Peak Parameters Research Articles

Temperature dependence of the viscoelastic properties of a natural gastropod mucus by Brillouin light scattering spectroscopy.

Brillouin spectroscopy was used to probe the viscoelastic properties of a natural gastropod mucus at GHz frequencies over the range -11 °C ≤ T ≤ 52 °C. Anomalies in the temperature dependence of mucus longitudinal acoustic mode peak parameters and associated viscoelastic properties at T = -2.5 °C, together with the appearance of a peak due to ice at this temperature, suggest that the mucus undergoes a phase transition from a viscous liquid state to one in which liquid mucus and solid ice phases coexist. Failure of this transition to proceed to completion even at -11 °C is attributed to glycoprotein-water interaction. The temperature dependence of the viscoelastic properties and the phase behaviour suggest that water molecules bind to glycoprotein at a temperature above the onset of freezing and that the reduced ability of this bound water to take on a configuration that facilitates freezing is responsible for the observed freezing point depression and gradual nature of the liquid-solid transition.

Statistical validation of ionospheric electron density profiles retrievals from GOES geosynchronous satellites

In this paper, we discuss a novel retrieval of ionospheric electron density profiles using the Radio Occultation (RO) technique applied to measurements captured by the Global Positioning System (GPS) receivers onboard two Geostationary Operational Environmental Satellites (GOES). The GOES satellites operate at ~35,800 km altitude and are primarily weather satellites that operationally contribute continuous remote-sensing data for real-time weather forecasting, as well as near-Earth environment monitoring and Sun observations. The GPS receivers onboard GOES-16 and GOES-17 satellites can track GPS signals propagated through the Earth’s atmosphere, and although the receivers are primarily designed for navigation and station-keeping maneuvers, these GPS measurements that traverse the Earth’s atmosphere can be used to retrieve the ionospheric electron density profiles. This process poses a range of technical challenges. GOES RO links are different from the traditional low Earth orbit (LEO) RO geometry since the receiver is located in an orbit that is higher in altitude than the GPS constellation of transmitters. Additionally, the GPS receivers onboard GOES satellites provide only single-frequency GPS L1 observations and have clocks much less stable than those typically used for RO measurements. The geographical distribution of the retrieved GEO-based RO profiles was found to be uniquely constrained and repeatable based on the relative geostationary fixed positions in the Earth-Centered Earth Fixed reference frame with respect to the GPS constellation orbiting at lower altitude, and significantly different from the coverage patterns of LEO-based RO missions. We demonstrate the successful application of the proposed RO profiling technique with a statistically significant set of GPS observations from GOES-16 and GOES-17 satellites over several years of data collection. This enabled us to retrieve more than 10,000 ionospheric electron density profiles with a maximum altitude of up to 1000–2000 km, much higher than any existing LEO-based RO mission. We demonstrate good performance of GEO-based RO measurements for properly specifying the vertical distribution of ionospheric plasma density by comparing the profiles dataset from the GOES RO experiment with independent reference observations – ground-based ionosondes and LEO-based RO missions, as well as model simulation results provided by the empirical International Reference Ionosphere model. Over multiple years of observations, statistical analysis of discrepancies between the ionospheric F2 layer peak parameters (peak density and height) derived from geosynchronous GOES observations and reference measurements was conducted. This analysis reveals a very good agreement between GOES RO electron density profiles and independent types of measurements in both the F2 peak and the profile shape.

Influence of structural-geometric features on seismic vulnerability of masonry buildings based on post-earthquake damage data

In this study, seismic vulnerability of Italian masonry buildings is analyzed taking advantage of the post-earthquake damage data recently released by the Italian Department of Civil Protection through the online platform Da.D.O. (Dolce et al. 2019).The main purpose of the study is to describe the damage attitude of several building's typologies, univocally defined by means of structural and geometrical features. To this aim, a time-consuming data processing has been performed to obtain a more effective taxonomy, based on masonry quality layout, type of horizontal structure, presence/absence of retrofit interventions, construction age and number of storeys.Moreover, to avoid bias in vulnerability analysis, the most reliable datasets has been detected through a comprehensive data analysis, also integrating the original database with census data. Then, damage analysis has been done, converting the damage observed on vertical structures in 5+1 damage levels of the whole building according to the European Macroseismic Scale classification. ShakeMaps in terms of peak parameters released by National Institute of Geophysics and Volcanology are also considered to characterize ground motion shaking at each building's location. Lastly, a lognormal statistical model has been used to derive vulnerability curves for considered typologies, fully investigating the influence of each building's feature on damage attitude.

