Photonic-Plasmonic Coupling Enhanced Fluorescence Enabling Digital-Resolution Ultrasensitive Protein Detection

Assays utilizing fluorophores are common throughout life science research and diagnostics, although detection limits are generally limited by weak emission intensity, thus requiring many labeled target molecules to combine their output to achieve higher signal-to-noise. We describe how the synergistic coupling of plasmonic and photonic modes can significantly boost the emission from fluorophores. By optimally matching the resonant modes of a plasmonic fluor (PF) nanoparticle and a photonic crystal (PC) with the absorption and emission spectrum of the fluorescent dye, a 52-fold improvement in signal intensity is observed, enabling individual PFs to be observed and digitally counted, where one PF tag represents one detected target molecule. The amplification can be attributed to the strong near-field enhancement due to the cavity-induced activation of the PF, PC band structure-mediated improvement in collection efficiency, and increased rate of spontaneous emission. The applicability of the method by dose-response characterization of a sandwich immunoassay for human interleukin-6, a biomarker used to assist diagnosis of cancer, inflammation, sepsis, and autoimmune disease is demonstrated. A limit of detection of 10 fg mL⁻¹ and 100 fg mL⁻¹ in buffer and human plasma respectively, is achieved, representing a capability nearly three orders of magnitude lower than standard immunoassays.     

Rapid Detection of Biomolecules in a Junction Less Tunnel Field-Effect Transistor (JL-TFET) Biosensor

Silicon - In this paper, we present a double gate JL-TFET based biosensor by varying the gate dielectric constant to detect various biomolecules through label-free detection technique. An...     

Improvement of Ion,Electric Field and Transconductance of TriGate FinFET by 5nm Technology

Silicon - In present days, the improved performance in nanoscale dimensions is of enormous need than conventional CMOS devices. This paper presents an insight into Trigate FinFET in 5 nm technology...     

A note on the existence and optimal control for mixed Volterra–Fredholm-type integrodifferential dispersion system of third order

The optimal control problem consists of a performance index subject to a set of differential equations that describes the path of the control and state variables. The main aim of this article is to prove the existence and uniqueness of a mild solution, optimal control, and time-optimal control of a mixed Volterra–Fredholm-type third-order dispersion system. By applying the strongly continuous semigroup theory and the Banach fixed-point theorem, we prove the existence and uniqueness of the considered system. The optimal control results are proved by using Mazur's lemma, Gronwall's inequality, and the minimizing sequence technique. The discussion on the time-optimal control of the third-order dispersion system is also presented.     

Polypyridyl CoII-Curcumin Complexes as Photoactivated Anticancer and Antibacterial Agents

Four new Co^II complexes, [Co(bpy)₂(acac)]Cl ( 1 ), [Co(phen)₂(acac)]Cl ( 2 ), [Co(bpy)₂(cur)]Cl ( 3 ), [Co(phen)₂(cur)]Cl ( 4 ), where bpy=2,2’-bipyridine ( 1 and 3 ), phen=1,10-phenanthroline ( 2 and 4 ), acac = acetylacetonate ( 1 and 2 ), cur=curcumin monoanion ( 3 and 4 ) have been designed, synthesized and fully characterized. The X-ray crystal structures of 1 and 2 indicated that the CoN₄O₂ core has a distorted octahedral geometry. The photoactivity of these complexes was tuned by varying the π conjugation in the ligands. Curcumin complexes 3 and 4 had an intense absorption band near 435 nm, which made them useful as visible-light photodynamic therapy agents; they also showed fluorescence with λ_em≈565 nm. This fluorescence was useful for studying their intracellular uptake and localization in MCF-7 breast cancer cells. The acetylacetonate complexes ( 1 and 2 ) were used as control complexes to understand the role of curcumin. The white-light-triggered anticancer profiles of the cytosol targeting complexes 3 and 4 were investigated in detail. These non-dark toxic complexes displayed significant apoptotic photo-cytotoxicity (under visible light) against MCF-7 cells through ROS generation. The control complexes 1 and 2 did not induce significant cell death in the light or dark. Interestingly, 1-4 produced a remarkable antibacterial response upon light exposure. Overall, the reported results here can increase the boundary of the Co^II-based anticancer and antibacterial drug development.     

