Shear design of HSC beams with combination of links and horizontal web steel

The existing recommendations in Eurocode 2 and the British Code of Practice for the shear design of beams are derived from research conducted essentially on normal-strength concrete (NSC) with cube strengths up to 50 MPa, and it was found that the shear strengths of high-strength concrete (HSC) members made with limestone aggregate are below the characteristic resistances of identical NSC members. Previous experimental tests have also shown that significant differences exist in the angle of crack of shear failure of NSC and HSC. This paper presents data from five beam tests, which demonstrate that HSC with limestone aggregate has a reduced shear strength compared with NSC made with gravel and thus shows a gap in knowledge in the design approach to shear resistance of HSC beams. Previous investigations have suggested that horizontal web steels can contribute to the overall shear resistance of a reinforced concrete member in conjunction with the other constituents, concrete, tension and shear steel. The paper also presents data from tests on 11 beam tests and shows that the shear resistance of HSC beams is highly dependent on dowel action resulting from horizontal web bars positioned at the centre of the depth of the beam. Past attempts to quantify this dowel action are investigated and an improved design rule is proposed

Shear design of HSC beams with combination of links and horizontal web steel

The existing recommendations in Eurocode 2 and the British Code of Practice for the shear design of beams are derived from research conducted essentially on normal-strength concrete (NSC) with cube strengths up to 50 MPa, and it was found that the shear strengths of high-strength concrete (HSC) members made with limestone aggregate are below the characteristic resistances of identical NSC members. Previous experimental tests have also shown that significant differences exist in the angle of crack of shear failure of NSC and HSC. This paper presents data from five beam tests, which demonstrate that HSC with limestone aggregate has a reduced shear strength compared with NSC made with gravel and thus shows a gap in knowledge in the design approach to shear resistance of HSC beams. Previous investigations have suggested that horizontal web steels can contribute to the overall shear resistance of a reinforced concrete member in conjunction with the other constituents, concrete, tension and shear steel. The paper also presents data from tests on 11 beam tests and shows that the shear resistance of HSC beams is highly dependent on dowel action resulting from horizontal web bars positioned at the centre of the depth of the beam. Past attempts to quantify this dowel action are investigated and an improved design rule is proposed

Effects of Thiobacillus, Sulfur and Micronutrient Spray on Some Traits of Green Beans

A factorial experiment with the split plot arrangement using the complete randomized block design with three replications was carried out adjacent to the Agriculture School of Shahrood University of Technology in 2010-2011 to study the effects of sulfur and Thiobacillus application and zinc and molybdenum sprays on some traits of green beans. The treatments included three levels of sulfur (zero, 100 kg/ha of sulfur powder, and 100 kg/ha of sulfur powder + Thiobacillus bacteria) as the main factor, and three levels of zinc spray (0, 5, and 10g/l) and two levels of molybdenum spray (0 and 0.5 g/l) as the sub-main factors. The treatments that included sulfur were applied before seeding. Zinc (using zinc sulfate) and molybdenum (using sodium molybdate) were sprayed during the growing season and 5 weeks after planting. Results showed the treatment of applying sulfur at 100 kg/hectare and Thiobacillus bacteria increased leaf fresh and dry weights by 57 and 54%, mean pod length by 14%, and number of lateral branches by 25% compared to the control. Moreover, this treatment increased pod fresh and dry weights by 41.6 and 42.11%, respectively, compared to the treatment of not applying sulfur, and improved yield by 42% compared to the control. Considering the results concerning yield in response to sulfur, zinc, and molybdenum, it can be said that application of sulfur and Thiobacillus together with zinc spray can be very useful in growing green beans

The effects of preanesthetic parental presence on preoperative anxiety of children and their parents: A randomized clinical trial study in Iran

Introduction: Parental presence during induction of anesthesia (PPIA) has been a controversial issue, with some studies showing its effects on reducing anxiety. Hence, this study aimed to investigate the effects of PPIA on preoperative anxiety of children as well as their parents. Materials and Methods: This clinical trial was conducted among 60 children aged 2–10 years and their parents. Children were randomly assigned to intervention (n = 30) and control (n = 30) groups. Children in the control group were taken to the operating room (OR) alone, while those in the intervention group were taken to the OR with one of their parents. When the anesthetic mask was placed on the children’s face (induction), the children’s preoperative anxiety in both groups was assessed using Modified‑Yale Preoperative Anxiety Scale (M‑YPAS), and after that the parents in the intervention group were escorted to the waiting area. Parents’ anxiety in both the groups was measured by the Spielberg State‑Trait Anxiety Inventory (STAI) in the waiting area. Data were analyzed using descriptive and inferential (independent t‑test and Chi‑square test) statistic methods through the Statistical Package for the Social Sciences version 18 software. Results: Results showed no significant difference between children’s anxiety in the intervention (70.83) and control (70.39) groups in the preanesthetic period. In addition, no significant difference was seen between the intervention (79.23) and control (85.86) groups regarding total parents’ anxiety. Conclusions: PPIA was not successful in reducing the children’s preoperative anxiety as well as parents’ anxiety. Future studies in this area are needed to clarify the effects of this intervention in pediatric populations

