Intermediate Size Research Articles

Genetic Analysis of GCA Repeats in the GLS Gene: Implications for Undiagnosed Ataxia and Spinocerebellar Ataxia 3 in Mainland China.

Recent studies have reported that expanded GCA repeats in the GLS gene can cause glutaminase deficiency with ataxia phenotype. However, to data, no studies have investigated the distribution and role of GCA repeats in the GLS gene of Chinese individuals. The aim was to investigate the distribution of GCA repeats in Chinese individuals, including undiagnosed ataxia patients for identifying causal factors, healthy controls for determining the normal range, and ATX-ATXN3 (spinocerebellar ataxia type 3, SCA3) patients for exploring genetic modifiers. We combined whole-genome sequencing (WGS), repeat-primed polymerase chain reaction, capillary electrophoresis (RP-PCR/CE), and ExpansionHunter to screen the GCA repeats in the GLS gene of 349 undiagnosed ataxia individuals, 1505 healthy controls, and 1236 ATX-ATXN3 (SCA3)patients from mainland China. No expanded GCA repeats in the GLS gene were detected across any of the samples. The average number of GCA repeats was 11 (range: 8-31), 12 (range: 6-33), and 11 (range: 6-33) for undiagnosed ataxia patients, healthy controls, and SCA3 patients, respectively. The intermediate repeat size (9 < repeat size ≤ 13) of the nonexpanded GCA allele in the GLS gene was associated with later disease onset in ATX-ATXN3 (SCA3) patients. Abnormal expansions of GLS GCA repeats are rare in the Chinese population. However, intermediate-length normal GCA repeat sizes may influence the age at onset (AAO) in ATX-ATXN3 (SCA3) patients. © 2024 International Parkinson and Movement Disorder Society.

Unveiling the embryo structure in Bromeliaceae Juss. (Poales): morphological diversity, anatomy, and character evolution.

Recent studies have documented numerous morphoanatomical variations for the seed coat in Bromeliaceae. However, the structural diversity and character evolution of the embryo within this family remain largely unexplored. Given the embryo's significance in plant diversification, this research aims to investigate the morphology and key anatomical features of Bromeliaceae embryos, providing insights into character evolution, taxonomic applications, and reproductive biology. We analysed samples of 88 species from 50 genera representing the major lineages of Bromeliaceae, using standard plant microtechniques adapted for seeds. To determine ancestral traits, parsimony and maximum likelihood analyses were performed in a consensus supertree combining previous phylogenies. This study identified 14 informative characters, highlighting significant differences among groups, particularly in embryo morphology, differentiation, and anatomical traits. Our analysis revealed that undifferentiated embryos with a vestigial cotyledonary hyperphyll are plesiomorphic in Bromeliaceae. They have evolved multiple times into rudimentary or well-differentiated embryos, the latter exhibiting intermediate or large sizes and diverse cotyledonary hyperphyll morphologies. The cotyledonary hypophyll varies in sheath lobes and slit morphologies, and is curved or expanded exclusively in Bromelioideae representatives. Similarly, several patterns of hypocotyl/radicle constriction are unique to Tillandsioideae and plesiomorphic for this clade. Although rudimentary embryos exhibit simpler and more uniform anatomy, they are distinct from undifferentiated embryos, which lack defined organs and internal tissues. In contrast, well-differentiated embryos possess more complex anatomical structures, including a multi-layered shoot apical meristem and root cap, a broad cotyledonary sheath, and often leaf primordia, the latter evolving independently several times only in large embryos. Our findings reveal a previously unknown morphological diversity for embryos in Bromeliaceae, enhancing our understanding of the morphological evolution of its major lineages. In addition, it introduces new informative characters for the family's systematics and broadens our understanding of the reproductive biology of Bromeliaceae.

Dose-dependent interaction of parasites with tiers of host defense predicts "wormholes" that prolong infection at intermediate inoculum sizes.

