Peak Intensity Research Articles

A Physics-Informed Auto-Learning Framework for Developing Stochastic Conceptual Models for ENSO Diversity

Abstract Understanding El Niño–Southern Oscillation (ENSO) dynamics has tremendously improved over the past few decades. The ENSO diversity in spatial pattern, peak intensity, and temporal evolution is, however, still poorly represented in conceptual ENSO models. In this paper, a physics-informed auto-learning framework is applied to derive ENSO stochastic conceptual models with varying degrees of freedom. The framework is computationally efficient and easy to apply. Once the state vector of the target model is set, causal inference is exploited to build the right-hand side of the equations based on a mathematical function library. Fundamentally different from standard nonlinear regression, the auto-learning framework provides a parsimonious model by retaining only terms that improve the dynamical consistency with observations. It can also identify crucial latent variables and provide physical explanations. This methodology successfully reconstructs the equations of a realistic six-dimensional reference ENSO model based on the recharge oscillator theory from its data. A hierarchy of lower-dimensional models is derived, and their representation of ENSO (including its diversity) is systematically assessed. The minimum model that represents ENSO diversity is four-dimensional, with three interannual variables describing the western Pacific thermocline depth, the eastern and central Pacific sea surface temperatures (SSTs), and one intraseasonal variable for westerly wind events. Without the intraseasonal variable, the resulting three-dimensional model underestimates extreme events and is too regular. A limited number of weak nonlinearities in the model are essential in reproducing the observed extreme El Niño events and the observed nonlinear relationship between eastern and western Pacific SSTs. Significance Statement This study develops a physics-informed auto-learning approach to improve the modeling and understanding of El Niño–Southern Oscillation (ENSO), a major climate phenomenon influencing global weather and climate. The auto-learning framework explores the causality between key processes to systematically produce stochastic conceptual models with different climate factors that simulate the diversity of observed ENSO events. The key finding is that the minimal model for characterizing the ENSO diversity (with the least number of climate factors) is a four-variable model capturing thermocline depth, sea surface temperatures, and wind bursts that can reproduce intensity and spatial pattern variation. This advancement provides an interpretable tool to identify the minimum sufficient processes governing ENSO behavior for improved predictability.

Tracheal Anastomosis Leaks Across Suture Techniques and Tensions: A Biomechanical Ex Vivo Study.

Anastomotic leak after tracheal resection may occur while coughing in the early postoperative period. We investigated the varying effects of suturing technique, stretch, and tension on anastomotic leaks during simulated coughs. End-to-end anastomoses were performed using continuous or interrupted sutures on excised porcine larynges. Tracheas were secured to a pressurized system simulating cough forces, submerged in a water bath, and stretched to 1, 2, and 3 cm above baseline. Peak pressure, incomplete cough generation, and observed leakages were recorded. Parameters were analyzed using Analysis of Variance (ANOVA), multiple linear regression, and logistic regression modeling. Peak tension (B = -0.660, p < 0.001) and stretch lengths (B = -0.329, p = 0.006) were associated with variance in peak pressure (R2 = 0.77, F(3,294) = 8.182, p < 0.001). Incomplete coughs increased with higher peak tension (odds ratio [OR] = 15.627, p < 0.001) and stretching to 3 cm above baseline (OR = 4.335, p < 0.007). Similarly, leak occurrences, primarily from the posterior tracheal wall, increased with higher peak tension (OR = 1.787, p < 0.001) and stretching to 3 cm (OR = 2.613, p = 0.017). No significance was identified with suturing technique. Interrupted and continuous suture techniques do not differ in anastomotic strength during simulated coughs. Increased peak tracheal tension is associated with a weaker anastomosis, and tracheal stretch to 3 cm was associated with a weaker anastomosis. Our study supports the commonly held clinical belief that, to create a stronger anastomosis, tension should be minimized, and particular attention should be placed at the posterior tracheal wall during closure. NA, Benchtop study Laryngoscope, 134:4998-5005, 2024.

