During photosynthesis, sunlight is efficiently captured by light-harvesting complexes, and the excitation energy is then funneled towards the reaction centre. These photosynthetic excitation energy transfer (EET) pathways are complex and proceed in a multistep fashion. Ultrafast two-dimensional electronic spectroscopy (2DES) is an important tool to study EET processes in photosynthetic complexes. However, the multistep EET processes can only be indirectly inferred by correlating different cross peaks from a series of 2DES spectra. Here we directly observe multistep EET processes in LHCII using ultrafast fifth-order three-dimensional electronic spectroscopy (3DES). We measure cross peaks in 3DES spectra of LHCII that directly indicate energy transfer from excitons in the chlorophyll b (Chl b) manifold to the low-energy level chlorophyll a (Chl a) via mid-level Chl a energy states. This new spectroscopic technique allows scientists to move a step towards mapping the complete complex EET processes ...
TY - JOUR. T1 - Two dimensional electronic spectroscopy of molecular complexes. AU - Cho, Minhaeng. AU - Brixner, Tobias. AU - Stiopkin, Igor. AU - Vaswani, Harsha. AU - Fleming, Graham R.. PY - 2006/2. Y1 - 2006/2. N2 - Two dimensional (2D) heterodyne-detected electronic photon echo spectroscopy is introduced and described. We give an intuitive description of the origin and information content of 2D electronic spectra, focusing on molecular complexes. We identify two important quantities-the transition dipole term, and the transition frequency cross correlation function that controls the appearance of 2D electronic spectra. We also show how the transition frequency cross correlation function controls the rate of exciton relaxation. These concepts are illustrated with experimental data on the seven bacteriochlorophyll FMO complex of a green sulfur bacterium, showing how the pathways and mechanisms of energy flow can be elucidated by combining 2D spectra with theoretical modeling.. AB - Two ...
The study of the photosynthetic processes has always had a particular relevance in spectroscopy because of its possible applications in light harvesting and energy storage. Since the light-harvesting pigment-protein complexes have this functional role in nature, many of studies have been focused on understanding photophysical processes occurring in these systems. Our work aims to study the spectroscopic properties of the best known pigment involved in the photosynthesis, Chlorophyll a, and their changes with different solvents. The study of the pigment was conducted by linear spectroscopic studies for water-solvent mixtures, while by the nonlinear technique 2D spectroscopy was applied for pure solvent. The theory and technique of 2D spectroscopy is described. The properties of solvents strongly influence the environment felt by the molecule and its capability of aggregate formation. The solvent properties that were found to be most relevant for our study were viscosity, H-bonding formation and ...
The |i|Journal of Biomedical Optics|/i| (JBO) publishes peer-reviewed papers on the use of novel optical systems and techniques for improved health care and biomedical research.
Apoptosis, ldquoprogrammed cell death,rdquo is a cellular process exhibiting distinct biochemical and morphological changes. There is much interest regardi
TY - JOUR. T1 - Electronic spectroscopy of intermediates involved in the conversion of methane to methanol by FeO+. AU - Aguirre, Fernando. AU - Husband, John. AU - Thompson, Christopher J.. AU - Stringer, Kay L.. AU - Metz, Ricardo B.. PY - 2002/3/8. Y1 - 2002/3/8. N2 - The reaction intermediates [H2C=Fe-OH2]+ and [HO-Fe-CH3]+ by photodissociation were studied. On the basis of experimental results and calculations performed at the B3LYP and TD3LYP level, excited state vibrational frequencies as well as geometry changes upon photoexcitation in [H2C=Fe-OH2]+ and [HO-Fe-CH3]+ were determined.. AB - The reaction intermediates [H2C=Fe-OH2]+ and [HO-Fe-CH3]+ by photodissociation were studied. On the basis of experimental results and calculations performed at the B3LYP and TD3LYP level, excited state vibrational frequencies as well as geometry changes upon photoexcitation in [H2C=Fe-OH2]+ and [HO-Fe-CH3]+ were determined.. UR - ...
Fleming has compared 2-D electronic spectroscopy to the technique used in the early super-heterodyne radios, where an incoming high frequency radio signal was converted by an oscillator to a lower frequency for more controllable amplification and better reception. In the case of 2-D electronic spectroscopy, scientists can track the transfer of energy between molecules that are coupled (connected) through their electronic and vibrational states in any photoactive system, macromolecular assembly or nanostructure.. Fleming and his group first described 2-D electronic spectroscopy in a 2005 Nature paper, when they used the technique to observe electronic couplings in the Fenna-Matthews-Olson (FMO) photosynthetic light-harvesting protein, a molecular complex in green sulphur bacteria. Said Engel, The 2005 paper was the first biological application of this technique, now we have used 2-D electronic spectroscopy to discover a new phenomenon in photosynthetic systems. While the possibility that ...
Virus diseases are of high concern in the cultivation of seed potatoes. Once found inthe field, virus diseased plants lead to declassification or even rejection of the seed lotsresulting in a financial loss. Farmers put in a lot of effort to detect diseased plants andremove virus-diseased plants from the field. Nevertheless, dependent on the cultivar,virus diseased plants can be missed during visual observations in particular in an earlystage of cultivation. Therefore, there is a need for fast and objective disease detection.Early detection of diseased plants with modern vision techniques can significantlyreduce costs. Laboratory experiments in previous years showed that hyperspectral imaging clearly could distinguish healthy from virus infected potato plants. This paper reports on our first real field experiment. A new imaging setup was designed, consisting of a hyperspectral line-scan camera. Hyperspectral images were taken in the field with a line interval of 5 mm. A fully convolutional ...
