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Synthesis and Characterization of Bimetallic Gold-Silver Core-Shell Nanoparticles: A Green Approach

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Advances in Nanoparticles 2015年第4期4卷 116-121页

作者： A. Calagua H. Alarcon F. Paraguay Juan Rodriguez facultad de Ciencias Universidad Nacional de Ingenier&iacute a Lima Per&uacute Laboratorio Nacional de Nanotecnologí a Centro de Investigaci&oacute n de Materiales Avanzados Chihuahua M&eacute xico

Bimetallic gold-silver core-shell nanoparticles were prepared by chemical reduction in aqueous solution, following a method that was friendly to the environment, allowing us to use this for medicinal purposes. Gold nanoparticles were synthesized, and silver cations were then reduced on the nanoparticles. Using the optical properties of metallic nanoparticles, surface plasmon resonance was determined by UV-Vis spectroscopy, and the values obtained for gold and silver were approximately 520 nm and 400 nm in wavelength, respectively. The absorption peaks of the surface plasmon band show a clear red-shift due to size effect in the case of the silver surface, and a plasmon coupling effect, in the case of gold. To obtain a better understanding of the coating conditions, high resolution transmission electron microscopy was used. The average hydrodynamic size and the size distribution of the synthesized nanoparticles were obtained by dynamic light scattering. The development of this process, which is benign for the environment, opens the possibility for many applications in the areas of renewable energy, medicine and biology.

关键词： Nanoparticles Bimetallic Core-Shell Gold Silver Au/Ag

Alternative derivation of the Mean-Field Equations for Composite Fermions

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Journal of Modern Physics 2015年第12期6卷 1737-1742页

作者： Edmundo C. Manavella Carlos E. Repetto Instituto de Física Rosario (CONICET-UNR) Rosario Argentina facultad de Ciencias Exactas Ingeniería y Agrimensura (UNR) Rosario Argentina

The Hamiltonian describing a composite fermion system is usually presented in a phenomenological way. By using a classical nonrelativistic U(1) × U(1) gauge field model for the electromagnetic interaction of electrons, we show how to obtain the mean-field Hamiltonian describing composite fermions in 2 + 1 dimensions. In order to achieve this goal, the Dirac Hamiltonian formalism for constrained systems is used. Furthermore, we compare these results with the ones corresponding to the inclusion of a topological mass term for the electromagnetic field in the Lagrangian.

关键词： Quantum Field Theory Field Theories in Dimensions Other than Four Chern-Simons Gauge Theory Lagrangian and Hamiltonian Formalisms

development of an Infusion Based on Romaine Lettuce and Banana for Treating Insomnia

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Agricultural Sciences 2020年第6期11卷 529-539页

作者： Daniel Revelo-Cáceres María Jesús Oliveras-López Marina Villalón-Mir Miguel Navarro-Alarcón Herminia López-García de la Serrana facultad de Farmacia Universidad de Granada Granada Espa&#241 a departamento de Biología Molecular e ingeniería Bioquímica Universidad Pablo de Olavide Sevilla Espa&#241 a

An infusion was developed based on green romaine lettuce leaves and banana. Further, its sensorial acceptability was evaluated as a possible alternative treatment for insomnia. The romaine lettuces and bananas used were washed, chopped, dehydrated and ground. Optimal lettuce dehydration time was determined through charting the weight lost and examining the curve. This was found after 180 minutes at 60°C. Two formulas were developed, the first with 1.1 g of dehydrated romaine lettuce and 0.2 g of dehydrated banana, and the second with 1.1 g of dehydrated romaine lettuce and 0.4 g of dehydrated banana. Sensory analysis was conducted using sorting tests for taste, aroma, paired preferences and intention to purchase. Tasters preferred the formula with a lower quantity of dehydrated banana. 85% of tasters indicated that they would buy this infusion due to its potential functional properties for overcoming insomnia.

关键词： Infusion Romaine Lettuce Banana Insomnia Sensory Analysis

Nutritional Composition of Sea Cucumber Isostichopus sp.

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Natural Resources 2016年第3期7卷 130-137页

作者： Wensy Vergara Adriana Rodrí guez Grupo de Investigació n y desarrollo Tecnoló gico en Acuicultura Facultad de Ingenier&iacute as Universidad del Magdalena Santa Marta Colombia

The knowledge of the chemical composition of invertebrates as sea cucumber contributes to improving our understanding of these living organisms. This study compared the chemical composition of wild sea cucumber Isostichopus sp., between February 2013 and January 2014. Sea cucumbers were captured by hand by artisanal fishermen and transported alive to the laboratory of Aquaculture of the Universidad del Magdalena (Colombia), where they were subsequently killed and taken to freeze until analysis. For proximate analysis 20 g of muscle were used for each sample. The analysis (in triplicate) was performed according to [1]. Significant differences (p Isostichopus sp. was similar to that reported for fresh sea cucumbers internationally traded, which indicates that it is a species with a competitive commercial value for use in food.