Association of screen time and physical activity with health-related quality of life in Iranian children and adolescents

Abstract Background Health-related quality of life (HRQoL) is a multidimensional concept with significant effects and children and adolescence; while physical activity (PA) and screen time (ST) have been suggested as its probable predictors. Present study aims to investigate the association of PA, ST and their combination, with HRQoL in a nationally-representative sample of Iranian children and adolescents. Methods As for the estimated sample size, 25,000 students aged 6–18 years were selected via multi-stage cluster sampling from 30 provinces of Iran. Sociodemographic data was obtained by using the questionnaire of the World Health Organization-Global school based student health survey (GSHS). Persian Pediatric Quality of Life inventory (PedsQL) and Physical Activity Questionnaire for the pediatric age group (PAQ-A) were applied for evaluating HRQoL and PA, respectively. PA scores 1–1.9 and 2–5 were respectively considered as low and high PA. The average duration of time spent on watching TV and leisure time computer use were considered as ST behaviors. ST of less than 2 h was considered low. Results Out of 25,000 invited individuals, 23,043 students (mean age: 12.5) completed the study (response rate: 92.17%). In linear regression models, ST duration had significant inverse association with total QoL (β: − 0.49, p < 0.05). PA showed positive significant associations with HRQoL total score (β: 1.8, p < 0.05). Joint association of PA and ST revealed the strongest association of “high PA-low ST” category with total HRQoL (β: 2.2, p < 0.05); while “high PA-high ST” showed better total HRQoL score (β: 1.3) compared to “low PA-low ST” subgroup. Conclusion Both PA and ST are significantly and independently associated with HRQoL in Iranian children and adolescents; while the adverse effect of prolonged ST could be diminished by a high PA

Association of passive and active smoking with self-rated health and life satisfaction in Iranian children and adolescents: the CASPIAN IV study

OBJECTIVE: To assess the joint association of passive and active smoking with self-rated health and life satisfaction among Iranian children and adolescents. METHODS: Using a multistage random cluster sampling method, a representative sample of 14 880 school students were selected from urban and rural areas of 30 provinces of Iran. Data were gathered using a questionnaire, a weight scale and metre. Participants were classified into four groups based on their smoking patterns: \u27non-smoker\u27, \u27only active smoker\u27, \u27only passive smoker\u27 and \u27active and passive smoker\u27. Life satisfaction (LS) and self-rated health (SRH) were assessed by self-administered validated questionnaires based on the WHO-Global School-based student Health Survey (WHO-GSHS). Data were analysed using a t-test, χ test and multiple logistic regression. RESULTS: A total of 13 486 individuals (6640 girls and 6846 boys) out of 14 880 invited participated in the study (response rate 90.6%). LS and good SRH showed linearly negative associations with smoking status in both sexes. The proportions of LS and SRH categories were significantly different among all subsets of smoking status. Those classified as \u27non-smokers\u27 had the highest proportions of LS and good SRH, followed by \u27only passive smokers\u27 and \u27only active smokers\u27, while those with \u27active and passive smoking\u27 had the lowest proportions of LS and good SRH. In a multivariate model, students in the \u27active and passive smoking\u27 group had lower odds of LS (OR 0.43; 95% CI 0.32 to 0.57) and good SRH (OR 0.51; 95% CI 0.38 to 0.68) than those in the \u27non-smoker\u27 group. Students in the \u27only passive smoker\u27 group also had lower odds of LS (OR 0.75; 95% CI 0.67 to 0.83) and good SRH (OR 0.72; 95% CI 0.66 to 0.80) compared with the \u27non-smoker\u27 group. CONCLUSIONS: Adolescents with different smoking habits and exposure patterns have poorer SRH and LS than non-smokers. Both active and passive smoking status could affect LS and SRH in adolescents. Therefore, smoking prevention strategies should be considered as a health priority in school health services for promoting psychological well-being in children and adolescents

Chlamydia Pneumoniae in the Atherosclerotic Plaques of Coronary Artery Disease Patients

An association between Chlamydia pneumoniae (C. pneumoniae) and cardiovascular disease has been demonstrated. In this study, we aimed to study this potential relationship in 105 Iranian patients. Coronary artery specimens from 105 Iranian patients undergoing CABG were analyzed by PCR method for C. pneumoniae. Serological evaluation for C. pneumoniae IgG and IgM was performed using ELISA. 53 specimens from mamillary artery were also investigated. C. pneumoniae PCR test result was positive for 23 (21.9%) of patients with coronary artery atherosclerosis, but none of the specimens from the mamillary artery was positive for C. pneumoniae when it was evaluated by the PCR (P<0.001). Coronary artery disease patients with and without a history of unstable angina or myocardial infarction were comparable in C. pneumoniae PCR test positive rates (P=0.618). Relevance of IgG and IgM positivity were also studied by correlating it to the study parameters, but no difference was found. CRP was significantly higher in the IgM positive group (P<0.001). A significant proportion of coronary atherosclerotic plaques are infected with C. pneumoniae while no infection was found in the normal mamillary artery specimens. No association was found between acute coronary syndromes and serological and PCR positivity. Further prospective randomized controlled studies with large patient population are needed to confirm our findings