Materials Plus

Effect of carboxylate additives on CaCO3 particle size by precipitation method using scallop shell

2024-05-27T11:54:21+08:00

The effect of carboxylate on the particle size of CaCO₃ derived from scallop shells was investigated. Shell was dissolved in HCl solution and used as a raw material for CaCO₃ particles. As the carboxylate additives, tartrate, oxalate, phthalate, and citrate were employed. The average diameter of particles, D_a, was found to be a function of the molar ratio of COO^–/CO₃^2–. In the case of adding tartrate and phthalate, D_a was varied as having a local minimum value at the molar ratio of 1-5. In the case of adding oxalate and citrate, D_a was varied as reaching the minimum value at the molar ratio of 1-2. These sizes were about 0.1-0.25 times smaller than those without adding (21 m). The characterization of the particles was conducted by SEM images and X-ray diffraction patterns. Particles were found to have a crystal structure of calcite, however, in the case of tartrate and phthalate, calcium tartrate tetrahydrate and vaterite were found.

Exploratory study about apparent elastic properties of human breast

2024-05-27T12:00:08+08:00

Since the behaviors of human breasts are rubberlike, current research explores elastic properties of human breasts. The elastic behavior of breasts is observed through force-displacement measurements in a laboratory setting and characterized through tensile and shear moduli considering individual breast geometries. The breast geometry was analyzed based on specific dimensions, such as cross-sectional areas and lengths in different orientations. The average tensile and shear moduli are estimated to be 5.04 and 0.96 kN/m², respectively, while both vary from individual to individual in wide ranges. The research approach is highly exploratory and examines apparent elastic properties, but the findings make it possible to quantify elastic capability of live human breasts as a whole and compare them with other soft materials. The conclusion suggests that the shear modulus might be more appropriate to characterize the elasticity of human breasts in terms of developing sportswear.

An investigation into the effect of anode platinum loading on Direct Methanol Fuel Cell performance

2024-06-06T14:57:31+08:00

Direct methanol fuel cells can utilize a liquid methanol fuel directly, without the need for prior reformation. This ability is highly advantageous when compared with other fuel cell technologies, which require pure hydrogen as a fuel source. An investigation was carried out to try and optimize the anode platinum loading using both Pt-NiTiO₃ and Pt-Ru based electrocatalysts by determining a point of diminishing performance returns. The results showed continued performance improvement as anode platinum loading increased for the Pt-NiTiO₃ catalyst, likely as a result of the methanol oxidation capabilities of NiTiO₃. Whereas, for Pt-Ru based catalysts, an optimum point was found at 0.66 mg_Ptcm^-2.

Kinetics and Products of the Reaction of Graphene Nanoplatelets with Noble Metal Ions to Nanocomposites with Single Atoms and Clusters

2024-06-17T16:31:43+08:00

Metal-supported graphene nanocomposites with single atoms or small clusters are of interest for various catalytic processes, including applications in batteries, fuel cells, water electrolysis, and chemical synthesis. Typically, graphene oxide is reduced in the presence of metal salts to produce metal-graphene nanocomposites. However, graphene itself has reductive properties and can react with metal ions in higher oxidation states in a suitable solvent. While direct reactions (dip and coat or wet coating) with metal salts have been described several times, less is known about the kinetics. This study investigates the reaction of suspended graphene nanoplatelets (GNP) in aerated water with the chlorocomplexes of gold(III), iridium(IV), platinum(IV), and palladium(II) to form nanocomposites covered with single atoms and small clusters. The maximum metal loading ranges from 3.3 mass% for palladium to 44 mass% for gold, increasing with redox potential. At high redox potentials, such as those of Ir(IV) and Au(III), the reactions follow pseudo-first order kinetics. In contrast, at lower potentials, such as those of Pt(IV) and Pd(II), the reaction adhere to pseudo-second order. This data enable kinetically controlled metal coating of the GNP. In contrast to the use of a reducing agent, gold, platinum, and palladium are present on the GNP in different oxidation states, which can be specifically modified, as shown for platinum-coated GNP. Iridium(IV) has been deposited as anhydrous and hydrated iridium(IV) oxide. The nanocomposites have great potential as single-atom catalysts. The described process can be transferred to other transition metals and is sustainable because the reaction media can be recycled.