156 Results Found

The investigation of the sensitivity of the relativistic corrections to the NMR shielding constants (σ) to the configuration of angular spaces of the basis sets used on the atoms of interest was carried out within the four-component density fun...

With the development of wireless power transfer (WPT), the wireless charging has become a research hotspot. This paper proposes a novel single-switch hybrid compensation topology, which can change the compensation network to realize the constant-curr...

The relativistic effects of the values of the shielding constants of ¹H, ¹³C, ¹⁵N, ⁵⁷Fe, ⁵⁹Co, ⁶¹Ni, ¹⁰⁵Pd, and ¹⁹⁵Pt nuclei were studied at the four-component relativistic level and were compared to the results of non-relativistic calculations perfo...

Nuclear magnetic resonance (NMR) is a branch of spectroscopy commonly used for identifying the chemical structure of various materials. One of the areas in which NMR provides accurate data is the determination of nuclear magnetic moments. This work r...

An investigation was conducted into the effectiveness of heat shields in an aero-engine compressor casing to slow down thermal time constants. The investigation used a combination of experimental measurements from a full-size compressor casing rig, c...

A recently developed methodology for calculating, analyzing, and visualizing nuclear magnetic shielding densities is used for studying spatial contributions including ring-current contributions to ${}^1$H nuclear magnetic resonance (NMR) chemical shifts o...

This review represents a compendium of computational studies of relativistic effects on the NMR chemical shifts of light nuclei caused by the presence of heavy main group p-block elements in molecules. The narration starts from a brief discussion of...

LiCl and LiNO₃ water solutions in the presence of small amounts of 3-helium have been investigated by means of multinuclear resonance spectroscopy. The resulting concentration dependences of the ³He, ^6,7Li⁺, ¹⁴NO₃⁻ and ³⁵Cl⁻ resonance radiofrequencie...

A root factor for the accuracy of all quantum chemical calculations of nuclear magnetic resonance (NMR) chemical shifts is the quality of the molecular equilibrium geometry used. In turn, this quality depends largely on the basis set employed at the...

Environmentally friendly materials with superior structural, physical, optical, and shielding capabilities are of great technological importance and are continually being investigated. In this work, novel multicomponent borate glasses with the compos...

Relativistic effects are found to be important for the estimation of NMR parameters in halogen-bonded complexes, mainly when they involve the heavier elements, iodine and astatine. A detailed study of 60 binary complexes formed between dihalogen mole...

Both four-component relativistic and nonrelativistic computations within the GIAO-DFT(PBE0) formalism have been carried out for ¹⁵N and ⁵⁹Co NMR shielding constants and chemical shifts of a number of the nitrogen-coordinated complexes of cobalt. It w...

MP2/aug’-cc-pVTZ calculations have been carried out to investigate the halogen-bonded complexes formed when CO and CS act as electron-pair donors through C to ClF, ClNC, ClCl, ClOH, ClCN, ClCCH, and ClNH₂. CO forms only complexes stabilized by tradit...

In recent years, we have seen spectacular growth in the experimental and theoretical investigations of magnetic properties of small subatomic particles: electrons, positrons, muons, and neutrinos. However, conventional methods for establishing these...

Theoretical results for the magnetic shielding of protonated and unprotonated nitrogens of eumelanin building blocks including monomers, dimers, and tetramers in gas phase and water are presented. The magnetic property in water was determined by carr...

This work proposes a systematic study of different computational schemes for fluorine Nuclear Magnetic Resonance (¹⁹F NMR) chemical shifts, with special emphasis placed on the basis set issue. This study encompasses two stages of calculation, namely,...

Medical shielding suits must be lightweight and satisfy the requirements of thin films to guarantee user mobility and safety. The thin film weight is related to the density and thickness, which are associated with the particle dispersion in shielding...

Liquid exfoliated molybdenum disulfide (MoS₂) nanosheets and polyaniline (PANI) nanoparticles are dispersed in polystyrene (PS) matrix to fabricate hybrid polymer composites with high dielectric and electromagnetic interference (EMI) shielding behavi...

Focusing on the shielding effectiveness of a single-layer shielded cavity, especially the impact of aperture shape, aperture quantity, internal dielectric plate, and other factors on shielding effectiveness, an equivalent circuit model and BLT equati...

Carbon nanotube-based nanocomposites are being increasingly utilized in materials for electromagnetic shielding purposes due to their exceptional electrical and mechanical properties. The current study optimizes a simple procedure to prepare multi-wa...

In automotive high voltage (HV) systems, the switching operation of a power electronic converter causes current and voltage ripple in the frequency range of [10 Hz–150 kHz]. Automotive system engineering provides requirements that define the be...

3-Alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1) reacted with 5-methylfuran-2-carboxyaldehyde to afford the corresponding 3-alkyl(aryl)-4-(5-methyl-2-furylmethylenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (2). Four newly synthesized com...

In this work, magnetic soft ferrites, namely manganese–zinc ferrite, nickel–zinc ferrite and combinations of both fillers, were incorporated into acrylonitrile-butadiene rubber to fabricate composite materials. The total content of ferrit...

This study carried out a comparison of the optical and gamma ray shielding features of TeO₂ with and without ZnO modifier concentration. Incorporating ZnO into the TeO₂ network reduces the indirect band gap from 3.515–3.481 eV. When ZnO is adde...

