Three-dimensional multi-level heat transfer model of silica aerogel

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this paper, a 3-D multi-level heat transfer model is developed in consideration of the tortuous path of heat conduction in solid skeleton and the fractal characteristic of silica aerogel. The heat conduction is analyzed for both the secondary particle model and the cluster model. The expression of effective thermal conductivity of a multi-level model is derived. The theoretical predictions from the proposed multi-level model are compared with three sets of experimental data with different densities and porosities. The results from the proposed model show good agreement with the experimental data

Personalized web search using clickthrough data and web page rating

Personalization of Web search is to carry out retrieval for each user incorporating his/her interests. We propose a novel technique to construct personalized information retrieval model from the users' clickthrough data and Web page ratings. This model builds on the userbased collaborative filtering technology and the top-N resource recommending algorithm, which consists of three parts: user profile, user-based collaborative filtering, and the personalized search model. Firstly, we conduct user's preference score to construct the user profile from clicked sequence score and Web page rating. Then it attains similar users with a given user by user-based collaborative filtering algorithm and calculates the recommendable Web page scoring value. Finally, personalized informaion retrieval be modeled by three case applies (rating information for the user himself; at least rating information by similar users; not make use of any rating information). Experimental results indicate that our technique significantly improves the search performance. © 2012 ACADEMY PUBLISHER

Study on the serum oxidative stress status in silicosis patients

To determine whether oxidative-stress damage play an important role in the mechanism of silicosis, the oxidative stress parameters were investigated in silicosis patients and controls group. 128 silicosis patients and 130 healthy controls were included. The serum superoxide dismutase (SOD) activity and the levels of malonyldialdehyde (MDA) and glutathione (GSH) were analyzed. The levels of GSH and MDA in silicosis patients were significantly higher than those of the controls group. SOD activity was higher in the silicosis group than that in the controls (p < 0.05) except for III stage. None of the 3 variables examined were associated with the age among both the controls and silicosis patients. The GSH level and SOD activity significantly declined over a prolonged disease period, while MDA levels remained largely unaffected by the disease duration. These results confirmed the role of oxidative stress in the mechanism of silicosis. Therefore, effective antioxidant therapy for inhibiting oxidative stress may be a therapeutic option in silicosis.Key words: Silica, silicosis, superoxide dismutase, glutathione, malondialdehyde

Atmospheric effects of the emerging mainland Chinese transportation system at and beyond the regional scale

Local surface travel needs in the People's Republic of China (mainland China) have traditionally been met largely by nonpolluting bicycles. A major automobile manufacturing/importing effort has begun in the country over the last decade, and planning documents indicate that the Chinese may strive to acquire more than 100 million vehicles early in the next century. By analogy with large automotive fleets already existing in the western world, both regional and global scale pollution effects are to be expected from the increase. The present work adopts the latest projections of Chinese automobile manufacture and performs some quantitative assessments of the extent of pollution generation. Focus for the investigation is placed upon the oxidant ozone. Emissions of the precursor species nitrogen oxides and volatile organics are constructed based on data for the current automotive sector in the eastern portion of the United States. Ozone production is first estimated from measured values for continental/oceanic scale yields relative to precursor oxidation. The estimates are then corroborated through idealized two dimensional modeling of the photochemistry taking place in springtime air flow off the Asian land mass and toward the Pacific Ocean. The projected fleet sizes could increase coastal and remote oceanic ozone concentrations by tens of parts per billion (ppb) in the lower troposphere. Influences on the tropospheric aerosol system and on the major greenhouse gas carbon dioxide are treated peripherally. Nitrogen oxides created during the vehicular internal combustion process will contribute to nitrate pollution levels measured in the open Pacific. The potential for soot and fugitive dust increases should be considered as the automotive infrastructure develops. Since the emerging Chinese automotive transportation system will represent a substantial addition to the global fleet and all the carbon in gasoline is eventually oxidized completely, a significant rise in global carbon dioxide inputs will ensue as well. Some policy issues are treated preliminary. The assumption is made that alterations to regional oxidant/aerosol systems and to terrestrial climate are conceivable. The likelihood that the Chinese can achieve the latest vehicle fleet goals is discussed, from the points of view of new production, positive pollution feedbacks from a growing automobile industry, and known petroleum reserves. Vehicular fuel and maintenance options lying before the Chinese are outlines and compared. To provide some perspective on the magnitude of the environmental changes associated with an Asian automotive buildup, recent estimates of the effects of future air traffic over the Pacific Rim are described

