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Our study aims at evaluating clinical predictors of menstrual cycle disorders in female athletes who compete in running disciplines. This is a prospective observational study. Women were recruited between January and May 2022. 53 patients were enrolled and completed a questionnaire about menstrual cycle, physical activity and food habits characteristics. 39,6% of women in our population had menstrual irregularities and reported a significantly higher number of kilometres run per week (67 vs 35, p:0.02). The number of kilometres run per week was associated with menstrual irregularities (for 10 km, OR 1,35; IC95% 1,05-1,73; p: 0,02) after adjusting for BMI, age, level of sport and caloric intake. The variable of “km run per week” appeared as a diagnostic indicator of irregular menstrual cycle with statistical significance (AUC ROC curve 0,71, IC95% 0,54-0,86, p-value = 0,01) and the cut off-of 65 km run per week is a good indicator of the presence of irregular menstrual cycle (sensitivity (SE) and specificity (SP) of 55% and 81,48%). Menstrual cycle disorders are very frequent in female athletes and the variable of km run per week may have a role in screening endurance athletes at high risk for them.

Mini-puberty is the physiological and transient activation of the hypothalamic-pituitary-gonadal axis occurring during the first months after birth. In preterm infants, the hormonal surge is more pronounced and longer-lasting than in at-term-peers. To date, only few cases of vaginal bleeding in the setting of an exaggerated mini-puberty have been reported. At the corrected age of 3 months, an ex-very-preterm girl presented with breast enlargement and recurrent vaginal bleeding. A remarkable increase in gonadotropins and estradiol levels was detected, while pelvic ultrasound highlighted a large right ovarian cyst. As brain and pituitary MRI showed negative findings, an exaggerated mini-puberty was suspected and no additional investigations were undertaken. The subsequent progressive regression of clinical, biochemical and sonographic findings confirmed the diagnosis. Although exaggerated mini-puberty of infancy in ex-preterm girls is a rare event, it is important to raise knowledge of this para-physiological condition in order to avoid unnecessary investigations and treatment.

PURPOSE: While overexercise is commonly described in patients who experience anorexia nervosa (AN), it represents a condition still underestimated, especially in the paediatric population.METHOD: The present study aims at assessing the possible associations between levels of physical activity (PA) and clinical features, endocrinological data and psychopathological traits in a sample of 244 female adolescents hospitalised for AN subdivided into two groups according to PA levels (high PA vs. no/low PA). The two groups were compared through multivariate analyses, while multiple regression analysis was conducted to determine whether physical activity predict specific outcomes.RESULTS: No significant differences were found between the two groups in terms of last Body Mass Index (BMI) before illness, BMI at admission and disease duration, while a difference emerged in delta BMI(rapidity of weight loss), significantly higher in high-PA group (p=0.021). Significant differences were observed in Free triiodothyronine- (p<0.001), Free thyroxine (p=0.046), Follicle-stimulating hormone (p=0.019), Luteinising hormone (p=0.002) levels, with values remarkably lower in high-PA group. Concerning psychopathological scales, the high-PA group showed worst Children's Global Assessment Scale (CGAS) scores (p=0.035). Regression analyses revealed that higher PA predicts higher delta BMI (p=0.021), presence of amenorrhea (p=0.003), lower heart rate (p=0.012), lower thyroid (Free triiodothyronine p<0.001, Free thyroxine p=0.029) and gynaecological hormones' levels (Follicle-stimulating hormone p=0.023, Luteinising hormone p=0.003, 17-Beta estradiol p=0.041). Concerning psychiatric measures, HPA predicts worst scores at CGAS (p=0.019), and at scales for evaluation of alexithymia (p=0.028) and depression (p=0.004).CONCLUSIONS: Results suggest that high levels of physical activity in acute AN associate with worst clinical conditions at admission, especially in terms of endocrinological and

