Fundamental Behavior Research Articles

Exciton Dissociation and Long‐Lived Delayed Components in High‐Efficiency Quasi‐Two‐Dimensional Green Perovskite Light‐Emitting Diodes

AbstractQuasi‐two‐dimensional (quasi‐2D) perovskites, consisting of multi‐quantum wells (MQWs) separated by organic intercalating cations, exhibit high luminescence efficiency while the photophysical processes involved remain partially obscure due to the uncertainty of the MQWs structure. Herein, a synergetic dual‐additive strategy is adopted to prepare quasi‐2D perovskite films, where 18‐crown‐6 and tris(4‐fluorophenyl)phosphine oxide are utilized to suppress the formation of low‐dimensional perovskites, diminish defect density, and enhance photoluminescence quantum yield to 93.7%. Notably, a long‐lived delayed component, spanning hundreds of microseconds, is identified for the first time in perovskite emitters, which correlates with exciton dissociation and recombination, and the differences in temperature‐dependent radiative lifetime of the delayed components match with the luminescence properties. Finally, benefiting from lower trap density and more efficient energy‐funneling, green PeLEDs treated with dual additives have achieved a high external quantum efficiency of 28.9% and a commendable operating half‐lifetime of 17.8 h at an initial brightness of 500 cd m−2. The observation of the long‐lived delayed components, coupled with insights into exciton dissociation, provides a profound and comprehensive understanding of the fundamental carrier behavior in perovskite emitters and establishes a direct correlation between the properties of perovskite emitters and their photophysical processes.

III–V heterostructure tunnel field-effect transistor operation at different temperature regimes

Tunnel field-effect transistors (TFETs) are a potential alternative to MOSFETs for low-temperature electronics. We provide an in-depth experimental characterization of TFETs analyzing the fundamental physical behavior at different temperature regimes. TFET characteristics from 13 to 300 K both in forward and reverse bias are discussed by employing a variation in InAs/InGaAsSb/GaSb heterojunction vertical nanowire devices. Evaluation of the TFET Negative Differential Resistance (NDR) characteristics at different temperatures is established as a technique to probe the dopant incorporation. It is observed that the temperature dependence of the Fermi degeneracy and Fermi-Dirac distribution largely influences the transistor performance at each operating temperature. Our investigation reveals that the TFETs demonstrate lower subthreshold swing than the physical limit of MOSFETs above 125 K. For low-temperature applications, the devices can be operated down to a low operating bias of 0.1 V, while for high temperature, a larger bias of 0.3 V is preferred.

Polypiperazine-Based Micelles of Mixed Composition for Gene Delivery

We introduce a novel concept in nucleic acid delivery based on the use of mixed polymeric micelles (MPMs) as platforms for the preparation of micelleplexes with DNA. MPMs were prepared by the co-assembly of a cationic copolymer, poly(1-(4-methylpiperazin-1-yl)-propenone)-b-poly(d,l-lactide), and nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers. We hypothesize that by introducing nonionic entities incorporated into the mixed co-assembled structures, the mode and strength of DNA binding and DNA accessibility and release could be modulated. The systems were characterized in terms of size, surface potential, buffering capacity, and binding ability to investigate the influence of composition, in particular, the poly(ethylene oxide) chain length on the properties and structure of the MPMs. Endo–lysosomal conditions were simulated to follow the changes in fundamental parameters and behavior of the micelleplexes. The results were interpreted as reflecting the specific structure and composition of the corona and localization of DNA in the corona, predetermined by the poly(ethylene oxide) chain length. A favorable effect of the introduction of the nonionic block copolymer component in the MPMs and micelleplexes thereof was the enhancement of biocompatibility. The slight reduction of the transfection efficiency of the MPM-based micelleplexes compared to that of the single-component polymer micelles was attributed to the premature release of DNA from the MPM-based micelleplexes in the endo–lysosomal compartments.

Single-Molecule Spectral Fluctuation Originates from the Variation in Dipole Orientation Connected to Accessible Vibrational Modes.