Synthesis and Characterization of ZnO/CuO Nanocomposites as an Effective Photocatalyst and Gas Sensor for Environmental Remediation

Journal of Inorganic and Organometallic Polymers and Materials - Current study delineates the synthesis and environmental applications of ZnO/CuO nanocomposite in photocatalysis and gas sensing....     

Machinability and surface morphology investigations of multiwall carbon nanotube reinforced aluminium 7075 metal matrix composite during electrical discharge machining: A grey relational approach

Multiwall carbon nanotube buttressed aluminium 7075 metal matrix composite was synthesized through an amended liquid metallurgy method, which consisted semisolid stirring, ultrasonic treatment and squeeze casting. Aim was to investigate its machinability and surface morphology during electrical discharge machining. Variable machining factors were peak current, pulse-on time and gap voltage, whereas the responses under investigation were electrode wear rate, material removal rate and average surface roughness. Results revealed electrode wear rate, material wear rate and average surface roughness increased on increasing peak current and pulse-on time, but all these responses behaved inversely with the increase of gap voltage. Average surface roughness reduced by around 44 % on reducing the peak current from 10 A to 4 A and increasing gap voltage from 55 V to 80 V at constant pulse-on time of 300 μs; however, it increased by around 25 % on reducing the gap voltage from 80 V to 55 V and increasing the pulse-on time from 100 μs to 300 μs at constant peak current of 10 A. Significance of the process parameters were verified, regression models were developed and morphology of the machined surfaces was studied. Finally, multiple response optimization was conducted following grey relational approach.     

Effects of initial α-phase content on properties of pressureless solid-state sintered SiC ceramics

α- and β-SiC starting powders of similar particle sizes were used to investigate the effect of initial α-phase content on the electrical, thermal, and mechanical properties of pressureless solid-state sintered (PSS) SiC ceramics with B₄C and C additives. For β-SiC starting powders, a coarse-grained microstructure with elongated platelet grains was formed by the transformation of 3C to 6H and finally to 4H-SiC phase. In contrast, materials prepared from α-SiC powders exhibited a fine-grained microstructure with platelet grains. This study revealed the beneficial effect of α-SiC starting powders in achieving low electrical resistivity and high thermal conductivity in PSS SiC ceramics, which was attributable to their higher sinterability, lower impurity content, and lower 6H to 4H-SiC phase transformation rate compared with β-SiC powders. The electrical resistivity decreased by an order of magnitude and the thermal conductivity increased by 32% with an increase in initial α-phase content from 0 to 100%. The flexural strength increased by approximately 16% with increasing initial α-phase content due to a decreased flaw size with decreasing grain size. However, the fracture toughness and hardness were insensitive to the change in initial α-phase content.     

Integration of an Axially Continuous Graphene with Functional Metals for High-Temperature Electrical Conductors

Demands for effective high-temperature electrical conductors continue to increase with the rapid adoption of electric vehicles. However, the use of conventional copper-based conductors is limited to relatively low temperatures due to their poor oxidation resistance and microstructural instability. Here, a highly conductive and thermally stable nickel-graphene-copper (NiGCu) wire that combines the advantages of graphene and its metallic components is developed. The NiGCu wire consists of a conductive copper core, an oxidation-resistant nickel shell, and axially continuous graphene embedded between them. The experiments on 10–80 µm diameter NiGCu wires demonstrate substantial enhancements in electrical properties and thermal stability across a variety of metrics. For instance, the smallest NiGCu wires have a 61.2% higher current density limit, 307.6% higher conductivity, and an order of magnitude smaller change in resistivity compared to conventional Ni-coated Cu counterparts after annealing at 650 °C. By performing both innovative experiments and simulations using different sizes of NiGCu wires, the diffusion coefficients of metals are quantified, for the first time to the best knowledge, through continuous graphene. These results indicate that the dramatic improvement in thermo-electrical properties is enabled by the embedded graphene layer which reduces Ni Cu interdiffusion by ≈10⁴ times at 550 °C and 650 °C.