Search Results (361)

While macroscopic stress significantly impacts the performance of metallic components, the underlying atom–electron coupling mechanisms governed by distinct crystal symmetries remain insufficiently understood. To address this gap, this work systematically investigates the structural and electronic evolution of representative metallic materials under applied stress. Experimentally, X-ray diffraction (XRD) revealed complex macroscopic residual stress distributions in cold rolled titanium alloy and silicon steel. Motivated by these engineering observations, first-principles density functional theory (DFT) calculations were conducted to uncover the underlying physical mechanisms. Specifically, the responses of face-centered cubic (FCC) aluminum and copper, body-centered cubic (BCC) iron, and hexagonal close-packed (HCP) titanium crystals were investigated under tension and compression using the RPBE functional. Stress-dependent elastic properties, density of states (DOS), band structures, and phonon spectra were calculated. Results show that tension softens all metals (Al becomes mechanically unstable), whereas compression stiffens their lattices. Electronically, tensile loading sharpens DOS peaks near the Fermi level and shifts conduction bands closer to it, whereas compression smooths DOS peaks and shifts bands away. Phonon analysis indicates Cu and Ti remain dynamically stable, while Al and Fe exhibit phonon mode softening under high tension. These stress-induced changes highlight crucial atom–electron coupling mechanisms, providing a theoretical basis for tailoring metallic performance via stress engineering. Full article

Cold-mercury gilding uses mercury as an adhesive to bond gold foil onto the surface of copper and silver artifacts. This technique and mercury gilding (fire gilding) both belong to the Au-Hg system and are closely related in technology. Clarifying the technical differences between them is of great significance for revealing the developmental sequence of ancient gilding technologies. On the basis of reconstructing traditional fire gilding, simulated cold-mercury-gilded samples were successfully prepared using experimental archeological methods, and multi-scale characterization was performed using SEM-EDS, XRD, and XPS. The results show that the surface of cold-mercury-gilded samples displays a micromorphology of folded and overlapped gold foil accompanied by locally dense particle aggregation. The cross-section of the gold layer exhibits a multilayer stacked structure, in which mercury is enriched at the gold layer/substrate interface and forms an AuHgCu/Ag diffusion layer. Room-temperature-stable Au-Hg and Ag-Hg phases such as Au₂Hg and AgHg are present in the gold layer, reflecting complex phase transformation behavior of the Au-Hg/Ag-Hg system at room temperature. During cold-mercury gilding, liquid mercury first adheres to the gold foil, and then interdiffusion and phase reactions occur between mercury, gold, and copper/silver atoms at room temperature. Intermetallic compounds and diffusion layers formed at the interface achieve firm bonding between the gold layer and the substrate. Both cold-mercury gilding and mercury gilding achieve metallurgical bonding through atomic interdiffusion. However, affected by differences in the initial state of mercury and operating temperature, the phase transformation and atomic diffusion behaviors of the system differ significantly, which are ultimately reflected in the cross-sectional structure of the gold layer, the composition of the interfacial diffusion layer, and the types of phases. Therefore, mercury-gilded artifacts show superior gold layer durability and bonding strength with the substrate compared with cold-mercury-gilded artifacts. Both techniques pioneered the application of mercury in metallic gilding and represent important innovations in ancient surface decoration technology. Full article

Cold-atom absolute gravimeters are widely used for measuring the acceleration of gravity, yet their sensitivity is often limited by ground vibrations. Existing vibration compensation algorithms struggle to strike a balance between search accuracy and computational efficiency and are prone to local optima. Here, we propose an improved whale optimization algorithm (IWOA) to address these issues. By combining Logistic-LHS (Latin hypercube sampling) chaotic initialization, adaptive adjustment, and a Gaussian mutation operator to prevent premature convergence, IWOA achieves higher search efficiency and superior sensitivity than traditional algorithms. The method is validated through multiple simulation studies and further assessed experimentally on the NIM-AGRb-1 cold-atom gravimeter system. The results show that IWOA reduces the uncertainty of the fitted phase parameter by 66%. The Pearson correlation between atomic transition probability and the calculated phase increases to a maximum of 0.98, and the gravity sensitivity improves to 47 $\mathrm{\mu }\mathrm{Gal}/\sqrt{\mathrm{Hz}}$ when the evolution time T is 80 ms. Full article

