Morphological Variation Research Articles

Bone matching versus tumor matching in image-guided carbon ion radiotherapy for locally advanced non-small cell lung cancer

Background and purposeThis study evaluates the dosimetric impact of tumor matching (TM) and bone matching (BM) in carbon ion radiotherapy for locally advanced non-small cell lung cancer.Materials and methodsForty patients diagnosed with locally advanced non-small cell lung cancer were included in this study. TM and BM techniques were employed for recalculation based on re-evaluation computed tomography (CT) images of the patients, resulting in the generation of dose distributions: Plan-T and Plan-B, respectively. These distributions were compared with the original dose distribution, Plan-O. The percentage of the internal gross tumor volume (iGTV) receiving a prescription dose greater than 95% (V95%) was evaluated using dose-volume parameters. Statistical analysis was performed using a paired signed-rank sum test. Additionally, the study investigated the influence of tumor displacement, volume changes, and rotational errors on target dose coverage.ResultsThe median iGTV V95% values for the Plan-O, Plan-T, and Plan-B groups were 100%, 99.93%, and 99.60%, respectively, with statistically significant differences observed. TM demonstrated improved target dose coverage compared to BM. Moreover, TM exhibited better target coverage in case of larger tumor displacement. TM’s increased adjustability in rotation directions compared to BM significantly influenced dosimetric outcomes, rendering it more tolerant to variations in tumor morphology.ConclusionTM exhibited superior target dose coverage compared to BM, particularly in cases of larger tumor displacement. TM also demonstrated better tolerance to variations in tumor morphology.

Paleoclimate Fluctuations Facilitate the Biogeographical History of Endemic Species of Freshwater Crabs in China via Cycles of Introgressive Hybridisation and Habitat Isolation

ABSTRACTAimThe impact of Pleistocene climate fluctuations on the biogeographical history of aquatic species has been a topic of enduring debate. This issue poses particular challenges for parapatric closely related species, especially those situated in transition zones where species assemblages occur between distinct zoogeographic boundaries.LocationEastern China.TaxonFive closely related Sinopotamon species and subspecies, S. shensiense, S. honanense, S. y. yangtsekiense, S. y. shanxianense, and S. y. tongbaiense.MethodsThese parapatric Sinopotamon species and subspecies, distributed along the boundary between the Palaearctic and Oriental realms in eastern China, offer an ideal model for addressing these challenges. We explored the biogeographic history of these species by conducting a comparative phylogeographic analysis using nine microsatellite loci and two mitochondrial DNA sequences, combined with morphological variation and fine‐tuned ecological niche modelling.ResultsOur phylogeographic analyses consistently revealed two well‐supported clades: clade A, for S. y. yangtsekiense, and clade B, which includes other species showing polyphyletic patterning and significant gene introgression. The Nanyang Basin and surrounding mountains regions (NBSM) was identified as a critical shared refuge and hybrid zone, facilitating interspecific introgression through at least two putative hybridisation events. During the Late Pleistocene glacial cycles, introgressive hybridisation of these species occurred in the NBSM, followed by rapid expansion and colonisation of heterogenous habitats during interglacial cycles, with dispersal corridors largely aligning with the local river system. In particular, the diffusion corridor of S. honanense significantly disrupted the continuous distribution of S. y. shanxianense and S. y. tongbaiense, indicating that S. honanense has replaced S. y. shanxianense and S. y. tongbaiense in the NYSM and caused a disruption in its distribution.Main ConclusionsThe biogeographic histories of the species in clade B are consistent with a mixing–isolation–mixing model, which suggests that populations experienced repeated introgressive hybridisation during glacial periods and regional habitat isolation during interglacial periods. Our findings represent a classic case of fine tracking biogeographical scenarios in parapatric species and provide unprecedented insights into the evolutionary radiation of the freshwater fauna that occupies zoogeographic boundaries.

Quantifying morphologic variations as an alternate to standard response criteria for unresectable primary liver tumors after checkpoint inhibition therapy.

