Solid State Phenomena Vol. 352

Abstract: On-site and portable detection of heavy metals, especially in water, is critical for public health safety. Mercury is a toxic heavy metal and poses environmental and health hazard concerns causing neurological and behavioral disorders. Metallic nanoparticles possess unique optical properties, which can be used for heavy metal sensing applications. In this study, a colorimetric method for detecting mercury using silver nanoparticles was developed. The reduction of Ag⁺ to AgNP was initiated using sunlight with coffee pulp aqueous extract as a reducing agent. The UV-Vis spectrum of the as-prepared AgNP solution shows a maximum absorption peak at 433 nm due to the metal’s localized surface plasmon resonance (LSPR). The SEM analysis of the dried sample shows an aggregate of AgNPs with spherical morphology with diameters less than 100 nm. The dynamic light scattering distribution curve shows a bimodal peak with a mean hydrodynamic radius of 12.73 nm and 145 nm, respectively. The large hydrodynamic radius of more than 100 nm may be attributed to the presence of AgNP aggregates in the solution. The synthesized AgNP was shown to selectively detect Hg²⁺ ions in solution colorimetrically. A linear calibration curve was obtained for the Hg²⁺ solution between 0.04 mM and 0.2 mM with R² equal to 0.9934. This proposed method can potentially be used in the analysis of actual water samples.

Abstract: Atomic Force Microscopy (AFM) technology has ushered researchers to directly observe surface topology and the substrate mechanical properties using specialized probe. AFM is one of the microscopic techniques with the highest lateral resolution which can be employed in air or even in liquids. In this experiment, we characterized the local elastic properties of the polyacrylamide (PA) hydrogel using Atomic Force Microscopy (AFM). PA consists of huge units of an organic acrylamide monomers which can be saturated to form a highly water-swollen hydrogel. The hydrogel offers tunable density with a high degree of pliability which depends of its applications. Such applications of PA hydrogel can be in cell substrate studies and measurement of cell-generated forces. Our results with AFM measurement yielded force-distance curves were used to determine the elastic behaviour of the polyacrylamide (PA) hydrogel. Analysis has shown that 15% w/v PA hydrogel concentration has Young’s modulus, Y_av=1608.9 ± 1.3 kPa (n=8) and transverse stiffness, K_av=88.7 ± 9.7 μN/nm (n=8) at Thus, elasticity measurements has provided useful insights for the future experiment on traction force microscopy with amoeboid organism.

Abstract: In recent studies, multifunctional oxide thin films have been given attention because of their special properties, such as ferroelectricity, gas sensitivity, and magnetism. Ion beam irradiation arose as a well-developed technique for tuning such properties. This study investigates the ion beam irradiation effects of He, Ni, and Kr ions on BiFeO₃, SnO₂, and ZnO thin films, respectively. The study utilized the 2013 version of Stopping and Range of Ions in Matter (SRIM) software to identify ion trajectory distribution and oxygen target vacancy differences on the Transport of Ions in Matter (TRIM) calculation types at various ion energies. A greater distribution of ion trajectories and higher peaks of oxygen target vacancies in oxide thin films were generated from monolayer TRIM than full cascade TRIM for all ion–thin-film pairs. The monolayer TRIM is preferable for ion beam irradiation of oxide thin films with its greater oxygen target vacancies and ion trajectory distribution for better analysis of ferroelectric coercive fields, adsorbed oxygen ions interaction with gas molecules, and the emergence of green emission for photoluminescence. The use of SRIM allows an alternative yet more flexible way of analyzing beam irradiation effects on oxide films considered in this work without resorting to costly or sophisticated experimental setups, which are a usual approach considered in most of the work under this topic. As such, the results presented here provide an initial or complementary basis should irradiation effect experiments require analysis of ion trajectories and oxygen vacancies.

Abstract: Here we provide a description of arsenic (As) adsorption on the cellulose biopolymer using first-principles density functional theory. In all studied configurations, the process of As adsorption on the cellulose is an exothermic process indicated by the negative binding energy. The cellulose's hydroxyl and hydroxymethyl groups significantly interact with As atom, characterized by the binding energy. In all optimized configurations, the interactions are mainly described as chemical bonding. This claim is supported by the overlap of the electron localization function (ELF) in the interface of As and cellulose in all studied adsorption sites. The adsorption of As on the cellulose introduces new states in the vicinity of the Fermi energy, leading to the lower bandgap of the cellulose-As systems. Overall, these results imply that the As atom can be trapped and detected using cellulose-based material. These findings offer an explanation of earlier research works on cellulose-As systems. This work will also serve as a reference for fabricating cellulose-based material for sensing and removing As.

