Gotowa bibliografia na temat „Mobile nanoparticles”

The polymers can be either dynamically tethered to or permanently grafted to the nanoparticle to produce polymer-functionalized nanoparticles. The surface mobility of polymer ligands with one end anchored to the nanoparticle can affect the surface pattern, but the effect remains unclear. Here, we addressed the influence of lateral polymer mobility on surface patterns by performing self-consistent field theory calculations on a modeled polymer-functionalized nanoparticle consisting of immobile and mobile brushes. The results show that except for the radius of nanoparticles and grafting density, the fraction of mobile brushes substantially influences the surface patterning of polymer-functionalized nanoparticles, including striped patterns and patchy patterns with various patches. The number of patches on a nanoparticle increases as the fraction of mobile brushes decreases, favored by the entropy of immobile brushes. Critically, we found that broken symmetry usually occurs in patchy nanoparticles, associated with the balance of enthalpic and entropic effects. The present work provides a fundamental understanding of the dependence of surface patterning on lateral polymer mobility. The work could also guide the preparation of diversified nanopatterns, especially for the asymmetric patchy nanoparticles, enabling the fundamental investigation of the interaction between polymer-functionalized nanoparticles.

Ethylene can be synthesized in a renewable manner by dehydrating bioethanol over supported metal oxide nanoparticle catalysts. Here, a series of nanoparticulate tungsten oxides supported on MFI (Mobil five) zeolite nanosheets was prepared at different W loadings (1 to 6 mol %) using the incipient wetness method and investigated with respect to the ability to catalyze the dehydration of ethanol. The resulting samples were characterized by X-ray diffraction, electron microscopy, N2 isotherms, X-ray absorption fine structures, and by the temperature-programmed desorption of NH3. The results obtained showed that WOx nanoparticles were homogeneously distributed over the entire void space of nanosheet samples up to a loading of 2 mol %, after which large WOx nanoparticles with needle-like morphology were formed on the surface of the zeolite nanosheet beyond 2mol%. The number of acid sites increased with WOx loading and, as a result, EtOH conversion progressively increased with WOx loading up to 6 mol %. At reaction temperatures of >390 °C, homogeneously distributed WOx nanoparticles showed slightly higher ethylene selectivity than nano-needle structured WOx. However, nano-needle structured WOx exhibited greater catalytic stability. In terms of ethylene yield over 8 h, needle-like WOx nanoparticles were found to be more suitable for the acid-catalyzed dehydration of ethanol than small-sized WOx nanoparticles.

The thermodynamic study of the particle consolidation process in a system consisting of nanoparticles, inclusions of macroparticles, and mobile phase (gas, vapor, liquid) has been conducted. The thermodynamic functions describing this process have been derived. The conditions have been established, under which the process of consolidation proceeds to the end; the conditions, under which the process does not take place in terms of thermodynamics; and the conditions, under which only certain phases consolidate. It has been shown that in this system there are diffusion flows of the substance from nanoparticles to the macrophase. The conditions have been defined, under which a nanoparticle or a group of nanoparticles can be in an equilibrium state and maintain the size and shape arbitrarily long.

A reversed-phase high-performance liquid chromatographic method has been developed to quantitatively determine matrine in liquid crystal nanoparticles. The chromatographic method is carried out using an isocratic system. The mobile phase was composed of methanol-PBS(pH6.8)-triethylamine (50 : 50 : 0.1%) with a flow rate of 1 mL/min with SPD-20A UV/vis detector and the detection wavelength was at 220 nm. The linearity of matrine is in the range of 1.6 to 200.0 μg/mL. The regression equation isy=10706x-2959(R2=1.0). The average recovery is 101.7%;RSD=2.22% (n=9). This method provides a simple and accurate strategy to determine matrine in liquid crystalline nanoparticle.

