Peak Height Research Articles

Efficacy of the peak area method of high-performance liquid chromatography (HPLC) analysis: The separation, identification, and quantification of phytochemical compounds of Moringa oleifera

The quantification and identification of phytochemical compounds in Moringa oleifera have received significant attention due to their potential health benefits. High-Performance Liquid Chromatography (HPLC) has become a widely used method for analyzing these phytochemicals due to its speed, adaptability, and effectiveness. However, there is a need to improve these methods to achieve more accurate quantification and understanding of these compounds. This study aims to assess the effectiveness of the peak area method in HPLC for the separation, identification, and quantification of phytochemical compounds in Moringa oleifera leaves. The main goal of the study is to use the peak area method within HPLC to measure the concentration of various phytochemical compounds in Moringa oleifera leaves. This method offers a more reliable measurement than peak height, allowing for comparison of different components' concentrations within or between samples, which is important for trace analysis in various applications. The methodology involved collecting and preparing Moringa oleifera leaves from five regions: Nigeria, Ghana, Haiti, India, and Texas, USA. The leaves were dried, ground, and extracted using methanol and ethanol. The extracts were then analyzed using HPLC, with the peak area method utilized to quantify the phytochemical compounds. The HPLC system utilized a Nucleosyl C18 column with a UV-vis diode-array detector, and the separation process was monitored at 332 nm. Key findings of the study indicated that chlorogenic acid, rutin, ferulic acid, luteolin, apigenin, and kaempferol were successfully separated, identified, and quantified from Moringa oleifera leaves using the peak area method in HPLC. Chlorogenic acid had a retention time of 15.759 minutes and a peak area of 170,844, indicating it is more polar and present in significant quantities. Rutin followed with a retention time of 16.919 minutes and a peak area of 115,599. Ferulic acid was the most abundant compound, with a peak area of 422,129 and a retention time of 17.965 minutes. Luteolin, with a peak area of 235,655 and a retention time of 19.777 minutes, was also present in considerable amounts. Apigenin and kaempferol showed retention times of 20.840 minutes and 21.039 minutes with peak areas of 343,378 and 197,585, respectively. The study also compared the extraction efficiencies of 70% ethanol and 80% methanol, finding that methanol was significantly more effective, especially for highly polar compounds like chlorogenic acid, luteolin, and rutin, with peak areas being 74% to over 1100% higher than those observed with ethanol. The study concluded that the peak area method in HPLC is a highly effective tool for the separation, identification, and quantification of phytochemical compounds in Moringa oleifera leaves. It recommended further optimization of the HPLC method and exploration of pharmacological properties of these phytochemical compounds for nutraceuticals and pharmaceuticals.

Evaluation of Macro- and Micro-Geometry of Models Made of Photopolymer Resins Using the PolyJet Method.

Additive manufacturing (AM) techniques are among the fastest-growing technologies for producing even the most geometrically complex models. Unfortunately, the lack of development of metrology guidelines for these methods, related to dimensional and geometry accuracy and surface roughness, significantly limits the commercialization of finished products manufactured using these methods. This paper aims to evaluate the macro- and micro-geometry of models manufactured using the PolyJet method from three types of photopolymer resins: Digital ABS Plus, RGD 720, and Vero Clear. For this purpose, test parts were designed and then manufactured on an Object 350 Connex3 3D printer. The Atos II Triple Scan optical system and the InfiniteFocusG4 microscope were used to evaluate macro- and micro-geometry, respectively. For both systems, measurement procedures were developed to obtain statistical results for evaluating geometric accuracy and surface roughness parameters. In the case of macro-geometry, for Digital ABS Plus and Vero Clear materials, 50% of the central deviations (between first quartile Q1 and third quartile Q3) lie within the range (-0.06, 0.03 mm) and for RGD 720 material within the range (-0.08, 0.01 mm). For micro-geometry, the arithmetic mean height (Sa) values for the Digital ABS Plus and Vero Clear samples were approximately 1.6 and 2.0 µm, respectively, while for RGD 720, it was 15.9 µm. The total roughness height expressed by reduced peak height (Spk) + core height (Sk) + reduced dale depth (Svk) for the Digital ABS Plus and Vero Clear samples was approximately 9.1 and 10.5 µm, respectively, while for the RGD 720, it was 101.9 µm.

