Spectral Monitoring Research Articles

Detection of fibronectin conformational changes in the extracellular matrix of live cells using plasmonic nanoplates.

Protein conformational changes are detected both in vitro and for the first time in the presence of living cells using versatile plasmonic nanoplates. Au-edge-coated triangular silver nanoplates (AuTSNP) exhibit some of the highest refractive index sensitivity values recorded to date and exhibit a strong spectral response to surface biomolecular interactions. Large spectral shifts of over 30 nm distinguish between pH induced compact and extended conformations of the ubiquitous extracellular matrix protein fibronectin (Fn). Conformational transition of Fn from compact to extended is accompanied by a red spectral shift of 27 nm while a corresponding blue spectral shift of 25 nm accompanies the reverse conformational transition. Cleavage of Fn by cathepsin B, which plays an important role in cellular functions and in cancer metastasis is characterised by a blue spectral shift with detection in serum using a straightforward no-wash assay demonstrated. Spectral monitoring of nanoplates decorated with Fn and incubated with MDCK II cells shows extensive shifts of 156 nm and cellular morphological re-arrangement as Fn uncoils from a compact format to from fibrils within the extracellular matrix.

Spectral optical monitoring of the double-peaked emission line AGN Arp 102B

We investigate a long-term (26 years, from 1987 to 2013) variability in the broad spectral line properties of the radio galaxy Arp 102B, an active galaxy with broad double-peaked emission lines. We use observations presented in Paper I (Shapovalova et al. 2013) in the period from 1987 to 2011, and a new set of observations performed in 2012--2013. To explore the BLR geometry, and clarify some contradictions about the nature of the BLR in Arp 102B we explore variations in the H$\alpha$ and H$\beta$ line parameters during the monitored period. We fit the broad lines with three broad Gaussian functions finding the positions and intensities of the blue and red peaks in H$\alpha$ and H$\beta$. Additionally we fit averaged line profiles with the disc model. We find that the broad line profiles are double-peaked and have not been changed significantly in shapes, beside an additional small peak that, from time to time can be seen in the blue part of the H$\alpha$ line. The positions of the blue and red peaks { have not changed significantly during the monitored period. The H$\beta$ line is broader than H$\alpha$ line in the monitored period. The disc model is able to reproduce the H$\beta$ and H$\alpha$ broad line profiles, however, observed variability in the line parameters are not in a good agreement with the emission disc hypothesis. It seems that the BLR of Arp 102B has a disc-like geometry, but the role of an outflow can also play an important role in observed variation of the broad line properties.

RADIAL VELOCITY CURVES OF ELLIPSOIDAL RED GIANT BINARIES IN THE LARGE MAGELLANIC CLOUD

Ellipsoidal red giant binaries are close binary systems where an unseen, relatively close companion distorts the red giant, leading to light variations as the red giant moves around its orbit. These binaries are likely to be the immediate evolutionary precursors of close binary planetary nebula and post-asymptotic giant branch and post-red giant branch stars. Due to the MACHO and OGLE photometric monitoring projects, the light variability nature of these ellipsoidal variables has been well studied. However, due to the lack of radial velocity curves, the nature of their masses, separations, and other orbital details has so far remained largely unknown. In order to improve this situation, we have carried out spectral monitoring observations of a large sample of 80 ellipsoidal variables in the Large Magellanic Cloud and we have derived radial velocity curves. At least 12 radial velocity points with good quality were obtained for most of the ellipsoidal variables. The radial velocity data are provided with this paper. Combining the photometric and radial velocity data, we present some statistical results related to the binary properties of these ellipsoidal variables.

