Fourier-transform Spectra Research Articles

Genetic analyses of blood β-hydroxybutyrate predicted from milk infrared spectra and its association with longevity and female reproductive traits in Holstein cattle

Ketosis is one of the most prevalent and complex metabolic disorders in high-producing dairy cows and usually detected through analyses of β-hydroxybutyrate (BHB) concentration in blood. Our main objectives were to evaluate genetic parameters for blood BHB predicted based on Fourier-transform mid-infrared spectra from 5 to 305 d in milk, and estimate the genetic relationships of blood BHB with 7 reproduction traits and 6 longevity traits in Holstein cattle. Predicted blood BHB records of 11,609 Holstein cows (after quality control) were collected from 2016 to 2019 and used to derive 4 traits based on parity number, including predicted blood BHB in all parities (BHBp), parity 1 (BHB1), parity 2 (BHB2), and parity 3+ (BHB3). Single- and multitrait repeatability models were used for estimating genetic parameters for the 4 BHB traits. Random regression test-day models implemented via Bayesian inference were used to evaluate the daily genetic feature of BHB variability. In addition, genetic correlations were calculated for the 4 BHB traits with reproduction and longevity traits. The heritability estimates of BHBp, BHB1, BHB2, and BHB3 ranged from 0.100 ± 0.026 (± standard error) to 0.131 ± 0.023. The BHB in parities 1 to 3+ were highly genetically correlated and ranged from 0.788 (BHB1 and BHB2) to 0.911 (BHB1 and BHB3). The daily heritability of BHBp ranged from 0.069 to 0.195, higher for the early and lower for the later lactation periods. A similar trend was observed for BHB1, BHB2, and BHB3. There are low direct genetic correlations between BHBp and selected reproductive performance and longevity traits, which ranged from -0.168 ± 0.019 (BHBp and production life) to 0.157 ± 0.019 (BHBp and age at first calving) for the early lactation stage (5 to 65 d). These direct genetic correlations indicate that cows with higher BHBp (greater likelihood of having ketosis) in blood usually have shorter production life (-0.168 ± 0.019). Cows with higher fertility and postpartum recovery, such as younger age at first calving (0.157 ± 0.019) and shorter interval from calving to first insemination in heifer (0.111 ± 0.006), usually have lower BHB concentration in the blood. Furthermore, the direct genetic correlations change across parity and lactation stage. In general, our results suggest that selection for lower predicted BHB in early lactation could be an efficient strategy for reducing the incidence of ketosis as well as indirectly improving reproductive and longevity performance in Holstein cattle.

Revised Energy Levels of Atomic Lanthanum Considering Hyperfine Structure

Abstract The experimental wavenumbers of 2118 spectral lines from calibrated Fourier transform (FT) spectra have been used to determine revised energy values of 405 fine structure levels of atomic lanthanum, 264 levels of even and 141 levels of odd parity, respectively. For the determination of the level energies a weighted global fit of the center-of-gravity (cg) wavenumbers of all 2118 spectral lines has been done. All lines have been classified previously by different spectroscopic methods and by different authors. In order to achieve high accuracy, the hyperfine (hf) structure was taken into account when determining the cg wavenumbers from the FT spectra. The total uncertainty for all revised energy levels lies below 0.007 cm−1. A compilation of all revised energy levels along with their hf structure data is given, as well as a list of the spectral lines used in this investigation.

