Search Results (599)

Background/Objectives: Exercise is essential for older adults to maintain or improve their physical condition. This study aimed to investigate whether improvements in physical performance, functional mobility, and balance through targeted physical function exercises could positively influence Concerns about Falling (CaF) and frailty in pre-frail community-dwelling older adults. Methods: We conducted an 18-month randomized controlled trial involving 112 pre-frail community-dwelling older adults aged 65 years or older. 55 individuals in the control group (CG) and 57 in the intervention group (IG) were assessed. The IG participated in a home-based physical function exercise program. Primary outcomes included Physical Performance (Short Physical Performance Battery, SPPB), Functional Mobility (Timed Up and Go, TUG), Balance (Berg Balance Scale, BBS), CaF (Falls Efficacy Scale–International, FES-I), and Frailty status (SHARE-FI). Assessments were conducted at baseline, 6, 12, and 18 months. Results: The IG showed significant improvements in BBS (p < 0.01, partial eta² 0.17), SPPB (p < 0.01, partial eta² 0.13), TUG (p < 0.01, partial eta² 0.14) and FES-I (p < 0.01, partial eta² 0.07) compared to the CG and their baseline after 6, 12 and 18 months of intervention. By 18 months, frailty status improved in the IG, with 12.3% classified as non-frail compared to 2.0% in the CG, while 14.5% of the CG transitioned to frailty versus none in the IG. Discussion: The intervention appears to support improvements in physical function and may contribute to reductions in CaF and beneficial changes in frailty status among pre-frail community-dwelling older adults. Full article

With the increasing severity of cadmium (Cd) contamination in soil and its persistent toxicity, developing efficient remediation methods has become a critical necessity. In this study, sodium borohydride (NaBH₄) and tea polyphenols (TP) were employed as reducing agents to synthesize biochar (BC)-supported nanoscale zero-valent iron (nZVI), denoted as BH₄-nZVI/BC and TP-nZVI/BC, respectively. The effects of dosage, pH, and reaction time on Cd immobilization efficiency were systematically investigated. Both composites effectively stabilized Cd, significantly reducing its mobility and toxicity. Toxicity Characteristic Leaching Procedure (TCLP) results showed that Cd leaching concentrations decreased to 8.23 mg/L for BH₄-nZVI/BC and 4.65 mg/L for TP-nZVI/BC, corresponding to performance improvements of 29.9% and 60.5%. The immobilization process was attributed to the reduction of Cd(II) into less toxic species, together with adsorption and complexation with oxygen-containing groups (-OH, -COOH, phenolic) on biochar. TP-nZVI/BC exhibited superior long-term stability, while maintaining slightly lower efficiency than BH₄-nZVI/BC under certain conditions. Microbial community analysis revealed minimal ecological disturbance, and TP-nZVI/BC even promoted microbial diversity recovery. Mechanistic analyses further indicated that tea polyphenols formed a protective layer on nZVI, which inhibited particle agglomeration and oxidation, reduced the formation of iron oxides, preserved Fe⁰ activity, and enhanced microbial compatibility. In addition, the hydroxyl and phenolic groups of tea polyphenols contributed directly to Cd(II) complexation, reinforcing long-term immobilization. Therefore, TP-nZVI/BC is demonstrated to be an efficient, sustainable, and environmentally friendly amendment for Cd-contaminated soil remediation, combining effective immobilization with advantages in stability, ecological compatibility, and long-term effectiveness. Full article

The demand for high energy density in mobile devices (including vehicles and small ships) is increasing. Nickel–Manganese–Cobalt (NMC) ternary, as a battery cathode material, is increasingly being applied because of its higher energy density relative to LiFePO₄ or other traditional materials. But NMC also faces challenges, such as a high degeneration rate and heat generation. So these aspects of Ni content must be clarified. In the current study, two Ni-content battery cells were tested, and the results of other composition cathode cells from the literature were compared. And three typical Ni-content batteries were simulated for searching Ni effects on performance, capacity fade and heat generation. Some findings were achieved: (1) from 0.8 Ni content, it can be seen that the specific capacity growth rate (slope) was much greater than before; (2) cathode materials that have an odd number (that does not surpass 0.7) of Ni content showed a linear capacity degradation trend, but others did not; (3) the Li concentration within material particles did not correspond to absolute stress value but stress temporal gradient; and (4) during discharge, lower Ni content made the heat peak occur earlier but lowered the absolute value; the irreversible heat increased with Ni content non-linearly, so that the higher the Ni content went up, the higher the increase rate of the irreversible heat ratio. Thus, the results of this study can guide the design and application of high energy batteries for mobile devices. Full article

