Applications of a New 206.5-nm Continuous-Wave Laser Source: UV Raman Determination of Protein Secondary Structure and CVD Diamond Material Properties

1996 ◽  
Vol 50 (11) ◽  
pp. 1459-1468 ◽  
Author(s):  
Janet S. W. Holtz ◽  
Richard W. Bormett ◽  
Zhenhuan Chi ◽  
Namjun Cho ◽  
X. G. Chen ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Raman Spectra ◽  
Continuous Wave ◽  
Broad Band ◽  
Protein Secondary Structure ◽  
Cvd Diamond ◽  
Spectroscopic Studies ◽  
Laser Source ◽  
High Signal ◽  
Signal To Noise

We demonstrate the utility of a new 206.5-nm continuous-wave UV laser excitation source for spectroscopic studies of proteins and CVD diamond. Excitation at 206.5 nm is obtained by intracavity frequency doubling the 413-nm line of a krypton-ion laser. We use this excitation to excite resonance Raman spectra within the π → π amide transition of the protein peptide backbone. The 206.5-nm excitation resonance enhances the protein amide vibrational modes. We use these high signal-to-noise spectral data to determine protein secondary structure. We also demonstrate the utility of this source to excite CVD and gem-quality diamond within its electronic bandgap. The diamond Raman spectra have very high signal-to-noise ratios and show no interfering broad-band luminescence. Excitation within the diamond bandgap also gives rise to narrow photoluminescence peaks from diamond defects. These features have previously been observed only by cathodoluminescence measurements. This new continuous-wave UV source is superior to the previous pulsed sources, because it avoids nonlinear optical phenomena and thermal sample damage; Photoluminescence.

UV Raman Microspectroscopy: Spectral and Spatial Selectivity with Sensitivity and Simplicity

1997 ◽  
Vol 51 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Vasil Pajcini ◽  
Calum H. Munro ◽  
Richard W. Bormett ◽  
Robert E. Witkowski ◽  
Sanford A. Asher
Keyword(s):  
Raman Spectra ◽  
Spatial Resolution ◽  
Rayleigh Scattering ◽  
Continuous Wave ◽  
Diamond Films ◽  
Cvd Diamond ◽  
High Signal ◽  
Spatially Resolved ◽  
Uv Raman ◽  
Nondiamond Carbon

The high sensitivity, selectivity, spatial resolution, and ease of operation of UV Raman microspectr oscopy is demonstrated with the use of a new highly efficient UV Raman microspectrometer with excitation at 244 nm. Single spectrograph dispersion combined with special new filters for the rejection of Rayleigh scattering improves the throughput efficiency by a factor of approximately 4 in comparison to a triple-stage spectrograph. The instrument has a spatial resolution of approximately 3 μm × 9 μm in the lateral (X–Y) plane, and 10 μm or less in the axial (Z) plane. UV resonance Raman spectra of nucleic acids are selectively excited from spatially resolved areas of a single paramecium by using low continuous-wave (cw) excitation powers and short accumulation times to minimize sample damage. High signal-to-noise Raman spectra are excited from spatially resolved areas of chemical-vapor-deposited (CVD) diamond films. We demonstrate, for the first time, the ability to probe the spatial distribution of the nondiamond carbon impurities in CVD diamond films. The amorphous carbon band at ∼ 1553 cm−1 is resolved from the normally broad ∼ 1600-cm−1 nondiamond carbon band.

scholarly journals Peak Fitting Applied to Fourier Transform Infrared and Raman Spectroscopic Analysis of Proteins

2020 ◽  
Vol 10 (17) ◽  
pp. 5918
Author(s):  
Azin Sadat ◽  
Iris J. Joye
Keyword(s):  
Secondary Structure ◽  
Raman Spectra ◽  
Protein Secondary Structure ◽  
Structural Data ◽  
Accurate Method ◽  
Globular Proteins ◽  
Raman Spectroscopic ◽  
Peak Separation ◽  
Secondary Structure Of Proteins ◽  
Ft Raman

