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Selective Laser Sintering 3D Printing a?? An Overview of the Technology and Pharmaceutical Applications
摘要： Food and Drug Administration (FDA) has approved a drug product (Spritam?) and many medical devices manufactured by 3-dimensional printing (3DP) processes for human use. There is immense potential to print personalized medicines using 3DP. Many 3DP methods have been reported in the literature for pharmaceutical applications. However, selective laser sintering (SLS) printing has remained least explored for pharmaceutical applications. There are many advantages and challenges in adopting a SLS method for fabrication of personalized medicines. Solvent free nature, availability of FDA approved thermoplastic polymer/excipients (currently used in hot melt-extrusion process), minimal/no post-processing step, etc. are some of the advantages of the SLS printing process. Major challenges of the technology are requirement of at least one thermoplastic component in the formulation and thermal stability of drug and excipients. This review provides an overview of the SLS printing method, excipient requirements, process monitoring, quality defects, regulatory aspects and potential pharmaceutical applications.
关键词： in-process monitoring,selective laser sintering,personalized medication,3D printing,quality defects,pharmaceuticals
更新于2025-09-23 15:21:01
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Experimental and numerical investigation of selective laser meltinga??induced defects in Tia??6Ala??4V octet truss lattice material: the role of material microstructure and morphological variations
摘要： The remarkable progress in additive manufacturing has promoted the design of architected materials with mechanical properties that go beyond those of conventional solids. Their realization, however, leads to architectures with process-induced defects that can jeopardize mechanical and functional performance. In this work, we investigate experimentally and numerically as-manufactured defects in Ti–6Al–4V octet truss lattice materials fabricated with selective laser melting. Four sets of as-manufactured defects, including surface, microstructural, morphological, and material property imperfections, are characterized experimentally at given locations and orientations. Within the characterized defects, material property and morphological defects are quanti?ed statistically using a combination of atomic force microscopy and micro–computed tomography to generate representative models that incorporate individual defects and their combination. The models are used to assess the sensitivity to as-manufactured defects. Then, the study is expanded by tuning defects amplitude to elucidate the role of the magnitude of as-designed defects on the mechanical properties of the lattice material.
关键词： mechanical properties,octet truss lattice,additive manufacturing,defects,Ti–6Al–4V,selective laser melting
更新于2025-09-23 15:21:01
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Surface Passivation of Perovskite Film by Sodium Toluenesulfonate for Highly Efficient Solar Cells
摘要： Ionic defects at the surfaces of organolead halide perovskite films are detrimental to both the efficiency and stability of perovskite solar cells (PSCs). Herein, sodium p-toluenesulfonate (STS) is applied during the surface modification of perovskite layer for the first time, leading to the efficient surface passivation of the perovskite film and consequently significant enhancements in both efficiency and stability of mixed-cation PSC devices. Upon incorporating STS atop the perovskite layer, the power conversion efficiency of the Cs0.05MA0.12FA0.83PbI2.55Br0.45 (abbreviated as CsMAFA) mesoporous-structure mixed-cation PSC devices improves from 18.70% to 20.05% with reduced hysteresis. The sulfonate (–SO3–) anion of STS coordinates with the Pb2+ of CsMAFA perovskite, and the Na+ cation of STS electrostatically interacts with the anions (I–/Br–) of CsMAFA perovskite, resulting in the surface passivation of the CsMAFA perovskite film with reduced electron and hole trap state densities. In addition, STS modification induces an upshift of the valence band of perovskite, facilitating hole extraction from the perovskite layer to the hole transport layer with suppressed interfacial charge recombination. Moreover, such a trap state passivation of perovskite film leads to improvement of the ambient stability of PSC devices.
关键词： ionic defects,trap state passivations,perovskite solar cells,surface modifications,charge extractions
更新于2025-09-23 15:21:01
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Study of point defects in wide-bandgap Cu <sub/>2</sub> CdGeS <sub/>4</sub> microcrystals by temperature and laser power dependent photoluminescence spectroscopy
摘要： We present temperature and laser power dependent photoluminescence (PL) study of high quality wide-bandgap Cu2CdGeS4 microcrystals. At T = 10 K three PL bands were detected at about 1.919 eV (#1), 1.855 eV (#2) and 1.748 eV (#3). The temperature and laser power dependencies indicate that the properties of PL bands can be explained by donor- acceptor pair model, where the #1 and #2 bands result from a recombination between distant pairs involving ≈ 30 meV and different deep donor defects. The #3 PL the same shallow acceptor VCu with EA band originates from the deep donor-deep acceptor pair recombination where the depth of deep acceptor defect is more than 157 meV. Detailed analysis of the PL spectra show the absence of deep potential or band gap fluctuations in this material making it suitable for photovoltaic applications.
关键词： Cu2CdGeS4,photoluminescence,defects,wide bandgap,donor-acceptor pairs
更新于2025-09-23 15:21:01
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External pressure induced liquid crystal defects for optical vortex generation
摘要： Simple and arbitrary creation of liquid crystal (LC) defects can be highly useful, in particular, for the creation of optical vortex. We report a novel method to create an isolated and stable +1 type concentric LC defect by combing an external pressure on a vertically aligned liquid crystal cell (VALC) and the application of electric fields. The method does not require special material in alignment layer, nor patterned electrodes such as in spatial light modulator, but it can produce stable and rewritable defects in a LC cell. We show that the created +1 defect can be used to generate optical vortices with ±2(cid:125) orbital angular momentum. The simple and cost-effective process and its tunability for the position of defect make the method useful in various applications such as advanced optical communication and quantum computation using tunable optical vortices.
