检索结果-南通市图书馆

Improved Low-Temperature Aqueous Synthesis of ZnO Nanorods and Their Use in SERS Detection of 4-ABT and RDX

在线全文

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2013年第1期4卷 29-38页

作者： Marcia del R.Balaguera-Gelves Oscar J.Perales-Pérez Surinder P.Singh josé a.jiménez Joaquín A.Aparicio-Bolanos Samuel P.Hernández-Rivera Department of Chemistry University of Puerto Rico-MayaguezMayagüezPuerto Rico Department of Engineering Science and Materials University of Puerto Rico-MayaguezMayagüezPuerto Rico Department of Chemistry University of North FloridaJacksonvilleUSA Department of Chemistry and Physics University of Puerto Rico-PoncePoncePuerto Rico

The growth-controlled synthesis of zinc oxide nanorods (ZnO NR) in the aqueous phase has been investigated. The rods were grown on ZnO films previously deposited onto Si(100) and indium tin oxide (ITO) substrates by RF magnetron sputtering. The formation of the rods took place in the presence of hexamethylenetetramine (HMT) as habit-control reagent. The grains in the base ZnO film acted as seeds that promoted the longitudinal growth of the oxide. As-synthesized base films and rods were characterized by X-ray diffraction, scanning electron microscopy (SEM), field emission SEM, optical absorption and photoluminescence spectroscopy techniques. Subsequently, a wet chemistry procedure was performed to achieve ZnO NR growth. This methodology was conducive to the formation of rods of a relatively narrow distribution of diameters (60 - 70 nm) with lengths in the 1 - 3 μm range. Photoluminescence spectra were characterized by a dominant near-band-edge (NBE) peak followed by a green luminescence (GL) broad band, indicative of higher oxygen vacancy concentration in the ZnO NR grown on ZnO/ITO in comparison with those grown on ZnO/Si(100). A UV process was used for coating the ZnO NR with gold (Au). Au coating on ZnO NR was used to evaluate the detection capability by SERS of different analytes such as: 4-aminobenzenethiol (4-ABT) and 1,3,5-trinitroperhydro-1,3,5- triazine (RDX) at low levels. A strong SERS Raman spectrum was observed for 4-ABT. A limit of detection (LOD) of 1 × 10-8M for 4-ABT was achieved corresponding to a minimum of 5.4 × 105molecules detected under the experimental conditions at excitation wavelength of 785 nm with a sensitivity of the ZnO NR in the range of 1.1 × 10-16g under the laser spot.

关键词： ZnO Nanorods Sputtering SERS 4-ABT RDX

Mitochondria–cGAS–STING axis is a potential therapeutic target for senescence-dependent inflammaging-associated neurodegeneration

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第3期20卷 805-807页

作者： joséM.Izquierdo Centro de Biología Molecular Severo Ochoa(CBM) Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid(CSIC-UAM)MadridSpain

The word “senescence” comes from the Latin senescens, meaning “to begin to age”, and is characterized by a long-lasting but reversible block in proliferation, resulting from stress-induced cell cycle arrest of pre... 详细信息

关键词： Latin potential lasting

Effect of rhenium on the microstructure and mechanical behavior of Fe–2.25Cr–1.6W–0.25V-0.1C bainitic steels

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第12期33卷 1487-1493页

作者： josé Antonio jiménez Manuel Carsí Oscar Antonio Ruano Department of Physical Metallurgy Centro Nacional de lnvestigaciones MetalurgicasC.S.I.CAvda.Gregorio del Amo 828040 MadridSpain

A new ferritic creep resistant steel has been developed by eliminating Nb and adding 1.5 mass % Re to a ferritic steel grade T/P23 with the aim of enhancing its mechanical properties at high *** ingots of both steels, new grade and ASTM T/P 23, were hot rolled at 900℃ and then submitted to a thermal treatment consisting of solubilization at 1050℃ and tempering at 700℃. Tempered bainitic microstructures obtained contain second phases reinforcing carbide particles, mainly M_6C and M_（23）C_6 at the boundaries of both, prior austenite grains and bainitic ferrite laths, as well as MC within the grains. Mechanical properties at temperatures ranging from 540 to 600℃ were studied by strain-ratechange tests in compression at strain rates between 10^（-7） and 10^（-4）s^（-1）. These tests showed high stress exponents（n ≥ 20） and activation energies（Q ≈ 400 k J/mol） for both alloys, which were associated with a dislocation movement mechanism with a strong interaction between dislocations and precipitates. On the other hand, a creep exponent of 5 was derived for the stress dependence of minimum creep rate from conventional-type creep tests at 600℃. Although this stress exponent is usually related to a dislocation climb controlled creep mechanism, remarkable microstructural degradation observed with increasing creep time makes difficult to elucidate the true deformation mechanism controlling creep.