The aim of this study was to assess the feasibility of quantifying morphologic changes in tumors during immunotherapy, as a reflection of response or survival. A retrospective single-center analysis was performed in patients with unresectable liver cancer previously enrolled in clinical trials combining immunotherapy (tremelimumab ± durvalumab) and locoregional treatment (either ablation or transarterial chemoembolization). Conventional response (RECIST 1.1) was assessed at 6-month follow-up. For morphologic assessment, the largest target lesion was manually segmented on axial slices in two dimensions using contrast-enhanced CT. Solidity and circularity of tumors were calculated at baseline, 3-month follow-up, and at 6-months follow-up. Survival analysis was performed. From the 68 patients enrolled in clinical trials, 28 did not have target lesions separate from lesions treated by locoregional therapies, and 3 had no follow-up imaging. Thirty-seven patients (9 with biliary cancer and 28 with hepatocellular carcinoma) were included. Shape features and shape variation were not correlated with RECIST 1.1 status at 6-month follow-up. However, patients with low solidity tumors at 6-month follow-up showed poorer prognosis compared with patients with high solidity tumors at 6-month follow-up (p = 0.01). Solidity variation analysis confirmed that a decrease of tumor solidity at 6-month follow-up was associated with poorer prognosis (p = 0.01). No association was found between shape features at baseline or shape features at 3-month follow-up with overall survival. Evolution and variation of tumor morphology during treatment may reflect or correlate with outcomes and contribute toward adapted response criteria.

Intraspecific phenotypic differentiation by habitat depth in deep demersal fish species

IntroductionOcean habitat characteristics change with depth. This is due to physical properties such as light, temperature and hydrostatic pressure, but also species community. In some cases, this generates a boundary (e.g. when light is lost in the bathypelagic), and in others it varies continuously (e.g. for hydrostatic pressure). Various studies have noted general morphometric adaptations to living at different depths seen among species, even though vertical migration can cause their ranges to overlap. However, few have looked at intraspecific changes.MethodsHere we investigate intraspecific variation for four species of demersal fish that inhabit a broad range of depths (200 m to over 2000 m). We test the hypothesis that intraspecific morphological variation will be similar to that seen among species.ResultsWe find that there are significant phenotypic differences between fish taken at different habitat depths, especially associated with mouth gape size, eye size, body shape and organ mass, despite the potential for vertical migration. However, we find that these patterns vary among species.DiscussionWe consider the possible drivers and implications for maintaining intraspecific phenotypic differences.

DUS and biochemical characterization of okra wild species for crop improvement

The present study focused on assessing the morphological and biochemical variations among the cultivated and wild okra species at vegetable research farm, Indian Agricultural Research Institute in the year 2021-22 and it has been found that the wild species possess more amount beneficial traits viz; chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, phenol, moisture, mucilage, sugar, ascorbic acid when compared to the cultivated species. The mean performance of these quantitative characters differed significantly from cultivated species (Abelmoschus esculentus). Biochemical parameter values were found to be high in wild accessions and lowest in cultivated species. Among the various wild species of A. moschatus, such as IC-141055 and IC-141040, and wild accessions of A. tetraphyllus, including IC-90515 and IC-90746-1, these plants are characterized by their small, deeply serrated leaves. These traits contribute to reduced infestation rates of BYVMV (Bhindi Yellow Vein Mosaic Virus) and ELCV (Enation Leaf Curl Virus), as the compact leaf structure offers less space for vectors to thrive. Consequently, these species are promising candidates for breeders to consider in crop improvement programs.

Distribution of branches of anterior choroidal artery in the uncus: an anatomical study.

The aim of our study was to examine the relationship between uncus and uncal branches of anterior choroidal artery (AChA) and to observe the morphological and morphometric features of these branches. 124 hemispheres from 62 fresh cadavers were included in the study. Measurement of the length of AChA and the distances of the uncal branches to the origin of AChA were measured by ImageJ software. Morphological variations of uncal branches originating from AChA were observed. The length of AChA was found as mean 26.24 ± 4.34mm. It was determined that the average distance of these uncal branches arising from the AChA was 13.48 ± 7.31mm. In 4 out of 124 AChAs, no branches were observed. 594 branches originating from 120 were detected. 130/594 branches appeared to be terminal branches. AChAs of 80/120 hemispheres have been reported to have uncal branches. Thirty of 130 uncal branches were observed to originate as the first branch of AChA. It was found that uncal branches may originate from AChA with a variability between 1 and 4. When evaluated according to the origin of each branch from the AChA, it was observed that the uncal branches originated from the midpoint of the AChA on average. Also, in 64 hemispheres, morophological variations were detected regarding the origin of uncal branches. We believe that the morphological and morphometric data we obtained from the uncal branches of the AChA are of clinical importance in terms of understanding this complex region and minimizing errors in surgical procedures.

