Assessment of the restoration potential for ecological sustainability in the Xijiang River basin, Southwest China: A comparative analysis of karst and non-karst areas.

Vegetation restoration is an eco-friendly strategy for countering land degradation and biodiversity loss. Since 2000-2001, large-scale restoration projects have been performed in Southwest China, with the net primary productivity (NPP) increasing over the past two decades. However, negative ecohydrological impacts, including streamflow decline and soil moisture deficit, have been reported following afforestation. Current understanding of the permissible NPP capacity (NPPcap) and NPP potential (NPPpot) under karst and non-karst areas or planted and natural vegetations constrained by environmental factors remains unclear. Here multiple environmental drivers characterizing the heterogeneous landscape in the Xijiang River Basin (Southwest China) were employed to predict the NPPcap using a random forest model. Results showed that 85% of the area exhibited an increasing trend in NPPcap during 2001-2018. Overall, 3.50% of the area has exceeded the NPPcap, implying an excessive plantation and potential water deficit in these areas. Excluding agriculture activities, urban areas, and water bodies, we found there is room for an average extra 22.85% of NPP enhancement. The NPPpot was spatially imbalanced, with high NPPpot located in the northeast, indicating these areas as a target area for future vegetation restoration. Moreover, the NPPpot reduction in karst areas (1.12 g C m-2 a-1) was more pronounced than in non-karst areas (0.26 g C m-2 a-1), highlighting a stronger negative impact on NPPpot in karst areas. Furthermore, significant NPPpot differences were found between planted vegetation and natural vegetation for both karst and non-karst areas. According to the findings, we identified four separate restoration sub-zones and proposed tailored strategies to guide the implementation of future restoration efforts. Our study highlights restoration potential and where land is available for reforestation but also the urgent need for future restoration activities towards ecosystem sustainability.

Balanced Mechanical and Biotribological Properties of Polymer Composites Reinforced by a 3D Interlocked Si3N4 Nanowire Membrane.

Polymer composites have great potential applications in the hip joint replacement, where the combinations of high mechanical strength and excellent biotribological properties are required. In this work, a well-dispersed three-dimensional (3D) silicon nitride nanowire membrane (SNm) designed as a reinforcement and brushite (Bs) served as bioactive filler are constructed into the polymer matrix, forming SNm-reinforced Bs/polymer composites (SNm-Bs/Pm). Especially, SNm could form a 3D interlocked structure, where the ultralong silicon nitride nanowires are entangled with each other. SNm could effectively facilitate the penetration of the polymer matrix and improve the cohesion strength of the polymer, thereby promoting mechanical and biotribological properties for SNm-Bs/Pm. The performances for polymer composites are optimized by increasing the layer number of preform. By comparing SNm-Bs/Pm with one-layer preform, the tensile strength of SNm-Bs/Pm with six-layer preforms reaches 83.3 MPa with an increase of 767.7%. In addition, the friction coefficient and wear rate of SNm-Bs/Pm with six-layer preforms in fetal bovine serum medium achieve 0.06 and 0.21 × 10-14 m3(N·m)-1 and decrease by 82.4 and 72.4%, respectively. The present work provides a promising methodology of preparing interlocked SNm-reinforced polymer composites with enhanced mechanical and biotribological properties that are potential for hip joint replacement applications.

Tetraanionic arachno-Carboranyl Ligand Imparts Strong Axiality to Terbium(III) Single-Molecule Magnets.

