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Light concentration using hetero-junctions of anisotropic low permittiv.ty metamaterials

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Light(Science & Applications) 2013年第1期2卷 18-26页

作者： Mohammad Memarian george v.eleftheriades The Edward S.Rogers Sr.Department of Electrical and Computer Engineering University of TorontoTorontoOnt.M5S 2E4Canada

Focusing incident power into an area of high concentration is of significant interest for v.rious *** optics,this has been traditionally achiev.d with lenses where a higher curv.ture and lens permittiv.ty typically result in shorter focal distances(low f/D).In this work,we present designs and techniques for collecting,refracting and guiding incident light into an area of high power concentration(a hot spot)at extremely short ***,a flat low-profile focusing mechanism is presented using a hetero-junction of anisotropic metamaterials(MTMs).The hetero-junction is formed from two cleav.d finite slabs of low(near zero)permittiv.ty anisotropic MTMs with rotated optical *** MTMs hav. near zero longitudinal permittiv.ty while matched in the transv.rse *** MTMs are shown to prov.de a unique ability to bend the transv.rse magnetic or p-polarized light away from the normal and along the interface,contrary to conv.ntional dielectrics,and with minimal reflections;hence allowing for a low profile *** in the optical regime are presented using periodic bilayers of metal and *** proposed hetero-junction focusing dev.ce concentrates the normally incident plane wav. and/or beam into a corresponding focal region similar to a lens v.a multiple *** hetero-junction is capable of creating a hot spot v.ry close to the dev.ce,much closer than dielectric lenses and it significantly outperforms the size requirements of thick high curv.ture lenses with low f/D *** proposed designs can find applications in v.rious scenarios including solar and thermo photov.ltaics,photodetectors,concentrated photov.ltaics,non-imaging optics,micro-and nano-Fresnel lenses.

关键词： epsilon near zero focusing light concentration metamaterials non-imaging optics photov.ltaics

Prospects of Huygens’ Metasurfaces for Antenna Applications

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Engineering 2022年第4期8卷 21-26页

作者： george v.eleftheriades Minseok Kim v.sileios G.Ataloglou Ayman H.Dorrah Department of Electrical and Computer Engineering University of TorontoTorontoON M5S 3G8Canada

*** In recent years,there has been an intense research effort by the international community in the field of“artificial”electromagnetic materials,or“metamaterials.”Metamaterials are engineered structures that induce a tailored arrangement of magnetic and electric dipole moments when excited by an incident electromagnetic *** certain conditions,such as when the comprising unit cells are sub-wav.length,metamaterials can be homogenized and described in terms of macroscopic constitutiv. parameters such as permeability,permittiv.ty,and refractiv. index.A summary of the early work on“artificial dielectrics”can be found in Ref.[1].In the ov.r 20-year-old field of metamaterials,the desired macroscopic parameters correspond to extreme properties such as negativ. permittiv.ty,negativ. permeability,and a negativ. refractiv. *** the most recognized metamaterial is that which realizes a negativ. refractiv. index,originally demonstrated at microwav.s and based on a unit cellmade out of a split-ring resonator and a wire[2].In the engineering community,a transmission-line approach was dev.loped for implementing metamaterials with significant adv.ntages,such as reduced transmission losses and wider operating bandwidths[3,4].

关键词： refractiv. arrangement artificial

Electrochemical manufacturing of nanocarbons from carbon dioxide in molten alkali metal carbonate salts： roles of alkali metal cations

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Adv.nces in Manufacturing 2016年第1期4卷 23-32页

作者： Happiness v. Ijije george Z. Chen Department of Chemical and Env.ronmental Engineering Faculty of Engineering University of NottinghamNottingham NG7 2RD UK Department of Chemical and Env.ronmental Engineering and Centre for Sustainable Energy Technologies Faculty ofScience and Engineering University of Nottingham NingboChina Ningbo 315100 People's Republic of China

One simple and fast way to manufacture a useful product from CO2 is to capture the gas by, and then carry out electrolysis in molten alkali metal carbonates. Carbon electro-deposition in molten Li2CO3-Na2CO3- KaCO3 （molar ratio： 43.5：31.5：25.0） has been widely reported in literature. Howev.r, studies in each of the indiv.dual alkali metal carbonates either hav. receiv.d less attention or are simply lacking in literature. Electrochem- ical studies of these molten carbonates are important to understand their underlying processes and reactions during the electrolysis. In this work, cyclic v.ltammograms （Cv.） were recorded in each of the abov.-mentioned molten alkali carbonate salts using a 0.25 mm diameter Pt wire working electrode. In molten Na2CO3 and K2CO3, the main cathodic reaction was likely the formation of alkali metal, while that in Li2CO3 was carbon deposition. The results also suggest that other competing reactions such as CO and alkali metal carbide formation are possible as well in dif- ferent molten salts. On the Cv., the anodic current peaks observ.d are mostly associated with the oxidation of cathodic products. Flake/ring/sheet-like structures and quasi-spherical particles were observ.d in the produced carbon. The morphology of the carbon contained both amorphous and graphitic structures, which v.ried with different electrolysis v.riables.

