1,721,012 research outputs found
MgO nanoparticles synthesized starting from an innovative one-step process
No full textNanosized MgO is a functional material showing a great promise as destructive adsorbent for toxic chemical agents, unique optical electronic, magnetic, thermal, and mechanical properties, as well as in good bactericidal performance in aqueous environments and in the cancer therapy. In this study, MgO nanoparticles are obtained by thermal decomposition of nanosized Mg(OH)2, which are synthesized by means of an innovative, time and cost-effective, scalable, and patented method. The nanoparticles are characterized by means of several techniques such as thermal analyses, X-ray diffraction analysis, infrared spectroscopy, transmission electron microscopy, atomic force microscopy, and surface area measurements (BET). After a pseudomorphic decomposition of the hydroxide precursor, pure and crystalline MgO nanoparticles are obtained. These nanoparticles are roughly spherical, monodispersed, and monocrystalline, having size ≤10 nm. Moreover, they exhibited a surface area up to 178 m2/g, revealing a bimodal mesoporous distribution with the important part of the pores with dimensions peaked at 4.87 nm
Innovative and green nanolime treatment tailored to consolidate the original mortar of the façade of a medieval building in L'aquila (Italy)
No full textThis paper presents an original, green and compatible treatment to consolidate the pointing lime plastering of the façade of a medieval Italian palace, subjected to detachments and pulverization phenomena. The cohesion between the mortar constituents was refurbished by an aqueous nanolime suspension, synthesized by a cheap, time/energy-saving and scalable method, here originally tested on historic mortars. The suspension showed a high reactivity, assuring a complete carbonation in few hours, “restoring” the binder fraction with a new-formed network of calcite nanoparticles. The treatment efficacy was evaluated by chemico-physical, mineralogical and mechanical characterization both on untreated and treated specimens
Nano-sized Fe(III) oxide particles starting from an innovative and eco-friendly synthesis method
Full text linkThis paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, thermal analysis, nitrogen adsorption and magnetic measurements. Ferrihydrite shows the typical spherical morphology and a very high specific surface area of 420 m2 /g. Rhombohedral or plate-like hexagonal hematite nanoparticles are obtained by the two procedures, characterized by dimensions of 50 nm and 30 nm, respectively, and a specific surface area up to 57 m2 /g, which is among the highest values reported in the literature for hematite NPs
Nano Ca(OH)2 synthesis using a cost-effective and innovative method: Reactivity study
No full textCa(OH)2 nanoparticles in hydro-alcoholic dispersion (nanolime) are currently used for eco-compatible treatments of carbonate-based substrates in the field of Cultural Heritage conservation. Unfortunately, at present nanolime is synthesized by processes which present some drawbacks (considerable cost, multiple steps, low specific production yield), thus limiting the potential of its applications. We have developed a single-step procedure, based on an ion exchange process, making it possible to produce pure and crystalline Ca(OH)2 nanoparticles easily in water, at room temperature and ambient pressure, starting from cheap or renewable reactants. The simplicity of the process and its time- and energy-saving aspects are very promising factors for extending the production from laboratory to industrial scale. The aim of this paper is to investigate the structural and morphological features of the nanoparticles produced and to analyze the influence of crucial parameters of the synthesis process (i.e., time, water usage, reagent concentration and reaction volume) on the nanoparticles’ characteristics. The nanolime produced is investigated by XRD, FTIR, TEM, and AFM techniques. The nanoparticle reactivity in the carbonation process is also investigated, by varying the suspension concentration, the solvent and relative humidity conditions. Pure, crystalline, and very reactive Ca(OH)2 nanoparticles are obtained. The nanoparticles are constituted of thin lamellas, composed of primary hexagonal nanoparticles <10 nm, irrespective of time, water employed, reagents concentration, and reaction volume
New nanolimes for eco-friendly and customized treatments to preserve the biocalcarenites of the “Valley of Temples” of Agrigento
No full textIn this paper we introduce new aqueous nanolime formulations, pure or properly chemically tailored, for innovative, compatible, and eco-friendly consolidation treatments on biocalcarenite stones, a renowned kind of stones used in ancient buildings throughout the Mediterranean region, which are however subject to severe decay. The phase composition, stability, and carbonation process of the nanolime formulations were investigated, while the treatments efficacy was evaluated in terms of aesthetical features, superficial cohesion, drilling resistance and durability. The aqueous nanolimes, applied by nebulization, increased the mechanical resistance on the surface and up to 2 cm in depth without appreciable surface variations, especially in the case of the tailored formulation, ensuring a good durability to UV/salt crystallization ageing
Influence of different types of solvent on the effectiveness of nanolime treatments on highly porous mortar substrates
