425 research outputs found
AE energy evolution during CJB fracture affected by rock heterogeneity and column irregularity under lateral pressure
No full textData availability: The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request.Copyright © 2022 The Author(s). Considering that the mechanical mechanism and energy release law of gradual failure of columnar jointed basalt (CJB) are affected by lateral pressure, rock heterogeneity and column irregularity, etc., the numerical CJB models with various column dip angles, irregularity degrees of column and lateral pressures were established through the digital image correlation. The progressive failure process and released energy of CJBs were simulated under the loading rate of 0.05 mm/step based the continuum mechanics and statistical damage theory. The influences of rock inhomogeneity, column irregularity degree, and model boundary on the nonlinear deformation and failure of CJB were comprehensively investigated. The results demonstrate that the effect of the inhomogeneity index depends on column dip angle, and the equivalent deformation modulus of CJBs is more sensitive to the inhomogeneity index than the lateral pressure. Moreover, the compressive strength along the direction perpendicular to the column axis basically decreases with column irregularity degree increasing when the meso strength of rock is 120 MPa. Besides, the mechanical properties and elastic energy of irregular CJBs are greatly affected by the model boundaries. These achievements will contribute to understanding the inner failure mechanism and energy evolution of CJBs.National Natural Science Foundation of China (Grant No 42102314); China Postdoctoral Science Foundation (Grant No. 2020M680950)
Molecular identification of three isolates of Trichoderma harzianum isolated from agricultural soils in Argentina, and their abilities to detoxify in vitro metsulfuron methyl
No full textMetsulfuron methyl (MM) is a sulfonylurea herbicide used worldwide for the control of weeds in cereal crops. In a previous study, three Trichoderma strains (T5, T6, and T7) capable of using MM as a sole carbon and energy source were isolated. In this study, the three strains were identified as Trichoderma harzianum using genetic markers, and the transformation of MM by the T. harzianum strains was quantified using spectrophotometry. Solutions of different phytotoxic doses of MM were incubated with plugs of mycelia of the Trichoderma strains and the resulting mixtures were used to assess MM detoxification. The toxicity of the degradation products was tested with a bioassay using pre-germinated seeds of Lens culinaris Medik. and mycelia. Strain T7 was more efficient in transforming MM at higher concentrations than the T5 and T6 strains. In the bioassay, T5 showed the best performance at higher MM doses. We conclude that both T5 and T7 strains are promising for further studies regarding treatment or amelioration of MM contaminated soils.Le metsulfuron méthyle (MM) est une sulfonylurée herbicide utilisée a` travers le monde pour contrôler les mauvaises herbes des champs de céréales. Dans une étude précédente, trois souches de Trichoderma (T5, T6 et T7) capables d'utiliser le MM comme unique source de carbone et d'énergie avaient été isolées. Dans l'étude actuelle, les trois souches ont attribuées a` Trichoderma harzianum par des marqueurs génétiques, et la transformation du MM par les souches de T. harzianum a été quantifiée par spectrophotométrie. Des solutions comprenant différentes doses phytotoxiques de MM ont été incubées avec des boulettes de mycélium des souches de Trichoderma et les mélanges résultants ont été utilisés afin d'évaluer la détoxication du MM. La toxicité des produits de dégradation a été testée par un dosage biologique a` l'aide de graines pré-germées de Lens culinaris Medik. et du mycélium. La souche T7 était plus efficace que les souches T5 et T6 dans la transformation du MM a` des concentrations plus élevées. Lors de l'essai biologique, la souche T5 affichait la meilleure performance a` des doses de MM plus élevées. Les auteurs concluent que les souches T5 et T7 sont prometteuses en vue d'études futures dans la perspective de traitement ou d'amélioration de sols contaminés au MM. [Traduit par la Rédaction]Fil: Vazquez, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Barrera, Viviana. Instituto Nacional de Tecnología Agropecuaria. Centro Nacional de Investigaciones Agropecuarias. Centro de Investigación de Ciencias Veterinarias y Agronómicas. Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Bianchinotti, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); Argentina. Universidad Nacional del Sur; Argentin
Comparative analysis of aluminum accumulation in leaves of three angiosperm species