Kinetic Study of Hydrolytic degradation of Rivaroxaban by HPTLC

The main objective of a research involved kinetic study of hydrolytic degradation of Rivaroxaban and validation of stability indicating HPTLC Method for estimation of rivaroxaban as per ICH guidelines.The chromatographic separation was carried on Merck TLC aluminium sheets of silica gel 60 F254 (10×10cm) with mobile phase of Acetonitrile: Ethyl acetate (3:7 v/v) with densitometric scanning at 249nm. Acceptable peak parameters were obtained at the retardation factor of about 0.75±0.02. The proposed method was validated according to ICH guidelines. The results were acceptable for linearity and range, accuracy, precision, robustness, detection limit and quantitation limit. During stress degradation study, it was observed that the rivaroxaban is more sensitive to hydrolytic conditions. Degradation product peak was well resolved when the sample exposed to alkali catalysed hydrolysis for 72 hrs. was spotted on TLC plate and studied by the developed method. Such a product peak was not observed at 48 hrs. exposure, though there was reduction in drug peak area. This prompted us to study degradation kinetics under alkaline hydrolytic conditions, and the results of the degradation kinetic study indicates that the reaction follows first order kinetics. Interestingly there was no product peak under acidic hydrolytic condition. Results of thermal, oxidative and photolytic degradation studies show reduction in drug peak area.The developed method describes simple, sensitive, and specific stability indicating HPTLC method for estimation of rivaroxaban. This optimised method can be considered as good alternative for routine analysis of the rivaroxaban stability.

Shaped beam from multiple beams using planar phased arrays

ABSTRACT This paper proposes a synthesis and optimization procedure to generate user-specific shaped and multiple beams in any arbitrary 3D space. The synthesis method generates independently controllable multiple beams over different azimuth and elevation angles with variable peak powers. These multiple beams can form any user-defined shaped pattern with an optimum number of beams, their power, and placement in the angles using the proposed direct synthesis method. Different evolutionary algorithms are employed to optimize the beam peak parameters to mitigate the ripple, side lobe level, and beam spread. The synthesis method is validated on a fully functional integrated 5G mmWave phased array for various shaped beam patterns. Measured sector, isoflex beams between , , and dual beams with unequal powers are presented and compared with the shaped beam synthesis method.

Deconvolution of 1D NMR spectra: A deep learning-based approach

The analysis of nuclear magnetic resonance (NMR) spectra to detect peaks and characterize their parameters, often referred to as deconvolution, is a crucial step in the quantification, elucidation, and verification of the structure of molecular systems. However, deconvolution of 1D NMR spectra is a challenge for both experts and machines. We propose a robust, expert-level quality deep learning-based deconvolution algorithm for 1D experimental NMR spectra. The algorithm is based on a neural network trained on synthetic spectra. Our customized pre-processing and labeling of the synthetic spectra enable the estimation of critical peak parameters. Furthermore, the neural network model transfers well to the experimental spectra and demonstrates low fitting errors and sparse peak lists in challenging scenarios such as crowded, high dynamic range, shoulder peak regions as well as broad peaks. We demonstrate in challenging spectra that the proposed algorithm is superior to expert results.

Analysis of wear of a nitrided AISI H13 hot work tool steel in an aluminium hot extrusion process

