Miniaturized Enzymatic Fuel Cells (EFCs) have attracted great attention due to the possibility of integrating them with various low-powered microelectronic devices. In a flow-through system, ...harnessing the co-laminar property of microfluidics, membraneless microfluidic EFCs (M-MEFC) can be designed, enhancing the ease of use of bio-devices and offering opportunities for new concepts. This brief review encompasses the development, current challenges and future pathways in the field of M-MEFCs, focusing in particular on some fabrication aspects and related device performance.
•Enzymatic fuel cells (EFCs) are eco-friendly power source devices.•Microfluidic concepts offer new opportunities towards miniaturized EFCs.•Easy-to-handle techniques are available for device fabrication.•Membraneless microfluidic EFCs show enhanced performance more than 100 μW/cm2.
Multicopper oxidases (MCOs) catalyze the oxidation of a variety of substrates while reducing oxygen into water through four copper atoms. As an additional feature, some MCOs display an enhanced ...activity in solution in the presence of Cu2+. This is the case of the hyperthermophilic laccase HB27 from Thermus thermophilus, the physiologic role of which is unknown. As a particular feature, this enzyme presents a methionine rich domain proposed to be involved in copper interaction. In this work, laccase from T. thermophilus was produced in E. coli, and the effect of Cu2+ on its electroactivity at carbon nanotube modified electrodes was investigated. Direct O2 electroreduction is strongly dictated by carbon nanotube surface chemistry in accordance with the enzyme dipole moment. In the presence of Cu2+, an additional low potential cathodic wave occurs, which was never described earlier. Analysis of this wave as a function of Cu2+ availability allows us to attribute this wave to a cuprous oxidase activity displayed by the laccase and induced by copper binding close to the Cu T1 center. A mutant lacking the methionine-rich hairpin domain characteristic of this laccase conserves its copper activity suggesting a different site of copper binding. This study provides new insight into the copper effect in methionine rich MCOs and highlights the utility of the electrochemical method to investigate cuprous oxidase activity and to understand the physiological role of these MCOs.
Redox enzymes catalyze major reactions in microorganisms to supply energy for life. Their use in electrochemical biodevices requires their integration on electrodes, while maintaining their activity ...and optimizing their stability. In return, such applicative development puts forward the knowledge on involved catalytic mechanisms, providing a direct electrode connection of the enzyme is fulfilled. Enzymes being large molecules with active site embedded in an insulating moiety, direct bioelectrocatalysis supposes strategies for specific orientation of the enzyme to be developed. In this review, we summarize recent advances during the past 3 years in the chemical modification of electrodes favoring direct electrocatalysis. We present the different methodologies used according to the electrode materials, including metals, carbon-based electrodes, or porous structures and discuss the gained insights into bioelectrocatalysis. We especially focus on enzyme engineering, which appears as an emerging strategy for enzyme anchoring. Remaining challenges will be discussed with regard to these later findings.
•Applicability of redox enzymes as electrocatalysts requires their oriented immobilization on electrodes.•Specific recognition of enzymes on related chemically modified electrodes favors DET.•Protein engineering to fit DET requirements is an increasing research area.•Electrode modification mainly involves diazonium salt grafting, SAMs, amine oxidation, or p–p stacking.•Grafting of enzymes includes maleimide, imine, or carbodimide coupling and click chemistry.
•The Microwave-assisted magnetite is a time and cost-efficient synthesis process.•The study of Analog resistive switching in Magnetite-based memristive devices.•The investigation of the ...magnetite-based memristive device for the synaptic application.•The synaptic behavior has been studied with different electrical pulses for performance optimization.
In this report, we have studied resistive switching (RS) dynamics in the microwave-assisted magnetite (Fe3O4) based memristive device by having Platinum (Pt) and Fluorine-doped-Tin-Oxide (FTO) as metal electrodes. Fe3O4 insulating layer film has been examined by using X-ray diffraction (XRD), energy dispersive X-ray (EDX), and field emission scanning electron microscopy (FESEM), respectively, for crystal structure, elemental composition, and surface microstructure. The electrical response of the fabricated memristive device has been observed by using Keithley-4200 parameter analyzer with −0.4 V/+0.4 V and −0.8 V/+0.8 V DC sweeping voltage at room temperature. The fabricated device has shown analog resistive switching (ARS); therefore potentiation/depression behavior of the device has been observed by applying multiple positive and negative pulses for evaluation of its synaptic performance.
Neurotransmitter release in chemical synapses plays a pivotal role in a wide range of essential brain functions, including neural activity (potentiation/depression), learning, cognition, emotion, ...perception, and consciousness. In this study, we have presented the fabricated cross-cell memristive device that exhibits an analog resistive switching (ARS) device, with Silver (Ag) as active and Platinum (Pt) as inert metal electrodes. The energy bandgap, crystal structure, surface morphology, elemental composition, and electronic properties of the deposited metal-oxide thin film were examined by using UV–Vis spectroscopy, Glancing Angle X-ray diffraction (GAXRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX), and Raman spectroscopy, respectively. The electrical characteristics of the fabricated resistive switching (RS) device have been studied by the Keithley 4200A SCS parameter analyzer by low triangular DC sweep voltage (-2V/+2V) at room temperature (RT). Furthermore, we have evaluated the outstanding performance of the fabricated cross-cell RS device at a read voltage of 0.1V, and we have also discussed its remarkable linearity. This work will aid researchers in realizing the synaptic behavior of cross-cell devices for neuromorphic computing applications.