Ozone-microbubble-enhanced oxidation of pharmaceuticals and personal care products in municipal secondary effluents

Microbubble aeration can greatly improve ozonation by enhancing ozone transfer and subsequent hydroxyl radical formation. Here, we applied microbubble ozonation to treat pharmaceuticals and personal care products (PPCPs) in several municipal secondary effluents. Compared with conventional ozonation, microbubble ozonation efficiently eliminated both ozone-reactive and ozone-resistant PPCPs and greatly reduced the ozone doses in the complex water matrixes of the secondary effluents. In addition, compared with millibubble ozonation, the removal of chemical oxygen demand (COD) increased by 32.0%–67.2% at 60mg/L ozone dose during microbubble ozonation. The carbon emission of microbubble ozonation varied in different water matrix, and was 47–76% less than that of millibubble ozonation. The oxidizing capacity ratio of microbubble to millibubble for PPCPs was between 1.26 to 3.50 times, and ozone-resistant PPCPs removal was enhanced more than ozone-reactive PPCPs by microbubble ozonation. Specifically, the oxidizing capacity ratio of microbubble to millibubble for carbamazepine (ozone-reactive) was 1.30 to 2.43 times, whereas that for N,N-diethyl-3-tolumide (ozone-resistant) was 1.88 to 3.50 times. Microbubble ozonation also greatly decreased the UV absorbance and fluorescence for all of the water samples. The UV absorbance at 254, 280, and 320nm decreased by 64.0%–83.8%, and the fluorescence peak intensity decreased by more than 94%. Surrogates for the removal of PPCPs and COD were evaluated and compared. This study provides new insights into the application of microbubble ozonation to control PPCPs in secondary effluents.

Investigating SERS performance of controllable fabricated Ag periodic nanostructures with morphologies of nanoclaws and nanocones in detecting SARS-CoV-2 S protein

Surface-enhanced Raman scattering (SERS) spectroscopy plays an important role in enabling high-precision detection and non-invasive diagnostics. Periodic metallic nanostructures with strong electromagnetic fields and tunable localized surface plasmon resonance can achieve high SERS sensitivity, but fabricating such nanostructures remains a challenge. In this work, the anodic aluminum oxide (AAO) nanocavity template-assisted process of fabricating periodic nanostructures with modulating morphologies from Ag nanoclaws (AgNCWs) to Ag nanocones (AgNCEs) is proposed. The morphologies-related SERS performances of nanostructures are analyzed by using rhodamine 6 g (R6G) as a probe molecule and the optimized AgNCEs possess a limit of detection (LOD) of 1 × 10−9 M. A sandwich strategy is applied to detect SARS-CoV-2 S protein in phosphate-buffered saline (PBS) and pharyngeal swab solution (PSS). The ACE2-modified AgNCEs (ACE2/AgNCEs) structure is applied to bind to the SARS-CoV-2 S protein. The 4-MBA and SARS-CoV-2 S antibody functionalized Au nanoparticles (AuNPs) are used as nanotags. By forming the ACE2/AgNCEs-SARS-CoV-2 S protein-nanotags sandwich structure, characteristic peak intensities of 1580 cm−1 are used as the report signal, and the LOD for SARS-CoV-2 S protein in PBS and PSS solution are 10 fg/mL.

Electro-optical and thermal characterization of copper tartrate crystals grown in silica gel

Copper Tartrate crystals were grown by Gel Growth technique by single diffusion method. Silica gel of Optimum specific gravity was set with tartaric acid at optimum pH and aging period. Band gap of copper tartrate crystal is determined using to be 5.24 eV. In PL spectra broad peak is observed at nearly 367.44186 nm in the range 287 nm to 458 nm along with the sharp, intense transmission maxima peak at wavelength nearly 505.03876 nm which is characteristic of a material composition and electronic band structure. This shows the transparency of it in UV-Visible region and it as a filter in this range TGA analysis concludes that Copper tartrate has loss of one-half water molecule as crystalline water and is stable up to 85.02 ℃DSC analysis assigns the temperature value 314.5 ℃ as melting point and apparent enthalpy of fusion determined is 10.18 mW.

