One‐pot synthesis of star‐block copolymers using double click reactions

3‐Arm star‐block copolymers, (polystyrene‐b‐poly(methyl methacrylate))₃, (PS‐b‐PMMA)₃, and (polystyrene‐b‐poly(ethylene glycol))₃, (PS‐b‐PEG)₃, are prepared using double‐click reactions: Huisgen and Diels–Alder, with a one‐pot technique. PS and PMMA blocks with α‐anthracene‐ω‐azide‐ and α‐maleimide‐end‐groups, respectively, are achieved using suitable initiators in ATRP of styrene and MMA, respectively. However, PEG obtained from a commercial source is reacted with 3‐acetyl‐N‐(2‐hydroxyethyl)‐7‐oxabicyclo[2.2.1]hept‐5‐ene‐2‐carboxamide (7) to give furan‐protected maleimide‐end‐functionalized PEG. Finally, PS/PMMA and PS/PEG blocks are linked efficiently with trialkyne functional linking agent 1,1,1‐tris[4‐(2‐propynyloxy)phenyl]‐ethane 2 in the presence of CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) at 120 °C for 48 h to give two samples of 3‐arm star‐block copolymers. The results of the peak splitting using a Gaussian deconvolution of the obtained GPC traces for (PS‐b‐PMMA)₃ and (PS‐b‐PEG)₃ displayed that the yields of target 3‐arm star‐block copolymers were found to be 88 and 82%, respectively. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7091–7100, 2008     

On measure‐valued solutions to a two‐dimensional gravity‐driven avalanche flow model

This paper concerns measure‐valued solutions for the two‐dimensional granular avalanche flow model introduced by Savage and Hutter. The system is similar to the isentropic compressible Euler equations, except for a Coulomb–Mohr friction law in the source term. We will partially follow the study of measure‐valued solutions given by DiPerna and Majda. However, due to the multi‐valued nature of the friction law, new more sensitive measures must be introduced. The main idea is to consider the class of x‐dependent maximal monotone graphs of non‐single‐valued operators and their relation with 1‐Lipschitz, Carathéodory functions. This relation allows to introduce generalized Young measures for x‐dependent maximal monotone graph. Copyright © 2005 John Wiley & Sons, Ltd.     

有相似产品信息情形下的可靠性评定方法

两个具有局部相同组成部分的相似设备为模型,建立有相关信息情形下进行可靠性评估的指数模型,并给出了指数模型中的参数估计方法,在此基础上建立了相似设备到目标设备信息的融合算法,进而提出了一种具有相似产品信息情形下的可靠性评定方法.     

Intermodulation of transverse magnetoresistance oscillations in structures with strong intersubband interaction

In the Shubnikov–de Haas oscillation spectrum of doped InAs/AlSb structures, high-amplitude peaks are established at combination frequencies. It is demonstrated that they are caused by a significant contribution of intersubband scattering to the processes of electron-electron interaction. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 32–38, December, 2008.     

On the problematic rising ratio of cosmic-ray positrons at ultra-high energies

Summary The rising ratio of cosmic-ray positrons at ultra-high energies of interactions seems to have puzzled the theorists to a great extent. We have made here a somewhat successful attempt to interpret the behaviour of this ratio,R=e⁺/(e⁺+e⁻), by putting into use the main physical ideas from our two previous works. The importance and the implications of this observation have also been highlighted and emphasized in the proper background.

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Riassunto Il crescente rapporto dei positroni dei raggi cosmici ad energie ultra-alte di interazioni sembra aver non poco confuso i teorici. Qui si tenta con un certo successo di interpretare il comportamento di questo rapportoR=e⁺/(e⁺+e⁻) usando i principali concetti fisici dei nostri due precedenti lavori. L'importanza e le implicazioni di questa osservazione sono state sottolineate ed enfatizzate nell'appropriato contesto.

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Резюме Увеличивающиеся отношение позитронов космических лучей при ультравыс оких энергиях, по-видимому, представляет загадку для теоретиков. В этой статье мы предпринимает отчасти успешную попытку интерпретировать поведение этого отношенияR=e⁺/(e⁺+e⁻), используя основные физические идеи из наших двух предыдущих публикаций. Отмчаются важностя и приложения полученных результатов.

     

Sea wave spectra by electromagnetic techniques

Summary Sea wave measurements have been carried out in the Sicilian Channel using a navigational radar for the lower-frequency component and a teflon-coated wire (Goubau line) for the high-frequency component. The results are discussed and the continuity of the complete spectrum is clearly proved.