The present work present experimental results of hot wear testing of AISI H13 tool steel with the aim of replicating the wear mechanisms occurring during hot extrusion process. The hot wear tests were carried out at a temperature of 550 °C and a sliding speed of 0.5 m/s for sliding distances of 1800, 3600 and 5400 m. A pin-on-disk test fixture was designed and fabricated to investigate the sliding between nitrided AISI H13 steel pins and 6063 aluminium alloy disks in a "flat surface-flat surface" conformal contact mode. The different characterisation techniques used (SEM/EDS, XRD) helped to better explain the complex wear mechanisms leading to surface degradation in the tribological couple. Graphitisation phenomenon caused by the dissolution of metastable iron carbide Fe3C was observed to occur after a sliding distance of 3600 m. In addition, coarsening, coalescence and tearing of carbides in the ultimate lower valleys of the degraded surface were observed to occur after 5400 m sliding distance. Nano-indentation technique was used to evaluate the cross-sectional hardness evolution of the nitrided layer, and results showed that the maximum value of hardness of 12.01 ± 0.63 GPa was obtained at the nearest point of the surface. Volume and surface parameters were used to characterise the surfaces before and after wear damage as function of sliding distance. The progressive variation and evolution of the peak material volume parameter (Vmp), core material volume (Vmc), core void volume (Vvc) and dale void volume (Vvv) parameters reached higher values after wear testing at 3600 m sliding distance indicating a synergy between different and complex wear mechanisms.

An ultra-precise fast fourier transform

<h2>Abstract</h2> The Fast Fourier Transform (FFT) is a cornerstone of digital signal processing, generating a computationally efficient estimate of the frequency content of a time series. Its limitations include: (1) information is only provided at discrete frequency steps, so further calculation, for example interpolation, is often used to obtain improved estimates of peak frequencies and amplitudes; (2) ‘energy' from spectral peaks may ‘leak' into adjacent frequencies, potentially causing lower amplitude peaks to be distorted or hidden; (3) the FFT, like many other DSP algorithms, is a discrete time approximation of continuous time mathematics. This paper describes a new FFT calculation which uses two windowing functions, derived from Prism Signal Processing. Separate FFT results are obtained from each windowing function applied to the data set. Calculations based on the two FFT results yields high precision estimates of spectral peak location (frequency), amplitude and phase. This technique addresses FFT limitations as follows: (1) spectral peak parameters are calculated directly, unrestricted by FFT frequency step discretization; (2) the windowing functions have narrowband characteristics which attenuate and localize spectral leakage; (3) the windowing functions incorporate a Romberg Integration mechanism to overcome the discrete/continuous time approximation.

Role of S/Se replacement on the structure of Ge20Se80-xSx glasses

The effect of S-content on the medium-and short-range order structure of Ge20Se80−xSxleft(x=0,15,30 mathrm {at}%right), has been investigated by using high-energy X-ray diffraction. Medium-range order changes, as illustrated by the parameters of the first sharp diffraction peak, were discussed in the light of the microcrystalline model. The short-range order parameters have been obtained by the analysis of the first two peaks in the curve of the total radial distribution function. The current results indicate that S-atoms enter the host network of the stiffness composition (Ge20Se80) as compensation of Se-atoms.

Investigation of phosphate glass activated with terbium oxide as beta dosimeter

• A new composition of phosphate glass doped with terbium oxides (Tb) was prepared. • Many Analyses such as XRD, HRTEM, SEM and EDX of the prepared samples were done. • The activity energies and the trapping parameters of the glow peaks were studied. • A linear behavior of the dose–response was displayed in the β-doses up to 275 Gy. • Increasing in the sensitivity of phosphate glass for β-radiation with dopant of (Tb). In the current work, a new composition of phosphate glass doped with terbium oxides (Tb 2 O 3 ) was prepared using the melting quenching method. The prepared glasses had been characterized through XRD analysis, FTIR spectra, and thermoluminescence (TL) properties. The TL results revealed that the doping of phosphate glass with 0.5 % Tb increases the sensitivity of phosphate glass for beta radiation by about 562.95 times, compared to undoped phosphate glass. The deconvolution process displayed the composition of the resultant glow curves to seven and eight overlapped peaks for the undoped and doped samples. The activation energies and the trapping parameters of the glow peaks were studied using different methods. A linear behaviour of the dose–response without saturation in the β - dose range was displayed from 0.22 up to 275 Gy.