Fluctuation in fluorescence emission of an immobilized single molecule is typically ascribed to the chromophore's intrinsic structural conformations and the influence of local environmental factors. Despite extensive research since its initial observation, a direct connection between these spectral fluctuations and the rearrangement of emission dipole orientations has remained elusive. Here, we elucidate this fundamental molecular behavior and its underlying mechanisms by employing unique single-molecule multidimensional tracking to simultaneously monitor both the emission spectrum and the three-dimensional dipole orientation of individual fluorophores. We present compelling evidence demonstrating a correlation between spectral fluctuations and dipolar rearrangements at room temperature. Our observations reveal that variations in the radiative relaxation probabilities among different vibronic emission bands, coupled with the interaction of associated vibrational modes, drive these spectral fluctuations. We identify significant out-of-plane dipole reorientations during pronounced spectral fluctuations, commonly known as spectral jumps, which primarily arise from transitions between dominant vibrational modes. Furthermore, we emphasize the potential for constructing vibrational spectra and optical nanoscopy with vibrational specificity, leveraging the vibronic emissions from single emitters.

Intermolecular Anionic Mixed‐Valence and π‐Dimer Complexes of ortho‐Pentannulated Bisazacoronene Diimide

AbstractThis study reports the serendipitous discovery of intermolecular anionic mixed‐valence (MV) and π‐dimer species in ortho‐pentannulated BisAzaCoroneneDiimides (BACDs) during their electrochemical reduction in a non‐aqueous solvent. A library of nitrogen‐containing extended PDIs was synthesized via an aza‐benzannulation reaction followed by a Pd‐catalysed ortho‐pentannulation reaction. Ortho‐pentannulated BACDs revealed strong aggregation abilities in solution. Concentration‐dependent UV/Vis absorption spectra, variable temperature 1H NMR experiments, and atomic force microscopy coupled to molecular dynamics support their self‐assembly into columnar aggregates. Cyclic voltammetry experiments in dichloromethane reveal prominent splitting of the first reduction wave, attributed to the formation of unprecedented intermolecular anionic MV and π‐dimers in organic solvent. These species were thoroughly characterized by real‐time spectroelectrochemistry, electrochemical simulations and theoretical calculations. Remarkably, this work underscores the tuneable nature of AzaBenzannulatedPerylene Diimides (AzaBPDIs) and BACDs, emphasizing their potential as a promising scaffold for designing supramolecular materials with long‐range radical anion delocalization. The observation of this phenomenon provides insights into the fundamental behaviour of supramolecular organic semiconductors, thereby paving the way for the development of novel electronic devices and electron‐deficient materials.

Intermolecular Anionic Mixed-Valence and π-Dimer Complexes of ortho-Pentannulated Bisazacoronene Diimide.

This study reports the serendipitous discovery of intermolecular anionic mixed-valence (MV) and π-dimer species in ortho-pentannulated BisAzaCoroneneDiimides (BACDs) during their electrochemical reduction in a non-aqueous solvent. A library of nitrogen-containing extended PDIs was synthesized via an aza-benzannulation reaction followed by a Pd-catalysed ortho-pentannulation reaction. Ortho-pentannulated BACDs revealed strong aggregation abilities in solution. Concentration-dependent UV/Vis absorption spectra, variable temperature 1H NMR experiments, and atomic force microscopy coupled to molecular dynamics support their self-assembly into columnar aggregates. Cyclic voltammetry experiments in dichloromethane reveal prominent splitting of the first reduction wave, attributed to the formation of unprecedented intermolecular anionic MV and π-dimers in organic solvent. These species were thoroughly characterized by real-time spectroelectrochemistry, electrochemical simulations and theoretical calculations. Remarkably, this work underscores the tuneable nature of AzaBenzannulatedPerylene Diimides (AzaBPDIs) and BACDs, emphasizing their potential as a promising scaffold for designing supramolecular materials with long-range radical anion delocalization. The observation of this phenomenon provides insights into the fundamental behaviour of supramolecular organic semiconductors, thereby paving the way for the development of novel electronic devices and electron-deficient materials.

Study on electrochemical anodization initiation and progression of binderless tungsten carbide (WC) through experimentation and simulation

This article explores the electrochemical anodization of binderless tungsten carbide (WC) using computational simulations and experimental methods. It aims to comprehend the complex relationship between anodization time, surface roughness, elemental composition, and current behavior on polished and non-polished substrates. COMSOL Multiphysics models provide the initial findings by meticulously mapping the electrolyte's potential and the current density vectors. These simulations reveal the fundamental electrochemical behaviors anticipated during anodization, particularly emphasizing the regions near the anode expected to undergo anodization. Experimental observations confirm the simulation results, showcasing how non-polished WC surfaces, replete with inherent imperfections, undergo anodization characterized by fluctuating current densities and compositional changes, highlighting the profound influence of surface defects on electrochemical processes. On the other hand, when WC substrates are polished, they show a more consistent and controlled anodization process. This suggests a close connection between the occurrence of anodization and the surface treatment, ultimately influencing the effectiveness of anodization. This comprehensive study, which combines simulation and experimentation, greatly enhances the understanding of the electrochemical anodization of WC. It suggests potential methods for enhancing surface modifications to expand the range of applications for WC, particularly in precision glass molding, aerospace, and medical industries.