We develop a method for calculating multichannel wavefunctions in the spirit of quantum defect theory, based on numerically calculated reference functions. We benchmark the method by calculating cold collisional properties of ⁸⁵Rb and ⁶Li in the presence of external magnetic fields tuned across specific s-wave Feshbach resonances and thereby reproducing known results. We then apply the method to calculate experimentally observed d-wave Feshbach resonance in ⁸⁷Rb-⁸⁵Rb cold collisions. Our numerical results for this d-wave resonance show good agreement with the experimental observations. The method is applicable to arbitrary interaction potentials and to any energy range near the scattering threshold. The implementation of our method to any multichannel two-body scattering problem is straightforward. Full article

The fabrication of NiTiZr alloys by solid-state routes remains challenging due to limited atomic diffusion and the high reactivity of Ti and Zr. Mechanical alloying offers a potential pathway for synthesising such systems; however, complete alloy formation is not always achieved under practical milling conditions. Researchers have infrequently explored the mechanical alloying of NiTiZr, and this study systematically investigates the effect of milling time on microstructural evolution rather than claiming complete alloy synthesis. A high-energy planetary ball mill was used to mechanically process elemental powders of Ni, Ti, and Zr for 5–28 h. The examination revealed that longer milling times resulted in progressive crystallite refinement and increased lattice strain, while particle morphology evolved from irregular to more globular shapes due to repeated fracture and cold welding. After 28 h of milling, limited reacted regions containing Ni, Ti, and Zr were observed (~4.6% area fraction), while most of the powder remained heterogeneous and polyphasic, with no evidence of complete Ni₅₀Ti₃₀Zr₂₀ alloy formation. X-ray diffraction showed significant peak broadening without systematic 2θ peak shifts, indicating severe plastic deformation and crystallite refinement rather than definitive solid-solution formation of the allot. Differential scanning calorimetry revealed exothermic thermal events between 300 °C and 470 °C, which are attributed to defect recovery and thermally activated structural rearrangements rather than confirmed martensitic or crystallisation transformations. These results demonstrate that high-energy ball milling alone is effective for particle size reduction and defect generation but insufficient for producing a fully homogeneous Ni₅₀Ti₃₀Zr₂₀ alloy within 28 h. Additional activation energy, such as post-milling heat treatment or extended processing, is required to promote complete alloying in this system. Full article

Potassium superoxide (KO₂) can form during the oxidation of residual potassium in NaK-contaminated cold traps of sodium-cooled fast reactors. Its strong oxidizing nature, combined with limited thermal stability, raises safety concerns during shutdown and maintenance. Here, we integrate first-principles calculations with experiments to clarify the facet stability, temperature-driven surface evolution, and stepwise thermal decomposition of KO₂. Guided by the tetragonal I4/mmm crystal symmetry of bulk KO₂, symmetry-non-equivalent low-index facets and relevant surface terminations were systematically evaluated to identify physically meaningful exposed surfaces. Ab initio molecular dynamics (AIMD) simulations further show that heating induces progressive surface amorphization and enhanced oxygen mobility, accompanied by the emergence of shortened O-O bonds and outward migration of oxygen species. Kinetic analysis using the climbing-image nudged elastic band (CI-NEB) method indicates that oxygen evolution is preferentially mediated by O₂ release rather than atomic oxygen escape. Differential scanning calorimetry (DSC) reveals two endothermic events consistent with sequential decomposition, while X-ray diffraction (XRD) confirms the transformation of KO₂ into K₂O. Collectively, these results provide an atomistic-to-macroscopic understanding of KO₂ decomposition, offering practical guidance for defining safer preheating windows and handling strategies for NaK-contaminated components. Full article