The link between broad emission line fluctuations and non-thermal emission from the inner AGN jet

AbstractAGN reverberate when the broad emission lines respond to changes of the ionizing thermal continuum emission. Reverberation measurements have been commonly used to estimate the size of the broad-line region (BLR) and the mass of the central black hole. However, reverberation mapping studies have been mostly performed on radio-quiet sources where the contribution of the jet can be neglected. In radio-loud AGN, jets and outflows may affect substantially the relation observed between the ionizing continuum and the line emission. To investigate this relation, we have conducted a series of multi-wavelength studies of radio-loud AGN, combining optical spectral line monitoring with regular VLBI observations. Our results suggest that at least a fraction of the broad-line emitting material can be located in a sub-relativistic outflow ionized by non-thermal continuum emission generated in the jet at large distances (> 1 pc) from the central engine of AGN. This finding may have a strong impact on black hole mass estimates based on measured widths of the broad emission lines and on the gamma-ray emission mechanisms.

Results of spectral monitoring of environmental gamma background in a fault zone of the Western Caucasus for seismological application

Results of continuous spectral monitoring of indoor gamma background are reported for seismological application in one fault zone of the Western Caucasus. Background count rates were recorded every 5 min since 2004. Two detectors (a scintillation crystal CsI(Tl), 200 mm × 150 mm in a low background metal screen and a NaI(Tl) detector, 90 mm × 90 mm outside of the screen) were used. Various intervals of energy of gamma rays, for example, (2.50–3.40) MeV, (1.70–2.00) MeV, (1.35–1.55) MeV and others were analyzed. Averages for all measurements as well as seasonal and hourly changes of count rate of detectors were obtained. As an example, for the interval (1.70–2.00) MeV a minimal monthly count rate of detector CsI(Tl) was observed in June, and the maximal monthly count rate of detector NaI(Tl) was observed in July. Factors of correlation between different intervals of energy of gamma rays were also investigated. Strong changes of annual, monthly and daily factors were obtained.In each daily curve of all intervals of energy of gamma rays, the first Fourier harmonic was calculated. The deviations from 3σ (“splash”), which are upward or downward from the first harmonic, were compared with the seismological data. It was possible to correlate the low background dates of “splashes” with the dates of regional earthquakes through 9 ± 1 days.Change of ratio of count rate in different intervals of energy of gamma rays can be used to study processes of preparation of earthquakes.The factor of correlations between intervals (2.50–3.40) MeV and (1.70–2.00) MeV increased to almost 1.00 close to earthquakes. This effect was obtained in low background screen.Connection of the gamma data with the meteorological data was not obtained.

Probabilistic Neural Network Southern Jujube Pest Stress Index Leaf Pigment Estimation Model Based Hyperspectral

Analysis jujube leaf rust pigment content and spectral reflectance correlation study comparing jujube leaf rust pigment content and differential spectral correlation. Hyperspectral characteristic parameters to achieve the southern jujube jujube leaf rust pigments PC1/PC2 and PC1+PC2 content estimation. Using a combination of linear and polynomial fitting method to construct the canopy hyperspectral disease dates Brix content estimation model and test. The probabilistic neural network PNN and SVM classifier SVC applied to hyperspectral estimation model, comparative analysis of model accuracy. The results of the quantitative estimation of disease hyperspectral information dates pigment content in leaves of jujube growing use of high spectral monitoring and impact assessment of disease have high practical value.

Synthesis, spectral characterization and crystal structure of Ni(II) pyridoxal thiosemicarbazone complexes and their recyclable catalytic application in the nitroaldol (Henry) reaction in ionic liquid media

The new square planar nickel(II) complexes 1, 2 and 3 have been synthesized from the reaction of [NiCl2(PPh3)2] with the tridentate Schiff base ligand, pyridoxal thiosemicarbazone (L1), pyridoxal N-methyl thiosemicarbazone (L2) and pyridoxal N-phenyl thiosemicarbazone (L3) respectively in ethanol. These complexes have been characterized by elemental analyses, IR, UV–Vis, 1H NMR, 31P NMR and ESI-MS spectroscopy. The molecular structure of the complex [Ni(L2)PPh3] (2) was determined by single-crystal X-ray diffraction, which reveals a distorted square planar geometry around the nickel(II) ion. The nitroaldol reaction was studied in detail using the nickel(II) complexes as catalysts in a homogeneous solution formed by an ionic liquid and methanol. The effect of solvent, ionic liquid, time, temperature, catalyst loading and substituent of the ligand moiety on the reaction was also studied. The β-nitroalcohol products were obtained in good yields of up to 97%. A two step substrate addition mechanism was tentatively proposed based on ESI-MS spectral monitoring of the reaction mass.