Frozen and unfrozen moisture content estimation in coral calcareous sand during artificial freezing

In tropical areas where coral calcareous sands are prevalent, artificial freezing techniques are frequently employed during construction. However, the fundamental thermodynamic behaviors and moisture dynamics of calcareous sands under freezing conditions are poorly understood. Therefore, we conducted laboratory tests and developed a numerical model to capture the total moisture, liquid water, and ice contents of calcareous sand during artificial freezing. The thermal fiber Bragg grating (T − FBG) and frequency − domain reflectometry methods were used in the study. Freezing characteristic curves were quantitatively analyzed with taking into account the initial moisture content and ambient temperature. The results indicate that T − FBG effectively estimates the total moisture content in unfrozen and frozen calcareous sand, as well as ice content in frozen soil, with less than 0.029 m3/m3 error. Ice melting induced by T − FBG heating is affected by the initial moisture content, heating duration, power, and ambient temperature. However, the maximum change is below 0.008 m3/m3, which is negligible. The van Genuchten model accurately describes the liquid moisture–temperature relationship of unsaturated calcareous sand, with an R2 exceeding 0.98. The residual–initial moisture content relationship follows a quadratic function. During freezing, the temperature reduction aligns with the Kozlowski model, and the liquid moisture–temperature relationship follows a cubic polynomial function.

Determination of Initial Data in the Time-Fractional Pseudo-Hyperbolic Equation

We examine a time-fractional pseudo-hyperbolic equation involving positive operators. We explore the determination of initial velocity and perturbation. It is demonstrated that these initial inverse problems are ill posed. Additionally, we prove that under certain conditions, the inverse problems exhibit well-posedness properties. Our focus is on developing a theoretical framework for these initial inverse problems associated with time-fractional pseudo-hyperbolic equations, laying the groundwork for future studies on numerical algorithms to solve these problems. This investigation is crucial for understanding the fundamental behavior of the equations under various initial conditions and perturbations. By establishing a rigorous theoretical framework, we pave the way for future research to focus on practical numerical methods and simulations. Our results provide a deeper insight into the mathematical structure of time-fractional pseudo-hyperbolic equations, ensuring that future computational approaches are built on a solid theoretical foundation.

Method of understanding for investigation of crack propagation trajectory and fracture aspects in dental cracks on view of fracture mechanics theories.

Current research introduces understanding of dental-cracks mechanistic with fundamental fracture behavior in natural-teeth and orthodontics including mode I crack under both tension and compression, mode II crack under both clockwise-shear and anticlockwise-shear and mixed-mode cracks under both compression-shear and tension-shear. It depends on experimental models of transparent-Plexiglas including pre-cracks of different orientations angle (b) based on fundamental theoretical fracture analysis with comparison. Problem-concept, cracking aspects of fracture-initiation, propagation-direction, fracture-increment length, critical external-load and fracture path are predicted experimentally and theoretically using directional fracture approach and directional strain-energy density theory. Tests are carried out for (36) samples for compression and tension in LEFM. Friction-resistance between crack-surfaces is considered with derivation of equations and charts. Negative stress-intensity factor (-KI) is developed for solving complicated problems of cracks under occlusal compression loads. The occlusal loads are compression and shear producing lateral tensile mixed mode cracks. The critical propagation angle (qc), critical propagation load (sc) and critical propagation envelope of stress intensity factors (KI-KII) are developed with respect to crack orientation angle (b) with comparisons. They are necessary to predict the fracture propagation early before teeth-failure. It helps for prevention and control of dental-cracks, correct-restoration, prosthodontics, orthodontics, and development of new dental-materials and technologies.

