Application of kinetic damping in dynamic material point method for static problems

Material point method (MPM) is widely used in geotechnical engineering, owing to its powerful capability of modelling large deformation problems. But the static equilibrium problems involving very large deformation and material non-linearity can be difficult to solve using the quasi-static MPM, because of numerical difficulties with convergence in iterative procedure. An alternative method is the dynamic relaxation (DR) method, which converts the static problem to a dynamic one by considering the virtual masses and artificial damping. This paper presents a method to solve static problems using dynamic MPM with DR technique. An energy ratio and a force ratio are defined to recognize the static equilibrium state from dynamic process first. Then the kinetic damping as an DR technique is introduced into the dynamic MPM for the first time. Finally, two numerical examples are presented to illustrate the convenience and efficiency of the kinetic damping in dynamic MPM for static problems

Physical activity's impact on rural older adult health: The multiple mediating effects of education, income, and psychological capital

IntroductionThis study aims to explore the influence mechanism of rural older adult health. By examining the mediating roles of education, income, and psychological capital in physical activity's impact on health, this study provides a reference for lifestyle interventions to improve the health level of rural older adults.MethodsThe analysis was conducted on a sample of 1778 rural older adults from CGSS2017, and data were analyzed using PROCESS V4.2 for multiple mediating effects.ResultsThe findings indicate that physical activity impacts rural older adult health through multiple mediating pathways. The mediating role includes seven paths, comprising the independent effects of three mediating variables of income, education, and psychological capital, and the chain mediating effects generated together.DiscussionBased on the influence mechanism of health on rural older adults, optimizing policy focus and developing a precise, interconnected, and sustainable health security system for older adults is necessary. These research results are of practical significance for advancing healthy aging in rural areas

Research progress on the impact of mineral surface roughness on particle-bubble interaction

Mineral surface roughness is an important factor affecting flotation efficiency. Surface roughness can affect the hydrophobicity of minerals, the adsorption of reagents, and the rupture of liquid films between particles and bubbles, resulting in a significant impact on the interaction process between particles and bubbles. However, there is currently a lack of systematic review work on the influence of roughness on particle-bubble interaction process. Therefore, the authors firstly reviewed the surface roughening modification techniques and roughness testing methods. Secondly, the influence of roughness on the particle-bubble interaction process was systematically discussed from four aspects: flotation kinetics, contact angle, formation time of triple-phase contact line, and interaction force between particles and bubbles. The concept of roughness scale was proposed for its importance in the research of particle-bubble interactions. Thirdly, based on the coupling mechanism between roughness scale and mineral surface hydrophobicity in the particle-bubble interaction process, the importance of mineral surface wetting state in the interaction process between rough surfaces and bubbles was emphasized. The reasons for the inconsistent research conclusions on the impact of roughness on contact angle and flotation performance were also analyzed and discussed. Finally, the conclusions were drawn through critical analysis and literature review, and the prospects for future research directions were outlined. This paper contributes to a better understanding of the influence of mineral surface roughness on the flotation process, and can provide a theoretical support for regulating mineral surface roughness to create favorable flotation conditions and improve the flotation efficiency and selectivity

Ameliorating effects of Mango (Mangifera indica L.) fruit on plasma ethanol level in a mouse model assessed with 1H-NMR based metabolic profiling

The ameliorating effects of Mango (Mangifera indica L.) flesh and peel samples on plasma ethanol level were investigated using a mouse model. Mango fruit samples remarkably decreased mouse plasma ethanol levels and increased the activities of alcohol dehydrogenase and acetaldehyde dehydrogenase. The 1H-NMR-based metabolomic technique was employed to investigate the differences in metabolic profiles of mango fruits, and mouse plasma samples fed with mango fruit samples. The partial least squares-discriminate analysis of 1H-NMR spectral data of mouse plasma demonstrated that there were clear separations among plasma samples from mice fed with buffer, mango flesh and peel. A loading plot demonstrated that metabolites from mango fruit, such as fructose and aspartate, might stimulate alcohol degradation enzymes. This study suggests that mango flesh and peel could be used as resources for functional foods intended to decrease plasma ethanol level after ethanol uptake

