检索结果-南通市图书馆

Soil Respiration and Litter Decomposition Increased Following Perennial Forb Invasion into an Annual Grassland

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2016年第4期26卷 567-576页

作者： ZHAnG Ling MA Xiaochi WAnG Hong LIU Shuwei evan SIEMAnn ZOU Jianwen College of Forestry Jiangxi Agricultural University College of Resources and Environmental Sciences Nanjing Agricultural University Department of Ecology and Evolutionary Biology Rice University

Exotic plant invasions may alter ecosystem carbon processes, especially when native plants are displaced by plants of a different functional group. Forb invasions into grasslands are common, yet little is known about how they impact carbon cycling. We conducted a field study over 2 years from April 2010 to March 2012 in China to examine changes in soil respiration （Rsoil） following invasion of exotic perennial forb species （Alternanthera philoxeroides or Solidago canadensis） into an annual grassland dominated by a native annual graminoid （Eragrostis pilosa）. Measurements of Rsoil were taken once a week in stands of the native annual graminoid or one of the forb species using static chamber-gas chromatograph method. Aboveground litterfall of each of the three focal species was collected biweekly and litter decomposition rates were measured in a 6-month litterbag experiment. The monthly average and annual cumulative Rsoil increased following invasion by either forb species. The increases in cumulative Rsoil were smaller with invasion of Solidago （36%） than Alternanthera （65%）. Both invasive forbs were associated with higher litter quantity and quality （e.g., C：n ratio） than the native annum graminoid. Compared to the native annual graminoid, the invasive forbs Altevnanthera （155%） and Solidago （361%） produced larger amounts of more rapidly decomposing litter, with the litter decay constant k being 3.8, 2.0 and 1.0 for Alternanthera, Solidago and Eragrostis, respectively. Functional groups of the invasive plants and the native plants they replaced appear to be useful predictors of directions of changes in Rsoil, but the magnitude of changes in Rsoil seems to be sensitive to variations in invader functional traits.

关键词： carbon cycling exotic plant functional group functional traits invasive plants litterfall native plants

Machine Learning Chemical Guidelines for Engineering Electronic Structures in Half-Heusler Thermoelectric Materials

在线全文

学校读者我要写书评

暂无评论

Research 2020年第1期2020卷 978-985页

作者： Maxwell TDylla Alexander dunn Shashwat Anand Anubhav Jain G.Jeffrey Snyder Department of Materials Science and Engineering Northwestern UniversityIL 60208USA Department of Materials Science and Engineering UC BerkeleyCA 94720USA Lawrence Berkeley national Laboratory Energy Technologies AreaCA 94720USA

Half-Heusler materials are strong candidates for thermoelectric applications due to their high weighted mobilities and power factors,which is known to be correlated to valley degeneracy in the electronic band ***,there are over 50 known semiconducting half-Heusler phases,and it is not clear how the chemical composition affects the electronic *** all the n-type electronic structures have their conduction band minimum at either theΓ-or X-point,there is more diversity in the p-type electronic structures,and the valence band maximum can be at either theΓ-,L-,or ***,we use high throughput computation and machine learning to compare the valence bands of known half-Heusler compounds and discover new chemical guidelines for promoting the highly degenerate W-point to the valence band *** do this by constructing an“orbital phase diagram”to cluster the variety of electronic structures expressed by these phases into groups,based on the atomic orbitals that contribute most to their valence ***,with the aid of machine learning,we develop new chemical rules that predict the location of the valence band maximum in each of the *** rules can be used to engineer band structures with band convergence and high valley degeneracy.

