Responsive Polymers for Biosensing and Protein Delivery

In this feature article, we review some of the most recent advances in the field of materials chemistry for biosensing, disease diagnostics, and drug delivery. Our recent work on the development of responsive polymer-based platforms for biosensing and drug delivery will also be highlighted. This feature article is meant to outline the breadth of the utility of polymer-based materials for select applications, as well as their enormous potential impact on future technologies

Electron Bunch Train Excited Higher-Order Modes in a Superconducting RF Cavity

Higher-order mode (HOM) based intra-cavity beam diagnostics has been proved effectively and conveniently in superconducting radio-frequency (SRF) accelerators. Our recent research shows that the beam harmonics in the bunch train excited HOM spectrum, which have much higher signal-to-noise ratio than the intrinsic HOM peaks, may also be useful for beam diagnostics. In this paper, we will present our study on bunch train excited HOMs, including the theoretic model and recent experiments carried out based on the DC-SRF photoinjector and SRF linac at Peking University.Comment: Supported by National Natural Science Foundation of China (11275014

Defect-Free Plastic Deformation Through Dimensionality Reduction and Self-Annihilation of Topological Defects in Crystalline Solids

As a signature of symmetry-breaking processes, the generation and annihilation of topological defects (domain walls, strings, etc.) are of great interest in condensed matter physics and cosmology. Here we propose a distinctive self-organization process through phase transitions, in which all the generated topological defects are dimensionality reduced and self-annihilated. In crystalline solids, such a unique mechanism allows a perfect single crystal after plastic deformation, which originates from the coupling of different types of broken symmetries

Transcriptome and comparative gene expression analysis of Phyllostachys edulis in response to high light

The values of gene expression in Calvin cycle and photorespiratory metabolism. (XLSX 12 kb

Dynamic Graph Representation Learning for Video Dialog via Multi-Modal Shuffled Transformers

Given an input video, its associated audio, and a brief caption, the audio-visual scene aware dialog (AVSD) task requires an agent to indulge in a question-answer dialog with a human about the audio-visual content. This task thus poses a challenging multi-modal representation learning and reasoning scenario, advancements into which could influence several human-machine interaction applications. To solve this task, we introduce a semantics-controlled multi-modal shuffled Transformer reasoning framework, consisting of a sequence of Transformer modules, each taking a modality as input and producing representations conditioned on the input question. Our proposed Transformer variant uses a shuffling scheme on their multi-head outputs, demonstrating better regularization. To encode fine-grained visual information, we present a novel dynamic scene graph representation learning pipeline that consists of an intra-frame reasoning layer producing spatio-semantic graph representations for every frame, and an inter-frame aggregation module capturing temporal cues. Our entire pipeline is trained end-to-end. We present experiments on the benchmark AVSD dataset, both on answer generation and selection tasks. Our results demonstrate state-of-the-art performances on all evaluation metrics.Comment: Accepted at AAAI 202

Amylose-Derived Macrohollow Core and Microporous Shell Carbon Spheres as Sulfur Host for Superior Lithium–Sulfur Battery Cathodes

Porous carbon can be tailored to great effect for electrochemical energy storage. In this study, we propose a novel structured spherical carbon with a macrohollow core and a microporous shell derived from a sustainable biomass, amylose, by a multistep pyrolysis route without chemical etching. This hierarchically porous carbon shows a particle distribution of 2–10 μm and a surface area of 672 m2 g–1. The structure is an effective host of sulfur for lithium–sulfur battery cathodes, which reduces the dissolution of polysulfides in the electrolyte and offers high electrical conductivity during discharge/charge cycling. The hierarchically porous carbon can hold 48 wt % sulfur in its porous structure. The S@C hybrid shows an initial capacity of 1490 mAh g–1 and retains a capacity of 798 mAh g–1 after 200 cycles at a discharge/charge rate of 0.1 C. A capacity of 487 mAh g–1 is obtained at a rate of 3 C. Both a one-step pyrolysis and a chemical-reagent-assisted pyrolysis are also assessed to obtain porous carbon from amylose, but the obtained carbon shows structures inferior for sulfur cathodes. The multistep pyrolysis and the resulting hierarchically porous carbon offer an effective approach to the engineering of biomass for energy storage. The micrometer-sized spherical S@C hybrid with different sizes is also favorable for high-tap density and hence the volumetric density of the batteries, opening up a wide scope for practical applications

Amylose-Derived Macrohollow Core and Microporous Shell Carbon Spheres as Sulfur Host for Superior Lithium–Sulfur Battery Cathodes

Porous carbon can be tailored to great effect for electrochemical energy storage. In this study, we propose a novel structured spherical carbon with a macrohollow core and a microporous shell derived from a sustainable biomass, amylose, by a multistep pyrolysis route without chemical etching. This hierarchically porous carbon shows a particle distribution of 2–10 μm and a surface area of 672 m2 g–1. The structure is an effective host of sulfur for lithium–sulfur battery cathodes, which reduces the dissolution of polysulfides in the electrolyte and offers high electrical conductivity during discharge/charge cycling. The hierarchically porous carbon can hold 48 wt % sulfur in its porous structure. The S@C hybrid shows an initial capacity of 1490 mAh g–1 and retains a capacity of 798 mAh g–1 after 200 cycles at a discharge/charge rate of 0.1 C. A capacity of 487 mAh g–1 is obtained at a rate of 3 C. Both a one-step pyrolysis and a chemical-reagent-assisted pyrolysis are also assessed to obtain porous carbon from amylose, but the obtained carbon shows structures inferior for sulfur cathodes. The multistep pyrolysis and the resulting hierarchically porous carbon offer an effective approach to the engineering of biomass for energy storage. The micrometer-sized spherical S@C hybrid with different sizes is also favorable for high-tap density and hence the volumetric density of the batteries, opening up a wide scope for practical applications

Comprehensive quantification of height dependence of entrainment mixing between stratiform cloud top and environment

Different entrainment-mixing processes of turbulence are crucial to processes related to clouds; however, only a few qualitative studies have been concentrated on the vertical distributions of entrainment-mixing mechanisms with low vertical resolutions. To quantitatively study vertical profiles of entrainment-mixing mechanisms with a high resolution, the stratiform clouds observed in the Physics of Stratocumulus Top (POST) project are examined. The unique sawtooth flight pattern allows for an examination of the vertical distributions of entrainment-mixing mechanisms with a 5ĝ€¯m vertical resolution. Relative standard deviation of volume mean radius divided by relative standard deviation of liquid water content is introduced to be a new estimation of microphysical homogeneous mixing degree, to overcome difficulties of determining the adiabatic microphysical properties required in existing measures. The vertical profile of this new measure indicates that entrainment-mixing mechanisms become more homogeneous with decreasing altitudes and are consistent with the dynamical measures of Damköhler number and transition scale number. Further analysis shows that the vertical variation of entrainment-mixing mechanisms with decreasing altitudes is due to the increases of turbulent dissipation rate in cloud and relative humidity in droplet-free air and the decrease of size of droplet-free air. The results offer insights into the theoretical understanding and parameterizations of vertical variation of entrainment-mixing mechanisms

A mechanochemical synthesis of submicron-sized Li2S and a mesoporous Li2S/C hybrid for high performance lithium/sulfur battery cathodes

Lithium sulfide, Li2S, is a promising cathode material for lithium–sulfur batteries (LSBs), with a high theoretical capacity of 1166 mA h g−1. However, it suffers from low cycling stability, low-rate capability and high initial activation potential. In addition, commercially available Li2S is of high cost and of large size, over ten microns, which further exacerbate its shortcomings as a sulfur cathode. Exploring new approaches to fabricate small-sized Li2S of low cost and to achieve Li2S cathodes of high electrochemical performance is highly desired. This work reports a novel mechanochemical method for synthesizing Li2S of high purity and submicron size by ball-milling LiH with sulfur in an Ar atmosphere at room temperature. By further milling the as-synthesized Li2S with polyacrylonitrile (PAN) followed by carbonization of PAN at 1000 °C, a Li2S/C hybrid with nano-sized Li2S embedded in a mesoporous carbon matrix is achieved. The hybrid with Li2S as high as 74 wt% shows a high initial capacity of 971 mA h g−1 at 0.1C and retains a capacity of 570 mA h g−1 after 200 cycles as a cathode material for LSBs. A capacity of 610 mA h g−1 is obtained at 1C. The synthesis method of Li2S is facile, environmentally benign, and of high output and low cost. The present work opens a new route for the scalable fabrication of submicron-sized Li2S and for the development of high performance Li2S-based cathodes