scholarly journals Experimental Evidence for a General Model of Modulated MOF Nanoparticle Growth

2020 ◽  
Author(s):  
Checkers R. Marshall ◽  
Sara Staudhammer ◽  
Carl Brozek
Keyword(s):  
Experimental Evidence ◽  
Reliable Control ◽  
Particle Sizes ◽  
Nanoparticle Growth ◽  
Seesaw Model ◽  
Polymer Formation ◽  
Metal Organic ◽  
High Concentrations ◽  
Solution Acidity ◽  
Metal Ligand

<p>Nanoparticles of metal-organic frameworks (nanoMOFs) boast superior properties compared to their bulk analogs, yet little is known about how common synthetic parameters dictate particle sizes. Here, we provide experimental evidence for the “seesaw” model of nanoMOF growth. Solution acidity, ligand excess, and reactant concentrations are decoupled and shown to form the key independent determinants of nanoMOF sizes, thereby validating the proposal that nanoMOFs arise from coupled equilibria involving ligand deprotonation and metal-ligand complexation. By achieving the first demonstration of a seesaw relationship between nanoMOF sizes and ligand excess, these results provide further proof of the model, as they required deliberate manipulation of relationships outlined by the model. Exploring the relative impacts of these parameters reveals that ligand excess has the greatest ability to decrease sizes, although low acidity and high concentrations can exhibit similar effects. As a complement to existing models of polymer formation and crystal growth, the seesaw model therefore offers a powerful tool for reliable control over nanoMOF sizes.</p>

scholarly journals Experimental Evidence for a General Model of Modulated MOF Nanoparticle Growth

2020 ◽  
Author(s):  
Checkers R. Marshall ◽  
Sara Staudhammer ◽  
Carl Brozek
Keyword(s):  
Experimental Evidence ◽  
Reliable Control ◽  
Particle Sizes ◽  
Nanoparticle Growth ◽  
Seesaw Model ◽  
Polymer Formation ◽  
Metal Organic ◽  
High Concentrations ◽  
Solution Acidity ◽  
Metal Ligand

<p>Nanoparticles of metal-organic frameworks (nanoMOFs) boast superior properties compared to their bulk analogs, yet little is known about how common synthetic parameters dictate particle sizes. Here, we provide experimental evidence for the “seesaw” model of nanoMOF growth. Solution acidity, ligand excess, and reactant concentrations are decoupled and shown to form the key independent determinants of nanoMOF sizes, thereby validating the proposal that nanoMOFs arise from coupled equilibria involving ligand deprotonation and metal-ligand complexation. By achieving the first demonstration of a seesaw relationship between nanoMOF sizes and ligand excess, these results provide further proof of the model, as they required deliberate manipulation of relationships outlined by the model. Exploring the relative impacts of these parameters reveals that ligand excess has the greatest ability to decrease sizes, although low acidity and high concentrations can exhibit similar effects. As a complement to existing models of polymer formation and crystal growth, the seesaw model therefore offers a powerful tool for reliable control over nanoMOF sizes.</p>

scholarly journals Experimental Evidence for a General Model of Modulated MOF Nanoparticle Growth

2020 ◽  
Author(s):  
Checkers R. Marshall ◽  
Sara Staudhammer ◽  
Carl Brozek
Keyword(s):  
Experimental Evidence ◽  
Reliable Control ◽  
Particle Sizes ◽  
Nanoparticle Growth ◽  
Seesaw Model ◽  
Polymer Formation ◽  
Metal Organic ◽  
High Concentrations ◽  
Solution Acidity ◽  
Metal Ligand

