Upconversion emissions of Yb3+/Er3+-codoped germanate-tellurite glasses have been investigated upon the excitation of 980 nm laser diode (LD). It is found that up- conversion luminescence intensities significantly inc...
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Upconversion emissions of Yb3+/Er3+-codoped germanate-tellurite glasses have been investigated upon the excitation of 980 nm laser diode (LD). It is found that up- conversion luminescence intensities significantly increase with the increasing size of alkali metal ions. Raman spectra show that the maximum phonon energies (MPE) of glass hosts are unchanged with the replacement of alkali metal oxides, indicating that MPE is not the reason for the increase of upconversion fluorescence intensities. The analysis of the non-radiative transition of Er3+ demonstrates that the de- crease of the maximum energy phonon density is the main reason for the enhanced fluorescence intensities.
Innovative advancements in the development of high-performance,eco-friendly adhesives are critical for meeting the demands of diverse applications in various *** study reports a significant leap in adhesive technology...
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Innovative advancements in the development of high-performance,eco-friendly adhesives are critical for meeting the demands of diverse applications in various *** study reports a significant leap in adhesive technology by enhancing the interfacial toughness and versatility of polyvinyl alcohol(PVA)through complexation with 1-nm Keggin-type polyoxotungstate clusters(POTs)carrying specific negative *** POT-PVA nanocomposites exhibit superior adhesion to hydrophilic surfaces,attributed to their high crosslinking densities and exceptional fracture energies surpassing 6.23 kJ·m^(-2).These adhesives,endowed with high flexibility and a wealth of surface hydroxyl groups,are uniquely suited for application on a wide array of substrates including glass,steel,aluminum,and beyond,demonstrating their broad ***,the reduction in PVA crystallinity due to the chaotropic effect of POTs,which significantly enhances polymer chain *** enhancement confers robust adhesive properties at extreme temperatures,from the cryogenic−196℃ to the high-temperature threshold of 100℃.By capitalizing on the chaotropic effects of charged POTs,the study achieves a notable enhancement in the adhesive capabilities of the POT-PVA nanocomposites,paving the way for the development of for eco-friendly and cost effective adhesives engineered to withstand extreme conditions.
The preparation of fine copper powders by chemical reduction method was investigated. The reaction of [Cu（NH3）4]2^＋ complex with hydrazine hydrate gives spherical monodispersed fine copper powders. The spherical co...
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The preparation of fine copper powders by chemical reduction method was investigated. The reaction of [Cu（NH3）4]2^＋ complex with hydrazine hydrate gives spherical monodispersed fine copper powders. The spherical copper powder with a uniform size of 3.5 ± 0.5 μtm was processed to obtain flake copper powder having a uniform size of 8-10 μm, excellent dispersibility and uniform shape. The spherical copper powder of 2.5 ±0.3 μm in size, flake copper, glass frit and vehicle were mixed to prepare copper paste, which was fired in 910-920℃ to obtain BME-MLCC （base metal multilayer ceramic capacitor） with a dense surface of end termination, high adhesion and qualified electrical behavior. Polarized light photo and SEM were employed to observe the copper end termination of BME-MLCC. The rough interface from the interracial reaction between glass and chip gives high adhesion.
Measuring the complex permittivity of ultrathin,flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods,and verifying the accuracy of test results remains **...
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Measuring the complex permittivity of ultrathin,flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods,and verifying the accuracy of test results remains *** this study,we introduce a methodology based on a back-propagation artificial neural network(ANN)to extract the complex permittivity of paper-based composites(PBCs).PBCs are ultrathin and flexible materials exhibiting considerable complex permittivity and dielectric loss *** the absence of mature measurement methods for PBCs and a lack of sufficient data for ANN training,a mapping relationship is initially established between the complex permittivity of honeycomb-structured microwave-absorbing materials(HMAMs,composed of PBCs)and that of PBCs using simulated *** the ANN model,the complex permittivity of PBCs can be extracted from that of HMAMs obtained using standard ***,two published methods are cited to illustrate the accuracy and advancement of the results obtained using the proposed ***,specific error analysis is conducted,attributing discrepancies to the conductivity of PBCs,the homogenization of HMAMs,and differences between the simulation model and actual ***,the proposed method is applied to optimize the cell length parameters of HMAMs for enhanced absorption *** conclusion discusses further improvements and areas for extended research.
This paper introduces a four-dimensional （4D） segmented disc dynamo which possesses coexisting hidden attractors with one stable equilibrium or a line equilibrium when parameters vary. In addition, by choosing an ap...
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This paper introduces a four-dimensional （4D） segmented disc dynamo which possesses coexisting hidden attractors with one stable equilibrium or a line equilibrium when parameters vary. In addition, by choosing an appropriate bifurcation parameter, the paper proves that Hopf bifurcation and pitchfork bifurcation occur in the system. The ultimate bound is also estimated. Some numerical investigations are also exploited to demonstrate and visualize the corresponding theoretical results.
The fundamentals of a new method of theoretically studying the kinetics of the phase transformation with nudeation and growth mechanism are ***,heterogeneous system,the survival probability of the individual sites for...
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The fundamentals of a new method of theoretically studying the kinetics of the phase transformation with nudeation and growth mechanism are ***,heterogeneous system,the survival probability of the individual sites for the given annealing time can be calculated by the present treatment,so that the kinetics equation under general conditions can be *** comparison to the classical treatment,the new derivations are not only rigorous and transparent,but also can be used to deal with the non-homogeneous systems and the non-steady *** the problems concerning the interference of more than one simultaneously occurring transformations and the correlation between different sites can be studied.
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