Room temperature HCHO oxidation over the Pt/CeO2 catalysts with different oxygen mobilities by changing ceria shapes

Oxygen mobility contributes to HCHO oxidation at room temperature. In this work, oxygen mobilities of the Pt/CeO2 catalysts were controlled by changing ceria shapes to nanorods (CeO2-R), nanocubes (CeO2-C) and nanoparticles (CeO2-P) for HCHO elimination. The smallest ceria crystallite size, the strongest metal-support interaction and the most oxygen vacancy in the Pt/CeO2-R catalyst than those in the Pt/CeO2-C and Pt/CeO2-P catalysts resulted in the greatest redox of surface lattice oxygen and the most oxygen molecules activation at oxygen vacancy sites. These contributed to the most active mobile oxygen and therefore the highest HCHO oxidation performance. In-situ diffused reflectance infrared Fourier-transform spectra (DRIFT) indicated the fastest decomposition of formate at Pt-CeO2 interface on the Pt/CeO2-R catalyst because of its highest oxygen mobility. This work illustrated importance of oxygen mobility for efficient HCHO oxidation.

Intermetallic PdZn nanoparticles catalyze the continuous-flow hydrogenation of alkynols to cis-enols

Designing highly active and stable lead-free palladium-based catalysts without introducing surfactants and stabilizers is vital for large-scale and high-efficiency manufacturing of cis-enols via continuous-flow semi-hydrogenation of alkynols. Herein, we report an intermetallic PdZn/ZnO catalyst, designed by using the coupling strategy of strong electrostatic adsorption and reactive metal-support interaction, which can be used as a credible alternative to the commercial PdAg/Al2O3 and Lindlar catalysts. Intermetallic PdZn nanoparticles with electron-poor active sites on a Pd/ZnO catalyst significantly boost the thermodynamic selectivity with respect to the mechanistic selectivity and therefore enhance the selectivity towards cis-enols. Based on in situ diffuse reflectance infrared Fourier-transform spectra as well as simulations, we identify that the preferential adsorption of alkynol over enol on PdZn nanoparticles suppresses the over-hydrogenation of enols. These results suggest the application of fine surface engineering technology in oxide-supported metal (particles) could tune the ensemble and ligand effects of metallic active sites and achieve directional hydrogenation in fine chemical synthesis.

Magnetocatalysis: The Interplay between the Magnetic Field and Electrocatalysis

Magnetocatalysis: The Interplay between the Magnetic Field and Electrocatalysis

Fabry Perot Cavity Length Demodulation Method Based on Continuous Thinning Algorithm of Fast Fourier Transform Spectrum

Optical fiber Fabry Perot sensors are widely used in industrial production and life. It is of great significance to improve the performance of sensor demodulation algorithm. Based on the analysis of the principle and error source of the cavity length demodulated by the Fast Fourier Transform (FFT) algorithm, the FFT-FT algorithm with continuous refinement of FFT spectrum is introduced. By using the feature that FFT-FT algorithm can refine at the peak of discrete spectrum, the length of F-P cavity demodulated by FFT algorithm is optimized to improve the accuracy of the demodulation. Through simulation experiments, the F-P cavity length of FFT demodulation algorithm and FFT-FT demodulation algorithm under the same light source signal are compared and analyzed, and the goodness of fit of the fitting curve of continuous demodulation is analyzed. The simulation results show that the error of FFT demodulation algorithm is more than 100 times that of FFT-FT algorithm when it is refined 100 times near the peak value of FFT discrete spectrum. The goodness of fit of the demodulation fitting curve calculated by FFT-FT algorithm is more than 2 times that of FFT algorithm, which proves that the improved algorithm demodulation F-P cavity length value has better consistency with the real value.

Evaluation of nature and intensity of fire concrete spalling by frequency analysis of sound records

The paper presents a new method for identifying the form and intensity of spalling using an analysis of the acoustic signal emitted by concrete. To assess the intensity and monitor the course of concrete spalling during fire exposure, the analysis of the recorded sound from the furnace chamber is used. The spalling intensity was determined based on signal amplitude analysis. Investigation of sound records showed that the character of spalling can be categorized by a well-defined frequency value. Based on the analysis of the Fast Fourier Transform (FFT) spectrum, the authors have distinguished the following phenomena that are the source of the signal by assigning the corresponding frequency of the sound wave vibration: explosive spalling, aggregate spalling and destructive spalling.