Immune responses are induced by parasite exposure and can in turn reduce parasite burden. Despite such apparently simple rules of engagement, key drivers of within-host dynamics, including dose-dependence of defense and infection duration, have proven difficult to predict. Here, we model how varied inoculating doses interact with multi-tiered host defenses at a site of inoculation, by confronting barrier, innate, and adaptive tiers with replicating and non-replicating parasites across multiple orders of magnitude of dose. We find that, in general, intermediate parasite doses generate infections of longest duration because they are sufficient in number to breach barrier defenses, but insufficient to strongly induce subsequent tiers of defense. These doses reveal "wormholes" in defense from which parasites might profit: Deviation from the hypothesis of independent action, which postulates that each parasite has an independent probability of establishing infection, may therefore be widespread. Interestingly, our model predicts local maxima of duration at two doses-one for each tier transition. While some empirical evidence is consistent with nonlinear dose-dependencies, testing the predicted dynamics will require finer-scale dose variation than experiments usually incorporate. Our results help explain varied infection establishment and duration among differentially-exposed hosts and elucidate evolutionary pressures that shape both virulence and defense.

Low Penetrance Sarcomere Variants Contribute to Additive Risk in Hypertrophic Cardiomyopathy.

Classically, hypertrophic cardiomyopathy (HCM) has been viewed as a single-gene (monogenic) disease caused by pathogenic variants in sarcomere genes. Pathogenic sarcomere variants are individually rare and convey high risk for developing HCM (highly penetrant). Recently, important polygenic contributions have also been characterized. Low penetrance sarcomere variants (LowSVs) at intermediate frequencies and effect sizes have not been systematically investigated. We hypothesize that LowSVs may be common in HCM with substantial influence on disease risk and severity. Among all sarcomere variants observed in the Sarcomeric Human Cardiomyopathy Registry (SHaRe), we identified putative LowSVs defined by (1) population frequency greater than expected for highly penetrant (monogenic) HCM (allele frequency >5×10-5 in the Genome Aggregation Database, gnomAD) and (2) moderate enrichment (>2×) in patients with HCM compared with gnomAD. LowSVs were examined for their association with disease severity and clinical outcomes. Functional effects of selected LowSVs were assessed using induced pluripotent stem cell-derived cardiomyocytes. Association of LowSVs with HCM-adjacent traits in the general population was tested using UK Biobank cardiac magnetic resonance imaging data. Among 6045 patients and 1159 unique variants in sarcomere genes, 12 LowSVs were identified. LowSVs were collectively common in the general population (1:350) and moderately enriched in HCM (aggregate odds ratio, 14.9 [95% CI, 12.5-17.9]). Isolated LowSVs were associated with an older age of HCM diagnosis and fewer adverse events. However, LowSVs in combination with a pathogenic sarcomere variant conferred higher morbidity (eg, composite adverse event hazard ratio, 5.4 [95% CI, 3.0-9.8] versus single pathogenic sarcomere variant, 2.0 [95% CI, 1.8-2.2]; P<0.001). An intermediate functional impact was validated for 2 specific LowSVs-MYBPC3 c.442G>A (partial splice gain) and TNNT2 c.832C>T (intermediate effect on contractile mechanics). Cardiac magnetic resonance imaging analysis of the general population revealed 5 of 12 LowSVs were significantly associated with HCM-adjacent traits without overt HCM. This study establishes a new class of low penetrance sarcomere variants that are relatively common in the population. When penetrant, isolated LowSVs cause mild HCM. In combination with pathogenic sarcomere variants, LowSVs markedly increase disease severity, supporting a clinically significant additive effect. Last, LowSVs also contribute to age-related remodeling even in the absence of overt HCM.

A Polyhedral Study of Multivariate Decision Trees

Decision trees are a widely used tool for interpretable machine learning. Multivariate decision trees employ hyperplanes at the branch nodes to route datapoints throughout the tree and yield more compact models than univariate trees. Recently, mixed-integer programming (MIP) has been applied to formulate the optimal decision tree problem. A key component of most MIP formulations is a specification of how to route datapoints in the tree from the root to the leaves. Our goal is to provide polyhedral characterizations of realizable routings, that is, routings that can be realized using multivariate branching rules. We first focus on shattering inequalities, a class of valid inequalities that can be used to strengthen almost any MIP formulation and that have been shown to be computationally effective. We prove that if all the feature vectors are in general position, then the shattering inequalities defined for the root of the tree are facet defining for the convex hull of the realizable routings. We then show that every facet-defining inequality of a depth one tree involving at least two variables is also facet defining for trees of arbitrary depth. Finally, we show that facet-defining inequalities characterizing realizable routings are also facet-defining for a complete MIP formulation. We validate our theoretical results by performing numerical experiments that specifically exploit shattering inequalities defined at the root node and we observe an improvement in performance for both numerical and categorical data sets, especially for decision trees of intermediate size. Funding: C. Michini gratefully acknowledges funding from the DoD, Air Force [Award FA9550-23-1-0487].

