• Computers and Concrete
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• 제27권4호
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• pp.333-341
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• 2021

Steel slag, an industrial reject from the steel rolling process, has been identified as one of the suitable, environmentally friendly materials for concrete production. Given that the coarse aggregate portion represents about 70% of concrete constituents, other economic approaches have been found in the use of alternative materials such as steel slag in concrete. Unfortunately, a standard framework for its application is still lacking. Therefore, this study proposed functional model equations for the determination of strength properties (compression and splitting tensile) of steel slag aggregate concrete (SSAC), using gene expression programming (GEP). The study, in the experimental phase, utilized steel slag as a partial replacement of crushed rock, in steps 20%, 40%, 60%, 80%, and 100%, respectively. The predictor variables included in the analysis were cement, sand, granite, steel slag, water/cement ratio, and curing regime (age). For the model development, 60-75% of the dataset was used as the training set, while the remaining data was used for testing the model. Empirical results illustrate that steel aggregate could be used up to 100% replacement of conventional aggregate, while also yielding comparable results as the latter. The GEP-based functional relations were tested statistically. The minimum absolute percentage error (MAPE), and root mean square error (RMSE) for compressive strength are 6.9 and 1.4, and 12.52 and 0.91 for the train and test datasets, respectively. With the consistency of both the training and testing datasets, the model has shown a strong capacity to predict the strength properties of SSAC. The results showed that the proposed model equations are reliably suitable for estimating SSAC strength properties. The GEP-based formula is relatively simple and useful for pre-design applications.

• Steel and Composite Structures
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• 제44권3호
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• pp.309-324
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• 2022

The post-fire elastic stiffness and performance of concrete-filled steel tube (CFST) columns containing recycled aggregate concrete (RAC) has rarely been addressed, particularly in terms of material properties. This study was conducted with the aim of assessing the modulus of elasticity of recycled aggregate concrete-filled steel tube (RACFST) stub columns following thermal loading. The test data were employed to model and assess the elastic modulus of circular RACFST stub columns subjected to axial loading after exposure to elevated temperatures. The length/diameter ratio of the specimens was less than three to prevent the sensitivity of overall buckling for the stub columns. The gene expression programming (GEP) method was employed for the model development. The GEP model was derived based on a comprehensive experimental database of heated and non-heated RACFST stub columns that have been properly gathered from the open literature. In this study, by using specifications of 149 specimens, the variables were the steel section ratio, applied temperature, yielding strength of steel, compressive strength of plain concrete, and elastic modulus of steel tube and concrete core (RAC). Moreover, parametric and sensitivity analyses were also performed to determine the contribution of different effective parameters to the post-fire elastic modulus. Additionally, comparisons and verification of the effectiveness of the proposed model were made between the values obtained from the GEP model and the formulas proposed by different researchers. Through the analyses and comparisons of the developed model against formulas available in the literature, the acceptable accuracy of the model for predicting the post-fire modulus of elasticity of circular RACFST stub columns was seen.

• Computers and Concrete
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• 제31권2호
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• pp.111-121
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• 2023

The influence of material composition such as aggregate types, addition of supplementary cementitious materials as well as exposed temperature levels have significant impacts on concrete residual mechanical strength properties when exposed to elevated temperature. This study is based on data obtained from literature for fly ash blended concrete produced with natural and recycled concrete aggregates to efficiently develop prediction models for estimating its residual compressive strength after exposure to high temperatures. To achieve this, an extensive database that contains different mix proportions of fly ash blended concrete was gathered from published articles. The specific design variables considered were percentage replacement level of Recycled Concrete Aggregate (RCA) in the mix, fly ash content (FA), Water to Binder Ratio (W/B), and exposed Temperature level. Thereafter, a simplified mathematical equation for the prediction of concrete's residual compressive strength using Gene Expression Programming (GEP) was developed. The relative importance of each variable on the model outputs was also determined through global sensitivity analysis. The GEP model performance was validated using different statistical fitness formulas including R², MSE, RMSE, RAE, and MAE in which high R² values above 0.9 are obtained in both the training and validation phase. The low measured errors (e.g., mean square error and mean absolute error are in the range of 0.0160 - 0.0327 and 0.0912 - 0.1281 MPa, respectively) in the developed model also indicate high efficiency and accuracy of the model in predicting the residual compressive strength of fly ash blended concrete exposed to elevated temperatures.

