Search Results (4,816)

Methane steam reforming is the most widely adopted hydrogen production technology. To address the challenges associated with the large radial thermal resistance and low mass transfer rates inherent in the tubular packed bed reactors during the MSR process, this study proposes a structural design optimization that integrates annular metal foam gas channels along the inner wall of the reforming tubes. Utilizing multi-physics simulation methods and taking the conventional tubular reactor as a baseline, a comparative analysis was performed on physical parameters that characterize flow behavior, heat transfer, and reaction in the reforming process. The integration of the annular channels induces a radially non-uniform distribution of flow resistance in the tubes. Since the metal foam exhibits lower resistance, the fluid preferentially flows through the annular channels, leading to a diversion effect that enhances both convective heat transfer and mass transfer. The diversion effect redirects the central flow toward the near-wall region, where the higher reactant concentration promotes the reaction. Additionally, the higher thermal conductivity of the metal foam strengthens radial heat transfer, further accelerating the reaction. The effects of operating parameters on performance were also investigated. While a higher inlet velocity tends to hinder the reaction, in tubes integrated with annular channels, it enhances the diversion effect and convective heat transfer. This offsets the adverse impact, maintaining high methane conversion with lower pressure drop and thermal resistance than the conventional tubular reactor does. Full article

The adsorption of gas reactant molecules (H₂, CO, etc.) to the surface of hematite is the premise of chemical reaction. In order to further promote the basic research on the reaction mechanism of hematite reduction by a H₂-CO gas mixture, the adsorption behavior of H₂ (or CO) under the conditions of pre-adsorbed H₂O (or CO₂) was systematically studied by the density functional theory (DFT) combined with reduction experiments. The results indicate that the gas molecules (H₂, CO, H₂O and CO₂) adsorbed on the Fe atom of the Fe₂O₃ (001) surface rather than the O atom, and the adsorption energy of the Fe₂O₃-CO adsorption system was relatively minimum (−1.317 eV), indicating that the Fe₂O₃-CO adsorption system was more stable. In addition, the adsorption energy of the H₂ molecule adsorbed to the Fe₂O₃-H₂O adsorption system was −0.132 eV, which was smaller than that of the H₂ molecule directly adsorbed to Fe₂O₃ (−0.013 eV), indicating that the H₂O molecule pre-adsorption was beneficial to the H₂ molecule adsorption. Compared with the H₂O molecule, the CO₂ molecule had relatively less influence on the adsorption and subsequent behavior of CO with Fe₂O₃. From the experiment analysis results, on the whole, CO₂ had a greater impact on the gas diffusion, while H₂O had a greater impact on the interfacial chemical reaction (gas adsorption), which was consistent with the DFT calculation results. Full article

Reported rate constants of charge transfer reactions (CTs) have ranged widely, depending on techniques and timescales. This fact can be attributed to the time-dependent double-layer capacitance (DLC), caused by solvent interactions such as hydrogen bonds. The time variation of the DLC necessarily affects the heterogeneous electrode kinetics. The delay by the solvation, being frequency dispersion, is incorporated into the CT kinetics in this report on the basis of the conventional reaction rate equations. It is different from the absolute rate theory. This report insists on a half value of the transfer coefficient owing to the segregation of the electrostatic energy from the chemical one. The rate equation here is akin to the Butler–Volmer one, except for the power law of the time caused by the delay of the DLC. The dipoles orient successively other dipoles in a group associated with the delay, which resembles that in the DLC. The delay suppresses the observed currents in the form of a negative capacitance. The above behavior was examined with a ferrocenyl derivative by ac impedance methods. The delay from diffusion control was attributed to the negative capacitance rather than the CT, even if the conventional DLC effect was corrected. Full article