The present study aims at supplying a more in-depth picture of the Environmentally Persistent Free Radicals (EPFRs) generation from phenol (PhOH) on ZnO/SiO2 systems, by exploring the properties of ZnO nanoparticles with different intrinsic defectivity grown on highly porous silica with spherical (ZnO/SiO2_S) and worm-like morphology (ZnO/SiO2_W). In detail, besides an extensive structural, morphological, and surface investigation, the occurrence of inequivalent defect centers in the samples was tracked by photoluminescence (PL) experiments, which unveiled, for ZnO/SiO2_W, intense blue emissions possibly involving radiative recombination from Zni excited levels to the valence band or to VZn levels. Electron Spin Resonance (ESR) spectra, corroborated these results and revealed a remarkably different behaviour of the samples in the EPFRs formation model reaction. In fact, upon PhOH contact, the ESR spectrum of ZnO/SiO2_S showed the exclusive presence of a weak isotropic signal ascribable to a PhenO• EPFR. Instead, for ZnO/SiO2_W, intense features associated to oxygen species in proximity of VO+, VZn‒ and (VZn‒)2‒ centers dominate the spectra, while a minor contribution of PhenO• radical can be discovered only by signals simulation. These outcomes definitively envisage a role of the intrinsic defectivity of ZnO NPs on the final yield and stability of EPFRs generation, with VO+ and VZn‒ defects possibly involved in dissociative adsorption or oxidation processes at the oxide surface. Although this work focuses on ZnO, it is expected to foster a critical re-examination and integration of important results on other metal oxide/silica systems already reported in the literature, offering the chance to better evaluate the dependence EPFRs generation on the oxide defects chemistry.

We comprehensively explored the photocatalytic properties, in H2 production by methanol photosteam reforming, of anatase nanocrystals with nearly rectangular (RC), rhombic (R), and nanobar (NB) shapes having exposed {001}, {101}, and {010} surfaces. The aim was to relate the reactivity both to the type of crystal facets and to the photogenerated defects. The electron spin resonance (ESR) spectra reveal that the amount of Ti3+ (electron traps) is parallel to the H2 evolution rate and becomes a maximum for the RC nanocrystals, which display the highest area of {001} surfaces and the lowest {101} area but also involve a significant area of {010} facets. This points out that the H2 production cannot be related only to the envisaged reducing {101} facets, but that the {010} facets also play a key role. We suggest that the contiguous {001}, {101}, and {010} facets form a highly effective "surface heterojunction" within a RC nanoparticle which drives the electrons photogenerated on {001} facets not just toward the {101} but also to the {010} facets, while the holes are driven toward the {001} facets. This transfer improves the charge separation, thus boosting the photoefficiency of RC nanocrystals compared to that of NB and R nanocrystals. The ESR spectra performed after ultraviolet excitation in the presence of MeOH show the partial annihilation of the Ti3+ features, mainly for highly reactive RC nanocrystals. Because H2 production involves an electron transfer to the proton, a relevant role in H+ photoreduction of the Ti3+ centers present on the exposed {010} and {101} surfaces is suggested. These findings underline the importance of determining the relationship between the photogenerated defects and the exposed crystal surfaces to optimize the photocatalytic properties of anatase nanocrystals. (Figure Presented).

A novel hybrid nanofiller, SiO2@POSS, where the silica nanoparticles (NPs) and the POSS belong to the same functional structure, has been synthesized by grafting different loadings of OctaMethacrylPOSS onto silanized commercial SiO2, using a surface reaction mediated by dicumylperoxide (DCP). The peroxide, besides anchoring the nanocages onto the silica surface, ensures the presence of methacryl functionalities in the final structure, which are still available for cross-linking reactions with a polymer host. The hybrid SiO2@POSS NPs were used to prepare, by ex situ blending, SBR nanocomposites. The dynamic-mechanical analysis performed on the cured SBR/SiO2@POSS composites indicated that the presence of POSS induces a remarkable increase of modulus either at low or at high strain, and a considerable decrease of hysteresis. This has been associated with the peculiar hybrid structure of the SiO2@POSS filler, in which silica NP aggregates are partially interconnected and surrounded by a thin shell of POSS nanounits which, thanks to their high number of reactive functionalities, promote the formation of "sticky regions" among the silica aggregates and, consequently, a tight filler network wherein rubber is immobilized. This grants a relevant reinforcement and increased hysteretic properties, suggesting SiO2@POSS as a promising filler system for decreasing the energy loss under strain and for leading to a potential reduction of filler utilization in rubber composite formulations.

