옹벽 내 지오폼 적용 시 토압 저감원리에 관한 연구

학위논문 (석사) -- 서울대학교 대학원 : 농업생명과학대학 생태조경·지역시스템공학부(생태조경학), 2020. 8. 강준석.Retaining wall has long been widely used in landscaping, civil engineering and architecture. Since retaining wall is built close to living space such as residential areas and roads, it can cause great damage and loss of life in the event of collapse. Accordingly, there has been a steady discussion on how to enhance the safety of the retaining wall. In particular, one alternative is to improve the safety of retaining walls by reducing the earth pressure of retaining walls by utilizing light weight artificial reinforced soil. The purpose of this study was to investigate the effectiveness of geofoam application for the reduction of earth pressure in retaining walls through finite element (FE) analysis. Furthermore, it was intended to reveal the principle of reducing the earth pressure in the retaining wall by geofoam. In this study, it is tried to reduce the earth pressure on the retaining wall efficiently and economically by examining the various geometric parameters of the geofoam and discovering the optimal shape of the geofoam. Through this, it was confirmed that the triangular geofoam shape was most optimized for the retaining wall. In addition, the earth pressure in the retaining wall was investigated according to the change in the properties and area of the geofoam and the slope of the backfill. In addition, the results of FE analysis were verified by comparing results with experimental work performed on retaining walls similar to finite element models. In addition, by examining the changes in earth pressure throughout the retaining wall, the principle of reducing earth pressure in the retaining wall due to geofoam was investigated. Through this study, it was confirmed that when the bottom part of the retaining wall was reinforced by using geofoam, it showed a somewhat constant earth pressure reduction regardless of the geofoam shape.옹벽은 조경 및 토목, 건축 분야에서 널리 사용되어 왔다. 옹벽은 주택가, 도로 등 생활공간에 밀접한 곳에 건설되기 때문에 붕괴 시 큰 피해와 인명 손실이 발생할 수 있다. 이에 따라, 옹벽의 안전성을 높이는 방법에 대해서는 꾸준한 논의가 이어져 왔다. 특히 옹벽의 토압을 줄임으로 옹벽의 안전을 향상시키는 방법이 하나의 대안으로 연구되고 있다. 본 연구의 목적은 유한 요소(FE) 해석을 통해 옹벽의 토압 감소에 대한 지오폼 적용의 효율성을 조사하는 것이었다. 나아가 지오폼 활용 시의 옹벽 내 토압 저감 원리를 밝히고자 하였다. 본 연구에서는 지오폼의 다양한 기하학적 매개변수를 검토하여 지오폼의 최적 형상을 발견함으로써 옹벽에 대한 토압을 효율적이며 경제적으로 감소시키고자 하였다. 이를 통해 삼각형의 지오폼 형태가 옹벽에 가장 최적화되어 있음을 확인하였다. 또한, 지오폼의 물성 및 면적 변화, 뒷채움의 흙의 경사에 따른 옹벽 내 토압를 조사하였다. 아울러 유한요소 해석 결과는 유사한 옹벽에서 수행된 실험과의 결과비교를 통해 검증되었다. 또한 옹벽 전체의 토압 변화를 살펴봄으로 지오폼으로 인한 옹벽 내 토압 저감 원리를 규명하였다. 본 연구를 통해 지오폼을 이용해 옹벽하단부를 보강하는 경우, 지오폼의 형태에 관계없이 다소 일정한 토압감소를 보임을 확인할 수 있었다.Chapter 1. Introduction 1 1.1 Background and Purpose 1 1.2 Geofoam 2 1.3 Prior Study 4 Chapter 2. Methodology 8 2.1 Mohr-Coulomb Model 8 2.2 Finite Element Analysis 9 2.3 Modeling 10 2.4 Verification of Model 11 2.5 Geometry Optimization of Geofoam 12 2.6 Reinforcement of the Lower Part of Retaining Wall 14 2.7 Change the Slope of Backfill 15 Chapter 3. Results and Discussion 17 3.1 Earth Pressure According to Location of Geofoam 17 3.2 Earth Pressure According to Shape of Geofoam 21 3.3 Earth Pressure According to Property of Geofoam 25 3.4 Earth Pressure According to Area of Geofoam 30 3.5 Earth Pressure According to Type 35 3.6 Earth Pressure According to Slope of Backfill 47 3.7 Variation of the Earth Pressure Ratio of Retaining Wall 57 Chapter 4. Conclusions 61 Chapter 5. Bibliography 65 Abstract in Korean 70Maste

