• Title/Summary/Keyword: Impact-resistance

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Pile tip grouting diffusion height prediction considering unloading effect based on cavity reverse expansion model

  • Jiaqi Zhang;Chunfeng Zhao;Cheng Zhao;Yue Wu;Xin Gong
    • Geomechanics and Engineering
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    • v.37 no.2
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    • pp.97-107
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    • 2024
  • The accurate prediction of grouting upward diffusion height is crucial for estimating the bearing capacity of tip-grouted piles. Borehole construction during the installation of bored piles induces soil unloading, resulting in both radial stress loss in the surrounding soil and an impact on grouting fluid diffusion. In this study, a modified model is developed for predicting grout diffusion height. This model incorporates the classical rheological equation of power-law cement grout and the cavity reverse expansion model to account for different degrees of unloading. A series of single-pile tip grouting and static load tests are conducted with varying initial grouting pressures. The test results demonstrate a significant effect of vertical grout diffusion on improving pile lateral friction resistance and bearing capacity. Increasing the grouting pressure leads to an increase in the vertical height of the grout. A comparison between the predicted values using the proposed model and the actual measured results reveals a model error ranging from -12.3% to 8.0%. Parametric analysis shows that grout diffusion height increases with an increase in the degree of unloading, with a more pronounced effect observed at higher grouting pressures. Two case studies are presented to verify the applicability of the proposed model. Field measurements of grout diffusion height correspond to unloading ratios of 0.68 and 0.71, respectively, as predicted by the model. Neglecting the unloading effect would result in a conservative estimate.

Evaluation of Factors Affecting the Use of the Accounting Information System Using the TAM Model: A Field Study in Algerian Firms

  • Widad Benzine;Ahcene Tiar
    • Asia pacific journal of information systems
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    • v.32 no.2
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    • pp.435-459
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    • 2022
  • The accounting literature abounds with many studies concerning the organizational and technical aspects of the AIS to simulate progress in the business environment. However, few studies have focused on the role of individual factors in overcoming resistance to change and maximizing the value of using the system. Therefore, this study aims to shed light on user beliefs by evaluating the factors that affect the use of the AIS using a developed TAM. A total of 132 subjects participated in this study, in which the questionnaire was used as a data collection tool and AMOS was used to test the model. The results showed that subjective norm, training and experience were the most important previous factors that affect the perceptual factors represented in usefulness, ease of use and the inevitability of change, which all had an impact on the continuance intention to use the AIS among users in Algerian firms. This study shed light on the importance of assessing individual factors rather than focusing only on the ways to develop AIS or researching for new technologies and the costs of this investment because this will increase the chances of success in using the system.

Shear mechanical behavior of prefabricated and assembled multi-key group stud connectors

  • Liang Fan;Wen Zeng;Wenhao Zhao;Mengting Wang
    • Steel and Composite Structures
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    • v.51 no.1
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    • pp.9-24
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    • 2024
  • In order to study the shear mechanical behavior of prefabricated and assembled multi-key group stud connectors, this paper conducted push-out tests on 10 prefabricated and assembled multi-key group stud connectors, distributed in 5 groups, and detailed the failure modes of each specimen. Based on the finite element software, a total of 22 models of this type of stud connector are established, and validated the finite element models using the push-out tests. Furthermore, the effects of stud diameter, number of key groups, and spacing of key groups on the shear resistance of prefabricated and assembled multi-key group stud connectors are analyzed. Combined with the test and finite element, the force analysis is carried out for the stud and first-pouring and post-pouring concrete. The results show that the spacing and number of key groups have a significant impact on the shear capacity and shear stiffness of the specimen. For a single stud, the shear force is transferred to the surrounding concrete via the stud's root. When the stud is finally cut, the steel and the concrete plate are separated. Under vertical shear force, the top row of studs experiences the highest shear, while the middle row has the least. Based on statistical regression, a formula of assembled multi-key group stud connectors is proposed.

The Role of Upper Airway Microbiome in the Development of Adult Asthma

  • Purevsuren Losol;Jun-Pyo Choi;Sae-Hoon Kim;Yoon-Seok Chang
    • IMMUNE NETWORK
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    • v.21 no.3
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    • pp.19.1-19.18
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    • 2021
  • Clinical and molecular phenotypes of asthma are complex. The main phenotypes of adult asthma are characterized by eosinophil and/or neutrophil cell dominant airway inflammation that represent distinct clinical features. Upper and lower airways constitute a unique system and their interaction shows functional complementarity. Although human upper airway contains various indigenous commensals and opportunistic pathogenic microbiome, imbalance of this interactions lead to pathogen overgrowth and increased inflammation and airway remodeling. Competition for epithelial cell attachment, different susceptibilities to host defense molecules and antimicrobial peptides, and the production of proinflammatory cytokine and pattern recognition receptors possibly determine the pattern of this inflammation. Exposure to environmental factors, including infection, air pollution, smoking is commonly associated with asthma comorbidity, severity, exacerbation and resistance to anti-microbial and steroid treatment, and these effects may also be modulated by host and microbial genetics. Administration of probiotic, antibiotic and corticosteroid treatment for asthma may modify the composition of resident microbiota and clinical features. This review summarizes the effect of some environmental factors on the upper respiratory microbiome, the interaction between host-microbiome, and potential impact of asthma treatment on the composition of the upper airway microbiome.

