On the I–V measurement of dye-sensitized solar cell: Effect of cell geometry on photovoltaic parameters

The effect of mask aperture size with respect to dye-adsorbed TiO₂ area on the response of photocurrent, voltage, fill factor and efficiency of dye-sensitized solar cell (DSSC) was recently studied by Gratzel's research group [S. Ito, Md. K. Nazeeruddin, P. Liska, P. Comte, R. Charvet, P. Pechy, M. Jirousek, A. Kay, S.M. Zakeeruddin, M. Grätzel, Prog. Photovolt. Res. Appl. 14 (2006) 589], where it was proposed that overall efficiency could be overestimated when measuring a DSSC without mask having adequate aperture size. In this report, beside the aperture size, we have studied effects of glass substrate thickness and geometry, thickness and layer structure of TiO₂ film on photovoltaic parameters. Photovoltaic parameters, mostly photocurrent density, were found to be significantly influenced by the glass substrate thickness and the TiO₂ layer structure. Data analysis suggests that photovoltaic characteristics before and after mask are dependent not only on measuring condition such as mask aperture size but also on substrate thickness and TiO₂ layer structure.     

Thermal shock resistance analysis methodology of ceramic coating/metal substrate systems

The paper establishes a methodology for the study of thermal shock resistance behavior of ceramic coating/metal substrate systems, based on multiple cracking analysis. The stress criterion and the toughness criterion are used to predict the failure behavior of the system. Multi-scale analysis of the thermal shock resistance of the system is made and variations of the thermal shock resistance of the system with crack density are displayed for different values of coating to substrate thickness ratio. Some critical size parameters, which control the applicability of the stress-based criterion and the fracture mechanics-based criterion for the determination of the thermal shock resistance of the coating/substrate systems, are explored.     

Immobilization of aromatic aldehyde molecules on indium tin oxide surface using acetalization reaction

We demonstrated an acetalization reaction as a versatile method to immobilize aromatic aldehyde molecules on surfaces of metal oxides, silicon dioxide, and indium tin oxide. First, a trimethylsily (TMS) terminated surface was formed using a silylation reaction between a chloride group of trimethylsilychloride and a hydroxyl group of the substrate surfaces. Second, terephthalaldehyde (TPA) was immobilized on the surfaces using an acetalization reaction between the TMS-terminated surface and an aldehyde group of TPA. Results of contact angle, X-ray photoelectron, and ultraviolet absorption spectra revealed that the TPA molecules on the surfaces were well-packed with a high surface density.     

碲镉汞外延用衬底材料的现状和发展

文章综合论述了碲镉汞外延用的衬底材料的现状,着重介绍了几种衬底材料CdTe、 Al2O3、GaAs、Ge、Si等的性能特点与各自的优缺点,评述了它们在碲镉汞外延中的使用情况,并对其未来的发展方向做出了预测。     

Low-temperature deposition of iridium thin films by pulsed laser deposition

Extremely smooth iridium (Ir) thin films were deposited on Si(1 0 0) substrate at lower temperature than 300 °C by pulsed laser deposition (PLD) technique using Ir target in a vacuum atmosphere. The crystal orientation, surface morphology, and resistivity of the Ir thin films were systematically determined as a function of substrate temperature. Well-crystallized and single-phase Ir thin films with (1 1 1) preferred orientation were obtained at substrate temperature of 200-300 °C. The surface roughness increased with the increasing of substrate temperature. Likewise, the room-temperature resistivity of Ir thin films decreased with increasing substrate temperature, showing a low value of (10.7±0.1) μΩ cm at 300 °C.     

Effects of sediment and flow regime on the aquatic insects of a high mountain stream

In 1984, a broad size range of sediment (boulder to sand) was introduced into a high elevation Rocky Mountain stream in southeastern Wyoming, U.S.A. In the spring of 1986, this stream was exposed to a high discharge of 7.5 m³ s⁻¹. From 1985 to 1987 a study was conducted to assess the impact of sediment deposition and flow regime on the aquatic insect community in context of the substrate occurrences of the insect fauna. Using a modified Surber sampler, samples were collected from June through September each year at nine stations which were rated as unimpacted, slightly-impacted, and impacted. The addition of the sediment had minimal effect on the abundance and diversity of aquatic insects. However, high water discharge severely reduced the abundance of aquatic insects and diversity was also negatively impacted. Recovery from these impacts was very rapid. The greatest insect abundance was found in samples taken in gravel and most taxa occurred predominantly on gravel or rubble substrates.     

