Structure, Stability, and Generation of CH3CNS

2010 ◽  
Vol 63 (12) ◽  
pp. 1686 ◽  
Author(s):  
Melinda Krebsz ◽  
Balázs Hajgató ◽  
Gábor Bazsó ◽  
György Tarczay ◽  
Tibor Pasinszki
Keyword(s):  
Uv Irradiation ◽  
Broad Band ◽  
Solid Matrix ◽  
Structure Stability ◽  
Ground State Structure ◽  
Bimolecular Reactions ◽  
Dilute Gas ◽  
Quantum Chemical Methods ◽  
The Matrix ◽  
Solid Argon

The unstable acetonitrile N-sulfide molecule CH3CNS has been photolytically generated in inert solid argon matrix from 3,4-dimethyl-1,2,5-thiadiazole by 254-nm UV irradiation, and studied by ultraviolet spectroscopy and mid-infrared spectroscopy. The molecule is stable in the matrix to 254-nm UV irradiation, but decomposes to CH3CN and a sulfur atom when broad-band UV irradiation is used. Chemiluminescence due to S2 formation from triplet sulfur atoms was detected on warming the matrix to ∼20–25 K. The ground-state structure and potential uni- and bimolecular reactions of CH3CNS are investigated using B3LYP, CCSD(T), and MR-AQCC quantum-chemical methods. CH3CNS is demonstrated to be stable under isolated conditions at room temperature, i.e. in the dilute gas phase or in an inert solid matrix, but unstable owing to bimolecular reactions, i.e. in the condensed phase.

Structure, Stability, and Cycloaddition Reactions of Nitrile Selenides

2014 ◽  
Vol 67 (3) ◽  
pp. 444 ◽  
Author(s):  
Tibor Pasinszki ◽  
Melinda Krebsz ◽  
Balázs Hajgató
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Room Temperature ◽  
Equilibrium Structure ◽  
Solid Matrix ◽  
Structure Stability ◽  
Chemical Methods ◽  
Bimolecular Reactions ◽  
Dilute Gas ◽  
Quantum Chemical Methods

The equilibrium structure, unimolecular reactions, and bimolecular reactions of nitrile selenides (XCNSe, where X = H, F, Cl, Br, CN, CH3) have been investigated using CCSD(T), CCSD(T)//B3LYP, and MR-AQCC//UB3LYP quantum-chemical methods. Nitrile selenides are demonstrated to be stable under isolated conditions at ambient temperature, i.e. in the dilute gas phase or in an inert solid matrix, but unstable in the condensed phase or solutions owing to bimolecular reactions. FCNSe and CH3CNSe cycloaddition with ethynes, ethenes, and nitriles was studied using the MR-AQCC//UB3LYP method. Cycloaddition was predicted to be facile at room temperature with small dipolarophiles.

Über die Entstehung von Zuckern und zuckerähnlichen Substanzen aus in Zeolithen absorbiertem Formaldehyd durch UV-Bestrahlung / Synthesis of Sugars and Sugar-Like Products by UV Irradiation of Formaldehyde Absorbed on Zeolites

1981 ◽  
Vol 36 (11) ◽  
pp. 1451-1456 ◽  
Author(s):  
Fritz Seel ◽  
Willi Schaum ◽  
Georg Simon
Keyword(s):  
Uv Irradiation ◽  
Type A ◽  
Product Distribution ◽  
The Matrix

Abstract The formation of sugars and sugar-like substances by UV irradiation of formaldehyde adsorbed on zeolites of type A and X has been demonstrated. The conversion inside or outside the matrix and product distribution depend on the type of zeolite.

Implementation of Finite Deformation Triphasic Modeling in the Finite Element Code FEBio

2012 ◽  
Author(s):  
Gerard A. Ateshian ◽  
Steve Maas ◽  
Jeffrey A. Weiss
Keyword(s):  
Soft Tissues ◽  
Mixture Theory ◽  
Solid Matrix ◽  
Osmotic Swelling ◽  
Solute Content ◽  
Counter Ions ◽  
The Matrix ◽  
Triphasic Theory ◽  
Ion Species ◽  
And Diffusion

