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MOVPE-grown AlGaN-based tunnel heterojunctions enabling fully transparent UVC LEDs

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Photonics Research 2019年第5期7卷 I0008-I0012页

作者： Christian Kuhn Luca Sulmoni Martin Guttmann Johannes Glaab norman Susilo Tim wernicke Markus weyers Michael Kneissl Technische Universitat Berlin Institute of Solid State Physics Hardenbergstr. 36 EW6-1 10623 Berlin Germany Ferdinand-Braun-Institut Leibniz-Institut fur Hochstfrequenztechnik Gustav-Kirchhoff-Str. 4 12489 Berlin Germany

we report on AlGaN-based tunnel heterojunctions grown by metalorganic vapor phase epitaxy enabling fully transparent UVC LEDs by eliminating the absorbing p-AlGaN and p-GaN layers. Furthermore, the electrical characteristics can be improved by exploiting the higher conductivity of n-AlGaN layers as well as a lower resistance of n-contacts. UVC LEDs with AlGaN:Mg/AlGaN:Si tunnel junctions exhibiting single peak emission at268 nm have been realized, demonstrating effective carrier injection into the AlGaN multiple quantum well active region. The incorporation of a low band gap interlayer enables effective tunneling and strong voltage ***, the interlayer thickness is systematically varied. Tunnel heterojunction LEDs with an 8 nm thick GaN interlayer exhibit continuous-wave emission powers >3 m w near thermal rollover. External quantum efficiencies of 1.4% at a DC current of 5 m A and operating voltages of 20 V are measured on-wafer. Laterally homogeneous emission is demonstrated by UV-sensitive electroluminescence microscopy images. The complete UVC LED heterostructure is grown in a single epitaxy process including in situ activation of the magnesium acceptors.

关键词： MOVPE-grown AlGaN-based UVC LEDs

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The light from the dark side of the moon

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The light from the dark side of the moon

Continuous applications of biochar to rice: Effects on grain yield and yield attributes

作者： norman G. Gautreau.

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Journal of Integrative Agriculture 2019年第3期18卷 563-570页

作者： HUANG Min FAN Long JIANG Li-geng YANG Shu-ying ZOU Ying-bin norman Uphoff Southern Regional Collaborative Innovation Center for Grain and Oil Crops(CICGO) Hunan Agricultural UniversityChangsha 410128P.R.China International Programs-College of Agriculture and Life Sciences(IP-CALS) Cornell UniversityIthaca 14853USA Key Laboratory of Crop Cultivation and Farming System Guangxi UniversityNanning 530004P.R.China

Biochar is considered as a beneficial soil amendment for crop production. However, limited information is available on the effects of continuous applications of biochar on rice. In this study, a fixed field experiment was conducted in the early and late rice-growing seasons from 2015 to 2017. Grain yield and yield attributes with a widely-grown rice cultivar Zhongzao 39 were compared, with and without applications of biochar in each season. The results showed that grain yield initially decreased with biochar applications in the first three seasons due to decreases in grain weight and harvest index. Although there were further relative decreases in grain weight and harvest index for rice that was supplied with biochar in the fourth to sixth seasons, grain yield was increased(by 4–10%) because of increases in sink size(spikelets per m2) and total biomass. The increased sink size in rice whose soil had been supplied with biochar in the fourth to sixth seasons was achieved by increasing panicle size(spikelets per panicle) or number of panicles, or both. Our study suggests that the positive effects of biochar application on rice yield and yield attributes depend on the duration of biochar application. Further investigations are needed to determine what are the soil and physiological processes for producing yield responses associated with ongoing applications of biochar. Also, it should be evaluated the performance of biochar application combined with other management practices, especially those can increase the grain weight and harvest index in rice production.

关键词： biochar grain yield rice yield attributes

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

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Energy and AI 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

Operations management / norman Gaither, Greg Frazier. 9th ed.

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Speciation with gene flow via cycles of isolation and migration:insights from multiple mangrove taxa

2002年

作者： norman Gaither Greg Frazier.

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National Science Review 2019年第2期6卷 275-288页

作者： Ziwen He Xinnian Li Ming Yang Xinfeng wang Cairong Zhong norman C.Duke Chung-I wu Suhua Shi State Key Laboratory of Biocontrol Guangdong Key Lab of Plant Resources Key Laboratory of Biodiversity Dynamics and Conservation of Guangdong Higher Education InstitutesSchool of Life Sciences Sun Yat-Sen University Department of Ecology and Evolution University of Chicago CAS Key Laboratory of Genome Sciences and Information Beijing Institute of GenomicsChinese Academy of Sciences Hainan Dongzhai Harbor National Nature Reserve Administration Centre for Tropical water and Aquatic Ecosystem Research James Cook University

Allopatric speciation requiring an unbroken period of geographical isolation has been the standard model of neo-Darwinism. while doubts have been repeatedly raised, strict allopatry without any gene flow remains a plausible mechanism in most cases. To rigorously reject strict allopatry, genomic sequences superimposed on the geological records of a well-delineated geographical barrier are necessary. The Strait of Malacca,narrowly connecting the Pacific and Indian Ocean coasts, serves at different times either as a geographical barrier or a conduit of gene flow for coastal/marine species. we surveyed 1700 plants from 29 populations of 5 common mangrove species by large-scale DNA sequencing and added several whole-genome assemblies. Speciation between the two oceans is driven by cycles of isolation and gene flow due to the fluctuations in sea level leading to the opening/closing of the Strait to ocean currents. Because the time required for speciation in mangroves is longer than the isolation phases, speciation in these mangroves has proceeded through many cycles of mixing-isolation-mixing, or MIM, cycles. The MIM mechanism, by relaxing the condition of no gene flow, can promote speciation in many more geographical features than strict allopatry can. Finally, the MIM mechanism of speciation is also efficient, potentially yielding mn(m > 1) species after n cycles.