Fuel blend combustion for decarbonization

The utilization of fossil fuels is currently transforming to low-carbon or zero-carbon fuels, which is one of the solutions to global warming. Hydrogen and ammonia are regarded as promising zero-carbon fuels in power supply and transportation scenarios but the availability of hydrogen and their distinctly different chemical activity constrain their large-scale direct utilizations. Fuel blends with physical and chemical complementary are considered as the effective approaches in the utilization of hydrogen and ammonia because no significant modification to the existing end-user infrastructures is needed. This paper reports recent progress in the fundamental combustion behaviors of fuel blends, focusing on hydrogen-hydrocarbon blends and ammonia-hydrocarbon blends. Firstly, laminar flame behaviors, auto- and forced-ignition characteristics, and pollutant emissions of binary fuels containing hydrogen are reviewed, all of which are supplemented with a discussion on the governing hydrogen-enriched combustion chemistry. Subsequently, the hydrogen-enriched flame responses to the flow conditions are discussed, including the turbulent burning velocity and statistical structures, the flashback swirl flames, thermoacoustic instabilities, and the jet ignition characteristics; Furthermore, with the increasing concern over ammonia as a zero carbon fuel and its extremely weak reactivity, recent progress on combustion of fuel blends containing ammonia are also reviewed. The fundamental combustion chemistry studies including laminar burning velocity, the ignition delay times data collection, as well as the attempts for chemical kinetic modeling development for fuel blend with ammonia are presented. The literature reported ammonia containing blends of turbulent flame characteristics are presented. Finally, from an engineering point of view, examples using hydrogen blends in practical internal combustion engines and in gas turbines are introduced, including the topic of engine efficiency performance and pollutant emissions and different combustors for gas turbines. It is suggested that fuel blends with hydrogen or ammonia that potentially monitors the overall reactivity will be one realistic solution to de-carbonization, on the basis of current transportation and power generation systems.

Surface, micellization, and thermodynamic behavior of cetyltrimethylammonium bromide in sodium polystyrene sulfonate with and without methyl red in water–ethanol mixed solvent media at varying temperatures: A tensiometric analysis

In this study, we aim to systematically investigate the surface, micellization, and thermodynamic properties of Cetyl Trimethyl Ammonium Bromide (CTAB) in Sodium Polystyrene Sulfonate (NaPSS) solutions with and without methyl red (MR) dye in water–ethanol mixed solvent media (0, 0.1, 0.2, and 0.3 vol fraction of ethanol at 298.15 ± 0.2 K, 308.15 ± 0.2 K, and 318.15 ± 0.2 K. By employing surface tension measurements, we seek to uncover the effects of solvent composition, temperature, polyelectrolyte presence, and dye addition on the Critical Micelle Concentration (CMC) and other key surface and thermodynamic parameters. The CMC, slope (dγdlnC), and γCMC values determined from γ versus ln [CTAB] for the CTAB + NaPSS + MR diminish in contrast to the CTAB + NaPSS in the chosen solvent and the temperature range studied. However, with a rising temperature and ethanol volume fraction, the CMC value rises while the obtained γCMC values fall. Various surface and thermodynamic parameters like γCMC,Amin,Γmax, ΠCMC, adsorption efficiency (PC20), packing parameter (P), aggregation number (Nagg), micellization Gibbs’ energy (ΔGm0), adsorption of Gibbs’ energy (ΔGads0), effective Gibbs’ energy (ΔGeff0), minimum Gibbs’ energy (ΔGmin), and many other parameters have been determined, comparatively discussed, and analyzed for CTAB + NaPSS and CTAB + NaPSS + MR systems. This research provides a deeper understanding of the fundamental behaviors of these complex systems, their stability, and their feasibility, with potential implications for their practical applications in fields such as drug delivery, wastewater treatment, and the formulation of personal care products.

Atomic-scale revelation of Cu diffusion mechanism in high-performance Pr-doped 2:17-type SmCo magnets

The coercivity of 2:17-type SmCo magnets is mainly determined by the gradient distribution of Cu within the cell boundary phase. However, the fundamental migratory behavior and driving force causing such Cu distribution remains unclear. In this work, the phenomenon of Cu enrichment at the lamellar/intracellular interface is reported at the atomic scale, and a new Cu diffusion mechanism of 2:17-type SmCo magnets is proposed via combining microstructure characterization with first-principles calculation. Our study indicates that Cu will migrate from the intracellular phase to the lamellar/intracellular phase interface following the migration of twin boundary, and then diffuses further along the lamellar phase interface to the cell boundary, achieving the expected Cu-rich cell boundary structure. Doping Pr results in a reduction of Cu substitution energy in the lamellar phase, leading to a decreased driving force during the subsequent Cu diffusion. As a result, the Cu does not completely diffuse into the cell boundary phase there is Cu enrichment at the interface between lamellar and intracellular phases. The Cu concentration of the cell boundaries could be increased in 2:17-type SmCo magnets by reasonable designing the substitution energy difference of intracellular phase, lamellar phase and cell boundary phase that promote Cu diffusion to cell boundary. Our study sheds light on the control of Cu segregation in magnets and a new strategy for enhancing the magnetic performance of 2:17-type SmCo magnets.