关键词： Carbon capture and utilisation Electro-deposition Cyclic v.ltammetry Nanocarbons Moltensalts Alkali metal carbonates

MELD v. Child-Pugh and creatinine-modified Child-Pugh score for Dredicting surv.v.l in patients with decompensated cirrhosis

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World Journal of Gastroenterology 2005年第20期11卷 3099-3104页

作者： george v. Papatheodoridis Ev.ngelos Cholongitas Eleni Dimitriadou Giota Touloumi v.ssilios Sev.stianos Athanasios J. Archimandritis 2nd Department of Internal Medicine National Univ.rsity of Athens Medical School Hippokration General Hospital Athens Greece Department of Epidemiology National Univ.rsity of Athens Medical School Athens Greece

AIM: Model of End-stage Liv.r Disease (MELD) score has recently gained wide acceptance ov.r the old Child-Pugh score in predicting surv.v.l in patients with decompensated cirrhosis, although it is more sophisticated. We compared the predictiv. v.lues of MELD, Child-Pugh and creatinine modified Child-Pugh scores in decompensated cirrhosis. METHODS: A cohort of 102 patients with decompensated cirrhosis followed-up for a median of 6 mo was *** types of modified Child-Pugh scores estimated by adding 0-4 points to the original score using creatinine lev.ls as a sixth categorical v.riable were ***: The areas under the receiv.r operating characteristic curv.s did not differ significantly among the four scores, but none had excellent diagnostic accuracy (areas:0.71-0.79). Child-Pugh score appeared to be the worst, while the accuracy of MELD was almost identical with that of modified Child-Pugh in predicting short-term and slightly better in predicting medium-term surv.v.l. In Cox regression analysis, all four scores were significantly associated with surv.v.l, while MELD and creatinine-modified Child-Pugh scores had better predictiv. v.lues (c-statistics: 0.73 and 0.69-0.70) than Child-Pugh score (c-statistics: 0.65). Adjustment for gamma-glutamate transpeptidase lev.ls increased the predictiv. v.lues of all systems (c-statistics: 0.77-0.81). Analysis of the expected and observ.d surv.v.l curv.s in patients subgroups according to their prognosis showed that all models fit the data reasonably well with MELD probably discriminating better the subgroups with worse prognosis. CONCLUSION: MELD compared to the old Child-Pugh and particularly to creatinine-modified Child-Pugh scores does not appear to offer a clear adv.ntage in predicting surv.v.l in patients with decompensated cirrhosis in daily clinical practice.

关键词： Child-Pugh MELD Cirrhosis Decompensated cirrhosis

Ev.luation of Technical Education by Using a Modern Structured MOODLE Laboratory Course, in Relation to Recent Data

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Journal of Intelligent Learning Systems and Applications 2024年第3期16卷 316-339页

作者： Gerasimos v.assopoulos george Albert Karikas Efstathia Papageorgiou Ioannis Psaromiligkos Niki Giannouli Pigi v.assopoulou Petros Karkalousos Department of Biomedical Sciences University of West Attica Athens Greece

E-learning platforms support education systems worldwide, transferring theoretical knowledge as well as soft skills. In the present study high-school pupils’, and adult students’ opinions were ev.luated through a modern structured MOODLE interactiv. course, designed for the needs of the laboratory course “Automotiv. Systems”. The study concerns Greek secondary v.cational education pupils aged 18 and v.cational training adult students aged 20 to 50 years. The multistage, equal size simple random cluster sample was used as a sampling method. Pupils and adult students of each cluster completed structured 10-question questionnaires both before and after attending the course. A total of 120 questionnaires were collected. In general, our findings disclosed that the majority of pupils and adult students had significantly improv.d their knowledge and skills from using MOODLE. They reported strengthening conv.ntional teaching, using the new MOODLE technology. The satisfaction indices improv.d quite, with the differences in their mean v.lues being statistically significant.

关键词： Information and Communication Technologies (ICT) Distance Learning E-Learning Students’ Opinions Education in Greece I.C.T. in Greece Students Pupils Adults Adult Students MOODLE MOOC (v.H.S.) v.cational High Schools (S.H.v.T.) Schools of Higher v.cational Training v.cational Profession Interactiv. Lessons Courses Training Laboratory Course Secondary Education Automotiv. Systems Car Systems

Giga- and terahertz-range nanoemitter based on peapod structure

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Nano Research 2015年第8期8卷 2595-2602页

作者： Michail M. Slepchenkov.Anna S. Kolesnikov. george v. Sav.styanov. Igor S. Nefedov.Ilya v. Anoshkin Albert G. Nasibulin Olga E. Glukhov. Department of Physics Saratov State University Saratov 410012 Russia Department of Radio Science and Engineering Aalto University Aalto P.O. Box 13000 Finland kolkov. Institute of Science and Technology Skolkovo 143025 Russia

We propose a theoretical model of a nanoemitter for giga- and terahertz-range wav.s. The model is based on a peapod structure comprising a carbon nanotube with chiral indices （10, 10）. Three encapsulated and partially polymerized fuUerene C60 molecules and a positiv.ly charged C60 fullerene are trapped inside the nanotube. The motion of the charged fullerene and the radiation frequency were controlled using an external electric field. Stable terahertz radiation at a frequency of 0.36 THz was produced at 300 K with an external electrical field of 10 v.μm. Stable radiation in the gigahertz range was observ.d at 50 K with an electric field below 10 v.m. A theoretical simulation was performed using the tight-binding molecular dynamics method with a description of the v.n der Waals interaction by the Morse potential. The system described by the theoretical model was experimentally observ.d.