Wear performance enhancement of interface layer in CMT-WAAM fabricated ER4043/ER5356 Bimetallic wall through Friction Stir Surface Treatment

Abstract The cold metal transfer (CMT) based wire arc additive manufacturing (WAAM) technique has limited wear applications compared to other manufacturing methods due to its lower wear resistance. However, integrating friction stir processing (FSP) with WAAM can enhance mechanical or wear performance, making it a promising and reliable manufacturing process for aerospace, automotive, and marine applications. In this work, CMT-WAAM technique has been used to fabricate a bimetallic wall of aluminium alloys (ER4043/ER5356), employing a bidirectional depositional strategy. The impact of FSP on the interface layer of the WAAM wall, serving as a post-processing treatment on the wall's surface, is studied in terms of microstructure and microhardness. Additionally, a pin-on-disk wear test is performed on the interface layer of both WAAM and FSP-treated WAAM walls under loads of 20N, 30N, and 40N. Results from optical and Field emission scanning electron microscopy (FESEM) microstructures revealed the grain refinement in the stirred zone, with a higher wt. % of Mg through Energy Dispersive Spectrometer (EDS) analysis. X-ray diffraction (XRD) identifies various intermetallic compounds, including Al12Mg17, Al3.21Si0.47, and Mg2Si, with higher peak intensities in the FSP-treated wall. Electron Backscatter Diffraction (EBSD) analysis indicates a decrease in the average grain size of stirred area, which is ~72.40 µm in unstirred area and ~5.57 µm in stirred area due to the local strain concentration effect during FSP. Grain refinement during FSP leads to an increase in average hardness by 35.9%. The wear rate and coefficient of friction (COF) get reduced, credited to high-temperature dynamic recrystallization and continuous grain recovery in FSP. Scanning electron microscope (SEM) analysis of worn surfaces highlights abrasion, delamination, and adhesion as significant wear mechanisms.

Moiré Lattice of Twisted Bilayer Graphene as Template for Non-Covalent Functionalization.

We present a novel approach to achieve spatial variations in the degree of non-covalent functionalization of twisted bilayer graphene (tBLG). The tBLG with twist angles varying between ~5°and 7°was non-covalently functionalized with 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) molecules. Our results show a correlation between the degree of functionalization and the twist angle of tBLG. This correlation was determined through Raman spectroscopy, where areas with larger twist angles exhibited a lower HATCN peak intensity compared to areas with smaller twist angles. We suggest that the HATCN adsorption follows the moiré pattern of tBLG by avoiding AA-stacked areas and attach predominantly to areas with a local AB-stacking order of tBLG, forming an overall ABA-stacking configuration. This is supported by density functional theory (DFT) calculations. Our work highlights the role of the moiré lattice in controlling the non-covalent functionalization of tBLG. Our approach can be generalized for designing nanoscale patterns on two-dimensional (2D) materials using moiré structures as a template. This could facilitate the fabrication of nanoscale devices with locally controlled varying chemical functionality.

The Electron–Phonon Interaction in Non-Stoichiometric Bi2Sr2CaCu2O8+δ Superconductor Obtained from the Diffuse Elastic Scattering of Helium Atoms

Previously, helium atom scattering (HAS) has been shown to probe the electron–phonon interaction at conducting crystal surfaces via the temperature dependence of the specular peak intensity. This method is now extended to non-stoichiometric superconductors. The electron–phonon interaction, as expressed by the mass-enhancement factor λ, is derived from the temperature dependence of the diffuse elastic scattering intensity, which specifically depends on the non-stoichiometric component responsible for superconductivity. The measured value of the mass-enhancement factor for Bi2Sr2CaCu2O8+δ at the optimal doping δ = 0.16 is λ = 0.55 ± 0.08 is in good agreement with values of λ recently estimated with other methods. This also confirms the relevant role of electron–phonon interaction in high-temperature non-stoichiometric cuprate superconductors.

