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Ultraviolet discharges from a radio-frequency system for potential biological/chemical applications

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Chinese Physics B 2017年第8期26卷 157-161页

作者： Joseph Ametepe Sheng Peng dennis Manos Georgia Gwinnett College School of Science and TechnologyLawrenceville-GA 30078USA EXFO Mississaugaon Canada L5N 6H7 College of William and Mary Department of PhysicsWilliamsburgVA 2385USA

In this work, we describe a new electrode-less radio-frequency（RF） excitation technique for generating excimers in the vacuum ultraviolet（VUV） and ultraviolet（UV） spectral regions for potential biological/chemical applications. Spectra data of Xe~＊_2, XeI~＊, and KrI~＊ generated by this new technique are presented. Optical efficiency of the lamp system ranges from 3% to 6% for KrI~＊, 7% to 13% for XeI~＊, and 15% to 20% for Xe~＊_2. Also, results of irradiating E-coli with XeI~＊discharge from this lamp system is presented to show one of the promising applications of such electrode-less *** new RF lamp system offers an interesting addition to the already existing technologies for generating VUV and UV light for various biological, physical, and chemical processes especially those requiring large area for high productivity.

关键词： radio-frequency ultraviolet light Xe2* XeI* KrI* excimers escherichia coli

The Study of Deposition Parameters, Properties for PVD Ti_xN and Cr_xN Coatings Using a Closed Field Unbalanced Magnetron Sputter Ion Plating System

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材料热处理学报 2004年第5B期25卷 841-846页

作者： HailinSun SusanField JianChen dennis.G.Teer TeerCoatingsLtd. WestStoneHouseBerryHillIndustrialEstateDroitwichWR99ASUK StateKeyLaboratoryofMechanicalBehaviourforMaterialss Xi＇anJiaotongUniversityP.R.CHINA

Closed Field Unbalanced Magnetron Sputter Ion Plating (CFUBMSIP) systems have been used increasingly for PVD coating in recent years. TiN and CrN coatings, commonly used as the basic coating for a number of different hard coatings, have been chosen to study the coating process parameters for the CFUBMSIP system. In this paper, the process parameters, such as substrate temperature, substrate bias and OEM control, have been carefully examined to achieve hard and wear-resistance coatings with good adhesion. The coating structure and orientation were found to change according to the coating parameters. The Rockwell test and Scratch test were carried out to examine the coating adhesion; pin-on-disc testing was used to estimate the wear-resistant; micro-hardness was also used to determine coating hardness. HSS drill testing has been carried out to study the general properties of the coating for cutting tool application. A combination of process parameters can be selected to achieve good performance for the TiN and CrN coatings.

关键词： PVD 衬底温度磁控管溅射 TixN涂层 CrxN涂层 OEM

Rainer Schulzer,Inoue Enryō:A Philosophical Portrait(reviewed by dennis Prooi)

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Frontiers of Philosophy in China 2021年第1期16卷 161-165页

作者： dennis Prooi The Hong Kong University of Science and Technology

In his timely book Inoue Enryo:A Philosophical Portrait,Rainer Schulzer offers a detailed study of the life and works of Inoue Enryo(1858-1919),a philosopher active during the Meiji period(1868-1912)who was one of the... 详细信息

关键词： driving Inoue Rain

Determination of Hydroxylated Polybrominated Diphenyl Ethers in Blood from Baltic Grey Seals

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Journal of Analysis and Testing 2019年第4期3卷 287-294页

作者： dennis Lindqvist Lillemor Asplund Department of Environmental Science and Analytical Chemistry Stockholm University10691 StockholmSweden

