Light–matter interaction of 2D materials:Physics and device applications

In the last decade, the rise of two-dimensional （2D） materials has attracted a tremendous amount of interest for the entire field of photonics and opto-electronics. The mechanism of light-matter interaction in 2D materials challenges the knowledge of materials physics, which drives the rapid development of materials synthesis and device applications. 2D materials coupled with plasmonic effects show impressive optical characteristics, involving efficient charge transfer, plas- monic hot electrons doping, enhanced light-emitting, and ultrasensitive photodetection. Here, we briefly review the recent remarkable progress of 2D materials, mainly on graphene and transition metal dichalcogenides, focusing on their tunable optical properties and improved opto-electronic devices with plasmonic effects. The mechanism of plasmon enhanced light-matter interaction in 2D materials is elaborated in detail, and the state-of-the-art of device applications is compre- hensively described. In the future, the field of 2D materials holds great promise as an important platform for materials science and opto-electronic engineering, enabling an emerging interdisciplinary research field spanning from clean energy to information technology.

基于Hydrolight模型的太湖SDGSAT-1卫星悬浮物浓度反演研究

利用卫星遥感反演水体中的悬浮物浓度对水质监测和保护具有重要意义,在悬浮物浓度反演过程中,如何避免或最大程度降低水体中叶绿素a、有色可溶性有机物(Colored Dissolved Organic Matter,CDOM)的干扰是当前的技术难点。文章针对可持续发展科学卫星1号(SDGSAT-1)MII传感器,利用Hydrolight辐射传输模型,从理论上挖掘只与悬浮物强相关的反演因子,以此构建适用于MII影像的太湖悬浮物浓度反演模型,通过水体的实测数据和遥感数据对模型应用效果进行验证。结果表明:反演因子R′(B_5/B_3)与悬浮物浓度为强相关,同时与叶绿素a、CDOM浓度弱相关;利用R′(B_5/B_3)作为反演因子构建的幂函数模型为最优反演模型;将幂函数模型分别应用于实测数据和2022年5月4日的太湖SDGSAT-1 MII数据,两次验证试验显示反演结果和现场测量结果具有较强一致性,模型适用性较好。该研究可为SDGSAT-1卫星在湖泊水体悬浮物浓度监测、水资源评估与保护等提供一些技术参考。

基于CEEMDAN-VMD-TCN-lightGBM模型的水质预测研究

针对目前水质预测模型中因为数据本身的复杂性、在信号处理过程中存在的噪声干扰以及分解深度不够导致单一分解难以全面捕捉信号非线性特征的问题,提出了一种基于二次分解的水质预测模型。该模型采用完全自适应噪声集合经验模态分解(CEEMDAN)对原始数据进行分解,再利用变分模态分解(VMD)对熵值最高的模态分量进行二次分解,最终将处理后的时间序列输入到TCN-lightGBM多特征预测模型中。同时,采用麻雀算法(SSA)对预测模型进行优化。以山东省玉符河水质为例,本模型的均方根误差(RMSE)是0.1053,平均绝对误差(MAE)是0.0815,决定系数(R2)是0.9471,与GRU、LSTM、LightGBM、TCN等当下较为流行的模型的预测指标进行比较。结果显示,在R2上本模型提升了53.04%、70.41%、66.07%、65.20%等,在RMSE上减少了62.76%、65.50%、64.93%、64.80%等,在MAE上降低了62.76%、66.24%、63.80%、65.24%等。由此可知,基于CEEMDAN-VMD-TCN-lightGBM的模型具有更好的预测性能、泛化能力和捕捉信号非线性特征的能力。

Search for Ultralight Dark Matter with a Frequency Adjustable Diamagnetic Levitated Sensor

Among several dark matter candidates,bosonic ultra-light(sub-meV)dark matter is well motivated because it could couple to the Standard Model and induce new forces.Previous MICROSCOPE and E¨ot–Wash torsion experiments have achieved high accuracy in the sub-1 Hz region.However,at higher frequencies there is still a lack of relevant experimental research.We propose an experimental scheme based on the diamagnetic levitated micromechanical oscillator,one of the most sensitive sensors for acceleration sensitivity below the kilohertz scale.In order to improve the measurement range,we utilize a sensor whose resonance frequencyω0 could be adjusted from 0.1 Hz to 100 Hz.The limits of the coupling constant gB-Lare improved by more than 10 times compared to previous reports,and it may be possible to achieve higher accuracy by using the array of sensors in the future.

Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei

Light levels determine regeneration in stands and a key concern is how to regulate the light environment of different stand types to the requirements of the understory.In this study,we selected three stands typical in south China(a Cryptomeria japonica plantation,a Quercus acutissima plantation,and a mixed stand of both)and three thinning intensities to determine the best understory light environ-ment for 3-year-old Phoebe bournei seedlings.The canopy structure,understory light environment,and photosynthe-sis and growth indicators were assessed following thin-ning.Thinning improved canopy structure and understory light availability of each stand;species composition was the reason for differences in the understory light environ-ment.Under the same thinning intensity,the mixed stand had the greatest light radiation and most balanced spectral composition.P.bournei photosynthesis and growth were closely related to the light environment;all three stands required heavy thinning to create an effective and sustained understory light environment.In a suitable understory light environment,the efficiency of light interception,absorption,and use by seedlings was enhanced,resulting in a higher carbon assimilation the main limiting factor was stomatal conductance.As a shade-avoidance signal,red/far-red radia-tion is a critical factor driving changes in photosynthesis and growth of P.bournei seedlings,and a reduction increased light absorption and use capacity and height:diameter ratios.The growth advantage transformed from diameter to height,enabling seedlings to access more light.Our findings suggest that the regeneration of shade-tolerant species such as P.bournei could be enhanced if a targeted approach to thinning based on stand type was adopted.

基于LightGBM的智能可穿戴设备用户行为预测

智能可穿戴设备产生的大量数据是人类宝贵的数字资源。使用开放数据集和主流数据分析工具,如可进行快速模型开发的PyCaret模块,有助于人们进行数据挖掘工作,且不被细节所困扰。作为Kaggle竞赛爱好者的常用工具,LightGBM分类器对用户行为的预测表现优异,对此文中的研究结果也得到验证。

A Simple Model Unifies Space, Matter and Light

An alternative model is proposed to derive several of Einstein’s basic relativity equations, which would make relativity theory easier to comprehend and more intuitive. Despite the radical nature of the hypothesis, the findings are consistent with many predictions of relativity theory and shed light on the fundamental aspects of various relativity concepts. The model unifies Space, Matter, and Light, all of which are of the same nature. The building block is a mass-unit composed of size and motion. The invariant space-time interval and the corresponding space-mass interval are derived and explained. Only when there is “external force”, the Einstein’s energy-momentum equation becomes applicable. The “no external force” scenario leads to the generation of a new energy-momentum equation that explains the nature of gravity and perhaps even dark matter. Modified Minkowski space-time and space-mass diagrams clearly depict time dilation, length contraction, the mass-momentum-energy relationship, and other relativity phenomena.

Commentary on “Does light-intensity physical activity moderate the relationship between sitting time and adiposity markers in adolescents?”

In the September 2022 issue of the Journal of Sport and Health Science,Ayala et al.1 published results from a cross-sectional study where they tested the hypothesis that light intensity physical activity(LIPA,1.6-2.9 metabolic equivalents(METs))moderates the relationship between sitting time and adiposity in 219 Australian adolescents aged 14±1.6 years(mean±SD).

