Crossover Point Research Articles

Ozone Doping and Negative Temperature Response in the Explosion Limits of Ethylene-Oxygen Mixtures.

In this work, effects of ozone (O3) addition on ethylene-oxygen (C2H4-O2) mixtures are computationally studied through the explosion limit profiles. The results show that the addition of minute quantities of ozone (with a mole fraction of 0.06% in the oxidizer) shifts the explosion limit of the C2H4-O3-O2 mixtures to the low-temperature regime. Further increases in the ozone concentration gradually strengthen the negative temperature coefficient (NTC) behavior at the second limit. That is because the explosion limit is primarily controlled by the ethylene ozonolysis reaction, and both the sensitivity analysis and chemical reaction rate perturbation method reveal specific kinetic reasons. Furthermore, it is shown that with the increasing equivalence ratio, the explosion limit curve with minute ozone addition rotates counterclockwise around a crossover point, while the explosion limit curve becomes complicated and the NTC behavior appears on the second limit with larger quantities of ozone addition. Furthermore, the effects of dilutions of nitrogen (N2), argon (Ar), carbon dioxide (CO2), and water (H2O) on the explosion limits are also studied. To elucidate the different wall elimination effects of different explosion limit regimes, the impacts of surface reactions of six radicals (H, O, OH, HO2, H2O2, and HCO) have been examined and the dominant radicals are found to be H and HO2. The H radicals significantly influence the first explosion limit, while the HO2 radicals impact the entire explosion limit.

Analyzing TVB-N in snakehead by Bayesian-optimized 1D-CNN using molecular vibrational spectroscopic techniques: Near-infrared and Raman spectroscopy

Total volatile basic nitrogen (TVB-N) is one of the key indicators for assessing fish freshness. This research employed near-infrared (NIR) and Raman spectroscopy methods to detect the TVB-N content in snakehead fillets. We extracted feature variables associated with TVB-N from NIR and Raman spectroscopy using Variable Crossover Point Arithmetic - Improved Reduced-Input Vector (VCPA-IRIV). Using these features, we established partial least squares (PLS) and One-dimensional Convolutional Neural Network (1D-CNN) models. Subsequently, data fusion strategies were employed to predict the TVB-N content. Notably, feature-level fusion in conjunction with Bayesian-optimized 1D-CNN, reached the best results, as evidenced by calibration and predictive correlation coefficients of 0.9677 and 0.9676 for TVB-N. These findings underscore the effectiveness of both NIR and Raman spectroscopy in evaluating fish freshness. The fusion of these two vibrational spectroscopy techniques enables a more rapid, efficient and comprehensive quantification of fish freshness.

Accelerated Nanocomposite Hydrogel Gelation Times Independent of Gold Nanoparticle Ligand Functionality.

The expansive use of hydrogels in healthcare relies on carefully tuned properties in dynamic environments with predictable behavior, including time sensitive biological systems and biomedical applications. To meet demands in these settings, nanomaterials are often introduced to a hydrogel matrix which simultaneously elevates potential applications while adding complexity to fundamental characteristics. With respect to drug delivery, gold nanoparticles have modifiable surfaces to carry an array of targeted drug treatments. However, different molecules acting as capping ligands possess different chemical structures that can impact gelation times. To understand the influence of capping ligand chemistry on polyacrylamide (PAM) based nanocomposite hydrogel radical gelation time, gold nanoparticle (Au NP) capping ligands were selected to encompass varying functional groups and molecular weights: citrate, cetyltrimethylammonium bromide, polyvinylpyrrolidone, and poly(acrylic acid). Gelation times were quantified as the storage-loss moduli crossover point in rheological time sweeps at constant strain and frequency. The dominating factor for gelation time was the presence of Au NPs, independent of a diverse range of capping ligand structures. The gelation times were also markedly faster than the same capping ligand structures used as stand-alone molecular additives. The accelerated Au NP gelation times, under 2 min, are attributed to the Au NPs acting as a cross-linker, promoting gelation. These results bolster the potential implementation of Au NP nanocomposite hydrogels in time-sensitive biomedical applications as robust drug carriers.

