Review on zirconate-cerate-based electrolytes for proton-conducting solid oxide fuel cell

The performance of low-to-intermediate temperature (400–800?°C) solid oxide fuel cells (SOFCs) depends on the properties of electrolyte used. SOFC performance can be enhanced by replacing electrolyte materials from conventional oxide ion (O^2-) conductors with proton (H⁺) conductors because H⁺ conductors have higher ionic conductivity and theoretical electrical efficiency than O^2- conductors within the target temperature range. Electrolytes based on cerate and/or zirconate have been proposed as potential H⁺ conductors. Cerate-based electrolytes have the highest H⁺ conductivity, but they are chemically and thermally unstable during redox cycles, whereas zirconate-based electrolytes exhibit the opposite properties. Thus, tailoring the properties of cerate and/or zirconate electrolytes by doping with rare-earth metals has become a main concern for many researchers to further improve the ionic conductivity and stability of electrolytes. This article provides an overview on the properties of four types of cerate and/or zirconate electrolytes including cerate-based, zirconate-based, single-doped cerate–zirconate and hybrid-doped cerate–zirconate. The properties of the proton electrolytes such as ionic conductivity, chemical stability and sinterability are also systematically discussed. This review further provides a summary of the performance of SOFCs operated with cerate and/or zirconate proton conductors and the actual potential of these materials as alternative electrolytes for proton-conducting SOFC application.     

An automatic approach for urban land-cover classification from Landsat-8 OLI data

Due to the lack of clear shape, texture characteristics, and abundant spectral or spatial information of urban objects, traditional per-/sub-pixel analysis and interpretation for moderate-resolution-remote sensing data are always confused by such shortcomings as dependence on special skills, requirements to a priori knowledge and training samples, complex process, time-consuming and subjective operations, etc.. In order to alleviate such disadvantages, an automatic approach is proposed to classify vegetation, water, impervious surface areas (dark and bright), and bare land from the Operational Land Imager (OLI) sensor data of Landsat-8 in urban areas, which can be employed by common users to automatically obtain land-cover maps for urban applications. In detail, a preliminary classification result is achieved based on a new vegetation and water masking index (VWMI), the normalized difference vegetation index (NDVI), and a new normalized difference bare land index (NDBLI), which are acquired automatically from the remote-sensing images based on available knowledge of spectral properties. VWMI is designed to extract vegetation and water information together with a simpler threshold, while NDBLI is developed to identify dark impervious surfaces and bare land in this work. A modification strategy is further proposed to improve preliminary classification results by a linear model. For this purpose, a stable sample selection method based on the histogram is developed to select training samples from the preliminary classification result and to build a non-linear support vector machine (SVM) model to reclassify the classes. For validation and comparison purposes, the proposed approach is evaluated via experiments with real OLI data of two study areas, Nanjing and Ordos. The results demonstrate that the approach is effective in automatically obtaining urban land-cover classification maps from OLI data for thematic analysis.     

The Crystal and Molecular Structure of Dianhydrogossypol

Dianhydrogossypol (4,4′-dihydroxy-5,5′-diisopropyl-7,7′-dimethyl-bis(3H-naphtho[1,8-bc]furan-3-one)) was made by refluxing gossypol in m-xylene. Proton NMR spectroscopy was used to confirm that complete conversion was achieved over a time period of several hours. Single crystals of the compound were obtained by slow evaporation from dichloromethane. Diffraction studies indicate that this crystal form is tetragonal with a I4₁/a space group and with cell dimensions of a = b = 33.8265(4) Å, c = 9.1497(2) Å, V = 10469.4(3) Å³ at 100 K. The structure was solved by direct methods and was refined to an R1 value of 0.0415 on 6,408 independent reflections. Dianhydrogossypol exists as a pair of enantiomers within this structure. The two fused planar ring systems are oriented at a 117° angle to each other (i.e., close to perpendicular), and the isopropyl groups are oriented with the ternary carbon hydrogen atoms pointed inward toward the center of the molecule. Repeating groups of four molecules (of the same chirality) pack to form a helical structure that is supported by intermolecular hydrogen bonds. Each helix is surrounded by four neighboring helices that are composed of molecules of the opposite chirality. The helices form the walls of empty channels that are 5–6 Å wide. As has been found for some gossypol crystal forms, the open-channel structure of dianhydrogossypol might be useful for scavenging or carrying small molecules. Additional NMR studies confirm that dianhydrogossypol can be converted directly to gossypol lactol ethers in the presence of anhydrous alcohols.     

