finite-element-modeling-for-simulation-quasi-static-compression

Finite Element Modeling for the Simulation of the Quasi-Static Compression of Corrugated Tapered Tubes

In this study, the quasi-static compression performance of tapered tubes was investigated using finite element simulations. Previous studies have shown ...

Guangzhou University

The structural, vibrational and Raman spectra properties of monolayer and bilayer TiC excited by two commonly used laser lines (532 nm and 633 nm) are investigated by first principles calculations to establish a correlation among layer stacks and optical features for two-dimensional MXenes. The stability of the monolayer and the energetically preferable stacking configuration are demonstrated by phonon dispersion. The monolayer and bilayer TiC systems are found to exhibit different point group symmetries and thereby the Raman properties due to the symmetry breaking of the bilayer structure caused by interlayer van der Waals interactions. We listed all Raman-active modes for monolayer (bilayer) TiC, , one (five) out-of-plane A (A) and one (five) pair (pairs) of degenerate in-plane E (E) vibration modes. Polarization angle dependent Raman intensity has been discussed in terms of the locations of two (four) maxima in the parallel (perpendicular) configuration, which might be applied in experimentally identifying monolayer and bilayer TiC. The difference in the polarization direction averaged Raman spectra between monolayer and bilayer TiC can be explained by the characteristics of light absorbance.

Theoretical assessment of Raman spectra on MXene TiC: from monolayer to bilayer.

To avoid carcinogenicity, formaldehyde gas, currently being only detected at higher operating temperatures, should be selectively detected in time with ppb concentration sensitivity in a room-temperature indoor environment. This is achieved in this work through introducing oxygen vacancies and Pt clusters on the surface of InO to reduce the optimal operating temperature from 120 to 40 °C. Previous studies have shown that only water participates in the competitive adsorption on the sensor surface. Here, we experimentally confirm that the adsorbed water on the fabricated sensor surface is consumed via a chemical reaction due to the strong interaction between the oxygen vacancies and Pt clusters. Therefore, the long-term stability of formaldehyde gas detection is improved. The results of theoretical calculations in this work reveal that the excellent formaldehyde gas detection of Pt/InO originates from the electron enrichment due to the surface oxygen vacancies and the molecular adsorption and activation ability of Pt clusters on the surface. The developed Pt/InO sensor has potential use in the ultraefficient, low-temperature, highly sensitive, and stable detection of indoor formaldehyde at an operating temperature as low as room temperature.

Anchoring Platinum Clusters onto Oxygen Vacancy-Modified InO for Ultraefficient, Low-Temperature, Highly Sensitive, and Stable Detection of Formaldehyde.

A large area of randomly distributed nanospike as nanostructured template was induced by femtosecond (fs) laser on a silicon substrate in water. Copper oxide (CuO) and palladium (Pd) heterostructured nanofilm were coated on the nanospikes by magnetron sputtering technology and vacuum thermal evaporation coating technology respectively for the construction of a p-type hydrogen sensor. Compared with the conventional gas sensor based on CuO working at high temperature, nanostructured CuO/Pd heterostructure exhibited promising detection capability to hydrogen at room temperature. The detection sensitivity to 1% H was 10.8%, the response time was 198 s, and the detection limit was as low as 40 ppm, presenting an important application prospect in the clean energy field. The excellent reusability and selectivity of the CuO/Pd heterostructure sensor toward H at room temperature were also demonstrated by a series of cyclic response characteristics. It is believed that our room-temperature hydrogen sensor fabricated with a waste-free green process, directly on silicon substrate, would greatly promote the future fabrication of a circuit-chip integrating hydrogen sensor.

Integrated CuO/Pd Nanospike Hydrogen Sensor on Silicon Substrate.

Monolayer XP (X = Ge, In) is a theoretically predicted two-dimensional (2D) material with fascinating adsorption efficiency, foreshadowing its potential applications in the photovoltaic and optoelectronic communities. To achieve a comprehensive understanding of its optical properties and to further boost quickly identifying its specific applications, in this paper we systematically investigated the polarization-resolved and helicity-resolved Raman spectra excited by two commonly used laser lines (532 nm and 633 nm) through density functional theory. The dynamical stability of monolayer XP is demonstrated by phonon dispersion. Monolayer GeP and InP are found to exhibit significantly different point group symmetries and thereby Raman properties due to the big difference in atomic size and electronic configurations between the Ge atom and In atom. Raman anisotropy of monolayer XP has been found when the wave vector of linear polarized incident light is parallel to the monolayer, and all the anisotropic Raman active phonons are categorized in terms of the locations of two (four) maxima in polarization angle dependent Raman intensities of the parallel (perpendicular) configuration. The polarization direction averaged Raman spectra have been further discussed according to the characteristics of light absorbance. The calculations of helicity-resolved Raman spectra indicate a stronger helicity selection rule under helical excitation with the wave vector normal to the monolayer. The present work paves the way for the suitable design, characterization and exploitation of the proposed 2D material with controllable surface properties for applications in electronics and optoelectronics.

Article	Year
Theoretical assessment of Raman spectra on MXene TiC: from monolayer to bilayer. Physical chemistry chemical physics : PCCP\| PubMed ID: 34525144	2021
Anchoring Platinum Clusters onto Oxygen Vacancy-Modified InO for Ultraefficient, Low-Temperature, Highly Sensitive, and Stable Detection of Formaldehyde. ACS sensors\| PubMed ID: 35362946	2022
Integrated CuO/Pd Nanospike Hydrogen Sensor on Silicon Substrate. Nanomaterials (Basel, Switzerland)\| PubMed ID: 35564243	2022
Polarization-resolved and helicity-resolved Raman spectra of monolayer XP (X = Ge and In). Physical chemistry chemical physics : PCCP\| PubMed ID: 36598003	2023

Shaolin Zhang

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