Arrow root is a tropical root crop cultivated for its starchy rhizomes that have carbohydrate contents. Zinc oxide nanoparticles have emerged a promising potential in biomedicine, especially in the fields of anticancer, wound healing, free radical scavenging and antimicrobial including antibacterial, antifungal and antiviral research fields, which might be worried with their potent ability to trigger extra reactive oxygen species (ROS) production, launch zinc ions, and induce mobile apoptosis. 1 gram of Arrow root powder extract was mixed with 100 mL of water and filtered for nanoparticles synthesis. The zinc sulphate was used as a precursor for the zinc oxide nanoparticles synthesis and 30 mM was used. 50 mL of freshly prepared root extract and zinc sulphate solution was added together for the synthesis of Zinc oxide nanoparticles, which was then dried and characterisedcharacterized using transmission electron microscope (TEM) and during reaction it was characterized using UVvis spectroscopy method. A spherical shaped nanoparticle with plant extract in the background was observed. The peak at 300 nm confirm the nanoparticles synthesis using root extract. Based on our results we confirmed the capability of arrow root for the zinc oxide nanoparticles synthesis and it will be used for the various biomedical application in future.

ChemEx is a mobile application that is created to assist students in performing chemical experiments. Students who study Bachelor of Electronic Engineering majoring in Nanotechnology use chemical experiment to synthesise nanoparticles. Through observation, they lack of confidence during the nanoparticles synthesis because they were not involved in any chemistry activities after foundation. To overcome this issue, a mobile application called ChemEx is created using Android Studio. In ChemEx, the usage of apparatuses and instruments, lab safety, the concept molarity and dilution, as well as the data of chemicals are introduced. Pre and post-test are used to evaluate the effectiveness of ChemEx in helping the students. Besides this, feedback form is used to evaluate the satisfaction of students after using ChemEx. The pre and post-test results show that the students have improved their understanding in apparatuses, safety, molarity and dilution. In the meantime, feedbacks show students are satisfied using ChemEx.