Ore mining and smelting are often related to environmental pollution. This study provides information about the geochemical features of Technosols at historical mining and metallurgical sites in the Tatra Mountains, southern Poland, evaluating the contents of potentially toxic trace elements (PTTE) and their behaviours in soils, as well as the influence of soil properties on PTTE mobility. Thirteen soil profiles were studied in eight abandoned mining and smelting sites. PTTE concentrations, including rare earth elements (REE), were measured using ICP-MS and ICP-OES. Selected elements (Cu, Zn, Pb, Cd, As, Sb, Ba, Sr, Co, Ni, Mn and Cr) were fractionated using the modified European Community Bureau of Reference (BCR) four-step sequential extraction. Contamination of soils with PTTE was compared against Polish regulatory limits, which were exceeded for Cu, Zn, Pb, Mo, Hg, As, Co, Ni and Ba, with concentrations exceeding limits by 16, 18, 34 and 160 times for Cu, Hg, As and Ba, respectively, in some profiles. Based on geochemical features depending on parent material properties, the soils examined were divided into three groups. Group I Technosols (near-neutral soils developed from Fe/Mn-ore and carbonate-bearing mining waste) were particularly enriched in Co, Ni, Mn and REE. Group II Technosols (acidic soils developed from polymetallic ore-bearing aluminosilicate mining waste) contained elevated concentrations of Cu, Zn, Hg, As, Sb, Bi, Co, Ag, Ba, Sr, U and Th; they contained lower contents of REE than Group I Technosols. Group III Technosols (soils developed in smelting-affected areas and containing metallurgical waste) were rich in Cu, As, Sb, Ba, Hg, Co and Ag and contained the lowest REE contents among the studied soils. Sequential BCR extraction revealed that PTTE mobility varied strongly according to soil group, with higher mobility of Mn, Cu and Zn in acidic polymetallic ore-derived soils (Group II), while carbonate-rich soils (Group I) showed mainly immobile forms. Metallurgical slag-derived soils (Group III) exhibited complex PTTE behaviour controlled by organic matter and Fe/Mn oxides. Soil properties (pH, carbonates and TOC) seem to control PTTE mobility. Full article

The persistent release of synthetic dyes such as methylene blue (MB) into aquatic environments poses a significant ecological hazard due to their chemical stability and toxicity. In recent years, the application of engineered composite photocatalysts has emerged as a potent solution for efficient dye degradation under visible and UV light. This review comprehensively summarizes various advanced composites, including carbon-based, metal-doped, and heterojunction materials, tailored for MB degradation. Notably, composites such as TiO₂/C-550, WS₂/GO/Au, and MOF-derived α-Fe₂O₃/ZnO achieved near-complete degradation (>99%) within 30–150 min, while others, like ZnO/JSAC-COO⁻ and Ag/TiO₂/CNT, displayed enhanced charge separation and stability over five consecutive cycles. Band gap engineering (ranging from 1.7 eV to 3.2 eV) and reactive oxygen species (·OH, ·O₂⁻) generation were key to their photocatalytic performance. This review compares the structural attributes, synthetic strategies, and degradation kinetics across systems, highlighting the synergistic role of co-catalysts, surface area, and electron mobility. This work offers systematic insight into the state-of-the-art composite photocatalysts and provides a comparative framework to guide future material design for wastewater treatment applications. Full article

