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STRUCTURING OF DIAMOND FILMS USING MICROSPHERE LITHOGRAPHY
摘要： In this study, the structuring of micro- and nanocrystalline diamond thin films is demonstrated. The diamond films are structured using the technique of microsphere lithography followed by reactive ion etching. Specifically, this paper presents a four-step fabrication process: diamond deposition (microwave plasma assisted chemical vapor deposition), mask preparation (by the standard Langmuir-Blodgett method), mask modification and diamond etching. A self-assembled monolayer of monodisperse polystyrene (PS) microspheres with close-packed ordering is used as the primary template. Then the PS microspheres and the diamond films are processed in capacitively coupled radiofrequency plasma using various plasma chemistries. This fabrication method illustrates the preparation of large arrays of periodic and homogeneous hillock-like structures. The surface morphology of the processed diamond films is characterized by scanning electron microscopy and with the use of an atomic force microscope. The potential applications of these diamond structures in various fields of nanotechnology are also briefly discussed.
关键词： polystyrene microspheres,nanostructuring,scanning electron microscopy,reactive ion etching,diamond thin films
更新于2025-09-09 09:28:46
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Dual-Emission Fluorescent Microspheres for the Detection of Biothiols and Hg2+
摘要： Dual-emission nanosensor for Hg2+ detection was prepared by coupling CA-AEAPMS on the surface of RBS-doped modified silica microspheres. The CA-AEAPMS was synthesized by using N-(β-aminoethyl)-γ-aminopropyl methyldimethoxysilane (AEAPMS) and citric acid as the main raw material. The obtained nanosensor showed characteristic fluorescence emissions of Rhodamine B (red) and CA-AEAPMS (blue) under a single excitation wavelength (360 nm). Upon binding to Hg2+, only the fluorescence of CA-AEAPMS was quenched, resulting in the ratiometric fluorescence response of the dual-emission silica microspheres. This ratiometric nanosensor exhibited good selectivity to Hg2+ over other metal ions, because of the amide groups on the surface of CA-AEAPMS serving as the Hg2+ recognition sites. The ratio of F450/F580 linearly decreased with the increasing of Hg2+ concentration in the range of 0 to 3 × 10?6 M, and a detection limit was as low as 97 nM was achieved. Then, the addition of three thiol-containing amino acids (Cys, Hcy, GSH) to the quenched fluorescence solution with Hg2+ can restore the fluorescence, and the detection limits of the three biothiols (Cys, Hcy, GSH) are 0.133 μM, 0.086 μM, and 0.123 μM, respectively.
关键词： dual-emission,fluorescence,silica microspheres
更新于2025-09-09 09:28:46
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Hollow Plasma-Sprayed Spherical Nanostructured Titania Feedstock for Photocatalytic Applications
摘要： There have been persistent challenges in thermal spraying of nanoparticles feedstock for making nanostructured coatings with desired mechanical strength. Here we report fabrication of nanostructured titania coatings by atmospheric plasma spraying of hollow titania spheres, and microstructures and photocatalytic activities of the coatings are examined. The hollow microspheres are * 50 lm in diameter and possess a mesoporous shell of 1-3 lm in thickness. The coatings show micro-nano hybrid structures with well-retained titania nanoparticles and agglomerated granules. High anatase content is achieved in the coatings, suggesting that constrained heating of the particles effectively prevents the transformation from anatase to rutile. The spherical characteristics of the organic materials in the feedstock powder play dominant roles in regulating the physicochemical characteristics of the coatings for photocatalytic performances. These results would provide insight into large-scale thermal spray fabrication of nanostructured coatings using appropriately designed hollow spherical powder.
