Surface undulation was formed while growing InGaN/GaN multi-quantum wells on a semi-polar m-plane (1-100) sapphire substrate. Two distinct facets, parallel to 112¯2 and 011¯1, were formed in the embedded multi-quantum wells (MQWs). The structural and luminescence characteristics of the two facets were investigated using transmission electron microscopy equipped with cathodoluminescence.
View Article and Find Full Text PDFMaterials (Basel)
April 2022
Real-time structural changes in Na-β″-alumina were observed in situ using transmission electron microscopy (TEM) with electron beam irradiation. Na-β″-alumina has been widely investigated as a solid electrolyte material for sodium-sulfur secondary batteries owing to its high ionic conductivity. This high conductivity is known to be due to the Na ions on the loosely packed conduction planes of Na-β″-alumina.
View Article and Find Full Text PDFTantalum nitride (TaN) thin films were grown utilizing an inductively coupled plasma (ICP) assisted direct current (DC) sputtering, and 20-100% improved microhardness values were obtained. The detailed microstructural changes of the TaN films were characterized utilizing transmission electron microscopy (TEM), as a function of nitrogen gas fraction and ICP power. As nitrogen gas fraction increases from 0.
View Article and Find Full Text PDFHigh-Solids Anaerobic co-Digestion (HS-AcD) of sewage sludge (biosolids) with the organic fraction of municipal solid waste is a promising waste management alternative due to high methane yields, lower reactor volume requirements, lower energy inputs, and less leachate production than liquid anaerobic digestion. This study evaluated the environmental and economic burdens and benefits of HS-AcD of biosolids, Food Waste (FW), and Yard Waste (YW) using Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) methods using Hillsborough County, Florida in the U.S.
View Article and Find Full Text PDFUtilization of biodegradable metals in biomedical fields is emerging because it avoids high-risk and uneconomic secondary surgeries for removing implantable devices. Mg and its alloys are considered optimum materials for biodegradable implantable devices because of their high biocompatibility; however, their excessive and uncontrollable biodegradation is a difficult challenge to overcome. Here, we present a novel method of inhibiting Mg biodegradation by utilizing reduced nicotinamide adenine dinucleotide (NADH), an endogenous cofactor present in all living cells.
View Article and Find Full Text PDFTi-doped nano MgAlO for white emission was synthesized by combustion method. Extrinsic Schottky defects, Al vacancies and Ti dopant in Al sites, which are considered to be responsible for bluish-white emission, were observed by STEM on the surface of Ti-doped nano MgAlO powder. The stabilities of the Schottky defect associates, (Ti-V''')'', were demonstrated by DFT calculation.
View Article and Find Full Text PDFIonic transport in the reverse direction of an electric field is caused by momentum transfer from free electrons to metal ions, i.e., electromigration (EM), which is a critical factor leading to copper (Cu) interconnect failure in integrated circuits under extreme operating conditions.
View Article and Find Full Text PDFGraphene oxide (GO) is reduced spontaneously when palladium nanoparticles are decorated on the surface. The oxygen functional groups at the GO surface near the nanoparticles are absorbed to the palladium to produce a palladium oxide interlayer. Palladium therefore grows on the GO with preferred orientations, resulting in unique microstructural and electrical properties.
View Article and Find Full Text PDFDue to the outstanding mechanical properties of individual carbon nanotubes (CNTs) at the nanoscale, CNT yarns are expected to demonstrate high strength at the macroscale. In this study, a predictable model was developed to predict the tensile strength of twisted CNT yarns. First, the failure mechanism of twisted CNT yarns was investigated using in situ tensile tests and ex situ observations.
View Article and Find Full Text PDFThe performance of carbon nanotube (CNT)-based devices strongly depends on the adhesion of CNTs to the substrate on which they were directly grown. We report on the bond strength of CNTs grown on a carbon fiber (T700SC Toray), measured via in situ pulling of individual CNTs inside a transmission electron microscope. The bond strength of an individual CNT, obtained from the measured pulling force and CNT cross-section, was very high (∼200 MPa), 8-10 times higher than that of an adhesion model assuming only van der Waals interactions (25 MPa), presumably due to carbon-carbon interactions between the CNT (its bottom atoms) and the carbon substrate.
View Article and Find Full Text PDFA novel nano-scale manipulator capable of handling low-dimensional materials with three-dimensional linear motion, gripping action, and push-pull action of the gripper was developed for an in situ experiment in transmission electron microscopy. X-Y-Z positioning and push-pull action were accomplished by a piezotubing system, combined with a specially designed assembly stage that consisted of a lever-action gripping tip backed by a push-pull piezostack. The gripper tip consisted of tungsten wire fabricated by electrochemical etching followed by a focused ion beam process.
View Article and Find Full Text PDFVertically ordered nanotube array is a desirable configuration to improve gas sensing properties of the hematite which is the most abundant and cheapest metal oxide semiconductor on earth but has low and sluggish chemiresistive responses. We have synthesized a vertically aligned, highly ordered hematite nanotube array directly on a patterned SiO2/Si substrate and then it used as a gas sensor without additional processing. The nanotube array sensor shows unprecedentedly ultrahigh and selective responses to acetone with detection limits down to a few parts per billion and response time shorter than 3 s.
View Article and Find Full Text PDFThe evolution of copper-based interconnects requires the realization of an ultrathin diffusion barrier layer between the Cu interconnect and insulating layers. The present work reports the use of atomically thin layer graphene as a diffusion barrier to Cu metallization. The diffusion barrier performance is investigated by varying the grain size and thickness of the graphene layer; single-layer graphene of average grain size 2 ± 1 μm (denoted small-grain SLG), single-layer graphene of average grain size 10 ± 2 μm (denoted large-grain SLG), and multi-layer graphene (MLG) of thickness 5-10 nm.
