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Low-dimensional organic-inorganic hybrid metal halides (OIMHs) have become an emerging class of light-emitting materials. Two zero-dimensional (0D) lead-free organic (EnrofloH 2) 4 Mn 3 X 12 (X = Cl, Br) has been reported in this work. Upon 338 and 340 nm excitation, (EnrofloH 2) 4 Mn 3 Cl 12 ·2Cl and (EnrofloH 2) 4 Mn 3 Br 12 ·2Br exhibit emission peaking at 460, 514 nm and 460, 520 nm respectively. It was noticed that the choice of the halide could profoundly govern the luminescent subjects (ENR or Mn2+) through the altered energy transfer. Different halogens could influence the rigidity of ENR organic cations by changing their stacking patterns and band gaps, thus manipulating their luminescent properties. The bandgap behaviors have been revealed by density functional theory calculations. Based on the results, the emission of both compounds come from organic cations (EnrofloH 2 2+) and 4D-6A 1 transition of Mn2+ ions. The spectral interplay of these emission bands is governed by the temperature and the possibility of exchanging mechanisms between two emission centers. • Novel two zero-dimensional organic−inorganic hybrid metal halides of (EnrofloH 2) 4 Mn 3 X 12 were successfully prepared. • The crystal structure and photoluminescence properties were investigated in detail. • It presents an interesting study into tuning luminescence properties by using different halides. [ABSTRACT FROM AUTHOR]

A series of CaLa 1- x LiTeO 6 : x Dy3+ phosphors were synthesized via a conventional solid-state reaction method, and the effects of different Dy3+ doping concentrations on the luminescence properties of the phosphors were studied. The excitation spectrum indicated that these synthesized phosphors had strong absorption bands in near-ultraviolet (n-UV) region in the range from 300 to 500 nm. There were two sharp emission peaks in the visible region, which were located at 483 nm, 574 nm, corresponding to transitions of 4F 9/2 →6H 15/2 (magnetic dipole transition) and 4F 9/2 →6H 13/2 (electric dipole transition), respectively. The phosphor CaLa 0.95 LiTeO 6 :0.05Dy3+ shows superior thermal stability. When the temperature rises to 425 K, the luminous intensity remains at 79% compared with the initial intensity of 300 K. These results demonstrate that the CaLa 1- x LiTeO 6 : x Dy3+ phosphors have great potential as a single-phase luminescence material for near-ultraviolet (n-UV) excitation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Climate change and freeze–thaw cycle influence the soil hydrological process in active layer. • The interaction of soil and plants alters the soil hydrothermal process in the active layer. • The actual available soil water state within root layers indicate the stability of alpine ecosystems. The hydrological properties of the active soil layer are the key parameters that regulate soil water–heat–solute migration and alter hydrologic cycles in a permafrost region. To date, much remains unknown about the interaction mechanism between permafrost degradation and eco-hydrological processes in the permafrost regions of the Qinghai–Tibet Plateau (QTP). In this study, the soil texture, soil hydrological properties, the soil moisture status, and the hydrothermal processes were measured and analyzed in different degradation degrees of alpine meadow soils on the QTP. The results showed a close relationship between soil hydrological properties and soil physicochemical properties. Freeze–thaw cycles changed the physicochemical and hydrological properties, that is, frequent freeze–thaw cycles promote to permafrost degradation in terms of soil basis properties of active layer. In addition, vegetation on the ground delayed the degradation of frozen soil. The actual available soil water content (SWC) in the root layer was a key factor in the ecohydrological process. The actual effective SWC in the root layers of different alpine meadows was ranked as follows: non-degraded meadow (NDM) > moderately-degraded meadow (MDM) > seriously degraded meadow (SDM) (1.8–5.0% at NDM and 0.0–4.2% at SDM). In addition, the weak soilpermeability in an SDM intensified the deficiency of the available SWC, thereby increasingthe difficulty of ecological restoration. This study provides a basis for ecological environmental protection in permafrost regions and provides a hydrological process model for cold regions under future climate change scenarios. [ABSTRACT FROM AUTHOR]

