The use of conducting polymers as coating layers for the protection of surfaces against corrosion represents an important topic for investigation, as reported in the literature. In this work, ...polypyrrole/Fe3O4 nanoparticles (Fe3O4_NPs/PPy) hybrid nanocomposites (HN) were incorporated as anticorrosive additives in an epoxy paint to protect SAE 1010 carbon steel from corrosion. The HN particles were obtained by chemical polymerization of pyrrole in an aqueous solution in the presence of Fe3O4_NPs and were characterized by infrared absorption spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM). The electrochemical impedance spectroscopy (EIS) was used in the analysis of the electrochemical response of the coated surface with and without HN. DLS data showed that the Fe3O4_NPs and Fe3O4_NPs/PPy obtained in solution present average diameters of (19.7 ± 9.6) nm and (63.5 ± 27.7) nm, respectively. TEM images showed Fe3O4_NPs with smaller sizes (10 nm - 30 nm), and that the HN had diameters smaller than 100 nm, consisting of Fe3O4 cores coated with polypyrrole. EIS measurements have shown that the addition of HN to the epoxy paint could improve the efficiency of the anticorrosive coating when compared to the original epoxy paint prepared without any corrosion inhibitor.
We report the preparation of flexible polystyrene/polypyrrole (PS/PPy) mats and their successful use as a resistive humidity sensor. These composite membranes were prepared by first obtaining PS ...films through the electrospinning technique, and then incorporating PPy chains by an in situ chemical polymerization of the pyrrole monomer. The PS fibers were homogeneously distributed, with diameters that obeyed a normal distribution with an average value of (1.04 ± 0.12) μm. The deposition of conducting PPy chains on the surface of the PS fibers was confirmed after characterizing the PS/PPy mats by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), contact angle measurements, and electrochemical impedance spectroscopy (EIS). When used as humidity sensors, the PS/PPy mats exhibited a sensor response of 128.6%, with fast response ((54.9 ± 3.5)s) and recovery times ((76.8 ± 11.1)s), and stable response under different humidity conditions over several days. These performance characteristics compare favorably to those of previous resistive humidity sensors discussed in the literature.
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•We deposited polypyrrole (PPy) chains on electrospun polystyrene (PS) films by in situ polymerization.•We examined the use of these hydrophilic PS/PPy films as resistive humidity sensors.•The hybrid PS/PPy films exhibit good sensing response towards the presence of water vapor and fast response times.•The hybrid PS/PPy films appear as promising active materials for the development of humidity sensors.
After preparing composite PSGO films by coating electrospun polystyrene (PS) fibers with graphene oxide (GO), we examined their use as dye adsorbents for water remediation. The GO, which was ...synthesized via a modified Hummers' method, was adsorbed on the surface of the PS fibers. Through X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TGA) analyses, we characterized the structure and morphology of the composite films, confirming that the GO was successfully incorporated onto the PS fibers. SEM images revealed that the PS fibers exhibited a smooth surface and that the GO was uniformly deposited on them. TGA analysis indicated that the PSGO is composed of ∼13 wt% GO and ∼87 wt% PS, and that both components exhibited similar thermogravimetric behavior. We examined the removal of the methylene blue (MB) dye from aqueous solutions as a model system to assess the adsorptive properties of the PSGO films. The composite films had a removal capacity that was approximately 2.3 times greater than that of pure PS membranes. For all MB concentrations investigated, the removal of the dye, which was very fast in the first 30 min, the equilibrium value of the adsorption capacity (qe = 114 mg g−1) was reached after 120 min. The kinetics of the adsorption process was best described by the pseudo-second-order (PSO) model, which predicted an adsorption capacity (qt) of 116.69 mg g−1.
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•Fabrication and use of electrospun polystyrene fiber covered with graphene oxide.•GO-coated polystyrene is a promising adsorbent of the Methylene Blue dye.•Outstanding adsorptive capacity in comparison to other reported adsorbents.
