Effects of ionizing radiation on bio-active plant extracts useful for preventing oxidative damages

Humans are exposed to ionizing radiations in medical radiodiagnosis and radiotherapy that cause oxidative damages and degenerative diseases. Airplane pilots, and even more astronauts, are exposed to a variety of potentially harmful factors, including cosmic radiations. Among the phytochemicals, phenols are particularly efficient in countering the oxidative stress. In the present study, different extracts obtained from plant food, plant by-products and dietary supplements, have been compared for their antioxidant properties before and after irradiation of 140 cGy, a dose absorbed during a hypothetical stay of three years in the space. All the dry extracts, characterized in terms of vitamin C and phenolic content, remained chemically unaltered and maintained their antioxidant capability after irradiation. Our results suggest the potential use of these extracts as nutraceuticals to protect humans from oxidative damages, even when these extracts must be stored in an environment exposed to cosmic radiations as in a space station.     

Template effect of tetrathiafulvalene in the formation of cyclobis(paraquat-p-phenylene)

[reaction: see text] The template effect exerted by tetrathiafulvalene (TTF) in the ring-closure reaction of the trication 5(3+) yielding cyclobis(paraquat-p-phenylene) has been quantitatively evaluated in acetonitrile at 62 degrees C with UV-vis spectrophotometry. The rate of ring closure of the trication 5(3+) largely increases in the presence of the template (a maximum increase of ca. 80 times at [TTF] approximately 0.14 M). The results are compared with those of other aromatic templates, 2 and 3, that were provided with polyethereal sidearms and indicate that the template ability of tetrathiafulvalene is comparable or better than that of the others.     

Two-point self-coordination of a dizinc(II) bispyridylporphyrin ruthenium complex leading selectively to a discrete molecular assembly: solution and solid-state characterization

The dizinc(II) bispyridylporphyrin ruthenium complex trans,cis,cis[RuCl2(CO)2(Zn.4'-cisDPyP)2] (1Zn, 4'-cisDPyP = 5,10-bis(4'-pyridyl)-15,20-diphenylporphyrin) features two donor (the uncoordinated 4'-N(py) atoms) and two acceptor (the Zn atoms) sites and is thus a building block suited for two-point coordination. 1H NMR spectroscopy indicates that 1Zn self-assembles in solution through Zn-4'-N(py) interactions to yield selectively a highly symmetrical discrete species, in which all donor and all acceptor sites of 1Zn are mutually saturated. Single-crystal X-ray analysis established that this adduct is a dimeric species, (1Zn)2, with a global S4 symmetry, in which the four porphyrins have a propeller-like arrangement. The dimeric species (1Zn)2 is a meso form derived from the combination of two 1Zn units with opposite helical chirality. The geometry of this highly symmetrical tetraporphyrin assembly in solution, as determined by NMR spectroscopy, is essentially the same as that found in the solid state. Thus 1Zn is an unprecedented example of metal-containing self-complementary building block that selectively recognizes itself through four Zn-N(py) interactions, and thus yields a very stable and symmetrical dimeric species, (1Zn)2, that features four porphyrins and six metal atoms (two Ru and four Zn).     

How to derive priorities in AHP: a comparative study

A heated discussion has arisen over the “best” priorities derivation method. Using a Monte Carlo simulation this article compares and evaluates the solutions of four AHP ratio scaling methods: the right eigenvalue method, the left eigenvalue method, the geometric mean and the mean of normalized values. Matrices with different dimensions and degree of impurities are randomly constructed. We observe a high level of agreement between the different scaling techniques. The number of ranking contradictions increases with the dimension of the matrix and the inconsistencies. However, these contradictions affect only close priorities.     

The lateral distribution of energetic shower muons

Summary The customary assumption of a unique structure function of the formf(r)∞r ^−αexp[−r/R ₀] with parameters independent of the shower size and the nature of the primary is tested against evidence on the multiplicity distribution of shower muons. The experimental data were obtained with an array of three spark chamber telescopes installed at the Mt. Cappuccini underground station, Torino, at depths of about 40 to 60 hg/cm². They pertain to events with mean shower sizes between about 10⁵ and a few 10⁷ electrons. It is shown that the results are incompatible with this assumption, whatever values are assigned to the exponent α and to the characteristic radiusR ₀ of the structure function. A modified representation allowing for a variation ofR ₀ with the shower size and with the massA of the primary is suggested. The resulting distribution is in reasonable agreement both with thorough Monte Carlo evaluations for proton and iron primaries and with direct experimental observations of other authors.

