The Effect of Shape and Stiffness of Originally Different Marine Soil Grains on Their Contractive and Dilative Behavior

Habib Shahnazari,Hossein Salehzadeh,Reza Rezvani,Yasser Dehnavi 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.4

Laboratory research was conducted to compare the monotonic behavior of two different marine calcareous sands - Hormuz Island(HI) and Bushehr Port (BP) - with siliceous sand named Firoozkuh sand (F). A series of undrained isotropically consolidated triaxialtests was performed on reconstituted specimens of these sands. In this experimental investigation, their contractive and dilativebehaviors were evaluated. The effect of some important parameters, such as relative density and confining pressure on the behaviorof these specimens was studied. To analyze the effect of shape and stiffness (resistance to particle breakage) on the contractive andthe dilative responses of these soils, the influence of axial strain on the crushability of the calcareous soils was assessed. Thereafter,the undrained behavior of the soils was analyzed, using two parameters, which represented a normalized variation of excess porewater pressure in two phases of monotonic triaxial tests. The contractive and dilative behavior of the two different calcareous sandswas compared to the siliceous sand. The results showed that particle shape played a key role in the behavior of soils in contractivephase. However, the shearing response of the used carbonate soils was more affected by particle crushing in dilation.

Associations between an MDM2 gene polymorphism and ulcerative colitis by ARMS-PCR

Doulabi, Mahsa Sadat Hashemi,Moghaddam, Reza Goleyjani,Salehzadeh, Ali Korea Genome Organization 2020 Genomics & informatics Vol.18 No.1

Ulcerative colitis is a form of inflammatory bowel disease characterized by chronic inflammation of the colon and rectum. The abnormal lesions in the digestive system caused by ulcerative colitis and intermittent colitis are of major clinical importance. MDM2 is a phospho-protein that functions as a ubiquitin ligase for p53. Recently, a T>G substitution in the promoter of the MDM2 gene (rs309) has been identified. In this case-control study, 174 ulcerative colitis biopsy samples and 82 control samples were collected from colonoscopy centers, hospitals, and clinics in Mazandaran and Gilan Provinces in Iran from October 2014 to May 2015. This MDM2 polymorphism was investigated in DNA samples (extracted from biopsy samples) by amplification-refractory mutation system polymerase chain reaction. The mean age of patients with ulcerative colitis was 46.5 years (range, 28 to 69 years) and that of control individuals was 45.3 years (range, 26 to 71 years). Seventy-eight patients (44.82%) were men and 96 (55.18%) were women. The distribution of the TT, TG, and GG genotypes was 17.93%, 27.59%, and 34.48%, respectively, in the ulcerative colitis patients and 31.70%, 24.40%, and 43.90%, respectively, in the control individuals (odds ratio of GG for ulcerative colitis, 7.142; 95% confidence interval, 2.400 to 9.542; p = 0.001). It was found that a single-nucleotide polymorphism at rs309 in the MDM2 gene was associated with ulcerative colitis. A direct relationship was found between age and ulcerative colitis, while no relationship was found with sex. This finding is of note because the occurrence of intestinal inflammation and subsequent ulcers can precede the development of cancer.

Effect of Gradation Curve and Dry Density on Collapse Deformation Behavior of a Rockfill Material

Ahmadreza Tabibnejad,Ali Akbar Heshmati,Hossein Salehzadeh,Saeed Hashemi Tabatabaei 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.3

Rockfill material, such as other coarse grained materials, undergoes rapid or sudden settlements of relatively large values, withoutany changes in the applied loads and only because of submerging. In the literature this phenomenon is called collapse deformation. The effects of gradation curve and dry density on the collapse deformation behavior of a rockfill material were explored and thechanges in the strength and deformability parameters of this material caused by submerging were determined. Two large scale triaxialequipments with three different sample diameters of 20, 30 and 80 cm were employed and a set of dry-saturated tests wereconducted. Specimens with different gradation curves and various initial dry densities were tested. The results indicate that in all ofthe dry-saturated tests, sudden reductions in the shear strengths and volumes of the specimens were observed during the submergingprocess. The effects of material maximum particle size, fines content and initial dry density on the value of sudden shear strengthreduction, internal friction angle reduction caused by saturation (Δφc), the change in elasticity modulus of the material due tosubmerging, i.e., (Ewet/Edry), and also the saturation-induced sudden volumetric strain (εvc) were evaluated and discussed.

