Structural and mechanistic insights into low-temperature CO oxidation over a prototypical high entropy oxide by Cu L-edge operando soft X-ray absorption spectroscopy.

High entropy oxides (HEOs) are an emerging class of materials constituted by multicomponent systems that are receiving special interest as candidates for obtaining novel and desirable properties. In this study we present a detailed investigation of the relevant intermediates arising at the surface of the prototypical HEO Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O during low-temperature CO oxidation. By combining Cu L2,3-edge operando soft X-ray absorption spectroscopy (soft-XAS) with density functional theory simulations and in situ FT-IR spectroscopy, we propose that upon HEO exposure to CO at 235 °C reduced Cu(I) sites arise mostly coordinated to activated CO molecules and partly to bidentate carbonate species. When the HEO surface is then exposed to a stoichiometric mixture of CO + 1/2O2 at 250 °C, CO2 is produced while bidentate carbonate moieties remain interacting with the Cu(I) sites. We structurally characterize the carbonate and CO preferential adsorption geometries on the Cu(I) surface metal centers, and find that CO adopts a bent conformation that may energetically favor its subsequent oxidation. The unique surface, structural and electronic sensitivity of soft-XAS coupled with the developed data analysis work-flow and supported by FT-IR spectroscopy may be beneficial to characterize often elusive surface properties of systems of catalytic interest.

Growth Mechanisms of ZnO Micro-Nanomorphologies and Their Role in Enhancing Gas Sensing Properties.

Zinc oxide (ZnO) is one of the main functional materials used to realize chemiresistive gas sensors. In addition, ZnO can be grown through many different methods obtaining the widest family of unique morphologies. However, the relationship between the ZnO morphologies and their gas sensing properties needs more detailed investigations, also with the aim to improve the sensor performances. In this work, seven nanoforms (such as leaves, bisphenoids, flowers, needles, etc.) were prepared through simple wet chemical synthesis. Morphological and structural characterizations were performed to figure out their growth mechanisms. Then, the obtained powders were deposited through screen-printing technique to realize thick film gas sensors. The gas sensing behavior was tested toward some traditional target gases and some volatile organic compounds (acetone, acetaldehyde, etc.) and compared with ZnO morphologies. Results showed a direct correlation between the sensors responses and the powders features (morphology and size), which depend on the specific synthesis process. The sensors can be divided in two behavioral classes, following the two main morphology kinds: aggregates of nanocrystals (leaves and bisphenoids), exhibiting best performances versus all tested gases and monocrystal based (stars, needle, long needles, flowers, and prisms).

High-Throughput Preparation of Metal Oxide Nanocrystals by Cathodic Corrosion and Their Use as Active Photocatalysts.

Nanoparticle metal oxide photocatalysts are attractive because of their increased reactivity and ease of processing into versatile electrode formats; however, their preparation is cumbersome. We report on the rapid bulk synthesis of photocatalytic nanoparticles with homogeneous shape and size via the cathodic corrosion method, a simple electrochemical approach applied for the first time to the versatile preparation of complex metal oxides. Nanoparticles consisting of tungsten oxide (H2WO4) nanoplates, titanium oxide (TiO2) nanowires, and symmetric star-shaped bismuth vanadate (BiVO4) were prepared conveniently using tungsten, titanium, and vanadium wires as a starting material. Each of the particles were extremely rapid to produce, taking only 2-3 min to etch 2.5 mm of metal wire into a colloidal dispersion of photoactive materials. All crystalline H2WO4 and BiVO4 particles and amorphous TiO2 were photoelectrochemically active toward the water oxidation reaction. Additionally, the BiVO4 particles showed enhanced photocurrent in the visible region toward the oxidation of a sacrificial sulfite reagent. This synthetic method provides an inexpensive alternative to conventional fabrication techniques and is potentially applicable to a wide variety of metal oxides, making the rapid fabrication of active photocatalysts with controlled crystallinity more efficient.

Deciphering Local Structural Complexity in Zn/Ga-ZrO2 CO2 Hydrogenation Catalysts.

