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材料热处理学报 2004年第5期25卷 546-551页

作者： Stephen j. Mashl Body cote HIP Inc. Andover Massachusetts USA

Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing. This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subj.cted to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.

关键词： Al-Si-Mg合金热处理热等静压缩 HIP 机械性质疲劳寿命

Mercury photoreduction and photooxidation in lakes：Effects of filtration and dissolved organic carbon concentration

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j.urnal of Environmental Sciences 2018年第6期30卷 151-159页

作者： Nelson j.O’Driscoll Emma Vost Erin Mann sara Klapstein Robert Tordon Matthew Lukeman Department of Earth & Environmental Science Acadia University Wolfville B4P 2R6 Nova Scotia Canada Environment Canada Dartmouth Nova Scotia Canada Department of Chemistry Acadia University Wolfville B4P 2R6 Nova Scotia Canada

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon（DOC） concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kej.mkuj.k National Park, Nova Scotia（DOC： 2.6–15.4 mg/L）. Filtered（0.2 μm） and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations（p = 0.04） of photoreducible divalent mercury（Hg（II）RED）（mean of 754 ± 253 pg/L） than filtered samples（mean of 482 ± 206 pg/L）;however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered（R2= 0.43; p = 0.08） and unfiltered（R2= 0.02; p = 0.71） samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg（Ⅱ）RED in unfiltered（R2= 0.53; p = 0.04）, but not in filtered samples（R2= 0.04;p = 0.60）. These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg（Ⅱ）RED in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.

关键词： Mercury Photoreduction Photooxidation Dissolved organic carbon(DOC) Particulates Kej.mkuj.k National Park

Women in visual neural regeneration research

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Neural Regeneration Research 2025年第2期20卷 489-490页

作者： Tonia S.Rex David j.Calkins Vanderbilt Eye Institute Vanderbilt University Medical CenterNashvilleTNUSA

The year 2024 marks the 60^(th)anniversary of Title IX and 25 years since the New York Times revealed bias against female faculty members at the Massachusetts Institute of *** take an opportunity here to examine the state of gender bias in a relatively new yet already prominent field,neural regeneration in the visual system,for which there is a well-defined context useful for this *** National Eye Institute(NEI)provided the first round of research funding for its Audacious Goals Initiative(AGI)on visual neural regeneration in 2013 and the last round in ***,we focus on this *** sources included PubMed,the National Science Foundation(NSF),the NEI,the Blue Ridge Institute for Medical Research and data from the maj.r professional organization for eye and vision research,the Association for Research in Vision and Ophthalmology(ARVO).

关键词： neural visual Times

Effect of dietary near ideal amino acid profile on heat production of lactating sows exposed to thermal neutral and heat stress conditions

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j.urnal of Animal Science and Biotechnology 2021年第2期12卷 739-754页

作者： S.Zhang j.S.johnson N.L.Trottier Department of Animal Science Michigan State UniversityEast Lansing 48824USA USDA-ARS Livestock Behavior Research Unit West Lafayette 47907USA

Background:Reduced protein diet manifested potential to mitigate heat production based on the concept of ideal amino acid *** hypothesis of this study was that lactating sows fed a low crude protein(LCP)diet with supplemental amino acid produce less heat compared to those fed a high crude protein(HCP)diet under both thermal neutral(TN)and heat stress(HS)***:Thirty-two lactating sows were allotted to HCP(193 g CP/kg)and LCP(140 g CP/kg)diets under thermal neutral(TN,21±1.5°C)or cycling heat stress(HS,32±1.5°C daytime and 24±1.5°C nighttime)*** contained 0.90%SID lysine and 10.8 Mj.kg net *** pressure indirect calorimeters were used to measure gas exchange in individual sows with litters,and individual piglets on days 4,8,14 and *** and litter weights were recorded on days 1,10 and ***:Sow total heat production(THP)was calculated by subtracting litter THP from sow+litter THP based on *** BW and body protein(BP)loss was greater for LCP diet compared to HCP diet in peak lactation(P<0.05 and P<0.01,respectively)and throughout the entire lactation period(P<0.05 and P=0.056,respectively)under HS ***-stressed sows fed HCP diet had higher(P<0.05)rectal temperature at 13:00(P<0.05)and 19:00(P<0.01),and higher respiration rate at 07:00(P<0.05),13:00(P<0.05)and 19:00(P<0.05)compared to TN sows fed HCP *** sows fed LCP diet,those under HS tended to have higher(P=0.098)rectal temperature at 13:00 and had higher(P<0.05)respiration rate at 07:00,13:00 and 19:00 compared to TN *** relationship between daily THP and days in lactation of sows fed LCP diet was quadratic(P<0.05),with an ascending trend until day 14 and a descending trend from days 14 to *** fed LCP diet had lower daily THP at day 18(P<0.001)compared to those fed the HCP diet under HS ***:Reduction in THP in sows fed LCP diet was largely associated with THP on day 18 of lactation under HS *** LCP die

