- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fabrication of Uniform Gold Nanopatterns on Graphene by Using Nanosphere Lithography
摘要： In this study, we have realized controllable fabrication of gold nanopatterns on pristine monolayer graphene by using nanosphere lithography, in which polystyrene (PS) spheres are used as templates. With this method, periodically ordered triangular Au nanopatterns are uniformly formed on graphene surface. Micro-Raman spectroscopy shows that these sacrificial PS templates have no obvious effect on graphene surface structure while the subsequently formed Au nanopatterns are found to enhance Raman intensity of G and 2D bands by surface plasmon resonance. The compressive stress introduced in the metal deposition process leads to an obvious blue shift of 2D band. Besides, the metal-induced doping effect reduces the intensity ratio between 2D and G bands. This uniform arrangement of metal nanostructure is expected to grow other nanomaterials or used as Raman enhancement substrate in biomedicine, catalyzer and optics areas.
关键词： Gold Nanopatterns,Nanosphere Lithography,Graphene,Raman Spectroscopy
更新于2025-09-04 15:30:14
-
Coherent Anti-Stokes Raman Spectroscopy of a Hydrogen Diffusion Flame in a Ramjet
摘要： Dual-pump coherent anti-Stokes Raman spectroscopy (CARS) was used to measure the mole fractions of major species as well as the rotational and vibrational temperatures of molecular nitrogen in a hydrogen-fueled dual-mode scramjet flowpath operated in the “ram” mode. Developments in CARS methods and uncertainties are described, including a detailed analysis of the effects of spatial averaging. The mean and standard deviation of the turbulent fluctuations of the temperature and mole fractions at multiple planes in the flowpath and scatter plots of vibrational and rotational temperature are presented. The flame is stabilized downstream of the ramp and grows under the influence of turbulence and rollup of the counterrotating vortex pair formed at the ramp; combustion continues in accelerating flow approaching the end of the measurement domain. Thermal nonequilibrium is observed in the mixing of air with the molecular hydrogen jet close to the injector. Spatial averaging errors are significant at some locations; new methods to correct these errors are described.
关键词： Coherent Anti-Stokes Raman Spectroscopy,CARS,thermal nonequilibrium,hydrogen diffusion flame,supersonic combustion,spatial averaging,ramjet
更新于2025-09-04 15:30:14
-
Adaptive filtering of physiological noises in fNIRS data
摘要： The study presents a recursive least?squares estimation method with an exponential forgetting factor for noise removal in functional near?infrared spectroscopy data and extraction of hemodynamic responses (HRs) from the measured data. The HR is modeled as a linear regression form in which the expected HR, the first and second derivatives of the expected HR, a short?separation measurement data, three physiological noises, and the baseline drift are included as components in the regression vector. The proposed method is applied to left?motor?cortex experiments on the right thumb and little finger movements in five healthy male participants. The algorithm is evaluated with respect to its performance improvement in terms of contrast?to?noise ratio in comparison with Kalman filter, low?pass filtering, and independent component method. The experimental results show that the proposed model achieves reductions of 77% and 99% in terms of the number of channels exhibiting higher contrast?to?noise ratios in oxy?hemoglobin and deoxy?hemoglobin, respectively. The approach is robust in obtaining consistent HR data. The proposed method is applied for both offline and online noise removal.
