General Cluster Sorption Isotherm

2020 ◽  
Author(s):  
Christoph Buttersack
Keyword(s):  
Density Functional ◽  
Capillary Condensation ◽  
Cluster Formation ◽  
Full Range ◽  
Full Description ◽  
Cross Sectional ◽  
Macroporous Silica ◽  
Isotherm Equation ◽  
Type Iv ◽  
Classical Thermodynamics

<p>Adsorption isotherms are an essential tool in chemical physics of surfaces. However, several approaches based on a different theoretical basis exist and for isotherms including capillary condensation existing approaches can fail. Here, a general isotherm equation is derived and applied to literature data both concerning type IV isotherms of argon and nitrogen in ordered mesoporous silica, and type II isotherms of disordered macroporous silica. The new isotherm covers the full range of partial pressure (10<sup>-6</sup> - 0.7). It relies firstly on the classical thermodynamics of cluster formation, secondly on a relationship defining the free energy during the increase of the cluster size. That equation replaces the Lennard-Jones potentials used in the classical density functional theory. The determination of surface areas is not possible by this isotherm because the cross-sectional area of a cluster is unknown. Based on the full description of type IV isotherms, most known isotherms are accessible by respective simplifications. </p>

scholarly journals General Cluster Sorption Isotherm

2020 ◽  
Author(s):  
Christoph Buttersack
Keyword(s):  
Density Functional ◽  
Capillary Condensation ◽  
Cluster Formation ◽  
Full Range ◽  
Full Description ◽  
Cross Sectional ◽  
Macroporous Silica ◽  
Isotherm Equation ◽  
Type Iv ◽  
Classical Thermodynamics

<p>Adsorption isotherms are an essential tool in chemical physics of surfaces. However, several approaches based on a different theoretical basis exist and for isotherms including capillary condensation existing approaches can fail. Here, a general isotherm equation is derived and applied to literature data both concerning type IV isotherms of argon and nitrogen in ordered mesoporous silica, and type II isotherms of disordered macroporous silica. The new isotherm covers the full range of partial pressure (10<sup>-6</sup> - 0.7). It relies firstly on the classical thermodynamics of cluster formation, secondly on a relationship defining the free energy during the increase of the cluster size. That equation replaces the Lennard-Jones potentials used in the classical density functional theory. The determination of surface areas is not possible by this isotherm because the cross-sectional area of a cluster is unknown. Based on the full description of type IV isotherms, most known isotherms are accessible by respective simplifications. </p>

uMBD: A Materials-Ready Dispersion Correction that Uniformly Treats Metallic, Ionic, Covalent, and van der Waals Bonding

2019 ◽  
Author(s):  
Minho Kim ◽  
won june kim ◽  
Tim Gould ◽  
Eok Kyun Lee ◽  
Sébastien Lebègue ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Electrode Materials ◽  
Full Range ◽  
Van Der Waals ◽  
Dft Method ◽  
Dispersion Correction ◽  
Computational Overhead ◽  
System A ◽  
Battery Design

<p>Materials design increasingly relies on first-principles calculations for screening important candidates and for understanding quantum mechanisms. Density functional theory (DFT) is by far the most popular first-principles approach due to its efficiency and accuracy. However, to accurately predict structures and thermodynamics, DFT must be paired with a van der Waals (vdW) dispersion correction. Therefore, such corrections have been the subject of intense scrutiny in recent years. Despite significant successes in organic molecules, no existing model can adequately cover the full range of common materials, from metals to ionic solids, hampering the applications of DFT for modern problems such as battery design. Here, we introduce a universally optimized vdW-corrected DFT method that demonstrates an unbiased reliability for predicting molecular, layered, ionic, metallic, and hybrid materials without incurring a large computational overhead. We use our method to accurately predict the intercalation potentials of layered electrode materials of a Li-ion battery system – a problem for which the existing state-of-the-art methods fail. Thus, we envisage broad use of our method in the design of chemo-physical processes of new materials.</p>

scholarly journals The Effect of Topology on Phase Behavior under Confinement

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1220
Author(s):  
Arnout M. P. Boelens ◽  
Hamdi A. Tchelepi
Keyword(s):  
Phase Behavior ◽  
Density Functional ◽  
Capillary Condensation ◽  
Good Description ◽  
Functional Theory ◽  
Minkowski Functionals ◽  
First Order ◽  
Lennard Jones ◽  
And Topology ◽  
First Order Transition

This work studies how morphology (i.e., the shape of a structure) and topology (i.e., how different structures are connected) influence wall adsorption and capillary condensation under tight confinement. Numerical simulations based on classical density functional theory (cDFT) are run for a wide variety of geometries using both hard-sphere and Lennard-Jones fluids. These cDFT computations are compared to results obtained using the Minkowski functionals. It is found that the Minkowski functionals can provide a good description of the behavior of Lennard-Jones fluids down to small system sizes. In addition, through decomposition of the free energy, the Minkowski functionals provide a good framework to better understand what are the dominant contributions to the phase behavior of a system. Lastly, while studying the phase envelope shift as a function of the Minkowski functionals it is found that topology has a different effect depending on whether the phase transition under consideration is a continuous or a discrete (first-order) transition.

