19 research outputs found

    Gaussian Schell-model arrays

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    We introduce a novel class of planar, quasi-homogeneous Schell-model source for producing far fields with optical lattice average intensity patterns and derive the corresponding beam conditions. The array dimension, lobes intensity profile, and periodicity of the optical lattice can be flexibly tuned by changing the correlation parameters of the source field. It is also found that, with an appropriate choice of the source parameters, the radiant intensity may possess flat-topped intensity patterns

    Fabrication and Performance of a Glue-Pressed Engineered Honeycomb Bamboo (GPEHB) Structure with Finger-jointed Ends as a Potential Substitute for Wood Lumber

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    With the increasing scarcity of wood as a natural resource, bamboo has become a popular substitute for wood. The present work developed a high-strength original state multi-reorganization material (GPEHB), without the use of a hot press or traditional assembly. The original bamboo units were polygonized into outer contours and milled into finger-joints on each ending. The GPEHB was organized and assembled under an external press, using industrial adhesives. The mechanical properties and thermal insulation of GPEHB were characterized. Moreover, the overall GPEHB unit bending strength was 73.15 MPa, and the parallel-to-grain compression was 55.22 MPa (higher than that of Pinus sylvestris lumber, though less than that of glued laminated bamboo). The GPEHB unit overall density was 0.24 g/cmÂł, 76% lower than that of glued laminated bamboo, and 50% lower than Pinus sylvestris lumber. The compressive strength of GPEHB (7 units) was 170.5 kN, while the compressive strength of GPEHB for 14 units was 493.5 kN, which meet the requirements of GB 50005 (2003). The bending strength of GPEHB 7 units was 12 kN, while that of 14 units was 37 kN. The heat conductivity coefficient for GPEHB was 0.25 W/mK, which is better than concrete and steel. The GPEHB has taken full advantage of its honeycomb-structured material, which allows it to avoid stress concentration in the regular polygonal corners

    Preparation and Performance Evaluation of Bamboo Lumber Prepared by Assembly and Glue-Curing of Naturally Arc-Shaped Segments with Finger Joints

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    Using bamboo to replace wood has great significance for the protection of forests. This work presents the concept of the reorganization of arc bamboo sheet to produce recombined arc-segment bamboo lumber (RABL). Several key preparation technology parameters were investigated. Results showed that when the phenol resin (PF) double-sided adhesive quantity was 250 g/m2, unit pressure was 2.0 MPa, screen voltage was 4200 V, screen current was 1.5 A, and hot pressing time was 30 s/mm, the modulus of rupture (MOR) of the RABL was 105 MPa and the modulus of elasticity (MOE) was 5000 MPa. These parameters mean that RABL could be used as the structural material for load-bearing situations. If ignoring the machining allowance, the bamboo utilization rate of the RABL was 1.72 times that of the rectangular element recombinant bamboo and the adhesive level of the RABL was 0.6 times that of the rectangular element recombinant bamboo. When considering the machining allowance, the bamboo utilization rate of the RABL was 1.8 times that of the rectangular element recombinant bamboo, and the adhesive volume of the RABL was 0.56 times that of the rectangular element recombinant bamboo, so RABL has obvious advantages

    Random light scattering by collections of ellipsoids

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    Theory of weak scattering of random optical fields from deterministic collections of particles with soft ellipsoidal scattering potentials of arbitrary shapes and orientations is developed. Far-field intensity distribution produced on scattering is shown to be influenced by source correlation properties as well as by a number, shapes and orientations of scatterers. The theory extends previous results on scattering from collections of spheres with soft Gaussian potentials and is applicable to analysis of a wide range of media including blood cells

    Static magnetic field-modulated mesenchymal stem cell-derived mitochondria-containing microvesicles for enhanced intervertebral disc degeneration therapy

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    Abstract Intervertebral disc degeneration (IVDD) is characterized by the senescence and declining vitality of nucleus pulposus cells (NPCs), often driven by mitochondrial dysfunction. This study elucidates that mesenchymal stem cells (MSCs) play a crucial role in attenuating NPC senescence by secreting mitochondria-containing microvesicles (mitoMVs). Moreover, it demonstrates that static magnetic fields (SMF) enhance the secretion of mitoMVs by MSCs. By distinguishing mitoMV generation from exosomes, this study shifts focus to understanding the molecular mechanisms of SMF intervention, emphasizing cargo transport and plasma membrane budding processes, with RNA sequencing indicating the potential involvement of the microtubule-based transport protein Kif5b. The study further confirms the interaction between Rab22a and Kif5b, revealing Rab22a’s role in sorting mitoMVs into microvesicles (MVs) and potentially mediating subsequent plasma membrane budding. Subsequent construction of a gelatin methacrylate (GelMA) hydrogel delivery system further addresses the challenges of in vivo application and verifies the substantial potential of mitoMVs in delaying IVDD. This research not only sheds light on the molecular intricacies of SMF-enhanced mitoMV secretion but also provides innovative perspectives for future IVDD therapeutic strategies

    Switching of the Triplet Excited State of Rhodamine/Naphthaleneimide Dyads: An Experimental and Theoretical Study

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    Rhodamine–bromonaphthaleneimide (<b>RB–NI</b>) and rhodamine–bromonaphthalenediimide (<b>RB–NDI</b>) dyads were prepared for switching of the <i>triplet</i> excited states. Bromo-NI or bromo-NDI parts in the dyads are the spin converters, i.e., the triplet state producing modules, whereas the RB unit is the acid-activatable electron donor/energy acceptor. NI and NDI absorb at 359 and 541 nm, and the T<sub>1</sub> state energy levels are 2.25 and 1.64 eV, respectively. RB undertakes the reversible spirolactam (RB-c) ↔ opened amide (RB-o) transformation. RB-c shows no visible light absorption, and the triplet-state energy level is <i>E</i><sub>T1</sub> = 3.36 eV. Conversely RB-o shows strong absorption at 557 nm, and <i>E</i><sub>T1</sub> is 1.73 eV. Thus, the acid-activated fluorescence-resonance-energy-transfer (FRET) competes with the ISC of NI or NDI. No triplet state was observed for the dyads with nanosecond time-resolved transient absorption spectroscopy. Upon addition of acid, strong fluorescence and long-living triplet excited states were observed. Thus, the producing of triplet state is acid-activatable. The triplet state of <b>RB–NI</b> is <i>localized</i> on RB-o part, whereas in <b>RB–NDI</b> the triplet state is <i>delocalized</i> on both the NDI and RB-o units. The ISC of spin converter was not outcompeted by RET. These studies are useful for switching of triplet excited state
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