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Drought presents a significant abiotic stress that threatens crop productivity worldwide. Rhizosphere bacteria play pivotal roles in modulating plant growth and resilience to environmental stresses. Despite this, the extent to which rhizosphere bacteria are instrumental in plant responses to drought, and whether distinct cassava (Manihot esculenta Crantz) varieties harbor specific rhizosphere bacterial assemblages, remains unclear. In this study, we measured the growth and physiological characteristics, as well as the physical and chemical properties of the rhizosphere soil of drought-tolerant (SC124) and drought-sensitive (SC8) cassava varieties under conditions of both well-watered and drought stress. Employing 16S rDNA high-throughput sequencing, we analyzed the composition and dynamics of the rhizosphere bacterial community. Under drought stress, biomass, plant height, stem diameter, quantum efficiency of photosystem II (Fv/Fm), and soluble sugar of cassava decreased for both SC8 and SC124. The two varieties' rhizosphere bacterial communities' overall taxonomic structure was highly similar, but there were slight differences in relative abundance. SC124 mainly relied on Gamma-proteobacteria and Acidobacteriae in response to drought stress, and the abundance of this class was positively correlated with soil acid phosphatase. SC8 mainly relied on Actinobacteria in response to drought stress, and the abundance of this class was positively correlated with soil urease and soil saccharase. Overall, this study confirmed the key role of drought-induced rhizosphere bacteria in improving the adaptation of cassava to drought stress and clarified that this process is significantly related to variety. [ABSTRACT FROM AUTHOR]

With the increase in global extreme climate events, the frequency of urban waterlogging caused by extreme rainstorms is increasing, resulting in serious economic losses and risk to local residents. Understanding the influence of impervious surfaces on urban waterlogging is of great significance for reducing urban waterlogging disasters. Based on InfoWorks ICM, the urban waterlogging model of Lin'an City was established, and the multi-scenario design method was used to analyze the characteristics and causes of urban waterlogging under different designed rainfall return periods. The results show that the maximum stagnant water depth and area are positively correlated with the proportion of impervious surfaces and rainfall return periods. In addition, urban waterlogging is related to the fragmentation of impervious surfaces, pipeline network, and so on. Based on the findings, it is suggested that impervious surfaces should be placed upstream and along roads where feasible. It is also recommended that the aggregation of impervious surfaces is minimized to prevent urban waterlogging. The results provide technical support and reference for local governments to prevent waterlogging disasters. [ABSTRACT FROM AUTHOR]

Limited by multiple factors, such as land use planning, landscape coordination and environmental standards, the ventilation conditions of the urban highway tunnels are insufficient, and therefore the joint control of ventilation and purification becomes a necessary solution. In this study, the effect of number, location of decentralized purification equipment, and the tunnel ventilation rate on pollution in the tunnel are studied using one-dimensional calculation. The results show that the arrangement of purification equipment can reduce the design ventilation rate to a certain extent. When purification equipment is arranged, the maximum NO2 concentration can be reduced by up to 30.9%, and the average NO2 concentration can be reduced by up to 18.2% compared with that without purification. The purification equipment arranged in the rear section of the tunnel is conducive to reducing the concentration of pollutants at the exit, while the arrangement in the middle section of the tunnel is conducive to reducing the average concentration of pollutants in the tunnel.

A total of 105 soil samples was collected from 21 villages/towns wheat farmland in 6 regions around Zhengzhou in June 2018, and the contents of heavy metals Pb, Cd, Cu and Zn in the soil samples were determined. Their distribution pattern and pollution status were analyzed. The results showed that the average values of Pb, Cu and Zn in the wheat farmland soil around Zhengzhou city were 12.22 mg ⋅ kg-1, 11.0 mg ⋅ kg-1 and 53.57 mg ⋅ kg-1 respectively, all lower than the soil environment quality standard and He'nan fluvo-aquic soil background value; with the increase of soil depth, the contents of these three kinds of heavy metals gradually decreased, and the content of Cd was not reduced; the contents of heavy metals in the wheat farmland soil in different regions was significantly different; among them, the contents of Pb, Cu and Zn in the wheat farmland soil in Gongyi city were relatively high; in the wheat farmland soil, the Pb content in 7 viilages/towns and the Zn content in 5 towns exceeded He'nan fluvo-aquic soil background value; and the Cu content and Cd content in 21 viilages/towns were lower than the He'nan fluvo-aquic soil background value; Cu and Pb might have homology, and Cu and Zn might be affected by multiple different pollution sources. The soil quality of wheat farmland around Zhengzhou was generally good, but the farmland soil with heavy metal content exceeding He'nan fluvo-aquic soil background value stiil needs to be monitored. Measures such as strengthening the publicization of agricultural knowledge such as land cultivation and using organic fertilizers instead of chemical fertilizers can improve the basic physical and chemical properties of the soil nature. [ABSTRACT FROM AUTHOR]