关键词： structure valence bands

(Re)assessing Climate-Smart Agriculture practices for sustainable food systems outcomes in sub-Saharan Africa:The case of Bono East Region,Ghana

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geography and Sustainability 2023年第2期4卷 112-126页

作者： Philip Tetteh Quarshie Seidu Abdulai evan D.G.Fraser Deparment of Geography Environment and Geomatics&Guelph Institute of Development StudiesCollege of Social and Applied Human ScienceUniversity of Guelph50 Stone Rd EGuelphON N1H 2W1 Canada Global Agri-Business Solutions InC.54-480 Grey Street BrantfordON N3S 7S5 Canada Deparment of Food Agricultural and Resource Economics Ontario Agriculture CollegeUniversity of Guelph50 Stone Rd EGuelphON N1G 2W1 Canada Department of Geography Environment and Geomatics&Arrell Food InstituteUniversity of Guelph50 Stone Rd EGuelphON N1H 2W1 Canada

This research paper assesses the reality of Climate-Smart Agriculture(CSA)practices’potential to promote the outcomes of sustainable food systems(SFS)within Ghana’s smallholding agriculture *** study demon-strates that rural farmers generally perceive CSA’s contribution to‘food and nutrition security’and‘economic performance’as more important than CSA’s contribution to‘social equity’and‘environmental stewardship’.From a narrow perspective,the study demonstrates that farmers perceive CSA’s potential to‘prevent pest and disease outbreaks’and‘increase human capital information’as the most important contribution of CSA to SFS *** contrast,CSA’s potential to promote environmental stewardship is perceived as the least important among Ghana’s rural *** enormity of displacement of smallholders’perceptions at large is motivated by de-mographic,socioeconomic and ecological ***,the CSA for SFS outcomes narratives is driven by farmers’self-apprise,social networks and other local information dissemination ***,research findings suggest farmers’awareness of CSA practices and interventions is deficient owing to unmet training and information needs for approximately 82%of the CSA practices and *** situation elucidates the dichotomy of CSA practices’narratives as tools for attaining food,nutrition security and economic performance to the detriment of critical issues such as increasing awareness and building farmers’capacity to engage with CSA practices while also managing socio-ecological trade-offs that emerge over time due to engagement with ***(re)orientation is needed across the scale to drive CSA practices and interventions that confine cli-mate adaptation and food production practices within safe planetary boundaries without undermining social,economic,food and nutrition security needs.

关键词： Climate adaptation Climate-Smart Agriculture Ghana Smallholder farmers Sustainable food systems Sub-Saharan Africa

Stopover behavior of Red-eyed Vireos(Vireo olivaceus) during fall migration on the coast of the Yucatan Peninsula

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Avian Research 2021年第4期12卷 491-502页

作者： Richard evan Feldman Antonio Celis-Murillo Jill L.Deppe Michael P.Ward Centro de Investigación Científica de Yucatán Unidad de Recursos NaturalesMeridaYucatánMexico Prairie Research Institute Illinois Natural History SurveyUniversity of IllinoisUrbana-ChampaignIllinoisUSA U.S.Geological Survey Eastern Ecological Science CenterPatuxent Research RefugeLaurelMDUSA national Audubon Society WashingtonDCUSA Department of natural Resources and Environmental Sciences University of IllinoisUrbana-ChampaignIllinoisUSA.

Background: For migrating birds, stopover requires spending time and energy that otherwise could be allocated to flying. Thus, birds optimally refuel their subsequent migratory flight by reducing stopover duration or foraging activ-ity in food-rich environments. In coastal habitats, birds may forego refueling and take short stopovers irrespective of local food availability. Given the paucity of studies exploring how migrants adjust stopover behavior in response to temporal variation in food availability, especially in the neotropics, we fixed radio tags to 51 Red-eyed Vireos(Vireo olivaceous) over two years at two sites on the coast of Mexico's Yucatan ***: We applied VHF radio tags during the fall of 2016 and 2017, and tracked birds using automatic and manual receiving units. We estimated stopover duration and activity levels(one site only) for between six and fifteen birds,depending on site and year. We measured fruit availability weekly along the net lanes where we captured birds. We used a generalized linear model to estimate the relationships between stopover duration/activity level and fruit den-sity, bird body mass and year. We interpreted relationships for the model with the lowest AICc ***: We found that approximately half of the birds departed on the same day they were captured. For the birds that stayed longer, we could not discern whether they did so because they were light, or fruit density was high. On the other hand, lighter birds were more active than heavier birds but only in one of the two ***: Given our results, it is unlikely that Red-eyed Vireos refuel along the Yucatan coast. However, they still likely need to recuperate from crossing the Gulf of Mexico, which may necessitate foraging more often if in poor body condition. If the birds then move inland then stopover should be thought of as a large-scale phenomenon, where habitats with different functions may be spread out over a broad landscape.

