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12 pages, 4632 KiB

Open AccessArticle

Fabrication of Automated Hydrostatic Pressure-Based Densitometer with a Calibrated Pressure Sensor

by D. N. P. Ruwan Jayakantha, Kelum A. A. Gamage, Navaratne Bandara, Migara Karunarathne, Madushani Seneviratne, Elisabetta Comini, Dario Zappa and Nanda Gunawardhana

Sci 2024, 6(3), 41; https://doi.org/10.3390/sci6030041 - 18 Jul 2024

Cited by 1 | Viewed by 1987

Abstract

An automated device is designed to measure the density of a liquid material using hydrostatic pressure method. A low cost pressure sensor is calibrated and used to get highly accurate readings. The calibration is done by measuring the pressure values vs. the generated [...] Read more.

An automated device is designed to measure the density of a liquid material using hydrostatic pressure method. A low cost pressure sensor is calibrated and used to get highly accurate readings. The calibration is done by measuring the pressure values vs. the generated voltage signal. The calibration has been challenging due to the low accuracy of the sensor but proved to be highly effective in applications. The interface is developed using a microcontroller, motor drives, analog to digital converters and sensors. The device is designed to get several readings automatically by changing the positions of the device/liquid column heights to increase the accuracy. Also the device can be programmed to measure the real time density of a liquid continuously. The readings were analyzed and averaged by a software developed in python language. The instruments accuracy was tested against 3 liquid types, water, coconut oil, kerosene oil, and showed a low error (0.007%, 0.001%, and 0.002% respectively) compared to the readings of a standard Pycnometer. The low error percentages confirm the accuracy of the device and the effectiveness of the sensor calibrations. Full article

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11 pages, 3054 KiB

Open AccessArticle

Nb₂O₅ Microcolumns for Ethanol Sensing

by Gayan W. C. Kumarage, Shasika A. Panamaldeniya, Valentin A. Maraloiu, Buddhika S. Dassanayake, Nanda Gunawardhana and Elisabetta Comini

Sensors 2024, 24(6), 1851; https://doi.org/10.3390/s24061851 - 14 Mar 2024

Cited by 1 | Viewed by 1586

Abstract

Pseudohexagonal Nb₂O₅ microcolumns spanning a size range of 50 to 610 nm were synthesized utilizing a cost-effective hydrothermal process (maintained at 180 °C for 30 min), followed by a subsequent calcination step at 500 °C for 3 h. Raman spectroscopy [...] Read more.

Pseudohexagonal Nb₂O₅ microcolumns spanning a size range of 50 to 610 nm were synthesized utilizing a cost-effective hydrothermal process (maintained at 180 °C for 30 min), followed by a subsequent calcination step at 500 °C for 3 h. Raman spectroscopy analysis unveiled three distinct reflection peaks at 220.04 cm⁻¹, 602.01 cm⁻¹, and 735.3 cm⁻¹, indicative of the pseudohexagonal crystal lattice of Nb₂O₅. The HRTEM characterization confirmed the inter-lattice distance of 1.8 Å for the 110 plain and 3.17 Å for the 100 plain. The conductometry sensors were fabricated by drop-casting a dispersion of Nb₂O₅ microcolumns, in ethanol, on Pt electrodes. The fabricated sensors exhibited excellent selectivity in detecting C₂H₅OH (ΔG/G = 2.51 for 10 ppm C₂H₅OH) when compared to a variety of tested gases, including CO, CO₂, NO₂, H₂, H₂S, and C₃H₆O. The optimal operating temperature for this selective detection was determined to be 500 °C in a dry air environment. Moreover, the sensors demonstrated exceptional repeatability over the course of three testing cycles and displayed strong humidity resistance, even when exposed to 90% relative humidity. This excellent humidity resistance gas sensing property can be attributed to their nanoporous nature and elevated operating temperature. Full article

(This article belongs to the Special Issue New Advances and Applications in Environmental Electrochemical Gas Sensors)

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15 pages, 6575 KiB

Open AccessArticle

Synthesis of TiO₂-(B) Nanobelts for Acetone Sensing

by Gayan W. C. Kumarage, Shasika A. Panamaldeniya, Dileepa C. Maddumage, Abderrahim Moumen, Valentin A. Maraloiu, Catalina G. Mihalcea, Raluca F. Negrea, Buddhika S. Dassanayake, Nanda Gunawardhana, Dario Zappa, Vardan Galstyan and Elisabetta Comini

Sensors 2023, 23(19), 8322; https://doi.org/10.3390/s23198322 - 8 Oct 2023

Cited by 4 | Viewed by 2699

Abstract

Titanium dioxide nanobelts were prepared via the alkali-hydrothermal method for application in chemical gas sensing. The formation process of TiO₂-(B) nanobelts and their sensing properties were investigated in detail. FE-SEM was used to study the surface of the obtained structures. The [...] Read more.

