Search

The therapeutic effectiveness of anticancer drugs, including nanomedicines, can be enhanced with active receptor‐targeting strategies. Epidermal growth factor receptor (EGFR) is an important cancer biomarker, constitutively expressed in sarcoma patients of different histological types. The present work reports materials and in vitro biomedical analyses of silanized (passive delivery) and/or EGF‐functionalized (active delivery) ceria nanorods exhibiting highly defective catalytically active surfaces. The EGFR‐targeting efficiency of nanoceria was confirmed by receptor‐binding studies. Increased cytotoxicity and reactive oxygen species (ROS) production were observed for EGF‐functionalized nanoceria owing to enhanced cellular uptake by HT‐1080 fibrosarcoma cells. The uptake was confirmed by TEM and confocal microscopy. Silanized nanoceria demonstrated negligible/minimal cytotoxicity toward healthy MRC‐5 cells at 24 and 48 h, whereas this was significant at 72 h owing to a nanoceria accumulation effect. In contrast, considerable cytotoxicity toward the cancer cells was exhibited at all three times points. The ROS generation and associated cytotoxicity were moderated by the equilibrium between catalysis by ceria, generation of cell debris, and blockage of active sites. EGFR‐targeting is shown to enhance the uptake levels of nanoceria by cancer cells, subsequently enhancing the overall anticancer activity and therapeutic performance of ceria. [ABSTRACT FROM AUTHOR]

Synroc, a candidate nuclear wasteform and Synroc technology, a waste treatment solution utilizing hot‐isostatic pressing (HIPing) have significant potential for the immobilisation of challenging nuclear wastes from both current and innovative reactors and fuel cycles. Hot isostatic press (HIP) consolidation is undertaken within sealed metal HIP canisters, where metal buffers (e.g., Ti, Fe and Ni) can be incorporated to control the redox environment within the canister. This study, for the first time, reports the effect of varying Ti‐metal addition (0, 2, 4, and 8 wt.%) on phase formation, microstructural characteristics, and wasteform performance for HIP consolidated Synroc‐C containing 20 wt.% simulated PUREX type (PW‐4b) high level waste. Quantitative X‐ray diffraction analysis, scanning electron microscopy‐energy dispersive X‐ray spectroscopy (EDS) and transmission electron microscopy‐EDS analyses were undertaken for analytical investigations. The chemical durability of the samples was assessed using ASTM C1220‐21 standard test. Hot‐isostatically pressed (HIPed) samples with 0 and 8 wt.% Ti added for redox control produced unfavourable phase formation. However, the HIPed samples with Ti additions of 2 and 4 wt.% as a redox buffer showed the desired phase formation of Synroc‐C without any significant change to the partitioning of waste elements among the phases along with compatible durability results, when compared to previous literature for hot uniaxial pressing (HUPed) or sintered materials. [ABSTRACT FROM AUTHOR]

The present work reports a detailed interpretation of the role of Ga and Mn dopants, solid solubility mechanisms, charge compensation mechanisms, intervalence charge transfer, antibacterial performance, and cell attachment and proliferation. Sol–gel undoped and doped (1, 5, and 9 mol%) CeO2 films are spin‐coated on 3D printed Ti6Al4V biomedical alloy substrates and annealed at 650 °C for 2 h in air. Material characterization includes scanning electron microscopy (SEM), 3D scanning laser confocal microscopy, glancing angle X‐ray diffraction (GAXRD), and X‐ray photoelectron spectroscopy (XPS). In vitro testing includes inhibition of bacterial growth, simulated body fluid (SBF) testing, and cell attachment and proliferation studies. The most significant outcome is that the bioactivity of ceria derives directly from the Ce3+ concentration, which itself results from solid solubility (substitutional and interstitial) and charge compensation and redox. This challenges the common assumption of the dominance of oxygen vacancies in the performance of ceria. The antibacterial activity is dependent on the type, amount, and valence of the dopant, where opposite trends are observed for gram‐positive Staphylococcus aureus and gram‐negative Escherichia coli bacteria. All of the doped samples result in enhanced cell proliferation, although this is greatest at the lowest dopant concentration. Surface hydroxyapatite formation on the samples is achieved by soaking in SBF at 2 weeks and 1 month. [ABSTRACT FROM AUTHOR]