Water molecular system dynamics associated with amyloidogenic nucleation as revealed by real time near infrared spectroscopy and aquaphotomics.

The formation of amyloid fibrils proceeds via a nucleation-dependent mechanism in which nucleation phase is generally associated with a high free energy resulting in the rate-limiting step. On the basis of this kinetic feature, the nucleation is one of the most crucial phases controlling the pathogenesis of amyloidoses, but little is known about the details of how protein molecules and surrounding environment vary at this stage. Here, we applied near infrared (NIR) spectral monitoring of water structural changes in real time during the nucleation-dependent fibrillation of insulin. Whilst multivariate spectral analysis in the 2050–2350 nm spectral region indicated cross-β formation, characteristic transformations of water structure have been detected in the spectral region 1300–1600 nm corresponding to the first overtone of water OH stretching vibrations. Furthermore, specific water spectral patterns (aquagrams) related to different water molecular conformations have been found along the course of protein nucleation and aggregation. Right in the beginning, dissociation of hydrogen-bonded network in bulk water and coinstantaneous protein and ion hydration were observed, followed by water hydrogen-bonded networks development, presumably forcing the nucleation. These specific transformations of water spectral pattern could be used further as a biomarker for early non-invasive diagnosis of amyloidoses prior to explosive amplification and deposits of amyloid fibrils.

Coupling of an advanced tri-functional building block by reductive amination leads to a protected backbone of a new archetype of foldamer

In order to advance our project to explore a new archetype of foldamer that preferentially folds in water, we designed two types of tri-functional building blocks with increasingly favorable ketone deprotection properties. Both were selected for their ease of synthetic access and the availability of bulk starting material. While the first building block proved unsuitable for efficient coupling by reductive amination, the second gave rise to almost quantitative yields according to mass spectral monitoring. It was thus effectively turned into a protected dimer and a tetramer. Although their subsequent purification prior to exhaustive ketone deprotection was preparatively impractical in view of their high polarity/water solubility, the stage is now set for transfer of the oligomer synthesis onto the solid phase on resin in view of the efficient five-step synthetic access from affordable bulk material, the favorable deprotection properties, the perspective for introduction of a variety of backbone substituents, and the possibility to protect the amine terminus by Boc or Fmoc protection.

Research Jujube Pest Stress Index Leaf Pigment Hyperspectral Model Based on Wireless Sensor Networks in the Southern Region of Xinjiang

Measured southern jujube pest stress index leaf pigment, create jujube jujube leaf rust sensitive bands characteristic parameter table, analyze the spectral characteristics of the relevant characteristics and vegetation index jujube high correlation parameters. Determination of diseased leaves and growing spectrum of different pigment content. Analysis jujube leaf rust pigment content and spectral reflectance correlation study comparing jujube leaf rust pigment content and differential spectral correlation. Hyperspectral characteristic parameters to achieve the southern jujube jujube leaf rust pigments PC1/PC2 and PC1+PC2 content estimation. Using a combination of linear and polynomial fitting method to construct the canopy hyperspectral disease dates Brix content estimation model and test. The probabilistic neural network PNN and SVM classifier SVC applied to hyperspectral estimation model, comparative analysis of model accuracy. The results of the quantitative estimation of disease hyperspectral information dates pigment content in leaves of jujube growing use of high spectral monitoring and impact assessment of disease have high practical value. classification accuracy of 98%, obtained very satisfactory recognition results.