关键词： Caribbean Sea Chemical Composition Isostichopus Protein Lipids

Benzyl Amino Purine and Gibberellic Acid Coupled to Nitrogen-Limited Stress Induce Fatty Acids,Biomass Accumulation,and Gene Expression in Scenedesmus Obliquus

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Phyton-International Journal of Experimental Botany 2021年第2期90卷 515-531页

作者： Hans Christian Correa-Aguado Gloria Viviana Cerrillo-Rojas Alejandro Rocha-Uribe Ruth Elena Soria-Guerra JoséFrancisco Morales-Domínguez departamento de Química Centro de Ciencias BásicasUniversidad Autónoma de AguascalientesAguascalientes20131México facultad de Ciencias Químicas Universidad Autónoma de San Luis PotosíSan Luis Potosí78210México Instituto Politécnico Nacional Unidad Profesional Interdisciplinaria de Ingeniería Campus ZacatecasBlvd.del Bote 202Cerro del Gato Ejido La EscondidaCol.Ciudad AdministrativaZacatecasZAC 98160Mexico

The need for renewable energy sources makes microalgae an essential feedstock for biofuels *** molecular aspects and the response to nitrogen(N)-limited conditions with a phytohormone stimulus in microalgae have been slightly *** this work,Scenedesmus obliquus was used as a study model to analyze the effect of benzyl amino purine(BAP)and gibberellic acid(GA)coupled to nitrogen limitation on cell growth,biomass and fatty *** selected 10^(-5)M BAP increased the biomass by 1.44-fold,and 10^(-6)M GA by *** total lipids also increased by 2.8 and 1.11-fold,*** 10^(-5)M BAP and 10^(-6)M GA addition to *** cultures at different initial nitrogen percentages(N-0,N-25,and N-50)showed a significant increase in cell growth and biomass productivity compared to the unstimulated *** N-0 and GA N-0 produced the highest lipid yields with 55%and 50%,*** lipid profile analysis revealed an increase,particularly in C18:1 and C16:0 fatty *** expression analysis showed an over-expression of acyl carrying protein(ACP),stearoyl-ACP desaturase(SAD),fatty acid acyl-ACP thioesterase(FATA),and diacylglycerol acyltransferase(DGAT)genes,which were mainly induced by nitrogen ***,BAP and GA produced a significant over-expression on these genes in the N-replete *** study shows that BAP and GA,coupled to N limitation stress,can be used to increase the biomass and lipid production in *** for sustainable biofuels.

关键词： Biodiesel gene expression lipids microalgae nitrogen deficiency phytohormones

Adsorption of Pharmaceuticals and Personal Care Products on Granular Activated Carbon

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Journal of Surface Engineered Materials and Advanced Technology 2016年第4期6卷 183-200页

作者： Nasly Y. delgado Alberto L. Capparelli Damián J. Marino Agustín F. Navarro Gustavo A. Peñuela Alicia E. Ronco Centro de Investigaciones del Medio Ambiente Facultad de Ciencias Exactas Universidad Nacional de la Plata (UNLP) La Plata Argentina Consejo Nacional de Investigaciones Científicas y Técnicas La Plata Argentina División Fisicoquímica Facultad de Ciencias Exactas UNLP La Plata Argentina departamento de ingeniería Química Facultad de Ingeniería UNLP La Plata Argentina Grupo GDCON Universidad de Antioquia Medellín Colombia

We investigated the adsorption to granular activated carbon of two pharmaceuticals (carbamazepine and sildenafil citrate) and a personal-care product (methylparaben) in aqueous solution, characterized the carbon, and evaluated its influence on the kinetics and adsorption equilibrium of the compounds under study. We adjusted data for the analysis of equilibrium to Langmuir and Freundlich models of adsorption isotherms and described adsorption rate using pseudo first- and second-order models;that same analysis was made on the basis of the behavior of the initial rate. In addition, we analyzed the potentiality of a nonlinear adjustment for studying kinetics and equilibrium of adsorption, an approach requiring neither knowledge of equilibrium conditions nor a-priori hypothetical suppositions regarding the order of reaction. The results indicated that the nonlinear model was capable of describing adsorption kinetic behavior, in order to determine concentrations adsorbed at equilibrium, adsorption rates of the system, maximum adsorption capacity, and global rate constant. Granular carbon exhibited an adsorption capacity for carbamazepine and methylparaben of ca. 323 mg/g and for sildenafil citrate of ca. 142 mg/g, though with slow adsorption kinetics characterized by average adsorption times of at least 168 h.

