Nanometer-sized Metal Particles Research Articles

Footprints of atomic-scale features in plasmonic nanoparticles as revealed by electron energy loss spectroscopy.

We present a first-principles theoretical study of the atomistic footprints in the valence electron energy loss spectroscopy (EELS) of nanometer-size metallic particles. Charge density maps of excited plasmons and EEL spectra for specific electron paths through a nanoparticle (Na380 atom cluster) are modeled using ab initio calculations within time-dependent density functional theory. Our findings unveil the atomic-scale sensitivity of EELS within this low-energy spectral range. Whereas localized surface plasmons (LSPs) are particularly sensitive to the atomistic structure of the surface probed by the electron beam, confined bulk plasmons (CBPs) reveal quantum size effects within the nanoparticle's volume. Moreover, we prove that classical local dielectric theories mimicking the atomistic structure of the nanoparticles reproduce the LSP trends observed in quantum calculations, but fall short in describing the CBP behavior observed under different electron trajectories.

Process intensification of microplasma nanoparticle synthesis enabled by gas flow design

The wide range of practical uses for nanometer-size metal particles has motivated many lab-scale aerosol synthesis processes. It is well known that the aggregation dynamics of aerosol particles impose a trade-off between particle size and concentration: methods that achieve sub-10 nm particles without aggregation are generally limited by low concentration and low flow rates of order 100 cm3/min. Thus, the intensification of aerosol nanoparticle synthesis and its development for industrial use remains a unique and important manufacturing challenge. We present a microplasma reactor system that has been developed to improve process intensification and reliability. The system utilizes an atmospheric pressure DC microplasma to synthesize iron-carbon particles from a ferrocene vapor precursor. The microplasma incorporates a novel focusing technique using a spatial gradient in gas composition to stabilize short-term fluctuations in performance, achieving an iron yield of up to 0.93. We identify the build-up of deposits between the plasma electrodes as the primary cause of reduced performance over time, and eliminate this build-up by indirectly supplying ferrocene to avoid dissociation in this region of the reactor. Further, we show that the design and conditions downstream of the microplasma have a similar influence on the final particle size distribution as those of the microplasma itself. By tuning the coupled process variables of both the microplasma and this downstream region, we synthesize aerosols with mean diameter from 2 to 7 nm and number concentration of 2 to 8×109 #/cm3 at the system outlet.

Heat transfer and thermoregulation within single cells revealed by transient plasmonic imaging

Summary Cells, as the basic unit of life, undergo continuous heat transfer and dissipation during their metabolism, which is related not only to fundamental cellular functions but also massive applications. Unfortunately, thus far, we still know little about the heat transfer properties at the cellular or subcellular levels. Here, we demonstrated a transient microscopic method to measure the heat transfer in single cells. The thermal conductivity of different regions within a single cell shows a wide heterogeneity, and heat transfer in the region near the cell membrane is more active than the central region. However, the median values of thermal conductivity between different individual cells are quite close. A cellular-level heat regulation that responds to environmental temperature is observed in warm-blooded humans and chickens rather than in cold-blooded bullfrogs. According to the temperature-dependent cell metabolism, we proposed a hypothesis for cellular control of heat dissipation, which might be the cellular-level foundation of body thermoregulation.

Stability of Cu-islands formed on Si substrate via ‘dewetting’ under subsequent thermal cycling