The dynamic transcriptional and translational landscape of the model antibiotic producer Streptomyces coelicolor A3(2)

Individual Streptomyces species have the genetic potential to produce a diverse array of natural products of commercial, medical and veterinary interest. However, these products are often not detectable under laboratory culture conditions. To harness their full biosynthetic potential, it is important to develop a detailed understanding of the regulatory networks that orchestrate their metabolism. Here we integrate nucleotide resolution genome-scale measurements of the transcriptome and translatome of Streptomyces coelicolor, the model antibiotic-producing actinomycete. Our systematic study determines 3,570 transcription start sites and identifies 230 small RNAs and a considerable proportion (∼21%) of leaderless mRNAs; this enables deduction of genome-wide promoter architecture. Ribosome profiling reveals that the translation efficiency of secondary metabolic genes is negatively correlated with transcription and that several key antibiotic regulatory genes are translationally induced at transition growth phase. These findings might facilitate the design of new approaches to antibiotic discovery and development

A single gene of a commensal microbe affects host susceptibility to enteric infection

Indigenous microbes inside the host intestine maintain a complex self-regulating community. The mechanisms by which gut microbes interact with intestinal pathogens remain largely unknown. Here we identify a commensal Escherichia coli strain whose expansion predisposes mice to infection by Vibrio cholerae, a human pathogen. We refer to this strain as 'atypical' E. coli (atEc) because of its inability to ferment lactose. The atEc strain is resistant to reactive oxygen species (ROS) and proliferates extensively in antibiotic-treated adult mice. V. cholerae infection is more severe in neonatal mice transplanted with atEc compared with those transplanted with a typical E. coli strain. Intestinal ROS levels are decreased in atEc-transplanted mice, favouring proliferation of ROS-sensitive V. cholerae. An atEc mutant defective in ROS degradation fails to facilitate V. cholerae infection when transplanted, suggesting that host infection susceptibility can be regulated by a single gene product of one particular commensal species.

Science and technology innovation and practice of major national science and technology special project of coalbed methane in coal mining area

The scientific and technological innovation system formed by the national major oil and gas projects has the characteristics of “new nationwide innovation system”, and the system of scientific and technological projects has the characteristics of “whole process, multi-stage and full life cycle”. During the 11th Five-Year Plan period and 13rd Five-Year Plan period, major national oil and gas projects have continuously supported scientific and technological breakthroughs and technological innovations in basic theories, key technologies and complete sets of equipment for the development and utilization of coalbed methane. Members of the national major projects of oil and gas projects and project implementation unit, paying great efforts, aim to taking the national major projects of oil and gas as an great opportunity, to enhance the level of coal mine area of coalbed methane of science and technology innovation and form the leading industry of coal mining area of coal bed methane research and development of science and technology innovation system, to fully support the realization of key scientific research goals of major national oil and gas projects. Coal mining area coal bed methane grograms have formed a series of major landmark achievements, built a series of industry innovation platform, comprehensively stired the technological progress and industrial development of coal-bed methane industry in coal mining areas of China, and effectively promoted the construction of the coal-bed methane industry in China. Combined with the organization and implementation of the project (subject)/demonstration project and the characteristics of the coal industry, we have systematically summarize the exploration and practice of CBM technological innovation in national major special coal mine area and formed a national major special project of science and technology, which is “guided by national investment, dominated by enterprise investment, highly integrated with industry, university, research and application, and continuously leading the technological progress of the industry”. In establishing and perfecting the organization and management institutions, continue to strengthen the special management specification, continue to play a role of cohesive ties, coordination to promote the scientific research management innovation, promote the development and use fusion to form coal mining area of coalbed methane from the concrete experience of science and technology innovation practice

Clinical features and surgical outcomes of high grade pleomorphic xanthoastrocytomas: a single-center experience with a systematic review