Functional dynamics of bacterial species in the mouse gut microbiome revealed by metagenomic and metatranscriptomic analyses

BACKGROUND: Microbial communities of the mouse gut have been extensively studied; however, their functional roles and regulation are yet to be elucidated. Metagenomic and metatranscriptomic analyses may allow us a comprehensive profiling of bacterial composition and functions of the complex gut microbiota. The present study aimed to investigate the active functions of the microbial communities in the murine cecum by analyzing both metagenomic and metatranscriptomic data on specific bacterial species within the microbial communities, in addition to the whole microbiome. RESULTS: Bacterial composition of the healthy mouse gut microbiome was profiled using the following three different approaches: 16S rRNA-based profiling based on amplicon and shotgun sequencing data, and genome-based profiling based on shotgun sequencing data. Consistently, Bacteroidetes, Firmicutes, and Deferribacteres emerged as the major phyla. Based on NCBI taxonomy, Muribaculaceae, Lachnospiraceae, and Deferribacteraceae were the predominant families identified in each phylum. The genes for carbohydrate metabolism were upregulated in Muribaculaceae, while genes for cofactors and vitamin metabolism and amino acid metabolism were upregulated in Deferribacteraceae. The genes for translation were commonly enhanced in all three families. Notably, combined analysis of metagenomic and metatranscriptomic sequencing data revealed that the functions of translation and metabolism were largely upregulated in all three families in the mouse gut environment. The ratio of the genes in the metagenome and their expression in the metatranscriptome indicated higher expression of carbohydrate metabolism in Muribaculum, Duncaniella, and Mucispirillum. CONCLUSIONS: We demonstrated a fundamental methodology for linking genomic and transcriptomic datasets to examine functional activities of specific bacterial species in a complicated microbial environment. We investigated the normal flora of the mouse gut using three different approaches and identified Muribaculaceae, Lachnospiraceae, and Deferribacteraceae as the predominant families. The functional distribution of these families was reflected in the entire microbiome. By comparing the metagenomic and metatranscriptomic data, we found that the expression rates differed for different functional categories in the mouse gut environment. Application of these methods to track microbial transcription in individuals over time, or before and after administration of a specific stimulus will significantly facilitate future development of diagnostics and treatments.ope

Targeted disruption of PDE3B, but not PDE3A, protects murine heart from ischemia/reperfusion injury

Although inhibition of cyclic nucleotide phosphodiesterase type 3 (PDE3) has been reported to protect rodent heart against ischemia/reperfusion (I/R) injury, neither the specific PDE3 isoform involved nor the underlying mechanisms have been identified. Targeted disruption of PDE3 subfamily B (PDE3B), but not of PDE3 subfamily A (PDE3A), protected mouse heart from I/R injury in vivo and in vitro, with reduced infarct size and improved cardiac function. The cardioprotective effect in PDE3B(-/-) heart was reversed by blocking cAMP-dependent PKA and by paxilline, an inhibitor of mitochondrial calcium-activated K channels, the opening of which is potentiated by cAMP/PKA signaling. Compared with WT mitochondria, PDE3B(-/-) mitochondria were enriched in antiapoptotic Bcl-2, produced less reactive oxygen species, and more frequently contacted transverse tubules where PDE3B was localized with caveolin-3. Moreover, a PDE3B(-/-) mitochondrial fraction containing connexin-43 and caveolin-3 was more resistant to Ca(2+)-induced opening of the mitochondrial permeability transition pore. Proteomics analyses indicated that PDE3B(-/-) heart mitochondria fractions were enriched in buoyant ischemia-induced caveolin-3-enriched fractions (ICEFs) containing cardioprotective proteins. Accumulation of proteins into ICEFs was PKA dependent and was achieved by ischemic preconditioning or treatment of WT heart with the PDE3 inhibitor cilostamide. Taken together, these findings indicate that PDE3B deletion confers cardioprotective effects because of cAMP/PKA-induced preconditioning, which is associated with the accumulation of proteins with cardioprotective function in ICEFs. To our knowledge, our study is the first to define a role for PDE3B in cardioprotection against I/R injury and suggests PDE3B as a target for cardiovascular therapies.ope

