Changes In Distribution Research Articles

Wear-resistant enhanced composite coatings on TC4: Combining halide-activated pack cementation and plasma electrolytic oxidation

Enhancing the wear resistance is crucial to broadening titanium alloy application potential. In this study, we discovered that preparing a boron-infiltrated prefabricated coating using halide-activated pack cementation (HAPC) before plasma electrolytic oxidation (PEO) can significantly improve the wear resistance of TC4. The composite coatings (HAPC/PEO) produced through this method exhibit effective boron (B) penetration, with the main phase being H3BO3. We investigated the properties of HAPC/PEO and compared the wear resistance to a single PEO coating. Our results show that the hardness and modulus of elasticity of HAPC/PEO are enhanced, while its resistance to plastic deformation is increased and the coating is not easily damaged during friction. HAPC/PEO shows a 55 % decrease in the coefficient of friction and a 47 % reduction in wear rate compared to PEO coating, indicating superior wear resistance. We analyzed the stress distribution and displacement changes during friction between the PEO coating and HAPC/PEO using ABAQUS. The influence of the main phases' structure on the two coatings' wear resistance is also discussed, and the significant role of the laminated structure of H3BO3 in enhancing the wear resistance of HAPC/PEO was discovered.

Ethnicity and Observed Oxygen Saturations, Fraction of Inspired Oxygen, and Clinical Outcomes: A Post Hoc Analysis of the Oxy-PICU Trial of Conservative Oxygenation.

A conservative oxygenation strategy, targeting peripheral oxygen saturations (Spo2) between 88% and 92% in mechanically ventilated children in PICU, was associated with a shorter duration of organ support and greater survival compared with Spo2 greater than 94% in our recent Oxy-PICU trial. Spo2 monitors may overestimate arterial oxygen saturation (Sao2) in patients with higher levels of skin pigmentation compared with those with less skin pigmentation. We investigated if ethnicity was associated with changes in distributions of Spo2 and Fio2 and outcome. Post hoc analysis of a pragmatic, open-label, multicenter randomized controlled trial. Fifteen PICUs across the United Kingdom and Scotland. Children aged 38 weeks corrected gestational age to 15 years accepted to a participating PICU as an unplanned admission and receiving invasive mechanical ventilation with supplemental oxygen for abnormal gas exchange. Hierarchical regression models for Spo2 and Fio2, and ordinal models for the primary trial outcome of a composite of the duration of organ support at 30 days and death, were used to examine the effects of ethnicity, accounting for baseline Spo2, Fio2, and mean airway pressure and trial allocation. Ethnicity data were available for 1577 of 1986 eligible children, 1408 (89.3%) of which were White, Asian, or Black. Spo2 and Fio2 distributions did not vary according to Black or Asian ethnicity compared with White children. The trial primary outcome measure also did not vary significantly with ethnicity. The point estimate for the treatment effect of conservative oxygenation in Black children was 0.64 (95% CI, 0.33-1.25) compared with 0.84 (0.68-1.04) in the overall trial population. These data do not suggest that the association between improved outcomes and conservative oxygenation strategy in mechanically ventilated children in PICU is modified by ethnicity.

Ultrasonic Levitation for Airway Humidification.

This study employs the transmitter part of an ultrasonic proximity sensor to generate a powerful ultrasonic field for medical humidification. This field is created using an arrangement of small ultrasonic transmitter transducers configured in an acoustic levitator-style setup. As droplets pass through this ultrasonic field, they undergo disintegration, leading to an accelerated evaporation process. The research findings highlight a significant change in droplet size distribution due to ultrasonics, resulting in a notable increase in the rate of evaporation. As a result, this study presents a conceptual framework for reimagining humidification devices for lung therapeutic purposes through the utilization of simple sensor technology.

A guide to developing population files for physiologically-based pharmacokinetic modeling in the Simcyp Simulator.

