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The description of quantum dielectric function for insulators over Bethe surface
摘要： A new expression for the dielectric function is suggested here, which is the Mermin–Belkacem-Sigmund (MBS) model derived from the Belkacem–Sigmund (BS) model based on the conservation of a local particle number in the Mermin model. The energy loss function expressions are reviewed analytically for both models, and these dielectric functions were used to calculate the Bethe sum rule, the energy loss function (ELF), as well as the differential inelastic inverse mean free path (DIIMP) for H2O. The indication from the results is that, compared to the BS dielectric function, the MBS dielectric function is more compatible in its consistency with the exact Bethe sum rule. The ELF for the MBS type is compatible relatively in high and low momentum transfers, while the ELF for the BS type is suitable for high-k. The two models of ELF were also applied to evaluate DIIMP for electron kinetic energy 1 keV, and these were compared with the results predicted in several ways via the SESINIPAC program, using the Mermin dielectric function and the extended Drude and Monte–Carlo method. These predicted results are in reasonable agreement with those estimated from other methods at the range of energy transfer (0–50) eV.
关键词： Bethe surface,differential inelastic inverse mean free path,local particle number,Energy loss function,dielectric function
更新于2025-09-23 15:23:52
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Sacrificial Layer Technique for Releasing Metallized Multilayer SU-8 Devices
摘要： The low fabrication cost of SU-8-based devices has opened the fields of point-of-care devices (POC), μTAS and Lab-on-Chip technologies, which call for cheap and disposable devices. Often this translates to free-standing, suspended devices and a reusable carrier wafer. This necessitates a sacrificial layer to release the devices from the substrates. Both inorganic (metals and oxides) and organic materials (polymers) have been used as sacrificial materials, but they fall short for fabrication and releasing multilayer SU-8 devices. We propose photoresist AZ 15nXT (MicroChemicals GmbH, Ulm, Germany) to be used as a sacrificial layer. AZ 15nXT is stable during SU-8 processing, making it suitable for fabricating free-standing multilayer devices. We show two methods for cross-linking AZ 15nXT for stable sacrificial layers and three routes for sacrificial release of the multilayer SU-8 devices. We demonstrate the capability of our release processes by fabrication of a three-layer free-standing microfluidic electrospray ionization (ESI) chip and a free-standing multilayer device with electrodes in a microchannel.
关键词： microfabrication,microfluidics,free standing,microchips,SU-8,sacrificial release,multi layered chips,AZ 15nXT
更新于2025-09-23 15:23:52
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Free-standing highly conducting PEDOT films for flexible thermoelectric generator
摘要： Recently, organic thermoelectric (TE) materials especially conducting polymers have attracted increasing attention. In this work, we successfully synthesized ultrafine poly (3,4-ethylenedioxythiophene) (PEDOT) nanowires (NWs) (~10 nm) by a simple self-assembled micellar soft-template method and then obtain highly flexible free-standing PEDOT NW films by vacuum-assisted filtration. The films are with very high electrical conductivity (~1340 S cm?1). After being treated with 6 M H?SO? and then with 1 M NaOH at room temperature, the film shows an enhanced power factor of 46.51 μW m?1 K?2 (Seebeck coefficient of 25.5 μV K?1, electrical conductivity of 715.3 S cm?1), which increases by 54% compared with that of the pristine film. To the best of our knowledge, it outperforms the TE performance of all reported one-dimensional conducting polymer-based films. In addition, the TE performance of the film almost remains unchanged even after being bent for 200 times, indicating excellent flexibility. A flexible TE prototype composed of six strips (7 mm × 30 mm) of the as-prepared PEDOT NW films connected in series shows an output power of 157.2 nW at a temperature difference of 51.6 K. The free-standing PEDOT NW films show promise to a new generation of wearable TE devices.