Arsenic (As) and mercury (Hg) are trace elements of major environmental and public health concern. Their relevance is due to their well-documented toxicological effects. In rapidly urbanizing port-industrial cities, soil contamination by these elements represents a critical challenge. This situation compromises sustainable urban development and environmental governance. This study had three main objectives: First, to evaluate the contamination status of As and Hg in urban soils using multiple geochemical indices; Second, to assess the potential human health risks associated with exposure in the urban environment of Talcahuano; Third, to identify the relative contributions of geogenic and anthropogenic sources based on spatial distribution patterns. A total of 420 soil samples were collected. These included 140 topsoil samples (TS; 0–10 cm), 140 subsoil samples (SS; 10–20 cm), and 140 deep-soil samples (DS; 150 cm). Arsenic concentrations were determined using hydride-generation atomic absorption spectrometry (HG-AAS). Mercury concentrations were measured by cold-vapour atomic absorption spectrometry (CV-AAS). Median As concentrations were 2.7 mg kg⁻¹ in TS, 3.1 mg kg⁻¹ in SS, and 2.5 mg kg⁻¹ in DS. The corresponding median Hg concentrations were 0.2 mg kg⁻¹ in TS and 1.4 mg kg⁻¹ in both SS and DS. Spatial distribution maps were generated through ordinary kriging interpolation. Geochemical baseline values were calculated using the median + 2 × MAD approach. The resulting baseline values were 7.8 mg kg⁻¹ for As and 3.6 mg kg⁻¹ for Hg. Contamination assessment was conducted using the geoaccumulation index (Igeo), enrichment factor (EF), and contamination factor (Cf). Results indicate that most soils are classified as uncontaminated. Enrichment levels were minimal and contamination factors were low. Nevertheless, isolated outliers were identified. These included one significantly enriched As sample and several moderately enriched or slightly contaminated Hg samples. Human health risk assessment incorporated the Hazard Index (HI) and Total Carcinogenic Risk (TCR). Results indicate that neither non-carcinogenic nor carcinogenic risks exceed acceptable thresholds at any investigated soil depth. Spatial analysis suggests that anthropogenic activities are the dominant sources of As and Hg in the study area. Traffic emissions and industrial activities appear to be the primary contributors. Full article

Quantum cold-atom sensors provide precise measurements of gravitational acceleration and gravity gradients. By matching these measurements to a high-resolution gravity database, a moving platform can derive its position using map-matching techniques that fuse gradient observations with inertial navigation. One such fusion technique, particle filters, is dominated by the cost of evaluating gravity gradients via surface integrals at each location. To overcome this overhead, we introduce a deep-learning model that predicts the vertical gravity gradient from a compact subset of local gravity anomaly samples, eliminating the need for full integral computations. We integrate this deep neural network into the map-matching framework, benchmark its accuracy against conventional methods, and demonstrate its real-time performance within a simulated inertial navigation system driven by a quantum sensor model. Full article

The limited ductility of the VW63K rare-earth magnesium alloy fabricated via cold metal transfer wire arc additive manufacturing (CMT-WAAM) was targeted in this work. An integrated approach that combines first-principles calculations with experimental characterization was employed to achieve this goal. This approach was used to systematically investigate how Ag doping alters the microstructure and mechanical properties of the alloy. First-principles calculations performed on the primary precipitate phase Mg₂₄(Gd,Y)₅ demonstrated that Ag atoms preferentially occupy the Mg lattice sites and form pronounced orbital hybridization with neighboring rare-earth atoms. These interactions were found to enhance critical mechanical parameters, including the Cauchy pressure, B/G ratio, and Poisson’s ratio, which are indicative of enhanced ductility and toughness of the phase. Experimental results indicate that the fracture strain of the VW63K-Ag alloy was increased from approximately 4% to above 12% following Ag doping. This resulted in a significant improvement in ductility. The ultimate tensile strength (UTS) underwent only a moderate reduction. Using a closed-loop approach integrating theoretical prediction and experimental validation, the microstructural modification and strengthening mechanisms of Ag in the VW63K alloy fabricated via CMT-WAAM were clarified. These findings offer a theoretical foundation and experimental evidence for compositional design and optimizing additive manufacturing (AM) processes for rare-earth magnesium alloys. Full article

