Vaporization and condensation in the Al4C3-SiC system

Al₄SiC₄ is a refractory ceramic with a reported band gap of about 2.5 eV, making it an interesting semiconductor material for various applications in the field of energy. However, the synthesis of Al₄SiC₄ single crystals has so far not been investigated. In this study, the sublimation growth method is explored as a potential route for getting high quality single crystals. Combining a thermodynamic analysis with an extensive experimental approach, the vaporization and condensation phenomena in the Al₄C₃ – SiC system are described. Experimental conditions, such as initial composition, baking temperature and temperature gradient, are investigated and demonstrated regarding the crystallization of Al₄SiC₄. From the results obtained, a condensed phase diagram at equilibrium is established for the molar fraction X_{Al4C3/(Al4C3+SiC)} < 0.5, which corresponds to the suitable condition for the Al₄SiC₄ condensation. Indeed, Al₄SiC₄ single phase could be experimentally condensed either by self-nucleation or as oriented film on SiC substrates.     

Role of fullerene electron transport layer on the morphology and optoelectronic properties of perovskite solar cells

High performance, hysteresis-free, low temperature n-i-p perovskite solar cells are successfully fabricated by solution processing using fullerene electron transport layer (ETL). PC₇₁BM fullerene, with broader absorption spectrum and lower HOMO level, when incorporated in the perovskite solar cell yielded average power conversion efficiency (PCE) of 13.9%. This is the highest reported PCE in n-i-p perovskite solar cells with PC₇₁BM ETL. The devices exhibited negligible hysteresis and high open-circuit voltage (V_oc). On the contrary, devices with PC₆₁BM, a common fullerene ETL in perovskite solar cell, exhibited large hysteresis and lower V_oc. The underlying mechanisms of superior performance of devices with PC₇₁BM ETL were found to be correlated with fullerene surface wettability and perovskite grain size. The influence of fullerene ETL on the perovskite grain growth and subsequent photovoltaic performance was investigated by contact angle measurement, morphological characterization of the surface topography and electrochemical impedance analysis.     

Photocatalytic degradation and hydrogen evolution using bismuth tungstate based nanocomposites under visible light irradiation

In this work, Bi₂WO₆/PANI composites were synthesized for efficient removal of ciprofloxacin (CIP) from urban wastewater and production of hydrogen energy in the absence of sacrificial agents. The experimental study visualizes the formation of 2D based nanostructures and perceived that these nanostructures could provide more photocatalytic active-sites for removal of CIP and also increase the oxidation/reduction of water for hydrogen energy production. The PXRD showed excellent crystallinity/orthorhombic structure with crystallite size 10–23 nm. The Bi₂WO₆/PANI composites, compared to Bi₂WO₆, exhibited higher efficiency and stability for degradation of CIP and production of hydrogen energy. CIP was effectively degraded 98% by Bi₂WO₆/PANI (5%) and the effect of different parameters such as pH, catalyst-concentration, and effect of CIP-concentration was also analyzed. The hydrogen energy rate was 490.56 h⁻¹g⁻¹ by using Bi₂WO₆/PANI (5%). The improved photocatalytic performance of Bi₂WO₆/PANI composite was mainly ascribed to the unique hierarchical structures, harvesting extended absorption of visible light, higher surface area, and higher crystallinity. The current findings may provide new insights to fabricate nanomaterials for environmental and energy issues.     

Transforming waste sugar solution into N-doped hierarchical porous carbon for high performance supercapacitors in aqueous electrolytes and ionic liquid

Waste sugar solution is a by-product in the process of manufacturing vitamin C. Nowadays, the unused industrial waste residues are transformed into high efficient energy storage devices, such as supercapacitors electrodes, which are worth exploring because they are consistent with the concept of green and sustainable development. In this paper, a nitrogen-doped hierarchical porous carbon are obtained via pre-carbonization and KOH activation. The as-prepared material, possessed proper pore size distribution, large specific surface area and nitrogen-doping, exhibits good electrochemical performance, such as a high specific capacitance of 342 F g⁻¹ (0.1 A g⁻¹), good stability with 95% capacitance retention after 15,000 cycles in 6 M KOH. Moreover, the supercapacitors deliver a high energy density of 25.6 and 65.9 W h kg⁻¹ in the 1 M Na₂SO₄ and EMIMBF₄, respectively. The good electrochemical performance illustrates that the nitrogen-doped hierarchically porous carbon derived from the waste sugar solution is a potential candidate for energy storage.     

