We investigate the damping effects of coherent electron oscillations on the bandwidth of a quantized nanoparticle plasmon resonance. The nanoparticle (NP) is treated as a two-level quantum system, and the total relaxation time involves both the population relaxation time associated with radiative processes and the collisional relaxation time associated with nonradiative processes that result in dephasing/ decoherence of electron oscillations. We describe the optical response of NPs to an external electromagnetic field by the optical Bloch equations employing the density matrix formalism to capture the quantum description nature of dipolar plasmon resonance and suggest a generalized criterion for the validity of dipole approximation. Then we explore the competition between the radiative and nonradiative damping in determining the plasmon bandwidth of two typical NP models; metallic nanospheres and dielectric core–metal shell NPs (nanoshells). We show that the frequency of plasmon resonance, in addition to the NP size, plays an important role in the competition between the damping mechanisms. Consequently, the damping processes are significantly influenced by the factors that determine the resonance frequency, such as the core size, the dielectric constant of the medium, and the shell thickness (for nanoshells). For both models of NPs, we identify the optimum parameters that achieve a narrower plasmon bandwidth (minimal damping), which is a prerequisite for advanced sensing and medical applications. We demonstrate excellent agreement of the simulated spectral features of the plasmon resonance with previously reported experimental results for a single NP where the inhomogeneous broadening of the plasmon line is excluded. For NP ensembles where inhomogeneous broadenings and interface chemical effects are significant, our theoretical approach successfully predicts the overall trend of size-dependent damping rates.

Nowadays, plasmonic titanium nitride (TiN) is widely employed as a potential alternative to noble metals in semiconductor–metal hybrid nanoparticles (S–M HNPs) for improving the utilization efficiency of solar energy in photocatalytic and photovoltaic systems. In semiconductor–TiN nanosystems, TiN NPs convert solar energy into highly energetic (hot) electrons that can be transmitted to the attached semiconductor for enhanced applications. In this paper, we propose TiN nanoshells with a nonabsorbing dielectric core as an improved energy conversion component in S–M HNPs, compared to homogenous TiN nanospheres, with higher geometrical optimization flexibility, wider absorption range tuneability, and effective hot electron generation and utilization due to the reduced plasmonic-shell size. For understanding the impact of the core material on the functionality of the nanoshells, we assume three core materials with different refractive indices (air, silica (SiO₂), and magnesium oxide (MgO)). The exact Mie theory is utilized to calculate the absorption coefficient and the plasmon field of the proposed TiN nanoshells. To quantify the absorbance effectiveness on the solar spectrum, we calculate a relevant figure of merit (FoM) that depends on the spectral features of the absorption coefficient. By optimizing the geometrical parameters of nanoshells, it is found that hollow TiN nanoshells with the lowest core refractive index exhibit the highest FoM of solar energy absorption. Also, the plasmon field intensity of hollow TiN nanoshells is higher and more concentrated in a smaller volume of TiN material in comparison to the field intensity of other nanoshells (SiO₂–TiN and MgO–TiN nanoshells) and TiN nanospheres. Factors affecting the utilization of the generated hot electrons, including the radiative damping of plasmons and the spreading of the plasmon field inside the nanoparticles, have been investigated. In view of the temporal dynamics of hot electrons, it is shown that using the hollow TiN nanoshells with thin shells greatly enhances the effectiveness of the generated hot electrons to reach the attached semiconductor. In fact, the reduced plasmonic-shell thickness results in a trade-off between a longer radiative relaxation time and less solar energy absorption with regard to the selected core material.

