Comparative analysis of phase extraction methods based on phase-stepping and shifting curve in grating interferometry

Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.

Highly-Sensitive Multiplexed in vivo Imaging Using PEGylated Upconversion Nanoparticles

Lanthanide-based upconversion nanoparticles(UCNPs)have been widely explored in various fields,including optical imaging,in recent years.Although earlier work has shown that UCNPs with different lanthanide(Ln3+)dopants exhibit various colors,multicolor-especially in vivo multiplexed biomedical imaging-using UCNPs has rarely been reported.In this work,we synthesize a series of UCNPs with different emission colors and functionalize them with an amphiphilic polymer to confer water solubility.Multicolor in vivo upconversion luminescence(UCL)imaging is demonstrated by imaging subcutaneously injected UCNPs and applied in multiplexed in vivo lymph node mapping.We also use UCNPs for multicolor cancer cell labeling and realize in vivo cell tracking by UCL imaging.Moreover,for the first time we compare the in vivo imaging sensitivity of quantum dot(QD)-based fluorescence imaging and UCNP-based UCL imaging side by side,and find the in vivo detection limit of UCNPs to be at least one order of magnitude lower than that of QDs in our current non-optimized imaging system.Our data suggest that,by virtue of their unique optical properties,UCNPs have great potential for use in highly-sensitive multiplexed biomedical imaging.

Flexible optoelectronic neural transistors with broadband spectrum sensing and instant electrical processing for multimodal neuromorphic computing

A flexible optoelectronic neural transistor(OENT)that consists of a one‐step spin‐coated tri‐blend film composed of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene(C8‐BTBT),poly(3‐hexylthiophene‐2,5‐diyl)(P3HT),and poly(methyl methacrylate)(PMMA)is demonstrated.The C8‐BTBT and P3HT phases in the film partially segregate into distinct domains,which combine to provide broadband spectrum sensing,and instant electrical‐processing capabilities dominated by C8‐BTBT.The OENT is sensitive to solar radiation from the near‐ultraviolet(NUV)and to visible(Vis)radiation from blue to red.When exposed to NUV radiation,the OENT responds sensitively and retains the memory of the exposure for over 10^(3 )s.The OENT provides a warning of excessive chronic exposure to harmful NUV.These properties allow high‐pass filtering with different cut‐off frequencies fc that can restrict the reception of blue,green,or red.These switchable fc enables sensitive image reconstruction and multitarget monitoring.The device combined with a chitosan gel achieves strictly defined short‐range plasticity of<1 s that can achieve diverse instant‐computing applications such as spatiotemporally correlated coding and logic functions.Stable real‐time signal processing facilitates the realization of a Morse‐code recognition system constructed using neuro‐morphological hardware,achieving highly accurate character recognition.This study provides a useful resource that can have applications in wearable biomedical electronics and multimodal neuromorphic computing.

High sensitivity and high selectivity terahertz biomedical imaging

We demonstrate two distinct emerging terahertz （THz） biomedical imaging techniques.One is based on the use of a new single frequency THz quantum cascade laser and the other is based on broadband THz time domain spectrocopy.The first method is employed to derive a metastasis lung tissue imaging at 3.7 THz with clear contrast between cancerous and healthy areas.The second approach is used to study an osseous tissue under several imaging modalities and achieve full THz spectroscopic imaging based on the frequency domain or on a fixed THz propagation time-delay.Sufficient contrast is achieved which facilitated the identification of regions with different cellular types and density compositions.