糙米发酵滤液——一种具有抗衰老潜力的物质

本研究以糙米水为底物,通过微生物发酵技术制备了糙米发酵滤液。通过对比发酵前后滤液,发现发酵可以增加可溶性固形物以及小分子物质含量。通过人类永生化表皮细胞(HaCaT)活性实验及DPPH自由基清除实验对发酵前后滤液进行功效比较。发酵前糙米滤液只有较弱的DPPH自由基清除能力,而糙米发酵滤液具有较强的DPPH自由基清除能力,并能提高HaCaT细胞活性。进一步研究发现,糙米发酵滤液能够减少细胞内ROS生成、提高细胞自噬标记物LC3B表达、以及减少糖化导致的Ⅰ型胶原蛋白流失。当作用于HaCaT细胞时能够促进透明质酸(HA)的生成和其受体CD44的表达。当作用于人原代成纤维细胞(FB)时能够促进胶原蛋白的生成。本研究表明,糙米发酵滤液具有多方面抗衰老的潜在能力。

Controllable synthesis of grain boundary-enriched Pt nanoworms decorated on graphitic carbon nanosheets for ultrahigh methanol oxidation catalytic activity

Although one-dimensional Pt nanocrystals have long been regarded as ideal electrode catalysts for fuel cells,the synthetic techniques commonly involve the use of various complicated templates or surfactants,which have largely hampered their large-scale industrial application.Herein,we present a convenient and cost-effective approach to the stereoassembly of quasi-one-dimensional grain boundary-enriched Pt nanoworms on nitrogen-doped low-defect graphitic carbon nanosheets(Pt NWs/NL-CNS).Benefiting from its numerous catalytically active grain boundaries as well as optimized electronic structure,the as-derived Pt NWs/NL-CNS catalyst possesses exceptionally good electrocatalytic properties for methanol oxidation,including an ultrahigh mass activity of 1949.5 mA mg^(-1), reliable long-term durability,and strong poison tolerance,affording one of the most active Pt-based electrocatalysts for methanol oxidation reaction.Density functional theory calculation further reveals that the formation of worm-shape Pt morphology is attributed to the modified electronic structure as well as controllable defect density of the carbon matrix,which could also weaken the adsorption ability of Pt towards CO molecule and meanwhile synergistically promotes the catalytic reaction kinetics.

Genome and transcriptome of Papaver somniferum Chinese landrace CHM indicates that massive genome expansion contributes to high benzylisoquinoline alkaloid biosynthesis

Opium poppy(Papaver somniferum)is a source of morphine,codeine,and semisynthetic derivatives,including oxycodone and naltrexone.Here,we report the de novo assembly and genomic analysis of P.somniferum traditional landrace‘Chinese Herbal Medicine’.Variations between the 2.62 Gb CHM genome and that of the previously sequenced high noscapine 1(HN1)variety were also explored.Among 79,668 protein-coding genes,we functionally annotated 88.9%,compared to 68.8%reported in the HN1 genome.Gene family and 4DTv comparative analyses with three other Papaveraceae species revealed that opium poppy underwent two whole-genome duplication(WGD)events.The first of these,in ancestral Ranunculales,expanded gene families related to characteristic secondary metabolite production and disease resistance.The more recent species-specific WGD mediated by transposable elements resulted in massive genome expansion.Genes carrying structural variations and large-effect variants associated with agronomically different phenotypes between CHM and HN1 that were identified through our transcriptomic comparison of multiple organs and developmental stages can enable the development of new varieties.These genomic and transcriptomic analyses will provide a valuable resource that informs future basic and agricultural studies of the opium poppy.

Influence of particle size and ionic strength on the freeze-thaw stability of emulsions stabilized by whey protein isolate

The influence of particle size and ionic strength on the freeze-thaw(FT) stability of emulsions stabilized by whey protein isolate(WPI) was investigated in this study. The destabilization of emulsions during the FT process could be suppressed in a way by decreasing the particle size of the initial emulsions, which was the result of retarding the coalescence between oil droplets. To further improve the FT stability of emulsions, different amounts of Na Cl were added before emulsification. The emulsions with the ionic strength at 30–50 mmol/L exhibited good FT stability. Notably, the ionic strength in this range would not lower the freezing point of emulsions below the freezing temperature used in this study. Salt addition could improve the structural properties of proteins, which was available to strengthen the rigidity and thickness of interfacial layers, sequentially building up the resistance that the destruction of ice crystals to emulsions. Moreover, stronger flocculation between emulsion droplets could promote the formation of a gel-like network structure dominated by elasticity in the emulsion system, which might effectively inhibit the movement of droplets, and improve the FT stability of emulsions eventually. The result was of great significance for the preparation of emulsion-based foods with improved FT stability.

