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American Journal of Analytical Chemistry 2013年第7期4卷 100-108页

作者： Pedro Rodríguez humberto rojas Miguel Medina Jazzmin Arrivillaga Yosue Francisco Fracehuli Dager Vincent Piscitelli Manuel Caetano Alberto Fernández Jimmy Castillo Centro de Microscopia Electrónica Facultad de Ciencias Universidad Central de Venezuela Caracas Venezuela Departamento de Biología Universidad Simón Bolívar Caracas Venezuela Escuela de Biología Facultad de Ciencias Universidad Central de Venezuela Caracas Venezuela Laboratorio de Espectroscopia Laser Facultad de Ciencias Universidad Central de Venezuela Caracas Venezuela

In this work we present the preparation and functionalization of gold nanoparticles (AuNPs) for the detection of presence of gp63 glycoprotein in the surface of Leishmania genus parasites. AuNPs were prepared by induced laser ablation in a clean and biologically suitable media. The nanoparticles were functionalized with anti-gp63 lgG antibody in order to study the interaction with the glycoprotein component gp63 (63 kDa) present on the membrane surface of Leishmania genus parasites. The functionalized AuNPs showed potential as a spectrometric indicator of the parasite existence, both by the detection of the presence of the gp63 in solution and through the specific interaction with the parasites in vitro. The specificity of the study opens a new line of research on the use of modified nanoparticles in the development of a fast and easy assay for Leishmaniosis diagnostics.

关键词： Leishmania Nanoparticles Surface Plasmon Resonance gp63 Protein

An Approach to Design MIMO FO Controllers for Unstable Nonlinear Plants

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IEEE/CAA Journal of Automatica Sinica 2016年第3期3卷 338-344页

作者： Arturo rojas-Moreno IEEE Department of Electrical Engineering Universidad de Ingenieriay Tecnologia (www.utec.edu.pe)

This paper develops an approach to control unstable nonlinear multi-inputs multi-output(MIMO) square plants using MIMO fractional order(FO) controllers. The controller design uses the linear time invariant(LTI) state space representation of the nonlinear model of the plant and the diagonal closedloop transfer matrix(TM) function to ensure decoupling between inputs. Each element of the obtained MIMO controller could be either a transfer function(TF) or a gain. A TF is associated in turn with its corresponding FO TF. For example, a D(Derivative) TF is related to a FO TF of the form Dδ, δ =[0, 1]. Two applications were performed to validate the developed approach via experimentation: control of the angular positions of a manipulator, and control of the car and arm positions of a translational manipulator.

关键词： Fractional calculus modeling of nonlinear sys-tem control of manipulator multivariable decoupling multivari-able nonlinear system

Physicochemical properties of Li_(3)Ba_(2)La_(3)(MoO_(4))_(8):Eu,Tb red-emitting phosphor for solid state white lamps

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Journal of Rare Earths 2023年第9期41卷 1279-1287,I0001页

作者： Kora Lu rojas Baldivia Gustavo A.Hirata Center for Scientific Research and Higher Education of Ensenada Ensenada Baja California 22860Mexico Center for Nanoscience and Nanotechnology National Autonomous University of Mexico EnsenadaBaja Califomia 22860Mex

In this work,combustion synthesis was used for the first time to fabricate a phosphor material with red emission for applications in solid-state white-light *** synthesized a material with emission wavelength at λ_(em)=617 nm,excited under long UV-blue wavelength based on Eu^(3+),Tb^(3+)-activated molybdates Li_(3)Ba_(2)(La_(1-x-y)Eu_(x)Tb_(y))_(3)(MoO_(4))_(8) with 0 ≤ x ≤1 and 0 ≤ y ≤ 1.A series of powder samples were produced by the combustion method and post-annealed at 800℃ in *** crystalline phase formation was investigated by X-ray diffraction,which reveals the monoclinic C2/c(15) space *** is observed that crystalline structure and morphology are preserved when the host lattice is doped with Eu^(3+) or Tb^(3+) single ions and co-doped with both ions at different doping concentrations.A detailed characterization by scanning electron microscopy(SEM) and transmission electron microscopy(TEM)shows a similar morphology in all samples:rather large(1-7 μm) agglomerate particles with irregular shapes and surrounded by smaller nanoparticles of 50 nm in ***-visible absorption spectra confirm the presence of Eu^(3+) and Tb^(3+) *** luminescent properties of the obtained phosphors were studied in *** measurements indicate that the best emission intensity is for Eu^(3+):Tb^(3+)doping ratios of 80:0,90:0 and 20:*** the other hand,samples with 80:0,60:40,and 20:80 doping ratios show the highest intensity in a detailed photoluminescence analysis and they exhibit the highest quantum yield values.A complete and efficient energy transfer from the sensitizer Tb^(3+) to the activator Eu^(3+) is observed in all co-doped phosphors post-annealed at 800℃ for 4 ***,the Li_(3)Ba_(2)La_(3)(MaO_(4))_(8):Eu^(3+),Tb^(3+) materials fabricated by combustion synthesis are excellent phosphors for being applied as red-emitting component in solid-state white-light lamps due to an improved color rendering index(CRI) that can be obtained under lo