FTIR and Raman spectroscopy are often used to investigate the secondary structure of proteins. Focus is then often laid on the different features that can be distinguished in the Amide I band (1600–1700 cm−1) and, to a lesser extent, the Amide II band (1510–1580 cm−1), signature regions for C=O stretching/N-H bending, and N-H bending/C-N stretching vibrations, respectively. Proper investigation of all hidden and overlapping features/peaks is a necessary step to achieve reliable analysis of FTIR and FT-Raman spectra of proteins. This paper discusses a method to identify, separate, and quantify the hidden peaks in the amide I band region of infrared and Raman spectra of four globular proteins in aqueous solution as well as hydrated zein and gluten proteins. The globular proteins studied, which differ widely in terms of their secondary structures, include immunoglobulin G, concanavalin A, lysozyme, and trypsin. Peak finding was done by analysis of the second derivative of the original spectra. Peak separation and quantification was achieved by curve fitting using the Voigt function. Structural data derived from the FT-Raman and FTIR analyses were compared to literature reports on protein structure. This manuscript proposes an accurate method to analyze protein secondary structure based on the amide I band in vibrational spectra.

Maximum Entropy Methods Applied to Simulated and Observed Raman Spectra

1996 ◽  
Vol 50 (1) ◽  
pp. 43-47 ◽  
Author(s):  
C. Craggs ◽  
K. P. Galloway ◽  
D. J. Gardiner
Keyword(s):  
Maximum Entropy ◽  
Raman Spectra ◽  
High Signal ◽  
Signal Recovery ◽  
Signal To Noise ◽  
Entropy Methods ◽  
Band Area ◽  
Area Reduction ◽  
The Mean ◽  
Squared Residuals

One- and two-channel maximum entropy methods (MEMs) have been applied to simulated and experimental Raman spectra of both single and double (overlapping) bands. The extent to which signal recovery is affected by signal-to-noise ratios has been determined with the use of measures based on the mean sum of squared residuals, loss of band intensity, and band area reduction. The analysis demonstrates that the two-channel approach results in improved signal recovery, especially at high signal-to-noise ratios.

Non-Resonance Acousto-Optics Signal Analysis from Photonics Microphone Using 1 mW Laser

2016 ◽  
Vol 846 ◽  
pp. 740-747
Author(s):  
Muhammad Adib Akram Mohdami Norashid ◽  
M. Kamil Abd-Rahman
Keyword(s):  
Laser Beam ◽  
Acoustic Waves ◽  
High Speed ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Free Space Optical ◽  
Signal To Noise ◽  
Optical Signals ◽  
Noise Ratio

This paper presents an acousto-optics analysis on free space optical signals modulated by two distinguishable non-resonant acoustic waves. The acoustic waves were directed at two different directions and locations along a laser beam and created non-interference modulated optical signals. The photonics microphone deploys low-powered eye-safe continuous-wave 633-nm laser; high-speed photodiode and a series of Fourier lenses. Two transducers generating 20 Hz to 20 kHz acoustic waves were directed across the laser beam. The receiving modulated signal was filtered and amplified electronically by two sets of passive bandpass filter separated by a transimpedance amplifier and connected to a computer for analysis. The signal was further digitally filtered and amplified to enhance the signal-to-noise ratio via MATLAB software. These signals were analyzed in time and frequency domains using Fast Fourier Transform (FFT) and Spectrogram. It was found that the recorded signals demonstrated higher signal intensities for lower acoustic frequencies with digital signal-to-noise ratio (SNR) ranging from 10.77 to 71.92 for frequency of 1 kHz to 20 kHz and 20 Hz to 1 kHz respectively. The frequencies of both transducers were simultaneously swept through from 20 Hz and 20 kHz respectively. These scanning frequencies approached one another and crossover with no resonant frequency was observed. This illustrates that it is able to detect multiple acoustic signals for any given frequencies along the laser beam and found its applications in stealth sound detection and long range sound sensor. Though low-powered 1-mW laser was used, a relatively high signal-to-noise ratio with clear-recorded playback was achieved.

scholarly journals Spectroscopic evidence for a large spot on the dimming Betelgeuse

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofya Alexeeva ◽  
Gang Zhao ◽  
Dong-Yang Gao ◽  
Junju Du ◽  
Aigen Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Supernova Explosion ◽  
Spectroscopic Studies ◽  
Dark Spot ◽  
High Signal ◽  
Signal To Noise ◽  
Deep Minimum ◽  
Near Infrared Spectra

AbstractDuring October 2019 and March 2020, the luminous red supergiant Betelgeuse demonstrated an unusually deep minimum of its brightness. It became fainter by more than one magnitude and this is the most significant dimming observed in the recent decades. While the reason for the dimming is debated, pre-phase of supernova explosion, obscuring dust, or changes in the photosphere of the star were suggested scenarios. Here, we present spectroscopic studies of Betelgeuse using high-resolution and high signal-to-noise ratio near-infrared spectra obtained at Weihai Observatory on four epochs in 2020 covering the phases of during and after dimming. We show that the dimming episode is caused by the dropping of its effective temperature by at least 170 K on 2020 January 31, that can be attributed to the emergence of a large dark spot on the surface of the star.