A multi-scale algorithm for dislocation creep at elevated temperatures

Dislocation creep at elevated temperatures plays an important role for plastic deformation in crystalline metals.When using traditional discrete dislocation dynamics(DDD)to capture this process,we often need to update the forces on N dislocations involving~N 2 interactions.In this letter,we introduce a multi-scale algorithm to speed up the calculations by dividing a sample of interest into sub-domain grids:dislocations within a characteristic area interact following the conventional way,but their interaction with dislocations in other grids are simplified by lumping all dislocations in another grid as a super one.Such a multi-scale algorithm lowers the computational load to~N 1.5.We employed this algorithm to model dislocation creep in Al-Mg alloy.The simulation leads to a power-law creep rate in consistent with experimental observations.The stress exponent of the power-law creep is a resultant of dislocations climb for~5 and viscous dislocations glide for~3.

Research on the mechanics of high speed rails

In the preceding theme issue on＂Current research progress on mechanics of high speed rails＂（Acta Mechanica Sinica,30：846–909（2014））,we invited several authors in the fiel to present their research on high speed rails（HSR）,including work on dynamic derailment analysis（Ling et al.[1]）,

Chalcogen-dependent catalytic properties of RuX2 (X = S/Se/Te) nanoparticles decorated carbon nanofibers for hydrogen evolution in acidic and alkaline media

Transition metal dichalcogenides(TMDs),with the general formula MX_(2)(M=Mo/W/Fe/Co/Ni,etc.;X=S/Se/Te),have attracted extensive research interests for hydrogen evolution reaction(HER).Compared with numerous studies on noble-metal-free TMDs,the chalcogen-dependent HER catalytic properties of noble-metal-based TMDs are lack of sufficient research attention.Herein,a facile electrospinning-assisted synthetic strategy is proposed to synthesize ruthenium dichalcogenides(RuX_(2),X=S/Se/Te)nanoparticles decorated carbon nanofibers(CNFs).Benefiting from the identical nanofibrous morphology and exposed crystal planes of RuX_(2)(111),the catalytic activities of RuX_(2)@CNFs samples were investigated and compared in a fair and direct manner.Detailed electrochemical measurements coupled with density functional theory calculations were carried out to probe their intrinsic HER catalytic activities,resulting in the catalytic activity order of RuS_(2)@CNFs>RuSe_(2)@CNFs>RuTe_(2)@CNFs in acidic media and that of RuS_(2)@CNFs>RuTe_(2)@CNFs>RuSe_(2)@CNFs in alkaline media.The superior catalytic performance of RuS_(2)@CNFs mainly stems from the relative lower HER energy barriers and thereby the higher intrinsic catalytic activity of RuS_(2)(111),leading to ultralow overpotentials of 44 and 9 mV at 10 mA·cm^(-2) in acidic and alkaline media,respectively.RuSe_(2)(111)is endowed with the more optimized Gibbs free energy of hydrogen adsorption(ΔGH*)than RuTe_(2)(111),but RuTe_(2)(111)shows enhanced catalytic property for H_(2)O dissociation and OH-desorption than RuSe_(2)(111),therefore,resulting in the altered catalytic activity sequences for RuSe_(2) and RuTe_(2) in acidic and alkaline media.

Resource-saving scheduling scheme for centralized target tracking in multiple radar system under automatic blanket jamming

This paper investigates the problem of Joint Radar Node Selection and Power Allocation(JRNSPA)in the Multiple Radar System(MRS)in the blanket jamming environment.Each radar node independently tracks moving target and subsequently transmits the raw observation data to the fusion center,which formulates a centralized tracking network structure.In order to establish a practical blanket jamming environment,we suppose that each target carries the self-defense jammer which automatically implements blanket jamming to the radar nodes that exceed the preset interception probability.Subsequently,the Predicted Conditional Cramer-Rao Lower Bound(PC-CRLB)is derived and utilized as the tracking accuracy criterion.Aimed at ensuring both the tracking performance and the Low Probability of Intercept(LPI)performance,the resource-saving scheduling model is formulated to minimize the transmit power consumption while meeting the requirements of tracking accuracy.Finally,the Modified Zoutendijk Method Of Feasible Directions(MZMFD)-based two-stage solution technique is adopted to solve the formulated non-convex optimization model.Simulation results show the effectiveness of the proposed JRNSPA scheme.

