Experimental study on a novel waterless solar collector

This study is an endeavour to introduce a novel approach to enhance the performance of solar collectors. The sun emits sufficient power of solar radiation to meet the demand of energy. Harvesting the renewable solar energy needs advanced technologies and requirements. Solar ponds including salinity gradient solar ponds (SGSPs) are common solar collectors. These ponds are one of the solar energy applications used for many industrial and domestic purposes. However, challenges of the conventional SGSPs such as evaporation, salt diffusion, temperature discrepancy, and layer mixing profoundly and significantly affected their expansion globally. A novel experimental solar collector configuration to overcome the challenges of the conventional solar ponds (solar collectors) is investigated, there is no water body and no salinity gradient to build; it is entirely a collector with no water body. The experimental unit was constructed in an arid area. It is basically a cylindrical tank with a total depth of 1.4 m with three zones or layers to store heat namely, paraffin wax layer (10 cm thickness). The paraffin layer was covered with a layer of coal with a thickness of 30 cm. On the top of coal layer, an air gap with a thickness of 80 cm was left. A clear plastic cover with a thickness of 0.2 cm was utilized to cover the constructed layers and making the air gap. The experimental unit was monitored, and temperature measurements were collected for the period of 17/7/2021-30/9/2021. The results demonstrated that temperature of the paraffin wax layer reached more than 48 °C in a short period and with a small day and night discrepancy (1 °C). Temperature of the paraffin layer remained constant around 43 °C even in night-time during the period of the study. Furthermore, the results showed that temperatures of coal layer and air gap reached the maximum at the daytime of 53 °C and 71 °C respectively with a clear discrepancy between day and night. The results of the present study are encouraging for more investigations in this new direction of solar collectors.</p

Hybrid Nano-scale Carbon Sensors for Improved Detection of Vital Neurotransmitters

Electrochemical detection of vital biomolecules using nano-carbon materials has attracted great attention to effectively carry-out electrochemical sensing of important neurotransmitters in the brain. Multi-walled carbon nanotubes (MWNTs) and graphene (G) have been employed as promising nano-carbon materials according to physical, electrical, optical, and thermal properties along with remarkable electrochemical performance. Modified MWNTs and G, on the same hand, exhibited greater electrocatalytic activity and improved redox signals of the targeted analytes. For this reason, the primary goal of this study is to fabricate simple, low cost, biocompatible, and modified MWNTs sensor appropriate for dopamine (DA) neurotransmitter detection. To obtain improved sensitivity and selectivity of DA compared to conventional electrodes, our MWNTs electrode was fabricated by a direct draw of MWNTs fibers from MWNTs forest converted into yarn/probe style by twisting then modified with nafion. The second goal was based on applying reduced graphene oxide (RGO) as graphene derivative along with poly (ethylenedioxythiophene): poly (styrenesulfonate) PEDOT:PSS to prepare RGO/PEDOT:PSS dispersion modified with nafion. RGO/PEDOT:PSS-nafion composite drop-casted onto gold mylar sheets to prepare films at specific dimensions. The deposited films were divided into strips in order to be tested for serotonin (5-HT) neurotransmitter detection. The electrocatalytic activity of both electrodes was investigated via electrochemical analytical methods including cyclic voltammetry (CV) and differential pulse Vvoltammetry (DPV) towards mentioned neurotransmitters in the presence of common interferences. The voltammetric studies included different parameters such as modifying with concentric or diluted nafion, number of nafion layer coated the electrode, varied dip-coating times in nafion, and different films thickness which were all investigated

Hybrid Graphene/Conducting Polymer Strip Sensors for Sensitive and Selective Electrochemical Detection of Serotonin

© 2019 American Chemical Society. There is an urgent need for electrochemical sensor materials that exhibit electrochemically compliant properties while also retaining high durability under physiological conditions. Herein, we demonstrate a novel strip-style electrochemical sensor using reduced graphene oxide (rGO) and poly(ethylene dioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) nanocomposite films. The fabricated rGO-PEDOT/PSS sensor with and without nafion has shown an effective electrochemical response for both selectivity and sensitivity of the serotonin (5-hydroxytryptamine, 5-HT) neurotransmitter. The developed high-performance hybrid graphene/conducting polymer strip sensors are likely to find applications as chip electrochemical sensor devices for patients diagnosed with Alzheimer\u27s disease

Probe Sensor Using Nanostructured Multi-Walled Carbon Nanotube Yarn for Selective and Sensitive Detection of Dopamine

The demands for electrochemical sensor materials with high strength and durability in physiological conditions continue to grow and novel approaches are being enabled by the advent of new electromaterials and novel fabrication technologies. Herein, we demonstrate a probe-style electrochemical sensor using highly flexible and conductive multi-walled carbon nanotubes (MWNT) yarns. The MWNT yarn-based sensors can be fabricated onto micro Pt-wire with a controlled diameter varying from 100 to 300 µm, and then further modified with Nafion via a dip-coating approach. The fabricated micro-sized sensors were characterized by electron microscopy, Raman, FTIR, electrical, and electrochemical measurements. For the first time, the MWNT/Nafion yarn-based probe sensors have been assembled and assessed for high-performance dopamine sensing, showing a significant improvement in both sensitivity and selectivity in dopamine detection in presence of ascorbic acid and uric acid. It offers the potential to be further developed as implantable probe sensors