People from Brač, emigrant press in Chile and newspaper Domovina - from the late 19th century to the beginning of World War I

Cilj je rada postaviti ishodišta za proučavanje povijesti hrvatskog iseljeničkog novinstva u Čileu od najranijeg razdoblja doseljenja Hrvata do kraja 1914. godine, među kojima je brojčano dominantnu grupaciju činilo stanovništvo s Brača. Radilo se prvenstveno o ekonomskoj migraciji uzrokovanoj ekonomskim promjenama u društvu općenito, ali i ekonomskim promjenama kao posljedicama političkih kretanja. U novu domovinu donose tradicionalnu potrebu organiziranja u razna društva, ali i svijest o vlastitoj nacionalnoj pripadnosti s vlastitim jezikom. Neobično brza asimilacija (već u prvoj generaciji) dovodi u pitanje opstojnost te potrebu očuvanja baštine. Iseljeničke novine u kojima surađuju, uređuju ih i pokreću Bračani – novinari, među kojima se ističu Ivan Krstulović i Luka Bonačić s novinama „Domovina“ iz Punta Arenasa, u dosadašnjoj literaturi sagledavane su gotovo isključivo s aspekta političke orijentacije i borbe. Cilj je rada kroz primjer rubrike „Iz mjesta i okolice“, koja je održala kontinuitet tijekom cijelog razdoblja izlaženja lista „Domovina“ i čijim je sastavnim dijelom bila, prikazati, s aspekta socijalne povijesti, da su lokalne novine odražavale i bilježile pojave i događanja značajna za svakodnevni život zajednice sa svrhom očuvanja njezina identiteta.The topic of this paper is to set the starting point for studying the history of Croatian emigrant journalism in Chile from the earliest period of the settlement of Croats until the end of 1914, including the dominant population group from Brač. It was primarily the economic migration, which was caused by economic changes in the society in general, and economic changes as a consequence of political movements. The immigrants had the need for organizing themselves in various societies in the new country, and they also had the awareness of their own nationality and language. The unusually rapid assimilation (already in the first generation) calls into question the viability and the need to preserve heritage. Immigrant newspapers edited and run by Brač emigrant journalists, most notably Ivan Krstulović and Luka Bonačić, with the newspaper Domovina from Punta Arenas, were in the current literature perceived almost exclusively in terms of political orientation and struggle. The aim of this paper is to show that the local newspaper Domovina reflected and recorded phenomena and events significant for the daily life of the community with the intention of preservation its identity from the perspective of social history, especially in the section From the town and surrounding areas

Toward the Understanding of the Comonomer Effect on Cr^II/SiO₂ Phillips Catalyst

The origin of the “comonomer effect” (i.e., the enhancement of ethylene polymerization rate in the presence of α-olefin comonomer) on Cr^II/SiO₂ Phillips catalyst was investigated by means of <i>in situ</i> FT-IR and Diffuse Reflectance UV–vis spectroscopies. A nonpolymerizing olefin, cyclohexene, was chosen as “comonomer” and introduced on the catalyst prior the monomer injection in order to produce only homopolymers. Under our experimental conditions, α-olefin (ethylene, propene, and 1-hexene) homopolymerization is enhanced up to a factor of 5. Our experimental data provide the first direct evidence that the comonomer strongly interacts with all the Cr^II sites and that it is responsible for their structural and electronic rearrangement at a molecular scale, as proposed for the “trigger mechanism”. We also proved that the fraction of Cr actives sites do not retain the comonomer during the olefin polymerization, meaning that the increased reactivity is due to a modification influencing all the catalyst Cr sites

Spectroscopic and Structural Characterization of Thermal Decomposition of γ‑Mg(BH₄)₂: Dynamic Vacuum versus H₂ Atmosphere

Magnesium borohydride [Mg­(BH₄)₂] attracts a particular interest as a material for hydrogen storage because of its high gravimetric capacities and being suggested as a rehydrogenable compound. Although extensively studied, besides the whole decomposition process, a large debate is still present in the literature about the temperatures leading to the different (and in many cases, unknown) products. In this paper, an ad hoc designed thermogravimetric study, together with a critical review of literature data, allowed us to identify the products for low reaction rates. Two reaction environments have been considered: dynamic vacuum and hydrogen atmosphere. In order to guarantee quasi-equilibrium conditions, the samples were obtained after 20 h isotherms in the room temperature to 400 °C range. The decomposition of γ-Mg­(BH₄)₂ has been here characterized by adopting a new approach and by X-ray diffraction (XRD) and medium-infrared spectroscopy, together with experimental techniques used for the first time for this process (far-infrared and UV–vis–near-infrared spectroscopies). Density functional calculations were performed to help the identification of the amorphous products. A possible process mechanism was delineated and in particular that (a) Mg­(BH₄)₂ decomposition starts at 200 °C; (b) MgB₄H₁₀ is proposed, for the first time, as the phase responsible for its reversibility for <i>T</i> < 270 °C, which would implicitly restrict the Mg­(BH₄)₂ reversible capacity to 3.7 mass %

