Experimental and theoretical L-subshell ionization cross sections for 83Bi by electron impact from the L3 threshold to 100 keV

We report experimental and theoretical Bi L1, L2, and L3 subshell ionization cross sections by the impact of electrons with energies from the Bi L3 ionization threshold to 100 keV. The x-ray spectra have been acquired with two Si drift detectors placed in vacuum, which allowed us to better evaluate the peak fit procedure in the L multiplet. The Lα, Lβ, Lγ, Lℓ, and Lη x-ray production cross sections, measured with relative uncertainties ranging from 5% to 9%, and two sets of atomic relaxation parameters have been used to derive the Bi L1, L2, and L3 ionization cross sections. Although the experimental uncertainties of the subshell ionization cross sections are smaller than those of the few previous measurements, they remain large due to the uncertainties associated with the relaxation parameters. Furthermore, ionization cross sections have been calculated for the three L subshells with the subconfiguration average distorted-wave (SCADW) formalism, which includes the full two-body retarded electromagnetic interaction between the projectile and target electrons. These theoretical cross sections are 15% to 30% lower than the measured values, but the agreement is reasonable given the aforementioned high uncertainties. We have also found that the simpler distorted-wave Born approximation yields subshell ionization cross sections that match those computed with the SCADW method

A setup for integral measurements of multiple scattering angular distributions by 10- to 100-keV electrons

A dedicated setup has been developed to study the angular distributions of electrons traversing thin films employing the low-energy beam available from the gun of the São Paulo Microtron. In this first stage, only integral measurements are possible using the fraction of the electron beam current collected in a Faraday cup and in a ring surrounding the entrance of the former. The overall normalisation is provided by measuring the beam current collected by the scattering chamber as well, thus covering the full solid angle. In this work, important construction specifications are presented. The experience gained by operating this system is also discussed regarding its critical aspects like: avoiding cross talk between the cup and the ring both at the physical and electronic levels, measurements of small charges deposited on large objects (the chamber in particular), and conditioning of the various surfaces involved. Finally, some selected results are compared to the well-known theory by Goudsmit and Saunderson with good agreement

Il blanching dei prodotti agro-alimentari: analisi e modellazione

Usually, the industrial processes were managed according to procedures which in turn were founded on previous experiences and traditions. Instead, the knowledge of the phenomena, which takes place during the transformation process, could help in optimizing and intensifying actions. A powerful tool, often neglected in industrial practice, to perform the desired optimization is the use of theoretical models which are able to simulate the real processes, i.e. the description of the unit operations in physical and mathematical terms. The availability of reliable mathematical models (predictive) allows remarkable savings during the design phase (the number of preliminary tests on laboratory and on pilot scale drastically decreases) and during the management (it is possible to test the effect of process condition change, even if this change does not take place in the real world). In the case history analyzed in this communication, two potential blanching treatments on foodstuff were investigated on laboratory scale (paying attention in particular to banana samples), a conventional treatment as well as a process assisted by microwave, with the aim of process intensification, and different models were tested to describe the observed phenomena

Integral measurements of plural and multiple scattering of electrons with energies between 10 and 100 keV for 6 ≤ Z ≤ 83: I. Thin and intermediate-thickness targets

Angle-integrated plural- and multiple-scattering distributions have been measured for electrons impinging with kinetic energies from 10 to 100 keV on targets with atomic numbers between those of C and Bi and mass thicknesses ranging from to 300 2. The thinnest targets, to 20 2, are not self-supporting and have been deposited on C backings with areal densities around 10 2. The intermediate-thickness ones are made of a single element and have mass thicknesses of to 300 2. The electrons scattered at frontal angles are collected with a Faraday cup covering the polar angles below 12.0°. In addition, to supplement this information, an aluminium ring spanning a polar angle interval of has been installed around the entrance of the Faraday cup and the charge deposited on it has also been recorded. The electrical current in the scattering chamber is measured as well so as to provide an accurate normalisation. Corrections for the fraction of impinging electrons backscattered by both the Faraday cup and the ring are applied to the data. The measurements are compared with the predictions of a Monte Carlo code that simulates each individual elastic collision. For targets made of a single element, the analytical Goudsmit–Saunderson and Lewis theories are tested as well. In all cases, the single-scattering angular differential cross sections, obtained by partial-wave solution of the Dirac equation in a self-consistent central potential, are taken from the ICRU Report 77. Good agreement is found within the uncertainties of the data. An analytical formula for the angular integration of the Goudsmit–Saunderson distribution is presented in an Appendix