The first hydrogenation behavior of the gas atomized Ti_48.8Fe_46.0Mn_5.2 alloy was systemically investigated. The as-received powder showed no hydrogen absorption due to the long air exposure before the hydrogenation tests. To overcome this, 5 passes of cold rolling were employed as an activation strategy. Cold rolling introduced cracks and defects that facilitated hydrogen diffusion, enabling the alloy to successfully absorb hydrogen. The influences of temperature, constant driving force, and hydrogen pressure on the first hydrogenation were evaluated. The results indicated that the first hydrogenation follows an Arrhenius behavior ($\mathrm{k}=\mathrm{A}{\mathrm{e}}^{-{\displaystyle \frac{{\mathrm{E}}_{\mathrm{a}}}{\mathrm{R}\mathrm{T}}}}$), and average activation energy was calculated as 71 kJ/mol H₂. The pre-exponential factor (A) was found to be pressure-dependent, following the equation A = A₀ (P/P₀)^1.8, where A₀ = 2.6 × 10⁶ s⁻¹. Full article

Green cosmetics are primarily based on plant-derived ingredients and use sustainable biotechnological tools for their preparation. The present research aimed to investigate the Usnea barbata (U. barbata) extract in Jojoba oil (JO) enriched with 5% Peppermint oil (PEO) and 10% Vitamin E, as a potential natural product for skin applications. The U. barbata oil extract (UBPJO) was obtained through cold maceration. Phytochemical screening was performed using Gas Chromatography/Mass Spectrometry (GC-MS), Folin–Ciocalteu method, and Graphite-Furnace Atomic Absorption Spectrophotometry (GFAAS). Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM) were used to evaluate the physicochemical properties. Then, rheological characteristics and oxidation stability (measured as the time to reach the oxidation starting point, induction period (IP)) of both oil samples (UBPJO and oil mixture alone (PJO) were investigated. Total phenolic content (TPC) in UBPJO was 2.5 times higher than in PJO (p < 0.05), while heavy metal levels (As and Pb) were slightly higher (p > 0.05). UBPJO has higher shear stress, viscosity, and spreadability than PJO, but the differences are not significant (p > 0.05). Finally, IP measurements indicated appreciable oxidative stability (UBPJO vs. PJO: 153.02 h vs. 137.35 h, p > 0.05). The phytochemical composition and physicochemical properties support the inclusion of UBPJO in various skincare formulations. Full article

Heavy metal pollution in mining wastelands poses a serious threat to soil quality and ecosystem sustainability, particularly in cold-climate regions where phytoremediation efficiency remains poorly understood. The present study aims to determine the risk of heavy metals in soils and the phytoremediation potential of native dominant spontaneous plants in lead–zinc mining wasteland and located in a cold region characterized by harsh winters and heavy snowfall. Soil samples (n = 60) and plant tissues (n = 84) were collected across the study area, and the concentrations of Cd, Pb, Zn, and Cu in rhizosphere soils and plant tissues were determined using atomic absorption spectrophotometry. Bioconcentration and translocation factors were calculated to evaluate plant metal enrichment and transport capacities. The results revealed that the concentrations of Cd, Pb, Zn, and Cu were at a relatively high potential ecological hazard level in the tailing ponds and surrounding areas. Field surveys showed that indigenous dominant spontaneous plants were better adapted to the harsh climatic conditions and poor soil matters than non-native plants, making them more economical and reliable candidates for phytoremediation. The study unexpectedly identified Commelina communis as a Cu phytostabilization candidate and found several metal-enriching plant species (n = 6), including Scirpus, Typha, Carex, Artemisia, Commelina, and Polygonum. The results can serve as a basic plant resource database for government institutions related to natural, ecological, and environmental sustainable management, offering new insights into self-sustaining phytoremediation strategies and sustainable ecological restoration in cold-region mining areas. Full article