La production d'énergie nucléaire nécessite des systèmes avancés pour améliorer les procédures de stockage et de confinement des déchets radioactifs. Par ailleurs, la capture d'éléments radioactifs mobiles dans les effluents des centrales nucléaires demande une amélioration de la capacité et de la sélectivité. L'iode 129-I est un des produits les plus critiques à confiner et il est produit pendant les procédés de recyclage des déchets nucléaires. Dans ce travail de thèse, la classe de matériaux moléculaires, dénommée structures de type Hofmann, a été étudiée en tant que matériaux massifs et nanoparticules supportées pour la capture sélective de l'iode moléculaire. En premier lieu, les matériaux M'(L)[M''(CN)4] ont été précipités sous la forme de poudres microcristallines. L'insertion d'iode dans le réseau des matériaux massifs a été effectuée par différents protocoles: 1) adsorption d'iode dans des solutions de cyclohexane à température ambiante; 2) adsorption d'iode en phase gazeuse à 80 °C; 3) adsorption de vapeurs d'iode en phase gazeuse à 80 °C et en présence de vapeurs d'eau. Les différents protocoles pour l'insertion d'iode n'ont pas influencé la nature de l'iode confiné. Pour la capture en solution, les structures NiII(pz)[NiII(CN)4], NiII(pz)[PdII(CN)4] et CoII(pz)[NiII(CN)4] ont montré une capacité d'une molécule d'iode par unité de maille. L'iode confiné est physisorbé en tant qu'iode moléculaire en interaction avec le réseau. Les modélisations GCMC ont confirmé la capacité maximale et ils ont indiqué que l'iode interagit avec la pyrazine et avec les cyanures. Sur la base des données expérimentales, la modulation des métaux dans le réseau a montré une légère différence dans la force d'interaction entre l'iode et le réseau et une adaptation de la maille spécifique pour chaque composition. Une complète régénération du réseau a été possible, puisque l'iode était complètement désorbé avant la décomposition du réseau. Pour le réseau NiII(pz)[PtII(CN)4], on a observé un mécanisme différent de capture puisque ce réseau contenant Pt a réagi avec l'iode en donnant le complexe de coordination NiII(pz)[PtII/IV(CN)4].I-. La formation de ce type de complexe était déjà observée dans la littérature par Ohtani et al. lesquels avaient préparé le complexe via une synthèse in-situ. Ensuite, le changement du ligand organique pyrazine avec d'autres ligands plus longs, c'est-à-dire la 4,4'-bipyridine (bpy) ou 4,4'-azopyridine (azpy), pour avoir des cages plus grandes a montré une diminution de la capacité maximale de capture d'iode. Les données expérimentales ont suggéré que pour un confinement d'iode optimisé, le réseau doit disposer de cages avec une dimension très proche de la molécule d'iode (0.5 nm). Après l'étude des matériaux massifs, nous avons considéré la préparation de nanoparticules supportées de NiII(pz)[NiII(CN)4] pour la capture d'iode. Nous avons obtenu les nanoparticules via un procédé étape par étape, par imprégnation d'une série de silices mésoporeuses greffées avec un ligand diamine, puis avec les précurseurs de NiII(pz)[NiII(CN)4]. Nous avons utilisé en tant que supports, une silice SBA-15 modifiée et des billes de verre poreux pour obtenir respectivement les nanocomposites Sil@NP and Glass@NP. Par microscopie électronique à transmission, nous avons détecté pour Sil@NP des nanoparticules de diamètre moyen 2.8 nm. L'adsorption d'iode dans les nanoparticules a été confirmée par spectroscopie FT-IR. Les traitements thermiques ont indiqué que la portion d'iode dans les nanoparticules pouvait être désorbé dans l'intervalle 150-250 °C. Nous avons pu estimer que la capacité de capture des nanoparticles était très proche de la capacité du massif NiII(pz)[NiII(CN)4]@I2
Nuclear power industry still demands further research to improve the methods for the storage and the confinement of the hazardous radioactive wastes coming from the fission of radionuclide 235U. The volatile radioactive 129I (half-life time 15x107 years) is one of the most critical products coming from the reprocessing plants in the fuel-closed cycles. In the present thesis the family of coordination solid networks, known as Hofmann-type structures, was studied in the form as both bulk and supported nanoparticles for the selective entrapment of the molecular iodine. This set of investigated materials exhibited a general formula M'(L)[M''(CN)4] where M' = NiII or CoII; L = pyrazine, 4,4'-bipyridine, 4,4'-azopyridine; M'' = NiII, PdII or PtII. Initially, the material NiII(pz)[NiII(CN)4] and its analogue structures were precipitated as microcrystalline bulky compounds and fully characterized. The insertion of the iodine in the bulky host structures was performed with different methods: 1) adsorption of iodine in solutions of cyclohexane at room temperature; 2) adsorption of iodine vapours at 80 °C; 3) adsorption of iodine vapours at 80 °C in presence of water steam (for few selected materials). The different methods did not affect the nature of the confined iodine. For the entrapment in solution, results indicated that the Hofmann-type structures NiII(pz)[NiII(CN)4], NiII(pz)[PdII(CN)4] and CoII(pz)[NiII(CN)4] could host one I2 molecule per unit cell. The iodine resulted physisorbed as molecular iodine in interaction with the host structure. GCMC simulations confirmed the maximal capacities and indicated that iodine could interact with both the pyrazine and the coordinated cyanides. Experimentally, however, the modulation of the metals showed a slightly different strength of interaction I2-lattice bringing to a different lattice adaptation. The materials also could be fully regenerated since the complete desorption of iodine occurred before the decomposition of the host structure. Reiterated adsorption-desorption steps (3 cycles) on the networks NiII(pz)[NiII(CN)4] and NiII(pz)[PdII(CN)4] indicated an excellent structural resistance to cycling and a maintained high capacity. A different mechanism of confinement was detected for the structure NiII(pz)[PtII(CN)4] which reacted with iodine giving complex NiII(pz)[PtII/IV(CN)4].I-. Finally, the modulation of the organic ligand L indicated that the replacement of the ligand pyrazine with longer ligands, to obtain larger pores, had a detrimental effect on the maximal iodine loading due to a weaker confinement. After the study of the bulk materials, we considered the preparation of supported nanoparticles of NiII(pz)[NiII(CN)4] for the entrapment of iodine. The nanoparticles were obtained by a step-by-step method, impregnating a set of diammine-grafted mesoporous silicas with the precursors of NiII(pz)[NiII(CN)4]. We detected nanoparticles with mean size 2.8 nm by transmission electronic microscopy. The insertion of iodine in the nanoparticles was confirmed by FT-IR. Thermal treatments indicated that the portion of iodine inside the nanoparticles could be reversibly desorbed in the range 150-250 °C and reintroduced in a cyclic process. It was estimated that the amount of physisorbed iodine in the NPs, with respect to the amount of deposited NPs matched with the maximal capacity NiII(pz)[NiII(CN)4]@I2

