Synthesis and Reactivity of Mevinolin-Like Lactone Precursors

The synthesis of mevinolin-like lactone precursors and the evaluation of their ability in the N-alkylation of N-potassium-phthalimide are reported.     

Stabilization of Titanium Dioxide Nanoparticles at the Surface of Carbon Nanomaterials Promoted by Microwave Heating

TiO₂ is frequently combined with carbon materials, such as reduced graphene oxide (RGO), to produce composites with improved properties, for example for photocatalytic applications. It is shown that heating conditions significantly affect the interface and photocatalytic properties of TiO₂@C, and that microwave irradiation can be advantageous for the synthesis of carbon‐based materials. Composites of TiO₂ with RGO or amorphous carbon were prepared from reaction of titanium isopropoxide with benzyl alcohol. During the synthesis of the TiO₂ nanoparticles, the carbon is involved in reactions that lead to the covalent attachment of the oxide, the extent of which depends on the carbon characteristics, heating rate, and mechanism. TiO₂ is more efficiently stabilized at the surface of RGO than amorphous carbon. Rapid heating of the reaction mixture results in a stronger coupling between the nanoparticles and carbon, more uniform coatings, and smaller particles with narrower size distributions. The more efficient attachment of the oxide leads to better photocatalytic performance.     

Search of single long-period oscillations in the daily temperatures

Summary Long-period oscillations have been searched in the time series of the daily minimum, mean and maximum temperatures measured in Modena, Italy, during the years 1869–1976. By assuming only one oscillation present, the amplitude and its statistical uncertainty have been estimated by means of a fitting procedure which takes into account the stochastic variability of the daily temperatures. The period of the long-term oscillations has been chosen to be an integer number of years (from 2 up to 36). This choice and the fit performed over a suitable number of years (the maximum possible multiple of the period) ensure a numerical stable solution and a negligible correlation between the long-period oscillation and the annual and seasonal oscillations present in the time series. The instrumental uncertainty of the long-period amplitude has been also evaluated. Within the overall uncertainty, no reliable evidence exists on single long-period oscillations.

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Riassunto Sono state cercate oscillazioni singole a lungo periodo nella serie temporale formata dalle temperature minime, medie e massime, misurate giornalmente a Modena durante gli anni 1869–1976. Nell'ipotesi di un'unica oscillazione sono state stimate l'ampiezza dell'oscillazione e la sua incertezza statistica mediante un procedimento di approssimazione che teneva conto della variazione stocastica delle temperature giornaliere. Come periodo delle oscillazioni a lungo termine si è scelto un numero intero di anni compreso fra 2 e 36. L'approssimazione è stata effettuata su un numero di anni che era il massimo multiplo del periodo compatibile con i dati disponibili. Con tali scelte le soluzioni risultano numericamente molto stabili. Inoltre le correlazioni fra i diversi parametri stimati in ciascuna approssimazione risultano trascurabili. è stato anche valutato l'effetto dell'errore sistematico di misure sull'ampiezza dell'oscillazione a lungo periodo. Dai risultati non emergono prove affidabili sull'esistenza di oscillazioni singole a lungo termine entro la risoluzione statistica e sistematica del presente studio.

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Резюме Проводится поиск осцилляций с большим периодом во временной последователвности суточных минимальных, средних и максимальных температур, измеренных в Модене, Италии, в течение 1869–1976 г. г. Предполагал, что существует только одна осцилляция, оценивается амплитуда и статистическая неопределенность, оспользуя процедуру подгонки, которая учитывает стохастическое изменение суточных температур. Период продолжителяной осцилляции выбирается равным целому числу лет (от 2 до 36). Этот выбор и проведенная подгонка соответствующего числя лет (максимально возможное кратное периоду) обеспечивают численное устойчивое решение и позволяйт пренебречь корреляцией между осцилляцией с большим периодом и ежегодными и сезонными осцилляциями, присутствующми во временной последовательности. Оценивается инструментальная неопределенность амплитуды осцилляции с большим периодом. С учетом полной неопределенности не обнаружено нодежного подтверждения отдельных осцилляциь с большим периодом.

     

Geographical determination of pixels. Time observation of ground points from satellites

Summary A pixel localization method in remote-sensed images through orbit and sensor swath simulation is described, thus avoiding traditional corrections of images. Consequently the quality of radiance data for each pixel is not affected by the geometric interpolations. The computer program even allows a precise predetermination of observed ground points, thus permitting an exact scheduling of field measurements. The method requires as input the parameters of the orbit which is assumed to be circular, and the three angles which give the attitude of the satellite. In the case of these parameters being unknown, the program allows an estimate by minimizing the sum of the squares of the differences between grid points and ground points assumed to be known. Also described is a procedure for the correction of atmospheric refraction. As an example, the method was applied to a NOAA7 image, and a discussion of the results obtained follows. This work has been supported by the Consiglio Nazionale delle Ricerche, Italy.     

