Energy coupled to matter for magnetic alignment of rare earth–doped alumina

Energy coupled to matter (ECM) concepts such as magnetic field–assisted processing were used to align rare earth–doped alumina ceramics in the presence of applied fields. The addition of gadolinium and ytterbium dopants to alumina increased the magnetic susceptibility anisotropies, and induced magnetic torques that led to significant alignment of ceramic particles under the application of magnetic fields as low as 1.8?T. In comparison, undoped alumina materials showed minimal alignment under applied field strengths as high as 9?T. Density function theory modeling indicated that the specific dopant type dictated changes in the magnetic properties of different rare earth–doped alumina systems by directly affecting the magnetic moment localization and magnetocrystalline anisotropy.     

High‐Temperature Particulate Matter Filtration with Resilient Yttria‐Stabilized ZrO2 Nanofiber Sponge

Particulate matter (PM) is a major air pollutant in many regions, jeopardizing ecosystems and public health. Filtration at pollutant source is one of the most important ways to protect the environment, however, considering the high‐temperature exhaust gas emissions, effective removal of PM and related pollutants from their sources remains a major challenge. In this study, a resilient, heat‐resisting, and high‐efficiency PM filter based on yttria‐stabilized ZrO₂ (YSZ) nanofiber sponge produced with a scalable solution blow spinning process is reported. The porous 3D sponge composed of YSZ nanofibers is lightweight (density of 20 mg cm^?3) and resilient at both room temperature and high temperatures. At room‐temperature conditions, the YSZ nanofiber sponge exhibits 99.4% filtration efficiency for aerosol particles with size in the range of 20–600 nm, associated with a low pressure drop of only 57 Pa under an airflow velocity of 4.8 cm s^?1. At a high temperature of 750 °C, the ceramic sponge maintains a high filtration efficiency of 99.97% for PM_0.3–2.5 under a high airflow velocity of 10 cm s^?1. A practical vehicle exhaust filter to capture particles with filtration efficiency of >98.3% is also assembled. Hence, the YSZ nanofiber sponge has enormous potential to be applied in industry.     

Light‐Activated,Multi‐Semiconductor Hybrid Microswimmers

Using a dynamic fabrication process, hybrid, photoactivated microswimmers made from two different semiconductors, titanium dioxide (TiO₂) and cuprous oxide (Cu₂O) are developed, where each material occupies a distinct portion of the multiconstituent particles. Structured light‐activated microswimmers made from only TiO₂ or Cu₂O are observed to be driven in hydrogen peroxide and water most vigorously under UV or blue light, respectively, whereas hybrid structures made from both of these materials exhibit wavelength‐dependent modes of motion due to the disparate responses of each photocatalyst. It is also found that the hybrid particles are activated in water alone, a behavior which is not observed in those made from a single semiconductor, and thus, the system may open up a new class of fuel‐free photoactive colloids that take advantage of semiconductor heterojunctions. The TiO₂/Cu₂O hybrid microswimmer presented here is but an example of a broader method for inducing different modes of motion in a single light‐activated particle, which is not limited to the specific geometries and materials presented in this study.     

利用光闪烁现象进行粉尘排放的监测

粉尘排放监测系统正在各国推广应用,新的方法也不断出现．本文提出一种基于光闪烁现象的粉尘排放监测方法．同光透射法相比,这种新方法具有测量精度高、不怕污染、成本低的特点．实验结果表明,测量系统的输出与粉尘排放的浓度呈线性关系．     

PM10 remote sensing from geostationary SEVIRI and polar-orbiting MODIS sensors over the complex terrain of the European Alpine region

The subject of this study is to investigate the capability of spaceborne remote sensing data to predict ground concentrations of PM₁₀ over the European Alpine region using satellite derived Aerosol Optical Depth (AOD) from the geostationary Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the polar-orbiting MODerate resolution Imaging Spectroradiometer (MODIS). The spatial and temporal resolutions of these aerosol products (10 km and 2 measurements per day for MODIS, ∼ 25 km and observation intervals of 15 min for SEVIRI) permit an evaluation of PM estimation from space at different spatial and temporal scales. Different empirical linear relationships between coincident AOD and PM₁₀ observations are evaluated at 13 ground-based PM measurement sites, with the assumption that aerosols are vertically homogeneously distributed below the planetary Boundary Layer Height (BLH). The BLH and Relative Humidity (RH) variability are assessed, as well as their impact on the parameterization. The BLH has a strong influence on the correlation of daily and hourly time series, whilst RH effects are less clear and smaller in magnitude. Despite its lower spatial resolution and AOD accuracy, SEVIRI shows higher correlations than MODIS (r_SEV∼ 0.7, r_MOD∼ 0.6) with regard to daily averaged PM₁₀. Advantages from MODIS arise only at hourly time scales in mountainous locations but lower correlations were found for both sensors at this time scale (r∼ 0.45). Moreover, the fraction of days in 2008 with at least one satellite observation was 27% for SEVIRI and 17% for MODIS. These results suggest that the frequency of observations plays an important role in PM monitoring, while higher spatial resolution does not generally improve the PM estimation. Ground-based Sun Photometer (SP) measurements are used to validate the satellite-based AOD in the study region and to discuss the impact of aerosols' micro-physical properties in the empirical models. A lower error limit of 30 to 60% in the PM₁₀ assessment from space is estimated in the study area as a result of AOD uncertainties, variability of aerosols properties and the heterogeneity of ground measurement sites. It is concluded that SEVIRI has a similar capacity to map PM as sensors on board polar-orbiting platforms, with the advantage of a higher number of observations. However, the accuracy represents a serious limitation to the applicability of satellites for ground PM mapping, especially in mountainous areas.     