L'industrie nucléaire produit, de nos jours, une large gamme d'effluents radioactifs liquides contenant du césium. Les matériaux à base de cyanométallates présentent une très forte affinité pour l'incorporation de cet élément sur une grande plage de pH ainsi qu'une bonne résistance à l'irradiation ce qui les rend très intéressant pour la décontamination. Chaque année, à La Hague, plusieurs centaines de m3 d'effluents radioactifs sont traités par un précipité préformé de ferrocyanure de nickel massif (nommé PPFeNi, de formule générale K2xNi2-x[Fe(CN)6] avec 0,5>x>1,1). Cette technique présente de bons rendements de décontamination mais elle est lourde à mettre en œuvre et produit une boue qui se doit ensuite d'être traitée par les filières de déchets disponibles. L'objet de cette thèse est de trouver un matériau pour la décontamination du Cs à la fois efficace, sélectif, adapté au procédé de décontamination en continu (colonne) et compatible avec les déchets classiques (ciments ou verres). Pour atteindre ce but, nous avons plusieurs objectifs :i) L'étude de matériaux massif à base de cyanométallate afin d'améliorer les connaissances sur le mécanisme de fixation du césium sur ces composés en variant la nature du métal de transition et la présence ou non de potassium au sein de la structure cristalline,ii) La synthèse de nanocomposites contenant des nanoparticules de cyanométallates incorporées dans des matrices inorganiques de type silice mésostructurée et verre poreux. La silice est utilisée comme modèle, alors que le verre poreux mise en forme de bille sera utilisé en vue d'un procédé de décontamination. Les matériaux massifs à base de cyanométallate contenant du potassium dans la structure sont ceux qui possèdent la plus grande capacité de sorption vis-à-vis du Cs. Les matériaux hybrides contenant des nanoparticules de cyanométallates possèdent une capacité maximale absolue inférieure à celle des matériaux massifs respectifs, cependant rapporté à la quantité de particule sorbante, la capacité maximale de sorption des matériaux hybrides est supérieure à celle des massifs. En revanche, la sélectivité est comparable pour les matériaux hybrides et les matériaux massifs, avec un coefficient de distribution de l'ordre de 104 à 105 mL.g-1.Les performances des matériaux hybrides ont été évaluées sur des effluents réels. Ces matériaux semblent très prometteurs pour la décontamination d'effluents à partir d'un procédé de traitement en colonne puisqu'ils présentent d'une part une forte sélectivité vis-à-vis du césium et ce malgré une forte salinité de la solution à décontaminer et d'autre part une mise en forme (bille de verre) adaptée à ce type de procédé
Nuclear industry produced, nowadays, a wide range of liquid radioactive waste containing cesium. Materials based on cyanométallates exhibit a very high affinity for the inclusion of this element in a wide range of pH and a good resistance to ionising radiation which makes them very interesting for decontamination. Every year, at La Hague, several hundred m3 of radioactive waste are treated by a nickel ferrocyanide preformed precipitate in bulk form (PPFeNi, general formula K2xNi2-x [Fe (CN) 6] with 0,5> x> 1,1). This process shows a good decontamination but it's difficult to implement and it produces a sludge that must then be treated by waste channel available.The purpose of this thesis is to find a material for the decontamination of Cs which have a good capacity, selectivity, adapted for continuous decontamination process (column) and compatible with conventional waste (cement or glass). To achieve this goal, we have several objectives:i) The study of solid materials based on cyanometallate to improve knowledge on the mechanism of fixation of cesium on these compounds by varying the nature of transition metal and the presence or not of potassium in the crystal structure,ii) Synthesis of nanocomposites containing cyanometallate nanoparticles incorporated into inorganic matrices which are mesostructured silica and porous glass. Silica is used as a template, whereas the porous glass shaping ball will be used for a decontamination process.Bulk materials containing potassium in the structure present the greater sorption capacity toward Cs. Hybrid materials containing cyanometallate nanoparticles have a lesser absolute capacity than the respective bulk materials, however, based on the amount of sorbent particles, the maximum sorption capacity of hybrid materials is higher than bulk materials. However, the selectivity is comparable for hybrid and bulk materials with a distribution coefficient about 104 to 105 mL.g-1.The performance of the hybrid materials were evaluated on real effluents. These materials are very promising for the decontamination of effluents from a treatment process in column one hand they have a high selectivity towards cesium and despite high salinity of the solution to decontaminate and other formatting (glass beads) adapted to this type of process