The diagnositic value of dynamic contrast-enhanced ultrasound for evaluation of tissue oxygen status in rat hepatoma model

BackgroundHypoxia is a characteristic of solid tumors, but whether significant hypoxia exists in the hepatocellular carcinoma remains unclear. This animal study aims to explore the value of dynamic contrast-enhanced ultrasound (CEUS) quantitative parameters to evaluate the oxygen status in two rat hepatoma models.Materials and methodsN1S1 and McA-RH7777 S-D rat orthotopic hepatoma models were established. Once the tumors reached a diameter of 10–15 mm, CEUS and oxygen partial pressure (pO2) polarography were performed. Immunohistochemical staining for HIF-1α and pimonidazole was conducted after euthanizing the rats. Correlation between quantitative CEUS parameters, pO2, and the immunohistochemical integrated optical density (IOD) was analyzed to assess the predictive ability of CEUS quantitative parameters for the tissue oxygen environment.ResultEleven N1S1 models and ten McA-RH7777 models were established successfully. There was no significant difference in pO2 (35.5 mmHg vs 32.2 mmHg, P = 0.917), IOD of HIF-1α (13.4 vs 20.0, P = 0.159) and pimonidazole (0.70 vs 1.30, P = 0.926) between the tumor and the peritumoral liver tissue. The pO2 values were correlated with CEUS quantitative parameters including mean time-intensity curves (mTIC) (P = 0.003), peak intensity (PKI) (P = 0.010), area under the curve (AUC) (P = 0.009), area under the wash-in curve (WiAUC) (P = 0.006), and arrival time (AT) (P = 0.033). The IOD of HIF-1α correlated with AUC (P = 0.022), WiAUC (P = 0.009), ascending slope (AS) (P = 0.044), and falling time (FT) (P = 0.009). Multiple linear regression indicated that the “short AT” was an independent protective factor for hypoxia (β = -2.347, 95% CI: -4.948, -0.394, P = 0.022), and CEUS had the ability to predict the tumor pO2 (P = 0.003).ConclusionNo evidence of significant hypoxia was identified in two rat orthotopic hepatoma models. Quantitative CEUS parameters correlated with the oxygen status of the tumor, which could be utilized to predict the tumor tissue pO2.

Comparison of contrast-enhanced ultrasound imaging (CEUS) and super-resolution ultrasound (SRU) for the quantification of ischaemia flow redistribution: a theoretical study

The study of microcirculation can reveal important information related to pathology. Focusing on alterations that are represented by an obstruction of blood flow in microcirculatory regions may provide an insight into vascular biomarkers. The current in silico study assesses the capability of contrast enhanced ultrasound (CEUS) and super-resolution ultrasound imaging (SRU) flow-quantification to study occlusive actions in a microvascular bed, particularly the ability to characterise known and model induced flow behaviours. The aim is to investigate theoretical limits with the use of CEUS and SRU in order to propose realistic biomarker targets relevant for clinical diagnosis. Results from CEUS flow parameters display limitations congruent with prior investigations. Conventional resolution limits lead to signals dominated by large vessels, making discrimination of microvasculature specific signals difficult. Additionally, some occlusions lead to weakened parametric correlation against flow rate in the remainder of the network. Loss of correlation is dependent on the degree to which flow is redistributed, with comparatively minor redistribution correlating in accordance with ground truth measurements for change in mean transit time,dMTT(CEUS,R = 0.85; GT,R = 0.82) and change in peak intensity,dIp(CEUS,R = 0.87; GT,R = 0.96). Major redistributions, however, result in a loss of correlation, demonstrating that the effectiveness of time-intensity curve parameters is influenced by the site of occlusion. Conversely, results from SRU processing provides accurate depiction of the anatomy and dynamics present in the vascular bed, that extends to individual microvessels. Correspondence between model vessel structure displayed in SRU maps with the ground truth was>91%for cases of minor and major flow redistributions. In conclusion, SRU appears to be a highly promising technology in the quantification of subtle flow phenomena due ischaemia induced vascular flow redistribution.

Vibrational mode tailoring approach: an efficient route to compute anharmonic molecular vibrations of large molecules.

