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  • 1
    Electronic Resource
    Electronic Resource
    The role of ionic hydration in the conformations of DNA in electrolytic solutions (1989)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 11 (1989), S. 1481-1487 
    Details
    ISSN: 0392-6737
    Keywords: Molecular biophysics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Sono stati analizzati spettri in dicroismo circolare (CD) di DNA di calf thymus in soluzioni acquose di LiCl, NaCl, KCl e CsCl a 25°C nell’intervallo spettrale (215÷300) nm. È stata messa in evidenza una correlazione tra le variazioni osservate negli spettri CD, al variare della concentrazione di sale, e la concentrazione d’acqua libera presente in soluzione (vedi lavoro precedente). È stato mostrato che effetti specifici, presenti nel processo studiato, trovano corrispondenza in semplici proprietà di idratazione degli ioni considerati.
    Abstract: Резюме Исследуются спектры кругового дихроизма ДчК тимуса теленка в водных раствоах LiCl, NaCl, KCl и CsCl при 25°C в спектральном интервале (215÷300) нм. Обнаружена корреляция между наблюденными изменениями спектров кругового дихроизма и измененениями концентрации электролита и концентрации свободной воды, присутствующей в растворе (см. предыдщую статью). Показывается, что специфические катионные эффекты, обнауженные в этом продессе, обьясњяются простыми свойствами гидратадии рассматриваемых катионов.
    Notes: Summary The circular dichroism (CD) spectra of calf thymus deoxyribonucleic acid have been examined at 25°C over the wavelength range (215÷300) nm in aqueus solutions of LiCl, NaCl, KCl, and CsCl. The CD changes observed as the electrolyte concentration is varied have been correlated quantitatively with the magnitude of the hydration of the ions in these solutions (see a preceding paper). It is shown that specific cation effects present in this process correspond consistently to simple hydration properties of these same cations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450507
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  • 2
    Electronic Resource
    Electronic Resource
    The hydration of caesium chloride in aqueous solutions (1989)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 11 (1989), S. 533-545 
    Details
    ISSN: 0392-6737
    Keywords: Studies of specific liquid structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto È state misurata la compressibilità adiabatica di soluzioni acquose di cloruro di cesio in funzione della temperatura e della concentrazione di sale nell’intervallo (14÷40)% in peso. I dati di compressibilità, insieme a quelli di densità delle stesse soluzioni, sono stati interpretati facendo uso di un semplice modello che tien conto delle sfere di idratazione degli ioni. Sulla base dell’analisi effettuata è stato possibile valutare la contrazione di volume dovuto all’interazione ione-acqua, il volume intrinseco degli ioni, i numeri di idratazione, la compressibilità e densità dell’acqua nelle sfere di idratazione e la dipendenza di queste quantità dalla temperatura e concentrazione di sale.
    Abstract: Резюме Определяется температурная зависимость адиабатической сжимаемости растворов хлорида цезия в воде для различных концентраций в интервале (14÷40) весовых процетов. данные, полученные для сжимаемости, вместе с данными дия плотности описываются в рамках простой модели в терминах водяных координационных оболочек, без использования информации о физических свойствах сферы гидратации. На основе проведенного анализа можно оценить величину объемного сжатия, обусловленного взвимодействиями ионов и воды, собственный объем ионов, числа гидратации, сжимаемость и плотность воды в сфере гидратации и их изменения с температурой и концентрацией соли.
