HIGH-PRESSURE BEHAVIOR OF MICROPOROUS MATERIALS: CRYSTAL-FLUID INTERACTIONS AND DEFORMATION MECHANISMS AT THE ATOMIC SCALE

Zeolite are crystalline, hydrated aluminosilicates characterized by a tetrahedral framework of TO4 units connected in such a way that sub-nanometric channels and cages occur. These structural cavities host the so-called extra-framework population, which mainly consists of alkali and alkaline-earth cations and small molecules, such as H2O. In the last decades, the scientific community showed a rising interest on the behavior of microporous and mesoporous compounds (e.g., zeolites) at high-pressure conditions, and in particular on the crystal-fluid interaction phenomena occurring at extreme conditions. As zeolites could act as an ideal carrier of H2O and others small molecules or monoatomic species (e.g., CO2, CH4, H2S, He, Ar, Kr, Xe,\u2026), experiments on zeolites compressed (and ambient to low/high T) in aqueous mixtures have important implications in the Earth Sciences. Furthermore, high-pressure experiments on synthetic zeolites may pave the way for new routes of tailoring new functional materials (made by hybrid host-guest architecture), bearing a potentially relevant technological impact. In this experimental thesis, after an overall introduction and a section on the high-pressure experimental techniques (Chapter 1 and 2 , respectively), the high-pressure behavior and the crystal-fluid interaction at the atomic scale of a selected series of natural and synthetic zeolites (i.e., AlPO4-5, leonhardite, laumontite, phillipsite) and a zeolites-like mineral (i.e., armstrongite) have been investigated by means of in-situ single-crystal X-ray diffraction, using \u201cpenetrating\u201d and \u201cnon-penetrating\u201d pressure-transmitting fluids. Into details: 1. AlPO4-5 (Chapter 3): the high-pressure behavior of AlPO4-5 has been studied by single crystal XRD using synchrotron radiation and a diamond anvil cell (DAC), with crystals compressed in silicone oil and methanol:ethanol:water =16:3:1 (m.e.w.) mixture. The high-pressure evolution of the crystalline structure and the deformation mechanism at atomic scale have been described on the basis of high-quality structure refinements, revealing adsorption phenomena of H2O (and likely methanol) already at 2 Kbar. Moreover, evidence of an incommensurately modulated structure of AlPO4-5 have been found. 2. Leonhardite and laumontite (Chapter 4): the H2O adsorption kinetics, at ambient pressure and temperature, of leonhardite to give laumontite has been investigated using single crystal XRD techniques. In-situ high-pressure XRD experiments, using synchrotron radiation and a DAC, have been performed in order to obtain the bulk moduli of the two minerals (previously unknown). A detailed description of the atomic deformation mechanisms has been addressed. 3. Phillipsite (Chapter 5): the pressure-induced deformation mechanisms, at the atomic scale, have been studied via single crystals XRD-experiments, using synchrotron radiation and a DAC. Despite no pressure-induced adsorption was observed, the experimental findings suggest a change in the deformation mechanisms induced by a re-arrangement of the extra-framework population. 4. Armstrongite (Chapter 6): the high-pressure evolution of this zeolite-like mineral has been studied in the m.e.w. as nominally penetrating fluid. A first-order phase transition has been detected between 4 and 5 GPa. In the Chapter 7 a detailed discussion of the aforementioned experimental findings has been addressed, along with their technological and geological implications. The results of the present studies have been published in peer-reviewed journals

Phase transitions and crystal structure evolution of hydrated borates at non-ambient conditions

Hydrated borates are a class of minerals composed of clusters or chains of Bφx groups (where φ represents an oxygen atom, a H2O molecule, or an OH- group) organized either in tetrahedra or planar triangular groups. Hydrated borates are considered a more cost-effective alternative to B4C in radiation-shielding concretes [1], primarily due to the significant cross-section (~3840 barns) for thermal neutrons of the 10B isotope, which represents approximately 20% of natural boron. It is advisable to comprehensively characterize the crystal chemistry, elastic properties, P-T phase stability fields, and structural behaviour of natural borates under varying temperature and pressure conditions to model and understand their role as aggregates in radiation-shielding concretes [2], where the components experience pressure (via static compression) and temperature (via irradiation). Since 2018, my research group has conducted an extensive study of economically valuable hydrated borates, as well as common complementary phases occurring in borates deposits. High-pressure investigations of all studied hydrated borates have revealed one or more phase transitions occurring at pressures below 11 GPa, and the occurrence of these transitions appears to be highly correlated with the H2O content of the minerals (e.g., [3-4]). In response to the phase transitions, the most significant structural change observed in our experiments is the increase in the coordination number of alkali/alkaline-earth cations as well as of part of the boron population, from IIIB to IVB, due to the interaction between IIIB and H2O molecules. This, on the other hand, emphasizes the importance of the hydrogen bond network, usually with complex and pervasive configuration, in preserving the stability of the crystalline edifice of this class of materials. References 1. Okuno K. (2005). Radiat. Prot. Dosimetry. 115, 258–261. 2. Torrenti J. and Nahas G. (2010) Int. Conf. Concr. under Sev. Cond., Merida, Yucatan. 3–18 3. Comboni D., Pagliaro F., Gatta G. D., et al. (2020) J. Am. Ceram. Soc. 103:5291–5301 4. Comboni D., Poreba T., Pagliaro F., et al. (2021) Acta Crystallogr. B 77:940–945