Variations in External and Internal Intensities and Impact of Maturational Age on Soccer Training Tasks.

During peak height velocity, adjusting training intensity is crucial for optimizing performance and minimizing injury risk. This cross-sectional study compares external and internal intensities in different training tasks (analytical tasks, small-sided games, and training matches) and analyzes their effect on the maturation age of young players. Fifty-five U-15 and U-16 boys from two soccer clubs in southwestern Spain were monitored using inertial movement units and heart rate monitors to report training intensities. Anthropometric data and birthdates were collected to estimate maturation age. The Friedman test and Durbin-Conover post hoc test identified specific differences between groups, and Spearman's rank correlation coefficients assessed variable impacts. Training matches showed significantly higher distance covered, maximum and average speed, and average heart rate compared to small-sided games and analytical tasks. High-intensity actions and sprints were significantly higher (p < 0.0001) during training matches compared to analytical tasks and during small-sided games compared to analytical tasks. Player load per minute was significantly highest (p < 0.05) during training matches, followed by small-sided games, and lowest in analytical tasks. Positive correlations between maturational age and high-intensity actions, accelerations, and decelerations indicated higher intensity (p < 0.05) in more mature players. A negative correlation between player load per minute and maturational age suggested more efficient intensity management in mature players. These findings highlight the importance of considering biological maturation and training task variability in youth athletes' development.

Effect of singular value decomposition on removing injection variability in 2D quantitative angiography: An in silico and in vitro phantoms study.

Intraoperative 2D quantitative angiography (QA) for intracranial aneurysms (IAs) has accuracy challenges due to the variability of hand injections. Despite the success of singular value decomposition (SVD) algorithms in reducing biases in computed tomography perfusion (CTP), their application in 2D QA has not been extensively explored. This study seeks to bridge this gap by investigating the potential of SVD-based deconvolution methods in 2D QA, particularly in addressing the variability of injection durations. Building on the identified limitations in QA, the study aims to adapt SVD-based deconvolution techniques from CTP to QA for IAs. This adaptation seeks to capitalize on the high temporal resolution of QA, despite its two-dimensional nature, to enhance the consistency and accuracy of hemodynamic parameter assessment. The goal is to develop a method that can reliably assess hemodynamic conditions in IAs, independent of injection variables, for improved neurovascular diagnostics. The study included three internal carotid aneurysm (ICA) cases. Virtual angiograms were generated using computational fluid dynamics (CFD) for three physiologically relevant inlet velocities to simulate contrast media injection durations. Time-density curves (TDCs) were produced for both the inlet and aneurysm dome. Various SVD variants, including standard SVD (sSVD) with and without classical Tikhonov regularization, block-circulant SVD (bSVD), and oscillation index SVD (oSVD), were applied to virtual angiograms. The method was applied on virtual angiograms to recover the aneurysmal dome impulse response function (IRF) and extract flow related parameters such as Peak Height PHIRF, Area Under the Curve AUCIRF, and Mean transit time MTT. Next, correlations between QA parameters, injection duration, and inlet velocity were assessed for unconvolved and deconvolved data for all SVD methods. Additionally, we performed an in vitro study, to complement our in silico investigation. We generated a 2D DSA using a flow circuit design for a patient-specific internal carotid artery phantom. The DSA showcases factors like x-ray artifacts, noise, and patient motion. We evaluated QA parameters for the in vitro phantoms using different SVD variants and established correlations between QA parameters, injection duration, and velocity for unconvolved and deconvolved data. The different SVD algorithm variants showed strong correlations between flow and deconvolution-adjusted QA parameters. Furthermore, we found that SVD can effectively reduce QA parameter variability across various injection durations, enhancing the potential of QA analysis parameters in neurovascular disease diagnosis and treatment. Implementing SVD-based deconvolution techniques in QA analysis can enhance the precision and reliability of neurovascular diagnostics by effectively reducing the impact of injection duration on hemodynamic parameters.

