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Wettability of silicon carbide ceramic by Al_2O_3/Dy_2O_3 and Al_2O_3/Yb_2O_3 systems

Journal of Rare Earths 2013年第6期31卷 634-638页

作者： J.A.da Silva B.m.moreschi G.C.R.garcia S.Ribeiro Department of materials Engineering (DEmAR) Engineering School of Lorena (EEL)Pólo Urbo IndustrialGleba AI6CP 11612608-970LorenaSPBrazil

Wettability is an important phenomenon in the liquid phase sintering of silicon carbide （SiC） ceramics. This work involved a study of the wetting of SiC ceramics by two oxide systems, Al2O3 /Dy2O3 and Al2O3 /Yb2O3, which have so far not been studied for application in the sintering of SiC ceramics. Five mixtures of each system were prepared, with different compositions close to their respective eutectic ones. Samples of the mixtures were pressed into cylindrical specimens, which were placed on a SiC plate and subjected to temperatures above their melting points using a graphite resistance furnace. The behavior of the melted mixtures on the SiC plate was observed by means of an imaging system using a CCD camera and the sessile drop method was employed to determine the contact angle, the parameter that measures the degree of wettability. The results of variation in the contact angle as a function of temperature were plotted in graphic form which showed that the curves displayed a fast decline and good spreading. All the samples of the two systems presented final contact angles of 40o to 10o indicating their good wetting on SiC in the argon atmosphere. The melted/solidified area and interface between SiC and melted/solidified phase were evaluated by scanning electron microscopy （SEm） and their crystalline phases were identified by X-ray diffraction （DRX）. The DRX analysis showed that Al2O3 and RE2O3 reacted and formed the Dy3Al5O12 （DyAg） and Yb3Al5O12 （YbAg） phases. The results indicated that the two systems had a promising potential as additives for the sintering of SiC ceramics.

关键词： liquid-phase sintering silicon carbide rare earth oxide wettability contact angle

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Soil fertilization does not alter plant architectural effects on arthropod communities

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Journal of Plant Ecology 2017年第5期10卷 800-807页

作者： m.Noelia Barrios-garcia mariano A.Rodriguez-Cabal Jennifer A.Rudgers Gregory m.Crutsinger CONICET CENAC-APNFagnano 244BarilocheRio Negro CP.8400Argentina Grupo de Ecología de Invasiones INIBIOMA-CONICETUniversidad Nacional del ComahueAv.de los Pioneros 2350BarilocheRio Negro CP.8400Argentina Department of Biology University of New MexicoCastetter Hall 286AlbuquerqueNM 87131USA Department of Zoology University of British Columbia#4200-6270 University Blvd.VancouverBritish Columbia V6T 1Z4Canada

Aims While a growing number of studies have demonstrated the impor-tance of intraspecific differences within plant species on associ-ated arthropod communities,little is known regarding the relative strength of these effects compared to environmental *** this study,we examined whether intraspecific plant differences and nutrient fertilization interact to shape the arthropod community of a dominant coastal shrub,Baccharis pilularis(coyote bush).methods We overlaid a fertilization treatment on a 12-year-old common garden experiment planted with erect and prostrate architectural morphs of Baccharis in california,*** collect the associated arthropod community,we vacuum sampled the crown of each Baccharis and identified individuals to species or *** Findings We found that arthropod richness and abundance were 2-to 3-fold greater on prostrate Baccharis than on erect morphs,but observed no main effects of fertilizer addition on the over-all arthropod *** responded as strongly as herbivores to plant morph,and both were unaffected by nutrient *** the specialist stem galler,Gnorimoschema bac-charisella,showed an interactive response to plant morph and ***,phosphorous and potassium addition had opposite effects on the two morphs,increasing stem gall abun-dance by 50%on prostrate morphs,but reducing galling by 20%on erect *** architectural complexity of prostrate morphs could be the driving mechanism of differences in arthropod ***,our results demonstrate that communitylevel consequences of intraspecific differences in plants are strong,rather than being context dependent,and are generally maintained under different resource *** growing number of studies showing strong genotype than nutrient effects on associated arthropod communities suggests that this might be a generalized pattern.

