Cyclic Process Research Articles

Roles of different Ni-Si interactions in methane combustion under oscillating temperature conditions

The silicon- modified nickel oxide catalysts with the same compositions but distinct Ni-Si interactions were obtained via different synthesis routes and utilized for methane combustion under conditions of oscillating temperatures. For catalysts prepared by co-grinding, amorphous SiO2 was dispersed on the surface of large NiO crystallites. During high-temperature calcination or reactions, the crystallization of SiO2, coupled with the sintering or decomposition of NiO crystallites, led to the inferior catalytic activity and stability. Interactions between Ni and Si species were enhanced in catalysts synthesized by precipitation. The Si species was incorporated into the NiO lattice to inhibit the growth of NiO crystallites and to generate nickel silicate species under thermal treatments. The small NiO crystallites provided more Ni3+ and active oxygen species for methane activation and oxidation, while the bulk nickel silicate species played a pivotal role in improving thermal stability, conjointly provoking excellent catalytic performance in cyclic heating–cooling tests between 180 and 800 °C. This study offers new insights into the design of metal oxide composites for catalytic applications.

Initial experimental testing of a hybrid solar-dish Brayton cycle for combined heat and power (ST-CHP)

The Solar Turbo Combined Heat and Power (ST-CHP) project developed a novel solar-gas hybrid prototype for combined heat and power generation in Pretoria, South Africa. A vacuum-membrane faceted parabolic dish with a large-pipe open-cavity receiver was coupled to a counterflow recuperator, a combustion chamber, a micro gas turbine with air bearings and a phase change thermal energy storage unit containing solar salts. This study aimed to validate the electrical output of the full-scale dish-Brayton prototype, addressing the literature gap on micro-scale dish-Brayton plants' in-field power generation. Solar hybridization of micro gas turbine technology can significantly reduce combustion fuel consumption. A performance analysis under relevant conditions revealed a late afternoon micro gas turbine output intermittently peaking at 0.4kWe and subsequently stabilizing to a steady state of 0.145kWe at 130krpm. A SimuPact numerical model and an analytical model supplemented the telemetry data to reduce interference in the experimental setup and fully characterize the ST-CHP prototype performance, estimating a steady-state turbine isentropic efficiency of 57%, a compressor efficiency of 71% and a collector efficiency of 17% due to the late afternoon steady-state point. Analytical case studies revealed that fuel savings of between 12% and 33% at the combustion chamber were achievable from the solarized preheating. A subsequent test of the micro gas turbine without solar hybridization or a recuperator resulted in 1.05kWe being generated. The study confirms the dish-Brayton prototype's viability for combined heat and power generation, producing an initial full-scale performance characterisation during in-field testing, and highlighting the impact of solar hybridization on turbine electrical output. Optical efficiency, insulation effectiveness, pressure losses, and turbine operating conditions were identified as critical areas requiring optimization to improve electrical output. The lessons learned, and the calibrated numerical model may be used to optimize the performance of the dish-Brayton plant in future work. The successful in-field full-scale power generation of the ST-CHP prototype adds to the available literature on dish-Brayton technology and brings the technology closer to a commercial product.

Effect of in-situ emulsification on CO2/N2-based cyclic solvent injection process for enhancing heavy oil recovery and CO2 storage

Surfactant-assisted CO2/N2-based CSI (SA CO2/N2-CSI) process emerges as a strategic solution to migrate the high energy consumption and carbon intensity associated with traditional thermal operations for heavy oil recovery. However, the interphase mass transfer makes the emulsification behavior in this process complex. In this study, the effect of in-situ emulsification on CO2/N2-CSI is assessed using a sandpack model and microchannel chip. Mesoscopically, SA CO2/N2-CSI outperforms conventional CO2/N2-CSI in terms of both oil recovery and CO2 storage, owing to the enhanced CO2 diffusion, oil solubilization, and foamy oil stability due to emulsification. Microscopically, the impact of emulsifier injection rate on oil removal efficiency in the dead-end pores becomes negligible when the injection rate exceeds 50 nL/min, providing insights to the emulsification mechanisms underlying the optimal pressure depletion rate (9 kPa/min) in SA CO2/N2-CSI. This study demonstrates the applicability of the SA CO2/N2-CSI in fostering sustainable heavy oil production and CO2 storage.