In this study, an efficient route to compute the multidimensional potential energy surfaces (PESs) for the description of quantum anharmonic molecular vibrations is presented. For large molecular systems, where the number of inter mode coupling terms are substantial, a tailor-made construction of truncated PESs is suggested which suitably avoids computation of full PESs by quantitative assessment of the atomic displacements during the normal mode of vibrations. It is shown that, typically, when two normal modes of vibrations are sharing the same atoms, the mode-mode coupling strength is generally large and can be included for truncated PESs. Since the calculations of these terms are the main computational bottleneck, the guided construction of tailor-made PESs can remarkably speed up the calculation by many folds against the expense of little accuracy for peak positions and intensities. This protocol is applicable to any anharmonic vibrational algorithm and more appropriate for large molecules where exploration of chemically important small fragments is more significant compared to that of the entire molecule. A systematic study for n-butanol and a dipeptide in the framework of the VSCF-PT2 method shows that for a group of n target modes, inclusion of a set of 5n-6n other associated important modes is sufficient to offer good accuracy with an error of ∼5-20 cm-1 against the full PES and computationally faster by ∼10-20 times. Finally, a prescription is given on the choice of such tailor-made PESs to compute anharmonic vibrational spectra accurately and efficiently without calculating the full PES.

Molecular Oxygen (O2) Artifacts in Tandem Mass Spectra.

Peak annotation plays an important role in mass spectral evaluation of the NIST 2023 tandem mass spectral library. While most fragment ions are formed by neutral losses, there are peaks that represent adduct ions from these fragments. Previously, we have reported two main types of addition reactions in the collision cell, namely addition of H2O and N2. Here we report a different reaction in the collision cell, with addition of O2 leading to a small peak that could only be assigned to a peroxyl radical ion. For example, some protonated iodoaromatics lose an iodine atom to form a radical cation [M+H-I]+•, which reacts with O2 to generate a peroxyl radical ion [M+H-I+O2]+•. Higher concentrations of O2 result in higher peroxyl radical peaks, which become dominant while the precursor ions are consumed, as examined by five compounds under different concentrations of O2. The correlation of the peroxyl radical peak intensities to the concentration of O2 provides a tool to estimate trace amounts of O2 within the instrument. In the NIST 2023 tandem mass spectral library, the peaks for [M+H-X+O2]+· are most abundant in numbers and in intensity for X = NO2 or I, are much less abundant for X = Br, and are rare for X = Cl. Other leaving groups in this library are SO3H, SO2NH2, CSNH2, CO2C6F5, SO2CH3, and COCH3. The O2 addition reaction is also observed with negative ions in this library. While adducts of H2O and N2 often constitute major peaks, the peaks of the peroxyl radicals under standard conditions are mostly very small and may be mistaken for noise, but their correct annotation improves the quality of the spectra and is important when comparing spectra from different instruments or conditions.

Assessing Therapeutic Nanoparticle Accumulation in Tumors Using Nanobubble-Based Contrast-Enhanced Ultrasound Imaging.

This study explores the challenges associated with nanoparticle-based drug delivery to the tumor parenchyma, focusing on the widely utilized enhanced permeability and retention effect (EPR). While EPR has been a key strategy, its inconsistent clinical success lacks clear mechanistic understanding and is hindered by limited tools for studying relevant phenomena. This work introduces an approach that employs multiparametric dynamic contrast-enhanced ultrasound (CEUS) with a nanoscale contrast agent for noninvasive, real-time examination of tumor microenvironment characteristics. We demonstrate that CEUS imaging can: (1) evaluate tumor microenvironment features, (2) be used to help predict the distribution of doxorubicin-loaded liposomes in the tumor parenchyma, and (3) be used to predict nanotherapeutic efficacy. CEUS using nanobubbles (NBs) was carried out in two tumor types of high (LS174T) and low (U87) vascular permeability. LS174T tumors consistently showed significantly different time intensity curve (TIC) parameters, including area under the rising curve (AUCR, 2.7×) and time to peak intensity (TTP, 1.9×) compared to U87 tumors. Crucially, a recently developed decorrelation time (DT) parameter specific to NB CEUS dynamics successfully predicted the distribution of doxorubicin-loaded liposomes within the tumor parenchyma (r = 0.86 ± 0.13). AUCR, TTP, and DT were used to correlate imaging findings to nanotherapeutic response with 100% accuracy in SKOV-3 tumors. These findings suggest that NB-CEUS parameters can effectively discern tumor vascular permeability, serving as a biomarker for identifying tumor characteristics and predicting the responsiveness to nanoparticle-based therapies. The observed differences between LS174T and U87 tumors and the accurate prediction of nanotherapeutic efficacy in SKOV-3 tumors indicate the potential utility of this method in predicting treatment efficacy and evaluating EPR in diseases characterized by pathologically permeable vasculature. Ultimately, this research contributes valuable insights into refining drug delivery strategies and assessing the broader applicability of EPR-based approaches.