Two-stage capillary condensation in pores with structured walls: A nonlocal density functional study

1998 ◽  
Vol 108 (20) ◽  
pp. 8689-8697 ◽  
Author(s):  
Petra Röcken ◽  
Andres Somoza ◽  
Pedro Tarazona ◽  
Gerhard Findenegg
Keyword(s):  
Density Functional ◽  
Capillary Condensation ◽  
Functional Study ◽  
Two Stage ◽  
Density Functional Study

scholarly journals Determinants of safe delivery utilization among Indonesian women in eastern part of Indonesia

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 332
Author(s):  
Ferry Efendi ◽  
Susy Katikana Sebayang ◽  
Erni Astutik ◽  
Setho Hadisuyatmana ◽  
Eka Mishbahatul Mar'ah Has ◽  
...  
Keyword(s):  
Maternal Mortality ◽  
Economic Status ◽  
Full Range ◽  
Unwanted Pregnancy ◽  
Secondary Data ◽  
Binary Logistic Regression ◽  
Wealth Quintile ◽  
Cross Sectional ◽  
Safe Delivery ◽  
Chi Squared

Background: Improving maternal health and reducing maternal mortality are part of the United Nations global Sustainable Development Goals for 2030. Ensuring every woman’s right to safe delivery is critical for reducing the maternal mortality rate. Our study aimed to identify determinants of safe delivery utilization among women in the eastern Indonesia. Methods: This study was cross-sectional and used a secondary data from the 2017 Indonesian Demographic and Health Survey (IDHS). A total of 2,162 women who had their last child in the five years preceding the survey and lived in the eastern part of Indonesia were selected as the respondents. Chi-squared test and binary logistic regression were used to understand the determinants of safe delivery. Results: Higher child rank and interval ≤2 years (OR: 0.30, 95% CI: 0.19-0.47), unwanted pregnancy at time of becoming pregnant (OR: 1.48, 95% CI: 1.05-2.08), richest wealth quintile (OR: 5.59, 95% CI: 3.37-9.30), more than four antenatal care visits (OR: 3.62, 95% CI: 2.73-4.79), rural residence, good composite labor force participation, and a good attitude towards domestic violence were found to be significantly associated with delivery at health facility. Higher child rank and interval ≤2 years (OR: 0.49, 95% CI: 0.29-0.83), husband/partner having completed secondary or higher education (OR: 2.18, 95% CI: 1.48-3.22), being in the richest wealth quintile, and four other factors were found to be significantly associated with the assistance of skilled birth attendants. Conclusions: This research extends our knowledge on the determinants of safe delivery among women in the eastern part of Indonesia. This study revealed that the economic status of household remains an important issue in improving safe delivery among women in eastern part of Indonesia. An open innovation and partnership process to improve safe delivery program that engages the full range of stakeholders should be developed based on economic situation.

scholarly journals Removal of 17β-Estradiol by Activated Charcoal Supported Titanate Nanotubes (TNTs@AC) through Initial Adsorption and Subsequent Photo-Degradation: Intermediates, DFT calculation, and Mechanisms

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2121
Author(s):  
Taobo Huang ◽  
Baozhu Pan ◽  
Haodong Ji ◽  
Wen Liu
Keyword(s):  
Activated Charcoal ◽  
Density Functional ◽  
Capillary Condensation ◽  
Uv Light ◽  
Density Functional Theory Calculation ◽  
Titanate Nanotubes ◽  
Photo Degradation ◽  
Photocatalytic Ability ◽  
17Β Estradiol ◽  
Initial Adsorption

A low-cost composite of activated charcoal supported titanate nanotubes (TNTs@AC) was developed via the facile hydrothermal method to remove the 17β-estradiol (E2, a model of pharmaceutical and personal care products) in water matrix by initial adsorption and subsequent photo-degradation. Characterizations indicated that the modification occurred, i.e., the titanate nanotubes would be grafted onto the activated charcoal (AC) surface, and the micro-carbon could modify the tubular structure of TNTs. E2 was rapidly adsorbed onto TNTs@AC, and the uptake reached 1.87 mg/g from the dual-mode model fitting. Subsequently, the adsorbed E2 could be degraded 99.8% within 2 h under ultraviolet (UV) light irradiation. TNTs@AC was attributed with a unique hybrid structure, providing the hydrophobic effect, π−π interaction, and capillary condensation for E2 adsorption, and facilitating the electron transfer and then enhancing photocatalytic ability for E2-degradation. In addition, the removal mechanism of E2 was elucidated through the density functional theory calculation. Our study is expected to provide a promising material for environmental application.

Nano-sized nickel catalyst for deep hydrogenation of lignin monomers and first-principles insight into the catalyst preparation

2017 ◽  
Vol 5 (8) ◽  
pp. 3948-3965 ◽  
Author(s):  
Shi-Chao Qi ◽  
Lu Zhang ◽  
Hisahiro Einaga ◽  
Shinji Kudo ◽  
Koyo Norinaga ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Full Range ◽  
Catalyst Preparation ◽  
Ni Catalyst ◽  
Borohydride Reduction ◽  
Functional Theory ◽  
Pyridine Complex ◽  
Insight Into

A type of nano-sized Ni catalyst supported by ZSM-5 zeolite for the deep hydrogenation of lignin monomers is prepared by borohydride reduction of a Ni2+–pyridine complex in ethanol. The mechanism of the borohydride reduction over the full range from Ni2+ to Ni0 is calculated by applying density functional theory.

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