Target detection of hyperspectral image (HSI) is a research hotspot in the field of remote sensing. It is of particular importance in many domains, especially in military application. Unsupervised target detection is usually more difficult because there is no prior information about target. Traditional algorithms exploit spectral information, only. This study introduces the idea of saliency detection from the visual technique into HSI processing domain and proposes a novel approach named spectral saliency target detection (SSD). It establishes a novel salient model, which utilises both spatial saliency and spectral saliency. In the framework of SSD, it combines the model with spectral matching algorithm to make it perform well even in situations where the target is concealed and small. A HSI set comprised of eight different scenes with complex background is setup to evaluate the performance of the proposed algorithm. The final visible detection results demonstrate that the SSD algorithm ...
Deep learning techniques have boosted the performance of hyperspectral image (HSI) classification. In particular, convolutional neural networks (CNNs) have shown superior performance to that of the conventional machine learning algorithms. Recently, a novel type of neural networks called capsule networks (CapsNets) was presented to improve the most advanced CNNs. In this paper, we present a modified two-layer CapsNet with limited training samples for HSI classification, which is inspired by the comparability and simplicity of the shallower deep learning models. The presented CapsNet is trained using two real HSI datasets, i.e., the PaviaU (PU) and SalinasA datasets, representing complex and simple datasets, respectively, and which are used to investigate the robustness or representation of every model or classifier. In addition, a comparable paradigm of network architecture design has been proposed for the comparison of CNN and CapsNet. Experiments demonstrate that CapsNet shows better accuracy and
CiteSeerX - Scientific articles matching the query: A Novel Analysis Dictionary Learning Model Based Hyperspectral Image Classification Method
Hyperspectral imaging is emerging as a promising approach for plant disease identification. The large and possibly redundant information contained in hyperspectral data cubes makes deep learning based identification of plant diseases a natural fit. Here, we deploy a novel 3D deep convolutional neural network (DCNN) that directly assimilates the hyperspectral data. Furthermore, we interrogate the learnt model to produce physiologically meaningful explanations. We focus on an economically important disease, charcoal rot, which is a soil borne fungal disease that affects the yield of soybean crops worldwide. Based on hyperspectral imaging of inoculated and mock-inoculated stem images, our 3D DCNN has a classification accuracy of 95.73% and an infected class F1 score of 0.87. Using the concept of a saliency map, we visualize the most sensitive pixel locations, and show that the spatial regions with visible disease symptoms are overwhelmingly chosen by the model for classification. We also find that the most
The non-resonant dynamic Stark effect is a powerful and general way of manipulating ultrafast processes in atoms, molecules, and solids with exquisite precision. We discuss the physics behind this effect, and demonstrate its efficacy as a method of control in a variety of systems. These applications range fr Coherence and Control in Chemistry
We measure several fundamental electronic properties of molecules such as charge transfer and electronic delocalization using a technique known as Stark spectroscopy. Stark spectroscopy involves applying large electric fields to molecules in films or matrices and analyzing the effects of the field perturbation on the absorption or emission spectrum. We have recently focused on the properties of MEH-PPV and other molecules used to make to organic light emitting diodes (OLEDs). Stark spectroscopy reveals the mechanism by which a large applied electric field, such as those present in OLEDs, produces undesirable emission quenching and suggests strategies for minimizing this loss of device efficiency through modifications of the polymer structure.. Emission properties of Single Molecules and Aggregates. Recent years has seen a huge growth in the use of organic conjugated oligomers and polymers in the design of light emitting diodes (OLEDs) and photovoltaic cells. When these molecules are placed in ...
Application Note: Kinetics of Photocatalysis Reactions Studied by Transient Absorption Spectroscopy. Read and Download our Application Note.
1. Physical principles of optical spectroscopy and ellipsometry - Electron transitions and the origin of the spectral dependences of the optical parameters - Modeling of dielectric function of materials - Kramers-Kronig dispersion relation, the relation of absorption and dispersion - Spectral device (dispersive prism, grating, Fabry-Perot interferometer) - Selected parts of optical thin films - Methods of effective environments and their use in optical spectroscopy 2. REFLECTION AND TRANSMISSION spectroscopy in the visible, near-ultraviolet A near-infrared - Components of spectrometers, the two-spectrometer - Materials used in optical spectroscopy - Resolution limit and instrumentation functions monochromator - Superstructure instruments for measuring reflection spectra, integrating sphere 3. Spectroscopic ellipsometry - Methods of ellipsometry, the ellipsometric measurement angles psi and delta, generalized ellipsometry - Type ellipsometer (zero ellipsometry, polarization modulation, rotating ...
There are loads of situations when spectrum analysis can be helpful during mixdown, but there are a few things to bear in mind if you want to take full advantage of it. The first thing is that the analysers bundled with most DAW systems arent high-resolution enough, so check out some of the much better third-party options. Voxengos SPAN is a good piece of cross-platform freeware, for example, although I tend to use Schwas affordable payware Schope myself.. The first big analysis application at mixdown highlights overall mix-tonality imbalances that your monitoring hasnt alerted you to. Although this is clearly relevant to budget setups with budget monitors and uncontrolled acoustics, even pros like Joe Chiccarelli and Eric Rosse talk about using spectrum analysis in this way. However, every spectrum analyser seems to display things in a different way, so you need to get to know how your favourite records look on screen before you can come to any meaningful conclusions about your own work. A ...