Very thin metallic films deposited on a substrate often dewet upon thermal exposure, forming discrete islands of micrometer and nanometer-sized metal particles. Herein, Cu islands on Si substrate, which were formed due to agglomeration (or ‘dewetting’) of Cu thin film at 600 °C, were exposed to thermal cycling, and the ensuing evolution in their morphology was monitored. Thermal cycling was performed between either −25 °C and 150 °C or 25 °C and 400 °C, using different heating and cooling rates. With faster heating-cooling rates, a change in the shape and size of the Cu islands was observed, whereas a slow heating-cooling rate did not induce noticeable effect on their morphology. Furthermore, the formation of new nano- and micro-sized particles, probably through the dewetting of the ultra-thin layer of Cu that was left intact during the initial agglomeration treatment, was observed during the thermal cycling performed at fast rates up to 400 °C. Finite element analysis, incorporating Anand’s viscoplasticity model, revealed the existence of high strain energy density in the vicinity of the particle-Si interface when the thermal cycling is carried at a faster ramp rate, suggesting the pivotal role of thermal stresses, in addition to the maximum temperature, in controlling the morphology of the Cu particles and the dewetting of the residual ultra-thin layer of Cu on Si.

Adverse Local Tissue Reactions in Total Hip Arthroplasty: Who, When, and How to Revise

Adverse local tissue reaction (ALTR) has initially been described as a complication in metal-on-metal total hip arthroplasty (THA) [ 1 Kwon Y.-M. Glyn-Jones S. Simpson D.J. Kamali A. McLardy-Smith P. Gill H.S. et al. Analysis of wear of retrieved metal-on-metal hip resurfacing implants revised due to pseudotumours. J Bone Joint Surg Br. 2010; 92: 356-361https://doi.org/10.1302/0301-620X.92B3.23281 Crossref PubMed Scopus (185) Google Scholar , 2 Kwon Y.-M. Fehring T.K. Lombardi A.V. Barnes C.L. Cabanela M.E. Jacobs J.J. Risk stratification algorithm for management of patients with dual modular taper total hip arthroplasty: consensus statement of the American Association of Hip and Knee Surgeons, the American Academy of Orthopaedic Surgeons and the Hip Society. J Arthroplasty. 2014; 29: 2060-2064https://doi.org/10.1016/j.arth.2014.07.029 Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar , 3 Liow M.H.L. Kwon Y.-M. Metal-on-metal total hip arthroplasty: risk factors for pseudotumours and clinical systematic evaluation. Int Orthop. 2017; 41: 885-892https://doi.org/10.1007/s00264-016-3305-1 Crossref PubMed Scopus (37) Google Scholar , 4 Kwon Y.-M. Cross-sectional imaging in evaluation of soft tissue reactions secondary to metal debris. J Arthroplasty. 2014; 29: 653-656https://doi.org/10.1016/j.arth.2014.02.007 Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar , 5 MacDonald S.J. Brodner W. Jacobs J.J. A consensus paper on metal ions in metal-on-metal hip arthroplasties. J Arthroplasty. 2004; 19: 12-16https://doi.org/10.1016/j.arth.2004.09.009 Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar ]. However, there have recently been increasing concerns regarding the occurrence of ALTR in metal-on-polyethylene THA due to corrosion at the head-neck taper junction in a process described as mechanically assisted crevice corrosion [ [6] Jacobs J.J. Gilbert J.L. Urban R.M. Corrosion of metal orthopaedic implants. J Bone Joint Surg Am. 1998; 80: 268-282https://doi.org/10.2106/00004623-199802000-00015 Crossref PubMed Scopus (743) Google Scholar ]. The generation of biologically active, nanometer-sized metal particles and metal ions from the arthroplasty bearing surfaces and taper junctions has been associated with the occurrence of localized, adverse periprosthetic soft tissue response, which has been recently recognized as an important emerging mode of failure in THA patients [ 7 Liow M.H.L. Urish K.L. Preffer F.I. Nielson G.P. Kwon Y.-M. Metal ion levels are not correlated with histopathology of adverse local tissue reactions in taper corrosion of total hip arthroplasty. J Arthroplasty. 2016; 31: 1797-1802https://doi.org/10.1016/j.arth.2016.01.041 Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar , 8 Kwon Y.-M. MacAuliffe J. Arauz P.G. Peng Y. Sensitivity and specificity of metal ion level in predicting adverse local tissue reactions due to head-neck taper corrosion in primary metal-on-polyethylene total hip arthroplasty. J Arthroplasty. 2018; 33: 3025-3029https://doi.org/10.1016/j.arth.2018.04.007 Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar , 9 Cooper H.J. Urban R.M. Wixson R.L. Meneghini R.M. Jacobs J.J. Adverse local tissue reaction arising from corrosion at the femoral neck-body junction in a dual-taper stem with a cobalt-chromium modular neck. J Bone Joint Surg Am. 2013; 95: 865-872https://doi.org/10.2106/JBJS.L.01042 Crossref PubMed Scopus (296) Google Scholar , 10 Vendittoli P.-A. Roy A. Mottard S. Girard J. Lusignan D. Lavigne M. Metal ion release from bearing wear and corrosion with 28 mm and large-diameter metal-on-metal bearing articulations: a follow-up study. J Bone Joint Surg Br. 2010; 92: 12-19https://doi.org/10.1302/0301-620X.92B1.22226 Crossref PubMed Scopus (100) Google Scholar , 11 Seon J.-K. Park J.-K. Shin Y.-J. Seo H.-Y. Lee K.-B. Song E.-K. Comparisons of kinematics and range of motion in high-flexion total knee arthroplasty: cruciate retaining vs. substituting designs. Knee Surg Sports Traumatol Arthrosc. 2011; 19: 2016-2022https://doi.org/10.1007/s00167-011-1434-z Crossref PubMed Scopus (51) Google Scholar ]. At the 2019 Annual Meeting of American Association of Hip and Knee Surgeons, the symposium on ALTRs with particular focus on “who, when, and how to revise” patients with ALTR was presented. The objectives of this symposium were to summarize clinical challenges in optimizing patient evaluation and revision surgery outcome. Specifically, the symposium presentations highlighted that there is a spectrum of clinical presentations of ALTRs due to taper corrosion and metal bearing surface wear, reflecting a complex interplay of implant, surgical, and patient factors. The current state of knowledge on the importance of various taper material combinations and taper design geometry on taper corrosion is evolving. A systematic risk stratification approach based on currently available data is critical in optimizing evaluation and revision surgery indications. The utility and limitations of specialized diagnostic tests including metal ion levels and cross-sectional imaging studies such as metal artifact reduction sequence magnetic resonance imaging in the clinical decision-making process is important in evaluation of these patients. Furthermore, optimizing revision surgery outcome for ALTRs involves careful preoperative planning, implant selection, and surgical techniques to overcome challenges associated with soft tissue necrosis.