A family of fully sandwiched arachno-lanthanacarborane complexes formulated as {η6 -[µ-1,2-[o-C6 H4 (CH2 )2 ]-1,2-C2 B10 H10 ]2 Ln}{Li5 (THF)10 } (Ln=Tb, Dy, Ho, Er, Y) is successfully synthesized, where the "carbons-adjacent" carboranyl ligand (arachno-R2 -C2 B10 H10 4- ) bears four negative charges and coordinates to the central lanthanide ions using the hexagonal η6 C2 B4 face. Thus, the central lanthanide cations are pseudo-twelve-coordinate and have an approximate pseudo-D6h symmetry or hexagonal-prismatic geometry. As the crystal field effect imparted by this geometry is still unknown, we thoroughly investigated the magnetic properties of this series of complexes and found that the crystal field imposed by this ligand causes a relation of Tb>Dy>Ho>Er for the energy gaps between the ground and the first excited states, which is of striking resemblance to the ferrocenophane and phthalocyanine ligands although the latter two ligands give disparate local coordination geometries. Moreover, the effective energy barrier to magnetization reversal of 445(10) K, the observable hysteresis loop up to 4 K and the relaxation time of the yttrium-diluted sample reaching 193(17) seconds at 2 K under an optimized field for the Tb analogue of this family of arachno-lanthanacarborane complexes, render a new benchmark for Tb3+ -based single-molecule magnets.

Ion exchange collaborating coordination substitution: More efficient Cr(VI) removal performance of a water-stable CuII-MOF material.

An unusual water-stable cationic metal-organic framework {[Cu(L)0.5(bpe)(H2O)](NO3)•(H2O)0.5}n (1) (H4L = bis(3,5-dicarboxypyridinium)-p-xylylene) was synthesized, which was developed into an effective capture material for removal chromate from water. The results show that this material efficiently traps HCrO4- pollutant ions via single-crystal to single-crystal (SCSC) coordination substitution process. The HCrO4- uptake capacity of 1 is high to 190 mg/g. Meaningfully, the structure of 1-HCrO4 ({[Cu(L)0.5(bpe)(HCrO4)]}n) can be accurately obtained by single-crystal X-ray diffraction, where the chromate enter the framework to form stable coordination with central metal ions Cu2+. This is the first example of a stable coordination between chromate and the framework during the capture process. The captured HCrO4- are not dissociated easily into the solution due to the coordination bond. This interaction makes the enrichment of HCrO4- more stable and the capture capacity excellent. Furthermore, the HCrO4- releasing process displays good regeneration in a single crystal state, which further elaborates the reversible SCSC transformation. The mechanism of Cr(VI) removal was also confirmed by DFT calculation studies. This work provides a new way to design and develop efficient MOF capture materials.

Metal-dependent photocatalytic activity and magnetic behaviour of a series of 3D Co-Ni metal organic frameworks.

Crystalline MOF materials with adjustable properties are of great interest for multiple potential applications. In this study, a series of 3D isostructural mixed metal MOFs {[M3(L)2(4,4'-bpy)2(H2O)2]·14H2O}n (M = Co (1), Co0.7Ni0.3 (2), Ni0.5Co0.5 (3), Co0.3Ni0.7 (4), Co0.1Ni0.9 (5), and Ni (6); H3L = 1-aminobenzene-3,4,5-tricarboxylic acid) have been synthesized. The crystal color changed regularly with the increase in the Ni ion content from red to green, and a new ultraviolet absorption spectrophotometry method has been developed for the accurate determination of the metal content of Co in MOF materials. In the detection of magnetic behaviour, 1 shows antiferromagnetism. As the Ni ion component gradually increases in 2-6, the magnetic behaviour of the complexes appears to transition from antiferromagnetic to ferromagnetic. Moreover, complex 1 exhibits preeminent photocatalysis activity in the degradation of organic dyes under visible light irradiation. As the ratio of Ni ions increases gradually in the complexes, the photocatalytic activities of 1-6 decrease. This work offers controllable regulation of the photocatalytic properties and magnetic behaviour of MOFs by changing the metal ions.

Manganese(III)-mediated alkenyl C(sp2)-P bond formation from the reaction of ß-nitrostyrenes with dialkyl phosphites.

Mn(OAc)3-mediated tandem phosphonyl radical addition to ß-nitrostyrenes followed by denitration to form (E)-2-alkenyl phosphonates in good yield is described.