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半导体CdTe纳米晶的合成及其光学性能 被引量:12
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作者 王韦 张纪梅 +3 位作者 郭宁 张军 崔永芳 刘桂芬 《应用化学》 CAS CSCD 北大核心 2006年第4期435-437,共3页
以巯基乙酸(HSCH2COOH)为稳定剂,在水溶液中合成半导体CdTe纳米晶。通过隧道扫描显微镜(STM)、紫外吸收光谱、荧光光谱等测试技术对所得的样品进行表征。结果表明,随着回流时间的增加,CdTe半导体纳米晶的粒径变大,其荧光发射峰和紫外吸... 以巯基乙酸(HSCH2COOH)为稳定剂,在水溶液中合成半导体CdTe纳米晶。通过隧道扫描显微镜(STM)、紫外吸收光谱、荧光光谱等测试技术对所得的样品进行表征。结果表明,随着回流时间的增加,CdTe半导体纳米晶的粒径变大,其荧光发射峰和紫外吸收峰发生红移,荧光颜色从绿色逐渐向红色过渡。 展开更多
关键词 CDTE 纳米晶 光学性能
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不同尺寸ZnS:Mn纳米粒子的静压光致发光研究
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作者 苏付海 马宝珊 +2 位作者 丁琨 李国华 CHEN Wei 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2005年第2期84-88,共5页
测量了ZnS:Mn纳米粒子以及相应体材料在不同压力下的光致发光谱.随压力增大,来源于Mn2+离子的4T1 6A1 跃迁的桔黄色发光明显红移.体材料和 10, 4. 5, 3. 5, 3nm的ZnS:Mn纳米粒子中Mn2+发光的压力系数分别是-29. 4±0. 3和-30. 1... 测量了ZnS:Mn纳米粒子以及相应体材料在不同压力下的光致发光谱.随压力增大,来源于Mn2+离子的4T1 6A1 跃迁的桔黄色发光明显红移.体材料和 10, 4. 5, 3. 5, 3nm的ZnS:Mn纳米粒子中Mn2+发光的压力系数分别是-29. 4±0. 3和-30. 1±0. 3, -33. 3±0. 6, -34. 6±0. 8, -39±1meV/GPa,压力系数的绝对值随粒子尺寸减小而增大,该种尺寸关系由晶体场场强Dq和Racah参数B值的尺寸依赖性引起. 1nm样品的Mn2+发光的特殊压力行为是因为样品的粒子尺寸比较小,另外,分布在Y型沸石中的纳米粒子的表面状况也不同于其它样品. 展开更多
关键词 ZNS:MN 纳米粒子 MN^2+ Racah参数 静压 压力系数 光致发光谱 尺寸依赖性 粒子尺寸 压力行为 尺寸关系 表面状况 Y型沸石 体材料 meV 绝对值 尺寸比 样品 晶体场 增大
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Management of incidentally discovered appendiceal neuroendocrine tumors after an appendicectomy 被引量:2
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作者 JoséLuis Muñoz de Nova Jorge Hernando +6 位作者 Miguel Sampedro Núñez Greissy Tibisay Vázquez Benítez Eva María Triviño Ibáñez María Isabel del Olmo García Jorge Barriuso Jaume Capdevila Elena Martín-Pérez 《World Journal of Gastroenterology》 SCIE CAS 2022年第13期1304-1314,共11页
Appendiceal neuroendocrine tumors(aNETs)are an uncommon neoplasm that is relatively indolent in most cases.They are typically diagnosed in younger patients than other neuroendocrine tumors and are often an incidental ... Appendiceal neuroendocrine tumors(aNETs)are an uncommon neoplasm that is relatively indolent in most cases.They are typically diagnosed in younger patients than other neuroendocrine tumors and are often an incidental finding after an appendectomy.Although there are numerous clinical practice guidelines on management of a NETs,there is continues to be a dearth of evidence on optimal treatment.Management of these tumors is stratified according to risk of locoregional and distant metastasis.However,there is a lack of consensus regarding tumors that measure 1-2 cm.In these cases,some histopathological features such as size,tumor grade,presence of lymphovascular invasion,or mesoappendix infiltration must also be considered.Computed tomography or magnetic resonance imaging scans are recommended for evaluating the presence of additional disease,except in the case of tumors smaller than 1 cm without additional risk factors.Somatostatin receptor scintigraphy or positron emission tomography with computed tomography should be considered in cases with suspected residual or distant disease.The main point of controversy is the indication for performing a completion right hemicolectomy after an initial appendectomy,based on the risk of lymph node metastases.The main factor considered is tumor size and 2 cm is the most common threshold for indicating a colectomy.Other factors such as mesoappendix infiltration,lymphovascular invasion,or tumor grade may also be considered.On the other hand,potential complications,and decreased quality of life after a hemicolectomy as well as the lack of evidence on benefits in terms of survival must be taken into consideration.In this review,we present data regarding the current indications,outcomes,and benefits of a colectomy. 展开更多
关键词 Neuroendocrine tumors Carcinoid tumor Appendiceal neoplasms COLECTOMY Neoplasm grading Treatment outcome
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Relationship between pre-pubertal nutrition plane with reproduction performanceand milk quality in Kurdish female kids
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作者 Sedigheh Menatian Mostafa Nemati +3 位作者 Mehdi Rashnavadi Ali Salimi Mohammad Rashid Taheri Farshad Yasemi 《Asian pacific Journal of Reproduction》 2017年第4期172-175,共4页