关键词： fullerenes nanotubes electronics simulations molecular modeling

Ambispectiv. epidemiological observ.tional study of v.ricella-zoster v.rus infection: An 18 year-single-center Bulgarian experience

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World Journal of v.rology 2024年第3期13卷 82-88页

作者： Hristiana M Batselov. Tsv.telina v.v.likov. Department of Epidemiology and Disaster Medicine Medical UniversityPlovdivUniversity Hospital“St George”Plovdiv 4000Bulgaria Medical Faculty Sofia University St.Kliment OhridskiSofia 1407Bulgaria

BACKGROUND v.ricella(chickenpox)and herpes zoster(shingles)are outcomes of v.ricella-zoster v.rus(v.v.infection,and understanding their incidence trends is v.tal for public health *** To conduct an ambispectiv. epidemiological study by analyzing the main epidemiological characteristics of v.v.infection during an 18 year-period(2000-2018).METHODS We used descriptiv. and epidemiological methods to characterize chickenpox in Bulgaria,the city of Plov.iv.and the region for a period of 18 years(2000-2018).RESULTS The av.rage incidence of v.ricella-zoster infection for the period 2000–2018 in the Plov.iv.region was estimated at 449.58‰.The highest relativ. share of the infection was assessed in the month of January at 13.6%,and the lowest in the months of August and September at 2.9%(both months).The age group most affected by the infection was 1-4 years,followed by 5-9 *** corresponds to the so-called"pro-epidemic population"-a phenomenon typical for airborne infections,confirming their mass impact on the perpetuation of v.v.*** Our findings rev.al significant insights into v.v.epidemiology,including age-specific incidence rates,clinical manifestations,and v.ccination *** comprehensiv. analysis contributes to the broader understanding of v.v.infec-tion dynamics and may inform ev.dence-based prev.ntiv. measures.

关键词： v.ricella-zoster v.rus Epidemiology Incidence trends Chickenpox Shingles Public health Pro-epidemic population Age-specific incidence Clinical manifestations v.ccination impact

Electric field distributions along helium plasma jets

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High v.ltage 2020年第6期5卷 650-653页

作者： george v.Naidis Natalia Yu Babaev. Joint Institute for High Temperatures RAS 125412 MoscowRussia

Results of simulations of streamers propagating along the atmospheric-pressure helium plasma jets ejected from a thin tube into ambient air are presented. The computational model includes the equations gov.rning the helium-air mixture composition along and across the jet, as well as the equations, describing streamer propagation in the mixture, for the electric field and the charged species densities. Streamer v.locity and spatial-temporal profiles of plasma parameters are obtained for v.rious v.lues of the helium flow rate. It is shown, in agreement with av.ilable experimental data, that the electric field v.lues in the heads of streamers increase nearly linearly with the distance from the tube exit and that the slope of this dependence decreases with the growth of the helium flow rate.

关键词： field mixture ambient

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H3亚型禽流感流行的潜在危害和防控建议

科学通报 2024年第10期69卷 1315-1319页

作者：刘金华孙洪磊高福中国农业大学动物医学院兽医公共卫生安全全国重点实验室农业农村部禽流感等家禽重大疾病防控重点实验室北京100193 中国科学院微生物研究所病原微生物与免疫学重点实验室北京100101 中国疾病预防控制中心病毒病预防控制所中国国家流感中心北京102206

21世纪短短的20年间,人类已经历了两次大流行传染病,即2009年甲型H1N1大流行流感和2019年新型冠状病毒感染.另外发生了5次世界卫生组织宣布的“全球关注的公共卫生应急事件”,给全球经济发展、社会稳定和人类健康造成了严重危害(https:/... 详细信息

21世纪短短的20年间,人类已经历了两次大流行传染病,即2009年甲型H1N1大流行流感和2019年新型冠状病毒感染.另外发生了5次世界卫生组织宣布的“全球关注的公共卫生应急事件”,给全球经济发展、社会稳定和人类健康造成了严重危害(https://***/emergencies/situations).大流行传染病的频繁出现警示我们,人兽共患性病毒是引发大流行疫病的重要病原.动物源性流感病毒在历史上导致了至少5次流感大流行,尤其是最近几年,动物流感病毒频繁跨种感染人类的现象让人们担忧其可能催生下一次人类流感大流行[1].

关键词：冠状病毒感染流感病毒防控建议禽流感 H3亚型跨种感染动物源性流感大流行