Many biological soft tissues exhibit a charged solid matrix, most often due to the presence of proteoglycans enmeshed within the matrix. The predominant solute content of the interstitial fluid of these tissues consists of the monovalent counter-ions Na+ and Cl−. The electrical interactions between the mobile ion species and fixed charge density of the solid matrix produces an array of mechano-electrochemical effects, including Donnan osmotic swelling, and streaming and diffusion potentials and currents. These phenomena have been successfully modeled by the triphasic theory of Lai et al. [1], which is based on the framework of mixture theory [2]. Other similar frameworks have also been proposed [3, 4]. The equations of triphasic theory are nonlinear, even in the range of infinitesimal strains. Therefore, numerical schemes are generally needed to solve all but the simplest problems using this framework.

scholarly journals Effect of Aluminum, Iron and Chromium Alloying on the Structure and Mechanical Properties of (Ti-Ni)-(Cu-Zr) Crystalline/Amorphous Composite Materials

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 874
Author(s):  
Andrey A. Tsarkov ◽  
Vladislav Yu. Zadorozhnyy ◽  
Alexey N. Solonin ◽  
Dmitri V. Louzguine-Luzgin
Keyword(s):  
Mechanical Properties ◽  
Testing Machine ◽  
High Strength ◽  
Alloying Elements ◽  
Solid Matrix ◽  
Complete Suppression ◽  
Structural Investigations ◽  
X Ray ◽  
Composites Materials ◽  
The Matrix

High-strength crystalline/amorphous composites materials based on (Ti-Ni)-(Cu-Zr) system were developed. The optimal concentrations of additional alloying elements Al, Fe, and Cr were obtained. Structural investigations were carried out using X-ray diffraction equipment (XRD) and scanning electron microscope (SEM) with an energy-dispersive X-ray module (EDX). It was found that additives of aluminum and chromium up to 5 at% dissolve well into the solid matrix solution of the NiTi phase. At a concentration of 5 at%, the precipitation of the unfavorable NiTi2 phase occurs, which, as a result, leads to a dramatic decrease in ductility. Iron dissolves very well in the solid solution of the matrix phase due to chemical affinity with nickel. The addition of iron does not cause the precipitation of the NiTi2 phase in the concentration range of 0–8 at%, but with an increase in concentration, this leads to a decrease in the mechanical properties of the alloy. The mechanical behavior of alloys was studied in compression test conditions on a universal testing machine. The developed alloys have a good combination of strength and ductility due to their dual-phase structure. It was shown that additional alloying elements lead to a complete suppression of the martensitic transformation in the alloys.

Enhancing the Photocatalytic Activity of La/Y Co-Doped ZnWO4 under UV Irradiation

2020 ◽  
Vol 842 ◽  
pp. 214-222
Author(s):  
Chu Wen Rao ◽  
Wei Zhang ◽  
Zheng Fa Hu ◽  
Zu Yong Feng ◽  
Ying Jun Chen ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Broad Band ◽  
Solid State Reaction Method ◽  
High Photocatalytic Activity ◽  
Photocatalytic Decomposition ◽  
X Ray ◽  
Co Doping ◽  
Broad Band Emission

In this paper, ZnWO4: La3+, Y3+ photocatalysts were synthesized by a high-temperature solid state reaction method. The effects of La3+ and Y3+ doping contents on the phase, morphologies and optical properties of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Diffuse reflectance spectra (DRS), photoluminescence spectra (PL), Raman and UV-visible spectroscopy, respectively. The as-prepared ZnWO4:La3+, Y3+ photocatalysts showed photoluminescence with a broad band emission, and high photocatalytic activity in degradation of rhodamine B (RhB) under simulated UV irradiation. The results showed that co-doping in ZnWO4 can enhance light harvesting capability to generate more electron-hole pairs, and acted as a trap center by decreasing the recombination of photogenerated electrons and holes. All the results obtained by the work suggest that ZnWO4: La3+, Y3+ photocatalysts are promising materials for the photocatalytic decomposition of pollutants.