Spectral Graph Analysis for Process Monitoring

Process monitoring is a fundamental task to support operator decisions under abnormal situations. In this article, spectral graph analysis monitoring (SGAM) is introduced. The approach is based on the spectral graph analysis theory. First, a weighted graph representation of process measurements is developed. Second, the process behavior is parametrized by means of graph spectral features, in particular, the algebraic connectivity and the spectral energy. The developed methodology is illustrated in autocorrelated and nonlinear synthetic cases and applied to the well-known Tennessee Eastman process benchmark with promising results.

Preoperative paracetamol infusion reduces sevoflurane consumption during thyroidectomy under general anesthesia with spectral entropy monitoring

BackgroundIntravenous (IV) paracetamol has a significant opioid-sparing effect. We investigated the effect of paracetamol infusion on sevoflurane consumption during entropy monitored general anesthesia.MethodsSixty-two ASA I and II patients undergoing thyroidectomy under general anesthesia were included in a prospective, randomized, double-blind and placebo controlled study. The patients were randomized to receive a slow infusion of either 1 g paracetamol (paracetamol group, n = 31) or saline (control group, n = 31) just before induction of anesthesia. Sevoflurane concentration was titrated to keep the state entropy value between 40 and 50. End-tidal sevoflurane concentration, sevoflurane consumption, recovery characteristics, time to first analgesic request and meperidine consumption during the first 6 postoperative hours were recorded.ResultsThe mean ± SD estimated sevoflurane consumption was significantly lower in the paracetamol treated patients (36.2 ± 15 vs 44.9 ± 13.9 ml, in the control group; p = 0.021). Patients receiving paracetamol had a faster post-anesthetic recovery profile (extubation time, time to eye opening to command and time to state name and mention his/her home address) than the other group (p < 0.05). Mean ± SD time to first analgesic request was significantly prolonged in paracetamol group compared to control group (48.4 ± 14.0 vs 40.7 ± 11.5 min, respectively; p = 0.021). Meperidine consumption was higher in control group than in paracetamol group (28.7 ± 10.2 vs 23.1 ± 9.0 mg, respectively; p = 0.025).ConclusionPreoperative IV paracetamol infusion improved consumption and emergence from entropy monitored sevoflurane anesthesia with enhancement of the early postoperative analgesia.

The Spectral Aerosol Extinction Monitoring System (SǼMS): setup, observational products, and comparisons

Abstract. The Spectral Aerosol Extinction Monitoring System (SǼMS) is presented that allows us to continuously measure the spectral extinction coefficient of atmospheric aerosol particles along an approximately 2.7 km long optical path at 30–50 m height above ground in Leipzig (51.3° N, 12.4° E), Germany. The fully automated instrument measures the ambient aerosol extinction coefficients from 300 to 1000 nm. The main goal of SǼMS observations are long-term studies of the relationship between particle extinction and relative humidity from below 40% to almost 100%. The setup is presented and observations (a case study and statistical results for 2009) are discussed in terms of time series of 550 nm particle optical depth, Ångström exponent, and particle size distribution retrieved from the spectrally resolved extinction. The SǼMS measurements are compared with simultaneously performed EARLINET (European Aerosol Research Lidar Network) lidar, AERONET (Aerosol Robotic Network) sun photometer, and in situ aerosol observations of particle size distribution and related extinction coefficients on the roof of our institute. Consistency between the different measurements is found, which corroborates the quality of the SǼMS observations. Statistical results of a period of 1 yr (2009) show mode extinction values of 0.09 km−1 (SǼMS), 0.075 km−1 (AERONET), and 0.03 km−1 (in situ). Ångström exponents for this period are 0.19 (390–880 nm, SǼMS) and 1.55 (440–870 nm, AERONET).