The spectrum pane is similar to the one you can see in Chanalyzer, a spectrum analysis application by MetaGeek that comes with Wi-Spy. By default, the Channels and Spectrum pane displays one or two planar spectrum graphs for single- and dual-band Wi-Spy models, respectively. The appearance of the graphs can be controlled via the context menu. Select 2.4 GHz, 5.0 GHz, or Dual to have the spectrum pane display one of the single frequency bands or two bands simultaneously (5.0 GHz and Dual are available only if you have a dual-band Wi-Spy model.) Select Current Level to display a line that shows the current signal amplitude; select Max Level to display a line that shows the maximum signal amplitude. The X-axis item allows you to select the measurement units of the horizontal axis; you can choose between Frequency in MHz and Channel numbers. By enabling the Waterfall view, you can have the application graph amplitude over time. Select 1/3, 1/2, or 2/3 of the window size to adjust the area of the ...
but the nature of this approximation is typically determined by characteristics of audio perception. Best results are usually obtained by formulating this as an FIR filter design problem (see Chapter 4). In general, both time-domain and frequency-domain specifications are needed. (Recall the potentially problematic impulses in the Dolph-Chebyshev window shown in Fig.3.33 when its length was long and ripple level was high). Equivalently, both magnitude and phase specifications are necessary in the frequency domain. A window transform can generally be regarded as the frequency response of a lowpass filter having a stop band corresponding to the side lobes and a pass band corresponding to the main lobe (or central section of the main lobe). Optimal lowpass filters require a transition region from the pass band to the stop band. For spectrum analysis windows, it is natural to define the entire main lobe as transition region. That is, the pass-band width is zero. Alternatively, the pass-band ...
I need to measure frequency of a low level signal in the range 300kHz to 500kHz with the frquency either displayed numerically or available to process in an automated PC test setup to give a pass/fail result. Currently I use an expensive hardware spectrum analyser with a human interpreter. The spectrum analysis software available for the picoscopes looks very basic and appears to always run from zero up to the maximum selected frequency. Question 1: can the frequency axis be displayed with user selectable start and stop frequencies like a normal hardware analyser? Question 2: Are there marker peak-find functions available with live readout or data-out that can be used in PC ATE ...
This thesis presents the non-invasive use of diffuse reflectance spectroscopy (DRS) to provide information about the biochemical composition of living tissue. During DRS measurements, the incident, visible light is partially absorbed by chromophores but also scattered in the tissue before being remitted.. Human skin and heart, the main tissue objects in this thesis, are dependent on a sufficient inflow of oxygenized blood, and outflow of metabolic byproducts. This process could be monitored by DRS using the spectral fingerprints of the most important tissue chromophores, oxyhemoglobin and deoxyhemoglobin.. The Beer-Lambert law was used to produce models for the DRS and has thus been a foundation for the analyses throughout this work. Decomposition into the different chromophores was performed using least square fitting and tabulated data for chromophore absorptivity.. These techniques were used to study skin tissue erythema induced by a provocation of an applied heat load on EMLA-treated skin. ...
I tried using a Sound Blaster Z PCIe card in conjunction with spectrum analysis software but the results were dissapointing. The SB Z appears to add a fair amount of distortion (mainly second harmonic) to signals feeding the line input. I then tried an old SB Audigy 2 PCI card in another PC. The results were much better. Does anyone know why this should be? My own theory is that the SB Z shares a single input jack for line input and mic input. That must mean there is some variable gain
Mohammadi, SM, Enshaeifar, S, Ghavami, M and Sanei, S (2015) Classification of Awake, REM, and NREM from EEG via Singular Spectrum Analysis In: 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015-08-25 - 2015-08-29, Milan, ITALY. Full text not available from this repository ...
A method and device for detecting dichroic and/or birefringent narrow spectral features in a sample is described. The method includes the steps of providing a beam of light having an optical frequency bandwidth which is narrow compared to the width of the narrow spectral feature and having a center frequency ωc which lies near the narrow spectral feature, polarization phase modulating a beam of light with a single RF frequency to provide a pure FM spectrum having upper and lower sidebands in which either the carrier and sidebands have been polarized with respect to one another, exposing the sample containing the narrow spectral feature to the polarized modulated light so that the FM sidebands probe the narrow spectral feature, polarization analyzing and then photodetecting the light emerging from the sample to detect a RF beat at the specific RF frequency used for the polarization phase modulation, and electronically monitoring the amplitude of the RF beat signal to indicate the strength of the narrow
If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library, or send a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. ...
Matteoli, S., E.J. Ientilucci, J.P. Kerekes. Operational and performance considerations of radiative transfer modeling in hyperspectral target detection. IEEE Transactions on Geoscience and Remote Sensing, (2010): 1-13. Print. £. Stefanou, M.S., J.P. Kerekes. Image-Derived Prediction of Spectral Image Utility for Target Detection Applications. IEEE Transactions on Geoscience and Remote Sensing, 48.5 (2010): 1827-1833. Print. † £. King, K.C., J.P. Kerekes. Development of a Web-based Blind Test to Score and Rank Hyperspectral Classification Algorithms. Proceedings of the 2010 Western NY Image Processing Workshop, IEEE, Nov. 2010. n.p. Print. † £. Lu, Z., A.C. Rice, J.R. Vasquez, J.P. Kerekes. Target Discrimination Via Optimal Wavelength Band Selection With Synthetic Hyperspectral Imagery. Proceedings of the Second Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing, IEEE, June 2010. n.p. Print. £. Presnar, M.D., J.P. Kerekes, D.R. Pogorzala. Dynamic ...
We explore the use of Monte-Carlo-model-based methods for the analysis of fluorescence and diffuse reflectance spectra measured from breast cells. the difference in model selection by individual researchers, and this was the only difference in the model 1572414-83-5 supplier parameters for fitted the diffuse reflectance spectra of units 1 and 2 and arranged 3. However, the absorption due to NADH only was found to account for only 0 to 3% normally of the total absorption across the wavelength range of 350 to 600 nm, having a imply of 0.4% and a standard deviation of 2%. This indicated that NADH did not contribute significantly to the absorption with this wavelength range, and the absorption and scattering properties from the three units of cells spectra are still similar. The absorption properties yielded from your model and used in further data analysis then include represents the contribution and then represents the fractional fluorescence contribution from an individual component to that ...
Planned hyperspectral satellite missions and the decreased revisit time of multispectral imaging offer the potential for data fusion to leverage both the spectral resolution of hyperspectral sensors and the temporal resolution of multispectral constellations. Hyperspectral imagery can also be used to better understand fundamental properties of multispectral data. In this analysis, we use five flight lines from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) archive with coincident Landsat 8 acquisitions over a spectrally diverse region of California to address the following questions: (1) How much of the spectral dimensionality of hyperspectral data is captured in multispectral data?; (2) Is the characteristic pyramidal structure of the multispectral feature space also present in the low order dimensions of the hyperspectral feature space at comparable spatial scales?; (3) How much variability in rock and soil substrate endmembers (EMs) present in hyperspectral data is captured by ...
