Orbital: The Electronic Journal of Chemistry

Fluorescence Spectroscopy and Silica Gel Applied as a Tool for Capture and Detection of Compressor Lubricant Oils

Claudio Yamamoto Morassuti — 2023-04-05

Here, we report the use of fluorescence spectroscopy for the identification of lubricant oils used in reciprocating compressors, and the use of silica gel as an adsorbent to capture lubricant oil vapors. The silica gel was tested for adsorption of lubricant oil vapors, by heating the samples at 200°C, the emission spectrum of the lubricant oils is observed on the silica gel layer, over 20 min of heating. The spectrum of the lubricant oils over the silica gel layer presents a redshift, an indication of the degradation effect. In order to investigate this effect on the optical properties, we conducted an experiment by heating the samples at (130 ± 4) °C, and collected at different times. The MID-infrared absorption of the samples presents bands of oxygen-containing groups at 1010 and 1050 cm^-1, and NIR infrared absorption measurements at 3444 cm^-1 show an increase in the hydroperoxide band during the degradation time. These two results indicate that the oxidation process is associated with the observed redshift of the absorption and emission bands in lubricant oils and over the adsorbent layer.

Spectral Voltage Contour Plots of Optical Constants and Interface Parameters of the Active Layer of a Multilayer Structure Suspended Particle Device Smart Window from Clear on to Dark off States

David Barrios — 2023-04-05

Smart windows based on suspended particle devices (SPDs) are able to switch optically from dark to clear visual appearance when applying an AC electrical signal. This effect is due to light absorbing nanoparticles that get aligned by the applied voltage. The sandwich structure of an SPD consists of several layers and includes two outer glass substrates, each one covered on its inwards-facing side with a transparent conducting thin layer surrounding the centrally positioned SPD active layer. A knowledge of the optical constants of each layer—i.e., the complex refractive index, including its real and imaginary (absorption) parts—is a key in the design of the visual appearance of the SPD window and is a useful tool to determine the optimum thickness of the active layer.

Cytotoxic Activity of Baccharis trimera (Less.) DC. Essential Oil in Tumor Cell Lines and its Role in Associated Death Mechanisms

Isabela Jacob Moro — 2023-04-06

This study evaluated the potential of Baccharis trimera essential oil (EO) and its components in cancer therapy through the application of cytotoxicity and cell death assays. Using gas chromatography analysis, the major components of the aerial parts of the essential oil were identified as (E)-caryophyllene (18.9%), bicyclogermacrene (15.6%), and germacrene D (10.5%). Baccharis trimera essential oil (5.8 μg/mL) and α-humulene (7.8 μg/mL) presented strong cytotoxic activity, while (E)-caryophyllene (11.5 μg/mL) and caryophyllene oxide (> 100.0 μg/mL) showed moderate and low activities, respectively, against MCF-7 cell lines. Against HepG2 cell lines, B. trimera essential oil (10.4 μg/mL), α-humulene (17.1 μg/mL), and caryophyllene oxide (19.4 μg/mL) exhibited moderate activity, while (E)-caryophyllene (52.3 μg/mL) displayed low activity against HepG2 cell lines. The selectivity index values of EO (MCF-7 and HepG2), α-humulene and (E)-caryophyllene (MCF-7), and caryophyllene oxide (HepG2) were found between 1.1 and 2.8, compared with MCF-10A cells. The annexin-V and Hoechst / propidium iodide assays performed with essential oil, (E)-caryophyllene, α-humulene, and caryophyllene oxide showed apoptosis and necrosis mechanisms for all cell lines. Based on these findings, B. trimera essential oil and its components can be considered as potential therapeutic agents against cancer.

The Theoretical Description for Psilocin Electrochemical Determination over Cobalt Oxyhydroxide

Volodymyr Tkach — 2023-04-06

The possibility of psilocin electrochemical determination over cobalt (III) oxyhydroxide-modified anode is evaluated from the mathematical point of view. Psilocin is thereby oxidized yielding either micro- or macromolecular product, being both of them important for the economical and green conducting polymer composite for electrocatalysis, electroanalysis and energy conversion. The analysis of the correspondent mathematical model confirms, that, despite of the high probability of the oscillatory behavior, the electrochemical process is efficient from both analytical and synthetical point of view.

Optimization of Hydrophobic Coating Production by Pechini Method on Modified Aluminum Surface

Ariane Aparecida de Lima — 2023-04-12

To fabricate a hydrophobic coating using the sol-gel method (Pechini), an experimental design using the drying time and chemicals ratio as variables was developed. The coating was deposited on an aluminum substrate (AA6061-T6) treated by acid solution or anodization method. The surface wettability was measured using a goniometric instrument. Coatings were fabricated using different numbers of layers, heating rates, and drying temperatures, and their morphologies were observed using visual analysis and scanning electron microscopy. The use of anodization treatment with a furnace ramp of 1 °C min^-1, a drying temperature of 220 °C ± 10 °C, and single-layer application, produced a coating free of visible flaws and apparent damage. The coating was obtained with a 15:1 glycerin:citric acid ratio and sample pre-polymerization in the drying oven for 1 hour at 100 °C resulted in the highest contact angle, 62° ± 2°, which meets the ASTM D-7334-08 standard for a hydrophobic surface.

