LA SCUOLA SPAIS: RICERCA SCIENTIFICA E DIDATTICA DELLE SCIENZE IN UN CONTESTO MULTIDISCIPLINARE

SPAIS si pone come obiettivo l’individuazione e il conseguente approfondimento delle conoscenze di base che sono necessarie nel campo della chimica, della fisica e delle scienze biologiche e naturali per comprendere e comunicare i contenuti fondamentali della moderna ricerca scientifica e tecnologica. L’edizione 2013 sul tema “ScientificaMente – le Neuroscienze” viene qui presentata evidenziandone particolarmente le implicazioni nella didattica della Chimic

VERSO UN APPRENDIMENTO AUTENTICO DELLA CHIMICA DI BASE: TRASPOSIZIONE DIDATTICA DEI RISULTATI DELLA MODERNA RICERCA SCIENTIFICA.

In questo lavoro viene presentata una proposta riguardante l'uso dei risultati della moderna ricerca in campo chimico per introdurre i concetti fondanti della disciplina nella pratica didattica della Chimica di base nella Scuola Secondaria di Secondo Grado. Con questo approccio, i concetti di base dovrebbero risultare meno astratti e il mondo della ricerca più accessibile

Scienza e Arti Perdute: i Segreti degli Antichi Maestri Liutai

Lo scopo di questo lavoro è illustrare agli insegnanti la connessione tra due settori di attività apparentemente lontani: la scelta dei materiali utilizzati nella liuteria artigianale e la chimica. Il ruolo, la composizione e la classificazione delle principali vernici per liuteria sono qui descritte assieme ad una breve sintesi dello stato dell’arte. Nel lavoro, vengono presentati i principali concetti di una tecnica analitica non distruttiva abbastanza semplice (la spettroscopia di fluorescenza da raggi X) ma, probabilmente, non abbastanza nota ai non addetti ai lavori. Un caso di studio a essa correlato è inoltre presentato per evidenziare uno dei possibili contributi del chimico nello studio dei beni culturali.The aim of this paper is showing teachers the connection between two apparently distant working fields: the choice of materials used in artisanal lute making and chemistry. The role, the composition and the classification of the main varnishes for classical lute making are here described with a brief review of the state of the art. Furthermore, the main theoretical basis of a relatively simple non-destructive analytical technique (X-Ray Fluorescence Spectroscopy), probably not very well known by non-specialists, is here illustrated. A case study is also presented to highlight one of the possible roles of the chemist in the study of cultural heritage

Influence of the modification, induced by zirconia nanoparticles, on the structure and properties of polycarbonate

Melt compounding was used to prepare polycarbonate (PC)-zirconia nanocomposites with different amounts of zirconia. The effect of the zirconia loading, in the range of 1-5 wt.%, on the structure, mechanical properties and thermal degradation kinetics was investigated. The zirconia nanoparticle aggregates were well dispersed in the PC matrix and induced the appearance of a local lamellar order in the polycarbonate as inferred by SAXS findings. This order could be a consequence of the intermolecular interactions between zirconia and the polymer, in particular with the quaternary carbon bonded to the methyl groups and the methyl carbon as inferred from the NMR results. The presence of zirconia caused a decrease in the storage and loss moduli below the glass transition temperature. However, the highest amount of zirconia increased the modulus. The presence of zirconia in PC slightly increased the thermal stability, except for the highest zirconia content which showed a decrease. The activation energies of thermal degradation for the nanocomposites were significantly lower than that for pure PC at all degrees of conversion

Influence of temperature on calcium hydroxyapatite nanopowders

The aim of this work is to investigate the effects of thermal treatment, in the range of temperature between 80°C - 900°C, on crystallinity, morphology and particles size of calcium hydroxylapatite nanopowders (HAp). A complete study was carried out applying 31P Magic Angle Spinning NMR, X-ray diffraction, nitrogen porosimetry and Transmis- sion Electron Microscopy techniques. HAp specimens were prepared by chemical precipitation in an aqueous solution of calcium nitrate and ammonium hydrogen phosphate. The thermal treatment performed, showed the formation of crystals whose appearance has three main morphologies and different particles size. HAp treated up to 500°C showed a set of needle-like shape crystals with a low surface area value. These crystals turned into rod-like crystals with tem- perature increase, along with an increase in crystallite size. At 900°C was detected a hexagonal hydroxylapatite phase. Furthermore, Dynamic Light Scattering explored a stable HAp dispersion. The isopropyl alcohol dispersion resulted stable for at least two weeks, useful to create layers of determined morphology nanoparticles

