Search Results (3,752)

The indiscriminate use of synthetic surfactants, despite their desirable properties, poses significant environmental risks to ecosystems. This study explores saponins extracted from quinoa (Chenopodium quinoa) residues as a sustainable alternative. Saponin extract (SE) with 42% purity, obtained through hydrodynamic cavitation and membrane technology, was analyzed to determine its techno-functional properties. The critical micelle concentration (CMC) was 1.2 g/L, reducing the surface tension (ST) from 72.0 mN/m to 50.0 mN/m. The effects of temperature (30–90 °C), pH (2–12), and salinity (10,000–150,000 ppm NaCl) on ST and the emulsification index (EI) were assessed using a Box–Behnken design. Optimized conditions yielded an ST of 49.02 mN/m and an EI of 63%. Given these characteristics, SE was evaluated as a detergent across diverse swatches. This study showcases the attributes of quinoa-derived saponins, highlighting their potential for eco-friendly detergent applications. Full article

Mini passive direct methanol fuel cells (mpDMFCs) appear to be a promising alternative for powering portable devices, since they use a liquid fuel, have a fast refuelling time, have a high efficiency and have a low environmental impact. However, some issues need to be solved before their commercialization, such as methanol crossover, short lifetime and high costs. The present work studies the effect of reducing the anode and cathode catalyst loading on the performance of a mpDMFC towards a reduction in the system costs and the characterization of the system losses. The undesirable losses that affect the fuel cell performance were identified and quantified using the electrochemical impedance spectroscopy (EIS) technique. Accordingly, a novel equivalent electric circuit (EEC) was proposed, accurately reproducing the mini pDMFC. In this work, a maximum power density of 7.07 mW cm⁻² was obtained, with a methanol concentration of 5 M, using 2 mg cm⁻² Pt-RuB and 4 mg cm⁻² PtB. The mpDMFC allowed the cell to work with high methanol concentrations and reduced anode catalyst loadings. Full article

As the use of electrochemical batteries, especially lithium–ion (Li-Ion) batteries, increases due to emerging applications and expanding markets, the accurate and fast estimation of their state of health (SOH) is becoming increasingly important. The accuracy of the SOH estimation is highly dependent on the correlation strength between the used indicator and SOH and the accuracy of the SOH indicator measurement. This paper presents a new differential indicator which has a strong and consistent correlation with the SOH of Li-Ion batteries, based on a new Electrochemical Impedance Spectrum (EIS) Phase–Magnitude relationship. It is shown in this paper that the EIS Phase–Magnitude relationship exhibits a phase-based differential impedance magnitude SOH indicator between a first-phase peak point and a last-phase valley point. Because of the differential nature of this SOH indicator and because the two impedance values are measured at a phase peak point and a valley phase point regardless of the phase absolute values, the effect of impedance measurement shift/offset (error) on SOH estimation is reduced. This supports the future development of more accurate and faster online and offline SOH estimation algorithms and systems that have a higher immunity to impedance measurement shift/offset (error). Furthermore, in this work, the EIS was measured for a lithium–ion battery that was down to a ~15% SOH, which was not only used to support the conclusions of this paper, but also helped in filling a gap in the literature for EIS data under deep/high degradation levels. Full article

In this investigation, the efficacy of PCA-GLU, a polymer obtained by copolymerizing citric acid and glutamic acid, as a corrosion inhibitor for carbon steel was investigated in a 3.5wt% NaCl solution. Electrochemical impedance spectroscopy (EIS) techniques and potentiodynamic polarization (PDP) measurements were used to evaluate the corrosion inhibition. The findings demonstrate that PCA-GLU has a 96.73% corrosion inhibition efficiency. Additionally, when the inhibitor concentration rises, the corrosion inhibition efficiency rises as well, reaching an ideal concentration of 400 mg/L. Furthermore, PCA-GLU can create an adsorption layer on the surface of Q235. This paper verifies the adsorption mechanism of PCA-GLU through molecular dynamics simulations of the system and quantum chemical calculations of corrosion inhibitors in solution. Ultimately, our research findings validate that PCA-GLU is an efficient corrosion inhibitor in safeguarding carbon steel against corrosion in marine environments. Full article

