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Zirconium-89 (89Zr) is an emerging radionuclide for positron emission tomography (PET), with nuclear properties suitable for imaging slow biological processes in cellular targets. The 89Y(p,n)89Zr nuclear reaction is commonly exploited as the main production route with medical cyclotrons accelerating low-energy (< 20 MeV) and low-current (< 100 μA) proton beams. Usually, natural yttrium solid targets manufactured by different methods, including yttrium electrodeposition, yttrium sputtering, compressed yttrium powders, and foils, were employed. In this study, the Spark Plasma Sintering (SPS) technique has been investigated, for the first time, to manufacture yttrium solid targets for an efficient 89Zr radionuclide yield. The natural yttrium disc was bonded to a niobium backing plate using a commercial SPS apparatus and a prototype machine assembled at the University of Pavia. The resulting targets were irradiated in a TR19 cyclotron with a 12 MeV proton beam at 50 μA. A dedicated dissolution module, obtained from a commercial system, was used to develop an automated process for the purification and recovery of the produced 89Zr radionuclide. The production yield and recovery efficiency were measured and compared to 89Zr produced by irradiating standard yttrium foils. SPS manufactured targets withstand an average heat power density of approximately 650 W∙cm-2 for continuous irradiation up to 5 h without visible damage. A saturation yield of 14.12 ± 0.38 MBq/μAh was measured. The results showed that the obtained 89Zr production yield and quality were comparable to similar data obtained using standard yttrium foil targets. In conclusion, the present work demonstrates that the SPS technique might be a suitable technical manufacturing solution aimed at high-yield 89Zr radioisotope production.

Some aquaporins (AQPs) allow the diffusion of hydrogen peroxide (H2O2), the most abundant ROS, through the cell membranes. Therefore, the possibility of regulating the AQP-mediated permeability to H2O2, and thus ROS scavenging, appears particularly important for controlling the redox state of cells in physiological and pathophysiological conditions. Several compounds have been screened and characterized for this purpose. This study aimed to analyze the effect of cerium oxide nanoparticles (CNPs) presenting antioxidant activity on AQP functioning. HeLa cells express AQP3, 6, 8, and 11, able to facilitate H2O2. AQP3, 6, and 8 are expressed in the plasma membrane and intracellularly, while AQP11 resides only in intracellular structures. CNPs but not cerium ions treatment significantly increased the water and H2O2 permeability by interacting with AQP3, 6, and especially with AQP8. CNPs increased considerably the AQP-mediated water diffusion in cells with oxidative stress. Functional experiments with silenced HeLa cells revealed that CNPs increased the H2O2 diffusion mainly by modulating the AQP8 permeability but also the AQP3 and AQP6, even if to a lesser extent. Current findings suggest that CNPs represent a promising pharmaceutical agent that might potentially be used in numerous pathologies involving oxidative stress as tumors and neurodegenerative diseases.

In this work we report the synthesis of (Co,Mg,Mn,Ni,Zn)(Al,Co,Cr,Fe,Mn)2O4 in a single-phase spinel structure (space group Fd 3 ¯ m). The chemical homogeneity and purity of the sample were checked through X-ray diffraction, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The analysis of the pre-edge peaks of the X-ray absorption spectra for all the transition metals clearly indicated the presence of a partial degree of inversion in the spinel structure. This material is characterized by a particularly large configurational entropy, regarding both the A and the B sites, leading to a total value equal to 3.3 in R unit.

High-entropy oxides based on transition metals, such as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation into TM-HEO-based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed a high specific capacity exceeding 600 mAh g-1 at 0.1 C and Coulombic efficiency very close to unity. The combination of functional and advanced spectroscopic studies revealed complex charging mechanisms, developing through the reduction of transition-metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and incomplete, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account for the observed cycling behavior of the TM-HEO-based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ∼60% of lithiation capacity, so proving the beneficial role of the configuration entropy in enhancing the stability of the HEO rock-salt structure during the redox phenomena.