Distribution and morphological variation of the freshwater halacarid mite Lobohalacarus weberi (Romijn & Viets, 1924) (Acari, Halacaridae) in Japan

The morphological variations of the subterranean freshwater halacarid mite Lobohalacarus weberi (Romijn & Viets) were examined for five regional populations in the Japanese Archipelago. When examining a total of 12 females and four deutonymphs, one of the four females in a single population had almost no frontal spine. Variations in the number of genital acetabula, perigenital setae, and leg chaetotaxy accorded well with the results of morphological variations in previous studies. The present distributional results and previous records of L. weberi in Japan showed the possibility of the species being distributed throughout the Japanese Archipelago. Considering the entire distributional records on the continent neighbouring Japan and the Japanese Archipelago lying relatively close to the continent, relictualism seems to effectively explain the current distribution of L. weberi in the Japanese Archipelago and on the continental landmass.

Morphological variations of the middle and superior turbinates, olfactory fossa and nasal septum in different sphenoid sinus pneumatization patterns.

Detailed assessment of the extrasinusal pneumatization of the superior and middle turbinate (SCB, MCB), olfactory fossa (OFP), and nasal septum (NSP) in coronal and sagittal sphenoid sinus (SS) pneumatization types provides a precise understanding of the surgical corridors used for skull base surgery. We aimed to analyze the relationships among these variations using computed tomography (CT) images. CT images of 153 patients were retrospectively analyzed for all types of sinonasal pneumatizations and volumes of SCB and sphenoid sinus, together with the prevalence of mucosal thickening of the sphenoid sinus (MTSS). The prevalences of cellular, extensive, and complete SCB were 28.6%, 21.1%, and 23.5% in prepterygoid; 38.1%, 42.1%, and 35.3% in prerotundum; and 33.3%, 36.8%, and 41.2% in postrotundum CSSP types, respectively. The frequencies of lamellar, bulbous, and extensive MCB were 29%, 14.3%, and 33.3% in pterygoid, 38.7%, 57.1%, and 25.9% in prerotundum, 32.3%, 8%, and 40.8% in postrotundum CSSP types, respectively. SCB and MCB were observed unilaterally at 24.8% and 30% and bilaterally at 12.8% and 32.7%, respectively. OFP, NSP, and MTSS were detected at 24.2%, 31.4%, and 27.5%, respectively. Increased age was significantly associated with a lower probability of pneumatization in SS and MCB. The data obtained showed that the degree of SS pneumatization significantly affected the frequencies of the SCB, MCB, OFP, NSP, and MTSS. Also, the SCB volume is significantly related to the CSSP types. Preoperative CT evaluation is crucial for surgeons to be aware of these variations and to avoid iatrogenic injury.

Late Pleistocene onset of mutualistic human/canid (Canis spp.) relationships in subarctic Alaska.

Large canids (wolves, dogs, and coyote) and people form a close relationship in northern (subarctic and arctic) socioecological systems. Here, we document the antiquity of this bond and the multiple ways it manifested in interior Alaska, a region key to understanding the peopling of the Americas and early northern lifeways. We compile original and existing genomic, isotopic, and osteological canid data from archaeological, paleontological, and modern sites. Results show that in contrast to canids recovered in non-anthropic contexts, canids recovered in association with human occupations are markedly diverse. They include multiple species and intraspecific lineages, morphological variation, and diets ranging from terrestrial to marine. This variation is expressed along both geographic and temporal gradients, starting in the terminal Pleistocene with canids showing high marine dietary estimates. This paper provides evidence of the multiple ecological relationships between canids and people in the north-from predation, probable commensalism, and taming, to domestication-and of their early onset.

Effect of CAD/CAM Abutment Morphology on the Outcomes of Implant Therapy: A Randomized Controlled Trial.