Cognitive flexibility—the ability to adapt cognitive strategies and behavioral responses in changing environments—is a key component of executive function, supporting rule updating and conflict resolution. Individuals with substance addiction often exhibit behavioral rigidity and reduced adaptability, reflecting impairments in this domain. This study examined cognitive flexibility in individuals with methamphetamine dependence through three behavioral tasks—intra-dimensional task switching, extra-dimensional task switching, and the Wisconsin Card Sorting Test (WCST)—in combination with a subjective self-report measure. Results showed that, compared to healthy controls, methamphetamine-dependent individuals demonstrated elevated reaction time switch costs in Intra-dimensional Task Switching and increased accuracy switch costs in Extra-dimensional Task Switching, as well as more perseverative and non-perseverative errors in the WCST. These findings suggested not only reduced performances in explicitly cued rule updating and strategic shifting but also deficits in feedback-driven learning and inflexibility in cognitive set shifting on methamphetamine-dependent individuals. Moreover, their self-reported cognitive flexibility scores were aligned with their objective performance, significantly lower than healthy controls. In summary, these findings revealed consistent cognitive flexibility impairments at both behavioral and subjective levels in individuals with methamphetamine dependence, indicating a core executive dysfunction that may undermine adaptive functioning in real-life contexts. The study offers critical insights into the cognitive mechanisms underlying addiction and provides a theoretical foundation for targeted cognitive interventions. Full article

Water-reducing admixtures are of enormous importance to adjust the workability of alkali-activated materials. Especially in geopolymers activated by highly concentrated alkaline solutions, the polycarboxylate ether (PCE) superplasticizers are less effective than in conventional cementitious systems. The aim of this study was to clarify the reasons for the lower dispersing performance of PCE and the synthesis of alternative dispersing agents based on the biopolymer starch to improve the workability of highly alkaline geopolymers. Furthermore, the focus of investigations was on the role of activator type and concentration as key parameters for geopolymer reaction and interaction of water-reducing agents. Therefore, in this study the conformation of three different types of PCE (MPEG: methacrylate ester, IPEG: isoprenol ether, and HPEG: methallyl ether) and synthesized starch admixtures in sodium and potassium hydroxide solutions (1 mol/L up to 8 mol/L) were studied. Furthermore, the dispersing performance, adsorption behavior, and influence on reaction kinetics in metakaolin-based geopolymer pastes were investigated in dependence on activator type and concentration. While the PCE superplasticizers show coiling and formation of insoluble aggregates at activator concentrations of 3 mol/L and 4 mol/L, the synthesized starch admixtures show no significant change in conformation. The cationic starch admixtures showed a higher dispersing performance in geopolymer pastes at all activator concentrations and types. The obtained adsorption isotherms depend strongly on the activator type and the charge density of the starch admixtures. The reaction kinetics of geopolymer pastes were not significantly influenced using the synthesized starch admixtures. Especially the cationic starch admixtures allow the reduction of liquid/solid ratios, which leads to higher flexural and compressive strengths. Full article

Copper selenide (Cu₂Se) has garnered significant attention as an exceptional thermoelectric material due to its high thermoelectric figure of merit (ZT values > 2). This remarkable efficiency makes it a strong candidate for various applications. However, the practical deployment of thermoelectrics often requires operation in an oxygen-containing atmosphere, which poses a significant challenge for Cu₂Se due to its environmental instability. This work investigates the environmental behavior of high-purity Cu₂Se, which was synthesized via a direct high-temperature reaction and spark plasma sintering (SPS). Our Temperature-Programmed Oxidation (TPO) studies determined that the onset of oxidation occurs at a temperature as low as 623 K. Further analysis using SEM–EDS confirmed the formation of copper oxides, Cu₂O and CuO. Critically, thermogravimetric analysis (TGA) revealed that the SeO₂ formation and sublimation process is an equally profound degradation mechanism, alongside copper oxidation, particularly within the optimal 673–973 K temperature range. Complementary XRD studies of samples annealed in air underscore this severe material degradation, which is especially devastating between 873 and 973 K. Ironically, this is the precise temperature window where Cu₂Se’s highest ZT values have been reported. Our findings demonstrate that the direct application of Cu₂Se in air is impractical, highlighting the urgent need for developing robust protective layers to unlock its full potential. Full article