关键词： State space model,Hemodynamic response (HR),Exponential forgetting,Recursive least squares estimation (RLSE),Real time estimation,Functional near?infrared spectroscopy (fNIRS)
更新于2025-09-04 15:30:14
-
In Vivo Spectroscopy vis-à-vis Ex Vivo Spectroscopy: Pearls and Pitfalls: Imaging Review
摘要： Aims and objective: The objective of this communication is to bring the metabolomics by magnetic resonance (high resolution spectroscopy) to the clinical radiologist and compare the spectroscopy in vivo (NMR spectroscopy used in clinical) with the high resolution spectroscopy ex vivo (magic angle spectroscopy, HR –MORE). S and analyzing differences, advantages and limitations of each technique in different tissues. Review of the topic: In vivo spectroscopy that is usually performed in the clinic is a non-invasive technique that can provide important information for the diagnosis and monitoring of different lesions. The most well-known applications of in vivo spectroscopy today are those carried out by localized 1H spectroscopy, monovoxel or multivoxel (spectroscopic image), brain, prostate or breast. There are other modalities, such as the 31 P or 13oC spectroscopy, but they are much less frequent and are only carried out in a few specialized centres. Without any doubt, the most widespread clinical use is confined to the central nervous system. Conclusion: The in vivo spectroscopy provides important metabolic information for the diagnosis of different pathologies, non-invasively, however, this technique has certain limitations, such as low spectral resolution, that is, the number of metabolites that can be identified/quantified; which results in low diagnostic specificity. Ex vivo spectroscopy, however, has a spectral resolution and sensitivity far superior to in vivo techniques, which allows detecting a large number of metabolites, and therefore greatly improves its diagnostic capacity. However, we must not forget that it is an invasive technique, since it is based on the analysis of pieces of tissue (biopsies, surgical pieces...) and therefore loses its usefulness in those lesions that are impossible to biopsy. In conclusion, each technique has its added value and its limitations and it is the correct use of them and the combination of them with other diagnostic parameters, where their clinical potential resides.
关键词： Prostate,Cerebral,Imaging,Diagnosis,Spectroscopy,Peak
更新于2025-09-04 15:30:14
-
The role of near-infrared spectroscopy in the detection of vulnerable atherosclerotic plaques
摘要： Coronary artery disease is the leading cause of mortality worldwide. Most acute coronary syndromes are caused by a rupture of a vulnerable atherosclerotic plaque which can be characterized by a lipid-rich necrotic core with an overlying thin fibrous cap. Many vulnerable plaques can cause angiographically mild stenoses due to positive remodelling, which is why the extent of coronary artery disease may be seriously underestimated. In recent years, we have witnessed a paradigm shift in interventional cardiology. We no longer focus solely on the degree of stenosis; rather, we seek to determine the true extent of atherosclerotic disease. We seek to identify high-risk plaques for improvement in risk stratification of patients and prevention. Several imaging methods have been developed for this purpose. Intracoronary near-infrared spectroscopy is one of the most promising. Here, we discuss the possible applications of this diagnostic method and provide a comprehensive overview of the current knowledge.
关键词： vulnerable plaque,near-infrared spectroscopy,lipid-core plaque
更新于2025-09-04 15:30:14
-
Relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists for display manufacture, studied by real-time Fourier transform infrared spectroscopy and quartz crystal microbalance methods
摘要： Photoresists are an indispensable technology used for manufacturing electronic devices such as displays and semiconductors. In this study, we investigated the relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists used for display manufacture using real-time Fourier transform infrared spectroscopy (FTIR) and quartz crystal microbalance (QCM) methods. To improve photoresist performance, it is important to understand the development mechanism of photoresists. Two kinds of polymers (a polymer with peeling-type dissolution and a polymer with a dissolution type with Case II diffusion) were used. 1,2-Octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide were used as photoinitiators. The dissolution was of the peeling type when the polymers were formulated as a typical cross-linking-type photoresist. With increasing conversion ratio of C=C double bonds, the rate of developer intake decreased and the impregnation threshold before the onset of peeling increased and then decreased. It was also found that the dissolution kinetics were affected by the radicals generated upon the decomposition of photoinitiators.
关键词： C=C double bond conversion,dissolution kinetics,quartz crystal microbalance,Photoresists,real-time Fourier transform infrared spectroscopy
更新于2025-09-04 15:30:14
-
Spectral analysis of the <scp>EBT</scp> 3 radiochromic films for clinical photon and electron beams
摘要： Purpose: To investigate the spectral response of the EBT3 radiochromic films to different beam qualities for radiation therapy dosimetry. Dose, dose rate, and inter-batch dependencies on the spectral response of the films are investigated as well. Methods: Pieces of EBT3 films placed between layers of solid water phantoms were irradiated with 6 and 15 MV photon beams, 6 and 10 MV-FFF photon beams, and 6 and 20 MeV electron beams at dose levels between 0.4-50 Gy. Net absorbance was measured as a function of wavelength from the spectra acquired in the wavelength range of 400-800 nm using a fiber-coupled spectrometer and broadband light source. Results: No significant change was observed in the absorption spectra of the EBT3 films irradiated with the same amount of dose using different beam qualities. Also, no spectral change with dose rate was observed. The measured net absorbance per Gy was independent of beam quality in the 1-50 Gy dose range. Slight differences in the spectral shape and absorption band positions were observed in film samples from different batches. The net absorbance spectra showed two absorption bands centered around 634-636 nm (primary) and 583-585 nm (secondary). However, depending on the film batch, for doses above a certain level the primary absorption band appears to “split” into two bands centered around ~624-628 and ~641-645 nm. Conclusions: The spectral shape of the EBT3 radiochromic films irradiated with photons (including FFF) and electron beams is beam quality and dose rate independent; however it varies with dose level, batch, and spectroscopy system used.
