Comparative Study of Influence of Experimental Configuration on Densities of Active Species in the Early Afterglows of N2/(0–2.5%)H2 HF Flowing Plasmas

Afterglows of mixed gas of N₂ and H₂(0–2.5%) flowing microwave discharges in a 5 mm diameter tube connected to a 5 L reactor via a tube of 1.8 cm diameter and 50 cm long, have been studied using optical emission spectroscopy. The obtained results at the entrance of the afterglow tube of 1.8 cm diameter: Short time afterglow (SA), (10^–3 s) and inside the 5 L reactor: Long time afterglow (LA), (10^–2 s) were then compared. It was found that, in N₂ at 2 Torr, 0.5 slpm, the active specie density ratios had a constant value of 10^–2 for N/N₂, but decreased respectively from 10^–3 to 10^–4 for N₂ (X,v?>?13)/N₂ and from 10^–6 to 10^–8 for N⁺₂ /N₂. By directly connecting the discharge tube inside the 5 L reactor, the density increases by 10 for N₂ (X,v?>?13) and by 10² for N₂⁺ by changing the afterglow from LA(10^?2 s) to a SA(10^–3 s). Moreover and by adding 1% of H₂ to N₂, the N/N₂ and H/H₂ ratios had constant values of 1% and 0.2% respectively. The SA(10^–3 s) appeared to be more efficient for surface treatments than the LA (10^–2 s).

     

Chemical Strategies for Dendritic Magneto-plasmonic Nanostructures Applied to Surface-Enhanced Raman Spectroscopy

Chemical analyses in the field using surface-enhanced Raman scattering (SERS) protocols are expected to be part of several analytical procedures applied to water quality monitoring. To date, these endeavors have been supported by developments in SERS substrate nanofabrication, instrumentation portability, and the internet of things. Here, we report distinct chemical strategies for preparing magneto-plasmonic (Fe₃O₄ : Au) colloids, which are relevant in the context of trace-level detection of water contaminants due to their inherent multifunctionality. The main objective of this research is to investigate the role of poly(amidoamine) dendrimers (PAMAMs) in the preparation of SERS substrates integrating both functionalities into single nanostructures. Three chemical routes were investigated to design magneto-plasmonic nanostructures that translate into different ways for assessing SERS detection by using distinct interfaces. Hence, a series of magneto-plasmonic colloids have been characterized and then assessed for their SERS activity by using a model pesticide (thiram) dissolved in aqueous samples.     

Tetracyclic Thioxanthene Derivatives: Studies on Fluorescence and Antitumor Activity

Thioxanthones are bioisosteres of the naturally occurring xanthones. They have been described for multiple activities, including antitumor. As such, the synthesis of a library of thioxanthones was pursued, but unexpectedly, four tetracyclic thioxanthenes with a quinazoline–chromene scaffold were obtained. These compounds were studied for their human tumor cell growth inhibition activity, in the cell lines A375-C5, MCF-7 and NCI-H460. Photophysical studies were also performed. Two of the compounds displayed GI₅₀ values below 10 µM for the three tested cell lines, and structure–activity relationship studies were established. Three compounds presented similar wavelengths of absorption and emission, characteristic of dyes with a push-pull character. The structures of two compounds were elucidated by X-ray crystallography. Two tetracyclic thioxanthenes emerged as hit compounds. One of the two compounds accumulated intracellularly as a bright fluorescent dye in the green channel, as analyzed by both fluorescence microscopy and flow cytometry, making it a promising theranostic cancer drug candidate.     