Enhancing electrode areal capacity of lithium-ion batteries will result in cost saving and better electrochemical performances. Additive manufacturing (AM) is a very promising solution, which enables to build structurally complex electrodes with well-controlled geometry, shape and thickness. Here we report on 3D-printed cathodes based on LiMn2O4 (LMO) as the active material, which are fabricated by robocasting AM via aqueous processing. Such a technology is: i) environmentally friendly, since it works well with water and green binders; ii) fast, due to very short deposition times and rapid drying process because of low amount of solvent in the printable pastes; iii) easily scalable. The cathodes are produced by extruding pastes with higher solid loadings (>70 vol %) than those typically reported in literature. The printing efficiency is strongly affected by both the binder and the carbonaceous additive. The best cathode is composed by LMO, Pluronic as the binder, and a mixture of graphite/carbon black as the electronic conductor, which is critical for achieving optimal electrochemical performance. The cathode with thickness of 200 μm and mass loading of 13 mg cm−2 exhibits good electrochemical areal capacity (2.3 mAh cm−2) and energy density (>32 J cm−2). Our results may boost the development of greener, lower cost and more efficient new generation of LIBs for applications as household energy storage or even micro-battery technology.

The mechanisms of CO oxidation on the Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O high-entropy oxide were studied by means of operando soft X-ray absorption spectroscopy. We found that Cu is the active metal and th...

The ever-growing demand for Li-ion batteries requires high-capacity electrode materials that should also be environmentally benign, Co-free, secure and durable, to achieve an optimal compromise between sustainability and functional performances. Spinel LiMn2O4 (LMO) is a state-of-the-art material, which, in principle, could satisfy such requirements. However, an undesired cubic-tetragonal phase transition favors Jahn-Teller (J-T) spinel distortion, leading to severe capacity reduction upon cycling below 3 V. Here, we propose a dual-doping strategy for LMO, based on the partial substitution of Mn(III) with Fe(III) and Ti(IV) to design new active materials for high-capacity cathodes, namely LiFexMn2-x-yTiyO4 (LFMT), with Li/Mn ratio ranging between 1 and 1.7. The substitution of Mn with Fe and Ti suppresses the J-T distortion, which is often still evident in the case of Ti-doped LMO. This allows cycling in a wider voltage range (4.8-1.5 V), thus resulting in higher capacity and significantly improved stability. The lithiation mechanisms were investigated by combining ex-situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS analyses). It demonstrated that the only redox-active metal is Mn, while Fe and Ti are electrochemically inactive. The extensive electrochemical lithiation/delithiation of the LFMT compositions brought to unprecedented results, which give evidence of stabilizing cation disorder through the formation of Mn-rich and Mn-poor domains, which leades to two spinel phases with different Mn:Ti ratios. These insights into the lithiation mechanism pave the way for a better understanding of the doping chemistry and electrochemistry of Mn-based spinels as cathode materials for Li-ion batteries.

The cellular uptake of nanoparticles (NPs) represents a critical step in nanomedicine and a crucial point for understanding the interaction of nanomaterials with biological systems. No specific mechanism of uptake has been identified so far, as the NPs are generally incorporated by the cells through one of the few well-known endocytotic mechanisms. Here, an alternative internalization route mediated by microvilli adhesion is demonstrated. This microvillus-mediated adhesion (MMA) has been observed using ceria and magnetite NPs with a dimension of

Transition metal-based sodium fluoro-perovskite of general formula NaMF3 (M = Fe, Mn, and Co) were investigated as cathode materials for rechargeable Na-ion batteries. Preliminary results indicated Na-ion reversible intercalation but highlighted the need to find optimization strategies to improve conductivity and to modulate the operating voltages within experimentally accessible electrolytes’ stability windows, in order to fully exploit their potential as high-voltage cathodes. In this study, we combined experimental and computational techniques to investigate structures, defects, and intercalation properties of the NaFe1-xMnxF3 and NaCo1-xMnxF3 systems. Through the use of a simple solvothermal synthesis, we demonstrated the possibility to modulate the sample’s morphology in order to obtain fine and dispersed powder samples. The structural results indicated the formations of two solid solutions with a perovskite structure over the entire compositional range investigated. Atomistic simulations suggested that Na-ion diffusion in these systems was characterized by relatively high migration barriers and it was likely to follow three-dimensional paths, thus limiting the effect of anti-site defects. The correlation between structural and computational data highlighted the possibility to modulate both ionic and electronic conductivity as a function of the composition.

