Microstructural characterization of spray-dried NiO-8YSZ particles as plasma sprayable anode materials for metal-supported solid oxide fuel cell

The plasma spray method is widely used to produce NiO-8YSZ (composed of nickel oxide (NiO) and 8 mol% yttria-stabilized zirconia) anode layers in metal-supported solid oxide fuel cell (SOFC). Flowability control of microsized particles is important for achieving consistent performance of the SOFC anode layer. When microsized particles are fabricated via spray drying and sintering, the most significant factors that influence flowability are their sizes, distribution, and surface conditions. Thus, the aim of this study is to analyze the fabrication conditions for microsized NiO-8YSZ cermet particles made from a nanoscale, sinterable NiO-8YSZ dispersion solution by using an appropriate spray-drying and sintering process. The characteristics of the as-sprayed and sintered NiO-8YSZ composite particles (such as size, distribution, roughness, and nanostructure) were analyzed via field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), particle size distribution (PSD), Brunauer–Emmett–Teller (BET) surface area, and atomic force microscopy (AFM). The as-sprayed microsized NiO-8YSZ particles became smaller and more uniformly distributed as the rotational speed used for spray drying increased. As a result of sintering, the extent of shrinkage of as-sprayed microsized NiO-8YSZ particles generated at high RPMs was lower than that of particles formed at low RPMs. No significant difference was observed in the distribution of the nanosized NiO and 8YSZ particles at different rotational speeds. Furthermore, the highest BET surface areas were observed for particles generated at 8000 RPM before sintering at 13.74 m²/g. After sintering, the highest BET surface area was 0.94 m²/g for particles generated at 16,000 RPM. Differences in nanostructure and surface roughness between as-sprayed and sintered microsized NiO-8YSZ particles were identified via AFM. This study is expected to provide important fundamental information useful for optimizing SOFC efficiency by promoting flowability control during the production of SOFC anodes via plasma spraying.     

Study on the nitrogen transformation during the primary pyrolysis of sewage sludge by Py-GC/MS and Py-FTIR

The nitrogen transformation with attention to the intermediates and NO_x precursors has been investigated during the primary pyrolysis of sewage sludge by using Pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) and Pyrolyzer-Fourier transform infrared spectrometry (Py-FTIR). A three-stage process of nitrogen transformation during the sewage sludge pyrolysis was suggested. The decomposition of labile protein and inorganic ammonium salt mainly occurred in the first stage (<300 °C), giving rise to a small amount of NH₃. In the second stage (300–600 °C), the macromolecular protein firstly cracked into small molecular amine compounds, and then went through deamination process, contributed to a large release of NH₃. In the third stage (600–900 °C), the amine compounds converted into nitriles, and generated a large amount of HCN, while the formation of NH₃ slowed down accordingly.     

Co-precipitation synthesis of nanocrystalline SnO2: Effect of Fe doping on structural,morphological and ethanol vapor response properties

The present study describes undoped and Fe-doped tin dioxide thick films as selective ethanol vapor sensors. The undoped and Fe doped SnO₂ powders were synthesized by using a facile co-precipitation route. The thick films of undoped and Fe-doped SnO₂ were deposited by screen-printing technique and then sintered at 650 °C for 2 h. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) techniques. The XRD studies reveal formation of nanocrystalline structure. The particle size of undoped and Fe (2 and 4 mol%) doped SnO₂ sintered powders were 17, 10 and 8 nm, respectively. It was found that the response of SnO₂ improved on addition of Fe. The 2 mol% Fe doped SnO₂ exhibits highest response toward ethanol at the operating temperature of 300 °C with response and recovery time of 15 and 32 s, respectively.     

Covalent modification of graphene oxide with polynorbornene by surface-initiated ring-opening metathesis polymerization

Surface-initiated ring-opening metathesis polymerization (SI-ROMP) was employed to prepare polymer-grafted graphene oxide (GO). Grubbs catalysts were immobilized onto GO surfaces followed by ROMP of norbornene from these active catalyst sites to result in polynorbornene (PNb)-functionalized GO (GO-PNb), whose structure and morphology were fully characterized by FTIR, Raman, NMR, XRD, TGA and SEM. The as-prepared hybrid material of GO-PNb is an intercalated layer structure with an improved solubility in organic solvents. Further epoxidation of double bonds along the PNb chains resulted in the epoxidized PNb-functionalized GO (GO-ePNb). The relatively low and irregular grafting ratio of PNb on GO measured by gravimetry mainly result from the effect of complex GO surfaces and the chain-transfer reactions in the polymerization process.     