Computational Issues of Quantum Heat Engines with Non-Harmonic Working Medium.

In this work, we lay the foundations for computing the behavior of a quantum heat engine whose working medium consists of an ensemble of non-harmonic quantum oscillators. In order to enable this analysis, we develop a method based on the Schrödinger picture. We investigate different possible choices on the basis of expanding the density operator, as it is crucial to select a basis that will expedite the numerical integration of the time-evolution equation without compromising the accuracy of the computed results. For this purpose, we developed an estimation technique that allows us to quantify the error that is unavoidably introduced when time-evolving the density matrix expansion over a finite-dimensional basis. Using this and other ways of evaluating a specific choice of basis, we arrive at the conclusion that the basis of eigenstates of a harmonic Hamiltonian leads to the best computational performance. Additionally, we present a method to quantify and reduce the error that is introduced when extracting relevant physical information about the ensemble of oscillators. The techniques presented here are specific to quantum heat cycles; the coexistence within a cycle of time-dependent Hamiltonian and coupling with a thermal reservoir are particularly complex to handle for the non-harmonic case. The present investigation is paving the way for numerical analysis of non-harmonic quantum heat machines.

Biodegradable thermochromic polylactic acid (PLA) sensor

Abstract This study investigates the development of polylactic acid (PLA) by incorporating thermochromic black pigments (TCB) at varying concentrations of 0, 0.5, 1, 2 and 3 wt% through the process of melt blending. The color transition and reversion behaviors of the resulting specimens were examined at different temperatures (−10, 10, 30, 35 and 50 °C) using colorimetric analysis. Additionally, mechanical properties, thermal characteristic and thermal stability were assessed through tensile testing, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The study revealed that an increase in TCB concentrations led to a reduction in lightness (L*). Higher pigment content enhanced thermochromic properties, resulting in more pronounced color changes. The total color difference (ΔE) remained reproducible over five cycles of heating and freezing, and this reproducibility persisted after thermal aging. Tensile strength and elongation at break exhibited improvement with increasing pigment content. Glass transition temperature (Tg) and melting temperature (Tm) of the thermochromic samples showed minimal reduction compared to that of neat PLA, which is 64.2 °C. Crystallinity degree (Xc) increased slightly by 0.2–0.92 %. The thermal stability of the PLA matrix was only marginally affected by the presence of thermochromic pigments.

Synthesis of magnetic NiFe2O4/rGO heterostructure as potential photocatalyst for a breakdown of malachite green (MG) dye under the visible source of light

The development of reactive radical generators, visible-light active photocatalysts with predictable stability, and efficient activity toward the breakdown of organic pollutant continue to be the primary goals of research in the area of photocatalytic environmental restoration. The present concern to on the development of an efficient heterostructure with a band gap operated on a visible region. The rGO incorporation into spinel material also decreases the agglomeration and provides a large surface area. The efficacy of NiFe2O4 (NF) nanoparticles, which are supported by rGO, as a photocatalyst for the breakdown of malachite green (MG) dye. The incorporation of rGO into NFO was investigated with the band gap property of the fabricated material using Tauc's plot profile. The NF/rGO nanocomposite underwent a reduction in magnetic properties determined through Vibrating Sample Magnetometer (VSM) analysis. However, the coercivity of the nanocomposite experienced a significant increase. When subjected to visible light, the degradation rate of malachite green (MG) dyes with NF/rGO was comparatively faster (93.84 %) than that of NF (64.33 %) and rGO (79.41 %). The cyclic photocatalytic degradation process exhibited notable reusability and stability of the magnetic recycling nanocomposite. The photocatalytic results revealed that the developed nanocomposite acts as a potential photocatalyst and it can also be employed in different applications.

