scholarly journals DFT studies of the σ-donor/π-acceptor properties of [SnCB10H11]– and its relationship to [SnCl3]–, CO, PF3, [SnB11H11]2–, SnC2B9H11, and related SnC2BnHn+2 compounds

2009 ◽  
Vol 87 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Mark A Fox ◽  
Todd B Marder ◽  
Lars Wesemann
Keyword(s):  
Dft Calculations ◽  
Lewis Acid ◽  
Negative Charge ◽  
Experimental Results ◽  
Dft Studies ◽  
Donor And Acceptor ◽  
Wide Range ◽  
Homo And Lumo ◽  
Borane Cluster

The 1,2-carbastanna-closo-dodecaborate, [SnCB10H11]–, was found via DFT calculations to have intermediate σ-donor/π-acceptor properties between those of [SnB11H11]2– and 3,1,2-SnC2B9H11, and quite similar HOMO and LUMO energies and shapes to those of [SnCl3]–, which is a stronger σ-donor and weaker π-acceptor than CO or PF3. The non-carbon containing cluster [SnB11H11]2– is shown to be a very strong donor, whereas the dicarbon cluster 3,1,2-SnC2B9H11 is a poor σ-donor but good Lewis acid, consistent with experimental results. Thus, these systems can be tuned across a very wide range via isolobal replacement of [BH]– for CH vertices. The higher negative charge in the non-carbon-containing systems, as well as the fact that boron is more electropositive than carbon, contribute to the increased energies of both HOMO and LUMO in the stannaboranes compared to the stannacarboranes, explaining their relative donor and acceptor properties.Key words: DFT calculations, tin, borane cluster.

Experimental Results and Modeling of the Codiffusion of Donors and Acceptors in Si

1995 ◽  
Vol 389 ◽  
Author(s):  
S. Solmi ◽  
S. Valmorri
Keyword(s):  
Ion Pairing ◽  
Experimental Results ◽  
Standard Process ◽  
Model Based ◽  
Proposed Model ◽  
Donor And Acceptor ◽  
Wide Range ◽  
High Concentrations ◽  
Process Simulator ◽  
Good Agreement

ABSTRACTA model based on ion pairing for the simulation of donor and acceptor codiffusion in silicon is presented. The proposed model allows us to obtain a good agreement with the experimental profiles over a wide range of diffusion conditions, specially at high concentrations where the standard process simulator codes give results strongly inaccurate. Comparison of the simulations with new and literature codiffusion profiles is provided.

On the nominal transverse shear strain to characterize the severity of creasing

TAPPI Journal ◽  
2018 ◽  
Vol 17 (04) ◽  
pp. 231-240
Author(s):  
Douglas Coffin ◽  
Joel Panek
Keyword(s):  
Shear Strain ◽  
Transverse Shear ◽  
Elastic Limit ◽  
Experimental Results ◽  
Transverse Shear Strain ◽  
Maximum Strain ◽  
Machine Direction ◽  
Engineering Approach ◽  
Wide Range ◽  
Analytic Expression

A transverse shear strain was utilized to characterize the severity of creasing for a wide range of tooling configurations. An analytic expression of transverse shear strain, which accounts for tooling geometry, correlated well with relative crease strength and springback as determined from 90° fold tests. The experimental results show a minimum strain (elastic limit) that needs to be exceeded for the relative crease strength to be reduced. The theory predicts a maximum achievable transverse shear strain, which is further limited if the tooling clearance is negative. The elastic limit and maximum strain thus describe the range of interest for effective creasing. In this range, cross direction (CD)-creased samples were more sensitive to creasing than machine direction (MD)-creased samples, but the differences were reduced as the shear strain approached the maximum. The presented development provides the foundation for a quantitative engineering approach to creasing and folding operations.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

2020 ◽  
Vol 24 ◽  
Author(s):  
Ghodsi Mohammadi Ziarani ◽  
Shima Roshankar ◽  
Fatemeh Mohajer ◽  
Alireza Badiei
Keyword(s):  
Mesoporous Silica ◽  
Heterogeneous Catalyst ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Heterogeneous Catalysts ◽  
Organic Transformations ◽  
Functionalized Mesoporous Silica ◽  
Silica Nanomaterials ◽  
Wide Range ◽  
Target Molecules

Abstract:: Mesoporous silica nanomaterials provide an extraordinary advantage for making new and superior heterogeneous catalysts because of their surface silanol groups. The functionalized mesoporous SBA-15, such as acidic, basic, BrÖnsted, lewis acid, and chiral catalysts, are used for a wide range of organic synthesis. The importance of the chiral ligands, which were immobilized on the SBA-15, was mentioned in this review to achieve chiral products as valuable target molecules. Herein, their synthesis and application in different organic transformations are reviewed from 2016 till date 2020.

Accurate prediction of 195Pt NMR chemical shifts for a series of Pt(ii) and Pt(iv) antitumor agents by a non-relativistic DFT computational protocol

2014 ◽  
Vol 43 (14) ◽  
pp. 5409-5426 ◽  
Author(s):  
Athanassios C. Tsipis ◽  
Ioannis N. Karapetsas
Keyword(s):  
Dft Calculations ◽  
Anticancer Agents ◽  
Antitumor Agents ◽  
Chemical Shifts ◽  
Accurate Prediction ◽  
Nmr Chemical Shifts ◽  
Relativistic Dft ◽  
Square Planar ◽  
Wide Range ◽  
Computational Protocol

Exhaustive benchmark DFT calculations reveal that the non-relativistic GIAO-PBE0/SARC-ZORA(Pt)∪6-31+G(d)(E) computational protocol predicts accurate 195Pt NMR chemical shifts for a wide range of square planar Pt(ii) and octahedral Pt(iv) anticancer agents.