In the last few decades, massive effort has been expended in heterogeneous catalysis to develop new materials presenting high conversion, selectivity, and stability even under high-temperature and high-pressure conditions. In this context, CO2 hydrogenation is an interesting reaction where the catalyst local structure is strongly related to the development of an active and stable material under hydrothermal conditions at T/P > 300 °C/30 bar. In order to clarify the relationship between catalyst local ordering and its activity/stability, we herein report a combined laboratory and synchrotron investigation of aliovalent element (Ce/Zn/Ga)-containing ZrO2 matrixes. The results reveal the influence of similar average structures with different short-range orderings on the catalyst properties. Moreover, a further step toward the comprehension of the oxygen vacancy formation mechanism in Ce- and Ga-ZrO2 catalysts is reported. Finally, the reported results illustrate a robust method to guide local structure determination and ultimately help to avoid overuse of the "solid solution" definition.

Highly Efficient and Reproducible Sonochemical Synthesis of ZnO Nanocrystals.

Sonochemical synthesis can be a facile, fast, efficient, versatile and economical way to prepare a large variety of conventional or novel nanostructured materials (metallic, magnetic, semiconducting, polymeric, etc.). In this work, zinc oxide nanocrystals were synthesized by irradiating and heating at 90 °C in a commercial ultrasonic bath a water solution of zinc nitrate hexahydrate and ammonia solution or hexamethylenetetramine as base catalysts. The evolution of the powder morphology and its crystalline structure were investigated at different times of ultrasonic irradiation (0-9 hours) and compared with those of samples obtained by only heating the solutions in a muffle furnace in order to enlighten the growth mechanism. It resulted that: i) the crystal morphology depends on the selected base, ii) for samples obtained by using ultrasounds, the homogeneity of the powders depends on the irradiation time, iii) by comparing all samples obtained at 7 hours of heating, the aspect ratio of the crystals is higher for those that also underwent to ultrasounds.

Tau seeding activity in skin biopsy differentiates tauopathies from synucleinopathies.

Most neurodegenerative diseases lack definitive diagnostic tests, and the identification of easily accessible and reliable biomarkers remains a critical unmet need. Since tau protein is highly expressed in skin of tauopathies patients, we aimed to exploit the ultrasensitive seeding activity assay (SAA) to assess tau seeding activity in skin of patients with tauopathies. In this multicentric, case-control study, patients with tauopathies and synucleinopathies were consecutively recruited and sex-matched to healthy controls (HC). Subjects underwent a double 3 mm skin biopsy in cervical area and ankle. Skin tau-SAA, using TauK18 and TauK19 as reaction substrates for 4R and 3R isoforms, seeding score, clinical scales, biochemical and morphological characterization of SAA end-products were evaluated. We analyzed 58 subjects: 24 tauopathies (18 progressive supranuclear palsy, PSP, and 6 corticobasal degeneration, CBD), 20 synucleinopathies (14 Parkinson's disease, PD, and 6 multiple system atrophy, MSA), and 14 HC. PSP and CBD showed higher tau seeding activity at both anatomical sites. A greater sensitivity of 4R-SAA than 3R-SAA was observed. 4R tau-SAA identified tauopathies with 71% sensitivity and 93% specificity. Accuracy was higher for PSP than CBD: PSP vs HC / PD (AUC 0.825), while CBD vs HC / PD (AUC 0.797), and PSP vs MSA (AU 0.778). SAA end-products showed differences in biochemical and morphological characterization according to the anatomical site. Skin tau-SAA identifies tauopathies with good accuracy and can be used to implement the in-vivo clinical diagnosis of patients with neurodegenerative diseases. Further characterization of peripheral tau seed in skin may elucidate the structure of tau deposits in brain.

Effect of water and ammonia on surface species formed during NO(x) storage-reduction cycles over Pt-K/Al2O3 and Pt-Ba/Al2O3 catalysts.

