Search Results (27,465)

Mineralogy 4.0 can play a significant role in the future of geological research, education, and exploration by providing a more comprehensive and interactive understanding of rocks and minerals. This paper explores the application of digital photogrammetry and augmented reality (AR) technologies as part of Mineralogy 4.0. An atlas of 3D rocks and minerals with 915 high-quality models was created to showcase the potential of photogrammetry in the mineral sciences. The repository contains a wide range of sample types, featuring transparency, metallic luster, fluorescence, or millimetric-scale crystals. The three-dimensional rocks and minerals can also be accessed on-the-go through a mobile application that was developed for Android devices. Additionally, web applications have been developed with specific three-dimensional collections as well as three-dimensional storytelling. AR technology was also integrated into the 3D repository, allowing users to superimpose virtual 3D models of rocks and minerals onto real-world surfaces through their device’s camera. Also, a digital solution with 3D holograms of rocks and minerals was effectively implemented to provide an interactive and immersive experience. The 3D datasets of rocks and minerals can play a significant role in the geoscience community’s research, developing not only in-depth knowledge of specimens but also opening new frontiers in mineral sciences, leading towards a more advanced era of mineralogy. Full article

The electromagnetic railgun, a novel kinetic energy weapon, has found utility in military operations due to its enhanced safety features and superior precision. This study investigates the enhancement of wear resistance in CuCrZr rails through the plasma cladding of CuCrZr-CeO₂ coatings with a varying Cerium dioxide (CeO₂) content. To enhance the wear resistance of the CuCrZr track, plasma cladding of CuCrZr-CeO₂ coatings with varying CeO₂ content was investigated. The impact of CeO₂ content (0%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%) on the microstructure, phase composition, and mechanical properties of the CuCrZr coating was assessed using scanning electron microscopy (SEM), X-ray diffraction (XRD), EDS(Energy Dispersive Spectrometer) surface scanning, friction and wear tests, and hardness analysis. The findings indicate that a CeO₂ content of 0.15% leads to a transition in the coating’s microstructure from columnar to equiaxed crystals, with the densest grain structure. Beyond 0.15% CeO₂, pore defects in the coating increase, compromising mechanical properties. The coating containing 0.15% CeO₂ exhibits optimal performance, with a hardness of 75.3, representing a 5.31% increase compared to CeO₂-free CuCrZr coatings. Under a 10 N load, the friction coefficient decreases by approximately 17.9% to about 0.64. Moreover, the minimum wear mass is reduced by 44.7% to 3.87 mg. The aforementioned research findings hold immense importance in extending the lifespan of the electromagnetic railgun and improving its operational efficiency. Full article

The Kalatag mineralization belt is an important metallogenic belt of polymetallic mineral deposits in the northern part of eastern Tianshan, and its age and tectonic setting are still controversial. We identified a set of Devonian volcanic rocks hosted in the Early Palaeozoic package of dominantly marine sediments with a small amount of terrestrial rocks. This study presents petrological, U–Pb geochronology, and geochemical data for the volcanic rocks. The ages of the rhyolite (407.2 ± 1.9 Ma) and basaltic andesite (380.4 ± 2.8 Ma) suggests that the Kalatag belt is a Devonian volcanic succession. These rocks consist mainly of marine calc–alkaline lava, tuff, pyroclastic rocks, and minor terrestrial basaltic andesite. The lavas are characterized by the enrichment of light rare earth elements and strongly depleted in Nb and Ta, typical of island arc magmatic rocks. The volcanic rocks probably originated from the partial melting of the mafic lower crust which was modified by subducted slab-related fluids. During their ascent through the crust, these volcanic rocks underwent variable extents of fractional crystallization (rhyolites) and crustal contamination (basaltic andesites). Combined with the results of previous studies, we suggest that the Devonian rocks formed in an island arc related to the northward subduction of the Northern Tianshan Ocean with a crustal thickness of ~35–40 km. Full article