A Glance on Preparation, Stability, Properties and Applications of Nanofluids

Nanofluids are colloidal suspension engineered by dispersing nanometersized metallic or non-metallic particles (nanoparticles, nanotubes, nanowires, nanosheets or droplets) in a base fluid. The nanofluid enhances properties of the base fluid. Nanofluids have extraordinary properties that make them potentially useful in many applications. Even though the nanofluid has lots of advantages, its applications are limited due to poor stability over long-term, high-pressure drop, particle collection, low specific heat, high cost. In this review, an attempt has been made to explain the method of preparation, stability, properties, and applications of nanofluids.

Energetic ion-induced modification of embedded Au nanoparticles size: a three-dimensional kinetic lattice Monte Carlo study

Nanometer-sized noble metallic particles embedded in dielectric matrices are of wide interest. To exploit their plasmonic properties, efforts have been made to vary their size and shape by various methods during or after fabrication. Energetic ion irradiation has been found to be very useful in this objective. In the present work, we have studied the effect of inter-particle separation using atomistic simulations to gain a better understanding of the pathway in the modification of size of nanoparticles which are smaller than the ion track size in the matrix. It is found that the size of nanoparticles can be varied depending on the initial inter-particle separation and the temperature in the spike generated by the passed energetic ion. The results agree with the model proposed by our group, based on inter-particle separation, to explain experimental results on the swift heavy ion-induced modification of the size of embedded nanoparticles.

A Gallium-Based Magnetocaloric Liquid Metal Ferrofluid.

