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25,284 result(s) for "639/925"
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Highly sensitive label-free biosensor: graphene/CaF2 multilayer for gas, cancer, virus, and diabetes detection with enhanced quality factor and figure of merit
One of the primary goals for the researchers is to create a high-quality sensor with a simple structure because of the urgent requirement to identify biomolecules at low concentrations to diagnose diseases and detect hazardous chemicals for health early on. Recently graphene has attracted much interest in the field of improved biosensors. Meanwhile, graphene with new materials such as CaF 2 has been widely used to improve the applications of graphene-based sensors. Using the fantastic features of the graphene/CaF 2 multilayer, this article proposes an improvement sensor in the sensitivity (S), the figure of merit (FOM), and the quality factor (Q). The proposed sensor is based on the five-layers graphene/dielectric grating integrated with a Fabry–Perot cavity. By tuning graphene chemical potential (µ c ), due to the semi-metal features of graphene, the surface plasmon resonance (SPR) waves excited at the graphene/dielectric boundaries. Due to the vertical polarization of the source to the gratings and the symmetry of the electric field, both corners of the grating act as electric dipoles, and this causes the propagation of plasmonic waves on the graphene surface to propagate towards each other. Finally, it causes Fabry–Perot (FP) interference on the surface of graphene in the proposed structure's active medium (the area where the sample is located). In this article, using the inherent nature of FP interference and its S to the environment's refractive index (RI), by changing a minimal amount in the RI of the sample, the resonance wavelength (interferometer order) shifts sharply. The proposed design can detect and sense some cancers, such as Adrenal Gland Cancer, Blood Cancer, Breast Cancer I, Breast Cancer II, Cervical Cancer, and skin cancer precisely. By optimizing the structure, we can achieve an S as high as 9000 nm/RIU and a FOM of about 52.14 for the first resonance order (M 1 ). Likewise, the remarkable S of 38,000 nm/RIU and the FOM of 81 have been obtained for the second mode (M 2 ). In addition, the proposed label-free SPR sensor can detect changes in the concentration of various materials, including gases and biomolecules, hemoglobin, breast cancer, diabetes, leukemia, and most alloys, with an accuracy of 0.001. The proposed sensor can sense urine concentration with a maximum S of 8500 nm/RIU and cancers with high S in the 6000 nm/RIU range to 7000 nm/RIU. Also, four viruses, such as M13 bacteriophage, HIV type one, Herpes simplex type 1, and influenza, have been investigated, showing Maximum S (for second resonance mode of λ R (M 2 ) of 8000 nm/RIU (λ R (M 2 ) = 11.2 µm), 12,000 nm/RIU (λ R (M 2 ) = 10.73 µm), 38,000 nm/RIU (λ R (M 2 ) = 11.78 µm), and 12,000 nm/RIU (λ R (M 2 ) = 10.6 µm), respectively, and the obtained S for first resonance mode (λ R (M 1 )) for mentioned viruses are 4740 nm/RIU (λ R (M 1 ) = 8.7 µm), 8010 nm/RIU (λ R (M 1 ) = 8.44 µm), 8100 nm/RIU (λ R (M 1 ) = 10.15 µm), and 9000 (λ R (M 1 ) = 8.36 µm), respectively.
Opportunities and challenges for spintronics in the microelectronics industry
Spintronic devices exploit the spin, as well as the charge, of electrons and could bring new capabilities to the microelectronics industry. However, in order for spintronic devices to meet the ever-increasing demands of the industry, innovation in terms of materials, processes and circuits are required. Here, we review recent developments in spintronics that could soon have an impact on the microelectronics and information technology industry. We highlight and explore four key areas: magnetic memories, magnetic sensors, radio-frequency and microwave devices, and logic and non-Boolean devices. We also discuss the challenges—at both the device and the system level—that need be addressed in order to integrate spintronic materials and functionalities into mainstream microelectronic platforms. This Review Article examines the potential of spintronics in four key areas of application —memories, sensors, microwave devices, and logic devices — and discusses the challenges that need be addressed in order to integrate spintronic materials and functionalities into mainstream microelectronic platforms.
