Partitioning Mechanism Research Articles

Enhanced remediation of naphthalene from aqueous solutions using synthesized organoclay: characterization, mechanisms, and isotherms.

Water contamination by polycyclic aromatic hydrocarbons (PAHs), particularly naphthalene, is a serious environmental concern due to its persistence, bioaccumulation, and toxicity. This study explores the adsorption behavior of naphthalene using organobentonite (OBt), synthesized by intercalating cetyltrimethylammonium bromide (CTAB) into sodium bentonite (SBt) with varying cation exchange capacities (CECs). The effectiveness of OBt in naphthalene adsorption was evaluated by analyzing key parameters, including CEC, contaminant concentration, and contact time. The morphological and structural properties of all adsorbents were characterized before and after the adsorption process. The results demonstrated a significant improvement in the adsorption capacity of OBt compared to SBt, with a maximum naphthalene adsorption capacity of 14.08mg/g at 2.0 CEC, versus 5.22mg/g for SBt. The Freundlich isotherm model provided the best fit for adsorption data (R2 > 0.97), indicating that the partitioning mechanism primarily governed the process. CTAB-modified OBt showed enhanced hydrophobicity, larger basal spacing, and faster adsorption kinetics, with most naphthalene removal occurring within the first 15min. These findings indicated that OBt, due to its improved adsorption efficiency, rapid kinetics, and cost-effectiveness, is a promising adsorbent that can enhance the remediation of hydrophobic organic pollutants from contaminated water.

SANet: Selective Aggregation Network for unsupervised object re-identification

Recent advancements in unsupervised object re-identification have witnessed remarkable progress, which usually focuses on capturing fine-grained semantic information through partitioning or relying on auxiliary networks for optimizing label consistency. However, incorporating extra complex partitioning mechanisms and models leads to non-negligible optimization difficulties, resulting in limited performance gains. To address these problems, this paper presents a Selective Aggregation Network (SANet) to obtain high-quality features and labels for unsupervised object re-identification, which explores primitive fine-grained information of large-scale pre-trained models such as CLIP and designs customized modifications. Specifically, we propose an adaptive selective aggregation module that chooses a set of tokens based on CLIP’s attention scores to aggregate discriminative global features. Built upon the representations output by the adaptive selective aggregation module, we design a dynamic weighted clustering algorithm to obtain accurate confidence-weighted pseudo-class centers for contrastive learning. In addition, a dual confidence judgment strategy is introduced to refine and correct the pseudo-labels by assigning three categories of samples through their noise degree. By this means, the proposed SANet enables discriminative feature extraction and clustering refinement for more precise classification without complex architectures such as feature partitioning or auxiliary models. Extensive experiments on existing standard unsupervised object re-identification benchmarks, including Market1501, MSMT17, and Veri776, demonstrate the effectiveness of the proposed SANet method, and SANet achieves state-of-the-art results over other strong competitors.

Quantifying steric, non-steric, and adsorption contributions to solute rejection in covalent organic framework nanofiltration membranes

Solute transport in nanofiltration (NF) membrane systems is described with the Donnan Steric Pore Model with Dielectric Exclusion (DSPM-DE), which couples size- and charge-based solute partitioning mechanisms into and out of the membrane pores with flow through the pore, as described by the Extended Nernst-Planck equation. If membrane structural and chemical characteristics are well defined, the DSPM-DE can theoretically be used to identify solute rejection mechanisms, predict NF performance, and guide membrane design. However, the presence of additional separation mechanisms, like adsorption, and the heterogeneous, convoluted characteristics of traditional NF membranes challenge these goals. In this work, we apply covalent organic frameworks (COFs) as model NF materials to demonstrate control over the steric and non-steric partitioning and transport mechanisms in NF. We experimentally isolate and quantify the steric and non-steric contributions to solute partitioning and transport in NF via application of the DSPM-DE to COF membranes fabricated with tailored pore sizes, thicknesses, and charge properties. We also demonstrate enhanced non-steric solute rejection achieved through changes to COF membrane structure and chemistry, and we highlight the significant impact of adsorption on measured solute rejection by COF membranes.

