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Topic review
Updated time: 21 Jul 2021
Submitted by: Mohamed Hassan
Definition: The detection of glucose is crucial in the management of diabetes and other medical conditions but also crucial in a wide range of industries such as food and beverages. The development of glucose sensors in the past century has allowed diabetic patients to effectively manage their disease and has saved lives. First-generation glucose sensors have considerable limitations in sensitivity and selectivity which has spurred the development of more advanced approaches for both the medical and industrial sectors.
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Topic review
Updated time: 12 Apr 2021
Submitted by: Aurelia Pisoschi
Definition: Antioxidants are compounds that prevent or delay the oxidation process, acting at a much smaller concentration, in comparison to that of the preserved substrate. Primary antioxidants act as scavenging or chain breaking antioxidants, delaying initiation or interrupting propagation step. Secondary antioxidants quench singlet oxygen, decompose peroxides in non-radical species, chelate prooxidative metal ions, inhibit oxidative enzymes. Based on antioxidants’ reactivity, four lines of defense have been described: Preventative antioxidants, radical scavengers, repair antioxidants, and antioxidants relying on adaptation mechanisms. Carbon-based electrodes are largely employed in electroanalysis given their special features, that encompass large surface area, high electroconductivity, chemical stability, nanostructuring possibilities, facility of manufacturing at low cost, and easiness of surface modification. Largely employed methods encompass voltammetry, amperometry, biamperometry and potentiometry. Determination of key endogenous and exogenous individual antioxidants, as well as of antioxidant activity and its main contributors relied on unmodified or modified carbon electrodes, whose analytical parameters are detailed. Recent advances based on modifications with carbon-nanotubes or the use of hybrid nanocomposite materials are described. Large effective surface area, increased mass transport, electrocatalytical effects, improved sensitivity, and low detection limits in the nanomolar range were reported, with applications validated in complex media such as foodstuffs and biological samples.
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Topic review
Updated time: 26 Apr 2021
Submitted by: Nan Gao
Definition: Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and electrochemical stability, good optical transparency and biocompatibility.
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Topic review
Updated time: 23 Jun 2021
Submitted by: Dong Sui
Definition: Na-CO2 batteries with high energy density are drawing tremendous attention because of their advantages of combining cost-effective energy conversion and storage with CO2 clean recycle and utilization. Nevertheless, their commercial applications are impeded by unsatisfactory electrochemical performance including large overpotentials, poor rate capability, fast capacity deterioration, and inferior durability, which mainly results from the inefficient electrocatalysts of cathode materials.
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Topic review
Updated time: 28 Oct 2020
Submitted by: Ali Zolfagharian
Definition: Building on the recent progress of four-dimensional (4D) printing to produce dynamic structures, this study aimed to bring this technology to the next level by introducing control-based 4D printing to develop adaptive 4D-printed systems with highly versatile multi-disciplinary applications, including medicine, in the form of assisted soft robots, smart textiles as wearable electronics and other industries such as agriculture and microfluidics. This study introduced and analyzed adaptive 4D-printed systems with an advanced manufacturing approach for developing stimuli-responsive constructs that organically adapted to environmental dynamic situations and uncertainties as nature does. The adaptive 4D-printed systems incorporated synergic integration of three-dimensional (3D)-printed sensors into 4D-printing and control units, which could be assembled and programmed to transform their shapes based on the assigned tasks and environmental stimuli. This paper demonstrates the adaptivity of these systems via a combination of proprioceptive sensory feedback, modeling and controllers, as well as the challenges and future opportunities they present.
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Topic review
Updated time: 02 Nov 2020
Submitted by: Gilbert Bellanger
Definition: Cathodic corrosion is evidenced by the formation of transient complexes of palladium. It is obvious to see a peak of palladium transient by cyclic voltammetry for different amounts of deposited hydrogen expressed as a current during back-diffusion. Therefore, in the part located at the surface of electrolyte, drastic structural changes lead to loss of cohesion and cracking. The objective of this project is to take into account the mechanical constraints formed by diffusion of hydrogenorisotope and the cathodic corrosion produced by formation of superficial hydride transients, bothresponsible of destruction of palladium or alloyed cathode. To know the origin of these, it was necessary to discriminating the damaging effects encountered.
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Topic review
Updated time: 27 May 2021
Submitted by: Fan Liu
Definition: Solid oxide fuel cells (SOFCs) are promising and rugged solid-state power sources that can directly and electrochemically convert the chemical energy into electric power. Direct-hydrocarbon SOFCs eliminate the external reformers; thus, the system is significantly simplified and the capital cost is reduced. To reduce operating temperatures of SOFCs, intermediate-temperature proton-conducting SOFCs (P-SOFCs) are being developed as alternatives, which give rise to superior power densities, coking and sulfur tolerance, and durability. Due to these advances, there are growing efforts to implement proton-conducting oxides to improve durability of direct-hydrocarbon SOFCs.
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Topic review
Updated time: 22 Jan 2021
Submitted by: Abd-Elgawad Radi
Definition: Over the last few decades, aptamers have attracted a lot of interest in the biosensor industry, because they are the next generation of target receptors that can replace antibody functions. SELEX is an automated procedure and needs only a few days to evolve some binders. This is much shorter compared to antibody selection, which often requires several months. Aptamers can even differentiate the chirality of a molecule and its secondary structure. Aptamers can choose any types of targets with no restrictions. The antibodies undergo permanent degradation, while aptamers can undergo several cycles of denaturation/regeneration. DNA aptamers are acceptable for the design of reusable aptamer detectors, while RNA aptamers can be single-dimensional. The use of aptamers is not limited to specific areas and can be used as recognition molecules in almost any domain. The main limitation is the degradation of RNAs aptamer by ribonuclease. These problems can be solved by modifying RNA aptamers. Another limitation is that the microenvironment will affect the structure of the aptamer and the interactions with the ligand-target. Moreover, the composition of salts has a significant effect on aptamer configuration. The integration of aptamers into detection platforms such as microfluidics and paper-based analytical devices and lab-on-a-chip (LOC) areas for point-of-care (POC) diagnosis is becoming increasingly popular. Aptamer-based detection systems meet most POC diagnostic requirements.
Topic review
Updated time: 13 Nov 2020
Submitted by: Martyn Pemble
Definition: The research field of glucose biosensing has shown remarkable growth and development since the first reported enzyme electrode in 1962. Extensive research on various immobilization methods and the improvement of electron transfer efficiency between the enzyme and the electrode have led to the development of various sensing platforms that have been constantly evolving with the invention of advanced nanostructures and their nano-composites. Examples of such nanomaterials or composites include gold nanoparticles, carbon nanotubes, carbon/graphene quantum dots and chitosan hydrogel composites, all of which have been exploited due to their contributions as components of a biosensor either for improving the immobilization process or for their electrocatalytic activity towards glucose. This review aims to summarize the evolution of the biosensing aspect of these glucose sensors in terms of the various generations and recent trends based on the use of applied nanostructures for glucose detection in the presence and absence of the enzyme.
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Topic review
Updated time: 22 Feb 2021
Submitted by: Jiri Barek
Definition: The main reason for electrode passivation is adsorption/deposition of a passivating compound on working electrode surface. The most pronounced consequences are the decrease of the rate of electrode reaction resulting in the shift of half-wave or peak potential to more negative (in the case of cathodic reaction) or to more positive (in the case of anodic reaction) potentials and in the decrease of peak current, which is especially in the case of pulsed technique influenced by this rate.
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