A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

2020 ◽  
Vol 64 (1-4) ◽  
pp. 951-958
Author(s):  
Tianhao Liu ◽  
Yu Jin ◽  
Cuixiang Pei ◽  
Jie Han ◽  
Zhenmao Chen
Keyword(s):  
Power Plants ◽  
Signal To Noise Ratio ◽  
Small Diameter ◽  
Performance Testing ◽  
Guided Wave ◽  
High Signal ◽  
Receiver Coil ◽  
Signal To Noise ◽  
Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

Computationally Assisted Design of High Signal-to-Noise Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes

2020 ◽  
Author(s):  
Rishikesh Kulkarni ◽  
Anneliese Gest ◽  
Chun Kei Lam ◽  
Benjamin Raliski ◽  
Feroz James ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dft Calculations ◽  
Photoinduced Electron Transfer ◽  
Density Functional ◽  
Embryonic Stem ◽  
High Sensitivity ◽  
Md Simulations ◽  
High Signal ◽  
Signal To Noise ◽  
Green Fluorescent

<p>High signal-to-noise optical voltage indicators will enable simultaneous interrogation of membrane potential in large ensembles of neurons. However, design principles for voltage sensors with high sensitivity and brightness remain elusive, limiting the applicability of voltage imaging. In this paper, we use molecular dynamics (MD) simulations and density functional theory (DFT) calculations to guide the design of a bright and sensitive green-fluorescent voltage-sensitive fluorophore, or VoltageFluor (VF dye), that uses photoinduced electron transfer (PeT) as a voltage-sensing mechanism. MD simulations predict an 11% increase in sensitivity due to membrane orientation, while DFT calculations predict an increase in fluorescence quantum yield, but a decrease in sensitivity due to a decrease in rate of PeT. We confirm these predictions by synthesizing a new VF dye and demonstrating that it displays the expected improvements by doubling the brightness and retaining similar sensitivity to prior VF dyes. Combining theoretical predictions and experimental validation has resulted in the synthesis of the highest signal-to-noise green VF dye to date. We use this new voltage indicator to monitor the electrophysiological maturation of human embryonic stem cell-derived medium spiny neurons. </p>

A Systematic Review on Popularity, Application and Characteristics of Protein Secondary Structure Prediction Tools

2019 ◽  
Vol 16 (2) ◽  
pp. 159-172 ◽  
Author(s):  
Elaheh Kashani-Amin ◽  
Ozra Tabatabaei-Malazy ◽  
Amirhossein Sakhteman ◽  
Bagher Larijani ◽  
Azadeh Ebrahim-Habibi
Keyword(s):  
Systematic Review ◽  
Secondary Structure ◽  
Structure Prediction ◽  
Web Of Science ◽  
Secondary Structure Prediction ◽  
Structural Information ◽  
Protein Secondary Structure ◽  
Structural Features ◽  
Prediction Tools ◽  
Insight Into

Background: Prediction of proteins’ secondary structure is one of the major steps in the generation of homology models. These models provide structural information which is used to design suitable ligands for potential medicinal targets. However, selecting a proper tool between multiple Secondary Structure Prediction (SSP) options is challenging. The current study is an insight into currently favored methods and tools, within various contexts. Objective: A systematic review was performed for a comprehensive access to recent (2013-2016) studies which used or recommended protein SSP tools. Methods: Three databases, Web of Science, PubMed and Scopus were systematically searched and 99 out of the 209 studies were finally found eligible to extract data. Results: Four categories of applications for 59 retrieved SSP tools were: (I) prediction of structural features of a given sequence, (II) evaluation of a method, (III) providing input for a new SSP method and (IV) integrating an SSP tool as a component for a program. PSIPRED was found to be the most popular tool in all four categories. JPred and tools utilizing PHD (Profile network from HeiDelberg) method occupied second and third places of popularity in categories I and II. JPred was only found in the two first categories, while PHD was present in three fields. Conclusion: This study provides a comprehensive insight into the recent usage of SSP tools which could be helpful for selecting a proper tool.

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