The effect of water, in the temperature range 25-350 °C, and ammonia at RT on two different surface species formed on Pt-K/Al2O3 and Pt-Ba/Al2O3 NSR catalysts during NO(x) storage-reduction cycles was investigated. The surface species involved are nitrates, formed during the NO(x) storage step, and isocyanates, which are found to be intermediates in N2 production during reduction by CO. FT-IR experiments demonstrate that the dissociative chemisorption of water and ammonia causes the transformation of the bidentate nitrates and linearly bonded NCO(-) species into more symmetric species that we call ionic species. In the case of water, the effect on nitrates is observable at all the temperatures studied; however, the extent of the transformation decreases upon increasing temperature, consistent with the decreased extent of dissociatively adsorbed water. It was possible to hypothesize that the dissociative chemisorption of water and ammonia takes place in a competitive way on surface sites able to give bidentate nitrates and linearly bonded NCO(-) that are dislocated, remaining on the surface as ionic species.

From Lab to Technical CO2 Hydrogenation Catalysts: Understanding PdZn Decomposition.

The valorization of CO2 to produce high-value chemicals, such as methanol and hydrocarbons, represents key technology in the future net-zero society. Herein, we report further investigation of a PdZn/ZrO2 + SAPO-34 catalyst for conversion of CO2 and H2 into propane, already presented in a previous work. The focus of this contribution is on the scale up of this catalyst. In particular, we explored the effect of mixing (1:1 mass ratio) and shaping the two catalyst functions into tablets and extrudates using an alumina binder. Their catalytic performance was correlated with structural and spectroscopic characteristics using methods such as FT-IR and X-ray absorption spectroscopy. The two scaled-up bifunctional catalysts demonstrated worse performance than a 1:1 mass physical mixture of the two individual components. Indeed, we demonstrated that the preparation negatively affects the element distribution. The physical mixture is featured by the presence of a PdZn alloy, as demonstrated by our previous work on this sample and high hydrocarbon selectivity among products. For both tablets and extrudates, the characterization showed Zn migration to produce Zn aluminates from the alumina binder phase upon reduction. Moreover, the extrudates showed a remarkable higher amount of Zn aluminates before the activation rather than the tablets. Comparing tablets and extrudates with the physical mixture, no PdZn alloy was observed after activation and only the extrudates showed the presence of metallic Pd. Due to the Zn migration, SAPO-34 poisoning and subsequent deactivation of the catalyst could not be excluded. These findings corroborated the catalytic results: Zn aluminate formation and Pd0 separation could be responsible for the decrease of the catalytic activity of the extrudates, featured by high methane selectivity and unconverted methanol, while tablets displayed reduced methanol conversion to hydrocarbons mainly attributed to the partial deactivation of the SAPO-34.

Photoreduction of mesoporous In2O3: mechanistic model and utility in gas sensing.

A model is proposed for the drop in electronic resistance of n-type semiconducting indium oxide (In(2)O(3)) upon illumination with light (350 nm, 3.5 eV) as well as for the (light-enhanced) sensitivity of In(2)O(3) to oxidizing gases. Essential features of the model are photoreduction and a rate-limiting oxygen-diffusion step. Ordered, mesoporous In(2)O(3) with a high specific surface area serves as a versatile system for experimental studies. Analytical techniques comprise conductivity measurements under a controlled atmosphere (synthetic air, pure N(2)) and temperature-resolved in-situ Fourier transform infrared (FTIR) spectroscopy. IR measurements reveal that oxygen vacancies form a donor level 0.18 eV below the conduction band.

Nanosized SnO2 Prepared by Electrospinning: Influence of the Polymer on Both Morphology and Microstructure.

An electrospinning (ES) procedure of polymeric solutions containing metal oxide precursors, followed by thermal treatments, was exploited to obtain SnO2 nanofibers. Attention was focused on the effect of different templating polymers (polyvinyl pyrrolidone (PVP), polyethylene oxide (PEO) and polyvinyl acetate (PVAc)) on the morphologies and particle size distributions of SnO2. We demonstrated that with different polymers, the final oxide's morphology and crystallite size change. Defined fibers, with homogeneous diameter, were obtained with each polymer, but, after calcination, the morphology of the oxide changes, leading to fibers, "flakes" or "sphere-shaped" particles when PVP, PEO or PVAc were used, respectively, as evidenced by SEM images. Data from HR-TEM and XRD measurements confirm that SnO2 samples consist of crystalline cassiterite, with small mean particle dimensions calculated by Debye-Scherrer equation, i.e., 30, 11 and 25 nm with PVP, PEO and PVAc, respectively. TEM measurements put in evidence lower average particle sizes and for SnO2 obtained with PEO average size of 8.5 nm with a standard deviation of ±4.9 nm was evidenced. By applying different calcination temperatures on fiber mat obtained by the same polymer, i.e., PEO, the influence of polymer not only on the final shape of the oxide particles but also on the crystallite size was definitively demonstrated.