NOTCH2NLC GGC intermediate repeat with serine induces hypermyelination and early Parkinson’s disease-like phenotypes in mice

BackgroundThe expansion of GGC repeats (typically exceeding 60 repeats) in the 5’ untranslated region (UTR) of the NOTCH2NLC gene (N2C) is linked to N2C-related repeat expansion disorders (NREDs), such as neuronal intranuclear inclusion disease (NIID), frontotemporal dementia (FTD), essential tremor (ET), and Parkinson’s disease (PD). These disorders share common clinical manifestations, including parkinsonism, dementia, seizures, and muscle weakness. Intermediate repeat sizes ranging from 40 to 60 GGC repeats, particularly those with AGC-encoded serine insertions, have been reported to be associated with PD; however, the functional implications of these intermediate repeats with serine insertion remain unexplored.MethodsHere, we utilized cellular models harbouring different sizes of N2C variant 2 (N2C2) GGC repeat expansion and CRISPR-Cas9 engineered transgenic mouse models carrying N2C2 GGC intermediate repeats with and without serine insertion to elucidate the underlying pathophysiology associated with N2C intermediate repeat with serine insertion in NREDs.ResultsOur findings revealed that the N2C2 GGC intermediate repeat with serine insertion (32G13S) led to mitochondrial dysfunction and cell death in vitro. The neurotoxicity was influenced by the length of the repeat and was exacerbated by the presence of the serine insertion. In 12-month-old transgenic mice, 32G13S intensified intranuclear aggregation and exhibited early PD-like characteristics, including the formation of α-synuclein fibers in the midbrain and the loss of tyrosine hydroxylase (TH)-positive neurons in both the cortex and striatum. Additionally, 32G13S induced neuronal hyperexcitability and caused locomotor behavioural impairments. Transcriptomic analysis of the mouse cortex indicated dysregulation in calcium signaling and MAPK signaling pathways, both of which are critical for mitochondrial function. Notably, genes associated with myelin sheath components, including MBP and MOG, were dysregulated in the 32G13S mouse. Further investigations using immunostaining and transmission electron microscopy revealed that the N2C intermediate repeat with serine induced mitochondrial dysfunction-related hypermyelination in the cortex.ConclusionsOur in vitro and in vivo investigations provide the first evidence that the N2C-GGC intermediate repeat with serine promotes intranuclear aggregation of N2C, leading to mitochondrial dysfunction-associated hypermyelination and neuronal hyperexcitability. These changes contribute to motor deficits in early PD-like neurodegeneration in NREDs.

Lewis-Acid Mediated Reactivity in Single-Molecule Junctions.

While chemical reactions at a gold electrode can be monitored using molecular conductance and driven by extrinsic stimuli, the intrinsic properties of the nanostructured interface may perform important additional functions that are not yet well understood. Here we evaluate these properties in studies of single-molecule junctions formed from components comprising 4,4'-biphenyl backbones functionalized with 12 different sulfur-based linker groups. With some linkers, we find evidence for in situ S-C(sp3) bond breaking, and C(sp2)-C(sp3) bond forming, reactions consistent with the ex situ transformations expected for those groups in the presence of a Lewis acid. Notably, we also approach the limits of substituent influence on the conductance of physisorbed sulfur-linked junctions. As an illustrative example, we show that a tert-butylthio-functionalized precursor can form both chemisorbed (Au-S) junctions, consistent with heterolytic S-C(sp3) bond cleavage and generation of a stable tert-butyl carbocation, as well as physisorbed junctions that are >1 order of magnitude lower conductance than analogous junctions comprising cyclic "locked" thioether contacts. These findings are supported by a systematic analysis of model thioether components comprising different simple hydrocarbon substituents of intermediate size, which do not form chemisorbed contacts and further clarify the inverse relationship between conductance and substituent steric bulk. First-principles calculations confirm that bulky sulfur-substituents increase the probability of forming junction geometries with reduced electronic coupling between the electrode and π-conjugated molecular backbone. Together, this work helps to rationalize the dual roles that linker chemical structure and metal electrode Lewis character can play in mediating interfacial reactions in break-junction experiments.

