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The influence of various grease compositions and silver nanoparticle additives on electrically induced rolling-element bearing damage

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Friction 2024年第4期12卷 796-811页

作者： Samuel BOND Robert L.JACKSON german MILLS Department of Chemistry and Biochemistry Auburn UniversityAuburn 36849-5412USA Department of Mechanical Engineering Auburn UniversityAuburn 36849-5412USA

Leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films,but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to improve contact *** findings prompted a study that examined electrically induced surface pitting of steel contacts in the presence of several lubricating greases including some containing nanometer-sized colloidal silver(Ag)*** rolling sphere-on-disk experiments were conducted under electro-tribological loads employing polyurea greases derived from mineral and synthetic base oils with and without *** forces and electrical resistance were monitored continuously during the tests;surface changes were characterized by means of optical spectroscopy,stylus profilometry,and scanning electron microscopy(SEM)including compositional analysis using energy dispersive spectroscopy(EDS).The observations demonstrate that surface pitting induced by arcing occurs mainly at the points were the rolling motion changes direction and that eroded metal is deposited along the wear ***-sized pits are formed which contain carbon and oxygen indicating that arcing causes decomposition of the hydrocarbon *** findings indicate a significant inhibition of pitting is induced by the Ag nanoparticles;some greases containing other additives exhibit a similar,although less pronounced,effect.

关键词： electric motor bearings wheel bearings electric vehicles arcing electrically induced bearing damage pitting leakage current stray current

Leaf habit differentiation explains trait tradeoffs across savanna woody plants

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Forest Ecosystems 2024年第3期11卷 287-295页

作者： Yangsiding Wang Da Yang german Vargas G. Guangyou Hao Jennifer S.Powers Yan Ke Qin Wang Yunbing Zhang Jiaolin Zhang CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMenglaYunnan 666303China University of Chinese Academy of Sciences Beijing 100049China School of Biological Sciences University of UtahSalt Lake CityUT 84112USA CAS Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China Department of Ecology Evolution and BehaviorUniversity of MinnesotaSt PaulMN 55108USA

Identifying how leaf habit subdivisions link to the fast–slow and avoidance–tolerance trait tradeoffs can provide new insight into divergence in ecophysiological strategies among plant functional groups. Here, we tested a hypothesis that the differentiation across deciduous, semi-deciduous and evergreen woody species contributes to physiological trait tradeoffs in a dry-hot valley savanna. We investigated 11 photosynthetic, morphological and hydraulic traits of 24 species including 8 deciduous, 10 semi-deciduous and 6 evergreen species. Deciduous species were grouped in the fast and avoidance side associated with high values of maximum photosynthetic rates,stomatal conductance and leaf size, while evergreen species were grouped in the slow and tolerance side associated with high photosynthetic water use efficiency, leaf mass per area, sapwood density, Huber value, leaf water potential at turgor loss point and water potential causing 50% loss of stem hydraulic conductance. Semideciduous species generally had intermediate trait values and represented different physiological characteristics when compared to deciduous and evergreen species. The physiological trait tradeoffs showed a close linkage to the differentiation of these three leaf habits. Our findings clearly reveal trait tradeoffs related to fast–slow and avoidance–tolerance strategies among diverse savanna plants, suggesting a syndrome in multiple ecophysiology strategies across different leaf habits.

关键词： Dry-hot habitat Gas exchange Hydraulics Phenology Tolerance Valley savanna

HVOF-sprayed HAp/S53P4 BG composite coatings on an AZ31 alloy for potential applications in temporary implants

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Journal of Magnesium and Alloys 2024年第1期12卷 345-360页

作者： Carlos A.Poblano-Salas John Henao Astrid L.Giraldo-Betancur Paola Forero-Sossa Diego german Espinosa-Arbelaez Jorge A.González-Sánchez Luis R.Dzib-Pérez Susana T.Estrada-Moo Idelfonso E.Pech-Pech CIATEQ A.C. Av.Manantiales 23-AParque Industrial Bernardo QuintanaEl MarquésQuerétaro 76246Mexico CONAHCYT-CIATEQ A.C. Av.Manantiales 23-AParque Industrial Bernardo QuintanaEl MarquésQuerétaro 76246Mexico CONAHCYT-Cinvestav Libramiento Norponiente#2000.Fraccionamiento Real de JuriquillaQuerétaro 76230Mexico Universidad Tecnológica de Querétaro Av.Pie de la Cuesta N°2501Querétaro 76148Mexico CIDESI Av.Playa Pie de la Cuesta No 702Col.San PabloQuerétaro 76125Mexico Center for Corrosion Research Autonomous University of CampecheAv.Héroe de Nacozari No.480P.C.24070San Francisco de CampecheCam.Mexico