Seismic response of deep soft soil sites with varying shear wave velocities

The variations in seismic response between deep soft soil sites with different shear wave velocities were not fully understood. This study focuses on the seismic response of deep soft soil sites in the lower reaches of the Yangtze River, China. A nonlinear dynamic finite element model was developed for two representative deep soft soil sites with borehole profiles and the shear wave velocity tested by the single borehole method. Two nonlinear cyclic constitutive models are used and thus compared through the site seismic response. To accurately calibrate the nonlinear cyclic model parameters, resonant column tests were conducted on 21 soil samples collected from the two boreholes. The results show that the peak ground acceleration (PGA) under low-frequency (Liuan) input motion was higher for soft soil sites compared to that under medium- and high-frequency (Kobe and Nahanni) input motions. The PGA amplification factor for deep soft soil sites under different input motions can be approximated by an exponential function. The peak ground acceleration tends to be lower as the equivalent shear wave velocity (Vse) decreases. The shapes of the spectral acceleration were similar for the two sites, despite a substantial difference in the Vse between them. Additionally, a crossover point was observed in the spectral acceleration for the two sites. The period corresponding to this crossover point increased with increasing intensity of input motions, indicating that the sites became softer with higher intensity and thus generally exhibited a longer characteristic period of the spectral acceleration. This paper also highlights the significance of selecting nonlinear constitutive models and the precise calibration of model parameters in the seismic response analysis of deep soft soil sites, providing a scientific basis for future similar site analyses.

Effects of OpenCL-Based Parallelization Methods on Explicit Numerical Methods to Solve the Heat Equation

In recent years, the need for high-performance computing solutions has increased due to the growing complexity of computational tasks. The use of parallel processing techniques has become essential to address this demand. In this study, an Open Computing Language (OpenCL)-based parallelization algorithm is implemented for the Constant Neighbors (CNe) and CNe with Predictor–Corrector (CpC) numerical methods, which are recently developed explicit and stable numerical algorithms to solve the heat conduction equation. The CPU time and error rate performance of these two methods are compared with the sequential implementation and Euler’s explicit method. The results demonstrate that the parallel version’s CPU time remains nearly constant under the examined circumstances, regardless of the number of spatial mesh points. This leads to a remarkable speed advantage over the sequential version for larger data point counts. Furthermore, the impact of the number of timesteps on the crossover point where the parallel version becomes faster than the sequential one is investigated.

Multifractal Analysis of the Impact of Fuel Cell Introduction in the Korean Electricity Market

This study employs multifractal detrended fluctuation analysis to investigate the impact of fuel cell introduction in the Korean electricity market via the lens of multifractal scaling behavior. Using multifractal analysis, the research delineates discrepancies between peak and off-peak hours, accounting for the daily cyclicity of the electricity market, and proposes a crossover point detection method based on the Chow test. Furthermore, the impacts of fuel cell introduction are evidenced through various methods that encompass multifractal spectra and market efficiency. The findings initially indicate a higher degree of multifractality during off-peak hours relative to peak hours. In particular, the crossover points emerged solely during off-peak hours, unveiling short- and long-term dynamics predicated on a near-annual cycle. Additionally, the average Hurst exponent for the short-term was 0.542, while the average for the long-term was 0.098, representing a notable discrepancy. The introduction of fuel cells attenuated the heterogeneity in the scaling behavior, which is potentially attributable to the decreased volatility in both the supply and demand spectra. Remarkably, after the introduction of fuel cells, there was a discernible decrease in the influence of long-range correlation within multifractality, and the market exhibited an increased propensity toward random-walk behavior. This phenomenon was also detected in the market deficiency measure, from an average of 0.536, prior to the introduction, to an average of 0.267, following the introduction, signifying an improvement in market efficiency. This implies that the introduction of fuel cells into the market engendered increased supply stability and a consistent increase in demand, mitigating volatility on both the supply and demand sides, thus increasing market efficiency.

Unified theory for the scaling of the crossover between strong and weak disorder behaviors of optimal paths and directed or undirected polymers in disordered media.