In Greece, the geodynamics of karst hypothermal–mineral springs, in which often shallow fresh groundwater is intermixed, is not well known. This study aims to investigate the monthly hydrochemical variability of three karst hypothermal mineral springs in Greece named Kyllini (southern Greece), Agiasma (northern Greece), and Voskina (northern Greece). Hence, monthly samples were collected and an analysis of major and trace elements, ion ratios, and saturation indices was performed, as well as statistical analysis and cross correlation. Elevated concentrations of Ca²⁺, Mg²⁺, and HCO₃⁻ are present in all springs, indicating that the dissolution of calcite and dolomite constitutes the main water–rock interaction process. Additionally, the mobilization and transport of Mn, Fe, and As are favored by the negative ORP values. However, there are also differences between the three springs. The Kyllini spring is characterized by high salinity and dominated by Na–Cl–HCO₃ water, while the Agiasma spring exhibits a mixed water type with moderate salinity. The Voskina spring reflects a fresher, bicarbonate-dominated aquifer system with modest trace element mobilization. This study provides the first comprehensive monthly assessment of the hydrochemical response of karst hypothermal–mineral springs in Greece, offering new insights into seasonal geochemical dynamics. Full article

This study compared the effectiveness of gallium nitride (GaN) with a single carbon-doped (C-doped) buffer layer and a composite carbon/iron-doped (C/Fe-doped) buffer layer within an AlGaN/GaN high-electron-mobility transistor (HEMT). In traditional power devices, Fe-doping has a large memory effect, causing Fe ions to diffuse outwards, which is undesirable in high-power-device applications. In the present study, a C-doped GaN layer was added above the Fe-doped GaN layer to form a composite buffer against Fe ion diffusion. Direct current (DC) characteristics, pulse measurement, low-frequency noise, and variable temperature analysis were performed on both devices. The single C-doped buffer layer in the AlGaN/GaN HEMT had fewer defects in capturing and releasing carriers, and better dynamic characteristics, whereas the composite C/Fe-doped buffers, by suppressing Fe migration toward the channel, showed higher vertical breakdown voltage and lower sheet resistance, and still demonstrated potential for further performance tuning to achieve enhanced semi-insulating behavior. With optimized doping concentrations and layer thicknesses, the dual-layer configuration offers a promising path toward improved trade-offs between leakage suppression, trap control, and dynamic performance for next-generation GaN-based power devices. Full article

Background/Objectives: Frailty is a multidimensional syndrome characterized by diminished physiological reserves, reduced mobility, and increased fall risk. While clinical assessments are commonly used to screen for frailty, they may not capture minor deficits in postural control. Center-of-pressure (CoP) metrics from force plates provide objective markers of postural control, yet their role in frailty screening remains underexplored. This study aimed to investigate the associations between functional performance measures and CoP-based metrics to identify predictors of frailty among older adults. Methods: Eighty-three adults aged ≥ 55 years with a history of falls were classified as frail or pre-frail based on modified Fried criteria. Functional assessments (Timed Up and Go (TUG), grip strength, Berg Balance Scale [BBS], Falls Efficacy Scale [FES]) and CoP metrics (mean velocity, sway path; eyes open/closed) were evaluated. Both unadjusted and age-adjusted logistic regression models were used to identify independent predictors of frailty. Results: Increased TUG time and number of falls were the strongest risk factors for frailty, while increased sway path and CoP velocity were protective. In particular, sway path under eyes-closed conditions showed the strongest protective association (OR = 0.323, p < 0.001). Additionally, fear of falling (OR = 1.078, p = 0.013) emerged as a significant psychological factor, consistently associated with increased frailty risk regardless of physical performance. Correlation analysis supported these findings, showing that better functional performance was linked to lower frailty risk. Conclusions: CoP sway path and mean velocity independently predict frailty status and offer added value beyond traditional clinical tools. These findings highlight the importance of incorporating instrumented balance assessments into frailty screening to capture nuanced postural control deficits and guide early intervention strategies. Full article

Batteries are important components of electrochemical energy storage systems used in mobile devices, electric vehicles, and power generation systems. This paper proposes a compact battery model dedicated to SPICE. This model takes into account properties of a real battery, such as limited electrical capacity, limited charge and discharge current, limited voltage change at its terminals, the self-discharge effect, the dependence of the battery’s internal resistance on its state of charge, and an influence of temperature on its characteristics. The developed model is presented, along with equations describing the parameters of its components. The results of experimental verification of the correctness of the developed model for different types of batteries are presented and discussed. Good agreement was achieved between the calculation and measurement results for AGM, LiPo, LiFePO₄, and Na-ion batteries. High accuracy of the proposed model was demonstrated for all tested batteries. Full article

