All currently known sandwich‐type electrochromic devices (ECDs) require at least one optically transparent electrode (OTE) for their operation. Here, it is demonstrated that this requirement is conceptually redundant. The so‐called inverted sandwich ECD architecture is introduced, with its principal components being: two solid optically nontransparent electrodes (high electrical conductivity material), an insulator that prevents a short‐circuit between the electrodes, and an electrochromic mixture applied on a solid carrier. The modus operandi of the present proof‐of‐concept solution‐phase double‐sided ECD is a reversible color change of the indicator dye caused by the variations in pH of the water‐based electrolyte solution due to electrolysis. Application of the inverted sandwich topology to make electrochromic tapes is given.
A green superhydrophobic hybridization concept that incorporates biomimetics (lotus effect), chemistry (siloxane and silane admixtures), and nanotechnology (hydrophobic coating with SiO2 nanoparticles) is used to produce superhydrophobic concrete. The fabricated samples exhibit superior hydrophobicity, contact angles (CA) up to 157.6° ± 3.1°, and roll‐off angles (RO) of 6.5° ± 1.5°, even under high surface mechanical abrasion. The superhydrophobic samples can decrease freeze‐thaw damage and maintain high freeze‐thaw resistance effectively. The modified surfaces exhibit 6 times lower deicing strength compared with the reference surfaces. Furthermore, the high water repellency helps to prevent corrosive liquids from encountering the concrete reinforcement samples and helps to improve the corrosion resistance of steel bars. These unique key properties and self‐cleaning capability make superhydrophobic concrete relevant for a wide range of commercial and practical engineering applications in construction, bridges, and transportation.
Humans are frequently exposed to environmental hepatotoxins, which can lead to liver failure. Biosensors may be the best candidate for the detection of hepatotoxins because of their high sensitivity and specificity, convenience, time-saving, low cost, and extremely low detection limit. To investigate suitability of HepG2 cells for biosensor use, different methods of adhesion on stainless steel surfaces were investigated, with three groups of experiments performed in vitro. Cytotoxicity assays, which include the resazurin assay, the neutral red assay (NR), and the Coomassie Brilliant Blue (CBB) assay, were used to determine the viability of HepG2 cells exposed to various concentrations of aflatoxin B1 (AFB1) and isoniazid (INH) in parallel. The viability of the HepG2 cells on the stainless steel surface was quantitatively and qualitatively examined with different microscopy techniques. A simple cell-based electrochemical biosensor was developed by evaluating the viability of the HepG2 cells on the stainless steel surface when exposed to various concentrations of AFB1 and INH by using electrochemical impedance spectroscopy (EIS). The results showed that HepG2 cells can adhere to the metal surface and could be used as part of the biosensor to determine simple hepatotoxic samples.
Electrochromism encompasses reversible changes of material's optical properties (color, opacity) under the influence of an external electric current or applied voltage. The effect has been known for decades, but its importance continues to grow due to the rapid development of smart systems and the accompanying demand to build devices that consume less power. Most commercial electrochromic devices (ECDs) require sophisticated chemicals and advanced material preparation techniques. Also, the demonstration of electrochromism in chemistry classes mainly uses expensive WO 3 films, intrinsically conductive polymers, and/or optically transparent electrodes (OTEs). The aim of this article is to present a simple and fast educational method to build ECDs from household materials without the need for OTEs: unsharpened kitchen knives are used as electrodes, curcumin from turmeric is used as the electrochromic dye, and baking soda is used as the electrolyte. The laboratory experiments presented will help students gain a deeper understanding of the fundamentals of electrochemistry (electrolysis, pH change) and electrochromism (in our case, color changes due to pH-induced keto-enol tautomerism of curcumin).
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