficiency of 6.02% for the best sample, with a short circuit current density of 24.9 mA/cm2 and open circuit voltage of 456 mV. The external quantum efficiency of this sample reaches to more than 59% at the wavelength of 700 nm. Finally, a simple model is proposed to describe the formation of nano-crystalline Si thin film, deposited by Si-Al co-sputtering, during the thermal annealing. [ABSTRACT FROM AUTHOR]

GaN epilayers are globally grown on amorphous glass substrates via a compound buffer layer including Ti pre-orienting layer and AlN nucleation layer (NL) grown by molecular beam epitaxy at 530 °C. It is shown that the ratio of V/III during AlN growth plays a key role in the crystallinity of AlN NL as a trade-off between the formation of Al clusters and the mobility of Al adatoms. The N 2 flux has an optimal value of 2.4 sccm when the Al flux is fixed to 7.46 × 10 −8  Torr at the RF power of 400 W. The obtained smooth GaN epilayer is hexagonal single-crystalline with the grain size in the order of submicron magnitude and root-mean-square roughness of 2.83 nm, which shows the great potential in the epitaxy of III-nitrides on amorphous glass substrates. [ABSTRACT FROM AUTHOR]

Solar cells consist of n-Si wafer and p-Si polycrystalline thin film, which was solely fabricated by magnetron sputtering, and aluminium induced crystallization, are presented in this paper. Firstly, the material and electrical properties of the fabricated p-Si thin films including the crystallization ratio, grain size, morphology, carrier density and mobility were studied by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy and Hall Effect measurement, respectively. The p-Si polycrystalline thin film formed under optimal process conditions had the crystallization ratio of ~ 99% and the grain size of ~ 64.6 nm, determined from the data of Raman spectroscopy and XRD. The hole concentration in the fabricated p-Si polycrystalline thin films was mainly in the order of 10 17 cm −3 to 10 19 cm −3 , and their corresponding mobility values ranged from 15 cm 2 /V s to 65 cm 2 /V s. Then solar cells with the device structure of Al electrode/n-Si wafer/p-Si thin film/Al electrode were fabricated, and their electrical properties were measured both under dark and illumination conditions by the semiconductor performance tester and solar simulator. The measured J-V curves under dark condition confirmed the creation of a p-n junction with the ideality factor of 1.55, rectification ratio of 410 at ± 1 V, and the reverse saturation current of 246 nA/cm 2 . The efficiency of 2.19%, with an open circuit voltage of 448 mV and a short circuit current density of 11.2 mA/cm 2 , was achieved under AM1.5G standard illuminations. [ABSTRACT FROM AUTHOR]

Although GaN-based materials have been successfully utilized in optoelectronic and electronic devices, some important physical issues have not been fully understood, for example, why they can have high luminous efficiency even with high density of point defects, and what are the origins of yellow luminescence (YL) in their photoluminescence (PL) spectra. In this paper, the influence of point defects on GaN-based materials are investigated by first principle calculation. It is revealed that vacancy defects in GaN-based materials only make the effective masses of electrons and holes increase, consequently they have no significant contribution on the non-radiative recombination. What is more, C O complex interstitial impurities or Ga interstitial impurities are most likely to lead to YL in PL spectra of GaN-based materials. [ABSTRACT FROM AUTHOR]

The highly c-oriented titanium (Ti) film is deposited on glass substrates by electron beam (EB) evaporation based on the study of effects of the substrate temperature (T s ) and deposition rate (R d ) on its properties. It is found that the T s is the critical parameter and the R d. is also important to the crystallization and surface morphology of EB-evaporated Ti film. The crystal orientation, grain size and surface smoothness are optimized if the migration time of Ti adatoms affected by the R d. matches to their surface mobility affected by T s . Besides, the Ti film thickness (T f ) is also exist an optimization range to achieve hexagonal c-oriented titanium film. The highly c-orientated (002) hexagonal and smooth Ti film, whose mean grain size and root mean square roughness are approximately 250 nm and 1.54 nm respectively, is realized with T s of 300 °C and R d. of approximately 0.5 nm/s when the thickness is 300 nm. The single crystalline characteristics of individual Ti grains are demonstrated, and GaN grown on Ti film/glass substrate by molecular beam epitaxy at 530 °C has the same epitaxial relationship to Ti film. It means that Ti film deposited by EB evaporation with appropriate T s and R d. can acts as the template of GaN epitaxy on glass substrate under the suitable thickness. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of resistance-spot-welded A5052 aluminum alloy and DP 600 dual-phase steel joint were studied. The fusion zone (FZ) and heat-affected zone (HAZ) of DP 600 exhibited lath martensite and ferrite-martensite structures, respectively. The microstructure of FZ and HAZ in the A5052 side was composed of cellular crystals and the boundary region of FZ exhibited a columnar crystal morphology. A Fe 2 Al 5 intermetallic compound (IMC) layer with 3.3 μm thickness was found adjacent to the DP 600 side, whereas a needle-shaped Fe 4 Al 13 IMC layer with length of 0.67 μm to 15.8 μm was found adjacent to the aluminum alloy side. The maximum tensile shear load of the A5052/DP 600 joint was 5.5 KN, with a corresponding molten nugget diameter of 6.3 mm. The fracture morphology of the optimized A5052/DP 600 joint was mainly an elongated dimple fracture accompanied by cleavage fracture. [ABSTRACT FROM AUTHOR]

NiCr–MgF 2 spectrally selective solar absorber, which consists of the tandem films of Au, high-metal-volume-fraction (HMVF) NiCr–MgF 2 , low-metal-volume-fraction (LMVF) NiCr–MgF 2 and MgF 2 , is designed and fabricated for ultra-high solar absorptance and low thermal emittance. The performance of Au/NiCr–MgF 2 (HMVF)/NiCr–MgF 2 (LMVF)/MgF 2 is simulated using the effective medium theory and film matrix method, and the optimized NiCr–MgF 2 spectrally selective solar absorber has a normal solar absorptance (α sn) of 0.981 and a normal thermal emittance (ε n) of 0.042 at 25 °C. The tandem films of Au/NiCr–MgF 2 (HMVF)/NiCr–MgF 2 (LMVF)/MgF 2 are fabricated by magnetron sputtering and measured by UV-VIS-IR spectrometer, and it has an ultra-high near normal solar absorptance of α sn = 0.976 and a low near normal thermal emittance of ε n = 0.045 at 25 °C, which approaches very closely to the simulated limit. Furthermore, NiCr–MgF 2 spectrally selective solar absorber allows a wide incident angle (θ) with its angular solar absorptance α s (θ)≥0.957 and angular thermal emittance ε (θ)≤0.054 if θ ≤ 50°. Such spectrally selective solar absorber is an outstanding candidate for solar thermal applications. • A novel NiCr–MgF 2 cermet based solar absorber are deposited. • Ultra-high solar absorptance of 0.976 and low thermal emittance of 0.045. • Wide incident angle of 50° with α s (θ)≥0.957 and ε (θ)≤0.054. [ABSTRACT FROM AUTHOR]