Templating effect of carbon nanoforms on highly cross‐linked imidazolium network: Catalytic activity of the resulting hybrids with Pd nanoparticles

Two different carbon nanoforms (CNFs), namely multi‐walled carbon nanotubes (MWCNTs) and carbon nanohorns (CNHs), have been chosen as support for the direct polymerization of a bis‐vinylimidazolium salt. Transmission electron microscopy analyses revealed a templating effect of the CNFs on the growth of the polymeric network, which perfectly covers their whole surfaces creating a cylindrical or spherical coating for MWCNTs and CNHs, respectively. Subsequently, the CNFs‐polyimidazolium have been used as stabilizers for Pd nanoparticles (Pd NPs), and the obtained materials have been characterized by means of analytical and spectroscopic techniques and then employed as easily recoverable and recyclable catalysts for Suzuki and Heck reactions. Quantitative conversions have been obtained in almost all the explored reactions, even employing low loading of catalyst (down to 0.007 mol%). Suzuki reactions were carried out in pure water under aerobic conditions. Both materials showed excellent activity and recyclability for the investigated C‐C coupling reactions, with the CNHs‐based material resulting slightly more active than the MWCNTs‐based one due to a higher superficial exposure of Pd NPs.     

Bond Length Alternation Observed Experimentally: The Case of 1H-Indazole

Bond length alternation is a chemical phenomenon in benzene rings fused to other rings, which has been mainly predicted theoretically. Its physical origin is still not clear and has generated discussion. Here, by using a strategy that combines microwave spectroscopy, custom-made synthesis and high-level ab initio calculations, we demonstrate that this phenomenon is clearly observed in the prototype indazole molecule isolated in the gas phase. The 1H-indazole conformer was detected by rotational spectroscopy, and its 17 isotopologues resulting from single and double heavy atom substitution (¹³C and ¹⁵N) were also unambiguously observed. Several experimental structures were determined and, in particular, the most useful semi-experimental equilibrium structure (r_e^SE), allowed determination of the heavy atom bond lengths to milli-Ångstrom precision. The experimentally determined bond length alternation is estimated to correspond to 60:40 contributions from the two resonant forms of 1H-indazole.     

Effect of the Zn2+ distribution on the magnetic properties of Ba2Zn2Fe12O22(Zn2-Y) hexaferrite investigated by thermal-scan Mössbauer spectroscopy

Summary The role of the cation distribution on the magnetic characteristics of Ba₂Zn₂Fe₁₂O₂₂(Zn₂-Y) hexaferrite has been analysed by using M?ssbauer techniques. For this purpose we developed a low-cost microcomputer-controlled thermal-scan M?ssbauer apparatus that allows accurate measurements of the Curie temperature. The measuring times are much shorter than those attained with previously described similar apparata. The variation of the Curie temperature with the sintering temperature of Zn₂-Y has been correlated with different cation distributions of Zn²⁺ among the two tetrahedral sublattices present in the Y-structure.

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Riassunto Utilizzando tecniche M?ssbauer si è analizzato il ruolo della distribuzione cationica sulle proprietà magnetiche dell’esaferrito Ba₂Zn₂Fe₁₂O₂₂ (Zn₂-Y). A questo scopo è stato messo a punto un apparato a basso costo controllato da microcomputer per analisi termiche che utilizza l’effetto M?ssbauer. L’apparecchiatura consente misure di temperatura di Curie con tempi di misura inferiori a quelli di apparecchiature simili descritte in precedenza. La variazione della temperatura di Curie al variare della temperatura di sinterizzazione osservata nell’esaferrito Zn₂-Y è stata correlata con la distribuzione del catione Zn²⁺ tra i due siti tetraedrici presenti nella struttura Y.

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Резюме Используя технику эффекта Мессбауэра, анализируется роль распределения катионов на магнитные свойства гексаферрита Ba₂Zn₂Fe₂O₂₂(Zn₂-Y). Для этой цели предлагается недорогостоящая установка, контролируемая компьютером для тырмического анализа, которая исрользует зффект Мессбауэра. Предложенная установка позволяет точно измерять температуру Кюри, причем времена измерений оказываются существенно меныше, чем у родобных установок, орисанных в литературе. Изменение температуры Кюри в завицимости от температурм спекания Zn₂-Y коррелирует с различными распределениями катионов Zn²⁺ между двумя тетраздрическими подрешетками, присутстствующими в Y-структуре.

     

Adherence to the Mediterranean diet in a Sicilian student population

Since the last decades, socio-economic changes have a key role on eating habits affecting the nutritional status and health of people, in particular children and adolescents. The aim of this study was to compare the diet of student population both normal weight and overweight and obese in order to understand their eating habits by comparing the different diets of the student referring to the Mediterranean diet. The study comprised 337 Sicilian students aged 9 to 13 years, 96 in primary schools and 241 in secondary schools, respectively, in three Sicilian cities namely, Messina, San Piero Patti and Ragusa. The variables studied were height, weight, body mass index (BMI) and adherence to the Mediterranean Adequacy Index (MAI) diet quality indicator. Interestingly, the results highlighted 2.67 MAI mean value for normal weight students while 1.27 MAI mean value indicating a decreased adherence to the Mediterranean diet in overweight students.     

White-light laser cooling of ions in a storage ring

We propose the use of a white laser for laser cooling of ions in a storage ring. The use of a broad-band laser provides a radiation pressure force with wide velocity capture range and high magnitude, which is promising to improve the performance of both longitudinal and indirect transverse cooling. This wide-range force could also be suitable for direct transverse cooling of low-density beams.     

2,6-Diarylhexahydro-4-pyridazinols by acid-catalyzed cyclization of benzaldehyde aryl-2-(2-propenyl)hydrazones

Treatment of benzaldehyde l-(2-propenyl)-4-methylsulfonylphenylhydrazone ( 1f ) with 45% sulfuric acid gave 2-(4-methylsulfonylphenyl)-6-phenylhexahydro-4-pyridazinol ( 2f ) in 35% yield rather than the expected 1-(4-methylsulfonylphenyl)-1-(2-propenyl)hydrazine. The halogen-substituted hydrazones 1c-1e and benzaldehyde 1-(2-methyl-2-propenyl)phenylhydrazone ( 1b ) gave similar results.