• Childhood Kidney Diseases
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• 제8권2호
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• pp.138-148
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• 2004

목적: 단백뇨 질환에서 볼 수 있는 사구체 상피세포(glomerular epithelial cells, GEpC) 족돌기(foot process)의 병리학적 변화에 있어서 GEpC사이의 세극막(slit diaphragm)과 세포골격을 연결하는 ZO-1 단백의 당뇨조건에 따른 변화를 알아보고자 하였다. 방법: 백서 GEpC을 배양하고 고농도의 당과 후기당화합물(advanced glycosylation enduroducts, AGE)를 적용하여 당뇨병 환경에 가까운 조건을 설정한 후, ZO-1 단백양은 Western 분석으로, 분포 변화는 공초점 현미경으로, 유전자 표현의 변화는 RT-PCR로 관찰하였다. 실험군은 당의 농도를 5 또는 30 mM로, AGE와 BSA를 첨가하고 osmotic control로서 당 5 mM에 mannitol 25 M을 섞은 것을 조합하여 A5, A30, B5, B30, Aosm로 하였다. 결과: 공초점 현미경 상 ZO-1은 정상적인 환경인 B5에서 B30, A5, 가장 병적인 A30 환경으로 진행할수록 세포질의 바깥에서 안쪽으로 이동하는 양상을 보였다. ZO-1 단백양은 B5 결과를 대조군으로 비교하여 당을 첨가한 B30에서 11.1%, AGE를 추가한 조건인 A5에서 2.3% 감소하였나 통계적 유의성은 없었고, 당과 AGE가 동시에 첨가된 A30에서는 19.0%의 유의한 감소를 보였다. mRNA의 발현도 A30에서만 12.0%의 의의 있는 감소를 보였다. 이러한 단백질과 mRNA의 감소 소견은 osmotic control (Aosm)에서는 관찰할 수 없었다. 결론: 고농도의 당과 AGE에 의한 GEpC의 ZO-1의 분포 변화와 유전자 수준에서의 억제로 단백의 생성 감소를 초래함으로써, 장기간 당뇨 환경체서 족돌기의 형태학적 변화를 설명할 수 있으며, 추후 이의 변화 기전에 대한 연구가 필요할 것으로 사료된다.

• Radiation Oncology Journal
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• 제24권1호
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• pp.58-66
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• 2006

목적: 방사선에 의한 신장손상은 궁극적으로 신장 섬유화로 인한 신부전으로 나타나며 여기에는 세포외기질의 변화가 동반된다. 방사선 신장손상에서 신사구체 상피세포의 역할을 알아보기 위하여 방사선에 의한 세포외기질과 연관된 여러 유전자 발현의 변화를 알아보고자 하였다. 대상 및 방법 : 백서 사구체 상피세포 (rat glomerular epithelial cell: GEpC) 에 6 MV 선형가속기 (Siemens, USA)를 이용하여 0, 2, 5, 10, 20 Gy 의 단일 방사선량을 조사한 후 각각 6, 24, 48, 72 시간에 시료를 채취하였다. Northern blot, Western blot, Zymography를 이용하여 fibronectin (Fn), plasminogen activator inhibitor-1 (Pai-1), matrix metalloproteinases-2, 9 (MMP-2, 9), tissue inhibitor of matrix metallproteinase-2 (TIMP-2), tissue-type plasminogen activator (t-PA), Urokinase-type plasminogen activator (u-PA)의 발현을 측정하였다. 결과: GEpC 에 대한 10 Gy 단일 방사선 조사후 24 시간부터 Fn mRNA 가 유의한 증가를 나타냈으며 48 시간에 측정한 Fn 단백질은 5, 10 Gy 의 방사선량에서 유의하게 증가되었다. 방사선조사에 의해서 Pai-1 유전자의 발현도 mRNA 및 단백질 단계에서 증가되었으며, 특히 10Gy 조사 후 24, 48 시간에 측정한 mRNA 의 증가는 통계적으로 유의하였다. GEpC에 방사선조사 후 24 시간에 측정한 MMP-2 활성형은 방사선량에 따라 증가하였으나 통계학적 유의성은 없었다. 그밖의 MMP-9, TIMP-2, t-PA 와 u-PA 는 아무런 변화를 나타내지 않았다. 결론 : 방사선에 의하여 GEpC에서 세포외 기질과 관련된 유전자 발현의 번화가 관찰되었으며 이는 방사선 신장 손상에 GEpC가 관여함을 나타낸다.