The production of conductive and organic devices from a 3D printer represents a promising strategy for several areas. In particular, the synthesis of polypyrrole-coated acrylonitrile butadiene ...styrene (ABS) composites can be considered an important step to produce conductive supports for 3D printing. Herein, it is reported the production of ABS samples through the additive manufacturing process (3D printing) accordingly to the Fused Deposition Modeling (FDM) method. The hydrophilic behavior was controlled by the surface treatment using air plasma for the following step of coating with polypyrrole (PPy) via an in situ polymerization, using two different oxidants: ferric chloride (FeCl3.6H2O) and ammonium persulfate (APS). The chemical, optical, surface, and electrical properties of these materials were characterized through Fourier Transform infrared spectroscopy (FTIR), contact angle measurements, cyclic voltammetry, Scanning Electron Microscopy (SEM), 4-probe electrical measurement, and mechanical tensile testing. The ABS/PPy (FeCl3) composite exhibited a low electrical contact resistance and better performance for applications that require electrodes with a good conductance level.
We report the preparation of polyacrylonitrile/polypyrrole/polyaniline (PAN/PPy/PANI) mats, a new type of composite membrane obtained through an in situ chemical polymerization of pyrrole and aniline ...on an electrospun polymeric matrix of polyacrylonitrile, and their use for the capture and removal of Remazol Black B (RBB) dye molecules dissolved in an aqueous media. We characterized these membranes through scanning electron microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analysis (TGA), and contact angle measurements. We observed that the coating of electrospun PAN fibers was uniform, with the resulting membrane exhibiting a hydrophilic character. When exposed to RBB aqueous solutions at room temperature, the PAN/PPy/PANI mats presented the highest adsorption capacity (247.7 mg g−1) at pH 2. While the kinetics and adsorption isotherm data were best described by pseudo-second-order (PSO) and Langmuir models, respectively, the RBB adsorption was favored by an increase in the temperature. After subjecting the RBB-loaded membrane to different elution procedures, we were able to achieve full desorption in just 10 min. The thermal and environmental stability of the composite membranes allowed us to use them in at least 6 consecutive adsorption/desorption cycles without noticeable loss of their properties. These results suggest that PAN/PPy/PANI membranes are promising adsorbent materials for use in water remediation protocols.
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•We deposited polypyrrole and polyaniline on electrospun polyacrylonitrile films.•The PAN/PPy/PANI mats exhibited excellent capacity for adsorbing Remazol Black B.•The dye captured by the membranes can be completely desorbed in just 5 min.•These composite mats can be used in several adsorption/desorption cycles.
We performed an aqueous in situ polymerization of pyrrole in presence of modified montmorillonite particles to obtain a polypyrrole/organophilic montmorillonite clay (PPy/MMTO) nanocomposite with an ...intercalated structure. The natural clay was previously modified to become organophilic. The PPy/MMTO was mixed to PVA to prepare nanofibers through electrospinning methods. The different nanocomposites were characterized through Fourier transform infrared spectroscopy and UV–Vis spectroscopy, X-ray diffraction, scanning electron microscopy and impedance spectroscopy. We confirmed the clay organophilization by observing the (001) plane displacement from 6,1° to 5,5° and the presence of absorption bands in 2924 cm−1, 2853 cm−1 and 1479 cm−1, by XRD and FTIR analyses, respectively. We observed that the conductivity of the final PVA/PPy-MMTO nanofibers increased upon exposure to ammonia vapors, confirming that this hybrid material exhibits promising properties for use as active elements in gas sensors.
•We synthesized PVA/polypyrrole montmorillonite clay nanofibers by electrospinning.•The successful organophilization of the clay was confirmed by XRD analysis.•FTIR and UV–Vis spectra confirmed the synthesis of the PPY/OMMT nanocomposite.•EIS showed that the nanofibers have a good response to the exposure to ammonia gas.