关键词： Flexible,Thermoelectric,Free-standing,PEDOT,Highly conductive
更新于2025-09-23 15:23:52
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Covalent organic framework as an efficient, metal-free, heterogeneous photocatalyst for organic transformations under visible light
摘要： Visible-light active, heterogeneous, and organic photocatalysts exhibit a more sustainable and environmentally friendly alternative to classical metal-based catalysts. Two-dimensional covalent organic frameworks (2D-COFs) with permanent porosity, columnar π-arrays and excellent stability, that can become an excellent platform for heterogeneous photocatalysis of organic transformations. Here we report a predesigned imine-based COF with electron donor and acceptor structure. And new framework possesses large surface area, high crystallinity, outstanding stability and broad absorption range in the visible-light region as well as good photoelectric response characteristics. Importantly, it was found to be a highly effective heterogeneous photocatalyst for reductive dehalogenation of phenacyl bromide derivatives and α-alkylation of aldehydes under irradiation of visible-light. In addition, the COF gave good recyclability and could be reused after a simple separation manipulation. The current present still reveals a great prospect for 2D-COFs as metal-free, heterogeneous photocatalysts for organic transformations.
关键词： visible light,photocatalysis,heterogeneous catalysis,metal-free,covalent organic frameworks
更新于2025-09-23 15:23:52
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Flexible all-organic photorefractive devices
摘要： The objective of the present study is to demonstrate and evaluate the photorefractive (PR) performance of an all-organic PR device with a self-assembled monolayer (SAM)-modified organic conductive electrode of PEDOT:PSS coated on polyethylene terephthalate (PET). The PR composite consisted of a triphenylamine-based photoconductive polymer: poly(4-(diphenylamino)benzylacrylate) (PDAA), triphenylamine photoconductive plasticizer: (4-(diphenylamino)phenyl)methanol (TPAOH), nonlinear optical dye based on aminocyanostyrene: (4-asacycloheptylbenzylidenemalononitrile) (7-DCST), and soluble fullerene: [6, 6]-phenyl C61 butyric acid-methyl ester (PCBM). For comparison with the all-organic PR device, the PR performances using PET/ITO, glass/ITO, and glass/PEDOT:PSS substrates were also evaluated. The PR performance at an applied electric field of 40 V μm-1: diffraction efficiency and the response time of the PR device using PET/PEDOT:PSS-SAM substrate were 21.9%, and 390 ms, respectively. As a result of repeating bending test on this all-organic PR device, we found that the flexible PR device with PET/PEDOT:PSS-SAM substrate had a potential to withstand bending 10,000 times and revealed that the change in the haze value strongly influenced the degradation of PR performance.
关键词： All-organic,Photorefractive polymer,ITO-free device,PET substrate,PEDOT:PSS,Flexible
更新于2025-09-23 15:23:52
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Hypoxia-Irrelevant Photonic Thermodynamic Cancer Nanomedicine
摘要： The hypoxic tumor microenvironment severely lowers the therapeutic efficacy of oxygen-dependent anticancer modalities because tumor hypoxia hinders the generation of toxic reactive oxygen species. Here we report a thermodynamic cancer-therapeutic modality that employs oxygen-irrelevant free radicals generated from thermo-labile initiators for inducing cancer-cell death. Free radical nanogenerator was engineered via direct growth of mesoporous silica layer onto the surface of two-dimensional Nb2C MXene nanosheets towards multifunctionality, where the mesopore provided the reservoirs for initiators and MXene core acted as the photonic-thermal trigger at near infrared-II biowindow (NIR-II). Upon illumination by a 1064 nm NIR-II laser, the photothermal-conversion effect of Nb2C MXene induced the fast release and quick decomposition of the encapsulated initiators (AIPH) to produce free radicals, which promoted cancer-cell apoptosis in both normoxic and hypoxic microenvironment. Systematic in vitro and in vivo evaluations have demonstrated the synergistic-therapeutic outcome of this intriguing photonic nanoplatform-enabled thermodynamic cancer therapy for completely eradicating the tumors without recurrence by NIR-II laser irradiation. This work pioneers the thermodynamic therapy for oxygen-independent cancer treatment by photonic triggering at NIR-II biowindow.