Variations in transmucosal abutment contour design may affect the outcomes of implant therapy. This randomized controlled trial was primarily aimed at testing the effect that CAD/CAM zirconia abutments with either a concave or linear divergent transmucosal morphology have on peri-implant mucosal dynamics and indicators of peri-implant health at 1 year after final implant-supported prosthesis insertion in the anterior maxilla. Following computer-guided implant placement and osseointegration, eligible subjects were randomized into either the experimental (concave morphology) or the control (linear divergent morphology) group. A comprehensive set of outcomes of interest related to peri-implant soft tissue dynamics, phenotypical features, and indicators of peri-implant health were assessed at different time points over a 1-year period after insertion of the final restoration. Out of 60 initially recruited subjects, a total of 54 completed the study (n = 29 in the experimental group concave/n = 25 in the control group). Overall implant survival and restoration rates between master impression and 12 months were 100% and 98.2%, respectively. Although a trend for coronal migration of the buccal mucosa zenith, gain in mucosal thickness, and increased probing depth and bleeding on probing was observed in both groups, these changes were clinically negligible, and no substantial differences were observed between study groups regardless of variations in transmucosal abutment morphology. The use of either linear divergent or concave custom CAD/CAM zirconia abutments in a screw-retained, delayed loading approach yielded no significant differences.

Phenotypic Plasticity, Multiple Paternity, and Shell Shape Divergence Across Lake‐Stream Habitats in a Freshwater Mussel Brood (Pyganodon grandis)

ABSTRACT Hydrodynamic forces and their absence appear to exert differential selection pressure on aquatic biodiversity in lake and stream habitats, creating a tight fit between organismal phenotypes and their environments. Ecophenotypic variants may be the result of genetic differentiation or phenotypic plasticity, where a genotype can produce multiple phenotypes dependent on the environment. Freshwater mussels possess a wide degree of morphological variation that frequently covaries with the environment, making them a good system to understand the mechanisms of ecophenotypic variation across hydrological conditions. We designed a two‐year experiment where individuals from the same Pyganodon grandis maternal brood (half and full siblings) were reared at a controlled site and four natural sites involving one lake and three streams. At the end of the experiment, shell shape was quantified for recaptured (N = 70), wild (N = 206), and zoo‐reared (N = 305) mussels. The maternal individual and 46 recaptured mussels were sequenced for genomic single nucleotide polymorphisms to test for multiple paternity and its effect on offspring morphology. Analysis of covariance found significant differences in shell shape between rearing sites, particularly between stream and lake habitats, but no shape differences were detected across the three stream sites. At two of the four sites, the shell shape of recaptured individuals was not significantly different than that of wild populations. Genomic sequencing and parentage analysis identified 11–27 different fathers among recaptured individuals. Yet no genetic differences were present between stream and lake habitats, and there was no paternal effect on shell shape. Taken together, phenotypic plasticity, over genetic differentiation, is identified as the primary mechanism of ecophenotypic variation. Plasticity is likely ubiquitous across freshwater mussels and may be a key adaptation given their high variance in habitat use. Multiple paternity may also play a role in the evolution of phenotypic plasticity, allowing more males from greater distances opportunities for fertilization, thus increasing genetic connectivity. Lastly, phenotypic plasticity and multiple paternity are convenient properties for freshwater mussel conservation and propagation. Multiple fathers increase the genetic variation of propagated broods, while plasticity may provide resilience to the release of stocked individuals across environmental heterogeneity.

Redescription of Physaloptera sarcophili Johnston & Mawson, 1940 and the description of Physaloptera dasyuri sp. nov. (Nematoda: Spirurida) parasitic in Australasian dasyurid marsupials

ABSTRACT Physaloptera sarcophili Johnston & Mawson, 1940 (Nematoda: Spirurida), originally described from the Tasmania devil, Sarcophilus harrisii (Boitard), is redescribed based on additional material from this host species. Physaloptera dasyuri sp. nov. is described from quolls, Dasyurus maculatus (Kerr) from Tasmania, Dasyurus hallucatus Gould from the Northern Territory and the Kimberly District of Western Australia and Dasyurus albopunctatus Schlegel from New Guinea. The two nematode species are distinguished by measurements, with values of those of P. sarcophili being approximately twice as large as those of P. dasyuri sp. nov. and by differences in the ratio of right to left spicule lengths. Limited morphological variation in the distribution of the papillae on the caudal bursa is described. Both species are differentiated from congeners in Australian mammals by the presence of four sessile post-cloacal papillae arranged in a single row, the arrangement of the three pairs of post-cloacal sessile papillae and spicule measurements. The differentiation of both species from congeners in South American marsupials and eutherian carnivores is also discussed.

