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Urban-induced changes in tree leaf litter accelerate decomposition

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Ecological Processes 2015年第1期4卷 1-16页

作者： jens Dorendorf Anja Wilken Annette Eschenbach Kai jensen Applied Plant Ecology Biocenter Klein FlottbekUniversität HamburgOhnhorstraße 1822609 HamburgGermany Institute for Soil Science CENUniversität HamburgAllende-Platz 220146 HamburgGermany.

Introduction:The role of urban areas in the global carbon cycle has so far not been studied ***,urbanization might affect decomposition within urban *** far,only few studies have examined the effects of the level of urbanization on *** study addresses the influence of the level of urbanization on decomposition *** explores whether potential influences are exerted through leaf litter quality alterations or through direct effects of decomposition site’s level of *** litter of five different tree species was sampled at urban and periurban *** of this litter was analyzed in three different experiments:a climate chamber incubation,a reciprocal litterbag transplant at urban and periurban sites,and a common garden litterbag ***:Decomposition site’s level of urbanization did not show a significant ***,in all species,when significant differences were observed,leaf litter of urban origin decomposed significantly faster than leaf litter of periurban *** effect was observed in all three *** the reciprocal litter transplant experiment,62%±3%mass loss in litter of urban origin compared to 53%±3%in litter of periurban origin was *** difference was not as pronounced in the other two experiments,with 94%±1%mass loss of litter originating in urban habitats compared to 92%±1%mass loss of litter originating in periurban habitats in the common garden experiment and 225±13 mg CO2 released from litter originating in urban habitats compared to 200±13 mg CO2 released from litter originating in periurban habitats in the climate chamber ***:We conclude that the level of urbanization affects decomposition indirectly through alterations in leaf litter quality even over short urban to periurban distances.

关键词： Litterbags Urban gradients Carbon cycling Mass loss Respiration Urban ecology Urban forests Paired studies Suburban Urban–rural contrast

Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts

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Science Bulletin 2018年第1期63卷 24-30页

作者： Lijie Zhong jens Oluf jensen Lars Nilausen Cleemann Chao Pan Qingfeng Li Department of Energy Conversion and Storage Technical University of Denmark

The graphitic-layer encapsulated iron-containing nanoparticles(G@Fe) have been proposed as a potential type of active and stable non-precious metal electrocatalysts(NPMCs) for the oxygen reduction reaction(ORR). However, the contribution of the encapsulated components to the ORR activity is still unclear compared with the well-recognized surface coordinated FeN_x/C structure. Using the strong complexing effect of the iron component with anions, cyanide(CN^-) in alkaline and thiocyanate(SCN^-) in acidic media, the metal containing active sites are electrochemically probed. Three representative catalysts are chosen for a comparison including the as-prepared encapsulated G@Fe, commercial Fe/N/C catalyst with iron–nitrogen coordinated surface functionalities and molecular iron phthalocyanine(Fe Pc) containing well-defined structures and compositions. It was found that all samples showed significant shifts of half-wave potentials indicating that surface Fe coordinated sites in all cases. The G@Fe catalyst showed the weakest poisoning effect(the lowest shifts of half-wave potential) compared to the Fe/N/C and Fe Pc catalysts in both electrolytes. These results could be explained that the encapsulated iron components influence the FeN_x/C and/or N_xC surface functionality.

关键词： Encapsulated Fe catalysts Oxygen reduction reaction Ion poisoning Active sites NPMCs

Tribological properties of transition metal di-chalcogenide based lubricant coatings

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Frontiers of Materials Science 2012年第2期6卷 116-127页

作者： Jun-Feng YANG Braham PARAKASH jens HARDELL Qian-Feng FANG Department of Applied Physics and Mechanical Engineering Lulea University of TechnologySE-97187 LuleaSweden Key Laboratory of Materials Physics Institute of Solid State PhysicsChinese Academy of SciencesHefei 230031China

Transition metal di-chalcogenides MX2 （X= S, Se, Te; and M = W, Mo, Nb, Ta） are one kind of solid lubricant materials that have been widely used in industry. The lubricant properties of such lubricant coatings are dependent not only on microstructure, orientation, morphology, and composition of the coatings, but also on the substrate, the interface between substrate and lubricant coatings, and the specific application environment. In this review, the effects of parameters on tribological properties of such kind of lubricant coatings were summarized. By comparing advantages and disadvantages of those coatings, the special treatments such as doping, structural modulation and post-treatment were suggested, aiming to improve the tribologicai performance under severe test conditions （e.g. high temperature, oxidizing atmosphere or humid condition）.

