Letteratura scientifica selezionata sul tema "Nanoparticle beams"
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Articoli di riviste sul tema "Nanoparticle beams":
1
Gagliardi, Frank M., Rick D. Franich e Moshi Geso. "Nanoparticle dose enhancement of synchrotron radiation in PRESAGE dosimeters". Journal of Synchrotron Radiation 27, n. 6 (23 ottobre 2020): 1590–600. http://dx.doi.org/10.1107/s1600577520012849.
Abstract (sommario):
The physical absorbed dose enhancement by the inclusion of gold and bismuth nanoparticles fabricated into water-equivalent PRESAGE dosimeters was investigated. Nanoparticle-loaded water-equivalent PRESAGE dosimeters were irradiated with superficial, synchrotron and megavoltage X-ray beams. The change in optical density of the dosimeters was measured using UV–Vis spectrophotometry pre- and post-irradiation using a wavelength of 630 nm. Dose enhancement was measured for 5 nm and 50 nm monodispersed gold nanoparticles, 5–50 nm polydispersed bismuth nanoparticles, and 80 nm monodispersed bismuth nanoparticles at concentrations from 0.25 mM to 2 mM. The dose enhancement was highest for the 95.3 keV mean energy synchrotron beam (16–32%) followed by the 150 kVp superficial beam (12–21%) then the 6 MV beam (2–5%). The bismuth nanoparticle-loaded dosimeters produced a larger dose enhancement than the gold nanoparticle-loaded dosimeters in the synchrotron beam for the same concentration. For the superficial and megavoltage beams the dose enhancement was similar for both species of nanoparticles. The dose enhancement increased with nanoparticle concentration in the dosimeters; however, there was no observed nanoparticle size dependence on the dose enhancement.
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Martelli, Stefano, e James C. L. Chow. "Dose Enhancement for the Flattening-Filter-Free and Flattening-Filter Photon Beams in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study". Nanomaterials 10, n. 4 (29 marzo 2020): 637. http://dx.doi.org/10.3390/nano10040637.
Abstract (sommario):
Monte Carlo simulations were used to predict the dose enhancement ratio (DER) using the flattening-filter-free (FFF) and flattening-filter (FF) photon beams in prostate nanoparticle-enhanced radiotherapy, with multiple variables such as nanoparticle material, nanoparticle concentration, prostate size, pelvic size, and photon beam energy. A phantom mimicking the patient’s pelvis with various prostate and pelvic sizes was used. Macroscopic Monte Carlo simulation using the EGSnrc code was used to predict the dose at the prostate or target using the 6 MV FFF, 6 MV FF, 10 MV FFF, and 10 MV FF photon beams produced by a Varian TrueBeam linear accelerator (Varian Medical System, Palo Alto, CA, USA). Nanoparticle materials of gold, platinum, iodine, silver, and iron oxide with concentration varying in the range of 3–40 mg/ml were used in simulations. Moreover, the prostate and pelvic size were varied from 2.5 to 5.5 cm and 20 to 30 cm, respectively. The DER was defined as the ratio of the target dose with nanoparticle addition to the target dose without nanoparticle addition in the simulation. From the Monte Carlo results of DER, the best nanoparticle material with the highest DER was gold, based on all the nanoparticle concentrations and photon beams. Smaller prostate size, smaller pelvic size, and a higher nanoparticle concentration showed better DER results. When comparing energies, the 6 MV beams always had the greater enhancement ratio. In addition, the FFF photon beams always had a better DER when compared to the FF beams. It is concluded that gold nanoparticles were the most effective material in nanoparticle-enhanced radiotherapy. Moreover, lower photon beam energy (6 MV), FFF photon beam, higher nanoparticle concentration, smaller pelvic size, and smaller prostate size would all increase the DER in prostate nanoparticle-enhanced radiotherapy.
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Abdulle, Aniza, e James C. L. Chow. "Contrast Enhancement for Portal Imaging in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Evaluation Using Flattening-Filter-Free Photon Beams". Nanomaterials 9, n. 7 (26 giugno 2019): 920. http://dx.doi.org/10.3390/nano9070920.
Abstract (sommario):
Our team evaluated contrast enhancement for portal imaging using Monte Carlo simulation in nanoparticle-enhanced radiotherapy. Dependencies of percentage contrast enhancement on flattening-filter (FF) and flattening-filter-free (FFF) photon beams were determined by varying the nanoparticle material (gold, platinum, iodine, silver, iron oxide), nanoparticle concentration (3–40 mg/mL) and photon beam energy (6 and 10 MV). Phase-space files and energy spectra of the 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF photon beams were generated based on a Varian TrueBeam linear accelerator. We found that gold and platinum nanoparticles (NP) produced the highest contrast enhancement for portal imaging, compared to other NP with lower atomic numbers. The maximum percentage contrast enhancements for the gold and platinum NP were 18.9% and 18.5% with a concentration equal to 40 mg/mL. The contrast enhancement was also found to increase with the nanoparticle concentration. The maximum rate of increase of contrast enhancement for the gold NP was equal to 0.29%/mg/mL. Using the 6 MV photon beams, the maximum contrast enhancements for the gold NP were 79% (FF) and 78% (FFF) higher than those using the 10 MV beams. For the FFF beams, the maximum contrast enhancements for the gold NP were 53.6% (6 MV) and 53.8% (10 MV) higher than those using the FF beams. It is concluded that contrast enhancement for portal imaging can be increased when a higher atomic number of NP, higher nanoparticle concentration, lower photon beam energy and no flattening filter of photon beam are used in nanoparticle-enhanced radiotherapy.
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Chow, James C. L., e Sama Jubran. "Depth Dose Enhancement in Orthovoltage Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study". Micromachines 14, n. 6 (10 giugno 2023): 1230. http://dx.doi.org/10.3390/mi14061230.
