Search Results (238)

In the shift toward sustainable energy, there is a strong demand for efficient and durable energy storage solutions. Supercapacitors, in particular, are a promising technology, but they require high-performance materials that can be produced using simple, eco-friendly methods. This has led researchers to investigate new materials and composites that can deliver high energy and power densities, along with long-term stability. Herein, we report a green synthesis approach to create a composite material consisting of reduced graphene oxide and silver nanoparticles (rGO/Ag). The method uses ascorbic acid, a natural compound found in fruits and vegetables, as a non-toxic agent to simultaneously reduce graphene oxide and silver nitrate. To enhance electrochemical performance, the incorporation of silver nanoparticles into the rGO structures is optimized. In this study, different molar concentrations of silver nitrate (1.0, 0.10, and 0.01 M) are used to control silver nanoparticle loading during the synthesis and reduction process. A correlation between silver concentration, defect density in rGO, and the resulting capacitive behavior was assessed by systematically varying the silver molarity. The synthesized materials exhibited excellent performance as supercapacitor electrodes in a three-electrode configuration, with the rGO/Ag 1.0 M composite showing the best performance, reaching a maximum specific capacitance of 392 Fg⁻¹ at 5 mVs⁻¹. Furthermore, the performance of this optimized electrode material was investigated in a two-electrode configuration as a coin cell device, which demonstrates a maximum areal-specific capacitance of 22.63 mFcm⁻² and a gravimetric capacitance of 19.00 Fg⁻¹, which is within the range of commercially viable devices and a significant enhancement, outperforming low-level graphene-based devices. Full article

Autonomic dysfunction is a key non-motor feature of Parkinson’s disease (PD) and may influence motor performance, particularly gait. While heart rate variability (HRV) has been associated with freezing of gait, its relationship with broader gait parameters remains unclear. The objective was to investigate correlations between resting-state HRV time-domain measures and spatiotemporal gait parameters during comfortable and fast walking in patients with idiopathic PD. Twenty-eight PD patients (mean age 68 ± 9 years) were evaluated at Campus Bio-Medico University Hospital. HRV was recorded at rest using the e-Sense pule™ portable sensor, including the Baevsky’s Stress Index a measure increasing with sympathetic burden. Gait parameters were assessed via the 10 m Timed Up and Go (TUG) test using the Mon4t™ smartphone app at comfortable and fast pace. Clinical data included UPDRS III, MoCA, and disease characteristics. Gait metrics significantly changed between walking conditions. HRV parameters clustered separately from gait metrics but intersected with significant correlations. Higher Stress Index values, reflecting sympathetic dominance, were associated with poorer gait performance, including prolonged transition times, shorter steps, and increased variability (p < 0.001, r = 0.57–0.61). MoCA scores inversely correlated with the Stress Index (r = −0.52, p = 0.004), linking cognitive and autonomic status. UPDRS III and MoCA were related to TUG metrics but not HRV. Time-domain HRV measures, particularly the Stress Index, are significantly associated with spatiotemporal gait features in PD, independent of gait speed. These findings suggest that impaired autonomic regulation contributes to functional mobility deficits in PD and supports the role of HRV as a biomarker in motor assessment. Full article

The wastewater discharged from the aquaculture and textile industries often contains toxic organic dyes, such as methylene blue (MB) and malachite green (MG), which pose significant risk to public health and ecosystem stability due to their high chemical stability, bioaccumulation potential and resistance to degradation. To address these challenges, the development of an integrated system capable of both efficient degradation and highly sensitive detection of organic dyes is essential for ecological restoration and early pollution monitoring. Herein, bifunctional Fe₃O₄-Cu₂O-Ag-GO (FCA 2-GO) nanocomposites (NCs) were developed by depositing Cu₂O, Ag nanocrystals and graphene oxide (GO) onto the surfaces of Fe₃O₄ nanocrystals. This multifunctional material acted as both a photocatalyst and a surface-enhanced Raman scattering (SERS) platform, enabling simultaneous degradation and ultrasensitive detection of organic dyes. Under simulated sunlight irradiation, FCA 2-GO NCs achieved over 98% degradation of both MB and MG within 60 min, driven by the synergistic action of reactive oxygen species (·O₂⁻ and ·OH). The degradation kinetics followed pseudo-first-order behavior, with rate constants of 0.0381 min⁻¹ (MB) and 0.0310 min⁻¹ (MG). Additionally, the FCA 2-GO NCs exhibited exceptional SERS performance, achieving detection limits as low as 10⁻¹² M for both dyes, attributed to electromagnetic–chemical dual-enhancement mechanisms. Practical applicability was demonstrated in soil matrices, showcasing robust linear correlations (R² > 0.95) between SERS signal intensity and dye concentration. This work provides a dual-functional platform that combines efficient environmental remediation with trace-level pollutant monitoring, offering a promising strategy for sustainable wastewater treatment and environmental safety. Full article

