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Laser‐Assisted Strain Engineering of Thin Elastomer Films to Form Variable Wavy Substrates for Cell Culture
摘要： Endothelial and epithelial cells usually grow on a curved environment, at the surface of organs, which many techniques have tried to reproduce. Here a simple method is proposed to control curvature of the substrate. Prestrained thin elastomer films are treated by infrared laser irradiation in order to rigidify the surface of the film. Wrinkled morphologies are produced upon stress relaxation for irradiation doses above a critical value. Wrinkle wavelength and depth are controlled by the prestrain, the laser power, and the speed at which the laser scans the film surface. Stretching of elastomer substrates with a “sand clock”-width profile enables the generation of a stress gradient, which results in patterns of wrinkles with a depth gradient. Thus, different combinations of topography changes on the same substrate can be generated. The wavelength and the depth of the wrinkles, which have the characteristic values within a range of several tens of μm, can be dynamically regulated by the substrate reversible stretching. It is shown that these anisotropic features are efficient substrates to control polarization of cell shapes and orientation of their migration. With this approach a flexible tool is provided for a wide range of applications in cell biophysics studies.
关键词： cell curvotaxis,laser treatment,curvature,dynamic substrates,strain engineering
更新于2025-11-21 11:08:12
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Origin of Ferroelectricity in Epitaxial Si-doped HfO2 Films
摘要： HfO2-based unconventional ferroelectric (FE) materials were recently discovered and have attracted a great deal of attention in both academia and industry. The growth of epitaxial Si-doped HfO2 films has opened up a route to understand the mechanism of ferroelectricity. Here, we used pulsed laser deposition (PLD) to grow epitaxial Si-doped HfO2 films in different orientations of N-type SrTiO3 substrates. Using piezoforce microscopy, polar nanodomains can be written and read, and these domains are reversibly switched with a phase change of 180o. Films with different thicknesses displayed a coercive field Ec and a remnant polarization Pr of approximately 4～5 MV/cm and 8～32 μC/cm2, respectively. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results identified that the as-grown Si-doped HfO2 films have strained fluorite structures. The ABAB stacking mode of the Hf atomic grid observed by HRTEM clearly demonstrates that the ferroelectricity originates from the noncentrosymmetric Pca21 polar structure. Combined with soft X-ray absorption spectra (XAS), it was found that the Pca21 ferroelectric crystal structure manifested as O sublattice distortion by the effect of interface strain and Si dopant interactions, resulting in further crystal-field splitting as a nanoscaled ferroelectric ordered state.
关键词： HRTEM,PLD,XRD,Ferroelectricity,PFM,XAS,Epitaxial Si-doped HfO2 thin films,N-type SrTiO3 substrates
更新于2025-11-14 17:04:02
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Preparation of ellipsoidal rod-shaped silica nanocomposite abrasives by Chromium ion/PEG200 induced method for sapphire substrates chemical mechanical polishing
摘要： Abrasive is vital to sapphire substrates chemical mechanical polishing and provides the most critical support for ?attening of sapphire. This work proposed a method to prepare ellipsoidal rod-shaped silica nanocomposite abrasives in order to increase the material removal rate and improve the surface roughness, which were applied to chemical mechanical polishing on sapphire substrates. Ellipsoidal rod-shaped silica nanocomposite abrasives were prepared by Chromium ion/PEG200 induced method. In this work, the synthesis process of ellipsoidal rod-shaped silica nanocomposite abrasives was discussed. As an inducing agent, Chromium compounds were bonded with two SiO2 particles via chemical bonds. And ellipsoidal rod-shaped silica nanocomposite abrasives were coated by PEG200 via hydrogen bonds. Results from X-ray photoelectron spectroscopy and time-of-?ight secondary ion mass spectroscopy revealed the occurrence of solid-state chemical reactions. The contact angle tests indicated the polishing liquid containing ellipsoidal rod-shaped silica nanocomposite abrasives had a good wettability. Ellipsoidal rod-shaped silica nanocomposite abrasives showed an excellent chemical mechanical polishing performance with a higher material removal and a lower surface roughness due to an excellent combination of chemical effect and mechanical effect occurred between ellipsoidal rod-shaped silica nanocomposite abrasives and sapphire substrates. A material removal model was built to describe the polishing behavior of ellipsoidal rod-shaped silica nanocomposite abrasives.
