Wearing a single DNA molecule with an AFM tip

While the fundamental limit on the resolution achieved in an atomic force microscope (AFM) is clearly related to the tip radius, the fact that the tip can creep and/or wear during an experiment is often ignored. This is mainly due to the difficulty in characterizing the tip, and in particular a lack of reliable methods that can achieve this in situ. Here, we provide an in situ method to characterize the tip radius and monitor tip creep and/or wear and biomolecular sample wear in ambient dynamic AFM. This is achieved by monitoring the dynamics of the cantilever and the critical free amplitude to observe a switch from the attractive to the repulsive regime. The method is exemplified on the mechanically heterogeneous sample of single DNA molecules bound to mica mineral surfaces. Simultaneous monitoring of apparent height and width of single DNA molecules while detecting variations in the tip radius R as small as one nanometer are demonstrated. The yield stress can be readily exceeded for sharp tips (R10nm). The ability to know the AFM tip radius in situ and in real-time opens up the future for quantitative nanoscale materials properties determination at the highest possible spatial resolution.Comment: 26 pages, 6 figure

Activity Recognition based on a Magnitude-Orientation Stream Network

The temporal component of videos provides an important clue for activity recognition, as a number of activities can be reliably recognized based on the motion information. In view of that, this work proposes a novel temporal stream for two-stream convolutional networks based on images computed from the optical flow magnitude and orientation, named Magnitude-Orientation Stream (MOS), to learn the motion in a better and richer manner. Our method applies simple nonlinear transformations on the vertical and horizontal components of the optical flow to generate input images for the temporal stream. Experimental results, carried on two well-known datasets (HMDB51 and UCF101), demonstrate that using our proposed temporal stream as input to existing neural network architectures can improve their performance for activity recognition. Results demonstrate that our temporal stream provides complementary information able to improve the classical two-stream methods, indicating the suitability of our approach to be used as a temporal video representation.Comment: 8 pages, SIBGRAPI 201

Um método proativo para gerenciamento da segurança em instalações nucleares

Em razão da abordagem moderna para tratar a segurança em instalações nucleares que destaca que estas organizações devem ser capazes de avaliar e gerenciar de forma proativa suas atividades torna-se cada vez mais importante a necessidade de instrumentos de avaliação das condições de trabalho. Nesse contexto, este trabalho apresenta um método proativo de gerenciamento da segurança organizacional, o qual apresenta três características inovadoras: 1) a utilização de indicadores preditivos que fornecem informações atuais sobre o desempenho das atividades, permitindo ações preventivas e não somente reativas na gestão da segurança, diferente dos indicadores de segurança tradicionalmente utilizados (indicadores reativos) que são obtidos após a ocorrência de eventos indesejados; 2) a adoção do enfoque da engenharia de resiliência no desenvolvimento dos indicadores – os indicadores são baseados em seis princípios da engenharia de resiliência: comprometimento da alta direção, aprendizagem, flexibilidade, consciência, cultura de justiça e preparação para os problemas; 3) a adoção dos conceitos e propriedades da teoria dos conjuntos fuzzy para lidar com a subjetividade e a consistência dos julgamentos humanos na avaliação dos indicadores. A teoria fuzzy é usada essencialmente para mapear modelos qualitativos de tomada de decisão, e para métodos de representação imprecisa. Os resultados deste trabalho objetivam uma melhoria no desempenho e na segurança nas organizações. O método foi aplicado no setor de expedição de radiofármacos de uma instalação nuclear. Os resultados mostraram que o método é uma boa ferramenta de monitoramento de forma objetiva e proativa das condições de trabalho de um domínio organizacional

Design and implementation of intelligent packet filtering in IoT microcontroller-based devices

Internet of Things (IoT) devices are increasingly pervasive and essential components in enabling new applications and services. However, their widespread use also exposes them to exploitable vulnerabilities and flaws that can lead to significant losses. In this context, ensuring robust cybersecurity measures is essential to protect IoT devices from malicious attacks. However, the current solutions that provide flexible policy specifications and higher security levels for IoT devices are scarce. To address this gap, we introduce T800, a low-resource packet filter that utilizes machine learning (ML) algorithms to classify packets in IoT devices. We present a detailed performance benchmarking framework and demonstrate T800's effectiveness on the ESP32 system-on-chip microcontroller and ESP-IDF framework. Our evaluation shows that T800 is an efficient solution that increases device computational capacity by excluding unsolicited malicious traffic from the processing pipeline. Additionally, T800 is adaptable to different systems and provides a well-documented performance evaluation strategy for security ML-based mechanisms on ESP32-based IoT systems. Our research contributes to improving the cybersecurity of resource-constrained IoT devices and provides a scalable, efficient solution that can be used to enhance the security of IoT systems.Comment: 11 pages, under revie