In the context of the rising demand for total knee arthroplasty (TKA) in older adults and persistent uncertainty about the quality of long-term functional recovery, this study evaluated elderly patients’ mobility after unilateral TKA via a transquadriceps approach using instrumented Timed Up and Go (TUG) tests. A total of 20 patients treated between 2022 and 2024 at a tertiary hospital were invited to participate in this observational, retrospective, descriptive study, and 19 met the inclusion criteria (age 50–80 and Kellgren–Lawrence ≥ 4). The participants performed two TUG trials at two postoperative time points (18 and 53 months), with an inertial measurement unit (G-sensor) capturing 15 kinematic variables. When comparing the postoperative time points, it was found that the total TUG duration remained stable (14.97 ± 3.48 vs. 15.47 ± 2.93 s; p = 0.58), while the mid-turning peak velocity increased significantly (106.44 ± 30.96 vs. 132.77 ± 30.82°/s; p = 0.0039; r = 0.88). The end-turning velocity and sit-to-stand parameters showed small-to-moderate effect size gains without statistical significance. These findings suggest that, in the first year following surgery, patients continue to experience difficulties with movement fluidity and motor control—especially during turning—underscoring the value of segmented, sensor-based assessments and the need for extended rehabilitation protocols that emphasize rotational control and balance. These findings provide clinically relevant parameters that can support future interventional studies and help guide rehabilitation planning after TKA. Full article

Transition metal sulfides have found a popular spot in research for super capacitive materials due to their enhanced power density and conductivity. This study reports the preparation of a hybrid iron copper sulfide, Fe_0.5Cu_0.5S/rGO, composite via the co-precipitation method. The structural and morphological characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM), which confirmed the successful integration of Fe_0.5Cu_0.5S with rGO. The composite exhibited a high specific capacitance of 416.91 F/g at 1 A/g, 330.65% higher than 96.81 F/g of Fe_0.5Cu_0.5S and outstanding cyclic stability. The enhanced performance can be attributed to the synergistic effects of Fe_0.5Cu_0.5S and rGO, facilitating efficient charge transfer kinetics, ion diffusion, and structural stability, making it a promising candidate for high-performing supercapacitor applications. Full article

Background/Objectives: Aging is associated with a gradual decline in physical capabilities, often leading to impaired balance and reduced functional status, which are major contributors to falls in older adults. Although many studies have assessed these variables independently, a limited amount of research has explored the direct relationship between balance and functional status in a healthy geriatric population. The aim of this study was to investigate the relationship between balance and functional capacity and to assess the influence of demographic factors such as age, comorbidities, smoking status, and history of falls. Methods: A sample of community-dwelling older adults (19 women, 16 men) (n = 35), aged 60 years and above (M = 78 years; SD = 9.23) from Sparta, Greece, took part in the present study. Participants were assessed using three validated tools: (a) the Five Times Sit-to-Stand test, (b) the Timed Up-and-Go test, and (c) the Berg Balance Scale. Spearman’s rank correlation coefficient was used for statistical analysis (α = 0.05). Results: Age was positively correlated with poorer performance in the Five Times Sit-to-Stand (r = 0.40; p < 0.01) and the Timed Up-and-Go test (r = 0.47; p < 0.01) and negatively correlated with Berg Balance Scale scores (r = −0.51; p < 0.01). Comorbidities and smoking were also associated with the Berg Balance Scale. A strong negative correlation was observed between balance and the other two functional tests (Five Times Sit-to-Stand: r = −0.51; Timed Up-and-Go: r = −0.66; both p < 0.01). Conclusions: The findings highlight the importance of evaluating both balance and functional capacity in older adults as interrelated factors that can significantly influence quality of life and fall risk. Future research with larger and more diverse populations is recommended to confirm the present findings and to use exercise programs to prevent falls in the geriatric population. Full article

