scholarly journals Ultrafast Laser Processing of Diamond Materials: A Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Tzveta Apostolova ◽  
Vasyl Kurylo ◽  
Iaroslav Gnilitskyi
Keyword(s):  
Electronic Excitation ◽  
State Of The Art ◽  
Ultrafast Laser ◽  
Theoretical Studies ◽  
Structural Modifications ◽  
Wide Range ◽  
Quantitative Understanding ◽  
Laser Engineering ◽  
Ultrashort Laser ◽  
Experimental And Theoretical Studies

Diamond laser engineering is of great importance for designing devices, which find applications in radiation sensing and quantum technologies. A review of the present state of the art of experimental and theoretical studies on ultrashort laser irradiation of diamond is presented. For a wide range of laser parameters, the optimization of laser-induced electronic, optical and structural modifications of diamond requires quantitative understanding of the microscopic processes underlying the high electronic excitation in the material.

The Stabilizing Effect of Pre-Equilibria: A Trifluoromethyl Complex as CF2 Reservoir in Catalytic Olefin Difluorocarbenation

2020 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  
Keyword(s):  
High Selectivity ◽  
Side Reactions ◽  
Theoretical Studies ◽  
Attractive Feature ◽  
Catalyst Recovery ◽  
Wide Range ◽  
Stabilizing Effect ◽  
Experimental And Theoretical Studies

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.

scholarly journals The Stabilizing Effect of Pre-Equilibria: A Trifluoromethyl Complex as CF2 Reservoir in Catalytic Olefin Difluorocarbenation

2020 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  
Keyword(s):  
High Selectivity ◽  
Side Reactions ◽  
Theoretical Studies ◽  
Attractive Feature ◽  
Catalyst Recovery ◽  
Wide Range ◽  
Stabilizing Effect ◽  
Experimental And Theoretical Studies

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.

scholarly journals Growth, Properties, and Applications of Branched Carbon Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2728
Author(s):  
Sharali Malik ◽  
Silvia Marchesan
Keyword(s):  
Carbon Nanotubes ◽  
Tissue Regeneration ◽  
Carbon Nanostructures ◽  
Structural Features ◽  
Theoretical Studies ◽  
Concise Review ◽  
Wide Range ◽  
Growth Properties ◽  
Experimental And Theoretical Studies ◽  
Advanced Applications

Nanomaterials featuring branched carbon nanotubes (b-CNTs), nanofibers (b-CNFs), or other types of carbon nanostructures (CNSs) are of great interest due to their outstanding mechanical and electronic properties. They are promising components of nanodevices for a wide variety of advanced applications spanning from batteries and fuel cells to conductive-tissue regeneration in medicine. In this concise review, we describe the methods to produce branched CNSs, with particular emphasis on the most widely used b-CNTs, the experimental and theoretical studies on their properties, and the wide range of demonstrated and proposed applications, highlighting the branching structural features that ultimately allow for enhanced performance relative to traditional, unbranched CNSs.

PZT Sensors and their Application in Structural Health Monitoring

2011 ◽  
Vol 128-129 ◽  
pp. 669-675 ◽  
Author(s):  
Xuan Sun
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Lamb Wave ◽  
State Of The Art ◽  
Research Work ◽  
Mechanical Systems ◽  
The State ◽  
Theoretical Studies ◽  
Engineering Systems ◽  
Experimental And Theoretical Studies

This paper provides the state of the art in methods to detect damage in structural and mechanical systems by PZT sensors, which include impedance methods and lamb wave propagations. The basic idea behind these technologies is to use impedance of PZT embedded on surface or lamb wave propagations. A brief overview of research work on experimental and theoretical studies on various structures and mechanical systems is descried. Past, current and applications of this technology in actual engineering systems are summarized. Finally, desirable developments for further advancement of this field are discussed.

scholarly journals A REVIEW OF HUMIDIFICATION-DEHUMIDIFICATION DESALINATION SYSTEMS

2020 ◽  
Vol 8 (5) ◽  
pp. 290-311
Author(s):  
Matheus Dias De Carvalho ◽  
Jane Selia Dos Reis Coimbra ◽  
Tiago Silva Miranda Lemos ◽  
Jorge David Alguiar Bellido ◽  
Antônio Marcos de Oliveira Siqueira
Keyword(s):  
State Of The Art ◽  
Theoretical Studies ◽  
Packed Beds ◽  
Project Data ◽  
Experimental And Theoretical Studies

This article aims to accomplish a review of state of the art in the humidification-dehumidification (HDH) desalination process. Foremost, an introduction to the main desalination technologies is presented to clarify the positives and negatives effects of each. Costs and project data are presented for experimental and theoretical studies. The information is shown by using tables, explaining the major variables, and the obtained results for each study. News regarding plants under the sea and packed beds are the main considerations of the present paper.