Effect of processing routes on the mechanical, thermal and morphological properties of PLA-based hybrid biocomposite

Due to environmental awareness and depletion of petroleum oil, bioplastics and their composites are one of the most researchable topics throughout the world. Polymers that are produced from renewable sources are expected to be the best alternative to replace conventional polymers. The bottles neck of these bioplastics is its cost which limits its application in certain purposes. Bioplastics filled or reinforced with natural fibers can reduce cost and improve properties, like stiffness, strength and toughness of biocomposites. Impact strength and fracture toughness are the main demerits of short fiber-filled biocomposite. On the other hand, when nanoclay, having a very high aspect ratio, is mixed with bioplastics it may significantly affect the thermal and mechanical properties of the final composites. A composite may also suffer dispersion inefficiency, which is considered the key factor to improve the properties. The aim of this paper was to hybridize nanoclay and short kenaf fiber in polylactic acid (PLA) by double extrusion method and followed by mechanical, thermal and morphological characterizations. Mechanical properties showed improvement with nanoclay, specifically the impact strength increased more than 50 % compared with unreinforced PLA. A double extruded composite showed 3–10 % better tensile and flexural properties than the single extruded composite. Similarly, addition of nanoclay increased decomposition and melting temperatures (T _m) from 198 to 225 °C and 152 to 155 °C, respectively. Crystallization temperature (T _c), however, dropped with nanoclay from 116 to 106 °C and storage modulus (E’) increased by about 1 GPa. These findings were also supported by scanning electron micrograph (SEM) and transmission electron micrograph (TEM) where in double extruded composite a better dispersion of nanoclay was observed. By employing X-ray diffraction (XRD) it was found that higher percentage of crystallinity was obtained while Fourier transform infrared (FTIR) displayed new bond formation. The presence of nanoclay enhanced thermal and mechanical properties of the hybrid composite.     

Radiation dose and in vitro precision in paediatric bone mineral density measurement using dual X-ray absorptiometry

Dual X-ray absorptiometry (DXA) is one of the most widely used techniques for non-invasive assessment of bone integrity. There is a growing demand for measurement of paediatric bone status. In DXA the principal radiation risks to patients are the carcinogenic and genetic effects. Radiation dosimetry is well established for DXA in adults, but there are limited paediatric data available. We report on a study to estimate the effective doses (EDs) received by typical 5- and 10-year-old children using the paediatric scan mode on the Lunar DPX-L bone mineral density scanner. Entrance surface doses (ESDs) and percentage depth doses for the total body and PA spine scan modes were measured using lithium borate thermoluminescent dosemeters (TLDs) located at the surface and distributed at various organ locations in anthropomorphic child phantoms. The EDs were calculated from the percentage depth doses, amount of each organ irradiated and tissue weighting factors. The ESDs were measured to be 6.0 and 0.12 microGy for the posteroanterior (PA) spine and total body, respectively. PA spine EDs were calculated as 0.28 and 0.20 microSv for the 5- and 10-year-old, respectively. Total body EDs were 0.03 and 0.02 microSv for the 5- and 10-year-old children, respectively. These results compare with an adult ED of 0.21 microSv for the PA spine. They are also more than two orders of magnitude lower than reported ESDs and EDs for paediatric chest X-rays. Bone mineral density (BMD) short-term in vitro precision was 0.5% and 1% in the 5- and 10-year-old phantoms, respectively. In conclusion, the Lunar DPX-L in the paediatric mode has a high precision and very low radiation doses, similar to those reported for the adult mode.     

Measurement and prediction of total body fat

Though it has been established that skinfold anthropometry has severe limitations as a method of deriving total body fat (TBF), the possibility that the problem might be related more to the assumptions implicit in densitometry has to be addressed. This paper suggests that smaller residual errors might be obtained if sums of skinfolds are regressed against TBF measured by a difference technique (IVNAA + 3H2O dilution), suggesting that the latter may perhaps be a better standard than densitometry.     