Rare earth elements (REE) have applications in various modern technologies, e.g., semiconductors, mobile phones, magnets. They are categorized as critical raw materials due to their strategic importance in economies and high risks associated with their supply chain. Therefore, more sustainable practices for efficient extraction and recovery of REE from secondary sources are being developed. This book, Environmental Technologies to Treat Rare Earth Elements Pollution: Principles and Engineering: presents the fundamentals of the (bio)geochemical cycles of rare earth elements and which imbalances in these cycles result in pollution.overviews physical, chemical and biological technologies for successful treatment of water, air, soils and sediments contaminated with different rare earth elements.explores the recovery of value-added products from waste streams laden with rare earth elements, including nanoparticles and quantum dots. This book is suited for teaching and research purposes as well as professional reference for those working on rare earth elements. In addition, the information provided in this book is helpful to scientists, researchers and practitioners in related fields, such as those working on metal/metalloid microbe interaction and sustainable green approaches for resource recovery from wastes. ISBN: 9781789062229 (Paperback) ISBN: 9781789062236 (eBook) ISBN: 9781789062243 (ePUB)

The Ag nanoparticles with no need for reduction supported on MgAl-layered double hydroxide (LDH) were prepared. Ag nanoparticles (NPs) were achieved in the LDH support by in situ reduction, meanwhile, metal nickel generated by the reaction mechanisms of hydrogenation of citral. Sliver generates highly mobile atomic hydrogen, which reduces nickel by abstracting H from the surface support, and nickel nanoparticles formed after reaction. The action of sliver and nickelare conducive to higher selectivity to unsaturated aldehyde in Ag-[Ni(OH)2]X/LDH. The effects of support and sliver were explained by TEM, SEM, XRD and H2-TPR.

The heavy metal pollution problem is all over the world. Plant-growth-promoting bacteria (PGPB) has transformed heavy metals present in the soil, which removes and minimizes their toxic effects. This chapter highlights the role of plant-growth-promoting bacteria, chelating agents, and nanoparticles for remediation of heavy metals; their mechanism of action; and their applications approach of hyperaccumulation. Therefore, this chapter focuses on the mechanisms by which microorganisms, chelating agents, and nanoparticles can mobilize or immobilize metals in soils and the nano-phytoremediation strategies are addressed for the improvement of phytoextraction as an innovative process for enhancement of heavy metals removal from soil.

The heavy metal pollution problem is all over the world. Plant-growth-promoting bacteria (PGPB) has transformed heavy metals present in the soil, which removes and minimizes their toxic effects. This chapter highlights the role of plant-growth-promoting bacteria, chelating agents, and nanoparticles for remediation of heavy metals; their mechanism of action; and their applications approach of hyperaccumulation. Therefore, this chapter focuses on the mechanisms by which microorganisms, chelating agents, and nanoparticles can mobilize or immobilize metals in soils and the nano-phytoremediation strategies are addressed for the improvement of phytoextraction as an innovative process for enhancement of heavy metals removal from soil.

Both, singlet and excimer exciton diffusion are demonstrated in Perylene Orange nanoparticles by transient absorption spectroscopy. Excimer-excitons in particles with strong intermolecular coupling are even more mobile than singlet excitons of particles with weak coupling.