关键词： Polishing mechanism,Sapphire substrates,Ellipsoidal rod-shaped silica nanocomposite abrasives,Chemical mechanical polishing
更新于2025-11-14 15:27:09
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Towards High Solar Cell Efficiency with Low Material Usage: 15% Efficiency with 14 ?μm Polycrystalline Silicon on Glass
摘要： This work showcases a bottom-up approach to creating silicon solar cells using a line-shaped laser. We report efforts to create thicker amorphous silicon passivation and contact layers as well as laser firing for low contact resistance. Collectively, a new in-house record efficiency of 15.1 % was achieved along with a clear pathway to reach 16 % efficiency with optimization of series resistance.
关键词： Foreign substrates,Liquid phase crystallized silicon,Passivation,Silicon Heterojunction Interdigitated back contact,Laser fired contacts
更新于2025-11-14 15:25:21
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Ion beam measurements for the investigation of TiN thin films deposited on different substrates by vacuum arc discharge
摘要： Titanium nitride thin films were deposited on different substrates using vacuum arc discharge system. Simultaneous ion beam analysis measurements including elastic backscattering (EBS) and nuclear reaction analysis (NRA); were applied for both composition analysis and thickness measurements of the prepared TiN films. Experimental conditions have been optimized to avoid overlapping of peaks of different nuclear reactions products, especially those related to interaction between ion beam and light elements present in totally different substrates. Independent compliment measurements utilizing time-of-flight elastic recoil detection analysis (TOF-ERDA), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) measurements were also applied to verify the experimental findings obtained by EBS and NRA measurements. The results have shown that all prepared TiN films have N/Ti ratio of around 1, with low levels of contamination elements.
关键词： IBA,TiN film,XRD,Substrates,SEM/EDX,Vacuum arc discharge
更新于2025-09-23 15:23:52
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Comparative investigation of performances for HIT-PV and PVT systems
摘要： Crystalline silicon heterojunction solar cells are a promising candidate for high efficiency solar cells, and the heterojunction photovoltaic (HIT-PV) module is strongly dependent on the temperature. In this study, we design three heterojunction photovoltaic modules to improve the performance by preventing from over-heating, with, glass, Tedlar/Polyethylene terephthalate/Tedlar (TPT) and aluminum substrates, respectively. The efficiencies of those HIT-PV modules are investigated under four different outdoor climates. The aluminum-module shows the best thermal dissipation; while the glass-module/TPT-module have the better electrical efficiency and electrical energy, since there is the high reflectivity layer on the surface of the glass (and TPT) substrates rather than the aluminum substrate. In order to increase the output power of HIT-PV modules, we design a heterojunction photovoltaic thermal (HIT-PVT) system based on HIT solar cells and aluminum thermal collector. The measured results of HIT-PVT system show that the coolant circulation increase the output power, and the HIT-PVT module can provide the domestic hot water supply (up to 51.2 °C) under outdoor conditions. In addition, the cost of HIT-PVT systems are much lower than those of the conventional photovoltaic systems, and the investment payback time can be less than 3 years.
关键词： Electrical energy,HIT-PV module,Three substrates,Aluminum thermal collector
更新于2025-09-23 15:23:52
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Direct detection of cysteine peptidases for MALDI-TOF MS analysis using fluorogenic substrates
摘要： A method is described for the direct detection of unstable cysteine peptidase activity in polyacrylamide gels after native electrophoresis using new selective fluorogenic peptide substrates, pyroglutamyl-phenylalanyl-alanyl-4-amino-7-methylcoumaride and pyroglutamyl-phenylalanyl-alanyl-4-amino-7-trifluoromethyl-coumaride (Glp-Phe-Ala-AFC). The detection limit of the model enzyme papain was 17 pmol (0.29 μg) for Glp-Phe-Ala-AMC and 43 pmol (0.74 μg) for Glp-Phe-Ala-AFC, with increased sensitivity and selectivity compared to the traditional method of protein determination with Coomassie G-250 staining or detection of activity using chromogenic substrates. Using this method, we easily identified the target digestive peptidases of Tenebrio molitor larvae by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analysis. The method offers simplicity, high sensitivity, and selectivity compared to traditional methods for improved identification of unstable cysteine peptidases in multi-component biological samples.
