The Effect of the Depth of Cutter Soil Mixing on the Compressive Behaviour of a Soft Clay Treated by Alkali-Activated Slag

Parham Rabbani,Ali Tolooiyan,Seyed Hamid Lajevardi,Younes Daghigh,Mahroo Falah 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

Cutter soil mixing (CSM) is a fairly new technique for shallow to deep soil stabilisation that mostly uses cement based slurry to improve the in-situ properties of soft soils. This research aims to experimentally investigate the effect of the depth of cutter soil mixing on the compressive strength of a saturated soft clay treated with alkali-activated slag slurry. Various percentages of additives were added to the saturated soft clay to increase the compressive strength and to make it suitable for constructing shallow to deep CSM panels as earth retaining walls that are used for excavations. Several high-pressure curing apparatuses were used to simulate in-situ field stress due to the depth/weight of CSM panels. Then a set of compressive strength tests were conducted to investigate the effect of different curing pressures, additives content and curing time on the compressive behavior and strength of CSM panels. Microstructural studies were also performed to understand the reactions of the mixtures. The results showed that the compressive behavior of CSM panel changes significantly by increasing the mixing depth. Moreover the influence of curing pressure equivalent to the depth of CSM panels on increasing unconfined compressive strength of specimens is partially more than the effect of additives and considerably more than the effect of curing time. The microstructural studies also showed that the main hydration products are cementitious products such as calcium silicate hydrates (C-S-H) and the addition of alkali-activated slag in a treated clay results in production of the cementitious products in a faster rate.

Effect of crack location on buckling analysis and SIF of cracked plates under tension

Parham Memarzadeh,Sayedmohammad Mousavian,Mohammad Hosseini Ghehi,Tadeh Zirakian 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.2

Cracks and defects may occur anywhere in a plate under tension. Cracks can affect the buckling stability performance and even the failure mode of the plate. A search of the literature reveals that the reported research has mostly focused on the study of plates with central and small cracks. Considering the effectiveness of cracks on the buckling behavior of plates, this study intends to investigate the effects of some key parameters, i.e., crack size and location as well as the plate aspect ratio and support conditions, on the buckling behavior, stress intensity factor (SIF), and the failure mode (buckling or fracture) in cracked plates under tension. To this end, a sophisticated mathematical code was developed using MATLAB in the frame-work of extended finite element method (XFEM) in order to analyze the buckling stability and collapse of numerous plate models. The results and findings of this research endeavor show that, in addition to the plate aspect ratio and support conditions, careful consideration of the crack location and size can be quite effective in buckling behavior assessment and failure mode prediction as well as SIF evaluation of the cracked plates subjected to tensile loading.

RESIDUAL SUPERSINGULAR IWASAWA THEORY OVER QUADRATIC IMAGINARY FIELDS

Parham Hamidi Korean Mathematical Society 2023 대한수학회보 Vol.60 No.4

Let p be an odd prime. Let E be an elliptic curve defined over a quadratic imaginary field, where p splits completely. Suppose E has supersingular reduction at primes above p. Under appropriate hypotheses, we extend the results of [17] to ℤ²_p-extensions. We define and study the fine double-signed residual Selmer groups in these settings. We prove that for two residually isomorphic elliptic curves, the vanishing of the signed 𝜇-invariants of one elliptic curve implies the vanishing of the signed 𝜇-invariants of the other. Finally, we show that the Pontryagin dual of the Selmer group and the double-signed Selmer groups have no non-trivial pseudo-null submodules for these extensions.

Multivariate Causal Relationship between Stock Prices and Exchange Rates in the Middle East

Parham Parsva,Hooi Hooi Lean 한국유통과학회 2017 The Journal of Asian Finance, Economics and Busine Vol.4 No.1

This study investigates the causal relationship between stock prices and exchange rates for six Middle Eastern countries, namely, Egypt, Iran, Jordan, Kuwait, Oman, and Saudi Arabia before and during (after) the 2007 global financial crisis for the period between January 2004 and September 2015. The sample is divided into two sub-periods, that is, the period from January 1, 2004 to September 30, 2007 and the period from October 1, 2007 to September 30, 2015, to represent the pre-crisis period and the post-crisis period, respectively. Using Vector Autoregressive (VAR) model in a multivariate framework (including two control variables, inflation rates and oil prices) the results suggest that in the case of Jordan, Kuwait and Saudi Arabia, there exists bidirectional causalities after the crisis period but not the before. The opposite status is available for the case of Iran. In the case of Oman, there is bidirectional causality between the variables of interest in both periods. The results also reveal that the relationship between stock prices and exchange rates has become stronger after the 2007 global financial crisis. Overall, the results of this study indicate that fluctuations in foreign exchange markets can significantly affect stock markets in the Middle East.