Background: Plantar pressure distribution is a valuable tool for studying how the ground reaction forces are transmitted from the feet to the body and for detecting abnormalities in foot biomechanics. Objectives: The objective of this study was to determine the effect of the foot type (normal foot, flatfoot, and cavus foot) on plantar pressure distribution in healthy Mexican men and women aged from 3 to 74 years. Methods: A database of the plantar pressure distribution under dynamic and static conditions for both feet was studied using descriptive statistics, regression analysis, and statistical factorial design. The database contained images of the soles of the feet and pressure distribution of 996 persons between 3 and 74 years old (53.9% females and 46.1% males). Two different conditions were evaluated; the first was in a static condition, and the second was during walking. The Chippaux–Smirak Index (CSI) was used to classify the type of feet. Results: In the left foot, a linear regression analysis of the soles of the feet shows that the prevalence of flatfoot (p-value = 3.45 × E⁻⁵) decreased with age, while the normal foot (p-value = 7.39 × E⁻⁵) increased. When people are standing (static), the hindfoot (55.64 ± 18.80%) presents more pressure than the forefoot (45.18 ± 19.50%), while in dynamic, the forefoot (55.95 ± 13.36%) supports more pressure than the hindfoot (44.05 ± 13.36%). Similar behavior occurs in the right foot. A statistical factorial design ANOVA shows that the plantar pressure in the forefoot and hindfoot regions is significantly different (p < 0.05). Conclusions: The prevalence of flatfoot decreased with age, while the proportion of normal foot type increased. Under static conditions, the hindfoot bore more load than the forefoot, whereas under dynamic conditions, the forefoot bore more load than the hindfoot. This research contributes to generating a comprehensive database of reference values of the plantar pressure of different foot types in a Mexican population; this will be useful to podiatrists, clinicians, and physiotherapists for the analysis or treatment of abnormal foot postures. Full article

n-Pentanol, a promising biofuel, can reduce greenhouse gas emissions while remaining compatible with internal combustion engines. We present a reduced kinetic mechanism comprising 66 species and 292 reactions that captures both high- and low-temperature ignition and flame propagation dynamics for this fuel. The mechanism, developed by integrating a detailed n-pentanol sub-mechanism with the San Diego mechanism and applying sensitivity and steady-state approximations criteria as reduction strategies, accurately reproduces key phenomena, including the negative temperature coefficient behavior (NTC). Validation against experimental data for ignition delay times, laminar flame speeds, and speciation measurements in a jet-stirred reactor confirms its predictive capability across a wide range of conditions. Full article

Lithium plating (LP), as a specific degradation mechanism in lithium-ion batteries (LIBs), has been thoroughly investigated regarding formation conditions and potential safety hazards, but it is yet unknown how this effect influences the mechanical properties of batteries in the case of mechanical deformation. To address this issue, pouch cells used in EVs were artificially aged (AA) to a state of health of 80–82% in conditions that predominantly cause the formation of LP. These cells were subjected to a mechanical abuse load, and safety-relevant parameters, such as tolerated deformation level, failure force, and the process of thermal runaway (TR), were analyzed and compared with respective fresh (F) and aged cells of the same type. Complementary microscopy analyses were carried out to compare the found changed mechanical response with the different layer morphology caused by LP. The tests did exhibit a significantly different mechanical response of cells in the three states but also clearly altered short-circuiting behavior. The tolerated peak force at discharge state dropped by −28% and at charge state by −37% compared to fresh cells, while the deformation at failure slightly increased by +6% for the AA cells. A clear reduction in stiffness (−16%) of the LP cells was attributed to the formed layer, identified as mossy LP. The significantly stronger voltage drop at failure, seen for the LP cells, was associated with severe exothermal reactions of LP in contact with air and moisture during TR. This study revealed the strong influence of LP on the mechanical properties of LIBs. However, the transferability of the findings to other cell chemistries or formats is unclear, emphasizing the need for further investigations in this research field. Full article