Synthesis methods for different nanoparticulate morphologies are of increasing importance since the morphological features determine the redox performance in many applications. However, the effects of synthesis variables on the formation of these morphologies are not well understood and previous work has been limited to relatively low [Ce] and [NaOH]. The present work reports an investigation of the morphological development of nanoceria through the examination of the key processing variables for precipitation and hydrothermal synthesis at high [Ce] and [NaOH]. Characterisation included XRD, Raman, TEM, HRTEM, SAED, XPS, and BET. The resultant refined morphological map delineates the effects of [NaOH] and temperature on the morphological evolution of ceria nanoparticles synthesised from Ce(NO3)3 aqueous solutions in terms of morphology and grain size. The data show that temperature dominates the morphology but elevated [NaOH] and temperature both increase the nanoparticle size. Compared to synthesis at low concentrations, high [Ce] also promotes grain growth, although this is secondary to the effect of [NaOH]. Significantly, the increased grain sizes also enhance the concentrations of catalytically active sites (Ce3+ and charge‐compensating oxygen vacancies). The present work provides a platform of fundamental concepts for the control of experimental variables to synthesise predictable nanoparticulate characteristics. [ABSTRACT FROM AUTHOR]

A contiguous carbonate‐rich hydroxyapatite microcoating in a microfluidic device represents a substrate that has chemical and structural similarity to bone mineral. The present work describes a low‐temperature method to deposit a carbonate‐rich hydroxyapatite microcoating on a glass slide and its incorporation within the microchannels of a microfluidic device. A glass slide is covered/masked with polypropylene‐based tape and CaCO3 nanoparticles are deposited on exposed areas by convective self assembly. The precursor CaCO3 is converted to carbonate‐rich hydroxyapatite by dissolution‐recrystallization in phosphate‐buffered saline. The microcoating is aligned/incorporated within a microchannel when the underlying glass is bonded to a polydimethylsiloxane structure with the device layout. X‐ray diffraction, laser Raman microspectroscopy, and X‐ray photoelectron spectroscopy indicate that the microcoating was comprised of carbonate‐rich hydroxyapatite. Scanning electron microscopy and 3D laser confocal microscopy showed that was comprised of nanocrystalline rod‐like clusters that collectively exhibit a thickness of ∼20 µm. Monocultures/cocultures of osteoblast‐lineage (MC3T3‐E1, MG63) and preosteoclast‐lineage (RAW 264.7) cells were performed. Osteoblast‐lineage cells adhered to the microcoating and deposited an extracellular matrix of collagen fibrils and mineral accretions. Mineralization was detected in/near the inlet wells. The microcoating is analogous to bone mineral and could be applied to various layouts and mineral systems. [ABSTRACT FROM AUTHOR]

Nanomaterials with cancer‐imaging and therapeutic properties have emerged as the principal focus of nanotheranostics. The past decade has experienced a significant increase in research in the design, formulation, and preclinical and clinical trials of theranostic nanosystems. However, current theranostic nanoformulations have yet to be approved by the FDA for clinical use. Consequently, the present review focuses on the importance of the careful examination of the in vivo preclinical status of specific nanotheranostic materials as a prerequisite for their clinical translation. The scope of coverage is structured according to all of the major organic, inorganic, 2D, and hybrid nanotheranostic materials and their in vivo preclinical status. The therapeutic advantages and limitations of these materials in animal models are considered and the various strategies to enhance the biocompatibility of theranostic nanoparticles are summarized. [ABSTRACT FROM AUTHOR]

Critical catalysis studies often lack elucidation of the mechanistic role of defect equilibria in solid solubility and charge compensation. This approach is applied to interpret the physicochemical properties and catalytic performance of a free‐standing 2D–3D CeO2−x scaffold, which is comprised of holey 2D nanosheets, and its heterojunctions with MoO3−x and RuO2. The band gap alignment and structural defects are engineered using density functional theory (DFT) simulations and atomic characterization. Further, the heterojunctions are used in hydrogen evolution reaction (HER) and catalytic ozonation applications, and the impacts of the metal oxide heteroatoms are analyzed. A key outcome is that the principal regulator of the ozonation performance is not oxygen vacancies but the concentration of Ce3+ and Ce vacancies. Cation vacancy defects are measured to be as high as 8.1 at% for Ru‐CeO2−x. The homogeneous distribution of chemisorbed, Mo‐oxide, heterojunction nanoparticles on the CeO2−x holey nanosheets facilitates intervalence charge transfer, resulting in the dominant effect and resultant ≈50% decrease in overpotential for HER. The heterojunctions are tested for aqueous‐catalytic ozonation of salicylic acid, revealing excellent catalytic performance from Mo doping despite the adverse impact of Ce vacancies. The present study highlights the use of defect engineering to leverage experimental and DFT results for band alignment. [ABSTRACT FROM AUTHOR]

