With 6.93M confirmed cases of COVID-19 worldwide, making individuals aware of their sanitary health and ongoing pandemic remains the only way to prevent the spread of this virus. Wearing masks is an important step in this prevention. Hence, there is a need for monitoring if people are wearing masks or not. Closed circuit television (CCTV) cameras endowed with computer vision function by embedded systems, have become popular in a wide range of applications, and can be used in this case for real time monitoring of people wearing masks or not. In this paper, we propose to model this task of monitoring as a special case of object detection. However, real-time scene parsing through object detection running on edge devices is very challenging, due to limited memory and computing power of embedded devices. To deal with these challenges, we used a few popular object detection algorithms such as YOLOv3, YOLOv3Tiny, SSD and Faster R-CNN and evaluated them on Moxa3K benchmark dataset. The results obtained from these evaluations help us to determine methods that are more efficient, faster, and thus are more suitable for real-time object detection specialized for this task.
The urea oxidation reaction (UOR) is an excellent alternative to the sluggish oxygen evolution reaction (OER) as an anode reaction for hydrogen generation via electrochemical water splitting. Here, a porphyrin-based conjugated porous polymer (CPP) has been developed through the polycondensation reaction of 2,6-diformyl-4-methylphenol and pyrrole (DMP-POR). The nickel(II) complex of this conjugated polymer Ni-DMP-POR shows efficient UOR in an alkaline medium. The as-synthesized materials were characterized by solid-state 13 C CP-MAS, thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The porous property of the materials was characterized by N 2 adsorption/desorption isotherms at 77 K. Both DMP-POR and Ni-DMP-POR showed excellent thermal stability. The Ni-DMP-POR exhibits very good UOR in 1 M KOH and 0.33 M urea with an overpotential of 260 mV at 10 mA cm −2 and a Tafel slope of 48 mV dec −1 . The catalyst also shows excellent chronoamperometric and chronopotentiometric stability, suggesting its future scope in sustainable hydrogen production from wastewater resources.
Ordered
mesoporous carbon-supported gold nanoparticles (Au/OMC)
have been fabricated in one step through a hard template method using
gold nanoparticle-intercalated mesoporous silica (GMS) to explore
two different catalytic properties, for example, electrocatalytic
oxidation of methanol and colorimetric determination of glutathione
(GSH). The catalytically inert but conducting nature of mesoporous
carbon (OMC) and promising catalytic activity of gold nanoparticles
(AuNPs) has inspired us to synthesize Au/OMC. The as-prepared Au/OMC
catalyst was characterized by powder X-ray diffraction, N2 adsorption–desorption, scanning electron microscopy, transmission
electron microscopy, energy-dispersive X-ray analysis-elemental mapping,
and X-ray photoelectron spectroscopy. The characterization results
indicate that AuNPs are uniformly distributed on the surface of OMC.
The conducting-OMC framework with a high surface area of Au/OMC provides
superior transport of electrons through the porous surface of carbon
matrix and resulted in its high efficiency and stability as an electrocatalyst
for the oxidation of methanol in comparison to CMK-3, SBA-15, and
GMS in alkaline medium. The efficiency of Au/OMC toward methanol oxidation
in alkaline medium is much higher in comparison to that in acidic
medium. The lower value of If/Ib in the acidic medium in comparison to that
in the alkaline medium clearly indicates that the oxidation process
with Au/OMC as a catalyst is much more superior in alkaline medium
with better tolerance toward the accumulation of intermediate CO species
on the active surface area. Furthermore, the Au/OMC catalyst is successfully
utilized for the detection and quantification of GSH spectrophotometrically
with a limit of detection value of 0.604 nM.
Electrolysis of water is emerging as a potential technique for producing green hydrogen. However, the large overpotential due to sluggish kinetics involved with the oxygen evolution reaction (OER) coerces scientific...
The intriguing features of artificial enzymes made nanozymes attractive in the field of biosensing and biomedical. Here, vanadium‐incorporated dendritic mesoporous silica (VMSN) as an oxidase mimicking nanozyme was utilized as a sensitive and selective colorimetric biosensor to detect dopamine (DA) and treat cancer cells. The nanozyme was successfully fabricated through the in‐situ incorporation of vanadium ions in the silica framework via a simple sol‐gel method using CTAB and mesitylene. The excellent oxidase‐like activity of VMSN was monitored by the oxidation of TMB. The kinetics, mechanism of the catalytic reaction and the effect of temperature, pH, and concentration on oxidase‐like activity were investigated thoroughly and further, based on the oxidase‐like activity, a fast and sensitive colorimetric sensing of dopamine developed with a LOD of 0.0021 μM and a linear range of 0–50 μM. The proposed colorimetric method was successfully used to determine DA concentration in commercially available dopamine hydrochloride injection.VMSN was further modified with folic acid and utilized against cancer cells in vitro. Neuroblastoma cells (SHSY‐5Y) show ROS generated by VMSN in the presence of oxygen, leading to enhanced cytotoxicity detrimental for SHSY‐5Y cells.
To date, the fabrication of multifunctional nanoplatforms
based
on a porous organic polymer for electrochemical sensing of biorelevant
molecules has received considerable attention in the search for a
more active, robust, and sensitive electrocatalyst. Here, in this
report, we have developed a new porous organic polymer based on porphyrin
(TEG-POR) from a polycondensation reaction between a triethylene glycol-linked
dialdehyde and pyrrole. The Cu(II) complex of the polymer Cu-TEG-POR
shows high sensitivity and a low detection limit for glucose electro-oxidation
in an alkaline medium. The characterization of the as-synthesized
polymer was done by thermogravimetric analysis (TGA), scanning electron
microscopy (SEM), transmission electron microscopy (TEM), Fourier
transform infrared (FTIR) spectroscopy, and 13C CP-MAS
solid-state NMR. The N2 adsorption/desorption isotherm
was carried out at 77 K to analyze the porous property. TEG-POR and
Cu-TEG-POR both show excellent thermal stability. The Cu-TEG-POR-modified
GC electrode shows a low detection limit (LOD) value of 0.9 μM
and a wide linear range (0.001–1.3 mM) with a sensitivity of
415.8 μA mM–1 cm–2 toward
electrochemical glucose sensing. The interference of the modified
electrode from ascorbic acid, dopamine, NaCl, uric acid, fructose,
sucrose, and cysteine was insignificant. Cu-TEG-POR exhibits acceptable
recovery for blood glucose detection (97.25–104%), suggesting
its scope in the future for selective and sensitive nonenzymatic glucose
detection in human blood.
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