scholarly journals Numerical Phase-Field Model Validation for Dissolution of Minerals

2021 ◽  
Vol 11 (6) ◽  
pp. 2464
Author(s):  
Sha Yang ◽  
Neven Ukrainczyk ◽  
Antonio Caggiano ◽  
Eddie Koenders
Keyword(s):  
Phase Field ◽  
Liquid Interface ◽  
Mineral Dissolution ◽  
Experimental Results ◽  
Wide Range ◽  
Congruent Dissolution ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Dissolution Of Minerals ◽  
Meso Scale

Modelling of a mineral dissolution front propagation is of interest in a wide range of scientific and engineering fields. The dissolution of minerals often involves complex physico-chemical processes at the solid–liquid interface (at nano-scale), which at the micro-to-meso-scale can be simplified to the problem of continuously moving boundaries. In this work, we studied the diffusion-controlled congruent dissolution of minerals from a meso-scale phase transition perspective. The dynamic evolution of the solid–liquid interface, during the dissolution process, is numerically simulated by employing the Finite Element Method (FEM) and using the phase–field (PF) approach, the latter implemented in the open-source Multiphysics Object Oriented Simulation Environment (MOOSE). The parameterization of the PF numerical approach is discussed in detail and validated against the experimental results for a congruent dissolution case of NaCl (taken from literature) as well as on analytical models for simple geometries. In addition, the effect of the shape of a dissolving mineral particle was analysed, thus demonstrating that the PF approach is suitable for simulating the mesoscopic morphological evolution of arbitrary geometries. Finally, the comparison of the PF method with experimental results demonstrated the importance of the dissolution rate mechanisms, which can be controlled by the interface reaction rate or by the diffusive transport mechanism.

scholarly journals MOCVD Grown HgCdTe Heterostructures for Medium Wave Infrared Detectors

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 611
Author(s):  
Waldemar Gawron ◽  
Jan Sobieski ◽  
Tetiana Manyk ◽  
Małgorzata Kopytko ◽  
Paweł Madejczyk ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Infrared Detectors ◽  
Lattice Mismatch ◽  
Layer Growth ◽  
Ex Situ ◽  
Current Status ◽  
Organic Chemical ◽  
Infrared Band ◽  
Donor And Acceptor ◽  
Wide Range

This paper presents the current status of medium-wave infrared (MWIR) detectors at the Military University of Technology’s Institute of Applied Physics and VIGO System S.A. The metal–organic chemical vapor deposition (MOCVD) technique is a very convenient tool for the deposition of HgCdTe epilayers, with a wide range of compositions, used for uncooled infrared detectors. Good compositional and thickness uniformity was achieved on epilayers grown on 2-in-diameter, low-cost (100) GaAs wafers. Most growth was performed on substrates, which were misoriented from (100) by between 2° and 4° in order to minimize growth defects. The large lattice mismatch between GaAs and HgCdTe required the usage of a CdTe buffer layer. The CdTe (111) B buffer layer growth was enforced by suitable nucleation procedure, based on (100) GaAs substrate annealing in a Te-rich atmosphere prior to the buffer deposition. Secondary-ion mass spectrometry (SIMS) showed that ethyl iodide (EI) and tris(dimethylamino)arsenic (TDMAAs) were stable donor and acceptor dopants, respectively. Fully doped (111) HgCdTe heterostructures were grown in order to investigate the devices’ performance in the 3–5 µm infrared band. The uniqueness of the presented technology manifests in a lack of the necessity of time-consuming and troublesome ex situ annealing.

scholarly journals Lewis acid / Base-free Strategy for the Synthesis of 2-Arylthio and Selenyl Benzothiazole / Thiazole and Imidazole

2021 ◽  
Vol 27 (1) ◽  
pp. 17-23
Author(s):  
Guniganti Balakishan ◽  
Gullapalli Kumaraswamy ◽  
Vykunthapu Narayanarao ◽  
Pagilla Shankaraiah
Keyword(s):  
Lewis Acid ◽  
Bond Formation ◽  
Acid Base ◽  
Mechanistic Pathway ◽  
Wide Range ◽  
Acid And Base ◽  
Lewis Acid And Base ◽  
Sulfur Bond

Abstract A Cu(II)-catalyzed Csp2-Se and Csp2-Sulfur bond formation was achieved with moderate to good yields without the aid of Lewis acid and base. The reaction is compatible with a wide range of heterocycles such as benzothiazole, thiazole, and imidazole. Also, this typical protocol is found to be active in thio-selenation via S-H activation. Additionally, we proposed a plausible mechanistic pathway involving Cu(III) putative intermediate.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

scholarly journals Mechanistic insights for the photoredox organocatalytic fluorination of aliphatic carbons by anthraquinone using time-resolved and DFT studies

2017 ◽  
Vol 7 (4) ◽  
pp. 848-857 ◽  
Author(s):  
J. W. Kee ◽  
H. Shao ◽  
C. W. Kee ◽  
Y. Lu ◽  
H. S. Soo ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Dft Studies ◽  
Time Resolved

Nanosecond TAS and DFT calculations reveal mechanistic insights for photoredox fluorination of aliphatic C–H bonds and evidence of an anthraquinone–Selectfluor® exciplex.

scholarly journals Adsorption of amino acids on MFI-type zeolite: DFT calculations and experimental results

2012 ◽  
Vol 4 (S1) ◽  
Author(s):  
Kai Stueckenschneider ◽  
Achim Zielesny ◽  
Gerhard Schembecker
Keyword(s):  
Amino Acids ◽  
Dft Calculations ◽  
Experimental Results ◽  
Type Zeolite
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