Polyether‐ether‐ketone (PEEK) is one of the key materials used to fabricate intervertebral spacers due to its mechanical similarity to bone and non‐interference with imaging. However, its surface chemistry limits osseointegration, while its chemical unreactivity and low glass transition/melting temperature poses technical challenges to the application of coatings conducive to bone growth. The present work applies nature‐inspired interfacial and surface chemistry processes to encapsulate PEEK with nanocrystalline carbonate‐rich hydroxyapatite (C‐Ap), a bioactive mineral valued for its chemical/structural similarity to bone mineral and its bioresorbability. This technique is distinguished from previous work by the combined features of low‐temperature, multidirectional/rapid application, and additive‐free processing. The resultant nanocrystalline C‐Ap coating encapsulates PEEK, indicating suitability with standard and state‐of‐the‐art spacers, made by additive/subtractive techniques. A precursor CaCO3 layer is deposited on PEEK by nacre‐inspired convective self‐assembly, followed by a travertine‐inspired rapid (10 min) cold‐sintering treatment. The CaCO3 layer is converted to C‐Ap in phosphate buffered saline through dissolution‐recrystallization processes inspired by the hydrated layer of bone. The coatings exhibit contact pressures that are an order of magnitude higher than coatings deposited by the biomimetic method. There is potential for application to other orthopaedic materials and incorporation of biologics throughout the coating structure for sustained release. [ABSTRACT FROM AUTHOR]

Al‐Si3N4 couples were heat‐treated at 850‐1150°C for 250 hours. The thickness of the interacted area was measured by scanning electron microscopy (SEM) and scanning/transmission electron microscopy (TEM/STEM). The interaction rate increases exponentially with inverse temperature, with an activation energy of 194.23 kJ/mol and diffusion pre‐coefficient of 5 × 10−9 m2/s, indicating that the interaction is diffusion‐dependent. As the results showed, the interfacial area is comprised of Al alloy channels, Si precipitates, and AlN grains. Al‐Si transfer through the solid solution (Si3‐xAlxN4‐y) at the interface of Al alloy and β‐Si3N4 grains controls the kinetic of the interaction. When concentration of Al in solid solution exceeds a certain amount, it undergoes a topotactic phase transformation to form Al1‐xSixN1+y (viz., AlN). Next, the Al1‐xSixN1+y grains detach from the β‐Si3N4 grains and subsequently new Al‐Si3N4 interfaces are established. These interfaces repeat the interaction process, continuing until all the reactant is depleted. Thus, the interaction kinetics consist of a sequence of associated parabolic stages, precluding the observation of parabolic kinetics. [ABSTRACT FROM AUTHOR]

Al‐Si3N4 couples were heat‐treated at 850‐1150°C for 250 hours. The thickness of the interacted area was measured by scanning electron microscopy (SEM) and scanning/transmission electron microscopy (TEM/STEM). The interaction rate increases exponentially with inverse temperature, with an activation energy of 194.23 kJ/mol and diffusion pre‐coefficient of 5 × 10−9 m2/s, indicating that the interaction is diffusion‐dependent. As the results showed, the interfacial area is comprised of Al alloy channels, Si precipitates, and AlN grains. Al‐Si transfer through the solid solution (Si3‐xAlxN4‐y) at the interface of Al alloy and β‐Si3N4 grains controls the kinetic of the interaction. When concentration of Al in solid solution exceeds a certain amount, it undergoes a topotactic phase transformation to form Al1‐xSixN1+y (viz., AlN). Next, the Al1‐xSixN1+y grains detach from the β‐Si3N4 grains and subsequently new Al‐Si3N4 interfaces are established. These interfaces repeat the interaction process, continuing until all the reactant is depleted. Thus, the interaction kinetics consist of a sequence of associated parabolic stages, precluding the observation of parabolic kinetics. [ABSTRACT FROM AUTHOR]