A pressure-sensitive rheological origin of high friction angles of granular matter observed in NASA–MGM project

An abnormally high peak friction angle of Ottawa sand was observed in(National Aeronautics and Space Administration) NASA–(Mechanics of Granular Materials) MGM tests in microgravity conditions on the space shuttle. Previous investigations have been unsuccessful in providing a constitutive insight into this behavior of granular materials under extremely low effective stress conditions. Here, a recently proposed unified constitutive model for transient rheological behavior of sand and other granular materials is adopted for the analytical assessment of high peak friction angles. For the first time, this long-eluded behavior of sand is attributed to a hidden rheological transition mechanism, that is not only rate-sensitive, but also pressure-sensitive. The NASA–MGM microgravity conditions show that shear-tests of sand can be performed under abnormally low confining stress conditions. The pressure-sensitive behavior of granular shearing that is previously ignored is studied based on the μ(I) rheology and its variations. Comparisons between the model and the NASA microgravity tests demonstrate a high degree of agreement. The research is highly valid for pressure-sensitive and rate-dependent problems that occur during earthquakes, landslides, and space exploration.

The Structure of Gravity Funnels and Stability Considerations of Matter in SI Units

This article describes an extension of the theory of vortices to electromagnetic types with a start point from known fluid systems. From this, properties of gravity-generating objects (particles and black holes) can be derived, which can also describe their possible interior. This also leads to questions about stability, which are then addressed and ultimately lead to considerations of black holes and their possible internal structure. The results fit into the observable areas and can also be directly verified because they were analytically calculated in SI units.

A Workable Solution for Reducing the Large Number of Vehicle and Pedestrian Accidents Occurring on a Yellow Light

Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada, during 2019, the National Collision Database shows that 28% of traffic fatalities and 42% of serious injuries occurred at intersections. Likewise, the U.S. National Highway Traffic Administration (NHTSA) found that about 40% of the estimated 5,811,000 accidents in the U.S. during the year studied were intersection-related crashes. In fact, a major survey by the car insurance industry found that nearly 85% of drivers could not identify the correct action to take when approaching a yellow traffic light at an intersection. One major reason for these accidents is the “yellow light dilemma,” the ambiguous situation where a driver should stop or proceed forward when unexpectedly faced with a yellow light. This situation is even further exacerbated by the tendency of aggressive drivers to inappropriately speed up on the yellow just to get through the traffic light. A survey of Canadian drivers conducted by the Traffic Injury Research Foundation found that 9% of drivers admitted to speeding up to get through a traffic light. Another reason for these accidents is the increased danger of making a left-hand turn on yellow. According to the National Highway Traffic Safety Association (NHTSA), left turns occur in approximately 22.2% of collisions—as opposed to just 1.2% for right turns. Moreover, a study by CNN found left turns are three times as likely to kill pedestrians than right turns. The reason left turns are so much more likely to cause an accident is because they take a driver against traffic and in the path of oncoming cars. Additionally, most of these left turns occur at the driver’s discretion—as opposed to the distressingly brief left-hand arrow at busy intersections. Drive Safe Now proposes a workable solution for reducing the number of accidents occurring during a yellow light at intersections. We believe this fairly simple solution will save lives, prevent injuries, reduce damage to public and private property, and decrease insurance costs.

Straw mulching alters the composition and loss of dissolved organic matter in farmland surface runoff by inhibiting the fragmentation of soil small macroaggregates

