用背反射提高染料敏化太阳能电池光电转换效率的研究

当光射入染料敏化太阳能电池(DSCs)时,有部分光不能被染料、电解液、导电玻璃等吸收,这部分光将透过电池而未被利用,本研究利用普通镀铝玻璃镜做为背底,将这部分透射光通过背反射重新射入电池来提高DSCs的光电转换效率.研究结果表明,背反射能大幅度提高DSCs的短路电流,短路电流的增加率随着测试遮光罩开孔尺寸的增加而增加,并且随纳米TiO2薄膜厚度的增加而降低.     

Systemic administration of atipamezole, a selective antagonist of alpha-2 adrenoceptors, facilitates behavioural activity but does not influence short-term or long-term memory in trimethyltin-intoxicated and control rats

The present study used trimethyltin (TMT)-intoxicated rats as a model for the behavioural syndrome seen after neuronal damage to the limbic system. Behavioural assessments indicated increased locomotor activity and reduced number of groomings in an open-arena task in TMT-intoxicated (6.6 mg/kg as a free base) rats, as has been found previously. A novel finding was the severe deficit in swimming to a visible platform in the water maze task, with reduced swimming speed at the beginning of the training period. During the reacquisition phase of a radial arm maze task, TMT-intoxicated rats made more short-term and long-term memory errors, and their behavioural activity was increased in comparison with controls. The administration of atipamezole (300 micrograms/kg), a selective antagonist of alpha 2-adrenoceptors, enhanced locomotor activity compared to saline-treated rats, but these effects did not differ between the TMT group and their controls. Atipamezole did not enhance short-term or long-term memory in either TMT or control groups. Taken together, the present data indicate that TMT intoxication is a model for global dementia rather than for a specific loss of relational memory. Previous studies on the neurochemical effects of TMT and the alleviation or prevention of neurotoxicity of TMT are reviewed.     

Hafnium clad fuels for fast spectrum BWRs

We show that by use of hafnium cladding, a fast neutron spectrum is achievable in the top of uprated BWRs. Monte Carlo calculations have been made for Hf clad inert matrix nitride and low fertile MOX fuels, with fuel segments located in the upper part of an uprated BWR, where the coolant void fraction exceeds 70%. The nitride fuel results in the hardest neutron spectrum, but the low fertile MOX fuel still yields fission probabilities for even neutron number nuclides similar to those of sodium cooled reactors. The inert matrix nitride fuel configuration yields high burning rates, permitting to stabilise TRU inventories with less than 50% BWR cores of the here suggested type in the power park. The core with low fertile MOX fuel is less efficient, but still a zero net producer of TRU. Fuel and coolant temperature feedbacks are affected by introduction of absorbing elements in the fuel, but remain within acceptable ranges for the low fertile MOX fuel. Although control rod worths are reduced, shutdown margins are sufficient to ensure sub-criticality in cold conditions. From a materials point of view, the behaviour of hafnium clad MOX fuel would be similar to zircalloy clad MOX fuel already used extensively in nuclear industry. Thus, if dynamic stability of the core can be ensured, the here proposed fuel may be considered as a low cost solution for transmutation of minor actinides on industrial scale.     

Enhanced conductivity of SDC based nanocomposite electrolyte by spark plasma sintering

Recently, ceria-based nanocomposites have been considered as promising electrolyte candidates for low-temperature solid oxide fuel cells (LTSOFC) due to their dual-ion conduction and excellent performance. However, the densification of these composites remains a great concern since the relative low density of the composite electrolyte is suspected to deteriorate the durability of fuel cell. In the present study, the ionic conductivity of two kinds of SDC-based nanocomposite electrolytes processed by spark plasma sintering (SPS) method was investigated, and compared to that made by conventional cold pressing followed by sintering (normal processing way). The density of solid electrolyte can reach higher than 95% of the theoretical value after SPS processing, while the relative density of the electrolyte pellets by normal processing way can hardly approach 75%. The structure and morphology of the sintered pellets were characterized by XRD and SEM. The ionic conductivity of samples was measured by electrochemical impedance spectroscopy (EIS). The results showed that the ionic conductivity of the two kinds of electrolytes treated with SPS was significantly enhanced, compared with the electrolyte pellets processed through the conventional method. The profile of impedance curve of the electrolytes was altered as well. This study demonstrates that the conductivity of SDC based nanocomposite electrolyte can be further improved by adequate densification process.     

Young citizens’ knowledge and perceptions of bioenergy and future policy implications

In the past few years extensive discussions on bioenergy has been both positive and negative. In Europe, the image of bioenergy appears to be low with lack of broad public support. Previous studies show that younger people are unsure about many issues surrounding renewable energy. The aim of this study was to investigate the knowledge and perceptions of bioenergy among pupils in North Karelia, Finland. Data drawn from 495 ninth grade students indicate that the majority of them lack in-depth knowledge about different renewable energy sources, including bioenergy. Only a small percentage has a ‘high’ level of knowledge about bioenergy and the majority indicates critical perceptions of it. Statistically significant gender differences are not apparent. Girls appear to be more knowledgeable than boys. Results also show a clear ‘urban’ and ‘rural’ difference in perceptions of bioenergy. Perceptions of urban respondents being more positive than that of their rural counterparts. Developing collaboration between future bioenergy policies and bioenergy education for younger citizens is necessary for their engagement in critical debates on bioenergy.     