White to beige conversion in PDE3B KO adipose tissue through activation of AMPK signaling and mitochondrial function

Understanding mechanisms by which a population of beige adipocytes is increased in white adipose tissue (WAT) reflects a potential strategy in the fight against obesity and diabetes. Cyclic adenosine monophosphate (cAMP) is very important in the development of the beige phenotype and activation of its thermogenic program. To study effects of cyclic nucleotides on energy homeostatic mechanisms, mice were generated by targeted inactivation of cyclic nucleotide phosphodiesterase 3b (Pde3b) gene, which encodes PDE3B, an enzyme that catalyzes hydrolysis of cAMP and cGMP and is highly expressed in tissues that regulate energy homeostasis, including adipose tissue, liver, and pancreas. In epididymal white adipose tissue (eWAT) of PDE3B KO mice on a SvJ129 background, cAMP/protein kinase A (PKA) and AMP-activated protein kinase (AMPK) signaling pathways are activated, resulting in "browning" phenotype, with a smaller increases in body weight under high-fat diet, smaller fat deposits, increased β-oxidation of fatty acids (FAO) and oxygen consumption. Results reported here suggest that PDE3B and/or its downstream signaling partners might be important regulators of energy metabolism in adipose tissue, and potential therapeutic targets for treating obesity, diabetes and their associated metabolic disorders.ope

Proteomic analysis-based discovery of a novel biomarker that differentiates intestinal Behçet's disease from Crohn's disease

Intestinal Behçet's disease (BD) and Crohn's disease (CD) present similar manifestations, but there are no specific diagnostic tests to differentiate them. We used a proteomic approach to discover novel diagnostic biomarkers specific to intestinal BD. Colon mucosa tissue samples were obtained from patients with intestinal BD or CD using colonoscopy-guided biopsy of the affected bowel. Peptides from seven intestinal BD and seven CD patients were extracted and labeled using tandem mass tag (TMT) reagents. The labeled peptides were identified and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The proteins were further validated using immunohistochemical (IHC) analysis with tissue samples and an ELISA test with serum samples from 20 intestinal BD and 20 CD patients. Using TMT/LC-MS/MS-based proteomic quantification, we identified 39 proteins differentially expressed between intestinal BD and CD. Beta-2 glycoprotein 1 (APOH) and maltase-glucoamylase (MGAM) showed higher intensity in the IHC staining of intestinal BD tissues than in CD tissues. The serum MGAM level was higher in intestinal BD patients. Proteomic analysis revealed that some proteins were differentially expressed in patients with intestinal BD compared with those with CD. Differential MGAM expression in intestinal BD suggests its role as a potential novel diagnostic biomarker.ope

An experimental approach to study the function of mitochondria in cardiomyopathy

Cardiomyopathy is an inherited or acquired disease of the myocardium, which can result in severe ventricular dysfunction. Mitochondrial dysfunction is involved in the pathological process of cardiomyopathy. Many dysfunctions in cardiac mitochondria are consequences of mutations in nuclear or mitochondrial DNA followed by alterations in transcriptional regulation, mitochondrial protein function, and mitochondrial dynamics and energetics, presenting with associated multisystem mitochondrial disorders. To ensure correct diagnosis and optimal management of mitochondrial dysfunction in cardiomyopathy caused by multiple pathogenesis, multidisciplinary approaches are required, and to integrate between clinical and basic sciences, ideal translational models are needed. In this review, we will focus on experimental models to provide insights into basic mitochondrial physiology and detailed underlying mechanisms of cardiomyopathy and current mitochondria-targeted therapies for cardiomyopathy.ope

Naphthalene-based fluorescent probes for glutathione and their applications in living cells and patients with sepsis