Rechargeable sodium-ion batteries are becoming a viable alternative to lithium-based technology in energy storage strategies, due to the wide abundance of sodium raw material. In the past decade, this has generated a boom of research interest in such systems. Notwithstanding the large number of research papers concerning sodium-ion battery electrodes, the development of a low-cost, well-performing anode material remains the largest obstacle to overcome. Although the well-known anatase, one of the allotropic forms of natural TiO2, was recently proposed for such applications, the material generally suffers from reduced cyclability and limited power, due to kinetic drawbacks and to its poor charge transport properties. A systematic approach in the morphological tuning of the anatase nanocrystals is needed, to optimize its structural features toward the electrochemical properties and to promote the material interaction with the conductive network and the electrolyte. Aiming to face with these issues, we were able to obtain a fine tuning of the nanoparticle morphology and to expose the most favorable nanocrystal facets to the electrolyte and to the conductive wrapping agent (graphene), thus overcoming the intrinsic limits of anatase transport properties. The result is a TiO2-based composite electrode able to deliver an outstandingly stability over cycles (150 mA h g(-1) for more than 600 cycles in the 1.5-0.1 V potential range) never achieved with such a low content of carbonaceous substrate (5%). Moreover, it has been demonstrated for the first time than these outstanding performances are not simply related to the overall surface area of the different morphologies but have to be directly related to the peculiar surface characteristics of the crystals.

Purpose. To compare the vitrectomy time, clinical outcomes, and complications between 27-gauge (27-G) and 25-gauge (25-G) vitrectomy in patients with primary rhegmatogenous retinal detachment (PRRD). Methods. Prospective, nonrandomized, comparative, interventional study. Forty consecutive patients with PRRD were recruited. Twenty patients underwent the 27-gauge procedure and twenty patients had the 25-gauge procedure. The main outcome measure of the study was the actual vitrectomy time. Results. The mean duration of vitreous removal was 23.2 min (SD 6.5) with 27-G vitrectomy and 19.6 min (SD 7.3) with 25-G vitrectomy, resulting in a difference of 3.6 min (95% confidence interval (95%CI): -8.0 to 0.8 mins, p=0.11). Mean logMAR visual acuity improved from 1.70 ± 1.18 preoperatively to 0.12 ± 0.14 at final postoperative visit (p<0.001) in the 27-G group and from 1.52 ± 1.15 preoperatively to 0.22 ± 0.30 at final postoperative visit (p<0.001) in the 25-G group. The anatomical success rate after a single operation was 90.0% and 85.0% in the 27-G and in the 25-G groups (p=0.63), respectively. Intraoperative iatrogenic retinal breaks (IRBs) occurred in 2 eyes in the 27-G group and 1 eye in the 25-G group. Conclusions. Twenty-seven-gauge vitrectomy may be a safe and effective surgery for the treatment of PRRD.

The present study reports on the synthesis and the electrochemical behavior of Na0.71CoO2, a promising candidate as cathode for Na-based batteries. The material was obtained in two different morphologies by a double-step route, which is cheap and easy to scale up: the hydrothermal synthesis to produce Co3O4 with tailored and nanometric morphology, followed by the solid-state reaction with NaOH, or alternatively with Na2CO3, to promote Na intercalation. Both products are highly crystalline and have the P2-Na0.71CoO2 crystal phase, but differ in the respective morphologies. The material obtained from Na2CO3 have a narrow particle length (edge to edge) distribution and 2D platelet morphology, while those from NaOH exhibit large microcrystals, irregular in shape, with broad particle length distribution and undefined exposed surfaces. Electrochemical analysis shows the good performances of these materials as a positive electrode for Na-ion half cells. In particular, Na0.71CoO2 thin microplatelets exhibit the best behavior with stable discharge specific capacities of 120 and 80 mAh g(-1) at 5 and 40 mA g(-1), respectively, in the range 2.0-3.9 V vs. Na (+)/Na. These outstanding properties make this material a promising candidate to construct viable and high-performance Na-based batteries.