Abstract: The paper shows that the introduction of up to 6 wt % of ferromanganese dust enhances the process of granule porization and improves the structural-mechanical properties. This is achieved due to the formation of low-base calcium hydrosilicates in the mineral matrix, reinforced by crystals of fayalite, orientite and pyroximite, which contribute to an increase in the dielectric component in the scattering of electromagnetic waves in the millimeter range. Granules with a developed pore structure in the frequency range from 110² to 3.1510³ Hz can absorb and scatter electromagnetic waves in the range of 54-58 dB. Granules in the temperature range from 20 to 300 °C are flame retardant and not prone to brittle fracture (F ≤ 4). The introduction of a 5% porous filler into the polymer matrix contributes to the growth of the effective part of the dielectric permittivity (μ to 1.5) and stabilization of the coefficient of attenuation of electromagnetic waves (from 2 to 4) in the range 110¹⁰ - 610¹⁰ Hz. The developed porous material is recommended to was used as a filler in the first layers of gradient-absorbing composites

Abstract: Automotive air conditioning (AAC) is essential, particularly in tropical countries like the Philippines, where temperatures can go beyond 40 °C during the summer. AAC system is installed for the comfort and safety of passengers. However, AAC may consume up to 30% of the fuel and increase fuel consumption by up to 20%. Consequently, increasing fuel consumption can lead to high costs and greenhouse emissions worldwide. Commercially available car tints can block harmful ultraviolet (UV) rays but selectively block IR rays which primarily cause heating. Therefore, sustainable cooling solutions must be developed. This study developed a silver nanowire (AgNW)-PVB (polyvinyl butyral) composite spray coating. The coating decreased the transmittance by at least 30% in the UV region and at least 25% in the near-infrared (NIR). Average transmittance in the visible region (Vis) is as much as 63.50% which highly depends on the concentration of PVB and AgNWs. More AgNWs decrease the transmittance at UV, Vis, and NIR regions.

Abstract: Microplastic is the most problematic persistent pollutants in the environment despite of its unique properties for various life application. The objective is to investigate the feasibility and practicability of the nanostructured TiO₂ coupling with noble metal in removal polypropylene (PP) microplastics. The TiO₂ nanowires (NWs) were synthesized by thermal oxidation of Ti foil under various mixed oxidation environments. TiO₂ NWs were successfully grown uniformly and with full coverage over the foil under the condition of ramping in KOH mist and soaking in water vapour at 700 °C for 120 minutes. Heterojunction photocatalyst of Ag/TiO₂ NWs was formed using wet impregnation method. Small quantity of Ag nanoparticles (NPs) was attached onto the TiO₂ nanowires. The photocatalytic efficiency of the synthesized Ag/TiO₂ NWs photocatalyst was tested upon removal of PP microplastic from non-static water bodies under UV irradiation. Coupling Ag NPs with TiO₂ NWs have better photocatalytic performance than those without Ag NPs from the reduction of weight loss and the possibility of presence of carbonyl group.

Abstract: Nanolubricants are a critical topic currently due to their outstanding thermal conductivity and system performance. A highly stable nanolubricant dispersion is extremely useful for good lubrication performance. However, maintaining their dispersion stability over time is still a major challenge in this field. As a result, the goal of this paper is to evaluate the influence of sonication duration on the stability and thermal conductivity of nanolubricants. In this work, 0.1 vol% concentrations of graphene (Gr) and aluminium nitride (AlN) nanoparticles and polyolester oil (POE) as the base fluid are used. The duration of mechanical stirrer is constant however the ultrasonication time is varied. The stability of nanolubricants are observed by using visual observation technique for 21 days and measured by thermal conductivity and Zeta potential. The results show that the 45 min of sonication time for AlN and 15 min of sonication time for Gr are the optimum time for the ultrasonication.

Abstract: A non-volatile memory is a solid-state device that can retain data even power supply is terminated. It is an essential data storage device that serves as a backbone for the advancement of Internet-of-Things. There are various emerging non-volatile memory technologies in different technology-readiness levels, to replace the existing technologies with limited memory density, operating speed, power consumption, manufacturability, and data security. Of the emerging technologies, resistive switching technology is one of the most promising next generation non-volatile random-access memories. The fundamental working principle of the resistive-switching random-access memory (ReRAM) is based on memristor characterises with metal-insulator-metal stacking structure. Same as other solid-state devices, ReRAM is also facing issue of electronic waste when the memory device is discarded. To overcome this issue, bio-organic materials as green and sustainable engineering materials have been used to fabricate ReRAM. In this review, development of bio-organic based ReRAM, in particular the resistive switching mechanisms and device performance, have been discussed and challenging and future applications of this memory have been provided.