Straw mulching is a widespread practice for reducing the soil carbon loss caused by erosion.However,the effects of straw mulching on dissolved organic matter(DOM)runoff loss from black soil are not well studied.How straw mulching affects the composition and loss of runoff DOM by changing soil aggregates remains largely unclear.Here,a straw mulching treatment was compared to a no mulching treatment(as a control)on sloping farmland with black soil erosion in Northeast China.We divided the soil into large macroaggregates(>2 mm),small macroaggregates(0.25-2 mm),and microaggregates(<0.25 mm).After five rain events,the effects of straw mulching on the concentration(characterized by dissolved organic carbon(DoC)and composition(analyzed by fluorescence spectroscopy)of runoff and soil aggregate DOM were studied.The results showed that straw mulching reduced the runoff amount by 54.7%.Therefore,although straw mulching increased the average DOc concentration in runoff,it reduced the total runoff DOM loss by 48.3%.The composition of runoff DOM is similar to that of soil,as both contain humic-like acid and protein-like components.With straw mulching treatment,the protein-like components in small macroaggregates accumulated and the protein-like components in runoff declined with rain events.Fluorescence spectroscopy technology may help in understanding the hydrological paths of rain events by capturing the dynamic changes of runoff and soil DOM characteristics.A variation partitioning analysis(VPA)indicated that the DOM concentration and composition of microaggregates explained 68.2%of the change in runoff DOM from no mulching plots,while the change in runoff DOM from straw mulching plots was dominated by small macroaggregates at a rate of 55.1%.Taken together,our results demonstrated that straw mulching reduces the fragmentation of small macroaggregates and the loss of microaggregates,thus effecting DOM compositions in soil and reducing the DOM loss in runoff.These results provide a theoretical basis for reducing carbon loss in sloping farmland.

Photoperiod Mediates the Effects of Temperature and Light Intensity on the Proliferation of Ulva prolifera

In order to study the complex effects of photoperiod,temperature,and light intensity on the spore maturation and release number of Ulva prolifera,we cultured thalli segment(2–3 mm)under three different photoperiods(L:D=12:12,14:10 and 10:14),temperature(15℃(LT),25℃(MT)and 30℃(HT))and light intensity(100,200 and 400μmol m^(−2)s^(−1),noted as LL,ML and HL,respectively)conditions.Then the maturation time,spore release number and chlorophyll fluorescence were analyzed.The results suggested that:1)The spore maturation time was accelerated by higher temperature or higher light intensity from 62 h to 36 h,and changes in day length accelerated the spore maturation to a certain extent as compared with 12:12 light/dark cycle;2)Higher light intensity significantly decreased the chlorophyll fluorescence(Fv′/Fm′,NPQ,rETRmax andα)of the mature reproductive segment under 30℃with 12:12 light/dark cycle.But when in the other photoperiods(10:14 and 14:10 conditions),the inhibitory effects of high light intensity were alleviated significantly;3)The optimum condition for the spore maturation and release was 12:12 light/dark cycle,25℃,400μmol m^(−2)s^(−1),with both shorter and longer photoperiod reducing the spore release number;4)Higher light intensity significantly increased the spore release number under 25℃,but these effects were alleviated by 30℃treatment.This study is the first attempt to elucidate the coincidence effects of photoperiod,temperature and light intensity on the reproduction of Ulva,which would help to reveal the mechanism of the rapid proliferation of green tide.

Biogeochemistry of sedimentary organic matter in the Yongjiang River estuary in the southern part of Hangzhou Bay,China,since the Late Pleistocene

A sediment core(YJK19-02)collected from the southern outlet of Hangzhou Bay near the Yongjiang River estuary in East China was analyzed for grain size,lignin,bulk elemental composition,stable carbon isotope,and rare earth elements(REEs)to determine the sources and diagenesis of sedimentary organic matter(OM)of the estuary and adjacent areas since the Late Pleistocene.δ^(13)C values(-24.80‰–-23.60‰),total organic carbon/total nitrogen(TOC/TN)molar ratios(8.00–12.14),and light rare earth element/heavy rare earth element ratios(LREE/HREE=8.34–8.91)revealed the predominance of terrestrial sources of OM,mainly from the Changjiang(Yangtze)River.The lignin parameters of syringyl/vanillyl(S/V=0.20–0.73)and cinnamyl/vanillyl(C/V=0.03–0.19)ratios indicate the predominance of nonwoody angiosperms,and the vanillic acid/vanillin ratios[(Ad/Al)_(V)=0.32–1.57]indicate medium to high degrees of lignin degradation.An increasing trend ofΛ(total lignin in mg/100-mg OC)values from ca.14500 a BP to ca.11000 a BP reflected the increase in temperature during the Late Pleistocene.However,a time lag effect of temperature on vegetation abundance was also revealed.The relatively higher and stableΛvalues correspond to the higher temperature during the mid-Holocene from ca.8500 a BP to ca.4500 a BP.Λvalues decreased from ca.4000 a BP to the present,corresponding to historical temperature fluctuations during this time.Our results show that the vegetation abundance in the Yongjiang River Basin since the Late Pleistocene was related to the temperature fluctuation duo to climate change.