Absorption and partitioning mechanism of nitrogen oxides by typical greening species of tree in Beijing

In this study, we analyzed the uptake of nitrogen dioxide (NO2) and its processes of distribution in various organs of different typical greening species of trees and the differences in its uptake by these different species using the 15N stable isotope tracer method under the gradient of three NO2 concentration treatments, namely, low, medium and high. These experiments were conducted using one-time artificial fumigation to provide necessary data and theoretical support for the selection and application of species of greening trees in urban gardens. The treatments of fumigation with different concentrations of NO2 showed that the leaves of the six species of trees had the highest content of 15N. The organs that were the most effective at taking up 15N were the leaves in broadleaf trees and the branches in conifers. The content of 15N per unit of the leaves (0.0058–2.0486 μg/g) increased in parallel with the concentration of fumigant and then was rapidly transported to various organs in the tree. This caused different degrees of changes in other organs. The total content of 15N per unit was higher in the broadleaf species (0.0129–2.3171 μg/g) than in the conifers (0.0296–0.1260 μg/g). The leaves of broadleaf trees were the most effective at taking up 15N (0.0054–1.3228 %) under medium and high concentrations of fumigant with the exception of ginkgo. The ability of each organ of the other broadleaf species was leaves>branches>trunks>roots, and the branches of conifers were the most effective parts of the trees at taking up NO2 under three concentrations of fumigants (0.0789–0.4005 %). The highest rate of distribution of 15N was found in the leaves (48.14–99.53 %) in all six species under different concentrations of fumigant, and the distribution in the other organs varied to different degrees.

Enhanced local multi-windows attention network for lightweight image super-resolution

Since the global self-attention mechanism can capture long-distance dependencies well, Transformer-based methods have achieved remarkable performance in many vision tasks, including single-image super-resolution (SISR). However, there are strong local self-similarities in images, if the global self-attention mechanism is still used for image processing, it may lead to excessive use of computing resources on parts of the image with weak correlation. Especially in the high-resolution large-size image, the global self-attention will lead to a large number of redundant calculations. To solve this problem, we propose the Enhanced Local Multi-windows Attention Network (ELMA), which contains two main designs. First, different from the traditional self-attention based on square window partition, we propose a Multi-windows Self-Attention (M-WSA) which uses a new window partitioning mechanism to obtain different types of local long-distance dependencies. Compared with original self-attention mechanisms commonly used in other SR networks, M-WSA reduces computational complexity and achieves superior performance through analysis and experiments. Secondly, we propose a Spatial Gated Network (SGN) as a feed-forward network, which can effectively overcome the problem of intermediate channel redundancy in traditional MLP, thereby improving the parameter utilization and computational efficiency of the network. Meanwhile, SGN introduces spatial information into the feed-forward network that traditional MLP cannot obtain. It can better understand and use the spatial structure information in the image, and enhances the network performance and generalization ability. Extensive experiments show that ELMA achieves competitive performance compared to state-of-the-art methods while maintaining fewer parameters and computational costs.

Linking Phylogeny and Morphology to Resource Assimilation Within Aquatic Assemblages

ABSTRACTNiche partitioning promotes species coexistence. Yet, it remains unclear how phylogeny and morphology influence the trophic niches of closely related aquatic species with shared feeding modes. Freshwater mussels (Family: Unionidae) are a group of filter‐feeding bivalves that are ideal for investigating mechanisms of niche partitioning. Particle size selection and patterns of ingestion are controlled by gill latero‐frontal cirri density (CD) and the number of cilia per cirrus (CC). We investigated trophic assimilation and niche area using stable isotope signatures (𝛿13C and 𝛿15N) and gill morphology with scanning‐electron microscopy for a diverse mussel assemblage from the Sipsey River, Alabama, USA. We predicted that (1) trophic niches and gill morphology would differ within and among species across sites; (2) co‐occurring species would partition food resources; (3) greater phylogenetic distances among species would result in increased trophic dissimilarity; (4) more CC and higher CD would result in a narrower trophic niche area, or more constrained range of food items assimilated. We found that (1) species identity and site influenced gill morphology and stable isotope signatures but that the trophic niche area of a species was only affected by species identity; (2) the average proportion of niche area overlap between co‐occurring species was low across sites (0.04 to 0.18); (3) trophic dissimilarity among species increased with phylogenetic distance; (4) CD but not the number of CC negatively related to trophic niche area. Our results indicate that gill morphology and evolutionary history are likely key factors governing the trophic niches of mussels. In addition, intraspecific variation in gill morphology across sites may either reflect a phenotypic response to differences in local resource availability or suggest that other mechanisms shape particle selection. Examining the interplay among the trophic niche, phylogeny, and morphology among functionally similar species further informs our understanding of the mechanisms facilitating their coexistence.