关键词： transition metal di-chalcogenide solid lubricant coating tribologicalproperty

New class of two-dimensional bimetallic nanoplatelets for high energy density and electrochemically stable hybrid supercapacitors

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Nano Research 2017年第9期10卷 3018-3034页

作者： Zhiting Liu Peng Ma jens Ulstrup Qijin Chi Kake Zhu Xinggui Zhou UNILAB State Key Lab of Chemical Engineering School of Chemical Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 China Department of Chemistry Technical University of Denmark Kongens Lyngby DK-2800 Denmark

Currently, the application of supercapacitors (SCs) in portable electronic devices and vehicles is limited by their low energy density. Developing high-energy density SCs without sacrificing their advantages, such as their long-term stability and high power density, has thus become an increasing demand but a major challenge. This demand has motivated tremendous efforts, especially towards discovering and optimizing the architecture of novel electrode materials. To this end, we herein report the design, synthesis, and SC application of a new family of two-dimensional (2D) nanoplatelets, i.e., a transition-metal hydroxymethylate complex (Ni x Co1–x (OH)(OCH3)). Bimetallic nanoplatelets were synthesized via a cost-effective approach involving a one-step solvothermal procedure. We for the first time tuned the metal composition of these 2D nanoplatelets over the entire molar-fraction range (0–1.0). Tuning the molar ratio of Ni/Co allowed us to optimize the structures and physicochemical properties of the nanoplatelets for SC applications. When tested in a half cell, SC electrodes using the nanoplatelets exhibited high electrochemical performance with a specific capacitance as high as 1,415 F·g–1 and a 96.1% retention of the initial capacitance over 5,000 cycles. We exploited the novel 2D nanoplatelets as cathode materials to assemble a hybrid SC for full-cell tests. The resulting SCs operated in a wide potential window of 0–1.7 V, exhibited a high energy density over 50 Wh·kg–1, and sustained their performance over 10,000 charge–discharge cycles. The results suggest that the novel 2D nanoplatelets are promising alternative materials for the development of high-energy density SCs.

关键词： transition-metal hydroxymethylate complex two-dimensional (2D) nanoplatelet supercapacitor electrochemical energy storage tuning bimetallic composition

Like or dislike:Response of rodents to the odor of plant secondary metabolites

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Integrative Zoology 2017年第5期12卷 428-436页

作者： Sabine C.HANSEN Caroline STOLTER Christian IMHOLT jens JACOB Julius-Kühn Institute for Plant Protection in Horticulture and Forests Vertebrate ResearchMünsterGermany University Hamburg Biocenter Grindel and Zoological MuseumHamburgGermany

Rodents,including common voles(Microtus arvalis)and house mice(Mus musculus)cause immense pre-harvest and post-harvest ***,developing methods that mitigate these losses while maintaining their role in ecosystems is a *** plant secondary metabolites(PSM)which significantly reduce food intake of both species under laboratory conditions have been ***,before these can be used in rodent pest management,they must be tested under more natural conditions where other food sources are *** this study,the odors of 4 PSMs were evaluated for their repellent effects in experiments conducted in semi-natural *** treated with PSMs or untreated soil(experimental control)was placed in an underground box containing food(rolled oats).We quantified the number of visits to each box and could demonstrate that all 4 PSMs reduced the number of visits to treatment boxes in both rodent *** common voles the combination of methyl nonyl ketone+black pepper oil was the most repellent *** mice made fewer visits to all PSM boxes;boxes with the anthraquinone were visited ***,house mice consumed less food from boxes containing soil treated with all 4 *** results suggest that PSMs are repellent in murid and microtine rodents under semi-field *** addition,the future use of PSM odors for repelling both pest species,especially house mice,seems *** investigations with other PSMs,different concentrations as well as alternative application methods are needed to repel common voles from attractive crops.

关键词： enclosure trials odor plant secondary metabolites repellents rodents

Degradation of the fungicide metalaxyl and its non-extractable residue formation in soil clay and silt fractions

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Pedosphere 2021年第4期31卷 549-559页

作者： Roschni KALATHOOR jens BOTTERWECK Andreas SCHÄFFER Burkhard SCHMIDT Jan SCHWARZBAUER Institute of Geology and Geochemistry of Petroleum and Coal RWTH Aachen UniversityAachen 52062(Germany) Institute for Environmental Research RWTH Aachen UniversityAachen 52062(Germany) School of the Environment Nanjing UniversityNanjing 210023(China)

The proportion of organic matter and mineral composition are important factors determining the formation and type of non-extractable residues(NERs) of pesticides in soil. In this study, we investigated the enantioselectivity in degradation and NER formation of the chiral fungicide metalaxyl in soil particle size fractions(silt and clay). Microbial and extracellular enzyme activities during these processes were monitored in incubation of silt and clay samples isolated from sterilized and non-sterilized soil samples collected from a long-term agricultural field experimental site in Ultuna, Sweden. The temporal influence on the fate of the fungicide was noted by short-term(10-d) and long-term(92-d) incubations. Besides the acquisition of quantitative data with gas chromatography-mass spectrometry(GC/MS), stereoselective analyses were performed with chiral GC/MS. Quantitative results pointed to a higher metabolism rate of the pesticide through microbial activity than through extracellular enzyme activity. This was also confirmed by the enantioselective depletion of R-metalaxyl and the subsequent formation of R-metalaxyl acid in microbially active samples from non-sterilized soil. The silt fraction containing a high amount of organic matter exhibited a significant hydrolyzable proportion of metalaxyl NERs that was releasable under alkaline conditions. On the contrary, the clay fraction showed an enhanced affinity for covalently bound residues. Based on our results, we recommend differentiating between reversibly and irreversibly bound proportions of pesticides in persistence and environmental risk assessment because the reversible fraction contained potentially bioavailable amounts of residues that may be released under natural conditions.