The Simcyp Simulator is a software platform widely used in the pharmaceutical industry to conduct stochastic physiologically-based pharmacokinetic (PBPK) modeling. This approach has the advantage of combining routinely generated invitro data on drugs and drug products with knowledge of biology and physiology parameters to predict a priori potential pharmacokinetic changes in absorption, distribution, metabolism, and excretion for populations of interest. Combining such information with pharmacodynamic knowledge of drugs enables planning for potential dosage adjustment when clinical studies are feasible. Although the conduct of dedicated clinical studies in some patient groups (e.g., with hepatic or renal diseases) is part of the regulatory path for drug development, clinical studies for all permutations of covariates potentially affecting pharmacokinetics are impossible to perform. The role of PBPK in filling the latter gap is becoming more appreciated. This tutorial describes the different input parameters required for the creation of a virtual population giving robust predictions of likely changes in pharmacokinetics. It also highlights the considerations needed to qualify the models for such contexts of use. Two case studies showing the step-by-step development and application of population files for obese or morbidly obese patients and individuals with Crohn's disease are provided as the backbone of our tutorial to give some hands-on and real-world examples.

Evolution of secondary metabolites, morphological structures and associated gene expression patterns in galls induced by four closely related aphid species on a host plant species.

Gall-forming insects induce various types of galls on their host plants by altering gene expression in host plant organs, and recent studies have been conducted for gene expression in galls. However, the evolutionary trajectories of gene expression patterns and the resulting phenotypes have not yet been studied using multiple related species. We investigated the speciation and the diversification process of galls induced by four closely related aphid species (Hormaphidini) on a host plant species (Hamamelis japonica) by examining the phylogenetic congruence between the geographical divergences of aphids and the host plant, and by comparing their gene expression patterns and resulting phenotypes. Phylogenetic analysis of aphids and the host plant showed that geographical isolation among host plant populations has interrupted gene flow in aphids and accelerated the speciation process. The concentration of phenolics and the complexity of the internal structure of galls were correlated with the expression levels of genes for the biosynthesis of phenolics and morphogenesis respectively. These results suggest that the expression levels of genes for the biosynthesis of phenolics and morphogenesis have evolutionarily increased in galls accelerated by the speciation process of aphids due to the distribution change of the host plant, leading to the related phenotypic evolution. Our study showed the evolutionary process of phenotypic traits in galls in the wild from both gene expression and actual phenotype levels.

Equilibrium and kinetic modeling studies for copper and cadmium removal from aqueous solutions by ground nut husk

This study investigates the equilibrium and kinetics of copper and cadmium adsorption from aqueous solutions using groundnut husk. Characterization of the groundnut husk reveals various functional groups and a porous morphology. Isothermal studies were conducted, and different models were evaluated to fit the data. The Langmuir model exhibits the best fit for copper adsorption, while the Temkin and Dubinin–Radushkevich (DR) isotherm models show superior fitting for cadmium adsorption. Results suggest that physisorption significantly influences both cases, with mean sorption adsorption energy lower than 8000 J/mole. Error analysis reveals that the Freundlich and Temkin models demonstrate maximum adsorption capacity, with lower Chi-square (ꭓ2), Sum of Square Errors (SSE), and SAE compared to Langmuir and DR models. Additionally, intra-particle diffusion was analyzed using the Weber and Morris equation. Evaluation of model parameters indicates that cadmium demonstrates better nonlinear fitting of data compared to copper. FTIR and SEM analysis confirm the involvement of various functional groups in adsorption and reveal changes in surface distribution post-adsorption due to copper and cadmium presence.

Study on the change of global ecological distribution of Nicotiana tabacum L. based on MaxEnt model.

Nicotiana tabacum L. (tobacco) has extremely high economic value, medicinal value, scientific research value and some other uses. Though it has been widely cultivated throughout the world, classification and change of its suitable habitats is not that clear, especially in the context of global warming. In order to achieve rational cultivation and sustainable development of tobacco, current (average from 1970-2000) and future (2070, average from 2061-2080) potential suitable habitats of Nicotiana tabacum L. were forecasted with MaxEnt model and ArcGIS platform based on 854 occurrence data and 22 environmental factors in this study. The results revealed that mean temperature of warmest quarter (bio10), annual precipitation (bio12), solar radiation in September (Srad9), and clay content (CLAY) were the four decisive environment variables for the distribution of Nicotiana tabacum L. Under current climate conditions, suitable habitats of Nicotiana tabacum L. were mainly distributed in south-central Europe, south-central North America, most parts of South America, central Africa, south and southeast Asia, and southeast coast of Australia, and only 13.7% of these areas were highly suitable. By the year 2070, suitable habitats under SSP1-2.6, SSP3-7.0, and SSP5-8.5 climate scenarios would all increase with the largest increase found under SSP3-7.0 scenario, while suitable habitats would reduce under SSP2-4.5 climate scenario. Globally, the center of mass of suitable habitats would migrate to southeast to varying degrees within Libya under four different climate scenarios. The emergence of new habitats and the disappearance of old habitats would all occur simultaneously under each climate scenario, and the specific changes in each area, combined with the prediction results under current climate conditions, will provide an important reference for the adjustment of agronomic practices and rational cultivation of Nicotiana tabacum L. both currently and in the future.

