Fine Lattice Structure Research Articles

Acoustic resonance testing of additive manufactured lattice structures

Additive manufacturing (AM) allows engineers to design and manufacture complex weight saving lattice structures with relative ease. These structures, however, present a challenge for inspection. A non-destructive testing and evaluation method used to assess material properties and quality is the focus of this paper, namely acoustic resonance (AR) testing. For this research, AR testing was conducted on weight saving lattice structures (fine and coarse) manufactured by powder bed fusion. The suitability of AR testing was assessed through a combined approach of experimental testing and FE modelling. A sensitivity study was conducted on the FE model to quantify the influence of element coarseness on the resonant frequency prediction and this needs to be taken into account in the application and analysis of the technique. The analysis was extended to extract effective modulus values for the lattice structures and the solid materials from every detected overtone, allowing for multiple measurements from a single AR test without the need to carefully isolate the fundamental. The AR and FE modelling modulus of elasticity values were validated using specimens of known properties. There was fair agreement between the FE and compression test extracted values of effective modulus for the coarse lattice. For the fine lattice, there was agreement in the values of effective modulus extracted from AR, 3-point bend, and compression experimental tests carried out. It was found that loose powder fusing from AM resulted in the fine lattice structure having a higher density (at least 1.5 times greater) than calculated due to the effect of loose powder adhesion. This effect resulted in an increased stiffness of the fine lattice structure. AR can be used as a measure of determining loose powder adhesion and other unique structural characteristics resulting from AM.

Galactosialidosis associated with IgA nephropathy: Morphological study of renal biopsy

Galactosialidosis is an autosomal recessive lysosomal disease associated with a deficiency of beta-galactosidase and neuraminidase. Described herein is the case of a young adult who had been diagnosed with galactosialidosis at 8 years of age. At the age of 30 years, proteinuria and hematuria appeared and the patient underwent a renal biopsy 1 year later. Light microscopy of the kidney sections indicated fine granular contents in the cytoplasm of glomerular endothelial and epithelial cells, arteriolar smooth muscles and proximal tubular epithelial cells on periodic acid silver-methenamin (PAM) stain. Electron microscopy of these cells indicated enlarged, smooth endoplasmic reticulum and lysosomes containing 150 nm-wide rods with a fine lattice structure at 66 A periodicity. Moreover, electron-dense deposits were located in the paramesangial area. Immunofluorescence staining indicated diffuse and global anti-human IgA and C3-positive staining as a mesangial pattern. Given these findings this patient was therefore diagnosed with both galactosialidosis and IgA nephropathy. This is the first report to describe light and electron microscopy observations of storage materials in the kidneys in young/adult galactosialidosis.

Control of two-dimensional aggregates of a long-chain merocyanine by change of molecular environments in monolayer assemblies

An amphiphilic unsymmetrical merocyanine forms J- and H-aggregates by changing molecular environments in the binary and the ternary mixed monolayer assemblies, which have been characterized by visible absorption spectra films having red-shifted and blue-shifted bands in comparison with the solution spectrum, respectively. From the surface pressure–area isotherms of the mixed monolayers, the film structures were studied at the air/water interface. The in-plane X-ray diffraction and the atomic force microscopy measurements of their LB films were done to observe the fine lattice structure. The aggregate structures were well corresponding to the dye arrangements speculated by calculation with an extended dipole model for the spectral shifts.

Multiple Medullæ in Wool Fibres

A SAMPLE of Lincoln wool grown near Hamilton in the Western District of Victoria, Australia, has been found to contain a small percentage of the fibres with two medullæ and even, in rare cases, with a few fragments of a third one. They varied from almost continuous to fragmental, frequently one being more broken than the other. The contents were of an irregular fine lattice structure.