RESUMO
Van der Waals (vdW) heterostructures composed of atomically thin two-dimensional (2D) materials have more potential than conventional metal-oxide semiconductors because of their tunable bandgaps, and sensitivities. The remarkable features of these amazing vdW heterostructures are leading to multi-functional logic devices, atomically thin photodetectors, and negative differential resistance (NDR) Esaki diodes. Here, an atomically thin vdW stacking composed of p-type black arsenic (b-As) and n-type tin disulfide (n-SnS2 ) to build a type-III (broken gap) heterojunction is introduced, leading to a negative differential resistance device. Charge transport through the NDR device is investigated under electrostatic gating to achieve a high peak-to-valley current ratio (PVCR), which improved from 2.8 to 4.6 when the temperature is lowered from 300 to 100 K. At various applied-biasing voltages, all conceivable tunneling mechanisms that regulate charge transport are elucidated. Furthermore, the real-time response of the NDR device is investigated at various streptavidin concentrations down to 1 pm, operating at a low biasing voltage. Such applications of NDR devices may lead to the development of cutting-edge electrical devices operating at low power that may be employed as biosensors to detect a variety of target DNA (e.g., ct-DNA) and protein (e.g., the spike protein associated with COVID-19).
RESUMO
Several phenomena occurring throughout the life of living things start and end with proteins. Various proteins form one complex structure to control detailed reactions. In contrast, one protein forms various structures and implements other biological phenomena depending on the situation. The basic principle that forms these hierarchical structures is protein self-assembly. A single building block is sufficient to create homogeneous structures with complex shapes, such as rings, filaments, or containers. These assemblies are widely used in biology as they enable multivalent binding, ultra-sensitive regulation, and compartmentalization. Moreover, with advances in the computational design of protein folding and protein-protein interfaces, considerable progress has recently been made in the de novo design of protein assemblies. Our review presents a description of the components of supramolecular protein assembly and their application in understanding biological phenomena to therapeutics.
RESUMO
A novel polymer-coated ZnO based bilayer electron transporting material is investigated for highly efficiency perovskite solar cells. The bilayer ETM consisting of an upper-layer of ZnO nanosheets and a lower-layer of ZnO nanoparticles demonstrates the averaged power conversion efficiency of 13.11% and a maximum power conversion efficiency of 15.13%, compared to single-layers of nanosheets (power conversion efficiencyâ¯=â¯11.73%) and nanoparticles (power conversion efficiencyâ¯=â¯11.08%) films. A conformal coating of a polymer such as polyethylenimine on the surface of bilayered film leading to a significant boost in power conversion efficiency upto 16.39%, thanks to the reduced work function, rapid electron transport and better perovskite infiltration into the bilayer electron transporting material.
RESUMO
Congenital harlequin syndrome is rare dysautonomia of the face most often reported in adults and rarely in infants and children. It is a diagnosis of exclusion and a seemingly benign condition. We report a case of a 6-month-old girl with episodic unilateral and bilateral facial flushing provoked upon awakening and resolved with sleeping with associated autonomic features consistent with harlequin syndrome. This is followed by a review of cases identified regarding this condition in infants and children.