Response of Morphological Plasticity of Quercus variabilis Seedlings to Different Light Quality

This experiment explores the regulatory mechanisms of various light qualities on the phenotypic plasticity of Quercus variabilis seedlings during their growth. The light conditions included blue light (BL), red light (RL), far-red light (FrL), a blend of RL and FrL with a ratio of 1:1 (RFr1:1L), and a blend of RL and FrL with a ratio of 1:2 (RFr1:2L), alongside a broad-spectrum white light (WL) as the control. Each treatment was maintained at a consistent photosynthetic photon flux density of 400 µmol·m−2·s−1. Results indicate significant morphological variations in Q. variabilis seedlings under different light qualities. Compared to white light treatment, all light quality treatments enhance seedling height, with the FrL treatment exhibiting the most pronounced effect. Seedling ground diameter elongation is stimulated by all light quality treatments, except for the BL treatment. Although the BL treatment promotes leaf morphology in Q. variabilis seedlings, it inhibits root growth, leading to reduced biomass accumulation and a lower root-to-shoot ratio. FrL can mitigate the effects of RL. Under the FrL treatment, Q. variabilis seedlings exhibit a greater increase in plant height and a higher height-to-diameter ratio. While the leaf morphology of RFr1:1L treatment does not show significant advantages, it demonstrates substantial root growth, resulting in the highest biomass accumulation. Quercus variabilis displays the strongest morphological plasticity in its root system, showing greater sensitivity to variations in light quality compared to leaf morphology and biomass accumulation. Strategically optimizing light spectrum and wavelength can significantly boost economic yields and improve the quality of forestry products.

Untangling the morphological and genetic variation of two endemic lizards from the coastal sand dunes of Northeastern Brazil

Abstract Studies in the Neotropical region consistently highlight high levels of endemism and biodiversity. However, challenges persist, particularly in uncovering the cryptic diversity among species. Various approaches are needed to address this, including morphological, genetic, and environmental data. This study focused on genetic and morphological variation in three endemic, sympatric lizard species: Tropidurus hygomi, Glaucomastix abaetensis, and Glaucomastix itabaianensis in the coastal sand dunes of Northeastern Brazil. These lizards are confined to sandy Pleistocene-formed environments with limited distribution. While earlier research revealed substantial genetic diversity, gaps remained in distribution sampling, morphological data, and understanding the correlation between this variation and environmental factors. We aimed to identify genetic clusters to assess the alignment of phenotypic differences with these clusters and explore potential relationships between climatic and geographical factors and morphometric variations. We utilized mtDNA data to assess population clusters. Geometric and linear morphometrics were employed to analyze morphological data, which was then correlated with climatic information. Results unveiled genetic and morphological variations signifying the presence of cryptic diversity. Our analyses also highlighted the influence of geography and climate on morphometric variations. These findings underscore hidden diversity and a complex evolutionary history within the confined Pleistocene sand dunes. Further genomic analyses could contribute to comprehending these patterns and enhancing the conservation strategies for these endangered species.

An innovative methodology for segmenting vessel like structures using artificial intelligence and image processing