Surface Roughness Evaluation of AZ31B Magnesium Alloy After Rough Milling Using Tools with Different Geometries

This paper presents the experimental results of a study investigating the impact of machining parameters on 3D surface roughness after rough, dry milling. The following 3D roughness parameters were analysed: Sa (arithmetic mean height), Sq (root mean square height), Sz (maximum height), Sku (kurtosis), Ssk (skewness), Sp (maximum peak height), and Sv (maximum pit height). Roughness measurements were made on the end face of the specimens. Additionally, 3D surface topography maps and Abbot-Firestone material ratio curves were generated. Carbide end mills with variable rake and helix angles were used in the study. Experiments were conducted on AZ31B magnesium alloy specimens using a contact-type profilometer. The machining process was conducted using the parameters of so-called high-speed machining. Three variable technological parameters were analysed: cutting speed vc, feed per tooth fz, and axial depth of cut ap. The results showed that the surface roughness of the rough-milled specimens depended to a great extent on the tool geometry and applied machining parameters. Feed per tooth was found to have the greatest impact on surface roughness parameters. Lower values of the analysed surface roughness parameters (and therefore higher surface quality) were obtained (in most cases) for the tools with a rake angle γ of 5° and a helix angle λs of 50°. The results provided both theoretical and practical knowledge about the achievable surface roughness after rough milling using tools with different tool blade geometry. It was shown that rough milling is an effective and efficient type of machining for the AZ31B alloy.

An automatic method for accurate signal-to-noise ratio estimation and baseline correction of Raman spectra of environmental microplastics

In this study, we introduced a k-iterative double sliding-window (DSW^k) method for the estimation of spectral noise, signal-to-noise ratio (SNR), and baseline correction. The performance was evaluated using simulated spectra and compared against other commonly employed methods. Convergent evaluation determined that a k value of 20 strikes an optimal balance between convergence and computational intensity. The DSW^k method demonstrated outstanding performance across different spectral types (flat baseline, baseline with elevation, baseline with fluctuation, baseline with elevation and fluctuation) coupled with SNR values from 10 to 1000, achieving results that ranged from 1.01 to 1.08 times of the reference value in estimating spectral noise. It also showed that the estimated SNR values are 0.89 to 0.93 times of the reference value, demonstrating a 74.5 % − 131.7 % improvement over the conventional method in spectra with elevated and/or fluctuating baselines. Additionally, the DSW^k method proved effective in correcting baselines and identifying polymers in environmental samples of polyethylene (PE), polypropylene (PP), and polystyrene (PS), despite the limitation of reducing the peak height in spectra with low SNR. This method offers the potential to enhance the automatic and accurate evaluation of spectral quality and could assist in the development of guidelines for more rapid parameter adjustments in Raman measurements.

HPTLC Phytochemical Profiling and Simultaneous Quantification of Quercetin and Gallic in Prosopis juliflora (Sw.)