(1) Background:The quality of neutron beams for Boron Neutron Capture Therapy (BNCT) is currently defined by its physical characteristics in air. Recommendations exist to define whether a designed beam is useful for clinical treatment. This work presents a new way to evaluate neutron beams based on their clinical performance and on their safety, employing radiobiological quantities. (2) Methods: The case study is a neutron beam for deep-seated tumors from a 5 MeV proton beam coupled to a beryllium target. Physical Figures of Merit were used to design five beams, however, they did not allow a clear ranking of their quality in terms of therapeutic potential. The latter was then evaluated based on in-phantom dose distributions and on the calculation of the Uncomplicated Tumor Control Probability (UTCP). The safety of the beams was also evaluated calculating the in-patient out-of-beam dosimetry. (3) Results: All the beams ensured a UTCP comparable to the one of a clinical beam in phantom, the safety criterion allowed to choose the best candidate. When this was tested in the treatment planning of a real patient treated in Finland, the UTCP was still comparable to the one of the clinical beam. (4) Conclusions: Even when standard physical recommendations are not met, radiobiological and dosimetric criteria demonstrate to be a valid tool to select an effective and safe beam for patient treatment.

Vascular oxidative stress is considered a worsening factor in the progression of Alzheimer’s disease (AD). Increased reactive oxygen species (ROS) levels promote the accumulation of amyloid-β peptide (Aβ), one of the main hallmarks of AD. In turn, Aβ is a potent inducer of oxidative stress. In early stages of AD, the concomitant action of oxidative stress and Aβ on brain capillary endothelial cells was observed to compromise the blood–brain barrier functionality. In this context, antioxidant compounds might provide therapeutic benefits. To this aim, we investigated the antioxidant activity of cerium oxide nanoparticles (CNP) in human cerebral microvascular endothelial cells (hCMEC/D3) exposed to Aβ oligomers. Treatment with CNP (13.9 ± 0.7 nm in diameter) restored basal ROS levels in hCMEC/D3 cells, both after acute or prolonged exposure to Aβ. Moreover, we found that the extent of CNP uptake by hCMEC/D3 was +43% higher in the presence of Aβ. Scanning electron microscopy and western blot analysis suggested that changes in microvilli structures on the cell surface, under pro-oxidant stimuli (Aβ or H2O2), might be involved in the enhancement of CNP uptake. This finding opens the possibility to exploit the modulation of endothelial microvilli pattern to improve the uptake of anti-oxidant particles designed to counteract ROS-mediated cerebrovascular dysfunctions.

The mechanisms of CO oxidation on the Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O high-entropy oxide were studied by means of operando soft X-ray absorption spectroscopy. We found that Cu is the active metal and that Cu(II) can be rapidly reduced to Cu(I) by CO when the temperature is higher than 130 °C. Co and Ni do not have any role in this respect. The Cu(II) oxidation state can be easily but slowly recovered by treatment of the sample with O2 at ca. 250 °C. However, it should be noted that CuO is readily and irreversibly reduced to Cu(I) when it is treated with CO at T > 100 °C. Thus, the main conclusion of this work is that the high configurational entropy of Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O stabilizes the rock-salt structure and permits the oxidation/reduction of Cu to be reversible, thus permitting the catalytic cycle to take place.

High entropy oxides based on transition metals, as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries, due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation on TM-HEO based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed high specific capacity exceeding 600 mAh g-1 at C/10 and Coulombic efficiency very close to unit. The combination of functional and advanced spectroscopic study revealed complex charging mechanisms, developing through an initial Li intercalation reaction during the first charging cycle, followed by the reduction of transition metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and not completed, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account the observed cycling behavior of the TM-HEO based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ~ 60% of lithiation delivered capacity, so proving the beneficial role of the configuration entropy to enhance the stability of the HEO rock-salt structure during the redox phenomena.