PurposeHigh grade pleomorphic xanthoastrocytomas (HGPXAs) are very rare and their management and prognostic outcomes remain unclear. To better understand the disease, we aimed to evaluate the risk factors for progression-free survival (PFS) and overall survival (OS), and propose a treatment protocol based on cases from our institute and cases from the literature.MethodsThe authors reviewed the clinical data of 26 patients with HGPXAs who underwent surgical treatment in Department of Neurosurgery of Beijing Tiantan Hospital between August 2014 and September 2021. We also searched the PubMed database using the keywords “anaplastic” combined with “pleomorphic xanthoastrocytoma(s)” between January 1997 and October 2022. Risk factors for PFS and OS were evaluated in the pooled cases.ResultsThe authors’ cohort included 11 males and 15 females with a mean age of 36.7 ± 20.3 years (range: 5.5-71 years). Gross-total resection (GTR) and non-GTR were achieved in 17 (65.4%) and 9 (34.6%) patients, respectively. Radiotherapy and chemotherapy were administered to 22 and 20 patients, respectively. After a mean follow-up of 20.5 ± 21.2 months (range: 0.5-78.1 months), 7 patients suffered tumor recurrence and 6 patients died with a mean OS time of 19.4 ± 10.8 months (range: 8-36 months). In the literature between January 1997 and October 2022, 56 cases of HGPXAs were identified in 29 males and 27 females with a mean age of 29.6 ± 19.6 years (range; 4-74 years). Among them, 24 (44.4%) patients achieved GTR. Radiotherapy and chemotherapy was administered to 31 (62%) patients and 23 (46%) patients, respectively. After a median follow-up of 31.4 ± 35.3 months (range: 0.75-144 months), the mortality and recurrence rates were 32.5% (13/40) and 70% (28/40), respectively. Multivariate Cox regression model demonstrated that non-GTR (HR 0.380, 95% CI 0.174-0.831, p=0.015), age≥30 (HR 2.620, 95% CI 1.183-5.804, p=0.018), no RT (HR 0.334,95% CI 0.150-0.744, p=0.007) and no CT (HR 0.422, 95% CI 0.184-0.967, p=0.042) were negative prognostic factors for PFS. Non-GTR (HR 0.126, 95% CI 0.037-0.422, p=0.001), secondary HGPXAs (HR 7.567, 95% CI 2.221-25.781, p=0.001), age≥30 (HR 3.568, 95% CI 1.190-10.694, p=0.023) and no RT (HR 0.223,95% CI 0.073-0.681, p=0.008) were risk factors for OS.Conclusion:High grade pleomorphic xanthoastrocytomas are very rare brain tumors. Children and younger adults have better clinical outcome than elderly patients. Secondary HGPXAs had worse OS than primary HGPXAs. Complete surgical excision plus RT and CT is recommended for this entity. The frequency of BRAF mutations in HGPXAs is 47.5% (19/40) in this study, however, we do not find the connections between BRAF mutations and clinical outcomes. Future studies with larger cohorts are necessary to verify our findings

Impaired pattern separation in Tg2576 mice is associated with hyperexcitable dentate gyrus caused by Kv4.1 downregulation

Alzheimers disease (AD) is a progressive neurodegenerative disorder that causes memory loss. Most AD researches have focused on neurodegeneration mechanisms. Considering that neurodegenerative changes are not reversible, understanding early functional changes before neurodegeneration is critical to develop new strategies for early detection and treatment of AD. We found that Tg2576 mice exhibited impaired pattern separation at the early preclinical stage. Based on previous studies suggesting a critical role of dentate gyrus (DG) in pattern separation, we investigated functional changes in DG of Tg2576 mice. We found that granule cells in DG (DG-GCs) in Tg2576 mice showed increased action potential firing in response to long depolarizations and reduced 4-AP sensitive K+-currents compared to DG-GCs in wild-type (WT) mice. Among Kv4 family channels, Kv4.1 mRNA expression in DG was significantly lower in Tg2576 mice. We confirmed that Kv4.1 protein expression was reduced in Tg2576, and this reduction was restored by antioxidant treatment. Hyperexcitable DG and impaired pattern separation in Tg2576 mice were also recovered by antioxidant treatment. These results highlight the hyperexcitability of DG-GCs as a pathophysiologic mechanism underlying early cognitive deficits in AD and Kv4.1 as a new target for AD pathogenesis in relation to increased oxidative stress.This research was supported by the Korean Ministry of Science and ICT (NRF2017R1A2B2010186 and NRF-2020R1A2B5B02002070 to WH)