Objective:To investigate the reproductive performance and milk quality to nutrition pre-pubertal plane in Kurdish female kids.Methods: Forty Kurdish female kids [aged (28.0±6.6) d and weighted (7.56±1.10) kg... Objective:To investigate the reproductive performance and milk quality to nutrition pre-pubertal plane in Kurdish female kids.Methods: Forty Kurdish female kids [aged (28.0±6.6) d and weighted (7.56±1.10) kg] were assigned randomly in pre-weaning period to one of two practical diets: low quality diet (LQD) [87 g CP/kg dray matter (DM) and 2.02 Mcal ME/kg DM], and high quality diet (HQD), (148 g CP/kg DM and 2.50 Mcal ME/kg DM). At weaning, from each group, one half of kids was separated randomly and allocated to LQD or HQD. Consequently, in post-weaning period, there were four treatment groups including: LQD pre and post-weaning (L-L), control group and LQD pre-weaning and HQD post-weaning (L-H);HQD pre-weaning and LQD post-weaning (H-L), HQD pre- and post-weanin (H-H). From 30 to 180 d of age, body weight and DM intake were determined every 2 wk.Results:Results showed that the HQD treatment enhanced body weight and DM intake during pre-weaning period, in comparison with the LQD treatment (P<0.01). During post-weaning, kids of H-H treatment had higher DM intake compared with other kid's treatments. Kids fed the HQD treatment had greater withers height compared to kids on the LQD treatment at 90 d of age (P<0.01). Kids in the L-H and H-H groups weighed more and were younger at puberty. In the period of pre-pubertal, diet plan was not significantly affected milk yield and reproductive performance at the first lactation.Conclusions:Overall, management strategies that have been used to availability of nutrition could increase growth and feed intake in Kurdish female kids. In addition, these strategic programs should be enhancing economic characteristics at the start of puberty of kid in goat husbandry. 展开更多
关键词 KIDS Iran MILK NUTRITION REPRODUCTION
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Synthesis and Characterization of a Polymeric Material Blended to Bone Forming Elements
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作者 Esther Perez-Torrero Leticia Esmeralda Luna-Rodriguez +3 位作者 Gerardo Antonio Fonseca-Hernandez Jose Santos-Cruz Eric Mauricio Rivera-Muñoz Maria Lucero Gomez-Herrera 《Journal of Biosciences and Medicines》 2023年第9期181-194,共14页
A synthetizing material blended with two distinct proteins (collagen and casein) and mineral mixture, was developed in order to evaluate their properties suitable for possible applications in the biomedical such as in... A synthetizing material blended with two distinct proteins (collagen and casein) and mineral mixture, was developed in order to evaluate their properties suitable for possible applications in the biomedical such as inducing the regeneration of damaged bone, either due to an accident or illness. Samples were evaluated by 1) Mechanical properties tests under the bending, 2) Scanning electronic microscopy and 3) Infrared spectroscopy were carried out. The results showed that the developed material has breaking strength and structure characteristics associated with the protein used in their composition. This fact suggests that the used protein determines the resistance of the material, in such a way according to the required use, being able to choose appropriate strength and duration either short or long time. The material composition for specific use, in order to find the most suitable mixture for bone replacement, or induce bone recovery, according to the required properties similar to those of damaged living tissue. 展开更多
关键词 MINERALS BONE POLYMETHYLMETHACRYLATE CASEIN COLLAGEN Mechanical Properties Infrared Scanning Electronic Microscopy
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Weak Type Estimates for Commutators of Littlewood-Paley Operators on Herz-Type Spaces
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作者 QU Meng SHU Li-sheng 《安徽师范大学学报(自然科学版)》 CAS 北大核心 2012年第1期7-10,共4页
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Representations of molecules and materials for interpolation of quantum-mechanical simulations via machine learning 被引量:5
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作者 Marcel F.Langer Alex Goeßmann Matthias Rupp 《npj Computational Materials》 SCIE EI CSCD 2022年第1期378-391,共14页
Computational study of molecules and materials from first principles is a cornerstone of physics,chemistry,and materials science,but limited by the cost of accurate and precise simulations.In settings involving many s... Computational study of molecules and materials from first principles is a cornerstone of physics,chemistry,and materials science,but limited by the cost of accurate and precise simulations.In settings involving many simulations,machine learning can reduce these costs,often by orders of magnitude,by interpolating between reference simulations.This requires representations that describe any molecule or material and support interpolation.We comprehensively review and discuss current representations and relations between them.For selected state-of-the-art representations,we compare energy predictions for organic molecules,binary alloys,and Al–Ga–In sesquioxides in numerical experiments controlled for data distribution,regression method,and hyper-parameter optimization. 展开更多