<p>Nanoparticles of metal-organic frameworks (nanoMOFs) boast superior properties compared to their bulk analogs, yet little is known about how common synthetic parameters dictate particle sizes. Here, we provide experimental evidence for the “seesaw” model of nanoMOF growth. Solution acidity, ligand excess, and reactant concentrations are decoupled and shown to form the key independent determinants of nanoMOF sizes, thereby validating the proposal that nanoMOFs arise from coupled equilibria involving ligand deprotonation and metal-ligand complexation. By achieving the first demonstration of a seesaw relationship between nanoMOF sizes and ligand excess, these results provide further proof of the model, as they required deliberate manipulation of relationships outlined by the model. Exploring the relative impacts of these parameters reveals that ligand excess has the greatest ability to decrease sizes, although low acidity and high concentrations can exhibit similar effects. As a complement to existing models of polymer formation and crystal growth, the seesaw model therefore offers a powerful tool for reliable control over nanoMOF sizes.</p>

scholarly journals Experimental evidence for a general model of modulated MOF nanoparticle growth

2020 ◽  
Vol 11 (42) ◽  
pp. 11539-11547 ◽  
Author(s):  
Checkers R. Marshall ◽  
Emma E. Timmel ◽  
Sara A. Staudhammer ◽  
Carl K. Brozek
Keyword(s):  
Experimental Evidence ◽  
General Model ◽  
Metal Organic Frameworks ◽  
Particle Sizes ◽  
Nanoparticle Growth ◽  
Metal Organic

Nanoparticles of metal–organic frameworks (nanoMOFs) boast superior properties compared to their bulk analogs, yet little is known about how common synthetic parameters dictate particle sizes.

ADMINISTRATION OF GLUCURONIC ACID TO ICTERIC NEWBORN INFANTS

PEDIATRICS ◽  
1959 ◽  
Vol 23 (1) ◽  
pp. 92-97
Author(s):  
Gloria Jeliu ◽  
Rudi Schmid ◽  
Sydney Gellis
Keyword(s):  
Experimental Evidence ◽  
Exchange Transfusion ◽  
Glucuronic Acid ◽  
Newborn Infants ◽  
Significant Change ◽  
High Concentrations

Fourteen icteric newborn infants were treated with varying amounts of glucuronic acid or sodium glucuronate, administered by oral or intravenous routes. No significant change in concentration of bilirubin in the serum was observed. Experimental evidence and biochemical considerations do not suggest that the administration of glucuronic acid enhances the formation of bilirubin glucuronide. It is the authors' opinion that at present the use of glucuronic acid should not be considered as an alternative for exchange transfusion in the treatment of newborn infants with high concentrations of bilirubin in the serum.

The isolation of nucleic acids from woody tissue using dimethyl sulfoxide

1972 ◽  
Vol 50 (5) ◽  
pp. 1085-1090 ◽  
Author(s):  
L. V. Gusta ◽  
V. C. Runeckles
Keyword(s):  
Nucleic Acids ◽  
Experimental Evidence ◽  
Dimethyl Sulfoxide ◽  
Ribonuclease Activity ◽  
Woody Tissue ◽  
Bark Tissue ◽  
High Concentrations ◽  
High Degree

A procedure is described for the isolation of nucleic acids from apple bark tissue using dimethyl sulfoxide. Nucleic acids isolated by this method are high in yield, and exhibit a high degree of purity as evidenced by their spectra. Experimental evidence is given to show that extraction of the tissue with dimethyl sulfoxide before the extraction of nucleic acids removes protein and pigments. Little or no ribonuclease activity could be detected in apple bark tissue after extraction with dimethyl sulfoxide. Ribonuclease activity was shown to be strongly inhibited by high concentrations of dimethyl sulfoxide.

scholarly journals Composition, stability and stereo effects of zirconium(IV) dl-tartrate formation

2019 ◽  
Vol 57 (2) ◽  
pp. 28-34
Author(s):  
Lilia I. Mukhamedyarova ◽  
◽  
Sergey G. Bezryadin ◽  
Elena Yu. Klukvina ◽  
Vladimir V. Chevela ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Ph Value ◽  
Acid System ◽  
Alkaline Ph ◽  
Titration Method ◽  
Software Complex ◽  
Tartaric Acids ◽  
Potentiometric Titration Method ◽  
High Concentrations ◽  
Metal Ligand