关键词： Molybdate Europium Terbium Luminescence Phosphor-converted LED Rare earths

UPLAND EROSION MODELING WITH CASC2D-SED

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International Journal of Sediment Research 2002年第4期17卷 265-274页

作者： Pierre JULIEN,Rosalía rojas Engineering Research Center Colorado State University Research Associate Civil Engineering Dept. Colorado State University Professor of Civil EngineeringFortCollins CO80523 USA Fort Collins CO80523 USA

Developed at Colorado State University, CASC2D-SED is a physically-based model simulating the hydrologic response of a watershed to a distributed rainfall field. The time-dependent processes include: precipitation, interception, infiltration, surface runoff and channel routing, upland erosion, transport and sedimentation. CASC2D-SED is applied to Goodwin Creek, Mississippi. The watershed covers 21 km2 and has been extensively monitored both at the outlet and at several internal locations by the ARS-NSL at Oxford, MS. The model has been calibrated and validated using rainfall data from 16 meteorological stations, 6 stream gauging stations and 6 sediment gauging stations. Sediment erosion/deposition rates by size fraction are predicted both in space and time. Geovisualization, a powerful data exploration technique based on GIS technology, is used to analyze and display the dynamic output time series generated by the CASC2D-SED model.

关键词： Geographical Information System (GIS) Hydrologic model Soil erosion Watershed

Potential use of magnesium industrial waste for synthesis of Li and Mg co-doped LiMn_(2)O_(4)nanoparticles as cathode material for Li-ion batteries:Effect of sintering temperature

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Nano Research 2022年第5期15卷 4500-4516页

作者： Aleksei Llusco Luis rojas Svetlana Ushak Mario Grageda Department of Chemical Engineering and Mineral Processing and Center for Advanced Study of Lithium and Industrial Minerals(CELiMIN) Universidad de AntofagastaAntofagasta 1270300Chile

Potential advantages of active electrode nanomaterials have led to development of high energy and power density lithium-ion(Li-ion)***,under increasing demand for critical resources such as lithium and cobalt,it is necessary to use abundant raw materials,which can be obtained from industrial *** this work,purified Mg(OH)_(2)from waste generated in the production of Li2CO3 with natural brines from the Salar de Atacama(Chile)is used as a doping agent for synthesis of LiMn_(2)O_(4)(LMO)spinel octahedral nanoparticles co-doped with excess Li and *** of a pure cubic spinel phase(Fd3m)takes place at 500℃and sintering temperature effect at 580 and 750℃,thus the elemental composition and the structural,morphological,and electrochemical properties are studied in *** electrochemical performance at room temperature is obtained for Li_(1.03)Mg_(0.05)Mn_(1.92)O_(4)spinel sintered at 750℃with an initial discharge capacity of 121.3 mAh·g^(-1)and capacity retention of 94.0%after 100 cycles at C/3.A locally ordered spinel structure is obtained at 750℃,and doping with Mg^(2+)improves structural *** between both effects resulted in a high Li^(+)diffusion rate(1.29×10^(-9)cm^(2)·s^(-1))significantly improving cycling performance at elevated C-rates in 50℃.