Multimodal Hox5 activity generates motor neuron diversity

Motor neurons (MNs) are the final output of circuits driving fundamental behaviors, such as respiration and locomotion. Hox proteins are essential in generating the MN diversity required for accomplishing these functions, but the transcriptional mechanisms that enable Hox paralogs to assign distinct MN subtype identities despite their promiscuous DNA binding motif are not well understood. Here we show that Hoxa5 modifies chromatin accessibility in all mouse spinal cervical MN subtypes and engages TALE co-factors to directly bind and regulate subtype-specific genes. We identify a paralog-specific interaction of Hoxa5 with the phrenic MN-specific transcription factor Scip and show that heterologous expression of Hoxa5 and Scip is sufficient to suppress limb-innervating MN identity. We also demonstrate that phrenic MN identity is stable after Hoxa5 downregulation and identify Klf proteins as potential regulators of phrenic MN maintenance. Our data identify multiple modes of Hoxa5 action that converge to induce and maintain MN identity.

The transcriptome of playfulness is sex-biased in the juvenile rat medial amygdala: a role for inhibitory neurons.

Social play is a dynamic behavior known to be sexually differentiated; in most species, males play more than females, a sex difference driven in large part by the medial amygdala (MeA). Despite the well-conserved nature of this sex difference and the importance of social play for appropriate maturation of brain and behavior, the full mechanism establishing the sex bias in play is unknown. Here, we explore "the transcriptome of playfulness" in the juvenile rat MeA, assessing differences in gene expression between high- and low-playing animals of both sexes via bulk RNA-sequencing. Using weighted gene co-expression network analysis (WGCNA) to identify gene modules combined with analysis of differentially expressed genes (DEGs), we demonstrate that the transcriptomic profile in the juvenile rat MeA associated with playfulness is largely distinct in males compared to females. Of the 13 play-associated WGCNA networks identified, only two were associated with play in both sexes, and very few DEGs associated with playfulness were shared between males and females. Data from our parallel single-cell RNA-sequencing experiments using amygdala samples from newborn male and female rats suggests that inhibitory neurons drive this sex difference, as the majority of sex-biased DEGs in the neonatal amygdala are enriched within this population. Supporting this notion, we demonstrate that inhibitory neurons comprise the majority of play-active cells in the juvenile MeA, with males having a greater number of play-active cells than females, of which a larger proportion are GABAergic. Through integrative bioinformatic analyses, we further explore the expression, function, and cell-type specificity of key play-associated modules and the regulator "hub genes" predicted to drive them, providing valuable insight into the sex-biased mechanisms underlying this fundamental social behavior.

Functional diversity along the anteroposterior axis of the ventromedial hypothalamus.

Innate behaviors ensure animal survival and reproductive success. Defending their territory, escaping from predators or mating with a sexual partner, are fundamental behaviors determining the ecological fitness of individuals. Remarkably, all these behaviors share a common neural substrate, as they are under the control of the ventromedial hypothalamus (VMH). Decades of research have contributed to understanding the exquisite diversity of functional ensembles underlying the wide array of functions that the VMH carries out. These functional ensembles are usually distributed throughout the dorsoventral and mediolateral axes of this nucleus. However, increasing evidence is bringing to attention the functional diversity of the VMH across its anteroposterior axis. In this review, we will overview our current understanding of how different ensembles within the VMH control a wide array of animal behaviors, emphasizing the newly discovered roles for its anterior subdivision in the context of conspecific self-defense.