Microwave-assisted catalytic technology for sustainable production of valuable chemicals from plastic waste with enhanced catalyst reusability

High energy consumption and catalyst deactivation hinder thermal plastic waste decomposition for chemical production. This study employs a microwave-assisted catalytic process with Ru/ZSM-5 as the catalyst for polyethylene waste. At 300 °C under the first cycle of microwave heating, gas yield reaches 90 wt%, with 23 wt% aromatics selectivity and 30 wt% light olefins selectivity. In the first cycle of thermal heating, gas yield is 72 wt%, with 67 wt% alkanes and 32 wt% light olefins selectivity. In microwave cycle reactions, gas yield remains around 88 wt% through seven cycles over the spent catalyst (without regeneration), shifting product composition to 80 wt% light olefins in the 7th cycle. In contrast, in thermal cycle reactions, catalyst activity is lost after one cycle, and gas yield drops from 72 wt% to 45 wt%. Microwave-assisted catalytic technology shows potential for economically producing valuable chemicals from plastic waste, as lower reaction temperature and high catalyst reusability.

Enhancement effects of hydrolysable/soluble Al-type dopants on the efficiency of CaO/CaCO3 thermochemical energy storage

Modification of CaO-based materials using Al-type dopants has been considered a promising method to enhance energy storage performance. The synergistic multi-doping effects of different Al-type dopants (soluble, hydrolysable and insoluble) on the energy storage performances, thermophysical and mechanical properties of CaO-based materials have never been reported. The hydrolysable/soluble Al-type supports co-doped CaO-based pellets were prepared, which exhibited superior energy storage density, multi-cycle stability, reaction rate, thermal conductivity and crushing strength compared to undoped CaO pellets. The regulation mechanisms of hydrolysable/soluble Al-type dopants (AlN/Al(NO3)3) on the reaction kinetics, multi-cycle stability, thermophysical properties and mechanical properties of CaO-based pellets were revealed. The addition of different Al-type dopants results in different dispersions of the formed Ca12Al14O33, which leads to different micro-morphologies and pore structures of CaO-based pellets. Hydrolysable Al-type dopants exhibit a more concentrated distribution in CaO-based pellets and the pellets have smaller crystallite sizes of CaO and predominantly microporous pores, which results in the high CO2 reactivity. Soluble Al-type dopants exhibit a more uniform dispersion in CaO-based pellets and the pellets have larger crystallite sizes of CaO and obvious pore channels, which results in the improved cyclic stability and decomposition kinetics. The optimized CaO-based pellets combine the advantages of the two Al-type dopants and present an increasing trend of energy storage density during the cyclic process. Its energy storage density remains 1571 kJ/kg after 50 cycles, and the value for CaO is only 569 kJ/kg. In addition, the optimal synthesized material has excellent thermal conductivity and crushing strength, which are 1.36 and 9.75 times those of CaO, respectively.

Thermal cycle stability and microstructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals

The Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) ferroelectric single crystals have been commercially available as important components in medical ultrasound transducers due to their excellent piezoelectric and electromechanical coupling performance. The variation in piezoelectric and dielectric properties of PMN-PT single crystals with ambient temperature is an important application indicator. In this work, the PMN-PT single crystals after direct current poling (DCP) and alternating current poling (ACP) were subjected to the cyclic thermal treatment process. The thermal cycling stability and microstructural changes in PMN-PT single crystals were investigated. The ACP single crystals exhibit a higher dielectric constant ε33T/ε0 (6500–7600) and piezoelectric coefficient d33 (2100–2500 pC N−1) compared to the DCP single crystals (ε33T/ε0 of 4100–5000, d33 of 1200–1300 pC N−1). Under thermal cycling at 60 °C, the DCP and ACP single crystals exhibit good thermal cycling stability after 150 cycles. Microstructural observations show that the domain structure of the DCP single crystals exhibits “staggered domain walls, inhomogeneous domain size, variety of domain structure,” while the relatively homogeneous stripe-like domains were observed in the ACP single crystals. After thermal cycling, new fine striped domains appear in both the DCP and ACP single crystals due to the instability of rotated polarization, but the piezoelectric and dielectric properties are not greatly affected. This work provides an intensive understanding of the effects of thermal cycling on the domain structure, which is useful for applications.