Analysis of the Stress Wave Characteristic Parameter of Cascode GaN HEMT

Mechanical stress wave characteristic parameters are important for analyzing the health of power devices and are the basis of power cycling experiments to establish the connection between the device’s health status and its mechanical stress wave. Based on acoustic emission detection technology, this article analyzes the generation principle of the mechanical stress wave in cascode gallium nitride (GaN) HEMT first and then designs repeatability tests to analyze the stress wave characteristics at different locations of the device and the variation law of stress wave characteristic parameters. We found that the stress wave acoustic emission source is at the bottom middle of the device. Stress waves in the 60–90 and 150–180 kHz frequency bands are generated when the device is turned on or off. It is positively correlated with the drain–source voltage and has a good peak parameter fitting curve on the package surface, while the stress wave has no relationship with the gate–source voltage.

A global evaluation of the JONSWAP spectra suitability on coastal areas

Wave spectra provide comprehensive information on wave energy for different directions and frequencies. Integrated sea state parameters, however, are more commonly used for wave climate characterization. Many engineering applications estimate spectral conditions from these parameters using theoretical spectra. One of the theoretical spectra of widest practical use is the JONSWAP. Here, the wave spectra for the hindcasted 30 years covering coastal areas worldwide are studied. We first compare the simulated historical spectra against measurements from 39 buoys. Several approaches are raised in order to provide different information, such as a directional and frequency distribution and climate evaluation. The suitability of the JONSWAP spectrum is then analysed by exploring the best fit of the peak-enhancement factor from hourly sea states. Results show a peak-enhancement factor below 2.4, lower than the standard JONSWAP (i.e a value of 3.3), in most coastal areas and especially in the east coast of the continents, even for energetic hourly sea states. Tropical areas on the west coasts provide values close to the standard JONSWAP. Seasonal and inter-annual variations in the peak parameter are also investigated.

Simultaneous determination of anthracene and phenanthrene using a poly-alizarin red S/carbon paste electrode

A polymer-based carbon paste electrode was constructed by electropolymerized Alizarin Red S (ARS) film on the carbon paste electrode (CPE) surface. The electrochemical properties of poly-ARS/CPE were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was utilized for electrode characterization. The electropolymerization cycles for the construction of the sensor and the supporting electrolyte were optimized. With 0.1 M LiClO4 as a supporting electrolyte, poly-ARS/CPE was able to generate oxidation peaks for anthracene (ANT) and phenanthrene (PHE), that were clearly defined and easily distinguished from one to another when operating in square wave voltammetry (SWV). In the simultaneous detection the linear ranges of ANT and PHE were within 80–1000 μM, with detection limits of 24 μM. The variation of peak parameters with scan rate was investigated to determine the nature of electrooxidation and the number of electrons involved in the electrode process. Poly-ARS/CPE was successfully utilized for the detection of ANT and PHE in different water samples and the obtained results suggested the selectivity, stability and reproducibility of the modified electrode.

Analysis for Predictors of Failure of Orthodontic Mini-implant Using Patient-Specific Finite Element Models.

In this study, we analyzed the clinical factors and mechanical parameters for predicting orthodontic mini-implant (OMI) failure in the mandible, which has different properties from the maxilla. A patient-specific finite element analysis was applied to 32 OMIs (6 failures and 26 successes) implanted between the mandibular second premolars and first molars used for anchorage. The peak stress and strain parameters were calculated for each sample. A logistic regression of the failure (vs. success) of OMIs on the mechanical parameters in the models was conducted. In addition, the influence of clinical factors on the mechanical parameters considered to be related to OMI failure was examined by a regression analysis. The mechanical parameter which best predicts OMI failure in the mandible was found to be a minimum principal strain of between 0.5 to 1.0mm from the OMI surface (R2 = 0.8033). The results indicate the patient's bone density, distance between the OMIs and adjacent root, and vertical implantation angle of the OMIs are potential clinical predictors of OMI failure in the mandible.

