An experimental study on different socket base connections under cyclic loading

Selim Pul,Metin Hüsem,Mehmet Emin Arslan,Sertaç Hamzaçebi 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.3

This paper presents an experimental study on socket base connections of precast reinforced concrete columns. The main purpose of this study is to determine socket base connection which has the closest behavior to monolithic casted column-base joints. For this purpose, six specimens having different column-socket base connection details were tested under cyclic loading. For each test, strength, stiffness, ductility and drift ratios of the specimens were determined. Test results indicated that a suggested connection type is 10% - 30% stronger than the other type of connections under lateral loading. The welded connection (PC-5) had better lateral load carrying capacity and ductility. On the other hand, performance of standard connection (PC-1) which is commonly used in construction was weaker than other connections. Thus, decision of connection type should be referred not only performance but also applicability.

Ultimate behavior of composite beams with shallow I-sections

Selçuk Emre Görkem,Metin Hüsem 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.5

Bending behavior of reinforced concrete slabs encased over shallow I-sections at different levels of compression heads were investigated in present study. 1500 mm long I-sections were used to create composite slabs. Compression heads of monolithic experimental members were encased at different levels into the concrete slabs. Shear connections were welded over some of the I-sections. The testing was carried out in accordance with the principles of four-point loading. Results revealed decreasing load bearing and deflection capacities of composite beams with increasing encasement depths into concrete. Mechanical properties of concrete and reinforcing steel were also examined. Resultant stresses calculated for composite beams at failure were found to be less than the yield strength of steel beams. Test results were discussed with regard to shear and slip effect.

Load capacity of high-strength reinforced concrete slabs by yield line theory

Selçuk Emre Gӧrkem,Metin Hϋsem 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.6

The objective of this study is to determine whether or not the yield line theory, an effective method widely used for slabs made of ordinary concrete, can be used also for the reinforced concrete slabs made of high-strength concrete. Flexural behavior of simply supported slabs in three different sizes were investigated under concentrated load at mid-span. Additionally, behavior of high strength reinforced concrete slabs with 50 mm and 150 mm reinforcement spacings also studied. Failure loads, deflections, experimental and theoretical failure mechanisms were evaluated. The difference between the moments based on yield line theory and experimental moments varied between 1% to 3%. Experimental and analysis results revealed that yield line analysis could conveniently be employed in the analysis of high strength reinforced concrete slabs.

Collapse of steel cantilever roof of tribune induced by snow loads

Ahmet C. Altunışık,Şevket Ateş,Metin Hüsem,Ali F. Genç 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.3

In this paper, it is aimed to present a detail investigation related to structural behavior of laterally unrestrained steel cantilever roof of tribune with slender cross section. The structure is located in Tutak town in A&$287;rı and collapsed on October 25, 2015 at eastern part of Turkey is considered as a case study. This mild sloped roof structure was built from a variable I beam, and supported on steel columns of 5.5 m height covering totally 240 m² closed area in plan. The roof of tribune collapsed completely without any indication during first snowfall after construction at midnight a winter day, fortunately before the opening hours. The meteorological records and observations of local persons are combined together to estimate the intensity of snow load in the region and it is compared with the code specified values. Also, the wide/thickness and height/thickness ratios for flange and web are evaluated according to the design codes. Three dimensional finite element model of the existing steel tribune roof is generated considering project drawings and site investigations using commercially available software ANSYS. The displacements, principal stresses and strains along to the cantilever length and column height are given as contour diagrams and graph format. In addition to site investigation, the numerical and analytical works conducted in this study indicate that the unequivocal reasons of the collapse are overloading action of snow load intensity, some mistakes made in the design of steel cantilever beams, insufficient strength and rigidity of the main structural elements, and construction workmanship errors.