A New XPS Test Material for More Reliable Analysis of Microstructures

ABSTRACTA reference material is required for small‐area XPS because it has been used more frequently for surface control in recent years and many operators use incorrect field of views. To address this problem, we developed a test material starting in 2019. We optimised this XPS test material dedicated to the control of analysis position on the sample, with respect to the following factors: type of XPS instruments available on the market, the manufacturing process and sample handling. Test structures are now aligned along lines instead of on a circle radius, so that the individual structures can be accessed more quickly and easily. In addition, a larger test structure of 300 μm and another one in an intermediate size of 18 μm were added. Smaller test structures under 50 μm have been annotated with finder grids/arrows around them so that they are easier to find. Further, the manufacturing process was changed from e‐beam lithography to a mask process to be able to offer the test material at a favourable price. The use of masks also had to be adapted for the new manufacturing process so that the smallest square structures are also realised as such and do not show any distortion of the structure boundaries. The quality control using a metrological SEM confirmed a very reproducible manufacturing process. It is demonstrated that the test material can be successfully employed to find the most suitable beam size of the XPS system used for the analysis of small (μm range) surface features.

A scaling law for predicting urban trees canopy cooling efficiency

Urban heat mitigation is a pressing concern for cities. Intense urban heat poses a threat to human health and urban sustainability. Tree planting is one of the most widely employed nature-based heat mitigation methods worldwide. Therefore, city policy makers require knowledge of how much temperature will be reduced by increasing urban tree canopy (UTC). Cooling efficiency (CE), which was been proposed to quantify the magnitude of temperature reduction associated with a 1% increase in UTC, has been primarily investigated at smaller scales previously. However, such small-scale results cannot be used to develop policy at the whole-city scale. This study developed a method that reveals the scaling relations of CE so as to predict its effects at the city scale. CE was found to follow the form of a power law as spatial scale increased from the small analytical units through intermediate size units up to the extent of a whole city. The power law form appeared consistently across cities with different climate backgrounds during summer daylight hours. Furthermore, the power law form was robust within cities under different summer weather conditions. The power-law scaling approach can thus be used to predict CE at the whole-city scale, providing a useful tool for managers to set UTC goals to mitigate extreme urban heat.

Differential predation pressure on island pit vipers shape their niches and defensive behavior

Abstract Animals are naturally exposed to several predators, and, given that a single encounter with a predator may cause prey’s death, natural selection will strongly act upon its defensiveness. Therefore, defensive behavior is strongly shaped by predation pressure. Predation rate in islands tends to be relaxed due to lower abundance of predators. The aim of this study was to test the hypothesis that predation rates upon the two island pit vipers Bothrops alcatraz and B. insularis would be lower than correlated mainland B. jararaca. Additionally, we evaluated the defensive behavior of these island snakes in the field to compare with the mainland B. jararaca. Predation pressure upon the insular species was assessed utilizing plasticine replicas, and we evaluated their defensive behavior to approach. These data were compared to those previously reported for B. jararaca. We found a lower predation pressure on B. insularis (from the smaller area) than on B. alcatraz and B. jararaca from the urban mainland forest fragment (areas with intermediate size), and all of them showed lower predation pressure than B. jararaca from the continuous mainland forested area. In the field, island snakes show narrower defensive repertoire than B. jararaca, since most B. insularis fled, and B. alcatraz either fled or remained immobile on approach. Apparently, the predation pressure to which these island pit vipers are exposed shapes their defensive behavior, as well as the niches exploited by them.

Predation on eggs and larvae of the Japanese brown frog Rana japonica Boulenger, 1879 by the invasive crayfish Procambarus clarkii (Girard, 1852) (Decapoda: Astacidea: Cambaridae) under laboratory conditions