Multinuclear NMR studies of the gaseous mixtures that involve volatile compounds and ³He atoms are featured in this review. The precise analyses of ³He and other nuclei resonance frequencies show linear dependencies on gas density. Extrapolation of t...

Three types of composites were tested for electromagnetic interference (EMI) absorption shielding effectiveness, the curing process, and their physical–mechanical properties. For the first type of composites, nickel–zinc ferrite, manganes...

To reduce traffic congestion and meet the demand for rail transportation, the diameters of shield tunnels are constantly expanded. The super-large diameter, deep depth and long distance of super-large-diameter shield tunnels, coupled with the limitat...

Polyimide, a class of high-performance polymers, is renowned for its exceptional thermal stability, mechanical strength, and chemical resistance. However, in the context of high-integration and high-frequency electronic packaging, polyimides face cri...

Multigroup constants are the foundation of neutron and photon transport problems, and the accuracy of multigroup cross-sections has a significant impact on shielding calculation. Challenges have arisen in generating accurate multigroup macroscopic cr...

In recent years, it has been found that the service life of cemented carbide shield machine tools used in uneven soft and hard strata is substantially reduced in engineering practice. The study found that thermal stress is the main reason for the fai...

Safety and environmental protection are key issues in shield construction. Due to wear, the cutter of a shield machine must be changed after a period of excavation. In order to realize the tool change operation of a shield machine at atmospheric pres...

Shield tunnels’ structural stability is challenged due to the fact that they are often built under rivers, lakes, and oceans. It is crucial to execute the structural deformation perception of the shield tunnel. Fiber Bragg grating (FBG) sensing...

This paper aims to study the radiation shielding characteristics and buildup factor of some types of granite in Egypt. The mass attenuation coefficient (MAC) for three types of granite (gandola, white halayeb, and red aswani) was experimentally deter...

The small amounts of gaseous ³He dissolved in low concentrated water solutions of NaCl, NaNO₃ and NaClO₄ were prepared and examined by ³He-, ²³Na-, ³⁵Cl- and ¹⁵N-NMR spectroscopy. This experimental data, along with new theoretical shielding factors,...

Shield segments of subway tunnels are often exposed to the combined actions of several hygrothermal factors that could lead to accidents such as water seepage and tunnel collapse. Further, they often break and deform owing to formation pressure. In a...

In recent years, polymer-based hybrid nanocomposites have emerged as promising alternatives to traditional heavy metal shields due to their low density, flexibility, and environmental safety. In this study, the synthesis of PS-PEG copolymers and the...

The efficient and accurate calculation of neutron flux distribution is essential for evaluating the safety of nuclear facilities and the surrounding environment. While traditional numerical simulation methods such as the discrete ordinates (S_N) metho...

Ti-based MXenes such as Ti₃C₂T_X and Ti₂CT_X have attracted considerable attention because of their superior electromagnetic interference (EMI) shielding effectiveness compared to other EMI shielding materials, especially for high electromagnetic (EM)...

To explore the influence of shield construction on the stress of tunnels surrounding rock and linings in deep, high groundwater and low-permeability soft rock strata, a 3D coupled hydro-mechanical model of a low permeability mudstone tunnel was estab...

Interdigitated dielectrometry sensors (IDS) are capacitive sensors investigated to precisely measure the relative permittivity ( ${ϵ}_{\text{r}}$ ) of insulating liquids. Such liquids used in the power industry exhibit a change in ${ϵ}_{\text{r}}$ as they de...

From the aspect of calculation theory, the beam–spring model method and modified routine method of shield tunnel segment structure calculation were improved, and an efficient integrated software system for segment structure calculation of shiel...

This paper focuses on electromagnetic transverse-electric wave propagation in a planar shielded waveguide filled with nonlinear medium. Instead of using the standard local Kerr (cubic) nonlinearity, we suggest a (nonlocal) modification of this law. I...

Aiming at studying the harm caused by sudden ground loadings on existing shield tunnels, a indoor scaled model test with a geometric similarity ratio of 1:15.5 was adopted. Considering the influencing factors such as ground loading, burial depth of t...

Superparamagnetic ZnFe₂O₄ spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe₂O₄ spinel ferrite na...

The longitudinal equivalent continuous model generally only studies the stiffness of shield tunnels under longitudinal bending moments, considering it a constant. However, in actual engineering, shield tunnels are exposed to complex environments wher...

¹H and ¹³C NMR chemical shifts of the tetrakis monoterpene indole alkaloid alasmontamine A, with a molecular formula of C₈₄H₉₁N₈O₁₂, have been calculated within the DFT framework. Six minimum energy conformers of this alkaloid were identified, and th...

The high porosity of a GaN porous structure (PS) makes it mechanically semi-flexible and can shield against the stress from the thick growth template on an overgrown layer to control the lattice structure or composition within the overgrown layer. To...

A synthetic procedure for the synthesis of azacrown ethers with a combination of pendant arms has been developed and the synthesized ligand, characterized by various techniques, was studied. The prepared benzoazacrown ether with hybrid pendant arms a...

The optical and radiation shielding of PVA have been enhanced through embedding with ZnO/CuO/SWCNT (ZCS) nanocomposites. ZCS polymeric nanocomposites (PNCs) were prepared with the solution casting method. Scanning electron, optical microscopy and FT-...

Polymeric permselective films are frequently used for amperometric biosensors to prevent electroactive interference present in the target matrix. Phenylenediamines are the most commonly used for the deposition of shielding polymeric films against int...