The preparation of pure Ca3Co4O9 materials in the form of dense bodies made of nano-sized grains was investigated by combining a sol-gel route, different thermal cycles, a ball-milling post-treatment and final densification with HP-FAST (High Pressure-Field Assisted Sintering). We found that an effective way for obtaining nano-sized compact bodies with only a marginal increase of the particle sizes of the original powder was the operation of HP-FAST at extremely high pressures (up to 430 MPa) and comparatively low temperatures. A ball-milling treatment before HP-FAST compaction was then required to hinder the large plastic deformation occurring when using these pressures. In contrast, un-milled powders could be densified by HP-FAST only at lower pressure and therefore required higher temperatures, thus losing their nanostructure. For all powders, X-ray absorption spectroscopy assessed a mean Co oxidation state slightly higher than III, coupled to absence of localized Co(II) and presence of localized Co(IV). Ball milling induced a decrease of the mean oxidation state of Co coupled to an increased disorder. The latter effect was confirmed by X-ray Absorption Fine Structure. Nanostructure had a complex effect on the different properties of compact bodies. According to the different conditions of HP-FAST, densities of 75–98% were achieved; the decrease in thermal conductivity was of a factor 2–3, while the electronic transport properties – in particular electrical conductivity – of nano-sized compact bodies were reduced to a larger extent with respect to their micro-sized counterparts. This demonstrates that, for bulk Ca3Co4O9 materials, nanostructure was not an effective approach toward a performing thermoelectric material.

Undoped as well as K-doped (40%), Y-doped (40%), Zr-doped (10%), and Mo-doped (12.5%) strontium barium niobate Sr0.5Ba0.5Nb2O6 (SBN50) materials have been investigated to explore the effect of heavy doping on the structural and functional properties (thermo-power, thermal and electrical conductivities) both in the as prepared (oxidized) and reduced states. For all materials, the EXAFS spectra at the Nb – K edge can be consistently analyzed with the same model of six shells around the Nb sites. Doping mostly gives a simple size effect on the structural parameters, but doping on the Nb sites weakens the Nb–O bond regardless of dopant size and charge. Shell sizes and Debye–Waller factors are almost unaffected by temperature and oxidation state, and the disorder is of static nature. The functional effects of heavy doping do not agree with a simple model of hole or electron injection by aliovalent substitutions on a large band gap semiconductor. With respect to the undoped samples, doping with Mo depresses the thermal conductivity by ~ 30%, Y doping enhances the electrical conductivity by an order of magnitude, while Zr doping increases the Seebeck coefficient by a factor of 2–3. Globally, the ZT efficiency factor of the K-, Y-, and Zr-doped samples is enhanced at least by one order of magnitude with respect to the undoped or Mo-doped materials., This work has been supported by the “Materiali Avanzati” Program (Projet code 2012-0815) of the Cariplo foundation (Milano, Italy). BM08 (LISA)@ESRF is acknowledged for the provision of beam-time, travel and accommodation expenses (Exp. HC-1582).

In the present work, we show a successful approach to achieve stable structural and optical changes induced by pressure on bulk amounts of MAPI after pressure release. Such effects on the optical properties resemble those achieved in situ (e.g., in diamond anvil cells) but are retained and stabilized under ambient conditions thanks to a partial quenching of the high-pressure state.

A structural and microstructural study was performed on several compositions of the Smy(FexNi1-x)4Sb12 system treated at three different pressures during the spark plasma sintering (SPS) process. Aim of the study is to recognize the effect of applied pressure at a fixed temperature on composition, microstrain and domains size, due to the relevance of these parameters in driving the thermoelectric properties of the material. Increasing pressure induces a change in the Sm amount, as well as an increase in microstrain and a decrease in the diffraction domains size. At the same time, enhancing pressure above a certain threshold promotes the formation of the extra phase (Sm,Fe,Ni)Sb2, and hence a large power factor reduction. Relying on data collected in this work, applying a pressure close to 180 MPa during SPS results to be a good compromise between advantages in terms of microstructure and transport properties, and disadvantages in terms of phase purity.