Temporal Study of Environmental DNA and Acoustic Data Reveals Coexistence of Sympatric Bat Species in a North American Ecosystem

ABSTRACTBats are a species‐rich mammalian order that provide a host of ecosystem services, but presently face threats from habitat loss, disease, climate change, and insect declines. Bat species often co‐occur with other ecologically similar bats, making them a suitable group in which to study niche overlap and partitioning. This study aimed to compare different non‐invasive sources of data on wildlife populations, while examining dietary, temporal, and spatial partitioning patterns among sympatric bat species. We used two different methods to assess niche partitioning among insectivorous bats at a site in the San Francisco Bay Area, California: (1) eDNA sequencing of bat feces that were collected weekly from a bat roost, and (2) nightly acoustic recordings of ultrasonic bat calls from recorders at multiple sites. Both the eDNA and acoustic data were collected over the course of an entire roosting season in 2020. We hypothesized that the insectivorous bats at this site would rely on one or more niche partitioning mechanisms to promote interspecific coexistence and limit competition. We found evidence of fine‐scale spatial partitioning of the broad community of bat species in our study area based on acoustic data, as well as temporal differences in activity of different species. The two species using the roosting site, Tadarida brasiliensis and Eptesicus fuscus, displayed some differences in the identities and relative abundances of prey species consumed, but both ultimately exhibited a strong reliance on dipterans and aquatic‐dependent insects. We demonstrate differences between the acoustic data and eDNA data, which has implications for how such datasets may be interpreted in future research. The study finds evidence of some types of niche partitioning in this community and characterizes baseline interactions between species, providing a foundation for future efforts to non‐invasively monitor for unexpected biological change in local ecosystems.

Unveiling spatiotemporal distribution, partitioning, and transport mechanisms of tire additives and their transformation products in a highly urbanized estuarine region

Numerous tire additives are high-production volume chemicals that are used extensively worldwide. However, their presence and partitioning behavior remain largely unknown, particularly in marine environments. This study is the first to reveal the spatiotemporal distribution, multimedia partitioning, and transport processing of 22 tire additives and their transformation products (TATPs) in a highly urbanized estuary (n = 166). Nineteen, 18, and 20 TATPs were detectable in water, suspended particulate matter (SPM), and sediments, respectively, with total levels of 59.7–2021 ng/L, 164–6935 ng/g, and 4.66–58.4 ng/g, respectively. The multimedia partitioning mechanisms of TATPs are governed by their molecular weight, hydrophobicity, and biodegradation rate. Mass inventories coupled with model simulations have revealed that substantial quantities of TATPs accumulate within estuarine environments, and these compounds can be continuously transported into the ocean, particularly during the wet season. According to the multi-criteria evaluation approach, four and three TATPs were identified as high-priority pollutants during the dry and wet seasons, respectively. Unexpectedly, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone was only listed as a medium-priority pollutant. This study underscores the importance of marine surveillance and advocates for particular attention to these ubiquitous but underexplored TATPs in future studies.