关键词： Amino acid Heat stress Lactating sows Low protein diet Total heat production

Analysis of Longitudinal Profiles along the Eastern Margin of the Qinghai-Tibetan Plateau

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j.urnal of Mountain Science 2013年第4期10卷 643-657页

作者： Simon j. Aiken Gary j. Brierley School of Environment the University of AucklandAuckland 1010 New Zealand

Resulting from the collision of the Eurasian and Indian plates, the Qinghai-Tibetan Plateau is commonly known as the ＇roof of the world＇. Collectively the Yarlung Tsangpo, Nu, Laneang, Yangtze, Yalong, and Yellow River basins drain the eastern margin of the plateau. In this paper, we utilize Shuttle Radar Topography Mission elevation data to examine morphometric and relief attributes of these basins to reveal insights rates of incision. A robust into tectonic activity and technique using Maflab is proposed to alleviate errors associated with SRTM data in the derivation of river longitudinal profiles. Convex longitudinal profiles are interpreted to be a product of uplift rates that exceed rates of channel incision along the entire margin of the Qinghai- Tibetan Plateau. Highest relief towards the south reflects extensive fluvial incision. High relief is also prominent along maj.r active faults. Erosion patterns are related to distance from knickpoints. Highest rates of erosion and incision are evident towards the south, with decreasing values towards the north, suggesting a link between tectonic activity and erosion.

关键词： Longitudinal profile Erosion Relief Tectonics Qinghai-Tibetan Plateau

Divergence in the ovipositional behavior of the Papilio glaucus group

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Insect Science 2008年第4期15卷 361-367页

作者： Rodrigo j. Mercader j. Mark Scriber Department of Entomology Michigan State University East Lansing MI48824 USA

This study contrasts the ovipositional profiles of four members of the Papilio glaucus group, P. glaucus, P. multicaudatus, P. canadensis, and P. rutulus. We used seven choice oviposition bioassays containing leaves from hosts in seven plant families utilized by members of the P. glaucus group. Specifically, we contrast the overall ovipositional profiles of these species and their acceptance of a host in a novel plant family （Populus tremuloides： Salicaceae） and a host in a putatively ancestral host plant family （Liriodendron tulipifera： Magnoliaceae）. Significant differences were observed between the ovipositional profiles of P. glaucus and P. multicaudatus relative to each other and to P. canadensis and P. rutulus. In contrast, no significant differences were observed between the ovipositional profiles of P. canadensis and P. rutulus, which were also the only species that accepted P. tremuloides. Unlike the acceptance of P. tremuloides, the acceptance of L. tulipifera was present throughout the group despite the inability of the larvae of most species in the group to utilize this host. These results support the prediction of the ＂hierarchical threshold model＂ that ancestral host plants are likely to be retained in the ovipositional hierarchy while novel hosts should only be accepted by derived populations.

关键词： host preference insect-plant interactions Lepidoptera Papilionidae

Contribution of national bioassessment approaches for assessing ecological water security： an AUSRIVAS case study

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Frontiers of Environmental Science & Engineering 2013年第5期7卷 669-687页

作者： Susan j. NICHOLS Fiona j. DYER Institute for Applied Ecology and MDBfutures CRN University of Canberra Canberra ACT 2601 Australia

River managers in Australia are managing in the face of extremes to provide security of water supply for people, production and the environment. Balancing the water requirements of people, environments and econo- mies requires that water security is viewed holistically, not j.st in terms of the water available for human consump- tion. Common definitions of water security focus on the needs of both humans and ecosystems for purposes such as drinking, agriculture and industrial use, and to maintain ecological values. Information about achieving water security for the environment or ecological purposes can be a challenge to interpret because the watering require- ments of key ecological processes or assets are not well understood, and the links between ecological and human values are often not obvious to water users. Yet the concepts surrounding river health are inherently linked to holistic concepts of water security. The measurement of aquatic biota provides a valuable tool for managers to understand progress toward achieving ecological water security obj.ctives. This paper provides a comprehensive review of the reference condition approach to river health assessment, using the development of the Australian River Assessment System （AUSRIVAS） as a case study. We make the link between the biological assessment of river health and assessment of ecological water security, and suggest that such an approach provides a way of reporting that is relevant to the contribution made by ecosystems to water security. The reference condition approach, which is the condition representative of minimally disturbed sites organized by selected physical, chemical, and biological characteristics, is most important for assessing ecological water security obj.ctives.