In this paper, we are concerned with the crossover between strong disorder (SD) and weak disorder (WD) behaviors in three well-known problems that involve minimal paths: directed polymers (directed paths with fixed starting point and length), optimal paths (undirected paths with a fixed end-to-end or spanning distance), and undirected polymers (undirected paths with a fixed starting point and length). We present a unified theoretical framework from which we can easily deduce the scaling of the crossover point of each problem in an arbitrary dimension. Our theory is based on the fact that the SD limit behavior of these systems is closely related to the corresponding percolation problem. As a result, the properties of those minimal paths are completely controlled by the so-called red bonds of percolation theory. Our model is first addressed numerically and then approximated by a two-term approach. This approach provides us with an analytical expression that seems to be reasonably accurate. The results are in perfect agreement with our simulations and with most of the results reported in related works. Our research also leads us to propose this crossover point as a universal measure of the disorder strength in each case. Interestingly, that measure depends on both the statistical properties of the disorder and the topological properties of the network.

Dependency of crossover point on absorption changes in bilayer diffusion reflection measurements.

A better understanding of diffusion reflection (DR) behavior may allow it to be used for more noninvasive applications, including the development of in vivo non-damaging techniques, especially for medical topical diagnosis and treatments. For a bilayer opaque substance where the attenuation of the upper layer is larger than the attenuation of the lower layer, the DR crossover point ( ) is location where the photons coming from the bottom layer start affecting the DR. We aim to study the dependency of the on absorption changes in different layers for constant scattering and top layer thickness. Monolayer and bilayer optical tissue-like phantoms were prepared and measured using a DR system. The results were compared with Monte Carlo simulations. There is an agreement between the experiments and the simulations. correlates with the square root of the absorption coefficient ratio of the lower layer to the top layer. The experimental findings support and validate the theoretical prediction describing the dependency of the on the square root of the ratio of the layers' absorption coefficients. In addition, a secondary breaking point is suggested to be observed experimentally at the entrance to the noise area.

Valley landau level crossings in weakly coupled bilayer WSe2

Abstract WSe2 is a p-type 2D-semiconductor that can be mechanically exfoliated down to atomic layers. Unlike the Bernal stacked bilayer graphene, the two layers in a bilayer WSe2 flake are weakly coupled. The electric displacement field can easily break the layer degeneracy of the bilayer WSe2. Together with the strong spin–orbit coupling, it exhibits many novel quantum physical properties. In this work, we fabricate high quality dual-gated bilayer WSe2 devices and observe twofold degenerate Landau levels(LLs) and density-dependent quantum Hall states which show transitions between even and odd filling. When introducing carriers into the system from the valence band edge by gating, two WSe2 layers are filled independently and the bottom layer WSe2 shows negative compressibility at the crossover point. Above 9 T, we observe the degeneracy of LLs is completely broken and there are two sets of LL crossings in the top WSe2 layer at Zeeman-to-cyclotron energy ratio E Z / E N ≈ 4 and E Z / E N ≈ 5. The interplay between two LLs from the two WSe2 layers confirms the weak coupling between them. Our results show that the bilayer WSe2 behave like two closely packed independent electronic systems under electric displacement fields.

Impact of Hearing Aid Processing Delay on Stop Consonant Voicing Perception in Open Fittings.

Hearing aid (HA) processing delay results in asynchronous overlap of the input sound and the delayed amplified sound at the eardrum in open-ear fittings. This may distort the temporal cues used for stop-consonant voicing distinctions. The current study evaluated the impact of HA processing delay on voiced-voiceless categorization of syllable initial consonants /d/ and /t/ for a range of voice onset times (VOTs). Nineteen older listeners (Mage = 73 years) with mild-moderate sensorineural hearing loss participated. All listeners performed the voiced-voiceless categorization task in double-blind within-subjects design. Thirteen stimulus tokens along the /di:/ - /ti:/ continuum were created by varying VOTs. Stimuli were then processed using an HA simulator, which simulated the overall sound pressure levels measured at the eardrum in open-ear fittings with four processing delay times (0, 0.5, 5, and 8 ms). Individualized stimuli were generated for each listener based on their audiogram and presented via calibrated ear inserts at the most comfortable listening level. Performance across all VOT intervals was fitted with psychometric functions, which were then used to estimate the voiced-voiceless crossover point and the slope parameter for each simulated delay condition. The crossover point along the voiced-voiceless continuum shifted systematically with increased processing delay toward voiced /di:/ over unvoiced /ti:/ percepts. The shift in the crossover point between the 0-ms reference condition and the 8-ms processing delay condition corresponded to 5.8 ms of change in VOT. The 8-ms processing delay condition resulted in significantly shallower categorization slopes compared to the 0- and 0.5-ms delay conditions. Temporal distortions created by HA processing delay in open-ear fittings impacted voicing perception of syllable initial stop-consonant stimuli near the voiced-voiceless crossover point. Short HA processing delay should be considered for open-ear fittings to preserve the natural VOT cues used for voicing detection.