In this work we investigate the use of NiCo bimetal/oxide as catalyst for hydrogen production from ethanol, with a focus on the deactivation pattern and the nature of the observed carbon deposition. It is well known that sintering and coke deposition during decomposition reaction significantly reduces the activity of the catalysts at higher temperature, by blocking the active sites of the catalysts. During ethanol decomposition reaction, the cleavage of C-C bond produces adsorbed *CH4 and *CO species that further decompose to form carbonaceous compounds. FTIR in-situ analysis was conducted between 50 to 400°C for all the catalysts to understand the reaction mechanism and product selectivity. Cobalt was found to be selective for aldehyde and acetate, whereas bimetallic Ni-Co was selective for the formation of CO at 400°C along with aldehyde. Complete conversion of ethanol was observed at 350°C and 420°C for NiCo and Cobalt respectively indicating an improvement in the rate of conversion when Ni was added to cobalt. The crystallinity, morphology and particle analysis of the used catalyst after reaction were studied using XRD, SEM and TEM respectively. The XRD shows the complete phase change of porous NiCoO2 to NiCo alloy and SEM indicates the presence of fibrous structure on the surface with 91.7 % of carbon while keeping 1:1 ratio of Ni and Co after the reaction. The detailed analysis of carbon structure using HRTEM-STEM shows the simultaneous growth of carbon nano fibers (CNFs) and multiwalled carbon nanotubes (MWCNTs) that were favored on larger and smaller crystallites respectively. Analysis of carbon formation on individual Co catalyst and bimetallic NiCo catalyst shows a clear difference in the initiation pattern of carbon deposition. Metallic Co nanoparticles were found to be more mobile where Co disperses along the catalysts surface, whereas NiCo nanoparticles were relatively less mobile, and maintained their structure.

Powering small electronics like mobile devices off-grid has remained a challenge; hence, there exists a need for an alternate source of powering these devices. This paper examines the efficacy of a novel nanoparticle-immobilized polyethylene wick in maintaining sufficient thermal gradient across a thermoelectric generator to power these devices with energy from waste heat. The work examines several other heat exchangers including heat pipes and loop heat pipe setups. The experimental evidence reveals that the nanoparticle-immobilized polyethylene wick is capable of generating sufficient thermal potential resulting in 5V, which is the minimum voltage required to power small mobile devices. In the opinion of the authors, this is the first ever recorded account of utilizing waste heat to generate enough voltage to power a mobile device. Experiment demonstrated that the nanoparticle-immobilized polyethylene wick showed over 40% thermoelectric voltage generation increment over a plain polyethylene wick and a metal wick in a loop heat pipe setup.

The size of combustion generated particles ranges from a few nanometers up to 1 micron, whereas the size of naturally occurring PM such as pollens, plant fragments, and sea salt is generally larger than 1 micron. Particles generated by photochemical processes in the atmosphere are generally smaller than 1 micron. Ultrafine particles (UFP), also called “nanoparticles”, are <0.1 micron and in recent yearshave attracted attention due to potential adverse health effects associated with them. The contribution of UFP to the total PM mass is very small. However, they dominate the total number of particles in urban aerosols. Their sources are both mobile and stationary combustion sources and also gas-to-particle conversions. In coal and waste combustion systems, UFP are hypothesized to be generated mainly by nucleation of metal vapors. Coal naturally contains a vast range of inorganic elements among which are heavy metals. Sources of heavy metals in MSW include batteries, electronic devices, light bulbs, house dust and paint chips, food containers, used motor oils, plastics, yard wastes and some papers. The input of these metals into WTE facilities can be controlled by better source-separation of metal-containing materials. In 2007 almost 50% of the approximately 4.16 billion MWh generated in the United States was produced by coal power plants whereas only 0.3% was generated by the WTE industry. A preliminary study has shown that in terms of contribution to UHF in the atmosphere, MSW combustion has a minor effect in comparison to coal-fired power plants in the U.S. This paper will report on the results of this investigation.