In search of opportunities to improve mechanical properties and abrasion resistance, composites based on aluminum reinforced with MoS₂ particles were produced. The authors’ previous research indicated the possibility of obtaining hard dispersion precipitates of the Al₁₂Mo intermetallic phase as a result of the reaction of the composite components at a temperature exceeding 550 °C during the SPS (Spark Plasma Sintering) process. This work focused on optimizing the SPS consolidation process and assessing the microstructure and mechanical properties of the obtained materials. A series of experiments proved that by increasing the amount of the strengthening phase and increasing the process temperature, a significant amount of Al₁₂Mo and Al₅Mo strengthening phases is produced. Exceptionally good dispersion of reinforcing particles and the presence of layered MoS₂ crystals, while ensuring optimal parameters of the synthesis process, lead to a change in friction mechanisms and improved abrasion resistance through an approximately 30-fold decrease in the wear factor. Full article

Naphthalene is a fungicide that can also be a phase-change agent owing to its high crystallization enthalpy at about 80 °C. The relatively rapid evaporation of naphthalene as a fungicide and its shape instability after melting are problems solved in this work by its placement into a cured epoxy matrix. The work’s research materials included diglycidyl ether of bisphenol A as an epoxy resin, 4,4′-diaminodiphenyl sulfone as its hardener, and naphthalene as a phase-change agent or a fungicide. Their miscibility was investigated by laser interferometry, the rheological properties of their blends before and during the curing by rotational rheometry, the thermophysical features of the curing process and the resulting phase-change materials by differential scanning calorimetry, and the blends’ morphologies by transmission optical and scanning electron microscopies. Naphthalene and epoxy resin were miscible when heated above 80 °C. This fact allowed obtaining highly concentrated mixtures containing up to 60% naphthalene by high-temperature homogeneous curing with 4,4′-diaminodiphenyl sulfone. The initial solubility of naphthalene was only 19% in uncured epoxy resin but increased strongly upon heating, reducing the viscosity of the reaction mixture, delaying its gelation, and slowing cross-linking. At 20–40% mass fraction of naphthalene, it almost entirely retained its dissolved state after cross-linking as a metastable solution, causing plasticization of the cured epoxy polymer and lowering its glass transition temperature. At 60% naphthalene, about half dissolved within the cured polymer, while the other half formed coarse particles capable of crystallization and thermal energy storage. In summary, the resulting phase-change material stored 42.6 J/g of thermal energy within 62–90 °C and had a glass transition temperature of 46.4 °C at a maximum naphthalene mass fraction of 60% within the epoxy matrix. Full article

This article presents new research on the surface condition of bulk crystal samples after the following stages of surface treatment: grinding, polishing, and etching. Furthermore, it shows how the surface condition affects the photothermal signal’s spectral amplitude and phase characteristics (PZE). A new theoretical interpretation of the photothermal spectra of CdTe samples after different surface treatments is proposed. We demonstrate that the piezoelectric method is susceptible to the surface condition, and it allows for the estimation of the thickness of surface-damaged layers of samples, and for the analysis of their thermal parameters. The roughness of surfaces obtained from the AFM pictures is estimated and compared to the photothermal results. Full article

Studies of micro/nanoscale mechanical properties of materials are scarce and the determination of the corresponding parameters such as fracture toughness (K_IC) and Vickers hardness number (HV) at those scales remains a challenge. In the presented work, a methodological approach was applied that provides detailed insight on the elastic/plastic behavior of minerals subjected to Vickers indentation experiments. In this research, five samples were analyzed: one fused silica sample (reference material), two synthetic quartz crystals (differently cut, SQ_⊥ and SQ_X), and two quartz grains from polished sections of granite and granodiorite rock. The applied methodology was predominantly based on qualitative and quantitative morphology measurements by Atomic Force Microscopy (AFM). This analysis shows the dominant presence of either Primary Radial Cracks (PRC) or Secondary Radial Cracks (SRC) in both natural (mineral) quartz grains and synthetic quartz crystals, and Cone Cracks (CC) in fused silica. Moreover, the parameters associated with the indentation (e.g., length of the cracks, the depth of residual indentation, and the indentation mark size) allowed the reconstruction of the indentation profile model and the determination of K_IC and HV with enhanced accuracy. Full article