Prosopis juliflora (Sw.) commonly known as jangli babool or vilayati babool have several bioactive compounds of therapeutic needs. The presence of various bioactive compounds and markers specifically, quercetin and gallic acid in the methanolic extract of Prosopis juliflora (fruiting aerial part) denotes their valuable pharmacological activities. Therefore, high performance thin layer chromatography (HPTLC) analysis with simultaneous quantification of quercetin and gallic acid was done for their phytochemical profiling.The phytochemical profiling and simultaneous quantification of quercetin and gallic acid of methanolic extract of Prosopis juliflora through CAMAG HPTLC analysis was determined and results were obtained in the form of chromatogram scanned at the wavelength 254nm and 366nm. Phytochemical profiling of the plant was presented in the tables showing the number of peaks, peak area, area percentage and Rf values. 14 compounds were present in sample 1 and 9 compounds were present in sample 2 denoted by the number of peaks as represented in chromatograms of test samples. Peak area and height were used to quantify quercetin and gallic acid. Quercetin was found to be 1.364% in sample 1 and 0.27% in Sample 2 while gallic acid was 0.088% in sample 1 only. Importance of this research is to rationalize the therapeutic properties of Prosopis juliflora in the indian traditional medicinal system and phytochemical profiling and simultaneous quantification of quercetin and gallic acid reveals that Prosopis juliflora have several bioactive compounds and this might be accountable for their future application in the field of pharmacognostic and pharmacological drug discovery.

Investigation of vaned diffuser endwall contouring technology for improving the stable operating range of a centrifugal compressor with an asymmetric volute

AbstractIn this study, nonaxisymmetric endwall contouring technology is employed as a passive control strategy to enhance the stable operating range of a centrifugal compressor with an asymmetric volute. The endwall contouring method is applied to the hub‐side wall of the vaned diffuser within a centrifugal compressor stage. Instead of utilizing a flat hub as the baseline diffuser, various diffuser configurations featuring hub‐side contoured endwalls are explored, with adjustments in the peak radial position and peak height of the convex and concave profiles. Numerical simulations are conducted to evaluate the performance of the centrifugal compressor stage with both the baseline and contoured vaned diffusers. The investigation explores the underlying flow control mechanisms and establishes the effective endwall contouring guidelines. The findings highlight the effectiveness of endwall contouring in enhancing the stable operating range of centrifugal compressors. Notably, a substantial enhancement of 15.1% in the stable operating range is achieved by employing the contoured diffuser with the peak radial position near the vane leading edge (LE) and the peak height at 20% of the vane height. The endwall contoured diffusers reduce the positive LE incidence angles to direct the fluid toward the suction side (SS), and increase the radial velocity near the SS to suppress the hub‐suction corner separations in the diffuser passages near the volute tongue. These improvements collectively contribute to the enhancement of diffuser flow characteristics. Finally, a set of effective endwall contouring guidelines is proposed to guide the endwall contouring design for enhancing the stable operating range of centrifugal compressors.

Directly visualizing nematic superconductivity driven by the pair density wave in NbSe2

Pair density wave (PDW) is a distinct superconducting state characterized by a periodic modulation of its order parameter in real space. Its intricate interplay with the charge density wave (CDW) state is a continuing topic of interest in condensed matter physics. While PDW states have been discovered in cuprates and other unconventional superconductors, the understanding of diverse PDWs and their interactions with different types of CDWs remains limited. Here, utilizing scanning tunneling microscopy, we unveil the subtle correlations between PDW ground states and two distinct CDW phases — namely, anion-centered-CDW (AC-CDW) and hollow-centered-CDW (HC-CDW) — in 2H-NbSe2. In both CDW regions, we observe coexisting PDWs with a commensurate structure that aligns with the underlying CDW phase. The superconducting gap size, Δ(r), related to the pairing order parameter is in phase with the charge density in both CDW regions. Meanwhile, the coherence peak height, H(r), qualitatively reflecting the electron-pair density, exhibits a phase difference of approximately 2π/3 relative to the CDW. The three-fold rotational symmetry is preserved in the HC-CDW region but is spontaneously broken in the AC-CDW region due to the PDW state, leading to the emergence of nematic superconductivity.