Abstract (sommario):
Background: This study was to examine the depth dose enhancement in orthovoltage nanoparticle-enhanced radiotherapy for skin treatment by investigating the impact of various photon beam energies, nanoparticle materials, and nanoparticle concentrations. Methods: A water phantom was utilized, and different nanoparticle materials (gold, platinum, iodine, silver, iron oxide) were added to determine the depth doses through Monte Carlo simulation. The clinical 105 kVp and 220 kVp photon beams were used to compute the depth doses of the phantom at different nanoparticle concentrations (ranging from 3 mg/mL to 40 mg/mL). The dose enhancement ratio (DER), which represents the ratio of the dose with nanoparticles to the dose without nanoparticles at the same depth in the phantom, was calculated to determine the dose enhancement. Results: The study found that gold nanoparticles outperformed the other nanoparticle materials, with a maximum DER value of 3.77 at a concentration of 40 mg/mL. Iron oxide nanoparticles exhibited the lowest DER value, equal to 1, when compared to other nanoparticles. Additionally, the DER value increased with higher nanoparticle concentrations and lower photon beam energy. Conclusions: It is concluded in this study that gold nanoparticles are the most effective in enhancing the depth dose in orthovoltage nanoparticle-enhanced skin therapy. Furthermore, the results suggest that increasing nanoparticle concentration and decreasing photon beam energy lead to increased dose enhancement.
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Rasoolpoor, M., R. Ansari e MK Hassanzadeh-Aghdam. "Multiscale analysis of the low-velocity impact behavior of ceramic nanoparticle-reinforced metal matrix nanocomposite beams by micromechanics and finite element approaches". Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, n. 12 (15 luglio 2019): 2419–32. http://dx.doi.org/10.1177/1464420719861993.
Abstract (sommario):
An efficient multiscale analysis is proposed to investigate the dynamic behavior of metal matrix nanocomposite beams reinforced by SiC nanoparticles under low-velocity impact loads. First, an analytical micromechanics model is developed to obtain the effective elastic properties of ceramic nanoparticle-reinforced metal matrix nanocomposite, and then the finite element method is used to predict the dynamic response of beams made of this nanocomposite material. Two important microstructural features, including size effect and agglomeration of nanoscale particles, are incorporated into the micromechanical analysis. The present simulation results for the elastic modulus and low-velocity impact response show good agreement with previously published results. The effects of volume percent, diameter and dispersion type of ceramic nanoparticles, geometrical features and boundary conditions of nanostructure, velocity and size of projectile on the contact force, and center deflection time histories of metal matrix nanocomposite beams are extensively examined. Analysis shows that homogenously distributed SiC nanoparticles into the metal matrix nanocomposites can obviously increase the nanostructure/projectile contact force and decrease both the beam center deflection and impact duration which is due to the enhancement of elastic properties. However, the ceramic nanoparticle agglomeration has an effect on the decrease of contact force and the increase of both the center deflection and impact duration. Also, it is concluded that decreasing nanoparticle size can increase the contact force and decrease the beam center deflection.
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Huynh, Ngoc Han, e James C. L. Chow. "DNA Dosimetry with Gold Nanoparticle Irradiated by Proton Beams: A Monte Carlo Study on Dose Enhancement". Applied Sciences 11, n. 22 (17 novembre 2021): 10856. http://dx.doi.org/10.3390/app112210856.
Abstract (sommario):
Heavy atom nanoparticles, such as gold nanoparticles, are proven effective radiosensitizers in radiotherapy to enhance the dose delivery for cancer treatment. This study investigated the effectiveness of cancer cell killing, involving gold nanoparticle in proton radiation, by changing the nanoparticle size, proton beam energy, and distance between the nanoparticle and DNA. Monte Carlo (MC) simulation (Geant4-DNA code) was used to determine the dose enhancement in terms of dose enhancement ratio (DER), when a gold nanoparticle is present with the DNA. With varying nanoparticle size (radius = 15–50 nm), distance between the gold nanoparticle and DNA (30–130 nm), as well as proton beam energy (0.5–25 MeV) based on the simulation model, our results showed that the DER value increases with a decrease of distance between the gold nanoparticle and DNA and a decrease of proton beam energy. The maximum DER (1.83) is achieved with a 25 nm-radius gold nanoparticle, irradiated by a 0.5 MeV proton beam and 30 nm away from the DNA.
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Gatsa, Oleksandr, Shabbir Tahir, Miroslava Flimelová, Farbod Riahi, Carlos Doñate-Buendia, Bilal Gökce e Alexander V. Bulgakov. "Unveiling Fundamentals of Multi-Beam Pulsed Laser Ablation in Liquids toward Scaling up Nanoparticle Production". Nanomaterials 14, n. 4 (16 febbraio 2024): 365. http://dx.doi.org/10.3390/nano14040365.
Abstract (sommario):
Pulsed laser ablation in liquids (PLAL) is a versatile technique to produce high-purity colloidal nanoparticles. Despite considerable recent progress in increasing the productivity of the technique, there is still significant demand for a practical, cost-effective method for upscaling PLAL synthesis. Here we employ and unveil the fundamentals of multi-beam (MB) PLAL. The MB-PLAL upscaling approach can bypass the cavitation bubble, the main limiting factor of PLAL efficiency, by splitting the laser beam into several beams using static diffractive optical elements (DOEs). A multimetallic high-entropy alloy CrFeCoNiMn was used as a model material and the productivity of its nanoparticles in the MB-PLAL setup was investigated and compared with that in the standard single-beam PLAL. We demonstrate that the proposed multi-beam method helps to bypass the cavitation bubble both temporally (lower pulse repetition rates can be used while keeping the optimum processing fluence) and spatially (lower beam scanning speeds are needed) and thus dramatically increases the nanoparticle yield. Time-resolved imaging of the cavitation bubble was performed to correlate the observed production efficiencies with the bubble bypassing. The results suggest that nanoparticle PLAL productivity at the level of g/h can be achieved by the proposed multi-beam strategy using compact kW-class lasers and simple inexpensive scanning systems.
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Fang, Jingyue, Xinxing Li, Wenke Xie e Kehui Sun. "A Novel Fabrication of Single Electron Transistor from Patterned Gold Nanoparticle Array Template-Prepared by Polystyrene Nanospheres". Nanomaterials 12, n. 18 (7 settembre 2022): 3102. http://dx.doi.org/10.3390/nano12183102.