The photoluminescence properties of dopants are strongly correlated with their distributions in host phosphors, the knowledge of which, however, is not well established yet. In this paper, the distribution of the active dopants, for example, trivalent ytterbium (Yb3+) and bivalent nickel (Ni2+) in a highly transparent germanate glass‐ceramic containing thermally grown Zn1+xGa2−2xGexO4 (0 ≤ x ≤ 1) nanospinels, is revealed by an analytical transmission electron microscope. The elemental mapping and linescan analysis confirm that both Yb3+ and Ni2+ accumulate preferentially in the germanium‐substituted ZnGa2O4 nanospinels embedded in the glass. The influence of glass crystallization on the electric transition properties of Yb3+ is presented. An enhanced ultrabroadband near infrared emission of Ni2+ is observed as a result of efficient energy transfer from Yb3+ to Ni2+ accumulated in the nanocrystals. Discussions are given to account for the detailed mechanisms of the efficient energy transfer occurring between the dopants. [ABSTRACT FROM AUTHOR]

Abstract: Ni2+/Yb3+/Er3+/Tm3+ codoped transparent glass‐ceramics (GCs) containing both hexagonal β‐YF3 and spinel‐like γ‐Ga2O3 dual‐phase nanoparticles (NCs) are synthesized by melt‐quenching and subsequent heating procedures. Two techniques of transmission electron microscopy (TEM) nanoanalytics and optical spectroscopy are conjugated to understand the distribution of the rare‐earth ions (REs) and transition metals (TMs) in the nanostructured GCs. It is found that the REs are located predominantly in β‐YF3, whereas the TMs in γ‐Ga2O3 NCs. As a result, energy transfer (ET) between the REs and TMs is considerably suppressed due to the large spatial separation (> 3 nm), but it is enhanced between the REs partitioned in the β‐YF3 NCs. This has important implications for intended and demanding photoluminescence functions. For example, an ultrabroadband near‐infrared (NIR) emission in the wavelength region of 1000‐2000 nm covering the entire telecommunications window is observed for the first time. Meanwhile, intense upconversion (UC) emissions covering the 3 primary colors and locating in the first biological window can be also recorded under excitation by a single pump source at 980 nm. [ABSTRACT FROM AUTHOR]

Abstract: A new method is reported to achieve the manufacture of glass of arbitrary ratio of SiO2/P2O5 which cannot be made by conventional melt‐quenching method. The new method is termed “melt‐in‐melt” which encapsulates the key step in the glass manufacturing process, i.e. one molten glass is poured into another molten glass with a stirring at high temperatures. Because of near unlimited possibilities in designing new glass compositions, there is a correspondingly great degree of freedom in the topological engineering of the glass structure, which in turn strongly influences the photoluminescence (PL) properties of active dopants. As a proof concept, bismuth and erbium are selected as the indicator dopants for emphasizing the real advantages of the new method as an effective means to tailoring the PL properties of the doped glasses. The micro structure and element distribution within the fabricated glasses are comprehensively characterized by high‐resolution scanning electron microscopy, micro‐Raman and high‐performance X‐ray fluorescence spectroscopy. Phase separation occurring at both nano‐ and meso‐scale is observed. Apart from the developed glasses being themselves promising broadband emission phosphors, the new glass‐making method may extend the possible applications of glass for important photonic applications (e.g. optical sensing, lighting, display, optical amplification and lasing etc.). [ABSTRACT FROM AUTHOR]

Chalcogenide glasses (ChGs) containing II-VI chalcogenide (ChG) nanocrystals such as ZnS/Se have recently been intensively studied as promising mid-infrared nonlinear optics and laser materials, yet preparation of pure-phase II-VI nanocrystals embedded in ChGs via controlled crystallization is still very challenging. In this study, a new system of ChGs and glass ceramics (GCs), viz., (100-x)As2S3- xZnSe (x = 0 ~ 30 mol%), is synthesized, and its physical and optical properties including density, molar volume, microhardness, glass transition temperature, glass network structure, transmission, and refractive index are comprehensively characterized. Significantly, it is initially demonstrated that pure ZnS nanocrystals can be precipitated in GCs simply by a thermal treatment process. The composition and thermal treatment temperature dependencies of crystallization are studied using X-ray diffraction spectroscopy, and the morphology of the nanocrystals by high-resolution transmission electron microscope. The ChG GCs with embedded ZnS nanocrystals retaining good transparency can be a potential host laser material for divalent transition metals (e.g., Cr2+/Fe2+, etc.), and thus used for ultrabroadband tunable continuous or ultra-short-pulsed mid-infrared fiber lasers. [ABSTRACT FROM AUTHOR]