We demonstrate a magnetocaloric ferrofluid based on a gadolinium saturated liquid metal matrix, using a gallium-based liquid metal alloy as the solvent and suspension medium. The material is liquid at room temperature, while exhibiting spontaneous magnetization and a large magnetocaloric effect. The magnetic properties were attributed to the formation of gadolinium nanoparticles suspended within the liquid gallium alloy, which acts as a reaction solvent during the nanoparticle synthesis. High nanoparticle weight fractions exceeding 2% could be suspended within the liquid metal matrix. The liquid metal ferrofluid shows promise for magnetocaloric cooling due to its high thermal conductivity and its liquid nature. Magnetic and thermoanalytic characterizations reveal that the developed material remains liquid within the temperature window required for domestic refrigeration purposes, which enables future fluidic magnetocaloric devices. Additionally, the observed formation of nanometer-sized metallic particles within the supersaturated liquid metal solution has general implications for chemical synthesis and provides a new synthetic pathway toward metallic nanoparticles based on highly reactive rare earth metals.

Surface plasmon resonance absorption of composite films doped with metal nanoparticles

Composite thin films formed by nanometer-sized metal particles embedded in dielectric matrices were fabricated by codepositing the metal and ceramic targets using a pulsed laser deposition technique. The optical absorption properties were measured from 350 to 800 nm, and the absorption peak due to the surface plasmon resonance of metal particles was found. The effects of different metal particles (Au, Ag, Fe, and Co) and embedding matrices (SrTiO3, Al2O3, and TiO2) on the optical absorption properties of the composite films were discussed. Strong absorption peaks can be found in composite films doped with noble metal particles, while most transition metal particles show ordinary absorption patterns. Dielectric properties of metal particles and the refractive index of embedding matrices were responsible for the observed results.

Optical absorption properties of dielectric composite films doped with metal nanoparticles

Composite thin films formed by using nanometer-sized metal particles embedded in dielectric matrices were fabricated by using a pulsed laser deposition technique to co-deposit the metal and the ceramic targets. The optical absorption properties were measured at wavelength from 350 to 800 nm, and the absorption peak due to the surface plasmon resonance of the metal particles was found. The effects of different metal particles (Au, Ag, Fe, Co) and different embedding matrices (SrTiO3, Al2O3, and TiO2) on the optical absorption properties of dielectric composite films are discussed. Strong absorption peaks can be found in composite films doped with noble-metal particles while the composites doped with most transition-metal particles show ordinary absorption patterns. The dielectric properties of the metal particles and the refractive indices of the embedding matrices were responsible for the observed results.

Metal-on-metal total hip arthroplasty: risk factors for pseudotumours and clinical systematic evaluation.

The potential advantages of contemporary MoM THA implants include less volumetric wear with subsequent reduction of polyethylene wear-induced osteolysis and greater component stability with use of large-diameter femoral heads. However, there have been concerns regarding significantly elevated revision rates in MoM THA due to MoM-related complications such as adverse local tissue reaction (pseudotumour) formation. The increased failure rate in MoM hip arthroplasty is associated with the generation of biologically active, nanometer sized metal particles from the MoM bearing surfaces and taper junctions, which result in the development of a localized, adverse periprosthetic soft tissue response. The focus of this article is to provide an update on (1) implant, surgical and patient factors associated with adverse local tissue reactions (pseudotumours) and (2) the clinical systematic evaluation and management of patients with MoM hip arthroplasty based on the currently available evidence. There should be a low threshold to conduct a systematic clinical evaluation of patients with MoM hip arthroplasty as early recognition and diagnosis will allow the initiation of prompt and appropriate treatment. As a symptomatic MoM total hip arthroplasty may have intrinsic and extrinsic causes, patients should be evaluated systematically, utilizing risk stratification algorithms. Although specialized laboratory tests such as metal ion levels and cross sectional imaging modalities such as MARS MRI can be used to facilitate clinical decision making, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. Further research is required to obtain a better understanding of implant and patient risk factors associated with tribocorrosion in MoM total hip arthroplasty.

