Time irregularity of generalized Ornstein--Uhlenbeck processes

The paper is concerned with the properties of solutions to linear evolution equation perturbed by cylindrical L\'evy processes. It turns out that solutions, under rather weak requirements, do not have c\`adl\`ag modification. Some natural open questions are also stated

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

First published online: 26 Feb 2016Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons. This fundamentally interesting process has many applications in biomedical imaging, light source and display technology, and solar energy harvesting. In this review we discuss the underlying physical principles and their modelling using rate equations. We discuss how the understanding of photophysical processes enabled a strategic influence over the optical properties of upconversion especially in rationally designed materials. We subsequently present an overview of recent experimental strategies to control and optimize the optical properties of upconversion nanoparticles, focussing on their emission spectral properties and brightness.Annemarie Nadort, Jiangbo Zhao and Ewa M. Goldy

Non-specific cellular uptake of surface-functionalized quantum dots

We report a systematic empirical study of nanoparticle internalization into cells via non-specific pathways. The nanoparticles were comprised of commercial quantum dots (QDs) that were highly visible under a fluorescence confocal microscope. Surface-modified QDs with basic biologically-significant moieties, e.g. carboxyl, amino, streptavidin were used, in combination with the surface derivatization with polyethylene glycol (PEG) in a range of immortalized cell lines. Internalization rates were derived from image analysis and a detailed discussion about the effect of nanoparticle size, charge and surface groups is presented. We find that PEG-derivatization dramatically suppresses the non-specific uptake while PEG-free carboxyl and amine functional groups promote QD internalization. These uptake variations displayed a remarkable consistency across different cell types. The reported results are important for experiments concerned with cellular uptake of surface-functionalized nanomaterials, both when non-specific internalization is undesirable and also when it is intended for material to be internalized as efficiently as possible. Published article at: http://iopscience.iop.org/0957-4484/21/28/285105/Comment: 14 pages 7 figure

A pricing formula for delayed claims: appreciating the past to value the future

We consider the valuation of contingent claims with delayed dynamics in a Samuelson complete market model. We find a pricing formula that can be decomposed into terms reflecting the current market values of the past and the future, showing how the valuation of prospective cashflows cannot abstract away from the contribution of the past. As a practical application, we provide an explicit expression for the market value of human capital in a setting with wage rigidity. The formula we derive has successfully been used to explicitly solve the infinite dimensional stochastic control problems addressed in [7], [6] and [16]

Sensitive cytokine assay based on optical fiber allowing localized and spatially resolved detection of interleukin-6

We demonstrated a cytokine detection device based on gold nanoparticle modified silica optical fiber for the monitoring of locally variable cytokine interleukin-6 (IL-6) concentrations using a sandwich immunoassay scheme. The fiber is designed to be introduced into an intrathecal catheter with micrometer-sized holes drilled along its length to enable fluid exchange between the outside and inside of the catheter. An exposed optical fiber (diameter 125 μm) modified with a layer of gold nanoparticles was functionalized with the IL-6 capture antibody to form the sensing interface. The immunocapture device was incubated with a cytokine solution to capture the analyte. The device was then exposed to the IL-6 detection antibody which was loaded on the fluorescently labeled magnetic nanoparticles, making it possible to quantify the cytokine concentration based on the intensity of fluorescence. A reliable method for quantifying the fluorescent signal on a 3D structure was developed. This device was applied to the detection of cytokine IL-6 with the low limit of detection of 1 pg mL⁻¹ in a sample volume of 1 μL. The device has the linear detection range of 1–400 pg mL⁻¹ and spatial resolution on the order of 200–450 μm, and it is capable of detecting localized IL-6 secreted by live BV2 cells following their liposaccharide stimulation. This biological detection system is suitable for monitoring multiple health conditions.Guozhen Liu, Kaixin Zhang, Annemarie Nadort, Mark R. Hutchinson, and Ewa M. Goldy

Recent advances in cytokine detection by immunosensing

Abstract not availableGuozhen Liu, Meng Qi, Mark R. Hutchinson, Guangfu Yang, Ewa M. Goldy

Doping effect on dark currents in In₀.₅Ga₀.₅As∕GaAs quantum dot infrared photodetectors grown by metal-organic chemical vapor deposition

Stacked self-assembled In₀.₅Ga₀.₅As∕GaAs quantum dot infrared photodetectors grown by low-pressure metal-organic chemical vapor deposition, with and without silicon dopants in the quantum dot layers, are investigated. The increase of dark currents observed at higher doping levels is attributed to higher defect density leading to stronger sequential resonant tunneling and to lowering of the operating temperature of the device

X-ray induced singlet oxygen generation by nanoparticle-photosensitizer conjugates for photodynamic therapy: determination of singlet oxygen quantum yield.

Singlet oxygen is a primary cytotoxic agent in photodynamic therapy. We show that CeF3 nanoparticles, pure as well as conjugated through electrostatic interaction with the photosensitizer verteporfin, are able to generate singlet oxygen as a result of UV light and 8 keV X-ray irradiation. The X-ray stimulated singlet oxygen quantum yield was determined to be 0.79 ± 0.05 for the conjugate with 31 verteporfin molecules per CeF3 nanoparticle, the highest conjugation level used. From this result we estimate the singlet oxygen dose generated from CeF3-verteporfin conjugates for a therapeutic dose of 60 Gy of ionizing radiation at energies of 6 MeV and 30 keV to be (1.2 ± 0.7) × 10(8) and (2.0 ± 0.1) × 10(9) singlet oxygen molecules per cell, respectively. These are comparable with cytotoxic doses of 5 × 10(7)-2 × 10(9) singlet oxygen molecules per cell reported in the literature for photodynamic therapy using light activation. We confirmed that the CeF3-VP conjugates enhanced cell killing with 6 MeV radiation. This work confirms the feasibility of using X- or γ- ray activated nanoparticle-photosensitizer conjugates, either to supplement the radiation treatment of cancer, or as an independent treatment modality

A pricing formula for delayed claims: appreciating the past to value the future

We consider the valuation of contingent claims with delayed dynamics in a Samuelson complete market model. We find a pricing formula that can be decomposed into terms reflecting the current market values of the past and the future, showing how the valuation of prospective cashflows cannot abstract away from the contribution of the past. As a practical application, we provide an explicit expression for the market value of human capital in a setting with wage rigidity. The formula we derive has successfully been used to explicitly solve the infinite dimensional stochastic control problems addressed in Biffis et al. (SIAM J Control Optim 58(4):1906–1938, 2020), Djeiche et al. (Stoch Process Appl 145:48–85, 2022) and Biagini et al. (SIAM J Financial Math 13(3):1004–1039, 2022)