Arsenic pollution in paddy soil is a major environmental issue, and its remediation has become a subject of broad interest. Geo-electrochemical technology has been shown to have significant potential for remediating heavy metal-contaminated soils in recent years. Taking contaminated paddy soil from northern Guangxi as the research subject, this study aims to assess the effectiveness of geo-electrochemical technology for arsenic remediation. An orthogonal experimental design was used to identify the optimal combination of parameters, including power supply duration, voltage gradient, power supply mode, and electrolyte type. The arsenic removal efficiency was thoroughly assessed, and the underlying remediation mechanisms associated with geo-electrochemical technology combined with EDTA-2Na were extensively investigated. The findings revealed a substantial decrease in the residual arsenic fraction after treatment, accompanied by a substantial increase in the mobility and bioavailability of arsenic. The maximum removal rate of arsenic from the soil was determined to be 19.59%. Among the analyzed factors, electrolyte type exerted the most significant influence on the arsenic removal efficiency, followed by power supply duration and voltage gradient, while the impact of the power supply mode was less significant. The optimal remediation effect was achieved under the following conditions: a power supply duration of 108 h, a voltage gradient of 0.6 V/cm, continuous power supply mode, and the use of EDTA-2Na as the electrolyte. The multiple strong coordinating atoms in EDTA-2Na can form stable chelates with Fe³⁺ and Al³⁺ bound to arsenic in the soil, thereby causing the desorption of arsenic. The integration of geo-electrochemical technology with EDTA-2Na forms a synergistic multiphase electrochemical reaction mechanism, significantly improving the overall remediation efficiency in arsenic-contaminated soils. Full article

As an important agricultural ecosystem, greenhouse gas (GHG) emissions and arsenic (As) mobilization in rice paddy fields have gained significant attention on climate change and food safety. There is a certain correlation between the GHG and As migration in rice paddy fields. The oxidation of methane in paddy fields can provide electrons for the reduction and release of arsenate. Nitrate in rice paddy soil can promote the fixation of As by oxidizing Fe (II) to form iron oxide–As complexes or directly oxidize As (III) to As (V) to reduce the toxicity of As. However, incomplete denitrification of nitrate can lead to the emission of N₂O. This review systematically expounds the research advances, influencing factors and simultaneous mitigation measures of GHG emissions and As mobilization in rice paddy fields. It focuses on discussing the influence mechanisms of soil physical and chemical properties, water management measures, fertilization methods, and the addition of soil conditioner on As migration and GHG emission, and it looks forward to future research directions. It aims to provide a theoretical basis and practical guidance for reducing the risk of As contamination in rice fields, reducing GHG emission, and achieving sustainable development of rice production. Full article

The Eastern Kazakhstan Gold Belt is a major black-shale-hosted gold province in Central Asia where the main types of deposits comprise mineralized zones with auriferous sulfides (micro- and nano-inclusions of gold and refractory gold) and quartz veins with visible gold. The quartz vein deposits are economically less important but may potentially represent the upper parts of bigger ore systems concealed at depth. In this work, the mineralogy of the quartz vein deposits and related wall rock alteration zones was studied using microscopy and SEM-EDS analysis, and the geochemical dispersion of the ore elements in primary alteration haloes was documented utilizing spatial distribution maps and statistical treatment methods. The studied auriferous quartz veins are classified as epizonal black-shale-hosted orogenic gold deposits. The veins generally have linear shapes with an average width of ca. 1 m and length up to 150 m and contain high-grade native gold with minor amounts of sulfides. In supergene oxidation zones, the native gold is closely associated with Fe-hydroxide minerals cementing brecciated zones within the veins. The auriferous quartz veins are usually enclosed by the wall rock alteration envelopes, where two types of alteration are distinguished. Proximal phyllic alteration (sericite-albite-pyrite ± chlorite, Fe-Mg-Ca carbonates, arsenopyrite, and pyrrhotite) develops as localized alteration envelopes, and pervasive carbonation accompanied by chlorite ± sericite and albite is the dominant process in the distal alteration zones. The rocks within the alteration zones are enriched in Au and chalcophile elements, and three groups of chemical elements showing significant positive mutual correlation have been identified: (1) an early geochemical assemblage includes V, P, and Co (±Ni), which are the chemical elements characteristic for black shale formations, (2) association of Au, As, and other chalcophile elements is distinctly overprinting, and manifests the main stage of sulfide-hosted Au mineralization, and (3) association of Bi and Hg (±Sb and U) includes the chemical elements that are mobile at low temperatures, and can be explained by activity of the late-stage hydrothermal or supergene fluids. The chalcophile elements show negative slopes from proximal to distal alteration zones and form overlapping positive anomalies on spatial distribution mono-elemental maps. Thus, the geochemical methods can provide useful tools to delineate the ore elemental associations and to outline reproducible anomalies for subsequent regional gold prospecting. Full article