Bioactive thermal spray coatings produced via high-velocity oxygen fuel spray(HVOF)from hydroxyapatite(HAp)and bioactive glasses(BG)have the potential to be employed on temporary implants due to the ability of both HAp and BG to dissolve and promote osseointegration,considering that both phases have different reaction and dissolution rates under in-vitro *** the present work,75%***-25%wt.S53P4 bioactive glass powders were HVOF-sprayed to obtain HAp/S53P4 BG composite coatings on a bioresorbable AZ31 *** study is focused on exploring the effect of the stand-off distance and fuel/oxygen ratio variation as HVOF parameters to obtain stable structural coatings and to establish their effect on the phases and microstructure produced in those *** characterization techniques,such as scanning electron microscopy,X-ray diffraction,and Fourier transform infrared spectroscopy,were employed to characterize relevant structural and microstructural properties of the composite *** results showed that thermal gradients during coating deposition must be managed to avoid delamination due to the high temperature achieved(max 550℃)and the differences in coefficients of thermal *** was also found that both spraying distance and oxygen/fuel ratio allowed to keep the hydroxyapatite as the main phase in the *** addition,in-vitro electrochemical studies were performed on the obtained HAp/S53P4 BG composite coatings and compared against the uncoated AZ31 *** results showed a significant decrease in hydrogen evolution(at least 98%)when the bioactive coating was applied on the Mg alloy during evaluation in simulated body fluid(SBF).

关键词： Coatings Composites Thermal spray Temporary implants Hydrogen evolution

Notes on the family Brassicaceae in China

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Journal of Systematics and Evolution 2009年第3期47卷 202-219页

作者： Dmitry A german Altai State University

A critical revision of the collections of Brassicaceae in some Chinese (PE, XJA, XJBI, XJFA, XJNM, XJU) and foreign (LE, P) herbaria is made. One genus, Neurotropis (DC.) F. K. Mey., and 11 species, Alyssum szarabiacum Nyár., Barbarea stricta Andrz., Erysimum czernjajevii N. Busch, Erysimum kotuchovii D. german, Erysimum mongolicum D. german, Lepidium karelinianum Al-Shehbaz, Matthiola superba Conti, Neurotropis platycarpa (Fisch. & Mey.) F. K. Mey., Ptilotrichum dahuricum Peschkova, Sisymbrium subspinescens Bunge, and Smelowskia micrantha (Botsch. & Vved.) Al-Shehbaz & S. I. Warwick, are reported from China for the first time. Six species, Aphragmus involucratus (Bunge) O. E. Schulz, Dontostemon perennis C. A. Mey., Goldbachia torulosa DC., Lepidium amplexicaule Willd., Neotorularia brevipes (Kar. & Kir.) Hedge & J. Léonard, and Parrya stenocarpa Kar. & Kir., are confirmed to occurr in China. Five species, Dontostemon integrifolius (L.) C. A. Mey., Draba zangbeiensis L. L. Lou, Lepidium alashanicum H. L. Yang, Sinapis arvensis L., and Strigosella brevipes (Bunge) Botsch., are reported as novelties for some provinces in China, and Strigosella hispida (Litv.) Botsch. occurs in Xinjiang, China. However, the occurrence of one genus, Pseudoarabidopsis Al-Shehbaz, O’Kane & Price, and four species, Draba huetii Boiss., Eutrema halophilum (C. A. Mey.) Al-Shehbaz & S. I. Warwick, Galitzkya spathulata (Steph. ex Willd.) V. Bocz., and Pseudoarabidopsis toxophylla (Bieb.) Al-Shehbaz, O’Kane & Price, could not be confirmed in China. The occurrence of six species, Aphragmus bouffordii Al-Shehbaz, Barbarea orthoceras Ledeb., Lepidium latifolium L., Ptilotrichum canescens (DC.) C. A. Mey., Strigosella hispida (Litv.) Botsch., and Strigosella scorpioides (Bunge) Botsch., is not confirmed in certain provinces of China. All names follow the latest taxonomic treatment for relevant groups; detailed morphological descriptions of the newly recorded taxa are provided; and distinguishing c

关键词： Brassicaceae China Cruciferae distribution new record.