The book Modern Optical Spectroscopy: With Examples from Biophysics and Biochemistry explains the theory of optical spectroscopic phenomena and demons
Hyperspectral imaging (HSI) provides images with numerous spectral bands over a continuous spectral range, enabling analysis of complex scenes that co
The primary objective of this pilot study is to calculate the sensitivity and specificity for discriminating tumor and benign tissues in vivo in colorectal cancer patients based on optical spectroscopy measurements. The secondary objective of this study is to calculate the spectral differences between in vivo and ex vivo measurements and the difference in the biological parameters (i.e. blood, water and fat content and blood oxygenation) that are extracted from the spectral information ...
A guided-mode resonance (GMR) filter with the same material (Ta2O5) for both the grating layer and the waveguide layer is designed and fabricated. This simple structure is easy to fabricate and can avoid the defects at the grating/waveguide interface using different materials. The spectral response measured with a Lambda 900 spectrophotometer under normal incidence for TE waves exhibits a peak reflectance exceeding 80% at the wavelength of 1040 nm with a full-width half-maximum (FWHM) linewidth of 23 nm. We evaluate the deviations of the fabricated structure from the designed parameters.. © 2010 Chinese Optics Letters. PDF Article ...
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-9892.2012.00820.x In this paper, we propose a new methodology for selecting the window length in Singular Spectral Analysis in which the window length is determined from the data prior to the commencement of modelling. The selection procedure is based on statistical tests designed to test the convergence of the autocovariance function. A classical time series…
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies. ...
Watch this video demonstration on how to use a spectrum analyzer, general RF spectrum analysis, and RF / EMC spectrum analyzer operations.
Learn the fundamentals of real-time spectrum analysis and how you can extend the performance of your PXI vector signal analyzer with high-throughput processing from the LabVIEW FPGA Module.
This document describes several approaches to implementing wideband spectrum analysis using the NI USRP™ (Universal Software Radio Peripheral) platform. After addressing how to acq...
Hyperspectral imaging (HSI) is a technique that analyzes a wide spectrum of light coming into a camera. Instead of assigning individual pixels to primary c
Is there such a beast? I just did a spectrum analysis of two of my reference tracks, and they both had a frequency cut off at about 17khz. I dont...
The APS frame definition allows for a variable number of spectrometer pixels (also called channels) to be included in the frame. The two pixel values are configured indirectly via the wavelength range of the spectrum to be output ...
Develop a broad, flexible level of knowledge of city and regional or town and country planning with our MSc Spatial Planning. Accredited by RTPI and RICS.

A means for intracavity sum frequency generation is described in which a er operates simultaneously, cw, at two wavelengths where the net gain at one wavelength is substantially lower than that at the other. The optical alignment of the resonator provides a region where both fundamental wavelengths are overlapped, and another region where both feedback paths are spatially distinct. An active feedback mirror is located in the path of the lower net gain laser transition to provide optical amplification at that wavelength. The laser resonator further contains a sum frequency generating crystal for intracavity sum frequency generation of the two fundamental wavelengths. The sum frequency generating crystal is placed near a laser resonator cavity mode waist in the region where both wavelengths are spatially superimposed, producing the sum frequency of the two wavelengths. An intracavity polarization rotator provides the appropriate orientation of the polarization of the two fundamental wavelengths in the
Surface-enhanced IR-visible sum frequency generation (SFG) was studied using Ag and Au films over nanospheres (AgFON and AuFON), which provided large area of reproducible nanoscale structures with well-defined morphology. SFG vibrational spectra for a self-assembled monolayer of octadecanethiol were investigated on spheres with diameters ranging from 300 nm to 620 nm. With an input wavelength of 532 nm, a sphere diameter near 360 nm produced the maximum enhancement, which was consistent with the localized surface-plasmon resonant wavelength identified by minimum reflectivity. The measured second-order susceptibility for the asymmetric CH3 stretch mode of octadecanethiol was enhanced by up to 27 times on AgFON, which corresponded to an SFG enhancement factor of similar to 730. The SFG enhancement factor for AuFON was a quarter of that from AgFON. The SFG enhancement factor for the symmetric CH3 mode was about 10 times smaller than that for the asymmetric CH3 mode. This difference can be explained ...
Dielectric spectroscopy (DS) of living biological cells is based on the analysis of the complex dielectric permittivity of cells suspended in a physiological medium. It provides knowledge on the polarization-relaxation response of cells to external electric field as function of the excitation frequency. This response is strongly affected by both structural and molecular properties of cells and therefore, can reveal rare insights on cell physiology and behaviour. This study demonstrates the mapping potential of DS after cytoplasmatic and membranal markers for cell-based screening analysis. The effect of membrane permittivity and cytoplasm conductivity was examined using tagged MBA and MDCK cell lines respectively. Comparing the permittivity spectra of tagged and native cell lines reveals clear differences between the analyzed suspensions. In addition, differences on the matching dielectric properties of cells were obtained. Those findings support the high distinction resolution and sensitivity of DS
The diffractive features of angular distribution have been investigated by analyzing the experimental data for a set of elastic scattering processes of {sup 7}Li by different target nuclei at different laboratory energies. Both Frahn-Venter and McIntyre models are used to analyze experimental data of angular distribution for elastic scattering processes. The theoretical models can reasonably reproduce the general pattern of the data. Some geometrical parameters for colliding nuclei have been obtained from the elastic scattering processes. It is found that interpretation of the diffractive features of the data is model-independent. The values of extracted parameters, from adopted models, are found comparable to each other and to those of others. The total reaction cross section is correlated to the incident laboratory energy for each scattering and values of total reaction cross section are found comparable with those of others. ...