The Evolution of Surfaces on Medium-Carbon Steel for Fatigue Life Estimations

Early in fatigue life, fatigue cracks are often initiated at persistent slip bands (PSBs), which play the main role in surface evolution when the components are subjected to cyclic loading. Therefore, this paper aims to study the behavior of the surface development of medium-carbon steel, specifically 42CrMo4 (SAE 4140). Tests were conducted using tension–compression fatigue testing with stress amplitudes set at 30%, 40%, and 50% of the ultimate tensile strength (UTS); a load ratio of R = −1; and a frequency of f = 10 Hz. The ultimate number of test cycles was 2 × 105. The fatigue test specimens with as-machined surface quality (Ra &lt; 100 nm) were tested on a servo-hydraulic push–pull testing machine, and the tests were interrupted a few times to bring the specimens out for surface measuring with a confocal microscope. The linear roughness values of the arithmetic mean deviation (Ra), maximum height (Rz), maximum profile peak height (Rp), and maximum profile valley depth (Rv) were investigated and further used to determine the roughness evolution during cyclic loading (REC) by analyzing the inclinations of the fitting curves of roughness and number-of-cycles diagrams. REC could then be used to estimate and classify the fatigue lifetime.

Application of the Agilent 2100 Bioanalyzer instrument as quality control for next-generation sequencing.

Next-generation sequencing (NGS) technologies have expanded the spectrum of forensic DNA analysis by facilitating efficient and precise genotyping of a large number of genetic markers. Yet, challenges persist regarding complex sample processing and assurance of equal molar concentrations across pooled samples. Since optimal cluster density is crucial for sequencing performance, the determination of both quantity and quality is indispensable for library preparation. In this study, we investigated the application of the Agilent 2100 Bioanalyzer for library quality control, as studies for forensic approaches, particularly for highly degraded postmortem samples, are rare. Our analysis encompassed assessing total DNA concentrations, fluorescence unit (FU) values, and adapter dimer concentrations in purified DNA libraries derived from buccal swabs and tissue samples of decomposed corpses. The sensitivity study tested a serial dilution derived from buccal swabs and revealed a decrease in FU values and an increase in adapter dimers with declining DNA input concentrations. Deviations in total DNA concentrations and average peak heights between the Agilent 2100 Bioanalyzer runs indicated a lack of repeatability in data and presented challenges in accurate quantification, which was also observed in previous studies. Yet, the analysis of degraded samples from decomposed human remains has shown the ability to detect adapter dimer concentrations, which can be crucial for the quality of subsequent NGS library preparation and sequencing success. Therefore, the Agilent 2100 Bioanalyzer proves to be a valuable tool for NGS quality control.

Synthesis and EPR Studies of Zinc and Copper TPMA Metal Complexes Containing TEMPO Functionalities

A new family of stable radical‐containing polytopic ligands based on tris(2‐pyridylmethyl)amines TPMA architecture and their corresponding metal complexes have been synthesized. These molecular systems offered the possibility to investigate how various spin carriers, such as the metal ion and the organic radical, influence their EPR properties mainly through the empirical ratio of peak heights d1/d. Moreover, it has been possible to analyze how different conformations of TEMPO radical units in the molecular skeleton affect the metallic system.

Injury Risk in Elite Young Male Soccer Players: A Review on the Impact of Growth, Maturation, and Workload.

Ribeiro, N, Martinho, DV, Pereira, JR, Rebelo, A, Monasterio, X, Gonzalo-Skok, O, Valente-dos-Santos, J, and Tavares, F. Injury risk in elite young male soccer players: a review on the impact of growth, maturation, and workload. J Strength Cond Res XX(X): 000-000, 2024-The long-term development of young male soccer players involves a prolonged period of significant adjustments, highlighting the importance of studying the complex interaction between dynamic variables, including workload, and inherent elements like growth and maturity. This analysis examines the intricate connections involving the development, maturity, workload, and susceptibility to injuries among adolescent male soccer players. Significantly, these connections become prominent at the peak height velocity (PHV) period, a crucial moment in maturation. Growth rates vary among individuals, and higher rates have been associated with an increased risk of injury in young soccer players, particularly during periods of rapid growth. Identifying possible risk factors and understanding the complex connections between them is crucial to developing specific methods for reducing the risk of injury. Sharing this valuable information with essential stakeholders is crucial for guaranteeing young athletes' comprehensive growth and maturation process. Furthermore, this review emphasizes the immediate need for long-term studies and thorough injury analyses to comprehend better the dynamic interactions that influence injury patterns in young male soccer players. This review will allow practitioners to better understand the main modifiable and nonmodifiable risk factors for injury and provide essential information focusing on practical strategies, facilitating more informed decision making by all stakeholders. The review aims to clarify these complexities and offer crucial insights that can assist in designing and implementing efficient strategies to reduce the risk of injury, specifically for the challenges faced during PHV and within the broader framework of long-term athletic development in young soccer.

