| Polyvinyl alcohol/starch modified cotton thread surface as a novel colorimetric glucose sensor | |
| Punnoy P., Preechakasedkit P., Aumnate C., Rodthongkum N., Potiyaraj P., Ruecha N. | |
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| Abstract | |
| Cotton threads have received significant attention to fabricate colorimetric sensing devices due to their self-microfluidic property. To improve the entrapment capacity and stability of the optically responsive reagents and bioreceptors on thread substrate, polyvinyl alcohol (PVA) composited with starch was modified on thread surface to serve as a detection zone relying on distance-based signaling for colorimetric glucose detection in artificial tear. The modified thread surface was characterized to ensure the desired properties prior to fabrication of glucose sensor by integrating with a 3D printed cassette, and the purple color length of iodine–starch–PVA complex was readily observed by the naked-eye within 120 s using a low sample volume of 25 µL, offering a linearity of 0.1–5.0 mM and detection limit of 0.1 mM, which covers a cut-off glucose level in human tear (<0.5 mM). | |
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| 3D printers; Color; Colorimetry; Cotton; Diagnosis; Glucose; Glucose sensors; Polyvinyl alcohols; Bioreceptors; Colorimetric sensing; Composited; Cotton threads; Detection zones; Distance-based readout; Polyvinyls; Property; Sensing devices; Thread surface; Starch | |
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| Flexible superhydrophobic gold film for magnetical manipulation of droplets | |
| Nootchanat S., Boonmeewiriya S., Parnsubsakul A., Insin N., Ekgasit S., Wongravee K. | |
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| Herein, we present a simple, efficient, and economical approach for the preparation of superhydrophobic gold film embedded on polydimethylsiloxane (PDMS) sheets without the requirement of surface pretreatment. The reduction reaction between chloroauric acid (HAuCl4) and sodium formate (HCOONa) at room temperature was performed to generate the aggregated gold microstructures on a PDMS sheet without chemical residuals. Superhydrophobic property was achieved when deposition time was reached to 2 h with water contact angle >160° and low contact angle hysteresis (H = 1.93°). Systematic investigations of the size, morphology, and mechanism of the generated gold films are presented. The generated gold film contains two different layers involving uniform spherical gold particles attached to the PDMS surface with the complex hierarchical structures on top. The complex structures play an important role in the superhydrophobic property, as they strongly promote the roughness to the PDMS surface. The durability of the fabricated gold film was elucidated by dropping ~7,200 waterdrops and external physical forces (e.g. stretch, bend, and twist). The main structures and their superhydrophobic properties have not disoriented after the tests. Moreover, the surface of the gold film demonstrated the potential applications as magnetical manipulation of droplets and a robust Surface enhanced Raman spectroscopy (SERS substrate). © 2021 Elsevier Ltd | |
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| Chlorine compounds; Contact angle; Drops; Film preparation; Gold; Gold compounds; Metallic films; Microchannels; Morphology; Photomasks; Polydimethylsiloxane; Raman spectroscopy; Silicones; Sodium compounds; Substrates; Superhydrophobicity; Chemical residuals; Contact angle hysteresis; Hierarchical structures; Polydimethylsiloxane PDMS; Reduction reaction; Surface enhanced Raman spectroscopy; Surface pretreatment; Water contact angle; Gold metallography | |
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| Radiation induced graft polymerization of fluorinated methacrylate onto polypropylene spunbond nonwoven fabric. | |
| Thinkohkaew K., Piroonpan T., Jiraborvornpongsa N., Potiyaraj P. | |
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| Radiation-induced grafting technique is one of the most promising methods to improve functional properties of textile materials. This work reports the grafting of 2,2,2-trifluoroethyl methacrylate (TFEM) onto polypropylene (PP) spunbond nonwoven fabric via gamma irradiation to improve its hydrophobicity. The effects of monomer concentration, solvent type, atmospheric condition, and irradiation dose on the degree of grafting were investigated. As characterized by SEM, FTIR, and NMR, the appearance and chemical characteristic of grafted fabric were completely altered compared to the original fabric. The grafted fabrics illustrated impressively high water contact angle of 125 degree. Moreover, the grafted fabrics maintained great hydrophobicity after the tests of chemical, thermal, UV, mechanical, and washing durability. These results suggested that grafting of 2,2,2-trifluoroethyl methacrylate onto PP spunbond offered a potential method to generate reusable hydrophobic fabrics. © 2021 | |
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| Bacterial cellulose-based re-swellable hydrogel: Facile preparation and its potential application as colorimetric sensor of sweat pH and glucose | |
| Siripongpreda T., Somchob B., Rodthongkum N., Hoven V.P. | |