The sensing behavior of pyramidal (PY), prismatic hexagonal (EP) and hexagonal rod-like (ER) ZnO micro and sub-microparticles, has been compared with that of commercial ZnO (ZnO®) particles having nanometric size and uneven shape. The performances have been firstly related to the predominance of specific crystal surfaces and then, more in depth, to the paramagnetic defects in ZnO (and), detected by Electron Spin Resonance (ESR), in order to associate the particles morphology with the defects amount and reactivity and, in turn, with a particular sensing mechanism. The results showed that the sensing behavior of ZnO® containing irregular nanoparticles is essentially related to the alternate formation and filling of oxygen vacancies during the gas pulse (oxygen vacancy mechanism), while that of ER and EP crystals does not seem to directly involve the defects. In particular, the sensing properties of shape controlled ZnO particles are mainly attributed to the ability of (0001) exposed surfaces in favoring a far better chemisorption of negatively charged oxygen species, then available for the reactions with the reducing gas (i.e. ionosorption mechanism). The outcomes and the approach adopted in this study may positively contribute to the debate still existing between the oxygen vacancy and ionosorption models by giving indications on the predominance of a specific sensing mechanism in shape controlled ZnO.

We report on the surface interaction between NH3 and WO 3 nanoparticles having different exposed surfaces or different porous structure, to identify the relative importance of exposed crystal surfaces, porous architecture, and specific surface area in the oxide sensing properties. WO3 nanocrystals with tailored morphology and definite prominent surfaces were synthesized by hydrothermal reactions. In parallel, inverted opal macroporous WO3 films have been prepared by a one-step sol-gel procedure, and WO3 hierarchical layers have been obtained by an innovative one-step dual-templating strategy which leads to macropores and mesopores simultaneously. The performances of WO3 samples in NH 3 sensing, indicate that high-energy surfaces result in a significant improvement of the electrical response. Enhanced porous structure and high surface area are not enough to produce high electrical response, while their synergistic combination with tailored crystal faceting appears effective. XPS survey performed on shape controlled WO3 nanocrystals demonstrated that, upon interaction with NH3, oxidized nitrogen atoms represent the prevalent species on the surface of rectangular (WO3-RE) nanocrystals with highly exposed high-energy {020} and {002} facets. Conversely, in the case of rectangular platelets (WO3-SS) and square platelets (WO3-RS) with very low surface area of high-energy surfaces, N-H surface groups are predominant. These results suggest that {020} and {002} crystal surfaces provide privileged reactive sites for ammonia oxidation and therefore they play a key role in driving the sensing properties of the WO 3 layers. © 2014 The Royal Society of Chemistry.

Sediment starved passive margins, particularly those of insular slopes, display significant mass transport activity despite the absence of environmental stresses from high sedimentation rates. The “Menorca Channel” represents the up to 120 m deep shelf sector connecting the Menorca and Mallorca Islands (Balearic Islands – Western Mediterranean). South of the Menorca Channel submarine gravitational processes have been mapped and interpreted from swath-bathymetry, TOPAS parametric echosounder and deep-towed videos. The shelf-break is located at an average depth of 140 m, and sediment instability is a widespread phenomenon. The slope region south the Menorca Channel shows a number of submarine canyons disrupting the outer shelf. The north-easternmost canyon is the more active feature, with an incised axis and scars shaping the flanks up to their edges. Headwall scarps, between 140 and 700 m depth, are up to 20 m high. The shallower scarps producing slab-type failures have carved the outer edges of planar sedimentary bodies interpreted as formed in shallow environments during previous glacial stages. Results show that a variety of sediment instability processes extensively shape the southern upper slope of the Menorca Channel. Submarine canyons develop on the Emile Bodout Escarpment (EBE), a passive tectonic feature which bounds the slope region of the study area. A number of knickpoints within the canyons suggest backward erosion control on mass wasting and, at the same time, that slope failure is one of the main drivers for canyon upslope migration. Steep gradients of the upper slope, the presence of weak layers and the action of major storms during lowstand stages are additional factors likely to influence the distribution and frequency of mass wasting processes in this area.