Holographic complexity and phase transition for AdS black holes

Recently, the complexity equals any gravitational observable conjecture has been proposed in [], which is an extension of the complexity equals volume proposal. These gravitational observables are referred to as generalized volumes. In this paper, we investigate the generalized volume complexity for black holes with one or two horizons respectively. We verify that the turning time is universal and independent of the Cauchy horizon. Not only does this phase transition occur once, but it may also occur two or more times depending on the number and height of the effective potential peaks. On the other hand, we confirm that the generalized volume complexity can be divided based on the shape of the effective potential. We then discuss the nonsmooth transition from the Reissner–Nordström–anti-de Sitter (AdS) black hole to the Schwarzschild-AdS black hole. Published by the American Physical Society 2024

Programmable Graphene e-Nose Sensor Arrays for Fast, Sensitive, and Label-Free Identification of Chemical Vapors

Conventional nanoelectronic chemical vapor sensors are mostly based on charge transfer mechanisms. The presence of vapor molecules interacts with the sensing material, resulting in changes in charge density in the channel; the resulting conductance change can subsequently be detected as changes in the current signals. This charge transfer-based mechanism naturally requires strong molecule-sensor interaction in order to achieve high sensitivity. However, the strong binding of analytes to the sensor surface will inevitably lead to slow response time and slow sensor recovery, making it unsuitable for applications requiring rapid monitoring of chemical vapors.To address this challenge, our groups previously demonstrated a new type of fast, sensitive, and broad-spectrum electronic vapor sensor by exploiting the fringing field capacitance effect in the graphene field-effect transistor (GFET). The typically trivial fringing field capacitance change due to analyte absorption is greatly amplified by both the graphene transistor and a micro-flow channel covering the surface of graphene. Different from the charge-transfer process in traditional sensors, when molecules of analytes flow through the surface of the graphene transistor, its local dielectric environment is altered which results in changes in the fringing capacitance. This molecular fringing gate effect can be amplified intrinsically by the large transconductance of the GFET. Instead of using AC spectroscopy, this capacitance change can be measured conveniently as a peak in DC current.1 In this work, a programmable graphene e-nose sensor array with electrical gates design and enhanced packaging will be demonstrated to achieve true label-free sensing and identification of chemical vapors. Individual graphene sensors within the 1D sensor array (up to 1 x 9) can be optimized to offer sensitive (down to picogram) and fast (sub-second) detection toward a variety of analytes. Figure 1 demonstrates the prototype of the graphene sensor array. Each sensor chip consists of two parts: an array of nine GFETs with a dimension of 15mm by 15mm (Figure 1(A)), and a 40cm long micro-column chip with a column width of 20-60 μm fabricated on a silicon wafer with 200nm of SiO2 by using DRIE (Deep Reactive Ion Etching) (Figure 1(B)). These two components were then bonded by epoxy and the assembled sensor chip is shown in Figure 1(C). The graphene transistor array was fabricated by transferring CVD graphene onto a silicon substrate with 200nm of thermally grown SiO2. Individual gold metal back gates were fabricated underneath the graphene film with 200nm Al2O3 deposited by ALD (atomic layer deposition) as the gate dielectric. Devices with single or multi-layer (up to 4 layers) graphene films were fabricated and tested.The fabricated graphene sensors have near-perfect device yield and a resistance range within 2 ~ 10 kΩ. Figure 1(D) and 1(E) shows the DC current signal changes of a typical sensor within the array when vapor-phase analytes of different masses were injected through a benchtop gas chromatography (GC) setup. 9 ng and 6 ng of Hexanal injection generated current peaks with peak heights of 0.8 μA and 0.5 μA, and peak width (full width at half maximum) of 1.8 seconds and 2 seconds, respectively. The high signal-to-noise ratio (~ 80 to 1) and the short response time demonstrate the high sensitivity and fast detection capability of the graphene sensor. Figure 1(E) shows a detailed sensitivity test from the injections of hexanal vapor of five different masses. The graphene sensor exhibits good linearity with a sensitivity of 79nA per nanogram of Hexanal and a 3σ detection limit of 380 picograms.We further tested the electrical gate tunability of the graphene sensor’s response. In order to eliminate the effect of graphene conductance modulation by the gate voltage, we normalize the peak height with the baseline current. As shown in Figure 1(F), when the gate voltage is programmed from -10V to +10V, the hexanal peak height is strengthened by approximately 30 percent. Similar gate voltage tuning is also observed on other analytes, such as acetone and hexanol.Our results clearly show the gate voltage tunability of the graphene sensor, suggesting a novel graphene sensor array using electrical programming rather than chemical functionalization to achieve selectivity. Combined with advanced data analysis tools, the graphene e-nose array has the potential to offer label-free chemical vapor sensing without the need to individually functionalize each sensor as in traditional e-nose devices. Furthermore, we will discuss the integration of the graphene e-nose sensor array with a micro-gas chromatography chip and a smartphone-sized custom PCB board for programming, readout, and Bluetooth data communication. W. Zang et al., Nano Lett., 21, 10301–10308 (2021). Figure 1