关键词： Creep resistant steel T/P23 Thermal treatment Tempered bainite High temperature mechanical properties Creep

Processing of Aerosol Particles in Convective Cumulus Clouds:Cases Study in the Mexican East Pacific

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2010年第6期27卷 1331-1343页

作者： josé C.jimnez-ESCALONA Oscar PERALTA ESIME UP Ticomán National Polytechnic Institute Chemistry Faculty National Autonomous University of MexicoCiudad Universitaria

In the Mexican Intertropical Convergence Zone, particle size distributions within 500 m of cloud boundaries at altitudes of 1000, 2500, and 4200 m, were compared against size distributions at the same levels but 1500 m away from the clouds. The differences in the distributions near and far from the cloud are related to processes that may change particle properties inside the cloud. Chemical changes in the aerosols are deduced from the particles＇ refractive index, as derived from comparisons with the scattering coeflcient measured by a nephelometer. An analysis of ten cloud systems indicates that vertical transport of cloud base aerosol followed by entrainment/detrainment is the cloud processing signature most frequently observed in the comparisons （65%）. Changes in the chemical composition are observed in approximately 20% of the cases and another 20% of the cases showed removal by precipitation. About 5% of the comparisons showed clear evidence of changes by coalescence. The principal effect of these cloud-processed aerosols is observed in the increase of optical depth in the layer from 30 m to 4200 m in the near-cloud regions, in comparison with the atmosphere further from clouds.

关键词： cloud processing cloud interaction scattering redistribution entrainment

Sintering study of Ti6Al4V powders with different particle sizes and their mechanical properties

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2018年第12期25卷 1389-1401页

作者： joséLuis Cabezas-Villa joséLemus-Ruiz Didier Bouvard Omar jiménez Héctor Javier Vergara-Hernández Luis Olmos University Michoacana of San Nicolás of Hidalgo IIMMMorelia 58060México University Grenoble Alpes CNRSSIMaPGrenoble 38000France University of Guadalajara Departamento de Ingeniería de ProyectosZapopan 45100México National Technological Institute of Mexico I.T.MoreliaMorelia 58120México University Michoacana of San Nicolás of Hidalgo INICITMorelia 58060México

Ti6Al4V powders with three different particle size distributions(0–20, 20–45, and 45–75 μm) were used to evaluate the effect of the particle size distribution on the solid-state sintering and their mechanical properties. The sintering kinetics was determined by dilatometry at temperatures from 900 to 1260°C. The mechanical properties of the sintered samples were evaluated by microhardness and compression tests. The sintering kinetics indicated that the predominant mechanism depends on the relative density irrespective of the particle size used. The mechanical properties of the sintered samples are adversely affected by increasing pore volume fraction. The elastic Young's modulus and yield stress follow a power law function of the relative density. The fracture behavior after compression is linked to the neck size developed during sintering, exhibiting two different mechanisms of failure: interparticle neck breaking and intergranular cracking in samples with relative densities below and above of 90%, respectively. The main conclusion is that relative density is responsible for the kinetics, mechanical properties, and failure behavior of Ti6 Al4 V powders.

关键词： Ti6Al4V powders dilatometry microhardness sintering kinetics compression failure behavior

Digital thermal monitoring of the Amazon forest:an intercomparison of satellite and reanalysis products

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2016年第5期9卷 477-498页

作者： Juan C.jiménez-Muñoz Cristian Mattar josé A.Sobrino Yadvinder Malhi Global Change Unit Image Processing LaboratoryUniversity of ValenciaPaternaSpain Laboratory for Analysis of the Biosphere Department of Environmental Sciences and Renewable Natural ResourcesUniversity of ChileLa PintanaChile School of Geography and Environment Environmental Change InstituteUniversity of OxfordOxfordUK

Remote sensing and climate digital products have become increasingly available in recent *** to these products has favored a variety of Digital Earth studies,such as the analysis of the impact of global warming over different *** study of the Amazon forest response to drought has recently received particular attention from the scientific community due to the occurrence of extreme droughts and anomalous warming over the last *** paper focuses on the differences observed between surface thermal anomalies obtained from remote sensing moderate resolution imaging spectroradiometer(MODIS)and climatic(ERA-Interim)monthly products over the Amazon *** a few exceptions,results show that the spatial pattern of standardized anomalies is similar for both *** terms of absolute anomalies,the differences between the two products show a bias near to zero with a standard deviation of around 0.2 K,although the differences can be up to 1 K over particular regions and *** this general agreement,the proper filtering of MODIS daily values in order to construct a new monthly product showed a dramatic reduction in the number of reliable pixels during the rainy season,while for the dry season this reduction is only seen in Northern Amazonia.

关键词： Thermal anomalies Amazon forest MODIS ERA interim thermal Amazonia

Multi-temporal NDVI analysis using UAV images of tree crowns in a northern Mexican pine-oak forest

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Forestry Research 2023年第6期34卷 1855-1867页