This work describes the preparation of polyvinyl alcohol/polyaniline-montmorillonite clay (PVA/PANI-OMMT) nanofibers through electrospinning. Initially, for improving the compatibility of the clay ...towards the organic polymer, the montmorillonite (MMT) was submitted to an organophilization process using hexadecyltrimethylammonium bromide (CH3(CH2)15N(Br)(CH3)3). The PANI-OMMT composite, which was obtained after the in situ polymerization of aniline in presence of the organophilic clay (ratio of ≈1:3 in weight), was then placed in a matrix of PVA (weight ratio of 1:7 of composite:PVA) for the production of the PVA/PANI-OMMT composite fibers through electrospinning. We used several characterization techniques (X-ray diffraction (XRD); infrared absorption spectroscopy (FTIR), ultraviolet visible absorption spectroscopy (UV–Vis), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS)) to analyze the different samples produced. The clay organophilization was confirmed after observing the (001) plane displacement from 5,6° to 4,7° and absorption bands in 2924 cm−1, 2853 cm−1 and 1479 cm−1, as analyzed by XRD and FTIR, respectively. The presence of polyaniline in its emeraldine salt was identified by the presence of the characteristic UV–Vis absorption bands in 360 nm, 430 nm and 822 nm, while the formation of the PANI/OMMT nanocomposite was confirmed by observing the characteristic FTIR bands of each individual component. From the SEM images, we could establish that the resulting nanocomposite mats were composed by uniform fibers with an average diameter of 240 nm and presented good surface quality. We have found that EIS is an efficient technique for the evaluation of changes in the electric properties of the nanofibers after their exposure to vapors of methanol. We suggest that this organic-inorganic composite may find useful applications in the preparation of several devices based on polymers, such as heavy metal filtration membranes and gas sensors.
•We synthesized PVA/PANI-montmorillonite nanofibers by electrospinning.•The successful organophilization of the clay was confirmed by XRD analysis.•FTIR and UV–Vis spectra confirmed the synthesis of the PANI/OMMT nanocomposite.•EIS showed that the nanofibers have a good response to the exposure to methanol.
We describe the circulation of Saint Louis encephalitis virus (SLEV) in two Brazilian States during outbreaks of Dengue and Zika viruses. We detected the virus in a patient from Araraquara, State of ...São Paulo, and in patients and in a mosquito pool of Culex quinquefasciatus from Sinop, State of Mato Grosso. Phylogenetic analysis grouped samples from this study within genotype V, which are closely related to other strains that previously circulated in other parts of the country. Genotype V seems to have established circulation in Brazil.
Highlights
During epidemics of DENV and ZIKV, we detected SLEV in human and mosquito samples from two different Brazilian States;
SLEV detected in our samples belong to Genotype V of the virus;
The detection of SLEV was only possible because there were active arbovirus surveillance protocols in both areas;
Cellular entry of SARS-CoV-2 has been shown to rely on angiotensin-converting enzyme 2 (ACE2) receptors, whose expression in the testis is among the highest in the body. Additionally, the risk of ...mortality seems higher among male COVID-19 patients, and though much has been published since the first cases of COVID-19, there remain unanswered questions regarding SARS-CoV-2 impact on testes and potential consequences for reproductive health. We investigated testicular alterations in non-vaccinated deceased COVID-19-patients, the precise location of the virus, its replicative activity, and the immune, vascular, and molecular fluctuations involved in the pathogenesis.
We found that SARS-CoV-2 testicular tropism is higher than previously thought and that reliable viral detection in the testis requires sensitive nanosensors or RT-qPCR using a specific methodology. Through an in vitro experiment exposing VERO cells to testicular macerates, we observed viral content in all samples, and the subgenomic RNA's presence reinforced the replicative activity of SARS-CoV-2 in testes of the severe COVID-19 patients. The cellular structures and viral particles, observed by transmission electron microscopy, indicated that macrophages and spermatogonial cells are the main SARS-CoV-2 lodging sites, where new virions form inside the endoplasmic reticulum Golgi intermediate complex. Moreover, we showed infiltrative infected monocytes migrating into the testicular parenchyma. SARS-CoV-2 maintains its replicative and infective abilities long after the patient's infection. Further, we demonstrated high levels of angiotensin II and activated immune cells in the testes of deceased patients. The infected testes show thickening of the tunica propria, germ cell apoptosis, Sertoli cell barrier loss, evident hemorrhage, angiogenesis, Leydig cell inhibition, inflammation, and fibrosis.
Our findings indicate that high angiotensin II levels and activation of mast cells and macrophages may be critical for testicular pathogenesis. Importantly, our findings suggest that patients who become critically ill may exhibit severe alterations and harbor the active virus in the testes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
