This is the second installment for the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Quasar Survey, which includes quasars observed from 2013 September to 2015 June. There are ...9024 confirmed quasars in DR2 and 10911 in DR3. After cross-match with the Sloan Digital Sky Survey (SDSS) quasar catalogs and NED, 12126 quasars are discovered independently. Among them, 2225 quasars were released by SDSS DR12 QSO catalog in 2014 after we finalized the survey candidates. 1801 sources were identified by SDSS DR14 as QSOs. The remaining 8100 quasars are considered as newly founded, and among them, 6887 quasars can be given reliable emission line measurements and the estimated black hole masses. Quasars found in LAMOST are mostly located at low-to-moderate redshifts, with a mean value of 1.5. The highest redshift observed in DR2 and DR3 is 5. We applied emission line measurements to H , Hβ, Mg ii, and C iv. We deduced the monochromatic continuum luminosities using photometry data, and estimated the virial black hole masses for the newly discovered quasars. Results are compiled into a quasar catalog, which will be available online.
•The SS biochar produced at 450°C is the most suitable one for garlic cultivation.•The favourable C:S ratio drifted when the biochar production temperature changed.•General heavy metal accumulation ...in the garlic root & bulb occurred for the most enriched Zn and Cu in the biochar.•Heavy metal bioaccumulation increased with heavy metal leaching from biochars but did not increase with increased C:S ratio.
Applying biochar products from sewage sludge (SS) pyrolysis as soil amendment for plant cultivation was investigated in this study with special attention paid to heavy metal accumulation in the plants when pyrolysis temperature and biochar-to-soil mass ratio (C:S) were changed. Biochar obtained at four different temperatures were adopted as soil amendment for Allium sativum L. garlic plant cultivation. Experimental results revealed that biochars were rich in nutrient contents and they improved garlic yields. Although contents of heavy metals including As, Zn, Pb, Ni, Cd, Cr and Cu, etc. were elevated in the biochars compared to local soil, they fell within the acceptable limits for land application and SS is a suitable biochar resource, especially biochar produced at 450°C had rich micropores, relatively stable functional groups in structure and rugged surface to contact well with soil, conducive to its usage as a biochar. The garlic grew faster when planted in the biochar-amended soil and had higher final dry matter yields than those planted in the reference soil, especially biochar produced at 450°C corresponding to the highest final yields. The C:S ratio related to the highest garlic yields changed when the pyrolysis temperature was changed and this ratio was 1:4 for the biochar produced at 450°C. General heavy metal accumulation in the garlic occurred only for the most enriched Zn and Cu, and mainly in the roots & bulbs; in addition this bioaccumulation was increasing as leaching from biochar increased but not increasing with C:S ratio. The garlic planted in soil amended with biochar of 450°C contained the lowest level of heavy metals compared to other biochars. Those results indicated that heavy metal accumulation in plants can be inhibited through proper pyrolysis temperature choice and prevention of heavy metal leaching from the SS biochar.
Symmetry plays a key role in modern physics, as manifested in the revolutionary topological classification of matter in the past decade. So far, we seem to have a complete theory of topological ...phases from internal symmetries as well as crystallographic symmetry groups. However, an intrinsic element, i.e., the gauge symmetry in physical systems, has been overlooked in the current framework. Here, we show that the algebraic structure of crystal symmetries can be projectively enriched due to the gauge symmetry, which subsequently gives rise to new topological physics never witnessed under ordinary symmetries. We demonstrate the idea by theoretical analysis, numerical simulation, and experimental realization of a topological acoustic lattice with projective translation symmetries under a Z_{2} gauge field, which exhibits unique features of rich topologies, including a single Dirac point, Möbius topological insulator, and graphenelike semimetal phases on a rectangular lattice. Our work reveals the impact when gauge and crystal symmetries meet together with topology and opens the door to a vast unexplored land of topological states by projective symmetries.
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A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) containing 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3− in air and/or ...precipitation from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by precipitation gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet/bulk Nr deposition. On a national basis, the annual average concentrations (1.3–47.0 μg N m−3) and dry plus wet/bulk deposition fluxes (2.9–83.3 kg N ha−1 yr−1) of inorganic Nr species are ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 (mean ± standard deviation) and 19.3 ± 9.2 kg N ha−1 yr−1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atmospheric dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.