关键词： electric fields,orbital angular momentum,liquid crystal defects,optical vortex generation,external pressure
更新于2025-09-23 15:21:01
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Design of an innovative and self-adaptive-smart algorithm to investigate the structural integrity of a rail track using Rayleigh waves emitted and sensed by a fully non-contact laser transduction system
摘要： The focus of this study is on locating surface and sub-surface defects that occur in rail tracks using Rayleigh waves that were emitted and sensed by a fully non-contact laser transduction system. As the quality of received signals varies with respect to the rail surface characteristics, spotting the reflection from a defect can be extremely challenging. These signals are in general contaminated with noise and have low repeatability that could hinder the proper identification of the defect signal. In view of this, an innovative signal processing technique called a self-adaptive-smart algorithm (SASA) was designed and developed. In SASA, the incident wave that is the first coming wave-packet is taken as a mother wavelet. A library of possible mother wavelets was designed based on the experimental data. As the incident wave for each sensing point varies because of the physical condition of the rail surface and the laser excitation, the algorithm automatically picks the mother wavelet from the library that generates the largest absolute cross-correlation with the incident wave. SASA is found to be able to suppress the unwanted wave packets from the overall signal leaving behind only the incident wave for a healthy specimen, and the incident wave and its reflection from the defect for a damaged specimen. The functioning of the algorithm was successfully tested by carrying out extensive experiments on a real rail track in the presence of different types of surface and sub-surface defects on its head and web. The obtained results prove the effectiveness of using SASA in localizing defects in rails with a marginal error. Notably, the proposed method has benefits such as being self-adaptive, can help suppress high levels of noise, bring the peak of defect reflected wave in the center, and distinguish between a healthy and damaged sample.
关键词： Structural integrity,Subsurface defects,Signal processing,Rail track,Rayleigh wave,Laser system
更新于2025-09-23 15:21:01
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Joint inspection in X-ray #0 belt tire based on periodic texture
摘要： Based on X-ray image of tire with periodic texture, this paper proposes an algorithm of detecting joint in #0 belt. Firstly, by projecting #0 belt image at 45° direction, we divide #0 belt image into several blocks with the same size based on periodic texture. Then, we find out the block containing joint and locate its upper and lower boundaries. Finally, upper and lower boundaries of joint are located by comparing the block containing joint with its corresponding standard block. The standard block is one of segmented blocks in first step. We quantify joint defects in #0 belt (large joint, small joint or appropriate joint), and experimental results show that our algorithm can accurately locate the joint and quantify the size of joint with 3.4% false positive rate and 2% false negative rate, which meets the industrial requirements.
关键词： False negative rate,False positive rate,Locating,Quantify,Joint defects in #0 belt
更新于2025-09-23 15:21:01
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Defects modes in one-dimensional photonic filter star waveguide structure
摘要： In this work, by the formalism of the interface response theory, we study the existence of defects’ modes in the transmission spectrum of a one-dimensional photonic star waveguide (SWG) structure. The perfect structure presents large forbidden bands (gaps) that come from the periodicity of the system and the resonance states of the grafted lateral branches which play the role of the resonators. The defects modes result from the presence of the defects of the lateral branches level located in two different sites. The behavior of the defects’ modes is analyzed as a function of the defects’ lengths, the number of defectives resonators, the positions of the defects’ and the number of sites. This system can be considered as a selective ?lter with high performance.
关键词： Electromagnetic ?lter,Green Function,Star waveguide structure,Defects modes,Gaps
更新于2025-09-23 15:21:01
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Increasing the laser-acoustic method efficiency for testing metal products by using 3D visualization
摘要： The article proposes a solution to the problem of increasing the efficiency of the laser-acoustic method of non-destructive testing. An approach to increasing the probability of detecting surface defects of microscopic dimensions in metals is considered. Due to the increased accuracy of determining defect parameters, the detail of 3D visualization of testing results was improved.
关键词： non-destructive testing,3D visualization,surface defects,metals,laser-acoustic method
更新于2025-09-23 15:21:01
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Hole-doped 2D InSe for spintronic applications
摘要： Using first-principles calculations based on density functional theory, we study the magnetic and electronic properties of hole-doped two-dimensional InSe. Our simulations reveal that although 2D InSe is intrinsically non-magnetic, a stable ferromagnetic phase appears for a wide range of hole densities. Interestingly, hole doping not only induces spontaneous magnetization but also half-metallicity, and hole-doped InSe, presenting one conducting and one insulating spin channel, could be highly promising for next generation spintronic nanodevices. The possibility to induce hole doping and a subsequent ferromagnetic order by intrinsic and extrinsic defects was also investigated. We found that In vacancy creates spin-polarized states close to the valence band and leads to a p-type behavior. Similar to In vacancies, group-V atoms replacing Se atoms lead to a p-type behavior, potentially stabilizing a ferromagnetic order in 2D InSe.
关键词： ferromagnetism,InSe,half-metallicity,hole-doping,defects
更新于2025-09-23 15:21:01