The dynamics of strong turbulence at free surfaces. Part 1. Description

2001 ◽  
Vol 449 ◽  
pp. 225-254 ◽  
Author(s):  
M. BROCCHINI ◽  
D. H. PEREGRINE
Keyword(s):  
Surface Tension ◽  
Surface Roughness ◽  
Free Surface ◽  
Water Waves ◽  
Theoretical Studies ◽  
Free Surfaces ◽  
Submerged Jets ◽  
Wide Range ◽  
Experimental And Theoretical Studies ◽  
Two Parameter

A free surface may be deformed by fluid motions; such deformation may lead to surface roughness, breakup, or disintegration. This paper describes the wide range of free-surface deformations that occur when there is turbulence at the surface, and focuses on turbulence in the denser, liquid, medium. This turbulence may be generated at the surface as in breaking water waves, or may reach the surface from other sources such as bed boundary layers or submerged jets. The discussion is structured by consideration of the stabilizing influences of gravity and surface tension against the disrupting effect of the turbulent kinetic energy. This leads to a two-parameter description of the surface behaviour which gives a framework for further experimental and theoretical studies. Much of the discussion is necessarily heuristic, and is often limited by a lack of appropriate experimental observations. It is intended that such experiments be stimulated, to test the value or otherwise of our two-parameter description.

Experimental and analytical investigation of impact dampers in free vibration reduction with coulomb friction

2021 ◽  
pp. 095745652110557
Author(s):  
Hossein Safaeifar ◽  
Anooshirvan Farshidianfar
Keyword(s):  
Free Vibration ◽  
Cantilever Beam ◽  
Coulomb Friction ◽  
Analytical Investigation ◽  
Harsh Environments ◽  
Theoretical Studies ◽  
Impact Damper ◽  
Wide Range ◽  
Passive Dampers ◽  
Experimental And Theoretical Studies

The presence of vibration in structures and machines can establish failures and reduce the efficiency. Passive dampers have been used extensively for vibration control because of their simple concept. One of these dampers is impact damper (ID). Impact dampers are suitable to operate in harsh environments and effective over a wide range of frequencies. In this paper, the experimental and theoretical investigation on the effect of the ID in free vibration of a cantilever beam is done. The lateral motion of the free end of the cantilever beam is modeled as one degree of freedom (1-DOF) system. The motion of the 1-DOF system equipped with the ID with Coulomb friction is studied analytically. Free vibration of cantilever beam investigated experimentally. The experimental results are presented and discussed. The damping inclination of the ID in various experimental and theoretical studies is proposed. The results show the validation between the experimental and the theoretical studies.

scholarly journals The Stabilizing Effect of Pre-Equilibria: A Trifluoromethyl Complex as CF2 Reservoir in Catalytic Olefin Difluorocarbenation

2021 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  
Keyword(s):  
High Selectivity ◽  
Side Reactions ◽  
Theoretical Studies ◽  
Attractive Feature ◽  
Catalyst Recovery ◽  
Wide Range ◽  
Stabilizing Effect ◽  
Experimental And Theoretical Studies

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.

scholarly journals Galactokinase promiscuity: a question of flexibility?

2016 ◽  
Vol 44 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Megan McAuley ◽  
Helena Kristiansson ◽  
Meilan Huang ◽  
Angel L. Pey ◽  
David J. Timson
Keyword(s):  
Active Site ◽  
Catalytic Mechanism ◽  
High Specificity ◽  
Enzyme Engineering ◽  
Structural Modifications ◽  
Leloir Pathway ◽  
Wide Range ◽  
Base Mechanism ◽  
Viable Approach ◽  
Experimental And Theoretical Studies

Galactokinase catalyses the first committed step of the Leloir pathway, i.e. the ATP-dependent phosphorylation of α-D-galactose at C1-OH. Reduced galactokinase activity results in the inherited metabolic disease type II galactosaemia. However, inhibition of galactokinase is considered a viable approach to treating more severe forms of galactosaemia (types I and III). Considerable progress has been made in the identification of high affinity, selective inhibitors. Although the structure of galactokinase from a variety of species is known, its catalytic mechanism remains uncertain. Although the bulk of evidence suggests that the reaction proceeds via an active site base mechanism, some experimental and theoretical studies contradict this. The enzyme has potential as a biocatalyst in the production of sugar 1-phosphates. This potential is limited by its high specificity. A variety of approaches have been taken to identify galactokinase variants which are more promiscuous. These have broadened galactokinase's specificity to include a wide range of D- and L-sugars. Initial studies suggest that some of these alterations result in increased flexibility at the active site. It is suggested that modulation of protein flexibility is at least as important as structural modifications in determining the success or failure of enzyme engineering.

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