Spectral emittance measurements of micro/nanostructures in energy conversion: a review

Micro/nanostructures play a key role in tuning the radiative properties of materials and have been applied to high-temperature energy conversion systems for improved performance. Among the various radiative properties, spectral emittance is of integral importance for the design and analysis of materials that function as radiative absorbers or emitters. This paper presents an overview of the spectral emittance measurement techniques using both the direct and indirect methods. Besides, several micro/nanostructures are also introduced, and a special emphasis is placed on the emissometers developed for characterizing engineered micro/nanostructures in high-temperature applications (e.g., solar energy conversion and thermophotovoltaic devices). In addition, both experimental facilities and measured results for different materials are summarized. Furthermore, future prospects in developing instrumentation and micro/nanostructured surfaces for practical applications are also outlined. This paper provides a comprehensive source of information for the application of micro/nanostructures in high-temperature energy conversion engineering.     

Laser Melting Deposition of CP-Ti/Ti–0.4Ni Graded Material for Structural Applications

Metallurgical and Materials Transactions A - In this study, microstructural evolution and strengthening of commercial purity Ti (CP-Ti)/Ti–0.4Ni graded material (GM) fabricated by laser...     

Liquid-Crystal-Elastomer-Based Dissipative Structures by Digital Light Processing 3D Printing

Digital Light Processing (DLP) 3D printing enables the creation of hierarchical complex structures with specific micro- and macroscopic architectures that are impossible to achieve through traditional manufacturing methods. Here, this hierarchy is extended to the mesoscopic length scale for optimized devices that dissipate mechanical energy. A photocurable, thus DLP-printable main-chain liquid crystal elastomer (LCE) resin is reported and used to print a variety of complex, high-resolution energy-dissipative devices. Using compressive mechanical testing, the stress–strain responses of 3D-printed LCE lattice structures are shown to have 12 times greater rate-dependence and up to 27 times greater strain–energy dissipation compared to those printed from a commercially available photocurable elastomer resin. The reported behaviors of these structures provide further insight into the much-overlooked energy-dissipation properties of LCEs and can inspire the development of high-energy-absorbing device applications.     

Nucleation Analysis of Variant Transformed from Austenite with Σ_3 Boundary in High-Strength Low-Alloy Steel

We elucidate here the effects of annealing twins on phase transformation products based on electron back-scatter diffraction analysis and corresponding microstructure visualization and quantification methods.Martensite and bainite were obtained by rapid continuous cooling and isothermal processing at different temperatures,respectively,which were designed to study variants formed in austenite with Σ_3 boundary.The isothermal transformation near martensite start(M_s) temperature was most conducive in obtaining the highest content of twin-related V_1/V_2 variant pair.Based on the classical nucleation theory of martensite and bainite,respectively,the role of austenite Σ_3 boundary in martensite and bainite transformation is illustrated.     

A β-galactosidase from chick pea (Cicer arietinum) seeds: Its purification,biochemical properties and industrial applications

A β-galactosidase from Cicer arietinum seeds has been purified to apparent electrophoretic homogeneity using a combination of various fractionation and chromatographic techniques, giving a final specific activity of 220 units mg⁻¹, with approximately 1840 fold purification. Analysis of the protein by SDS–PAGE revealed two subunits with molecular masses of 48 and 38 kDa, respectively. These bands were further confirmed with LC–MS/MS, indicating that Chick pea β-galactosidase (CpGAL) is a heterodimer. Molecular mass was determined to be 85 kDa by Superose-12 FPLC column, which is in agreement with the molecular mass suggested by mass spectroscopy to be 83 kDa. The optimum pH of the enzyme was 2.8 and it hydrolysed o-nitrophenyl β-d galactopyranoside (ONPG) with a K_m value of 1.73 mM at 37 °C. The energy of activation (E_a) calculated in the range of 35 to 60 °C, using Arrhenius equation, was determined to be 11.32 kcal mol⁻¹. The enzyme could also hydrolyse lactose, with an optimum pH of 4.0 at 40 °C. K_m and E_a for lactose hydrolysis was found to be 10 mM and 10.57 kcal mol⁻¹, respectively. The enzyme was found to be comparatively thermostable showing maximum activity at 60 °C for both ONPG and lactose. Galactose was found to be the competitive inhibitor. β-Galactosidase also exhibited glycoproteineous properties when applied on Con-A Sepharose column. The enzyme was localised in germinated seeds with X-gal activity staining and shown to be expressed prominently at grown radical tip and seed coat. Sequence alignment of CpGAL with other known plant β-galactosidase showed high amino acid sequence homology.     

Thermoelastic analysis of laminated and functionally graded sandwich cylindrical shells with two refined higher order models

Analytical solutions for laminated and functionally graded sandwich open cylindrical shells under mechanical and thermal loads are presented using a refined higher order shear and normal deformation theory. Temperature variation through thickness is assumed as thickness coordinate polynomial. Present study also extends the classical thickness criteria with more reliable extension to moderately thick shells. Navier solution method is used to solve system of equations derived using principle of minimum potential energy for all edges diaphragm supported. Two kinds of sandwich panels with core or face sheets made of thickness graded material are studied. Several examples are numerically evaluated to establish the accuracy of present models.     

Malleability Resilient Concealed Data Aggregation in Wireless Sensor Networks

The objective of concealed data aggregation is to achieve the privacy preservation at intermediate nodes while supporting in-network data aggregation. The need for privacy preservation at intermediate nodes and the need for data aggregation at intermediate nodes can be simultaneously realized using privacy homomorphism. Privacy homomorphism processes the encrypted data without decrypting them at intermediate nodes. However, privacy homomorphism is inherently malleable. Although malicious adversaries cannot view transmitted sensor readings, they can manipulate them. Hence, it is a formidable challenge to realize conflicting requirements, such as end-to-end privacy and end-to-end integrity, while performing en route aggregation. In this paper, we propose a malleability resilient concealed data aggregation protocol for protecting the network against active and passive adversaries. In addition, the proposed protocol protects the network against insider and outsider adversaries. The proposed protocol simultaneously realizes the conflicting objectives like privacy at intermediate nodes, end-to-end integrity, replay protection, and en route aggregation. As per our knowledge, the proposed solution is the first that achieves end-to-end security and en route aggregation of reverse multicast traffic in the presence of insider, as well as outsider adversaries.     

Quasi-aligned gold nanodots on a nanorippled silica surface: experimental and atomistic simulation investigations

Quasi-aligned gold nanodots with a periodicity of ～ 40 nm have been synthesized on a silica substrate by oblique deposition of gold on fast argon atom-beam-created nanoripples of wavelength 40 nm and subsequent annealing. The size distribution of these aligned nanodots resulting from oblique deposition at 85° of 0.5 nm Au film perpendicular to ripples is narrower than the similar deposition on a flat surface. The deposition and annealing process was simulated with a three-dimensional kinetic lattice Monte Carlo technique in order to understand the formation of aligned nanodots. The atomistic simulation and the experimental results suggest that there is an optimal thickness which can result in nanodots aligned along the ripples in the case of depositions perpendicular to the ripples. The nanodots formed after annealing of the films deposited parallel to ripples or on flat surface lack alignment.