Prevalence of asthma symptoms in Golestan schoolchildren aged 6–7 and 13–14 years in Northeast Iran

Asthma is the most common chronic disease among children, and its incidences are often imminent among elementary schoolchildren. This study aimed to examine the prevalence of asthma symptoms in Golestan schoolchildren aged 6–7 and 13–14 years in Northeast Iran. The prevalence rate was compared according to age group (aged 6–7 years vs. aged 13–14 years) and gender (male vs. female). In this cross-sectional study, 1706 Iranian schoolchildren aged 6–7 and 13–14 years in Golestan Province were enrolled. Participants completed questionnaires between February and July 2014. Asthma symptoms were assessed using the questionnaire of the International Study of Asthma and Allergies in Childhood protocol in Persian. The logistic regression model was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of the asthma symptoms for each of the gender and age groups. The prevalence rates of “current asthma” symptoms and “asthma ever” in all the children were estimated as 9.5% and 7.5%, respectively. The prevalence of asthma (“asthma ever” and “wheezing in the past 12 months”) in junior high schoolchildren (aged 13–14 years) is higher than that in elementary schoolchildren (aged 6–7 years) (P < 0.05). The prevalence of the severity of wheezing in girls is lower than that in boys (OR = 1.7, 95%CI = 1.06–2.96, P = 0.02). Asthma is still a major public health problem. This study shows that the prevalence of the asthma symptoms in boys is lower than that in girls in both age groups, and the severity of asthma in girls is higher than that in boys aged 13–14 years. © 2016 Higher Education Press and Springer-Verlag Berlin Heidelber

Production of biological nanoparticles from &#920- lactalbumin for drug delivery and food science application

In recent years, the concept of controlled release of encapsulated ingredients at the right place and the right time has become of more interest to the food and pharmaceutical industry. Whey proteins are valuable by-products from the cheese industry. The physicochemical properties of the whey proteins suggest that they may be suitable for novel food and drug delivery system. The objective of this study was to characterize the two step desolvation process of -lactalbumin for preparation of its nanoparticles. Following the desolvation of the protein with acetone, the produced nanoparticles were stabilized and cross linked by addition of glutaraldehyde. Nanoparticle sample was subsequently purified by 3 cycle’s centrifugation (15000 ×g, 20 min). Three process parameters were examined to achieve a suitable size of nanoparticles including the pH value, temperature and desolvating agent type. In addition, fabricated nanoparticles were analyzed by photon correlation spectroscopy (PCS) as well as scanning electron microscopy (SEM). The smallest size of the nanoparticles achieved was 102 nm while the largest size was 454 nm

Geotechnical Performance of Suction Caisson Installation in Multi-layered Seabed Profiles

Suction caissons consist of large cylindrical buckets made from steel. In order to serve as foundations for various offshore structures, suction caissons are pushed into the seabed under pressure differential exerted on their lid by an imposed suction. Despite their wide use in the oil and gas industry, there are still some uncertainties regarding their installation process as a result of changes in seabed profiles such as the existence of low permeability layers as well as the variation in soil properties with depth (e.g. permeability decreasing with depth due to an increase in soil density). It is known that seepage conditions play a pivotal role in the installation process, particularly in sand. Indeed, pressure gradients generated by the imposed suction inside the caisson cavity cause an overall reduction in the soil resistance around the caisson wall and at caisson tip, thereby assisting the penetration into the seabed. Successful installation of caisson foundations relies on accurate prediction of soil conditions, in particular soil shear resistance during the installation. Existing knowledge of the prediction of soil conditions and required suction during caisson installation has some limitations which often resulted into rather conservative design methods. Most design procedures used to control suction during caisson installation assume an isotropic and homogenous seabed profile. Moreover, the actual variation of pressure gradient around the caisson wall at different penetration depths is often ignored, although it significantly affects soil resistance. Natural seabed can possess a heterogeneous property where it may comprise of different layers of soils including the presence of layers with low-permeability i.e. clay or silt. In this paper, the effect of seepage on soil conditions during caisson installation is studied within the frame of the presence of a substratum that consists of silt. Suction induced seepage described throughout the installation process and its effects on frictional and tip resistance are considered. For this purpose, a numerical simulation is conducted on a normalised geometry of the suction caisson and surrounding soil, at different penetration depths. The distribution of pressure gradient on both inside and outside of the caisson wall is taken into consideration in both soil shear and tip resistance. Particular conclusions will be drawn on the implications of the presence of a low permeability silt layer on caisson installation