诃子膏核心药对正常大鼠能量代谢相关因子的影响

目的分别观察诃子膏3种核心药(诃子、毛诃子、余甘子)及其组合(剂量比为1:1:1)对正常大鼠能量代谢相关因子的影响,分析其作用趋势和特点。方法制备药液并灌胃给药30 d后,观察大鼠体重变化,采用酶联免疫吸附法(enzyme-linked immunosorbent assay, ELISA)检测肝组织Na~+-K~+ATP酶、Ca~(2+)-Mg~(2+)ATP酶和琥珀酸脱氢酶(succinate dehydrogenase, SDH)活性、肝糖原(hepatic glycogen, HG)和肌糖原(muscle glycogen,MG)含量,检测血浆三碘甲状腺原氨酸(triiodothyronine, T3)、四碘甲状腺原氨酸(tetraiodothyronine, T4)、促甲状腺激素(thyroid stimulating hormone, TSH)含量。结果核心药组和毛诃子组能够抑制正常老鼠体重自然增大。毛诃子组显著升高Na~+-K~+ATP酶、Ca~(2+)-Mg~(2+)ATP酶和SDH活性, HG、MG、T3、T4和TSH含量,而诃子组、余甘子组和核心药组合对能量代谢相关因子的影响不明显。结论核心药组合对正常大鼠Na~+-K~+ATP酶、Ca~(2+)-Mg~(2+)ATP酶和SDH、HG、MG、T3、T4和TSH等能量代谢相关因子的影响不显著,而毛诃子影响显著,可能是毛诃子所含物质基础与其他2种药材不同有关,还需要进一步研究。     

Characterizing the scale sensitivity of the cellular automata simulated urban growth: A case study of the Seberang Perai Region, Penang State, Malaysia

In modeling the complex behaviour of urban systems using a cellular automata approach, scale is an important concept in representing space since the result obtained at specific scale shall not be expected to be valid at another scale. The selection of scale, however, has often been taken for granted on the basis of information available to be mapped. Although it is desirable to run a model with fine spatial scale datasets, such datasets may well be costly to collect and add computational expenses in processing. This article investigates the effect of changing scale on the performance of a GIS-based cellular automata (CA) model developed to simulate the spatial pattern of urban growth. The sensitivity of scale of the input data used to parameterize the model was undertaken by evaluating the resulting prediction accuracy of the model and the morphology of urban areas. It seemed that the model managed to perform well and produce realistic urban form only up to specific range of scale. Thus, the selection of scale to represent urban system under consideration has to be undertaken with care, in order to ensure that the output produced maintains the overall accuracy of the model and morphology of urban areas.     

Microstructural evolution,dislocation density and tensile properties of Al-6.5Si-2.1Cu-0.35Mg alloy produced by different casting processes

Al-Si-Cu-Mg foundry alloys are used in casting process technologies.However,their strength proper-ties remain low due to their microstructural characteristics and porosity.In this work,the microstruc-tural characteristics,dislocation densities,and mechanical properties of Al-Si-Cu-Mg cast alloys prepared through different casting methods were studied experimentally.Four casting processes,namely,gravity casting (GC),rheocasting (RC),thixoforming (Thixo),and Thixo with heat treatment,were used.The GC and RC samples had mainly dendritic α-Al phase microstructures and exhibited coarse Si particles and intermetallic compounds in their interdendritic regions.By contrast,the Thixo and heat-treated Thixo(HT-Thixo) samples exhibited microstructural refinement with uniformly distributed α-Al globules,fine fibrous Si particles,and fragmented intermetallic compounds among α-Al globules.The accumulation of dislocation densities increased in the Thixo sample as the strain was increased due to plastic deforma-tion.Furthermore,the ultimate tensile strength and yield strength of the HT-Thixo sample increased by 87％ and 63％,respectively,relative to those of the GC sample.The cleavage fracture displayed by the GC and RC samples led to brittle failure.Meanwhile,the Thixo and HT-Thixo samples presented dimple-based ductile fracture.     

Assessment of the long-term possible radiological risk from the use of ceramic tiles in Malaysia

This study investigated the level of natural radioactivity and radiological risks of 40 different ceramic tiles through gamma-ray spectroscopy using a high-purity germanium detector. The calculated activity concentrations were evaluated to determine their potential radiological risks to human health. Furthermore, the activity concentrations were subjected to the RESRAD-BUILD computer code to assess the effect of ventilation rate, dweller position, and room size and direction on the total effective dose(TED). The simulated TED received by a receptor when changing the ventilation rate in a room ranged from0.26 ± 0.01 to 0.61 ± 0.01 mSv/y; however,the percentage variations in the TED due to dweller position and room size are 34, 31,and 35% and 33, 27, and 40% for the x-,y-,and z-directions, respectively. The overall TED received by the dweller based on room size and direction is 0.75 mSv/y. The calculated radiological risk parameters were all below the recommended maximum limit. However, the TED received by the dweller is significantly affected by the directions of the measurement, position,room size,and ventilation. Therefore,estimating the TED from one direction would underestimate the total dose received by the dweller.