Abstract (sommario):
In this paper, polystyrene microspheres were firstly prepared by seeded emulsion polymerization, and the uniform monolayer of polystyrene microspheres was prepared on the substrate by the dipping method. Then, polystyrene monolayer film was used as a mask and a low dimensional array structure of gold was prepared by bottom-up self-assembly process. After that, the method of solution etching and annealing was used, and the gold nanoparticle array was post-processed. As a result, gold nanoparticles were recrystallized, with an average diameter of about 50 nm. Subsequently, the semiconductor process was adopted, with focused ion beams induced deposition and electron beam evaporation, and single electron transistors were fabricated, based on self-assembled gold nanoparticles. Finally, the devices were fixed in a liquid helium cryostat and Coulomb blockade was observed at 320 mK. It is a novel fabrication of a single electron transistor based on gold nanoparticle array template and prepared with polystyrene nanospheres.
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Srinivasan, K., e E. James Jabaseelan Samuel. "Effective atomic number and photon buildup factor of bismuth doped tissue for photon and particles beam interaction". Polish Journal of Medical Physics and Engineering 28, n. 1 (1 marzo 2022): 37–51. http://dx.doi.org/10.2478/pjmpe-2022-0005.
Abstract (sommario):
Abstract Introduction: The doping of high Z nanoparticles into the tumor tissue increases the therapeutic efficiency of radiotherapy called nanoparticle enhanced radiotherapy (NERT). In the present study, we are identifying the effective types of radiation and effective doping concentration of bismuth radiosensitizer for NERT application by analyzing effective atomic number (Zeff) and photon buildup factor (PBF) of bismuth (Bi) doped soft tissue for the photon, electron, proton, alpha particle, and carbon ion interactions. Material and methods: The direct method was used for the calculation of Zeff for photon and electron beams (10 keV-30 MeV). The phy-X/ZeXTRa software was utilized for the particle beams such as proton, alpha particle, and carbon ions (1-15 MeV). Bismuth doping concentrations of 5, 10, 15, 20, 25 and 30 mg/g were considered. The PBF was calculated over 15 keV-15 MeV energies using phy-X/PSD software. Results: The low energy photon (<100 keV) interaction with a higher concentration of Bi dopped tissue gives the higher values of Zeff. The Zeff increased with the doping concentration of bismuth for all types of radiation. The Zeff was dependent on the type of radiation, the energy of radiation, and the concentration of Bi doping. The particle beams such as electron, proton, alpha particle, and carbon ion interaction gives the less values of Zeff has compared to photon beam interaction. On the other hand, the photon buildup factor values were decreased while increasing the Bi doping concentration. Conclusions: According to Zeff and PBF, the low energy photon and higher concentration of radiosensitizer are the most effective for nanoparticle enhanced radiotherapy application. Based on the calculated values of Zeff, the particle beams such as electron, proton, alpha particle, and carbon ions were less effective for NERT application. The presented values of Zeff and PBF are useful for the radiation dosimetry in NERT.
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Kawaguchi, Haruki, Kei Umesato, Kanta Takahashi, Keisaku Yamane, Ryuji Morita, Ken-ichi Yuyama, Satoyuki Kawano, Katsuhiko Miyamoto, Michinari Kohri e Takashige Omatsu. "Generation of hexagonal close-packed ring-shaped structures using an optical vortex". Nanophotonics 11, n. 4 (20 ottobre 2021): 855–64. http://dx.doi.org/10.1515/nanoph-2021-0437.
Abstract (sommario):
Abstract An optical vortex possesses a ring-shaped spatial profile and orbital angular momentum (OAM) owing to its helical wavefront. This form of structured light has garnered significant attention in recent years, and it has enabled new investigations in fundamental physics and applications. One such exciting application is laser-based material transfer for nano-/micro-fabrication. In this work, we demonstrate the application of a single-pulse optical vortex laser beam for direct printing of ring-shaped structures composed of hexagonal close-packed, mono-/multi-layered nanoparticles which exhibit ‘structural color’. We compare and contrast the interaction of the vortex beam with both dielectric and metallic nanoparticles and offer physical insight into how the OAM of vortex beams interacts with matter. The demonstrated technique holds promise for not only photonic-based nano-/micro-fabrication, but also as a means of sorting particles on the nanoscale, a technology which we term ‘optical vortex nanoparticle sorting’.
Tesi sul tema "Nanoparticle beams":
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Wan, Chenchen. "Optical Tweezers Using Cylindrical Vector Beams". University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1353515022.
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Bolsa, Ferruz Marta. "Oxygen effect in medical ion beam radiation combined with nanoparticles". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS476/document.
Abstract (sommario):
Environ 50% des patients recevant un traitement contre le cancer bénéficient de la radiothérapie. La radiothérapie conventionnelle consiste à utiliser des rayons X de haute énergie capables de traverser les tissus et de traiter des tumeurs situées en profondeur de façon non-invasive. Malheureusement, les rayons X ne font pas la distinction entre les tumeurs et les tissus sains, qui peuvent donc être endommagés. Cette non-sélectivité est à l’origine de graves effets secondaires, voire du développement de cancers secondaires. Par conséquent, l’amplification des effets radiatifs au sein de la tumeur par rapport aux tissus environnants représente un défi majeur.L’hadronthérapie (traitement par faisceaux de protons ou d’ions carbone) est considérée comme l’une des techniques les plus prometteuses car, contrairement aux rayons X, la quantité d’énergie déposée atteint son maximum en fin de trajectoire. Lorsque le faisceau est réglé de manière à ce que ce maximum atteigne la tumeur, aucun dommage n’est causé aux tissus situés au-delà. Un autre avantage majeur est que les ions lourds sont plus efficaces pour traiter les tumeurs radiorésistantes. L’utilisation de cette technique est cependant restreinte du fait des dommages – plus faibles mais néanmoins significatifs – causés aux tissus normaux situés sur la trajectoire du faisceau d’ions en amont de la tumeur. Afin d’améliorer les performances de l’hadronthérapie, l’équipe a développé à l’ISMO une nouvelle stratégie combinant l’utilisation de nanoparticules (NPs) métalliques avec l’irradiation par faisceaux d’ions. L’utilisation de NPs a pour but non seulement d’amplifier les effets des rayonnements dans la tumeur mais également d’améliorer l'imagerie médicale à l’aide des mêmes agents (théranostic). Les NPs possèdent une chimie de surface permettant leur fonctionnalisation avec des ligands capable d’améliorer la biocompatibilité, la stabilité ainsi que la circulation sanguine et l’accumulation dans la tumeur. L’équipe a déjà démontré que les petites NPs d’or et de