Postpartum changes in plasma viral load and CD4 percentage among HIV-infected women from Latin American and Caribbean countries: the NISDI Perinatal Study

The goal of this study was to evaluate changes in plasma human immunodeficiency virus (HIV) RNA concentration [viral load (VL)] and CD4+ percentage (CD4%) during 6-12 weeks postpartum (PP) among HIV-infected women and to assess differences according to the reason for receipt of antiretrovirals (ARVs) during pregnancy [prophylaxis (PR) vs. treatment (TR)]. Data from a prospective cohort of HIV-infected pregnant women (National Institute of Child Health and Human Development International Site Development Initiative Perinatal Study) were analyzed. Women experiencing their first pregnancy who received ARVs for PR (started during pregnancy, stopped PP) or for TR (initiated prior to pregnancy and/or continued PP) were included and were followed PP. Increases in plasma VL (> 0.5 log10) and decreases in CD4% (> 20% relative decrease in CD4%) between hospital discharge (HD) and PP were assessed. Of the 1,229 women enrolled, 1,119 met the inclusion criteria (PR: 601; TR: 518). At enrollment, 87% were asymptomatic. The median CD4% values were: HD [34% (PR); 25% (TR)] and PP [29% (PR); 24% (TR)]. The VL increases were 60% (PR) and 19% (TR) (p < 0.0001). The CD4% decreases were 36% (PR) and 18% (TR) (p < 0.0001). Women receiving PR were more likely to exhibit an increase in VL [adjusted odds ratio (AOR) 7.7 (95% CI: 5.5-10.9) and a CD4% decrease (AOR 2.3; 95% CI: 1.6-3.2). Women receiving PR are more likely to have VL increases and CD4% decreases compared to those receiving TR. The clinical implications of these VL and CD4% changes remain to be explored.Universidade Federal de Minas Gerais Faculdade de MedicinaWestatUniversidad Nacional Mayor de San MarcosHospital FeminaHospital ConceiçãoUniversidade Federal de São Paulo (UNIFESP)Hospital dos Servidores do EstadoNational Institute of Health Human Development Department of Health and Human ServicesUNIFESPSciEL

A strategy to overcome multispecies vascular catheter-related infections

Funding Information: The authors thank Fundação para a Ciência e Tecnologia (FCT) Portugal, for the financial support under the Project PTDC/BTM-SAL/29335/2017 . Portugal 2020 for the Portuguese Mass Spectrometry Network (Rede Nacional de Espectrometria de Massa RNEM ) is also acknowledged. The authors also acknowledge the Designer Nuno Monge for the artwork, Isabel Dias Nogueira (Microlab, Instituto Superior Técnico, Lisbon University) for the technical assistance with the SEM analysis, Andreia Bento for the assistance with the UHPLC-MS equipment (iMed.Ulisboa) and Professor Maria José Ferreira (FFULisboa) for allowing the use of the automatic flash chromatography equipment. Funding Information: The authors thank Fundação para a Ciência e Tecnologia (FCT) Portugal, for the financial support under the Project PTDC/BTM-SAL/29335/2017. Portugal 2020 for the Portuguese Mass Spectrometry Network (Rede Nacional de Espectrometria de Massa RNEM) is also acknowledged. The authors also acknowledge the Designer Nuno Monge for the artwork, Isabel Dias Nogueira (Microlab, Instituto Superior Técnico, Lisbon University) for the technical assistance with the SEM analysis, Andreia Bento for the assistance with the UHPLC-MS equipment (iMed.Ulisboa) and Professor Maria José Ferreira (FFULisboa) for allowing the use of the automatic flash chromatography equipment. Publisher Copyright: © 2022In clinic there is a demand to solve the drawback of medical devices multispecies related infections. Consequently, different biomaterial surfaces, such as vascular catheters, urgently need improvement regarding their antifouling/antimicrobial properties. In this work, we covalently functionalized medical grade polydimethylsiloxane (PDMS) with antimicrobial rhamnolipids to investigate the biomaterial surface activity towards mono and dual species biofilms. Preparation of surfaces with “piranha” oxidation, followed by APTES bonding and carbodiimide reaction with rhamnolipids effectively bonded these compounds to PDMS surface as confirmed by FTIR-ATR and XPS analysis. Generated surfaces were active towards S. aureus biofilm formation showing a 4.2 log reduction while with S. epidermidis and C. albicans biofilms a reduction of 1.2 and 1.0 log reduction, respectively, was observed. Regarding dual-species testing the higher biofilm log reduction observed was 1.9. Additionally, biocompatibility was assessed by cytocompatibility towards human fibroblastic cells, low platelet activation and absence of vascular irritation. Our work not only sheds light on using covalently bonded rhamnolipids towards dual species biofilms but also highlights the biocompatibility of the obtained PDMS surfaces.publishersversionpublishe

