In this work, the Raman spectra of LCCs encapsulated single-walled carbon nanotubes (SWCNTs) are calculated using the spectral moment’s method. To derive the optimum configurations of the linear ...carbon chains inside nanotubes, the minimum energy calculations using a convenient Lennard-Jones expression of the van der Waals intermolecular potential is devoted. The optimized structures show that the minima correspond to nanotubes configurations with diameter close to 0.68nm. The influence of the nanotube diameter and chirality are investigated. We also address the important question of the effect of filling degree using the frequency of Raman active modes. These predictions are useful to interpret the experimental data.
Current research develops a comprehensive wave propagation analysis of a magneto-electro-thermo-elastic (METE) nano-beam (NB) resting on the visco-elastic medium. To model the size dependency ...effects, modified couple stress (MCS) and Eringen's nonlocal (ENL) theories are employed to analyze and describe the wave propagation behaviors for those nano-beams. These theories were the most used in the literature due to the inclusion of one additional size-dependent length scale parameter. Those theories are compared side by side in this investigation and their impacts/differences on the wave propagation of specific materials are explored. Sinusoidal shear deformation beam model with Hamilton's principle is adopted to develop the governing equations of motion. Then, an analytical solution is executed to extract numerical results for transverse wave propagation in both elastic and METE configurations of the nano-beam. The effects of size-dependent length scale of both theories, thickness of NB, Winkler-Pasternak coefficients, thermal gradient, and magnetic potential and external electric voltage are illustrated and discussed in details. It is concluded that wave frequency decreases with increment of nonlocal parameter for ENL model. On the other hand, a stiffening effect takes place for the wave frequency when the MCS model is considered. Hence, the results indicate that there is a significant difference between ENL and MCS theories in the estimation of the behavior of wave propagation in small-scale structures. One of the main results of this investigation indicates that the MCS theory has similar nonlocal effects as the Eringen's theory for specific conditions.
•Comprehensive wave-propagation analysis on METE nano-beams is presented.•MCST and ENLT are considered as non-classical elasticity to establish the model.•Wave-propagation analysis is considered under elastic foundation and thermal effects.•Effects of nonlocal and length scale parameters are discussed in details.•Selecting the proper theory with correct size effect parameter to describe the wave behavior of small-scale structures.
The new technologies used in the green transition towards carbon-free societies typically demand extensive use of metals. This leads to a heavily growing need for exploration and extraction of ore ...deposits. Exploration can be facilitated by measuring metal concentrations in ground and surface waters carrying trace concentrations of metals leached from nearby deposits. Currently, measuring metal concentrations in water is slow and expensive and it cannot be done on-site, which hinders the discovery of new ore deposits. To address this challenge, we have developed a method to collect and concentrate the dissolved metals in a solid filter and measure the metal concentrations directly from the filter with a portable X-ray fluorescence spectrometer. The permeable filter is made of mesoporous silicon modified with bisphosphonates. Two types of adsorbing materials for the filters were prepared based on scalable production methods: i) regenerative etching of metallurgical grade silicon powder, and ii) magnesiothermic reduction of silica from barley husks. Empirical calibrations were prepared in a concentration range of 10–200 μg/L for Mn, Co, Ni, Cu, Zn, and Pb using water samples prepared by spiking well water with standard metal solutions. Both filter types were tested for their ability to adsorb metals from the real water samples taken from drill holes. The developed system was able to detect metal concentrations down to 12 μg/L (ppb) showing its potential for on-site measurements of dissolved metals in water samples, which could be feasible in the discovery of new mineral deposits. This innovation enables smart sampling during exploration and provides real-time information on metal concentrations in water.
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•Developed an on-site system for analysis of low metal concentrations in water with preconcentration filters and portable XRF.•The developed system measures Mn, Co, Ni, Cu, Zn and Pb down to 12 μg/L concentrations.•Demonstrated system's effectiveness in mineral exploration using drill hole water samples.