No full textHistoric calcareous structures suffer from weathering processes that result in the loss of some of their original properties. Nanolime products represent an attractive choice for the consolidation of these substrates containing calcite due to their high chemical compatibility with the original structure. The effectiveness of nanolime products has been widely proven for superficial consolidation treatments (e.g. plasters and wall-paintings). However, its consolidation mechanism in highly porous substrates (e.g. limestones or lime mortars) still needs to be fully understood. The aim of this paper is to study the influence of different types of solvent on the effectiveness of nanolime treatments on highly porous lime-mortars. The consolidation effectiveness is investigated by evaluating changes on superficial cohesion, porosity, drilling resistance, water absorption by capillarity, drying rate and aesthetic properties. Results showed that nanolime dispersed in a mixture of isopropanol (50%) and water (50%) yielded slightly better consolidation properties in terms of reduction in porosity, increase in strength and penetration within coarse lime-mortars than nanolime dispersed in other solvents
[Behavior of serum gastrin, under basal and meal-stimulated conditions, in patients with duodenal ulcer treated with cimetidine]
No full textNew aqueous nanolime formulations for fully compatible consolidation treatments of historical mortars for hypogeum environment
No full textThe religious buildings characterizing by hypogea environments need of proper restoration interventions by using compatible materials. At now, organic and inorganic products proved to be inappropriate for this scope, in relation to the lack of chemical compatibility with the original substrate, to poor penetration depth and to the irreversibility of the treatments. Aim of this paper, is to present an innovative approach to safeguard the hypogea environment, by using new aqueous nanolime formulations, properly chemically tailored, for eco-friendly and green consolidation treatments. Phase composition, stability, and reactivity of the nanolime formulations were investigated, and chemical, petrographic and mechanical analyses of the mortar samples from the hypogeum were carried out. The treatments effectiveness was evaluated in terms of aesthetical features, superficial cohesion and mechanical improvement. The aqueous nanolime suspensions, pure and tailored, applied by airbrush, in-crease the superficial cohesion up to 95 % and improve the mechanical resistance of the surface and up to at least 1 cm in depth, without causing appreciable surface chromatic alterations
Influence of aging and exercise-induced stress on human platelet function
No full textTen healthy nonsmoking old men (age 52-70 years, OM) and ten healthy nonsmoking
young men (age 20-30 years, YM) were submitted to an exercise test on a bicycle
ergometer to examine the combined influence of aging and exercise-induced stress
on platelet function. Data were analyzed by two-way ANOVA test to determine the
statistical significance of differences between baseline, after exercise and
after recovery values, and by Mann-Whitney test to compare differences between
young and old groups. Our results show in OM at rest an increased platelet
aggregability induced by the higher values of intraplatelet basal free calcium
(143.3 +/- 4.8 vs. 121.5 +/- 6.0 nM, p < 0.05) and a statistically significant
increase of plasma oxidative by-products evaluated as thiobarbituric
acid-reactive substances (TBA-RS: 5.9 +/- 0.7 vs. 1.5 +/- 0.1 micromol/l, p <
0.05). Further, significant modifications of calcium and TBA-RS levels were found
in both groups because of exercise-induced stress. The positive relationships
between calcium amount and plasma values of TBA-RS in OM before (r = 0.728, p =
0.017) and after (r = 0.772, p = 0.009) physical test and in YM only at the end
of exercise (r = 0.853, p = 0.002), underline that oxidative stress may modulate
platelet function by influencing calcium homeostasis and platelet membrane
permeability
New sustainable, scalable and one-step synthesis of iron oxide nanoparticles by ion exchange process
Full text linkThis work introduces an innovative, sustainable, and scalable synthesis of iron oxides nanoparticles (NPs) in aqueous suspension. The method, based on ion exchange process, consists of a one-step procedure, time and energy saving, operating in water and at room temperature, by cheap and renewable reagents. The influence of both oxidation state of the initial reagent and reaction atmosphere is considered. Three kinds of iron nanostructured compounds are obtained (2-lines ferrihydrite; layered-structure iron oxyhydroxide δ-FeOOH; and cubic magnetite), in turn used as precursors to obtain hematite and maghemite NPs. All the produced NPs are characterized by a high purity, small particles dimensions (from 2 to 50 nm), and high specific surface area values up to 420 m2/g, with yields of production >90%. In particular, among the most common iron oxide NPs, we obtained cubic magnetite NPs at room temperature, characterized by particle dimensions of about 6 nm and a surface area of 170 m2/g. We also obtained hematite NPs at very low temperature conditions (that is 2 h at 200 °C), characterized by particles dimensions of about 5 nm with a surface area value of 200 m2/g. The obtained results underline the strength of the synthetic method to provide a new, sustainable, tunable, and scalable high-quality production
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