The system of zirconium (IV) – dl-tartaric acid for metal: ligand 1: 1, 1: 2 and 1: 3 ratios in aqueous solution has been studied by means of using potentiometric titration method in combination with mathematical modeling. The comparison of Bjerrum functions from pH for zirconium(IV) systems: d-tartaric acid and zirconium (IV): dl-tartaric acid, has revealed the following features in the behavior of the curves: the degree of titration for the complexes at a fixed pH value for systems with dl-tartaric acid is more than for d-acid. The CPESSP software complex has calculated the composition, stability constants and molar fractions of zirconium(IV) tartrate accumulation. It has been also found that at a ratio of 1: 1 for Zr (IV) and ligand (H4Tart) ions in the system under study ZrHTart+ is formed, which is tetramerized into Zr4Tart40 and, further, tetranuclear particles of varying degrees of deprotonization are formed, as well as mononuclear forms. In a strongly alkaline pH environment > 10, Bjerrum curves for d- and dl-tartaric acids overlap each other and correspond to hydroxocomplexes of varying degrees of titration. For the 1: 2 ratio, the composition of the complexes for the zirconium(IV) – dl-H4T system is slightly different; compared to the zirconium(IV) – dH4T system, differences are clearly observed for both low and high concentrations. Based on these data, a complex formation scheme in the Zr(IV) – dl-tartaric acid system has been proposed for all the ratios studied. The characteristics of stereoselective diastereomer formation have been calculated. It has been revealed that in the medium of racemic tartrate, ddd- and lll-Zr(H2Tart)2(HTart)3-forms, as well as Zr(H2Tart)(НTart)24-Zr(HTart)35- are formed on a stereoselective basis.

scholarly journals CONCENTRATION AND SIZE OF AIRBORNE PARTICLES IN MANUFACTURING ENVIRONMENTS

2018 ◽  
Vol 42 (1) ◽  
Author(s):  
Renilson Luiz Teixeira ◽  
Raphael Nogueira Rezende ◽  
José Reinaldo Moreira da Silva ◽  
Luana Elís de Ramos e Paula
Keyword(s):  
Medium Density Fiberboard ◽  
Work Environments ◽  
Airborne Particles ◽  
Protective Equipment ◽  
Particle Sizes ◽  
Small Particles ◽  
Measuring Process ◽  
Minas Gerais State ◽  
High Concentrations ◽  
Manufacturing Environments

ABSTRACT In furniture factories, the cutting of medium density fiberboard (MDF) generates high concentrations of particulates suspended in the air, which, depending on their dimensions, can reach the sensitive areas of the respiratory tract of workers. The aim of this study was to test a method to measure particle sizes derived from the cutting of wood paneling. The experiment was conducted in two small furniture factories located in the municipality of Lavras, Minas Gerais state, Brazil. During the cutting of MDF, airborne particles were collected and measured by means of optical microscopy. The data obtained showed a critical condition in the work environments, with high concentrations of small particles (<10 microns), which could be lodged in the workers’ lungs. The particle measuring process proved to be accurate and easy to perform. In addition, it is worth noting the importance of investment in personal protective equipment (PPE) such as hoods and/ or PFF2 dust masks for the protection of workers.

scholarly journals Facile stabilization of a cyclodextrin metal–organic framework under humid environment via hydrogen sulfide treatment

RSC Advances ◽  
2019 ◽  
Vol 9 (32) ◽  
pp. 18271-18276 ◽  
Author(s):  
Duo Ke ◽  
Jun-Feng Feng ◽  
Di Wu ◽  
Jun-Bo Hou ◽  
Xiao-Qin Zhang ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Water Adsorption ◽  
Metal Organic Framework ◽  
Moisture Resistance ◽  
Adsorption Sites ◽  
Humid Environment ◽  
Metal Organic ◽  
Metal Ligand ◽  
Organic Framework

The moisture stable γ-CD-K-MOF was obtained by simply treating MOF with H2S gas. H2S acting as new water adsorption sites protected the metal–ligand bonds from water attack and thus enhanced the moisture resistance of γ-CD-K-MOF.

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