Ordered mesoporous silica nanoparticles (MSNs) were impregnated with different loadings of the luminescent complex tris(dibenzoylmethane) mono(1,10-phenanthroline)europium(III) (Eu(dbm)3phen), with the aim of increasing the luminescence by avoiding concentration quenching and having mainly in mind the application as spectral converter for multi-crystalline silicon solar cells. The morphological, structural and luminescence properties of the impregnated silica nanoparticles were characterized by N2 physisorption, X-ray diffraction, transmission electron microscopy, infrared spectroscopy, UV–visible spectroscopy and photoluminescence excitation and emission measurements. Photostability was tested under 1 sun (1000 W/m2) illumination for 24 h and the related effects were inspected by UV–visible and photoluminescence spectroscopies. Impregnation of the complex into 50–70 nm MSNs with pore size tailored around 2.9 nm depressed concentration quenching and allowed the use of complex loadings as high as 23 wt%. Sunlight irradiation caused a marked increase in the luminescence intensity.

Introduction and hypothesis The aim of this study was to evaluate the functional outcome of a single-incision sling procedure for the treatment of female stress urinary incontinence (SUI) and to correlate the cure rate with a pelvic floor ultrasound examination Methods Fifty-seven patients treated with a single-incision sling procedure between January 2009 and September 2010 were included in the study. Functional outcome was evaluated as objective cure rate assessed with stress test and subjective cure rate determined by the International Consultation on Incontinence-Short Form and Patient Global Impression of Improvement scores. Women underwent perineal ultrasound examination by a combined 2D translabial and 3D transvaginal approach to assess bladder neck and tape mobility, tape position along the urethral axis, and tape anchorage. According to the position of self-fixating tips, we divided patients into group A (both tips crossed the obturator membrane), group B (only one tip crossed the obturatormembrane) and group C (none of the tips crossed the obturator membrane). Objective cure rate and type of anchorage were compared with all ultrasound parameters. Results At an average follow-up of 13 months objective cure rate was 87.7 % with a significant subjective improvement. A significant difference in tape mobility was noted between group A and group C. Bladder neck mobility significantly increased in failures. Sling was significantly closer to midurethra in cured than in failures. Conclusions In 77 % of patients MA didn't reach the obturator membrane on both sides. This feature conditioned significantly bladder neck mobility but not the efficacy of the procedure. Tape position seems to be the most important factor for success. © The International Urogynecological Association 2013.

The promising properties of anatase TiO 2 nanocrystals exposing specific surfaces have been investigated in depth both theoretically and experimentally. However, a clear assessment of the role of the crystal faces in photocatalytic processes is still under debate. In order to clarify this issue, we have comprehensively explored the properties of the photogenerated defects and in particular their dependence on the exposed crystal faces in shape-controlled anatase. Nanocrystals were synthesized by solvothermal reaction of titanium butoxide in the presence of oleic acid and oleylamine as morphology-directing agents, and their photocatalytic performances were evaluated in the phenol mineralization in aqueous media, using O 2 as the oxidizing agent. The charge-trapping centers, Ti 3+, O -, and O 2 -, formed by UV irradiation of the catalyst were detected by electron spin resonance, and their abundance and reactivity were related to the exposed crystal faces and to the photoefficiency of the nanocrystals. In vacuum conditions, the concentration of trapped holes (O - centers) increases with increasing {001} surface area and photoactivity, while the amount of Ti 3+ centers increases with the specific surface area of {101} facets, and the highest value occurs for the sample with the worst photooxidative efficacy. These results suggest that {001} surfaces can be considered essentially as oxidation sites with a key role in the photoxidation, while {101} surfaces provide reductive sites which do not directly assist the oxidative processes. Photoexcitation experiments in O 2 atmosphere led to the formation of Ti 4+-O 2 - oxidant species mainly located on {101} faces, confirming the indirect contribution of these surfaces to the photooxidative processes. Although this work focuses on the properties of TiO 2, we expect that the presented quantitative investigation may provide a new methodological tool for a more effective evaluation of the role of metal oxide crystal faces in phot