A CROSS-SECTIONAL STUDY ABOUT FACTORS CONTRIBUTING TO USE OF ANTIBIOTICS AMONG RESIDENTS OF MOROTO PARISH IN PALABEK GEM SUBCOUNTY, AGED FROM 18- 65 YEARS IN LAMWO DISTRICT (UGANDA).

Background The objectives of the study were; to determine the demographic factors leading increased use of antibiotics, to assess the knowledge of the residents of Moroto parish in Palabek sub-county on antibiotic use, and to determine the socio-economic factors that lead increased use of antibiotics among residents of Palabek Gem sub-county. Methodology A descriptive cross-sectional design and a self-administered questionnaire well designed were used on 50 respondents obtained through a random sampling technique. The data obtained were presented through tables, graphs, and pie charts and then analyzed. Results Majority of respondents (54%) were women, and most of the respondents (42%) were between 18-30 years. Poor knowledge of causative agents treatable by Abs and good knowledge of ABR were shown by 82% of respondents. 86% of the respondents were low-income earners. There is generally increased use of Abs with women taking the lead. 58% of respondents do not show respect to doctors’ decision not to prescribe Abs if it is not relevant. The study also revealed that there is easy access to Abs as reported by 68.0% of respondents,78.0% of respondents shared Abs with family members while Leftover Abs were highly used by 78.0% of respondents. Conclusion There is a high use of Abs. There’s easy access to Abs with Clinics and Pharmacies noted as a chief source though leftover antibiotics are also being widely used. The respondents had an average and staggering overall knowledge of Abs use which is not pleasing. Most of the respondents do not value doctors’ decisions not to prescribe Abs. Recommendation  The government to put more effort into controlling the use of Abs both among the population and the medical workers altogether. And also studies on the community members to find out their views/ opinions on strategies that help best curb the increased use of antibiotics

High-pressure behavior and pressure-driven phase transitions in hydrated borates

Hydrated borates (e.g., colemanite, ulexite, kernite and borax) are the most common ore minerals of boron, an important geochemical marker, in particular in pegmatitic and granitic systems, for petrogenetic processes and a strategic element in a series of technological applications. In hydrated borates, the main structural units are Bφx units (tetrahedra and planar trigonal group where φ is an anion, O2- or OH-), connected in such a way to form clusters of polyions connected to alkaline/Earth alkaline (mainly Na+, K+, Ca2+, Mg2+) polyhedra. In these structures, H2O molecules and OH- form a complex and pervasive hydrogen-bond network, often enhancing the connection between the polyions clusters and the cations-polyhedra, therefore playing a paramount role in the stability of the crystalline edifice. The aim of this contribution is to analyze and provide insides on the high-pressure behavior and structure evolution of a number of hydrate borate minerals, unveiling the phase transition driving deformation mechanisms that lead to the formation of their high-pressure polymorphs. A common pattern, that could be used to predict the high-pressure phase stability of this class of minerals, has been detected

Eros e Anteros nella poesia italiana del Rinascimento : appunti per una ricerca

Nell’ultimo decennio ben due convegni hanno richiamato l’attenzione degli studiosi di letteratura rinascimentale sulla figura di Anteros, « une figure mythologique quelque peu oubliée et qui réapparait obstinément dans la littérature et l’iconographie à l’aube des temps modernes ». Sulla scorta di un noto intervento di Robert V. Merrill, si è così cercato di mettere a fuoco le diverse funzioni e i contraddittori significati che in epoca umanisticorinascimentale sono stati attribuiti a ques..

