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  • Open access
  • 50 Reads
Autonomous Movement of Wheelchair by Cameras and YOLOv7

A wheelchair can provide limited but crucial mobility to an injured or disabled individual. This paper presents the first stage of the development of a smart wheelchair which is the customization of a manually controlled wheelchair with a novel implementation of octascopic vision. This relatively inexpensive design of an autonomous wheelchair consists of two monochromic camera arrays (each having four cameras) placed around the frame of the wheelchair to achieve a view of ~360 degrees. The initial research goal was to design a wheelchair controlled by the embedded processor, allowing the wheelchair to navigate autonomously around an indoor facility with and without human intervention. Also, it was intended to allow those previously denied access to the world of automatic wheelchairs because of a low personal income. Our developed wheelchair cost only 1350$. Through the testing of wheelchair functionality, a) a large dataset of octascopic images was captured from this wheelchair, and b) a Yolov7-based object detection model was developed to avoid obstacles and autonomously control the movement. This paper presents the completed wheelchair hardware and the obstacle detection model using octascopic images. All the project design files have been granted an open-source license and can be reproduced publicly.

  • Open access
  • 20 Reads
Sensitive voltammetric sensor for thymol and carvacrol based on the electropolymerized thymolphtalein

Thymol and carvacrol (isopropylmethylphenols) are phenolic monoterpenoids with antibacterial, antifungal, insecticidal, and antioxidant properties. Thyme, oregano, and other culinary and medicinal herbs are their natural sources. The dose-dependent antioxidant effect of isopropylmethylphenols requires their control in real samples. The presence of phenolic hydroxyl group in the thymol and carvacrol structures makes them electroactive at the electrode surface allowing application of voltammetry for their quantification. Glassy carbon electrode modified with multi-walled carbon nanotubes and electropolymerized thymolphthalein has been developed for this purpose. Conditions of thymolphthalein electropolymerization (monomer concentration, number of cycles, parameters of electrolysis) providing the best response to thymol have been found. Scanning electron microscopy and electrochemical methods confirm the effectivity of the sensor developed. According to voltammetric data, both thymol and carvacrol are irreversibly oxidized at almost the same potential with the participation of two electrons and two protons forming thymoquinone. In differential pulse mode, the sensor gives a linear response in the ranges of 0.050-25 and 25-100 µM for thymol and 0.10-10 and 10-100 µM for carvacrol with detection limits of 0.037 and 0.063 µM, respectively that is significantly improved compared to reported earlier. Sensor developed is selective to isopropylmethylphenols in the presence of typical interferences (inorganic ions, saccharides, ascorbic acid) and other phenolics (caffeic, chlorogenic, gallic and rosmarinic acids, quercetin, and rutin). Sensor has been applied for the evaluation of total isopropylmethylphenols in oregano and thyme spices using single sonication assisted extraction with methanol. Voltammetric sensor data agree well with the independent spectrophotometric quantification.

  • Open access
  • 18 Reads
MIP-based screen-printed electrode for Irbesartan sensing
Published: 09 December 2022 by MDPI in 3rd International Electronic Conference on Applied Sciences session Student Session

This work aimed to develop a voltammetric method for Irbesartan detection.

Irbesartan is a drug prescribed to treat hypertension and high blood pressure. Recent studies associated sartans with several forms of cancer, making removing this class of substances from the environment a high priority. The EU has categorized drugs as emerging pollutants, and they can be more potent than other substances because they were designed to operate at low concentrations. Thus, effective and sensitive methods to determine irbesartan selectively and accurately in environmental samples are necessary. MIPs have already been used to remove pollutants from complex matrixes, so they were also chosen for this work. In particular, MIP-polyacrylate was used to functionalize the graphite working electrode of screen-printed cells (SPCs), aiming to develop a voltammetric method for Irbesartan sensing. The MIP’s prepolymeric mixture was drop coated on the working electrode, and polymerization was carried out in an oven at 70°C overnight. The electrochemical technique used to quantify Irbesartan is the square wave voltammetry (SWV); the experiments were carried out in acetate buffer at pH 5.5. The calibration curve was obtained by plotting current intensity (μA) versus Irbesartan concentration only after determining the best parameters with an Experimental Design. The procedure was replicated with different SPCs obtaining similar results, highlighting good reproducibility. The MIP-based electrodes were also applied to determine Irbesartan in fortified tap water samples, obtaining high recovery percentages. Since the good results, the electrochemical methods based on MIP-functionalized screen-printed electrodes are promising for quantifying Irbesartan at a trace level.