Confinement effects in methanol to olefins catalysed by zeolites： A computational review

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Frontiers of Chemical Science and Engineering 2016年第1期10卷 76-89页

作者： german Sastre Instituto de Tecnologia Quimica U.P.V.-C.S.I.C Universidad Politecnica de Valencia Avenida Los Naranjos s/n 46022 Valencia Spain

Small pore zeolites, containing 8-rings as the largest, are widely employed as catalysts in the process of methanol-to-olefins （MTO）. Reactants and products dif- fuse with constraints through 8-rings and this is one of the reaction bottlenecks related to zeolite micropore topology. Small pore zeolites and silicon-aluminophosphates （SAPOs） containing cavities, where olefins are mainly formed through the hydrocarbon pool （HP） mechanism, are frequently tested for MTO. Shape selectivity of transition states within the side-chain methylation will be reviewed as this is one of the controlling steps of the MTO process, with particular attention to the role of hexam- ethylbenzene （HMB） and heptamethylbenzenium cation （HeptaMB~）, which are the most tipically detected reaction intermediates, common to the paring and side-chain routes within the HP mechanism. The relative stability of these and other species will be reviewed in terms of confinement effects in different cage-based zeolites. The role of the different alkylating agents, methanol, dimethyl ether （DME）, and surface methoxy species （SMS） will also be reviewed from the computational viewpoint.

关键词： small pore zeolites SAPOs methanol-to-olefins hydrocarbon pool mechanism alkylation of poly-methylbenzenes

A transition from a large open pit into a novel “macroblock variant” block caving geometry at Chuquicamata mine, Codelco Chile

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 549-561页

作者： german Flores Alex Catalan Newcrest Mining Ltd. Melbourne3004Australia Codelco Chile Santiago8320000Chile

With a history of more than 100 years, Chuquicamata has become one of the largest open pits in the world. Its current depth of 1100 m, length of 4500 m and width of 3000 m, resulting in haulage distances of over 11,000 m from pit bottom to the processing plant or waste dumps, with waste/ore ratio greater than 4 and much lower grades, are effectively determining its profitable limit by the end of this decade. Currently, there are over 4300 Mt of geological resources containing 0.7% of copper and 340 ppm (1 ppm = 1 g/t) of molybdenum below the final pit shell. The corresponding orebody geometry is 3000 m northsouth, 300-800 m eastwest and the drilling campaign suggested the existence of more than 900 m of mineable ore from the final pit bottom. This is in spite of the fact that the Chuquicamata orebody is still open at depth. The business case to continue with the mining of the Chuquicamata orebody is to change from the current large open pit to a novel macroblock variant block caving geometry. This requires a production rate of 140,000 t/d (50 Mt per annum), with a continuous material handling system to achieve the 7-year ramp-up to full production. The resolution of a number of known technical, operational and logistical challenges outside current industry practises which Chuquicamata will face over its projected 40-year mine life is therefore essential. These challenges include simultaneous operations of open pit and underground macroblocks and from the initial lift to the second lift, rapid ramp-up and optimum sequencing of the planned macroblocks, early dilution from the west fault and late dilution from potential slope failures, and the potential for major operational hazards. An equally important issue to be addressed is cultural given that the mining history in the northern region of Chile, which includes Chuquicamata, is predominantly open pit. This paper presents a synopsis of the main challenges that the Chuquicamata underground project will face in order t

关键词： Macroblock variant Block caving Cave propagation Early and late dilutions Intensive preconditioning Rib pillar West fault Ore buffer

Method and portable facility for measurement of trace element concentration in prostate fluid samples using radionuclideinduced energy-dispersive X-ray fluorescent analysis

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Nuclear Science and Techniques 2016年第6期27卷 93-100页

作者： Vladimir Zaichick Sofia Zaichick german Davydov Radionuclide Diagnostics Department Medical Radiological Research Centre Department of Medicine College of Medicine at ChicagoUniversity of Illinois