Preparation and evaluation of poly(2-hydroxyethyl aspartamide)-hexadecylamine-iron oxide for MR imaging of lymph nodes

The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C₁₆-iron oxide (PHEA-C₁₆-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C₁₆-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C₁₆-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C₁₆. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C₁₆-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C₁₆-iron oxide nanoparticles. Therefore, PHEA-C₁₆-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes.     

Development of paraffin and paraffin/bitumen composites with additions of B2O3 for thermal neutron shielding applications

In this work, paraffin and paraffin/bitumen composites with additions of boron oxide (B₂O₃) were prepared to evaluate the viscosity, flexural, and thermal neutron shielding properties for uses as thermal neutron shielding materials. The results showed that the addition of 3 wt% or 9 wt% bitumen to paraffin increased the overall flexural properties with the content of 9 wt% bitumen having the highest values. The improvement in flexural properties made the composites less brittle, stiffer, and longer-lasting. Furthermore, different contents of B₂O₃ (0, 7, 14, 21, 28, and 35 wt%) were added to paraffin and paraffin/bitumen composites to investigate the effects of the B₂O₃ contents. The results indicated that an increase in B₂O₃ contents improved the shielding properties but slightly reduced the flexural properties. Specifically for 5-mm paraffin and 5-mm paraffin/bitumen samples with 35 wt% of B₂O₃, both samples could reduce neutron flux by more than 70%. The overall results suggested that the paraffin and paraffin/bitumen composites with additions of B₂O₃ showed improved properties for utilization as effective thermal neutron shielding materials.     

Effect of vibration on behaviour of bifilms in A356 and A357 melts

The effect of applying vibration to a melt on the behaviour of bifilm defects in A356 and A357 melts was studied using a reduced pressure test technique. The results showed that vibrating a melt can have a dual effect on bifilms. This effect depends on the rate of phase transformations that occur in the oxide films. If the transformation occurs fast enough then the vibration would facilitate the formation of bonding between the layers of bifilm defects by causing the atmosphere of the defects to be consumed faster. Otherwise, the vibration might facilitate the diffusion of hydrogen into the atmosphere of the defects, and hence prevent or delay the formation of bonding between the oxide layers.     

Positron Emitting Magnetic Nanoconstructs for PET/MR Imaging

Hybrid PET/MRI scanners have the potential to provide fundamental molecular, cellular, and anatomic information essential for optimizing therapeutic and surgical interventions. However, their full utilization is currently limited by the lack of truly multi‐modal contrast agents capable of exploiting the strengths of each modality. Here, we report on the development of long‐circulating positron‐emitting magnetic nanoconstructs (PEM) designed to image solid tumors for combined PET/MRI. PEMs are synthesized by a modified nano‐precipitation method mixing poly(lactic‐co‐glycolic acid) (PLGA), lipids, and polyethylene glycol (PEG) chains with 5 nm iron oxide nanoparticles (USPIOs). PEM lipids are coupled with 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) and subsequently chelated to ⁶⁴Cu. PEMs show a diameter of 140 ± 7 nm and a transversal relaxivity r₂ of 265.0 ± 10.0 (mM × s)^?1, with a r₂/r₁ ratio of 123. Using a murine xenograft model bearing human breast cancer cell line (MDA‐MB‐231), intravenously administered PEMs progressively accumulate in tumors reaching a maximum of 3.5 ± 0.25% ID/g tumor at 20 h post‐injection. Correlation of PET and MRI signals revealed non‐uniform intratumoral distribution of PEMs with focal areas of accumulation at the tumor periphery. These long‐circulating PEMs with high transversal relaxivity and tumor accumulation may allow for detailed interrogation over multiple scales in a clinically relevant setting.     

Influence of Oxide Morphologies on Galvanizability of Third Generation Automotive Steel

Focusing on improving the galvanizability of the third generation automotive steel, the effect of surface ox ide morphologies on the galvanizability was studied. The results show that the surface oxide types of sample steels by X ray photoelectron spectroscopy （XPS） analysis after annealing in different conditions are the same. Only MnO, MnO2 and Cr2O3 were detected and no complex oxide exists on the surface. Morphologies of surface oxides can greatly influence the galvanizability of the third generation automotive steel. Nodule-like oxide surface can contribute to better wettability and inhibition layer than vitreous film like oxide surface. Galvanized panels of nodule-like oxide surface steels only show pinhole sized bare spots, while panels galvanized from vitreous film-like oxide surface steels reveal larger areas of bare spots and uncoated areas. Inhibition layer observed in galvanized panels of nodule-like oxide surface steels is compact but not homogeneous; some inhibition layer grains are fine, and others are coarse, while the inhibition layer grains of panels galvanized from vitreous film-like oxide surface steels have a non-compact morphology with some particularly fine equiaxed crystals which developed deficiently.