Heat stress limits wheat production and trehalose can improve stress tolerance. How trehalose affects wheat respiration is unclear. In this study, we investigated the effects of exogenous trehalose ...on the respiration of wheat seedlings during heat stress and the subsequent recovery period. Trehalose pretreatment significantly increased the expression of the alternative oxidase genes AOX1a and AOX1c under heat stress, indicating that trehalose pretreatment increased the capacity of the alternative respiration pathway (AP) in response to heat stress. Trehalose pretreatment also enhanced the activity of the malate-oxaloacetate (Mal-OAA) shuttle and ameliorated the decrease in photosynthetic activity caused by heat stress. However, when the AP was inhibited by salicylhydroxamic acid under heat stress, both Mal-OAA shuttle activity and photosynthetic efficiency were substantially reduced in the control and trehalose pretreatment groups. In addition, trehalose pretreatment helped to maintain inner mitochondrial respiratory activity and the activity of Complex II during heat stress, particularly the coupling of oxidative phosphorylation with the Complex II electron transport chain, thereby mitigating heat-related damage to the cytochrome pathway (CP). Taken together, these results suggest that exogenous trehalose enhanced the AP and reduced damage to the CP under heat stress in wheat seedlings, thus maintaining cellular energy metabolism. Up-regulation of the AP by trehalose pretreatment may improve the heat tolerance of wheat seedlings by dissipating excess reducing equivalents transported through the Mal-OAA shuttle, thereby protecting photosynthetic performance.
Band topology of materials describes the extent Bloch wavefunctions are twisted in momentum space. Such descriptions rely on a set of topological invariants, generally referred to as topological ...charges, which form a characteristic class in the mathematical structure of fiber bundles associated with the Bloch wavefunctions. For example, the celebrated Chern number and its variants belong to the Chern class, characterizing topological charges for complex Bloch wavefunctions. Nevertheless, under the space-time inversion symmetry, Bloch wavefunctions can be purely real in the entire momentum space; consequently, their topological classification does not fall into the Chern class, but requires another characteristic class known as the Stiefel-Whitney class. Here, in a three-dimensional acoustic crystal, we demonstrate a topological nodal-line semimetal that is characterized by a doublet of topological charges, the first and second Stiefel-Whitney numbers, simultaneously. Such a doubly charged nodal line gives rise to a doubled bulk-boundary correspondence-while the first Stiefel-Whitney number induces ordinary drumhead states of the nodal line, the second Stiefel-Whitney number supports hinge Fermi arc states at odd inversion-related pairs of hinges. These results experimentally validate the two Stiefel-Whitney topological charges and demonstrate their unique bulk-boundary correspondence in a physical system.
Storm surges are responsible for much of the damage and loss of life associated with landfalling tropical cyclones (TCs). Thus, understanding the characteristics of risk associated with TC storm ...surges for the coastal regions of China is of great interest. Based on a comprehensive assessment of hazard indices for TC storm surges and vulnerability indices for coastal counties, we obtained a risk assessment for coastal regions of China as a county‐level unit. The hazard index was calculated using a model based on the parameters of a TC landfall frequency index (f) and maximum storm surge elevation (MSSE). The MSSE was calculated from the TC maximum sustained wind and tide gauge records using a regression function. Vulnerability indices were obtained from indices on socioeconomics, land use, the ecological environment, and resilience. From this study, it can be concluded that the hazard level of TC storm surges increases from north to south along the Chinese coast, the vulnerabilities have significant spatial heterogeneity, and coastal regions of China can be divided into four zones of risk level. The results of this study can provide scientific support for marine disaster mitigation and decision making. Additionally, the risk assessment methodology used here for storm surges could be extended and applied to other coastal areas.
Key Points
Developed a parametric representation of hazard on tropical storm surge
Estimated the vulnerabilities for coastal regions of China
Divided the coastal region of China into four risk level zones
There is increasing evidence that mitochondrial genomes (mitogenomes) can be under selection, whereas the selective regimes shaping mitogenome evolution remain largely unclear. To test for mitogenome ...evolution in relation to the climate adaptation, we explored mtDNA variation in two spider mite (Tetranychus) species that distribute across different climates. We sequenced 26 complete mitogenomes of Tetranychus truncates, which occurs in both warm and cold regions, and nine complete mitogenomes of Tetranychus pueraricola, which is restricted to warm regions. Patterns of evolution in the two species’ mitogenomes were compared through a series of dN/dS methods and physicochemical profiles of amino acid replacements. We found that: (1) the mitogenomes of both species were under widespread purifying selection; (2) elevated directional adaptive selection was observed in the T. truncatus mitogenome, perhaps linked to the cold climates adaptation of T. truncatus; and (3) the strength of selection varied across genes, and diversifying positive selection detected on ND4 and ATP6 pointed to their crucial roles during adaptation to different climatic conditions. This study gained insight into the mitogenome evolution in relation to the climate adaptation.
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