Near-infrared spectral monitoring of Pluto’s ices II: Recent decline of CO and N2 ice absorptions

IRTF/SpeX observations of Pluto’s near-infrared reflectance spectrum during 2013 show vibrational absorption features of CO and N2 ices at 1.58 and 2.15μm, respectively, that are weaker than had been observed during the preceding decade. To reconcile declining volatile ice absorptions with a lack of decline in Pluto’s atmospheric pressure, we suggest these ices could be getting harder to see because of increasing scattering by small CH4 crystals, rather than because they are disappearing from the observed hemisphere.

A System for the Spectral Monitoring of the Deposition of Multilayer Dielectric Coatings

A high precision system for monitoring the thicknesses of the layers of multilayer dielectric coatings over a wide spectral range has been constructed. An example of the use of the system to construct an antireflection coating with a maximum reflection coefficient of 0.15% in the 400 – 660 nm spectral range on VU-2M vacuum equipment is presented.

Spectral monitoring of moorland plant phenology to identify a temporal window for hyperspectral remote sensing of peatland

Recognising the importance of the timing of image acquisition on the spectral response in remote sensing of vegetated ecosystems is essential. This study used full wavelength, 350–2500nm, field spectroscopy to establish a spectral library of phenological change for key moorland species, and to investigate suitable temporal windows for monitoring upland peatland systems. Spectral responses over two consecutive growing seasons were recorded at single species plots for key moorland species and species sown to restore eroding peat. This was related to phenological change using narrowband vegetation indices (Red Edge Position, Photochemical Reflectance Index, Plant Senescence Reflection Index and Cellulose Absorption Index); that capture green-up and senescence related changes in absorption features in the visible to near infrared and the shortwave infrared. The selection of indices was confirmed by identifying the regions of maximum variation in the captured reflectance across the full spectrum. The indices show change in the degree of variation between species occurring from April to September, measured for plant functional types. A discriminant function analysis between indices and plant functional types determines how well each index was able to differentiate between the plant functional groups for each month. It identifies April and July as the two months where the species are most separable. What is presented here is not one single recommendation for the optimal temporal window for operational monitoring, but a fuller understanding of how the spectral response changes with the phenological cycle, including recommendations for what indices are important throughout the year.

A Micro-Perfusion System for the Fluorescence-Based Monitoring of Physiological Responses to High Hydrostatic Pressures

Hydrostatic pressures of 102 to 103 atm affect a range of cellular processes, including motility, cell division, nutrient uptake, fermentation, translation and transcription, protein synthesis, and ultimately viability. In order to perform the real time monitoring of pressure effects, we present a micro-perfusion system designed for spectroscopic measurements on cellular systems under high pressure. The system consists of an optically-compatible pressure chamber and interchangeable fluid reservoirs. Perfusion is achieved using a dual pressure-generator configuration, where one positive-displacement generator is compressed while the other is retracted, thus maintaining a pressurized volume while achieving fluid flow. Control over perfusion rates (typically in the 10 μl/s range) and the ability to change between fluid reservoirs while under pressure (up to 600 atm) are demonstrated. Next, the system is used for the time-gated, spectral monitoring of endogenous NADH fluorescence under pressure. Spectrofluorimetric measurements utilize a nitrogen-discharge laser for sub-nanosecond pulse width, 337-nm wavelength excitation, and an intensified CCD coupled to a spectrograph for nanosecond-gated spectral detection. Because emission from NADH is routinely used at ambient pressure for monitoring mitochondrial function, we validate the system by observing the pressurized response of Saccharomyces cerevisiae (baker's yeast) to mitochondrial functional modifiers (e.g., cyanide). Because the system is compatible with both spectroscopy and sub-cellular resolution microscopy imaging, the system represents a robust tool for investigating the biophysical effects of pressure on cellular systems.

