Next-generation experiments searching for rare events must satisfy increasingly stringent requirements on the bulk and surface radioactive contamination of their active and structural materials. The ...measurement of surface contamination is particularly challenging, as no existing technology is capable of separately measuring parts of the 232Th and 238U decay chains that are commonly found to be out of secular equilibrium. We will present the results obtained with a detector prototype consisting of 8 silicon wafers of 150 mm diameter instrumented as bolometers and operated in a low-background dilution refrigerator at the Gran Sasso Underground Laboratory of INFN, Italy. The prototype was characterized by a baseline energy resolution of few keV and a background <100 nBq/cm2 in the full range of α energies, obtained with simple procedures for cleaning of all employed materials and no specific measures to prevent recontamination. Such performance, together with the modularity of the detector design, demonstrate the possibility to realize an alpha detector capable of separately measuring all alpha emitters of the 232Th and 238U chains, possibly reaching a sensitivity of few nBq/cm2.
•Material screening.•Bolometric alpha detector.•Low-radioactivity measurements.
Abstract
The development of new sample preparation alternatives in analytical toxicology leading to quick, effective, automated and environmentally friendly procedures is growing in importance. One ...of these alternatives is the QuEChERS, originally developed for the analysis of pesticide residues, producing cleaner extracts than liquid–liquid extraction, and easier separation of aqueous and organic phases. However, there are few published studies on the miniaturization of this technique for forensic toxicology, especially in postmortem analysis. We developed and validated a modified micro-QuEChERS and LC–MS-MS assay to quantify 16 antidepressants, 7 antipsychotics and 3 metabolites and semi-quantify norfluoxetine and norsertraline in postmortem blood. The calibration curve was linear from 1 to 500 ng/mL, achieved an r > 0.99, with all standards quantifying within ±15% of target except ±20% at the limit of quantification of 1 ng/mL for 26 substances. The F test was applied to evaluate if the variance between replicates remained constant for all calibrators. Six weighting factors were analyzed (1/x, 1/x2, 1/x0,5, 1/y, 1/y2 and 1/y0,5), with the weighting factor with the lowest sum of residual regression errors (1/x2) selected. No endogenous or exogenous interferences were observed. Method imprecision and bias were <19.0% and 19.7%, respectively. Advantages of this method include a low sample volume of 100 µL, simple but effective sample preparation and a rapid 8.5-min run time. The validated analytical method was successfully applied to the analysis of 100 authentic postmortem samples.
The abuse of chat services by automated programs, known as chat bots, poses a serious threat to Internet users. Chat bots target popular chat networks to distribute spam and malware. In this paper, ...we first conduct a series of measurements on a large commercial chat network. Our measurements capture a total of 16 different types of chat bots ranging from simple to advanced. Moreover, we observe that human behavior is more complex than bot behavior. Based on the measurement study, we propose a classification system to accurately distinguish chat bots from human users. The proposed classification system consists of two components: 1) an entropy-based classifier; and 2) a Bayesian-based classifier. The two classifiers complement each other in chat bot detection. The entropy-based classifier is more accurate to detect unknown chat bots, whereas the Bayesian-based classifier is faster to detect known chat bots. Our experimental evaluation shows that the proposed classification system is highly effective in differentiating bots from humans.
Abstract This study assesses the interpretive value of cocaine, benzoylecgonine (BZE) and cocaethylene (COET) in skeletal muscle ( rectus femoris ) in cocaine-using decedents. The distribution of ...these analytes in cardiac muscle (CM), vitreous humour (VH), femoral blood (FB) and cardiac blood (CB) is also reported. In rectus femoris muscle, the spatial distribution of the analytes was examined across the whole rectus femoris muscle collected from seven fatalities in which cocaine was detected. In six of these cases, death was attributed to trauma and in one case the cause of death was undetermined but suspected to be drug related. In two additional cases analytes were detected in the blood and/or VH but not in the muscle. The muscle was sectioned into 12–15 approximately equal segments, each of which was analysed after homogenisation. Tissue and bio-fluid samples were extracted by solid phase extraction with confirmation and quantification by GC–ion trap-MS/MS. No significant variation was observed in the concentration of any analyte throughout the muscle in the 7 cases analysed. The results reported here are in contrast to a previous study in which great variation in the concentration of some basic drugs (mainly tricyclic antidepressants and benzodiazepines) was observed throughout the thigh muscle bulk (Williams and Pounder, 1997). Analyte concentrations in skeletal muscle (SM) correlated well with those in FB ( p < 0.01). In general, the concentration of cocaine and COET followed the order VH > CM > SM > FB ≥ CB. Cocaine concentrations measured in VH were significantly higher than in blood and muscle. Inter-matrix variations in the concentrations of BZE and COET were less marked. The concentration of BZE exceeded that of cocaine in all matrices and in all cases except one where the time between death and drug intake was suspected to be short. In this case, the cocaine to BZE ratio measured in SM (2.66), CM (2.91) and VH (2.19) was higher than that measured in FB (0.97). Given that the concentrations of cocaine and its metabolites were uniformly distributed throughout the muscle and considering the good correlation observed between muscle and blood, muscle could be of interpretive value in cocaine related deaths. Further, since cocaine is known to have greater post-mortem stability in muscle than blood, concentrations measured in muscle may reflect more closely those at the time of death and might be of particular value in cases with an extended period between death and tissue sampling.