Advancement of Novel Graphene Oxide Embedded Alumina Nickel Composite Coating Developed at Various Current Densities to Evaluate Corrosion Resistance

Usha Pandey — 2023-04-12

In this research, the influence of deposition current density on the properties of nickel-Graphene oxide/alumina coatings produced by electrodeposition was examined. Nickel matrix composite coatings with graphene oxide doped Alumina (GO-Al₂O₃) particles were prepared via electrodeposition. When embedding GO-Al₂O₃ particles in the Ni matrix, remarkable anti-corrosion properties are anticipated due to the outstanding mechanical properties of GO and Al₂O₃. The structure, content, and morphology of GO, GO-Al₂O_3,and coatings deposited at various current densities were determined using X-ray diffraction, Fourier transforms infrared spectroscopy, Field emission Scanning electron microscopy, and energy-dispersive X-ray spectroscopy. GO-doped alumina particles were successfully incorporated into the matrix of nickel, according to the findings. Porosity measurement and cross-sectional thickness were also investigated at various current densities. Potentiodynamic polarization testing and electrochemical impedance spectroscopy were used to study the coatings' corrosion-resistant characteristics. According to the findings, coatings developed at high current densities, such as 30 mA cm^-2, are porous and not uniform in nature. Furthermore, at high current densities, the content of GO and Alumina is reduced, resulting in a decrease in mechanical and corrosion resistance. Due to its less porous and uniformly formed coating, 10 mA cm^-2 was the optimum current density for achieving the most desirable features.

Investigation of Neolamarckia cadamba Phytoconstituents Against SARS-CoV-2 3CL Pro: An In-Silico Approach

Sumit Arora — 2023-04-12

In present study, the inhibitory potential of Neolamarckia cadamba phytoconstituents was investigated against SARS-CoV-2 3CL protease (3CL pro) (PDB ID: 6M2N). Molecular docking was analyzed using AutoDock Vina software by setting the grid parameter as X= -33.163, Y= -65.074 and Z= 41.434 with dimensions of the grid box 25 × 25 × 25 Å. Remdesivir was taken as the standard for comparative analysis along with inhibitor 5, 6, 7-trihydroxy-2-phenyl-4H-chromen-4-one. Furthermore, the exploration of 2 D Hydrogen-bond interactions was performed by Biovia Discovery Studio 4.5 program to identify the interactions between an amino acid of target and ligand followed by assessment of physicochemical properties using Lipinski’s rule and Swiss ADME database. The decent bonding scores of secondary metabolites owing to hydrogen bonding with catalytic residues suggest the effectiveness of these phytochemicals towards 3CLpro. The results are further consolidated positively by Lipinski’s rule and Swiss ADME prediction. Thus reasonably, observations with docking studies suggest possibility of phytochemicals from Neolamarckia cadamba to inhibit the 3CLpro and consequently would be explored further as agents for preventing COVID-19.

A Subjective Study on the Effects of Dynamic Virtual Chemistry Laboratory in a Secondary School Education

Numan Ali — 2023-04-13

Virtual chemistry laboratories (VCLs) are the alternative solutions of the physical laboratories, where students can virtually conduct their experiments with a lower cost, and in an efficient and safer way. Considering the importance of technology-enhanced learning and that of the experimental study, several VCLs have been proposed. However, the existing VCLs are static and only provide the simulation of pre-defined experiments, procedures, or safety procedures and cannot be adapted according to the students’ level or new experimental tasks. In this paper, we proposed a dynamic virtual chemistry lab (DVCL) where instructors or experts are allowed to add a new chemical experiment by adding its apparatus, chemicals, glassware, and mechanism or add something new to its properties. We conducted a subjective study with field experts to investigate the effect of proposed DVCL in secondary school chemistry education. During evaluation, twenty-seven field experts were participated and evaluated the proposed DVCL with system usability scale (SUS)-questionnaire and by a simple questionnaire. The results showed that the proposed DVCL is very helpful for students’ performance and mental modeling and also for effortlessly uplifting their knowledge for hands-on experiments.

Chemistry of Pre-exposure Prophylaxis (PrEP) and Brazil’s Protagonism in the Fight Against HIV/AIDS: Exploring the Theme with High School Seniors

Mateus Ladeira — 2023-04-13

The Pre-exposure Prophylaxis (PrEP) for the prevention of human immunodeficiency virus (HIV) infection consists in using antiretroviral medicine before sexual exposure to the virus to decrease probability of infection. The PrEP is capable of preventing the virus infection and promoting a healthier sexual life. Brazil has been a reference in HIV treatment not only because it was the first country in Latin America to offer free antiretroviral treatment to virus carriers but also because it participated in the Initiative in Pre-exposure Prophylaxis (iPrEP), a study that was carried out in several countries worldwide and proved effectiveness of the PrEP. Medication distributed by the Brazilian Public Health System (SUS) is quite unknown to the population. To mitigate current proliferation of sexually transmitted diseases (STDs) and increase in pregnancy cases among adolescents, sexual orientation has been intensified in schools and, thus, it has also become their responsibility, rather than parents’ responsibility alone. Therefore, this study aimed at carrying out dynamic and dialogic interventions about the PrEP in classes taught to High School seniors who attend technical courses in Commerce and in Development of Digital Games at the Instituto Federal do Triângulo Mineiro - Campus Uberlândia Centro, Uberlândia, Minas Gerais (MG), Brazil. A dialogical Chemistry class was taught to show students several images and chemical structures of active ingredients found in the medication (PrEP). Besides, students answered a questionnaire with open questions anonymously to evaluate the effect of the class on their learning about sexual education, HIV/AIDS and, mainly, the PrEP. Students showed much interest in the tasks and interacted positively. Results of the questionnaire enabled to observe students’ increase in knowledge about the PrEP. In sum, this study enabled the PrEP to be better disseminated, since doubts were mitigated.