Chemogenic versus biogenic synthesis of Selenium nanoparticles: a structural characterization

Among the plethora of available metal- and metalloid-based nanomaterials (NMs), selenium nanostructures (SeNSs) are one of the most interesting from an applicative perspective due to their intermediate properties between metals and non-metals, as well as their high biocompatibility. In this regard, the capability of microorganisms to biotransform toxic Se-oxyanions – i.e., selenite (SeO32-) and selenate (SeO42-) – into their less bioavailable elemental forms [Se(0)], mostly generating Se nanoparticles (SeNPs), represents as a useful and green alternative over chemogenic synthesis allowing to obtain highly thermodynamically stable NMs. However, their structural characterization, in terms of biomolecules and interactions stabilizing the biogenic colloidal solution, is still a black hole in the microbial nanotechnology field, impairing the exploitation of biogenic SeNP full potential. Here, a parallel characterization between biogenic and chemogenic SeNPs was carried out through Fourier Transform Infrared spectroscopy in Attenuated Total Reflectance (ATR-FTIR) mode, Nuclear Magnetic Resonance (NMR) spectroscopy, and Density Functional Theory (DFT) calculations, to better understand which functional groups, hence biomolecules, contribute the most to the stabilization of biogenic SeNPs

Polysaccharide-based biodegradable films for agricultural mulching

In the last 20 years, the global population has blowout growth from 6.0 billion to 7.2 billion and will reach over 8.0 billion around 2046 [1]. Consequently, food shortage has drawn attention, and the demand for agricultural products has increased annually. To meet this need, the excessive and prolonged use of mulching films based on low-density polyethene resulted in significant environmental pollution events, leading to serious side effects on human health [2]. Due to the thickness of the plastic film and the difficulty of recovery, some mulch films were discarded in agricultural soils intentionally or unintentionally. Mulch film residue is a direct source of farmland meso- and microplastics (MMPs), which constitute a global environmental issue, as they accumulate even in the food chain [3]. MMPs' further degradation into nanoscale particles can endanger human health [4]. To provide agricultural sustainability, there is a great interest in developing biodegradable bio-based polymeric films for agriculture mulching, which can be tilled directly into the soil after use. Based on the above issues, this study aims at (i) the preparation and characterisation of biodegradable bio-based composite films and (2) their enrichment with plant nutrients, which could be efficiently released into the water to sustain their application as mulch films on the soil. Sodium carboxymethyl cellulose (CMC), chitosan (CS) and sodium alginate (SA) were combined in the presence of glycerol as a plasticiser to produce composite films by solvent casting. Composition (i.e., concentrations and mass ratios between the precursors) and cross-linking agent (CaCl2) effects on films' properties were evaluated. In the first stage, we investigated the structure of the formed films through Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy, the thermal and mechanical properties by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA), and some water-interaction properties (degree of swelling and solubility in water). This approach allowed identifying the best quality films, which were enriched with NH4H2PO4, as N and P are generally the most deficient nutrients in the soil. Moreover, the release kinetics in the water of this salt was studied. The latter aspect is of great importance as the release of N and P helps to improve the nutrient supply to the soil, thus reducing the use of synthetic fertilisers. [1] B. Chieng et al. J. Appl. Polym. Sci. 130 (2013) 4576-4580 [2] H. M. S . Akhtar, et al. Int. J. Biol. Macromol. 118 (2018), 469-477 [3] M.C. Rillig, M. C. Environ. Sci. Technol. 46 (2012), 6453-6454 [4] I. Ali et al. J. Clean. Prod. 313 (2021) 12786

Pt(II) complex @mesoporous silica: preparation, characterization and study of release

Cisplatin analogs, having cytotoxic activity higher than that exerted by cisplatin, have recently triggered considerable interest by the community. The cis-[PtCl2(DMSO)HL]·2DMSO, where HL = 7-amino-2-(methylthio)[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid, has shown a potent cytotoxic activity on HepG2 hepatocarcinoma cells, while under identical conditions, it did not affect normal immortalized human liver cells (Chang). In this work, the above complex has been incorporated into MCM41 mesoporous silica, pure and functionalized with amino group, which is considered one of the best host for a drug delivery system for carrying high dosages of a variety of drugs in their mesopores. Since the controlled release of an anticancer drug helps to maintain its therapeutic level for an extended time period while minimizing undesirable high peaks immediately following administration, the in vitro tests have been performed in order to obtain the corresponding drug release profile. The investigated system demonstrated to be an efficient system for pharmaceutic controlled release. A deepened characterization of the systems has been performed in order to known their structure and features and to speculate the mechanisms involved in the release