Macroporous WO3 films with inverted opal structure were synthesized by one-step procedure, which involves the self-assembly of the spherical templating agents and the simultaneous sol-gel condensation of the semiconductor alkoxide precursor. Transition metal doping, aimed to enhance the WO3 electrical response, was carried out by including Cr(III) and Pt(IV) centers in the oxide matrix. It turned out that Cr remains as homogeneously dispersed Cr(III) centers inside the WO3 host, while Pt undergoes reduction and aggregation to form nanoclusters located at the oxide surface. Upon interaction with NH3, the electrical conductivity of transition metal doped-WO3 increases, especially in the presence of Pt dopant, resulting in outstanding sensing properties (S = 110 ± 15 at T = 225 °C and [NH3] = 74 ppm). A mechanism was suggested to explain the excellent electrical response of Pt-doped films with respect to the Cr-doped ones. This associates the easy chemisorption of ammonia on the WO 3 nanocrystals, promoted by the inverted opal structure, with the catalytic action exerted by the surface Pt nanoclusters on the N-H bond dissociation. The overall results indicate that in Pt-doped WO3 films the effects of the macroporosity positively combine with the electrical sensitization promoted by the metal nanoclusters, thus providing very lightweight materials which display high functionality even at relatively low temperatures. We expect that this synergistic effect can be exploited to realize other functional hierarchical metal oxide structures to be used as gas sensors or catalysts.(Figure Presented) © 2011 American Chemical Society.

Mesoporous Cr or Pt-doped WO3 thin films to be employed as ammonia gas sensors were prepared by a fast one-step sol–gel procedure, based on the use of triblock copolymer as templating agent. The obtained films were constituted by aggregates of interconnected WO3 nanocrystals (20–50 nm) separated by mesopores with dimensions ranging between 2 and 15 nm. The doping metals, Pt and Cr, resulted differently hosted in the WO3 mesoporous matrix. Chromium is homogeneously dispersed in the oxide matrix, mainly as Cr(III) and Cr(V) centers, as revealed by EPR spectroscopy; instead platinum segregated as Pt (0) nanoparticles (4 nm) mainly included inside the WO3 nanocrystals. The semiconductor layers containing Pt nanoclusters revealed, upon exposure to NH3, remarkable electrical responses, much higher than Cr-doped and undoped layers, particularly at low ammonia concentration (6.2 ppm). This behavior was attributed to the presence of Pt nanoparticles segregated inside the semiconductor matrix, which act as catalysts of the N–H bond cleavage, decreasing the activation barrier in the ammonia dissociation. The role of the mesoporous structure in influencing the chemisorption and the gas diffusion in the WO3 matrix appeared less decisive than the electronic differences between the two examined doping metals. The overall results suggest that a careful combination between mesoporous architecture and metal doping can really promote the electrical response of WO3 toward ammonia. Keywords Pt and Cr—doped WO3 Mesoporous thin film Gas sensors Morphological, electronic and electrical

TiO2-SiO2 composite materials with photocatalytic properties similar to those of slurry powdered TiO2 is obtained by a novel sol-gel synthetic strategy involving the hydrolysis/condensation of TMOS assisted by PEG as templating agent and the grafting of preformed titania nanocrystals onto the macropore walls of the silica matrix. In order to anchor TiO2 particles to the surface of SiO2, avoiding their embedding into silica matrix, functionalization with carboxylic acid or amine derivatives was carried out. The functionalization induces the confinement of titania nanocrystals in PEG, during the silica formation, and allows their dispersion on the silica surface. TiO2-SiO2 materials exhibit high thermal and chemical stability and a photocatalytic activity in the phenol mineralization comparable to that of powder TiO2 in slurry (half degradation time ∼120min). These results suggest that the immobilization procedure here reported provides high accessibility of the catalyst active sites preserving the functional properties of the photoactive catalyst. © 2011 Elsevier B.V.

TiO2 dispersed in polyester acrylate membranes was tested as a photocatalyst in the phenol mineralization reaction assisted by molecular oxygen. Kinetics experiments revealed that, although embedded, the oxide maintains significant catalytic activity. This result was first attributed to the homogeneous dispersion inside the polymeric host of TiO2 nanocrystals, which can be easily irradiated and interact with the reactants. Furthermore, the investigation of the photogenerated charge carriers in the photocatalyst demonstrated that electrons are trapped on Ti3+ centers, while holes are trapped on C-centered species of the polymer matrix. In the presence of O-2, the C-centered radicals of the polymer transform into peroxy radicals, reinforcing the charge separation in the polymer-embedded oxide with respect to the powder. The positive interference of the polymer matrix in reinforcing the electron hole separation is responsible for the relevant photoactivity of the embedded TiO2.