关键词： nanomedicine,thermodynamic therapy,photothermal effect,tumor hypoxia,free radicals
更新于2025-09-23 15:23:52
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Large electric field-induced strain in ternary Bi0.5Na0.5TiO3-BaTiO3-Sr2MnSbO6 lead-free ceramics
摘要： The large electric-field-induced strain of Bi0.5Na0.5TiO3-BaTiO3 based ceramic make it a potential replacement for lead-based ferroelectrics in actuator applications. Herein, a ternary system (1-x)(Bi0.5Na0.5)0.935Ba0.065TiO3-xSr2MnSbO6 (BNBT6.5-xSMS) ceramic was fabricated using conventional solid-state reaction. It was found that the ferroelectric to relaxor phase transition temperature TF-R gradually shifted to lower temperature by increasing SMS contents. The ferroelectricity and piezoelectricity of BNBT6.5 were highly affected by trace amount of SMS doping. For composition BNBT6.5-0.003SMS, where TF-R was near room temperature, a large electric-field-induced unipolar strain of ~0.4% with high normalized strain (Smax/Emax) of 728 pm/V, which is comparable to lead-based ferroelectric/antiferroelectric ceramics, was achieved owing to the reversible electric-field-induced phase transition between a non-polar relaxor phase to a polar phase with long-range ferroelectric order.
关键词： electric-field-induced phase transition,ferroelectric,Lead-free ceramics,Bi0.5Na0.5TiO3
更新于2025-09-23 15:23:52
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[IEEE 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Paris, France (2018.10.14-2018.10.17)] 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Biomass Free Piston Stirling Engine Generator with PV
摘要： Proposed hybrid electric power generation system is constituted from Free Piston Stirling engine generator and solar photovoltaic system. Free Piston Stirling engine electric generator uses biomass, such as wood pellets as the heat source. This system produces maximum output of 1.6kW and 45°C 200L hot water with linear generator. This paper studied the control of output voltage of Free Piston Stirling Engine. ILQ (Inverse Linear Quadratic) control theory is used to keep output active power between 400W and 500W. In long range time constant of burning system and in short range time constant of electrical circuit, experiment yields temperature of FPSEG head between upper limit and lower limit.
关键词： hybrid system,Free Piston Stirling Engine,biomass,solar power,ILQ control
更新于2025-09-23 15:23:52
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Fluorometric determination of glucose based on a redox reaction between glucose and aminopropyltriethoxysilane and in-situ formation of blue-green emitting silicon nanodots
摘要： A method is described for fluorometric detection of glucose. It is based on the finding that silicon nanodots (SNDs) are formed from glucose and aminopropyltriethoxysilane (APTES) under mild experimental conditions. The SNDs thus formed have an average diameter of ～2 nm, exhibit good water dispersibility, blue fluorescence (with excitation/emission maxima at 410/475 nm), broad pH tolerance, and are photostable. The assay was applied to the quantification of glucose with high sensitivity, good specificity, and over a wide detection range (from 10 μM to 0.9 mM). It was applied to the determination of glucose in spiked serum samples and gave satisfactory results and recoveries.
关键词： Fluorescence detection,Enzyme-free analysis,Diabetes,Silicon nanoparticles
更新于2025-09-23 15:23:52
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Micro Grating Deposition on Non-Planar Surfaces by Polymer-Assisted Transfer Printing
摘要： By spin-coating a few hundred of nanometer thick poly(methyl methacrylate) (PMMA) film on a micron or a sub-micron scale structure, the structure can be transferred on an arbitrary substrate. More precisely, by using a thin PMMA support layer and releasing the structure from the transient substrate into water, the PMMA with the structure can be collected on a desired substrate. Here, this technique is demonstrated to be suitable for transferring metallic binary grating and few-layer Bragg gratings from flat substrates onto 3D-printed convex lenses. Moreover, the thin PMMA film is sufficiently strong to support centimeter size free-standing areas. This enables fabrication of 1.5 μm thick, free-standing structure of a Bragg-grating with PMMA. Thus, the presented technique provides a powerful tool for transfer printing of micron scale structures.
关键词： transfer printing,non-planar surfaces,free-standing structures,microstructure transfer
更新于2025-09-23 15:23:52