Investigation of Ca2Al2SiO7: Pr3+/Gd3+ UVB upconverting phosphor and its optical thermometric properties

On basis of fluorescence intensity ratio (FIR) over certain narrow coupled levels of rare-earth ions, up-conversion of RE-doped materials perform excellent temperature-sensing abilities for thermometry applications. A series of Pr3+/Gd3+ co-doped Ca2Al2SiO7 phosphors (Ca2Al2SiO7:Pr3+/Gd3+) were prepared by a conventional high-temperature solid-state reaction. Under excitation of blue ∼445 nm, the Ca2Al2SiO7:Pr3+/Gd3+ phosphor yields intense photoluminescence (PL) bands around 489, 528, 537, 580, 604, 613, and 646 nm due to electronic transition of 3P0 → 3H4, 3P0 → 3H5, 3P1 → 3H5, 3P1 → 3H6, 1D2 → 3H4, 3P0 → 3H6, and 3P0 → 3F2 of Pr3+, respectively. Their relative intensities are sensitively determined by Pr3+ contents, which, from 0.1 % to 5 %, tune the emission color from pink to warm white under excitation of 445 nm. It is of great interest that intense irradiation using a blue ∼445 laser does make efficient ultraviolet B (UVB) up-conversion at about 297, 306, and 313 nm, just stemming from the 6P3/2 → 8S7/2, 6P5/2 → 8S7/2, and 6P7/2 → 8S7/2 of Gd3+, respectively. A typical two-photon absorption process was proved to account for the UVB up-conversion, i.e. successive absorption of two blue ∼445 nm photons populating Pr3+ 4f5d excited state, which further efficiently transfer its energy to the 6IJ/6PJ states of Gd3+ neighbor for UVB emission. Moreover, the thermally coupled levels (TCLs) of Gd3+: 6P3/2-6P7/2, and Gd3+: 6P5/2-6P7/2 were thoroughly investigated for temperature sensing in 298–598 K. Maximum relative sensitivity of the 6P3/2-6P7/2 TCLs, i.e. Sr(I306/I313), is proved to be 0.96 % K−1 at 298 K, and that of the 6P5/2-6P7/2 TCLs, i.e. Sr(I297/I313), is 1 % K−1 at 373 K. The relevant thermal stabilities of the Ca2Al2SiO7:Pr3+/Gd3+ thermometric candidate was well validated with 10 cycles of heating and cooling processes in 298–598 K. Such continuous explorations of Pr3+/Gd3+ co-doping system will significantly promote the development of robust UVB up-converting phosphors as well as their practical applications in the field of high-resolution optical thermometry.

Self-healing coatings for large-scale damages via ultrahigh load capacity of healing agents in short kapok microtubules

Self-healing materials, due to their ability to autonomously repair damages, have been extensively applied in the field of metal corrosion protection. However, prior self-healing coatings are powerless against large-scale damages limited by their relatively low amounts of prestored self-healing agents in microcontainers, which severely restricts their long-term anticorrosion performance. Herein, to address this issue, we propose a simple strategy to prestore a water-soluble cerium-based corrosion inhibitor, cerium gluconate, into Kapok fibers through a cyclic process of vacuum drying after saturation with the inhibitor solution, and the load capacity of cerium gluconate in Kapok (CG@K) by this approach can reach up to 455 wt%. This new loading system is relatively easy to be carried out while give an ultrahigh load capacity, and applicable to encapsulate other healing agents theoretically. The Kapok fibers embedded uniformly in the self-healing coatings exhibit a dense three-dimensional network structure, which, along with the ultra-high loading content, renders the self-healing coatings distinguished corrosion resistance. It is worth noting that the self-healing coatings achieve a remarkable ability to autonomously repair large-scale cracks up to 400 μm. This work provides an option for fabricating high agent load capacity and shows tremendous potential for designing self-healing coatings for large-scale damages.