Effect of artificial natural light on the development of myopia among primary school-age children in China:a three-year longitudinal study

AIM:To assess the efficacy of artificial natural light in preventing incident myopia in primary school-age children.METHODS:This is a prospective,randomized control,intervention study.A total of 1840 students from 39 classes in 4 primary schools in Foshan participated in this study.The whole randomization method was adopted to include classes as a group according to 1:1 randomized control.Classrooms in the control group were illuminated by usual light,and classrooms in the intervention group were illuminated by artificial natural light.All students received uncorrected visual acuity and best-corrected visual acuity measurement,non-cycloplegic autorefraction,ocular biometric examination,slit lamp and strabismus examination.Three-year follow-up,the students underwent same procedures.Myopia was defined as spherical equivalent refraction≤-0.50 D and uncorrected visual acuity<20/20.RESULTS:There were 894 students in the control group and 946 students in the intervention group with a mean±SD age of 7.50±0.53y.The three-year cumulative incidence rate of myopia was 26.4%(207 incident cases among 784 eligible participants at baseline)in the control group and 21.2%(164 incident cases among 774 eligible participants at baseline)in the intervention group[difference of 5.2%(95%CI,3.7%to 10.1%);P=0.035].There was also a significant difference in the three-year change in spherical equivalent refraction for the control group(-0.81 D)compared with the intervention group[-0.63 D;difference of 0.18 D(95%CI,0.08 to 0.28 D);P<0.001].Elongation of axial length was significantly different between in the control group(0.77 mm)and the intervention group[0.72 mm;difference of 0.05 mm(95%CI,0.01 to 0.09 mm);P=0.003].CONCLUSION:Artificial natural light in the classroom of primary schools can result in reducing incidence rate of myopia during a period of three years.

Identifying drivers of urban landuse changes in the Wenchuan earthquake- affected area by using night-time light data

To learn the process of urban land evolution before and after an earthquake is vital to formulate the urban reconstruction control policies and recovery measures in the earthquake-stricken areas.However,spatiotemporal evolution and its driving factors of urban land in earthquake-prone areas remains limited due to the scarcity of ground observation data.This research,leveraging night-time light remote sensing imagery and land cover data,conducted a comprehensive analysis of the long-term evolution characteristics of urban land in earthquake-prone areas.It introduced methodologies for assessing the socio-economic impact and the primary natural environmental factors driving urban land evolution in these regions.To validate the proposed methods,the 2008 Wenchuan earthquake-affected area in China was selected as a representative study area.The results indicated that the average Digital Number(DN)values in socio-economically impacted areas showed a trend of rising,falling,and then rising again after the earthquake.DN values in three types of damaged areas including Type Ⅱ,Type Ⅲ,and Type Ⅳ exceeded pre-earthquake levels.The analysis of determinative factors influencing urban land evolution revealed that slope and elevation were key elements in controlling urban land expansion before the earthquake,whereas factors such as slope,elevation,lithology,and faults had a stronger influence on urban land expansion after the earthquake.It can be seen that,in view of the differences in the natural conditions of regions for post-disaster reconstruction,the local government need to actively adjust and adapt to urban spatial planning,so as to leverage the scale effect of large-scale inputs of funds,facilities,human resources and other factors after the disaster,thus enhancing resilience and recovery efficiency in response to disaster impacts.