• The freeze–thaw cycle affected the soil hydrological process in active layer; • There were significant differences in soil hydrothermal processes at the slope scales and profile scales; • The redistribution of soil water during the freezing and thawing periods is affected by vegetation." The Qinghai-Tibet Plateau (QTP) is a region with an extensive area of permafrost that is very sensitive to climate change. In this study, soil water and thermal dynamic processes in the active layer of the QTP permafrost area at the profile and slope scales were investigated. The results showed that the hydrothermal process in the active layer soil was strongly affected by freezing and thawing processes and external weather conditions. The temperature of the active layer fluctuated in tandem with air temperature. The soil water content was more stable during the freezing period and showed a "double-hump" trend during the thawing period. The correlation coefficient between soil and air temperature decreased with depth, from 0.896 in the surface soil layer to 0.082 in the deep soil layer; and the correlation coefficient between unfrozen water content and soil temperature during the freezing period showed an overall increasing trend with depth. The soil layers at different depths at the top and bottom of slope profiles differed in their hydrothermal processes due to the physicochemical properties and texture of the soil and vegetation types. The water-heat exchange of the surface soil is more frequent than that of the deep soil, and the frequency is more at the bottom than at the top of the slope. The soil water content at a depth of 0.25 m was the highest in the profile in association with a higher organic matter content and the blocking effect of dense roots. The changes of soil hydrothermal process in the active layer accelerated the hydrological cycle and the spatial–temporal variability in water resources in the frozen soil area. These effects might lead to a series of ecological and environmental problems, such as permafrost degradation and desertification in the QTP alpine meadow ecosystem. [ABSTRACT FROM AUTHOR]

• Heterogeneity of soil hydrothermal processes and soil structure in undegraded meadows and degraded bare ground. • Vegetation degradation in concert with freeze–thaw affects soil structure in the active layer. • Changes in soil structure in the active layer reveal the response of soil hydrological processes to the external environment. The soil structure is the key parameter that regulate soil water–heat–solute migration. To date, much remains unknown about the interaction mechanism between soil structure and the external environment in the permafrost regions. In this study, the undegraded meadow and degraded bare land in the permafrost region of the Qinghai–Tibet Plateau were used as research objects, and the soil structure characteristics and their influencing factors of the two sample sites were studied based on in situ hydrothermal observation data and CT scan. The results showed that the macropore system of the undegraded meadow was dominated by connected pores, with a small number of macropores, but the large volume, the shape mainly was elongated, and the connectivity was good. The degraded bare ground was dominated by isolated pores, with more large pores but smaller volume, more regular pore shape, and less pore connectivity than undegraded meadow. The macropore structure in both samples was affected by vegetation, freeze–thaw action, and soil moisture content. The undegraded meadow formed connected pores with mainly tubular pore aggregates in the soil layer above 23 cm due to the protective effect of vegetation roots, and only a few isolated pores existed in the deep soil layer below 23 cm due to weak freeze–thaw action and low moisture content. The daily freeze–thaw cycle days were long, and the complete freezing days were short for the degraded bare land. The frequent freeze–thaw action produced connected pores dominated by fractures, and many isolated pores, while the high water content of the deep soil intensified the freeze–thaw action, producing a large number of isolated pores and also increasing the depth of occurrence of macropores. The difference in the soil pore deepens the understanding of the relationship between the soil macropore and the soil hydrothermal process. [ABSTRACT FROM AUTHOR]

Up-conversion fluorescent materials serve a significant function as the detection materials of temperature sensors. In this study, a series of green-emitting LiLuW 2 O 8 :Yb3+, Er3+ phosphors applied in optical temperature sensing detection were successfully synthesized via the solid-state process in air. The crystal structure, luminescence properties, luminescence mechanism, and optical temperature sensing properties of samples were investigated. LiLuW 2 O 8 :Yb3+, Er3+ phosphor with excitation at 980 nm emits pronounced green emissions owing to the 2H 11/2 → 4I 15/2 and 4S 3/2 → 4I 15/2 transitions of Er3+ ions. The whole emission processes of LiLu 0.72 W 2 O 8 :0.24 Yb3+, 0.04Er3+ sample are all two-photon processes. Moreover, we apply thermal coupling levels (2H 11/2 , 4S 3/2) for temperature sensing and the value of sensing sensitivity can reach the maximum of about 1.41% K−1. All the experimental results imply that LiLuW 2 O 8 :Yb3+, Er3+ phosphors show good potential in temperature sensing. • Novel LiLuW 2 O 8 :Yb3+, Er3+ phosphors were successfully prepared for the first time. • The crystal structure and photoluminescence properties were investigated in detail. • The LiLuW 2 O 8 :Yb3+, Er3+ phosphors show high sensitivity for temperature sensing, and the S r was found to be as high as 1.41% K−1. • The present phosphors could have potential application in optical temperature sensors. [ABSTRACT FROM AUTHOR]