Unveiling the high-pressure transitions in hydrated borates at ID15b, ESRF

Natural borates (e.g., ulexite, colemanite, kernite and borax) are the most common ore minerals of boron, strategic element in a series of technological applications. In hydrated borates, the main structural units are Bφx units (tetrahedra and planar trigonal group where φ is an anion, O2- or OH-), connected in such a way to form clusters of polyions connected to alkaline/Earth alkaline (mainly Na+, K+, Ca2+, Mg2+) polyhedra. In these structures, H2O molecules and OH- form a complex and pervasive hydrogen-bond network, often enhancing the connection between the polyions clusters and the cations-polyhedra, therefore playing a paramount role in the stability of the crystalline edifice. Hydrated borates can act as neutron-shielding materials, due to the isotope 10B (which accounts for about 20% of the natural boron) high cross-section for thermal neutrons (~3840 barns) [1]. Enhanced neutron radiation shielding capacity is achievable by using boron-containing minerals as aggregates in concretes. Notably, a comprehensive characterization of the crystal-chemistry, elastic parameters, phase-stability and structural behaviour (at the atomic scale) at different T and P conditions, is still missing for most hydrated borates. The aim of this contribution is to analyze and provide insides on the high-pressure behavior and structure evolution of a number of hydrate borate minerals, unveiling the phase transition driving deformation mechanisms that lead to the formation of their high-pressure polymorphs

Giovan Battista Pio a Milano 1497-1500

The paper illustrates Giovan Battista Pio’s Milanese period (1497-1500), during which the Bolognese humanist published editions with commentary of Fulgentius, Sidonius Apollinaris, Plautus and prepared an important edition of Varro, Festus, Nonius. The analysis of paratextual elements inserted in these editions has permitted to reconstruct Pio’s Milanese relationships.   Il contributo illustra il soggiorno milanese (1497-1500) di Giovan Battista Pio, durante il quale l’umanista bolognese pubblicò edizioni commentate di Fulgenzio, Sidonio Apollinare, Plauto e preparò un’importante edizione di Varrone, Festo e Nonio. L’esame dei paratesti di queste edizioni ha reso possibile avviare la ricostruzione delle relazioni milanesi del Pio

High-pressure behavior of intermediate scapolite : compressibility, structure deformation and phase transition

Scapolites are common volatile-bearing minerals in metamorphic rocks. In this study, the high-pressure behavior of an intermediate member of the scapolite solid solution series (Me47), chemical formula (Na1.86Ca1.86K0.23Fe0.01)(Al4.36Si7.64)O24[Cl0.48(CO3)0.48(SO4)0.01], has been investigated up to 17.79 GPa, by means of in situ single-crystal synchrotron X-ray diffraction. The isothermal elastic behavior of the studied scapolite has been described by a III-order Birch\u2013Murnaghan equation of state, which provided the following refined parameters: V0 = 1110.6(7) \uc53, KV0 = 70(2) GPa (\u3b2V0 = 0.0143(4) GPa 121) and KV\u2032 = 4.8(7). The refined bulk modulus is intermediate between those previously reported for Me17 and Me68 scapolite samples, confirming that the bulk compressibility among the solid solution increases with the Na content. A discussion on the P-induced structure deformation mechanisms of tetragonal scapolite at the atomic scale is provided, along with the implications of the reported results for the modeling of scapolite stability. In addition, a single-crystal to single-crystal phase transition, which is displacive in character, has been observed toward a triclinic polymorph at 9.87 GPa. The high-pressure triclinic polymorph was found to be stable up to the highest pressure investigated

Exploring Pressure-Induced Crystal Structure and Fluid Interactions in ABC-6 Zeolite Group

The infiltration of molecules (or solvated ions) into the nano-cavities of microporous materials opens new routes for enhancing mass transfer from fluids to molecules incorporated in the structure. Thoroughly exploring this phenomenon, in both synthetic and natural zeolites, could expand their industrial applications, such as the development of new functional materials and enhancement of catalytic performance [1,2]. From a geological standpoint, understanding this phenomenon can unveil the role played by zeolites as fluid carriers during the early stages of subduction of oceanic sediments and altered basalts. In this research, we examined the interaction between crystals and fluids, driven by pressure, in three distinct natural zeolites belonging to the ABC-6 group: erionite (ERI framework type, 6-membered ring sequence: ABBACC), offretite (OFF, with AAB seq.), and bellbergite (EAB, with AABCCB seq.). The objectives of the experiments were: 1) to understand the potential role of erionite as a fluid carrier during subduction, given its presence, as a secondary mineral, in altered oceanic basalts [3]; and 2) to compare the mechanisms employed by structurally similar frameworks (characterized by the presence of 6-membered rings) in accommodating bulk compression and adsorbing new molecules. The results revealed that erionite, a common zeolite, exhibits the highest magnitude of adsorption among the studied species. Additionally, the occurrence and magnitude of the phenomena were found to be governed by the H2O content of the hydrous P-transmitting fluids. Offretite framework allowed Ne atoms to penetrate into the 12mRs channel in response to applied pressure, exhibiting weak Van der Waals interactions with the extra-framework population