We investigated the interdiffusion process in nanostructured fluoritic oxides sintered by Field Assisted or Spark Plasma Sintering (FAST/SPS). Ceria and zirconia nanopowders were surface decorated with dopants, using simple solution techniques and then sintered at temperatures of 600–900 °C for very short times, under a pressure of 575 MPa. Remarkable ionic conductivity increase and phase composition alteration were observed after only 5 min of sintering. This rapid modification cannot be justified with regular bulk diffusion models, as cationic bulk diffusivity in these oxides is very limited at these temperatures. We propose an alternative model, involving only surface diffusion processes, justifying the apparently anomalous fast interdiffusion. This model helps clarifying some fundamental aspects of diffusion at the nanoscale when fast sintering is involved. We also evidenced as surface decoration coupled with FAST/SPS represents a simple alternative approach to the doping of oxides, which can be applied when other approaches are inconvenient.

Nanostructuring has been proposed as an effective strategy for the reduction of the phonon contribution to the thermal conductivity, resulting in an increase in the figure of merit of thermoelectric materials. However, obtaining bulk samples presenting high relative density and nanometric grain size can be quite challenging, particularly in the case of ceramic phases. Only few examples have been reported and none in the case of Ca3Co4O9. In this work, we used a sol-gel synthesis coupled with ball milling to prepare powders of Ca3Co4O9 presenting a grain size as small as 4 nm. These nanopowders were then sintered at different temperature and pressures using the High-Pressure Field-Assisted Sintering Technique (HP-FAST). Relative densities up to 95 vol% where obtained while maintaining a nanometric grain size. The microstructural and electrical properties of the sintered samples have been characterized. The results show that in this oxide a reduction to the nanometric grain size produces a drastic reduction in the electrical conductivity, which cannot be compensated by the reduction in the thermal conductivity. The Seebeck effect, on the other hand, appears to be affected only marginally by the grain size and porosity.

SrTiO3-BaTiO3 nanocomposites with tailored microstructures exhibit enhanced dielectric properties in comparison to homogeneous ceramics with the same overall composition, including stable permittivity (830 +/- 60) over a wide temperature range (-150 to 50 degrees C), low losses (

Preliminary studies for the design of an accelerator-based BNCT clinical facility are presented. The Beam Shaping Assembly neutron activation was evaluated experimentally and with Monte Carlo simulations. The activations of patient, air and walls in the room, the absorbed doses by the patient and the in-air dose distributions were evaluated. Based on these calculations, different walls compositions were tested to optimize the environmental conditions. Borated concrete, advantageously reducing the thermal flux in the room, was proven the best choice.

Hybrid polymer–ceramic electrolytes with high ceramic loading are currently investigated as a promising solution to achieve high safety and optimal mechanical properties in all-solid-state rechargeable batteries. In this study composite poly(ethylene oxide)/Li1.3Al0.3Ti1.7(PO4)3 (PEO/LATP) electrolytes, with and without lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the Li+ salt, were investigated through a combination of physicochemical and electrochemical techniques, including X-ray diffraction, scanning electron microscopy, thermal analysis, solid-state MAS-NMR and impedance spectroscopy. We were able to shed light on the interactions between the ceramic and the polymer phases, and on the mechanisms for Li+ transport. Membranes containing 70 wt% of LATP and 30 wt% of P(EO)15LiTFSI exhibit conductivity values of 4 × 10−5 Ω−1 cm−1 at 25 °C and in excess of 10−4 Ω−1 cm−1 at 45 °C. These promising results, obtained on a quasi-ceramic electrolyte through room temperature processing, suggest that further improvements in the transport properties of “polymer-in-ceramic” systems may be sought by increasing the amorphous polymer content, and by carefully investigating the role of the ceramic particles’ composition, dimensions and dispersion on the transport properties of the hybrid system.