(Ti,Sn) Solid Solution Based Gas Sensors for New Monitoring of Hydraulic Oil Degradation.

The proper operation of a fluid power system in terms of efficiency and reliability is directly related to the fluid state; therefore, the monitoring of fluid ageing in real time is fundamental to prevent machine failures. For this aim, an innovative methodology based on fluid vapor analysis through metal oxide (shortened: MOX) gas sensors has been developed. Two apparatuses were designed and realized: (i) A dedicated test bench to fast-age the fluid under controlled conditions; (ii) a laboratory MOX sensor system to test the headspace of the aged fluid samples. To prepare the set of MOX gas sensors suitable to detect the analytes' concentrations in the fluid headspace, different functional materials were synthesized in the form of nanopowders, characterizing them by electron microscopy and X-ray diffraction. The powders were deposited through screen-printing technology, realizing thick-film gas sensors on which dynamical responses in the presence of the fluid headspace were obtained. It resulted that gas sensors based on solid solution TixSn1-xO2 with x = 0.9 and 0.5 offered the best responses toward the fluid headspace with lower response and recovery times. Furthermore, a decrease in the responses (for all sensors) with fluid ageing was observed.

Development of an easy portable procedure for on-site determination of mercury and methylmercury.

A portable measurement and speciation procedure for inorganic mercury (HgIN) and methylmercury (CH3Hg) was developed. A portable sample pretreatment was optimized to determine total mercury content. A new home-made sorbent (CYXAD, CHYPOS 101 modified Amberlite XAD), was prepared to separate HgIN and CH3Hg. Mercury species were determined using square wave anodic stripping voltammetry (SW-ASV) with a solid gold electrode (SGE) and using a portable potentiostat. A certified reference material, five freeze-dried samples and three fresh samples were analysed with conventional voltammetric analyzer, after dissolution of the samples in microwave oven, and with a portable potentiostat after the mild eating procedure. The results obtained by SW-ASV were compared with those obtained using Direct Mercury Analyser (DMA). The quantification with the portable method is comparable to that obtained with the DMA. Retention tests showed the selectivity of CYXAD for HgIN, its stability and the possibility to re-use the same aliquot of resin.

Multifunctional Catalyst Combination for the Direct Conversion of CO2 to Propane.

The production of carbon-rich hydrocarbons via CO2 valorization is essential for the transition to renewable, non-fossil-fuel-based energy sources. However, most of the recent works in the state of the art are devoted to the formation of olefins and aromatics, ignoring the rest of the hydrocarbon commodities that, like propane, are essential to our economy. Hence, in this work, we have developed a highly active and selective PdZn/ZrO2+SAPO-34 multifunctional catalyst for the direct conversion of CO2 to propane. Our multifunctional system displays a total selectivity to propane higher than 50% (with 20% CO, 6% C1, 13% C2, 10% C4, and 1% C5) and a CO2 conversion close to 40% at 350 °C, 50 bar, and 1500 mL g-1 h-1. We attribute these results to the synergy between the intimately mixed PdZn/ZrO2 and SAPO-34 components that shifts the overall reaction equilibrium, boosting CO2 conversion and minimizing CO selectivity. Comparison to a PdZn/ZrO2+ZSM-5 system showed that propane selectivity is further boosted by the topology of SAPO-34. The presence of Pd in the catalyst drives paraffin production via hydrogenation, with more than 99.9% of the products being saturated hydrocarbons, offering very important advantages for the purification of the products.

Alpha-synuclein oligomers and small nerve fiber pathology in skin are potential biomarkers of Parkinson's disease.