关键词： Baccharis pilularis community genetics G×E interactions galling insects nutrient fertilization

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Electro-acupuncture to prevent prolonged postoperative ileus:A randomized clinical trial

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World Journal of Gastroenterology 2010年第1期16卷 104-111页

作者： m Kay garcia Joseph S Chiang Bob Thornton J Lynn Palmer Jennifer mcQuade Lorenzo Cohen Department of Anesthesiology and Pain medicine/Integrative medicine M.D.Anderson Cancer CenterThe University of Texas Department of Anesthesiology and Pain medicine M.D.Anderson Cancer CenterThe University of Texas Department of Palliative Care and Rehabilitation medicine M.D.Anderson Cancer CenterThe University of Texas Department of Behavioral Science M.D.Anderson Cancer CenterThe University of Texas Department of GI medical Oncology M.D. Anderson Cancer CenterThe University of Texas

AIm:To examine whether acupuncture can prevent prolonged postoperative ileus(PPOI)after intraperitoneal surgery for colon cancer. mETHODS:Ninety patients were recruited from the Fudan University Cancer Hospital,Shanghai,China. After surgery,patients were randomized to receive acupuncture(once daily,starting on postoperative day 1, for up to six consecutive days)or usual *** was defined as an inability to pass flatus or have a bowel movement by 96 h after *** main outcomes were time to first flatus,time to first bowel movement, and *** outcomes were quality of life(QOL)measures,including pain, nausea,insomnia,abdominal distension/fullness,and sense of well-being. RESULTS:No significant differences in PPOI on day 4 (P=0.71)or QOL measures were found between the *** were also no group differences when the data were analyzed by examining those whose PPOI had resolved by day 5(P=0.69)or day 6(P= 0.88).No adverse events related to acupuncture were reported. CONCLUSION:Acupuncture did not prevent PPOI andwas not useful for treating PPOI once it had developed in this population.

关键词： Acupuncture Gastrointestinal motility Gastrointestinal disorders Gastrointestinal neoplasms

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Overview of power electronics technology and applications in power generation, transmission and distribution

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Journal of modern Power Systems and Clean Energy 2017年第4期5卷 499-514页

作者： J.m.mAZA-ORTEGA E.ACHA S.garcia A.GómEZ-EXPóSITO Department of Electrical Engineering University of SevillaSevilleSpain Department of Electrical Energy Engineering Tampere University of TechnologyTampereFinland School of Electrical Engineering Universidad MichoacanaMoreliaMexico

The main objective of this paper is ***, to provide an overview of the current status of the power electronics technology, one of the key actors in the upcoming smart grid paradigm enabling maximum power throughputs and near-instantaneous control of voltages and currents in all links of the power system chain. Second, to provide a bridge between the power systems and the power electronic communities, in terms of their differing appreciation of how these devices perform when connected to the power grid. Third, to discuss on the role that the power electronics technology will play in supporting the aims and objectives of future decarbonized power systems. This paper merges the equipment, control techniques and methods used in flexible alternating current transmission systems(FACTS) and high voltage direct transmission(HVDC) equipment to enable a single, coherent approach to address a specific power system problem, using ‘best of breed’ solutions bearing in mind technical, economic and environmental issues.

关键词： Flexible alternating current transmission systems(FACTS) High voltage direct transmission(HVDC) Voltage source converter(VSC) Insulated gate bipolar transistor(IGBT) Smart grids

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Estimates of voluntary activation in individuals with anterior cruciate ligament reconstruction:Effects of type of stimulator,number of stimuli,and quantification technique

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Journal of Sport and Health Science 2022年第1期11卷 85-93页

作者： Steven A.garcia Kazandra m.Rodriguez Scott R.Brown Riann m.Palmieri-Smith Chandramouli Krishnan School of Kinesiology University of MichiganAnn ArborMI 48109USA Neuromuscular and Rehabilitation Robotics Laboratory(NeuRRo Lab) Department of Physical Medicine and RehabilitationUniversity of MichiganAnn ArborMI 48108USA Department of Orthopaedic Surgery Michigan MedicineUniversity of MichiganAnn ArborMI 48109USA Robotics Institute University of MichiganAnn ArborMI 48109USA

Background:Accurate quantification of voluntary activation is important for understanding the extent of quadriceps dysfunction in individuals with anterior cruciate ligament reconstruction(ACLR).Voluntary activation has been quantified using both percent activation derived from the interpolated twitch technique and central activation ratio(CAR)derived from the burst superimposition technique,as well as by using different types of electrical stimulators and pulse train ***,it is unclear how these parameters affect voluntary activation estimates in individuals with *** study was performed to fill this important knowledge gap in the anterior cruciate ligament ***:Quadriceps strength and voluntary activation were examined in 18 ACLR participants(12 quadriceps/patellartendon graft,6 hamstring tendon graft;time since ACLR:1.06±0.82 years,mean±SD)at 90°of knee flexion using 2 stimulators(Digitimer and Grass)and pulse train conditions(3-pulse and 10-pulse).Voluntary activation was quantified by calculating both CAR and percent ***:Results indicated that voluntary activation was significantly overestimated by CAR when compared with percent activation(pmates were not affected by pulse train conditions when using percent activation;however,3-pulse stimuli resulted in greater overestimation than 10-pulse stimuli when using CAR(p=0.003).Voluntary activation did not differ between stimulators(p>0.05);however,the Digitimer evoked greater torque at rest than the Grass(pm the interpolated twitch technique provides superior estimates of voluntary activation than CAR derived from burst superimposition and is less affected by pulse train conditions or stimulators in individuals with ACLR.

