Image_1_The Hierarchy of Protoxylem Groupings in Primary Root and Their Plasticity to Nitrogen Addition in Three Tree Species.TIF

Protoxylem grouping (PG), a classification based on the number of protoxylem poles, is a crucial indicator related to other functional traits in fine roots, affecting growth and survival of individual root. However, within root system, less is known about the arrangement of PG. Moreover, the responses of PG to fertilization are still unclear. Here, we selected three common hardwood species in Northeast China, Juglans mandshurica, Fraxinus mandshurica, and Phellodendron amurense, conducted root pruning and nutrient addition. In this study, we analyzed the PG, morphology, and other anatomy traits of newly formed root branches. The results showed all root length, diameter, and stele, as well as hydraulic conductivity, were significantly positive related to the PG number, and the PG number generally decreased with ascending root developmental order; these patterns were independent of species and fertilization. Additionally, we also found the plasticity of PGs to environmental changes, in terms of the increased frequency of high PG roots after fertilization, significantly in J. mandshurica and F. mandshurica. Therefore, the heterogeneity, hierarchy, and plasticity of individual roots within root system may be widespread in woody plants, which is of great significance to deepen our understanding in root growth and development, as well as the belowground ecological process.</p

Table_1_The Hierarchy of Protoxylem Groupings in Primary Root and Their Plasticity to Nitrogen Addition in Three Tree Species.DOCX

Protoxylem grouping (PG), a classification based on the number of protoxylem poles, is a crucial indicator related to other functional traits in fine roots, affecting growth and survival of individual root. However, within root system, less is known about the arrangement of PG. Moreover, the responses of PG to fertilization are still unclear. Here, we selected three common hardwood species in Northeast China, Juglans mandshurica, Fraxinus mandshurica, and Phellodendron amurense, conducted root pruning and nutrient addition. In this study, we analyzed the PG, morphology, and other anatomy traits of newly formed root branches. The results showed all root length, diameter, and stele, as well as hydraulic conductivity, were significantly positive related to the PG number, and the PG number generally decreased with ascending root developmental order; these patterns were independent of species and fertilization. Additionally, we also found the plasticity of PGs to environmental changes, in terms of the increased frequency of high PG roots after fertilization, significantly in J. mandshurica and F. mandshurica. Therefore, the heterogeneity, hierarchy, and plasticity of individual roots within root system may be widespread in woody plants, which is of great significance to deepen our understanding in root growth and development, as well as the belowground ecological process.</p

Clean Hydrogen Release from Ammonia Borane in a Metal–Organic Framework with Unsaturated Coordinated Tm³⁺

A hybrid of ammonia borane (AB) and a metal–organic framework (MOF), which contains unsaturated coordinated Tm³⁺, Tm­(BTC) (BTC = 1,3,5-benzenetricarboxylic), was synthesized through the solvent-based impregnation method (named as AB@Tm­(BTC)–CH₃OH). Also two other materials AB@Tm­(BTC)-milled and AB@Tm₂O₃-milled were prepared by physical milling separately. TPD-MS results show that the H₂-release peaks of the three materials shift to lower temperature, 77, 79, and 85 °C, respectively, compared with neat AB (114 and 150 °C). To avoid the undesirable volatile byproduct, only AB@Tm­(BTC)–CH₃OH shows superior performance without any byproduct, especially ammonia. The three samples exhibit enhanced dehydrogenation kinetics compared to neat AB, but AB@Tm₂O₃-milled presents much slower than the other two materials. The dehydrogenation activation energies of AB@Tm­(BTC)–CH₃OH, AB@Tm­(BTC)-milled, and AB@Tm₂O₃-milled are 98.1, 103.1, and 116.4 kJ·mol^–1, respectively. The mechanisms of the AB@MOF thermal dehydrogenation system especially for the prevention of ammonia have been discussed. The interaction between AB and the unsaturated coordinated metal sites in MOFs plays a key role for inhibiting ammonia during AB thermolysis