Abstract We hypothesized that the North American invasive crayfish Procambarus clarkii (Girard, 1852) can negatively affect the populations of native frog species through predation. We conducted three laboratory experiments to examine whether P. clarkii can prey on eggs or larvae of the Japanese native frog Rana japonicaBoulenger, 1879: Experiment I crayfish + frog egg in an aquarium without a substrate or aquatic plants, Experiment II crayfish + frog larva in an aquarium without a substrate or aquatic plants, and Experiment III crayfish + frog larva in an aquarium with a substrate and aquatic plants as shelter for the larva. We used three experimental groups of crayfish individuals (small, intermediate, and large size), each of 10 individuals, and simultaneously placed one crayfish individual and one egg or frog larva in the same aquarium for 24 h and checked for predation by the crayfish. We found that 88.9% and 86.7% of eggs and larvae used in Experiments I and II were preyed upon, respectively. Predation rate of frog larvae was still high (77.8%) in Experiment III, suggesting that crayfish can potentially find and prey on frog larvae in nature. Predation on frog eggs or larvae was high regardless of the crayfish body size. Our results indicate that P. clarkii can potentially have a marked effect on the population of R. japonica by preying on eggs and larvae.

Dissecting the effect of substrate on polyamide reverse osmosis membranes via regulating substrate pore size by drying shrinkage

Several studies have proved that the substrate significantly influences the chemical properties of reverse osmosis (RO) membranes, whereas the underlying mechanisms remain elusive. Herein, we adjusted the substrate pore size from 8.6 nm to 4.4 nm by drying shrinkage, ensuring the substrate's chemical properties remained consistent. Interestingly, we observed that an intermediate pore size (7.4 nm) of the substrate resulted in the highest exotherm, with the interfacial temperature rising to 26.8 °C, thus showing that larger pore sizes do not necessarily result in more pronounced exothermic interfacial polymerization (IP) reactions. Through multiscale simulations and various characterization techniques, we found that the IP reaction is governed by two competing effects: (1) the storage capacity of MPD, which provides the reactive monomers; and (2) the water content, which absorbs the heat in the IP reaction. Balancing these two competing factors contributes to enhancing the diffusion of MPD, thereby promoting the progression of the IP reaction. This work revealed a new mechanism through which the substrate affects RO membrane formation.

Intermetallics triggering pyroptosis and disulfidptosis in cancer cells promote anti-tumor immunity

Pyroptosis, an immunogenic programmed cell death, could efficiently activate tumor immunogenicity and reprogram immunosuppressive microenvironment for boosting cancer immunotherapy. However, the overexpression of SLC7A11 promotes glutathione biosynthesis for maintaining redox balance and countering pyroptosis. Herein, we develop intermetallics modified with glucose oxidase (GOx) and soybean phospholipid (SP) as pyroptosis promoters (Pd2Sn@GOx-SP), that not only induce pyroptosis by cascade biocatalysis for remodeling tumor microenvironment and facilitating tumor cell immunogenicity, but also trigger disulfidptosis mediated by cystine accumulation to further promote tumor pyroptosis in female mice. Experiments and density functional theory calculations show that Pd2Sn nanorods with an intermediate size exhibit stronger photothermal and enzyme catalytic activity compared with the other three morphologies investigated. The peroxidase-mimic and oxidase-mimic activities of Pd2Sn cause potent reactive oxygen species (ROS) storms for triggering pyroptosis, which could be self-reinforced by photothermal effect, hydrogen peroxide supply accompanied by glycometabolism, and oxygen production from catalase-mimic activity of Pd2Sn. Moreover, the increase of NADP+/NADPH ratio induced by glucose starvation could pose excessive cystine accumulation and inhibit glutathione synthesis, which could cause disulfidptosis and further augment ROS-mediated pyroptosis, respectively. This two-pronged treatment strategy could represent an alternative therapeutic approach to expand anti-tumor immunotherapy.

Disruption of natural disturbance regime decouples habitat and life stage in a keystone species