A facility and method for109 Cd radionuclide-induced energy-dispersive X-ray fluorescent(EDXRF) were developed to determine the Fe,Zn,Br,Rb,and Sr concentrations in the specimens of human prostatic *** of expressed prostatic fluid were obtained from 51 men(mean age 51 years,range 18–82 years) with apparently normal prostates using standard rectal massage *** values(M ± SEL) for concentration of trace elements(mg L^(-1)) in human prostate fluid were:Fe 9.04 ±1.21,Zn 573 ± 35,Br 3.58 ± 0.59,Rb 1.10 ± 0.08,and Sr B *** was shown that the results of trace element analysis in the micro-samples(20 l L) are sufficiently representative for assessment of the Fe,Zn,Br,and Rb concentration in the prostate *** facility for109 Cd radionuclide-induced EDXRF is comparatively compact and can be located in close proximity to the site of carrying out the massage *** means of Zn and Rb concentration obtained for prostate fluid agree well with median of reported *** the first time,the Fe and Br concentrations,as well as the upper limit of the Sr concentration,were determined in the human prostate fluid.

关键词：能量色散X射线荧光分析放射性核素元素浓度便携式设备前列腺测定样品诱导

Generating native user interfaces for multiple devices by means of model transformation

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Frontiers of Information Technology & Electronic Engineering 2015年第12期16卷 995-1017页

作者： Ignacio MARIN Francisco ORTIN german PEDROSA Javier RODRIGUEZ Department of Research and Development CTIC Foundation Department of Computer Science University of Oviedo

In the last years, the types of devices used to access information systems have notably increased using different operating systems, screen sizes, interaction mechanisms, and software features. This device fragmentation is an important issue to tackle when developing native mobile service front-end applications. To address this issue,we propose the generation of native user interfaces(UIs) by means of model transformations, following the modelbased user interface(MBUI) paradigm. The resulting MBUI framework, called LIZARD, generates applications for multiple target platforms. LIZARD allows the definition of applications at a high level of abstraction, and applies model transformations to generate the target native UI considering the specific features of target platforms. The generated applications follow the UI design guidelines and the architectural and design patterns specified by the corresponding operating system manufacturer. The objective is not to generate generic applications following the lowest-common-denominator approach, but to follow the particular guidelines specified for each target device. We present an example application modeled in LIZARD, generating different UIs for Windows Phone and two types of Android devices(smartphones and tablets).

关键词： Model-to-model transformation Native user interfaces Model-based user interfaces Model-driven engineering

Bean yellow disorder virus： Parameters of transmission by Bemisia tabaci and host plant range

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Insect Science 2011年第1期18卷 50-56页

作者： german Martin Isabel Maria Cuadrado Dirk Janssen Instituto Andaluz de Investigacion y Formacion Agraria y Pesquera Centro La Mojonera Almeria Spain

Bean yellow disorder virus （BnYDV） was recently identified as the first crinivirus （family Closteroviridae） that infects members of the family Leguminosae. It was first observed during the autumn of 2003, causing heavy losses in French bean （Phaseolus vulgaris L.） grown commercially in Spain. The virus is transmitted by the sweetpotato whitefly, Bemisia tabaci （Hemiptera： Aleyrodidae） Q-biotype, and disease symptoms resemble nutritional disorders consisting of interveinal mottling and yellowing in leaves, combined with stiffness or brittleness, and are typically produced on the middle to lower parts of the plant. Transmission experiments showed that 50% and 100% of B. tabaci adults acquired the virus after a feeding period of 3 and 7 h, respectively. Viruliferous whiteflies infected 66% and 100% ofP. vulgaris plants after a feeding period of 12 and 24 h, respectively. The transmission efficiency of single whiteflies was 37% and persistence of BnYDV in the vector lasted up to 2 weeks with a half-life of 9 days. BnYDV was transmitted to P. vulgaris, Pisum sativum L., Lens culinaris Medik., and Vicia faba L., but not to Vigna unguiculata L., Glycine max （L.） Merr., Cicer arietum L., and to crop species belonging to families of the Solanaceae and Cucurbitaceae. No virus was detected in field samples collected from 30 different species from Boraginaceae, Asteraceae, Geraniaceae, Lamiaceae, Leguminosae, Malvaceae, Scrophulariaceae, Thymelaeaceae and Verbenaceae. The restricted host range and efficient management of crops regarding whitefly infestation may be key elements in the control of BnYDV.

关键词： bean Closteroviridae Crinivirus disease vector whiteflies