An approach to quantify depth-resolved marine photochemical fluxes using remote sensing: Application to carbon monoxide (CO) photoproduction

This paper presents a model to calculate depth-resolved marine photochemical fluxes from remotely sensed ocean color and modeled solar irradiance. The basic approach uses three components: 1) below-sea-surface spectral downward scalar irradiance calculated from a radiative transfer model (STAR) and corrected for clouds using TOMS UV reflectivities; 2) surface-ocean spectral diffuse attenuation coefficients and absorption coefficients for chromophoric dissolved organic matter retrieved from SeaWiFS ocean color using the SeaUV/SeaUVc algorithms; and (3) spectral apparent quantum yield for the photochemical reaction considered. The output of the model is a photochemical rate profile, Ψ_PR(z), where z represents depth.We implemented the model for carbon monoxide (CO) photochemistry using an average apparent quantum yield spectrum and generated a monthly climatology of depth-resolved CO photoproduction rates in the global ocean. The climatology was used to compute global budgets and investigate the spatial and seasonal variabilities of CO photoproduction in the ocean. The model predicts a global CO photoproduction rate of about 41 TgC yr^− 1, in good agreement with other recent published estimates ranging from 30 to 84 TgC yr^− 1. The fate of photochemically derived CO and its role in global biogeochemical cycles remains uncertain however, with biological consumption and sea-air exchange competing for its removal in the surface ocean. Knowledge of the vertical distribution of CO photoproduction is critical in the quantification of the relative magnitudes of these sink mechanisms. The depth-resolution capabilities of this model, together with US Naval Research Laboratory climatology for mixed layer depths allowed further estimation that > 95% of the total water-column CO photoproduction occurs within the mixed layer on a global, yearly basis. Despite this compelling figure, the model also suggests significant spatio-temporal variability in the vertical distribution of CO photoproduction in the subtropical gyres, where up to 40% of water-column CO can be produced below the mixed layer during summertime.While the approach can be applied to other photochemical fluxes (e.g. DIC formation or DMS removal), accurate quantification of such processes with remote sensing will be limited until the mechanisms regulating observed oceanic variability in the apparent quantum yields are better understood. Minor modification to this model can also make it applicable for the determination of the effects of UV and visible solar radiation on sensitive biological systems.     

Effect of animation enhanced conceptual change texts on 6th grade students’ understanding of the particulate nature of matter and transformation during phase changes

In this study, the effect of animation enhanced conceptual change texts (CCT–CA) on grade 6 students’ understanding of the particulate nature of matter (PNM) and transformation during the phase changes was investigated. A quasi-experimental design and one control group (CG, N = 25) and one experimental group (EG, N = 26) were used. While the control group taught traditional instruction, the experimental group received CCT–CA instruction. Two different tests, The Particulate Nature of Matter Concept Test (ParNoMaC) and The Transformation of Matter Statement Test (ToMaSaT), were administered as pretest, posttest and delayed test to collect data. Results indicate that while there is no statistically significant difference between groups in pretest, performance of EG students is greater than the CG ones in posttest and delayed test. And also, the EG students are better in remediating their alternative conceptions related to the PNM and transformations during the phase changes. Based on the study, it is concluded that CCT–CA combination may be effective way to improve students’ understanding of basic science and chemical concepts.     

A Graph‐based Approach to Continuous Line Illustrations with Variable Levels of Detail

This paper introduces a method for automatically generating continuous line illustrations, drawings consisting of a single line, from a given input image. Our approach begins by inferring a graph from a set of edges extracted from the image in question and obtaining a path that traverses through all edges of the said graph. The resulting path is then subjected to a series of post‐processing operations to transform it into a continuous line drawing. Moreover, our approach allows us to manipulate the amount of detail portrayed in our line illustrations, which is particularly useful for simplifying the overall illustration while still retaining its most significant features. We also present several experimental results to demonstrate that our approach can automatically synthesize continuous line illustrations comparable to those of some contemporary artists.     

基于梯度化邻居节点信息的传感器网络性能优化*

由于路由控制粒度粗,传统最小跳数路由无线传感器网络模型MHR存在数据汇聚可靠性差和能量有效性低等问题,需进一步完善。为改善传统MHR网络的性能,提出一种高效可靠的最小跳数路由无线传感器网络模型MHR-ER,在MHR网络的基础上,通过提取网络梯度化邻居节点信息作为路由精细化控制的依据,通过限制最小跳数梯度场梯度层次宽度以保证数据汇聚的高可靠性,通过限制数据分组的各跳转发节点数以提高数据汇聚的能量有效性。理论分析和仿真结果表明,与MHR网络相比,MHR-ER网络具有极高的数据汇聚可靠性和较好的能量有效性,有利于推动最小跳数路由无线传感器网络的实际应用。