Influence of pH in the synthesis of ferric tannate pigment for application in antifouling coatings

Ferric tannate was synthesized at pH 4 and pH 7 (FT4 and FT7, respectively) as a new class of environmentally friendly antifouling pigments. The solubility of both pigments was evaluated by gravimetric tests, showing that FT4 is more soluble than FT7. A mixture of rosin/acrylic resin (9:1 w/w) was sufficient to form an antifouling coating due to improved matrix properties. Electrochemical impedance spectroscopy (EIS) measurements were used to determine the apparent water coefficient of diffusion (D) and coating behavior. The D in the coating formulated with FT4 exhibited better values than that obtained with FT7. EIS results showed that both coatings present Fickian behavior at the initial stages of immersion, while flat Nyquist plots revealed penetration of water in the films. The physicochemical characteristics of FT4 pigment were determined by thermogravimetry and Fourier transform infrared. Immersion tests in the Mediterranean Sea demonstrated the excellent efficacy of the FT4-containing coating against marine fouling after six months of immersion.     

Mapping of hydrothermally altered rocks by the EO‐1 Hyperion sensor,Northern Danakil Depression,Eritrea

An EO‐1 Hyperion scene was used to identify and map hydrothermally altered rocks and a Precambrian metamorphic sequence at and around the Alid volcanic dome, at the northern Danakil Depression, Eritrea. Mapping was coupled with laboratory analyses, including reflectance measurements, X‐ray diffraction, and petrographic examination of selected rock samples. Thematic maps were compiled from the dataset, which was carefully pre‐processed to evaluate and to correct interferences in the data. Despite the difficulties, lithological mapping using narrow spectral bands proved possible. A spectral signature attributed to ammonium was detected in the laboratory measurements of hydrothermally altered rocks from Alid. This was expressed as spectral absorption clues in the atmospherically corrected cube, at the known hydrothermally altered areas. The existence of ammonium in hydrothermally altered rocks within the Alid dome has been confirmed by previous studies. Spectral information of endmember's mineralogy found in the area (e.g. dolomite) enables a surface mineral map to be produced that stands in good agreement with the known geology along the overpass. These maps are the first hyperspectral overview of the surface mineralogy in this arid terrain and may be used as a base for future studies of remote areas such as the Danakil.     

Supercritical Carbon Dioxide and Microwave-Assisted Extraction of Functional Lipophilic Compounds from Arthrospira platensis

Arthrospira platensis biomass was used in order to obtain functional lipophilic compounds through green extraction technologies such as supercritical carbon dioxide fluid extraction (SFE) and microwave-assisted extraction (MAE). The temperature (T) factor was evaluated for MAE, while for SFE, pressure (P), temperature (T), and co-solvent (ethanol) (CS) were evaluated. The maximum extraction yield of the obtained oleoresin was (4.07% ± 0.14%) and (4.27% ± 0.10%) for SFE and MAE, respectively. Extracts were characterized by gas chromatography mass spectrometry (GC-MS) and gas chromatography flame ionization detector (GC-FID). The maximum contents of functional lipophilic compounds in the SFE and MAE extracts were: for carotenoids 283 ± 0.10 μg/g and 629 ± 0.13 μg/g, respectively; for tocopherols 5.01 ± 0.05 μg/g and 2.46 ± 0.09 μg/g, respectively; and for fatty acids 34.76 ± 0.08 mg/g and 15.88 ± 0.06 mg/g, respectively. In conclusion, the SFE process at P 450 bar, T 60 °C and CS 53.33% of CO₂ produced the highest yield of tocopherols, carotenoids and fatty acids. The MAE process at 400 W and 50 °C gives the best extracts in terms of tocopherols and carotenoids. For yield and fatty acids, the MAE process at 400 W and 70 °C produced the highest values. Both SFE and MAE showed to be suitable green extraction technologies for obtaining functional lipophilic compounds from Arthrospira platensis.     

Polyaniline coated hematite sand supported on graphene oxide (HS@PANI-GO) as a new magnetic material for advanced catalytic oxidation based on sulfate radicals: optimization using response surface methodology

The cover image is based on the Research Article Polyaniline coated hematite sand supported on graphene oxide (HS@PANI-GO) as a new magnetic material for advanced catalytic oxidation based on sulfate radicals: optimization using response surface methodology by Abdellah Ait El Fakir et al., DOI: 10.1002/jctb.6070 .