• ALGAE
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• 제30권2호
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• pp.121-137
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• 2015

Studies on carbon flux in the oceans have been highlighted in recent years due to increasing awareness about climate change, but the coastal ecosystem remains one of the unexplored fields in this regard. In this study, the dynamics of carbon flux in a vegetative coastal ecosystem were examined by an evaluation of net and gross ecosystem production (NEP and GEP) and $CO_2$ exchange rates (net ecosystem exchange, NEE). To estimate NEP and GEP, community production and respiration were measured along different habitat types (eelgrass and macroalgal beds, shallow and deep sedimentary, and deep rocky shore) at Gwangyang Bay, Korea from 20 June to 20 July 2007. Vegetative areas showed significantly higher ecosystem production than the other habitat types. Specifically, eelgrass beds had the highest daily GEP ($6.97{\pm}0.02g\;C\;m^{-2}\;d^{-1}$), with a large amount of biomass and high productivity of eelgrass, whereas the outer macroalgal vegetation had the lowest GEP ($0.97{\pm}0.04g\;C\;m^{-2}\;d^{-1}$). In addition, macroalgal vegetation showed the highest daily NEP ($3.31{\pm}0.45g\;C\;m^{-2}\;d^{-1}$) due to its highest P : R ratio (2.33). Furthermore, the eelgrass beds acted as a $CO_2$ sink through the air-seawater interface according to NEE data, with a carbon sink rate of $0.63mg\;C\;m^{-2}\;d^{-1}$. Overall, ecosystem production was found to be extremely high in the vegetated systems (eelgrass and macroalgal beds), which occupy a relatively small area compared to the unvegetated systems according to our conceptual diagram of a carbon-flux box model. These results indicate that the vegetative ecosystems showed significantly high capturing efficiency of inorganic carbon through coastal primary production.

• Childhood Kidney Diseases
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• 제17권2호
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• pp.79-85
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• 2013

목적: 단백뇨 질환의 실험모델인 puromycin aminonucleoside (PAN)에서 관찰할 수 있는 족세포의 병리학적 이상에 있어서 P-cadherin의 변화를 생체 외 족세포 배양실험을 통하여 알아보고자 하였다. 방법: PAN에 의한 족세포의 P-cadherin의 변화를 생체 외 배양실험을 통해 알아보고자 백서 사구체 상피세포(GEpC)를 배양하여 다양한 농도의 PAN을 투여하여 confocal 현미경을 통하여 P-cadherin의 분포를 관찰하였고, Western blotting 과 RT-PCR을 사용하여 P-cadherin 발현의 변화를 관찰하였다. 결과: 외곽세포질에 분포하는 P-cadherin은 단일세포 혹은 응집환경에서 PAN의 농도가 올라갈수록 내부로 응집되는 현상를 볼 수 있었다. Western 분석에서, P-cadherin 단백양은 PAN에 농도-의존적으로, 특히, 고농도인 50 mg/mL에서 24시간과 48시간이 노출 조건에서 각각 21.9% (P< 0.05)와 31.9% (P<0.01)의 의미 있는 감소소견을 보였다. RT-PCR에서도 48시간에서 50 mg/mL PAN을 첨가한 조건에서 23.5%의 의미 있는 감소를 보였다(P<0.05). 결론: PAN은 족세포에서 P-cadherin을 세포막으로부터 내부로의 응집을 유발하고, P-cadherin mRNA의 발현 감소와 단백수준에서 양의 감소를 초래함으로서, 단백뇨의 발생에 기여할 것이라 사료된다.