Injecting carbon dioxide (CO₂) into subsea water zones, where the in situ temperatures are below the hydrate-forming temperature of CO₂, has been recently proposed to lock CO₂ inside the water zones in a solid hydrate form. It is a common concern that CO₂ may form hydrates during the injection period, which would reduce well injectivity. CO₂ injection into sandstone cores under simulated subsea temperatures ranging from 0 °C to 5 °C was investigated in this study. Experimental results show that flowing CO₂ at Darcy velocity 0.033 cm/s begins to form hydrate in the sandstone core at dynamic pressures higher than the minimum required pressure under static conditions. At temperatures changing from 0 °C to 5 °C, the observed hydrate-forming pressure changes from 1.87 to 2.5 times the pressures required for CO₂ hydrates under static conditions. The reason why the required minimum pressure for CO₂ to form hydrates in dynamic conditions is higher than that in static conditions is attributed to the shear rate effect of flowing fluids that should slow down the growth of hydrate crystals and/or break down formed hydrate films in the dynamic conditions. Therefore, higher pressure energy, or fugacity, is required to promote the growth of hydrate crystals and hydrate films in dynamic conditions. More rigorous investigations in this area are needed in the future. Full article

As quantum computing advances, current cryptographic protocols are increasingly vulnerable to quantum attacks, particularly those based on Public Key Infrastructure (PKI) like RSA or Elliptic Curve Cryptography (ECC). This paper presents a comprehensive review of Post-Quantum Cryptography (PQC) as a solution to protect digital systems in the quantum era. We provide an in-depth analysis of various quantum-resistant cryptographic algorithms, including lattice-based, code-based, hash-based, isogeny-based, and multivariate approaches. The review highlights the National Institute of Standards and Technology (NIST) PQC standardization process, highlighting key algorithms, such as CRYSTALS–Kyber, CRYSTALS–Dilithium, Falcon, and SPHINCS+, and discusses the strengths, vulnerabilities, and implementation challenges of the leading algorithms. In addition, we explore transition strategies for organizations, emphasizing hybrid cryptography to ensure backward compatibility during migration. This study offers key insights into the future of cryptographic standards and the critical steps necessary to prepare for the transition from classical to quantum-resistant systems. Full article

Biosensors operating in the terahertz (THz) region are gaining substantial interest in biomedical analysis due to their significant potential for high-sensitivity trace-amount solution detection. However, progress in compact, high-sensitivity chips and methods for simple, rapid and trace-level measurements is limited by the spatial resolution of THz waves and their strong absorption in polar solvents. In this work, a compact nonlinear optical crystal (NLOC)-based reflective THz biosensor with a few arrays of asymmetrical meta-atoms was developed. A near-field point THz source was locally generated at a femtosecond-laser-irradiation spot via optical rectification, exciting only the single central meta-atom, thereby inducing Fano resonance. The reflective resonance response demonstrated dependence on several aspects, including structure asymmetricity, geometrical size, excitation point position, thickness and array-period arrangement. DNA samples were examined using 1 μL applied to an effective sensing area of 0.234 mm² (484 μm × 484 μm) for performance evaluation. The developed Fano resonance sensor exhibited nearly double sensitivity compared to that of symmetrical sensors and one-gap split ring resonators. Thus, this study advances liquid-based sensing by enabling easy, rapid and trace-level measurements while also driving the development of compact and highly sensitive THz sensors for biological samples. Full article

Urbanization growth has intensified the challenge of managing and treating increasing amounts of municipal solid waste (MSW). Landfills are commonly utilized for MSW disposal because of their low construction and operation costs. However, this practice produces huge volumes of landfill leachate, a highly polluting liquid rich in ammoniacal nitrogen (NH₃-N), organic compounds, and various heavy metals, making it difficult to treat in conventional municipal wastewater treatment plants (WWTPs). In recent years, research has shown that microbial biofilms, developed on carriers of different materials and called “moving bed biofilm reactors” (MBBRs), may offer promising solutions for bioremediation. This study explored the biofilm development and the nitrification process of moving bed biofilms (MBBs) obtained from high ammonia-selected microbial communities. Using crystal violet staining and confocal laser-scanning microscopy, we followed the biofilm formation stages correlating nitrogen removal to metagenomic analyses. Our results indicate that MBBs unveiled a 10-fold more enhanced nitrification rate than the dispersed microbial community present in the native sludge of the Porto Sant’Elpidio (Italy) WWTP. Four bacterial families, Chitinophagaceae, Comamonadaceae, Sphingomonadaceae, and Nitrosomonadaceae, accumulate in structured biofilms and significantly contribute to the high ammonium removal rate of 80% in 24 h as estimated in leachate-containing wastewaters. Full article