Evaluation of PEGylated fibrin as a three-dimensional biodegradable scaffold for ovarian tissue engineering

The most challenging task of creating a bioengineered ovary to restore fertility in cancer patients is choosing an appropriate biomaterial to encapsulate isolated preantral follicles and ovarian cells. In this study, as a biocompatible and biodegradable biomaterial containing fibrin-like bioactivity and manageable physical properties, PEGylated fibrin aims to encapsulate isolated ovarian stromal cells as a first step of creating an engineered ovarian tissue. For this purpose, human ovarian stromal cells were isolated from frozen-thawed ovarian tissue and cultured in the PEGylated fibrin hydrogels (PEG:Fib), which were fabricated by combining two different molar ratios of PEG:Fib (10:1 and 5:1) and two thrombin concentrations. The samples were analyzed at days 0 and 5 of in vitro for cell density, proliferation (Ki67), and apoptosis (caspase-3). Moreover, LIVE/DEAD and PrestoBlue assays assessed cell viability and proliferation on days 1, 3, and 5. The effect of PEGylation on the biodegradation behavior of fibrin was evaluated by measuring the remaining mass ratio of non-modified fibrin, PEG:Fib 10:1, and PEG:Fib 5:1 hydrogels after 1, 2, 3, 5, 8, 11, and 15 days. The results showed that PEGylated fibrin hydrogels enhanced scaffold stability and supported cell viability and proliferation. In addition, PEG:Fib 5:1 T50 indicated a significantly higher cell density dynamic and non-significantly lower expression of caspase-3 on day 5. Besides, uniformity of cell distribution inside the hydrogel and a tendency to a high rate of Ki67-positive cells was observed in PEG:Fib 10:1 T50 hydrogels. In conclusion, this study reveals the positive effects of PEGylated fibrin hydrogels on isolated human ovarian stromal cells. Based on such promising findings, we believe that this matrix should be tested to encapsulate isolated human ovarian follicles.     

Use of Cucurbit[6]uril as Ionophore in Ion Selective Electrodes for Etilefrine Determination in Pharmaceuticals

Cucurbiturils are macrocyclic molecules and have been used with promising results in the development of electrochemical sensors and biosensors due to their main properties such as shape, selectivity, binding interactions and solubility. However, its application for the development of ion selective electrodes has been scarce. In this work, cucurbit[6]uril was used as molecular‐recognition compound for etilefrine sensing membrane with potentiometric transduction. The etilefrine selective electrode was evaluated and proposed as an alternative methodology for pharmaceutical quality control. Different membranes composition were evaluated, considering the use of different solvent mediators and the presence of anionic additives. The best membrane comprises 9.24 mmol.Kg^?1 of cucurbit[6]uril, 68.90 % (w/w) of dibutylsebacate and 30.18 % (w/w) of carboxylated polyvinyl chloride. The electrode exhibited selective cationic response toward the etilefrine in a concentration interval of more than four decades, with an slope of 57.4±0.5 mV dec^?1, a practical detection limit of (8±1)×10^?7 mol L^?1 and a low limit of linear range of (1.25±0.28)×10^?6 mol L^?1. The selectivity of the electrode towards different interfering was high. A comparative evaluation of the accuracy and precision of both procedures was done using the t‐student test (t4,12=1.135) and the Fischer test (F12,4=2.42) and compared with the tabulated ones (t4,12=1.135, F11,3=5.91) for the level of confidence of 95 %.     

Production of N,H, and NH active species in N2-H2 dc flowing discharges

Densities of N, H, and NH active species have been detected by laser-induced fluorescence (LIF) in N₂-xH₂ dc flowing discharges. A peak value of N atom densities far x = 0.2–0.5% and a plateau value of H atom densities between x = 1% and 90% in post-discharge conditions (0.05 sec, p = 2 torr) has been found. Comparison between LIF measurements of N atoms and the trend of the N₂(B, v = II) population shows that the emission from this state can be used for monitoring N atoms. The NH radical has only been detected inside the discharge region.On leave from Instituto Tecnológico de Aeronáutica, CNPq, Brazil.     

Morphology of PMMA/polyoxide blends and grafted copolymers using etching and staining techniques

The morphology of poly(methyl methacrylate), poly(ethylene oxide) blend and the grafted copolymer poly(methyl methacrylate-g-ethylene oxide) was observed by scanning electron microscopy. The contrast was obtained by an etching technique, removing the PEO phase out of the blend. The PEO phase of the copolymer was stained with OsO₄ and better contrast was observed using a back-scattering image. The PEO phase was shown to be distributed as spherical domains in the PMMA matrix for both the copolymer and the blend.     

Heritability of Stroop and flanker performance in 12-year old children

Background  

There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks.