Seeking sustainable solutions for human food systems

Sustainable food system development is the cornerstone of global human survival and development.This research briefly analyzes the challenges facing the current food system,summarizes the directions of food system trans-formation,expounds the role of geography in the transformation of food system,and discusses the future paths to promote the sustainable development of food system.The main conclusions are as follows:1)The interaction of factors such as regional conflicts,climate change,slowdown in development,raging epidemics,and resource and environmental constraints pose multiple challenges to the global food system.2)The food system should be high-quality,efficient,nutritious and healthy,green and low-carbon,inclusive and inclusive transformation.3)Geography can provide solutions for the transformation of food systems.4)The transformation paths of the food system includes:establishing a global food system with benefit sharing,cleaner production,and fair participation,improving the innovation capability of the food system,and establishing an effective organizational guarantee system.

Rabi Oscillations and Coherence Dynamics in Terahertz Streaking-Assisted Photoelectron Spectrum

We present an approach,a Terahertz streaking-assisted photoelectron spectrum(THz SAPS),to achieve direct observations of ultrafast coherence dynamics with timescales beyond the pulse duration.Using a 24 fs probe pulse,the THz SAPS enables us to well visualize Rabi oscillations of 11.76 fs and quantum beats of 2.62 fs between the 5S_(1/2) and 5P_(3/2) in rubidium atoms.The numerical results show that the THz SAPS can simultaneously achieve high resolution in both frequency and time domains without the limitation of Heisenberg uncertainty of the probe pulse.The long probe pulse promises sufficiently high frequency resolution in photoelectron spectroscopy allowing to observe Autler-Townes splittings,whereas the streaking THz field enhances temporal resolution for not only Rabi oscillations but also quantum beats between the ground and excited states.The THz SAPS demonstrates a potential applicability for observation and manipulation of ultrafast coherence processes in frequency and time domains.

Role of local coordination in bimetallic sites for oxygen reduction: A theoretical analysis

Understanding of the oxygen reduction reaction(ORR)mechanism for single atom catalysts is pivotal for the rational design of non-precious metal cathode materials and the commercialization of fuel cells.Herein,a series of non-precious metal electrocatalysts based on nitrogen-doped bimetallic(Fe and Co)carbide were modeled by density functional theory calculations to predict the corresponding reaction pathways.The study elucidated prior oxygen adsorption on the Fe atom in the dual site and the modifier role of Co atoms to tune the electronic structures of Fe.The reaction activity was highly correlated with the bimetallic center and the coordination environment of the adjacent nitrogen.Interestingly,the preadsorption of*OH resulted in the apparent change of metal atoms'electronic states with the d-band center shifting toward the Fermi level,thereby boosting reaction activity.The result should help promote the fundamental understanding of active sites in ORR catalysts and provide an effective approach to the design of highly efficient ORR catalysts on an atomic scale.

Global practical stabilization of the double integrator system with an imperfect sensor and subject to a bounded disturbance

This paper is concerned with global practical stabilization of the double integrator system with an imperfect sensor and subject to an additive bounded output disturbance.The imperfect sensor nonlinearity possesses the nonlinear characteristics of saturation and dead zone.Because of the presence of output dead zone and the additive disturbance,the states cannot be expected to driven into an arbitrarily small neighborhood of the origin.To solve the global practical stabilization problem,we proposes a low gain-based linear dynamic output feedback law,under which the first state enters and remains in a bounded set whose size is depended on the bound of disturbance and the range of dead zone and the second state enters and remains in a pre-specified arbitrarily small set,both in finite time.Simulation results illustrate the effectiveness of our proposed control method.

Migrasomes released by HSV-2-infected cells serve as a conveyance for virus spread

Dear Editor,Migrasomes are newly discovered cellular organelles with diameters of 0.5–3μm which have been found to be produced by normal and cancer cells,and distributed in various organs of animals(Ma et al.,2015)and in human sera(Zhao et al.,2019).Migrasomes are present inside the cavities of pulmonary alveoli,blood vessels and lymph capillaries(Zhang et al.,2020),and can be captured by surrounding cells with their cargoes internalized.

