E‌X‌P‌E‌R‌I‌M‌E‌N‌T‌A‌L I‌N‌V‌E‌S‌T‌I‌G‌A‌T‌I‌O‌N T‌H‌E M‌E‌C‌H‌A‌N‌I‌C‌A‌L A‌N‌D S‌T‌R‌U‌C‌T‌U‌R‌A‌L S‌T‌R‌E‌N‌G‌T‌H‌S O‌F C‌O‌N‌C‌R‌E‌T‌E‌S C‌O‌M‌B‌I‌N‌E‌D R‌U‌B‌B‌E‌R W‌A‌S‌T‌E‌S A‌N‌D F‌I‌B‌E‌R‌S

The current research deals with the use of waste rubber powder with different forms and percentages as a replacement for the fine aggregates in concrete production for the purpose of examining different mechanical and structural properties at an experimental level. The mixed design of common concrete as well as other mixed designs having waste rubber powder were constructed. The amounts of waste rubber were equivalent to 5, 10, and 15% of actual volume of the aggregate. To remove the negative effects on some mechanical properties of the product such as compressive and tensile strength and impact resistance, the synthetic Polyphenylene Sulfide (PPS) fibers known as synthetic complex fibers with 0.75 and 1.5% were added to the concrete having waste rubber powder. The first part of this research examines the effects of the combination of fibers with waste rubber powder on the compressive, tensile, flexural strength, and impact resistance of specimens. Also, in the second part of this research, six concrete slabs were constructed with the structural performance of such concrete in road construction under elastic basement under direct loading. The displacement-load curve of the samples as well as the failure pattern of the samples were observed and analyzed. The result of the experiments on the standard specimen in the first part of this research showed that despite the decrease in compressive strength due to the simultaneous addition of rubber powder compared to the common concrete samples, the tensile, flexural strength, and impact resistance were improved compared to the samples constructed with common concrete. By replacing 15% rubber powder instead of the fine aggregates, the final impact resistance increased up to 48%. Simultaneous addition of 0.75 % fibers and 5% rubber doubled the impact resistance of the concrete. It is worth mentioning that 1.5% addition of fibers to the concrete having 5% rubber power increased final impact resistance up to 5.72 times of that of Ref concrete. The results of the second part of this research showed that the final capacity of fiber-rubber concrete slabs under elastic basement to have favorite flexural behavior as concrete pavement compared to common concrete slab increased up to 50%; meanwhile, the amount of absorbed energy and the strength of combined concrete slabs of rubber wastes and fibers were 3 times higher than those made by common concrete in the reference sample

Experimental evaluation of the effects of ingredients ratio, combination of slag and zeolite as Precursor and Emboss fiber on the strength characteristics of geopolymer mortar

About 7% of the total volume of carbon dioxide produced in the world belongs to cement plants. Therefore, it is necessary to look for suitable alternative materials that their mechanical characteristics are similar to or better than mortars made with OPC and also consider the concept of sustainable development and environmental protection. In this paper, the effects of ingredients ratio, combination of slag and zeolite as Precursor and adding Emboss fiber on the strength characteristics of geopolymer mortar has been investigated experimentally in three separate sections. The different parameters such as weight ratios of sand to slag, sodium silicate to sodium hydroxide in activator solution, concentration of sodium hydroxide solution, different volume percentages of Emboss fiber, and replacing a part of the slag with zeolite were considered and studied in three parts. In the first part, 18 mix designs including 180 specimens were casted to study the effect of ingredients ratios on 7-days and 28-days compressive strength. In the second part, 3 mixes designs were selected from the part 1 and considered as the second group including 105 specimens to measure the compressive strength and modulus of rupture. In the third part, a part of the slag in one of mix designs that was selected from part 1, was replaced with zeolite to study the effect of using combined slag-zeolite as Precursor to investigate 28-days compressive strength and modulus of rupture of the geopolymer mortar. 30 specimens were casted in part 3. Experimental results indicated that the reduction of the sand to slag ratio, the reduction of sodium silicate to sodium hydroxide ratio, the increase of sodium hydroxide molarity, and adding Emboss fiber, respectively, increased the compressive strength by 26, 6, 20, and 14%. The modulus of rupture of fiber specimens was increased up to 38% compared to non-fiber samples. Despite the significant reduction in the strength properties of geopolymer mortar containing zeolite, due to the large number of natural zeolite mines in our country (IRAN) and consequently easy access to this material, using a precursor composed of slag and zeolite could be a good idea