Introdução: A relação médico-paciente é a base da Medicina e está fundamentada nos princípios da beneficência, não-maleficência, justiça e autonomia. A perícia médica surgiu diante da necessidade da ...aplicação de conhecimentos técnicos no âmbito do Direito. As diferenças entre essas duas atuações médicas é objeto de conflitos que dificultam a atuação do médico perito. Objetivo: Estabelecer as diferenças e semelhanças entre a relação médico-paciente e a relação perito-periciando. Material e Métodos: Revisão de literatura de artigos e periódicos em língua portuguesa na base de dados Scielo e em livros especializados sobre o assunto. Discussão: A relação médico-paciente se baseia em confiança mútua, estabelecimento de vínculo mútuo, busca por um resultado em comum: diagnóstico e tratamento; há coerência entre a comunicação verbal e não verbal, a anamnese constitui o principal método propedêutico, sendo os exames complementares solicitados para auxiliar o diagnóstico e há o compromisso com o sigilo profissional. Já a relação perito-periciando possui uma natureza investigativa, não havendo uma relação de confiança mútua, a finalidade é o esclarecimento da Justiça e o sigilo profissional não fica restrito ao binômio perito-periciando. A semelhança entre essas duas relações está relacionada à conduta do médico que deve ser pautada na técnica, no respeito, educação e abstenção de julgamentos morais e de valores, além da necessidade de atualização por parte do profissional. Conclusão: A relação médico-paciente e a relação perito-periciando apresentam características peculiaridades e algumas delas são inconfundíveis. Em ambas as situações observamos a importância da atuação médica como essência desta relação e suas consequentes implicações morais, jurídicas e éticas.
The Cryogenic Underground Observatory for Rare Events (CUORE) at Laboratori Nazionali del Gran Sasso of INFN in Italy is an experiment searching for neutrinoless double beta (0νββ) decay. Its main ...goal is to investigate this decay in 130Te, but its ton-scale mass and low background make CUORE sensitive to other rare processes as well. Here, in this Letter, we present our first results on the search for 0νββ decay of 128Te, the Te isotope with the second highest natural isotopic abundance. We find no evidence for this decay, and using a Bayesian analysis we set a lower limit on the 128Te 0νββ decay half-life of T1/2 > 3.6 x 1024 yr (90% CI). This represents the most stringent limit on the half-life of this isotope, improving by over a factor of 30 the previous direct search results, and exceeding those from geochemical experiments for the first time.
The Cryogenic Underground Observatory for Rare Events (CUORE) is a large-scale cryogenic experiment searching for neutrinoless double-beta decay (0νββ) in 130Te. The CUORE detector is made of natural ...tellurium, providing the possibility of rare event searches on isotopes other than 130Te. In this work we describe a search for neutrinoless positron-emitting electron capture (β+ EC ) decay in 120Te with a total TeO2 exposure of 355.7 kg yr, corresponding to 0.2405 kg yr of 120Te. Albeit 0νββ with two final-state electrons represents the most promising channel, the emission of a positron and two 511-keV γ 's make 0νβ+ EC decay signature extremely clear. To fully exploit the potential offered by the detector modularity we include events with different topology and perform a simultaneous fit of five selected signal signatures. Using blinded data we extract a median exclusion sensitivity of 3.4 × 1022 yr at 90% credibility interval (C.I.). After unblinding we find no evidence of 0νβ+ EC signal and set a 90% C.I. Bayesian lower limit of 2.9 × 1022 yr on 120Te half-life. This result improves by an order of magnitude the existing limit from the combined analysis of CUORE-0 and Cuoricino.
The increase in the number of users, hospitalizations and deaths due to overdose of synthetic opioids made the scientific community to treat this problem as “the opioid crisis”, justifying the need ...for the development of analytical strategies to identify and quantify these drugs. Even with the global discussion, there is no Brazilian data regarding opioids consumption, addiction or fatal intoxication cases. The aim of this work was to develop, validate and applied an analytical method based on liquid chromatography-tandem mass spectrometry for determination of fentanyl and seven analogues (acetyl norfentanyl, acetyl fentanyl, thiofentanyl, acrylfentanyl, furanylfentanyl, carfentanil and valerylfentanyl) in postmortem blood samples, to the routine analysis of the Forensic Toxicology Laboratory of São Paulo State Police. Linearity was evaluated from 1-500 ng mL-1 (correlation coefficient (r) value (r ≥ 0.99), 1/x weight linear regression), with limit of quantification of 1 ng mL-1. The method imprecision, bias and matrix effect were lower than 19.7%. No interference or carryover were observed, and extraction yield was greater than 57.7%. Analysis of postmortem blood samples (n = 1,359) showed that fentanyl was the most frequently detected opioid. The developed method proved to be useful for routine analysis of the Forensic Toxicology Laboratory.
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