关键词： speciation gene flow allopatry geographical isolation mangrove

Design of binder jet additive manufactured co-continuous ceramic-reinforced metal matrix composites

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Journal of Materials Science & Technology 2020年第14期47卷 81-90页

作者： Pablo D.Enrique Ehsan Marzbanrad Yahya Mahmoodkhani Ali Keshavarzkermani Hashem Al Momani Ehsan Toyserkani norman Y.Zhou University of waterloo 200 University Ave WWaterlooOntarioN2L 3G1Canada

Ceramic-reinforced metal matrix composites(MMCs)display beneficial properties owing to their combination of ceramic and metal ***,the properties are highly dependent on the reinforcing phase composition,volume fraction and *** fiber or network reinforcement morphologies are difficult and expensive to manufacture,and the often-used discontinuous particle or whisker reinforcement morphologies result in less effective ***,we demonstrate the formation of a co-continuous ceramic-reinforced metal matrix composite using solid-state *** jet additive manufacturing(BJAM)was used to print a nickel superalloy part followed by post-processing via reactive sintering to form a continuous carbide reinforcing phase at the particle *** kinetics of reinforcement formation are investigated in order to develop a relationship between reactive sintering time,temperature and powder composition on the reinforcing phase thickness and volume *** evaluate performance,the wear resistance of the reinforced BJAM alloy 625 MMC was compared to unreinforced BJAM alloy 625,demonstrating a 64%decrease in the specific wear rate under abrasive wear conditions.

关键词： Binder jetting Reactive sintering Metal matrix composite Co-continuous composite wear resistance

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Synthesis of ultrathin rhenium disulfide nanoribbons using nano test tubes

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Nano Research 2022年第2期15卷 1282-1287页

作者： Luke T.norman Johannes Biskupek Graham A.Ranee Craig T.Stoppiello Ute Kaiser Andrei N.Khlobystov School of Chemistry University of NottinghamNottinghamNG72RDUK Central Facility for Electron Microscopy Ulm UniversityAlbert Einstein-Allee 11Ulm 89081Germany Nanoscale and Microscale Research Centre University of NottinghamNottinghamNG72RDUK

The synthesis of ultrathin rhenium disulfide(ReS_(2))nanoribbons within single-walled carbon nanotubes(SwNTs)has been *** decacarbonyl complex is encapsulated into the SwNTs to provide a source of confined rhenium atoms,which readily react with iodine to form discrete nm-sized clusters of rhenium iodide[Re_(6)l_(14)]^(2-) embedded in the *** final step of the synthesis is accomplished by admitting hydrogen sulfide gas into nano test tubes,yielding twisted nanoribbons of rhenium disulfide encapsulated in carbon nanotubes,ReS_(2)@*** width,structure,and composition of rhenium disulfide nanoribbons are strictly controlled by the extreme confinement of the host-SwNT.A holistic analytical approach combining complementary imaging and analysis methods is used at each synthetic step to elucidate the structure and composition of the guest material and reveal the role of the SwNT contributing towards the electronic interactions with encapsulated inorganic *** ReS_(2) nanoribbons are expected to retain the electronic properties of the bulk material,such as direct bandgap,the low dimensional form of this material can be of interest for use in nanoscale electronic devices.

关键词： nanotubes nanoribbons rhenium confinement microscopy spectroscopy

Auxin EvoDevo: Conservation and Diversification of Genes Regulating Auxin Biosynthesis, Transport, and Signaling

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Molecular Plant 2019年第3期12卷 298-320页

作者： Michaela Sylvia Matthes norman Bradley Best Janlo M.Robil Simon Malcomber Andrea Gallavotti Paula McSteen Division of Biological Sciences Interdisciplinary Plant Group and Missouri Maize CenterUniversity of Missouri-Columbia301 Christopher Bond Life Sciences CenterColumbiaMO 65211USA Department of Biological Sciences California State UniversityLongBeachCA 90840USA waksman Institute of Microbiology Rutgers UniversityPiscatawayNJ 08854-8020USA Department of Plant Biology Rutgers UniversityNew BrunswickNJ 08901USA Present address:National Science Foundation 2415 Eisenhower AvenueAlexandriaVA 22314USA

The phytohormone auxin has been shown to be of pivotal importance in growth and development of land *** underlying molecular players involved in auxin biosynthesis, transport, and signaling are quite well understood in ***, functional characterizations of auxin-related genes in economically important crops, specifically maize and rice, are still *** this article, we comprehensively review recent functional studies on auxirelated genes in both maize and rice, compared with what is known in Arabidopsis, and highlight conservation and diversification of their functions. Our analysis is illustrated by phylogenetic analysis and publicly available gene expression data for each gene family, which will aid in the identification of auxin-related genes for future *** challenges and future directions for auxin research in maize and rice are *** in gene editing techniques provide powerful tools for overcoming the issue of redundancy in these gene families and will undoubtedly advance auxin research in crops.

关键词： auxin maize Arabidopsis rice