The proximity ligation assay (PLA) is a specific and sensitive technique for the detection of αSyn oligomers (αSyn-PLA), early and toxic species implicated in the pathogenesis of PD. We aimed to evaluate by skin biopsy the diagnostic and prognostic capacity of αSyn-PLA and small nerve fiber reduction in PD in a longitudinal study. αSyn-PLA was performed in the ankle and cervical skin biopsies of PD (n = 30), atypical parkinsonisms (AP, n = 23) including multiple system atrophy (MSA, n = 12) and tauopathies (AP-Tau, n = 11), and healthy controls (HC, n = 22). Skin biopsy was also analyzed for phosphorylated αSyn (P-αSyn) and 5G4 (αSyn-5G4), a conformation-specific antibody to aggregated αSyn. Intraepidermal nerve fiber density (IENFD) was assessed as a measure of small fiber neuropathy. αSyn-PLA signal was more expressed in PD and MSA compared to controls and AP-Tau. αSyn-PLA showed the highest diagnostic accuracy (PD vs. HC sensitivity 80%, specificity 77%; PD vs. AP-Tau sensitivity 80%, specificity 82%), however, P-αSyn and 5G4, possible markers of later phases, performed better when considering the ankle site alone. A small fiber neuropathy was detected in PD and MSA. A progression of denervation not of pathological αSyn was detected at follow-up and a lower IENFD at baseline was associated with a greater cognitive and motor decline in PD. A skin biopsy-derived compound marker, resulting from a linear discrimination analysis model of αSyn-PLA, P-αSyn, αSyn-5G4, and IENFD, stratified patients with accuracy (77.8%), including the discrimination between PD and MSA (84.6%). In conclusion, the choice of pathological αSyn marker and anatomical site influences the diagnostic performance of skin biopsy and can help in understanding the temporal dynamics of αSyn spreading in the peripheral nervous system during the disease. Skin denervation, not pathological αSyn is a potential progression marker for PD.

Micro-sized TiO2 as photoactive catalyst coated on industrial porcelain grès tiles to photodegrade drugs in water.

Pharmaceutical compounds and their metabolites raise worrying questions because of their continuous release and lack of efficient removal by conventional wastewater treatments; therefore, they are being detected in groundwater, surface water and drinking water in increasing concentrations. Paracetamol and aspirin are two of the most commonly used drugs employed as fever reducer, analgesic and anti-inflammatory. They and their metabolites are very often found in river water, so their degradation is necessary in order to render water suitable for human consumption. The present work is focused on the comparison of the photocatalytic performance of industrial active grés porcelain tiles covered with a commercial micro-sized TiO2 by industrial process using either conventional spray deposition or innovative digital printing methods. The photodegradation of two commonly used drugs, namely aspirin and paracetamol, was investigated both individually and as a mixture, in both deionized and tap water. The results reveal the full conversion of the drugs and the significant role of the photocatalytic tiles in the mineralization processes leading to harmless inorganic species. In particular, the digitally printed tiles exhibited better photodegradation performance for both drugs compared to the spray deposited tiles. No deactivation was observed on both photocatalytic tiles.

Aspirin and paracetamol removal using a commercial micro-sized TiO2 catalyst in deionized and tap water.

Micro-sized TiO2 catalyst was employed to degrade pharmaceutical compounds, i.e. aspirin and paracetamol, two of the most widely used drugs, purchasable without prescription. Their active agents, acetylsalicylic acid and acetaminophen, are characterized by different substituent groups, linked to the aromatic ring, which affect both the photodegradation and mineralization processes. The experimental conditions highlight the relationship between the nature of the pristine molecules, their degradation mechanisms, their mutual interference and the water's role. The research started from model systems with a single pollutant to the mixture of them and finally by moving from deionized water to tap water.

Copper NPs decorated titania: A novel synthesis by high energy US with a study of the photocatalytic activity under visible light.

The most important drawback of the use of TiO2 as photocatalyst is its lack of activity under visible light. To overcome this problem, the surface modification of commercial micro-sized TiO2 by means of high-energy ultrasound (US), employing CuCl2 as precursor molecule to obtain both metallic copper as well as copper oxides species at the TiO2 surface, is here. We have prepared samples with different copper content, in order to evaluate its impact on the photocatalytic performances of the semiconductor, and studied in particular the photodegradation in the gas phase of some volatile organic molecules (VOCs), namely acetone and acetaldehyde. We used a LED lamp in order to have only the contribution of the visible wavelengths to the TiO2 activation (typical LED lights have no emission in the UV region). We employed several techniques (i.e., HR-TEM, XRD, FT-IR and UV-Vis) in order to characterize the prepared samples, thus evidencing different sample morphologies as a function of the various copper content, with a coherent correlation between them and the photocatalytic results. Firstly, we demonstrated the possibility to use US to modify the TiO2, even when it is commercial and micro-sized as well; secondly, by avoiding completely the UV irradiation, we confirmed that pure TiO2 is not activated by visible light. On the other hand, we showed that copper metal and metal oxides nanoparticles strongly and positively affect its photocatalytic activity.