INVESTIGATION OF DESIGN CODES RELIABILITY FOR SEISMIC DESIGN OF STEEL PLATE SHEAR WALLS CONSISTING OF SEVERAL PARAMETERS

Steel plate shear walls have been used as lateral resistant systems at several buildings particularly at high rise building during past three decades. This system contains appropriate rigidity to control displacements and also have ductile failure and high energy dissipation mechanism, so it can be used for new buildings or strengthening existing structures at seismic prone areas. Generally steel plate shear walls are consisting of steel plate walls and two boundary columns and horizontal floor beams. In this paper, initially a steel plate shear wall of a 5-floor building at high seismic area was designed according to AISC 341-05, then ABAQUS finite element program was used to investigate the seismic behavior of structure and get hysteresis curves under cyclic loading and also investigate the several parameter effects on local instability and non-linearity of material at designed typical shear wall and also the other new walls with different opens and rigidities. Numerical analysis results indicate that rigidity, shear capacity, and energy dissipation of wall were increased whenever column dimensions and length to height ratio was increased. Moreover, the main failure mode as global buckling was happened at the base of the column with increasing of the number of floors, so indicating the decreasing capacity and rigidity. And also the results showed that more open dimensions caused the higher ductility, decreasing capacity and rigidity and dissipation. The higher capacity, rigidity, energy dissipation, and ductility were observed at shear wall consisting of the more stiff nesses

Asymptomatic Giardiasis in school children in Rey city

This cross-sectional descriptive study was undertaken to know the rate of intestinal parasites infestations in our school children population. A sum of 1155 fecal samples were analyzed from an equal number of children whose age were between 6-11 years old. The percentage of infestations were: Giardia lamblia (14.11%), hymenolepis nana (1.21%), ascaris lumbricoides (0.08%) and enterobius vermicularis (0.08%). We found no differences with regard to sex, age, father and mother levels of education, family size, body mass index (BMI) and the erythrocyte sedimentation rate (ER) between the stools positive and the stools negative cases. Nearly all cases of giardiasis (99.4%) were symptomatic. Eosinophilia was seen in (5.5%) of the infested children with giardiasis and in (0.5%) of the non-infested children, the difference was statistically non-significant (P=0.056). All cases of giardiasis (N=163) were treated with metronidazole 15 mg/kg/day in 3 divided doses for 7 days. Metronidazole was effective in (92.2%) of the treated children.&nbsp

Etiological profile of short stature in a referral endocrinology clinic

Background: Physiological growth is a sensitive long-term indicator of child health. Impaired growth of children may be the first manifestation of a serious chronic disease. Short stature is a common pediatric endocrine problem. The short stature, although not a disease per se, is a manifestation of several diseases. Its early diagnosis and treatment is most of the time rewarding. Methods: Children between the age group of 2 to 15 years with growth retardation attending endocrine clinic in Loghman Hospital, Tehran, in October 2003 through October 2005were evaluated for short stature. Evaluation included: detailed medical history, physical examination and laboratory tests such as blood count, thyroid function, growth hormone screening, bone age estimation, and karyotypes. Centers for Disease Control (CDC) growth charts was used for percentiles. Findings: 188 children (110 boys, 78 girls) with growth retardation, whose heights were below 2 standard deviation score for age and gender, attended endocrine clinic. Normal variations accounted for 85.5% of all etiologies for reasons such as constitutional delay 49% and familial short stature 26.5% and a combination of both 9%. The rest (14.5%) consisted of pathological short stature. Growth hormone deficiency and hypothyroidism were the most common causes of pathological short stature Conclusions: The most common cause of short stature was a normal variance followed by short stature caused by endocrine disturbances. In both sexes constitutional growth delay followed by familial short stature counted to the most common non-endocrine causes of short stature

Effect of Different Levels of Zinc on the Performance and Humoral Immunity Response in Broiler Chicken

This experiment was conducted to evaluate the effects of different levels of zinc on the performance and humoral immunity response in broiler chickens with 250 Ross broiler chickens with five experimental treatments consisted of five replicates in a completely randomized design. Treatments were diets containing: basal diet (control) and basal diet plus 40, 80, 120 and 160 mg Zn/kg. Results of the experiment indicated that birds were fed on diets containing 120 mg Zn/kg and control showed the highest and the lowest weight gain, respectively (P0.05). In connection with feed conversion ratio, the highest and the lowest means belonged to the treatments containing 40 and 120 mg Zn/kg respectively (P0.05). Regarding Bronchitis antibody titer in 13th and 19th days, the lowest titer belonged to the birds on the control and 40 mg Zn/kg and the highest titer belonged to the birds fed with 160 mg Zn/kg. The difference between this treatment and the others was significant (P0.05). In secondary SRBC at 36 days of age the best and the lowest titer were shown by 40 mg Zn/kg and 160 mg Zn/kg of diet, respectively(P0.05). Finally, the results indicated that addition of 120 mg Zn/kg, of diet improved weight gain and feed conversion ration. The levels of 40 and 160 mg Zn/kg of diet showed the highest immunity response against SRBC and Bronchitis respectively