Udon Thani Rajabhat University

This work aims to disclose the strengths and limitations of utilizing hydroxyl-compatible fillers, rice husks and silica (SiO2), in citric acid-crosslinked thermoplastic starch foams. FTIR characterization demonstrated that citric acid could establish ester linkages with starch molecules for both neat and composite foams, with the C = O peak shifting from 1724 cm-1 (neat foam) to 1730-1732 cm-1 (composite foams). The key role of hydroxyl-compatible fillers was the strong starch-filler interactions that enabled more thermally stable composite foams, which elevated thermal decomposition temperatures to 300-302 degrees C with higher residue weights of 22.73-25.33%. These strong starch-filler interactions were also responsible for retarding cell foam expansion. The composite foams showed 16.61-92.03% improved flexural strength, 2.82-10.67% increased densities and lower moisture absorption. However, incorporation of hydroxyl-compatible fillers in composite foams increased water solubility to 16.84-20.73%, compared to 12.14% for a neat foam. These experimental results indicate that the employed fillers might interfere with the crosslinking process, leading to decreased crosslink formation in composite foams. Consequently, possible interruption mechanisms of crosslink formation by the fillers were suggested and confirmed by qualitative analysis. The findings of the strengths and limitations of hydroxyl-compatible fillers illustrate crucial trade-offs in using starch-based composite foams as sustainable food packaging materials.

Heavy metal contamination in food crops remains a critical environmental and public health issue, particularly for cadmium (Cd2+) and copper (Cu2+), which can accumulate through soil, water, and agricultural inputs. Reduced graphene oxide (rGO) was prepared via boric acid-assisted thermal reduction of graphene oxide followed by acid washing. A boron-doped reduced graphene oxide modified graphite electrode (rGO/GE) was then fabricated and applied for the sensitive voltammetric determination of Cd2+ and Cu2+ in jasmine rice using differential pulse anodic stripping voltammetry (DPASV) coupled with a standard addition technique. DPASV analysis included immersion of the rGO/GE and the deposition of target metal ions (Cd2+ and Cu2+) and bismuth onto the electrode surface. The synthesized GO and rGO were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-vis spectroscopy, and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS). Results confirmed the complete reduction of GO to rGO using boric acid as the reducing agent. The method showed excellent reproducibility and sensitivity, with limits of detection (LODs) of 30 µg/L for Cd2⁺ and 0.05 µg/L for Cu2⁺. Electrochemical analysis results show that the actual concentrations of Cd2+ and Cu2+ in Royal Umbrella brand jasmine rice were 0.46 ± 0.01 mg/kg and 1.16 ± 0.06 mg/kg, respectively. The results were validated using atomic absorption spectroscopy (AAS), which provided relative differences of 0.00

The Constrained Application Protocol (CoAP) has become a widely adopted communication standard for the Internet of Things (IoT) and wireless sensor networks (WSNs). However, its default congestion control mechanism, based on binary exponential backoff (BEB), lacks adaptability to dynamic network conditions. This limitation often results in excessive retransmissions, increased latency, and inefficient energy consumption, particularly in resource-constrained environments. To address these challenges, this study proposes a novel Constrained Adaptive Exponential Backoff (CAEB) algorithm designed to enhance retransmission timeout (RTO) estimation through an adaptive, lightweight approach. CAEB integrates a logarithmic adjustment mechanism and weighting factors based on retransmission count and active node density, enabling real-time adaptability while maintaining computational simplicity. The proposed algorithm was implemented and evaluated in the Cooja simulator using the Contiki operating system under both continuous and periodic traffic scenarios. The experimental results demonstrated that CAEB consistently achieved lower flow completion time, higher throughput, and reduced packet loss and retransmissions compared with BEB, with these improvements confirmed as statistically significant based on the two-sample t-tests (p < 0.05) and the Holm-Bonferroni correction method. These findings highlight the effectiveness of CAEB in mitigating congestion and improving reliability in constrained IoT networks. The proposed algorithm not only advances methodological approaches for RTO estimation but also offers practical implications for energy-efficient and scalable IoT communication systems, particularly in applications such as smart agriculture, environmental monitoring, and structural health monitoring, where timely and reliable data delivery is critical.

Given a rational number alpha not equal +/- 2, a criterion is established for the existence of the general solution to the alternative quadratic functional equation of the form f(xy) +f(xy(-1)) = 2(f(x) +f(y)) or f(xy) +f(xy(-1)) = alpha(f(x) +f(y)), where f is a mapping from an abelian group (G, center dot) to a uniquely divisible abelian group (H,+). Subsequently, the Hyers-Ulam stability of this equation is proved for mappings from an abelian group to a Banach space, provided that alpha is an element of {0, +/- 1/2, +/- 1, +/- 2} is a rational number.

Under elevated (relative to ambient) light intensity and CO₂ levels combined with drought affect photosynthesis, with responses may be varying between genotypes depending on their drought resistance. Thus, this study aimed to determine the difference of light intensity and CO2 concentration on the photosynthetic traits of Jerusalem artichoke genotypes differing in drought resistance under drought conditions. The rising CO₂ concentrations enhanced photosynthetic rate (Pn) and transpiration efficiency (TE), but decreased stomatal conductance (gs) and transpiration rate (E) in both genotypes. The highest Pn was observed at 1,000 µmol mol⁻¹ CO₂ for drought-resistant genotype JA 60 and at 1500 µmol mol⁻¹ CO₂ for drought-susceptible genotype KT 2. Additionally, rising photosynthetic photon flux density (PPFD) levels improved Pn, gs, and E under both water levels, with optimal responses recorded at 2500 µmol m⁻² s⁻¹ PPFD for both genotypes. In drought-resistant genotype, TE increased with rising PPFD up to 1500 µmol m⁻² s⁻¹ while the drought-susceptible genotype peaked at 1000 µmol m⁻² s⁻¹, after which TE declined under drought. The drought-resistant genotype demonstrated more efficient stomatal regulation, higher photosynthetic capacity, greater transpiration efficiency and better maintenance of leaf area and biomass under drought stress, whereas the susceptible genotype showed weaker control over these physiological and growth-related traits. Drought-tolerant JA 60 and drought-sensitive KT 2 exhibited contrasting physiological strategies. JA 60 maintained consistently high Pn, gs, and E across all CO₂ and light conditions and retained leaf area and biomass under drought, whereas KT 2 showed reduced photosynthesis and greater declines in leaf area and biomass under drought conditions, but showed higher TE. Despite these differences, both genotypes displayed common responses, including decreased gs under elevated CO₂, enhanced TE during water stress, and increased Pn with higher light intensity. The strong performance of JA 60 under combined stresses suggests its suitability for cultivation in water-limited environments, whereas the water-saving strategies of KT 2 provide valuable insights for breeding programs aimed at enhancing TE.