Characterization of line mixing effects in the 11101←00001 band of carbon dioxide for pressures up to 19 atm

Fourier-transform spectra of room-temperature carbon dioxide compressed to pressures up to 19 atm reported previously are re-analyzed to obtain weak line-mixing parameters and a representation of full line mixing for transitions observed in the P- and Q-branches of the 11101 ← 00001 (Π ← Σ) band centered at 2076.86 cm−1. Similar analyses for the R-branch transitions are prevented by strong Coriolis resonances that nearly completely transfer the intensities of R-branch transitions to the P-branch. The weak line mixing coefficients are retrieved experimentally and are modeled using the Exponential Power Gap scaling law. Another modeling is performed with an Energy-Corrected-Sudden type approach making use of a symmetric relaxation matrix satisfying all basic relations. Comparisons of experimental and calculated parameters with results available in the literature are presented and discussed.

Discovery of new even-parity fine structure levels of Pr I with angular momenta 1/2, 3/2, and 5/2

The spectrum of Praseodymium was investigated in the visible region from 4000 Å to 7500 Å based on previously recorded Fourier Transform spectra. Source of free Pr atoms was a hollow cathode discharge lamp. The investigation of spectral lines was performed using laser-induced fluorescence spectroscopy. A tunable single mode ring-dye laser, pumped by a frequency doubled Nd-YAG laser, was used as the light source to investigate selected lines. Hyperfine spectra of 129 lines were recorded and the magnetic dipole hyperfine structure constants of the involved energy levels were determined. This led to the discovery of up to now unknown levels. In this paper, 30 even parity levels, having J-values of 1/2, 3/2, and 5/2 are presented. The existence of all levels is confirmed by several laser excitations in the spectral range of our dye laser.

Window function for chirped pulse spectroscopy with enhanced signal-to-noise ratio and lineshape correction

In chirped pulse experiments, magnitude Fourier transform is used to generate frequency domain spectra. The application of window function as a tool for lineshape correction and signal-to-noise ratio (SnR) enhancement is rarely discussed in chirped spectroscopy, with the only exception of using Kaiser-Bessel window and trivial rectangular window. We present a specific window function, called “Voigt-1D” window, designed for chirped pulse spectroscopy. The window function corrects the magnitude Fourier-transform spectra to Voigt lineshape, and offers wide tunability to control the SnR and lineshape of the final spectral lines. We derived the mathematical properties of the window function, and evaluated the performance of the window function in comparison to the Kaiser-Bessel window on experimental and simulated data sets. Our result shows that, compared with un-windowed spectra, the Voigt-1D window is able to produce 100% SnR enhancement on average.

New Ritz Wavelengths and Transition Probabilities of Parity-forbidden [Mn II] Lines of Astrophysical Interest.

We report a comprehensive list of accurate Ritz wavelengths and calculated transition probabilities for parity-forbidden [Mn II] lines. Ritz wavelengths have been derived from experimentally established energy level values resulting from an extensive analysis of a high-resolution Fourier-transform emission spectrum of singly ionized manganese. Our analysis includes transitions between all known metastable and other long-lived levels of Mn II giving a total of 1130 [Mn II] Ritz wavelengths. Our entire list of derived Ritz wavelengths for [Mn II] lines ranges between 237 nm and 170 μm (42,125-58 cm-1). The accurate Ritz wavelengths and calculated transition probabilities for forbidden lines in this paper are useful in the study and diagnostics of nebulae and other low-density astrophysical plasmas.