    Notes: Summary The temperature dependence of the adiabatic compressibility of solutions of caesium chloride in water has been determined for different solute concentrations from 14 to 40 wt.%. The compressibility data thus obtained, together with density data, are described in terms of water coordination shells by using a simple model, without the need for further information on the physical properties of the hydration sphere. On the basis of the analysis performed it has been possible to estimate the values of the volume contraction caused by ion-water interactions, the intrinsic volume of ions, the hydration numbers, the compressibility and density of water in hydration shells and their variation with temperature and salt concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457510
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  • 3
    Electronic Resource
    Electronic Resource
    Secondary structure of T2 intraphage DNA: a spectrophotometric study (1983)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1480-1488 
    Details
    ISSN: 0392-6737
    Keywords: General, theoretical and mathematical biophysics (including logic of biosystems, quantum biology and relevant aspects of thermodynamics, information theory, cybernetics and bionics)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto In questo lavoro si mettono in evidenza significative differenze nelle proprietà spettrali del DNA di T2 intrafagico e libero in soluzione nell'intervallo (230÷320) nm. Queste differenze sono molto simili a quelle ottenute in una soluzione di DNA nativo abbassando ilpH a partire dal valore neutro. Su questa base si avanza l'ipotesi di una protonazione della citosina nel DNA intrafagico.
    Abstract: Резюме В этой работе рассматриваются различия в спектральных свойствах (в области (230÷320) нм) между внутрифаговыми и свободными T2 ДНК. Эти различия очень сходны с изменениями в поглощении, полученными для естественного раствора ДНК, когдаpH уменьшается по сравнению с нейтральной величиной. На основе этого подхода выдвигается гипотеза протонации цитозина во внутрифаговой ДНК.
    Notes: Summary Relevant differences in the spectral properties (in the (230÷320) nm range) between intraphage and free T2 DNA are reported in this work. These differences are very similar to the variation in absorption obtained for a native DNA solution when thepH is lowered starting from the neutral value. On this basis, cytosine protonation in intraphage DNA is hypothesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460226
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  • 4
    Electronic Resource
    Electronic Resource
    UV damage of T2-phage particles and conformation of DNAin situ (1983)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1489-1496 
    Details
    ISSN: 0392-6737
    Keywords: General, theoretical and mathematical biophysics (including logic of biosystems, quantum biology and relevant aspects of thermodynamics, information theory, cybernetics and bionics)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si studia l'effetto dell'irraggiamento UV sul DNA del fago T2 in situ e libero in soluzione mediante un'analisi delle modificazioni dei profili di fusione e degli spettri d'assorbimento. L'analogo comportamento fotochimico osservato nei due sistemi sembra escludere significative differenze nella loro struttura secondaria.
    Abstract: Резюме Исследуется влияние ультрафиолетового облучения на ДНК фага T2 на месте и на свободные молекулы ДНК в растворе, посредством анализа изменений профилей плавления и изменений спектров поглощения. Аналогичное фотохимическое ооведение, полученное в этих двух системах, по-видимому, исключает значительные различия между их вторичными структурами.
    Notes: Summary The effect of UV irradiation onin situ and free T2 DNA is studied by analysing the melting profiles and absorption spectra modifications. The similar photochemical behaviour obtained in the two systems seems to exclude significant differences in their secondary structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460227
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  • 5
    Electronic Resource
    Electronic Resource
    Metal ion interaction with ribosomal RNA (1986)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 7 (1986), S. 265-272 
    Details
    ISSN: 0392-6737
    Keywords: Molecular biophysics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si è fatto uso di una tecnica di spettroscopia differenziale nell’UV allo scopo di evidenziare le piccole variazioni nello spettro di assorbinemto di molecole di RNA ribosomiale dovute all’interazione con gli ioni Na+, K+, Mg2+, Ca2+ e Ni2+. I dati mostrano che tutti gli ioni esaminati interagiscono con i, gruppi fosfato provocando variazioni conformazionali nelle molecole di rRNA con la formazione di una struttura piú compatta caratterizzata da un aumento complessivo nelle interazioni di «stacking», tra le basi. Oltre a questo legame di tipo ionico con i gruppi fosfato i nostri dati indicano per i metalli di transizione Mn2+, Co2+ e Ni2+ un’interazione diretta con le singole basi.