Passivation of Lead-Acid Batteries Lead Negative Electrodes by PbSO4 Crystals: Analysis from Modeling Cyclic Voltammetry Responses

Lead-acid batteries (LABs) play a pivotal role in the energy storage sector with applications spanning from starting-ignition-lightning batteries to grid energy storage. Passivation of lead negative electrodes by PbSO4 crystals is a one fundamental mechanism limiting the performance of LAB. In this regard, we developed an electrochemical mathematical model that simulates the nucleation and growth dynamics of PbSO4 crystals on a flat lead electrode, responsible for its passivation. The model considers the electrochemical dissolution of Pb2+ from lead electrode and the ternary transport of lead, bisulfate, and hydrogen ions in H2SO4 electrolyte. We have validated the model with a rich dataset of cyclic voltammetry (CV) responses collected at several scan rates and several concentrations of H2SO4. The model shows remarkable qualitative and quantitative agreement with the experimental data including the onset potential, center, height, and width of the CV peaks, discharge capacity, and particle size. The model is used to give insights on how different physical and operational parameters can influence the electrochemical response of lead negative electrodes. Keywords: lead-acid battery, nucleation and growth, passivation, cyclic voltammetry

Evaluation and comparison of nine growth and development-based measures of pubertal timing

BackgroundPubertal timing is heritable, varies between individuals, and has implications for life-course health. There are many different indicators of pubertal timing, and how they relate to each other is unclear. Our aim was to quantitatively compare nine indicators of pubertal timing.MethodsWe used data from questionnaires and height, weight, and bone measurements from ages 7–17 y in a population-based cohort of 4267 females and 4251 males to compare nine growth and development-based indicators of pubertal timing. We summarise age of each indicator, their phenotypic and genetic correlations, and how they relate to established genetic risk score (GRS) for puberty timing, and phenotypic childhood body composition measures.ResultsWe show that pubic hair in males (mean: 12.6 y) and breasts in females (11.5 y) are early indicators of puberty, and voice breaking (14.2 y) and menarche (12.7 y) are late indicators however, there is substantial variation between individuals in pubertal age. All indicators show evidence of positive phenotypic intercorrelations (e.g., r = 0.49: male genitalia and pubic hair ages), and positive genetic intercorrelations. An age at menarche GRS positively associates with all other pubertal age indicators (e.g., difference in female age at peak height velocity per SD higher GRS: 0.24 y, 95%CI: 0.21 to 0.26), as does an age at voice breaking GRS (e.g., difference in age at male axillary hair: 0.11 y, 0.07 to 0.15). Higher childhood fat mass and lean mass associated with earlier puberty timing.ConclusionsOur findings provide insights into the measurements of the timing of pubertal growth and development and illustrate value of various pubertal timing indicators in life-course research.