The properties of mullite-glass and mullite-mullite interfaces have been investigated at 1800 K by molecular dynamics ( MD) simulation and high-resolution TEM. The simulation showed that mullite-glass interfaces typically have much lower interfacial energies than mullite-mullite interfaces, which results from the structural flexibility of the glass and associated accommodation of interfacial mismatch. The (110)-glass interface has the lowest energy of all interfaces studied, which is consistent with the observed dominance of this interface in experimental mullite-glass samples examined by TEM. The simulation shows that the interfacial energies of the (100)-glass and (010)-glass interfaces are higher than that those of the (001)-glass interface, so [100] and [010] would be expected to be the dominant growth directions. However, the growth of mullite in glass occurs predominantly in the [001] direction. This apparent discrepancy can be explained by the fact that growth in the [100] and [010] directions is limited by the slow growth of (110) plane (i.e., [110] direction), which facilitates [001] growth, which is confirmed by the TEM data. [ABSTRACT FROM AUTHOR]

The present work reports an investigation of the interactions of Al 7075 alloy and anorthite at 850°C (150 h) and 1150°C (24 h). Transmission electron microscopy, electron probe microanalysis, X-ray diffraction, and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to identify the mineralogical and microstructural changes at the metal-ceramic interface. At 850°C, the phase formation mechanisms were (a) Si4+-Al3+ interdiffusion between the Al alloy and anorthite to form calcium dialuminate ( CA2) and Ca2+-Mg2+ interdiffusion between the Al alloy and calcium dialuminate to form spinel. At 1150°C, spinel + Al2O3 and calcium hexaluminate ( CA6) + CA2 were the major and minor phase mixtures, respectively in the corroded area. A thin layer of calcium monoaluminate ( CA), gehlenite, and Si was present in the immediate vicinity of anorthite. The early stages of corrosion at 1150°C and 850°C were identical. However, due to thickening of the corroded region ( viz., spinel formation) and enhanced evaporation of Mg at the higher temperature, the interdiffusion path evolves from Si4+-Al3+ + Ca2+-Mg2+ to Si4+-Al3+ + Ca2+-Al3+, thus establishing the following phase evolution path at the interface: [ABSTRACT FROM AUTHOR]

A corrosion cup test was undertaken using BaAl2Si2O8 and Al4.1Zn3.2Mg alloy, heated in air for 150 h at 850°C. Electron probe microanalysis, X-ray diffraction, and scanning electron microscopy coupled with energy dispersive spectroscopy were used to identify the mineralogical and microstructural changes at the interfaces. The microstructural results revealed three microstructural areas: (1) Spinel layer with large numbers of Al alloy channels; (2) interfacial area with mainly alumina, spinel, and BaAl2Si2O8; and (3) interdiffusion zone chemically close to barium hexaaluminate. The principal observations are: BaAl2Si2O8 was highly resistant to molten Al alloy corrosion owing to sluggish kinetics, as evidenced by the observation of unreacted BaAl2Si2O8 grains in the interfacial area., The nature of the microstructure, particularly an interdiffusion zone instead of a continuous layer of precipitated alumina at the interface between the Al alloy channels and the unreacted BaAl2Si2O8 supports the conclusion that the corrosion mechanism is governed by interdiffusion (Si/Ba and Al/Mg) and substitution., The formation and limited retention of an MgO layer at the metal-ceramic interface played a critical role in alloy oxidation and the consequent interfacial phenomena. [ABSTRACT FROM AUTHOR]

The corrosion of duplex stainless steel 2205 was investigated both under service conditions and via an electrochemical study in chlorinated media. The steel sample surfaces showed pitting, crevice and selective dissolution, with the ferrite phase being more susceptible to dissolution in this media. The dissolution of MnS was identified to be a contributing factor for pitting corrosion, while electrochemical investigations revealed that the presence of hypochlorite ions caused a switching from a general corrosion phenomenon to a localized one. [ABSTRACT FROM AUTHOR]