Mechanisms of Caromatic-C bonds cleavage in lignin over NbOx-supported Ru catalyst

Efficient and selective cleavage of Caromatic-C linkages in lignin to enhance the productivity of monocyclic aromatic hydrocarbons is an extremely challenging and attractive task. Previously, we reported a Ru/NbOPO4 catalyst that realized the catalytic cleavage of both interunit C-C and C-O bonds in one-pot lignin conversions [Chem, 2019, 5, 1521–1536]. However, the roles of NbOx species in the selective Caromatic-C cleavage are not clear and need to be extensively studied. Herein, we focus on the exploration of the catalytic mechanisms of Caromatic-C bond cleavage over NbOx-supported Ru catalyst, by comparing with those of Ru/TiO2, Ru/ZrO2, and Ru/Al2O3 catalysts. It shows that the Ru/Nb2O5 catalyst exhibits high activity and remarkable selectivity to monocyclic hydrocarbons. A combined diffuse reflectance infrared Fourier Transform spectra (DRIFTS) and density functional theory (DFT) calculation analysis unambiguously confirmed that (i) NbOx not only can strongly adsorb phenylcyclohexane via benzene ring, but also selectively activate Caromatic-C bond between benzene ring and cyclohexane; (ii) NbOx can promote the protonation of phenylcyclohexane with the assistance of H3PO4; and (iii) NbOx can significantly reduce the barrier of Caromatic-C bonds cleavage of the carbocation intermediate (C6H5(H)C6H11+). A detail underlying mechanism has been established, which would have further implications to promote the design of new, high efficient catalysts.

The Spectrum and Term Analysis of Singly Ionized Manganese

Abstract An extensive analysis of the Mn spectrum was carried out using high-resolution Fourier transform (FT) and grating spectroscopy of Mn–Ne and Mn–Ar hollow cathode discharge sources, over the range 82–5500 nm (1820–121,728 cm−1). Spectral wavelengths for a total of 6019 Mn ii lines have been measured, of which 1345 are obtained through FT spectroscopy. These wavelengths are given to at least an order of magnitude lower uncertainty than previous measurements. These lines were used to identify 6256 Mn ii transitions and improve the values of 505 previously published energy levels with typical uncertainties of a few thousandths of a cm−1, representing an order-of-magnitude reduction in uncertainty. We have verified and improved an additional 57 Mn ii energy levels, previously established through observation of stellar spectra alone, using our FT spectra. In addition, 52 new energy level values have been established. The number of classified lines reported is approximately 50% more than previously published. The new accurate data for 614 energy levels and 6019 lines will allow a more reliable analysis of Mn ii spectral lines in astrophysical spectra.

Stability diagrams of two optically mutual-injected quantum cascade lasers

The dynamic properties and stability of optically mutual-injected arrays composed of terahertz quantum cascade lasers (THz QCLs) were investigated and compared with those of diode laser (DL) arrays. The influences of the coupling strength and frequency detuning on the working states of the arrays were analyzed using numerical simulations of the time evolutions of the electric fields and their corresponding Fourier-transform spectra. It was found that when the frequency detuning between individual lasers was zero, the QCL arrays could always maintain phase-locked operation. In contrast, the DLs were only able to function in a stable state with weak coupling strengths. With increasing coupling strength, periodic, quasi-periodic, multi-periodic, and aperiodic oscillations appeared. When the frequency detuning of the array lasers was nonzero, the QCL array could not be phase-locked at low coupling strengths, and it only entered the phase-locked region if the coupling strength was increased. However, the DL array could only work stably at low coupling strengths and quickly entered the aperiodic oscillation region as the coupling strength was increased. When we fixed the coupling strength and changed the frequency detuning, with large frequency detunings, both the QCL and DL arrays exhibited periodic oscillations. However, the QCLs were phase-locked at low frequency detunings, while the DLs exhibited periodic and multi-periodic oscillations across a broader frequency range. The results indicate that QCL arrays are more stable than DL arrays across a wide range of coupling strengths and frequency detuning parameters.