UV-Raman Fingerprint of Brønsted Sites in MFI Zeolites: A Useful Marker in Dealumination Detection

In the present work, a detailed UV-Raman characterization of a set of protonic MFI zeolites with variable Si/Al ratio is presented. A new vibrational feature was detected: interestingly, such peak is present only when samples are carefully activated. Moreover, its intensity is quantitatively related to the Al content of the framework through a direct law. On these bases, the origin of the vibrational mode can be attributed to the Brønsted acid site. The assignment was further supported by means of exchange experiments (with deuterium, sodium and ammonium), demonstrating the relevant contribution of the Brønsted proton in this peculiar vibration. Finally, by applying a steaming-like treatment (known to be able to induce dealumination), the observed decrease in the mode intensity was related to the leaching of Al atoms out of the framework, i.e., to the destruction of a fraction of the former Brønsted sites population. In this regard, the monitoring by UV-Raman of such signal could represent an useful marker in detecting steaming and/or reaction induced dealumination in acidic zeolites

In Situ Resonant UV-Raman Spectroscopy of Polycyclic Aromatic Hydrocarbons

PAHs are hazardous and persistent pollutants, also found as byproducts of some petrolchemical reaction (e.g., MTH) in relation to the catalyst deactivation, i.e., to the formation of coke species. The analysis of such deactivation products is typically performed by means of chromatographic techniques, with some drawbacks: the extraction and separation of the molecules from the matrix (the catalyst) is always required, and the solubility of the larger ones is often very low also in nonpolar solvents, so that their analysis is not possible with a standard approach. Spectroscopies can represent an interesting alternative for the qualitative analysis of PAHs: in particular Raman spectroscopy has been demonstrated to be a powerful tool in the characterization of carbonaceous materials and PAHs, and the possibility to exploit the resonance effect (allowing the selective enhancement of vibrational features of the resonant species) can be a considerable advantage in the analysis of very diluted species. In the present work, PAHs have been characterized by means of UV Raman spectroscopy: the 244 nm excitation wavelength allowed to exploit the resonance effect and in the meantime to avoid interference due to the visible fluorescence typical of these molecules. A pool of representative PAHs have been analyzed in their pure form, in diluted solution, and dispersed on high surface area microporous supports: the collected data constitute a reference database to be compared with the deactivation products observed during petrolchemical reactions, offering the possibility to univocally identify them

Particles Morphology and Surface Properties As Investigated by HRTEM, FTIR, and Periodic DFT Calculations: From Pyrogenic TiO₂ (P25) to Nanoanatase

By combining electron microscopy, FTIR spectroscopy of different CO isotopic mixtures, and DFT calculations, a complete assignment of the IR spectrum of CO adsorbed on P25 (a mixture of 85% anatase and 15% rutile) at various dehydration states, on its pure rutile component, and on nanoanatase was obtained. It is shown that the measurements at 60 K provide IR spectra of unprecedented quality and that the spectroscopic method is extremely powerful not only to study the surface Lewis and Brønsted acidity but also to investigate the particles morphology. Indeed, as CO adsorbed on different faces is characterized by different stretching frequencies, the IR spectrum contains information on the exposed faces and hence on particles morphology. This information, combined with the study of the IR spectrum of CO adsorbed on defects, of dipole–dipole interactions between parallel oscillators adsorbed on extended faces and with HRTEM results allowed us to fully explore the relations between particles morphology and surface properties. By comparing the spectra of CO obtained on P25, on the pure rutile fraction of P25, and on nanoanatase, the high crystalline character of P25 is inferred, which is likely the key of its outstanding photocatalytic activity. It is also found that the IR spectrum of CO on P25 is the sum of the rutile and anatase contributions and that no additional surface features ascribable to anatase–rutile junctions are noticeable, thus contributing to the strong debate present in the literature