Lead-free multilayer piezoelectric transformer

Author name used in this publication: K. H. LamAuthor name used in this publication: S. WangAuthor name used in this publication: C. L. SunAuthor name used in this publication: X. Z. Zhao2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites

High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-inspired aggregation control to limit the CNT aggregation to be sub 20--50 nm, a dimension determined by the CNT growth. After being stretched with full structural relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite yielded super-high tensile strengths up to 6.27--6.94 GPa, more than 100% higher than those of carbon fiber/epoxy composites, and toughnesses up to 117--192 MPa. We anticipate that the present study can be generalized for developing multifunctional and smart nanocomposites where all the surfaces of nanometer-sized components can take part in shear transfer of mechanical, thermal, and electrical signals

Geochemical characteristics and 40Ar- 39Ar ages of the amphibolites and gabbros in Tarlang area: Implications for tectonic evolution of the Chinese Altai

Amphibolitic and gabbroic rocks occur in Tarlang area in Chinese Altay. Amphibolites are metamorphosed products of mafic magmatic rocks (SiO 2 = 45.42% - 52.96%) and contain high Al 2O 3 (13.14% - 17.92%), Fe 2O 3 T (9.08% - 16.88%) and TiO 2 (0.82% - 3.23%) contents. The amphibolite samples show relatively flat REE patterns, without significant fractionations of REEs (La/Yb N = 1.53 - 1.79). These samples are depleted in HFSEs slightly, with slightly Ti-Nb-Ta negative anomalies, which suggest a subtle relation to subduction-related environment. The gabbroic samples (SiO 2 = 46.96% - 49.86%) have intermediate TiO 2 (0.38% - 1.89%) and relatively low K 2 O contents (K 2 O = 0.34% - 1.03%), belonging to subalkali rocks (Na 2 O > K 2 O). They have relatively high Al 2O 3 (15.0% - 20.81%), CaO (10.13% - 11.60%) and moderate MgO (7.3% - 8.3% ) contents. The gabbroic samples show two types of REE patterns. One is characterized by slight fractionation of REEs (La/Yb N = 1.10 - 1.67) and weak Eu anomalies (δEu = 1.03 - 1.10), while the other is enriched in LREE s (La/Yb N = 5.97 - 6.39), with significantly positive Eu anomalies (δEu = 1.31 - 1.44), which may reflect accumulation of plagioclase in the magma chamber. These gabbroic rocks all exhibit Ti-Nb-Ta troughs and Pb-Sr spikes, also implying a subduction-related origin. The 40Ar/ 39Ar spectrum of the gabbroic sample is simple and flat (plateau age of 266.9 ± 4.2Ma; isochron age of 261 ± 23Ma), indicating that its K-Ar isotopic system was not seriously disturbed by subsequent thermal events and may reflect the intrusion time of the gabbro. However, 40Ar- 39Ar analysis of the amphibolite give rise to a saddle-like spectrum, and its youngest plateau (297.3 ± 6.1Ma) probably reflects the last metamorphic event. The difference on age and geochemistry between the amphibolitic and gabbroic rocks implies that they probably represent different mafic magma. The protolith of amphibolites probably formed in a seamount near a subduction zone and subsequently accreated to the Altai. The gabbro exhibits subduction-releted characteristics and was coeval with transtensional movement in the Chinese Altai, probably reflecting a tectonic transition in the Permian.阿爾泰塔爾浪地區出露一些斜長角閃巖和輝長巖。其中,斜長角閃巖為基性巖漿巖變質的產物,SiO_2含量為45.42%～52.96%,具有較高的Al_2O_3(13.14%～17.92%)、Fe_2O_3~T(9.08%～16.88%)和TiO_2(0.82%～3.23%)含量。斜長角閃巖樣品稀土元素曲線比較平坦,輕重稀土元素分餾不明顯(La/Yb_N=1.53～1.79),無明顯的Nb和Ta虧損。通過野外產狀及地球化學特征分析,認為該斜長角閃巖形成于海山的構造環境。輝長巖SiO_2(46.96%～49.86%)含量稍低,TiO_2(0.38%～1.89%)變化較大,并富Al_2O_3(15.0%～20.81%)、CaO(10.13%～11.60%),具有中等至較高MgO含量(7.3%～8.3%)和相對較低的鉀含量(K_2O=0.34%～1.03%),屬亞堿性巖石系列(Na_2O>K_2O)。輝長巖呈現兩種稀土元素組成特征。一種輕重稀土分餾不明顯,配分曲線比較平坦(La/Yb_N=1.10～1.67),具有輕微的Eu正異常(δEu=1.03～1.10);另一種輕重稀土元素分餾較明顯(La/Yb_N=5.97～...published_or_final_versio