Naturally produced hydroxylated polybrominated diphenyl ethers(OH-PBDEs)have been extensively studied in the lower end of the Baltic Sea food *** OH-PBDE congeners have displayed increasing concentrations over the last 30 years in herring(Clupea harengus)from the Baltic ***,studies on the top carnivores in the Baltic Sea are *** data on OH-PBDEs exist for ringed seal(Pusa hispida)from the Gulf of Bothnia,but only a limited amount of data have been produced with regard to Baltic grey seal(Halichoerus grypus),and seals from the Baltic proper.A method was developed and evaluated for quantification of OH-PBDEs in coagulated whole *** method was applied on blood obtained from dead grey seals originating from different parts of the Baltic *** levels of OH-PBDEs were observed to be low in the analyzed seals in comparison with reported levels in white-tailed sea eagle nestlings(Halizeetus albicilla),and some Baltic fish *** levels of the dominant congener,6-OH-BDE47,were statistically significantly higher in seals from the Baltic proper than in seals from the Gulf of *** polychlorinated biphenyls(OH-PCBs)were observed to be of much higher concentration than the OH-PBDEs in the analyzed *** average concentration of the dominant OH-PCB congener,4-OH-CB107,was one order of magnitude greater than that of 6-OH-BDE47.

关键词： Phenols OH-PBDEs Seal Blood Analysis Analytical methods

Release the iron: does the infection of magnetotactic bacteria by phages play a role in making iron available in aquatic environments?

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Journal of Oceanology and Limnology 2021年第6期39卷 2063-2069页

作者： Igor TAVEIRA dennis ABAZYLINSKI Fernanda ABREU Instituto de Microbiologia Paulo de Góes Departamento de Microbiologia GeralUniversidade Federal do Rio de JaneiroRio de Janeiro 21941-902Brazil School of Life Sciences University of Nevada at Las VegasLas Vegas 94720USA

Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the *** structures are ferrimagnetic organelles that impart a magnetic moment to the *** succeed in producing magnetosomes,MTB accumulate iron in(i)cytoplasm;(ⅱ)magnetosomes;and(ⅲ)nearby the *** has already been estimated that a single MTB has an iron content of 10 to 100-fold higher than Escherichia *** are the most abundant entity in oceans and are known for controlling nutrient flow such as carbon and nitrogen by viral shunt and *** current work addresses the putative role of phages that infect MTB on the iron biogeochemical *** phage infection in MTB hosts cause a biogenic iron fertilization-like event in localized microenvironments?Are phages critical players in driving magnetosome biomineralization genes(BGs)horizontal transfer?Further investigation of those events,including frequency of occurrence,is necessary to fully comprehend MTB’s effect on iron cycling in aqueous environments.

关键词： horizontal gene transfer iron biogeochemical cycle magnetotactic bacteria magnetosome biomineralization genes phages

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暗能量理论可能出了大问题

世界科学 2024年第5期 15-17页

作者：李威丹尼斯·奥弗比

科学家可能发现，他们认识暗能量这种神秘宇宙力量的理论存在重大缺陷。这对宇宙的命运倒可能是个好消息。一群天文学家正在开展迄今为止对宇宙历史最大规模、最精确的调查研究。他们在2024年4月对外宣布，可能发现了当前暗物质理论中...

科学家可能发现，他们认识暗能量这种神秘宇宙力量的理论存在重大缺陷。这对宇宙的命运倒可能是个好消息。一群天文学家正在开展迄今为止对宇宙历史最大规模、最精确的调查研究。他们在2024年4月对外宣布，可能发现了当前暗物质理论中的一个重大缺陷——暗能量是一种加速宇宙膨胀的神秘力量。按照之前的主流观点，无论是现在还是过去，暗能量都是宇宙中的一股不变的力量。然而，最新的数据表明，暗能量其实也在变化，会随着时间的推移变强或变弱，甚至会反转乃至消失。

关键词：

Ecohydrological processes and ecosystem services in the Anthropocene: a review

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Ecological Processes 2017年第1期6卷 364-372页

作者： Ge Sun dennis Hallema Heidi Asbjornsen Eastern Forest Environmental Threat Assessment Center Southern Research StationU.S.Department of Agriculture Forest Service920 Main Campus Dr.Suite 300RaleighNC 27606USA Oak Ridge Institute for Science and Education U.S.Department of EnergyOak RidgeTN 37830USA Institute for the Study of Earth Oceansand SpaceUniversity of New HampshireDurhamNHUSA