Using the evolution of knowledge to explain changes in farm size distribution and specialization

Using the evolution of knowledge to explain changes in farm size distribution and specialization

Phenotypic response of a geographically expanding species, Scomber colias: Clues in the fish otolith shape

During the last decades, there has been a growing interest in the Atlantic chub mackerel, Scomber colias, owing to its northward expansion across the East Atlantic Ocean. This trend has been observed from regions of higher abundance off northwest Africa to the waters of the Atlantic Iberian and the Mediterranean Sea. Changes in abundance and spatial distribution of Atlantic chub mackerel have been previously studied and various theoretical models have been proposed to elucidate the changes in its abundance and biomass. However, within this fishing context, only a limited number of studies have attempted to understand how this species has responded at both the individual and population levels to the changing environmental conditions. The phenotypic variability of 1660 individuals of S. colias collected from the Canary Islands, Madeira, the Cantabrian Sea and the Central-Northern Mediterranean Sea was examined, with a specific focus on otolith shape. We identified six morphotypes classified into two groups and associated to the four analyzed regions. Despite of the occurrence of shared phenotypes in varying proportions among the different fishing grounds, this classification might be explained by the adaptation of certain morphotypes to specific environmental conditions and the migratory behavior of this species. The morphotypes M1-M5 were more abundant in the warmer waters of Madeira-Canary Islands region and M6 in the colder waters of Ligurian-Cantabrian. It is plausible that the former set may represent resident contingents, while morphotypes M2-M3 and M4 are likely to exhibit migratory behavior. Therefore, we suggest a complex metapopulation structure, where different contingents coexist.

Spatial-temporal characterization of cropland abandonment and its driving mechanisms in the Karst Plateau in Eastern Yunnan, China, 2001-2020.

The karst plateau is dominated by mountainous and hilly landforms, with low mechanization level of cropland, high difficulty of cultivation, and obvious phenomenon of cropland abandonment, which threatens regional food security. This study aims to analyze the spatial-temporal variation and its driving mechanisms of abandoned cropland in the Karst Plateau in Eastern Yunnan, China (KPEYC) between 2001 and 2020. To achieve this goal, 18 key factors from population, economic environment, cropland attributes, and farming conditions are selected. Moreover, correlation analysis, geodetector, and regression analysis methods are applied from three perspectives: temporal change, spatial distribution and spatial-temporal change. The results show that: (i) The cropland abandonment rate (CAR) in the KPEYC shows a fluctuating trend, with an average value of 9.78%, and the spatial distribution shows a pattern of "high in the center and low in the south and north". (ii) From the perspective of temporal change, gross value of agricultural production, and gross value of industrial production have the largest correlation coefficients with CAR. (iii) The explanatory power of gross tertiary industrial production, gross value of industrial production, followed by soil thickness. (iv) Gross value of agricultural production, and gross tertiary industrial production are the core driving forces for the spatial-temporal change of CAR. The higher the gross value of agricultural production and gross tertiary industrial production, the lower the CAR. elevation, soil thickness, and traffic mileage are the main driving factors for the spatial-temporal change of CAR. The study indicates that economic factors are decisive for cropland abandonment in the KPEYC. Based on the results, this study can provide decision-making support for local prevention and control of cropland abandonment, and the local community needs to promote land transfer and concentration and local urbanization according to local conditions, improve agricultural policies, improve farming conditions, etc. in order to increase farmers' enthusiasm for production, promote the rational use of cropland, and solidly push forward ecological restoration and management, optimize ecological spatial patterns, manage serious areas of rocky desertification, and appropriately alleviate the contradiction between people and land.