关键词： LiMn_(2)O_(4)(LMO)spinel Mg doped excess Li octahedral nanoparticle industrial waste lithium-ion(Li-ion)batteries

Processing of ingredients and diets and effects on nutritional value for pigs

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Journal of Animal Science and Biotechnology 2017年第4期8卷 751-763页

作者： Oscar Javier rojas Hans Henrik Stein Devenish Nutrition Fairmont MN 56031 USA Department of Animal Sciences University of Illinois Urbana IL 61801 USA.

A conventional diet based on corn and soybean meal fed to pigs is usually provided in a mash form and in most cases, processing other than grinding and mixing is not used. However, due to the high cost of energy in pig diets,use of high fiber ingredients such as soybean hulls, distillers dried grains with solubles, and wheat middlings has increased. High fiber concentrations in the diet usually results in reduced energy and nutrient digestibility due to the low capacity of pigs to digest fiber, which negatively impacts growth performance and carcass composition of the pigs. Feed processing technologies such as changes in grinding procedures, expansion, extrusion, pelleting, use of enzymes or chemical treatments may, however, be used to solubilize some of the cel ulose and hemicel ulose fractions that form the cel wal of plants in the ingredients, and therefore, increase nutrient availability. This may have a positive effect on energy digestibility, and therefore, also on pig growth performance and carcass composition, but effects of different feed technologies on the nutritional value of feed ingredients and diets fed to pigs are not fully understood. It has however, been demonstrated that reduced particle size of cereal grains usually results in increased digestibility of energy, primarily due to increased digestibility of starch. Extrusion or expansion of ingredients or diets may also increase energy digestibility and it appears that the increase is greater in high fiber diets than in diets with lower concentrations of fiber. Chemical treatments have not consistently improved energy or nutrient digestibility, but a number of different enzymes may be used to increase the digestibility of phosphorus, calcium, or energy. Thus, there are several opportunities for using feed technology to improve the nutritional value of diets fed to pigs.

关键词： Chemical treatments Enzymes Particle size Pig Processing Starch

Use of two-surfactants mixtures to attain specific HLB values for assisted TPH-diesel biodegradation

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Journal of Environmental Sciences 2004年第6期16卷 950-956页

作者： Luis G. Torres Neftalí rojas Rosario Iturbe Instituto de Ingeniería Universidad Nacional Autó noma de México Coordinación de Ingeniería Ambiental Grupo Saneamiento de Suelos y Acuíferos Apartado Postal 70-472 Coyoacán 04510 México D.F. Mexico

In a surfactant assisted biodegradation process, the choice of surfactant(s) is of crucial importance. The question is: does the type of surfactant(i.e. chemical family) affect the biodegradation process at fixed hidrophillic-lypofillic balance(HLB) values? Microcosm assessments were developed using contaminated soil, with around of 5000 mg/kg of hydrocarbons as TPH-diesel. Mixtures of three nonionic surfactants were employed to get a wide range of specific HLB values. Tween20 and Span20 were mixed in the appropriate proportions to get HLB values between 8.6 and 16.7. Tween/Span60 mixtures reached HLB values between 4.7 and 14.9. Finally, Tween/Span80 combinations yielded HLB values between 4.3 and 15. TPH-diesel biodegradation was measured at the beginning, and after 8 weeks, as well as the FCU/gr soil, as a measure of microorganisms′ development during the biodegradation period. A second aim of this work was to assess the use of guar gum as a biodegradation enhancer instead of synthetic products. The conclusions of this work are that surfactant chemical family, and not only the HLB value clearly affects the assisted biodegradation rate. Surfactant's synergism was clearly observed. Regarding the use of guar gum, no biodegradation enhancement was observed for the three assessed concentrations, i.e., 2, 20, and 200 mg/kg, respectively. On the contrary, TPH-diesel removal was lower as the gum concentration increased. It is quite possible that guar gum was used as a microbial substrate.