Kinetics of ceramic particulate penetration into spray atomized metallic droplet at variable penetration depth

The present study provides insight into the physical interactions that take place when an injected ceramic particulate collides with an atomized metallic droplet during spray atomization and deposition processing of particulate reinforced metal matrix composites. A model is developed to predict the extent of penetration for a given particulate velocity, and the critical velocity for complete penetration. In the model, the initial kinetic energy of the injected particulates or the atomized droplets is considered as the driving force for penetration; the change in surface energies and the work done by viscous drag in the droplet melt are considered as the forces resisting penetration. As examples, Al/graphite and Al/SiC systems are analyzed to demonstrate the applicability of the model. The influence of the particulate size and the fraction of solid phase in the atomized droplet on the critical velocity and the penetration depth is also examined.     

Fabrication of superhydrophilic and antireflective silica coatings on poly(methyl methacrylate) substrates

Silica nanoparticles of ca. 20 nm in size were synthesized, from which hierarchically porous silica coatings were fabricated on poly(methyl methacrylate) (PMMA) substrates via layer-by-layer (LbL) assembly followed by oxygen plasma treatment. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 99%, whereas that of the PMMA substrate is only 92%. After oxygen plasma treatment, the time for a water droplet to spread to a contact angle of lower than 5° decreased to as short as 0.5 s. Scanning and transmission electron microscopy were used to observe the morphology and structure of nanoparticles and coating surfaces. Transmission and reflection spectra were recorded on UV–vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.     

BESⅢ主漂移室模拟真实化调试研究

以BESⅢ上开发的主漂移室模拟软件为基础,仔细研究并建立了一套规范、有效的主漂移室模拟真实化调试方法。该方法基于对主漂移室响应机制以及真实数据中探测器工作状态的深入理解,建立恰当的参数化模型,通过调试丝击中效率及丝空间分辨,实现主漂移室模拟真实化。论文介绍了BESⅢ主漂移室模拟真实化调试的原理、利用真实数据进行调试的过程以及调试的性能表现。采用这套调试方法,通过调试丝击中效率和空间分辨可以获得恰当的探测器模拟输入参数,使模拟数据与真实数据径迹重建效率的差异达到1%的水平。     

磷酸三丁酯从盐湖卤水中萃取锂的机理研究

以磷酸三丁酯（TBP）为萃取剂,磺化煤油为稀释剂,在六水合三氯化铁存在的条件下,从盐湖卤水中萃取锂。研究了TBP浓度对萃取率的影响,得到TBP最佳浓度为80%TBP+20%磺化煤油。通过斜率法、化学分析法、紫外光谱与红外光谱法,证实了锂离子（Li+）在溶液中与铁络阴离子（FeCl4-）形成铁氯络酸盐（LiFeCl4）,LiFeCl4与TBＰ中的PO键作用配位形成二溶剂化物LiFeCl4·2TBP,从而达到与其他组分分离的目的。利用空腔理论阐述了萃取过程。     

Modeling business risk: The effect of regulatory revision on renewable energy investment - The Iberian case

Regulatory risk is commonly accepted as one of the most important risks in the energy business, particularly renewable energy. With the recent changes (in June 2014) in the Spanish regulatory framework, investors' returns might be significantly affected. Further, as the Spanish and the Portuguese electricity systems are integrated, a change in the regulatory framework of Spain might also affect renewable energy policies and investment strategies in Portugal. This study is a projection of business risk under the assumption that the Portuguese government may adopt similar regulatory changes. Monte Carlo method is used to simulate the data under different scenarios. Applying Net Present Value and Real Options approaches, a 50 MW wind power project is evaluated. This study has considered the delay option to study five regulatory scenarios. A higher value for the delay option suggests that a high financial loss is expected if new wind power projects of similar capacity are implemented under the new regulatory framework.