作者： joséLuis Gallardo-Salazar Marcela Rosas-Chavoya Marín Pompa-García Pablito Marcelo López-Serrano Emily García-Montiel Arnulfo Meléndez-Soto Sergio Iván jiménez-jiménez Instituto de Investigaciones Agropecuarias y Forestales Universidad Michoacana de San Nicolás de Hidalgo(UMSNH)58330 MoreliaMichoacánMexico Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales Universidad Juárez del Estado de DurangoRío Papaloapan y Blvd.DurangoValle del Sur s/n34120 DurangoDurangoMéxico Facultad de Ciencias Forestales Universidad Juárez del Estado de DurangoRío Papaloapan y Blvd.DurangoValle del Sur s/n34120 DurangoDurangoMéxico Instituto de Silvicultura e Industria de la Madera Universidad Juárez del Estado de DurangoBoulevard del Guadiana 501Ciudad UniversitariaTorre de Investigación34120 DurangoMéxico INIFAP-CENID RASPA Centro Nacional de Investigación Disciplinaria en Relación Agua-Suelo-Planta-Atmósfera Margen derecha canal Sacramento km 6.5Zona industrial35140 Gómez PalacioDurangoMexico

The use of unmanned aerial vehicles(UAV)for forest monitoring has grown significantly in recent years,providing information with high spatial resolution and temporal *** with multispectral sensors allow the use of indexes such as the normalized difference vegetation index(NDVI),which determines the vigor,physiological stress and photo synthetic activity of *** study aimed to analyze the spectral responses and variations of NDVI in tree crowns,as well as their correlation with climatic factors over the course of one *** study area encompassed a 1.6-ha site in Durango,Mexico,where Pinus cembroides,Pinus engelmannii,and Quercus grisea *** images were acquired with UAV and information on meteorological variables was obtained from NASA/POWER *** ANOVA explored possible differences in NDVI among the three *** correlation was performed to identify the linear relationship between NDVI and meteorological *** differences in NDVI values were found at the genus level(Pinus and Quercus),possibly related to the physiological features of the species and their *** grisea had the lowest NDVI values throughout the year which may be attributed to its sensitivity to relative humidity and *** the use of UAV with a multispectral sensor for NDVI monitoring allowed genera differentiation,in more complex forest analyses hyperspectral and LiDAR sensors should be integrated,as well other vegetation indexes be considered.

关键词： Multispectral images Normalized diff erence Vegetation index Phenology Unmanned aerial vehicles Multitemporal analysis

Evaluation of Terra/MODIS atmospheric profiles product(MOD07)over the Iberian Peninsula:a comparison with radiosonde stations

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2015年第10期8卷 771-783页

作者： joséA.Sobrino Juan C.jiménez-Muñoz Cristian Mattar Guillem Sòria Global Change Unit–Image Processing Laboratory University of ValenciaValenciaSpain Laboratory for Analysis of the Biosphere Universidad de ChileSantiagoChile

Remote sensing techniques are a useful tool for continuous observation of the Earth at global ***,products derived from remote sensing data require a rigorous validation using in situ *** Resolution Imaging Spectroradiometer(MODIS)is not really a sounding instrument,but it does have 16 infrared bands(bands 20-36 covering the spectral range from 3μm to 14μm)that allow the retrieval of temperature and moisture profiles as well as total column integrated *** this paper we show the results obtained in the evaluation of MOD07 daytime and nighttime products over the Iberian Peninsula during the decade from 2000 to 2010 using nine radiosonde *** MODIS limitations in comparison with other sounding instruments,the validation provided satisfactory results,with bias(MOD07 minus radiosonde)<0.3 cm and a standard deviation of 0.5 cm for the total column water vapor,and bias around 1 K on average with standard deviations between 2 K and 3 K for air temperature at different pressure *** average,bias was positive and below 2 K with standard deviations around 5 K for the dew point temperature *** errors were found in this case for pressure levels higher than 50 hPa.

关键词： MODIS MOD07 atmospheric profiles water vapor air temperature dew point temperature

Visual function,performance,and processing of basketball players *** individuals

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Sport and Health Science 2020年第6期9卷 587-594页

作者： Jesús Vera Raimundo jiménez David Cárdenas Beatriz Redondo josé Antonio García Department of Optics Faculty of ScienceUniversity of GranadaGranada 18071Spain Department of Physical Education and Sport Faculty of Sport ScienceUniversity of GranadaGranada 18071Spain Sport and Health University Mixed Institute University of GranadaGranada 18071Spain

Background:Athletes tend to have better visuo-motor performance than do sedentary ***,several basic visual-function and perceptual parameters remain unexplored to *** this study,we investigated whether differences exist in visual function,performance,and processing between basketball players and individuals without a sport-involvement ***:A total of 33 healthy men with no visual impairment or pathology were divided into 2 groups,depending on the involvement in sport(semi-professional basketball players and sedentary individuals).We tested their baseline heart-rate variability in the resting position apart from subjective questionnaires to determine their physical fitness level,and we checked their visual function,performance,and processing through an extended battery of optometric ***:The 2 groups differed in resting heart-rate variability parameters(p<0.001),confirming their dissimilarities in regular time practising sports per *** basketball players showed a closer breakpoint and recovery nearpoint of convergence,a higher fusional-vergence rate,better discriminability halos,and better eye-hand coordination(all p values<0.05).Conclusion:These results show evidence that athletes,basketball players in this case,exhibit better performance in several visual abilities in comparison to a group of individuals without sporting backgrounds,suggesting an improvement due to the systematic involvement of those skills during basketball practice.

关键词： Exercise Fitness level Health Heart rate variability Visual skills Team sport