Scaling in the Lattice Gas Model

A good quality scaling of the cluster size distributions is obtained for the Lattice Gas Model using the Fisher's ansatz for the scaling function. This scaling identifies a pseudo-critical line in the phase diagram of the model that spans the whole (subcritical to supercritical) density range. The independent cluster hypothesis of the Fisher approach is shown to describe correctly the thermodynamics of the lattice only far away from the critical point.Comment: 4 pages, 3 figure

Isotopic composition of fragments in multifragmentation of very large nuclear systems: effects of the chemical equilibrium

Studies on the isospin of fragments resulting from the disassembly of highly excited large thermal-like nuclear emitting sources, formed in the ^{197}Au + ^{197}Au reaction at 35 MeV/nucleon beam energy, are presented. Two different decay systems (the quasiprojectile formed in midperipheral reactions and the unique source coming from the incomplete fusion of projectile and target in the most central collisions) were considered; these emitting sources have the same initial N/Z ratio and excitation energy (E^* ~= 5--6 MeV/nucleon), but different size. Their charge yields and isotopic content of the fragments show different distributions. It is observed that the neutron content of intermediate mass fragments increases with the size of the source. These evidences are consistent with chemical equilibrium reached in the systems. This fact is confirmed by the analysis with the statistical multifragmentation model.Comment: 9 pages, 4 ps figure

Implementation of the reverse screening syphilis algorithm in a clinical laboratory

Background: Syphilis remains a public health concern worldwide, the accuracy of diagnostic tests is critical for its successful control. Currently, there are two approaches to the diagnosis of syphilis using serological tests: the traditional algorithm and the reverse algorithm. Aim: The goal of this study was to analyse the advantages and disadvantages in the implementation of the syphilis reverse-screening algorithm in an outpatient clinical laboratory. Methods: An observational cross-sectional study was carried out analyzing 246 reactive sera from a total of 14700 requests for syphilis serology. Chemiluminescent assay ARCHITECT Syphilis TP, V.D.R.L. and FTA-Abs were performed. Results: Among 246 reactive sera by ARCHITECT Syphilis TP, 129 were reactive and 117 were non-reactive by V.D.R.L. the last mentioned resulted in 97 reactive and 20 non-reactive by FTA-Abs, suggesting false positives (0.13%).Two patients with primary infection were detected, that were not detected by V.D.R.L. and one pregnant woman with primary infection with a high value S/CO and V.D.R.L.:1 dils. Conclusions: Among the advantages of using a reverse algorithm were greater sensitivity in the detection of patients with primary syphilis; automation, complete traceability of the samples; objective interpretation and conclusive results.Facultad de Ciencias Exacta

Searching for the Nuclear Liquid-Gas Phase Transition in Au + Au Collisions at 35 MeV/nucleon

Within the framework of Classical Molecular Dynamics, we study the collision Au + Au at an incident energy of 35 MeV/nucleon. It is found that the system shows a critical behaviour at peripheral impact parameters, revealed through the analysis of conditional moments of charge distributions, Campi Scatter Plot, and the occurrence of large fluctuations in the region of the Campi plot where this critical behaviour is expected. When applying the experimental filters of the MULTICS-MINIBALL apparatus, it is found that criticality signals can be hidden due to the inefficiency of the experimental apparatus. The signals are then recovered by identifying semi-peripheral and peripheral collisions looking to the velocity distribution of the largest fragment, then by selecting the most complete events.Comment: RevTex file, 21 pages + 19 figures available upon request from [email protected]

Helium burning and neutron sources in the stars

Helium burning represents an important stage of stellar evolution as it contributes to the synthesis of key elements such as carbon, through the triple-alfa process, and oxygen, through the 12C(alfa, gamma)16O reaction. It is the ratio of carbon to oxygen at the end of the helium burning stage that governs the following phases of stellar evolution leading to different scenarios depending on the initial stellar mass. In addition, helium burning in Asymptotic Giant Branch stars, provides the two main sources of neutrons, namely the 13C(alfa, n)16O and the 22Ne(alfa, n)25Mg, for the synthesis of about half of all elements heavier than iron through the s-process. Given the importance of these reactions, much experimental work has been devoted to the study of their reaction rates over the last few decades. However, large uncertainties still remain at the energies of astrophysical interest which greatly limit the accuracy of stellar models predictions. Here, we review the current status on the latest experimental efforts and show how measurements of these important reaction cross sections can be significantly improved at next-generation deep underground laboratories

Almonds By-Product Microcrystalline Cellulose as Stucco for Wooden Artifacts

Over the years in the field of conservation of cultural heritage, a wide use of traditional products for the plastic reintegration of wooden artifacts has been seen. However, they are usually not designed for this purpose. The present study also shows, in terms of material compatibility, the material most suited for wood restoration, cellulose pulp, from the perspective of a new green approach of reusing waste. Indeed, microcellulose was obtained by simple alkaline treatment from softwood almond shells. In particular, Prunus dulcis Miller (D.A.) Webb. was considered an agro-industrial waste largely available in southern Italy. To value the possibility of using this material in a circular economy framework, a microcellulosic material was used, by adding different binders, to manufacture several stuccos to utilize as wood consolidants. Successively, in order to obtain stuccos with biocidal properties against fungal colonization or insect infestation, to which wooden artifacts are often exposed, cellulose pulp was combined with the essential oil of Thymus capitaus (L.) Hoffmanns. & Link., whose biological properties have been largely reported. The physical flexion properties of all new materials were tested

PARTICLE-PARTICLE CORRELATIONS: A TOOL FOR INVESTIGATING EXCITED STATES AND CLUSTERING EFFECTS IN THE DECAY OF EXCITED NUCLEI

In this contribution we present a selection of results from experiments performed at INFN Laboratori Nazionali di Legnaro exploiting the 4π GARFIELD + RCo apparatus. The investigated reactions are the medium-heavy 32S + 58,64Ni, and the light 12C + 12C and 14N + 10B systems. For the first set of reactions, we extracted information on fragments in the last but one stage of the compound nucleus decay using particle-particle and fragmentfragment correlation functions. In particular, the issue of odd-even staggering was addressed. We show that the distribution of excited fragments displays odd-even effects, but reversed with respect to the asymptotic distributions. The conclusion is that the staggering cannot be only due to the pairing effect of nuclear masses, but it is also influenced by pairing and possibly isospin effects in the level density. In the light nuclei reactions the possible α-cluster states in even-even nuclei were investigated through particle-particle correlations. Thanks to this powerful technique we were able to reconstruct the particle emission sequence, thus showing that multiple α particle emission from the decay of 24Mg* and 12C* can be understood as a sequential process with an important contribution of doorway Be states. Other chosen applications of the correlation function technique are also briefly reviewed, including measurement of the size, emission time, temperature and symmetry energy of excited nuclear sources.status: publishe