Rationale: Among the biothiols-related diseases, sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection and can result in severe oxidative stress and damage to multiple organs. In this study, we aimed to develop a fluorescence chemosensor that can both detect GSH and further predict sepsis. Methods: In this study, two new naphthalene dialdehyde compounds containing different functional groups were synthesized, and the sensing abilities of these compounds towards biothiols and its applications for prediction of sepsis were investigated. Results: Our study revealed that the newly developed probe 6-methoxynaphthalene-2, 3-dicarbaldehyde (MNDA) has two-photon is capable of detecting GSH in live cells with two-photon microscopy (TPM) under the excitation at a wavelength of 900 nm. Furthermore, two GSH detection probes naphthalene-2,3-dicarboxaldehyde (NDA) and 6-fluoronaphthalene-2,3-dicarbaldehyde (FNDA) not only can detect GSH in living cells, but also showed clinical significance for the diagnosis and prediction of mortality in patients with sepsis. Conclusions: These results open up a promising direction for further medical diagnostic techniques.ope

CTCF Regulates Otic Neurogenesis via Histone Modification in the Neurog1 Locus

The inner ear is a complex sensory organ responsible for hearing and balance. Formation of the inner ear is dependent on tight regulation of spatial and temporal expression of genes that direct a series of developmental processes. Recently, epigenetic regulation has emerged as a crucial regulator of the development of various organs. However, what roles higher-order chromatin organization and its regulator molecules play in inner ear development are unclear. CCCTC-binding factor (CTCF) is a highly conserved 11-zinc finger protein that regulates the three-dimensional architecture of chromatin, and is involved in various gene regulation processes. To delineate the role of CTCF in inner ear development, the present study investigated inner ear-specific Ctcf knockout mouse embryos (Pax2-Cre; Ctcffl/fl ). The loss of Ctcf resulted in multiple defects of inner ear development and severely compromised otic neurogenesis, which was partly due to a loss of Neurog1 expression. Furthermore, reduced Neurog1 gene expression by CTCF knockdown was found to be associated with changes in histone modification at the gene's promoter, as well as its upstream enhancer. The results of the present study demonstrate that CTCF plays an essential role in otic neurogenesis by modulating histone modification in the Neurog1 locus.ope

Quantitative Proteomic Analysis of the Expression of SARS-CoV-2 Receptors in the Gut of Patients with Chronic Enterocolitis

The cellular entry of severe respiratory syndrome coronavirus-2 (SARS-CoV-2) is mediated by interaction with the human angiotensin-converting enzyme 2 (ACE2), a receptor that is expressed on both lung and intestinal epithelial cells. We performed a quantitative proteomic analysis to investigate the expression of possible receptors for SARS-CoV-2 in the intestinal mucosa of 23 patients with chronic colitis. ACE2 expression was low and remained unaltered in the gut of patients with ulcerative colitis (UC), Crohn's disease (CD), intestinal Behćet's disease (BD), and intestinal tuberculosis (TB), when compared with that of healthy individuals. Additionally, the expression levels of some probable co-receptors, including dipeptidyl peptidase 4 (DPP4), aminopeptidase N (AMPN), and glutamyl aminopeptidase (AMPE), were unchanged in the affected UC, CD, intestinal BD, and intestinal TB colon mucosa samples. In conclusion, gut inflammation associated with chronic colitis does not mediate a further increase in the cellular entry of SARS-CoV-2.ope

Modulation of dendritic cell function by Trichomonas vaginalis-derived secretory products

Trichomoniasis caused by the parasitic protozoan Trichomonas vaginalis is the most common sexually transmitted disease in the world. Dendritic cells are antigen presenting cells that initiate immune responses by directing the activation and differentiation of naïve T cells. In this study, we analyzed the effect of Trichomonas vaginalis-derived Secretory Products on the differentiation and function of dendritic cells. Differentiation of bone marrow-derived dendritic cells in the presence of T. vaginalis-derived Secretory Products resulted in inhibition of lipopolysaccharide-induced maturation of dendritic cells, down-regulation of IL-12, and up-regulation of IL-10. The protein components of T. vaginalis-derived Secretory Products were shown to be responsible for altered function of bone marrow- derived dendritic cells. Chromatin immunoprecipitation assay demonstrated that IL-12 expression was regulated at the chromatin level in T. vaginalis-derived Secretory Productstreated dendritic cells. Our results demonstrated that T. vaginalis- derived Secretory Products modulate the maturation and cytokine production of dendritic cells leading to immune tolerance.ope