platine (≈ 3 nm) avaient la capacité d’amplifier les effets causés par les faisceaux d’ions carbone médicaux en présence d’oxygène. Cependant, les tumeurs radiorésistantes sont susceptibles de contenir des régions hypoxiques. Il est donc urgent de quantifier et de caractériser l’influence de l’oxygène sur l’effet radio-amplificateur. Le but de ma thèse était d’étudier l’influence de l’oxygène lors d’irradiations par des faisceaux d’ions médicaux en présence de NPs d’or et de platine. Pour cela, deux lignes de cellules cancéreuses humaines radiorésistantes ont été testées: HeLa (col de l’utérus) et BxPC-3 (pancréas). Plusieurs techniques d’irradiation ont été utilisées : des faisceaux d’ions carbone et hélium générés par « passive scattering » et des faisceaux d’ions carbone générés par « pencil beam scanning ». Les principaux résultats de cette étude sont les suivants. En condition oxique (concentration d’O₂ = 20%), une amplification des effets radiatifs a été observée pour les deux types de NPs (à concentration de métal égale). Ce phénomène se réduit à mesure que la concentration d’oxygène diminue mais reste significatif jusqu’à 0.5%. Aucune différence significative n’a été observée entre les deux lignes cellulaires. Il est intéressant de noter que la dépendance à l’oxygène varie en fonction de la technique d’irradiation utilisée. Une tentative d’explication de l’influence de l’oxygène par des processus moléculaires est proposée. Des perspectives de développements ultérieurs sont suggéréesAbout 50% of the cancer patients who are treated benefit from radiation therapy. Conventional radiotherapy consists of high energy X-rays traveling through the tissues, so that deeply sited tumors are treated in a non-invasive way. Unfortunately, X-rays are not tumor selective and healthy tissues may be damaged. This lack of selectivity is responsible for severe side effects and/or secondary cancers. Hence, improving the differential of radiation effects between the tumor and surrounding tissues remains a major challenge. Particle therapy (treatment by protons or carbon ion beams) is considered as one of the most promising technique because, by opposition to X-rays, the energy deposition of ions is maximum at the end of their tracks. When the beam is tuned so that the maximum reaches the tumor, there is no damage induced in tissues siting after the tumor. Another important added value is that heavy ions are more efficient to treat radioresistant tumors. The use of this modality is however restricted by the low but significant damage that is induced to normal tissues located at the entrance of the track prior to reaching the tumor. To improve the performance of particle therapy, a new strategy based on the combination of high-Z nanoparticles with ion beam radiation has been developed by the group at ISMO. This approach aims at using nano-agents not only to increase radiation effects in the tumor but also to improve medical imaging with the same agent (theranostic). Nanoparticles present a remarkable surface chemistry, which allows functionalization with ligands able to improve biocompatibility, stability as well as blood circulation and accumulation in tumors. The group already demonstrated the efficiency of small (≈ 3 nm) gold and platinum nanoparticles to amplify the effects of medical carbon ions in normoxic conditions (in the presence of oxygen). However, radioresistant tumors may host hypoxic regions. It is thus urgent to quantify and characterize the influence of oxygen on the radio-enhancement effect. The goal of my thesis was to study the influence of oxygen on medical ion radiation effects in the presence of gold and platinum nanoparticles. This was performed using two radioresistant human cancer cell lines: HeLa (uterine cervix) and BxPC-3 (pancreas). Different radiation modalities were used: carbon and helium ion beams delivered by a passive scattering delivery system and carbon ion beams delivered by a pencil beam scanning system. The major results of this work are the following. In oxic conditions (O₂ concentration = 20%), an enhancement of ion radiation effects was observed for the two nanoparticles (at the same concentration in metal). This effect decreased with the oxygen concentration but remained significant for a concentration of 0.5%. No significant difference was found between the cell lines. Interestingly, the oxygen-dependence varied with the type of radiation. An attempt to explain the effect of oxygen by molecular processes is proposed. Perspectives of further developments are suggested
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Tabor, Christopher Eugene. "Some optical and catalytic properties of metal nanoparticles". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31794.
Abstract (sommario):
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.Committee Chair: El-Sayed, Mostafa; Committee Member: Perry, Joseph; Committee Member: Wang, Zhong; Committee Member: Whetten, Robert; Committee Member: Zhang, John. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Powell, Tremaine Bennett. "The Use of Nanoparticles on Nanometer Patterns for Protein Identification". Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194368.
Abstract (sommario):
This dissertation describes the development of a new method for increasing the resolution of the current protein microarray technology, down to the single molecule detection level. By using a technique called size-dependent self-assembly, different proteins can be bound to different sized fluorescent nanostructures, and then located on a patterned silicon substrate based on the sized pattern which is closest to the size of the bead diameter.The protein nanoarray was used to detect antibody-antigen binding, specifically anti-mouse IgG binding to mouse IgG. The protein nanoarray is designed with the goal of analyzing rare proteins. However, common proteins, such as IgG, are used in the initial testing of the array functionality. Mouse IgG, representing rare proteins, is conjugated to fluorescent beads and the beads are immobilized on a patterned silicon surface. Then anti-mouse IgG binds to the mouse IgG on the immobilized beads. The binding of the antibody, anti-mouse IgG, to the antigen, mouse IgG is determined by fluorescent signal attenuation.The first objective was to bind charged nanoparticles, conjugated with proteins, to an oppositely charged silicon substrate. Binding of negatively charged gold nanoparticles (AuNP), conjugated with mouse IgG, to a positively charged silicon surface was successful.The second objective was to demonstrate the method of size-dependent self-assembly at the nanometer scale (<100 >nm). Different-sized, carboxylated, fluorescent beads and AuNP, which were conjugated with proteins, were serially added to a patterned polymethyl methacrylate (PMMA) coated silicon surface. Size-dependent self-assembly was successfully demonstrated, down to the nanometer scale.The final objective was to obtain a signal from antibody-antigen binding within the protein array. Conjugated fluorescent beads were bound to e-beam patterns and signal attenuation was measured when the antibodies bound to the conjugated beads. The size-dependent self-assembly is a valuable new method that can be used for the detection and quantification of proteins.