Microchannel heat sinks (MCHSs) have emerged as an alternative for dissipating high heat rates. However, manufacturing MCHSs can be expensive, so exploring low-cost additive manufacturing using 3D printing is warranted. Before fabrication, the entropy minimization method helps to optimize MCHSs, enhancing their cooling capacity while maintaining their power consumption. We employed this method through computational simulation of laminar water flow in rectangular microchannels ($\mathsf{\mu }$C) and minichannels (mC), considering two heat fluxes (10 and 50 kW/m²). The results showed that the frictional entropy is only appreciable in the smallest and largest channels. These computational results enabled the fabrication of the optimal $\mathsf{\mu }$C and mC, whose experimental implementation validated the computational findings. Moreover, we computationally studied the effect of using rGO-Ag water-based nanofluids as a coolant. In general, a reduction in total entropy generation was observed at a heat flux of 50 kW/m². Although at lower heat flux (10 kW/m²), mC was the best option. Channels with lower heights were more effective at higher heat fluxes (≥50 kW/m²). Our findings offer a cost-effective strategy for fabricating high-performance cooling systems while also highlighting the interplay among heat flux, entropy generation, and nanofluid-enhanced cooling. Full article

This study reports the impact of a silver nanoparticles/reduced graphene oxide@titanium dioxide nanocomposite (Ag/rGO@TiO₂) on the mechanical and biocompatibility properties of poly(styrene-co-methylmethacrylate)/poly methyl methacrylate (PS-PMMA/PMMA)-based bone cement. The chemical, structural, mechanical, and thermal characteristics of Ag/rGO@TiO₂ nanocomposite-reinforced PS-PMMA bone cement ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) were evaluated using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, and electron microscopy. FT-IR, XRD, and transmission electron microscopy results confirmed the successful synthesis of the nanocomposite and the nanocomposite-incorporated bone cement. The elastic modulus (E) and hardness (H) of the ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) bone cement were measured to be 5.09 GPa and 0.202 GPa, respectively, compared to the commercial counterparts, which exhibited E and H values of 1.7 GPa to 3.7 GPa and 0.174 GPa, respectively. Incorporating Ag/rGO@TiO₂ nanocomposites significantly enhanced the thermal properties of the bone cement. Additionally, in vitro studies demonstrated that the bone cement was non-toxic to the MG63 cell line. Full article

Background: This study compared performance-based function and self-report function in lower-limb prosthesis users. Methods: Twenty-two lower-limb prosthesis users (aged 52.1 ± 14.2) were administered the Orthotic Prosthetic User Survey (OPUS) Lower Extremity Functional Status (LEF), Satisfaction With Devices (SWD), alongside the Godin Leisure-Time Exercise Questionnaire (GLTQ), Timed Up and Go (TUG) test, two-minute walk test (2MWT), and six-minute walk test (6MWT). Body composition and standing postural sway displacement and velocity were also measured. Pearson’s Product Moment coefficients were used to assess relationships between the OPUS and other outcome variables. ANOVAs were used to identify differences in all outcome variables between lower unilateral (LU) and all other (AO) amputees. Results: There was a moderate correlation between LEF and center of pressure (CoP) path length with eyes open (r₍₁₉₎ = −0.43, p = 0.048) and eyes closed (r₍₁₉₎ = −0.43, p = 0.049). While the relationship between LEF and TUG was significant (r₍₂₀₎ = −0.49, p = 0.021), this was not so with SWD and TUG (r₍₂₀₎ = −0.17, p = 0.456). Both the 2MWT (r₍₂₀₎ = 0.48, p = 0.023) and 6MWT (r₍₂₀₎ = 0.47, p = 0.028) were moderately correlated with LEF. GLTQ was significantly correlated with LEF (r₍₂₀₎ = 0.70, p = 0.001). The LU group outperformed the AP group during the TUG and 6MWT (p < 0.05). LU group scored significantly higher on LEF compared to the AO group (p < 0.05). The reliability of LEF between the measurement on day 1 (54.3 ± 12.0) and day 2 (53.6 ± 12.8) was high (α = 0.94). Conclusions: This study provides an insight into associations of balance and self-reported function in lower limb prosthesis users. Future work can target rehabilitation strategies to address challenges faced by multiple limb prosthesis users. Full article

Moisture–electricity generators (MEGs) hold great promise for green energy conversion. However, existing devices focus on the need for complex gradient distribution treatments and the improvement in output voltage, overlooking the important role of the graphene oxide (GO) oxidation degree and the response time and recovery time in practical application. In this work, we develop printed MEGs by synthesizing reduced graphene oxide/silver nanoparticle (rGO/Ag) composites and controlling the GO oxidation degree. The rGO/Ag layer serves as a functional component that enhances cycling stability and shortens the recovery time. Additionally, compared to conventional rigid-structure devices, these flexible MEGs can be produced by inkjet printing and drop-casting techniques. A 1 cm² MEG can generate a voltage of up to 60 mV within 2.4 s. Notably, higher output voltages can be easily achieved by connecting multiple MEG units in series, with 10 units producing 200 mV even under low relative humidity (RH). This work presents a low-cost, highly flexible, lightweight, and scalable power generator, paving the way for broader applications of GO and further advancement of MEG technology in wearable electronics, respiratory monitoring, and Internet of Things applications. Full article