Arterial input function estimation compensating for inflow and partial voluming in dynamic contrast-enhanced MRI.

Both inflow and the partial volume effect (PVE) are sources of error when measuring the arterial input function (AIF) in dynamic contrast-enhanced (DCE) MRI. This is relevant, as errors in the AIF can propagate into pharmacokinetic parameter estimations from the DCE data. A method was introduced for flow correction by estimating and compensating the number of the perceived pulse of spins during inflow. We hypothesized that the PVE has an impact on concentration-time curves similar to inflow. Therefore, we aimed to study the efficiency of this method to compensate for both effects simultaneously. We first simulated an AIF with different levels of inflow and PVE contamination. The peak, full width at half-maximum (FWHM), and area under curve (AUC) of the reconstructed AIFs were compared with the true (simulated) AIF. In clinical data, the PVE was included in AIFs artificially by averaging the signal in voxels surrounding a manually selected point in an artery. Subsequently, the artificial partial volume AIFs were corrected and compared with the AIF from the selected point. Additionally, corrected AIFs from the internal carotid artery (ICA), the middle cerebral artery (MCA), and the venous output function (VOF) estimated from the superior sagittal sinus (SSS) were compared. As such, we aimed to investigate the effectiveness of the correction method with different levels of inflow and PVE in clinical data. The simulation data demonstrated that the corrected AIFs had only marginal bias in peak value, FWHM, and AUC. Also, the algorithm yielded highly correlated reconstructed curves over increasingly larger neighbourhoods surrounding selected arterial points in clinical data. Furthermore, AIFs measured from the ICA and MCA produced similar peak height and FWHM, whereas a significantly larger peak and lower FWHM was found compared with the VOF. Our findings indicate that the proposed method has high potential to compensate for PVE and inflow simultaneously. The corrected AIFs could thereby provide a stable input source for DCE analysis.

The Measurement of the Splash-back Radius of Dark Matter Halos

In the hierarchical evolution framework of cosmology, larger halos grow through matter accretion and halo mergers. To clarify halo evolution, we need to define the halo mass and radius physically. However, the pseudoevolution problem makes the process difficult. Thus, we aim to measure the splash-back radius (R sp), a physically defined halo radius for a large number of halos with various mass and redshift, and to determine the most important parameters that affect it. We use the typical definition of splash-back radius as the radius with the steepest radial density profile. In this work, we measure the splash-back radius of dark matter halos within the mass of 1013 M ⊙ to 3 × 1015 M ⊙ and redshifts spanning 0.08–0.65. This is the measurement of the R sp in the largest range of halo mass and redshift. Using the shear catalog of the Dark Energy Camera Legacy Survey Data Release 8, we investigate the splash-back radius of halos associated with galaxies and galaxy clusters identified in the various catalogs. Our finding reveals a trend wherein massive halos demonstrate a larger splash-back radius, and the normalized splash-back radius (R sp/R 200m) shows a U-shaped mass evolution. The upturn in these relations mainly comes from the contribution of massive halos with low redshifts. We further find the splash-back radius increases with the peak height, while the normalized splash-back radius has a negative relation with the peak height. We also find that R sp ≳ R 200m for most halos, indicating their low accretion rates. Our result is consistent with previous literature across a wide range of mass, redshift, and peak height, as well as the simulation work from More et al.

Long-Term Trends in the Height of the Ionospheric F2 Layer Peak

Long-Term Trends in the Height of the Ionospheric F2 Layer Peak