关键词： Coastal dune Fruit Geographic barrier Gulf of Mexico Phenology Stopover Time?minimization

Pseudocapacitive Vanadium-based Materials toward High-Rate Sodium-Ion Storage

在线全文

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2020年第3期3卷 221-234页

作者： Qiulong Wei Ryan H.De Block Danielle M.Butts Christopher Choi Bruce dunn Department of Materials Science and Engineering Fujian Key Laboratory of Materials GenomeCollege of MaterialsXiamen UniversityXiamen Fujian 361005China national Research Council Postdoctoral Associate U.S.Naval Research LaboratoryWashington DC 20375USA Department of Materials Science and Engineering University of California Los AngelesLos Angeles CA 90095–1595USA

Sodium-ion battery materials and devices are promising candidates for largescale applications,owing to the abundance and low cost of sodium *** sodium-ion pseudocapacitive materials provide one approach for achieving high capacity at high rates,but are currently not well ***,a comprehensive overview of the fundamentals and electrochemical behaviors of vanadium-based pseudocapacitive materials for sodium-ion storage is *** insight of sodium-ion storage mechanisms for various vanadium-based materials,including vanadium oxides,vanadates,vanadium sulfides,nitrides,and carbides are systematically discussed and *** particular,areas for further development to improve fundamental understanding of electrochemical and structural properties of materials are ***,we provide a perspective on the application of pseudocapacitive materials in high-power and high-energy sodium-ion storage devices(e.g.,sodium-ion capacitors).

关键词： charge-storage mechanism nanomaterials pseudocapacitance sodium-ion capacitors vanadium-based materials

在线全文

学校读者我要写书评

暂无评论

自动沙拉机的兴起

商业周刊（中文版） 2023年第10期 58-63页

作者： ELIZABETH G.dunn evan JEnKInS(摄影) 不详

Sweetgreen是一个充满小资情调的沙拉连锁品牌,其联合创始人兼首席品牌官纳撒尼尔·茹(nathaniel Ru)站在即将开业的一家门店里,说道:“我们一直尽量对这个东西保持低调,因为它还没有得到证明,我们不想做出任何承诺。”他指的是耸立在... 详细信息

Sweetgreen是一个充满小资情调的沙拉连锁品牌,其联合创始人兼首席品牌官纳撒尼尔·茹(nathaniel Ru)站在即将开业的一家门店里,说道:“我们一直尽量对这个东西保持低调,因为它还没有得到证明,我们不想做出任何承诺。”他指的是耸立在柜台后面的一架不锈钢玻璃装置,它和20世纪60年代的计算机主机差不多大小。这台设备名叫InfiniteKitchen,它的工作是装配数百份大丰收碗(harvest bowl)、羽衣甘蓝凯撒沙拉(kale Caesars)以及这家餐厅每天都会出产的许多其他精美沙拉组合。

关键词：计算机主机羽衣甘蓝小资情调沙拉

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

富锂巨星的观测研究

天文学进展 2012年第4期30卷 453-466页

作者：符晓婷邓李才 Kirby evan n Guhathakurta Puragra 中国科学院光学天文重点实验室北京100012 中国科学院国家天文台北京100012 中国科学院研究生院北京100049 California Institute of Technology 1200 E.California Blvd.MC 249-17PasadenaCA 91125USA Hubble Fellow University of California Observatories/Lick Observatory University of California1156 High St.Santa CruzCA 95064USA

锂在温度达到T〉2．5×10^6K时即参与’Li（p，a）4He反应燃烧，经典恒星理论推测，当恒星演化到红巨星阶段时，由于向内非常延伸的对流包层的存在，锂的丰度A（Li）=12＋lg[n（Li）／n（H）1应为A（Li）〈0．5。但是，陆续有处于不同... 详细信息