     

Thermal and mechanical properties of UHMWPE/HDPE/PCL and bioglass filler: Effect of polycaprolactone

Polymeric composites based on polyethylene, high-density polyethylene (HDPE) and ultra-high-molecular-weight polyethylene (UHMWPE) with polycaprolactone (PCL) and a ceramic filler (bioglass type) were studied in terms of their thermal and mechanical behavior. Two polyethylene ratios (10/90 and 30/70% wt/wt of UHMWPE/HDPE) and two PCL content ratios (5% and 10% wt/wt) were used. The obtained composites were characterized by differential scanning calorimetry, melt flow index, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The results indicate a nonchemical interaction between polyethylene, especially the UHMWPE, and PCL and that the composites' thermal transitions vary from the parent polymers and depend on the PCL concentration. The PCL's melting temperature in the composite was reduced, showing a new one. Also, the melting enthalpy of polyethylene was reduced when the concentration of PCL increased. The mechanical behavior depends on both the polyethylene ratio and the PCL content. The composite with 30% wt/wt of UHMWPE and 10% wt/wt of PCL showed the highest toughness value due to the good interaction between polymers. These new composites may be attractive for biomedical applications and could be evaluated, for example, as materials for prostheses.     

Two-objective metaheuristic optimization for floating gate transistor-based CMOS-MEMS inertial sensors

Microsystem Technologies - In this work, a study case is presented in which the design of the layout for a CMOS sensor cell is partially automated by implementing a metaheuristic algorithm to find...     

Characterization of Ti6Al4V–Ti6Al4V/30Ta Bilayer Components Processed by Powder Metallurgy for Biomedical Applications

Metals and Materials International - The design and fabrication of a bilayer Ti6Al4V–Ti6Al4V/30Ta component were performed by using the powder metallurgy process and solid-state sintering as...     

Harnessing the Power of the De Mayo Reaction: Unveiling a Photochemical and Photocatalytic Masked [2+2] Methodology for Organic Synthesis

In 1962, Paul J. de Mayo initially described the photochemical reaction involving 1,3-diketones and double bonds, resulting in the formation of 1,5-diketones. Since then, this reaction has been extensively utilized for the synthesis of a wide range of fascinating natural products. Over time, this synthetic methodology has been applied to various carbonyl systems, including locked enol-tautomers of diketones, β-keto esters, and β-enaminones. Additionally, it has found application in other unsaturated systems such as allenes and alkynes. In this review article, we provide a comprehensive overview of the classical de Mayo reaction, highlighting its scope and potential. Furthermore, we focus on recent advances achieved through photocatalytic conditions. Special emphasis is placed on the regioselectivity of the process and the underlying reaction mechanism, particularly within the context of photocatalysis.     

Electroactive polymers for the detection of morphine

The interaction between morphine (MO), a very potent analgesic psychoactive drug, and five electroactive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-methylthiophene) (P3MT), polypyrrole (PPy), poly(N-methylpyrrole (PNMPy) and poly[N-(2-cyanoethyl)pyrrole] (PNCPy), has been examined using theoretical calculations on model complexes and voltammetric measures considering different pHs and incubation times. Quantum mechanical calculations in model polymers predict that the strength of the binding between the different polymers and morphine increases as follows: PEDOT < PNMPy < Py < < P3MT ≈ PNCPy. The most relevant characteristic of P3MT is its ability to interact with morphine exclusively through non-directional interactions. On the other hand, the variations of the electroactivity and the anodic current at the reversal potential evidence that the voltammetric response towards the presence of MO is considerably higher for P3MT and PNCPy than that for the other polymers at both acid (P3MT > PNMPy) and neutral (P3MT ≈ PNCPy) pHs. Energy decomposition analyses of the interaction of MO with different model polymers indicate that the stronger affinity of MO for P3MT and PNCPy as compared to PEDOT, PNMPy, and PPy is due to more favorable orbital interactions. These more stabilizing orbital interactions are the result of the larger charge transfer from MO to P3MT and PNCPy model polymers that takes place because of the higher stability of the single occupied molecular orbital (SOMO) of these model polymers. Therefore, to design polymers with a large capacity to detect MO we suggest looking at polymers with high electron affinity.