High-Performance, Easy-to-Fabricate, Nanocomposite Heater for Life Sciences and Biomedical Applications.

Microheaters are used in several applications, including medical diagnostics, synthesis, environmental monitoring, and actuation. Conventional microheaters rely on thin-film electrodes microfabricated in a clean-room environment. However, low-cost alternatives based on conductive paste electrodes fabricated using printing techniques have started to emerge over the years. Here, we report a surprising effect that leads to significant electrode performance improvement as confirmed by the thorough characterization of bulk, processed, and conditioned samples. Mixing silver ink and PVA results in the solubilization of performance-hindering organic compounds. These compounds evaporate during heating cycles. The new electrodes, which reach a temperature of 80 °C within 5 min using a current of 7.0 A, display an overall 42% and 35% improvement in the mechanical (hardness) and electrical (resistivity) properties compared to pristine silver ink electrodes. To validate our results, we use the composite heater to amplify and detect parasite DNA from Trypanosoma brucei, associated with African sleeping sickness. Our LAMP test compares well with commercially available systems, confirming the excellent performance of our nanocomposite heaters. Since their fabrication relies on well-established techniques, we anticipate they will find use in a range of applications.

Six-Tower Pressure Swing Adsorption Demonstration Animation

The Pressure Swing Adsorption (PSA) technique is a widely embraced automated method for gas separation within the industrial sector, prized for its operational simplicity and substantial economic benefits. In practice, the process typically involves the use of multiple towers to facilitate the completion of the PSA cycle. However, with the increasing number of towers in a PSA system, the intricacies of the cyclic process tend to amplify, posing challenges for novices attempting to grasp the mechanics of a six-tower PSA cycle. Utilizing animation can facilitate the process of comprehending these complex techniques by presenting them in a simplified and visually engaging format. Therefore, our research group has designed an animated depiction of a six-tower PSA device, predicated on the prototype established in our laboratory. This animation furnishes an inclusive demonstration of a complete cycle, encompassing twelve steps, pertaining to the operation of a six-tower PSA. It is our aspiration that this tool will prove advantageous for those who are embarking on the journey of understanding multi-tower PSA, as well as for seasoned professionals engaged in the field of pressure swing adsorption.

Solar photothermal utilization of coupled latent heat storage: A numerical and optimization study

The combination of Organic Rankine Cycle (ORC) and Latent Heat Thermal Energy Storage (LHTES) is a novel approach for effectively utilizing solar energy. However, the influence of solar energy fluctuations on the heat transfer process of LHTES systems is not yet clear. In this study, a sinusoidal heat source is applied to a rotating triple-tube LHTES system, and numerical analysis and model verification are conducted. The parameters of the sinusoidal heat source are optimized using the response surface method. The effects of heat source amplitude, half period, and rotation speed on the heat release time and heat release rate of LHTES are investigated, and corresponding quadratic regression equations are fitted. The optimized structure (rotation speed = 0.5 rpm, amplitude = 7.5 K, half-cycle = 100) obtained through the response surface method reduced the solidification time by 12.45% compared to the initial structure (rotation speed = 0.3 rpm, amplitude = 7.5 K, half-cycle = 100). The average temperature response and heat release rate increased by 28.34% and 16.25%, respectively. The sensible heat and total heat release within one solidification cycle increased by 12.17% and 1.87%, respectively. This study lays the foundation for the optimization design of LHTES systems and the integrated application of Organic Rankine Cycle.