AbstractAnthropogenic disturbance of stream ecosystems, often chronic in nature, has been studied extensively. However, when disturbance is driven by more than one resource policy over many decades, feedback between habitat evolution and biological adaptation can be disrupted and ecological function affected in unforeseen ways. We analyzed over 100 years of Chinook salmon (Oncorhynchus tshawytscha) length frequency trends associated with fisheries management and changes in available spawning substrate (habitat) linked to flow regulation in a highly altered California river. Over time, salmon lengths generally decreased, fluctuating with exploitation (ocean harvest) and hatchery production rates. Female size reduction, coupled with a degrading and coarsening channel, and perching peripheral habitat related to past mining activity, indicates available spawning substrate may be too large to support the current salmon population. Assuming a salmon can move material ~10% of her body length, length frequency data and current substrate size distribution suggest that increasing salmon sizes to historic distributions could increase available spawning habitat by as much as 13%. Alternatively, decreasing spawning substrate size could support a greater portion of the current population. To test the latter hypothesis and inform future management actions, we monitored two spawning riffles where large and small gravel was placed on top of a cobble. We observed an immediate spawning activity increase that was more pronounced where smaller gravel was deposited. Following a decade of habitat decline, the two sites were both replenished with medium gravel. Elevated spawning use occurred immediately at both sites, commensurate with this intermediate size, further supporting our hypotheses. Sediment coarsening and habitat disconnect below dams, combined with reduced salmon size, indicate the natural spawning process may be decoupled from available habitat below dams in the foreseeable future without continuous intervention. Actively managing salmon population demographics through modified hatchery and size‐selective harvest practices and developing a coarse sediment budget with size‐appropriate material for regulated anadromous rivers could produce immediate benefits for ecosystem services, including salmon populations. However, these management actions will require continued maintenance and informed socio‐ecological goals to remain successful.

Optimization of abrasive slurry assisted rotating ultrasonic machining for enhanced micro-channel fabrication on ceramic silicon wafer (111)

This study examined the impact of abrasive slurry assisted Rotating Ultrasonic Machining (RUM) using Boron Carbide (B4C) powder of three mesh sizes: 400 Mesh, 600 Mesh, and 800 Mesh. The effects of abrasive size, feed rate, and tool rotation on Material Removal Rate (MRR) and Surface Roughness (SR) were investigated. The highest MRR of 3.454 mm³/min was achieved with 400 mesh, 30 mm/min feed rate, and 1250 rpm due to larger abrasive size, medium feed rate, and medium tool rotation velocity, while the lowest MRR of 0.284 mm³/min was noted with 600 mesh, 30 mm/min feed rate, and 1500 rpm, attributed to intermediate abrasive size and high tool rotation. The lowest SR of 1.16 μm was observed at 800 mesh, 15 mm/min feed rate, and 1500 rpm, resulting from smaller abrasive size and higher tool rotation facilitating polishing action and vibrational dampening. The highest SR of 3.71 μm occurred at 400 mesh, 45 mm/min feed rate, and 1500 rpm, due to larger abrasive size, higher feed rate, and tool rotation, increasing surface corrosion. ANOVA and regression analyses highlighted mesh size as the most significant parameter for both MRR and SR, with strong model-experimental value correlations. The findings demonstrate the suitability of abrasive slurry assisted RUM for fabricating micro-channels in X-Ray, optoelectronic, and semiconductor applications.

The bubble size produced in a pilot HydroFloat® cell and its effects on flotation

Unlike a traditional mechanical flotation cell, Eriez’s HydroFloat® is a fluidized-bed flotation device that can recover much coarser and less liberated particles. This is a new flotation machine where the effects of parameters such as bubble size are yet to be established. To address this problem, JKMRC has built a pilot HydroFloat® rig which it deployed to a copper–gold plant in New South Wales, Australia. Tests were performed at a range of operating conditions and bubble size images were collected and analysed using a novel newly created bubble size measurement method. In conventional flotation, a finer bubble size increases flotation rates because it increases the probability of bubble-particle collision and attachment. In this pilot HydroFloat® test program, however, flotation performance was optimal at an intermediate bubble size. Using the comprehensive test program data, the operating parameters that significantly affect bubble size were established, and an empirical model to predict bubble size was developed.

Substrate heterogeneities cause root growth trajectories to switch from vertical to oblique.

Hard pans, soil compaction, soil aggregation and stones create physical barriers that can affect the development of a root system. Roots are known to exploit paths of least resistance to avoid such obstacles, but the mechanism through which this is achieved is not well understood. Here, we combined 3D-printed substrates with a high-throughput live imaging platform to study the responses of plant roots to a range of physical barriers. Using image analysis algorithms, we determined the properties of growth trajectories and identified how the presence of rigid circular obstacles affects the ability of a primary root to maintain its vertical trajectory. Results showed the types of growth responses were limited, both vertical and oblique trajectories were found to be stable and influenced by the size of the obstacles. When obstacles were of intermediate sizes, trajectories were unstable and changed in nature through time. We formalised the conditions for root trajectory to change from vertical to oblique, linking the angle at which the root detaches from the obstacle to the root curvature due to gravitropism. Exploitation of paths of least resistance by a root may therefore be constrained by the ability of the root to curve and respond to gravitropic signals.