We study two types of linear instabilities in Einstein-Born-Infeld-scalar field theory and show that small Born-Infeld (BI) black holes suffer from superradiant instability within a particular range ...of frequencies; the larger the BI coupling parameter, the slower the growth rate of the instability. It is predicted that a small BI black hole decays into a small hairy black hole that has a charged scalar condensate floating near the horizon. We numerically show that there is a phase transition between hairy and BI black holes. The metric solution shows the existence of a hairy black hole for T<Tc and a BI black hole for T>Tc. In addition, the BI black hole will suffer from tachyonic mass, resulting in a near horizon scalar condensation instability, which is related to a planar hairy black hole. We show that the BI coupling parameter has a direct relation to the critical temperature in the small hairy black hole framework. This is not true for planar hairy black holes where a larger BI coupling parameter leads to a smaller critical temperature. Finally, it is shown that a small hairy black hole is stable at the critical temperature so it can be considered as the end point of superradiant instability.
The pion-less effective field theory has been used to study the
H
3
(
α
,
γ
)
7
L
i
reaction using the Faddeev equation procedure. This reaction is the seventh interaction in the Big Bang ...Nucleosynthesis (BBN) model which has a golden role in the estimating of
L
7
i
abundance in the universe, and answering the “cosmological lithium problem”. In this work the astrophysical s-factor of the
H
3
(
α
,
γ
)
7
L
i
reaction has been calculated in leading order (LO), considering the Coulomb interactions, for the dominant electrical
E
1
transition from the s-and p-wave initial states to the final ground state of
L
7
i
, at the astrophysical range of
E
≤
1.5
MeV.
•Nurses who experience WPV complain of mental and physical health problems.•Nurses’ social and professional lives were affected negatively after facing WPV.•WPV consequences negatively impact nurses ...and the entire healthcare organization.•The serious consequences of WPV ultimately harm patient care.•Preventing violence will ensure a safe workplace and safer patient care.
Workplace violence (WPV) in healthcare organizations can lead to serious consequences that negatively affect nurses’ lives and patient care. There is limited research on the deeper, underlying consequences of WPV for emergency nurses, particularly among emergency nurses in Iran.
A qualitative exploratory design was utilized. Semi-structured interviews were conducted with sixteen nurses working in emergency departments in five hospitals in west and east Azerbaijan of Iran. Data were analyzed using conventional content analysis.
“Suffering nurses” emerged as a primary theme of underlying consequences of WPV for emergency nurses. Four sub-themes of suffering were revealed: “mental health risks”; “physical health risks”; “threats to professional integrity”; and “threats to social integrity.”
Emergency nurses suffer from consequences following WPV. These consequences may not be addressed by staff health and safety programs, putting nurses at further risk. The findings of this study can help policy makers, healthcare leadership, and managers better understand the consequences of WPV so they can advocate for and establish WPV prevention programs and support for nurses who have experienced WPV. Preventing violence and providing support for nurses will ensure a safe workplace and safer patient care.
In this theoretical work, we study the Raman spectra of double-walled boron nitride nanotubes (DBNNTs) as a function of their diameters, chiralities, and lengths. Calculations are performed using the ...spectral moments method coupled to the bond polarizability model. This original approach allows us to consider not only infinite tubes as usual in most theoretical models but also tubes with finite lengths. We provide benchmark theoretical data to estimate the diameter and length of DBNNTs using Raman measurements.
This work focuses on a bundle of two van der Waals-coupled single wall carbon nanotubes. The non-resonant Raman spectra of inhomogeneous dimers of single walled of carbon nanotubes are calculated in ...the framework of spectral moments method, together with a bond-polarizability model. The evolution of the low frequency Raman-active modes as a function of the nanotube diameters is discussed. Effects of van der Waals coupling on charge transfer processes are also investigated. The obtained results are compared to experimental Raman data measured on dimer sample.
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