Ethyl acetate fraction of Sargassum pallidum extract attenuates particulate matter-induced oxidative stress and inflammation in keratinocytes and zebrafish

Objective:To evaluate the effect of the ethyl acetate fraction derived from Sargassum pallidum extract against particulate matter(PM)-induced oxidative stress and inflammation in HaCaT cells and zebrafish.Methods:HaCaT cells and zebrafish were used to evaluate the protective effects of the ethyl acetate fraction of Sargassum pallidum extract against PM-induced oxidative stress and inflammation.The production of nitric oxide(NO),intracellular ROS,prostaglandin E_(2)(PGE_(2)),and pro-inflammatory cytokines,and the expression levels of COX-2,iNOS,and NF-κB were evaluated in PM-induced HaCaT cells.Furthermore,the levels of ROS,NO,and lipid peroxidation were assessed in the PM-exposed zebrafish model.Results:The ethyl acetate fraction of Sargassum pallidum extract significantly decreased the production of NO,intracellular ROS,and PGE_(2) in PM-induced HaCaT cells.In addition,the fraction markedly suppressed the levels of pro-inflammatory cytokines and inhibited the expression levels of COX-2,iNOS,and NF-κB.Furthermore,it displayed remarkable protective effects against PM-induced inflammatory response and oxidative stress,represented by the reduction of NO,ROS,and lipid peroxidation in zebrafish.Conclusions:The ethyl acetate fraction of Sargassum pallidum extract exhibits a protective effect against PM-induced oxidative stress and inflammation both in vitro and in vivo and has the potential as a candidate for the development of pharmaceutical and cosmeceutical products.

Constraints on Asymmetric Dark Matter in Quintessence Model

The modified cosmology like quintessence model with kination phase predicted the Hubble expansion rate of the universe before Big Bang Nucleosynthesis is different from the standard cosmological scenario. The modified expansion rate leaves its imprint on the relic density of asymmetric dark matter. In this work, we review the calculation of relic density of asymmetric WIMP dark matter in the standard cosmological scenario and quintessence model with kination phase. Then we use the Planck data to find constraints on the annihilation cross section and the mass of the asymmetric dark matter in those models.

Differences in and factors controlling organic matter enrichment in the Ziliujing Formation shale in the Sichuan Basin

Lacustrine shale oil and gas are important fields for unconventional exploration and development in China,and organic-rich shale deposition lays down the critical foundation for hydrocarbon generation.There are two sets of shale,the Dongyuemiao and Da’anzhai Members,in the Ziliujing Formation in the Sichuan Basin.To identify the differential enrichment characteristics of organic matter and clarify its controlling factors,geochemical analyses of organic and inorganic geochemical analyses were performed.The results showed that the total organic carbon content of the Dongyuemiao shale(1.36%)is slightly higher than that of the Da’anzhai shale(0.95%).The enrichment of organic matter in the two shales resulted from the comprehensive controls of paleoproductivity,paleoenvironment,and terrigenous input,but different factors have different effects.In addition,driven by climate,the change in the sulfate concentration in the bottom water further led to the different intensities of bacterial sulfate reduction in early diagenesis.This made a great difference regarding organic matter accumulation in the two members.In general,climate may have played a dominant role in organic matter enrichment in the two sets of shale.

Model prediction of inactivation of Aeromonas salmonicida grown on poultry in situ by intense pulsed light

The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of inactivation.In this work,chicken meat and skin inoculated with meat-borne A.salmonicida isolates were subjected to IPL treatments under different conditions.The results showed that IPL had obvious bactericidal effect in the chicken skin and thickness groups when the treatment voltage and time were 7 V combined with 5 s.In addition,the lethality curves of A.salmonicida were fitted under IPL conditions of 3.5-7.5 V.The comparison of statistical parameters revealed that the Weibull model could best fit the mortality curves and could accurately predict the mortality dynamic of A.salmonicida grown on chicken skin.And further a secondary model between the scale factor b and the treatment voltage in Weibull model was established using linear equations,which determined that the secondary model could accurately predict the inactivation of A.salmonicida.This study provides a theoretical basis for future prediction models of Aeromonas,and also provides new ideas for sterilization approaches of meat-borne Aeromonas.