Ripple period adjustment on SiC surface based on electron dynamics control and its polarization anisotropy

In this paper, the Mach Zehnder interferometer is utilized to generate a collinear dual optical path with 800-nm center wavelength, 1 kHz repetition rate, 120-fs pulse duration and an energy ratio of 1:1 to scan 6H-SiC crystal at a scanning speed of 500 μm/s, resulting in laser-induced periodic surface structure (LIPSS). From the perspective of instantaneous electron density level, variation of the period of low spatial frequency LIPSS (LSFL) with interpulse delay time and polarization angle is studied. The scanning electron microscope (SEM) characterization of the line-scanned ablation zone combined with fast Fourier transformation (FFT) spectrum analysis shows that the period of LSFL decreases with the increase of delay time, and remains stable when the delay exceeds 240 fs. Meanwhile, the period of LSFL increases with the increase of polarization angle under the same delay time, showing an anisotropy that dependent on the polarization angle. The variation trend of the maximum electron density level with delay time calculated by electron rate equation is roughly consistent with the periodic variation trend. Interaction between incident light and transient metal-like SiC surface is simulated based on finite-difference time-domain method (FDTD). The simulation results show that the surface of the sample has a periodic light field enhancement structure controlled by the transient electron density, which explains the phenomenon that the period decreases with increasing delay time. It is further confirmed that the formation of LSFL is due to the interference of incident light and surface plasmon, and the period of LSFL can be controlled by adjusting the electron density level by delay time. The periodic polarization dependence of LSFL may be related to the relative orientation change of the laser pulse front tilt (PFT) and laser polarization.

Health Analysis of Transformer Winding Insulation Through Thermal Monitoring and Fast Fourier Transform (FFT) Power Spectrum

This paper presents a health analysis technique for transformer winding insulation through thermal monitoring and Fast Fourier Transform (FFT) power spectrum. A novel thermal model for the Kraft paper insulation of transformer is proposed by using the transformer’s top-oil and winding hot-spot temperature models. The relationship between the temperature rise of oil inside the transformer tank and the winding insulation degradation are considered by utilizing the data-sets and daily load cycles of a 10/13 MVA, 132/11 kV, 50 Hz, ONAF grid power transformer. The model based on IEEE Guide for loading mineral-oil-immersed transformers is developed in Simulink. The hotspot temperature rise from the thermal model is used as a reference to analyze the winding insulation degradation in the form of high frequency partial discharges (PDs) upon the output parameters of the transformer. Using data analysis techniques, a correlation is presented between the load cycles and the hot-spot temperature through which the health status of the transformer winding insulation is estimated. Moreover, the high frequency transients were detected using the Fast Fourier Transform (FFT) spectrum analyzer tool in MATLAB. The preliminary study shows that high frequency PDs are detected for the overheated and deteriorated state of the winding insulation. The results show that the proposed technique is feasible for the health analysis of power transformers and successfully predicted the deterioration of the transformer winding insulation.

A New Modulation Recognition Method Based on Flying Fish Swarm Algorithm

The modulation recognition method based on deep learning plays a significant role in the intelligent communication system. To further improve the recognition rate, especially in the case of small samples with a low signal-to-noise ratio, this paper proposes a new modulation recognition method based on flying fish swarm algorithm. First, Short-Time Fourier Transform, Choi-Williams Distribution, and Cyclic Spectrum are combined to complete multi-channel signal processing. Second, AlexNet, VGGNet, GoogLeNet, and ResNet are transferred to realize feature extraction. Third, the support vector machine classifies the modulations after dimension reduction and feature fusion. Finally, the flying fish swarm is proposed to optimize the signal processing methods, the types of networks, the layers of networks, the dimensions of features, and the parameters of the support vector machine. The method can accurately recognize BPSK, QPSK, OQPSK, 8PSK, 4ASK, QAM16, QAM32, and QAM64. The simulation results show that the average recognition rate of modulation is 94.5% at SNR of 0 dB and 84.7% at SNR of −4 dB. Besides, the proposed modulation recognition method possesses good robustness under low SNR conditions.