Due to the broad biological significance of the correlation between phospholipid membrane structure and function, there is a great need for powerful tools to probe the distribution, kinetics, orientation and conformation of lipid and protein membrane constituents. Sum Frequency Spectroscopy (SFS) can simultaneously elucidate the absolute orientation and the detailed degree of conformational order of the alkyl chains of lipids comprising a membrane. To date, SFS studies of membrane structures have been performed on model membranes formed directly on solid substrates, at the oil/ solution interface, and at the air/ water interface. Such systems are not amenable to studies of membrane transport processes or incorporation of transmembrane proteins with intracellular domains. Thus, a model membrane system replicating, in a controlled manner, the cross-section of a biological membrane is being developed by building upon knowledge regarding cushioned model membranes and utilizing a detailed ...
Plant Analysis by Laser Induced Breakdown Spectroscopy (LIBS) - Agriculture - Agriculture Monitoring and Testing by Applied Spectra, Inc.. Laser-induced breakdown spectroscopy (LIBS) offers the ability to analyze plant samples with little to no sampl...
TY - JOUR. T1 - Determination of potassium in ceramic raw materials using laser-induced breakdown spectroscopy combined with profile fitting. AU - Tang, Yun. AU - Guo, Lianbo. AU - Tang, Shisong. AU - Chu, Yanwu. AU - Zeng, Qingdong. AU - Zeng, Xiaoyan. AU - Duan, Jun. AU - Lu, Yongfeng. PY - 2018/8/1. Y1 - 2018/8/1. N2 - The determination of potassium (K) content in ceramic raw materials provides important references for ceramic sintering. To realize rapid, in situ, and real-time analysis detection, a laser-induced breakdown spectroscopy (LIBS) system was set up to analyze K content in ceramic raw materials. However, the self-absorption was the serious influence on the accuracy of K element analysis. In this work, a method of profile fitting with Lorentz function was proposed to reduce the self-absorption effect in LIBS. After Lorentz fitting, the determination coefficient (R2 factor) for K element improved from 0.993 to 0.998, the root mean square error of cross-validation reduced from 0.458 ...

We have observed a new mechanism for photon-gated spectral hole burning, donor-acceptor electron transfer, in a material composed of a zinc-tetrabenzoporphyrin derivative (donor) with chloroform acceptors in poly(methyl methacrylate) thin films. Gated holes form when we simultaneously excite the donor 0-0 singlet absorption (630 nm) and the donor triplet-triplet absorption (350-550 nm), with the largest gating enhancement (,30) occurring for gating light near 480 nm. The gating action spectrum and the photoproduct spectrum confirm that the mechanism is electron transfer from an excited triplet of the porphyrin donor to the chloroform acceptor. This result opens up a new class of materials for photon gating that should be of interest for frequency-domain optical storage applications as well as high-resolution spectroscopy of electron transfer processes in solids.. © 1987 Optical Society of America. Full Article , PDF Article ...
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Drusen, the hallmark lesions of age related macular degeneration (AMD), are biochemically heterogeneous and the identification of their biochemical distribution is key to the understanding of AMD. Yet the challenges are to develop imaging technology and analytics, which respect the physical generation of the hyperspectral signal in the presence of noise, artifacts, and multiple mixed sources while maximally exploiting the full data dimensionality to uncover clinically relevant spectral signatures. This paper reports on the statistical analysis of hyperspectral signatures of drusen and anatomical regions of interest using snapshot hyperspectral imaging and non-negative matrix factorization (NMF). We propose physical meaningful priors as initialization schemes to NMF for finding low-rank decompositions that capture the underlying physiology of drusen and the macular pigment. Preliminary results show that snapshot hyperspectral imaging in combination with NMF is able to detect biochemically ...
With 1.6 million deaths per year, lung cancer is one of the leading causes of death worldwide. One reason for this high number is the absence of a preventive medical examination method. Many diagnoses occur in a late cancer stage with a low survival rate. An early detection could significantly decrease the mortality. In recent decades, certain substances in human breath have been linked to certain diseases. Different studies show that it is possible to distinguish between lung cancer patients and a healthy control group by analyzing the volatile organic compounds (VOCs) in their breath. We developed a sensor based on photoacoustic spectroscopy for six of the most relevant VOCs linked to lung cancer. As a radiation source, the sensor uses an optical-parametric oscillator (OPO) in a wavelength region from 3.2 µm to 3.5 µm. The limits of detection for a single substance range between 5 ppb and 142 ppb. We also measured high resolution absorption spectra of the biomarkers compared to the data currently
In this paper we report the development and application of photoacoustic spectroscopy (PAS) for the detection and characterization of transient intermediates with lifetimes on the picosecond...
Find photoacoustic spectroscopy articles on Environmental XPRT, the worlds largest environmental industry marketplace and information resource.
Pollution of water is a matter of concern all over the earth. Particles are known to play an important role in the transportation of pollutants in this medium. In addition, the emergence of new materials such as NOAA (Nano-Objects, their Aggregates and their Agglomerates) emphasizes the need to develop adapted instruments for their detection. Surveillance of pollutants in particulate form in waste waters in industries involved in nanopartide manufacturing and processing is a telling example of possible applications of such instrumental development. The LIBS (laser-induced breakdown spectroscopy) technique coupled with the liquid jet as sampling mode for suspensions was deemed as a potential candidate for on-line and real time monitoring. With the final aim in view to obtain the best detection limits, the interaction of nanosecond laser pulses with the liquid jet was examined. The evolution of the volume sampled by laser pulses was estimated as a function of the laser energy applying conditional analysis
JPK Instruments, a world-leading manufacturer of nanoanalytic instrumentation for research in life sciences and soft matter, reports on the work of the Nano-Mechanics Laboratory at the Indian Institute of Science Education &Research (IISER) Pune, India. The Nano-mechanics group develops and uses novel techniques to understand molecular processes and has recently developed new instrumentation in the fields of single molecule force spectroscopy and correlation spectroscopy. There are three main areas of research: protein folding using AFM, measuring the mechanical properties of supported lipid bilayers and following the mechanical response of nano-confined fluids. This last area is performed on home-built instruments. Assistant Professor, Shivprasad Patil, leads the research team. He describes his work and reasons for selecting JPKs NanoWizard® AFM platform and CellHesion® modules to help speed his research efforts. For our protein folding research, we modified our JPK system to enable the ...