Relationship Between Meniscal Sample Swelling and the Compressive Properties of Bovine Menisci

2013 ◽  
Author(s):  
Stephen H. J. Andrews ◽  
Nigel G. Shrive ◽  
Janet L. Ronsky
Keyword(s):  
Vertical Direction ◽  
Axial Direction ◽  
Solid Matrix ◽  
Compressive Properties ◽  
Connective Tissues ◽  
Drag Forces ◽  
The Matrix ◽  
Two Phases ◽  
And Storage ◽  
Phosphate Buffered Saline

The menisci are anisotropic hydrated connective tissues, situated in the tibiofemoral joint. The menisci transmit approximately 50% of the load across this joint [1, 2]. In this tissue, compression would only be experienced in the axial (vertical) direction, and as such, many studies have tested samples in the axial direction to determine the compressive properties [3–5]. The material behaviour of the menisci has been described as biphasic, meaning the response of the tissue to applied load is time dependent and determined by both the solid constituents and their interaction with the fluid component [3]. Due to the low permeability of the tissue, deformation results in relative movement of the solid matrix and the fluid it contains, resulting in the creation of drag forces between the two phases. Fluid exudation from the matrix governs the viscoelastic behaviour of the tissue, including stress relaxation and creep [6]. The swelling behaviour of meniscal samples in varying osmotic environments was evaluated in our lab (unpublished data), where they swelled significantly, approximately 30% volumetrically in iso-osmotic phosphate buffered saline (PBS). It was hypothesized that the material properties of the tissue would be affected by this significant swelling. To date, no study has evaluated the effect of sample swelling, due to sample preparation and storage, on the behaviour of the menisci in compression. Therefore, the purpose of this study was to evaluate this relationship. We hypothesized that meniscal samples would be less stiff and more permeable in a swollen state than when they are compressed to the ‘fresh’, non-swollen, thickness prior to initiation of the protocol.

scholarly journals Feeding and Cooling and Time of Thermal Treatment of a Massive Bush Made of the Complex Aluminum Bronze Cast by the Lost Foam

2014 ◽  
Vol 14 (4) ◽  
pp. 39-44
Author(s):  
P. Just ◽  
B.P. Pisarek
Keyword(s):  
Thermal Treatment ◽  
Adhesive Wear ◽  
Structure Stability ◽  
Aluminum Bronze ◽  
Aluminium Bronze ◽  
The Matrix ◽  
Iron Nickel ◽  
Lost Foam ◽  
Selection Of ◽  
Eps Pattern

Abstract Small additions of Cr, Mo and W to aluminium-iron-nickel bronze are mostly located in phases κi (i=II; III; IV),and next in phase α (in the matrix) and phase γ2. They raise the temperature of the phase transformations in aluminium bronzes as well as the casts’ abrasive and adhesive wear resistance. The paper presents a selection of feeding elements and thermal treatment times which guarantees structure stability, for a cast of a massive bush working at an elevated temperature (650-750°C) made by means of the lost foam technology out of composite aluminium bronze. So far, there have been no analyses of the phenomena characteristic to the examined bronze which accompany the process of its solidification during gasification of the EPS pattern. There are also no guidelines for designing risers and steel internal chill for casts made of this bronze. The work identifies the type and location of the existing defects in the mould’s cast. It also proposes a solution to the manner of its feeding and cooling which compensates the significant volume contraction of bronze and effectively removes the formed gases from the area of mould solidification. Another important aspect of the performed research was establishing the duration time of bronze annealing at the temperature of 750°C which guarantees stabilization of the changes in the bronze microstructure - stabilization of the changes in the bronze HB hardness.

scholarly journals Morphological: Optical, and Mechanical Characterizations of Non-Activated and Activated Nanocomposites of SG and MWCNTs

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1280
Author(s):  
Mohammed S. Alotaibi ◽  
Norah H. Almousa ◽  
Mohammed A. Asaker ◽  
Fahad S. Alkasmoul ◽  
Nezar H. Khdary ◽  
...  
Keyword(s):  
Silica Gel ◽  
Broad Band ◽  
Base Material ◽  
Weight Percent ◽  
Surface Phenomenon ◽  
Composite Matrix ◽  
Multiwalled Carbon ◽  
Low Concentrations ◽  
Before And After ◽  
The Matrix