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Riassunto L'ipotesi usuale di una funzione di struttura unica della formaf(r)∞r ^−αexp[−r/R ₀] con parametri indipendenti dalle dimensioni dello sciame e dalla natura dei primari è provata rispetto alle prove sperimentali sulla distribuzione di molteplicità dei muoni dello sciame. I dati sperimentali sono stati ottenuti con un sistema di tre telescopi con camere a scintille istallati nella stazione sotterranea del Monte dei Capuccini, Torino, a profondità da 40 a 60 hg/cm². Essi riguardano eventi con grandezze medie di sciami tra circa 10⁵ e pochi 10⁷ elettroni. Si mostra che i risultati non sono compatibili con questa ipotesi, qualsiasi valore sia assegnato all'esponente α e al raggio caratteristicoR ₀ della funzione di struttura. Si suggerisce una rappresentazione modificata che consente una variazione diR ₀ con la grandezza dello sciame e con la massaA dei primari. La distribuzione risultante è in ragionevole accordo sia con tutte le valutazioni di Montecarlo per primari di protoni e di ferro e con osservazioni sperimentali dirette di altri autori.

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Резюме Исследуется обычное предположение о единственной структурной функции видаf(r)∼r ^−αexp[−r/R ₀], с параметрами, не зависяцими от размеров ливня и природы первичной частицы, на основе данных о распределении множественности мюонов в ливне. Зкспериментальные данные получены с помошью системы трех телескпов искровых камеп, установленных на подземной стандии Капучини в Турине, на глубинах от 40 до 60 гг/см². Полученные данные относятся к событиям со средними размерами ливня от 10⁵ до 10⁷ злектронов. Показывается, что полученные результаты являются несовместимыми с зтим предположением, какие бы значения зкспоненте α и характерному радиусуR ₀ структурной функции не были бы приписаны. Предлагается модифицированное представление, учитывающее изменение велиьиныR ₀ с размером ливия и с массойA первичной частицы. Полученное распределение хорошо согласуется и с оценками по Монте-Карло для первичных протонов и ядер железа и с непосредственными экспериментальными результатами других авторов.

     

An intermolecular force field for chlorinated benzene crystals

Intermolecular potential parameters corresponding to atom—atom interactions of the Buckingham form are refined on the basis of static and dynamic properties of some chlorinated benzene crystals. The model reproduces well the observed properties, including k ≠ 0 vibrations.     

Killing Symmetries of Generalized Minkowski Spaces, 3: Spacetime Translations in Four Dimensions

In this paper, we continue the study of the Killing symmetries of a N-dimensional generalized Minkowski space, i.e., a space endowed with a (in general non-diagonal) metric tensor, whose coefficients do depend on a set of non-metrical coordinates. We discuss here the translations in such spaces, by confining ourselves (without loss of generality) to the four-dimensional case. In particular, the results obtained are specialized to the case of a deformed Minkowski space (i.e. a pseudoeuclidean space with metric coefficients depending on energy).     

Laboratory simulation of coriolis effects on atmospheric dispersion of airborne tracers over a complex terrain

Summary The experimental research described here deals with a problem of diffusion and transport on local scale (30 km) of pollutants of urban and industrial origin, emitted into the atmosphere of a complex terrain site, with noticeable orographical features. The diffusion process was visualized and analysed in detail. The results of this research allowed acquiring the capability of forecasting environmental impact on the area, due to the sources considered. On account of its spatial scale, the phenomenon was investigated in a rotating hydraulic channel, by the method of simulation on physical model at reduced scale. Typical local atmospheric conditions, taking into account diurnal evolution of stability inside a turbulent, rotating planetary boundary layer, were modeled. Seasonal variations of sources emission rates were considered. Measurements of dilution factors at several spatial points of the model and at five levels (from ground up to a height equivalent to about 1000m) allowed mapping out concentration isolines over the site in various conditions and producing evolving contour plots which visualized the diffusion processes in a very useful way for planning purposes.     

Coupled nonlinear Schrödinger systems with potentials

Coupled nonlinear Schrödinger systems describe some physical phenomena such as the propagation in birefringent optical fibers, Kerr-like photorefractive media in optics and Bose-Einstein condensates. In this paper, we study the existence of concentrating solutions of a singularly perturbed coupled nonlinear Schrödinger system, in presence of potentials. We show how the location of the concentration points depends strictly on the potentials.     

The effect of nonlinearities on the power spectrum of cosmic-ray fluctuations observed underground

Summary Theoretical power spectra for the fluctuations of high-rigidity cosmic rays (R≳100 GV) as detected in underground muon stations are obtained. The high-rigidity limit of diffusion theory is used and nonlinear interactions between particles and interplanetary magnetic fields are considered according to nonlinear-closure approximation theory.

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Riassunto Si presentano i risultati sullo spettro di potenza atteso per fluttuazioni di raggi cosmici primari (rigidità >100 GV) rivelati in stazioni sottoterra. Si fa uso della teoria di diffusione nel limite di alta rigidità, e si considerano le interazioni non lineari fra particelle e campi magnetici interplanetari tramite la teoria di ?nonlinear-closure approximation?.

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Резюме Получены теоретические степенные спектры для флуктуаций косми-ческих лучей с высокой жесткостью (R≳100 GV), которые регистрируются на подземных мюонных станциях. Используется предел высокой жесткости для диф-фузионной теории. В рамках приближения ?незамкнутости? рассматриваются нелинейные взаимодействия между частицами и межпланетными магнитными полями.