Nanomaterials for T-cell cancer immunotherapy
T-cell-based immunotherapies hold promise for the treatment of many types of cancer, with three approved products for B-cell malignancies and a large pipeline of treatments in clinical trials. However, there are several challenges to their broad implementation. These include insufficient expansion of adoptively transferred T cells, inefficient trafficking of T cells into solid tumours, decreased T-cell activity due to a hostile tumour microenvironment and the loss of target antigen expression. Together, these factors restrict the number of therapeutically active T cells engaging with tumours. Nanomaterials are uniquely suited to overcome these challenges, as they can be rationally designed to enhance T-cell expansion, navigate complex physical barriers and modulate tumour microenvironments. Here, we present an overview of nanomaterials that have been used to overcome clinical barriers to T-cell-based immunotherapies and provide our outlook of this emerging field at the interface of cancer immunotherapy and nanomaterial design.This Review discusses the progress and the remaining challenges for the clinical application of nanomaterial-based T-cell immunotherapies.
Formation of the hollow nanopillar arrays through the laser-induced transformation of TiO2 nanotubes
In the following article, we present a simple, two-step method of creating spaced, hollow nanopillars, from the titania nanotube arrays via pulsed laser-treatment. Due to the high ordering of the structure, the prepared material exhibits photonic properties, which has been shown to increase the overall photoefficiency. The optical and morphological changes in the titania nanotubes after pulsed laser-treatment with 532, 355, and 266 nm wavelengths in the 10–50 mJ/cm 2 fluence range are studied. The investigation reveals, that by using appropriate wavelength and energy, the number of surface defects, geometrical features, or both can be tailored.
A fast and sensitive room-temperature graphene nanomechanical bolometer
Bolometers are a powerful means of detecting light. Emerging applications demand that bolometers work at room temperature, while maintaining high speed and sensitivity, properties which are inherently limited by the heat capacity of the detector. To this end, graphene has generated interest, because it has the lowest mass per unit area of any material, while also possessing extreme thermal stability and an unmatched spectral absorbance. Yet, due to its weakly temperature-dependent electrical resistivity, graphene has failed to challenge the state-of-the-art at room temperature. Here, in a departure from conventional bolometry, we use a graphene nanoelectromechanical system to detect light via resonant sensing. In our approach, absorbed light heats and thermally tensions a suspended graphene resonator, thereby shifting its resonant frequency. Using the resonant frequency as a readout for photodetection, we achieve a room-temperature noise-equivalent power (2 pW Hz −1/2 ) and bandwidth (from 10 kHz up to 1.3 MHz), challenging the state-of-the-art. Bolometers are highly sensitive instruments that can detect radiant energy. Here, authors report micro-bolometers based on suspended graphene nano-electromechanical membranes that can detect light at room-temperature with a NEP coefficient of 2 pW/Hz^1/2 and bandwidth up to 1.3 MHz.
Nanopore electro-osmotic trap for the label-free study of single proteins and their conformations
Many strategies have been pursued to trap and monitor single proteins over time to detect the molecular mechanisms of these essential nanomachines. Single-protein sensing with nanopores is particularly attractive because it allows label-free high-bandwidth detection on the basis of ion currents. Here we present the nanopore electro-osmotic trap (NEOtrap) that allows trapping and observing single proteins for hours with submillisecond time resolution. The NEOtrap is formed by docking a DNA-origami sphere onto a passivated solid-state nanopore, which seals off a nanocavity of a user-defined size and creates an electro-osmotic flow that traps nearby particles irrespective of their charge. We demonstrate the NEOtrap’s ability to sensitively distinguish proteins on the basis of size and shape, and discriminate between nucleotide-dependent protein conformations, as exemplified by the chaperone protein Hsp90. Given the experimental simplicity and capacity for label-free single-protein detection over the broad bio-relevant time range, the NEOtrap opens new avenues to study the molecular kinetics underlying protein function.A trap, formed by a DNA-origami sphere docked onto a solid-state nanopore, allows the hydrodynamic trapping and label-free observation of single proteins, enabling nucleotide-dependent protein conformation to be discriminated on the timescale of submilliseconds to hours.