Dietary partitioning in sympatric Paradoxurinae civets in Borneo suggested by compound-specific nitrogen isotope analysis of amino acids

We applied stable carbon and nitrogen isotopic analyses to understand the faunivory of the four sympatric wild Paradoxurinae civet species in Borneo, which share similar ecological characteristics. We also employed compound-specific nitrogen isotope analysis of amino acids to estimate these species’ trophic positions (TPs). The bulk stable isotope analysis revealed distinctly lower nitrogen isotope ratios in binturongs than in the other three species. This suggests that binturongs exhibit the lowest degree of faunivory among the four species. Binturongs had the lowest TP estimated from the nitrogen isotope ratios of amino acids (2.0–2.1), followed by small-toothed palm civets (2.4–2.5), masked palm civets (2.7), and common palm civets (2.9). These results suggest that there is little faunivory in binturong and variations in faunivory in the other species. Although the number of samples measured for the nitrogen isotope ratios of amino acids is small (n = 2 for each species), our results suggest that the varying degree of consumption of animal food sources, such as insects, is the key mechanism of niche partitioning in these four Paradoxurinae civet species in Borneo. Such subtle but essential differences in closely related sympatric species would maintain high biodiversity in tropical regions.

Seasonal and anthropogenic effects on niche overlap and habitat selection by sympatric bears (Ursus arctos marsicanus) and wolves (Canis lupus) in a human-dominated landscape.

Interspecific interactions among species of the same guild play a critical role in shaping their realized niches, and their understanding may disclose mechanisms of coexistence. Investigating interactions among apex predators is of ecological and management interest, especially in human-dominated landscapes where type and intensity of their interspecific competition may be affected by human interference. During 2005-2010, we investigated, by means of GPS-telemetry, interactions between brown bears (n = 19) and wolves (n = 7) in a long-established national park in the central Apennines, Italy, where bears and wolves have always coexisted close to humans. Based on a K-select analysis and a randomization approach, we assessed the extent of overlap between the species' niches on a seasonal basis. Bears and wolves clearly segregated in fall but not during summer when overlap between their realized niches suggests a convergent adaptation to a seasonal peak of anthropogenic pressure. However, using multi-species resource selection functions (RSFs) at the home range level (i.e., third-order selection), we revealed that habitat selection by bears and wolves was reciprocally affected also when their niches overlapped, possibly disclosing mechanisms of fine-scale resource partitioning. In early summer, bears selected areas with a high probability of resource selection by wolves, but in late summer avoided areas positively selected by wolves. On the contrary, wolves avoided areas where the probability of resource selection by bears was high, both in late summer and fall. These results indicate that bears and wolves do interact in our study area and, although the actual behavioral mechanisms are unknown, they reciprocally and asymmetrically affect their realized niche and habitat selection patterns. Further research is needed to better understand how anthropogenic factors impact intraguild interactions and what are the effects at the population and community levels.

Smaller islands, bigger appetites: evolutionary strategies of insular endemic skinks.

Competitive dietary and morphological divergence among co-occurring species are fundamental aspects of ecological communities, particularly on islands. Cabo Verde (~570 km west of continental Africa) hosts several endemic reptiles descended from common ancestors, with sympatric species exhibiting wide morphological variation and competing for limited resources. To explore the mechanisms of resource partitioning between coexisting species, DNA metabarcoding was used to compare the diets of large and small skinks, Chioninia vaillantii and Chioninia delalandii, in sympatric and allopatric contexts on Fogo Island and in a more competitive context on the small and resource-poor Cima Islet. The morphological variation of all populations was also examined to test the character displacement hypothesis and to compare the effect of different competitive scenarios. Results showed significant differences in diet and linear measurements between species and populations. The two sympatric populations of C. delalandii on Fogo and Cima showed similar changes in head morphology compared to the allopatric population, supporting character displacement. The effect of higher competitive pressure on Cima was evidenced by the increased morphological and dietary variation observed. This study demonstrates how sister species develop dietary adaptations/morphologies to maintain stable coexistence, especially in highly competitive scenarios, providing useful insights for effective conservation strategies.