No full textAluminum (Al) accumulators are widely distributed in the plant kingdom but phylogenetic implications of internal Al detoxification mechanisms are not well understood. We investigated differences in the characteristics of Al accumulation (i.e., accumulation potential, chemical form, and localization) in three woody Al accumulators, Symplocos chinensis (Lour.) Druce var. leucocarpa (Nakai) Ohwi f. pilosa (Nakai) Ohwi (Symplocaceae, Ericales), Melastoma malabathricum L., and Tibouchina urvilleana Cogn. (both Melastomataceae, Myrtales). The order of Al accumulation potential under hydroponic conditions was S. chinensis approximate to M. malabathricum > T. urvilleana. Oxalate was at least partly involved in the internal Al detoxification mechanisms in leaves of all three Al accumulators, based on a correlation analysis between Al and organic acid in water and 0.02 mol.L-1 HCl extracts and the Al-27 nuclear magnetic resonance spectra of intact leaves. However, the Al forms in the leaves were not simple Al-ligand complexes in a specific cell structure. Al localization in leaf sections differed among the three species. Extremely high levels of Al were found in trichomes of the lower epidermis in leaves of T. urvilleana. These data illustrate that woody Al-accumulating angiosperms have independently developed various internal Al-tolerance mechanisms in which oxalate plays a significant role
Local differentiation of flowering phenology in an alpine-snowbed herb Gentiana nipponica
No full textPhenological events of alpine plants are strongly influenced by the seasonal thermal conditions at the local scale that are caused by heterogeneity in snowmelt time. Populations in late-snowmelt locations suffer from a short period for seed maturation, in which rapid flowering that occurs soon after snowmelt (i.e., a low thermal requirement for flowering) is advantageous. To test the possibility of local adaptation of flowering phenology, we compared reproductive phenology, the preflowering period, and the thermal requirement for flowering of the alpine-snowbed species Gentiana nipponica Maxim. between populations inhabiting early- and late-snowmelt sites within a local area. Plants in the late-snowmelt population showed a shorter preflowering period than in the early-snowmelt population; nevertheless, they often failed to set fruit owing to the short growth period. To test the plasticity and genetic regulation of flowering phenology, we performed a reciprocal transplant experiment between early- and late-snowmelt populations. Although the preflowering period showed clear plastic responses depending on the transplanted habitats, the lower thermal requirement for flowering was retained in plants originating from the late-snowmelt populations, even after transplantation. Therefore, habitat-specific differentiation of flowering phenology was genetically determined between these local populations
Spatial and temporal assessments of genetic structure in an endangered Garry oak ecosystem on Vancouver Island
No full textGarry oak (Quercus garryana Dougl. ex Hook.) is a deciduous tree whose ecosystem is listed “at-risk” throughout its range in British Columbia (B.C.), Canada, under the Canadian Species at Risk Act (SARA). Garry oak ecosystems host the most diverse flora for coastal B.C. yet they account for less than 0.3% of the province’s land-base. Due to the loss and degradation of Garry oak habitat, many associated plant and animal species that rely on these sensitive ecosystems are endangered. Microsatellite markers were used to investigate temporal changes in fine-scale population genetic structure of 121 Garry oak trees from the Nanaimo region (Vancouver Island, B.C.) using diameter at breast height as a proxy for age. Overall, allelic diversity was moderate, ranging from 3.0 to 7.5 alleles per locus with an average of 4.4 (± 0.4 SE) across all loci. Global FST of 0.06 and 0.09 suggests significant departures from Hardy-Weinberg equilibrium among all populations and age-classified subpopulations, respectively. We found no evidence for change in genetic diversity across generations. Our results indicate low levels of differentiation within populations and high levels of gene flow among populations, suggesting an adaptive potential for Garry oaks in response to future climate change events.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Haiku, Spiritual Exercises, and Bioethics
No full textPierre Hadot has discussed the deep connections between ancient Western philosophy and spiritual exercises. The author appreciates these connections, but he explains why he explored a different path. He began to write haiku as a form of spiritual practice. He wanted to use these short verses to become more mindful, present, and responsive – in his life and in his work in bioethics. After comparing traditional haiku and modern haiku, the author gives some examples from classical sources. Then he considers how reading and writing haiku might help bioethics to focus less on deliberation and choice, and more on attention and perception. Haiku might help bioethics to attend to the contexts, life conditions, and lifeworlds that shape and situate people’s lives. These short poems might even illuminate some of the backgrounds and existential grounds of ethical life. At the end, the author presents some haiku that he wrote about modern life, young children, older adults, illness, medicine, and death
Central Management of Research Misconduct in the USA and Canada