关键词： aged soils enhanced bioremediation HLB mixtures Tween Span surfactants

Observation of dipolar transport in one-dimensional photonic lattices

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Science Bulletin 2017年第5期62卷 339-344页

作者： Camilo Cantillano Luis Morales-Inostroza Bastián Real Santiago rojas-rojas Aldo Delgado Alexander Szameit Rodrigo A.Vicencio Departamento de Física MSI-Nucleus on Advanced Opticsand Center for Optics and Photonics(CEFOP)Facultad de CienciasUniversidad de ChileSantiagoChile Center for Optics and Photonics and MSI-Nucleus on Advanced Optics Universidad de ConcepciónCasilla 160-C ConcepcionChile Institute for Physics University of RostockD-18059 RostockGermany

We experimentally study the transport properties of dipolar and fundamental modes on one dimensional(1D) coupled waveguide arrays. By carefully modulating a wide optical beam, we are able to effectively excite dipolar or fundamental modes to study discrete diffraction(single-site excitation) and gaussian beam propagation(multi-site excitation plus a phase gradient). We observe that dipolar modes experience a larger spreading area due to an effective larger coupling constant, which is found to be more than two times larger than the one for fundamental modes. Additionally, we study the effect of non-diagonal disorder and find that while fundamental modes are already trapped on a weakly disorder array, dipoles are still able to propagate across the system.

关键词： Photonic lattices Waveguide arrays Wave propagation Integrated optics

Myxomycete colonization on translocated and non-translocated dead leaves from temperate and tropical forests

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Studies in Fungi 2020年第1期5卷 462-470页

作者： rojas C Stephenson SL rojas PA Finca Experimental Interdisciplinaria de Modelos Agroecológicos University of Costa RicaTurrialba30502-Costa Rica Engineering Research Institute University of Costa RicaSan Pedro de Montes de Oca11501-Costa Rica Department of Biological Sciences University of ArkansasFayettevilleAR 72701USA

Samples of dead leaves on the forest floor were collected from a locality in central Costa Rica and another locality in northwest Arkansas in the United States and then were placed in fine-mesh nylon bags,autoclaved and left out in the field for four *** of the bags prepared with sterile material from each country were placed out in the country where they were collected,and the other half were placed in the other country.A characterization of forest structure and ground leaf chemistry was carried out for both localities and both leaf *** recollected,all samples were processed for myxomycetes with the use of the moist chamber culture *** cultures yielded a total of 156 records of myxomycetes representing 16 species,but only 13 records and six species were isolated from the samples left out in Costa *** hundred percent of cultures placed out in Arkansas produced myxomycetes,whereas only 68%of those placed out in Costa Rica were positive for these *** in species richness and number of records were observed across forests where the samples were placed out,and no differences were observed based on the origin of the *** suggested that myxomycete colonization in the studied areas is primarily affected by the dynamics of the forest type and secondarily by substrate *** myxomycete species recorded on leaves with poorer chemical values are also consistent with field *** the present study,the more open character of the temperate forest in Arkansas without a film of water layer covering the leaves on the ground seemed to have played a role in the establishment of myxomycete propagules in the sterile material during the time of the investigation.

关键词： Arkansas Costa Rica myxogastrids Pea Ridge slime molds Turrialba

＂Symptom of an Era＂： Dung Kai-Cheung＇s Histories of Time

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Frontiers of Literary Studies in China-Selected Publications from Chinese Universities 2016年第1期10卷 133-149页

作者： Carlos rojas Asian Pacific Studies Institute Duke University John Hope Franklin Center 2204 Erwin RoadDurham NC 27708-0411 USA

This essay uses the notion of a symptom to examine the ways in which temporality is deployed in Hong Kong author Dung Kai-Cheung＇s 2007 novel, Histories o^Time. In particular, the essay follows Dung＇s own lead, in Histories of Time, and considers the peculiar temporality implicit in the concept of figuration in Biblical hermeneutics, wherein the ＂figure＂ mediates between the two distinct--yet structurally related--temporalities of the Old and the New Testaments： the ＂prefiguration＂ of the Old Testament and the ＂fulfillment of figuration＂ of the New Testament. I propose that a literary ＂figure,＂ in Dung＇s work, similarly mediates between the different temporal planes within his novel, while at the same time mediating between the fictional space of the novel and the historical era within which the work is positioned. Just as a symptom is simultaneously a function of--but also structurally external to--the underlying condition that it signifies, this sort of literary figure may similarly be seen as a function of--but simultaneously external to--the historical era to which it corresponds. This sort of literary figure, accordingly, marks a point of rupture within the temporality of the novel and its corresponding era, while at the same time providing the ground on which that temporal continuum is established in the first place.

关键词： Dung Kai-Cheung Histories of Time symptom figuration Hong Kong