A new, fast, one-pot synthesis of SnO2 and Pt-doped SnO2 inverted opal thin films, to be used as materials for gas sensing, was carried out. Films were built from crystalline cassiterite nanoparticles, uniform in size (∼5 nm), resulting in a well-organized hierarchical structure of macro- and mesopores. The noble metal was homogeneously dispersed into the sensing layer of the oxide and the doping centers were present as Pt(IV) and Pt(II) species, partially reduced to Pt(0) after the interaction with the reducing gas (CO). The values of the electrical sensitivity under CO/Air atmosphere demonstrated that the response of Pt-doped films is higher than that of bare SnO2 films, and that the response of inverted opal films is higher compared to that of the sol-gel films. The regular array of cassiterite nanoparticles, strongly interconnected and ordered as close-packed hollow spheres, promotes the effective gas diffusion through the oxide layer and, along with the electron acceptor ability of Pt(IV) doping centers, significantly contributes to enhancing the electrical sensitivity. The conductance regime of the Pt-doped SnO2 inverted opal film is indicative of a regular microstructure of SnO2 nanoparticles

The sol-gel synthesis of TiO2 from TiCl4 assisted by the triblock copolymer EO20-PO70 -EO20 (EO = -CH2CH2O-, PO = -CH2 (CH3)CHO-) as templating agent was carried out by systematically changing H2O:Ti (rw) and HCl:Ti (ra) molar ratios. Mesoporous and nanocrystalline TiO2 samples with well-defined and controlled phase composition (anatase, rutile, and mixed phase) were obtained after calcination at 400 °C and characterized for the morphology, particle size, and shape using TEM, HRTEM, XRD, and surface area measurements. The role of rw and ra and influence of the copolymer in determining the phase composition was demonstrated. Rutile becomes the main phase by increasing rw. In fact, the decrease of Ti concentration slows down the condensation rate, favoring formation of rutile seeds in the gel. The photocatalytic activity of TiO2 in the UV photomineralization of phenol depends on the phase composition and oxidizing agent, H2O2 or O2. When the oxidation is performed by H2O2, rutile, formed by large crystalline rods with high aspect ratios (size 15-20 × 100-120 nm), shows higher catalytic activity with respect to the small, almost cubic, anatase particles (5-15 nm). If O2 is used, the catalytic activity generally decreases and the behavior of polymorphous species is reverse. EPR investigation of the paramagnetic charge carriers, formed under UV irradiation at 10 K, showed the resonance lines of holes trapped at O- lattice sites and electrons trapped at Ti3+ and O2- sites. The rutile crystalline rods present the largest quantity of O- and Ti3+ centers. The overall results suggest correlation between TiO2 particle size and shape and the photocatalytic activity

Nanocrystalline powders of undoped and lanthanide (Pr3+, Tm3+)- doped gadolinium gallium garnet, Gd3Ga5O12 (GGG), were prepared by propellant synthesis and studied by x-ray powder diffraction (XRD), electron diffraction (ED), high-resolution electron microscopy (HREM) and luminescence spectroscopy. The x-ray diffraction patterns of the GGG samples were analysed using the Rietveld method. The Rietveld refinement reveals the existence of two garnet-type phases: both are cubic (space group Ia $(3) over bar $d) with a slightly different lattice parameter and probably a slightly different composition. Electron diffraction and electron microscopy measurements confirm the x-ray diffraction results. EDX measurements for lanthanide-doped samples show that stable solid solutions with composition Gd(3-x)Ln(x)Ga(5)O(12), x approximate to 0.3 ( Ln = Pr; Tm) have been obtained. The luminescence properties of the Tm3+ -doped nanocrystalline GGG samples were measured and analysed.