Thin (~50 nm thick) BaM hexaferrite (BaFe₁₂O₁₉) films were grown on (1–102) and (0001) cut α-Al₂O₃ (sapphire) substrates via laser molecular beam epitaxy using a one- or two-stage growth protocol. The advantages of a two-stage protocol are shown. The surface morphology, structural and magnetic properties of films were studied using atomic force microscopy, reflected high-energy electron diffraction, three-dimensional X-ray diffraction reciprocal space mapping, powder X-ray diffraction, magneto-optical, and magnetometric methods. Annealed BaFe₁₂O₁₉/Al₂O₃ (1–102) structures consist of close-packed islands epitaxially bonded to the substrate. The hexagonal crystallographic axis and the easy axis (EA) of the magnetization of the films are deflected from the normal to the film by an angle of φ~60°. The films exhibit magnetic hysteresis loops for both in-plane H_in-plane and out-of-plane H_out-of-plane magnetic fields. The shape of M_out-of-plane(H_in-plane) and M_in-plane(H_in-plane) hysteresis loops strongly depends on the azimuth θ of the H_{in plane}, confirming the tilted orientation of the EA. The M_out-of-plane(H_out-of-plane) magnetization curves are caused by the reversible rotation of magnetization and irreversible magnetization jumps associated with the appearance and motion of domain walls. In the absence of a magnetic field, the magnetization is oriented at an angle close to φ. Full article

This study aims to develop a reference material that enables precise management of dopant distribution in power semiconductors. We thoroughly investigate the structural and surface properties of 4H-silicon carbide (4H-SiC) single crystals implanted without annealing using aluminum (Al) and phosphorus (P) ions. Ion-implanted 4H-SiC was thoroughly evaluated using advanced techniques, including X-ray diffraction (XRD), field emission transmission electron microscopy (FE-TEM), atomic force microscopy (AFM), time of flight medium energy ion scattering (ToF-MEIS), and secondary ion mass spectrometry (SIMS). The evaluated results indicate that, without post-annealing, ion-implanted 4H-SiC can serve as an effective reference material for the precise control of trace elements and the quantitative monitoring of dopant distribution in power semiconductor applications. Full article

A T-shaped photonic crystal waveguide was designed with square lattice tellurium photonic crystals. A diamond-shaped ferrite pillar array was inserted in the junction of the waveguide to make a novel terahertz polarization splitter. Both transverse electric and transverse magnetic modes were numerically investigated by the plane wave expansion method, which used complete photonic band gaps covering from 0.138 THz to 0.144 THz. In this frequency domain of the fully polarized band gaps, the transmission efficiency of the photonic crystal waveguide was up to −0.21 dB and −1.67 dB for the transverse electric and transverse magnetic modes, respectively. Under the action of a DC magnetic field, the THz waves were rotated 90 degrees by the diamond-shaped ferrite pillar array. Transverse electric waves or transverse magnetic waves can be separated by a polarization isolator (six smaller tellurium rods) from the fixed waves. The characteristics of the designed polarization splitter were analyzed by the finite element method, and its transmission efficiency was optimized to 95 percent by fine-tuning the radii of the thirteen ferrite pillars. A future integrated communication network of sky–earth–space will require fully polarized devices in the millimeter and terahertz wavebands. The envisaged polarization splitter has a unique function and provides a promising method for the realization of fully polarized 6G devices. Full article

In this study, we innovatively proposed a facile method to synthesize ultrafine porous copper (Cu) powders under mild conditions by utilizing the reduction properties of reduced iron (Fe) powders. The results showed that Cu²⁺ was easily reduced to Cu at 1.05–1.1 times the theoretical iron powder content for a reaction time of 10~20 min at 20~25 °C. The obtained Cu powders with an average diameter of 10.2 μm did not show significant differences in crystal structure and purity compared to the commercial Cu powders with an average diameter of 6.6 μm, but the prepared Cu powders showed a loose and porous structure, which demonstrates their higher potential in catalyzing energetic materials. The ultrafine porous Cu powder resulted in a significant decrease in the high decomposition temperature of ammonium perchlorate (AP) from 441.3 °C to 364.2 °C at only 1% of the dosage, and also slightly advanced its low decomposition temperature, which confirmed its remarkable catalytic activity in the field of energetic materials. These meaningful results will provide a new method for the preparation of Cu powders and promote the development of the chemical reduction method for the preparation of ultrafine porous Cu powders, which is expected to promote the application of ultrafine porous Cu powders in the field of energetic materials catalysis. Full article