The framework for ecosystem services has been increasingly used in integrated watershed ecosystem management practices that involve scientists,engineers,managers,and policy *** objective of this review is to explore the intimate connections between ecohydrological processes and water-related ecosystem services in human-dominated ecosystems in the *** synthesize current literature to illustrate the importance of understanding the ecohydrological processes for accurately quantifying ecosystem services under different environmental and socioeconomic settings and *** synthesis focuses on managed ecosystems that are dominated by humans and explores how ecological processes affect the tradeoffs and synergies of multiple ecosystem *** identify research gaps in studying ecological processes mainly including energy,carbon,water,and nutrient balances to better assess and quantify ecosystem services that are critical for sustaining natural resources for future *** better assess ecosystem services,future ecohydrological studies need to better account for the scaling effects of natural and anthropogenic stressors exerted on evapotranspiration and other water supply and demand *** studies should focus on the bidirectional interactions between hydrological functions and services and human actions to solve real world problems such as water shortages,ecological degradation,and climate change adaptation.

关键词： watershed services ecosystem

Impacts of environmental factors on urban heating

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Journal of Environmental Sciences 2010年第12期22卷 1903-1909页

作者： Rizwan Ahmed Memon dennis Y.C.Leung Department of Mechanical Engineering Mehran University of Engineering & Technology Department of Mechanical Engineering The University of Hong Kong School of Energy and Environment City University of Hong Kong

This study investigated the impact of important environmental variables （i.e., wind speed, solar radiation and cloud cover） on urban heating. Meteorological parameters for fifteen years （from 1990 to 2005）, collected at a well developed and densely populated commercial area （Tsim Sha Tsui, Hong Kong）, were analyzed in details. Urban heat island intensity （UHII）, a well known indicator of urban heating, has been determined as the spatially averaged air-temperature difference between Tsim Sha Tsui and Ta Kwu Ling （a thinly populated rural area with lush vegetation）. Results showed that the UHII and cloud cover have increased by around 9.3% and 4%, respectively, whereas the wind speed and solar radiation have decreased by around 24% and 8.5%, respectively. The month of December experienced the highest UHII （10.2℃） but the lowest wind speed （2.6 m/sec） and cloud cover （3.8 oktas）. Conversely, the month of April observed the highest increases in the UHII （over 100%） and the highest decreases in wind speed （over 40 %） over fifteen years. Notably, the increases in the UHII and reductions in the wind speed were the highest during the night-time and early morning. Conversely, the intensity of solar radiation reduced while the intensity of urban cool island （UCII） increased during solar noon-time. Results demonstrated strong negative correlation between the UHII and wind speed （coefficient of determination, R^2 = 0.8） but no negative correlation between UCII and solar radiation attenuation. A possible negative correlation between UHII and cloud cover was investigated but could not be substantiated.

关键词： urban heat island urban cool island wind speed cloud cover

CFD simulation of bubbly turbulent Tayor–Couette flow

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Chinese Journal of Chemical Engineering 2016年第6期24卷 719-727页

作者： Xi Gao Bo Kong R.dennis Vigil Department of Chemical & Biological Engineering 2114 Sweeney Hall Iowa State University

Bubbly gas-liquid Taylor-Couette vortex flow has been the subject of several recent investigations both because of interest in bubble-induced drag reduction and because such devices have potential applications to a variety of chemical and biochemical processing problems. In order to quantitatively describe the hydrodynamics of highly turbulent two phase Taylor-Couette flow, a rigorous two-fluid computational fluid dynamics （CFD） model was developed and compared with previously published experimental data. This model includes a comprehensive description of the constitutive closure for inter-phase forces and turbulence was simulated using both the k- and k-to models. In addition, the mechanism by which the dispersed fluid attains a non-uniform radial and axial distribution is analyzed and the relative importance of various interphase forces is discussed. Lastly the model was validated by comparison of simulation predictions with experimental data, and it is shown that the CFD model correctly predicts phase velocity, velocity fluctuation, and gas distribution, and may provide guidance for reactor design and scale-up.

关键词： Taylor-Couette flowTwo-phase flowBubbleCFD