A graphene-based THz metasurface sensor with air-spaced structure

Owing to the unique electromagnetic response ability, electromagnetic metasurface have potential applications in medical, imaging, sensing, and other fields. In this paper, a graphene-based THz metasurface sensor with an air spacer layer is designed by combining the advantages of the air spacer structure and the dynamic tunability of graphene materials. The proposed metasurface sensor consists of six layers, which are silicon dioxide (SiO2) substrate, metal reflector, air layer, graphene metasurface etched with microstructure, ion-gel layer and silicon dioxide dielectric layer from bottom to top. A comprehensive study of the absorption properties and sensing performance are carried out which is simulated and analyzed with the help of CST Microwave Studio software. The calculation results show that the two obvious resonance absorption peaks located at 0.95 THz and 1.53 THz with absorption of 94.9% and 79%, respectively, and there is a good linear relationship between the absorption peak and dielectric parameters of analyte. The frequency shift sensitivity of the two resonance peaks M1 and M2 can reach 450 GHz/RIU and 717 GHz/RIU, respectively. By changing the thickness of the air layer, when the two resonance peaks M1 and M2 reach the maximum absorption at h2=140 μm and h2=280 μm, respectively, the frequency shift sensitivity is still as high as close to 450 GHz/RIU. The influence of structure parameters and incident angle on the absorption spectrum shows that the proposed structure has good stability and reliability. The proposed graphene-based absorption sensor has good biocompatibility, broadening the application range of terahertz functional devices.

Cardiopulmonary Exercise Testing Characterizes Silent Cardiovascular Abnormalities in Asymptomatic Pediatric Cancer Survivors.

Late-onset cardiovascular complications are serious concerns for pediatric cancer survivors (PCS) including those who are asymptomatic. We investigated whether cardiopulmonary exercise testing (CPET) can delineate the underlying pathophysiology of preclinical cardiovascular abnormalities in PCS. We examined CPET data via cycle ergometer in asymptomatic PCS with normal echocardiogram and age-matched controls. Peak and submaximal parameters were analyzed. Fifty-three PCS and 60 controls were studied. Peak oxygen consumption (VO2), peak work rate (WR), and ventilatory anaerobic threshold (VAT) were significantly lower in PCS than controls (1.86 ± 0.53 vs. 2.23 ± 0.61 L/min, 125 ± 45 vs. 154 ± 46W, and 1.20 ± 0.35 vs. 1.42 ± 0.43 L/min, respectively; all p < 0.01), whereas peak heart rate (HR) and ventilatory efficiency (a slope of minute ventilation over CO2 production or ∆VE/∆VCO2) were comparable. Peak respiratory exchange ratio (RER) was significantly higher in PCS (p = 0.0006). Stroke volume (SV) reserve was decreased in PCS, indicated by simultaneous higher dependency on HR (higher ∆HR/∆WR) and lower peak oxygen pulse (OP). Twelve PCS with high peak RER (≥ 1.3) revealed lower pVO2 and VAT than the rest of PCS despite higher ventilatory efficiency (lower ∆VE/∆VCO2), suggesting fundamental deficiency in oxygen utilization in some PCS. Poor exercise performance in PCS may be mainly attributed to limited stroke volume reserve, but the underlying pathophysiology is multifactorial. Combined assessment of peak and submaximal CPET parameters provided critical information in delineating underlying exercise physiology of PCS.

Comprehensive detection of analytes in large chromatographic datasets by coupling factor analysis with a decision tree

Abstract. Environmental samples typically contain hundreds or thousands of unique organic compounds, and even minor components may provide valuable insight into their sources and transformations. To understand atmospheric processes, individual components are frequently identified and quantified using gas chromatography–mass spectrometry. However, due to the complexity and frequently variable nature of such data, data reduction is a significant bottleneck in analysis. Consequently, only a subset of known analytes is often reported for a dataset, and large amounts of potentially useful data are discarded. We present an automated approach of cataloging and potentially identifying all analytes in a large chromatographic dataset and demonstrate the utility of our approach in an analysis of ambient aerosols. We use a coupled factor analysis–decision tree approach to deconvolute peaks and comprehensively catalog nearly all analytes in a dataset. Positive matrix factorization (PMF) of small subsections of multiple chromatograms is applied to extract factors that represent chromatographic profiles and mass spectra of potential analytes, in which peaks are detected. A decision tree based on peak parameters (e.g., location, width, and height), relative ratios of those parameters, peak shape, noise, retention time, and mass spectrum is applied to discard erroneous peaks and combine peaks determined to represent the same analyte. With our approach, all analytes within the small section of the chromatogram are cataloged, and the process is repeated for overlapping sections across the chromatogram, generating a complete list of the retention times and estimated mass spectra of all peaks in a dataset. We validate this approach using samples of known compounds and demonstrate the separation of poorly resolved peaks with similar mass spectra and the resolution of peaks that appear in only a fraction of chromatograms. As a case study, this method is applied to a complex real-world dataset of the composition of atmospheric particles, in which more than 1100 unique chromatographic peaks are resolved, and the corresponding peak information along with mass spectra are cataloged.