Core–shell structures with ZnO cores have been widely investigated due to their effectiveness in suppressing surface defects of ZnO nanostructures. As the surface defects are hugely dependent on the synthesis conditions, it is important to understand the interactions between shell material and ZnO with different surface chemistry. Here we produce well-aligned ZnO nanorods using two growth methods, leading to ZnO with different surface chemistries. A thin layer of TiO2 shell is applied via layer-by-layer adsorption method. The core–shell structure is confirmed via high-resolution transmission electron microscopy. The optical properties and chemical states of both bare nanorods and core–shell structures are investigated and compared using photoluminescence (PL) measurement and x-ray photoelectron spectroscopy (XPS). Both PL and XPS results suggest surface defects are passivated by TiO2 shell coating. The shell coating has a stronger effect on ZnO synthesized in OH− rich environment, due to excessive hydroxyl groups provided during synthesis, which remain even after annealing-induced crystallization.

In Boron Neutron Capture Therapy, the boronated drug plays a leading role in delivering a lethal dose to the tumour. The effectiveness depends on the boron macroscopic concentration and on its distribution at sub-cellular level. This work shows a way to colocalize alpha particles and lithium ions tracks with cells. A neutron autoradiography technique is used, which combines images of cells with images of tracks produced in a solid-state nuclear track detector.

In this paper we report the influence of the absolute surface area (ASA) and aspect ratio (L/D) of hydrothermally grown ZnO nanorods (NRs) on the NO 2 and H 2 gases relative responses (RRs) in the 20 ppb − 1 ppm and 50 ppm–1000 ppm concentrations range. We used films of NRs characterized by different geometrical features, such as diameter, length, L/D and ASA, obtained using different growth times, but all showing a well-defined hexagonal shape and an alignment perpendicular to the substrate. Values of L/D up to 129 and NRs lengths up to 14 μm have been obtained; one of the highest reported for quasi-one-dimensional ZnO nanostructures obtained through solution-based one-pot syntheses. Electrical tests at 150 °C (NO 2 ) and 200 °C (H 2 ) carried out using films of NRs presenting different L/D evidenced a direct relationship between the increase of the ASA and L/D and gas RRs. The influence of geometrical and chemical characteristics, such as diameter, size and surface-defects concentration is also discussed in light of the existing literature. Cross sensitivity, investigated measuring the H 2 (target) response in the presence of NO 2 (interfering) gases as well as dynamic and cumulative NO 2 gas reproducibility test are also presented. Beside the considerable interference played by NO 2 to the H 2 response, our long NRs demonstrate an excellent reproducibility of the electrical signal and fast recovery of the base line, evidencing the absence of irreversible chemisorption or sample-surface “history-related” phenomena.

When used in prosthetic dentistry, zirconia encounters severe durability issues due to low temperature degradation: exposure to humidity results in a transition from tetragonal to monoclinic phase, associated to disruptive integrity loss. Recently it has been shown that size-induced stabilization helps maintaining zirconia in tetragonal form, when the grain size is reduced to the nano-range. Objective of this work is to demonstrate the applicability of High Pressure Field Assisted Sintering (HP-FAST) to the preparation of dense, nanostructured samples of tetragonal yttria stabilized zirconia, with yttria content between 0.5 and 3 mol% and showing resistance to low temperature degradation. The yttria stabilized zirconia nanopowders were prepared by a hydrothermal method. Sintering by HP-FAST was performed at 900 °C in 5 min, under a pressure of 620 MPa. Resistance to low temperature degradation was tested at 134 °C, under vapor pressure, for up to 40 h. Both pristine and aged samples were characterized by X-ray diffraction, high-resolution scanning electron microscopy and nanoindentation tests in continuous stiffness measurement mode. The sintered samples presented a grain size between 20 and 30 nm and low or null monoclinic content. Both parameters resulted unaffected by ageing. The best results in terms of phase composition and mechanical properties have been obtained with the material containing 1.5 mol% of yttria. These results induce to reconsider the use of yttria stabilized zirconia as material for dental prosthetic systems requiring long-term durability.

In the present work, we show a successful approach to achieve stable structural and optical changes induced by pressure on bulk amounts of MAPI after pressure release. Such effects on the optical properties resemble those achieved in situ (e.g., in diamond anvil cells) but are retained and stabilized under ambient conditions thanks to a partial quenching of the high-pressure state.