Wang, HF. Quantitative analysis of vibrational spectrum and orientational order in Sum Frequency Generation Vibrational Spectroscopy (SFG-VS) studies on molecular interfaces[J]. ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY,2005,230:U303-U303 ...
JILA is a joint physics institute of the University of Colorado at Boulder and the National Institute of Standards and Technology. We support an eclectic and innovative research program that fosters creative collaborations among our scientists. Collaborations play a key role in the pioneering research JILA and the JILA Physics Frontier Center are known for around the world. To learn more, visit our About JILA page.. ...
This paper presents the latest results of a series of experiments deigned to identify situations in which linear and nonlinear mixing models are expect to occur. It continues to investigate the possibility that there may be naturally occurring situation in which the typically used linear mixture model may not provide the most accurate spectrum. It has already been shown that for specific situations, in binary mixing cases, the nonlinear mixing model can produce more accurate endmember abundance estimates. These results are extended to include ternary and quaternary mixtures, as well as hyperspectral imagery collected over Cuprite, Nevada. In order to test these hypotheses, laboratory endmember and mixture data are collected in various scenarios for analysis. As shown in experiments, ternary and quaternary mixtures are more complicated than binary mixtures and the nonlinear mixing is more likely to occur in ternary and quaternary mixtures than in binary mixtures ...
This review explores how imaging techniques are being developed with a focus on deployment for crop monitoring methods. Imaging applications are discussed in relation to both field and glasshouse-based plants, and techniques are sectioned into healthy and diseased plant classification with an emphasis on classification accuracy, early detection of stress, and disease severity. A central focus of the review is the use of hyperspectral imaging and how this is being utilised to find additional information about plant health, and the ability to predict onset of disease. A summary of techniques used to detect biotic and abiotic stress in plants is presented, including the level of accuracy associated with each method.. ...
Optical Spectroscopy has shown promise as a fundamental characterization tool for carbon nanotubes (CNTs). With the potential of CNTs being utilized for aerospace applications, in-situ techniques including temperature and strain measurements with spectroscopy, are gaining significance. These techniques will provide valuable information to advance design and tailoring of CNT reinforcements in composites for maximum strength or damping. Development of these in-situ techniques allow for the study of the effects of external parameters on the spectra of CNTs. The results from these in-situ studies can further be used to develop non-invasive measurement capabilities to establish the integrity of CNT reinforced materials. In this study, changes in the peaks width, intensity, area, and peak location were analyzed under an expansive in-situ temperature range, using a novel deconvolution and fitting algorithm. The findings are significant to the development of optical spectroscopy techniques as characterization
PUBLICATIONS - CONFERENCES - PRESENTATIONS. A. Gates, State of the Art Protein Secondary Structure Prediction Using a Novel Two-Stage Alignment and Machine Learning Method Dissertation Publication: University of Florida Library, 2008. Bolton, P. Gader, and A. Gates, Embedding Multiple Instances: Applications to Hyperspectral Image Analysis, Proceedings of the IEEE Workshop on Hyperspectral Image Signal Processing: Evolution in Remote Sensing, Gainesville, 2013. Hohensee, L. Johnson, A. Gates, Leveraging Google Apps to Enhance Online Learning in Mathematics, American Mathematical Association of Two Year Colleges, 2014. A Gates, A. & Bolton, J. (2015). The Effectiveness of Twitter as an Adjunctive Pedagogical Tool for Online Statistics Education: An Empirical Study. In Proceedings of Society for Information Technology & Teacher Education International Conference 2015 (pp. 2834-2840). Chesapeake, VA: Association for the Advancement of Computing in Education (AACE/SITE).. A. Gates, Methods of ...
Known particles that may cause such scattering include neutrinos and antineutrinos (three flavours each) which are also seen in inelastic destruction and formation processes. Also, since dark matter is thought to not fit neutrino properties, that also means unknown number of different dark matter particles are eligible to cause elastic scattering of visible particles ...
When polymer power cables were introduced into mediumvoltage applications in the late 1960s, the degradationphenomenon later referred to aswater treeingwas still unknown. However, this changedwithin a relatively short space of time. Just 5-10 years afterthese first polymer applications, faults began to appear thatcould be attributed to the new phenomenon-water treeing. Sincethen, cable manufacturers have been improving their designsgradually, and cables produced today are assumed to have muchlower susceptibility to water trees. However, water treeing isstill assumed to be the most important degradation process inthese applications.. There are huge amounts of polymer cable installations thatare degraded by water trees. Since many of these cables areinstalled in the same grid nets, one cable fault oftengenerates another. If two or more cables fail at the same time,the consequences can be extensive. A non-destructive diagnosticmethod makes it possible to assess cables and take action priorto ...
High-resolution C 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of naphthalene are investigated. By comparing the spectral signatures of condensed naphthalene molecules with those of naphthalene in the gas phase, we are able to unambiguously identify spectral features which are affected by the intermolecular interactions in the condensed phase. With the help of calculations using time-dependent density-functional theory and the second-order algebraic-diagrammatic construction scheme for the polarization propagator, resonances in the relevant energy range can be assigned to valence and Rydberg-like excitations. Thus, we obtain a more detailed identification of NEXAFS resonances beyond the present literature.. ...