Semiconductor-less vertical transistor with ION/IOFF of 106
Semiconductors have long been perceived as a prerequisite for solid-state transistors. Although switching principles for nanometer-scale devices have emerged based on the deployment of two-dimensional (2D) van der Waals heterostructures, tunneling and ballistic currents through short channels are difficult to control, and semiconducting channel materials remain indispensable for practical switching. In this study, we report a semiconductor-less solid-state electronic device that exhibits an industry-applicable switching of the ballistic current. This device modulates the field emission barrier height across the graphene-hexagonal boron nitride interface with I ON / I OFF of 10 6 obtained from the transfer curves and adjustable intrinsic gain up to 4, and exhibits unprecedented current stability in temperature range of 15–400 K. The vertical device operation can be optimized with the capacitive coupling in the device geometry. The semiconductor-less switching resolves the long-standing issue of temperature-dependent device performance, thereby extending the potential of 2D van der Waals devices to applications in extreme environments. In field-effect transistors, a semiconducting channel is indispensable for device switching. Here, the authors demonstrate semiconductor-less switching via modulation of the field emission barrier height across a graphene-hBN interface with ON/OFF ratio of 10 6 .
Spin-crossover nanoparticles anchored on MoS2 layers for heterostructures with tunable strain driven by thermal or light-induced spin switching
In the past few years, the effect of strain on the optical and electronic properties of MoS2 layers has attracted particular attention as it can improve the performance of optoelectronic and spintronic devices. Although several approaches have been explored, strain is typically externally applied on the two-dimensional material. In this work, we describe the preparation of a reversible ‘self-strainable’ system in which the strain is generated at the molecular level by one component of a MoS2-based composite material. Spin-crossover nanoparticles were covalently grafted onto functionalized layers of semiconducting MoS2 to form a hybrid heterostructure. Their ability to switch between two spin states on applying an external stimulus (light irradiation or temperature change) serves to generate strain over the MoS2 layer. A volume change accompanies this spin crossover, and the created strain induces a substantial and reversible change of the electrical and optical properties of the heterostructure.Spin-crossover nanoparticles have been covalently grafted onto a semiconducting MoS2 layer to form a self-strainable heterostructure. Under light or thermal stimulus, the nanoparticles switch between their high- and low-spin states, in which they have different volumes. This generates a reversible strain over the MoS2 layer and, in turn, alters the electrical and optical properties of the heterostructure.
Investigating compatibilization of polyoxymethylene/styrene-butadiene-styrene immiscible blend through addition of hydroxylated graphene
The main objective of this work was to use hydroxyl-functionalized graphene as a compatibilizer for an immiscible blend. A neat polyoxymethylene/styrene-butadiene-styrene binary blend was prepared at a constant ratio (80/20) and then was compounded with different loading amounts of hydroxyl-functionalized graphene (0.25, 0.5, 0.75, and 1 wt%). The formation of droplet-matrix morphology during blending was observed in microscopy images. A deep understanding of the compatibility was inspected through studying the mechanical, rheological, and microstructural properties. By inspecting the localization of nanoparticles, triple functions of hydroxyl-functionalized graphene as a compatibilizing/reinforcing/lubricating agent were elucidated. The mechanical properties showed that the best compatibility with the ultimate performance was related to the nanocomposite containing 0.25 wt%. Furthermore, the electrical conductivity of the prepared nanocomposites was investigated. Thermodynamic/kinetic studies showed the tendency of hydroxyl-functionalized graphene to disperse droplets, however as the loading value increases, the probability of its presence in the matrix also increases, creating conductive pathways for conductive purposes. The lowest resistance and highest volume of electrical conductivity (8.4 × 10 −6 S.cm −1 ) were shown by 1 wt% FG.
Efficient, fast and reabsorption-free perovskite nanocrystal-based sensitized plastic scintillators
The urgency for affordable and reliable detectors for ionizing radiation in medical diagnostics, nuclear control and particle physics is generating growing demand for scintillator devices combining efficient scintillation, fast emission lifetime, high interaction probability with ionizing radiation and mitigated reabsorption losses in large-volume/high-density detectors. To date, the simultaneous achievement of all such features is still an open challenge. Here we realize this regime with poly(methyl methacrylate) nanocomposites embedding CsPbBr3 perovskite nanocrystals as sensitizers for a conjugated organic dye featuring a large Stokes shift and a fast emission lifetime in the red spectral region. Complete energy transfer from the nanocrystals to the dye under both X-rays and α-particle excitation results in highly stable radioluminescence with an efficiency comparable to that of commercial-grade inorganic and plastic scintillators; an ~3.4 ns emission lifetime, competitive with fast lanthanide scintillators; and reabsorption-free waveguiding for long optical distances.Poly(methyl methacrylate) nanocomposites embedding CsPbBr3 perovskite nanocrystals can be used to simultaneously achieve optimized parameters in scintillator devices.