Lithium- and sodium-ion batteries (LIBs and SIBs) suffer from the significant degradation of electrochemical performance at low temperatures. This work presents promising hybrid anodes synthesized by the rapid thermolysis of ammonium tetrathiomolybdate and graphene oxide (GO) at 600 and 700 °C. Transmission electron microscopy revealed the formation of MoS₂ crystallites oriented along or perpendicular to the surface of reduced GO (rGO) layers. X-ray photoelectron spectroscopy found the covalent C–S bonds connecting components in the MoS₂/rGO hybrids. The MoS₂/rGO_600 hybrid showed higher specific capacities in LIBs of 1370 mAh/g, 835 mAh/g, and 711 mAh/g at a current density of 0.1 A/g and temperatures of 25 °C, 0 °C, and −20 °C, respectively, due to the presence of excess sulfur in the sample. Increasing the current density to 2 A/g retained 78 and 34% of the capacity at 25 °C and −20 °C. In SIBs, the MoS₂/rGO_700 hybrid showed more promising results, achieving 550 mAh/g at 0.1 A/g and 400 mAh/g at 2 A/g, while lowering the temperature to −20 °C retained 48 and 17% of the capacity. Such good SIB performance is attributed to the enrichment of the sample with vertically oriented MoS₂ layers covalently bonded to the rGO surface. Full article

The measurement of humidity is of great significance for precision instruments, semiconductor integrated circuits, and element manufacturing factories. The oxygen-containing groups and noble metals in graphene-based sensing materials can significantly influence their humidity-sensing performance. Herein, 1,3,5-benzenetricarboxylic acid-functionalized reduced graphene oxide (H3BTC-rGO) loaded with Ag nanocluster nanocomposites (H3BTC-rGO/Ag) was synthesized via a facile one-step reduction method. The H3BTC-rGO/Ag-based sensor exhibited excellent humidity-sensing performance, including a higher sensitivity of 88.9% and a faster response/recovery time of 9 s/16 s towards 50% RH than those of other GO-, rGO-, and H3BTC-rGO-based sensors. The proposed humidity sensor was tested in the range of 0% to 100% RH and showed excellent sensitivity even at a low relative humidity of 0–10% or a high relative humidity of 90–100%. In addition, the H3BTC-rGO/Ag-based sensor had excellent selectivity, reliable repeatability, and good stability over 30 days under different relative humidities. Compared with H3BTC-rGO-200, the H3BTC-rGO/Ag-0.25-based sensor exhibited a low hysteresis of less than ±5% RH. The high performance was ascribed to the high density of the carboxyl groups and good conductivity of H3BTC-rGO, as well as the catalytic role of the Ag nanoclusters, resulting in high water adsorption rates. The potential applications of the H3BTC-rGO/Ag-based humidity sensor in human exhalation monitoring are also discussed. This work provides a reference for the application of graphene-based flexible sensors in monitoring very wet and dry environments. Full article