Contrasting impact of single-year and multi-year El Niño on the Pacific-North American teleconnection pattern

Abstract Distinct Pacific-North American (PNA) teleconnection patterns and their associated climate impacts in North America have been observed during single-year El Niño events, as well as during both the first and second years of multi-year El Niño events. The research highlights the critical role of PNA-related North Pacific circulation anomalies, which shift northwestward during multi-year events and reach their peak intensity in the second year. Multiple dynamical diagnostic methods are employed to elucidate the reasons behind the diverse subtropical circulation responses. Differences in the anomalous tropical heat sources influence the formation of Rossby wave sources through adjustments in divergent wind anomalies, subsequently modulating the position and intensity of the PNA patterns. Additionally, variations in the meridional range of sea surface temperature anomalies affect the edge of tropospheric temperature through moist-adiabatic adjustment, leading to distinct subtropical jet stream responses. This, in turn, modifies the position of North Pacific circulation anomalies through the advection of anomalous kinetic energy. Furthermore, synoptic-scale transient eddies act as a feedback mechanism, helping to maintain and intensify these diverse atmospheric anomalies.

Crystal structure, bandgap, photoluminescence and resistivity properties of double perovskite Cs2AgBiCl6 single crystal and its thin film.

Lead-free Cs2AgBiCl6 double perovskite (Cs2AgBiCl6-DP) material, as a substitute for lead halide perovskite materials, has the advantages of environmental friendliness and high stability and has attracted much attention. However, the photoluminescence and conductive properties of Cs2AgBiCl6-DP have not been well studied. In this study, we prepared Cs2AgBiCl6-DP single crystals (SCs) by coordination-dissolution and coordination-precipitation method. Single- and powder-XRD, SEM, EDS, XPS, and EPR characterization were performed to confirm the structural characteristics of Cs2AgBiCl6-DP SCs. The Tauc diagram based on UV-visible (UV-vis) absorption spectroscopy reveals that the optical bandgap of Cs2AgBiCl6-DP SCs is extrapolated to 2.51 eV. Steady-state fluorescence spectra and time-resolved fluorescence spectra show that Cs2AgBiCl6-DP SCs has four fluorescence peaks entered at 443, 615, 650 and 723 nm and a fluorescence lifetime of about 4.16 ns. Cs2AgBiCl6/PMMA thin films were prepared by spin coating suspension (Cs2AgBiCl6 DP and PMMA in acetone solvent). The intensity of emission peak increases with the increase of light intensity at 369 nm. The intensity of emission peak located at 576 nm decreases with increasing incidence wavelength (from 369 to 454 nm) at 10 W m-2. The emission intensity remains basically unchanged under continuous illumination for 9 hours at 369 nm at 5 W m-2, which indicates that the Cs2AgBiCl6-DP thin film has good stability. In addition, the resistivity and block resistance show a negative exponential change with increasing temperature. These results provide some interesting ideas for the fields of photoluminescence and thermistors.

The Effect of the Pyrolysis Temperature of a Leather-Textile Mixture from Post-Consumer Footwear on the Composition and Structure of Carbonised Materials.