Titanium dioxide nanobelts were prepared via the alkali-hydrothermal method for application in chemical gas sensing. The formation process of TiO₂-(B) nanobelts and their sensing properties were investigated in detail. FE-SEM was used to study the surface of the obtained structures. The TEM and XRD analyses show that the prepared TiO₂ nanobelts are in the monoclinic phase. Furthermore, TEM shows the formation of porous-like morphology due to crystal defects in the TiO₂-(B) nanobelts. The gas-sensing performance of the structure toward various concentrations of hydrogen, ethanol, acetone, nitrogen dioxide, and methane gases was studied at a temperature range between 100 and 500 °C. The fabricated sensor shows a high response toward acetone at a relatively low working temperature (150 °C), which is important for the development of low-power-consumption functional devices. Moreover, the obtained results indicate that monoclinic TiO₂-B is a promising material for applications in chemo-resistive gas detectors. Full article

(This article belongs to the Special Issue Chemical Sensors—Recent Advances and Future Challenges 2023–2024)

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14 pages, 379 KiB

Open AccessReview

Academic Standards and Quality Assurance: The Impact of COVID-19 on University Degree Programs

by Kelum A. A. Gamage, R. G. G. Roshan Pradeep, Vesna Najdanovic-Visak and Nanda Gunawardhana

Sustainability 2020, 12(23), 10032; https://doi.org/10.3390/su122310032 - 1 Dec 2020

Cited by 29 | Viewed by 8635

Abstract

COVID-19, caused by a member of the coronavirus family of viruses, has spread to most countries around the world since it was first recorded in humans in China in late 2019. Closing universities and cancelling all face-to-face activities have become a COVID-19 inevitable [...] Read more.

COVID-19, caused by a member of the coronavirus family of viruses, has spread to most countries around the world since it was first recorded in humans in China in late 2019. Closing universities and cancelling all face-to-face activities have become a COVID-19 inevitable reality in many parts of the world. Its impact on university programs, particularly to maintain academic standards and quality assurance procedures, has become significantly more challenging and complex. New ways of working digitally, to minimize disruption to daily operations, have also led to enormous anxiety and uncertainty within the student population, and meeting students’ expectations has also become significantly more difficult. This paper reviews actions taken by universities to safeguard high academic standards and quality assurance procedures during this time and appraise the challenges and impacts on students’ academic performance. Full article

(This article belongs to the Special Issue Effects of COVID 19 for Sustainable Education, Systems and Institutions)

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24 pages, 567 KiB

Open AccessEditor’s ChoiceArticle

Online Delivery and Assessment during COVID-19: Safeguarding Academic Integrity

by Kelum A.A. Gamage, Erandika K. de Silva and Nanda Gunawardhana

Educ. Sci. 2020, 10(11), 301; https://doi.org/10.3390/educsci10110301 - 25 Oct 2020

Cited by 195 | Viewed by 26277

Abstract

Globally, the number of COVID-19 cases continues to rise daily despite strict measures being adopted by many countries. Consequently, universities closed down to minimise the face-to-face contacts, and the majority of the universities are now conducting degree programmes through online delivery. Remote online [...] Read more.

Globally, the number of COVID-19 cases continues to rise daily despite strict measures being adopted by many countries. Consequently, universities closed down to minimise the face-to-face contacts, and the majority of the universities are now conducting degree programmes through online delivery. Remote online delivery and assessment are novel experiences for many universities, which presents many challenges, particularly when safeguarding academic integrity. For example, invigilated assessments, often considered as more secure, are not an option given the current situation and detecting any cheating would be significantly challenging. This paper reviews assessment security in the digital domain and critically evaluates the practices from different universities in safeguarding academic integrity, including associated challenges. Full article

(This article belongs to the Special Issue COVID-2019 Impacts on Education Systems and Future of Higher Education)

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9 pages, 201 KiB

Open AccessReview

Online Delivery of Teaching and Laboratory Practices: Continuity of University Programmes during COVID-19 Pandemic

by Kelum A. A. Gamage, Dilani I. Wijesuriya, Sakunthala Y. Ekanayake, Allan E. W. Rennie, Chris G. Lambert and Nanda Gunawardhana

Educ. Sci. 2020, 10(10), 291; https://doi.org/10.3390/educsci10100291 - 19 Oct 2020

Cited by 251 | Viewed by 26728

Abstract

A great number of universities worldwide are having their education interrupted, partially or fully, by the spread of the novel coronavirus (COVID-19). Consequently, an increasing number of universities have taken the steps necessary to transform their teaching, including laboratory workshops into an online [...] Read more.