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Arribard, Yann. "Analyse de matière extraterrestre primitive par imagerie hyperspectrale infrarouge et spectrométrie de masse TOF-SIMS". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASP005.
Abstract (sommario):
La matière extraterrestre dite primitive se caractérise par sa faible évolution chimique depuis sa formation. Elle se retrouve notamment comme un des constituants des fragments de petits corps du système Solaire, tels que les astéroïdes. L'étude d'échantillons en provenance de ces corps peut ainsi permettre de mieux comprendre son origine et son évolution.Dans cette thèse, mon travail s'est orienté autour de l'analyse de la matière primitive et plus particulièrement sur l'étude des chondrites carbonées ayant subi de l'altération aqueuse. La première partie de ma thèse s'oriente sur l'analyse des phases minérales et organiques au sein de chondrites CM de type pétrologique 2 grâce à des techniques de spectroscopie infrarouge et Raman ainsi que de la spectrométrie de masse à ionisation secondaire par temps de vol (TOF-SIMS). Ces techniques bénéficient d'une bonne complémentarité dans la caractérisation des différentes phases qui nous intéressent. Elles sont également couplées à l'imagerie, ce qui permet d'étudier le lien qu'il peut exister entre les différentes phases minérales et organiques. J'ai utilisé un nouveau processus non supervisé d'analyse des données hyperspectrales infrarouge, ce qui a permis de déterminer des paramètres spectraux caractérisant l'état d'avancement de l'altération aqueuse des échantillons, notamment de leur phase minérale, tout en les reliant à leur évolution chimique. La spectroscopie Raman a permis de mettre en évidence des différences de structure de la matière organique poly-aromatique au sein des différents échantillons. Enfin, le TOF-SIMS a également mis en évidence une différence de structure de la matière organique tout en confirmant et précisant les différences de co-localisation entre matière organique et phase minérale observées par l'imagerie hyperspectrale entre les échantillons.La seconde partie de ma thèse s'est orientée sur l'étude d'efficacité d'un nouvel accélérateur linéaire - Andromede (IJCLab) - comme source primaire pour le TOF-SIMS sur des analogues à la matière primitive des chondrites. J'ai produit ces analogues organiques en laboratoire afin de simuler la matière organique insoluble, la part majoritaire de la matière organique des chondrites. J'ai contrôlé les caractéristiques de ces analogues par des spectroscopies infrarouges, à rayon X et par TOF-SIMS. Ils demeurent différents de la matière organique des CM en termes de structure poly-aromatique, mais similaires en termes de composition élémentaire et caractère insoluble. J'ai produit des analogues minéraux à partir de roches terrestres similaires aux minéraux rencontrés dans les CM. Les mesures que j'ai réalisées sur ces analogues et sur des chondrites montrent à la fois le potentiel et les limites actuelles du TOF-SIMS couplé à Andromède, et suggèrent des pistes d'amélioration en vue d'en augmenter, notamment, la résolution en masseSo-called primitive extraterrestrial matter is characterized by its low chemical evolution since its formation. It is found in particular as one of the constituents of the fragments of small bodies of the Solar system, such as asteroids. The study of samples from these bodies can thus make it possible to better understand its origin and its evolution.In this thesis, my work focused on the analysis of primitive matter and more particularly on the study of carbonaceous chondrites having undergone aqueous alteration. The first part of my thesis focuses on the analysis of mineral and organic phases within petrological type 2 CM chondrites using infrared and Raman spectroscopy techniques as well as time-of-flight secondary ionization mass spectrometry. (TOF-SIMS). These techniques benefit from a good complementarity in the characterization of the different phases that interest us. They are also coupled with imagery, which makes it possible to study the link that may exist between the different mineral and organic phases. I used a new unsupervised process for analyzing infrared hyperspectral data, which made it possible to determine spectral parameters characterizing the state of progress of the aqueous alteration of the samples, in particular of their mineral phase, while relating to their chemical evolution. Raman spectroscopy made it possible to highlight differences in the structure of the polyaromatic organic matter within the different samples. Finally, the TOF-SIMS also highlighted a difference in the structure of the organic matter while confirming and clarifying the differences in co-localization between organic matter and mineral phase observed by hyperspectral imaging between the samples.The second part of my thesis focused on the study of the effectiveness of a new linear accelerator - Andromeda (IJCLab) - as a primary source for TOF-SIMS on analogues of primitive chondrite matter. I produced these organic analogues in the laboratory to simulate insoluble organic matter, the majority of organic matter in chondrites. I checked the characteristics of these analogues by infrared spectroscopy, X-ray spectroscopy and TOF-SIMS. They remain different from CM organic matter in terms of poly-aromatic structure, but similar in terms of elemental composition and insoluble character. I have produced mineral analogues from earth rocks similar to minerals found in CM chondrite. The measurements that I carried out on these analogues and on chondrites show both the potential and the current limits of TOF-SIMS coupled to Andromede, and suggest areas for improvement with a view to increasing, in particular, the masse resolution
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Do, Jaekwon. "Controlled spatial arrangement of gold nanoparticles using focused laser beams and DNA origami". Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-171381.
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Krishnappa, Arjun. "Optical Steering of Microbubbles for Nanoparticle Transport". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1469461239.
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Kong, David Sun 1979. "Nanostructure fabrication by electron and ion beam patterning of nanoparticles". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28346.
Abstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2004.Includes bibliographical references (leaves 82-83).
Two modes of energetic beam-mediated fabrication have been investigated, namely focused ion beam (FIB) direct-writing of nanoparticles, and a technique for electrostatically patterning ionized inorganic nanoparticles, termed nanoxerography. A FIB has been used to directly pattern thin films of organometallic Ag-precursors down to a resolution of 100 nm. The sensitivity of the resist to 30 keV Ga+ ions was measured to be approximately 5 C/cm2. Using this technique arbitrary structures were fabricated in two and three dimensions with resistivity on the order of 1x10 4 Q-cm and 1x1 0-5 Q-cm for single- and multi-layer structures, respectively. A new unit of merit for characterizing direct-write processes, termed resistivity-dose (Q-jC/cm), has been introduced. A Nanocluster Source capable of generating a beam of charged, inorganic nanoparticles has been characterized. The relationship between power supplied to the magnetron of the source and the size of deposited clusters has been plotted. Techniques for utilizing such clusters to develop latent electrified images patterned by an electron beam (EB) have been proposed. The charge-storing characteristics of a variety of substrates such as mylar and polyimide were studied by developing EB-patterned charge images with toner particles.
