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Key message: A gradual change exists in the altitudinal response of earlywood growth of Abies fargesii to hydrothermal conditions, with temperature being the main climatic factor controlling its latewood growth. The Tibetan Plateau, as the "Third Pole", has witnessed profound and intricate effects of climate change in recent decades. This may result in different responses of tree radial growth to climatic factors in this region, varying with elevation and growth stages. To accurately reveal these different responses we established totalwood, earlywood and latewood width chronologies of Abies fargesii at four elevations. Our results showed that: (1) As the elevation increases, the response of radial growth of Abies fargesii to climatic factors shifted from restriction primarily by water deficiency caused by rapid warming, to weak restriction by winter precipitation with favorable hydrothermal conditions, and then to double restriction owing to insufficient heat and excessive moisture. This pattern was inconsistent with the relationship between the radial growth and climatic factors for latewood observed at the low and middle–low elevations. (2) There existed a temporal variability in the relationship between tree radial growth and restrictive climate factors. This unstable relationship was mainly observed in the middle–low elevation within suitable ecological conditions and during the later stages of tree radial growth with lower growth rates. This is related to the fact that more suitable ecological conditions and lower growth rates make tree growth more susceptible to climatic fluctuations. Considering these findings, if the climate would experience further cooling and humidity increasing in the study region, the growth of Abies fargesii might be more adversely affected at high elevation. For economic and ecological considerations, the afforestation of Abies fargesii should be prioritized in the middle–low elevation zones where favorable for the population distribution. [ABSTRACT FROM AUTHOR]

Nonstructural carbohydrates (NSCs) reflect the carbon balance in trees and play a central role in their responses to environmental stresses. However, our understanding of tree NSC storage dynamics under environmental stress is unclear. Here, we quantified the deciduous conifer Larix principis-rupprechtii at five altitudes on Luya Mountain, North-Central China. We measured NSCs in different organs and simultaneously monitored environmental variables during the growing seasons in 2018 and 2019. The results showed that temperature was the main environmental factor affecting tree NSCs. Furthermore, as the soil–atmosphere temperature gradient decreased, the concentrations of soluble sugars in the needles increased while their starch decreased, as well as the concentrations of starch in the shoots, stems, and roots increased. These results may indicate that temperature gradients may assist carbohydrate allocation within individual trees. The NSCs, especially starch, in the needles increased with lower soil moisture, and the soluble sugars and starch in the needles and shoots increased with a higher vapor pressure deficit. The soluble sugars in the stems were significantly affected by soil moisture, and the NSCs in the roots were mainly affected by temperature. These results provide new insights to improve our understanding of the environmental stress effects on future forest C balances. [ABSTRACT FROM AUTHOR]

Due to their excellent physical and chemical properties, boron nitride nanosheets (BNNSs) have shown great application potential in many fields. However, the difficulty in scalable preparation of large-size BNNSs is still the current factor that limits this. Herein, a simple yet efficient microwave-assisted chemical exfoliation strategy is proposed to realize scalable preparation of BNNSs by using perchloric acid as the edge modifier and intercalation agent of h-BN. The as-obtained BNNSs behave a thin-layered structure (average thickness of 3.9 nm) with a high yield of ∼16%. Noteworthy, the size of BNNSs is maintained to the greatest extent so as to realize the preparation of BNNSs with ultra-large size (up to 7.1 µm), which is the largest so far obtained for the top-down exfoliated BNNSs. Benefiting from the large size, it can significantly improve the thermal diffusion coefficient and the thermal conductivity of polyvinyl alcohol by 51 and 62 times respectively, both showing a higher value than the one previously reported. This demonstrates that the prepared BNNSs have great promise in enhancing the thermal conductivity of polymer materials. [ABSTRACT FROM AUTHOR]

Graphene films prepared through a self-assembly of graphene oxide and its derivatives have been recently explored for electromagnetic interference (EMI) shielding applications. However, this film preparation usually requires long-time high-temperature annealing, leading to a dramatic increase in energy and time-consumption and thus the total cost of mass production. Herein, a free-standing, highly flexible and conductive graphene film was fabricated via a simple and inexpensive method. The fabrication process starts with the chemical exfoliation of graphite in a novel binary-component system comprised of sodium peroxyborate and sulfuric acid, as a graphene suspension, which is then vacuum-filtered and mechanically pressed, not involving high-temperature post-treatment. The obtained graphene film shows excellent electrical conductivity of 1.53 × 106 S m−1. More importantly, it also exhibits an ultrahigh EMI SE of 68 dB at a frequency of 8.2–12.4 GHz, which can block 99.99999% of incident radiation. To the best of our knowledge, this is the highest EMI SE performance reported so far in such thin thickness (about 3.2 μm) of pure graphene materials. These outstanding properties make this ultrathin graphene film a promising alternative building block for electronic devices. [ABSTRACT FROM AUTHOR]

In this study, ozone-oxidation was used to treat synthetic chemical plating solution containing Cu(II)/Ni(II)-EDTA solution to realize the purpose of decomplexation. The effects of solution pH, initial concentration of Cu(II)/Ni(II)-EDTA, the molar ratio of EDTA to Cu(II)/Ni(II), and the coexistence of Cu(II)/Ni(II) on their removal efficiencies were investigated. The degradation of EDTA-Cu(II) and EDTA-Ni(II) were mainly attributed to OH oxidation, and the removal rates of Cu(II)/Ni(II) depend on the complete decomplexation. The removal rates of Cu(II) and Ni(II) was affected by the pH of solution, and the optimal pH was found to be 7–9; nevertheless, their removal rates can still be up to 90% even in acidic pHs of 3~5. When the molar ratio of EDTA to Cu(II)/Ni(II) increased from 1:1 to 3:1, the kinetics of metal ion removal rate declined from 0.0788 and 0.1139 min-1 to 0.0250 and 0.0271 min-1. The synergistic effect was found in the Cu(II)/Ni(II) blended system due to the higher catalytic capability and the lower complexation affinity toward EDTA for Ni(II). In summary, ozone oxidation can be considered as an effective technology to realize the complete decomplexation of Cu(II)/Ni(II)-EDTA that contained in chemical plating industry wastewater. [ABSTRACT FROM AUTHOR]

Transitional climate zones (TCZ) are characterized by instability due to rapid changes in climate and biological variables, and trees growing there are particularly sensitive to climate change. Therefore, knowledge about the shifted relationships of tree growth in response to climate warming will shape regional forest conservation and management strategies. China has experienced rapid warming in recent decades. However, how tree growth in semihumid to semiarid regions, such as the Guandi Mountains, responds to more sophisticated changes in the hydrothermal combination is not yet clear. In this study, we used tree-ring width data from three sites along an elevational gradient in the Guandi Mountains to present the response of Picea wilsonii Mast. radial growth to increasing temperature and elevational differences in the relationship between tree growth and climate. The results indicated that the Guandi Mountains have experienced rapid warming with a clear trend toward aridity. From 1959 to 1995, the radial growth of P. wilsonii was mainly influenced by temperature, while it was controlled by both temperature and precipitation after rapid warming in 1996. From 1959 to 2017, this species showed a generally consistent growth–climate relationship at different elevations in the Guandi Mountains. However, the radial growth of trees at higher elevations had a higher climatic correlation than at lower elevations, and it was more conditioned by higher summer temperatures and precipitation in December of the previous year. These results suggested that P. wilsonii was more susceptible to drought and high temperatures due to a warming climate and that more attention should be devoted to forest management, especially the adverse consequences of summer drought on P. wilsonii. [ABSTRACT FROM AUTHOR]