关键词： Postelectrophoretic activity,Cysteine peptidases,Fluorogenic substrates,Tenebrio molitor,Native electrophoresis
更新于2025-09-23 15:23:52
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Vertical GaN Schottky barrier diodes on Ge-doped free-standing GaN substrates
摘要： Vertical GaN Schottky barrier diodes (SBDs) were fabricated on Ge-doped free-standing GaN substrates grown by hydride vapor phase epitaxy. Detailed material characterization was performed, and the results indicate the superiority of Ge doping in the GaN, which contributed to the SBDs with lower stress, fewer defects and higher quality. Based on the capacitance-voltage and currentevoltage measurements performed, SBDs achieved together with a low turn-on voltage Von (0.71e0.74 V), high current Ion/Ioff ratio (3.9 (cid:1) 107e2.9 (cid:1) 108), high Schottky barrier height (0.96e0.99 eV), and high breakdown voltage Vb (802 V for a 100 mm diameter). This shows that vertical GaN SBDs on the Ge-doped substrates are promising candidates for high power applications.
关键词： GaN device,Vertical SBDs,Low turn-on voltage,Ge-doped GaN substrates,High breakdown voltage
更新于2025-09-23 15:23:52
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New Assay Method Based on Raman Spectroscopy for Enzymes Reacting with Gaseous Substrates
摘要： Enzyme activity is typically assayed by quantitatively measuring the initial and final concentrations of the substrates and/or products over a defined time period. For enzymatic reactions involving gaseous substrates, the substrate concentrations can be estimated either directly by gas chromatography or mass spectrometry, or indirectly by absorption spectroscopy, if the catalytic reactions involve electron transfer with electron mediators that exhibit redox-dependent spectral changes. We have developed a new assay system for measuring the time course of enzymatic reactions involving gaseous substrates based on Raman spectroscopy. This system permits continuous monitoring of the gas composition in the reaction cuvette in a non-invasive manner over a prolonged time period. We have applied this system to the kinetic study of the [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F. This enzyme physiologically catalyzes the reversible oxidation of H2 and also possesses the non-physiological functions of H/D exchange and nuclear spin isomer conversion reactions. The proposed system has the additional advantage of enabling us to measure all of the hydrogenase-mediated reactions simultaneously. Using the proposed system, we confirmed that H2 (the fully exchanged product) is concomitantly produced alongside HD by the H/D exchange reaction in the D2/H2O system. Based on a kinetic model, the ratio of the rate constants of the H/D exchange reaction (k) at the active site and product release rate (kout) was estimated to be 1.9±0.2. The proposed assay method based on Raman spectroscopy can be applied to the investigation of other enzymes involving gaseous substrates.
关键词： kinetic experiment,H/D exchange reaction,quantitative analysis of gaseous substrates,Raman spectroscopy,non-invasive measurement,[NiFe] hydrogenase
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE CPMT Symposium Japan (ICSJ) - Kyoto, Japan (2018.11.19-2018.11.21)] 2018 IEEE CPMT Symposium Japan (ICSJ) - A 77GHz Antenna-in-Package with Low-Cost Solution for mm Wave System Integration
摘要： This work provides Antenna in package (AiP) implemented on Advanced single sided substrates (aS3 package) , which utilizes low-cost substrate and low-cost assembly process. The dipole antenna implemented on aS3 package results in a peak gain of 5 dBi at operating frequency band. The return loss of < - 10 dB bandwidth is from 65 to 81 GHz. The resonant rectangular series-fed patch array implemented on aS3 package results in a peak gain of 8 dBi at operating frequency band. The return loss of < - 10 dB bandwidth is from 76 to 81 GHz. The antenna performance of antenna on aS3 package meets the requirements of 77 GHz automotive radar systems. This work also discuss with the impact of fabrication inaccuracies on the antenna bandwidth and gain. For 77 GHz automotive radar application, the corner analysis of process variation supports correct antenna performance and a short time to market.
关键词： Advanced single sided substrates (aS3 package),fabrication inaccuracies,resonant rectangular series-fed patch array,dipole antenna,Antenna in package (AiP),77 GHz automotive radar systems
更新于2025-09-23 15:22:29