关键词： ecological water security biological assessment river health

Effect of particle stress tensor in simulations of dense gas-particle flows in fluidized beds

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Particuology 2018年第3期16卷 31-43页

作者： Mohammad Reza Haghgoo Donald j. Bergstrom Raymond j. Spiteri Department of Mechanical Engineering University of Saskatchewan Saskatoon SK SFN 5A9 Canada Department of Computer Science University of Saskatchewan Saskatoon. SK S7N 5C9 Canada

A two-fluid model based on the kinetic theory of granular flow for the rapid-flow regime and the Coulomb friction law for the quasi-static regime is applied to predict the hydrodynamics of dense gas-particle flow in a three-dimensional fluidized bed. Two different models for the particle stress tensor that use different constitutive equations in the elastic-inertial regime are examined to assess their ability to predict bed dynamics. To understand how particle stress models affect structural features of the flow, a quantitative analysis is performed on some important aspects of the mechanics of bubbling beds that have received relatively little attention in the literature. Accordingly, different flow regimes are identified in the context of fluidized beds through the dimensionless inertial number, and the main characteristics of each regime are discussed. In addition, how the particle stress tensor manifests itself in the bubble characteristics, natural frequency of the bed, and particle Reynolds stress are investigated, all of which help to better understand the complex dynamics of the fluidized bed. The numerical results are validated against pub- lished experimental data and demonstrate the significant role of the stress tensor in the elastic-inertial regime.

关键词： Two-fluid model Inertial number Fluidized bed Flow regime Particle Reynolds stress MFIX

NANOCOMPOSITE COATINGS WITH ENHANCED HARDNESS

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 433-442页

作者： j. Musil Department of Physics University of West Bohemia Univerzitní 22 306 14 Pl zeň.

The article reviews the present state of the art in the magnetron sputtering of hart and superhard nanocomposite coatings. It is shown that there are (1) two gr oups of hard and superhard nanocomposites: (i) nc-MN/hard phase and (ii) nc-MN/s oft phase, (2) three possible origins of the enhanced hardness: (i) dislocation- dominated plastic deformation, (ii) cohesive forces between atoms and (iii) nano structure of materials, and (3) huge differences in the microstructure of single - and two-phase films. A main attention is devoted to the formation of nanocryst alline and/or X-ray amorphous films. Such films are created in a vicinity of tra nsitions between (i) crystalline and amorphous phases, (ii) two crystalline phas es of different chemical composition or (iii) two different preferred orientatio ns of grains of the same material from which the coating is composed. The existe nce of the last transition makes it possible to explain the enhanced hardness in single-phase films. The thermal stability and oxidation resistance of hard nano composite films is also shortly discussed.

关键词： nanocomposites single- and two-phase films enhanced hardness,

The earliest archaeobiological evidence of the broad-ening agriculture in China recorded at Xishanping site in Gansu Province

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Science China Earth Sciences 2007年第11期50卷 1707-1714页

作者： j. DODSON Institute of Environmental Research Australian Nuclear Science and Technology Organisation Sydney NSW 2234 Australia

The crop types and agricultural characteristic are reconstructed using the archaeobiological proxies of pollen, seed and phytolith at Xishanping site in Gansu Province between 5250 and 4300 cal a BP. The agricultural activity strengthened in Xishanping from 5100 cal a BP. It appeared the earliest cultivation of prehistoric rice in the most northwest China at 5070 cal a BP. The sudden disappearance of conifers and expansion of chestnut trees is likely to be the result of selective hewing of conifers and cultivation of chestnuts at about 4600 cal a BP. There existed 8 crop types of foxtail millet, broomcorn millet, rice, wheat, barley, oats, soybean and buckwheat at Xishanping between 4650 and 4300 cal a BP, which cover the main crop types of the two origin centers of East and West Asia. Not only has the wheat and barley been approved to spread to northwestern China, but the earliest complexity agriculture in Neo-lithic China appeared in Tianshui, Gansu Province.

关键词： archaeobiological proxy,broadening agriculture,Xishanping site,Gansu Province,4650 cal a BP