衬底温度对蒸汽辅助沉积法制备钙钛矿薄膜微观结构的影响

通过调控薄膜生长衬底温度,提出了一种改良的蒸汽辅助沉积法制备有机-无机混合钙钛矿薄膜,可以更为可控优化薄膜生长条件。用同步辐射掠入射X射线衍射(Grazing Incidence X-ray Diffraction,GIXRD)结合扫描电镜(Scanning Electron Microscope,SEM)、紫外可见吸收谱(UV-Visible Absorption Spectrum)等表征方法证明衬底温度对制备的钙钛矿薄膜质量具有重要的作用:较低的衬底温度(约70?C)有助于钙钛矿晶粒的形成,其结晶性、晶面择优生长取向均较好,同时具有较高的光吸收性能;当衬底温度升高时(100?C、125?C),所制备的钙钛矿薄膜结晶性变弱,晶体择优生长取向明显变差,光吸收性能随之下降。研究结果有助于进一步优化蒸汽辅助沉积法制备钙钛矿薄膜工艺。     

Substrate temperature influence on boron carbide coatings grown by the PLD technique

Boron carbide films were synthesized by laser ablation technique, using a target of B₄C with 99.9% of purity, varying the substrate temperature between room temperature and 650 °C, in order to produce the hexagonal phase (h-BC). Films were grown on (111)-silicon wafers in an ultra high vacuum system with a base pressure in the order of 10^− 7 Pa. For the films' growth, an atmosphere of (CH₄) at a pressure of 2.5 Pa was used. During the process, the substrate temperature was varied in order to identify the influence of this parameter on the coatings' structure, composition and morphology. XRD analysis did not present peaks of BC, possibly because of the amorphous character of the film that has different phases. Films were characterized by several techniques as in situ Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and ex situ electron diffraction. Results present a concentration of 50 at.% for the sample grown to 650 °C. Electron diffraction showed an interplanar spacing (d₍₀₀₂₎ = 0.334 nm) and also other hkl reflections have been identified. Lattice parameters calculated from the interplanar spacing a = 0.585 nm and c = 1.2 nm obtained for the sample grown at 650 °C are similar to those reports for hexagonal boron carbide.     

Inhibitory effects of substrate and soluble end products on biohydrogen production of the alkalithermophile Caloramator celer: Kinetic,metabolic and transcription analyses

In this study the tolerance of the alkalithermophile Caloramator celer towards substrate (glucose) and soluble end product (acetate, formate and ethanol) inhibition was assessed employing nonlinear inhibition models. In addition, the effects of subinhibitory concentrations of end products on fermentative metabolism and regulation of 12 key genes involved in pyruvate catabolism were studied. Optimal growth and H₂ production were found at 50 mM of glucose and the critical substrate concentration was observed at 290–360 mM. Two inhibition models revealed that ethanol had a higher inhibitory effect on growth rate, whereas H₂ production kinetics was more sensitive towards increasing concentrations of acetate and formate. Acetate, the main soluble metabolite of the fermentation, inhibited the H₂ production by increasing the ionic strength in the medium. Subinhibitory concentrations of soluble end products induced changes in the metabolite profile of C. celer, specifically exogenous acetate (80 mM) and ethanol (40 mM) slightly increased the H₂ yield by 4 and 7%, respectively. However, despite the observed metabolic shifts, gene regulation was minimal and not always in agreement with the measured product yields. Overall, the results suggest that further optimization of the H₂ production process from C. celer should focus on methods to evolve adapted osmotolerant strains and/or remove soluble metabolites, especially acetate, from the culture.     

Topology awareness algorithm for virtual network mapping

Network virtualization is recognized as an effective way to overcome the ossification of the Intemet.However,the virtual network mapping problem (VNMP) is a critical challenge,focusing on how to map th...