The electronic absorption spectra (5000-30,000 cm.)(in chloroform) of thirty-three complexes of general formula (Amine)CoX where the amine is quinoline, isoquinoline, 2,6-dimethylpyrazine, pyridine, or a 2-, 3-, or 4-substituted pyridine, and X is Cl, Br, I, NCS, NCO, or NCSe, are reported. The near-infrared absorp
If an optically active organic substance is labelled in the chirality center with another isotopic species (such as15N for14N) a pronounced variation of rotatory power is predicted. We tried to varify this idea experimentally on L-α-alanine and found an isotope effect of ORD (optical rotatory dispersion). The magnitude of the rotation is mainly dependent on the pH of the solvent. The ratio of the optical activity alanine-14N/alanine-15N is about 1.02. The molecular rotations show a consistently lower ratio but it can be seen that the isotope effect is not only a mass effect. ...
If an optically active organic substance is labelled in the chirality center with another isotopic species (such as15N for14N) a pronounced variation of rotatory power is predicted. We tried to varify this idea experimentally on L-α-alanine and found an isotope effect of ORD (optical rotatory dispersion). The magnitude of the rotation is mainly dependent on the pH of the solvent. The ratio of the optical activity alanine-14N/alanine-15N is about 1.02. The molecular rotations show a consistently lower ratio but it can be seen that the isotope effect is not only a mass effect. ...
A dual-mode hyperspectral imager using field of view scanning needs no moving macro parts. It could work in dual-mode (macro imaging and micro imaging) and is equipped with a conjugated camera for quick object-selection and focusing. By adjusting the imaging lens and achieving the image clarity on the conjugated camera, we could find the correct location and focusing of the ROIs simultaneously instead of inefficiently checking the hyperspectral image after the whole scanning process. The whole system was applied to the study of spectral characteristics of blood oxygen in human hands and the microscopic identification of algae, showing a great potential of clinical and marine applications of our system.. ...
A spectroscopy device that separates input light into a plurality of wavelength ranges. A metal body has a hole or aperture which is open on the upper side. The hole or aperture is formed in a polygonal shape having at least a pair of opposite faces not parallel to each other in horizontal cross-section. Inner side faces of the hole or aperture are finished as mirror like reflection surfaces. Polarized input light inputted from the opening to the hole or aperture is reflected by the reflection surfaces and a standing wave is generated inside of the hole or aperture by self interference, whereby the input light is separated into a plurality of wavelength ranges.
The S10121-256Q-01 is self-scanning photodiode arrays designed specifically as detectors for spectroscopy. The scanning circuit operates at low power consumption and is easy to handle. This photodiode has a large photosensitive area with high sensitivity and smoothly varying spectral response characteristics in UV region. Features-High UV sensitivity-High UV sensitivity than previous type-Smoothly varying spectral response characteristics in UV region-Variable integration time for each pixel-Wide photosensitive area Pixel pitch: 50 μm Pixel height: 2.5 mm-Large saturation output charge
Continuing Geography Awareness Week, we would like to talk about a topic that brings together geospatial technologies (it is GIS Day after all) with this years Geography Awareness Week theme of Freshwater. Water quality assessment is a crucial issue in many parts of the world due to causes such as pollution in manufacturing countries, scarcity in arid regions, and issues of access in urban areas. While Earth Observation Day is still a few months away (April 8, 2011), we wanted to take a look at geographic information gathered from remote sensing technologies to understand how this imagery can be used in studying water quality and other water-related issues. There are a number of remote sensing studies that have taken advantage of spectral responses of specific phenomena to look at how light of different wavelengths can capture various water quality issues including sediments suspended in water, algae blooms, aquatic plants, and water temperature. Additional studies of these spectral responses ...
The K3413-08 is a hybrid detector containing an infrared-transmitting Si photodiode mounted over an InGaAs PIN photodiode, along the same optical axis. This structure delivers a wide spectral response range from 0.25 μm to nearly 1.7 μm. The built-in thermoelectric cooler maintains a constant temperature during operation, allowing precision measurement with an improved S/N ratio.Features-Wide spectral response range-Si photodiode and InGaAs PIN photodiode are arranged along the same optical axis-One-stage thermoelectrically cooled type
In this study, an efficient spectral similarity method referred to as Weighted Chebyshev Distance (WCD) is introduced for supervised classification of hyperspectral imagery (HSI) and target detection applications. The WCD is based on a simple spectral similarity based decision rule using limited amount of reference data. The estimation of upper and lower spectral boundaries of spectral signatures for all classes across spectral bands is referred to as a vector tunnel (VT). To obtain the reference information, the training signatures are provided randomly from existing data for a known class. After determination of the parameters of the WCD algorithm with the training set, classification or detection procedures are accomplished at each pixel. The comparative performances of the algorithms are tested under various cases. The decision criterion for classification of an input vector is based on choosing its class corresponding to the narrowest VT that the input vector fits in to. This is also shown to be
BioMEMS as microsystems designed for biomedical and biological applications provide various functions from micro implants, Lab-on-chip, PoC diagnostics to biosensors. This paper focuses on the sensing capability of BioMEMS in cell characterization, drug screening and biofilm detection. In situ staining and electrical approaches as impedance spectroscopy, dielectric spectroscopy and contactless impedimetric sensing are presented and discussed for applications in 3D cell culturing, for drug screening, sedimentation analysis in aquatic research and biofilm detection in indwelling devices.. Download. ...