The possibility of controlling the photocatalytic activity of TiO 2 nanoparticles by tailoring their crystalline structure and morphology is a current topic of great interest. In this study, a broad variety of well-faceted particles with different phase compositions, sizes, and shapes have been obtained from concentrated TiOCl2 solutions by systematically changing temperature, pH, and duration of the hydrothermal treatment. The guide to select the suitable experimental conditions was provided by thermodynamic modeling based on available thermochemical data. By combining the results of TEM, HRTEM, XRD, density, and specific surface area measurements, a complete structural and morphological characterization of the particles was performed. Correlation between the photocatalytic activity in the UV photodegradation of phenol solutions and the particle size was established. Prismatic rutile particles with length/width ratio around 5 and breadth of 60-100 nm showed the highest activity. The surface chemistry of the particles was also investigated. Treatments that decrease the surface acidity, such as washing the powders with ammonia solution and/or calcining at 400 °C, have detrimental effect on photocatalytic activity. The overall results suggest correlation between particle morphology and photocatalytic activity and indicate that both electron-hole recombination and adsorption at the surface can be rate-controlling processes. The systematic approach presented in this study demonstrates that a substantial improvement of the photocatalytic activity of TiO2 can be achieved by a careful design of the particle morphology and the control of the surface chemistry. © 2007 American Chemical Society.

Inverted opal Ce-doped silica glasses (Ce : Si molar ratio 1 . 10(-3)) were prepared by a sol-gel method using opals of latex microspheres as templates. The rare earth is homogeneously dispersed in silica host matrix, as evidenced by the absence of segregated CeO2, instead present in monolithic Ce-doped SG with the same cerium content. This suggests that the nanometric dimensions of bridges and junctions of the host matrix in the inverted opal structures favor the RE distribution avoiding the possible segregation of CeO2. Copyright (C) 2006 R. Scotti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Ce3+-doped boro, phospho and borophosphosilicate monolithic glasses (BSG, PSG and BPSG) were prepared by sol-gel method. The inclusion of the glass formers P and B in silica lowered the tendency of rare earth (RE) to segregate as CeO2 with respect to pure SiO2 matrix (SG). In PSG and BPSG, Ce3+ co-ordination to P=O groups was responsible for the inhibition of both CeO2 segregation and oxidation of isolated Ce3+ ions to Ce4+. The better ion dispersion in the host matrix and the stabilization of Ce3+ oxidation state improved PSG and BPSG luminescence properties with respect to BSG and SG

Ce-doped borosilicate (BSG), phosphosilicate (PSG), and borophosphosilicate (BPSG) glasses (B:P:Si molar ratios 8:0:92, 0:8:92, and 8:8:84; Ce:Si molar ratio 1 10-4 to 1 10-2) were prepared by the sol-gel method. High-resolution transmission electron microscopy (HRTEM), 31P, 29Si, and 11B magic angle spinning nuclear magnetic resonance (MAS NMR), electron paramagnetic resonance (EPR), and UV-vis absorption investigations demonstrated that, in PSG and BPSG, Ce3+ ions interact with phosphoryl, [OdPO3/2], metaphosphate, [OdPO2/ 2O]-, and pyrophosphate, [OdPO1/2O2]2-, groups, linked to a silica network. This inhibits both CeO2 segregation and oxidation of isolated Ce3+ ions to Ce4+, up to Ce:Si ) 5 10-3. In BSG, neither trigonal [BO3/2] nor tetrahedral [BO4/2]- boron units coordinate cerium; thus, Ce3+ oxidation occurs even at Ce:Si ) 1 10-4, as in pure silica glass (SG). The homogeneous rare-earth dispersion in the host matrix and the stabilization of the Ce3+ oxidation state enhanced the intensity of the photoluminescence emission in PSG and BPSG with respect to BSG and SG. The energy of the Ce3+ emission band in PSG and BPSG matrixes agrees with the phosphate environment of the rare earth

Tin dioxide and ruthenium(platinum)-doped tin dioxide were synthesized in the form of inverted opals, aiming to investigate the interaction of these materials with CO reducing gas. The results of electron paramagnetic resonance (EPR) investigation allowed us to conclude that CO interaction causes the formation of singly ionized oxygen vacancies located in the subsurface region. These ones transfer their electrons to transition metal centers, Ru or Pt, enhancing the SnO2 surface reactivity toward CO. The reduction of Ru4+ and Pt4+ was assessed both by EPR and Mössbauer spectroscopy. Resistance measurements showed that the materials are well-suitable for use in CO sensor devices because of their reproducible and fast electrical response; this was related to the homogeneous and high dispersion of Ru and Pt centers in the oxide matrix and to the subsurface location of the species active in the electron-transfer processes. © 2005 American Chemical Society.