Martensite size and morphology influence on strain distribution and micro-damage evolution in dual-phase steels; comparing segregation-neutralised and banded grades

A change in strain partitioning and microscale failure mechanisms in dual-phase (DP) steel was found when both the morphology and distribution of martensite were altered compared to a banded DP steel grade benchmarked against a specific commercial DP grade. To achieve a DP microstructure with equiaxed and well-dispersed martensite, the concept of segregation neutralisation was utilised, where the ratio of Mn to Si elements was decreased (from 7.4 to 0.3) to neutralise the effect of Mn segregation on generating the banded martensite. A combination of micromechanical modelling simulations and in-situ notch tensile testing (within an SEM) was employed to compare the micro strain field and void formation rate between the segregation-neutralised and the benchmark grades. The benchmark grade showed extensive void coalescence along the direction of shear bands in the tensile sample after the average tensile strain of 30%. In contrast, no void coalescence was observed in the segregation-neutralised DP steel even at the average tensile strain of 80% just before failure. As a result, post-uniform elongation in the segregation-neutralised grade increased to 63.3%, compared to 30.1% in the benchmark grade.

Virtual Simulation-Based Optimization for Assembly Flow Shop Scheduling Using Migratory Bird Algorithm.

As industrial informatization progresses, virtual simulation technologies are increasingly demonstrating their potential in industrial applications. These systems utilize various sensors to capture real-time factory data, which are then transmitted to servers via communication interfaces to construct corresponding digital models. This integration facilitates tasks such as monitoring and prediction, enabling more accurate and convenient production scheduling and forecasting. This is particularly significant for flexible or mixed-flow production modes. Bionic optimization algorithms have demonstrated strong performance in factory scheduling and operations. Centered around these algorithms, researchers have explored various strategies to enhance efficiency and optimize processes within manufacturing environments.This study introduces an efficient migratory bird optimization algorithm designed to address production scheduling challenges in an assembly shop with mold quantity constraints. The research aims to minimize the maximum completion time in a batch flow mixed assembly flow shop scheduling problem, incorporating variable batch partitioning strategies. A tailored virtual simulation framework supports this objective. The algorithm employs a two-stage encoding mechanism for batch partitioning and sequencing, adapted to the unique constraints of each production stage. To enhance the search performance of the neighborhood structure, the study identifies and analyzes optimization strategies for batch partitioning and sequencing, and incorporates an adaptive neighborhood structure adjustment strategy. A competition mechanism is also designed to enhance the algorithm's optimization efficiency. Simulation experiments of varying scales demonstrate the effectiveness of the variable batch partitioning strategy, showing a 5-6% improvement over equal batch strategies. Results across different scales and parameters confirm the robustness of the algorithm.

Automated analysis framework of strain partitioning and deformation mechanisms via multimodal fusion and computer vision

Simultaneously investigating strain partitioning and the underlying deformation mechanisms for both the grain interior and the grain boundary (GB) is essential for understanding the complex plastic deformation of hexagonal close-packed metals. To this end, an automated analysis framework based on high-resolution digital image correlation (HRDIC) and electron backscatter diffraction (EBSD) data fusion and computer vision, integrating nanoscale resolution and a large field of view, is proposed. This framework consists of: (1) HRDIC-EBSD data fusion; (2) Segmenting the strain field into individual grains each with a core and a mantle; (3) Data clustering of the Matrix and slip bands (SBs) for each grain; (4) Full slip system (SS) identification and SS assignment to the SBs. The capabilities of this framework were demonstrated on Mg-10Y during compression. The strain field data, which was segmented into different clusters, including grain mantle, grain core, Matrix, and SBs, was analyzed statistically and quantitatively. The pixel-based slip activity, which considers the SB morphology, was obtained from a statistical perspective. Inter-granular accommodating mechanisms, including GB strain, slip transfer, and GB sliding, were quantitatively analyzed. Overall, this analysis framework, which can be applied to other materials, can automatically and statistically evaluate both nanoscale strain fields and underlying intra- and inter-granular deformation mechanisms grain-by-grain. This work provides valuable experimental insights into plastic deformation and accommodation mechanisms for polycrystals.

Differential use of nest materials and niche space among avian species within a single ecological community.