Light pollution is becoming more widespread every year, accompanied by the active use of LED lighting. Currently, the ability of organisms to adapt to this pollution and the potential impact of LED lighting of different color temperatures and intensities on organisms remains poorly understood. In this study, we aimed to find out how long-term light pollution affects the behavior of amphipods Gammarus lacustris, and to compare their locomotor activity under different lighting conditions, taking into account the factor of shelter from light. The response of individuals was compared in group and individual experiments under daylight, without light, warm and cold LED light up to 30 lx. The individuals were from two populations: the first is not exposed to light pollution (lake No. 14), while the second is affected (the Angara River within the city of Irkutsk). The locomotor activity of amphipods was assessed in daylight, without light, warm and cold light of 2–2.5 lx and 10–11 lx in the presence and absence of shelters from light. As a result of the experiments, adaptive changes in the reaction of G. lacustris to warm light were identified in individuals from the Angara River. The importance of LED light color temperature and warm light intensity in determining amphipod response to light was also confirmed. It was found that warm and cold light have different effects on the behavior of G. lacustris, and the presence of shelters from light can reduce the negative impact of light pollution in natural conditions. Full article

In 2023, 95.5 million Europeans were aged over 65, falling within the definition of the “elderly population”. According to statistics, this number will rise to 129.8 million by 2050, making Europe the oldest continent in the world. One of the consequences of such growth is a sharp increase in the number of elderly drivers. Although they have more experience, which can positively impact road safety, their performance and health generally decline, limiting some of the physical and mental abilities required for safe vehicle control. The main objective of this research was to shed light on the behavior of elderly drivers by comparing three different drivers’ age groups: young, middle-aged and elderly drivers. Based on analysis of road accidents involving elderly drivers, the road safety situation for elderly drivers in Slovenia was highlighted, a questionnaire was developed to understand how elderly drivers perceive traffic, and an experiment was conducted where 30 volunteers were tested using a driving simulator and eye-tracking glasses. Objective driving and gaze behavior data were obtained, and very different performance was found among the three age groups, with elderly drivers having poorer reaction times and overlooking many elements compared to younger drivers. Full article

Background/Objectives: This study presents Co.Ge. a Cognitive Generative digital platform for cognitive testing. We describe its architecture and report a pilot study. Methods: Co.Ge. is modular and web-based (Laravel-PHP, MySQL). It can be used to administer a variety of validated cognitive tests, facilitating administration and scoring while capturing Reaction Times (RTs), trial-level responses, audio, and other data. Co.Ge. includes a study-management dashboard, Application Programming Interfaces (APIs) for external integration, encryption, and customizable options. In this demonstrative pilot study, clinical and non-clinical participants completed an Auditory Verbal Learning Test (AVLT), which we analyzed using accuracy, number of recalled words, and reaction times as outcomes. We collected ratings of user experience with a standardized rating scale. Analyses included Frequentist and Bayesian Generalized Linear Mixed Models (GLMMs). Results: Mean ratings of user experience were all above 4/5, indicating high acceptability (n = 30). Pilot data from AVLT (n = 123, 60% clinical, 40% healthy) showed that Co.Ge. seamlessly provides standardized clinical ratings, accuracy, and RTs. Analyzing RTs with Bayesian GLMMs and Gamma distribution provided the best fit to data (Leave-One-Out Cross-Validation) and allowed to detect additional associations (e.g., education) otherwise unrecognized using simpler analyses. Conclusions: The prototype of Co.Ge. is technically robust and clinically precise, enabling the extraction of high-resolution behavioral data. Co.Ge. provides traditional clinical-oriented cognitive outcomes but also promotes complex generative models to explore individualized mechanisms of cognition. Thus, it will promote personalized profiling and digital phenotyping for precision psychiatry and rehabilitation. Full article

