scholarly journals Dissociating stable nitrogen molecules under mild conditions by cyclic strain engineering

2019 ◽  
Vol 5 (11) ◽  
pp. eaax8275 ◽  
Author(s):  
Gao-Feng Han ◽  
Xiang-Mei Shi ◽  
Seok-Jin Kim ◽  
Jeonghun Kim ◽  
Jong-Pil Jeon ◽  
...  
Keyword(s):  
Scientific Community ◽  
Compressive Strain ◽  
Direct Synthesis ◽  
Mechanical Strain ◽  
Cyclic Strain ◽  
Strain Engineering ◽  
Mild Conditions ◽  
Cyclic Loading And Unloading ◽  
Challenging Tasks ◽  
Loading And Unloading

All quiet on the nitrogen front. The dissociation of stable diatomic nitrogen molecules (N2) is one of the most challenging tasks in the scientific community and currently requires both high pressure and high temperature. Here, we demonstrate that N2 can be dissociated under mild conditions by cyclic strain engineering. The method can be performed at a critical reaction pressure of less than 1 bar, and the temperature of the reaction container is only 40°C. When graphite was used as a dissociated N* receptor, the normalized loading of N to C reached as high as 16.3 at/at %. Such efficient nitrogen dissociation is induced by the cyclic loading and unloading mechanical strain, which has the effect of altering the binding energy of N, facilitating adsorption in the strain-free stage and desorption in the compressive strain stage. Our finding may lead to opportunities for the direct synthesis of N-containing compounds from N2.

QDs-Epoxy Resin for Strain Monitoring

2016 ◽  
Vol 853 ◽  
pp. 508-513
Author(s):  
Qi Xin Zhong ◽  
Shao Feng Yin ◽  
Zi Ming Zhao ◽  
Wei Ling Luan
Keyword(s):  
Epoxy Composite ◽  
Mechanical Strain ◽  
Tensile Tests ◽  
Transmission Electron Microcopy ◽  
Cyclic Loading And Unloading ◽  
Strain Monitoring ◽  
Transmission Electron ◽  
Before And After ◽  
Loading And Unloading ◽  
Pl Intensity

The discovery of the variation of the photoluminescence (PL) intensity of quantum dots (QDs) with mechanical deformation has stimulated the interest of developing QDs-based structures for the measurement and monitoring of stress or strain. In this work, tensile bars with the coating of QDs-epoxy composite are subjected to cyclic loading and unloading tests, and the PL intensity of the coating of QDs-epoxy composite is measured as a function of mechanical strain. There are four types of responses in the PL intensity, depending on the loading condition. Transmission electron microcopy is used to examine the rearrangement of QDs in the coatings before and after the tensile tests for understanding the change in the PL response.

Synergistic vacancy defects and mechanical strain for the modulation of the mechanical, electronic and optical properties of monolayer tungsten disulfide

2021 ◽  
Vol 23 (10) ◽  
pp. 6298-6308
Author(s):  
Chan Gao ◽  
Xiaoyong Yang ◽  
Ming Jiang ◽  
Lixin Chen ◽  
Zhiwen Chen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Transition Metal ◽  
Mechanical Strain ◽  
Transition Metal Dichalcogenides ◽  
Strain Engineering ◽  
Tungsten Disulfide ◽  
Defect Engineering ◽  
Vacancy Defects ◽  
Electronic And Optical Properties ◽  
Metal Dichalcogenides

The combination of defect engineering and strain engineering for the modulation of the mechanical, electronic and optical properties of monolayer transition metal dichalcogenides (TMDs).

scholarly journals Recent Advances in Rapid Synthesis of Non-proteinogenic Amino Acids from Proteinogenic Amino Acids Derivatives via Direct Photo-Mediated C–H Functionalization

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5270
Author(s):  
Zhenbo Yuan ◽  
Xuanzhong Liu ◽  
Changmei Liu ◽  
Yan Zhang ◽  
Yijian Rao
Keyword(s):  
Amino Acids ◽  
Direct Synthesis ◽  
Environmentally Friendly ◽  
Powerful Method ◽  
Rapid Synthesis ◽  
Conservation Of Energy ◽  
Mild Conditions ◽  
Recent Advances ◽  
Recent Developments

Non-proteinogenic amino acids have attracted tremendous interest for their essential applications in the realm of biology and chemistry. Recently, rising C–H functionalization has been considered an alternative powerful method for the direct synthesis of non-proteinogenic amino acids. Meanwhile, photochemistry has become popular for its predominant advantages of mild conditions and conservation of energy. Therefore, C–H functionalization and photochemistry have been merged to synthesize diverse non-proteinogenic amino acids in a mild and environmentally friendly way. In this review, the recent developments in the photo-mediated C–H functionalization of proteinogenic amino acids derivatives for the rapid synthesis of versatile non-proteinogenic amino acids are presented. Moreover, postulated mechanisms are also described wherever needed.

A rig for controlled cyclic strain and temperature testing

1982 ◽  
Vol 17 (1) ◽  
pp. 45-52 ◽  
Author(s):  
D J Beauchamp ◽  
E G Ellison
Keyword(s):  
Mechanical Strain ◽  
Thermal Strain ◽  
Cyclic Strain ◽  
Heating System ◽  
Temperature Cycle ◽  
Transient Temperature ◽  
Microprocessor System ◽  
Hydraulic Test ◽  
Heating And Cooling ◽  
Phase Temperature

A servo-hydraulic test rig capable of applying combined temperature and strain or load cycles has been developed and commissioned. The nature of the test has dictated the specimen form as a hollow, hour-glass type. The critical problem of a suitable extensometer for temperature and strain cycling has been solved. The device designed and produced shows negligible transient temperature effects, has a high resolution of better than 0.1 μm, and is mechanically very stable. The heating and cooling is controlled by an induction heating system with grip cooling; additional cooling is available using compressed air passing through the hollow specimen. The system is capable of following a temperature ramp to within 1°C linearity. The thermal strain associated with a temperature cycle is compensated for using a microprocessor system specially developed for the purpose, which also enables a mechanical strain-stress loop to be plotted during a test. Both ‘in-phase’ and ‘out-of-phase’ temperature/strain cycles have been carried out and development continues to include dwell periods.