Differential use of resources among bird species has been examined extensively in diet and nesting sites, but few studies have assessed this regarding avian nest materials. We assessed the structure and composition of nests in a group of co-existing passerine shrubland birds at a site in Massachusetts, USA. We found, measured, collected, and dissected nests, and then weighed nest materials in morphological groups (e.g., bark, twigs, feathers) to determine if our seven focal species were using different nest materials. Among species, we compared proportional material masses in complete nests, and also separately in the exterior, structural part of the nest and the interior, cup lining. We found that the proportional masses of all 17 material types that we examined in nests differed among species. The compositions of nests among all seven bird species were distinct in multivariate ordination space and only a few pairs of species had substantial niche overlap. Proportional masses of materials within discrete sections (exterior and interior) also varied among species. Although some differences in nest composition could be partially explained by bird species size, nest materials differed even within the three larger bodied species and within four smaller bodied species. Our study builds upon previous studies that have shown species-specificity in avian nest composition and supports the notion that birds using the same environment have distinct niches in relation to the materials placed in their nests. Niche partitioning due to interspecific competition could partially explain our findings, as certain materials are limited as resources, and searching for suitable nest materials is energetically costly. Additionally, other factors, such as partitioned nest sites, may have led to differential nest material use. We recommend further research to help elucidate underlying mechanisms of nest composition partitioning in birds and potentially other nest-building taxa.

Size-resolved gas-particle partitioning of polycyclic aromatic hydrocarbons in a large temperature range of 50 ℃

Size-resolved gas-particle partitioning of semi-volatile organic compounds (SVOCs) can affect their environmental behaviors and health effects, which has not been widely studied in comparing with the gas-total suspended particle partitioning. Herein, the size-resolved gas-particle partitioning quotient (KPi) of polycyclic aromatic hydrocarbons (PAHs) in a large temperature range (−20.6 ℃ ∼ 29.4 ℃) was firstly comprehensively studied. The log KPi values of PAHs related to fine particles were significantly higher than those related to coarse particles. When the logarithm of subcooled liquid-vapor pressure (log PL0) ∈ [−7, −1), the regression slopes of log KPi vs log PL0 related to the particle size > 1.0 µm were shallower than those with the particle size range of 0.10–1.0 µm, which indicated the influence of particle size on KPi. Among the three previous prediction equations of gas-particle partitioning quotient, the empirical equation based on the ambient temperature matched better with the measured log KPi. Therefore, a new prediction equation including ambient temperature and particle size as the two major parameters was established. For most particle size ranges, the new equation showed better prediction performance than the three previous equations. In summary, this study provided new insights for the size-resolved gas-particle partitioning mechanism and quotient.

Divergent Response of Two Bark Beetle-Fungal Symbiotic Systems to Host Monoterpenes Reflects Niche Partitioning Strategies.

The successful establishment of bark beetle-fungus symbionts on plants is required to overcome host defenses. However, little is known about how different bark beetle-fungus symbionts adapt to different niches on the same host plant. Here, we investigated the niche partitioning mechanism of two co-occurring bark beetle-fungus symbiotic systems, Ips nitidus-Ophiostoma bicolor and Dendroctonus micans-Endoconidiophora laricicola, on Qinghai spruce (Picea crassifolia) tree. The lower niche of the spruce trunk inhabited by D. micans showed a higher content of monoterpenes than the upper niche of the trunk inhabited by I. nitidus. Dendroctonus micans showed greater tolerance and higher metabolic efficiency toward monoterpenes than I. nitidus. However, both beetle species showed a similar metabolic profile toward α-pinene, albeit with different levels of metabolites. Additionally, O. bicolor, transmitted by I. nitidus, showed a significantly higher tolerance to monoterpenes and pathogenicity to spruce trees than E. laricicola, transmitted by D. micans. In particular, monoterpenoid metabolites were observed to attenuate the inhibitory effect of high-dose α-pinene on E. laricicola, thus increasing its fitness in a high-dose monoterpene microhabitat. These results show that these two bark beetle-fungus symbionts have adapted to different niches, leading to fitness differences in niche distribution that are at least partly related to the different distribution of monoterpene concentration in the spruce trunk. This research provides a novel perspective for understanding the coevolution between bark beetle-fungus symbionts and their host plants.