关键词 ALLOYS CORNERS PRECISE
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Accelerating materials-space exploration for thermal insulators by mapping materials properties via artificial intelligence 被引量:2
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作者 Thomas A.R.Purcel Matthias Scheffler +1 位作者 Luca M.Ghiringhelli Christian Carbogno 《npj Computational Materials》 SCIE EI CSCD 2023年第1期1204-1215,共12页
Reliable artificial-intelligence models have the potential to accelerate the discovery of materials with optimal properties for various applications,including superconductivity,catalysis,and thermoelectricity.Advancem... Reliable artificial-intelligence models have the potential to accelerate the discovery of materials with optimal properties for various applications,including superconductivity,catalysis,and thermoelectricity.Advancements in this field are often hindered by the scarcity and quality of available data and the significant effort required to acquire new data.For such applications,reliable surrogate models that help guide materials space exploration using easily accessible materials properties are urgently needed.Here,we present a general,data-driven framework that provides quantitative predictions as well as qualitative rules for steering data creation for all datasets via a combination of symbolic regression and sensitivity analysis.We demonstrate the power of the framework by generating an accurate analytic model for the lattice thermal conductivity using only 75 experimentally measured values.By extracting the most influential material properties from this model,we are then able to hierarchically screen 732 materials and find 80 ultra-insulating materials. 展开更多
关键词 artificial THERMAL PROPERTIES
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The NOMAD Artificial-Intelligence Toolkit:turning materials-science data into knowledge and understanding 被引量:1
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作者 Luigi Sbailò Ádám Fekete +1 位作者 Luca M.Ghiringhelli Matthias Scheffler 《npj Computational Materials》 SCIE EI CSCD 2022年第1期2385-2391,共7页
We present the Novel-Materials-Discovery(NOMAD)Artificial-Intelligence(AI)Toolkit,a web-browser-based infrastructure for the interactive AI-based analysis of materials-science findable,accessible,interoperable,and reu... We present the Novel-Materials-Discovery(NOMAD)Artificial-Intelligence(AI)Toolkit,a web-browser-based infrastructure for the interactive AI-based analysis of materials-science findable,accessible,interoperable,and reusable(FAIR)data.The AI Toolkit readily operates on the FAIR data stored in the central server of the NOMAD Archive,the largest database of materials-science data worldwide,as well as locally stored,users’owned data.The NOMAD Oasis,a local,stand-alone server can be also used to run the AI Toolkit.By using Jupyter notebooks that run in a web-browser,the NOMAD data can be queried and accessed;data mining,machine learning,and other AI techniques can be then applied to analyze them.This infrastructure brings the concept of reproducibility in materials science to the next level,by allowing researchers to share not only the data contributing to their scientific publications,but also all the developed methods and analytics tools.Besides reproducing published results,users of the NOMAD AI toolkit can modify the Jupyter notebooks toward their own research work. 展开更多
关键词 TOOLKIT BROWSER SERVER
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Finding predictive models for singlet fission by machine learning 被引量:3
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作者 Xingyu Liu Xiaopeng Wang +5 位作者 Siyu Gao Vincent Chang Rithwik Tom Maituo Yu Luca M.Ghiringhelli Noa Marom 《npj Computational Materials》 SCIE EI CSCD 2022年第1期669-678,共10页
