Microfluidic redox flow batteries (& micro;RFBs) have emerged as promising membrane-free energy storage systems due to their enhanced mass transport characteristics and precise control of microscale fluid dynamics; however, their performance remains strongly constrained by electrolyte crossover and flow instability. Here, we systematically investigate the coupled effects of microchannel geometry, flow rate, and electrode spacing on the hydrodynamic and electrochemical behavior of a graphene-based & micro;RFB employing a Zn/Mn redox couple. A three-dimensional computational fluid dynamics model was developed to analyze co-laminar flow and species transport within rectangular microchannels, revealing that channel dimensions and operating conditions critically govern micromixing, reactant utilization, and energy conversion efficiency. Excessive mixing, driven by longer residence times and specific channel aspect ratios, was found to accelerate electrolyte crossover and reduce electrochemical performance. Using a Taguchi design-of-experiments approach, an optimized microchannel geometry was identified and subsequently validated through fluorescence-based micromixing measurements. The electrode spacing plays a decisive role in device performance; although reducing the inter-electrode gap lowers ohmic resistance, excessively narrow spacing enhances cross-stream species transport and activation losses. The findings establish fundamental design principles for optimizing & micro;RFB architectures and provide a robust framework for developing high-performance, scalable, and flexible microfluidic energy storage systems.
Architectural education requires students to integrate design thinking with technical knowledge, yet building construction and building component design courses are often structured around instructor-centered knowledge transmission in which technical information precedes and remains partially detached from design exploration. Although integrated, experiential, and problem-based approaches have sought to bridge this divide, less attention has been given to when formal technical instruction enters the design learning process and how this timing may shape students’ engagement with technical-design problems. This study proposes a phased and guided pedagogical framework that treats the timing of formal technical instruction as a deliberate instructional design variable in building construction education. The framework is organized through three successive stages: initial problem exploration, structured technical guidance, and the revision of initial design decisions following technical instruction. The framework is conceptually articulated through a stair and vertical circulation module within an undergraduate Building Component Design course, where spatial, ergonomic, regulatory, structural, and representational considerations must be addressed simultaneously. Traditional lecture-based, discovery-based, and phased and guided configurations are used as contrasting pedagogical structures to clarify differences in the sequencing of technical knowledge rather than to establish comparative performance outcomes. The proposed framework does not claim pedagogical superiority and has not yet been empirically validated. Instead, it provides a conceptual and methodological basis for future investigation of technical reasoning, design decision-making, reflective revision, and knowledge transfer. Its underlying sequence is intended to be adaptable across different building components and stages of architectural education, while also accommodating contemporary access to technical information through digital resources and generative AI.
A novel fluorenylidene-bridged bis-BODIPY hybrid compound (FLB-Bis-BDPY) was designed and synthesized by integrating a diphenylbenzofulvene (DPBF) core with emissive BODIPY chromophores. The molecular structure was confirmed by spectroscopic techniques and single-crystal X-ray diffraction analysis, revealing a highly twisted yet conformationally rigid molecular framework together with pi-pi stacking supported by C-H & sdot;& sdot;& sdot;pi and C-H & sdot;& sdot;& sdot;F interactions. The photophysical properties of FLB-Bis-BDPY were systematically investigated by UV-Vis absorption and fluorescence spectroscopy in solution, together with aggregation studies in THF/H2O mixtures and solid-state spectroscopic measurements. The compound exhibited fluorescence quenching with increasing water fraction, indicating aggregation-caused quenching (ACQ) behavior rather than aggregation-induced emission (AIE). In contrast, the solid state remained emissive, showing a red-shifted emission consistent with its ordered crystalline packing, and diffuse reflectance spectroscopy provided further insight into its condensedphase optical behavior. Taken together, the crystallographic and spectroscopic results indicate that the molecular organization in the crystalline state differs from the aggregates formed in water-rich media, giving rise to distinct emission behaviors. Overall, this work contributes to a better understanding of the relationship between molecular structure, crystal packing, aggregation behavior, and photophysical properties in fluorene-BODIPY hybrid systems.
In this study, water-soluble and carrying biologically active molecule tripodal compounds based on a cyclotriphosphazene platform (4a, 5a, 4b, and 5b) were successfully designed and synthesized. The structures of the compounds were characterized using NMR (31P, 1H, and 13C) spectroscopy, mass spectroscopy, and elemental analyses. Their biological activities in vitro were tested in normal colon (CCD-18Co), primary colorectal cancer (Caco-2) and metastatic colorectal cancer (SW-620) cell lines. Compound 5a showed the lowest IC50 values among the synthesized derivatives and was chosen for further biological evaluation. Compound 5a induced cellcycle distribution changes and apoptosis in a cell line-dependent manner. Spectroscopic studies also showed that compound 5a interacted with CT-DNA and BSA. However, the similar cytotoxicity of compound 5a to normal and colorectal cancer cells suggests low selectivity, which limits the conclusion regarding its therapeutic potential. The results indicate that the biological activity of cyclotriphosphazene derivatives could be modulated through structural modification of the cyclotriphosphazene platform and further structural optimization and mechanistic investigation are needed to improve the selectivity of these derivatives toward cancer cells.
Voltage loss is widely used to monitor proton exchange membrane fuel cell (PEMFC) aging, but it provides limited information during load-varying operation by combining irreversible degradation with reversible hydration, thermal, and recovery effects. To address this non-intrusively, a voltage-transient-based method is applied to an automotive dynamic load dataset (3076 cycles, 1008 h) using standard 1-Hz operational data. Natural current steps were treated as diagnostic excitations. A region-based comparison first identified the most stable operating segment for transient extraction. These voltage transients were decomposed into three time-domain quantities: fast apparent resistance, relaxation resistance change, and characteristic relaxation time. The analysis revealed that aging fundamentally alters the resistance-relaxation structure of the current-step response. Furthermore, comparison with periodic polarization curves showed that the 1-Hz apparent resistance growth strongly tracks the increase in steady-state polarization-derived resistance. A Dynamic Response Index (DRI) was introduced to summarize this coupled change as a relative descriptor referenced to the initial response state. Within the scope of this proof-of-concept study, the proposed method relies exclusively on routinely recorded time, current, and voltage data, extracting aging-sensitive descriptors without dedicated electrochemical characterization hardware.