Study on the forming mechanism and evolutionary pattern of stagnant region in mechanical scratching

In this paper, a combination of theoretical modeling, finite element simulation, and experimental methods is employed to investigate the forming mechanism and evolutionary pattern of the stagnant region during mechanical scratching with a diamond wedge tool. The study is structured as follows: Firstly, a theoretical calculation model for the geometric parameters of the stagnant region on the formed groove surface is established based on the contact friction partition mechanism and slip-line field theory. The model indicates that the geometric parameters lB-sg, lV-sg, and ∆lsg of the stagnant region are determined by the length of the stagnant region lp-sg in the plastic flow plane and the transformation parameters. Secondly, the formation process of the stagnant region in mechanical scratching is investigated using an orthogonal cutting simulation model with a negative rake angle tool. The results reveal that the stagnant region is a plastic deformation region formed due to the geometrical characteristics of the negative front surface of the scratching tool and its excessive extrusion, which leads to the formation of adhesive friction within the material. Thirdly, the characteristics of the stagnant region are determined through scratching experiments. Compared to the material in the plastic flow region, the material within the stagnant region exhibits finer and denser microstructures, reduced surface hardening peaks and hardened layer depths, and significantly improved surface roughness. Finally, the evolutionary pattern of the stagnant region under the influence of scratching processing parameters is examined based on the theoretical calculation model of the geometric parameters and the scratching experiment. The findings indicate that as the wedge angle of the scratching tool decreases, the relief angle increases, the absolute value of the rotation angle around the Y-axis decreases, the scratching speed decreases, and the material’s plastic adherence improves, the PI/k value decreases, the lp-sg value increases, and consequently, the geometric parameters lB-sg, lV-sg, and ∆lsg of the stagnant region on the formed groove surface also increase. The deviation analysis of the geometric parameters of the stagnant region reveals a consistent trend between the theoretical and experimental values of lV-sg and ∆lsg, with maximum deviations of 15 μm and 4.13%, respectively. This study provides theoretical and experimental evidence for the establishment of the theoretical model of the stagnant region in mechanical scratching, the analysis of its forming mechanism, and the control of the stagnant region geometric parameters on the formed groove surface.

Differential growth regulates asymmetric size partitioning in Caulobacter crescentus.

Cell size regulation has been extensively studied in symmetrically dividing cells, but the mechanisms underlying the control of size asymmetry in asymmetrically dividing bacteria remain elusive. Here, we examine the control of asymmetric division in Caulobacter crescentus, a bacterium that produces daughter cells with distinct fates and morphologies upon division. Through comprehensive analysis of multi-generational growth and shape data, we uncover a tightly regulated cell size partitioning mechanism. We find that errors in division site positioning are promptly corrected early in the division cycle through differential growth. Our analysis reveals a negative feedback between the size of daughter cell compartments and their growth rates, wherein the larger compartment grows slower to achieve a homeostatic size partitioning ratio at division. To explain these observations, we propose a mechanistic model of differential growth, in which equal amounts of growth regulators are partitioned into daughter cell compartments of unequal sizes and maintained over time via size-independent synthesis.

Correlation Between Antimicrobial Structural Classes and Membrane Partitioning: Role of Emerging Lipid Packing Defects

In this study, a combination of bioinformatics and molecular dynamics simulations is employed to investigate the partitioning behavior of different classes of antimicrobial peptides (AMPs) into model membranes. The main objective is to identify any correlations between the structural characteristics of AMPs and their membrane identification and early-stage partitioning mechanisms. The simulation results reveal distinct membrane interactions among the various structural classes of AMPs, particularly in relation to the generation and subsequent interaction with lipid packing defects. Notably, AMPs with a structure-less coil conformation generate a higher number of deep and shallow defects, which are larger in size compared to other classes of AMPs. AMPs with helical component demonstrated the deepest insertion into the membrane. On the other hand, AMPs with a significant percentage of beta sheets tend to adsorb onto the membrane surface, suggesting a potentially distinct partitioning mechanism attributed to their structural rigidity. These findings highlight the diverse membrane interactions and partitioning mechanisms exhibited by different structural classes of AMPs.Graphical abstract