Singlet fission(SF),the conversion of one singlet exciton into two triplet excitons,could significantly enhance solar cell efficiency.Molecular crystals that undergo SF are scarce.Computational exploration may acceler... Singlet fission(SF),the conversion of one singlet exciton into two triplet excitons,could significantly enhance solar cell efficiency.Molecular crystals that undergo SF are scarce.Computational exploration may accelerate the discovery of SF materials.However,many-body perturbation theory(MBPT)calculations of the excitonic properties of molecular crystals are impractical for large-scale materials screening.We use the sure-independence-screening-and-sparsifying-operator(SISSO)machine-learning algorithm to generate computationally efficient models that can predict the MBPT thermodynamic driving force for SF for a dataset of 101 polycyclic aromatic hydrocarbons(PAH101).SISSO generates models by iteratively combining physical primary features.The best models are selected by linear regression with cross-validation.The SISSO models successfully predict the SF driving force with errors below 0.2 eV.Based on the cost,accuracy,and classification performance of SISSO models,we propose a hierarchical materials screening workflow.Three potential SF candidates are found in the PAH101 set. 展开更多
关键词 MATERIALS SINGLET INDEPENDENCE
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Automatic identification of crystal structures and interfaces via artificial-intelligence-based electron microscopy
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作者 Andreas Leitherer Byung Chul Yeo +1 位作者 Christian H.Liebscher Luca M.Ghiringhelli 《npj Computational Materials》 SCIE EI CSCD 2023年第1期489-499,共11页
Characterizing crystal structures and interfaces down to the atomic level is an important step for designing advanced materials.Modern electron microscopy routinely achieves atomic resolution and is capable to resolve... Characterizing crystal structures and interfaces down to the atomic level is an important step for designing advanced materials.Modern electron microscopy routinely achieves atomic resolution and is capable to resolve complex arrangements of atoms with picometer precision.Here,we present AI-STEM,an automatic,artificial-intelligence based method,for accurately identifying key characteristics from atomic-resolution scanning transmission electron microscopy(STEM)images of polycrystalline materials.The method is based on a Bayesian convolutional neural network(BNN)that is trained only on simulated images.AI-STEM automatically and accurately identifies crystal structure,lattice orientation,and location of interface regions in synthetic and experimental images.The model is trained on cubic and hexagonal crystal structures,yielding classifications and uncertainty estimates,while no explicit information on structural patterns at the interfaces is included during training.This work combines principles from probabilistic modeling,deep learning,and information theory,enabling automatic analysis of experimental,atomic-resolution images. 展开更多
关键词 MATERIALS CRYSTAL ESTIMATES
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Variability and change of climate extremes from indigenous herder knowledge and at meteorological stations across central Mongolia
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作者 Sukh TUMENJARGAL Steven RFASSNACHT +6 位作者 Niah BHVENABLE Alison PKINGSTON Maria EFERNANDEZ-GIMENEZ Batjav BATBUYAN Melinda JLAITURI Martin KAPPAS GADYABADAM 《Frontiers of Earth Science》 SCIE CAS CSCD 2020年第2期286-297,共12页
In semi-arid regions,air temperatures have increased in the last decades more than in many other parts of the world.Mongolia has an arid/semi-arid climate and much of the population are herders whose livelihoods depen... In semi-arid regions,air temperatures have increased in the last decades more than in many other parts of the world.Mongolia has an arid/semi-arid climate and much of the population are herders whose livelihoods depend upon limited water resources that fluctuate with a variable climate.Herders were surveyed to identify their observations of changes in climate extremes for two soums of central Mongolia,Ikh-Tamir in the forest steppe north of the Khangai Mountains and Jinst in the desert steppe south of the mountains.The herders’indigenous knowledge of changes in climate extremes mostly aligned with the station-based analyses of change.Temperatures were warming with more warm days and nights at all stations.There were fewer cool days and nights observed at the mountain stations both in the summer and winter,yet more cool days and nights were observed in the winter at the desert steppe station.The number of summer days is increasing while the number of frost days is decreasing at all stations.The results of this study support further use of local knowledge and meteorological observations to provide more holistic analysis of climate change in different regions of the world. 展开更多
关键词 climate change climate extreme indices indigenous knowledge systems temperature PRECIPITATION
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