  • Open access
  • 26 Reads
Electrode modified with manganese dioxide nanorods for the simultaneous voltammetric determination of food colorants

Synthetic colorants in particular tartrazine and brilliant blue FCF are widely used in food chemistry and technology although can give negative health effects of various severities. Moreover, brilliant blue FCF application is restricted in many countries. Therefore, sensitive and selective as well as simple and reliable methods for the quantification of these dyes are required. Voltammetric sensors suits well for such purposes. Glassy carbon electrode modified with manganese dioxide nanorods dispersed in cationic surfactant cetylpyridinium bromide gives a sensitive response to tartrazine and brilliant blue FCF in mixtures. Electrode modification provides 7.9-fold increase of the electroactive surface area as well as 72-fold decrease of electron transfer resistance i.e. improvement of the electron transfer rate. Simultaneous voltammetric quantification of colorants has been performed in phosphate buffer pH 7.0 in differential pulse mode. The linear dynamic ranges of 0.10-2.5 and 2.5-15 µM of tartrazine and 0.25-2.5 and 2.5-15 µM of brilliant blue FCF have been obtained with the limits of detection 43 and 41 nM, respectively. Dyes electrooxidation in the first linear range proceeds independently. The advantage of the sensor developed is the high selectivity of response in the presence of typical interferences (inorganic ions, saccharides, ascorbic and sorbic acids) and other food colorants (riboflavin, indigo carmine, sunset yellow). The practical applicability of the approach is shown on the soft and isotonic sports drinks and is validated by comparison to chromatography. Novel sensitive and selective voltammetric method is simple, express, reliable, cost-effective and can be applied for the beverages control.

  • Open access
  • 27 Reads
Synthesis of doped sol-gel glasses as adsorbents for water treatment.

Doped sol-gel glasses of thiourea (THU), urea (U), n-propoylamine (PA), iso-propylamine (IPA), o-anisidine (AN) and o-aminophenol (AP) were prepared and treated by two methods, thermal and microwave (MW) irradiation. The optical properties and particle size of the as-synthesized doped sol-gels and plain sol-gel (P) were measured, and their characteristic Fourier Infrared Radiation (FTIR) spectra were analyzed. The sol-gels were then tested for their capacity to adsorb methylene blue dye (MB) and remove it from aqueous solutions. The highest removal efficiencies were exhibited by PA, IPA and THU that were prepared by either the thermal or MW method. Amongst all the tested adsorbents, the thermally-prepared PA yielded the highest removal of over 95% for 6.5 mg/L of MB, and about 75% for 12.5 mg/L of MB. The MW-prepared PA showed the second highest removal efficiencies. IPA, prepared thermally or by MW, showed comparable results to its PA counterpart. This behavior could be attributed to the higher basicity of aliphatic amines relative to aromatic amines, which resulted in increased interaction between the lone pair of electrons on amino nitrogen and MB. On the other hand, the interaction between U or THU, and MB is suggested to have possibly occurred via electrostatic attraction or redox reaction between them.

  • Open access
  • 46 Reads
On the role of Leaf Area Index parameterization in simulating the terrestrial carbon fluxes of Africa using a regional coupled climate-vegetation model

In this study, the Regional Climate Model version 4 (RegCM4) coupled with the Community Land Model version 4.5 (CLM45) including a module of carbon–nitrogen cycling (CN) (RegCM4-CLM45-CN) is used to examine the sensitivity of the terrestrial carbon fluxes of Africa to leaf area index (LAI) parameterization. Two LAI formulas were implemented in CLM45-CN. The new LAI formula is based on a modified BioGeochemical Cycles (BIOME-BGC) ecosystem model. The two simulations were designated as LAIorg and LAImod, respectively and they both shared the same initial and lateral boundary conditions and they were evaluated concerning reanalysis products and FLUXNET measurements. In LAIorg, the above-ground terrestrial carbon fluxes were overestimated to the reanalysis products, which were also noted for the below-ground terrestrial fluxes. On the other-hand in LAImod, terrestrial carbon fluxes were notably decreased relative to LAIorg and the model bias was reduced. For in-situ observation, LAImod was better matched to the observation than LAIorg although both were limited in capturing the observed magnitude and seasonality of gross primary production (GPP) to some extent. In conclusion, switching between the two formulas has a substantial effect on the simulated terrestrial carbon fluxes. Despite noted biases, the regional coupled RegCM4-CLM4-CN-LAImod model can be recommended for future studies to investigate influence of climate change on the terrestrial carbon fluxes of Africa.