Some aspects of the formation and structural features of low nuclearity heterometallic carboxylates

2020 ◽  
Vol 92 (7) ◽  
pp. 1093-1110 ◽  
Author(s):  
Aleksey A. Sidorov ◽  
Natalia V. Gogoleva ◽  
Evgeniya S. Bazhina ◽  
Stanislav A. Nikolaevskii ◽  
Maksim A. Shmelev ◽  
...  
Keyword(s):  
Ligand Exchange ◽  
Direct Synthesis ◽  
Molecular Complexes ◽  
Structural Features ◽  
Exchange Reactions ◽  
Metal Core ◽  
Mild Conditions ◽  
Metal Organic ◽  
Heterometallic Carboxylates ◽  
Molecular Compounds

AbstractHeterometallic carboxylate complexes are of paramount interest in pure and applied coordination chemistry. Despite that plurality of such type compounds have been published to date, synthetic aspects of their chemistry often remain in the shadow of intriguing physical properties manifesting by these species. Present review summarizes reliable data on direct synthesis of low nuclearity molecular compounds as well as coordination polymers on their base with carboxylate-bridged {M2Mg} (M = Co2+, Ni2+, Cd2+), {M2Li2} (M = Co2+, Ni2+, Zn2+, VO2+), {M2Ln2} and {M2Ln} (M = Cu2+, Zn2+, Co2+) metal cores. Structural features and stabilization factors are considered and principal outcomes are confirmed by quantum-chemical calculations. Particular attention is paid to consideration of ligand-exchange reactions that allow controllable modification of heterometallic metal core under mild conditions giving diverse molecular complexes with modified ligand environment or Metal-Organic Frameworks with permanent porosity.

Strain-engineering in AlGaN/GaN HEMTs: impact of silicon nitride passivation layer on electrical performance

2021 ◽  
Author(s):  
Sanghamitra Das ◽  
Taraprasanna Dash ◽  
Devika Jena ◽  
Eleena Mohapatra ◽  
C K Maiti
Keyword(s):  
Experimental Data ◽  
Compressive Strain ◽  
Cutoff Frequency ◽  
Strain Engineering ◽  
Electrical Performance ◽  
Current Gain ◽  
Great Promise ◽  
High Electron ◽  
Wide Range ◽  
Gan Hemts

Abstract In this work, we present a physics-based analysis of two-dimensional electron gas (2DEG) sheet carrier density and other microwave characteristics such as transconductance and cutoff frequency of AlxGa1-xN/GaN high electron mobility transistors (HEMT). An accurate polarization-dependent charge control-based analysis is performed for microwave performance assessment in terms of current, transconductance, gate capacitances, and cutoff frequency of lattice-mismatched AlGaN/GaN HEMTs. The influence of stress on spontaneous and piezoelectric polarization is included in the simulation of an AlGaN/GaN HEMT. We have shown the change in threshold voltage (Vt) due to tensile and compressive strain with different gate lengths. Also, the influence of stress due to the change in nitride thickness is presented. Our simulation results for drain current, transconductance, and current-gain cutoff frequency for various gate length devices are calibrated and verified with experimental data over a wide range of gate and drain applied voltages, which are expected to be useful for microwave circuit design. The predicted transconductance, drain conductance, and operation frequency are quite close to the experimental data. The AlGaN/GaN heterostructure HEMTs with nitride passivation layers show great promise as a candidate in future high speed and high power applications.

Adjustable buttons for ACL graft cortical fixation partially fail with cyclic loading and unloading

2018 ◽  
Vol 27 (8) ◽  
pp. 2530-2536 ◽  
Author(s):  
J. Glasbrenner ◽  
C. Domnick ◽  
M. J. Raschke ◽  
T. Willinghöfer ◽  
C. Kittl ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Acl Graft ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading

scholarly journals Experimental Study of Stress-Seepage Coupling Properties of Sandstone under Different Loading Paths

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Xi Chen ◽  
Wei Wang ◽  
Yajun Cao ◽  
Qizhi Zhu ◽  
Weiya Xu ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Pore Pressure ◽  
Complex Loading ◽  
Friction Angle ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Biot Coefficient ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading

The study on hydromechanical coupling properties of rocks is of great importance for rock engineering. It is closely related to the stability analysis of structures in rocks under seepage condition. In this study, a series of conventional triaxial tests under drained condition and hydrostatic compression tests under drained or undrained condition on sandstones were conducted. Moreover, complex cyclic loading and unloading tests were also carried out. Based on the experimental results, the following conclusions were obtained. For conventional triaxial tests, the elastic modulus, peak strength, crack initiation stress, and expansion stress increase with increased confining pressure. Pore pressure weakened the effect of the confining pressure under drained condition, which led to a decline in rock mechanical properties. It appeared that cohesion was more sensitive to pore pressure than to the internal friction angle. For complex loading and unloading cyclic tests, in deviatoric stress loading and unloading cycles, elastic modulus increased obviously in first loading stage and increased slowly in next stages. In confining pressure loading and unloading cycles, the Biot coefficient decreased first and then increased, which indicates that damage has a great impact on the Biot coefficient.

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