There is currently a great deal of interest in realizing localized surface plasmon resonances (LSPRs) in two distinct windows in the near-infrared (NIR) spectrum for in vivo biosensing and medical applications, the biological window (BW) I and II (BW I, 700–900 nm; BW II, 1000–1700 nm). This study aims to
demonstrate that LSPRs of Ga-doped ZnO (GZO) core–silver (Ag) shell structures exhibit promising features for biological applications in the NIR BW I and II. Here, we study three different shapes for nanoshells: the core–shell nanosphere, nanorod, and nanodisk. In the calculation of the optical response of these nanoshells, an effective medium approach is first used to reduce the dielectric function of a nanoshell to that of an equivalent homogenous NP with an effective dielectric function. Then, the LSPR spectra of nanoshells are calculated using the modified long-wavelength approximation (MLWA), which corrects the polarizability of the equivalent NP as obtained by Gans theory. Through numerical investigations, we examine the impacts of the core and shell sizes of the proposed nanoshells as well as the medium refractive index on the position and line width of the plasmon resonance peaks. It is shown that the plasmon resonances of the three proposed nanoshells exhibit astonishing resonance tunability in the NIR region by varying their geometrical parameters. Specifically, the improved spectrum characteristics and tunability of its plasmon resonances make the GZO–Ag nanosphere a more viable
platform for NIR applications than the spherical metal colloid. Furthermore, we demonstrate that the sensitivity and figure of merit (FOM) of the plasmon resonances may be significantly increased by using GZO–Ag nanorods and nanodisks in place of GZO–Ag nanospheres. It is found that the optical properties of the transverse plasmon resonance of the GZO–Ag nanodisk are superior to all plasmon resonances produced by the GZO–Ag nanorods and GZO–Ag nanospheres in terms of sensitivity and FOM. The FOM of the transverse plasmon mode of the GZO–Ag nanodisk is almost two orders of magnitude higher than that of the longitudinal and transverse plasmon modes of the GZO–Ag nanorod in BW I and BW II. And it is 1.5 and 2 times higher than the plasmon resonance FOM of GZO–Ag nanospheres in BW I and BW II, respectively.

This paper is aimed at proposing a calculation model for the ground resistance of a grounding scheme servicing a high-voltage direct-current converter station. The method is based on the equivalence of current conduction and electric field from the grounding scheme through the surrounding medium. The grounding scheme is composed of three concentric ring electrodes supported by two horizontal conductors and eight vertical rods. The calculated ground resistance is 4.8 Ω4.8 Ω against the experimental value of 5 Ω5 Ω with an error of 4.2%4.2%. The calculated ground resistance value agrees reasonably well with that of 4.7 Ω4.7 Ω as obtained using CYMGRD software (version 7.0). The calculated surface-potential values over the ground surface agreed reasonably well with those measured experimentally, with an average deviation not exceeding 6.5%6.5%. This study is designed to investigate how ground resistance is decreased by the increase in the scheme parameters, including the rods’ diameter and length, as well as the radius of the inner and outer rings. The dependency of the ground resistance on the soil type is also investigated.

This study investigated the use of oxalic acid as an eco-friendly compound for extracting ulvan from Ulva linza biomass. The concentration of oxalic acid, temperature, and period of extraction were optimized using Box-Behnken design in response of ulvan yield, molecular weight (MW), sulphate content, uronic acid content, purity ratio (total sugars/total phenolics and proteins), and Fe(III) chelation properties. Under the optimized conditions (1.7 % w/v oxalic acid, 64 °C, and 2.63 h), ulvan yield, MW, sulphate content, uronic acid content, and purity ratio were 29.90 % (w/w), 32.22 kDa, 11.01 % (w/w), 8.12 % (w/w), and 12.84, respectively. The optimized ulvan exhibited good Fe(III) chelation of 18.58 % (w/w). The synthesized Fe-ulvan complex released approximately 73 % of the chelated Fe(III) under in vitro simulated gastro-intestinal conditions. Furthermore, both ulvan and Fe-ulvan complex exhibited potent antioxidant properties. FT-IR analysis confirmed the fundamental role played by hydroxyl, carboxyl and sulphate groups in the coordination of Fe(III). Furthermore, MW, MW/sulphate ratio, and MW/uronic acid ratio should be low to enhance the Fe(III) chelation properties of ulvan. The results of the present study shed light on the use of oxalic acid as a simple and environmentally-benign treatment for ulvan extraction, especially for the recovery of low MW ulvan with high yield and good Fe(III)-binding properties.

The well-distributed Late Cretaceous–early Paleogene rocks in Egypt are one of the keys to understanding the geologic history of the southern Tethys. Four Late Cretaceous–early Paleogene successions exposed in the Esh-ElMellaha area were investigated. The integrated stratigraphic analyses, including; field, lithostratigraphy and biostratigraphy of these sections within the Esh-ElMellaha ridge showed interesting results. Intensive tectonic processes throughout Paleocene period substantially influenced all rock units, causing differences in their facies and thickness. In addition, these tectonic processes deformed the sedimentary basins. During the Paleocene, Esh-ElMellaha area experienced two significant syn-sedimentary tectonic events (I and II) related to the Syrian Arc Tectonic Event. The evolution of the Esh-ElMellaha basin has been documented for the first time throughout this period which is extremely …