Author(s): Digiacomo, Luca; Digman, Michelle A; Gratton, Enrico; Caracciolo, Giulio | Abstract: Fluorescence microscopy and spectroscopy techniques are commonly used to investigate complex and interacting biological systems (e.g. proteins and nanoparticles in living cells), since these techniques can explore intracellular dynamics with high time resolution at the nanoscale. Here we extended one of the Image Correlation Spectroscopy (ICS) methods, i.e. the image Mean Square Displacement, in order to study 2-dimensional diffusive and flow motion in confined systems, whose driving speed is uniformly distributed in a variable angular range. Although these conditions are not deeply investigated in the current literature, they can be commonly found in the intracellular trafficking of nanocarriers, which diffuse in the cytoplasm and/or may move along the cytoskeleton in different directions. The proposed approach could reveal the underlying systems symmetry using methods derived from fluorescence correlation
The wavelength-resolved fluorescence excitation technique has been used to record the (0,0) band of the $b^{3}\Pi_{1} - X^{1}\Sigma^{+}$ electronic transition of HfO at a resolution of $0.03 cm^{-1}$. $Previously^{1}$, this transition has been assigned as a $B^{1}\Pi - X^{1}\Sigma^{+}$ electronic transition. The principal constants (in $cm^{-1}$) obtained from recent and previous $analyses^{1,2}$ are: \$\begin{array}{lccl}State&Configuration&T_{0}&B_{0}\\ {[}31.4{]}^{3}\Phi_{4}&5d6p&z+22 655.82&0.3719\\ {[}31.4{]}^{3}\Phi_{3}&5d6p&31 392.17&0.3699\\ {[}31.4{]}^{3}\Phi_{1}&5d6p&29 208.32&0.3696\\ G^{1}\Sigma^{+}&5g6s&30 032.706(8)&0.369 070(3)\\ F^{1}\Sigma^{+}(^{3}\Pi_{0+})&6s69(?)&27 351.136(8)&0.364 688(3)\\ E^{1}\Pi (c^{3}\Sigma^{+}_{1})&5d6s&25 176.878(7)&0.367 694(3)e\\ &&&0.368 294(4)f\\ D^{1}\Pi&5d6s&23 503.280(5)&0.368 191(3)e\\ &&&0.367 460(3)f\\ X^{1}\Sigma^{+}&62^{2}&0.0&0.385 644 05(2)\\ a^{3}\Delta_{3}&5d6s&z&0.378 644(7)\\ a^{3}\Delta_{2}&5d6s&10 152.303(12)&0.377 957(13)\\ ...
The quantitative understanding of nature at the molecular levels is the field of physical chemistry and I am interested in the spectroscopy properties of molecules to provide a unique diagnostic of the physical processes occurring in these diverse environments. We have research projects in spanning a large field from interfacial electronic spectroscopy, through nanotoxicology to the recovery of patients from major surgery. The current projects include:. ...
Which shows an absorption band at a larger wavenumber: a carbonyl group bonded to an sp3 carbon or acarbonyl group bonded to an sp2 carbon of an alkene?
misc{4936673, abstract = {Optical spectroscopy is commonly used in technology and science today. The presence and concentration of a substance can be determined by its spectral signature, the typical wavelengths that are absorbed (or emitted) by the atoms or molecules. Standard absorption spectroscopy requires that the substance is clear and that the optical path-length is known to obtain quantitative information. Unfortunately in many materials, such as human tissue or pharmaceutical tablets, there are also a strong scattering of light which complicates measurements. The pathlength of the light is now no longer known and the intensity of the detected light can in many cases be more affected by high scattering than by the absorption values. One method to separate these two values are photon Time-of-Flight Spectroscopy (TOFS). By sending many short light pulses through a sample, and recording the time for a single photon to arrive at our detector for each pulse, we can build a histogram that ...
In hyperspectral imaging, spectral unmixing aims at decomposing the image into a set of reference spectral signatures corresponding to the materials present in the observed scene and their relative proportions in every pixel. While a linear mixing model was used for a long time, the complex nature of the physico-chemical phenomena that affect the spectra of the materials led to shift the communitys attention towards algorithms accounting for the variability of the endmembers. Such intra-class variations are mainly due to local changes in the composition of the materials, and to illumination changes. In the physical remote sensing community, a popular model accounting for illumination variability is the radiative transfer model proposed by Hapke. It is however too complex to be directly used in hyperspectral unmixing in a tractable way. Instead, the Extended Linear Mixing Model (ELMM) allows to easily unmix hyperspectral data accounting for changing illumination conditions and to address nonlinear
Hyperspectral imagery is a new class of image data which is mainly used in remote sensing. It is characterized by a wealth of spatial and spectral information that can be used to improve detection and estimation accuracy in chemical and biological standoff detection applications. Finding spectral endmembers is a very important task in hyperspectral data exploitation. Over the last decade, several algorithms have been proposed to find spectral endmembers in hyperspectral data. Existing algorithms may be categorized into two different classes: 1) endmember extraction algorithms (EEAs), designed to find pure (or purest available) pixels, and 2) endmember generation algorithms (EGAs), designed to find pure spectral signatures. Such a distinction between an EEA and an EGA has never been made before in the literature. In this paper, we explore the concept of endmember generation as opposed to that of endmember extraction by describing our experience with two EGAs: the optical real-time adaptative ...
EN] Dielectric spectroscopy studies have been performed on fresh and osmotically dehydrated Granny Smith apples. The osmotic treatment consisted on immerse the samples into 65% (w/w) sucrose aqueous solution at 30 degrees ...
Because spectral peaks are so relatively dominant in hearing, sinusoidal models are unreasonably effective in capturing the tonal aspects of sound in a compact, easy-to-manipulate form. Computing a sinusoidal model entails fitting the parameters of a sinusoid (amplitude, frequency, and sometimes phase) to each peak in the spectrum of each time-segment. In typical sinusoidal modeling systems, the sinusoidal parameters are linearly interpolated from one time segment to the next, and this usually provides a perceptually smooth variation over time. (Higher order interpolation has also been used.) Modeling sound as a superposition of modulated sinusoids in this way is generally called additive synthesis [233]. Additive synthesis is not the only sound modeling method that requires sinusoidal parameter estimation for its calibration to desired signals. For the same reason that additive synthesis is so effective, we routinely calibrate any model for sound production by matching the short-time ...
Baldwin provides the code and explains the requirements for using spectral analysis to resolve spectral peaks for pulses containing closely spaced truncated sinusoids.