View Article and Find Full Text PDFGraphene oxide potentially has multiple applications and is typically prepared by solution-based chemical means. To date, the synthesis of a monolithic form of graphene oxide that is crucial to the precision assembly of graphene-based devices has not been achieved. Here we report the physical approach to produce monolithic graphene oxide sheets on copper foil using solid carbon, with tunable oxygen-to-carbon composition.
View Article and Find Full Text PDFWe present a new synthetic process of near infrared (NIR)-absorbing copper-indium-selenide (CISe) quantum dots (QDs) and their applications to efficient and completely heavy-metal-free QD-sensitized solar cells (QDSCs). Lewis acid-base reaction of metal iodides and selenocarbamate enabled us to produce chalcopyrite-structured CISe QDs with controlled sizes and compositions. Furthermore, gram-scale production of CISe QDs was achieved with a high reaction yield of ~73%, which is important for the commercialization of low-cost photovoltaic (PV) devices.
View Article and Find Full Text PDFAlthough different kinds of metal oxide nanoparticles continue to be proposed as anode materials for lithium ion batteries (LIBs), their cycle life and power density are still not suitable for commercial applications. Metal oxide nanoparticles have a large storage capacity, but they suffer from the excessive generation of solid-electrolyte interphase (SEI) on the surface, low electrical conductivity, and mechanical degradation and pulverization resulted from severe volume expansion during cycling. Herein we present the preparation of mesoporous iron oxide nanoparticle clusters (MIONCs) by a bottom-up self-assembly approach and demonstrate that they exhibit excellent cyclic stability and rate capability derived from their three-dimensional mesoporous nanostructure.
View Article and Find Full Text PDFSci Technol Adv Mater
February 2013
Deformation and work hardening behavior of Fe-17Mn-0.02C steel containing -martensite within the austenite matrix have been investigated by means of microstructural observations and x-ray diffraction analysis. During deformation, the steel shows the deformation-induced transformation of austenite → -martensite → '-martensite as well as the direct transformation of austenite → '-martensite.
View Article and Find Full Text PDFACS Appl Mater Interfaces
April 2013
We report the fabrication of graphene-encapsulated nanoballs with copper nanoparticle (Cu NP) cores whose size range from 40 nm to 1 μm using a solid carbon source of poly(methyl methacrylate) (PMMA). The Cu NPs were prone to agglomerate during the annealing process at high temperatures of 800 to 900 °C when gas carbon source such as methane was used for the growth of graphene. On the contrary, the morphologies of the Cu NPs were unchanged during the growth of graphene at the same temperature range when PMMA coating was used.
View Article and Find Full Text PDFToday, state-of-the-art III-Ns technology has been focused on the growth of c-plane nitrides by metal-organic chemical vapor deposition (MOCVD) using a conventional two-step growth process. Here we show that the use of graphene as a coating layer allows the one-step growth of heteroepitaxial GaN films on sapphire in a MOCVD reactor, simplifying the GaN growth process. It is found that the graphene coating improves the wetting between GaN and sapphire, and, with as little as ~0.
View Article and Find Full Text PDFWe report on a case of severe hepatotoxicity in a 52-year-old male with multiple myeloma (MM) who had received bortezomib therapy. At patient presentation, liver enzymes were normal, but started to markedly increase 3 days after the patient's second dose of bortezomib was administered, when free kappa light chains were noticeably reduced in the serum. After discontinuation of bortezomib, liver enzymes recovered gradually to baseline.
View Article and Find Full Text PDFMultimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, a sol-gel reaction of tantalum(V) ethoxide in a microemulsion containing Fe(3)O(4) nanoparticles (NPs) was used to synthesize multifunctional Fe(3)O(4)/TaO(x) core/shell NPs, which were biocompatible and exhibited a prolonged circulation time. When the NPs were intravenously injected, the tumor-associated vessel was observed using computed tomography (CT), and magnetic resonance imaging (MRI) revealed the high and low vascular regions of the tumor.
View Article and Find Full Text PDFLarge-area graphene films are best synthesized via chemical vapour and/or solid deposition methods at elevated temperatures (~1,000 °C) on polycrystalline metal surfaces and later transferred onto other substrates for device applications. Here we report a new method for the synthesis of graphene films directly on SiO(2)/Si substrates, even plastics and glass at close to room temperature (25-160 °C). In contrast to other approaches, where graphene is deposited on top of a metal substrate, our method invokes diffusion of carbon through a diffusion couple made up of carbon-nickel/substrate to form graphene underneath the nickel film at the nickel-substrate interface.
View Article and Find Full Text PDFBackground: Non-dippers were reported as showing different left atrial function, compared to dippers, but no study to date investigated the changes in the left atrial function according to the diurnal blood pressure pattern, using tissue Doppler and strain imaging.
Methods: Forty never treated hypertensive patients between 30 and 80 years of age were enrolled in this study. Patients were classified as non-dippers when, during night time, they had a blood pressure decrease of less than 10%.
Uniform and extremely small-sized iron oxide nanoparticles (ESIONs) of < 4 nm were synthesized via the thermal decomposition of iron-oleate complex in the presence of oleyl alcohol. Oleyl alcohol lowered the reaction temperature by reducing iron-oleate complex, resulting in the production of small-sized nanoparticles. XRD pattern of 3 nm-sized nanoparticles revealed maghemite crystal structure.
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