Identification of FUT7 hypomethylation as the blood biomarker in the prediction of early-stage lung cancer

Early detection of lung cancer (LC) is vital for reducing LC-related mortality. However, noninvasive diagnostic tools remain a great challenge. We aim to identify blood-based biomarkers for the early detection of LC. Here, LC-associated hypomethylation in alpha-1,3-fucosyltransferase VII (FUT7) is identified via the Illumina 850K array in a discovery study and validated by mass spectrometry in two independent casecontrol studies with blood samples from 1720 LC patients (86.8% LC at stage I, blood is collected before surgery and treatment) and 3143 healthy controls. Compared to the controls, blood-based FUT7 hypomethylation is identified in LC patients at stage I, and even in LC patients with malignant nodules ≤1 cm and in patients with adenocarcinoma in situ. Gender plays a role in the LC-associated FUT7 hypomethylation in blood, which is more significant in males than in females. We also reveal that FUT7 hypomethylation in LC could be enhanced by the advanced stage of cancer, involvement of lymph nodes, and larger tumor size. Based on a large sample size and semi-quantitative methods, our study reveals a strong association between blood-based FUT7 hypomethylation and LC, suggesting that methylation signatures in blood may be a group of potential biomarkers for detection of early-stage LC.

Spatiotemporal variations and determinants of stream nitrogen and phosphorus concentrations from a watershed in the Three Gorges Reservoir Area,China

Socioeconomic development induced nonpoint source(NPS)pollution has aroused an increasing concern,however,most of the previous studies were concentrated on the impacts of environmental determinants.Here,total nitrogen(TN)and total phosphorus(TP)concentrations from 13 sampling sites were collected biweekly from January 2018 to October 2021,and 26 potential factors including environmental and socioeconomic were considered in the Wangjiaqiao watershed of the Three Gorges Reservoir Area,China.Impacts of these factors on TN and TP were evaluated by partial least squares regression(PLSR)model.It showed that average TN and TP concentrations in wet seasons(TN,14.68 mg L^(-1):TP,0.113 mg L^(-1))were higher than that in dry seasons(TN,11.73 mg L^(-1);TP,0.087 mg L^(-1)).Additionally,the TN concentrations were greater in downstream than upstream,however,the highest TP concentrations were found in the middle of the watershed.The optimal PLSR model explained 69.6%,73.1%and 66.1%of the variance in TN concentration,as well as 65.7%,79.5%and 67.4%of the variance in TP concentration during the annual,dry and wet seasons,respectively.Moreover,TN was primarily influenced by topographic wetness index,planting structure,interspersion and juxtaposition index,orchard proportion,nitrogen fertilization,per capita income,and catchment area,whereas TP was mainly controlled by slope gradient,topographic wetness index,hypsometric integral,interspersion and juxtaposition index,and population density.Collectively,environmental factors had greater impacts on the TN and TP concentrations than socioeconomic factors.Raising farmers'awareness of the hazards of NPS pollution is beneficial to watershed NPS pollution control.

Dynamic study of infiltration rate for soils with varying degrees of degradation by water erosion

Ultisols,widely distributed in tropical and subtropical areas of south China,are suffering from serious water erosion,however,slope hydrological process for Ultisols under different erosional degradation levels in field condition has been scarcely investigated.Field rainfall simulation at two rainfall intensities (120 and 60 mm/h) were performed on pre-wetted Ultisols with four erosion degrees (non,moderate,severe and very-severe),and the hydrological processes of these soils were determined.The variation of soil infiltration was contributed by the interaction of erosion degree and rainfall intensity (p < 0.05).In most cases,time to incipient runoff,the decay coefficient,steady state infiltration rate,and their variability were larger at the high rainfall intensity,accelerating by the increasing erosion severity.Despite rainfall intensity,the infiltration process of Ultisols was also significantly influenced by mean weight diameter of aggregates at the field moisture content,soil organic carbon and particle size distribution (R2 > 30%,p < 0.05).The temporal erodibility of surface soil and soil detachment rate were significantly and negatively correlated with infiltration rate (r <-0.32,p < 0.05),but less significant correlation was observed between sediment concentration and infiltration rate for most soils,especially at the high rainfall intensity.The variation of surface texture and soil compactness generated by erosion degradation was the intrinsic predominant factors for the change of infiltration process of Ultisols.The obtained results will facilitate the understanding of hydrological process for degraded lands,and provide useful knowledge in managing crop irrigation and soil erosion.