Electrochemical DNA sensors for DNA damage detection based on electroactive polymer poly(proflavine) (PPFL) that was synthesized at screen-printed carbon electrodes (SPCEs) from phosphate buffer (PB) and two natural deep eutectic solvents (NADESs) consisting of citric or malonic acids, D-glucose, and a certain amount of water (NADES1 and NADES2) were developed. Poly(proflavine) coatings obtained from the presented media (PPFL_PB, PPFL_NADES1, and PPFL_NADES2) were electrochemically polymerized via the multiple cycling of the potential or potentiostatic accumulation and used for the discrimination of thermal and oxidative DNA damage. The electrochemical characteristics of the poly(proflavine) coatings and their morphology were assessed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The working conditions for calf thymus DNA implementation and DNA damage detection were estimated for all types of poly(proflavine) coatings. The voltammetric approach made it possible to distinguish native and chemically oxidized DNA while the impedimetric approach allowed for the successful recognition of native, thermally denatured, and chemically oxidized DNA through changes in the charge transfer resistance. The influence of different concentrations of conventional antioxidants and pharmaceutical preparations on oxidative DNA damage was characterized. Full article

Background/Objectives: Energy availability (EA) is essential for maintaining physiological functions, significantly influencing athletes’ health and performance. Nutritional behaviors, however, vary across sports. This study aims to assess EA levels in athletes from different disciplines, focusing on the relationship between EA and body composition in endurance athletes compared to rugby players. Methods: This study involved 18 endurance athletes (15 men, 3 women) and 36 rugby players (all men). Data were gathered through interviews, questionnaires, and bioimpedance analysis. Energy intake (EI) was measured with a 24 h dietary recall, and exercise energy expenditure (EEE) was calculated using the IPAQ questionnaire. EA was calculated as EA = (EI − EEE)/fat-free mass (FFM), with results categorized into clinical, subclinical, and optimal ranges. Results: The endurance group had a lower average FFM (57.81 kg) compared to the rugby players (67.61 kg). EA was also significantly lower in endurance athletes (11.72 kcal/kg FFM) than in rugby players (35.44 kcal/kg FFM). Endurance athletes showed more restrictive nutritional behavior with lower EI and higher EEE, but both groups maintained body composition within normal ranges. Conclusions: Endurance athletes exhibit greater nutritional restrictions compared to rugby players, though their body composition remains healthy. Further research is required to investigate the long-term effects of low EA on performance, injury risk, and potential impairment when EA falls below the optimal threshold of 45 kcal/kg FFM/day. Full article

Graphene oxide (GO) is considered an ideal material for applications involving corrosion resistance due to its excellent properties. However, the structure, surface functional groups, and distribution of GO in zinc-rich coatings (ZRCs) have a remarkable influence on coating properties. GO was reduced in a hydrochloric acid environment using spherical zinc powder, and the resulting products were subsequently dried and incorporated into waterborne inorganic ZRCs. Results show that zinc powder effectively reduces oxygen-containing functional groups on the GO surface, and reduced GO (rGO) is deposited on the surface of zinc powder. This improves the electron migration efficiency of rGO and decreases its surface energy. The electrochemical impedance spectroscopy (EIS) and salt spray test results demonstrate that among the coatings, the ZRC containing 0.2 wt.% rGO (40Zn–0.2rGO) exhibits the highest impedance modulus at the low frequency end. Its impedance modulus reaches 1 × 10⁴ Ω∙cm² after 216 h immersion. Furthermore, 40Zn–0.2rGO exhibits no signs of corrosion at the marked areas even after 216 h of the salt spray test. The good dispersion effect of the added 0.2 wt.% rGO in the coating, coupled with its exceptional electrical conductivity, facilitates the enhanced contribution of zinc powder to cathodic protection, thereby mitigating the matrix erosion caused by corrosive media. Following zinc powder corrosion, the surface of the coating can still be adorned with insoluble corrosion products such as ZnO or Zn₅(OH)₈Cl₂, thereby offering shielding protection to the substrate. Full article

The specific energy of lithium-ion batteries (LIBs) can be enhanced through various approaches, one of which is increasing the proportion of active materials by thickening the electrodes. However, this typically leads to the battery having lower performance at a high cycling rate, a phenomenon commonly known as rate capacity retention. One solution to this is perforating the electrode, by creating channels or corrugations in the active electrode material, either as holes or as channels. This is known to reduce the rate capacity retention effect, but in order to engineer this better, a simplified transport process analysis needs to be established. In this paper, we propose a classic electrochemical analysis based on voltage–charge cycling measurements in order to obtain a classical mass transport coefficient, $h_m$, that is further used as a main indicator for electrode design quality assessment. We also demonstrate theoretically and experimentally how the mass transfer coefficient, $h_m$, can be determined and how it changes as the electrode layer thickness increases, with and without electrode corrugations. Full article