David Sun Kong.
S.M.
9
MELONI, MARIA CRISTINA. "Preparazione e caratterizzazione di due sistemi carrier: beads a base di chitosano e chitosano/alginato; nanoparticelle di N-trimetilchitosano". Doctoral thesis, Università degli Studi di Cagliari, 2012. http://hdl.handle.net/11584/266151.
Abstract (sommario):
Chitosan is a very attractive polysaccharide and it is known to be a favorable pharmaceutical material because of its low toxicity, biodegradability, biocompatibility,
mucoadhesivity and natural origin. Therefore it forms an ideal hydrophilic carrier system. In this study we described the preparation and characterization of two carrier systems, chitosan and chitosan – alginate beads, and N-Trimethyl Chitosan (TMC) chloride nanoparticles.
We realized spherical beads using different polymeric dispersions, chitosan, alginate and chitosan - alginate mixture, to investigate their effect on the phytoterapic anti- inflammatory agent delivery. The main purpose of the present in vitro study is to have some information about their stability in the gastrointestinal tract and to formulate a drug delivery system for the oral administration of this phytoterapic agent. Alginate
beads were prepared by ionotropic gelation in presence of CaCl2 and BaCl2 solutions; chitosan beads were prepared by using a TPP (tripolyphosphate) solution as an ionic
cross-linking agent and acetone as a coacervating agent; beads of chitosan - alginate mixture were prepared according to the two combined procedures reported above.
The swelling degradation behaviour of the bead samples and drug release were investigated using four different medium solutions (PBS pH 7.4, HCl 0.1N pH 1, buffer pH 5). TMC with different degrees of quaternization were synthesized and characterized by 1 H- NMR spectroscopy, XRD and viscosity. Trimethyl Chitosan chloride nanoparticles (TMC-NPs) were prepared according to the ionotropic gelation process of TMC with TPP. The aim of this study is to characterized TMC-NPs (particle size -Z-average mean-, PDI and zeta potential) and evaluate their potential for brain delivery.
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Tijiwa, Birk Felipe. "Spin electronics in metallic nanoparticles". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39525.
Abstract (sommario):
The work presented in this thesis shows how tunneling spectroscopy techniques can be applied to metallic nanoparticles to obtain useful information about fundamental physical processes in nanoscopic length scales. At low temperatures, the discrete character of the energy spectrum of these particles, allows the study of spin-polarized current via resolved "electron-in-a-box" energy levels. In samples consisting of two ferromagnetic electrodes tunnel coupled to single aluminum nanoparticles, spin accumulation mechanisms are responsible for the observed spin-polarized current. The observed effect of an applied perpendicular magnetic field, relative to the magnetization orientation of the electrodes, indicates the suppression of spin precession in such small particles. More generally, in the presence of an external non-collinear magnetic field, it is the local field "felt" by the particle that determines the character of the tunnel current. This effect is also observed in the case where only one of the electrodes is ferromagnetic. In contrast to the non-magnetic case, ferromagnetic nanoparticles exhibit a much more complex energy spectrum, which cannot be accounted for, using the simple free-electron picture. It will be shown that interactions between quasi-particle excitations due to sequential electron tunneling and spin excitations in the particle are likely to play an important role in the observed temperature/voltage dependence of magnetic hysteresis loops.
Libri sul tema "Nanoparticle beams":
1
Seibel, Robin. Manipulation of micro scale particles in an optical trap using interferometry. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2002.
2
Manipulation of micro scale particles in an optical trap using interferometry. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2002.
Capitoli di libri sul tema "Nanoparticle beams":
1
Hall, B. D., M. Hyslop, A. Wurl e S. A. Brown. "Electron Diffraction from Atomic Cluster Beams". In Gas Phase Nanoparticle Synthesis, 157–84. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2444-3_6.
2
Gerlich, Stefan, Yaakov Y. Fein, Armin Shayeghi, Valentin Köhler, Marcel Mayor e Markus Arndt. "Otto Stern’s Legacy in Quantum Optics: Matter Waves and Deflectometry". In Molecular Beams in Physics and Chemistry, 547–73. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63963-1_24.
Abstract (sommario):
AbstractOtto Stern became famous for molecular beam physics, matter-wave research and the discovery of the electron spin, with his work guiding several generations of physicists and chemists. Here we discuss how his legacy has inspired the realization of universal interferometers, which prepare matter waves from atomic, molecular, cluster or eventually nanoparticle beams. Such universal interferometers have proven to be sensitive tools for quantum-assisted force measurements, building on Stern’s pioneering work on electric and magnetic deflectometry. The controlled shift and dephasing of interference fringes by external electric, magnetic or optical fields have been used to determine internal properties of a vast class of particles in a unified experimental framework.
3
Al-Furjan, M. S. H., M. Rabani Bidgoli, R. Kolahchi, A. Farrokhian e M. R. Bayati. "Buckling of Nanoparticle-Reinforced Beams Exposed to Fire". In Application of Numerical Methods in Engineering Problems using MATLAB®, 29–42. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003349525-3.
4
Townsend, Peter. "Luminescence, Ion Implantation, and Nanoparticles". In Ion Beams in Nanoscience and Technology, 357–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00623-4_29.
5
Rizza, Giancarlo, e Mark C. Ridgway. "Ion-Shaping of Nanoparticles". In Ion Beam Modification of Solids, 443–73. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-33561-2_11.
6
Ehbrecht, M., H. Hofmeister, B. Kohn e F. Huisken. "Molecular Beams of Silicon Clusters and Nanoparticles Produced by Laser Pyrolysis of Gas Phase Reactants". In Atomic and Molecular Beams, 709–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56800-8_50.
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Verkhovtsev, Alexey, Andrei V. Korol e Andrey V. Solov’yov. "Irradiation-Induced Processes with Atomic Clusters and Nanoparticles". In Nanoscale Insights into Ion-Beam Cancer Therapy, 237–76. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-43030-0_7.