• Earthquakes and Structures
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• 제15권4호
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• pp.403-410
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• 2018

The choice of attenuation relationships is one of the most important parts of seismic hazard analysis as using a different attenuation relationship will cause significant differences in the final result, particularly in near distances. This problem is responsible for huge sensibilities of attenuation relationships which are used in seismic hazard analysis. For achieving this goal, attenuation relationships require a good compatibility with the target region. Many researchers have put substantial efforts in their studies of strong ground motion predictions, and each of them had an influence on the progress of attenuation relationships. In this study, two attenuation relationships are presented using seismic data of Mazandaran province in the north of Iran by Genetic Expression Programming (GEP) algorithm. Two site classifications of soil and rock were considered regarding the shear wave velocity of top 30 meters of site. The quantity of primary data was 93 records; 63 of them were recorded on rock and 30 of them recorded on soil. Due to the shortage of records, a regression technique had been used for increasing them. Through using this technique, 693 data had been created; 178 data for soil and 515 data for rock conditions. The Results of this study show the observed PGA values in the region have high correlation coefficients with the predicted values and can be used in seismic hazard analysis studies in the region.

• Clinical and Experimental Pediatrics
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• 제55권10호
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• pp.371-376
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• 2012

Purpose: Puromycin aminonucleoside (PAN) specifically injures podocytes, leading to foot process effacement, actin cytoskeleton disorganization, and abnormal distribution of slit diaphragm proteins. p130Cas is a docking protein connecting F-actin fibers to the glomerular basement membrane (GBM) and adapter proteins in glomerular epithelial cells (GEpCs; podocytes). We investigated the changes in the p130Cas expression level in the PAN-induced pathological changes of podocytes in vitro. Methods: We observed changes in the p130Cas expression in cultured rat GEpCs and mouse podocytes treated with various concentrations of PAN and antioxidants, including probucol, epigallocatechin gallate (EGCG), and vitamin C. The changes in the p130Cas expression level were analyzed using confocal immunofluorescence imaging, Western blotting, and polymerase chain reaction. Results: In the immunofluorescence study, p130Cas showed a diffuse cytoplasmic distribution with accumulation at distinct sites visible as short stripes and colocalized with P-cadherin. The fluorescences of the p130Cas protein were internalized and became granular by PAN administration in a dose-dependent manner, which had been restored by antioxidants, EGCG and vitamin C. PAN also decreased the protein and mRNA expression levels of p130Cas at high doses and in a longer exposed duration, which had been also reversed by antioxidants. Conclusion: These findings suggest that PAN modulates the quantitative and distributional changes of podocyte p130Cas through oxidative stress resulting in podocyte dysfunction.

• Geomechanics and Engineering
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• 제30권6호
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• pp.551-564
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• 2022

Fragmenting the rock mass is considered as the most important work in open-pit mines. Ground vibration is the most hazardous issue of blasting which can cause critical damage to the surrounding structures. This paper focuses on developing an explicit model to predict the ground vibration through an multi objective evolutionary polynomial regression (MOGA-EPR). To this end, a database including 79 sets of data related to a quarry site in Malaysia were used. In addition, a gene expression programming (GEP) model and several empirical equations were employed to predict ground vibration, and their performances were then compared with the MOGA-EPR model using the mean absolute error (MAE), root mean square error (RMSE), mean (𝜇), standard deviation of the mean (𝜎), coefficient of determination (R²) and a20-index. Comparing the results, it was found that the MOGA-EPR model predicted the ground vibration more precisely than the GEP model and the empirical equations, where the MOGA-EPR scored lower MAE and RMSE, 𝜇 and 𝜎 closer to the optimum value, and higher R² and a20-index. Accordingly, the proposed MOGA-EPR model can be introduced as a useful method to predict ground vibration and has the capacity to be generalized to predict other blasting effects.