Spin magnetotransport in rare-earth iron garnet (REIG)/Pt: Effects of modulated bulk and REIG/Pt interfaces

The intrinsic magnetization compensation behaviors of rare-earth iron garnets (REIGs) make the material promising for applications in ultrafast spin storage devices. REIG/heavy metal heterostructures such as TbIG/Pt often display two sign crossovers of anomalous Hall effect resistance with varying temperatures. One of these crossovers is attributed to the magnetization compensation of REIG, and the other to the competition between the magnetic proximity effect and the spin Hall effect. Here, we design trilayer REIG heterostructures based on two rare-earth species (Tb and Eu). We modulate the layer stacking of the TbIG/EuIG/TbIG sandwich with a fixed total thickness and explore the contributions of REIG bulk and REIG/Pt interfaces on these two crossover points. As TbIG gradually moves away from Pt, the compensation temperature shows some fluctuations. However, when TbIG is entirely out of contact with Pt, the second crossover point undergoes a change that shows REIG/Pt interface dependency. The results highlight the dominance of REIG bulk on the compensation behavior and the interface sensitivity of the second crossover point. This study provides a reference for designing controllable spintronics devices, such as magnon valve applications.

Comparative Analysis of the Irradiation with Medium Fluences of High-Energy Electrons and Pr Doping on the Fluctuation Conductivity of YBa2Cu3O7–δ Single Crystals

Medium-fluence fast electron irradiation (1019 e/cm2 to 1020 e/cm2) or the changes in the praseodymium concentration in the range of 0.0 ≤ z ≤ 0.5 on the excess conductivity of YBa2Cu3O7–δ single crystals ware investigated. These can lead to a wider range of the temperature interval of excess conductivity which narrows the interval of linearity in the ab plane. At fluences 0 ≤ Φ ≤ 6.5 × 1019 e/cm2, there was a threefold increase in the transverse coherence length ξc(0) with an increase in Φ of more than four times as the praseodymium concentration increased to z ≈ 0.42. The two-dimensional–three-dimensional (2D–3D) crossover point shifted upward in temperature. Conversely, to irradiation with low fluences (Φ ≤ 1019 e/cm2) or low praseodymium doping (z ≤ 0.39), irradiation with medium fluences or high praseodymium doping led to a non-monotonic dependence of ξc(0) on the irradiation fluence, with characteristic maxima at Φ~(7–8) × 1019 e/cm2 and z ≈ 0.42, likely due to the suppression of the superconducting characteristics.

Canonical and noncanonical roles of Hop1 are crucial for meiotic prophase in the fungus Sordaria macrospora.

We show here that in the fungus Sordaria macrospora, the meiosis-specific HORMA-domain protein Hop1 is not essential for the basic early events of chromosome axis development, recombination initiation, or recombination-mediated homolog coalignment/pairing. In striking contrast, Hop1 plays a critical role at the leptotene/zygotene transition which is defined by transition from pairing to synaptonemal complex (SC) formation. During this transition, Hop1 is required for maintenance of normal axis structure, formation of SC from telomere to telomere, and development of recombination foci. These hop1Δ mutant defects are DSB dependent and require Sme4/Zip1-mediated progression of the interhomolog interaction program, potentially via a pre-SC role. The same phenotype occurs not only in hop1Δ but also in absence of the cohesin Rec8 and in spo76-1, a non-null mutant of cohesin-associated Spo76/Pds5. Thus, Hop1 and cohesins collaborate at this crucial step of meiotic prophase. In addition, analysis of 4 non-null mutants that lack this transition defect reveals that Hop1 also plays important roles in modulation of axis length, homolog-axis juxtaposition, interlock resolution, and spreading of the crossover interference signal. Finally, unexpected variations in crossover density point to the existence of effects that both enhance and limit crossover formation. Links to previously described roles of the protein in other organisms are discussed.