关键词： nanostructured coatings,plasma spray,titania nanoparticles,photocatalytic performances,hollow microspheres
更新于2025-09-09 09:28:46
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Total Retinal Blood Flow in a Nonhuman Primate Optic Nerve Transection Model Using Dual-Beam Bidirectional Doppler FD-OCT and Microsphere Method
摘要： PURPOSE. We validated noninvasive Doppler-optical coherence tomography (OCT) blood ?ow measurements against the terminal microsphere method in a surgical induced optic nerve transection nonhuman primate model. METHODS. In 6 nonhuman primates, total retinal blood ?ow (TRBF) was measured with a custom-built dual-beam bidirectional Doppler Fourier Domain (FD)-OCT. Peripapillary retinal nerve ?ber layer thickness (RNFLT) was measured by Spectralis spectral-domain (SD)-OCT. Measurements were performed every 10 to 15 days before and after unilateral optic nerve transection (ONT) until RNFLT was reduced by more than 40% from baseline. Before the animals were killed, TRBF was measured using the microsphere technique. RESULTS. A signi?cant correlation between all arterial and venous Doppler OCT TRBF measurements was found in ONT and contralateral control eyes (both P < 0.01, n ? 6). The Bland-Altman analysis showed a bias of 0.57 in the ONT group and 0.02 in the contralateral control group. Also, excellent agreement was observed between Doppler OCT and microsphere measurements (P < 0.01, r ? 0.976, bias ? 0.54). After ONT, TRBF and RNFLT decreased by (cid:2)51% 6 42% and (cid:2)44% 6 2% (n ? 5), respectively. In the contralateral control eyes, TRBF and RNFLT were unchanged. CONCLUSIONS. Very good accordance was found between TRBF measurements, obtained with dual-beam bidirectional Doppler FD-OCT and the microsphere method. It also was possible to monitor changes over time in TRBF after ONT with Doppler OCT. These ?ndings highlight the accuracy and potential of noninvasive Doppler OCT to provide valuable information for detecting early changes in ocular disease in future.
关键词： microspheres,optic nerve transection,total retinal blood ?ow,Doppler OCT,nonhuman primate
更新于2025-09-09 09:28:46
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Superfast, Porous and Organic Solvent Sensitive Actuator Based on EVOH Nanofibrous Membrane and PS Microspheres
摘要： Despite much progress in solvent-sensitive actuators, most of the actuators are sensitive to water, ethanol or acetone with low responsive speed and small curvature. Herein, a simple approach was introduced to fabricate a new solvent-sensitive bilayer actuator consisting of poly(vinyl alcohol-co-ethylene) (EVOH) nanofibrous membrane and polystyrene (PS) microspheres. The actuator showed superfast and multi-stimulus responsive ability to organic vapors of toluene, chloroform, THF and acetone. With solvents stimulation, the difference in swelling degree between the EVOH layer and PS microspheres layer contributed to the asymmetric expansions or contractions of two layers, therefore resulting in the mechanical deformation of the actuator. The flexible and porous EVOH nanofibrous membrane, as well as the spherical PS could improve the response rate and deformation scale. This bilayer actuator could bend quickly into a multi-coil with the curvature of 21.02 cm-1 within 0.15 s in response to toluene vapor, and the bending-unbending process could repeat more than 150 times when the deformation degree was controlled by cross-linking PS microspheres with divinylbenzene (DVB). This study will provide an important insight for the development of new solvent-sensitive devices and applications in volatile organic compounds detecting.