Effects of surface silylation on dye removal performance of mesoporous promoted titania-silica nanocomposite

Parham Haghighi,Amin Bazyari,Somayeh Alijani,Fatemeh Khademian,Levi Theodore Thompson 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.5

Surface modification of a mesoporous tungsten- and bismuth-promoted titania-silica nanocomposite was conducted by a silylation method using hexamethyldisilazane (HMDS) as the silylation reagent to overcome the low adsorption capacity of TiO2-based photocatalysts for organic dyes, which subsequently enhances photodegradation of the organic dyes under visible light irradiation. The performance of the nanocomposites was evaluated by photodegradation of Rhodamine B (RhB) dye under visible light irradiation in a triple-walled immersion well reactor. The synthesized nanocomposites were characterized by N2 adsorption-desorption, FE-SEM, XRD, SAED pattern, HR-TEM, EDX, FTIR, UV-Vis DRS, PL spectroscopy, TGA, and water contact angle measurement to determine the bulk structure and surface properties before and after surface silylation. The results revealed that surface hydroxyl groups were successfully replaced by the silyl groups via the silylation process, without significant alterations in the structure and textural properties of the nanocomposite. In addition, silylation of the nanocomposite surface significantly enhanced the adsorption capacity of RhB molecules due to increased surface hydrophobicity, which accelerated the photocatalytic degradation of RhB in water. The results of the photocatalytic degradation experiments demonstrated that although all the synthesized nanocomposites were able to remove all RhB molecules from water after 240 minutes of the reaction, the optimized silylated sample with 0.15 g of HMDS (TSWBi-Sil3) was able to remove 92% of the RhB after only 90 minutes, while it was only 79% for the unmodified nanocomposite.

실재로서의 자연과 실천으로서의 환경운동

이영현 (토론자),John Parham (토론자) 문학과 환경학회 2008 문학과 환경 Vol.7 No.2

Investigation of adding cement kiln dust (CKD) in ordinary and lightweight concrete

Shoaei, Parham,Zolfaghary, Sina,Jafari, Navid,Dehestani, Mehdi,Hejazi, Manouchehr Techno-Press 2017 Advances in concrete construction Vol.5 No.2

Cement kiln dust (CKD) is one of the most important waste materials in the cement industry. The large amount of this material, has encouraged researchers to propose new ways to recycle and reuse it. In this paper, effects of adding cement kiln dust to the ordinary Portland cement, on the physical and mechanical properties of ordinary and lightweight concrete were investigated. Results showed that concrete containing CKD, presents lower workability and modulus of elasticity; however, improvements in strength was observed by adding particular amounts of CKD. Eventually, it was found that adding 10% of cement weight CKD is the appropriate percentage for utilizing in manufacturing ordinary and lightweight concrete.

Pre-concentration and determination of traces of nitrobenzene and 1,3-dinitrobenzene in water samples using anthracite adsorbent

Hooshang Parham,Sedighe Saeed 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.3

This study introduces a novel analytical method for the determination of nitrobenzene (NB) and 1,3-dinitrobenzene (DNB) from an aqueous solution using high performance liquid chromatography (HPLC)and anthracite as adsorbent for pre-concentration. The method showed good linearity for determinationof NB and DNB concentrations in the range of 0.10–200 mg L-1 with regression coefficients better than0.9995. Limits of detections (LOD) were 0.010 and 0.055 mg L-1 for DNB and NB, respectively. Relativestandard deviations (RSD) for 0.50 mg L-1 and 150 mg L-1 were in the range of 2.0–3.8% for (DNB) and3.0–4.8% for (NB).