Starch exploration in Nelumbo nucifera and Trapa natans: Understanding physicochemical and functional variations for future perspectives

The current research emphasis on identifying unconventional starch sources with varied properties to broaden industrial applications. The focus of this research is on the search for alternative sources of starch with different properties in order to expand their potential use in the industrial sector. Starch was extracted from Trapa natans and Nelumbo nucifera and analyzed for their physicochemical and functional properties. They had similar protein (0.35 %) and ash contents, but the nitrogen-free extract was slightly higher in Nelumbo starch (87.58 %) than in Trapa starch (85.09 %). The amylose and amylopectin contents were 23.89 % and 76.11 % in Trapa starch and 15.70 % and 84.30 % in Nelumbo starch, respectively. Fourier-transform infrared spectroscopy identified both as polysaccharides. The characteristic absorption bands assigned to the stretching of OH groups (3324 cm−1; 3280 cm−1), the asymmetric and symmetric stretching of aliphatic chain groups (2925 cm−1; 2854 cm−1), the bending vibration of CHO groups (1149 cm−1; 1144 cm−1) were present in both the starch samples, with the exception of CH3 which could not be detected in Trapa natans starch. X-ray diffraction confirmed hexagonal and orthorhombic crystal structures in Nelumbo nucifera and Trapa natans starch. Scanning electron microscopy revealed a smooth oval and a rough cuboidal shape for lotus and chestnut starch, respectively. Rheological analysis showed that both starch solutions exhibited gel behavior, with Trapa showing stronger gel behavior after the crossover point. These results suggest potential applications in various industries, including the food industry and beyond.

Subsurface Mapping of Groundwater Contamination Pathway at Using Very Low Frequency Electromagnetic Method at Waste Site of Kubanni Basin, Zaria, Kaduna State

Subsurface Mapping of Groundwater Contamination Pathway at Using Very Low Frequency Electromagnetic Method at Waste Site of Kubanni Basin, Zaria, Kaduna State

Diet Affects the Temperature-Size Relationship in the Blowfly Aldrichina grahami.

In warmer environments, most ectotherms exhibit a plastic reduction in body size (the temperature-size rule, TSR). However, in such environments, growth is usually accelerated and would be expected to result in maturation at a larger body size, leading to increases in fecundity, survival, and mating success, compared to maturation at a smaller size (the 'life-history puzzle'). To explore these mechanisms, we reared Aldrichina grahami at 20 °C, 25 °C, and 30 °C, and added a nutritional challenge by using dilutions of pork liver paste to provide diets that ranged in quality from high (undiluted) to moderate (1/8), low (1/16), and poor (1/24). Larvae were randomly sampled for weighing from hatching. Growth curves were fitted to the relationships between growth rate and weight for the third instar larvae. Our results showed that body size was affected by an interaction between temperature and diet, and that following or not following the TSR can vary depending on underfeeding. Moreover, when the TSR was followed as temperature increased, there was a cross-over point that divided the two growth curves into early and later stages, which could be used to help understand the life-history puzzle in warmer temperatures, with the instantaneous growth rate being faster in the early stages of development and then slower in later stages. This study reminds us that animals have evolved to cope with multiple simultaneous environmental changes, and it has thus offered a better understanding of life-history puzzles.