Molecular studies of cellulose synthase supercomplex from cotton fiber reveal its unique biochemical properties

Cotton fiber is a highly elongated and thickened single cell that produces large quantities of cellulose,which is synthesized and assembled into cell wall microfibrils by the cellulose synthase complex(CSC).In this study,we report that in cotton(Gossypium hirsutum)fibers harvested during secondary cell wall(SCW)synthesis,GhCesA 4,7,and 8 assembled into heteromers in a previously uncharacterized 36-mer-like cellulose synthase supercomplex(CSS).This super CSC was observed in samples prepared using cotton fiber cells harvested during the SCW synthesis period but not from cotton stem tissue or any samples obtained from Arabidopsis.Knock-out of any of GhCesA 4,7,and 8 resulted in the disappearance of the CSS and the production of fiber cells with no SCW thickening.Cotton fiber CSS showed significantly higher enzyme activity than samples prepared from knock-out cotton lines.We found that the microfibrils from the SCW of wild-type cotton fibers may contain 72 glucan chains in a bundle,unlike other plant materials studied.GhCesA4,7,and 8 restored both the dwarf and reduced vascular bundle phenotypes of their orthologous Arabidopsis mutants,potentially by reforming the CSC hexamers.Genetic complementation was not observed when non-orthologous CesA genes were used,indicating that each of the three subunits is indispensable for CSC formation and for full cellulose synthase function.Characterization of cotton CSS will increase our understanding of the regulation of SCW biosynthesis.

A triboelectric nanogenerator based oncosmetic fixing powder for mechanicalenergy harvesting

In this work,we use commercial powder particulates(a cosmetic fixing powder)as triboelectric materials for constructing a triboelectric nanogenerator(CFP-TENG).Through finger pressing,the CFP-TENG generated approximate open-circuit voltage,short-circuit current,and maximum power density values of 1141 V,521μA,and 570.96μW/cm^(2),respectively.Thirty-seven commercial blue LEDs can be easily lit up by the CFP-TENG.Moreover,this TENG,which was designed as a novel palette structure for harvesting mechanical energy from bicycle motion,serves as a self-powered bicycle speed sensor.In addition,the cosmetic fixing powder can be used as an effective material to enhance the triboelectric property of skin.This study provides an effective method for developing a cost-effective TENG without the use of complex surface micro-/nano-texturing.

Precisely installing gold nanoparticles at the core/shell interface of micellar assemblies of triblock copolymers

Two reduction-cleavable ABA triblock copolymers possessing two disulfide linkages,PMMA-ssPMEO3MA-ss-PMMA and PDEA-ss-PEO-ss-PDEA were synthesized via facile substitution reactions from homopolymer precursors,where PMMA,PMEO3MA,PDEA,and PEO represent poly（methyl methacrylate）,poly（tri（ethylene glycol） monomethyl ether methacrylate,poly（2-（diethylamino）ethyl methacrylate）,and poly（ethylene oxide）,respectively.Spherical micelles were obtained through supramolecular self-assembly of these two triblock copolymers in aqueous solutions.The resultant micelles with abundant disulfide bonds could serve as soft templates and precisely accommodate gold nanoparticles in the core/shell interface as a result of the formation of Au-S bonds.

Blood pressure monitoring via double sandwich-structured triboelectric sensors and deep learning models

Real-time blood pressure monitoring is essential for the timely diagnosis and treatment of cardiovascular disease.Many traditional prediction methods estimate blood pressure by measuring multiple sets of physiological signals with energyconsuming sensors.Herein,a continuous,cuffless and self-powered blood pressure monitoring system was developed based on a new double sandwich-structured triboelectric sensor and a novel blood pressure method estimation.A pyramid-patterned sensor based on the double sandwich structure realizes a sensitivity of 0.89 V/kPa in a linear range of 0–35 kPa,which is more than twice of the conventional single electrode structure.The sensor processes a low pressure detection limit of 1 g andfast response time of 32 ms.Hence,it can easily capture the pulse signal at the radial artery.Furthermore,a novel method for estimating blood pressure using pulse waves accompanied by the user’s background information was proposed.This method measures only one set of pulse signals and is portable.A deep learning model with multi-network structures was developed to improve the estimation accuracy.The mean absolute error and standard deviation of error for systolic and diastolic blood pressure(SBP and DBP)estimations were 3.79±5.27 and 3.86±5.18 mmHg,respectively.This work reveals a new sensing structure of triboelectric sensors and offers a novel method for blood pressure estimation.