The unregulated use of ciprofloxacin (CIPF) has led to increased resistance in patients and has threatened human health with issues such as digestive disorders, kidney disorders, and liver complications. In order to overcome these concerns, this work introduces a portable electrochemical sensor based on a disposable integrated screen-printed carbon electrode (SPCE) coated with gold nanoparticle-embedded thiol-functionalized Ti₃C₂T_x MXene (AuNPs-S-Ti₃C₂T_x MXene) for simple, rapid, precise, and sensitive quantification of CIPF in milk and water samples. The high surface area and electrical conductivity of AuNPs are maximized thanks to the strong interaction between AuNPs and SH-Ti₃C₂T_x MXene, which can prevent the aggregation of AuNPs and endow larger electroactive areas. Ti₃C₂T_x MXene was synthesized from Ti₃AlC₂ MAX phases, and its thiol functionalization was achieved using 3-mercaptopropyl trimethoxysilane. The prepared AuNPs-S-Ti₃C₂T_x MXene nanocomposite was characterized using FESEM, EDS, XRD, XPS, FTIR, and UV–visible spectroscopy. The electrochemical behavior of the nanocomposite was examined using CV, EIS, DPV, and LSV. The AuNPs-S-Ti₃C₂T_x MXene/SPCE showed higher electrochemical performances towards CIPF oxidation than a conventional AuNPs-Ti₃C₂T_x MXene/SPCE. Under the optimized DPV and LSV conditions, the developed nonenzymatic CIPF sensor displayed a wide range of detection concentrations from 0.50 to 143 μM (DPV) and from 0.99 to 206 μM (LSV) with low detection limits of 0.124 μM (DPV) and 0.171 μM (LSV), and high sensitivities of 0.0863 μA/μM (DPV) and 0.2182 μA/μM (LSV). Full article

The inhomogeneity between cells is the main cause of failure and thermal runaway in Lithium-ion battery packs. Electrochemical Impedance Spectroscopy (EIS) is a non-destructive testing technique that can map the complex reaction processes inside the battery. It can detect and characterise battery anomalies and inconsistencies. This study proposes a method for detecting impedance inconsistencies in Lithium-ion batteries. The method involves conducting a battery EIS test and Distribution of Relaxation Times (DRT) analysis to extract characteristic frequency points in the full frequency band. These points are less affected by the State of Charge (SOC) and have a strong correlation with temperature, charge/discharge rate, and cycles. An anomaly detection characteristic impedance frequency of 136.2644 Hz was determined for a cell in a Lithium-ion battery pack. Single-frequency point impedance acquisition solves the problem of lengthy measurements and identification of anomalies throughout the frequency band. The experiment demonstrates a significant reduction in impedance measurement time, from 1.05 h to just 54 s. The LOF was used to identify anomalies in the EIS data at this characteristic frequency. The detection results were consistent with the actual conditions of the battery pack in the laboratory, which verifies the feasibility of this detection method. The LOF algorithm was chosen due to its superior performance in terms of FAR (False Alarm Rate), MAR (Missing Alarm Rate), and its fast anomaly identification time of only 0.1518 ms. The method does not involve complex mathematical models or parameter identification. This helps to achieve efficient anomaly identification and timely warning of single cells in the battery pack. Full article

Tungsten-doped TiO₂ thin films were prepared by sol–gel method on fluorine-doped tin oxide-coated substrates as working electrodes of dye-sensitized solar cells. The influences of different W doping (0, 2, 4, 6, and 8 at%) on the microstructure, optical, and photovoltaic properties of the W-TiO₂ thin-film DSSCs were studied by the measurement of X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, and electrochemical impedance spectroscopy (EIS). An optimal DSSCs performance was observed with a 6 at% W-doped TiO₂ thin film, resulting in a Voc of 0.68 V, a Jsc of 20.2 mA/cm², an FF of 68.6%, and an efficiency (η) of 9.42%. The efficiency of DSSCs with 6 at% W-doped TiO₂ photoanode improved by 75%. This is because the 6 at% W-doped TiO₂ thin film increases the specific surface area and electron transfer rate. Full article