  • Open access
  • 35 Reads
Comparison of band structures of ErSb and ErNiSb intermetallics from ab initio calculations

RNiSb intermetallics are composed of R - rare earth, T - transition metals, and X - p elements. This family of compounds demonstrates many outstanding properties and phenomena perspective in functional applications. The intermetallic compounds are crystalized in the cubic half-Heusler structure (space group F-43m). Similar binary RSb compounds with the same crystal structure are topological semimetals with unusual Dirac-cone-like states observed in ARPES studies. In this work, the band structure and magnetic properties of ErSb and ErNiSb compounds are investigated in the framework of the DFT+U method comprising density functional theory and correction for strong electron correlations in Er 4f shell. The calculated magnetic properties of both alloys obtained to be solely caused by the magnetic moments of the Er ions and provide a good agreement with the experimental data. ErSb has the band structure of a topological semimetal. A narrow energy gap was found in the band structure of ErNiSb, i.e., this alloy is an indirect gap semiconductor. The energy gap in ErNiSb was calculated to be 0.25 eV due to the minority spin projection. The band structure exhibits the presence of occupied bands which can form a hole pocket near Γ in the L-Γ-X and K-Γ directions. In the band structure of ErSb, one can find the hole pockets near the same k-point along L-Γ-X, K-Γ and an electron pocket along Γ-X-W. These bands form topological features in ErSb, in particular, cause a semimetallic state. This study was supported by Russian Science Foundation, Project No. 22-42-02021.

  • Open access
  • 32 Reads
Multicriteria Model for Organizational Green Information Technology Maturity Assessment and Benchmarking: Defining a Class Structure

Assessing Green Information Technology (IT) maturity in organizations is a relevant process to measure the progress of sustainable IT initiatives and to support new actions to improve them. Knowledge about the organizational maturity level in Green IT and comparing this level with those of other companies are necessary for self-assessment to strengthen organizations' general sustainability strategy. The main objective of this paper is to communicate a Green IT maturity assessment model with its class structure. This model can also provide benchmarking regarding organizations' maturity since its fundamental premise is a pairwise comparison between companies to obtain their classification. Based on a literature search to identify the existing maturity models, the CMMI model was selected since it is the most recurrent in the literature on managing organizational Green IT actions. The classification process using CMMI maturity levels as classes is based on the ELECTRE IV multicriteria decision support method, which was developed to work specifically with classification problems. The results include the companies' allocation into the most appropriate classes, considering well-defined criteria set with their weights, the class boundaries according to numerical parameters such as lower and upper limits for each of them, and data collected with companies under consideration for the assessment.

  • Open access
  • 22 Reads
Comprehensive List of Topics Describing the IoT Ecosystem
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Internet of things (IoT) is a complex ecosystem of connected devices that exchange data over a network and whose final aim is to provide services. The total number of installed connected devices is expected to grow exponentially in the near future. Analogously, the number of IoT-related studies published every year is constantly increasing. This huge knowledge asset has generated a fragmented picture about IoT systems, their basic constituents, their qualities, and in some cases even inconsistent terminologies and definitions.
This paper aims at providing a holistic view of the topics characterizing the IoT ecosystem by taking into account a technology perspective and a business one; then a definition of IoT ecosystem is given.

  • Open access
  • 25 Reads
Characterization of the essential oils antioxidant properties by coulometric titration

Essential oils are known from ancient times and used in aromatherapy. Nowadays, their application area also covers medicine and food industry due to a wide spectrum of bioactivity including antioxidant properties. Thus, estimation of the essential oils antioxidant properties is of practical interest. Phenolic compounds and terpenes are the major antioxidants according to gas chromatography-mass spectrometry (GC-MS). Total antioxidant parameters are a good alternative to the characterization of individual components by GC-MS allowing to avoid a time-consuming and expensive procedure. Coulometric titration with electrogenerated bromine and ferricyanide ions has been used for the estimation of total antioxidant capacity and ferric reducing power of essential oils for the first time. Data for the reaction of individual antioxidants (volatile phenolics and terpenes) with coulometric titrants confirm applicability of the method for characterization of the essential oils antioxidant properties. Essential oils of clove, cinnamon, nutmeg, lavender, ginger, anise, basil, bergamot, jasmine, ylang-ylang, marjoram, neroli, rosemary, thyme, and clary sage of various trademarks (total 27 samples) are investigated. The data are compared to the standard parameters (antioxidant activity towards 2,2-diphenyl-1-picrylhydrazyl and total phenolic contents). Positive correlations with coefficients of 0.7051-0.9558 confirm the accuracy of the coulometric approach. Moreover, ferric reducing power reflecting phenolic antioxidant content can be used for all samples of essential oils, while Folin-Ciocalteu method for total phenolic contents is applicable to four essential oils only. Another advantage of coulometry titration is the possibility of automation and rapidity making it an attractive tool for screening purposes in routine practice.