Accuracy analysis of GNSS-IR snow depth inversion algorithms

In recent years, with the continuous development of Global Navigation Satellite System (GNSS), it has been applied not only to navigation and positioning, but also to Earth surface environment monitoring. At present, when performing GNSS-IR (GNSS Interferometric Reflectometry) snow depth inversion, Lomb-Scargle Periodogram (LSP) spectrum analysis is mainly used to calculate the vertical height from the antenna phase center to the reflection surface. However, it has the problem of low identification of power spectrum analysis, which may lead to frequency leakage. Therefore, Fast Fourier Transform (FFT) spectrum analysis and Nonlinear Least Square Fitting (NLSF) are introduced to calculate the vertical height in this paper. The GNSS-IR snow depth inversion experiment is carried out by using the observation data of P351 station in PBO (Plate Boundary Observatory) network of the United States from 2013 to 2016. Three algorithms are used to invert the snow depth and compared with the actual snow depth provided by the station 490 in the SNOTEL network. The observations data of L1 and L2 bands are respectively used to find the optimal combination between different algorithms further to improve the accuracy of GNSS-IR snow depth inversion. For L1 band, different snow depths correspond to different optimal algorithms. When the snow depth is less than 0.8 m, the inversion accuracy of NLSF algorithm is the highest. When the snow depth is greater than 0.8 m, the inversion accuracy of FFT algorithm is higher. Therefore, according to the different snow depth, a combined algorithm of NLSF + FFT is proposed for GNSS-IR snow depth inversion. Compared with the traditional LSP algorithm, the inversion accuracy of the combined algorithm is improved by 10%. For L2 band data, the results show that the accuracy of snow depth inversion of various algorithms do not change with the variations of snow depth. Among the three single algorithms, the inversion accuracy of FFT algorithm is better than that of LSP and NLSF algorithms.

Rotational Temperature of AlO Molecule from Fourier Transform Spectrum of the 0-1 band of B2∑+ - X2∑+ System

Rotational structure of (0-1) bands of the B2∑+ - X2∑+ system of AlO molecule was recorded on Fourier Transform Spectrometer. Intensity distribution among the well-resolved rotational lines of R1 and R2 for each band was recorded and average rotational temperature calculated from these lines which is 1813 K.

Comparative study of Co3O4-ZSM-5 catalysts synthesized by different hydrothermal methods for the catalytic oxidation of dichloromethane

In this work, various Co3O4-ZSM-5 catalysts were prepared by the microwave hydrothermal method (MH-Co3O4@ZSM-5), dynamic hydrothermal method (DH-Co3O4@ZSM-5), and conventional hydrothermal method (CH-Co3O4/ZSM-5). Their catalytic oxidation of dichloromethane (DCM) was analyzed. Detailed characterizations such as X-ray diffractometer (XRD), scanning microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), H2 temperature-programmed reduction (H2-TPR), temperature-programmed desorption of O2 (O2-TPD), temperature-programmed desorption of NH3 (NH3-TPD), diffuse reflectance infrared Fourier-transform spectra with NH3 molecules (NH3-DRIFT), and temperature-programmed surface reaction (TPSR) were performed. Results showed that with the assistance of microwave, MH-Co3O4@ZSM-5 formed a uniform core-shell structure, while the other two samples did not. MH-Co3O4@ZSM-5 possessed rich surface adsorbed oxygen species, higher ratio of Co3+/Co2+, strong acidity, high reducibility, and oxygen mobility among the three Co3O4-ZSM-5 catalysts, which was beneficial for the improvement of DCM oxidation. In the oxidation of dichloromethane, MH-Co3O4@ZSM-5 presented the best activity and mineralization, which was consistent with the characterizations results. Meanwhile, according to the TPSR test, HCl or Cl2 removal from the catalyst surface was also promoted in MH-Co3O4@ZSM-5 by their abundant Brønsted acid sites and the promotion of Deacon reaction by Co3O4 or the synergistic effect of Co3O4 and ZSM-5. According to the results of in situ DRIFT studies, a possible reaction pathway of DCM oxidation was proposed over the MH-Co3O4@ZSM-5 catalysts.