    Abstract: Резюме Мы используем UV дифференциальную спектроскопню, чтобы зарегистрировать небольшие изменения в спектре поглошения молекул рибосомных RNA, обусловленные взаимодействием с металлическими ионами Na+, K+, Mg2+, Ca2+, Mn2+, Co2+ и Ni2+. Полученные данные показывают, что исследованные ионы связываются с фосфатной группой, что приводит к конформационным изменениям в молекуле рибосомной RNA с образованием более компактной структуры, характеризуюшейся увеличением взаимодействия «укладок» между основаниями. Кроме этой связи ионного типа фосфатными группами, ионы переходных металлов Mn2+, CO2+ и Ni2+ могут непосредственно взаимодействоватъ с основаниями.
    Notes: Summary We have used UV differential spectroscopy in order to detect small modifications in the ribosomal RNA absorption spectrum due to the binding of rRNA molecules with the metal ions Na+, K+, Mg2+, Ca2+, Mn2+, Co2+ and Ni2+. Our data show that all the ions, investigated are involved in ion-type bond with the phosphate groups of rRNA and cause a refolding of the molecules with an overall increase in basebase «stacking» interactions. Besides this ion-type binding with phosphate groups, transition metal ions Mn2+, Co2+, and Ni2+ are also able to bond directly to the bases
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02451247
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  • 6
    Electronic Resource
    Electronic Resource
    Isentropic compressibility behaviour of dilute solutions of ethyl-alcohol in water (1986)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 8 (1986), S. 465-480 
    Details
    ISSN: 0392-6737
    Keywords: Acoustical properties of liquids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto È stata misurata la compressibilità adiabatica,β s, di miscele acqua-alcool etilico in funzione della temperatura e della concentrazione di alcool. Le misure sono state effettuate ogni 5°C, nell'intervallo di temperatura (10⋎40) °C e sono particolarmente dettagliate a bassa concentrazione di alcool (frazione molare di alcoolx 2〈0.25), L'osservata dipendenza diβ s dax 2 nella zona 0〈x 2〈0.25 indica l'esistenza nella miscela di microstrutture locali simili a quelle che caratterizzano un clatrato idrato di tipo II di composizione C2H2OH-17H2O. I risultati ottenuti sono spiegati facendo uso di un semplice modello in cui si considerano le interazioni soluto-solvente e le associazioni tra le molecole di soluto.
    Notes: Summary The adiabatic compressibility of ethanol-water mixtures was measured as a function of temperature and cosolvent concentration; the measurements were carried out at 5°C intervals over the range (10⋎40) °C, paying particular attention to the water-rich region (mole fraction of cosolventx 2〈0.25). The observed concentration dependencies of the adiabatic compressibility in the low-concentration range were well explained if we consider the existence in the mixture of local structures with a composition that is close to ethanol-17 H2O like that of solid clathrate hydrate of type II. A simple model, involving the solutesolvent interactions and the molecular aggregation of the solute, is used to explain the observed behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450610
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  • 7
    Electronic Resource
    Electronic Resource
    Self-association behaviour of alcohols in diluted aqueous solutions (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 1499-1514 
    Details
    ISSN: 0392-6737
    Keywords: Studies of specific liquid structures ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Our recent studies related to the properties of alcohol/water mixtures show the occurrence of some kind of molecular aggregation in the water-rich region of composition beyond a threshold alcohol concentrationx 2 *. The observed behaviour suggests that forx 2〈x 2 * the alcohol molecules are essentially dispersed and surrounded by «water cages» where the short-range order and microdynamic of water molecules are changed with respect to those of pure water. Alcohol molecules are in mutual contact at higher concentration only when almost all water is involved in hydration shells of alcohol molecules. The structural transition atx 2 * resembles, for some aspect, the micellization process. The main results of these investigations are reviewed and discussed in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02462035
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  • 8
    Electronic Resource
    Electronic Resource
    Structure of water-in-oil microemulsions of AOT by infrared spectroscopy (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 1601-1611 
    Details
    ISSN: 0392-6737
