Role of the metal cation in the dehydration of the microporous metal–organic frameworks CPO-27-M

The dehydration of the CPO-27-M (M-MOF-74, M = Zn, Co, Ni, Mg, Mn, Cu) metal-organic framework series has been investigated comprehensively using in situ variable temperature powder X-ray diffraction (VT-PXRD) and thermal analysis (TG) coupled with mass spectrometry (MS). Significant differences in the order of water desorption from different adsorption sites on heating are found with varying metal cation in the otherwise isostructural material. For all CPO-27-M (except M = Cu), water is bonded significantly more strongly to the accessible open metal sites, and these water molecules are only desorbed at higher temperatures than the other water molecules. CPO-27-Cu is an exception, where all water molecules desorb simultaneously and at much lower temperatures (below 340 K). MS and TG data show that all CPO-27-M start to release traces of CO2 already at 300–350 K, and thus long before bulk thermal decomposition is observed. Only for CPO-27-Co, the CO2 release is essentially constant on its baseline between 450 and 700 K, and it is the only CPO-27-M member that shows a stable plateau in the TG in this region. Additional rehydration studies on CPO-27-Co show that the MOF incorporates any water molecules present until the pores are fully loaded. CPO-27-Co consequently behaves as an efficient trap for any water present

Root growth and crop performance of soybean under chemical, physical, and biological changes after subsoiling.

Chemical, physical and biological soil attributes can facilitate soybean root growth in greater volume and depth in the soil, which can minimize yield reduction caused by water deficit. Soil management can contribute positively or negatively to these soil attributes. The aim of this work was to evaluate the root growth and crop performance of soybean, in response to chemical, physical and biological changes after subsoiling at different depths. At the R5 phenological stage, trenches were made for sampling and soil collection for chemical, physical and biological analysis and root growth was carried out. At V5, V7, R2 and R5 stages, plants were collected to evaluate height, leaf area and dry mass. At V5, stage number and dry mass of the nodules were evaluated. Subsoiling increased pH and Ca, and decreased Al in the soil, resulted in higher relative density and did not affect in mechanical penetration resistance compared to non-subsoiled soil. Basal respiration and soybean nodulation were higher in the subsoiled soil. Up to 15 cm depth, there were 87.91% of the total root dry mass and 78.79% of the total root volume. Initial and final plant growth were the same in subsoiled and non-subsoiled soil. Number of nodules in the subsoiled soil was 28% higher than in the non-subsoiled soil. Under these study conditions, subsoiling provides lower root growth but benefits grain yield