Synthesis and Characterization of High-Surface-Area Silica–Titania Monoliths

Hybrid SiO₂–TiO₂ mesoporous monoliths were synthesized via sol–gel method. The water for hydrolysis of titanium precursor has been obtained in situ via esterification reaction between acid and alcohol without use of additional agents. The titania content in the samples has been varied from 2 to 40 M% molar content with respect to silica. The nitrogen adsorption isotherms showed that monoliths containing 2 M% of Ti retain a large surface area and micropores with size peaking in the 1 to 2 nm interval. For larger Ti content, a bimodal average micropores distribution is observed. The surface area decreases for titania content larger than 10 M%. The Raman spectra taken with excitation lines in the 244–785 nm interval and the UV–vis measurements demonstrate that in the 2 M% sample Ti is atomically dispersed and fully incorporated in the SiO₂ framework and that the local structure is similar to that of titanium silicalite. This conclusion is further confirmed by XAS measurements. Also, the reactivity toward hydrogen peroxide is similar. For larger Ti concentrations, the presence of segregated anatase particles grown in restricted space is observed, as demonstrated by XRD, TEM, Raman, and UV–vis measurements. The surface properties of the silica matrix and of the embedded anatase nanoparticles have been fully characterized by FTIR spectra of CO probe adsorbed at 100 K. Unlike the samples with 5–20 M% Ti, the 40 M% Ti system is fully amorphous, and only small traces of crystalline TiO₂ are present

Rutile Surface Properties Beyond the Single Crystal Approach: New Insights from the Experimental Investigation of Different Polycrystalline Samples and Periodic DFT Calculations

The relationships between particle morphology and surface properties for different kinds of rutile polycrystalline samples have been thoroughly investigated, combining FTIR spectroscopy of CO adsorbed at 60 K through the carbon end on surface Ti⁴⁺ centers, electron microscopy, and periodic DFT calculations. We provide a complete assignment of the FTIR spectra of CO adsorbed on micro- and nanorutile crystals with well-defined morphology, on commercially sourced nanorutile, and on the P25 rutile component. On the basis of these results, the spectrum of CO on native P25 is revisited. Of special interest is the fact that the (110) rutile main surface undergoes a thermally induced relaxation process, leading to the shielding of exposed Ti⁴⁺ sites and consequently to the reduction of the polarizing power. This process can be reversed by inducing an outward relaxation of the shielded Ti atoms by treating the sample in water at 573 K. A red-shifted band ascribed to CO adsorbed through the oxygen end on the low polarizing sites of relaxed surfaces provides the signature of surface relaxation. CO species interacting through the oxygen end have already been studied for CO on zeolites exchanged with low polarizing alkaline cations but not yet properly discussed for CO on metal oxides

Defect Sites in H₂‑Reduced TiO₂ Convert Ethylene to High Density Polyethylene without Activator

We show the unprecedented potential of commercially available TiO₂ materials reduced in H₂ (H₂-reduced TiO₂) in the conversion of ethylene to high density polyethylene (HDPE) under mild conditions (room temperature, low pressure, absence of any activator), with the consequent formation of HDPE/TiO₂ composites, which have been characterized by electron microscopy. Combination of UV–vis and IR spectroscopies allows one to demonstrate that ethylene polymerization occurs on Ti^4–<i>n</i> defect sites, which behave as shallow-trap defects located in the band gap and, differently from the active sites in the widely used Ziegler–Natta catalysts, do not contain any alkyl (Ti–R) or hydride (Ti–H) ligands. These results represent a step forward the understanding of ethylene polymerization mechanism and open valuable perspectives for commercial TiO₂ materials as catalysts for polyethylene production under mild conditions

Electronic and Geometrical Structure of Zn⁺ Ions Stabilized in the Porous Structure of Zn-Loaded Zeolite H‑ZSM-5: A Multifrequency CW and Pulse EPR Study

Electron spin resonance and hyperfine sublevel correlation (HYSCORE) spectroscopy at X- and Q-band frequencies have been employed, in conjunction with X-ray absorption spectroscopy (XAS), to determine the geometric and electronic structure of Zn⁺ ions in H-ZSM-5 zeolite. Zn⁺ ions were generated by the direct exposure of dehydrated acid H-ZSM-5 to Zn vapors. The number of Zn⁺ ions is found to increase substantially upon UV irradiation. A single EPR active species is detected, indicating a single site of adsorption, characterized by the presence of an Al³⁺ site, as revealed by superhyperfine interactions. The full <b>g</b> (<i>g</i>_<i>x</i> = 1.9951, <i>g</i>_<i>y</i> = 1.9984, <i>g</i>_<i>z</i> = 2.0015) and ²⁷Al |<b>A</b>| (<i>A</i>_<i>x</i> = 2.8, <i>A</i>_<i>y</i> = 2.7, <i>A</i>_<i>z</i> = 4.6) MHz tensors were resolved, allowing for a detailed description of the geometric and electronic structure of Zn⁺ ions stabilized in the cages of H-ZSM-5 zeolite. The dispersion and nuclearity of Zn species formed during the sublimation/irradiation process was assessed by means of XAS spectroscopy, which indicates the absence of metal or metal oxide particles in a significant amount