This paper presents a novel approach to manufacture and metalize a standard waveguide microwave filter, with a high dielectric resonator inserted in it. As a first step, a set of 3D-printed ABS plastic filaments have been measured, to establish their electrical properties and suitability for microwave design. Subsequently, a new commercial silver conductive lacquer has been tested to metalize a standard hollow WR-90 waveguide, printed by Fused Deposition Modeling (FDM) technique. This lacquer furnishes acceptable conductivity and proper shielding of the electromagnetic fields inside the structure, operating among microwave frequencies. In parallel, a special thin pellet, chemically synthesized, has been investigated and fabricated. This small cylindrical rod behaves like a high dielectric resonator, that has been employed to design a highly selective waveguide microwave filter, paving the road to the implementation of a novel class of microwave components and systems.

This paper highlights a novel methodology to synthesize and manufacture high dielectric resonator filters in microstrip line technology. While the adopted technology is well studied among the last decades, an innovative investigation among composite materials has been set up to create a high dielectric resonator, suitable for microwave applications. After a preliminary research, a special thin pellet has been chemically grown and manufactured. This small cylindrical rod will represents the high dielectric resonator, employed to couple the input and output microstrip lines, traced on standard commercial laminated substrates. The same specimen will be exploited to design, simulate and experimentally validate a pair of high selective filters, paving the road to the implementation of a novel class of components and systems operating among microwave frequencies.

ZnO sol–gel films, with and without embedded Pt nanoparticles, were used as seeding layers for the hydrothermal growth of ZnO nanorods. The morphology of the nanorods was controlled by adjusting the chemistry and processing, yielding samples with high transparencies and exposed surface areas. The prepared samples were assessed for performance as optical gas sensors in terms of absorbance variation and response time and these data were correlated with the structural properties. The nanorods grown on ZnO films containing Pt nanoparticles showed excellent H 2 -sensing properties owing to the high exposed surface areas of the ZnO nanorods and to the catalytic effect the underlying Pt nanoparticles.

The optical and conductometric responses of sol-gel-based ZnO thin films with embedded 5% mol. Au or Pt nanoparticles (NPs) have been compared at different operating temperatures, to assess the effect of noble metal additions on to H 2 , CO and NO 2 gases sensors response. The scanning electron microscopy and X-ray diffraction techniques have been utilized for morphological characterization of the crystal structures of the films after annealing at 400°C for 30 min and the effect of Au and Pt NPs additions on crystallite growth is discussed. Au NPs additions is effective to enhance the optical response to H 2 and CO at 390 nm and in the 500-700-nm wavelength range at 300- °C temperature. No optical response to NO 2 gas, even at low concentrations has been measured in the optical mode. The catalytic action of Pt NPs additions powerfully improves both the optical to H 2 and CO at 390 nm, and the conductometric gas responses. Detection limits as low as 20-ppb NO 2 and 50-ppm H 2 , in line with the best performances reported to the best of our knowledge in literature for ZnO-based sensors, have been measured in the conduction mode. Response times have been also compared, highlighting the positive effects played by Pt additions.

ZnO nanorods present great potential for application in optical, sensing and piezoelectric devices; thanks to their nanometric diameter and large surface area. In some of these applications a probing current must flow directly through the nanorods, requiring each nanorod to be directly connected to two electrodes. To attain this architecture a few solutions have been proposed in the past, mostly involving the use of complex and time-consuming procedures, but the large-scale production of such devices represents still a major challenge. We present here a new all-solution approach that allows the fabrication of extensive self-assembled, bi-dimensional networks of ZnO nanorods. Such networks can be easily produced on interdigitated electrodes with no need for any alignment, resulting directly in the formation of very robust devices. The entire process is fast, does not require any complex experimental apparatus and involves only the use of inexpensive and environmentally friendly chemical reagents. We demonstrate the potentiality of such networks in a gas sensing application, where these networks were able to detect NO2 at trace levels, at low temperatures, using UV-visible activation.