In recent years, compared to the traditional Portland cement, environmentally friendly geo-polymers have gained more attention as construction materials. In this paper, volcanic ash (VA) and ground granulated blast furnace slag (GGBFS) in different percentages (0%, 3%, 7%, and 10%) are considered as a replacement for the conventionally used Portland cement to stabilize sandy soils. NaOH and Na2SiO3 in different concentrations (4M, 8M, and 12M) and alkali to binder ratios (1, 1.5, 2, and 3) are used as alkali activator solutions to build new geopolymers. Samples are cured in both ambient and oven temperatures and in 1-, 7-and 28-days curing condition.Unconfined compressive strength (UCS) of samples is then evaluated. Two predictive approaches, artificial neural network (ANN) modeling and evolutionary polynomial regression technique (EPR) are applied to model UCS of geo-polymerized sand samples. Regarding the high value of the coefficient of determination of the proposed ANN, 97%, and acceptable prediction errors, RMSE of 0.0439 and MAE of 0.0336, an 8-5-10-1 ANN is introduced as a more accurate tool for the prediction of UCS. Next, three-dimensional parametrical studies are conducted to investigate effects of simultaneous changes in alkali solution, binder and curing condition parameters on UCS values of geo-polymerized samples. Sensitivity analysis based on the Cosine amplitude method has also introduced Si/Al ratio as the most and VA content as the least affecting parameters on the compressive strength of samples. Results attained are further analyzed using pH and electrical conductivity tests and interpreted based on the microstructural investigations throughout scanning electron microscopy (SEM) images, and X-ray diffraction analysis.
Nasal Polyposis (NP) is a complex multi-factorial disease; associated with several environmental, genetic and inflammatory factors. TNF-alpha is one of the major pro-inflammatory cytokines involved in NP pathogenesis. Some of the polymorphisms of this gene affect its expression. Therefore, the aim of this study was to evaluate the polymorphism of TNF-alpha G/A308 gene and its association with nasal polyposis in north part of Iran. In this case-control study, 60 patients with NP and 75 healthy individuals referred to Guilan University hospital were evaluated. After DNA extraction, RFLP-PCR was used to determine polymorphism. Chi-square test was used to compare the frequency distribution of genotype and alleles of TNF-alpha gene with NP. The frequency of genotype G/G, A/A and G/A in the NP group was 46.7, 10.0 and 43.3%, and in the control group was 65.3, 5.3 and 29.3%, respectively. There was a statistically significant difference between genotype G/G in two groups (P = 0.006, OR 2.58, CI 1.27-5.23). In addition, the frequency of allele A in patients and controls was 31.7 and 20%, respectively; and this difference was statistically significant (p = 0.02). The findings of this study demonstrated that polymorphism in TNF-alpha gene might be a risk factor for NP in north part of Iran and the minor frequency of G308A allele in the current study is slightly more than other major populations. However, more investigations with high number of population are necessary in future.
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