关键词： chiral fungicide enantioselectivity metalaxyl enantiomer non-extractable pesticide residues organo-mineral complex pesticide degradation extracellular enzymes soil particle size fractions

Tribological performance of iron- and nickel-base self-lubricating claddings containing metal sulfides at high temperature

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Friction 2022年第12期10卷 2069-2085页

作者： Hector TORRES Tugce CAYKARA jens HARDELL Janne NURMINEN Braham PRAKASH Manel RODRIGUEZ RIPOLL AC2T research GmbH Viktor-Kaplan-Straße 2/CWiener Neustadt 2700Austria Department of Applied Physics and Mechanical Engineering LuleåUniversity of TechnologyLuleå97187Sweden Castolin Eutectic GmbH Gutenbergstraße 10Kriftel 65830Germany Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

Iron-based coatings with the incorporation of solid lubricants have been prepared by means of laser cladding,in an effort to control friction and decrease tool wear at high temperatures during metal forming *** choice of a Fe-based powder has been considered advantageous,as it can lead to decreased costs compared to nickel-based claddings previously studied by the authors,in addition to having a lower environmental *** particular,the incorporation of transition metal dichalcogenides such as MoS_(2) as precursors leads to the encapsulation of silver in Fe-based self-lubricating claddings,resulting in a uniform distribution of the soft metal across the thickness of the *** tribological evaluation of the claddings at high temperatures shows that the addition of lubricious compounds leads to lower friction at room temperature and significantly decreased wear up to 600℃ compared to the unmodified iron-based reference alloy,although higher than similar self-lubricating Ni-based *** order to cast light into these observed differences,the corresponding microstructures,phase composition,and self-lubricating mechanisms have been studied and compared for Fe-and Ni-based claddings having both of them the addition of silver and MoS_(2).The results suggest a key role of the formation of protective tribolayers on the counter body during high temperature sliding *** simulation of the phase evolution during solidification reveals that the formation of different chromium-and nickel-based metal sulfides in Fe-and Ni-claddings during laser cladding by the decomposition of MoS_(2) plays a key role in determining their tribological behaviour at high temperatures.

关键词： high temperature laser cladding self-lubrication metal forming chromium sulphide MoS_(2)

Noise emission of concrete pavement surfaces produced by diamond grinding

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Journal of Traffic and Transportation Engineering(English Edition) 2015年第2期2卷 81-92页

作者： jens Skarabis Ulrike Stckert Center for Building Materials Technical University of Munich Federal Highway Research Institute (BASt)

In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been sys- tematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise- reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.

关键词： Concrete pavement Noise emission Diamond grinding Surface texture

Incidental findings at MRI-enterography in patients with suspected or known Crohn's disease

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World Journal of Gastroenterology 2010年第1期16卷 76-82页

作者： Michael Dam jensen Torben Nathan jens Kjeldsen Sφren Rafael Rafaelsen Department of Internal Medicine Section of GastroenterologyVejle Hospital part of Lillebaelt Hospital Department of Medical Gastroenterology Odense University Hospital Department of Radiology Vejle Hospital part of Lillebaelt Hospital

AIM:To determine the frequency and clinical impact of incidental findings detected with magnetic resonance imaging(MRI)-enterography in patients with suspected or known Crohn's disease(CD). METHODS:Incidental findings were defined as unexpected lesions outside the small intestine,not previously known or suspected at the time of referral, and not related to inflammatory bowel *** a systematic review of medical charts we analyzed the clinical impact of incidental findings,and compared the MRI findings with subsequent diagnostic procedures. RESULTS:A total of 283 patients were included in the analysis,and MRI detected active CD in 31%,fistula in 1.4%and abscess in 0.7%.Extra-intestinal findings notrelated to CD were recorded in 72 patients(25%),of which 58 patients(20%)had 74 previously unknown *** or incompletely characterized findings were detected in 17 patients(6.0%).Incidental findings led to 12 further interventions in 9 patients(3.2%) revealing previously unknown pathological conditions in 5(1.8%).One patient(0.4%)underwent surgery and one patient was diagnosed with a malignant disease. MRI detected incidental colonic lesions in 16 patients of which additional work-up in 4 revealed normal anatomy. Two patients(0.7%)benefitted from the additional examinations,whereas incidental findings led to unnecessary examinations in 9(3.2%). CONCLUSION:In a minority of patients with suspected or known CD,important incidental findings are diagnosed at ***,a substantial number of patients experience unnecessary morbidity because of additional examinations of benign or normal conditions.

关键词： Magnetic resonance imaging Incidental findings Crohn’s disease Small intestine