Topology change and emergent scale symmetry in compact star matter via gravitational wave detection

Topological structure has been extensively studied and confirmed in highly correlated condensed matter physics. We explore the gravitational waves emitted from binary neutron star mergers using the pseudoconformal model for dense nuclear matter for compact stars. This model considers the topology change and the possible emergent scale symmetry and satisfies all the constraints from astrophysics. We find that the location of the topology change affects gravitational waves dramatically owing to its effect on the equation of state. In addition, the effect of this location on the waveforms of the gravitational waves is within the ability of the on-going and up-coming facilities for detecting gravitational waves, thus suggesting a possible way to measure the topology structure in nuclear physics.

高温高密度时的新物质形态

在高温高密条件下,夸克将解除禁闭形成全新的物质形态——夸克物质.本文从核物质的基本相互作用——量子色动力学(QCD)的基本对称性出发,首先简单介绍研究QCD相变的各种方法,阐述相变发生的物理机制和条件,然后着重讨论实现QCD相变的两种物理系统,即相对论重离子碰撞和致密星体.相对论重离子碰撞是制造高温环境的重要手段,核物质将形成全新的夸克胶子等离子体相(QGP).文中介绍了探测QGP的实验信号和高温环境特有的新奇物理现象.致密天体中的高密区则展现了极其丰富多彩的相结构.理论预示了与颜色和味道等自由度相联系的各类超导、超流态存在的可能性.相信在未来更大范围的束流能量扫描和对致密星体的精确观测中,我们将会对高温高密核物质的物态性质有着更加深入的认识.

Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O3,decreased. Spatially, the PM2.5, PM10, SO2, and CO concentrations were higher in the northern YRD region, and NO2 and O3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM2.5 was the largest contributor to air pollution in the YRD region, followed by O3, PM10, and NO2.However, particulate matter pollution has declined gradually, while O3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM2.5 concentration was inversely related to wind speed, while O3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM2.5, PM10, SO2, NOx, CO, NH3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.

Characteristics and mixing state of S-rich particles in haze episodes in Beijing

Direct individual analysis using Scanning Electron Microscopy combined with online obscrv ation was conducted to examine the S-rich particles in PM2.5 of two typical polluted haze cpisodes in summer and winter from 2014 to 2015 in Beijing. Four major types of S-rich particles, including sccondary CaSO4 particles （mainly observed in summer）, S-rich mineral particles （SRM）, S-rich water droplets （SRW） and （C, O, S）-rich particles （COS） were identified. We lbund the differcnt typical morphologies and element distributions of S-rich particles and considered that （C, O, S）-rich parliclcs had two major mixing states in different seasons. On the basis of the S-rich particles＂ relative abundances. S concentrations and their relationships with PM2.5 as well as the seasonal comparison, wc revealed that the S-participated formation degrees of SRM and SRW would enhance with increasing PM2.5 concentration. Moreover, C-rich matter and sulfate had seasonally differcnt but significant impacts on the formation of COS.

A comparative study of particle size distribution from two oxygenated fuels and diesel fuel

Oxygenated fuels are known to reduce particulate matter(PM)emissions from diesel engines.In this study,100%soy methyl ester(SME)biodiesel fuel(B100)and a blend of 10%acetal denoted by A-diesel with diesel fuel were tested as oxygenated fuels.Particle size and number distributions from a diesel engine fueled with oxygenated fuels and base diesel fuel were measured using an Electrical Low Pressure Impactor(ELPI).Measurements were made at ten steady-state operational modes of various loads at two engine speeds.It was found that the geometric mean diameters of particles from SME and Adiesel were lower than that from base diesel fuel.Compared to diesel fuel,SME emitted more ultra-fine particles at rated speed while emitting less ultra-fine particles at maximum speed.Ultra-fine particle number concentrations of A-diesel were much higher than those of base diesel fuel at most test modes.

Organic nitrogen in PM2.5 in Beijing

Nitrogenous species, as important chemical components in PM2.5, include organic nitrogen （ON） and inorganic nitrogen （IN）, both of which have potential effects on human health, climate change and visibility degradation. In this study, we analyzed total nitrogen （TN） by CHN Elemental analyzer and inorganic nitrogen by ion chromatography （IC） respectively to obtain ON by calculating the difference between TN and IN. The results show that the mean ON concentrations in winter and summer are both 2.86 μg. m-a, ten times higher than other places reported on average. ON contributes about 20%- 30% to TN on average in both seasons, presenting higher contribution in summer. N：C ratios are much higher in summer than winter. ON sources or formation were strengthened by heavy PM2.5 pollution loads, especially sensitive to sulfate. ON concentrations are higher at night in the both seasons, however with distinguished day and night difference patterns influenced by relative humidity （RH） conditions. In winter, ON concentrations increase with RH on average through low RH values to high RH values. The variations are far larger than the ones caused by day and night difference. However in summer, day and night difference dominates the variations of ON concen- trations at low RH values, and RH conditions promote ON concentrations increase significantly only at high RH values. Dust related source and anthropogenic emission related secondary source are identified as important sources for ON. At heavy pollution loads, ON sources are more of secondary formation, possibly strengthened by combination influence of RH and acidity increase.

Selenium uptake and simultaneous catalysis of sulfite oxidation in ammonia-based desulfurization

Accelerating the(NH_4)_(2)SO_(3) oxidation gives rise to the reclaiming of byproduct, while there are secondary environmental risks from reduction of the coexisted selenium species by sulfite. In this study, a bi-functional Co-SBA-15-SH, were synthesized through Co impregnation and sulfhydryl(-SH) decoration, which can simultaneously uptake Se and accelerate sulfite oxidation efficiently. Meanwhile, the adsorption kinetics and migration mechanism of Se species were revealed through characterization and density functional calculations, with maximum adsorption capacity of 223 mg/g. The inhibition of Se~0 re-emission and poisonous effect of Se on sulfite oxidation was also investigated. Using the findings of this study, the ammonia desulfurization can be improved by enabling purification of the byproduct and lowering the toxicity of effluent by removing toxic pollutants.