This paper presents an investigation into the use of pyrolysis to valorise solid waste in the form of post-consumer footwear uppers. A heterogenous leather and textile mixture is studied, produced by crushing some representative samples of post-consumer footwear uppers. The waste has a low ash content and a high net calorific value, which translates into the high gross calorific value of the material. In addition, it contains relatively little S and Cl, which is promising for its use in the process of pyrolysis. The effect of the pyrolysis temperature on the efficiency of carbonising leather and textile mixtures, their physico-chemical parameters, elemental composition, and structure, as well as the development of a specific surface, is investigated. The research results imply that as the pyrolysis temperature grows, the carbonisation efficiency declines. The produced materials consist primarily of C, O, N, and H, whose contents depend on the pyrolysis temperature. Moreover, all the carbonised materials display the presence of two G and D bands, which is typical for carbon materials. Based on the peak intensities of the bands, ID/IG coefficients are calculated to assess the organisation of the materials' structures. As the pyrolysis temperature rises, the structural organisation declines, contributing to an increased material porosity and, thus, a greater specific surface of the carbonised materials. This study contributes data on the thermal management and pyrolysis of leather and textile waste into useful carbonised materials. Investigating the applicability of carbonised materials is projected as the next stage of research work.

Study on the Structural Changes of Boneless Chicken Claw Collagen and Its Effect on Water Retention Performance.

The purpose of this study was to explore the water retention mechanism of chicken claws by detecting the structural changes in collagen in boneless chicken claws under different expansion rates. Firstly, boneless chicken claw collagen with different expansion rates (0%, 10%, 20%, 30%, 40%, 50%) was extracted by the acid-enzyme complex method, and the changes in collagen were determined by scanning electron microscopy (SEM), ultraviolet spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), low-field nuclear magnetic resonance LF-NMR) and surface hydrophobicity to explore the mechanism that leads to changes in the water retention performance. The results of scanning electron microscopy showed that with the increase in the expansion rate, collagen molecules showed curling, shrinking, breaking and crosslinking, forming a loose and irregular pore-like denatured collagen structure. UV analysis showed that the maximum absorption wavelength of chicken claw collagen was blue shifted under different expansion rates, and the maximum absorption peak intensity increased first and then decreased with the increase in expansion rate. The FTIR results showed that collagen had obvious characteristic absorption peaks in the amide A, B, I, II and III regions under different expansion rates, and that the intensity and position of the characteristic absorption peaks changed with the expansion rate. The results of the CD analysis showed that collagen at different expansion rates had obvious positive absorption peaks at 222 nm, and that the position of negative absorption peaks was red shifted with the increase in expansion rate. This shows that the expansion treatment makes the collagen of chicken claw partially denatured, and that the triple helix structure becomes relaxed or unwound, which provides more space for the combination of water molecules, thus enhancing the water absorption capacity of boneless chicken claw. The results of the surface hydrophobicity test showed that the surface hydrophobicity of boneless chicken claw collagen increased with the increase in expansion rate and reached the maximum at a 30% expansion rate, and then decreased with the further increase in the expansion rate. The results of LF-NMR showed that the water content of boneless chicken claws increased significantly after the expansion treatment, and that the water retention performance of chicken claws was further enhanced with the increase in the expansion rate. In this study, boneless chicken claws were used as raw materials, and the expansion process of boneless chicken claws was optimized by acid combined with a water-retaining agent, which improved the expansion rate of boneless chicken claws and the quality of boneless chicken claws. The effects of the swelling degree on the collagen structure, water absorption and water retention properties of boneless chicken claws were revealed by structural characterization. These findings explain the changes in the water retention of boneless chicken claws after expansion. By optimizing the expansion treatment process, the water retention performance and market added value of chicken feet products can be significantly improved, which is of great economic significance.

Analysis of mooring performance and layout parameters of multi-segment mooring system for a 15 MW floating wind turbine

