ABSTRACT
Metal-organic frameworks (MOFs) have captured the imagination of researchers for their highly tunable properties and many potential applications, including as catalysts for a variety of transformations. Even though MOFs possess significant potential, the challenges associated with processing of these crystalline powders into usable form factors while retaining their functional properties limit their end use applications. Herein, we introduce a new approach to construct MOF-polymer composites via 3D photoprinting to overcome these limitations. We designed photoresin composite formulations that use polymerization-induced phase separation to cause the MOF catalysts to migrate to the surface of the printed material, where they are accessible to substrates such as chemical warfare agents. Using our approach, MOF-polymer composites can be fabricated into nearly any shape or architecture while retaining both the excellent catalytic activity at 10 wt % loading of the MOF components and the flexible, elastomeric mechanical properties of a polymer.
ABSTRACT
Phytoliths, silica structures derived from plant residues in silicon (Si)-accumulating plant species, have recently been recognized as a sink and source of nutrients and a hosting phase for carbon sequestration in soil. While the solubility of phytoliths in relation to their respective nature and solution chemistry has been intensively studied, the combined effects of CO2 and temperature, two highly variable parameters in soil, have not been fully understood. We hypothesized that changes in CO2 and temperature may affect the dissolution rate, thereby resizing the soil phytolith pool. Rice straw phytoliths were obtained from either open burning or controlled heating of straw from 300 to 900 °C and used to determine their batch incubation kinetics in a closed chamber at CO2 concentrations of 0 to 15% vol. and a temperature range of 20 to 50 °C for six days. The results revealed a contrasting effect in which temperature and CO2 were correspondingly found to accelerate or decelerate the dissolution rate of phytoliths. Under the most dissimilar conditions, i.e., 0% vol. CO2 and 50 °C and 15% vol. CO2 and 20 °C, the discrepancy in solubility was approximately six-fold, indicating a high vulnerability of phytoliths to CO2 and temperature changes. This finding also suggests that the soil phytolith pool can be diminished in the case of either increasing soil temperature or decreasing CO2 flux. Calculations based on these data revealed that the dissolution rate of phytoliths could be increased by an average of 4.5 to 7.3% for each 1 °C increase in temperature. This finding suggests a possible impact of current global warming on the global biogenic silica pool, and more insight into the relationship between this pool and climate change is, therefore, necessary to maintain the function of the phytolith phase in soil.
Subject(s)
Carbon Dioxide , Carbon Sequestration , Carbon Dioxide/analysis , Soil , Solubility , TemperatureABSTRACT
BACKGROUND: Osteoarthritis (OA) is a clinical syndrome characterized by joint failure that is accompanied by pain and functional limitations. OA is the leading cause of chronic disability in elderly and it is estimated that the United States spends $185 billion in management of OA annually. Although OA patients receive both pharmacologic and non-pharmacologic treatments, none of them provide long-lasting treatments. Since 1980s, autologous chondrocyte transplantation (ACT) has been used to regenerate cartilage within focal cartilage defects of young patients without pre-existing OA with increased functionality by 74% to 90%. In this technique, chondrocytes are removed from patients, multiplied in vitro, then implanted into the focal cartilage defect. Our review aimed to compare chondrocyte gene expression profiles of non-OA patients with OA patients to determine if OA-derived chondrocytes could be used for the ACT. METHODS: An extensive literature search was conducted with following criteria:(1) comparing chondrocyte gene expression profiles of OA joint and non-OA joint, or (2)relating to ACT. Ingenuity Pathway Analysis (IPA) was then utilized to analyze the differential chondrocyte gene expression profiles of OA to non-OA patients to identify key associated biological pathways. RESULTS: Differential gene expression profiles were similar between non-OA and OA chondrocytes: including ACAN, COL2A1, COL1A1, SOX 6 (p<0.001-0.05); FN1, COL11A1, MMP7, DLX5, SOX9, MMP2, TGFB1, THBS3, COMP, CILP2, ASPN, IGF2, DPT (p<0.001-0.05), and ADAMTS5, LAMA4 (p<0.01-0.05). CONCLUSION: These genes are important to cartilage function. Therefore, our results suggest that OA-derived chondrocytes may be useful to heal focal cartilage defects using ACT.
