Xiaogang Liu

Bio: Xiaogang Liu is an academic researcher from National University of Singapore. The author has contributed to research in topics: Medicine & Photon upconversion. The author has an hindex of 94, co-authored 425 publications receiving 41825 citations. Previous affiliations of Xiaogang Liu include Heilongjiang University & Massachusetts Institute of Technology.

Dynamic upconversion multicolour editing enabled by molecule-assisted opto-electrochemical modulation.

Abstract: Controlling nonlinear optical signals electrically offers many opportunities for technological developments. Lanthanide-activated nanoparticles have recently emerged as leading platforms for nonlinear upconversion of infra-red excitation within nanometric volumes. However, manipulation of upconversion emission is restricted to varying percentages of component materials, nanocrystal structure, and optical pumping conditions. Here, we report temporal modulation of anti-Stokes luminescence by coupling upconversion nanoparticles with an electrochemically responsive molecule. By electrically tailoring orbital energy levels of the molecules anchored on nanoparticle surfaces, we demonstrate reversible control of molecular absorption, resulting in dynamic colour editing of anti-Stokes luminescence at single-particle resolution. Moreover, we show that a programmable logic gate array based on opto-electrochemical modulation can be constructed to convert information-encrypted electrical signals into visible patterns with millisecond photonic readout. These findings offer insights into precise control of anti-Stokes luminescence, while enabling a host of applications from low-threshold infrared logic switches to multichannel, high-fidelity photonic circuits. Though upconversion nanoparticles (UCNPs) are attractive for infrared detecting and modulating photonic devices, devising strategies to electrically manipulate upconversion emission remain a challenge. Here, the authors report molecule-assisted opto-electrochemical modulation of UCNP luminescence.

Spin-Orbit Torque-Induced Domain Nucleation for Neuromorphic Computing

Abstract: Neuromorphic computing has become an increasingly popular approach for artificial intelligence because it can perform cognitive tasks more efficiently than conventional computers. However, it remains challenging to develop dedicated hardware for artificial neural networks. Here, a simple bilayer spintronic device for hardware implementation of neuromorphic computing is demonstrated. In L11 -CuPt/CoPt bilayer, current-inducted field-free magnetization switching by symmetry-dependent spin-orbit torques shows a unique domain nucleation-dominated magnetization reversal, which is not accessible in conventional bilayers. Gradual domain nucleation creates multiple intermediate magnetization states which form the basis of a sigmoidal neuron. Using the L11 -CuPt/CoPt bilayer as a sigmoidal neuron, the training of a deep learning network to recognize written digits, with a high recognition rate (87.5%) comparable to simulation (87.8%) is further demonstrated. This work offers a new scheme of implementing artificial neural networks by magnetic domain nucleation.

Expanding the toolbox for lanthanide-doped upconversion nanocrystals

Abstract: The ability to convert low-energy quanta into a quantum of higher energy is critical for a variety of applications, including photovoltaics, volumetric display, bioimaging, multiplexing sensing, super-resolution imaging, optogenetics, and potentially many others. Although the processes of second harmonic generation and multiphoton (or two-photon) absorption can be used to generate photon upconversion, lanthanide-doped upconversion nanocrystals have emerged as an attractive alternative for nonlinear upconversion of near-infrared light with pump intensities several orders of magnitude lower than required by conventional nonlinear crystals. Over the past five years, considerable efforts have been made to tune the photoluminescence of upconversion nanocrystals, and significant progress has been achieved. In this review, we focus on manipulation of the wavelength, emission intensity and lifetime of upconversion nanocrystals. Here, we outline the fundamental principle for the upconversion phenomenon, review the current experimental state-of-the-art for controlling photon upconversion in lanthanidedoped nanocrystals and highlight the prospects for multifunctional upconversion nanocrystals currently in development.

An Ultrahigh Rate and Stable Zinc Anode by Facet‐Matching‐Induced Dendrite Regulation

Abstract: Resource‐abundant metal (e.g., zinc) batteries feature intrinsic advantages of safety and sustainability. Their practical feasibility, however, is impeded by the poor reversibility of metal anodes, typically caused by the uncontrollable dendrite enlargement. Significant effort is exerted to completely prevent dendrites from forming, but this seems less effective at high current densities. Herein, this work presents an alternative dendrite regulation strategy of forming tiny, homogeneously distributed, and identical zinc dendrites by facet matching, which effectively avoids undesirable dendrite enlargement. Confirmed by multiscale theoretical screening and characterization, the regularly exposed Cu(111) facets at the ridges of a copper nanowire are capable of such dendrite regulation by forming a low‐mismatched Zn(002)/Cu(111) interface. Consequently, reversible zinc electroplating/stripping is achieved at an unprecedentedly high rate of 100 mA cm−2 for over 30 000 cycles, corresponding to an accumulative areal capacity up to 30 Ah cm−2. A full cell using this anode shows a high capacity of 308.3 mAh g−1 and a high capacity retention of 91.4% after 800 cycles. This strategy is also viable for magnesium and aluminum anodes, thus opening up a promising and universal avenue toward long‐life and high‐rate metal anodes.

Replication study of candidate genes/loci associated with osteoporosis based on genome-wide screening.

Abstract: Summary Osteoporosis is a major public health problem characterized by low bone mineral density (BMD). This replication study confirmed 38 single-nucleotide polymorphisms (SNPs) out of 139 SNPs previously reported in three recent genome-wide association studies (GWASs) in an independent US white sample. Ten SNPs achieved combined p < 3.6 × 10−4.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Room-temperature ultraviolet nanowire nanolasers

Abstract: Room-temperature ultraviolet lasing in semiconductor nanowire arrays has been demonstrated The self-organized, oriented zinc oxide nanowires grown on sapphire substrates were synthesized with a simple vapor transport and condensation process These wide band-gap semiconductor nanowires form natural laser cavities with diameters varying from 20 to 150 nanometers and lengths up to 10 micrometers Under optical excitation, surface-emitting lasing action was observed at 385 nanometers, with an emission linewidth less than 03 nanometer The chemical flexibility and the one-dimensionality of the nanowires make them ideal miniaturized laser light sources These short-wavelength nanolasers could have myriad applications, including optical computing, information storage, and microanalysis

Structural absorption by barbule microstructures of super black bird of paradise feathers

Abstract: Many studies have shown how pigments and internal nanostructures generate color in nature. External surface structures can also influence appearance, such as by causing multiple scattering of light (structural absorption) to produce a velvety, super black appearance. Here we show that feathers from five species of birds of paradise (Aves: Paradisaeidae) structurally absorb incident light to produce extremely low-reflectance, super black plumages. Directional reflectance of these feathers (0.05-0.31%) approaches that of man-made ultra-absorbent materials. SEM, nano-CT, and ray-tracing simulations show that super black feathers have titled arrays of highly modified barbules, which cause more multiple scattering, resulting in more structural absorption, than normal black feathers. Super black feathers have an extreme directional reflectance bias and appear darkest when viewed from the distal direction. We hypothesize that structurally absorbing, super black plumage evolved through sensory bias to enhance the perceived brilliance of adjacent color patches during courtship display.