Display omitted
•Study of analog resistive switching (ARS) of an Iron-Oxide-based cross-cell memristive device with the configuration Ag/Fe3O4/Pt/Ti/SiO2.•Optimizing the read voltage and achieving excellent linearity for cross-cell memristors in synaptic memristive device applications.•The study of neural activity (potentiation/depression) conducts neuromorphic computing to mimic the functions of the human brain.•Neuromorphic computing mimics biological brain function for information processing, aiming to alleviate the von Neumann architecture bottleneck.
Redox enzymes, which catalyze reactions involving electron transfers in living organisms, are very promising components of biotechnological devices, and can be envisioned for sensing applications as ...well as for energy conversion. In this context, one of the most significant challenges is to achieve efficient direct electron transfer by tunneling between enzymes and conductive surfaces. Based on various examples of bioelectrochemical studies described in the recent literature, this review discusses the issue of enzyme immobilization at planar electrode interfaces. The fundamental importance of controlling enzyme orientation, how to obtain such orientation, and how it can be verified experimentally or by modeling are the three main directions explored. Since redox enzymes are sizable proteins with anisotropic properties, achieving their functional immobilization requires a specific and controlled orientation on the electrode surface. All the factors influenced by this orientation are described, ranging from electronic conductivity to efficiency of substrate supply. The specificities of the enzymatic molecule, surface properties, and dipole moment, which in turn influence the orientation, are introduced. Various ways of ensuring functional immobilization through tuning of both the enzyme and the electrode surface are then described. Finally, the review deals with analytical techniques that have enabled characterization and quantification of successful achievement of the desired orientation. The rich contributions of electrochemistry, spectroscopy (especially infrared spectroscopy), modeling, and microscopy are featured, along with their limitations.
The thermal properties of polymeric nanocomposites can be examined using TGA and DSC techniques, while dielectric properties can be examined through simulated scattering (S11, S12, S21, and S22) ...parameters. Polyaniline (PAni) nanopowder was synthesized using chemical oxidative polymerization techniques. Consequently, the crystallite size and morphology of the synthesized powder were examined using the XRD, TEM, and FESEM techniques. Further, a series of polymeric nanocomposites was developed via wet mixing and compressor molding techniques for various volume percentages (54.0, 57.5, 60.1, and 61.7 vol%) of synthesized powder within PAni/epoxy composites. Consequently, dielectric and absorbing properties have been measured using a vector network analyzer and its software module. The computed complex permittivity data were used to evaluate the absorption for different thicknesses of samples. A minimum reflection loss of − 22.3 dB (> 99.9% absorption) was optimized with broadband frequency ranges. The unique heterostructures of nanocomposite are responsible for the enhanced absorption and shielding performance.
Graphical abstract
Electromagnetic absorbers based on carbonaceous materials, i.e., carbon black, polyaniline, polypyrrole, carbon fiber, etc., are prominently employed to attenuate incident electromagnetic waves. In ...the current work, exfoliated graphite (EG) was synthesized with swollen expanded volume from graphite flake by using a simple and inexpensive method. After synthesis, a series (8.9, 22.9, 33.3, 41.4 and 44.7 volume percentage) of EG–epoxy composites were prepared using a wet mixing method. EG and the prepared composites were characterized by x-ray diffraction analysis, field-emission scanning electron microscopy, and energy-dispersive x-ray analysis. An Agilent vector network analyzer (model PNA E8364B) was employed to compute the complex permittivity (
ε
r
=
ε
′ − j
ε
″) of the prepared composites in the frequency range of 2 GHz to 18 GHz. The dielectric loss of the prepared EG–epoxy composites was quantified in terms of the loss tangent (tan
δ
e
=
ε
″/
ε
′). Their radar absorption properties were evaluated in terms of the return loss (RL), which in turn was calculated for varying thicknesses of the prepared composites using the computed complex permittivity data. The measured minimum RL was −26.4 dB for the absorber with thickness of 4.0 mm, and the bandwidth achieved was 5.2 GHz for RL ≤ − 10 dB in the effective frequency region of 8 GHz to 14 GHz. The matching frequency shifted towards downwards with increasing EG content in the epoxy thermosetting matrix according to both the calculated and measured data. Consequently, the prepared composites exhibited good complex permittivity, dielectric tangent loss, and microwave absorption and could be utilized in the design of electromagnetic interference shielding and absorbers for stealth applications.
Background: Mental health is a big problem throughout the world, and India is not far behind. When we look at progress in the field of mental health, it appears to be sluggish. Despite the fact that ...a newly created mental health literacy (MHL) scale revealed substantial score disparities between the general public and mental health professionals, there is currently no published scale to measure MHL among healthcare students.
Aims and Objectives: The major part was comparing the knowledge, attitude and perception of 1st year medical students with final year medical students regarding psychiatric disorders and measuring there response on Likert scale.
Materials and Methods: The participants were recruited from 1st year to final year undergraduate students, during the period April 2019 to January 2020 in Patna Medical College and Hospital, Patna. The sample consisted of 100 students (50 from 1st year MBBS Students and 50 from final year MBBS (Students) Non-random, non-stratified, and purposive sampling was done for the purpose of the study.
Results: Among the groups, majority of the of the final year students (64%) agreed that the best described condition of the patient was Generalized Anxiety Disorder, but only 26% of the 1st years students agreed that the best described condition of the patient was Generalized Anxiety Disorder. There was significant difference between 1st years and final year students about the knowledge of the described condition with P<0.001.
Conclusion: Result showed that the final year students had more knowledge about the cases with regard to correct diagnosis, usefulness of various treatments and interventions and best the source of help. The 1st and final yearstudent had no differences in the attitude and perception regarding various cases given in the vignettes. Stigma based attitude was almost equally common among both 1st year and final year students.
PDF