Optimal sustainable design of steel-concrete composite footbridges considering different pedestrian comfort levels

  • Fernando L. Tres Junior;Guilherme F. Medeiros;Moacir Kripka
    • Steel and Composite Structures
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    • v.51 no.6
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    • pp.647-659
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    • 2024
  • Given the increased interest in enhancing structural sustainability, the current study sought to apply multiobjective optimization to a footbridge with a steel-concrete composite I-girder structure. It was considered as objectives minimizing the cost for building the structure, the environmental impact assessed by CO2 emissions, and the vertical accelerations created by human-induced vibrations, with the goal of ensuring pedestrian comfort. Spans ranging from 15 to 25 meters were investigated. The resistance of the slab's concrete, the thickness of the slab, the dimensions of the welded steel I-profile, and the composite beam interaction degree were all evaluated as design variables. The optimization problem was handled using the Multiobjective Harmony Search (MOHS) metaheuristic algorithm. The optimization results were used to generate a Pareto front for each span, allowing us to assess the correlations between different objectives. By evaluating the values of design variables in relation to different levels of pedestrian comfort, it was identified optimal values that can be employed as a starting point in predimensioning of the type of structure analyzed. Based on the findings analysis, it is possible to highlight the relationship between the structure's cost and CO2 emission objectives, indicating that cost-effective solutions are also environmentally efficient. Pedestrian comfort improvement is especially feasible in smaller spans and from a medium to a maximum level of comfort, but it becomes expensive for larger spans or for increasing comfort from minimum to medium level.

Management and control of coccidiosis in poultry - A review

  • Rafiq Ahmad;Yu-Hsiang Yu;Kuo-Feng Hua;Wei-Jung Chen;Daniel Zaborski;Andrzej Dybus;Felix Shih-Hsiang Hsiao;Yeong-Hsiang Cheng
    • Animal Bioscience
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    • v.37 no.1
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    • pp.1-15
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    • 2024
  • Poultry coccidiosis is an intestinal infection caused by an intracellular parasitic protozoan of the genus Eimeria. Coccidia-induced gastrointestinal inflammation results in large economic losses, hence finding methods to decrease its prevalence is critical for industry participants and academic researchers. It has been demonstrated that coccidiosis can be effectively controlled and managed by employing anticoccidial chemical compounds. However, as a result of their extensive use, anticoccidial drug resistance in Eimeria species has raised concerns. Phytochemical/herbal medicines (Artemisia annua, Bidens pilosa, and garlic) seem to be a promising strategy for preventing coccidiosis, in accordance with the "anticoccidial chemical-free" standards. The impact of herbal supplements on poultry coccidiosis is based on the reduction of oocyst output by preventing the proliferation and growth of Eimeria species in chicken gastrointestinal tissues and lowering intestinal permeability via increased epithelial turnover. This review provides a thorough up-to-date assessment of the state of the art and technologies in the prevention and treatment of coccidiosis in chickens, including the most used phytochemical medications, their mode of action, and the applicable legal framework in the European Union.

Seismic linear analytical research on the mechanical effects of RC frame structure under the different column orientations

  • Mo Shi;Min-woo Choi;Yeol Choi;Sanggoo Kang
    • Architectural research
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    • v.26 no.3
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    • pp.83-92
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    • 2024
  • The profound impact of earthquakes on human lives and the built environment emphasizes the substantial human and economic losses result-ing from structural collapses. Many researchers in this field highlight the longstanding societal challenge posed by earthquakes and under-score the imperative to minimize such losses. Over the decades, researchers have dedicated efforts to seismic design, focusing on improv-ing structural performance to mitigate earthquake-induced damages. This has led to the development of various structural analysis methods. In this research, a specific RC frame structure (401 Bldg.) at Kyungpook National University that is designed for educational purposes, serves as a representative case. This research employs SAP 2000 for simulation, aiming to assess the structural performance under seismic condi-tions, focusing on evaluating the structural behavior under different column orientations. This research utilizes RSA (Response Spectrum Analysis) to comprehensively examine parameters of displacement, base shear force, base moment, joint radians, and story drift. Referring to the results from RSA, this research also assesses the structural performance using LTHA (Linear Time History Analysis) by conducting synthetic frequency domain and synthetic time domain analyses based on the seismic wave from the Kobe 1995 earthquake (Abeno). Based on the findings from the discussions, this research is expected to be a valuable reference for structural design within seismic resistance and the seismic reinforcement of existing RC frame structures.