Association of sugar-based carboranes with cationic liposomes: an electron spin resonance and light scattering study.

The possibility of cationic (di-oleoyltrimethylammonium propane, DOTAP)/(L-alpha-dioleoylphosphatidyl-ethanolamine, DOPE) liposomes to act as carriers of boronated compounds such as 1,2-dicarba-closo-dodecaboran(12)-1-ylmethyl](beta-D-galactopyranosyl)-(1-->4)-beta-D-glucopyranoside and 1,2-di-(beta-D-gluco-pyranosyl-ox)methyl-1,2-dicarba-closo-dodeca-borane(12) has been investigated by Electron Spin Resonance (ESR) of n-doxyl stearic acids (n-DSA) and Quasi-Elastic Light Scattering (QELS). Both these carboranes have potential use in Boron Neutron Capture Therapy (BNCT), which is a targeted therapy for the treatment of radiation resistant tumors. They were shown to give aggregation both in plain water and in saline solution. Carborane aggregates were, however, disrupted when DOTAP/DOPE liposome solutions were used as dispersing agents. The computer analysis of the ESR spectra from carborane-loaded liposomes allowed to establish an increase of the order degree in the liposome bilayer with increasing carborane concentration, together with a decreased mobility. The same discontinuities of both correlation time and order parameter with respect to temperature variations were observed in carborane-containing and carborane-free liposomes. This suggested that a homogeneous dispersion of nitroxides and carboranes occurred in the liposome bilayer. The ESR line shape analysis proved that no dramatic changes were induced in the liposome environment by carborane insertion. QELS data showed that the overall liposome structure was preserved, with a slight decrease in the mean hydrodynamic radius and increase in polydispersity caused by the guest molecules.

Evaluating the clinical accuracy of GlucoMen®Day: a novel microdialysis-based continuous glucose monitor.

BACKGROUND: The objective of this work was to determine the clinical accuracy of GlucoMen®Day, a new microdialysis-based continuous glucose monitoring system (CGMS) from A. Menarini Diagnostics (Florence, Italy). Accuracy evaluation was performed using continuous glucose-error grid analysis (CG-EGA), as recommended by the Performance Metrics for Continuous Interstitial Glucose Monitoring; Approved Guideline (POCT05-A). METHODS: Two independent clinical trials were carried out on patients with types 1 and 2 diabetes mellitus, the glycemic levels of whom were monitored in an in-home setting for 100-hour periods. A new multiparametric algorithm was developed and used to compensate in real-time the GlucoMen®Day signal. The time lag between continuous glucose monitoring (CGM) and reference data was first estimated using the Poincaré plot method. The entire set of CGM/reference data pairs was then evaluated following the CG-EGA criteria, which allowed an estimation of the combined point and rate accuracy stratified by glycemic ranges. RESULTS: With an estimated time lag of 11 minutes, the linear regression analysis of the CGM/reference glucose values yielded r = 0.92. The mean absolute error (MAE) was 11.4 mg/dl. The calculated mean absolute rate deviation (MARD) was 0.63 mg/dl/min. The data points falling within the A+B zones of CG-EGA were 100% in hypoglycemia, 95.7% in euglycemia, and 95.2% in hyperglycemia. CONCLUSIONS: The GlucoMen®Day system provided reliable, real-time measurement of subcutaneous glucose levels in patients with diabetes for up to 100 hours. The device showed the ability to follow rapid glycemic excursions and detect severe hypoglycemic events accurately. Its accuracy parameters fitted the criteria of the state-of-the-art consensus guideline for CGMS, with highly consistent results from two independent studies.