8
Bolsa Ferruz, M., V. Ivošev, K. Haume, L. Ellis-Gibbings, A. Traore, V. Thakare, S. Rosa et al. "New Research in Ionizing Radiation and Nanoparticles: The ARGENT Project". In Nanoscale Insights into Ion-Beam Cancer Therapy, 379–434. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-43030-0_12.
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Khaibullin, R. I., B. Z. Rameev, A. L. Stepanov, C. Okay, V. A. Zhikharev, I. B. Khaibullin, L. R. Tagirov e B. Aktaş. "Ion Beam Synthesis of Magnetic Nanoparticles in Polymers". In Nanostructured Magnetic Materials and their Applications, 33–54. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2200-5_4.
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Chen, Feng, Hiroshi Amekura e Yuechen Jia. "Fundamentals of Ion Beam Technology, Waveguides, and Nanoparticle Systems". In Springer Series in Optical Sciences, 1–19. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-4607-5_1.
Atti di convegni sul tema "Nanoparticle beams":
1
Hurst, K. M., C. B. Roberts e W. R. Ashurst. "Reduced Microstructure Adhesion Provided by Gas-Expanded Liquid Deposited Gold Nanoparticles". In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71253.
Abstract (sommario):
In order to alleviate or eliminate the occurrence of stiction during the actuation of microstructures, the real contact area available for contact must be reduced. Au nanoparticles were intentionally deposited using gas-expanded liquids onto polysilicon cantilever beam arrays to increase surface roughness. The nanoparticle-coated beams were subjected to an actuation voltage of 120 V. Following actuation, the adhesion of beams was quantified by estimating the apparent work of adhesion. Au nanoparticles deposited onto these microstructures were shown to drastically reduce the effects of in-use stiction. Capillary adhesion due to condensation of ambient moisture was effectively eliminated.
2
Davino, Michael, Tobias Saule, Jeffrey A. Powell, Nora G. Helming e Carlos Trallero-Herrero. "Strong field ionization for the characterization of aerosolized nanoparticles in vacuum". In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.tu4a.67.
Abstract (sommario):
Strong field ionization is used to attain the three-dimensional nanoparticle density distribution for aerosol nanoparticle beams produced by an aerodynamic lens. This technique bypasses nanoparticle size limitations of light-scattering characterization techniques.
3
Kim, Jinwook, Sandeep Kasoji, Phillip G. Durham e Paul A. Dayton. "Acoustic Hologram Lens Made of Nanoparticle-Epoxy Composite Molding for Directing Predefined Therapeutic Ultrasound Beams". In 2022 IEEE International Ultrasonics Symposium (IUS). IEEE, 2022. http://dx.doi.org/10.1109/ius54386.2022.9957379.
4
Chung, Jaewon, Seunghwan Ko, Nicole R. Bieri, Costas P. Grigoropoulos e Dimos Poulikakos. "Laser Curing of Gold Nanoparticle Inks". In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41650.
Abstract (sommario):
The concept of effective laser curing of nanoparticle suspensions (NPS) with a laser beam is presented in this paper. A toluene solvent is employed as the carrier of gold nanoparticles possessing a lower melting temperature than that of bulk gold. Using a modified drop-on-demand jetting system, the gold nanoparticle suspended solution is printed on a glass substrate and cured with laser irradiation. The laser energy coupling to the nanoparticles in conjunction with thermocapillary effects and the evaporation of the solvent are critical to the quality of the electrically conductive gold microlines. By employing a intensity-modulated double laser beam processing scheme, to optimize the curing process, it is demonstrated for the first time, that the gold nanoparticles could be sintered on a glass substrate to form a gold line of resistivity close to that of bulk gold. This is a noticeable result, compared to recently published microconductor manufacturing with nanoparticle suspensions with oven [1] or low power single laser beam [2] curing reporting resistivities four to five times higher than that of bulk gold. As a consequence, in addition to their scientific value, the current results demonstrate the potential of laser printing for use in the microelectronics manufacturing for the first time. It was also shown that the morphology of the gold line could be modified by appropriate design of the shape of the processing laser beam.
5
Mukherjee, R., W. M. Mook, J. Hafiz, X. Wang, W. W. Gerberich, J. V. R. Heberlein, P. H. McMurry e S. L. Girshick. "Synthesis of Nanocomposites by Ballistic Impaction of Nanoparticles". In ASME 4th Integrated Nanosystems Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/nano2005-87036.
Abstract (sommario):
We are investigating ballistic impact assembly of nanoparticles to form a new class of materials for superhard coatings and micromolded MEMS parts. Nanoparticles are generated by dissociating vapor-phase reactants injected downstream of a thermal plasma and expanding the resultant flow through a converging nozzle into a low-pressure chamber. The nanoparticle-laden gases achieve hypersonic velocities due to the pressure difference between the reaction region (450 torr) and the low-pressure chamber (∼2 torr). Particles are deposited by one of two processes: (a) by placing a substrate 20mm downstream of the flow, which results in a bow shock at the substrate and high impact velocities (calculated to be over 2000 m/s for a 20 nm SiC particle): termed as high-rate deposition, (b) by focusing the particles into a tight beam (width of ∼35 (μm) using aerodynamic lenses, and subsequent impaction on a translating substrate: termed as focused beam deposition. Thus far, nanoparticle deposits consisting of combinations of Si, Ti, C and N have been explored.
6
Cody, Jonathan W., e Sungwon S. Kim. "Effects of Annealing Parameters on Nickel Catalyst Nanoparticle Size for Carbon Nanotube Synthesis Applications". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65514.
