Pristine graphene has low thermoelectric performance due to its ultra-high thermal conductivity and a low Seebeck coefficient, the latter of which results from the zero-band gap of graphene. To improve the thermoelectric performance of graphene-based materials, various methods have been proposed to open a band gap in graphene. Graphene antidot lattices is one of the most effective methods to reach this goal by patterning periodic nano- or sub-1-nm pores (antidots) across graphene. In high-porosity graphene antidot lattices, charge carriers mainly flow through the narrow necks between pores, forming a comparable case as graphene nanoribbons. This will open a geometry-dependent band gap and dramatically increase the Seebeck coefficient. The antidots also strongly scatter phonons, leading to a dramatically reduced lattice thermal conductivity to further enhance the thermoelectric performance. In computations, the thermoelectric figure of merit of a graphene antidot lattices was predicted to be around 1.0 at 300 K but experimental validation is still required. The electrical conductivity and Seebeck coefficient of graphene antidot lattices on various substrates including SiO2, SiC and hexagonal boron nitride were measured. The antidots were drilled with a focused ion beam or reactive ion etching.

This article presents a laboratory module developed for undergraduate micro/nano engineering laboratory courses in the mechanical engineering departments at the Massachusetts Institute of Technology and King Fahd University of Petroleum and Minerals. In this laboratory, students fabricate superoleophobic membranes by spray-coating of titania nanoparticles on steel meshes, characterize the surfaces and ability of the membrane to retain oil, and then use these membranes to separate an oil-water mixture. The laboratory module covers nanomaterials, nanomanufacturing, materials characterization, and understanding of the concepts of surface tension and hydrostatics, with oil-water separation as an application. The laboratory experiments are easy to set up based on commercially available tools and materials, which will facilitate implementation of this module in other educational institutions. The significance of oil-water separation in the petroleum industry and integration of concepts from fluid mechanics in the laboratory module will help to illustrate the relevance of nanotechnology to mechanical and materials engineering and its potential to address some of the future societal needs.

TiO2 nanotubular structures were formed on titanium foils through anodic oxidation using an electrolyte of Ethyleneglycol-H2O (97:3 Vol %)+0.25 M NH4F at a constant voltage of 60V. The anodized samples were analyzed in a FE-SEM obtaining the geometric parameters of the nanotubular arrays. The diameter and the length of the nanotubes were 112 nm and 65µm |respectively, whereas the wall thickness was 44 nm. Crystalline phase of TiO2 nanotubular films (TNTF) were determined by XRD after annealing at 500°C for 2 h, resulting high intensity peaks of anatase and low intensity peaks of rutile. Then, the crystallized samples were characterized from an optical, photoelectrochemical and photocatalytic point of view. The photoelectrochemical measurements were carried out in 0.5 M Na2SO4 solution using an 8 W UV lamp at a λ= 365 nm, which results were recorded at 0 bias during 10 min under darkness and illumination intervals of 1 min each. Photocatalytic performance of the TNTF was explored with a 10 mg/L methyl orange solution using an UV light at a wavelength of 365 nm. The changes in the concentration of the MO solution was determined from the calibration curve determined from the absorption spectra at different concentrations of MO (from 0.1 mg/L to 20 mg/L). It was observed an efficiency yield of 99.8% in the photocatalytic performance in presence of the TNTF.

La2Hf2O7 and La2Mo2O9 as potential electrolytes for solid oxide fuel cells (SOFCs) have been investigated through first-principles calculations to understand the mechanism of ion motion. In La2Hf2O7, three unique types of positions that can form anion-Frenkel (a-Fr) pairs have been screened out and a reasonable continuous diffusion path constructed by these migration sites has also been suggested as the dominant cause of ion conduction. On the other side, excellent ion conductivity in La2Mo2O9 is more based on the short-range disorder induced by mobile structure. The thermodynamic properties comparison of La2Mo2O9 and La2Hf2O7 shows that the formation of a-Fr pairs in La2Mo2O9 will start at lower temperature because of higher degree of structural disorder and less constraints on oxygen ions.