가토의 Anti GBM Antibody 에 의한 Crescentic Nephritis 에서 요중 Transforming Growth Factor - Beta 의 변동

노정우,조원용,권영주,김형규 ( Roger C . Wiggins,Sem H . Phan ) 대한신장학회 1991 학술대회및초록집 Vol.10 No.2

Telomerase Regulation of Myofibroblast Differentiation

Liu, Tianju,Hu, Biao,Chung, Myoung Ja,Ullenbruch, Matt,Jin, Hong,Phan, Sem H. American Thoracic Society 2006 AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR Vol.34 No.5

<P>Telomerase activity, which has wide expression in cancerous cells, is induced in lung proliferating fibroblasts. It is preferentially expressed in fibroblasts versus myofibroblasts. It is unknown whether regulation of telomerase expression is related to the process of fibroblast differentiation into myofibroblasts. The objective of this study was to clarify such a potential link between telomerase expression and myofibroblast differentiation. Telomerase inhibitor, 3'-azido-2',3'-dideoxythymidine, or antisense oligonucleotide to the telomerase RNA component was used to inhibit the induced fibroblast telomerase activity. The results showed that inhibition of induced telomerase increased alpha-smooth muscle actin expression, an indicator of myofibroblast differentiation. In contrast, induction of telomerase by basic fibroblast growth factor inhibited alpha-smooth muscle actin expression. These findings suggest that the loss of telomerase activity is closely associated with myofibroblast differentiation and possibly functions as a trigger for myofibroblast differentiation. Conversely, expression of telomerase suppresses myofibroblast differentiation.</P>

Telomerase activity is required for bleomycin-induced pulmonary fibrosis in mice.

Liu, Tianju,Chung, Myoung Ja,Ullenbruch, Matthew,Yu, Hongfeng,Jin, Hong,Hu, Biao,Choi, Yoon Young,Ishikawa, Fuyuki,Phan, Sem H American Society for Clinical Investigation 2007 The Journal of clinical investigation Vol.117 No.12

<P>In addition to its well-known expression in the germline and in cells of certain cancers, telomerase activity is induced in lung fibrosis, although its role in this process is unknown. To identify the pathogenetic importance of telomerase in lung fibrosis, we examined the effects of telomerase reverse transcriptase (TERT) deficiency in a murine model of pulmonary injury. TERT-deficient mice showed significantly reduced lung fibrosis following bleomycin (BLM) insult. This was accompanied by a significant reduction in expression of lung alpha-SMA, a marker of myofibroblast differentiation. Furthermore, lung fibroblasts isolated from BLM-treated TERT-deficient mice showed significantly decreased proliferation and increased apoptosis rates compared with cells isolated from control mice. Transplantation of WT BM into TERT-deficient mice restored BLM-induced lung telomerase activity and fibrosis to WT levels. Conversely, transplantation of BM from TERT-deficient mice into WT recipients resulted in reduced telomerase activity and fibrosis. These findings suggest that induction of telomerase in injured lungs may be caused by BM-derived cells, which appear to play an important role in pulmonary fibrosis. Moreover, TERT induction is associated with increased survival of lung fibroblasts, which favors the development of fibrosis instead of injury resolution.</P>

Adverse effects following dental local anesthesia: a literature review

Ho, Jean-Pierre T.F.,van Riet, Tom C.T.,Afrian, Youssef,Chin Jen Sem, Kevin T.H.,Spijker, Rene,de Lange, Jan,Lindeboom, Jerome A. The Korean Dental Society of Anesthsiology 2021 Journal of Dental Anesthesia and Pain Medicine Vol.21 No.6

Local anesthesia is indispensable in dentistry. Worldwide, millions of local anesthetic injections are administered annually, and are generally considered safe invasive procedures. However, adverse effects are possible, of which dentists should be aware of. This scoping review aimed to provide an extensive overview of the reported literature on the adverse effects of dental local anesthesia. The types of papers, what is reported, and how they are reported were reviewed. Additionally, the incidence and duration of adverse effects and factors influencing their occurrence were also reviewed. An electronic search for relevant articles was performed in PubMed and Embase databases from inception to January 2, 2020. The titles and abstracts were independently screened by two reviewers. The analysis was narrative, and no meta-analysis was performed. This study included 78 articles. Ocular and neurological adverse effects, allergies, hematomas, needle breakage, tissue necrosis, blanching, jaw ankylosis, osteomyelitis, and isolated atrial fibrillation have been described. Multiple adverse effects of dental local anesthesia have been reported in the literature. The results were heterogeneous, and detailed descriptions of the related procedures were lacking. Vital information concerning adverse effects, such as the dosage or type of anesthetic solution, or the type of needle used, was frequently missing. Therefore, high-quality research on this topic is needed. Finally, the adverse effects that are rarely encountered in real-world general practice are overrepresented in the literature.