Thrombin generation as a predictor of outcomes in patients with non-traumatic intracerebral hemorrhage.

Non-traumatic intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and leads to a higher rate of mortality as compared to ischemic strokes. We aimed to find out whether the thrombin generation assay (TGA) could predict outcomes in patients with ICH. In this prospective, observational study, 87 consecutive patients with ICH and 164 healthy controls were included. Computed tomography (CT), detailed clinical investigation, and laboratory investigations were performed from patients on admission. TGA was performed using stored platelet poor plasma obtained on admission. Lag time, endogen thrombin potential (ETP), peak thrombin, and time to peak parameters were calculated. Short- and long-term outcomes of ICH were defined at 14 days and 3 months post-event according to the NIHSS and the modified Rankin Scale (mRS), respectively. Peak thrombin was significantly higher in patients as compared to controls (397.2 ± 93.9 vs. 306 ± 85.3 nM, p < 0.0001). Lag time, ETP, and time to peak parameters showed a significant positive correlation with CRP in both groups. In patients with worse long-term functional outcomes, peak thrombin was significantly higher as compared to those with favorable outcomes [mRS 2-6 median: 402.5 (IQR:344.8-473.8) vs. mRS 0-1: 326.4 (294.2-416.1) nM, p = 0.0096]. Based on the statistically optimal threshold of 339.1 nM peak thrombin, the sensitivity and specificity of this parameter to determine mRS 2-6 as an outcome were 80.8 and 64.7%, respectively. In a binary logistic regression model including age, sex, BMI, smoking status, NIHSS on admission, D-dimer, and peak thrombin (>339.1 nM), only NIHSS and the peak thrombin parameters remained in the model as significant, independent predictors of poor outcome. Lag time and time to peak showed a modest, significant negative correlation with intracerebral bleeding volume on admission (r = -0.2603, p = 0.0231 and r = -0.3698, p = 0.0010, respectively). During the follow-up of patients, estimated hemorrhage volumes on day 90 showed significant positive association with the ETP and peak thrombin parameters (r = 0.3838, p = 0.0363 and r = 0.5383, p = 0.0021, respectively). In patients with ICH, TG was increased as compared to healthy controls, which might be explained by the presence of higher inflammatory parameters in patients. Peak thrombin measured on admission might be a useful tool to predict outcomes in patients with ICH.

EFFECT OF CLAY SHALE SHEAR STRENGTH DEGRADATION ON BORED PILE FRICTION IN CLAY SHALE

This research aims at investigating and modeling the axial bearing capacity degradation of a bored pile on clay shale due to the bored pile installation processes. Clay shale sample models were prepared to simulate the wetting and drying cycles through weathering process between 0 to 6 hours. All samples were tested in which every 1 hour of the weathering process representing 1 cycle of wetting and drying. The direct shear laboratory tests were performed to obtain the peak and residual shear strength parameters of the interface between the bored pile and clay shale. The peak and residual shear strength parameters were obtained after 6 hours of the weathering process. The residual shear strength parameters were measured by applying with and without stress release. This investigation showed that the shear strength degradation at peak, residual without stress release, and residual with stress release respectively reached 87-62%, 28-20%, and 25-14% after 1 to 6 hours of weathering process. This result is very useful for predicting the bored pile skin friction in clay shale soils.

Wettability of the surface of bacterial cellulose film modified with the ion implantation

Wettability of the surface of bacterial cellulose film modified with low energy ion implantation The paper presents the preliminary results of the modification on the water wettability of cellulose, using ion implantation method. Two kinds ions of the noble gases, i.e. helium and argon were implanted with fluences of 1e15 nand 1e16 cm-2, and with the ion energy of 60 keV. The measurements of the contact angle values show the different influence of both types ions on the hydrophobicity of the modified cellulose, but the hydrophobicity of implanted cellulose increases in all cases. The real investigations were supplemented with the modelling results of the depth profiles of the implanted ions and the main parameters of the modelled peaks.