Effect of Stress Conditions on Collapse Deformation Behavior of a Rockfill Material

Ali Akbar Heshmati,Ahmadreza Tabibnejad,Hossein Salehzadeh,Saeed Hashemi Tabatabaei 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

A set of saturated and dry-saturated large-scale triaxial tests were conducted in order to explore the effects of stress conditions on the saturation-induced collapse deformation behavior of a rockfill material. Specimens were tested in different confining pressures and for dry-saturated tests the specimens were submerged in various shear stress levels. The results indicate that in all of the drysaturated tests a sudden reduction in the volume of the specimens was observed during the submerging process. The ratio of the minimum axial strength of a submerged specimen (at the end of the saturation process) to the shear strength of the specimen before saturation is defined as the coefficient of stress recovery, Csr. Results of the dry-saturated tests showed that this ratio increases as the confining pressure increases and decreases by increasing the shear stress level. According to the results of dry-saturated tests the values of internal friction angle reduction caused by saturation (Δφc), the ratio of the elasticity modulus of the material after saturation to its elasticity modulus in dry condition, i.e., Ewet/Edry, and also the saturation induced sudden volumetric strain (εvc) decrease as the confining pressure increases. However the shear stress level does not have any meaningful effect on the variation of Dfc, Ewet/Edry and (εvc).

Chemoselective N-Nitrosation of Secondary Amines under Mild and Heterogeneous Conditions

Zolfigol, Mohammad Ali,Choghamarani, Arash Ghorbani,Abolfazl, Taqian Nasab,Keypour, Hassan,Salehzadeh, Sadegh Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.5

Efficacy of Maxforce and Avion gel baits containing fipronil, clothianidin, and indoxacarb against the German cockroach (Blattella germanica)

Behroz DAVARI,Susan KASHANI,Hassan NASIRIAN,Mansour NAZARI,Aref SALEHZADEH 한국곤충학회 2018 Entomological Research Vol.48 No.6

The present study evaluated the efficacy of Maxforce gel baits containing 0.01% fipronil (Maxforce), 0.05% fipronil (Maxforce Magnum), 1.0% clothianidin (Maxforce Impact), and 0.6% indoxacarb (Avion gel bait; all from Bayer Environmental Science, Clayton, CA, USA) against reference and wild strains (Mobasher, Andisheh, Tamin‐e Ejtemaei, and Maskoni) of German cockroach collected in 2016. Test design and bait placement were according to World Health Organization (WHO) procedures for efficacy achieving a 95% mortality rate. Although cockroaches fed on all gel baits, gel baits containing clothianidin and indoxacarb were eaten at higher rates than gel baits containing 0.01% and 0.05% fipronil. The cumulative mortality rates reached 100% for all cockroach strains at 32, 28, 28 and 40 h after eating baits containing 0.01% fipronil, 0.05% fipronil, clothianidin, and indoxacarb, respectively. Efficacy (a 95% mortality rate) after exposure (consumption) of gel baits containing 0.05% fipronil and clothianidin was seen after 28 h, compared with 32 h for 0.01% fipronil and 40 h for indoxacarb. In conclusion, commercial gel baits have improved and may be more effective than spray formulations against German cockroaches.

Investigation of Failure Behaviour of Soil Nailed Excavations under Surcharge by Centrifuge Model Test

S. Mohammad Shoari Shoar,Ali A. Heshmati R.,Hossein Salehzadeh 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1

A series of centrifuge tests were performed to evaluate surcharge effects on the behavior of nailed vertical excavations. The primary purpose was to observe the mechanism of failure surface development and to compare the test results with software results based on equilibrium limit analysis. In this experiment, four different surcharges were applied to both samples with and without nails. Applying surcharge and the following excavation were performed in 40 g acceleration. At the beginning of the test, the excavation was maintained using a water-filled membrane, right next to it. At the target acceleration, the surcharge was modelled by filling the loading tank over the sample with water, and finally, with water draining from the membrane, soil excavation was simulated. Eventually, failure surfaces resulted from the experiment were compared with the ones calculated by the equilibrium limit analysis-based software. Results revealed that the shapes of failure surfaces are bilinear in all tests and that the surcharge has its effects on the development of failure surfaces. In the meantime, the pull-out mechanism was observed in the nails during failure, with no bending. The equilibrium limit analysis also estimates the width of failure wedge well and its depth conservatively.