This study synthesized NiAl-layered double hydroxide (LDH)/Cu-MOF photocatalyst using a simple impregnation method involving NiAl-LDH and Cu-MOF. The successful synthesis was confirmed through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential measurements, thermogravimetric analysis (TGA), ultraviolet diffuse reflectance spectroscopy (UV-DRS), N₂ adsorption at −196 °C, and electrochemical impedance spectroscopy (EIS). Photocatalysts based on NiAl-LDH, Cu-MOF, and NiAl-LDH/Cu-MOF were used to remove methyl orange (MO) dye from contaminated water. The impact of various factors, including pH, dye concentration, and photocatalyst amount, on MO degradation efficiency was assessed. FTIR analysis was conducted both before and after dye degradation. The optimal degradation conditions were a photocatalyst dose of 25 mg and a pH of 3. Kinetic studies indicated that the degradation of MO dye onto NiAl-LDH/Cu-MOF followed a pseudo-first-order and an L–H or Langmuir–Hinshelwood model. The value of R² = 0.94 confirms the validity of pseudo-first-order and Langmuir–Hinshelwood (L–H) kinetic models for the photocatalytic degradation of MO dye. This study highlights the importance of developing novel photocatalysts with improved degradation efficiency to protect the water environment. Antibacterial activity was also performed with antibacterial sensibility testing by disk diffusion to determine minimal inhibitory and bactericidal concentrations. In short, NiAl-LDH/Cu-MOF can be helpful for various biomedical and industrial applications. Full article

Electrochemical impedance spectroscopy (EIS) is a non-invasive and label-free method widely used for characterizing cell cultures and monitoring their structure, behavior, proliferation and viability. Microfluidic systems are often used in combination with EIS methods utilizing small dimensions, controllable physicochemical microenvironments and offering rapid real-time measurements. In this work, an electrode array capable of conducting EIS measurements was integrated into a multichannel microfluidic chip which is able to trap individual cells or cell populations in specially designed channels comparable to the size of cells. An application-specific printed circuit board (PCB) was designed for the implementation of the impedance measurement in order to facilitate connection with the device used for taking EIS spectra and for selecting the channels to be measured. The PCB was designed in consideration of the optical screening of trapped cells in parallel with the EIS measurements which allows the comparison of EIS data with optical signals. With continuous EIS measurement, the filling of channels with cell suspension can be followed. Yeast cells were trapped in the microfluidic system and EIS spectra were recorded considering each individual channel, which allows differentiating between the number of trapped cells. Full article

Prostate cancer (PCa) remains a significant health threat, with chemoresistance and recurrence posing major challenges despite advances in treatment. The epithelial to mesenchymal transition (EMT), a biochemical process where cells lose epithelial features and gain mesenchymal traits, is linked to chemoresistance and metastasis. Electrical impedance spectroscopy (EIS), a novel label-free electrokinetic technique, offers promise in detecting cell phenotype changes. In this study, we employed EIS to detect EMT in prostate cancer cells (PCCs). PC3, DU145, and LNCaP cells were treated with EMT induction media for five days. EIS characterization revealed unique impedance spectra correlating with metastatic potential, distinguishing DU145 EMT+ and EMT− cells, and LNCaP EMT+ and EMT− cells (in combination with dielectrophoresis), with comparisons made to epithelial and mesenchymal controls. These changes were supported by shifts in electrical signatures, morphologies, and protein expression, including the downregulation of E-cadherin and upregulation of vimentin. No phenotype change was observed in PC3 cells, which maintained a mesenchymal phenotype. EMT+ cells were also distinguishable from mixtures of EMT+ and EMT− cells. This study demonstrates key advancements: the application of EIS and dielectrophoresis for label-free EMT detection in PCCs, characterization of cell electrical signatures after EMT, and EIS sensitivity to EMT transitions. Detecting EMT in PCa is important to the development of more effective treatments and overcoming the challenges of chemoresistance. Full article

Skin barrier impairment is becoming increasingly common due to changes in lifestyle and modern living environments. Oily sensitive skin (OSS) is a condition that is characterized by an impaired skin barrier. Thus, examining the differences between OSS and healthy skin will enable a more objective evaluation of the characteristics of OSS and facilitate investigations of potential treatments. Initially, a self-assessment questionnaire was used to identify patients with OSS. Biophysical measurements and LAST scores were used to determine whether skin barrier function was impaired. Epidermal biophysical properties, including skin hydration, transepidermal water loss (TEWL), sebum content, erythema index (EI), and a* value, were measured with noninvasive instruments. We subsequently devised a noninvasive D-square sampling technique to identify changes in the skin metabolome in conjunction with an untargeted metabolomics analysis with an Orbitrap Q ExactiveTM series mass spectrometer. In the stratum corneum of 47 subjects, 516 skin metabolites were identified. In subjects with OSS, there was an increase in the abundance of 15 metabolites and a decrease in the abundance of 48 metabolites. The participants with OSS were found to have the greatest disruptions in sphingolipid and amino acid metabolism. The results revealed that an impaired skin barrier is present in patients with OSS and offers a molecular target for screening for skin barrier damage. Full article