Abstract (sommario):
The properties of carbon nanotubes are dependent, in part, on the size of the catalyst metal nanoparticles from which the carbon nanotubes are grown. Annealing is a common technique for forming the catalyst nanoparticles from deposited films. While there is ample work connecting catalyst film properties or catalyst nanoparticle properties to carbon nanotube growth outcomes, the control of catalyst nanoparticle size by means other than the variation of initial film thickness is less explored. This work develops an empirical correlation for the control of nickel nanoparticle equivalent diameter by modification of anneal plateau temperature and anneal plateau time, thereby providing an additional avenue of control for catalyst properties. It has been hypothesized that the size of catalyst nanoparticles can be predetermined by appropriate selection of the initial catalyst film thickness, plateau temperature, and plateau time of the annealing process. To this end, buffer layers of 50 nm titanium, followed by 20 nm aluminum, were deposited onto silicon substrates via electron beam evaporation. Nickel catalyst layers were then deposited with thicknesses of either 5, 10, or 20 nm. Samples of each of the three nickel layer thicknesses were annealed in an ambient air environment at different combinations of 500, 600, 700, 800, and 900 °C plateau temperature and 5, 10, and 15 minute plateau time. Representative time-temperature curves corresponding to each plateau temperature were also acquired. The end result was a set of 45 samples, each with a unique combination of initial nickel film thickness, anneal plateau temperature, and anneal plateau time. Resulting nanoparticles were characterized by atomic force microscopy, and distributions of nanoparticle equivalent diameter were collected via a watershed algorithm implemented by the Gwyddion software package. Comparison of the 45 parameter combinations revealed a wide range of nanoparticle sizes. In most cases, comparable equivalent diameters were obtained from a variety of parameter combinations. Thus, results provide multiple options for achieving the same nanoparticle diameter, for use in cases where additional restraints are present. To facilitate such decisions, a correlation was developed that connected catalyst nanoparticle diameter to the three process parameters of initial catalyst film thickness, anneal plateau temperature, and anneal plateau time. For example, a given initial Ni film thickness can be annealed to a specified nanoparticle size by selecting anneal plateau temperature and plateau time per the correlation, provided that comparable buffer layers were chosen. This correlation provides a more robust array of options for specification of catalyst nanoparticle size and final carbon nanotube properties for a specific application.
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Bansal, Shalu, Chih-Hung Chang e Rajiv Malhotra. "The Coupling Between Densification and Optical Heating in Intense Pulsed Light Sintering of Silver Nanoparticles". In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8693.
Abstract (sommario):
Sintering of nanoparticles deposited onto rigid or flexible substrate is required for many devices that use continuous and patterned thin films. An emerging need in this area is to perform nanoparticle sintering under ambient conditions, at high speeds, and with throughput that is compatible with high speed nanoparticle deposition techniques. Intense Pulsed Light sintering (IPL) uses a high energy, broad area and broad spectrum beam of xenon lamp light to sinter metallic and non-metallic nanoparticles. The capability of IPL to meet the above needs has been demonstrated. This paper experimentally examines temperature evolution and densification during IPL. It is shown, for the first time, that temperature rise and densification in IPL are related to each other. A coupled optical-thermal-sintering model on the nanoscale is developed, to understand this phenomenon. This model is used to show that the change in nanoscale shape of the nanoparticle ensemble due to sintering, reduces the optically induced heating as the densification proceeds, which provides a better explanation of experimental observations as compared to current models of IPL. The implications of this new understanding on the performance of IPL are also discussed.
8
Zhou, Yingke, Robert Pasquarelli, Joe Berry, David Ginley e Ryan O’Hayre. "Improving PEM Fuel Cell Catalysts Using Nitrogen-Doped Carbon Supports". In ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/fuelcell2008-65172.
Abstract (sommario):
This study experimentally examines the effect of nitrogen doping on the activity of Pt/C catalyst systems. The investigation was accomplished through the development of geometrically well-defined model catalytic systems consisting of tunable assemblies of Pt catalyst nanoparticles deposited onto both N-doped and undoped highly-oriented pyrolytic graphite (HOPG) substrates. N-doping was achieved via ion beam implantation, and Pt was electrodeposited from solutions of H2PtCl6 in aqueous HClO4. Morphology from scanning electron microscopy (SEM) and catalytic activity measurement from aqueous electrochemical analysis were utilized to examine the N-doping effects. The results strongly support the theory that doping nitrogen into a graphite support significantly affects both the morphology and behavior of the overlying Pt nanoparticles. In particular, nitrogen-doping was observed to cause a significant decrease in the average Pt nanoparticle size, an increase in the Pt nanoparticle dispersion, and a significant increase in catalytic activity for both methanol oxidation and oxygen reduction.
9
Zhang, Yi, e Gary J. Cheng. "Multilayer Laser Sintering of HAp/Ti Nanoparticles Onto Metallic Implants". In ASME 2009 International Manufacturing Science and Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/msec2009-84089.
Abstract (sommario):
Novel methodology of laser sintering of mixture of mixture of bio-ceramics and metallic nanoparticles on metallic implants is introduced in current work. Feasibility of this method is demonstrated using a multiphysics numerical simulation. Treating laser beam as electromagnetic (EM) wave, EM module is coupled with heat transfer (HT) module. The EMHT scheme analyzes the interaction between laser-nanoparticles which ends up with temperature raise within the sample. As a demonstration, HAp and Ti nanoparticles are employed to be sintered on titanium substrate. Processing parameters such as laser power, beam radius, scan speed, and layer thickness are studied, and correlation between these parameters and final temperature is presented. Effects of mixing ratio and nanoparticle size are also examined. Considering effects of mixing ratios and particle sizes, the following coating scheme is proposed for future experiments: varying HAp concentration from 100% to 0% at 10% intervals from coating surface to coating/substrate interface, and meanwhile, varying particle diameters from 500 nm to 100 nm at 100 nm intervals.
10
Ortega, A. Balbuena, F. E. Torres-González, V. López Gayou, R. Delgado Macuil, G. Assanto e K. Volke-Sepulveda. "Induced dark solitons by means of singular beams". In CLEO: Applications and Technology. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_at.2022.jtu3a.46.
Abstract (sommario):
We investigate the nonlinear propagation of singular light beams with complex structures of phase and intensity in a colloidal suspension of gold nanoparticles. All the structured beams can act as waveguides of a probe beam.
Rapporti di organizzazioni sul tema "Nanoparticle beams":
1
Toney, Michael F. Ion Beam Stabilization of FePt Nanoparticle Arrays for Magnetic Storage Media. Office of Scientific and Technical Information (OSTI), luglio 2003. http://dx.doi.org/10.2172/813281.
2
Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock e Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, gennaio 2013. http://dx.doi.org/10.32747/2013.7598156.bard.
Abstract (sommario):
Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.