关键词： EBT3,film dosimetry,Radiochromic film,absorption spectroscopy
更新于2025-09-04 15:30:14
-
The effects of lumbar sympathectomy on bone and soft tissue haemodynamics of the leg recorded using near infrared spectroscopy: A case report
摘要： Near infrared spectroscopy (NIRS) is an established tool for the measurement of microvascular haemodynamics in different tissue types. This case report outlines the novel use of NIRS for measuring total oxygenation index (TOI) and relative oxygenated and deoxygenated haemoglobin concentration changes as markers of oxygenation and blood volume in muscle and bone tissue. In particular, NIRS is used to examine differences between the left and right leg in a participant who has experienced a permanent unilateral lumbar sympathectomy following an anterior lumbar intervertebral fusion. Anatomical sites at the lateral head of the gastrocnemius, tibial diaphysis and proximal tibia were investigated with NIRS during an arterial occlusion protocol at the distal femur. Consistent differences were observed between the sympathectomised left leg and the normal right leg. These included reduced baseline TOI, reduced deoxygenation rates during occlusion, and reduced reoxygenation rates post occlusion release in the sympathectomised leg at all anatomical sites. This case report demonstrates the potential of NIRS as a research tool for investigating the microvascular effects of lumbar sympathectomy. This may be useful for further investigation into the merit of chemical lumbar sympathectomy for the treatment of a variety of conditions, including hyperhidrosis and peripheral vascular disease.
关键词： Sympathectomy,Near infrared spectroscopy,Total oxygenation index,Muscle,Bone
更新于2025-09-04 15:30:14
-
Raman Spectroscopy and Applications || Raman Mapping: Emerging Applications
摘要： Raman mapping is a noninvasive, label‐free technique with high chemical specificity and high potential to become a leading method in biological and biomedical applications. As opposed to Raman spectroscopy, which provides discrete chemical information at distinct positions within the sample, Raman mapping provides chemical information coupled with spatial information. The laser spot scans the investigated sample area with a preset step size and acquires Raman spectra pixel by pixel. The Raman spectra are then discriminated from each other by chemometric analysis, and the end result is a false color map, an image of the sample that contains highly precise structural and chemical information. Raman imaging has been successfully used for label‐free investigations at cellular and subcellular level. Cell compartments, cell responses to drugs and different stages of the cell cycle from the stem cell to the completely differentiated cell were successfully distinguished. This technique is also able to differentiate between healthy and cancer cells, indicating great potential for replacing conventional cancer detection tools with Raman detection in the future.
关键词： plants,algae,cells,medical diagnosis,tissues,Raman imaging,Raman mapping,Raman spectroscopy
更新于2025-09-04 15:30:14
-
Plasmon confinement by carrier density modulation in graphene
摘要： We investigate plasmon resonances in graphene with periodic carrier density modulation. The period is 8 μm, and each period consists of 1.7- and 6.3-μm-wide ribbons with di?erent density. Using terahertz spectroscopy, we show two plasmon modes with their electric ?eld mostly localized in the 1.7- or 6.3-μm-wide ribbon arrays. We also show that plasmons are excited only in one of the micro-ribbon arrays when the Fermi energy of the other micro-ribbon array is set close to the charge neutrality point. These results indicate that plasmons can be con?ned by the carrier density modulation. ? 2018 The Japan Society of Applied Physics
关键词： carrier density modulation,plasmon resonances,graphene,terahertz spectroscopy
更新于2025-09-04 15:30:14