Characterization of Ni–Ti Alloy Powders for Use in Additive Manufacturing

Additive manufacturing (AM) offers a fully integrated fabrication solution within many engineering applications. Particularly, it provides attractive processing alternatives for nickel-titanium (Ni–Ti) alloys to overcome traditional manufacturing challenges through layer by layer approach. Among powder-based additive manufacturing processes, the laser beam melting (LBM) and the electron beam melting (EBM) are two promising manufacturing methods for Ni–Ti shape memory alloys. In these methods, the physical characteristics of the powder used as raw material in the process have a significant effect on the powder transformation, deposition, and powder-beam interaction. Thus, the final manufactured material properties are highly affected by the properties of the powder particles. In this study, the Ni?Ti powder characteristics are investigated in terms of particle size, density, distribution and chemical properties using EDS, OM, and SEM analyses in order to determine their compatibility in the EBM process. The solidification microstructure, and after built microstructure are also examined for the gas atomized Ni–Ti powders.     

Gradient Type-II CdSe/CdSeTe/CdTe Core/Crown/Crown Heteronanoplatelets with Asymmetric Shape and Disproportional Excitonic Properties

Characterized by their strong 1D confinement and long-lifetime red-shifted emission spectra, colloidal nanoplatelets (NPLs) with type-II electronic structure provide an exciting ground to design complex heterostructures with remarkable properties. This work demonstrates the synthesis and optical characterization of CdSe/CdSeTe/CdTe core/crown/crown NPLs having a step-wise gradient electronic structure and disproportional wavefunction distribution, in which the excitonic properties of the electron and hole can be finely tuned through adjusting the geometry of the intermediate crown. The first crown with staggered configuration gives rise to a series of direct and indirect transition channels that activation/deactivation of each channel is possible through wavefunction engineering. Moreover, these NPLs allow for switching between active channels with temperature, where lattice contraction directly affects the electron–hole (e–h) overlap. Dominated by the indirect transition channels over direct transitions, the lifetime of the NPLs starts to increase at 9 K, indicative of low dark-bright exciton splitting energy. The charge transfer states from the two type-II interfaces promote a large number of indirect transitions, which effectively increase the absorption of low-energy photons critical for nonlinear properties. As a result, these NPLs demonstrate exceptionally high two-photon absorption cross-sections with the highest value of 12.9 × 10⁶ GM and superlinear behavior.     

Point-of-Care Diagnostic Platforms for Loop-Mediated Isothermal Amplification

The loop-mediated isothermal amplification (LAMP) method is one of the Nucleic acid amplification tests (NAATs) that allows for the amplification of target regions without using a thermal cycle. With its unique primer design, LAMP ensures the rapid replication of the targeted DNA region with high specificity and high efficiency. LAMP technology is used for diagnostic purposes in pathogen detection due to its ease of use, low cost, and simplicity without requiring complex equipment. A wide range of LAMP diagnostic platforms have been developed for applications in bacteria, virus, and parasitic pathogen detection. Herein, the methodology of LAMP technology and its applications in pathogen detection and SNP genotyping and mutation detection are discussed. Point-of-care (PoC) LAMP platforms designed with the principles of microfluidic chip technology, including LAMP-on-a-chip, paper-based LAMP, and smartphone-based LAMP applications have been elaborated. LAMP technology represents a fast, robust, and reliable diagnostic platform for point-of-care testing.