Nanocomposites of silica gel (SG) and multiwalled carbon nanotubes (MWCNTs) of relatively low concentrations (0.25, 0.50, and 0.75 wt%) were characterized before and after annealing. Adsorption is a surface phenomenon, and based on this, the morphology of the composites was investigated by scanning electron microscopy (SEM). The produced images show that the MWCNTs were embedded into the silica gel base material. Fourier transform infrared (FTIR) transmittance spectroscopy showed that MWCNTs were not functionalized within the matrix of silica gel and MWCNT composites. However, after annealing the composites at 400 °C for 4 h in air, evidence of activation was observed in the FTIR spectrum. The effects of the embedding of MWCNTs on porosity, specific surface area, and pore size distribution were studied using Raman spectroscopy. The Raman spectra of the prepared composites were mainly dominated by characteristic sharp scattering peaks of the silica gel at 480, 780, and 990 cm−1 and a broad band centered at 2100 cm−1. The scattering peaks of MWCNTs were not well pronounced, as the homogeneity of the composite is always questionable. Nanosizer analysis showed that at 0.25 wt%, the distribution of MWCNTs within the silica gel was optimal. Vickers hardness measurements showed that the hardness increased with the increasing weight percent of MWCNTs within the composite matrix, while annealing enhanced the mechanical properties of the composites. Further studies are required to investigate the pore structure of silica gel within the matrix of MWCNTs to be deployed for efficient cooling and water purification applications.

Theoretical Study of Structural, Elastic Properties and Phase Transitions of Cu2ZnSnS4

2014 ◽  
Vol 1058 ◽  
pp. 113-117 ◽  
Author(s):  
Yi Feng Zhao ◽  
Zu Ming Liu ◽  
De Cong Li
Keyword(s):  
Phase Transitions ◽  
Elastic Properties ◽  
Density Functional ◽  
Theoretical Work ◽  
Structure Stability ◽  
Ground State Structure ◽  
Preparation Technology ◽  
Functional Theory ◽  
Unstable Phase ◽  
Total Energies

The total energy, the electronic properties, phase transitions, and elastic properties of Cu2ZnSnS4(CZTS) in the three structures are investigated by first-principles calculations based on density functional theory. Results show that the total energies of stannite (ST) and primitive-mixed CuAu (PMCA) structures are higher than that of kesterite-type (KS), and the KS is the ground state structure. Relationships between enthalpy and pressure of the KS, ST and PMCA structure of CZTS are also investigated at 0 K, since the pressure can have profound impacts on the electronic structure, possible phase transitions and structure stability. And results also show that KS structure is always the most stable; ST is the second; and the PMCA structure is the most unstable; phase transitions of three structures could not occur in high pressure. The high ratios of shear modulus to bulk modulus (G/B) indicate that CZTS compounds in three types have ductile behaviors. The Poisson ratios for the three structures are from 0.27 to 0.31, which again proves that all structures of CZTS have better plasticity. The results can increase more hints about further research directions, and these effects can play an important role in future experimental preparation technology and theoretical work of CZTS materials.

Shallow, gravity-driven flow in a poro-elastic layer

2015 ◽  
Vol 778 ◽  
pp. 335-360 ◽  
Author(s):  
Duncan R. Hewitt ◽  
Jerome A. Neufeld ◽  
Neil J. Balmforth
Keyword(s):  
Coupled Model ◽  
Solid Matrix ◽  
Rigid Base ◽  
Surface Uplift ◽  
Hydrogel Particles ◽  
Dense Fluid ◽  
The Matrix ◽  
Gravity Driven ◽  
Flow Through ◽  
Gravity Driven Flow

By combining Biot’s theory of poro-elasticity with standard shallow-layer scalings, a theoretical model is developed to describe axisymmetric gravity-driven flow through a shallow deformable porous medium. Motivated in part by observations of surface uplift around $\text{CO}_{2}$ sequestration sites, the model is used to explore the injection of a dense fluid into a horizontal, deformable porous layer that is initially saturated with another, less dense, fluid. The layer lies between a rigid base and a flexible overburden, both of which are impermeable. As the injected fluid spreads under gravity, the matrix deforms and the overburden lifts up. The coupled model predicts the location of the injected fluid as it spreads and the resulting uplift of the overburden due to deformation of the solid matrix. In general, the uplift spreads diffusively far ahead of the injected fluid. If fluid is injected with a constant flux and the medium is unbounded, both the uplift and the injected fluid spread in a self-similar fashion with the same similarity variable $\propto r/t^{1/2}$. The asymptotic form of this spreading is established. Results from a series of laboratory experiments, using polyacrylamide hydrogel particles to create a soft poro-elastic material, are compared qualitatively with the predictions of the model.

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