The quality of the feedstock powder plays a key role in determining the properties of coatings produced by cold spray (CS). However, most commercially available powders are not specifically designed for CS, which makes it difficult to tailor powder characteristics for optimal performance. In this study, we examined the cold sprayability of five copper (Cu) powders manufactured using electrolysis, gas atomization, and mechanical grinding. The powders were characterized in terms of their microstructure, particle shape, and size distribution to evaluate how the production method influences powder properties. Powder flowability was measured using a shear cell test, while mechanical properties and deformability relevant to CS were assessed through nano-indentation. The results showed that gas-atomized powders with equiaxed grain structures offered the best combination of flowability and deformability, making them the most suitable for CS. Their spherical particle shape resulted in a lower surface area compared to the irregular electrolytic powder, which reduced inter-particle surface forces and allowed for smoother powder flow. Nano-indentation measurements indicated that the mechanically ground powder with ultra-fine grains and the gas-atomized powder containing fine dendrites had the highest nano-hardness values (HIT = 2.1 ± 0.15 GPa and 1.6 ± 0.1 GPa, respectively). In contrast, the porous electrolytic Cu powder showed the lowest hardness (HIT = 0.7 ± 0.2 GPa). These trends were confirmed by microstructural analysis of the deposited coatings. Coatings produced from the irregular electrolytic powder exhibited limited particle deformation, weak inter-particle bonding, and the highest porosity. Conversely, spherical gas-atomized powders produced much denser coatings. In particular, the powder with the most uniform spherical shape and no microsatellite particles resulted in the lowest coating porosity due to its superior deformation behavior upon impact. Full article

Phosphate coatings were obtained by cold method from solutions based on Mazev Salt (containing Mn(H₂PO₄)₂∙2H₂O and iron phosphates). Metal nitrates and nitrites were introduced into solutions as accelerators of the phosphating process. To obtain green and blue phosphate coatings, procyon olive green and methylene blue dyes (8 g/L) were added into the solutions. Colored phosphate coatings are deposited unevenly on the steel surface. The thickness of the modified phosphate films was estimated from SEM images of the cross-section samples and determined to be 3–4 microns. Colored phosphate coatings are fine-grained with a grain size of 170–190 nm, which was determined using an atomic force microscope. Phosphate films continue to exhibit protective properties when heated to 100 °C. With a further increase in temperature, the protective ability of the film is significantly reduced. Colored phosphate films have a low coefficient of friction (0.1–0.15). The breakdown voltage of colored phosphate coatings is 180–200 V, which characterizes low electrical insulation ability. Based on the established properties, colored phosphate coatings can be used as protective and decorative. Full article

In the rubidium-87 atomic fountain clock, the laser collimating and beam-expanding telescope plays a key role in atomic cooling and manipulation, as well as in realizing the cold-atom fountain. To address the bulkiness of conventional laser collimating and beam-expanding telescopes, which limits system integration and miniaturization, we design and implement a compact laser collimating and beam-expanding telescope. The design employs a Galilean beam-expanding optical path to shorten the optical path length. Combined with optical modeling and optimization, this approach reduces the mechanical length of the telescope by approximately 50%. We present the mechanical structure of a five-degree-of-freedom (5-DOF) adjustment mechanism for the light source and the associated optical elements and specify the corresponding tolerance ranges to ensure their precise alignment and mounting. Based on this 5-DOF adjustment mechanism, we further propose a method for tuning the output beam characteristics, enabling precise and reproducible control of the emitted beam. The experimental results demonstrate that, after adjustment, the divergence angle of the output beam is better than 0.25 mrad, the coaxiality is better than 0.3 mrad, the centroid offset relative to the mechanical axis is less than 0.1 mm, and the output beam diameter is approximately 35 mm. Furthermore, long-term monitoring over 45 days verified the system’s robustness, maintaining fractional power fluctuations within ±1.2% without manual realignment. Compared with the original telescope, all of these beam characteristics are significantly improved. The proposed telescope therefore has broad application prospects in integrated atomic fountain clocks, atomic gravimeters, and cold-atom interferometric gyroscopes. Full article