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A novel disposable sensor based on gold digital versatile disc chip modified with graphene oxide decorated with Ag nanoparticles/β-cyclodextrin for voltammetric measurement of naproxen
摘要： A novel homemade disposable electrode made from gold digital versatile disc (G-DVD) and it was modified with graphene oxide decorated with Ag nanoparticles and β-cyclodextrin (AgNPs@GO-β-CD) for quantitative measurement of naproxen (NAP) in solution. Cyclic voltammetry and differential pulse voltammetry were used to evaluate the analytical response of the modified gold-DVD electrode to the NAP molecules. The nanohybrid which used in fabrication of the electrode, showed an excellent electrocatalytic activity towards oxidation of NAP. The calibration plot was linear within the concentration range of 0.4 μM to 80 μM of NAP molecules. The limits of detection and quantification were achieved as 0.023 μM (S/N = 3) and 0.08 μM (S/N = 10), respectively. Also, the RSDs were found to be 2.5% for 5 parallel experiments with the separate similar electrodes and 3.2% for 5 successive measurements with one electrode. The proposed electrochemical sensor, was successfully applied for measurement of NAP in real samples.
关键词： β-cyclodextrin,Gold disc,DVD,Ag nanoparticles,Naproxen,Graphene oxide
更新于2025-09-19 17:15:36
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A Simple and Rapid Method to Produce SERS Substrates Using Au Nanoparticles Prepared by Laser Ablation and DVD Template
摘要： Simple and highly sensitive SERS substrates were produced using Au nanoparticles (AuNPs) prepared by laser ablation in water and available Digital Video Discs (DVDs). We used the simple ‘‘drop-cast’’ method to deposit AuNPs on the grating pattern surface of a DVD in place of the other methods such as electrochemical deposition, electrophoretic deposition and sputtering method which require some more equipment. AuNPs were proposed to be synthesized in water by laser ablation to form a nearly circular AuNP stain of small size on a DVD surface. The protecting polycarbonate layer of a DVD was removed from the DVD surface. The bare metallic DVD surface was rinsed carefully with ethanol and distilled water. The width of tracks on a DVD surface is around 300 nm and distance between them is around 450 nm. We prepared AuNPs by pulsed laser ablation of a gold piece in distilled water. The colloidal gold nanoparticles were deposited on DVD templates. We studied to produce an effective layer of AuNPs on DVD template for SERS substrates (AuNPs/DVD). The average SERS enhancement factor of the AuNPs/DVD SERS substrates is about 106. The SERS substrates can detect SERS spectra of Malachite Green and Amoxicillin at low concentrations of around 0.1–1 ppm.
关键词： Surface enhanced Raman scattering (SERS),digital video disc (DVD),laser ablation
更新于2025-09-11 14:15:04
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Relative Roles of Luminance and Fixation in Inducing Dissociated Vertical Divergence
摘要： PURPOSE. We evaluated the roles of luminance and fixation in the pathophysiology of dissociated vertical divergence (DVD). METHODS. Vertical eye position was measured in 6 subjects with DVD (ages 11–47 years, 5 females) and 6 controls (ages 16–40 years, 5 females) using video-oculography (VOG) under conditions of change in fixation and luminance. RESULTS. Subjects with DVD showed the following VOG responses. When fixation was precluded with a translucent filter and bright light was shone into one eye to produce a marked binocular luminance disparity, we found some subjects had a small induced vertical divergence causing the illuminated eye to be lower than the nonilluminated eye (mean (cid:2)1.68 6 1.58, P ? 0.06 compared to no vertical divergence using the signed rank test). When fixation was precluded with a translucent filter, while alternate occlusion produced a mild binocular luminance disparity, we found a smaller vertical divergence of the eyes that was not statistically significant (1.28 6 2.18, P ? 0.3). When alternate occlusion produced reversal of monocular fixation in the dark (with essentially no change in peripheral luminance disparity), there was a significant vertical divergence movement causing the covered eye to be relatively higher than the uncovered eye (7.28 6 3.18, P ? 0.03). The amplitude of this vertical divergence was similar to that measured under conditions of alternate occlusion in a lighted room (where there also was a significant average relative upward movement of the covered eye of 8.18 6 2.98, P ? 0.03). Control subjects showed no vertical divergence under any testing conditions. CONCLUSIONS. Dissociated vertical divergence is mediated primarily by changes in fixation and only to a minor degree by binocular luminance disparity.
关键词： strabismus,videooculography,dissociated vertical divergence,DVD
更新于2025-09-04 15:30:14
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DVD Review
摘要： This DVD course, “Basic Concepts in NMR”, is exactly what the title claims – a very thorough and detailed description of the underlying “concepts” that one needs to know to fully understand one-dimensional NMR experiments. Since I have been an industrial NMR spectroscopist training scientists to do NMR for over 40 years, I have a full appreciation for the amount of time this course would have saved me. The course explores the basic theory behind NMR experiments and even explains the components of the hardware necessary to obtain NMR data. The author’s presentations show the result of decades of teaching this topic. He presents each concept clearly and at a pace that allows the student to think about what the lessons mean. He frequently relates abstract principles to more easily understood physical observations such as his use of a common spring to illustrate the rate of return to equilibrium of excited nuclei during the relaxation process.
关键词： spectroscopy,DVD course,NMR,basic concepts
更新于2025-09-04 15:30:14