Epidemiological and ecological aspects related to malaria in the area of influence of the lake at Porto Primavera dam, in western São Paulo State, Brazil Aspectos epidemiológicos e ecológicos relacionados à malária na área de influência do lago da Represa de Porto Primavera, região oeste do Estado de São Paulo, Brasil

A study was carried out in the area of influence of the Porto Primavera Hydroelectric Power Station, in western São Paulo State, to investigate ecological and epidemiological aspects of malaria in the area and monitor the profile of the anopheline populations following the environmental changes brought about by the construction of the lake. Mosquitoes captured were analyzed by standardized indicator species analysis (ISA) before and during different flooding phases (253 m and 257 m elevations). The local human population was studied by means of parasitological (thin/thick blood smears), molecular (PCR) and serological tests. Serological tests consisted of Enzyme Linked Immunosorbent Assay (ELISA) with synthetic peptides of the circumsporozoite protein (CSP) from classic Plasmodium vivax, P. vivax variants (VK247 and "vivax-like"), P. malariae and P. falciparum and Indirect Immunofluorescence Assay (IFA) with asexual forms of P. vivax, P. malariae and P. falciparum. The results of the entomological survey indicated that, although the Anopheles darlingi population increased after the flooding, the population density remained very low. No malaria, parasite infection or DNA was detected in the inhabitants of the study area. However, there was a low frequency of antibodies against asexual forms and a significant prevalence of antibodies against P. vivax, P. vivax variants, P. falciparum and P. malariae; the presence of these antibodies may result from recent or less recent contact with human or simian Plasmodium (a parallel study in the same area revealed the existence of a sylvatic cycle). Nevertheless, these results suggest that, as in other places where malaria is present and potential vectors circulate, the local epidemiological conditions observed could potentially support the transmission of malaria in Porto Primavera Lake if infected individuals are introduced in sufficient numbers. Further studies are required to elucidate the phenomena described in this paper.<br>Foi realizada pesquisa na área de influência do lago da Usina Hidrelétrica de Porto Primavera, região oeste do Estado de São Paulo, para estudar aspectos ecológicos e epidemiológicos da malária na localidade e acompanhar o perfil das populações de anofelinos frente às mudanças decorrentes do impacto ambiental pela formação do lago. Mosquitos capturados foram analisados pelo Índice de Abundância de Espécies Padronizado (IAEP), antes e durante o enchimento do reservatório (cotas 253 e 257 m). A população humana local foi estudada por meio de teste parasitológico (gota espessa e esfregaço sangüíneo), testes moleculares (PCR) e testes sorológicos. A sorologia consistiu na reação de ELISA com peptídeos sintéticos correspondentes à porção repetitiva da proteína circumsporozoíta (CSP) de Plasmodium vivax clássico, e suas variantes VK247 e "vivax-like", P. malariae e P. falciparum; e reação de Imunofluorescência Indireta (RIFI) com formas assexuadas de P. vivax, P. malariae e P. falciparum. Os resultados do estudo entomológico indicaram que, embora a população de Anopheles darlingi tenha aumentando após o enchimento, permaneceu em baixa densidade. Não foi detectada malária nem a presença de parasitos ou de DNA parasitário nos habitantes estudados. No entanto, foi observada baixa freqüência de anticorpos contra formas assexuadas e significativa prevalência de anticorpos contra esporozoítos de P. vivax e suas variantes, P. falciparum e P. malariae, que poderiam decorrer de contatos prévios, recentes ou não, com plasmódios humanos ou símios (o ciclo silvestre foi evidenciado em estudo paralelo realizado na mesma área). Por outro lado, estes resultados sugerem que, como em outros lugares onde existem vetores potenciais da malária, as condições epidemiológicas poderiam potencialmente permitir a transmissão da malária na área de influência do lago de Porto Primavera, se indivíduos infectados fossem introduzidos em número suficiente. Estudos adicionais deverão ser realizados para elucidar os fenômenos relatados neste artigo