Temperature-controlled fabrication of Co-Fe-based nanoframes for efficient oxygen evolution

Transition metal phosphides(TMPs)have emerged as promising electrocatalysts to enhance the slow kinetic process of oxygen evolution reaction(OER).Framelike hollow nanostructures(nanoframes,NFs)provide the open structure with more accessible active sites and sufficient channels into the interior volume.Here,we report the fabrication of bimetallic Co-Fe phosphide NFs(Co-Fe-P NFs)via an intriguing temperature-controlled strategy for the preparation of precursors followed by phosphidation.The precursors,Co-Fe Prussian blue analogues(Co-Fe PBAs)are prepared by a precipitation method with Co^(2+)and[Fe(CN)_(6)]^(3−),which experience a structural conversion from nanocubes to NFs by increasing the aging temperature from 5 to 35℃.The experimental results indicate that this conversion is attributable to the preferentially epitaxial growth on the edges and corners of nanocubes,triggered by intramolecular electron transfer at an elevated aging temperature.The as-prepared Co-Fe-P NFs catalyst shows remarkable catalytic activity toward OER with a low overpotential of 276 mV to obtain a current density of 10 mA cm^(−2),which is superior to the reference samples(Co-Fe-P nanocubes)and most of the recently reported TMPs-based electrocatalysts.The synthetic strategy can be extended to fabricate Co-Fe dichalcogenide NFs,thereby holding a great promise for the broad applications in energy storage and conversion systems.

Relationship between granitic soil particle-size distribution and shrinkage properties based on multifractal method

The mechanical properties of granitic residual soils vary with depth due to changes in soil type and heterogeneity caused by weathering.The purpose of this study was to relate the spatial variation of particle-size distribution(PSD)of granitic soils with soil shrinkage parameters using multifractal theory.The heterogeneity of PSD and pedogenic processes were depicted in detail by multifractal dimensions.The PSD generally increased with the increase of profile depth in accordance with the variation of single fractal dimension(D)ranging from 2.45 to 2.65.The shrinkage limit was greatly influenced by the multifractal dimension parameters,including information dimension(D1)and capacity dimension(D0)(Adjusted R2=0.998,P<0.01),and the maximum linear extensibility(κv)was determined by spectral width(?α)and bulk density,with the latter explaining 89%of the total variance ofκv(P<0.01).Soil shrinkage characteristic curve was fitted by the modified logistic model(R2>0.97,root sum of squares<0.1),and the water variation corresponding to the maximum change rate of linear extensibility was determined by the silt content(R2=0.81,P<0.01).Overall,the shrinkage of granitic soils was primarily influenced by PSD and soil compactness.

Temperature-controlled synthesis of heterostructured Ru-Ru_(2)P nanoparticles embedded in carbon nanofibers for highly efficient hydrogen production

Developing highly efficient,cost-effective,and stable electrocatalysts for hydrogen evolution reaction(HER)is of considerable importance but remains challenging.Herein,we report the fabrication of a robust Ru-based electrocatalyst,which comprises heterostructured Ru-Ru_(2)P nanoparticles that are embedded in the N,P-codoped carbon nanofibers(CNFs),through a synthetic strategy involving electrospinning and temperature-controlled pyrolysis treatment.The as-prepared Ru-Ru_(2)P catalyst(Ru-Ru_(2)P@CNFs)shows excellent HER catalytic activities with low overpotentials of 11 and 14 mV in acidic and alkaline media,respectively,to achieve a current density of 10 mA cm^(−2),which are superior to the individual components of pure Ru and Ru_(2)P catalysts.Density functional theory calculations demonstrate the existence of electronic coupling effect between Ru and Ru_(2)P at the heterointerfaces,leading to a well-modulated electronic structure with optimized hydrogen adsorption strength and enhanced electrical conductivity for efficient HER electrocatalysis.In addition,the overall synthetic strategy can be generalized for the synthesis of a series of transitional metal phosphide-based nanofibers,thereby holding a remarkable capacity for various potential applications.

