scholarly journals Fabrication of Agglomerate-Free Nanopowders by Hydrothermal Chemical Processing

1998 ◽  
Vol 520 ◽  
Author(s):  
H.K. Schmidt ◽  
R. Nass ◽  
D. Burgard ◽  
R. Nonninger

ABSTRACTA chemical processing technique for the fabrication of nanopowders has been developed. The route is based on precipitation processes in solutions, either within aqueous droplets in micro-emulsions in the presence of surface modifiers like surfactants or by direct precipitation in solutions in the presence of these surface modifiers or small organic molecules directly bonded to the particle surface. In order to obtain well crystallized or densified particles, a continuous flow hydrothermal process has been developed which allows the fabrication of agglomerate-free surface modified nanopowders. The surface modification provides a full redispersibility after drying and permits a water-based processing. Nanoparticles preparation for ZrO2, ITO and ATO by this route are described.

2019 ◽  
Author(s):  
Nikita A. Ivanov ◽  
Sven Kochmann ◽  
Sergey N. Krylov

Continuous-flow electrophoresis (CFE) separates a stream of a multi-component mixture into multiple streams of individual components inside a thin rectangular chamber. CFE will be able to benefit flow chemistry when it is capable of generically detecting streams of small organic molecules. Here we propose a general approach for molecular stream visualization via analyte-caused obstruction of excitation of a fluorescent layer underneath the separation chamber – fluorescent sublayer-based visualization (FSV). We designed and fabricated a CFE device with one side made of quartz and another side made of UV-absorbing visibly-fluorescent, chemically-inert, machinable plastic. This device was demonstrated to support non-aqueous CFE of small organic molecules and quantitative detection of their streams in real-time with a limit of detection below 100 µM. Thus, CFE may satisfy conditions required for its seamless integration with continuous flow organic synthesis in flow chemistry.<br>


2019 ◽  
Author(s):  
Nikita A. Ivanov ◽  
Sven Kochmann ◽  
Sergey N. Krylov

Continuous-flow electrophoresis (CFE) separates a stream of a multi-component mixture into multiple streams of individual components inside a thin rectangular chamber. CFE will be able to benefit flow chemistry when it is capable of generically detecting streams of small organic molecules. Here we propose a general approach for molecular stream visualization via analyte-caused obstruction of excitation of a fluorescent layer underneath the separation chamber – fluorescent sublayer-based visualization (FSV). We designed and fabricated a CFE device with one side made of quartz and another side made of UV-absorbing visibly-fluorescent, chemically-inert, machinable plastic. This device was demonstrated to support non-aqueous CFE of small organic molecules and quantitative detection of their streams in real-time with a limit of detection below 100 µM. Thus, CFE may satisfy conditions required for its seamless integration with continuous flow organic synthesis in flow chemistry.<br>


2020 ◽  
Vol 92 (4) ◽  
pp. 2907-2910 ◽  
Author(s):  
Nikita A. Ivanov ◽  
Sven Kochmann ◽  
Sergey N. Krylov

Author(s):  
Joshua Horton ◽  
Alice Allen ◽  
Leela Dodda ◽  
Daniel Cole

<div><div><div><p>Modern molecular mechanics force fields are widely used for modelling the dynamics and interactions of small organic molecules using libraries of transferable force field parameters. For molecules outside the training set, parameters may be missing or inaccurate, and in these cases, it may be preferable to derive molecule-specific parameters. Here we present an intuitive parameter derivation toolkit, QUBEKit (QUantum mechanical BEspoke Kit), which enables the automated generation of system-specific small molecule force field parameters directly from quantum mechanics. QUBEKit is written in python and combines the latest QM parameter derivation methodologies with a novel method for deriving the positions and charges of off-center virtual sites. As a proof of concept, we have re-derived a complete set of parameters for 109 small organic molecules, and assessed the accuracy by comparing computed liquid properties with experiment. QUBEKit gives highly competitive results when compared to standard transferable force fields, with mean unsigned errors of 0.024 g/cm3, 0.79 kcal/mol and 1.17 kcal/mol for the liquid density, heat of vaporization and free energy of hydration respectively. This indicates that the derived parameters are suitable for molecular modelling applications, including computer-aided drug design.</p></div></div></div>


Author(s):  
Joshua Horton ◽  
Alice Allen ◽  
Leela Dodda ◽  
Daniel Cole

<div><div><div><p>Modern molecular mechanics force fields are widely used for modelling the dynamics and interactions of small organic molecules using libraries of transferable force field parameters. For molecules outside the training set, parameters may be missing or inaccurate, and in these cases, it may be preferable to derive molecule-specific parameters. Here we present an intuitive parameter derivation toolkit, QUBEKit (QUantum mechanical BEspoke Kit), which enables the automated generation of system-specific small molecule force field parameters directly from quantum mechanics. QUBEKit is written in python and combines the latest QM parameter derivation methodologies with a novel method for deriving the positions and charges of off-center virtual sites. As a proof of concept, we have re-derived a complete set of parameters for 109 small organic molecules, and assessed the accuracy by comparing computed liquid properties with experiment. QUBEKit gives highly competitive results when compared to standard transferable force fields, with mean unsigned errors of 0.024 g/cm3, 0.79 kcal/mol and 1.17 kcal/mol for the liquid density, heat of vaporization and free energy of hydration respectively. This indicates that the derived parameters are suitable for molecular modelling applications, including computer-aided drug design.</p></div></div></div>


ACS Omega ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 4995-5000 ◽  
Author(s):  
Jiaxiang Zhang ◽  
Junwen Yang ◽  
Ziyue Liu ◽  
Bin Zheng

Author(s):  
Mohamed R. Rizk ◽  
Muhammad G. Gamal ◽  
Amina Mazhar ◽  
Mohamed El-Deab ◽  
Bahgat El-Anadouli

In this work, we report a single-step preparation of porous Ni-based foams thin layer atop Cu substrate via a facile dynamic hydrogen bubble template technique (DHBT). The prepared porous Ni-based...


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