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| Direct deposition of the negatively charged polyelectrolyte, carboxymethyl cellulose (CMC), into a bacterial cellulose (BC) matrix was used as a simple route to fabricate a re-swellable and biocompatible cellulose-based hydrogel. As a result of this non-destructive approach, the physical and mechanical property of the original BC were well-preserved within the resulting BC/CMC hydrogel. As a BC/CMC-based colorimetric pH sensor, it exhibited a rapid response with an easy color differentiation between each pH by the naked eye, and wide linear range of pH 4.0–9.0 with good linearity. For the detection of glucose in sweat, the BC/CMC-based colorimetric glucose sensor provided a low limit of detection (25 μM) with a wide linear detection range (0.0–0.5 mM) and high accuracy. These BC/CMC based sensors could potentially be applied as non-invasive semi-quantitative sensors for on-skin health monitoring. © 2020 Elsevier Ltd | |
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| Biocompatibility; Cellulose; Color; Colorimetry; Glucose; Glucose sensors; Hydrogels; Polyelectrolytes; Bacterial cellulose; Carboxymethyl cellulose; Colorimetric sensors; Facile preparation; Limit of detection; Linear detection ranges; Negatively charged; Physical and mechanical properties; pH sensors; Carboxymethyl Cellulose; Colorimetry; Glucose; Polyelectrolytes; carboxymethylcellulose; cellulose; glucose; water; chemistry; color; colorimetry; genetic procedures; Gluconacetobacter xylinus; human; hydrogel; limit of detection; pH; procedures; static electricity; sweat; wettability; Biosensing Techniques; Carboxymethylcellulose Sodium; Cellulose; Color; Colorimetry; Gluconacetobacter xylinus; Glucose; Humans; Hydrogels; Hydrogen-Ion Concentration; Limit of Detection; Static Electricity; Sweat; Water; Wettability | |
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| Computational fluid dynamics simulation of methanol to olefins in stage circulating fluidized bed riser: Effect of reactor stage parameters on product yields | |
| Soanuch C., Korkerd K., Phupanit J., Piemjaiswang R., Piumsomboon P., Chalermsinsuwan B. | |
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| The risers of a conventional fluidized bed reactor and a stage fluidized bed reactor for the convention of methanol to olefins (MTO) were simulated using computational fluid dynamics. The reaction rates of the MTO reaction were validated to successfully match with the literature experiment. Then, the reactor stage parameters were examined by using the 2k design of the experiment method, including the number of reactor stages, the thickness of the reactor stage, and the wall temperature of the reactor stage. The stage circulating fluidized bed riser decreased the yield of ethene but increased the yield of propene and light olefins. From the obtained solid volume fraction profile, the stage circulating fluidized bed riser could reduce the back-mixing and increase the system turbulence, which promotes the light olefins of the MTO reaction yield. The wall temperature of the reactor stage did not significantly affect the chemical reaction in the circulating fluidized bed riser. © 2021, The Korean Institute of Chemical Engineers. | |
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| Long-chain bio-olefins production via oxidative dehydrogenation of oleic acid over vanadium oxides/KIT-6 catalysts | |
| Le D., Chaidherasuwet N., Rueangthaweep A., Kulsing C., Hinchiranan N. | |
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| Long-chain α-olefins (≥ C10) are normally applied in detergents, lubricants, and oil field chemicals. Due to the abundance of palm oil, the derivatives derived from palm oil, such as oleic acid (OA), can be converted to long-chain olefins via oxidative dehydrogenation (ODH) over a series of vanadium oxides (VxOy) incorporated with KIT-6 (nV-KIT-6 catalysts) synthesized by a direct hydrothermal method. Various ammonium metavanadate/tetraethyl orthosilicate molar ratios (V/Si) were evaluated over the range of 0.01–0.09. The results obtained from X-ray diffractometry, hydrogen-temperature programmed reduction, and X-ray photoelectron spectroscopy analyses revealed that the VxOy were mainly in a tetrahedral form when the V/Si molar ratios were lower than 0.05. Above this point, the formation of V2O5 crystallites was observed. The ODH of OA was performed in a continuous flow fixed-bed reactor under atmospheric pressure in the absence of solvent to avoid the interference of by-products generated from solvent oxidation. The results showed that the OA conversion and selectivity towards the desired products strongly depended on the V/Si molar ratio and the reaction temperature. The highest selectivity of olefins (alkenes + dienes) with carbon atoms in the range of C7–17 was 44%. Moreover, the selectivity to aromatics at 24% was observed at a 76% OA conversion level when the ODH was activated using the 0.05 V-KIT-6 catalyst under a 1/1 (v/v) oxygen/nitrogen gas mixture at a flow rate of 100 mL min−1 at 450 °C. Although the high selectivity towards alkenes was promoted by a higher dispersion of VxOy species on the catalyst, overdose of V/Si molar ratios produced more oxygenate compounds. The reaction mechanism for the ODH of OA was likely to be decarboxylation and decarbonylation followed by dehydration. The 0.05 V-KIT-6 catalyst also exhibited reusability over two cycles. © 2021 Elsevier B.V. | |
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| Carboxylation; Catalyst selectivity; Chemical reactors; Dehydrogenation; Epoxidation; Molar ratio; Oleic acid; Palm oil; Reusability; Vanadium pentoxide; X ray photoelectron spectroscopy; $+10$/Be; High selectivity; Long chain olefins; Long chains; Mesoporous KIT-6; Molar ratio; Olefin production; Oxidative dehydrogenations; Vanadium oxides; ]+ catalyst; Olefins | |
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