Innovation is currently driving enhanced performance and productivity across various fields through process automation. However, identifying intricate details in images can often pose challenges due to morphological variations or specific conditions. Here, artificial intelligence (AI) plays a crucial role by simplifying the segmentation of images. This is achieved by training algorithms to detect specific pixels, thereby recognizing details within images. In this study, an algorithm incorporating modules based on Efficient Sub-Pixel Convolutional Neural Network for image super-resolution, U-Net based Neural baseline for image segmentation, and image binarization for masking was developed. The combination of these modules aimed to identify capillary structures at pixel level. The method was applied on different datasets containing images of eye fundus, citrus leaves, printed circuit boards to test how well it could segment the capillary structures. Notably, the trained model exhibited versatility in recognizing capillary structures across various image types. When tested with the Set 5 and Set 14 datasets, a PSNR of 37.92 and SSIM of 0.9219 was achieved, surpassing significantly other image superresolution methods. The enhancement module processes the image using three different varaiables in the same way, which imposes a complexity of O(n) and takes 308,734 ms to execute; the segmentation module evaluates each pixel against its neighbors to correctly segment regions of interes, generating an quadratic complexity and taking 687,509 ms to execute; the masking module makes several runs through the whole image and in several occasions it calls processes of complexity at 581686 microseconds to execute, which makes it not only the most complex but also the most exhaustive part of the program. This versatility, rooted in its pixel-level operation, enables the algorithm to identify initially unnoticed details, enhancing its applicability across diverse image datasets. This innovation holds significant potential for precisely studying certain structures’ characteristics while enhancing and processing images with high fidelity through AI-driven machine learning algorithms.

Behavior of PGS/apatite foam scaffolds during incubation in SBF, PBS, Ringer's solution, artificial saliva, and distilled water.

Poly(glycerol sebacate) is a polymeric material with potential biomedical application in the field of tissue engineering. In order to act as a biodegradable scaffold, its incubation study is vital to simulate its behavior. This study explores the degradation of porous poly(glycerol sebacate)/hydroxyapatite scaffolds subjected to incubation in various physiological solutions. The research involved monitoring pH and conductivity values over a 14-day period, as well as analyzing the swelling capacity and mass alterations of the scaffolds. In simulated body fluid (SBF) and phosphate-buffered saline (PBS), the pH levels remained relatively stable, whereas Ringer's solution caused a pH decrease. Conversely, artificial saliva demonstrated an increase in pH, and distilled water caused a slight decrease. The conductivity values remained stable in SBF and Ringer's solution, slightly decreased in PBS, increased in artificial saliva, and significantly increased in distilled water. The swelling capacity of the scaffolds varied depending on the solution used, with the lowest equilibrium swelling observed in SBF and PBS. The effect of the presence of ceramics on this parameter was also observed. The mass changes of the scaffolds indicated deposition of particles or salts from the incubation solutions, and subsequent rinsing in distilled water led to a decrease in mass. Scanning electron microscopy (SEM) imaging and elemental analysis confirmed the presence of crystallized salts on the scaffold surfaces after incubation in SBF. Surface roughness measurements revealed changes in roughness depending on the solution, with deposition of additional layers in SBF and degradation in artificial saliva. In summary, the scaffolds exhibited biodegradation in physiological solutions, with variations in pH, conductivity, swelling capacity, mass changes, and surface morphology depending on the specific solution and scaffold composition.

Radial variation of fiber morphology and wood density of the commercial species Drypetes sp. and Myroxylon balsamum

Studying the radial variation of wood density, an essential biophysical property that reflects the quality of commercial species in tropical forests, is crucial. Understanding how these variations relate to wood anatomy provides valuable insights. In this study, we evaluated fiber morphology and radial density variation using X-ray densitometry in two commercial species from southeastern Peru. Ten trees from each species, Drypetes sp. and Myroxylon balsamum (Peru balsam), were analyzed. Fiber characteristics were assessed using macerated tissue, and density profiles were obtained via X-ray densitometry. The results indicate that in Drypetes sp., density decreases from the pith to the bark, whereas Myroxylon balsamum shows no significant radial variation. These findings are important for the efficient use and processing of these species.

Intraspecific variability of rice root knot nematodes across diverse agroecosystems for sustainable management