Facing energy and environmental issues is recognized globally as one of the major challenges for sustainable development, to which sustainable chemistry can make significant contributions. Strontium ferrate-based materials belong to a little-known class of perovskite-type compounds in which iron is primarily stabilized in the unusual 4+ oxidation state, although some Fe³⁺ is often present, depending on the synthesis and processing conditions and the type and amount of dopant. When doped with cerium at the Sr site, the SrFeO_3−δ cubic structure is stabilized, more oxygen vacancies form and the Fe⁴⁺/Fe³⁺ redox couple plays a key role in its functional properties. Alone or combined with other materials, Ce-doped strontium ferrates can be successfully applied to wastewater treatment. Specific doping at the Fe site enhances their electronic conductivity for use as electrodes in solid oxide fuel cells and electrolyzers. Their oxygen storage capacity and oxygen mobility are also exploited in chemical looping reactions. The main limitations of these materials are SrCO₃ formation, especially at the surface; their low surface area and porosity; and cation leaching at acidic pH values. However, these limitations can be partially addressed through careful selection of synthesis, processing and testing conditions. This review highlights the high versatility and efficiency of cerium-doped strontium ferrates for energy and environmental applications, both at low and high temperatures. The main literature on these compounds is reviewed to highlight the impact of their key properties and synthesis and processing parameters on their applicability as sustainable thermocatalysts, electrocatalysts, oxygen carriers and sensors. Full article

The microcrack initiation and evolution behavior of Fe-C alloy under uniaxial tensile loading are investigated using molecular dynamics (MD) simulations. The model is stretched along the z-axis at a strain rate of 2 × 10⁹ s⁻¹ and temperatures ranging from 300 to 1100 K, aiming to elucidate the microscopic deformation mechanisms during crack evolution under varying thermal conditions. The results indicate that the yield strength of Fe-C alloy decreases with a rising temperature, accompanied by a 25.2% reduction in peak stress. Within the temperature range of 300–700 K, stress–strain curves exhibit a dual-peak trend: the first peak arises from stress-induced transformations in the internal crystal structure, while the second peak corresponds to void nucleation and growth. At 900–1100 K, stress curves display a single-peak pattern, followed by rapid stress decline due to accelerated void coalescence. Structural evolution analysis reveals sequential phase transitions: initial BCC-to-FCC and -HCP transformations occur during deformation, followed by reversion to BCC and unidentified structures post-crack formation. Elevated temperatures enhance atomic mobility, increasing the proportion of disordered/unknown structures and accelerating material failure. Higher temperatures promote faster potential energy equilibration, primarily through accelerated void growth, which drives rapid energy dissipation. Full article

A wearable closed-loop transcutaneous electrical nerve stimulation (TENS) platform has been developed to address the limitations of conventional open-loop neuromodulation systems. Unlike existing systems such as CLoSES—which targets intracranial stimulation—and electromyography-triggered functional electrical stimulation (EMG-FES) platforms primarily used for motor rehabilitation, the proposed device uniquely integrates low-latency surface electromyography (sEMG)-driven control with six-channel current stimulation in a fully wearable, non-invasive format aimed at ambulatory pain modulation. The system combines real-time sEMG acquisition, adaptive signal processing, a programmable multi-channel stimulation engine, and a high-voltage, boost-regulated power supply within a compact, battery-powered architecture. Bench-top evaluations demonstrate rapid response to EMG events and stable biphasic output (±22 mA) across all channels with high electrical isolation. A human-subject protocol using the Cold Pressor Test (CPT), heart rate variability (HRV), and galvanic skin response (GSR) has been designed to evaluate analgesic efficacy. While institutional review board (IRB) approval is pending, the system establishes a robust foundation for future personalized, mobile neuromodulation therapies. Full article