GAPDH, β-actin and β2-microglobulin, as three common reference genes, are not reliable for gene expression studies in equine adipose- and marrow-derived mesenchymal stem cells

Nazari, Fatemeh,Parham, Abbas,Maleki, Adham Fani Korean Society of Animal Science and Technology 2015 한국축산학회지 Vol.57 No.5

Background: Quantitative real time reverse transcription PCR (qRT-PCR) is one of the most important techniques for gene-expression analysis in molecular based studies. Selecting a proper internal control gene for normalizing data is a crucial step in gene expression analysis via this method. The expression levels of reference genes should be remained constant among cells in different tissues. However, it seems that the location of cells in different tissues might influence their expression. The purpose of this study was to determine whether the source of mesenchymal stem cells (MSCs) has any effect on expression level of three common reference genes (GAPDH, ${\beta}$-actin and ${\beta}2$-microglobulin) in equine marrow- and adipose-derived undifferentiated MSCs and consequently their reliability for comparative qRT-PCR. Materials and methods: Adipose tissue (AT) and bone marrow (BM) samples were harvested from 3 mares. MSCs were isolated and cultured until passage 3 (P3). Total RNA of P3 cells was extracted for cDNA synthesis. The generated cDNAs were analyzed by quantitative real-time PCR. The PCR reactions were ended with a melting curve analysis to verify the specificity of amplicon. Results: The expression levels of GAPDH were significantly different between AT- and BM-derived MSCs (p < 0.05). Differences in expression level of ${\beta}$-actin (P < 0.001) and B2M (P < 0.006.) between MSCs derived from AT and BM were substantially higher than GAPDH. In addition, the fold change in expression levels of GAPDH, ${\beta}$-actin and B2M in AT-derived MSCs compared to BM-derived MSCs were 2.38, 6.76 and 7.76, respectively. Conclusion: This study demonstrated that GAPDH and especially ${\beta}$-actin and B2M express in different levels in equine AT- and BM-derived MSCs. Thus they cannot be considered as reliable reference genes for comparative quantitative gene expression analysis in MSCs derived from equine bone marrow and adipose tissue.

Determination of Trace Amounts of Zirconium by Flotation - Spectrophotometric Method

Pourreza, N.,Parham, H.,Shiri, S. Korean Chemical Society 2010 대한화학회지 Vol.54 No.3

지르코늄의 부유-분광 광도의 측정에 대한 감도가 좋고 재현성 있는 방법이 기록되었다. 그 방법은 지르코늄과 자일렌오렌지(XO)착물 형성에 기초하였고 그것은 격렬한 진탕에 의해 수용액 상과 n-헥산의 표면에 떠있게 된다. 수용액과 n-헥산을 폐기함에 따라 분리된 깔대기의 벽에 있던 흡착된 착물은 작은 부피의 메탄올 용액으로 해리되어진다. 그리고 그것의 흡광도는 429 nm에서 측정되었다. PH, HCl, XO의 농도, n-헥산 부유 용매의 부피, 지속시간과 진탕시간과 같은 다른 변수의 효과가 연구되었다. 보정곡선은 0.9991의 상관계수를 갖는 지르코늄의 7 ~ 120 ng/mL의 범위에서 선형이었다. 검출한계(LOD)는 58 ng/mL이었다. 지르코늄의 50과 110 ng/mL 의 7개의 분할척정에 대한 상대표준편차(RSD)는 4.4와 3.0%였다. 이 방법은 물샘플에서 지르코늄의 측정에 성공적으로 적용되었다. A sensitive and reproducible method for the flotation-spectrophotometric determination of zirconium is reported. The method is based on the complex formation zirconium and xylenol orange (XO) which is floated in the interface of aqueous phase and n-hexane by vigorous shaking. By discarding the aqueous solution and n-hexane, the adsorbed complex on to the wall of a separating funnel was dissolved in a small volume of methanol solvent and its absorbance was measured at 429 nm. The effect of different parameters such as pH, concentrations of HCl, and XO, and volume of n-hexane flotation dissolvent, standing and shaking time were studied. The calibration curve was linear in the range of 7-120 ng $mL^{-1}$ of zirconium with a correlation coefficient of 0.9991. The limit of detection (LOD) was 5.8 ng $mL^{-1}$. The relative standard deviation (RSD) for seven replicate measurements of 50 and 110 ng $mL^{-1}$ of zirconium were 4.4 and 3.0%, respectively. The method was successfully applied to the determination of zirconium in water samples.