Oral squamous carcinoma cells stimulated by Porphyromonas gingivalis-derived lipopolysaccharide induce osteoclastogenesis through a paracrine mechanism

  • Bo Ram Keum;Soon Chul Heo;Hyung Joon Kim
    • International Journal of Oral Biology
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    • v.49 no.3
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    • pp.79-86
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    • 2024
  • Periodontal disease (PD) is strongly linked to increased risk of oral squamous cell carcinoma (OSCC); however, the specific mechanism through which the development of PD and OSCC is simultaneously promoted remains unclear. This study explored the impact of periodontal pathogens on OSCC progression and the contribution of periodontal pathogen-stimulated OSCC to PD development. The expression of osteoclastogenesis-inducing factors was assessed using quantitative reverse transcription polymerase chain reaction analysis following stimulation of OSCC with lipopolysaccharide (LPS) derived from the periodontal pathogen Porphyromonas gingivalis (Pg), a pathogen commonly responsible for PD. The cell counting kit-8 assay was used to determine the effects of Pg-LPS on OSCC proliferation and drug resistance to cisplatin and 5-fluorouracil. The effects of conditioned medium (CM) derived from Pg-LPS-stimulated OSCC on osteoclastogenesis was evaluated using tartrate-resistant acid phosphatase (TRAP) staining on bone marrow-derived macrophages (BMMs). Pg-LPS administration in SCC-25 and YD-8 OSCC cell lines induced a significant increase in receptor activator of nuclear factor kappa-B ligand mRNA expression; however, it did not affect cell proliferation. Treatment with CM derived from Pg-LPS-stimulated SCC-25 or YD-8 cells markedly enhanced the formation of TRAP-positive multinucleated cells during osteoclast differentiation of BMMs. Altogether, these findings demonstrate that Pg-LPS-stimulated OSCC promoted osteoclastogenesis through a paracrine mechanism.

NiMo LDHs Nanosheets-Coupled V2C MXene-Based Heterocatalyst for Enhanced Overall Water Splitting

  • Deepanshu Malhotra;Duy Thanh Tran;Nam Hoon Kim;Joong Hee Lee
    • Composites Research
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    • v.37 no.4
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    • pp.286-290
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    • 2024
  • The rapid increase in the demand for energy has put huge pressure on fossil fuels. The continuous overutilization of these existing non-renewable energy sources has been causing severe environmental concerns. In these regards, electrochemical water splitting has gained huge attention for producing green hydrogen, a superior energy source with high gravimetric energy density (120 MJ/kg), as compared with conventional options. Electrochemical water splitting is a viable option for generating green hydrogen. However, the various limitations of state-of the art Pt/C and RuO2- based electrocatalysts has motivated the scientific community to develop novel cathode (hydrogen evolution reaction (HER)) and anode (oxygen evolution reaction (OER)) electrocatalysts. In our present study, we have achieved a new milestone by fabricating the NiMo-based transition metal LDHs coupled V2C MXene support based heterocatalyst. The synergistic impact of NiMo LDHs (corrosion resistance, favorable intrinsic catalytic properties, etc.) and V2C (high electrical conductivity, pseudocapacitive behavior, etc.) has resulted in the HER and OER at smaller overpotential of 135 and 370 mV at the current density of 10 and 30 mA cm-2 in an alkaline (1.0 M KOH) environment.

Effects of autumn olive berry extract on insulin resistance and non-alcoholic fatty liver in high fructose-fed rat (고과당식이를 급여한 흰쥐에 있어서 토종보리수 추출물의 인슐린 저항성 및 비알콜성 지방간 개선 효과)

  • Ha-Neul Choi;Jihye Choi;Jung-In Kim
    • Journal of Nutrition and Health
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    • v.56 no.6
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    • pp.629-640
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    • 2023
  • Purpose: Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of fat in the liver which is not a result of excessive alcohol consumption. Its global prevalence was estimated to be approximately 32% in the years 1994-2019. More than half of obese individuals and patients with diabetes are reported to have NAFLD as a comorbidity. This study aimed to investigate the impact of the autumn olive (Elaeagnus umbellata Thunb.) berry on insulin resistance and steatosis in rats fed a high-fructose diet. Methods: Six-week-old Wistar rats were divided into four groups. The control group received a diet consisting of 65% corn starch, while the fructose and experimental groups were fed a diet comprising 65% fructose (FRU) and an FRU diet containing 0.5% (low-dose autumn olive berry group; LAO) or 1.0% (high-dose autumn olive berry group; HAO) ethanol extract of autumn olive berry, respectively, for 10 weeks. Results: The HAO group exhibited significantly lower blood glucose levels compared to the fructose-fed group. Both the LAO and HAO groups showed a substantial reduction in serum insulin levels and insulin resistance when compared to the fructose-fed group. The consumption of LAO and HAO significantly ameliorated dyslipidemia and reduced the levels of triglycerides in the liver compared to the fructose-fed group. Additionally, the consumption of HAO resulted in lower serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities compared to the fructose group. The hepatic expression of the sterol regulatory element-binding protein-1c (SREBP-1c) and carbohydrate-responsive element-binding protein (ChREBP) was significantly reduced in the LAO and HAO groups compared to the fructose group. Conclusion: Autumn olive berries improved steatosis by ameliorating insulin resistance and down-regulating the lipogenesis proteins in rats fed on high fructose diet.