锂在温度达到T〉2．5×10^6K时即参与’Li（p，a）4He反应燃烧，经典恒星理论推测，当恒星演化到红巨星阶段时，由于向内非常延伸的对流包层的存在，锂的丰度A（Li）=12＋lg[n（Li）／n（H）1应为A（Li）〈0．5。但是，陆续有处于不同光谱型、不同演化阶段的富锂巨星被发现，其中一些巨星的锂丰度甚至远超出宇宙大爆炸的原初锂丰度，给经典恒星演化模型带来了难题。回顾了从恒星主序到巨星支的锂丰度观测研究历史，并详细介绍了我们对银河系矮星系中富锂巨星的最新发现，总结了所有富锂巨星的观测证据，以及为解决此难题所提出的理论解释。

关键词：恒星演化巨星元素丰度锂

Data–driven decision–making for lost circulation treatments: A machine learning approach

在线全文

学校读者我要写书评

暂无评论

能源与人工智能(英文) 2020年第2期2卷 125-135页

作者： Husam H.Alkinani Abo Taleb T.Al-Hameedi Shari dunn-norman Missouri University of Science and Technology 1201 N State StRollaMO 65409USA

Lost circulation is an expensive and critical problem in the drilling *** of dollars are spent every year to mitigate or stop this *** this work,data from over 3000 wells were collected from multiple *** data went through a processing step where all outliers were removed and decision rules were set *** machine learning methods(support vector machine,decision trees,logistic regression,artificial neural networks,and ensemble trees)were used to create a model that can predict the best lost circulation treatment based on the type of loss and the reason of loss.5-fold cross-validation was conducted to ensure no overfitting in the created *** using all the aforementioned machine learning methods to train models to choose the best lost circulation treatment,overall,the results showed that support vector machine had the highest accuracy among the other ***,it was selected to train the *** created model went through quality control/quality assurance(QC/QA)to limit the results of incorrect *** treatments were suggested to treat partial loss,four to treat severe loss,and seven for complete loss,based on the reason of *** addition,a formalized methodology to respond to lost circulation was provided to help the drilling personnel handling lost circulation in the field.

关键词： Machine learning Lost circulation Data-driven Classification

In Vitro assessment of the nutritive value of expanded soybean meal for dairy cattle

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2012年第2期3卷 93-99页

作者： Eman A Elwakeel evan C Titgemeyer Zongjia J Cheng Abdelaziz M nour Mohamed EA nasser Department of Animal & Fish Production Faculty of Agriculture Alexandria University Department of Animal Sciences and Industry Kansas State University American Soybean Association-International Marketing

Little information is available about the nutritive value of expanded soybean meal, which is produced by expansion of soybeans prior to solvent extraction of the oil. During processing, expanded soybean meal is subjected to additional heat, which might increase the concentration of ruminally undegraded protein. Processing of soybeans with heat during oil extraction could affect lysine availability by increasing ruminally undegraded protein or by impairing intestinal digestion. Our objective was to compare solvent and expanded soybeans with regard to chemical composition and nutritive value for dairy cattle. Samples of expanded soybean meal （n = 14） and solventextracted soybean meal （n = 5） were obtained from People＇s Republic of China to study effects of the expansion process on nutritive value for dairy cattle. Solvent-extracted soybean meal （n = 2） and mechanically extracted （heated） soybean meal （n = 2） from the United States served as references for comparison. Samples were analyzed for crude fat, long-chain fatty acids, crude protein, amino acids, chemically available lysine, in situ ruminal protein degradation, and in vitro intestinal digestibility. no differences were found between solvent-extracted soybean meals from China and expanded soybean meals from China for crude fat, crude protein, amino acids, or chemically available lysine. In situ disappearance of nitrogen, ruminally undegraded protein content, and in vitro intestinal digestion of the ruminally undegraded protein were generally similar between solvent-extracted soybean meals made in China and expanded soybean meals made in China; variation among soybean meals was small. Results indicate that the additional heat from the expansion process was not great enough to affect the nutritive value of soybean meal protein for ruminants. Although expansion may improve the oil extraction process, the impact on the resulting soybean meal is minimal and does not require consideration when formulating ruminant di

关键词： Digestibility Escape Lysine Protein Rumen