Dynamic Change Characteristics and Main Controlling Factors of Pore Gas and Water in Tight Reservoir of Yan’an Gas Field in Ordos Basin

Tight sandstone gas has become an important field of natural gas development in China. The tight sandstone gas resources of Yan’an gas field in Ordos Basin have made great progress. However, due to the complex gas–water relationship, its exploration and development have been seriously restricted. The occurrence state of water molecules in tight reservoirs, the dynamic change characteristics of gas–water two-phase seepage and its main controlling factors are still unclear. In this paper, the water-occurrence state, gas–water two-phase fluid distribution and dynamic change characteristics of different types of tight reservoir rock samples in Yan’an gas field were studied by means of water vapor isothermal adsorption experiment and nuclear magnetic resonance methane flooding experiment, and the main controlling factors were discussed. The results show that water molecules in different types of tight reservoirs mainly occur in clay minerals and their main participation is in the formation of fractured and parallel plate pores. The adsorption characteristics of water molecules conform to the Dent model; that is, the adsorption is divided into single-layer adsorption, multi-layer adsorption and capillary condensation. In mudstone, limestone and fine sandstone, water mainly occurs in small-sized pores with a diameter of 0.001 μm–0.1 μm. The dynamic change characteristics of gas and water are not obvious and no longer change under 7 MPa displacement pressure, and the gas saturation is low. The gas–water dynamic change characteristics of conglomerate and medium-coarse sandstone are obvious and no longer change under 9 MPa displacement pressure. The gas saturation is high, and the water molecules mainly exist in large-sized pores with a diameter of 0.1 μm–10 μm. The development of organic matter in tight reservoir mudstone is not conducive to the occurrence of water molecules. Clay minerals are the main reason for the high water saturation of different types of tight reservoir rocks. Tight rock reservoirs with large pore size and low clay mineral content are more conducive to natural gas migration and occurrence, which is conducive to tight sandstone gas accumulation.

Climate Change impact on Weeds and Herbicide Efficacy

Climate change is the change in statistical distribution of weather pattern that lasts for an extended period of time. There are several components of these climate changes occurring globally that includes uneven rainfall, droughts, floods, warming of atmosphere etc. These are the most important challenges influencing natural ecosystems, agricultural productivity and food security. Climate change is not only influencing crop plants and forests directly but can also impact the pests of these crops. Weeds respond to climate change by changing the duration of their life cycles, population dynamics and shift to new habitats and become a potential competitor to crop plants thereby reducing the production and productivity of crops. Elevated temperature and elevated CO2 level in the environment interfere with herbicide activity, which affects the herbicide absorption, translocation and thereby reduces the efficacy of the applied herbicide. Weeds’ resistance to herbicides may probably increase due to further aggressive growth of weeds in future climate conditions, which can cause a decline in the efficacy of routinely used herbicides.

Dependence of Growth Parameters of Atomic Chains on Changes in the Substrate Temperature

The growth and evolution of one-dimensional nanostructures on metal stepped surfaces were studied using the kinetic Monte Carlo method. The distribution of nanochain lengths was shown to change differently when the substrate was heated and cooled. Regularities are described that connect the nature of changes in the length distribution and the relative values of diffusion barriers for adatoms on the surface, which will make it possible to predict the length distribution of the resulting one-dimensional nanostructures.

Two-sample testing with local community depth

AbstractIn this paper, we investigate nonparametric two-sample hypothesis testing with local community depth, a measure of data depth calculated from pairwise distances between observations. Unlike many common “center-outwards” measures of data depth, local community depth captures local features of a distribution such as multimodality and can adapt to modes with different scales. This gives local community depth greater power to detect scale changes in multimodal distributions, and importantly the method is parameter-free. The local depth employed supplements existing adaptations of depth to local regions and is computationally cheaper in high dimensions than many classic depths such as halfspace depth, regression depth, simplicial depth, and Mahalanobis depth. We test hypotheses by using local community depth in the Liu–Singh test and give conditions under which our method is consistent against fixed alternatives (and has a limiting null distribution). In simulations and an application to diagnosing dengue fever, we show that local community depth outperforms other depths when the underlying distribution is multimodal or asymmetric, and is comparable to other methods when the data is unimodal and symmetric.