No full textThis paper proposes major changes in how research misconduct cases should be managed in the USA and Canada. Specifically, I advocate for centralized oversight that completely removes research institutions from this role in order to: mitigate institutional conflicts of interest, standardize definitions of research misconduct, better preserve confidentiality of complainants (those alleging misconduct), ensure that cases are not screened for rejection, mobilize a review panel of experts who are free of conflicts of interest, avoid inappropriate collective punishment of institutions, and ultimately save resources as compared to current decentralized systems. Two cases which this author, as complainant, alleged research misconduct (in the USA and Canada) demonstrate clearly how far institutional Research Integrity Officers can go to prevent an impartial expert review. Given that our institutions and scientific community rightly have zero tolerance for research misconduct, the current decentralized practice should be a grave concern to those who hope to trust in proper oversight. A discussion follows, including comments on new directives for 2025 from the US Office of Research Integrity and the implications of high-profile cases. I conclude with details as to how cases might be brought to justice under the proposed centralized process
Population Decline of Endangered Lichen Erioderma pedicellatum in Nova Scotia, Canada
No full textErioderma pedicellatum (Hue) P.M. Jørg. (1972) is a globally endangered lichen known from only four countries worldwide. The Atlantic population in Nova Scotia, Canada has been declining for at least the last several decades. The population has been closely monitored between 2003 and 2012 to determine mortality rates by life stage and population growth. A population viability model was created to assess the future viability of this population. The population declined by 12.8% over the ten year monitoring period. Mortality rates for juveniles were significantly lower than for adults. The population viability model suggests the population in Nova Scotia will decline by 49% within 25 years. Conservation measures aimed at prolonging adult survival or increasing juvenile survival is, according to the model, the best way to maintain the population.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Numerical investigation on anisotropy and shape effect of mechanical properties of columnar jointed basalts containing transverse joints
No full textData Availability: The datasets generated and/or analyzed during the current research are available from the corresponding author upon reasonable request.Copyright © The Author(s) 2022. We studied the non-linear mechanical response and failure mechanism of columnar jointed basalts (CJBs) with transverse joints by modeling meso-mechanics, statistical damage theory and continuum mechanics. The anisotropy and shape effect of CJBs with transverse joints were captured under different lateral pressures. The digital images were transformed into heterogeneous element meshes, and the gradual fracturing process and various failure modes of CJBs were reproduced. The compressive strength (CS) and equivalent deformation modulus (EDM) of CJBs parallel and perpendicular to the column axis were studied. The results show that the U-shaped CS curve of CJB appears as the column dip angle increases, and the CS is obviously improved as the lateral pressure increases when the column dip angle is 0°–90°. When the shape of CJB changes from 6 m × 3 m, 3 m × 3 m to 1.5 m × 3 m, the CS continues to increase. Meanwhile, the transverse joints are proven to be critical for determining the mechanical properties of CJBs at the certain dip angles of columns. However, the high lateral pressure can reduce the CS difference between the CJBs with and without the transverse joints. Besides, as the elastic modulus of joints rises, the CS will grow up, and the EDM will increase first and then almost remain at the same level. The coefficient of rock residual strength has a great influence on the CS at the certain dip angles of columns. Additionally, the model boundary significantly affects the anisotropy and shape effect of mechanical properties of CJBs under compression. These conclusions will improve our knowledge of the failure mechanisms and failure patterns of CJBs containing transverse joints.National Natural Science Foundation of China (Grant Nos. 42102314 and 42050201); China Postdoctoral Science Foundation (Grant No. 2020M680950)
The importance of living collections for botanical research: Araceae as a case study
No full textBotanical gardens play a crucial role in botanical research by maintaining living collections of plants that serve educational and scientific purposes. This article examines the significance of living collections, using the Araceae family as a case study. Botanical gardens worldwide house diverse collections that contribute to studies in systematics, taxonomy, anatomy, morphology, floral biology, pollination ecology, phytochemistry, and medicine. The Araceae family, with its extensive diversity and distribution, provides an excellent model for comparative studies. Historical and contemporary research has utilized these collections to advance knowledge in specific areas. For instance, molecular systematics has benefited from these collections, as have studies on calcium oxalate crystal production, floral anatomy and development, pollen-ovule ratios, pollen viability, seed size and growth type, thermogenesis, and pollination syndromes. The article highlights the indispensable role of living collections in facilitating research that would be challenging to conduct solely in the field. It underscores the need for continued investment in botanical gardens to preserve their scientific and educational value, and outlines future research opportunities that living collections can offer.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
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