IntroductionFloating wind power is the important path for the development of offshore wind energy, and the performance of the mooring system of floating wind turbines (FOWTs) significantly affects their economic viability, safety, and sustainability.MethodsThis paper systematically analyses the positioning performance, mooring line extreme loads, and fatigue response of a FOWT equipped with both single segment and multi-segment mooring systems, based on the IEA 15 MW large turbine and a floating platform. The hydrodynamic performance of the floating platform is calculated, and the platform’s motion-sensitive directions are analysed through Response Amplitude Operators (RAOs). The natural periods of the platform are validated by free decay tests. The six degrees of freedom (DOFs) motion response and the mooring line peak tensions are analysed under normal and extreme conditions.ResultsThe results show that both mooring systems provide good motion performance and stable tilt angles for the platform. Under ALS (single-line failure) condition, the multi-segment mooring system demonstrates a notable capacity to resist impact loads, with comparatively minor fluctuations in mooring line tension. In the multi-segment system, fatigue damage primarily occurs in the upper mooring chain, with damage approximately 4.5 times greater than that of the bottom chain over a 1-year period. The effects of mooring line spread angles and lengths on performance are also analysed. The results indicate that the mooring line spread angle has slight impact on platform motion response and mooring line tension, while mooring line length significantly affects the extreme tension of the lines.DiscussionThe findings of this study can provide some references in the design of mooring systems for future FOWTs.

Synthesis, Structural Aspects, Magnetic, and Adsorption Properties of a Dinuclear Cu (II) Complex Derived From Mixed Ligand Approach

ABSTRACTA dinuclear copper complex, [Cu2(teaH)(pNBA)2(H2O)2]·MeOH·pNBH (1) (where teaH3 = triethanolamine, pNBH = 4‐nitro‐benzoic acid, and pNBA = 4‐nitro‐benzoate) has been prepared and structurally characterized. In 1, there is an interesting intermolecular structure that is shown as a tetramer copper connected in chain‐like motif. In the UV‐Vis spectrum, higher absorbance at 267 nm is referred to n → π* transition, coupled with a weak peak at 500 nm, indicating another transition, which is specified as metal‐to‐ligand charge transfer. The higher intensity peak in the photoluminescence spectrum is marked as the absorption of energy required for the excitation of electrons, whereas lower intensity peaks show the emission of energy, which describes d‐d transitions of Cu (II) electrons due to d9 configuration. Complex 1 was explored for the adsorption of methylene blue (MB) dye, with the maximum adsorption as 101.07 mg/g, whereas the removal efficiency was estimated to be 81.05%. In conformity with the kinetic studies, the adsorption process proceeded via a Pseudo‐first‐order kinetic model. The incorporation of mixed ligands such as teaH3 and pNBH in 1 tends to increase the dimensionality that led to increased MB adsorption. The plausible mechanism behind the adsorption was favored by hydrogen‐bonding, electrostatic, π–π, and n–π* interactions, operating between the dye and complex 1. Further, the H‐bonding and these interactions provided stability to the complex, and an improved dye adsorption was observed even during the 2nd and 3rd recyclability experiments. Additionally, complex 1 corroborated remarkable stability after dye adsorption, allowing for up to four recycling turns. The magnetic study revealed antiferromagnetic coupling between the two magnetic centers with a singlet ground state (S = 0).

Solving the puzzle of higher photoluminescence yield at the edges of MoS2 monolayers grown by chemical vapor deposition

Higher photoluminescence yield from the boundaries as compared to the interiors in monolayer (1L) islands of transition metal dichalcogenides grown by chemical vapor deposition (CVD) has been frequently documented in the literature. However, the detailed understanding of this phenomenon is still lacking. Here, we investigate the effect observed in CVD grown 1L-MoS2 islands on c-sapphire substrates. The study reveals a blue shift of the A-excitonic feature from the interiors to the edges of the monolayers, suggesting the release of the tensile strain, which is resulting in the interiors due to lattice and/or thermal expansion coefficient mismatch between the layer and the substrate, toward the boundaries. The degree of valley polarization is also found to increase at the edges. However, when the as-grown monolayers are transferred on a SiO2 surface, the intensity, position, and valley polarization of the A-excitonic peak do not show any inhomogeneity over the surface. The study attributes the decrease in PL intensity and the valley polarization in the interiors as compared to the edges of these as-grown islands to the reduction of the energy gap between the Γ- and K-valley valence band maxima with the increase in the tensile strain in the layer. First principles density functional theory based calculations for the geometry optimization are performed on a 1L-MoS2 flake residing on a (0001) sapphire surface, which indeed shows the relaxation of tensile strain toward the edges.