An activity-based integrated land-use transport model for urban spatial distribution simulation

This research develops an activity-based integrated land use/transport interaction model based on the concepts – activities (mainly, households and employment activities), activity location and relocation for Chinese regions. It consists of a residential and employment location sub-model, a transport sub-model and an implicit real estate rent adjustment sub-model. The model is developed to model the urban activity distribution evolution, predict urban spatial development trends and examine various planning decision implications. It spatially distributes household and employment activity change of a study area by zone based on the current activity distribution, land use policies and the accessibilities of the zones. The model is subsequently calibrated to predict the distribution of households and employment activities in Beijing metropolitan area in 2025. Model results show that the resident and employment densities are still high in central Beijing in 2025, and most zones’ resident densities are higher than their employment densities. However, there is also significant population density increase along the 6th ring road, indicating the relocation trend of the residents and businesses to the outskirts. This is consistent with the government objectives to decentralize activities within the central urban area. The paper also suggests that the model should be used mainly in examining the possible differences arising from the adoption of different policies though predicting future of a city distribution proves feasible

Continuous Regional Arterial Infusion with Fluorouracil and Octreotide Attenuates Severe Acute Pancreatitis in a Canine Model

Aim: To investigate the therapeutic effects of fluorouracil (5-Fu) and octreotide (Oct) continuous regional arterial infusion (CRAI,) alone or in combination, was administered in a canine model of severe acute pancreatitis (SAP). Materials and Methods: The animals were divided into five groups; group A (Sham), group B (SAP), group C (SAP and 5-Fu), group D (SAP and Oct), and group E (SAP and 5-Fu + Oct). Levels of amylase, alpha-tumor necrosis factor (TNF-alpha), blood urea nitrogen (BUN), creatinine, thromboxane B2 and 6-keto-prostaglandin F1 alpha were measured both before and after the induction of SAP. Pathologic examination of the pancreas and kidneys was performed after termination of the study. Results: Pathologic changes noted in the pancreas in SAP significantly improved following CRAI with either single or combined administration of 5-Fu and Oct, where combination therapy demonstrated the lowest injury score. All treatment groups had significantly lower levels of serum TNF-alpha and amylase activity (P<0.05), though only groups D and E had a lower BUN level as compared to group B. The plasma thromboxane B-2 level increased in SAP, but the ratio of thromboxane B-2/6-keto-prostaglandin F-1 alpha decreased in the treatment groups, with the combination therapy (group E) demonstrating the lowest ratio as compared to the other 3 experimental groups (P<0.05). Conclusions: The findings in the present study demonstrate an attenuation of SAP in a canine model following CRAI administration with 5-Fu or Oct, alone or in combination