Effective ablative thermal protection systems are essential for ensuring the structural integrity of hypersonic vehicles subjected to extreme aerothermal loads. However, the microscopic reaction mechanisms at the gas–solid interface, particularly under non-equilibrium high-enthalpy conditions, remain poorly understood. This study employs reactive molecular dynamics (RMD) simulations with the ReaxFF-C/H/O force field to investigate the atomic-scale ablation behavior of a graphene-based knitted graphene structure impacted by atomic oxygen (AO). By systematically varying the AO incident kinetic energy (from 0.1 to 8.0 eV) and incidence angle (from 15° to 90°), we reveal the competing interplay between catalytic recombination and ablation processes. The results show that the catalytic recombination coefficient of oxygen molecules reaches a maximum at 5.0 eV, where surface-mediated O₂ formation is most favorable. At higher energies, the reaction pathway shifts toward enhanced CO and CO₂ production due to increased carbon atom ejection and surface degradation. Furthermore, as the AO incidence angle increases, the recombination efficiency decreases linearly, while C-C bond breakage intensifies due to stronger vertical energy components. These findings offer new insights into the anisotropic surface response of knitted graphene structures under hyperthermal oxygen exposure and provide valuable guidance for the design and optimization of next-generation thermal protection materials for hypersonic flight. Full article

The potent sensitizer PPD is considered a key sensitizer in hair dye contact allergy. Modification of its molecular structure to 2-methoxymethyl-p-phenylenediamine (ME-PPD) reduces its skin sensitizing potency. We investigated the usage, behavior, and tolerance profile of ME-PPD-containing professional hair color products in a specifically tailored proactive market surveillance program in hairdresser salons across 5 countries. Hairdressers completed record cards for their clients, which were evaluated at the end of the program. 497 individuals received in total 2461 hair color treatments with ME-PPD-containing hair color. Feedback on compatibility was provided for 194 individuals: 6 individuals reported intolerance reactions, which were assessed as likely allergic contact dermatitis (2), likely irritation (2), or were unassessable (2); none of these reactions were severe or serious. Mild discomfort was reported by 46 individuals, while 142 individuals explicitly reported good tolerance to the ME-PPD-containing hair color. A total of 27 individuals applied ME-PPD-containing hair color more than 15 times (long-term tolerability). The study confirms good tolerability of ME-PPD-containing hair color. This is consistent with the primary prevention benefit of ME-PPD in terms of significantly reduced risk of skin sensitization induction and the reduced severity of elicitation reactions for all hair dye users. Full article

Immune cells play a pivotal role in orchestrating tissue repair, executing functions such as debris clearance, extracellular matrix remodeling, and modulation of cytokine secretion profiles. However, when their activity is dysregulated or inadequately directed, these same processes can give rise to chronic inflammation and foreign body reactions (FBR), ultimately leading to fibrosis and compromised biomaterial performance. The immunological landscape following injury or biomaterial implantation is profoundly influenced by the physicochemical properties of material surfaces. By strategically tailoring these surface characteristics, it becomes possible to modulate immune cell responses—governing their adhesion, recruitment, proliferation, polarization, and cytokine expression patterns. This review elucidates the multifaceted roles of immune cells in tissue repair and their dynamic interactions with implanted biomaterials. It then explores how specific surface attributes—such as topography, chemistry, stiffness, and wettability—influence immune behavior. Particular emphasis is placed on recent advances in surface modification techniques aimed at engineering next-generation biomaterials that mitigate adverse immune responses while actively promoting regenerative healing. The review concludes by offering critical insights into the future of immunomodulatory biomaterial design, highlighting both emerging opportunities and persisting challenges in the field. Full article