Stearic acid, beeswax and carnauba wax as green raw materials for the loading of carvacrol into nanostructured lipid carriers

The use of lipid nanoparticles as drug delivery systems has been growing over recent decades. Their biodegradable and biocompatible profile, capacity to prevent chemical degradation of loaded drugs/actives and controlled release for several administration routes are some of their advantages. Lipid nanoparticles are of particular interest for the loading of lipophilic compounds, as happens with essential oils. Several interesting properties, e.g., anti-microbial, antitumoral and antioxidant activities, are attributed to carvacrol, a monoterpenoid phenol present in the composition of essential oils of several species, including Origanum vulgare, Thymus vulgaris, Nigellasativa and Origanum majorana. As these essential oils have been proposed as the liquid lipid in the composition of nanostructured lipid carriers (NLCs), we aimed at evaluating the influence of carvacrol on the crystallinity profile of solid lipids commonly in use in the production of NLCs. Different ratios of solid lipid (stearic acid, beeswax or carnauba wax) and carvacrol were prepared, which were then subjected to thermal treatment to mimic the production of NLCs. The obtained binary mixtures were then characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS) and polarized light microscopy (PLM). The increased concentration of monoterpenoid in the mixtures resulted in an increase in the mass loss recorded by TG, together with a shift of the melting point recorded by DSC to lower temperatures, and the decrease in the enthalpy in comparison to the bulk solid lipids. The miscibility of carvacrol with the melted solid lipids was also confirmed by DSC in the tested concentration range. The increase in carvacrol content in the mixtures resulted in a decrease in the crystallinity of the solid bulks, as shown by SAXS and PLM. The decrease in the crystallinity of lipid matrices is postulated as an advantage to increase the loading capacity of these carriers. Carvacrol may thus be further exploited as liquid lipid in the composition of green NLCs for a range of pharmaceutical applications.This work was funded by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq/Brazil), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/Brazil, FinanceCode 001), by the Portuguese Science and Technology Foundation (FCT/MCT) and European Funds (PRODER/COMPETE) under the projects M-ERA-NET/0004/2015 and UIDB/04469/2020 (strategic fund), co-financed by FEDER, under the Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio

A Contribution to the Bio and Circular Economy

and Cássia H. Barbosa’s Ph.D. fellowship (2021.08154.BD). MMA thanks the Instituto Superior Técnico for the Scientific Employment contract (contract No: IST-ID/154/2018) under Decree-Law No. 57/2016 and 57/2017. Publisher Copyright: © 2023 by the authors.The development of innovative/sustainable materials capable of enlarging the shelf-life of food products has lately been a focus of research, aiming to reduce food waste. Due to their good antimicrobial properties, zinc oxide nanoparticles (ZnO NPs) can add activity to food packaging, improving its performance. Furthermore, these nanoparticles are considered GRAS by the Food and Drug Administration (FDA), which represents an advantage in their application. Through an innovative and sustainable approach using tomato and passionfruit extracts, ZnO NPs were produced and incorporated into pectin films. The resulting bionanocomposites were tested for their activity via in situ studies, using fresh poultry meat as a food matrix. Overall, the bionanocomposites presented good antimicrobial activity, with the intrinsic antimicrobial properties of pectin having shown to be enhanced by the incorporated ZnO NPs. When used as primary packaging for the meat, the deterioration rate of the poultry meat, measured through microbiological growth and total volatile basic nitrogen content, was reduced. However, the nanoparticles contributed to the increment of discoloration and meat oxidation processes. Nonetheless, it can be concluded that fresh poultry meat protected with the bionanocomposites presented an extension of its shelf-life time, and it was confirmed that this eco-friendly packaging has potential to be employed by the food industry.publishersversionpublishe