Enhanced strength-ductility synergy in a gradient pseudo-precipitates heterostructured Al-2.5%Mg alloy: Design, fabrication, and deformation mechanism

Heterostructures of alloyed composites, comprising heterogeneous domains with dramatically different constitutive properties, hold remarkable potential to expand the realm of material design systems and resolve the trade-off between strength and ductility. This study introduces an innovative materials design method for synthesizing gradient pseudo-precipitates heterostructure (GPHS) in non-heat-treatable Al-2.5%Mg alloys. Utilizing cost-effective mild steel as both the diffusion source and protective layer, this heterostructure is achieved through pin-less friction stir-assisted cyclic localized deformation process. Exogenous Fe atoms diffuse across the interface by friction stir-induced heat conduction, forming Fe-Al second-phase particles in the Al alloy matrix. A rapid inter-diffusion mechanism is activated in conjunction with dense dislocation walls, grain boundaries, and sub-structures, resulting in the formation of pseudo-precipitates. These pseudo-precipitates are ultimately dispersed in a gradient distribution throughout the entire thickness of the Al alloy matrix induced by localized incremental deformation. The GPHSed Al-2.5%Mg alloy exhibits an enhanced synergy of strength and ductility, with a uniform elongation increase from 11 % to 21.2 %, while maintaining the strength. Multiple strengthening and hardening mechanisms, such as solid solution strengthening, dislocation hardening, and second phase strengthening, work synergistically to promote mechanical performance. Notably, the hetero-deformation between hard pseudo-precipitates and soft Al alloy matrix induces additional strain hardening, leading to high ductility. This work provides a fresh perspective on the design and fabrication of high-performance alloys with advanced heterostructures, especially for non-heat-treatable alloys.

Phase-field modeling of stored-energy-driven grain growth with intra-granular variation in dislocation density

We present a phase-field (PF) model to simulate the microstructure evolution occurring in polycrystalline materials with a variation in the intra-granular dislocation density. The model accounts for two mechanisms that lead to the grain boundary migration: the driving force due to capillarity and that due to the stored energy arising from a spatially varying dislocation density. In addition to the order parameters that distinguish regions occupied by different grains, we introduce dislocation density fields that describe spatial variation of the dislocation density. We assume that the dislocation density decays as a function of the distance the grain boundary has migrated. To demonstrate and parameterize the model, we simulate microstructure evolution in two dimensions, for which the initial microstructure is based on real-time experimental data. Additionally, we applied the model to study the effect of a cyclic heat treatment (CHT) on the microstructure evolution. Specifically, we simulated stored-energy-driven grain growth during three thermal cycles, as well as grain growth without stored energy that serves as a baseline for comparison. We showed that the microstructure evolution proceeded much faster when the stored energy was considered. A non-self-similar evolution was observed in this case, while a nearly self-similar evolution was found when the microstructure evolution is driven solely by capillarity. These results suggest a possible mechanism for the initiation of abnormal grain growth during CHT. Finally, we demonstrate an integrated experimental-computational workflow that utilizes the experimental measurements to inform the PF model and its parameterization, which provides a foundation for the development of future simulation tools capable of quantitative prediction of microstructure evolution during non-isothermal heat treatment.

한 경력교사의 놀이중심 교육과정 실천경험에 대한 자기성찰 연구

Objectives The purpose of this study is to examine the change in perception through self-reflection on the difficulty of practicing the play-based curriculum of experienced teachers.
 Methods An in-depth interview was conducted with one retired early childhood teacher who had experience in teaching and practicing both the existing curriculum and the play-centered curriculum, focusing on the teacher's own experience, inner life, and relationships such as infants and fellow teachers. Data analysis was conducted in a repetitive and cyclical process in a spiral analysis method.
 Results The experienced teacher was feeling confused about the role of the teacher as a play supporter and looked deeply at herself and her fellow teachers. In this process, she found a new perspective on the role of teachers in the play-centered curriculum and discovered an educational perception of the curriculum she was creating.
 Conclusions Experienced teachers have changed their perception of education and practice through selfreflection. There is a need for support centered on experienced teachers who can enhance their understanding of the play-centered curriculum through self-reflection. In addition, as an alternative to this, we propose a group of fellow teachers where reflection and learning through relationships take place.