关键词： Activated Carbon Carbamazepine Sildenafil Citrate Methylparaben Adsorption

Borane-Tetrahydrofurane Complex Reduction of Nickel and First Transition Metals in Tetrahydrofurane Media: Controllable Chemistry Leading to Nanoscale Metal and Metal Boride Particles

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Modern Research in Catalysis 2016年第1期5卷 19-30页

作者： delicia Acosta Elio E. Gonzo Hugo A. destéfanis Instituto de Investigaciones para la Industria Química—INIQUI-CONICET ANPCyT Consejo de Investigaciones— CIUNSa Facultad de Ingeniería—UNSa Buenos Aires Argentina

Nickel borides doped with transition metal (Cr, Mn, Fe, Co, Cu, and Zn) MNiB, 4% w/w respect to Ni were prepared by chemical reduction of nickel and metallic salts in methanol solution with borane-tetrahydrofurane (BH3-THF) complex obtained in aprotic solvent (THF anhydrous). Different techniques were used to characterize these materials. The MNiB amorphous structure was verified by XRD. Thermal treatment in N2 shows Ni°, Ni2 Band NiO phases. Spongy-morphology was evident by SEM studies in all cases. XPS and TEM show that doped and non-doped nickel boride was present as Ni° in metallic state as principal phase and nickel alloying with boron was observed in minor quantities. The oxidation stability, magnetic susceptibility and catalytic effect are correlated with parameters of each dopant metal.

关键词： NiB Doped NiB Borane-Tetrahydrofurane Reduction Catalyst

Influence of three aphid species used as prey on some biological aspects of the predator <i>Eriopis connexa</i>

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Open Journal of Animal Sciences 2013年第3期3卷 193-199页

作者： William Duarte Helber Arévalo Ingeborg Zenner de Polanía facultad de ingeniería Agronómica Universidad de Ciencias Aplicadas y Ambientales U.D.C.A. Bogotá D.C. Colombia

Up to now, the search for an efficient artificial diet to rear the predator Eriopis connexa, native to the Colombian highlands of Cundinamarca and Boyacá has been without success. Therefore, it is necessary to determine which of the available preys supply the best food for its development, survival and fertility. With this purpose, under controlled conditions, three aphid species, accessible within the natural habitat of the predator, were evaluated. The cabbage aphid (Brevicoryne brassicae) does not provide an adequate nutrition for the predator, and apparently, the glucosinolate content of this aphid is transferred and affecting the predator. Based on the demographic parameters such as net reproductive rate, finite reproduction rate, generational time and intrinsic growth rate, for three consecutive generations, it was determined that none of the other two aphid species can be considered either as optimum prey. Macrosiphum euphorbiae, as prey stands out over the alder aphid, Pterocallis sp., supplied as food. The influence that these three prey species had on the growth potential of the larval stages of the predator, under particular ambient conditions, is reported.

关键词： Predator Rearing Brevycoryne brassicae Macrosiphum Pterocallis sp. The Alder Aphid Glucosinolates

A Simple Two-Phase System Involving the Commercial Organophosphorous Extractant Cyanex 471x for the Preparation of Silver Sulphide Nanoparticles

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Materials Sciences and Applications 2012年第12期3卷 843-850页

作者： Rosa Lina Tovar-Tovar Octavio Domínguez-Espinós Adriana Gaona-Couto Azdrubal Lobo-Guerrero Salvador Palomares-Sánchez María Guadalupe Sánchez-Loredo Instituto de Metalurgia San Luis PotosíMéxico facultad de Ciencias San Luis PotosíMéxico facultad de ingeniería Univer-sidad Autónoma de San Luis PotosíSan Luis PotosíMéxico

The facile chemical synthesis of silver sulphide nanocrystals from metal-loaded organic media, containing a silver-selective organophosphorous ligand as extractant, is reported. The method involves the phase-transfer of silver species from aqueous nitrate media to organic solution using the commercial extractant Cyanex? 471x (tri-isobutylphosphine sulphide, Cytec Co.) as extractant, followed by precipitation stripping using ammonium sulphide as strip reagent. The nanoparticles were structurally characterized, and some aspects of the synthetical process, are briefly discussed. Under the conditions studied, the extractant Cyanex? 471x was able to act as stabilizer adsorbing on the particles surface, maintaining the size of the particles nanometrical.

关键词： Silver Sulphide Solvent Extraction Precipitation Stripping Cyanex 471x Tri-Isobutylphosphine Sulphide