Charge transfer resistance of spray deposited and compressed counter electrodes for dye-sensitized nanoparticle solar cells on plastic substrates

Electrochemical impedance spectroscopy was used to determine the effective charge transfer resistances of porous dye-sensitized solar cell counter electrodes prepared by low-temperature spray deposition and compression of conductive carbon and platinized Sb-doped SnO₂ powders on indium tin oxide-coated plastic substrates. The charge transfer resistances were 0.5–2 and 8–13 Ω cm², respectively, when using 3-methoxypropionitrile as the electrolyte solvent. The manufacturing method used lends itself to produce mechanically stable and even-quality electrodes in an easy and fast manner.     

Comparative analysis of ceramic-carbonate nanocomposite fuel cells using composite GDC/NLC electrolyte with different perovskite structured cathode materials

A comparative analysis of perovskite structured cathode materials, La_0.65Sr_0.35MnO₃ (LSM), La_0.8Sr_0.2CoO₃ (LSC), La_0.6Sr_0.4FeO₃ (LSF) and La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF), was performed for a ceramic-carbonate nanocomposite fuel cell using composite electrolyte consisting of Gd_0.1Ce_0.9O_1.95 (GDC) and a eutectic mixture of Na₂CO₃ and Li₂CO₃. The compatibility of these nanocomposite electrode powder materials was investigated under air, CO₂ and air/CO₂ atmospheres at 550 °C. Microscopy measurements together with energy dispersive X-ray spectroscopy (EDS) elementary analysis revealed few spots with higher counts of manganese relative to lanthanum and strontium under pure CO₂ atmosphere. Furthermore, electrochemical impedance (EIS) analysis showed that LSC had the lowest resistance to oxygen reduction reaction (ORR) (14.12 Ω·cm²) followed by LSF (15.23 Ω·cm²), LSCF (19.38 Ω·cm²) and LSM (>300 Ω·cm²). In addition, low frequency EIS measurements (down to 50 µHz) revealed two additional semi-circles at frequencies around 1 Hz. These semicircles can yield additional information about electrochemical reactions in the device. Finally, a fuel cell was fabricated using GDC/NLC nanocomposite electrolyte and its composite with NiO and LSCF as anode and cathode, respectively. The cell produced an excellent power density of 1.06 W/cm² at 550 °C under fuel cell conditions.     

Aerosol analysis of residual and nanoparticle fractions from spray pyrolysis of poorly volatile precursors

The quality of aerosol‐produced nanopowders can be impaired by micron‐sized particles formed due to non‐uniform process conditions. Methods to evaluate the quality reliably and fast, preferably on‐line, are important at industrial scales. Here, aerosol analysis methods are used to determine the fractions of nanoparticles and micron‐sized residuals from poorly volatile precursors. This is accomplished using aerosol instruments to measure the number and mass size distributions of Liquid Flame Spray‐generated alumina and silver particles produced from metal nitrates dissolved in ethanol and 2‐ethylhexanoic acid (EHA). The addition of EHA had no effect on silver, whereas, 5% EHA concentration was enough to shift the alumina mass from the residuals to nanoparticles. The size‐resolved aerosol analysis proved to be an effective method for determining the product quality. Moreover, the used on‐line techniques alone can be used to evaluate the process output when producing nanopowders, reducing the need for tedious off‐line analyses. © 2016 American Institute of Chemical Engineers AIChE J, 63: 881–892, 2017     

The effect of water‐soluble polymers on rheology of microfibrillar cellulose suspension and dynamic mechanical properties of paper sheet

Rheological properties of fiber/polymer suspensions and dynamic mechanical analysis (DMA) of paper sheets containing the same polymers were measured. Correlations between viscoelastic properties of suspensions and strength of paper sheet are presented. Rheological properties of suspensions of microfibrillar cellulose (MFC) and a set of water soluble polymers were measured. Rheological properties of these complex fluids vary considerably depending on the added polymer. A suspension of fiber and carboxymethyl cellulose (CMC) exhibits a viscosity higher than the sum of the viscosity of the individual components in the suspension. In contrast, when cationic starch (CS) is used together with the fiber, the yielding behavior rather than the viscosity is characteristic of the suspension. Dynamic mechanical properties of paper sheets containing CMC or CS as additives were studied at different humidity levels. Different yielding behavior observed in oscillatory rheology can be correlated with straining behavior in dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Miscibility,morphology and mechanical properties of rubber‐modified biodegradable poly(ester‐urethanes)

Biodegradable, lactic acid based amorphous poly(ester‐urethane)s (PEU) were modified with poly(L‐lactic acid‐co‐ϵ‐caprolactone‐urethane) elastomer (P[LA/CL]U) by melt blending. The phase separation of P(LA/CL)U elastomer with three different ϵ‐caprolactone (CL) compositions (CL content 30, 50, and 70 mol %) and the mechanical properties of the resulting impact‐modified linear and branched PEU were investigated. The amounts of P(LA/CL)U elastomer in the PEU blends were 10, 15, 20, and 30 wt %. Dynamic mechanical thermal analysis (DMTA) of the blends with P(LA50/CL50)U and P(LA30/CL70)U elastomers revealed separate glass transition temperatures for rubber and matrix, indicating phase separation. No phase separation was found for P(LA70/CL30)U elastomer. The effect of mixing rate and temperature during processing on composite properties was tested by blending P(LA30/CL70)U rubber with PEU under various processing conditions. Impact modification studies were also made with two P(LA30/CL70)U elastomers having different amounts of functional groups. The influence of end‐functionalization and cross‐linking on mechanical properties was investigated in blends containing PEU and 15 wt % of these elastomers. Scanning electron microscopy (SEM) showed the morphology to change dramatically with increase in the degree of cross‐linking in the rubber. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1074–1084, 2000