Insights into COVID-19 epidemiology and control from temporal changes in serial interval distributions in Hong Kong.

The serial interval distribution is used to approximate the generation time distribution, an essential parameter to infer the transmissibility (${R}_t$) of an epidemic. However, serial interval distributions may change as an epidemic progresses. We examined detailed contact tracing data on laboratory-confirmed cases of COVID-19 in Hong Kong during the five waves from January 2020 to July 2022. We reconstructed the transmission pairs and estimated time-varying effective serial interval distributions and factors associated with longer or shorter intervals. Finally, we assessed the biases in estimating transmissibility using constant serial interval distributions. We found clear temporal changes in mean serial interval estimates within each epidemic wave studied and across waves, with mean serial intervals ranged from 5.5 days (95% CrI: 4.4, 6.6) to 2.7 (95% CrI: 2.2, 3.2) days. The mean serial intervals shortened or lengthened over time, which were found to be closely associated with the temporal variation in COVID-19 case profiles and public health and social measures and could lead to the biases in predicting ${R}_t$. Accounting for the impact of these factors, the time-varying quantification of serial interval distributions could lead to improved estimation of ${R}_t$, and provide additional insights into the impact of public health measures on transmission.

Research on Temperature Distribution and Gradient Prediction of U-Shaped Girder Bridge under Solar Radiation Effect

With the development of bridge engineering, U-shaped girder bridges have been applied in numerous bridge designs due to their structural characteristics. However, the U-shaped girder bridge is sensitive to solar radiation effects, leading to uneven temperature distributions that can affect the service performance of the structure. Thus, this study proposes an analysis method for the temperature distribution of U-shaped girder bridges and develops a prediction model to estimate temperature gradients. First, an improved ASHRAE clear sky model is proposed to calculate the structural shadow areas under sunlight, which provides a basis for the numerical simulation of U-shaped girder bridges under solar radiation effect. Then, a three-dimensional finite element model of the U-shaped girder bridge is established, and its correctness is verified by comparing with the actual temperature data. The temperature distribution of the U-shaped girder bridge under solar radiation is simulated using the verified model to obtain the maximum temperature difference and temperature variation characteristics. Finally, a prediction model for the temperature gradient is developed using nonlinear fitting approaches, and its accuracy is confirmed through comparison with actual data. The results indicate that the temperature distribution of the U-shaped girder bridge has minor changes along the longitudinal direction, while there are significant changes in the transverse distribution; the temperature distribution exhibits nonlinear changes in the height direction of the two side webs and the lateral direction of the bottom slab, with the maximum temperature difference reaching 17 °C; the fitting effect of the prediction model is very good, the correlation coefficients of the fitting curve and the actual data are all greater than 88%, providing a basis for the analysis of the temperature effects on U-shaped girder bridges and its application in design specifications.

Sexual dimorphism in the dwarf round ray Urotrygon nana.

This paper presents information on the morphological, morphometric, and dental sex differences in the dwarf round ray Urotrygon nana. We recorded 12 morphological traits, sex, the distribution pattern of dermal denticles, the number of tooth rows, and the tooth shape of 466 individuals. The disc width of females ranged from 50 to 172 mm and that of males ranged from 53 to 135 mm. A neuronal classification model and a correspondence analysis showed that female disc width was 21.5% broader, and the distance from the rostrum to the anus was 17.7% longer than that of males, whereas males presented 19.5% greater distance between the nostrils, 9.7% greater preorbital snout length, 6.8% greater cloaca to caudal-fin length, 2.7% greater interorbital distance, and 1.1% greater total length than females. The disc of adult males, including the abdominal cavity area, was densely covered with dermal denticles, which were slightly larger than those observed in females. Females presented homodont dentition with molariform teeth and a smooth lozenge-shaped crown with rounded margins. Males exhibited homodonty but with tooth morphology variations in individuals of different sizes (from molariforms to sharper cusp teeth). There were changes in disc shape (from subcircular to oval), distribution and size of dermal denticles (more abundant and larger), and tooth shape (from molariform to monocuspid teeth) during male development, from neonates to adults. U. nana exhibited sexual dimorphism in size, disc shape, number and shape of teeth, and distribution and size of dermal denticles.