关键词： PS microspheres,EVOH nanofibrous membrane,multi-stimulus responsive,organic vapors,solvent-sensitive actuators
更新于2025-09-09 09:28:46
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Versatile polymeric microspheres with tumor-microenvironment bioreducible degradation, pH-activated surface charge-reversal, pH-triggered “off-on” fluorescence and drug release as theranostic nanoplatforms
摘要： Facile approach has been developed for the versatile polymeric microspheres with tumor-microenvironment bioreducible degradation, pH-activated surface charge-reversal, pH-triggered “off-on” fluorescence and drug release via emulsion copolymerization of glycidyl methacrylate (GMA), poly(ethylene glycol) methyl ether methacrylate (PEGMA), N-rhodamine 6G-ethyl-acrylamide (Rh6GEAm) with N,N-bis(acyloyl)cystamine) (BACy) as disulfide crosslinker and functionalization. The final PGMA-DMMA microspheres showed excellent cytocompatibility, pH-triggered surface charge reversal at pH 5-6, strong fluorescence only in acidic media, and bioreducible degradation with high reductant level, indicating their promising application as theranostic nanoplatforms for precise imaging-guided diagnosis and chemotherapy. The DOX-loaded PGMA-DMMA microspheres with a drug-loading capacity of 18% and particle size of about 150 nm possessed unique pH/reduction dual-responsive controlled release, with a cumulative DOX release of 60.5% within 54 h at the simulated tumor microenvironment but a premature leakage of < 8.0% under the simulated physiological condition. Enhanced inhibition efficacy against HepG2 cells was achieved than the free DOX.
关键词： tumor-microenvironment bioreducible degradation,pH-triggered “off-on” fluorescence,pH-triggered drug release,theranostic nanoplatforms,pH-activated surface charge-reversal,polymeric microspheres
更新于2025-09-09 09:28:46
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Citric acid-modulated in situ synthesis of 3D hierarchical Bi@BiOCl microsphere photocatalysts with enhanced photocatalytic performance
摘要： 3D hierarchical Bi@BiOCl microspheres were successfully synthesized by a facile solvothermal method using citric acid as a modulating agent and the growth process was revealed. The modulation of citric acid not only reduced the size of BiOCl nanosheets, finally transforming BiOCl microflowers into microspheres, but also induced the in situ reductive deposition of metallic Bi on the surface of the microspheres. Consequently, Bi@BiOCl microspheres showed larger specific surface areas and total pore volumes, higher absorptivity to the visible light and better charge transfer ability than BiOCl microflowers. As a result, Bi@BiOCl microspheres exhibited much better photocatalytic performance than BiOCl microflowers. Bi@BiOCl microspheres modulated by 2.8 g citric acid showed the highest photocatalytic activity, which was 4.4 and 2.5 times higher than BiOCl microflowers in degrading RhB under visible light and salicylic acid under UV light, respectively. This work may provide a new insight into simultaneous size control and in situ metal deposition for Bi-containing photocatalysts and other materials.
关键词： solvothermal method,Bi@BiOCl microspheres,photocatalytic performance,citric acid modulation,in situ reductive deposition
更新于2025-09-04 15:30:14
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Assignment of the Number of Equivalent Reference Fluorophores to Dyed Microspheres
摘要： A procedure will be described to assign to each dyed microsphere a number called the Equivalent number of Reference Fluorophores (ERF). The ERF unit gives the number of reference fluorophores in solution which produce the same fluorescence signal as a single dyed microsphere. In the first step, fluorescence measurements were carried out on serial dilutions of a solution of reference fluorophores. The resulting fluorescence intensities and the corresponding concentrations were used to calibrate the response of the fluorometer. The calibration consisted of establishing a linear relation between the intensities and concentrations. In the second step, the fluorescence intensity from a suspension of microspheres was measured in order to determine the equivalent concentration of reference fluorophores which gave the same fluorescence intensity as the suspension of microspheres. This was performed by utilizing the calibration line obtained in the first step. In the third step, a flow cytometer and a light obscuration apparatus were used to measure the total concentration of microspheres in the suspensions used for the fluorescence measurements. In addition to the total microsphere concentration, the flow cytometer also enabled the measurement of the concentration of a sub population of microspheres which are used to calibrate the fluorescence scale of a flow cytometer. The fourth step utilized the data collected in steps one, two, and three to assign a value of ERF to individual microspheres. The set of microspheres with assigned ERF values will be used to establish a linear fluorescence scale in each channel of a flow cytometer. The discussion will emphasize the estimate of uncertainties in each step of the assignment process.
关键词： fluorescence,concentration,calibration,ERF,microspheres,flow cytometer
更新于2025-09-04 15:30:14