Detailed field and stratigraphic (lithostratigraphy & biostratigraphy) studies were carried out on the Upper Cretaceous–lower Paleogene successions at Esh-ElMellaha half-graben, Gulf of Suez, Egypt. Four stratigraphic sections were investigated and arranged in a geologic profile extends from south to north as follow: Gabal El-Mellaha, Wadi Abu Had, Wadi Dib and Gabal Tarbul. The field work led to recognize four lithostratigraphic units (formations): Sudr (upper part), Dib, Esna and Thebes (top). The distinctive Dababiya Quarry Member (DQM) which characterizes the Paleocene Eocene Thermal Maximum (PETM) was initially recorded at Esh-ElMellaha region. Sudr Formation is stratigraphically differentiated into two distinctive informal rock units, argillaceous bedded limestone unit and calcareous shale unit. The Dib Formation is here reviewed and correlates with the Dakhla Formation (upper part) in the different …

Detailed stratigraphic studies of the Paleocene-lower Eocene interval were conducted on four stratigraphic successions (Sudr-Alhitan, Thamad, Abu-Qada, and Nukhul) in central and southwestern Sinai. These sections are arranged along a North-South direction as: Sudr-Alhitan, Thamad, Abu-Qada, and Nukhul. The biostratigraphic framework was achieved by integrating data of calcareous nannofossils and planktonic foraminifera. The studied area experienced two major tectonic events, most likely related to the Syrian Arc System (SAS), which led to two distinct hiatuses of significant magnitude, evidenced from integrated biostratigraphic analysis and thorough field observations. Benthic foraminifera assemblages suggest a deposition in outer neritic to upper bathyal setting for investigated sites, except for the Tarawan and Thebes formations in Abu-Qada and Sudr-Alhitan sections, which were deposited in middle-outer neritic and outer neritic settings, respectively. Benthic foraminiferal indices indicate an oligo-mesotrophic environment associated with oxic/suboxic conditions at the bottom of the seawater for the studied interval. Low oxygen levels and mesotrophic conditions were seen to mark the Paleocene Eocene Thermal Maximum event, as evidenced by the organic-rich laminated sediment, low benthic foraminiferal indices, and the occurrence of agglutinated taxa Repmanina charoides and Ammobaculites spp., which reflects a major change in food supply. The obtained sequence stratigraphic framework shows that the depositional record of the studied area is significantly influenced by both the regional tectonics and eustatic sea level.

For the Wadi El Mayet, the metagabbro-granodiorite-tonalite intrusive complex (MIC) occupies the eastern sector of famous wadi Mubarak–Dabr complex which considered as the largest intrusion in the Egyptian Eastern Desert. The basement associations in the area include volcano-sedimentary rocks, metavolcanics, and ultramafics. The whole successions were intruded by MIC, and granites. The (MIC) comprises multifarious gabbroic varieties namely: olivine, pyroxene, hornblende, uralitized gabbros and rare amphibolites, while silicic portion includes tonalite and granodiorite. Microprobe analytical chemistry of gabbros and granites refers that: the amphiboles are calcic magnesio hornblende formed at low pressure conditions. Chlorites have corundophillite composition. Plagioclase range between labradorite, andesine and oligoclase. Biotite is mainly siderophylite. Muscovite minerals are mainly cheladonite. Geothermo-barometers calculations reveal crystallization temperatures of 550 °C and 860 °C for granites and metagabbros respectively. The (MIC) cover a wide silica range (44.5–74.5 wt %). It has transitional tholeiitic to calc-alkaline magmas. The gabbroic rocks show distinct fecundity with LILE (e.g. Rb, Ba, U and Th), but show observed shortage in most HFSE (e.g. Zr, Nb, Ta). The REE patterns show enrichment in light REE and posse variably positive Eu. It is suggested that, the gabbroic units were likely generated by fractional crystallization of mafic magmas produced through partial melting of metasomatized mantle within island-arc environments. Tonalite - granodiorite (TG) suite show calc-alkaline magmas of I-type settings. They also exhibit enrichment in Ba, Zr, Hf, Rb, U and Th, while P, Nb, Ta and Sr are depleted. Such reductions are harmonious with fractionation of K-feldspar phases. The (TG) show enrichment of (LREE) compare to (HREE) this proposes either the existence of persistent garnet or LREE fertile magma sources. The (TG) is believed to be formed through dehydration melting processes at lower crust settings. Based on the field, geochemistry and structure elements, the investigated mafic and silicic suites are not linked to a single magma origin. The (MIC) can be comparable with intrusions formed in ensialic island-arcs settings. At subduction zone integration between mantle (basaltic suites) and silicic magmas from lower crust forming the early stages of (MIC) crystallization. The whole association was suffered by insignificant fractionation processes and addition of crustal materials during the final stages of (MIC) emplacement.