ChemInform Abstract: Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research

AbstractReview: 93 refs.

Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research.

The foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like electrolyzers or fuel cells. Transmission electron microscopy (TEM) and scanning transmission electron microscope (STEM) are to a great extent nondestructive characterization tools that provide structural, morphological, and compositional information with nanoscale or even atomic resolution. Due to recent marked advancement in electron microscopy equipment such as aberration corrections and monochromators, such insightful information is now accessible in many institutions around the world and provides huge benefit to everyone using electron microscopy characterization in general. Classical ex situ TEM characterization of random catalyst locations however suffers from two limitations regarding catalysis. First, the necessary low operation pressures in the range of 10(-6) to 10(-9) mbar for TEM are not in line with typical reaction conditions, especially considering electrocatalytic solid-liquid interfaces, so that the active state cannot be assessed. Second, and somewhat related, is the lack of time resolution for the evaluation of alterations of the usually highly heterogeneous nanomaterials. Two methods offer a solution to these shortcomings, namely, identical location TEM (IL-TEM) and electrochemical in situ liquid TEM. The former is already well established and has delivered novel insights particularly into degradation processes; however, characterization is still performed in vacuum. The latter circumvents this issue by using dedicated in situ TEM holders but introduces extremely demanding technical challenges. Although the introduction of revolutionizing thin SiN window cells, which elegantly confine the specimen from vacuum, has allowed demonstration of the potential of the in situ approach, the reproducibility and data interpretation is still limited predominately due to the strong interaction of the electron beam with the supporting electrolyte and electrode material. Because of the importance of understanding the nanoelectrochemical structure-function relationship, this Account aims to convey a timely perspective on the opportunities and particularly the challenges in electrochemical identical location TEM and in situ liquid cell TEM with a focus on electrochemical energy conversion.

Odyssey in Polyphasic Catalysis by Metal Nanoparticles.

Nanometer-sized metal particles constitute an unavoidable family of catalysts, combining the advantages of molecular complexes in regards to their catalytic performances and the ones of heterogeneous systems in terms of easy recycling. As part of this research, our group aims at designing well-defined metal nanoparticles based-catalysts, in non-conventional media (ionic liquids or water), for various catalytic applications (hydrogenation, dehalogenation, carbon-carbon coupling, asymmetric catalysis) in mild reaction conditions. In the drive towards a more eco-responsible chemistry, the main focuses rely on the search of highly active and selective nanocatalysts, in association with an efficient recycling mainly under pure biphasic liquid-liquid conditions. In this Personal Account, we proposed our almost fifteen-years odyssey in the world of metal nanoparticles for a sustainable catalysis.

SPECIFICATIONS OF RABI OSCILLATIONS IN THE QUANTUM EMITTERS SYSTEMS COUPLED TO THE LOCALIZED PLASMON POLARITONS

In this work phenomenon of resonant transfer of the excited energy between quantum dipole emitters (QDE) by the localized plasmon polaritons (LPP) is investigated. In system the molecules or semiconductor quantum dots act as QDEs and the nanometer size metal particles (MNP) care LPPs. The dependence of the frequency of Rabi oscillations on system parameters (the distance between MNP and QDE, the radius of MNP and dielectric permittivity of the surrounding medium) was determined. Conditions when the period of Rabi oscillations is considerably shorter than system relaxation time were defined.