Ag@Co/Zn N‐Doped Carbon as Antibacterial Oxygen Reduction Catalysts for Microbial Fuel Cells

Biofouling of air cathode surface decreases the electricity generation performance of membrane‐free microbial fuel cells (MFCs). Ag@Co/Zn N‐doped carbon (Ag@Co/Zn‐NC) is designed as an antibacterial oxygen reduction reaction (ORR) catalyst to inhibit biofouling on the cathode surface. The Co/Zn‐NC active component promotes ORR catalytic activity through the advantages of well‐distributed Co nanoparticles and numerous active sites. Superficial Ag nanoparticles act as antibacterial active species to inhibit bacterial proliferation and suppress biofilm growth. Ag@Co/Zn‐NC catalyst prevents bacterial adhesion and biofilm formation, effectively preventing excessive biofouling on the cathode surface. The antibacterial catalyst maintains a high catalytic activity and good ion diffusion properties without the adverse effects of biofouling, resulting in enhanced ORR durability of the air cathode. The assembled MFCs achieve high electricity generation during long‐term cyclic operation. The maximum power density retention percentage (82.6%) is higher than that of Co/Zn‐NC MFC (65.3%) and Pt/C MFC (52.4%) after continuous operation for 1200 h. Excellent operational durability is revealed for the air‐cathode MFCs assembled with the antibacterial ORR catalyst during the cyclic process. The novelty of this study is that the design of antibacterial catalysts inhibits the excessive growth of the cathode biofilm to improve the cyclic electricity generation performance of MFCs.

목도나루학교 전환기교육 학습자의 자아 성장 사례연구

Objectives This study aims to deeply understand the process of self-growth in students within the school educational environment. It explores the self-growth process of four participants who are enrolled in a transitional educational institution, ‘Mokdonaru School’ located in Chungcheongbuk-do.
 Methods Preliminary surveys were conducted among all enrolled students, and foundational surveys were carried out with all teachers to select four research participants. Semi-structured, in-depth interviews were conducted with these participants, and the data was collected through transcription. The gathered data was analyzed using Nvivo (version 14), processing a cyclical process of open coding, axial coding, and selective coding.
 Results The participants in this study revealed a growth process characterized by individual differences. They recognize various triggers and elements as the background of their self-growth, and their individual growth is not so much independent as it is holistic, affecting and transforming across the areas of self-identity, social identity, and career identity.
 Conclusions These findings suggest the need for a deeper understanding of individual differences in students' self-growth processes in secondary education, and for a holistic approach that goes beyond a narrow focus on teaching activities to include the diverse living spaces and relational aspects surrounding the school.

Improving Aerosol Characterization Using an Optical Particle Counter Coupled with a Quartz Crystal Microbalance with an Integrated Microheater.

Aerosols, as well as suspended particulate matter, impact atmospheric pollution, the climate, and human health, directly or indirectly. Particle size, chemical composition, and other aerosol characteristics are determinant factors for atmospheric pollution dynamics and more. In the last decade, low-cost devices have been widely used in instrumentation to measure aerosols. However, they present some issues, such as the problem of discriminating whether the aerosol is composed of liquid particles or solid. This issue could lead to errors in the estimation of mass concentration in monitoring environments where there is fog. In this study, we investigate the use of an optical particle counter (OPC) coupled to a quartz crystal microbalance with an integrated microheater (H-QCM) to enhance measurement performances. The H-QCM was used not only to measure the collected mass on its surface but also, by using the integrated microheater, it was able to heat the collected mass by performing heating cycles. In particular, we tested the developed system with aerosolized saline solutions of sodium chloride (NaCl), with three decreasing concentrations of salt and three electronic cigarette solutions (e-liquid), with different concentrations of propylene glycol and glycerin mixtures. The results showed that the OPC coherently counted the salt dilution effects, and the H-QCM output confirmed the presence of liquid and solid particles in the aerosols. In the case of e-liquid aerosols, the OPC counted the particles, and the HQCM output highlighted that in the aerosol, there were no solid particles but a liquid phase only. These findings contribute to the refinement of aerosol measurement methodologies by low-cost sensors, fostering a more comprehensive understanding.