BiFeO3/SrTiO3 superlattice-like based ferroelectric memristors with pronounced artificial synaptic plasticity

Memristors are attracting widespread attention for their multilevel storage capacity and synaptic learning ability. Ferroelectric memristors, with resistance switching based on polarization reversal, offer uniform threshold voltage and analog resistance modulation. By preparing superlattice-like ferroelectric films, the ferroelectric properties can be significantly enhanced, thereby improving the memristive characteristics. In this study, the constructed BiFeO3/SrTiO3 (BFO/STO) superlattice-like structure increases the remanent polarization by approximately 200 % compared to a single-layer BFO structure, as well as the dramatically enhanced resistance switching performance. Notably, the Pt/(BFO/STO)2/NSTO device shows superior storage performance, with extended endurance (1000 cycles), reliable retention (10000 seconds) and fundamental synaptic behaviors being demonstrated. Finally, simulations for handwritten digit recognition classification, involving modulation of conductance to vary synaptic weights, achieve an impressive accuracy of 87.46 %, showing great promising for applications in information storage and neuromorphic computing.

Mechanotransduction alterations in tissue-engineered tumor models for new drug interventions

Mechanotransduction is a collection of pathways in which the cells reprogram themselves by sensing mechanical stimuli. Cells use biological cues to interpret the physiological stresses and respond to changing conditions by modifying the cellular and ECM architecture. This feedback loop regulates a variety of cellular processes, including migration, growth, differentiation, and death, which is essential for the network stability to work together in a coordinated manner. The effect of stress on cancer progression and the role of mechanics as a critical inducer in determining the cancer cell fate has been studied. This review discusses the progression of cancer cells to epithelial to mesenchymal transitions. It examines tumor microenvironment models, such as spheroids, bio-printing, and microfluidics, and how they recapitulate the tumor microenvironment. These offer certain benefits and help replicate the fundamental behavior in vivo conditions. We further discuss mechanosensing, the associated signaling molecules, and how it modulates the cancer drug resistance and transduction pathways that implicate cancer treatment. The difficulties with the existing methods and the prospects for additional study that may be applied in this area are discussed, and how they allow for new therapeutic development.

A multiscale discrete fiber model of failure in heterogeneous tissues: Applications to remodeled cerebral aneurysms

Damage-accumulation failure models are broadly used to examine tissue property changes caused by mechanical loading. However, damage accumulation models are purely phenomenological. The underlying justification in using this type of model is often that damage occurs to the extracellular fibers and/or cells which changes the fundamental mechanical behavior of the system. In this work, we seek to align damage accumulation models with microstructural models to predict alterations in the mechanical behavior of biological materials that arise from structural heterogeneity associated with nonuniform remodeling of tissues. Further, we seek to extend this multiscale model toward assessing catastrophic failure events such as cerebral aneurysm rupture. First, we demonstrate that a model made up of linear elastin and actin and nonlinear collagen fibers can replicate bot the pre-failure and failure tissue-scale mechanics of uniaxially-stretched cerebral aneurysms. Next, we investigate how mechanical heterogeneities, like those observed in cerebral aneurysms, influence fiber and tissue failure. Notably, we find that failure occurs and the interface between regions of high and low material stiffness, suggesting that spatial mechanical heterogeneity influences aneurysm failure behavior. This model system is a step toward linking structural changes in growth and remodeling to failure properties.

Vertical diaphragms for moment connection of thin-walled CFT column to steel beam

A vertical diaphragm scheme is proposed to connect the concrete-filled thin-walled steel tube (thin-walled CFT) column and steel beam, as an alternative to horizontal diaphragm connections: dual vertical diaphragms are installed inside the steel tube, considering poor out-of-plane resistance of the thin tube wall. For verification of the moment connection, two experimental programs were carried out. In the first experiment, an ultimate tension test was conducted for flange-to-column connections, to identify the fundamental behavior of the proposed connection (i.e., strength, failure mode, and out-of-plane deformation). The design parameters, such as the thickness, number, and continuity of the vertical diaphragms, were considered. All the test specimens exceeded the design strengths based on a yield line model (i.e., the tensile capacity-to-demand ratios ranged Tu/TYL = 1.11–1.31), without early fracture of welded joints. In particular, at the design strengths, the tube out-of-plane deformations were more limited with the heavier diaphragms. In the second experiment, beam-to-column connections using prototype I-section steel were tested under cyclic flexure, to verify the joint flexural strength and rigidity as well as the seismic performance. The beam-to-column connections failed by the beam flexural mechanism, whereas damage was marginal at the joint wall (i.e., the flexural capacity-to-demand ratios ranged Mu/Mj = 0.87–1.09). Overall, the dual diaphragms were effective in achieving rigid (full-strength) connections with satisfactory plastic rotation of the beam. On the basis of the test results, design considerations were recommended for the vertical diaphragm connections.