Reassessing iron–gallium recombination activity in silicon

In this work, we present a comprehensive re-evaluation of the iron–gallium (FeGa) recombination parameters in silicon using injection-dependent lifetime spectroscopy (IDLS). Ga-doped silicon wafers (of varying resistivities) with precise concentrations of intentional iron contamination in the silicon wafer bulk, through ion implantation and distribution, were used. The presence of interstitial Fei and FeGa, and their lifetime-limiting effects in these silicon wafers, were confirmed through measuring the effective minority carrier lifetime changes during the conditions that are known to cause FeGa dissociation and association. The presence of Fe was also confirmed by deep-level transient spectroscopy. To ensure accurate IDLS analysis of the FeGa defect in silicon, a lifetime linearization scheme was employed to effectively filter out interference by other defects. Error analysis was employed to find the combination of defect parameters that best fit the experimental data and to ascertain the range of uncertainty associated with the IDLS best-fit results. The optimal fitting of the experimental IDLS by Shockley–Read–Hall statistics produced an electron capture cross section σn=2.3×10−14cm2, hole capture cross section σp=1.1×10−14cm2, and a trap energy level Et=EV+0.2−0.01+0.02eV for the FeGa defect in silicon. The extracted defect parameters are also verified by experimentally measuring the crossover point of Fei and FeGa lifetime curves.

Влияние органического вещества и влажности на пересечение спектров диэлектрической проницаемости поч

The present study considers the crossover of the real part spectra of the complex dielectric constant obtained in the frequency range from 15 MHz to 15 GHz and temperature range from 0 to 25 °C for moist organic soils with the content of organic matter varying from 11 to 54 %. Based on the obtained experimental dependences, the empirical model is proposed to estimate the average value of the frequencies at which the crossover point of the soil dielectric constant spectra are observed with temperature changes. The proposed model also includes a formula for calculating the value of volumetric moisture at which the crossover point of the soil dielectric constant spectra appears.

FT-IR combined with oscillatory rheology: How to evaluate chemical structure of ester derivatives of MA-containing compatibilizers

Ester derivatives of experimental olefin-maleic anhydride copolymers synthesized at the University of Pannonia have been investigated by both classical and instrumental analytical methods that contribute to a deeper understanding of how that type of additives functions as compatibilizers for plastics and rubbers.Titration-based acid and saponification numbers have provided limited information about the chemical structure of the experimental copolymer compounds. A prompt, precise and low-cost method or combination of methods has been required to access to the ratio of the various derivatives not only straight after esterification but also for quality control during long-term storage considering the even stricter sustainability aspects either. Reproduction and scaling-up synthesises can be also followed by the combined measuring techniques of Fourier-transform infrared spectroscopy (FT-IR) and oscillatory rheometry. Structural changes occurred in the additives could be followed through monitoring their Ester Indices (EI) during the measurement, which can be connected also to the long-term properties. Experimental additives (AD) like AD-1 and AD-2 types with lower EI values of 21.5 % and 32.1 %, respectively, resulted in higher upper limits of the linear viscoelastic (LVE) range (15 % and 10 %). Conversely, the higher EI values of AD-3 and AD-4 led to significantly lower or even immeasurable upper limits of the LVE range. Additives with solid behaviour showed slight dependence on frequency above the crossover point that indicated strong connections disappearing.

Expansion Kinetics of Flexible Polymers upon Release from a Disk-Shaped Confinement.

A general theory is developed to explain the expansion kinetics of a polymer released from a confining cavity in a d-dimensional space. At beginning, the decompressed chain undergoes an explosive expansion while keeping the structure resembling a sphere. As the process continues, the chain transitions to a coil conformation, and the expansion significantly slows down. The kinetics are derived by applying Onsager's variational principle. Computer simulations are then conducted in a quasi-two-dimensional space to verify the theory. The average expansion of the chain size exhibits a distinctive sigmoidal variation on a logarithmic scale, characterized by two times and associated exponents that represent the fast and the slow dynamics, respectively. Through an analysis of the kinetic state diagrams, two important universal behaviors are discovered in the two expansion stages. The intersection of the expansion speed curves allows us to define the crossover point between the stages and study its properties. The scaling relations of the characteristic times and exponents are thoroughly investigated under different confining conditions, with the results strongly supporting the theory. Additional calculations conducted in a three-dimensional (3D) space demonstrate the robustness of the proposed theory in describing the kinetics of polymer expansion in both 2D and 3D spaces.