Unlocking guanine’s potential: Unveiling electronic transitions and nanoelectronic applications through electric field modulation

Guanines, key players in DNA and RNA, exist as dynamic keto and enol forms, influencing reactivity and potential applications. This study explores the impact of external electric fields on these forms using computational methods in gas and solvent (water) phases. Analyzing the energy gap, dipole moment, enthalpy, and Gibbs free energy revealed distinct responses. The keto form showed a significant decrease in the energy gap in the presence of an electric field, particularly in water, indicating enhanced reactivity. Conversely, the enol form exhibited a stabilizing effect with increasing electric field strength. Thermodynamic properties highlighted solvent-dependent interactions and electric field-induced changes in electron density distribution. The study further investigated guanine’s potential for nanoelectronics by calculating I-V curves, revealing promising characteristics, especially for the keto form in the aqueous phase. Additionally, the analysis of solvation and cohesive energies provided insights into solute–solvent interactions and intrinsic molecular stability. Overall, this research contributes to understanding how guanine responds to electric fields, paving the way for novel guanine-based materials with potential applications in nanoelectronics.

Bipolar electrochemical sensor with perylene diimide-based cathodic luminophore for dopamine detection and imaging

Bipolar electrochemical microscopy (BEM), which visualizes the concentration distribution of molecular species in biological systems by electrochemiluminescence (ECL), is expected to be applied to the high-spatiotemporal-resolution imaging of biomolecules, enabling the analysis of cellular functions. In the past, the molecular species that could be imaged by BEM were generally restricted to oxidized molecules due to the limitation derived from the ECL mechanism of the luminophore. Recently, the imaging of dopamine (DA), a reduced molecule, was achieved using Ru (bpy)32+/glutathione disulfide (GSSG) as a cathodic luminophore. However, a large driving voltage was required for ECL generation, resulting in a low S/N ratio. In this study, we employed N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide (PDI-CH3)/potassium peroxodisulfate (K2S2O8), which is a cathodic luminophore that can be reduced at a nobler potential to produce ECL than [Ru(bpy)3]2+/GSSG. First, the ECL mechanism of PDI-CH3/K2S2O8 was elucidated by using a PDI-CH3 drop-cast glassy carbon electrode (GCE) immersed in K2S2O8 solution as the working electrode in a 3-electrode system. The PDI-CH3 drop-casted GCE, a single closed bipolar electrode (c-BPE), was used as the cathode in the successful quantification of 50–500 μmol L−1 DA in a sample chamber in which a c-BPE anode was immersed, resulting in a high S/N. The selective detection of DA in the presence of ascorbic acid was achieved by modifying the anode with Nafion. Finally, DA imaging was demonstrated using a commercially available anisotropic conducting film with PDI-CH3 coating on the cathode surface as a c-BPE array. The change in the concentration distribution in the inflow of DA was successfully imaged based on the change in the ECL intensity at the c-BPE cathode. This BEM system is expected to be useful for DA imaging of the brain.

Experimental investigation on sedimentation characteristics of coastal slurry by flocculation

Coastal waste slurry has a negative impact on the environment due to its slow, natural settling characteristics. In this study, the organic, inorganic, and composite flocculants were applied to improve the mud-water separation performance. A series of experiments with sedimentation columns and particle size analysis were conducted to investigate the effects of flocculant type, dosage and combination on slurry settling rates and its associated mechanisms. The experimental results show that different types of flocculants varied in improving the settling efficiency of slurry, while the flocculation effect of inorganic flocculants is relatively poor. The settling efficiency of organic polymer flocculants on slurry is in order of anionic polyacrylamide (APAM) > cationic polyacrylamide (CPAM) > nonionic polyacrylamide (PAM), with their optimal dosage 0.2%, 0.1%, and 0.1%, respectively. Moreover, the combination of APAM and Solid Polymeric Ferric Sulfate (SPFS) can further improve the efficiency of mud-water separation by enhancing electro-neutralization and net sweeping capability. Subsequently, the change in the particle size distribution of the slurry demonstrates that flocculation causes the aggregation of fine particles in slurry to form coarse particles. These findings have implications for improving the sedimentation characteristics of waste slurry to reduce environmental pollution.