Soil organic carbon stock and fractional distribution across central-south China

The stock and stability of soil organic carbon(SOC)are critical to soil functions and global carbon cycle,but little quantitative information is available on the precise location and chemical components of SOC for soils across a wide range of climatic gradients.Here,a broad range of zonal soils were collected in forest land at topsoil(0-15 cm)and subsoil(15-30 cm)from temperate to tropical climatic gradient in central to south China.The stock and stability of SOC were determined in terms of aggregate and humic fractionation.SOC in bulk soils with a less significant geographic variation was comparably higher at Haplic Luvisoils in temperate regions(3637.61 g m^(−2))and Rhodi-Humic Ferrosols in tropical regions(3446.12 g m^(−2))than in the other experimental soils,but a consistent decreasing trend was observed along the soil profiles with the SOC stock was 1.11-1.97 times higher in the topsoil than in the subsoils.In addition,insoluble humin residue(HMr)as the dominant components of SOC ranged from 643.95 to 2696.90 g m^(−2) and decreased from temperate to tropical regions,which was consistent with the zonal variation of humic acids(HAs),but contrary to the zonal variation of fulvic acids(FAs)that fluctuated in a range of 39.67-389.55 g m^(−2) across the experimental sites.According to the results of partial correlation analysis,the variation of FAs stock was significantly attributed to soil pH,bulk density,iron and aluminum oxides,clay,and clay mineral content(|r|>0.61,p<0.05),while these soil physical properties showed a contradictory effects on HAs,iron-linked humin(HMi),clay-combined humin(HMc),and HMr.Moreover,the aggregate-associated carbon stock was mainly stored in macroaggregates(36.34-76.09%)for both SOC and its chemical components,especially in topsoils,and its zonal variation was associated with that of bulk soils.In general,the redundancy analysis(RDA)revealed that mean annual precipitation(MAP)accounted for 81.8%and 13.8%of the variance in SOC chemical and physical fractionation,respectively,while the corresponding contribution of mean annual temperature(MAT)was 1.5%and 34.7%.With the increase of MAT and MAP,the chemical stability of SOC decreased in the molecular structure,and the physical protection of SOC by aggregate exhibited a unimodal trend.The obtained results would facilitate the development of regional soil carbon prediction and land management against global warming.

The stress-velocity relationship of twinning partial dislocations and the phonon-based physical interpretation

The dependence of dislocation mobility on stress is the fundamental ingredient for the deformation in crystalline materials. Strength and ductility, the two most important properties characterizing mechanical behavior of crystalline metals, are in general governed by dislocation motion. Recording the position of a moving dislocation in a short time window is still challenging, and direct observations which enable us to deduce the speed-stress relationship of dislocations are still missing. Using large-scale molecular dynamics simulations, we obtain the motion of an obstacle-free twinning partial dislocation in face centred cubic crystals with spatial resolution at the angstrom scale and picosecond temporal information. The dislocation exhibits two limiting speeds: the first is subsonic and occurs when the resolved shear stress is on the order of hundreds of megapascal. While the stress is raised to gigapascal level, an abrupt jump of dislocation velocity occurs, from subsonic to supersonic regime. The two speed limits are governed respectively by the local transverse and longitudinal phonons associated with the stressed dislocation, as the two types of phonons facilitate dislocation gliding at different stress levels.

The scaling of charging rate and cycle number of commercial batteries

Health management for commercial batteries is crowded with a variety of great issues,among which reliable cycle-life prediction tops.By identifying the cycle life of commercial batteries with different charging histories in fast-charging mode,we reveal that the average charging rate c and the resulted cycle life N of batteries obey c=c_(0)N^(b),where c_(0) is a limiting charging rate and b is an electrode-dependent constant.This c-N law,resembling the classic stress versus cycle number relationship(the S-N curve or Wohler curve)of solids subject to cyclic loading,could be applicable to most batteries.Such a scaling law,in combination with a physics-augmented machine-learning algorithm,could foster the predictability of battery life with high fidelity.The scaling of charging rate and cycle number may pave the way for cycle-life prediction and the directions of optimization of advanced batteries.

Grain boundary diffusion and viscous flow governed mechanical relaxation in polycrystalline materials

Grain boundary(GB) diffusion and viscous flow play dominant roles in mechanical relaxation of polycrystalline materials. The pioneering work of Zener and Kê, by accounting for relaxation in GBs by viscous shearing, predicts a single peak in the internal friction spectrum. Later investigations show the existence of two to three peaks in the internal friction spectrum when taking into account both GB diffusion and viscous flow for dissipation. In this paper, we further identify the characteristic relaxation modes in polycrystalline materials. We illustrate that competitive viscous flow and diffusion for normal stress relaxation give rise to distinct dependence of relaxation time on grain size. We construct an internal friction spectrum mapping based on the competitive deformation mechanisms including viscous flow in both normal and tangential directions and GB diffusion. The essential features of internal friction spectrum of polycrystalline materials from our analysis are consistent with available experimental observations. These findings may also be applicable to study relaxation dynamics of other material systems such as metallic glasses and porous materials.