Background: The prevalence of malnutrition is high in post-intensive care unit (ICU) coronavirus disease 2019 (COVID-19) patients during hospitalization and after hospital discharge. This paper presents prospective results from the NutriEcoMuscle study, a multicenter observational study. The study aimed to evaluate changes in nutritional and functional status in post-ICU COVID-19 patients following nutritional and physical rehabilitation interventions. Secondary aims included assessing adherence to and tolerance of the oral nutritional supplement (ONS) used in the nutritional intervention. Methods: The study enrolled adults who had been admitted to the ICU due to severe COVID-19. At hospital discharge, the patients underwent a nutritional intervention based on oral nutritional supplements (ONSs) with 100% serum lactoprotein enriched with leucine and vitamin D and a physical rehabilitation program. They were followed up during three months. Performed assessments included Subjective Global Assessment (SGA), Global Leadership Initiative on Malnutrition (GLIM) criteria, Barthel index (BI), handgrip strength and Timed Up and Go test, bioelectrical impedance analysis (BIA), nutritional ultrasound (US), and tolerance and adherence to ONS. Sample size was calculated based on handgrip strength, and parametric and non-parametric tests were used to assess differences between the baseline and three-month outcomes. Results: The study included 96 patients (71.9% male, mean age 58.8 years, mean body mass index (BMI) of 28.8 kg/m², 36.5% obese). A total of 85 patients (62 men and 23 women) completed the 90-day follow-up. The mean weight gain after the intervention was 6.8 (SD 5.2) kg (similar in men and women; p = 0.263). The proportion of patients with malnutrition according to the SGA or GLIM criteria decreased from 100% to 11.8% and 36.4%, respectively (p < 0.00001 in both cases). The proportion of patients with functional limitations by BI decreased from 66.7% to 27.0% (p < 0.0001). Handgrip strength increased more than 40% in both men and women (p < 0.00001). The time to perform the Timed Up and Go (TUG) test decreased more than 40% in both men and women (p < 0.00001). According to BIA, the mean fat mass did not increase significantly in either men or women. The mean fat-free mass index (FFMI) increased significantly in both men and women. There were also significant increases in body cell mass, skeletal muscle mass index, and appendicular skeletal muscle mass index. The phase angle (PhA) increased significantly in both men (26.5%) and women (17.4%). In a multivariate analysis, age and baseline PhA were related to the PhA increase (adjusted R² = 0.5573). The US study showed a significant increase in the mean measurements of muscle area, muscle circumference, X-axis, and Y-axis in the rectus femoris. Regarding abdominal fat, there were no significant increases in total, superficial, or preperitoneal adipose tissue by US. Participants engaged in a median interquartile range (IQR) of 70 (0–120) min/week of strength exercise and 60 (0–120) min/week of moderate physical exercise. The supplement was well tolerated, and poor adherence (less than 50%) was low (4% of the participants). Conclusions: A three-month intervention, including ONS and physical rehabilitation, is associated with a significant improvement in nutritional and functional status. Patients gained weight primarily by increasing their muscle mass. There was no significant increase in fat mass, as measured by BIA or US. The intervention was well tolerated and had good adherence. Full article

Graphene and its related nanocomposites have garnered significant interest due to their distinct physiochemical and biological properties. In this study, reduced graphene oxide–silver hybrid nanostructures were synthesized for applications in biomedical nanotechnology, particularly in targeting cancer stem cells (CSCs). A range of analytical techniques, such as X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV–visible absorption spectroscopy (UV–VIS), were employed to characterize graphene oxide (GO), reduced graphene oxide (rGO)–silver nanoparticles (AgNPs), and their composite structures. The GO-rGO-AgNPs exhibited potent anticancer properties as evidenced by cell culture assays, spheroid formation assay, and quantitative RT-PCR analysis. Treatment of breast cancer cells (MCF-7) with GO, rGO, and AgNPs significantly reduced cell proliferation and mammosphere formation. Furthermore, these treatments downregulated the expression of marker genes associated with CSCs in MCF-7 cells. Among the tested materials, rGO-AgNP, sodium citrate-mediated GO-AgNP, and rGO-AgNP nanocomposites demonstrated superior inhibitory effects on cell survival compared to GO alone. These findings suggest that these nanocomposites hold promise as effective and non-toxic therapeutic agents for targeting cancer cells and CSCs, thereby offering a novel approach to cancer treatment. Full article

Background: The early detection of fall risk in older adults is crucial for prevention. This study assessed the 3-Meter Backward Walk Test (3m-BWT) as a predictor of falls. Methods: A retrospective observational case–control study was conducted with 483 community-dwelling participants (mean age 76.3 ± 6.5 years), including 101 individuals with a history of falls in the previous 12 months. A standardized battery of functional assessments was applied. Results: Significant differences were observed between fallers and non-fallers across all functional variables (p < 0.001), with fallers demonstrating slower performance on the 3m-BWT (6.8 ± 3.4 s vs. 5.1 ± 1.3 s). The 3m-BWT showed moderate correlations with Short Physical Performance Battery, 5-repetition Sit-to-Stand, gait speed, and 4-Square Step Test, and a moderate-to-strong correlation with Timed Up-and-Go (r = 0.632), even after adjusting for age, sex, and BMI. Although the 3m-BWT exhibited superior discriminative ability compared to other tests (AUC = 0.655), its predictive power in isolation remains limited. The optimal cut-off point was identified at 5.5 s (sensitivity: 59.5%; specificity: 68.6%), while a threshold of <3.5 s yielded high sensitivity (98%) but low specificity, supporting its use in fall risk screening. Conclusions: These findings support the integration of the 3m-BWT as a complementary tool within comprehensive geriatric assessments, particularly in contexts requiring high sensitivity. Given the multifactorial nature of falls, combining the 3m-BWT with other clinical evaluations and fall history is recommended to enhance risk stratification and inform preventive strategies. Full article