Inspired by sea sponges, porous Al2O3/starch composite sponges were designed and fabricated as a new controlled release system enabling mechano-triggered logic delivery of molecules. Results of material characterization indicate that the all the composite sponges had a high macro-porosity of >80%, and dehydrated sponges revealed favorable pore structure for drug loading and retaining. The composite sponges have moisture-dependent mechanical properties and samples with appropriate moisture contents revealed high resilience and mechanical robustness under cyclic deformation. Based on the unique mechanical properties of the composite sponge, mechanically modulated, nano-gram precision delivery of model molecules was achieved in an AND logic manner gated by both moisture and compressive strain.

Based on the nature of the links and interactions existing at the hybrid interface, hybrid materials can be broadly classified in two main designations: a) Hybrid compounds Class I, that include all systems with electrostatic forces, hydrogen bonding or Van der Waals interactions and b) Hybrid compounds Class II, showing that the inorganic and organic components are linked through strong covalent or ionic-covalent bonds. The physico–chemical properties of nanostructured copolymer acrylates based on butyl acrylate (BA), methyl methacrylate (MMA) and acrylic acid (AA) has been investigated employing un-modified SiO2 (Class I) and modified SiO2 particles (Class II) using 3-(trimethoxysilyl) propyl methacrylate (MPS) as compatibilizing agent. The synthesis was carried out using seeded batch emulsion polymerization system. Metastable nanostructured emulsions containing 1 wt% nanoparticles were obtained. Films casted from the in-situ nanostructured latex exhibited excellent optical transparency suggesting good nanoparticles dispersion. However, the mechanical properties showed by SiO2-MPS nanocomposite, are better than the Class I hybrid compounds. Therefore, SiO2-MPS surface treatment prior to polymerization enhances the physical properties of copolymer BA-MMA-AA film. The mass loss derivative traces for the polyacrylic nanocomposites and the neat polymer obtained by thermogravimetric analysis showed that the onset temperature for thermal decomposition was shifted towards a higher temperature than the neat polyacrylic, indicating the enhancement of thermal stability of the un-modified SiO2 nanocomposite. However, there is a decrease of 40°C in the decomposition temperature for the modified polyacrylic nanocomposite. The results obtained so far have shown that weak Van der Waals and H-bonding interactions may be sufficient to enable improvement of the physical properties of the acrylate nanocomposites.

The world is full of educational materials created by faculty but there has been insufficient progress in disseminating even the best of these and without broad dissemination there is little penetration of open materials into higher education. Dissemination of open educational materials cannot be limited to textbooks but systems must be created to support students and faculty as are provided by commercial publishers. LibreTexts addresses this across a broad range of science and technology fields with a new reach into social science and liberal arts. LibreTexts design makes it simple for instructors to build their own courseware, either by mapping components created by others or writing their own. LibreTexts is working towards implementing a complete learning management system including testing software, homework systems guided by artificial intelligence, classroom response software and more to provide an open, online educational system suited to the students and faculty of today.

Hydroxyapatite [HAp, Ca5(PO4)3(OH)] was synthesized by chemical precipitation, using H3PO4 and Ca(OH)2 as chemical precursors. The precursors were slowly mixed in suitable proportions aiming to obtain Ca/P molar ratios of 1.5, 1.67 or 2.0 in the reacting suspension. This was followed by 21.5 h of aging. Both reaction and aging stages were carried out under an atmosphere of still ambient air and under continuous stirring, either at room temperature, 60 or 90 °C. The precipitates were characterized by ICP-AES and XRD. The results suggested that the most suitable Ca/P molar ratio for the production of pure phase HAp is Ca/P = 1.67, as long as the initial Ca(OH)2 particle size and/or the suspension pH are carefully controlled, especially when the synthesis is carried out above room temperature.

The thermal properties of organic membranes attract much attention due to the fact that heat dissipation in electronic devices limits their functionality and reliability. Here, we enhance the thermal conductivity of polyvinyl alcohol (PVA) membrane using nano-fibers fabricated by electrospinning. Measured by the 3-Omega method, the results show that the effective thermal conductivity of the electrospinning membranes (with/without Cu nanoparticles) are as high as 0.7 W/m-K at room temperature which is as twice as the value of thermal conductivity of amorphous spin-coated PVA membrane (0.35 W/m-K). The mechanism of enhancement are that, compared with amorphous membrane, the phonon scattering is attenuated and the crystallinity is improved in the electrospinning process. Our studies bring new insights in designing new kind of membrane with high thermal conductivity.