Strong and Tough Multilayer Heterogeneous Pyrocarbon Based Composites

AbstractThe integration of bio‐inspired hierarchical design into synthetic carbon materials holds promise for developing lightweight, high‐performance structural materials. Hierarchical and heterogeneous nanoscale units are crucial to load bearing and mechanical functionality yet receives limited attention for difficulties in accurate regulation. Herein, one kind of multilayered heterogeneous have proposed pyrocarbon based composite constructed through chemical vapor deposition method with nanoscale graphene orderliness regulation. Sequential construction from orientational graphene sheets to nondirective isotropic networks is achieved through controlling the size and morphology of pyrolysis intermediates with moderate oxidation, being expected to facilitate load transfer and structural stability through dynamically adjustment in heterogeneous interfacial sliding. The resulting multilayer heterogeneous phases exhibit impressive strengthening and toughening mechanisms dominated by microstructural multiscale coupling, which provides new solutions for developing structural composites for high‐temperature aerospace applications. Additionally, the multiple internal reflections arising from the abundant heterogeneous interfaces significantly improve the efficiency of electromagnetic microwave absorption. The multilayered heterogeneous interfaces achieved through orderliness manipulation offer novel insights into the assembly of mechanical functionality integration for wide‐temperature applications and high‐performance macroscopic carbon‐based composites.

Sedimentation of heterogeneous particles in a porous material

Filtration of suspensions and colloids in porous materials occurs during the construction and operation of hydraulic structures, tunnels and underground storage facilities. Filtration models are used to calculate the penetration of grout into loose soil, when treating drinking water and industrial wastewater. During the filtration process, suspended particles pass through large pores and get stuck at the entrance of small-diameter pores. The trapped particles form a stationary deposit. A model of filtration of a polydisperse suspension in a porous material is considered. The purpose of the work is to study sediment profiles – the dependence of the concentration of deposited particles on the distance to the porous material inlet at a fixed time. An exact solution to the model was constructed using the method of characteristics. It has been shown that when filtering a polydisperse suspension, the distribution of sediment differs for different types of particles. The sediment profile of the largest particles always decreases monotonically, but the sediment profile of the smallest particles is not monotonic. It decreases at short times, then a maximum point appears on the graph, moving along the porous medium as time increases. After the maximum point reaches the porous material exit, the sediment profile becomes monotonically increasing. The sediment profiles of intermediate size particles and the total sediment profile are either monotonic or non-monotonic depending on the model parameters. The behavior of maximum points of non-monotonic profiles has been studied.

Species-level characterization of the core microbiome in healthy dogs using full-length 16S rRNA gene sequencing.

Despite considerable interest and research in the canine fecal microbiome, our understanding of its species-level composition remains incomplete, as the majority of studies have only provided genus-level resolution. Here, we used full-length 16S rRNA gene sequencing to characterize the fecal microbiomes of 286 presumed healthy dogs living in homes in North America who are devoid of clinical signs, physical conditions, medication use, and behavioral problems. We identified the bacterial species comprising the core microbiome and investigated whether a dog's sex & neuter status, age, body weight, diet, and geographic region predicted microbiome variation. Our analysis revealed that 23 bacterial species comprised the core microbiome, among them Collinsella intestinalis, Megamonas funiformis, Peptacetobacter hiranonis, Prevotella copri, and Turicibacter sanguinis. The 23 taxa comprised 75% of the microbiome on average. Sterilized females, dogs of intermediate body sizes, and those exclusively fed kibble tended to harbor the most core taxa. Host diet category, geographic region, and body weight predicted microbiome beta-diversity, but the effect sizes were modest. Specifically, the fecal microbiomes of dogs fed kibble were enriched in several core taxa, including C. intestinalis, P. copri, and Holdemanella biformis, compared to those fed raw or cooked food. Conversely, dogs on a raw food diet exhibited higher abundances of Bacteroides vulgatus, Caballeronia sordicola, and Enterococcus faecium, among others. In summary, our study provides novel insights into the species-level composition and drivers of the fecal microbiome in healthy dogs living in homes; however, extrapolation of our findings to different dog populations will require further study.