Successful implementation of flexible photocatalysts (TiO2 films on polymeric substrates) has been hindered by the low photoactivity of the resultant amorphous films and difficulties with adhesion. In this work, thin films (~570 nm) of nanocrystalline TiO2 were deposited on PET sheets at room temperature using a novel sol-gel process. The precursor solution (titanium tetra-isopropoxide and propanol) was subjected to hydrolysis, peptisation, and condensation reactions in dilute HNO3 solution, followed by refluxing at 80°C/15 h to increase the crystallinity of TiO2 precursor. Dip-coating was used to apply the films on different substrates (PET/fused quartz), followed by drying/annealing at different temperatures, viz., 150°C/15 h on PET and 150°C/5 h, 350°C/5 h, and 500°C/5 h on fused quartz. The mineralogy, particle size/morphology, interfacial characteristics, crystallite sizes, transparency, photoactivity, and adhesion of the films were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), focussed ion beam milling (FIB), high-resolution transmission electron microscopy (HRTEM), UV-Visible spectrophotometry, methylene blue decomposition, and pull-off tape testing, respectively. The films dried/annealed at 150°C were highly transparent and comprised principally of crystalline anatase particles (~20 nm size); moreover, the films were strongly adhered to the PET sheets and displayed excellent photoactivity with regard to methylene blue degradation under UV irradiation. The superior photoactivity of these films is attributed to: (a) increased film surface area, which increased the number of reaction sites, and (b) decreased contamination of the films at lower temperatures. [ABSTRACT FROM AUTHOR]

The reduction of FeO-containing slag by blends of metallurgical coke and end-of-life tyres (RT) have been investigated through experiments conducted in a laboratory-scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with coke, RT, and blends of coke/RT (in four different proportions) were rapidly heated at 1550°C under high purity argon gas and the off gas was continuously analyzed for CO and CO2using an online infrared (IR) gas analyzer. The extent of reduction after 10 min, level of carburization and desulfurization, and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that the extent of reduction, level of carburization and desulfurization of the reduced metal are significantly improved when coke is blended with RT. Blending of coke with RT resulted in a decrease in direct CO2 emissions from the reduction reactions. [ABSTRACT FROM AUTHOR]

Bakelite is a thermoset plastic commonly found in electronic and automobile components. CaCO3 is generally found in the polymer as a filler material. Since it cannot be remelted, the disposal of this material has become an environmental issue. The present study investigates a new route to utilize waste bakelite as a source of carbon in EAF steelmaking process. This paper reports the carbon dissolution behaviour of bakelite/coke blends into liquid steel at 1550 °C. The carbon pick up in the liquid steel after reaction with varying blends of bakelite/coke for 30 minutes ranged between 0.13 wt% to 0.17 wt%; these were generally higher than that observed from coke alone (0.1 wt%). The dissolution rate (K) was also found to improve and the observed trend was BK2 (0.045 × 10−3 s−1) > BK3 (0.023 × 10−3 s−1) > BK1 (0.005 × 10−3 s−1) > coke (0.003 × 10−3 s−1). The reaction products formed at the interface after 30 minutes of contact between liquid steel and bakelite/coke blends were observed to be a CaS-Al2O3 complex. The presence of CaS in the interfacial layer due to the CaO in the ash, lowered melting temperature of the layer, thereby allowing for increased removal of the ash layer and greater carbon pick-up. The CaO is formed from the decomposition of CaCO3, and its presence was found to have a positive effect on modifying the properties of the coke, and thereby enhancing the carbon dissolution behaviour. [ABSTRACT FROM AUTHOR]

Metal foams are highly sought‐after porous structures for heterogeneous catalysis, which are fabricated by templating, injecting gas, or admixing blowing agents into a metallic melt at high temperatures. They also require additional catalytic material coating. Here, a low‐melting‐point liquid metal is devised for the single‐step formation of catalytic foams in mild aqueous environments. A hybrid catalytic foam fabrication process is presented via simultaneous chemical foaming, melting, and sintering reaction of liquid metal nanoparticles. As a model, nanoparticles of tertiary low‐melting‐point eutectic alloy of indium, bismuth, and tin (Field's metal) are processed with sodium hydrogen carbonate, an environmentally benign blowing agent. The competing endothermic foaming and exothermic sintering reactions are triggered by an aqueous acidic bath. The overall foaming process occurs at a localized temperature above 200 °C, producing submicron‐ to micron‐sized open‐cell pore foams with conductive cores and semiconducting surface decorations. The catalytic properties of the metal foams are explored for a range of applications including photo‐electrocatalysis, bacteria electrofiltration, and CO2 electroconversion. In particular, the Field's metal‐based foams show exceptional CO2 electrochemical conversion performance at low applied voltages. The facile process presented here can be extended to other low‐temperature post transition and transition metal alloys. [ABSTRACT FROM AUTHOR]