This study aims to investigate the effects of accelerated aging on withdrawal strength of different nail diameters in coconut lumber, assess the sensitivity of ultrasonic test parameters on the damage induced by accelerated aging in wood-nail materials, and develop a regression model for estimating nail withdrawal strength in coconut lumber subjected to accelerated aging. The prepared samples were subjected to different number of accelerated aging cycles. Ultrasonic and withdrawal tests were then implemented. The results show that all nail groups exhibited lower withdrawal strength after one cycle due to high fiber deterioration rate. From two to six cycles, cracking and corrosion influenced withdrawal strength. The smallest nail diameter group demonstrated a continuous increase in withdrawal strength because it developed less cracks but more rust resulting in net increase in withdrawal strength. However, larger nail diameter groups showed a fluctuating trend in withdrawal strength from two to four cycles since they developed more cracks but less rust. After six cycles, these groups showed an increase in withdrawal strength due to continuous corrosion development while fiber deterioration remained roughly the same. Moreover, the results indicate that ultrasonic pulse velocity (UPV) is the most reliable parameter for late damage monitoring while sideband peak count-index (SPC-I) is the most effective parameter for early damage detection in wood-nail materials. Combining SPC-I and UPV will provide a more holistic approach for monitoring damage progression of non-engineered structures in the Philippines. Lastly, based on several performance indicators and adequacy tests, an overall best model was selected. The best model achieved an R2 value of 0.6381. The results also revealed that the lower-prediction bound of the developed model (i.e., best model) in this study may supplement the structural codes and be used to
estimate withdrawal strength of coconut lumber in non-engineered structures in the Philippines.

Carbon dioxide (CO2) electrolysis using Solid Oxide Electrolysis Cells (SOECs) plays a key role in CO2 utilization technologies, such as the production of O2 gas. While Ni-YSZ is a widely used cathode material, it suffers from carbon deposition under dry CO2 conditions, limiting its long-term stability. Perovskite-based cathodes, particularly the composite of La0.6Sr0.4Co0.2Fe0.8O3-δ and CeO2-Gd2O3 (LSCF-GDC), have emerged as promising alternatives due to their mixed ionic-electronic conductivity and structural stability. In this study, symmetrical SOECs were fabricated with LSCF-GDC composite cathodes deposited on YSZ substrates using the screen-printing technique, with varying LSCF-GDC weight ratios of 30:70, 50:50, and 70:30 LSCF-GDC. The cells were characterized by their microstructure, morphology, and total conductivity. SEM/EDS analysis confirmed good homogeneity between LSCF and GDC phases and adequate porosity for gas diffusion with an observed thin film thickness of <20um. Electrochemical impedance spectroscopy revealed that the total conductivity for different studied composition ranges from 10-7 to 10-4 S/cm. The total conductivity trend shows that it is increasing as GDC weight percentage increases. The total conductivity in a CO2 environment was lower compared to O₂, likely due to the lower oxygen partial pressure and reduced availability of reactive oxygen species. In addition, initial investigation of the electrolysis performance was conducted for the 30:70 LSCF-GDC, which resulted in a current density of 51mA/cm2 and a 0.09% O2 production rate at 800℃. Thus, this study successfully fabricated a symmetrical LSCF-GDC cell for dry CO2 electrolysis; however, further optimization is needed to increase its performance

Topology Optimization is a popular method to optimize the pattern of a material given a defined design domain, given the proper boundary and load conditions. However, the issues that arise with the use of this method are the lack of homogeneity in the design and the default method of maximizing stiffness, which is opposite to the desired outcome of the study, to maximize the compliance of aircraft morphing wings while increasing the spread of the material within the design space. This paper introduces the use of a homogeneity condition to the established Topology Optimization algorithm to maximize compliance and increase homogeneity. Through the use of the K Nearest Neighbors method, an optimized pattern with increased homogeneity and compliance is successfully created and validated through 3D printing and mechanical testing. Various parameters could be controlled to increase results for homogeneity and compliance using this new method.

The global accumulation of mine tailings, particularly those generated from nickel mining operations, poses substantial environmental hazards due to the presence of leachable heavy metals (HMs). Among the emerging remediation techniques, stabilization/solidification via geopolymerization offers a promising circular strategy by transforming hazardous waste into
valuable construction materials while immobilizing toxic contaminants. This study investigates the potential of nickel mine tailings (NMT) as a precursor for geopolymeric binders, in combination with supplementary cementitious materials (SCMs) including ground granulated blast furnace slag (GGBFS), coal fly ash (CFA), and limestone powder (LP), incorporated at 75
wt%, 50 wt%, and 25 wt% ratios. Sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)₂) were used to initiate geopolymerization. The result showed that near absence of aluminosilicates in nickel mine tailing presents inadequacy of the material as standalone precursor for preparation of geopolymer. Hence, the addition of supplementary materials as sources of alumina and silica demonstrated favorable engineering properties. Highest 28-day compressive strength of 20.05
MPa was achieved in sample containing 75wt% GGBFS via Ca(OH)2 activation, attributed from C-A-S-H and C-S-H formation, while comparable strength of 14.32 MPa was attained in sample activated by NaOH. Optimized mix ratio for CFA-based sample of 75wt% CFA, NaOH-activated yielded a 28-day compressive strength of 13.01 MPa. These strengths fall within the acceptable range for load-bearing mortar application as per ASTM standards. Samples have also demonstrated HM immobilization rates, as high as 99.9859%, 99.9995%, and 99.9380% for Ni, Mn, and Cr, respectively. In addition, NaOH-based activation presented more resistance to HM remobilization and acid attack due to strong alkalinity and ability to synthesized to denser matrices. This study implies the potential of NMT-based geopolymer as construction and building material based on its evaluated mechanical and leaching properties.

This study investigates the effect of coexisting iron (Fe(III)) on nickel recovery using Fluidized Bed Homogeneous Crystallization (FBHC) technology. A Box–Behnken experimental design was employed to evaluate the influence of pH (8.5–9.5), precipitant-to-metal molar ratio (carbonate/nickel ion) (1.5–2.0), and iron concentration (0.36–1.07 mM) on nickel removal and granulation efficiency. It has fixed factors of Ni(II) (5.11 mM), flowrate (10 mL/min), and gradual increase of reflow rate (120 mL/min). Results showed that elevated pH and molar ratio enhanced nickel recovery (>96%) through increased supersaturation and nucleation kinetics. Iron played a multifaceted role—moderate concentrations (~0.72 mM) enhanced crystallization by serving as scaffolds for nucleation, while excessive iron disrupted crystal structure and surface passivation.

Comprehensive characterization (FTIR, Raman, XRD, SEM-EDS, XPS, TGA) confirmed the formation of NiCO₃, Ni(OH)₂, FeOOH, and Ni–Fe layered double hydroxides (LDHs). Kinetic analysis revealed that the pseudo-second-order mechanism dominated the crystallization process. Thermodynamic analysis indicated that moderate Fe(III) levels improve the thermal stability of the granules. This work highlights the potential of FBHC in treating complex multi-metal wastewater, providing a pathway for high-purity nickel recovery, and reduced sludge generation.