Evidence of an anthropogenic climatic change in the daily temperatures of Modena, Italy

Summary The daily minimum, mean and maximum temperatures, measured in Modena, Italy, in the years 1869–1976 have been analysed in order to detect possible long-term trends. An increasing trend appears to be present both in the minimum and in the mean temperature with a reasonable confidence level. The presence of a trend in the maximum temperatures instead is questionable. The trends have been estimated by means of a procedure which provides also the statistical uncertainty of the parameter representing the trend. The uncertainty due to the errors of the measuring instruments has been also evaluated. The trends do not show any clear seasonal pattern. The overall behaviour of the trends (for the three daily temperatures) and the lack of a seasonal pattern can be explained by a ?greenhouse? effect due to the increasing town. The experimental results and the explanation suggested are quite consistent with similar results and conclusions found elsewhere.

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Riassunto Sono state analizzate le temperature giornaliere minime, medie e massime misurate nella città di Modena nel periodo 1869–1976, at fine di mettere in evidenza eventuali tendenze a lungo termine. Nelle temperature giornaliere minime e medie esiste una tendenza all'aumento con un ragionevole livello di affldabilità. Viceversa è più dubbia la presenza di una tendenza nelle temperature giornaliere massime. Il parametro che rappresenta la tendenza a lungo termine è stato stimato mediante una procedura che permette di ottenere la sua varianza. Oltre alla parte statistica è stata stimata anche l'incertezza causata dagli errori strumentali. Le tendenze a lungo termine stimate non risentono di effetti stagionali. Il comportamento delle tendenze a lungo termine (caratterizzate dall'aumento in due sole temperature giornaliere) e la mancanza di effetti stagrionali può essere spiegata da un effetto ?serra? causato dall'accrescimento della città. I risultati sperimentali e la spiegazione che è proposta sono compatibili con analoghi risultati e conclusioni già trovati altrove.

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Резюме Чтобы определить возможные долгосрочные тенденции, анализируются ежедневные минимальные, средние и максимальные температуры, измеренные в Модене (Италия) в период 1869–1976 г.г. Обнаружена тенденция увеличения минимальных и средних температур. Однако наличие тенденции для максимальной температуры является сомнительным. Указанные тенденции установлены с помощью процедуры, которая дает также статистическую неопределенность параметра, характеризующего тенденцию. Также оценивалась неопределенность, обусловловленная ошибками аппаратуры измерений. Тенденции не обнаруживают каких-либо ясных сезонных характеристик. Общее поведение тенднций (для трех ежедневных температур) и отсутствие сезонных особенностей может быть объяснено с помощью эффекта, обусловленного растущими городами. Полученные экспериментальные результаты и предложенное объяснение сотласуются с аналотичными результатами и выводами, полученными ранее.

     

Elliptic phases: a study of the nonlinear elasticity of twist-grain boundaries

We develop an explicit and tractable representation of a twist-grain-boundary phase of a smectic-A liquid crystal. This allows us to calculate the interaction energy between grain boundaries and the relative contributions from the bending and compression deformations. We discuss the special stability of the pi/2 grain boundaries and discuss the relation of this structure to the Schwarz D surface.     

Correlation between carbon nanotube microstructure and their catalytic efficiency towards the p-coumaric acid degradation

Pristine and annealed multi-walled C nanotubes are preliminarily tested as catalysts towards the degradation of p-coumaric acid with better performances than the widely used activated carbon. In order to clarify the origin of their different catalytic efficiency, the samples are analysed by means of high-resolution transmission electron microscopy, X-ray photoemission, reflection electron energy loss and micro-Raman spectroscopy. Chemical composition, mass density, bonding configurations and threefold- to fourfold-coordinated carbon bonding ratios are determined. The comparative discussion of the results obtained leads to attribute the higher catalytic activity of the pristine nanotubes to their larger sp²/sp³ carbon bonding fraction and greater amount of oxygen containing functional groups.     

Developed smectics: when exact solutions agree

In the limit where the bending modulus vanishes, we construct layer configurations with arbitrary dislocation textures by exploiting a connection between uniformly spaced layers in two dimensions and developable surfaces in three dimensions. We then show how these focal textures can be used to construct layer configurations with finite bending modulus.