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Isotopic effects in the fragmentation of excited target residues following collisions of 12C on (112,124)Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4pi detector. The measured yield ratios for light particles and fragments with atomic number Z < or = 5 obey the exponential law of isotopic scaling. The deduced scaling parameters decrease strongly with increasing centrality to values smaller than 50% of those obtained for the peripheral event groups. Symmetry-term coefficients, deduced from these data within the statistical description of isotopic scaling, are near gamma = 25 MeV for peripheral and gamma < 15 MeV for central collisions.

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Sedum telephium L. is a medicinal plant used in antiquity to cure many types of inflammatory skin diseases. The leaves (without the external cuticle), are used to promote healing and reduce skin inflammation and pain, and contain various components. We found two major components: flavonol glycosides and polysaccharides, with molecular weight between 13,000 and 13,500 Da. We evaluated the in-vitro antioxidant and in-vivo skin photoprotective effects of three lyophilized extracts obtained from the juice of S. telephium L. leaves: a total lyophilized juice, a lyophilized flavonolic fraction, and a lyophilized polysaccharidic fraction. Two in-vitro models were used: the bleaching of the stable 2,2-diphenyl-1-picrylhydrazyl (DPPH*) radical, and the protective effect against UV-induced peroxidation on phosphatidylcholine multilamellar vesicles, as model membranes. The antioxidant/radical scavenging activity of each lyophilized extract was also assessed in-vivo by determining their ability to reduce UVB-induced skin erythema (monitored by reflectance spectrophotometry) in healthy human volunteers. The findings of the in-vitro experiments clearly demonstrated that, unlike the lyophilized polysaccharidic fraction, the lyophilized flavonolic fraction and total lyophilized juice possess strong antioxidant/free radical scavenging properties, which are likely due to phenolic compounds. Consistent with these findings, gel formulations of both the total lyophilized juice and, to a greater degree, the lyophilized flavonolic fraction appeared to possess a strong protective effect against UV-induced skin erythema in-vivo, whereas the lyophilized polysaccharidic fraction was completely ineffective. The in-vitro and in-vivo results suggest that, both the total lyophilized juice and, in particular, the lyophilized flavonolic fraction, but not the lyophilized polysaccharidic fraction of S. telephium L. leaves, have photoprotective effects against UVB-induced skin damage.

Breakup temperatures were deduced from double ratios of isotope yields for target spectators produced in the reaction 197 The good agreement with the breakup temperatures measured previously for projectile spectators at an incident energy of 600 MeV per nucleon confirms the universality established for the spectator decay at relativistic bombarding energies. The measured temperatures also agree with the breakup temperatures predicted by the statistical multifragmentation model. For these calculations a relation between the initial excitation energy and mass was derived which gives good simultaneous agreement for the fragment charge correlations.The energy spectra of light charged particles, measured at θ lab = 150• , exhibit Maxwellian shapes with inverse slope parameters much higher than the breakup temperatures. The statistical multifragmentation model, because Coulomb repulsion and sequential decay processes are included, yields light-particle spectra with inverse slope parameters higher than the breakup temperatures but considerably below the measured values. The systematic behavior of the differences suggests that they are caused by light-charged-particle emission prior to the final breakup stage. Keywords:197 Au projectiles and targets, E/A = 600 and 1000 MeV; measured fragment cross sections, isotopic yield ratios; deduced breakup temperatures, pre-breakup emission; analysis using quantum statistical and statistical multifragmentation models.

Breakup temperatures in central collisions of 197 Au 1 197 Au at bombarding energies E͞A 50 to 200 MeV were determined with two methods. Isotope temperatures, deduced from double ratios of hydrogen, helium, and lithium isotopic yields, increase monotonically with bombarding energy from 5 to 12 MeV, in qualitative agreement with a scenario of chemical freeze-out after adiabatic expansion. Excited-state temperatures, derived from yield ratios of states in 4 He, 5,6 Li, and 8 Be, are about 5 MeV, independent of the projectile energy, and seem to reflect the internal temperature of fragments at their final separation from the system. [ S0031-9007(98) . The temperatures were derived from double ratios of helium and lithium isotopic yields while the excitation energies were obtained by adding up the kinetic energies of the product nuclei and the mass excess of the observed partition with respect to the ground state of the reconstructed spectator nucleus. The double-bended shape of the caloric curve and its similarity to predictions of microscopic statistical models [2][3][4], has stimulated considerable experimental and theoretical activities. In particular, the second rise of the temperature to values exceeding 10 MeV at high excitation energies has initiated the discussion of whether nuclear temperatures of this magnitude can be measured reliably (see , and references given in these recent papers) and whether this observation may indeed be linked to a transition towards the vapor phase [7,8]. Obviously, a well-founded understanding of the significance of the employed temperature observables [9] is indispensable when searching for signals of the predicted liquid-gas phase transition in nuclear matter.Here, we present the results of temperature measurements for central collisions of 197 Au 1 197 Au at incident energies E͞A 50 to 200 MeV. These collisions are characterized by a collective radial flow of light particles and fragments which, over the covered energy range, evolves as a dynamical phenomenon closely connected to the initial stages of the reaction [10]. Global equilibrium is clearly not achieved. If local equilibrium is reached, the associated temperatures should reflect the adiabatic cooling of the rapidly expanding system. Two temperature observables were used simultaneously. Isotope temperatures were deduced from double ratios of isotopic yields [11] and excited-state temperatures were derived from the correlated yields of lightparticle coincidences [9,12,13]. It will become evident from the diverging results that this represents more than a methodical test and that the two types of thermometers are sensitive to different stages of the fragment formation and emission.Beams of 197 Au with E͞A 50, 100, 150, and 200 MeV, provided by the heavy-ion synchrotron SIS, were directed onto targets of 75 mg͞cm 2 areal density. Two multidetector hodoscopes, consisting of 96 and of 64 Si-CsI(Tl) telescopes in closely packed geometries, were placed on opposite sides with respect to the beam axis. Four high-resolution te...

The biological properties and, particularly, the antioxidant activity of plant hydroxycinnamic acids, such as caffeic and ferulic acids, are well recognised. This preliminary study was designed to estimate the potential utility of caffeic and ferulic acids to prevent, when topically applied, photooxidative stress in the skin. With this aim we have evaluated the antioxidant activity of ferulic and caffeic acids in two experimental models: (1) the UV radiation‐induced peroxidation in phosphatidylcholine (PC) liposomal membranes; (2) the scavenging activity against nitric oxide (a radical involved in oxidative reactions). In addition, given that a suitable percutaneous absorption is an essential requirement for successful topical photoprotective agents, we measured their in vitro permeation through excised human skin. Caffeic and ferulic acids efficiently protected PC liposomes from UV radiation‐induced peroxidation and reacted with nitrogen oxides. In addition, caffeic and ferulic acids were able to permeate through the stratum corneum (the main barrier against the penetration of exogenous substances through the skin). Taken together, these findings suggest that caffeic and ferulic acids should be good canditates for successful employment as topical protective agents against UV radiation‐induced skin damage. © 1999 Society of Chemical Industry