    Keywords: Electron correlation calculations for atoms and molecules ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The structure of water in water/AOT/n-heptane reverse micelles has been studied as a function of the [H2O]/[AOT] ratio (W) by using the absorption IR due to O−H stretching modes in the 3800–3000 cm−1 range. The results show that the IR spectra can be expressed as a sum of contributions from bound- and bulk-like water. The fraction of water in the two «regions» within the water pool was evaluated as a function ofW. The «bound» water region seems to hold 3.5 water molecules (corresponding to 7 O−H oscillators) per AOT molecule and its formation is nearly complete atW〉6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02462048
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  • 9
    Electronic Resource
    Electronic Resource
    Infrared absorption and water structure in aerosol OT reverse micelles (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1053-1065 
    Details
    ISSN: 0392-6737
    Keywords: Disperse systems ; PACS 78.30 ; Infrared and Raman spectra and scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The structure of water in bis(2-ethylhexyl)sodium sulfosuccinate (AOT) micelles has been studied as a function of the [H2O]/[AOT] ratio (W) by using the absorption IR due to O−H stretching modes in the 3800–3000 cm−1 range. Three systems have been studied: water/AOT/carbon tetrachloride, water/AOT/n-heptane and water/AOT iso-octane. Experimental spectra are presented and discussed for the O−H stretching region both of H2O and isotopically diluted HDO molecules in D2O. We have restricted ourselves to the region of small amounts of water (0〈W〈20) where the properties of the systems change strongly with the water content. The results show that IR spectra can be expressed as sum of contributions from interfacial and bulk-like water. The fraction of water in the two “regions” within the water pool was evaluated as a function ofW. From the data a continuous variation appears in the water properties inside micellar cores rather than a two-steps hydration mechanism. The solubilization of water is described in terms of hydration of the AOT head group and Na+ counterions. The maximum hydration number of AOT was found to be 3.5. The same behaviour has been observed in the three solvents studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456791
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  • 10
    Electronic Resource
    Electronic Resource
    Microwave study of intermediate- to mixed-state behaviour changes in tin superconducting films (1983)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1497-1508 
    Details
    ISSN: 0392-6737
    Keywords: General properties of superconductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto In questo lavoro si studia, con una tecnica differenziale a microonde, la transizione superconduttiva di film di stagno in campo magnetico perpendicolare. Le misure sono state effettuate in funzione dello spessore (65 nm÷200 μm) e della temperatura (1.5 K÷T c). È stato osservato il passaggio fra lo stato intermedio e lo stato misto e sono stati determinati i valori dello spessore critico,d ⊥, a cui avviene tale passaggio; i valori ottenuti sono in accordo con le previsioni teoriche. Inoltre l'andamento del campo magnetico critico perpendicolare,H ⊥, in funzione dello spessore è in buon accordo con le previsioni teoriche perd〈d ⊥ e nel limited≪d ⊥.
    Abstract: Резюме С помощью измерений микроволнового поглощения исследуются переходы, связанные с перпендикулярным магнитным полем, для пленок чистого олова, как функция толщины образцов (65 нм÷200 мкм) и температуры (1.5 K÷T c). Наблядается переход от промежуточного к смешанному состоянию. Значения, полученные для критической толщиныd ⊥, при которой имеет место переход от поведения типа I к поведению типа II, согласуется с теоретическими предсказаниями. Критические значения перпендикулярного магнитного поляH ⊥ также согласуются с теоретическими предсказаниями дляd〈d ⊥ и в пределеd≫d ⊥.
    Notes: Summary Perpendicular magnetic-field transitions of pure Sn films, assessed by microwave absorption measurement as a function of specimen thickness (65 nm÷200 μm) and temperature (1.5 K÷T c), are presented. The passage from intermediate- to mixed-state behaviour was observed. The values obtained for the critical thicknessd ⊥ at which the passage from type-I to type-II behaviour occurs agree with theoretical predictions. Critical perpendicular magnetic-field values,H ⊥, also agree well with theoretical predictions ford〈d ⊥ and in the limitd≫d ⊥.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02460228
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