In the rice agroecosystems of Southeast Asia, rice root knot nematode (Meloidogyne graminicola) significantly impairs yield, representing a major species within the ‘graminis-group’ known for its morphological similarities with other root knot nematodes (RKNs). This study delves into the variations in reproductive potential, morphology, morphometrics, and genetic diversity among thirty RKN populations in rice across three distinct agroecological zones in Jharkhand, India. Despite notable differences in reproductive potential among the populations, morphological and morphometric correlations to reproductive potential were inconclusive. However, male and juvenile morphometrics were crucial for identifying intraspecific variability. Genetic analysis utilizing five molecular markers (ITS, 18 S rRNA, D2-D3 of 28 S, COX-I, and COX-II) affirmed the populations as M. graminicola, with ITS marker revealing significant intraspecific variability. Phylogenetic analysis underscored the close relationship between M. oryzae and M. graminicola, distinct from other mitotic RKN species. Low genetic distance and nucleotide diversity, coupled with high haplotype diversity, negative Tajima’s D, and Fu’s Fs of haplotype network analysis, suggested that all M. graminicola populations are expanding. These findings highlight the urgent need for comprehensive management strategies against M. graminicola, providing valuable insights for growers, extension officials, and plant breeders to develop targeted management approaches and resistance breeding programs.

Study on the deformation mechanism of chair-like bedding rock landslides under the coupling effect of geological and hydrological factors

Chair-like bedding rock landslides are prevalent in the Three Gorges Reservoir area (TGRA), necessitating further investigation into their inducing mechanisms. This study focuses on the Muyubao and Tanjiahe landslides, conducting a comparative analysis of their deformation characteristics and mechanisms while comprehensively considering geological and hydrological factors. The findings indicate that the Muyubao landslide was primarily triggered by the combined effects of rainfall during the water storage period and the rise of the reservoir water levels (RWL), with a threshold of approximately 165 m. In contrast, the Tanjiahe landslide was influenced by a rapid drawdown in RWL, heavy rainfall, and a high RWL, with a threshold of around 175 m. Both landslides exhibited a clear response to the rise in groundwater levels in the steep sections, with significant deformation occurring when groundwater levels reached 175 m (Muyubao landslide QSK1) and 245 m (Tanjiahe landslide QSK2). Notably, variations in landslide morphology, permeability coefficients, and fluctuations in groundwater levels can facilitate the mutual conversion between different landslide types (seepage-driven and buoyancy-driven). To investigate the influence of chair-like slope morphology on landslides, eight landslide models were constructed, featuring a range of dip angles for the rock formation (15° to 30°) and varying length ratios of gentle to steep sections (2:8 to 5:5). The UDEC Code was employed to simulate and analyze the governing effects of slope morphology on landslide deformation and evolution. Through a comparative analysis of the Muyubao, Tanjiahe, Jiuxianping, and Qianjiangping landslide cases, we examined the significant influence of landslide morphology and permeability coefficients on landslide behavior. The results indicate that the length ratio of gentle to steep section is a crucial parameter. When this ratio exceeds 2:8, the landslide is characterized by pushing deformation; conversely, when the ratio is lower, it tends to exhibit overall movement. Additionally, geological factors affect groundwater seepage and water level variation under the influence of rainfall and reservoir water, resulting in distinct deformation characteristics and mechanisms across different landslide types. Factors such as slope angle and the length of the gentle section influence the extent of the submerged area, leading to varied landslide responses to rise of the RWL.

Oxidation behavior and mechanism of 4H-SiC surface by holes in electrochemical and photoelectrochemical systems

4H-SiC serves as an ideal substrate for fabricating high-performance power electronic devices, and the extremely low polishing efficiency is a key constraint to its promotion and application. To explore the oxidation behavior and mechanism of 4H-SiC surfaces can help to achieve efficient surface oxidation and improve the polishing efficiency. Therefore, in this work, a comparative analysis between electrochemical oxidation and photoelectrochemical oxidation of the 4H-SiC substrate surface is carried out. The variations of oxidation current density, surface morphology, oxide thickness, and surface hardness of 4H-SiC substrate are investigated by oxidation experiments, nanoindentation tests, and linear sweep voltammetry (LSV) measurements. Based on the study about the oxidation behavior of 4H-SiC surface by holes and the energy band theory, benzoic acid is introduced as a fluorescence probe to reveal the principles of low-concentration hole induced electrochemical oxidation and high-concentration hole dominated photoelectrochemical oxidation. Evolution models for the oxidation of 4H-SiC surfaces by these two methods are developed, and the differences in oxidation mechanisms are clarified. Photoelectrochemical oxidation is approximately 3 times more efficient than electrochemical oxidation, the former can form a dense and uniform oxide layer. The results of this work provide insights into achieving efficient polishing of 4H-SiC substrate.