Biocompatible silver nanoparticles embedded in a PEG–PLA polymeric matrix for stimulated laser light drug release

The laser-induced release of a well-known hepatoprotective drug (silibinin, SLB) from a temperature-sensitive polymeric composite loaded with silver nanoparticles (Ag NPs) was investigated. The surface chemistry tuning and the specific design of Ag NPs are fundamental in view of the engineering of specific stimuli-responsive systems, able to control drug release in response to external stimuli. The release profiles of SLB from the newly synthesized PEG–PLA@Ag composite show strong dependences on laser wavelength and Ag NPs’ Surface Plasmon Resonance (SPR). The resonant laser light excites the SPR of the NPs and the absorbed energy is converted into heat due to electron–photon collisions. The heat generated from the nanometer-sized metal particles embedded within the polymer is efficient and strongly localized. The nanovector, irradiated by a relatively low-intensity laser but tuned specifically to the metal NPs’ SPR, releases the encapsulated drug with a higher efficiency than that not irradiated or irradiated with a laser wavelength far from the metal SPR. A combination of analytical techniques including UV–Vis, NMR, and FT-IR spectroscopy and scanning/transmission electron microscopy has been used to study the structural and morphological properties of the composite. The controllable specificity of this approach and the possibility of the SPR-mediated localized photothermal effect to be usefully applied in aqueous environments are the relevant advances of the proposed system for photothermal therapies that make use of visible optical radiation or for the drug delivery in proximity of the tumor cells.

Ellipsometric Study on Size-Dependent Melting Point of Nanometer-Sized Indium Particles

Size-dependent melting properties of nanometer-sized Indium particles with size ranging from 25.5 to 68.1 nm were studied by spectroscopic ellipsometry, and a critical size is found between 42.4 and 44.9 nm. The melting points of nanometer-sized Indium particles with size larger than critical size are almost the same as that of bulk indium, while no clear melting point was found for indium particles with size smaller than the critical size. A knee point defined as the average melting point was introduced to characterize the melting of these smaller size particles, and it depresses with decreasing size. The mechanism for size dependent melting of indium particles was discussed. This work shows that spectroscopic ellipsometry is an effective optical tool for characterizing the melting of nanometer-sized metal particles.

Back Cover: Advanced Engineering Materials 6∕2015

Advanced Engineering MaterialsVolume 17, Issue 6 p. 914-914 Back CoverFree Access Back Cover: Advanced Engineering Materials 6∕2015 First published: 10 June 2015 https://doi.org/10.1002/adem.201570023AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract A simple and effective method has been developed to produce high performance and improved mechanical properties of sintered bulk MgB2 materials by adding the optimum silver amount. The picture shows a scanning electron microscopy image (upper part), presenting the large metallic Ag particles embedded in the void regions. The nanometer-sized metallic AgMg3 particles and their dispersion can be seen in the metallic MgB2 matrix by just different contrasts (bottom). Further details can be found in the article by Miryala Muralidhar and co-workers on pages 831. Volume17, Issue6June 2015Pages 914-914 RelatedInformation

Surface scattering contribution to the plasmon width in embedded Ag nanospheres.

Nanometer-sized metal particles exhibit broadening of the localized surface plasmon resonance (LSPR) in comparison to its value predicted by the classical Mie theory. Using our model for the LSPR dependence on non-local surface screening and size quantization, we quantitatively relate the observed plasmon width to the nanoparticle radius R and the permittivity of the surrounding medium ε(m). For Ag nanospheres larger than 8 nm only the non-local dynamical effects occurring at the surface are important and, up to a diameter of 25 nm, dominate over the bulk scattering mechanism. Qualitatively, the LSPR width is inversely proportional to the particle size and has a nonmonotonic dependence on the permittivity of the host medium, exhibiting for Ag a maximum at ε(m) ≈ 2.5. Our calculated LSPR width is compared with recent experimental data.

Attosecond Forces Imposed by Swift Electrons on Nanometer-Sized Metal Particles

1 Institute of Advanced Materials, Devices and Nanotechnology, Rutgers University, New Jersey USA. 2 Department of Physics and Astronomy, Rutgers University, New Jersey USA. 3 Department of Materials Science and Engineering, Rutgers University, New Jersey USA. 4 Instituto de Fisica, Benemerita Universidad Autόnoma de Puebla, Puebla Mexico. 5 Donostia International Physics Center of Physics, San Sebastian Spain.