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Riassunto Mediante nuove tecniche elettromagnetiche è stata misurata l'ondosità del mare nel Canale di Sicilia. è stato ottenuto lo spettro completo del mare, dalla banda di gravità a quella capillare, grazie all'impiego congiunto di un radar di navigazione che fornisce la componente a bassa frequenza, e di un nuovo ondametro a microonde a filo che misura in modo assoluto la componente a bassa frequenza. Si discutono i risultati ottenuti e si dimostra la validità dei sistemi impiegati.

     

Multiscale asymptotic method of optimal control on the boundary for heat equations of composite materials

In this paper, we study the optimal control on the boundary for parabolic equations with rapidly oscillating coefficients arising from the heat transfer problems and the optimal control on the boundary of composite materials or porous media. The multiscale asymptotic expansion of the solution for the problem in the case without any constraints is presented. We derive the proofs of all convergence results.     

ILL-POSEDNESS FOR THE NONLINEAR DAVEY-STEWARTSON EQUATION

The nonlinear D-S equations on R^d, with general power nonlinearity and with both the focusing and defocusing signs, are proved to be ill-posed in the Sobolev space H^s whenever the exponent s is lower than that predicted by scaling or Galilean invariance, or when the regularity is too low to support distributional solutions. Authors analyze a class of solutions for which the zero-dispersion limit provides good approximations.     

Study of Oxidation-Reduction Properties and NO-Donor Ability of Dienediamines in the Indole, Pyrrole, and Thiophene Series

We have conducted an electrochemical study of the oxidation-reduction properties of synthesized dienediamines: derivatives of indole, pyrrole, and thiophene. We have established that reduction of the indicated compounds occurs with successive transfer of two electrons, the first transfer being reversible. We consider the effect of structural factors and the nature of the heterocycle on the ease of reduction of the given compounds. We present the results of an initial study of the NO-donor ability of the compounds upon oxidation.     

Observations of coastal upwelling off northwest Africa using meteosat data

Summary One month of Meteosat IR data has been used to study the upwelling phenomenon along the northwest coasts of Africa. The analysis has shown the presence of a cold water strip along the coastline (1500 km long and (100÷200) km wide) characterized by a sea surface temperature of almost 3°C lower than the surroundings. The synoptic view offered by Meteosat evidentiated the simultaneous presence of two zones of the upwelling regime characterized by a different behaviour: the C. Bojador zone where the oscillations of the cross-shore thermal gradient measured by satellite follow quite well the daily variation of the large-scale meteorological forcings and the C. Ghir zone where the phenomenon is not always present and is more related to local forcings and coastal geometry. The general features resulting from our study are in agreement with the results of in situ previous measurements.

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Riassunto Il fenomeno dell'upwelling lungo le coste del nord-ovest dell'Africa è stato studiato utilizzando un mese di dati del statellite Meteosat relativi al canale dell'infrarosso. L'analisi di questi dati ha mostrato la persistenza di una striscia di acqua fredda lungo costa (lunga circa 1500 km e larga (100÷200) km) caratterizzata da una temperatura superficiale di almeno 3 °C piú bassa rispetto alle acque circostanti. La visione sinottica di tutta la zona del nord-ovest dell'Africa fornita dal Meteosat ha permesso di evidenziare due zone di upwelling caratterizzate da un regime differente: la zona di Capo Bojador, dove le variazioni del gradiente termico perpendicolare alla costa misurato da satellite seguono le oscillazioni dei forzanti meteorologici a grande scala, e la zona intorno a Capo Ghir, dove il fenomeno dell'upwelling non è sempre presente e dove i forzanti locali e la geometria della costa sembrano avere un ruolo predominante. Le strutture oceanografiche evidenziate dall'analisi delle immagini da satellite e la loro evoluzione temporale sono risultate consistenti con le precedenti osservazioni basate su tecniche convenzionali.

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Резюме Инфракрасные данные с метеоспутника в течение одного месяса используются для исследования явления ?апвелинга? вдоль северного побережья Африки. Проведенный анализ показывает наличие узкой полосы холодной воды вдоль береговой линии (1500 км в длину и (100÷250) км в ширину), которая характеризуется поверхностной температурой ночти на 3 °C ниже, чем температура окружающих слоёв. Данные с метеоспутника указывают на одновременное присутствие двух различных зон, которые имеют различное поведение в режиме ?апвелинга?. Общие особенности, полученные из проведённых исследований, хорошо согласуются с результатами предыдущих измерений на месте.