Spectral optical monitoring of a double-peaked emission line AGN Arp 102B

Here we present results of the long-term (1987-2010) optical spectral monitoring of the broad line radio galaxy Arp 102B, a prototype of active galactic nuclei with the double-peaked broad emission lines, usually assumed to be emitted from an accretion disk. To explore the structure of the broad line region (BLR), we analyze the light curves of the broad H\alpha and H\beta lines and the continuum flux. We aim to estimate the dimensions of the broad-line emitting regions and the mass of the central black hole. We use the CCF to find lags between the lines and continuum variations. We investigate in more details the correlation between line and continuum fluxes, moreover we explore periodical variations of the red-to-blue line flux ratio using Lomb-Scargle periodograms. The line and continuum light curves show several flare-like events. The fluxes in lines and in the continuum are not showing a big change (around 20%) during the monitoring period. We found a small correlation between the line and continuum flux variation, that may indicate that variation in lines has weak connection with the variation of the central photoionization source. In spite of a low line-continuum correlation, using several methods, we estimated a time lag for H\beta around 20 days. The correlation between the H\beta and H\alpha flux variation is significantly higher than between lines and continuum. During the monitoring period, the H\beta and H\alpha lines show double-peaked profiles and we found an indication for a periodical oscillation in the red-to-blue flux ratio of the H\alpha line. The estimated mass of the central black hole is \sim 1.1 \times 10^8 M\odot that is in an agreement with the mass estimated from the M-\sigma* relation.

The One Hour Yeast Proteome

We describe the comprehensive analysis of the yeast proteome in just over one hour of optimized analysis. We achieve this expedited proteome characterization with improved sample preparation, chromatographic separations, and by using a new Orbitrap hybrid mass spectrometer equipped with a mass filter, a collision cell, a high-field Orbitrap analyzer, and, finally, a dual cell linear ion trap analyzer (Q-OT-qIT, Orbitrap Fusion). This system offers high MS2 acquisition speed of 20 Hz and detects up to 19 peptide sequences within a single second of operation. Over a 1.3 h chromatographic method, the Q-OT-qIT hybrid collected an average of 13,447 MS1 and 80,460 MS2 scans (per run) to produce 43,400 (x̄) peptide spectral matches and 34,255 (x̄) peptides with unique amino acid sequences (1% false discovery rate (FDR)). On average, each one hour analysis achieved detection of 3,977 proteins (1% FDR). We conclude that further improvements in mass spectrometer scan rate could render comprehensive analysis of the human proteome within a few hours.

&lt;em&gt;In-situ&lt;/em&gt; Tapering of Chalcogenide Fiber for Mid-infrared Supercontinuum Generation

Supercontinuum generation (SCG) in a tapered chalcogenide fiber is desirable for broadening mid-infrared (or mid-IR, roughly the 2-20 μm wavelength range) frequency combs(1, 2) for applications such as molecular fingerprinting, (3) trace gas detection, (4) laser-driven particle acceleration, (5) and x-ray production via high harmonic generation. (6) Achieving efficient SCG in a tapered optical fiber requires precise control of the group velocity dispersion (GVD) and the temporal properties of the optical pulses at the beginning of the fiber, (7) which depend strongly on the geometry of the taper. (8) Due to variations in the tapering setup and procedure for successive SCG experiments-such as fiber length, tapering environment temperature, or power coupled into the fiber, in-situ spectral monitoring of the SCG is necessary to optimize the output spectrum for a single experiment. In-situ fiber tapering for SCG consists of coupling the pump source through the fiber to be tapered to a spectral measurement device. The fiber is then tapered while the spectral measurement signal is observed in real-time. When the signal reaches its peak, the tapering is stopped. The in-situ tapering procedure allows for generation of a stable, octave-spanning, mid-IR frequency comb from the sub harmonic of a commercially available near-IR frequency comb. (9) This method lowers cost due to the reduction in time and materials required to fabricate an optimal taper with a waist length of only 2 mm. The in-situ tapering technique can be extended to optimizing microstructured optical fiber (MOF) for SCG(10) or tuning of the passband of MOFs, (11) optimizing tapered fiber pairs for fused fiber couplers(12) and wavelength division multiplexers (WDMs), (13) or modifying dispersion compensation for compression or stretching of optical pulses.(14-16.)