关键词： Anterior cruciate ligament Central activation Inhibition Knee strength Triplet Twitch interpolation

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On the use of ferroelectric material LiNbO3 as novel photocatalyst in wastewater-fed microbial fuel cells

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Particuology 2017年第5期15卷 147-155页

作者： N.Touach V.m.Ortiz-martinez m.J.Salar-garcia A.Benzaouak F.Hernandez-Fernandez A.P.de Rios m.El mahi E.m.Lotfi Laboratory of mechanics Processes and Industrial Process Team Chemical Sciences ENSET Mohammed V University in Rabat Morocco School of Chemical and Environmental Engineering Polytechnic University of Cartagena Campus Muralla Del Mar Murcia Spain University of murcia Chemical Engineering Department Campus de Espinardo E-30071 Murcia Spain

In this work, the use of lithium niobate （LiNbO3）, a ferroelectric and photocatalyst material, is investi- gated as a new type of cathode catalyst for wastewater-fed single-chamber microbial fuel cells （mFCs）. Carbon cloth electrodes coated with LiNbO3 were studied with and without UV-vis irradiation to assess its photocatalytic behavior in these devices. The synthesized phase of LiNbO3 was characterized by X- ray diffraction, differential scanning calorimetry, particle size distribution, and transmission electron microscopy analyses. The mFC containing a LiNbO3-based cathode exhibited a maximum open circuit potential and power output of 400 mV and 131 mW/m^3, respectively, under irradiation. This cathode configuration also achieved the maximum chemical oxygen demand removal of 84% after 120 h of mFC operation. These results show that ferroelectric materials such as LiNbO3 could be used as cathode cat- alysts in mFC devices. As a complementary analysis, the removal of the heavy metals detected in the wastewater was also monitored.

关键词： Lithium niobate Ferroelectric material Photocatalyst microbial fuel cell (mFC)Power outputWastewater treatment

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Corrosion and passive film characteristics of 3D-printed NiTi shape memory alloys in artificial saliva

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Rare metals 2023年第9期42卷 3114-3129页

作者： ming Liu Jia-Ning Zhu V.A.Popovich E.Borisov J.m.C.mol Y.Gonzalez-garcia State Key Laboratory for mechanical Behavior of materials Center for Advancing Materials Performance from the Nanoscale(CAMP-Nano)Xi’an Jiaotong UniversityXi’an710049China Department of materials Science and Engineering Delft University of TechnologyAA Delft2600The Netherlands Peter the Great Saint-Petersburg Polytechnic University Saint Petersburg195251Russia

Electrochemical tests and surface analysis were applied to study the corrosion behavior and passive film characteristics of three-dimensional-printed NiTi shape memory alloys fabricated by laser-powder bed fusion(LPBF) in artificial saliva at 37.C. The passivity of L-PBF NiTi shows to be influenced by the process parameters and resulting morphological and physicochemical surface properties. The results show that the defects at the surface of L-PBF Ni Ti can promote the passivation rate in the early stages of exposure but a slowly formed passive film shows the best corrosion protection. The thickness of the passive film is positively correlated with its corrosion protective performance. The L-PBF NiTi alloy prepared at a linear energy density of 0.2 J·m^(-1) and volumetric energy density of 56 J·mm^(-3) shows the least defects and best corrosion protection. An outer Ti-rich and inner Ni-rich dense passive film could be also obtained showing higher corrosion resistance.

关键词： NiTi Laser-powder bed fusion(L-PBF) Passive film Corrosion resistance Artificial saliva

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Strong emissions of blue-yellow-red regions of La and Ti modified KNaNbO_(3) ferroelectric ceramics

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Journal of Advanced Ceramics 2015年第3期4卷 183-189页

作者： m.D.DURRUTHY-RODRIGUEZ m.HERNANDEZ-garcia J.PORTELLES J.FUENTES m.A.HERNANDEZ-LANDAVERDE m.RAmIREZ CARDONA J.m.YANEZ-LImON Departamento de Fisica Aplicada Instituto de CiberneticaMatematica y FisicaCITMA15#551VedadoLa HabanaCP 10400Cuba Facultad de Fisica Universidad de La HabanaSan Lazaro y LVedadoLa HabanaCP 10400Cuba CINVESTAV-Unidad Queretaro IPNLibramiento Norponiente 2000Fracc.Real de JuriquillaCP 76230QueretaroMexico Centro de Investigaciones en Ciencias de la Tierra y materiales Universidad Autonoma del Estado de HidalgoMexico