A great number of universities worldwide are having their education interrupted, partially or fully, by the spread of the novel coronavirus (COVID-19). Consequently, an increasing number of universities have taken the steps necessary to transform their teaching, including laboratory workshops into an online or blended mode of delivery. Irrespective of the measures taken, universities must continue to maintain their high academic standards and provide a high-quality student experience as required for delivery of learning outcomes associated with each degree programme. This has created a challenge across the higher education landscape, where academics had to switch to remote teaching and different approaches to achieving laboratory delivery. As a result, students have not been receiving face-to-face teaching, and access to laboratory facilities has been limited or nearly impossible. This paper reviews numerous approaches taken by universities to deliver teaching and laboratory practices remotely, in consideration of the COVID-19 pandemic, whilst also considering the potential impacts on the student learning experience. This review is primarily focused on the fields of engineering, science and technology, based on published literature including books, reviewing web-based provision of selected universities, institutional and national policy documents. Full article

(This article belongs to the Special Issue COVID-2019 Impacts on Education Systems and Future of Higher Education)

15 pages, 6776 KiB

Open AccessArticle

Seed-Assisted Growth of TiO₂ Nanowires by Thermal Oxidation for Chemical Gas Sensing

by Hashitha M. M. Munasinghe Arachchige, Dario Zappa, Nicola Poli, Nanda Gunawardhana, Nuwan H. Attanayake and Elisabetta Comini

Nanomaterials 2020, 10(5), 935; https://doi.org/10.3390/nano10050935 - 13 May 2020

Cited by 17 | Viewed by 4033

Abstract

Herein, we report the catalyst assisted growth of TiO₂ one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic [...] Read more.

Herein, we report the catalyst assisted growth of TiO₂ one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic layer on the Ti metallic one. Thermal oxidation was carried out in an oxygen deficient environment. The optimal thermal growth temperature was 700 °C, in a mixture environment composed by Ar and O₂. As a comparison, Ti films were also oxidized without the presence of the Au catalyst. However, without the Au catalyst, no growth of nanowires was observed. Furthermore, the effect of the oxidation temperature and the film thickness were also investigated. SEM, TEM, and EDX studies demonstrated the presence of Au nanoparticles on top of the NWs, indicating that the Au catalyst drove the growth process. Raman spectroscopy revealed the Rutile crystalline phase of TiO₂ NWs. Gas testing measurements were carried out in the presence of a relative humidity of 40%, showing a reversible response to ethanol and H₂ at various concentrations. Thanks to the moderate temperature and the easiness of the process, the presented synthesis technique is suitable to grow TiO₂ NWs for many different applications. Full article

(This article belongs to the Special Issue Nanostructured Gas Sensors)

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4 pages, 813 KiB

Open AccessProceeding Paper

UV Light Assisted NO₂Sensing by SnO₂/Graphene Oxide Composite

by Hashitha M. M. Munasinghe Arachchige, Nanda Gunawardhana, Dario Zappa and Elisabetta Comini

Proceedings 2018, 2(13), 787; https://doi.org/10.3390/proceedings2130787 - 23 Nov 2018

Cited by 5 | Viewed by 1984

Abstract

Nitric oxide (NO₂) is one of the air pollutants that pose serious environmental concerns over the years. In this study, SnO₂ nanowires were synthesized by evaporation-condensation method and graphene oxide were synthesized using modified Hummers method for low temperature NO [...] Read more.

Nitric oxide (NO₂) is one of the air pollutants that pose serious environmental concerns over the years. In this study, SnO₂ nanowires were synthesized by evaporation-condensation method and graphene oxide were synthesized using modified Hummers method for low temperature NO₂ detection. Drop cast method was used to transfer graphene oxide (GO), to form composite GO-metal oxide p-n junctions. With integration of reduce graphene oxide (rGO), the UV light absorption was enhanced. This metal oxide composite has shown a reversible response in detecting low concentrations of NO₂ under UV irradiation, with a working temperature range of 50–150 °C. Pure SnO₂ shows 20% response to NO₂ (4 ppm) in dark conditions, while the response increasesupto60%usingUVirradiationat50°C.Furthermore, SnO₂/rGOshowsa40%ofresponse in dark, while the response increases to 160% under UV light illumination. This composite exhibits excellent recovery and maintains the baseline under UV light at low temperatures, which effectively overcome the drawbacks of low recovery typically shown by metal oxide gas sensors at low temperature. Full article

(This article belongs to the Proceedings of EUROSENSORS 2018)

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