In this work,the results of the study on the optical properties of the perovskite structure ABO3 with La^(3+) substitution for ions K^(+) and Na^(+) in the A site and Ti^(4+) substitution for ion Nb^(5+) in the B site are *** ceramics were sintered at 1100℃ and 1190℃ and formed at 10 mPa and 80 *** ceramics were obtained with 94% of the theoretical *** piezoresponse force microscopy(PFm)showed needle-shaped grains with a size of 30 nm for the samples formed at 10 mPa at both sintering ***,the high temperature and high pressure used in formation reduced the energy of the band gap(Eg)from 3.36 to 3.09 *** emissions to 2.19,1.86,2.5,and 2.31 eV were obtained by exciting the samples at 325,373,457,and 500 nm,respectively;these emissions corresponded to blue-yellow-red regions of the visible spectrum.

关键词： emission spectra condense matter ferroelectric materials band structure X-ray diffraction(XRD)

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An Invasive Succulent Plant (Kalanchoe daigremontiana) Influences Soil Carbon and Nitrogen mineralization in a Neotropical Semiarid Zone

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Pedosphere 2018年第4期28卷 632-643页

作者： Ileana HERRERA Jose R. FERRER-PARIS Diana BENZO Saul FLORES Belkis garcia Jafet m. NASSAR Ecuela de Ciencias Ambientales Universidad Espiritu Santo Guayaquil 091650 (Ecuador) Centro de Ecologla Instituto Venezolano de Investigaciones Cientificas (IVIC) Caracas 1020 (Venezuela) Centro de Estudios Botdnieos y Agroforestales Instituto Venezolano de Investigaeiones Cientificas Maracaibo 4005 (Venezuela)

It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effects caused by the invasion of a noxious exotic plant, Kalanchoe daigrernontiana （Crassulaceae）, on C and N mineralization and enzymatic and microbial activities in the soil of a semiarid locality in Venezuela. We compared soil parameters associated with these processes （C and N mineralization time and the cumulative values, fluorescein diacetate hydrolytic activity, and activities of dehydrogenase, β-glucosidase, glucosaminidase, and urease） between invaded and adjacent non-invaded sites. In addition, correlations among these parameters and the soil physical-chemical properties were also examined to determine if a positive feedback exists between nutrient availability and K. daigremontiana invasion. Overall, our results showed that C mineralization and transformation of organic compounds to NH4^＋ were favored at sites colonized by K. daigrernontiana. With this species, we found the highest cumulative amounts of NH4^＋-N and C and the lowest mineralization time. These results could be explained by higher activities of urease and glueosaminidase in soils under the influence of K. daigremontiana. In addition, higher amounts of organic matter and moisture content in invaded soils might favor C and N mineralization. In conclusion, invasion of Neotropical semiarid zones by K. daigrernontiana may influence the chemical and biological properties of the soils covered by this species, increasing nutrient bioavailability, which, in time, can facilitate the invasion process.

关键词： Akaike Information Criterion C and N pools enzymatic activity NH4^+-N NO3^--N nutrient availability plant invasion

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A simulation approach: miscible carbon dioxide injection in a carbonate reservoir

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Petroleum Science 2010年第2期7卷 257-262页

作者： Ehsan Heidaryan Jamshid moghadasi marylena garcia Quijada Faculty of Energy Kermanshah University of Technology Petroleum Engineering Department Petroleum University of Technology Texas A&m University College Station Texas USA

The purpose of this study is to optimize the existing carbon dioxide （CO2） flood in deep dolomite formations by improving oil sweep efficiency of miscible CO2 floods and enhancing the conformance control. A full compositional simulation model using a detailed geologic characterization was built to optimize the injection pattern. The model is a quarter of an inverted nine-spot and covers 20 acres of field formation. Geologic description was used to construct the simulation grids. The simulation layers represent actual flow units and resemble the large variation of reservoir properties. History match was performed to validate the model. Several sensitivity runs were made to improve the CO2 sweep efficiency and increase the oil recovery. Finally, the optimum CO2 injection rate for dolomite formations was determined approximately. Simulation results also indicate that a water-alternating-gas （WAG） ratio of 1：1 along with an ultimate CO2 slug of 100% hydrocarbon pore volume （HCPV） will allow an incremental oil recovery of 18%. The additional recovery increases to 34% if a polymer is injected as a conformance control agent during the course of the WAG process at a ratio of 1：1. According to the results, a pattern reconfiguration change from the nine spot to staggered line drive would represent an incremental oil recovery of 26%.

关键词： miscible injection carbon dioxide dolomite formation water-alternating-gas

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