Unwanted Pregnancy and Its Risk Factors Among Pregnant Women in Tehran, Iran

Background: Unwanted pregnancies remain a main public health problem worldwide. In Iran, comparative studies on the risk factors of unwanted pregnancies and their effects on maternal health are rare. Objectives: This study was conducted to determine the risk factors of unwanted pregnancies and their impact on maternal behavior during pregnancy. Patients and Methods: This case-control study was carried out on 240 pregnant women who referred to the healthcare centers of Shahid Beheshti University of Medical Science for receiving routine prenatal care. Of the 240 women, 120 had unwanted pregnancies (case) and 120 had wanted pregnancies (control). Data collection was performed using a researcher-made questionnaire. The data were analyzed using chi-square tests, Fisher’s exact tests, t-tests, Mann Whitney U tests, odds ratios, and logistic regression analysis. Results: Compared to women with wanted pregnancies, those with unwanted pregnancies were more employed (23.3% vs. 12.5%, P = 0.006), had lower education levels (P = 0.016), had lower incomes (P = 0.009), had more children (1.30 ± 1.08 vs. 0.53 ± 0.67, P = 0.001), and had more traditional marriages (15% vs. 3.3%, P = 0.002). Also, women with unwanted pregnancies had significantly lower tendencies to do prenatal care (P = 0.002), had a higher tendency to abortion (P = 0.001), had higher previous abortion attempts (P = 0.001), and had higher levels of unhealthy behaviors (P = 0.017) compared to those with wanted pregnancies. Conclusions: Lower education and socioeconomic status, longer marriage duration, being employed, and unwilling of spouse were among the risk factors of unwanted pregnancies. These women are at high risk for unhealthy behaviors and have a higher tendency to abortion that consequently threatens their health

Modelling the variation of suction pressure during caisson installation in sand using FLAC3D

A suction caisson is an upturned ‘bucket’ of cylindrical shape made from steel. This type of foundation has been very popular in the oil and gas industry and the current trend is to extend its use to offshore wind farms. Seepage conditions play a pivotal role in suction caisson installation process in sand. Pressure gradients generated by imposed suction inside the caisson cavity cause an overall reduction in the soil resistance around the caisson wall and tip. This transient soil loosening around the caisson wall helps caisson penetration into the seabed. In this paper, we present a study of the role of seepage on the suction caisson installation process in homogenous sand. We also investigate the effects of seepage conditions on soil resistance to caisson penetration with a particular focus on how frictional and tip resistances are differently affected. For this purpose, a series of numerical models are developed using FLAC3D. These models are used to investigate the variation of suction pressure during caisson installation in homogenous sand and to predict the amount of suction required to penetrate the caisson to a certain depth. An explicit strategy is used for each embedment depth, which consists of updating current suction based on displacement history available after the previous prescribed displacement increment. The numerical models are developed for different caisson sizes and wall thicknesses to study the effects of caisson geometry on soil resistance during caisson installation. Problem dimensions are normalised with respect to the diameter of the caisson in order to obtain the results that can be applied to any caisson size. The results showed that suction pressure tends to increase with the embedment depth. Additionally, the overall behaviour and the pressure variation with depth are similar for caissons of different sizes and wall thicknesses. Finally, in order to validate the developed numerical models, data from centrifuge tests are investigated and compared with the results obtained from this study. The developed finite difference models are found to be in good agreement with centrifuge tests, in particular for thicker caissons (t/D = 1%)

Ultra-strong nonlinear optical processes and trigonal warping in MoS2 layers

Nonlinear optical processes, such as harmonic generation, are of great interest for various applications, e.g., microscopy, therapy, and frequency conversion. However, high-order harmonic conversion is typically much less efficient than low-order, due to the weak intrinsic response of the higher-order nonlinear processes. Here we report ultra-strong optical nonlinearities in monolayer MoS2 (1L-MoS2): the third harmonic is 30 times stronger than the second, and the fourth is comparable to the second. The third harmonic generation efficiency for 1L-MoS2 is approximately three times higher than that for graphene, which was reported to have a large χ (3). We explain this by calculating the nonlinear response functions of 1L-MoS2 with a continuum-model Hamiltonian and quantum mechanical diagrammatic perturbation theory, highlighting the role of trigonal warping. A similar effect is expected in all other transition-metal dichalcogenides. Our results pave the way for efficient harmonic generation based on layered materials for applications such as microscopy and imaging.We acknowledge funding from the Academy of Finland (Nos: 276376, 284548, 295777, 298297, and 304666), TEKES (NP-Nano, OPEC), Royal Academy of Engineering (RAEng) Research Fellowships, Fondazione Istituto Italiano di Tecnologia, the Graphene Flagship, ERC grants Hetero2D, Nokia Foundation, EPSRC Grants EP/K01711X/1, EP/K017144/1, EP/L016087/1, AFOSR COMAS MURI (FA9550-10-1-0558), ONR NECom MURI, CIAN NSF ERC under Grant EEC-0812072, and TRIF Photonics funding from the state of Arizona and the Micronova, Nanofabrication Centre of Aalto University

Modelling suction caisson installation in sand using FLAC3D

Suction caisson foundations have been very popular in oil and gas industry and the current trend is to extend their use to offshore wind farms. A suction caisson is an upturned ?bucket? of cylindrical shape made from steel. Seepage conditions play a pivotal role in suction caisson installation process in sand. Pressure gradients generated by the imposed suction inside the caisson cavity cause an overall reduction in the soil resistance around the caisson wall and tip. This transient soil loosening around the caisson wall helps caisson penetration into the seabed. However, these effects must be controlled to avoid soil failure due to critical conditions such as piping or loss of soil shear strength. In this paper, we endeavour to study the role of seepage on the suction caisson installation process in sand. We investigate the effect of seepage conditions on soil resistance to caisson penetration with a particular focus on how frictional and tip resistance are differently affected. For this purpose a series of finite difference simulations of suction caisson installation process are performed using FLAC3D models. The required suction is predicted using an explicit strategy which consists of updating current suction based on displacement history available after the previous prescribed displacement increment. The results of FLAC3D models show that this approach provides an insight on how soil resistance evolves under suction during the installation process and confirm the effect of seepage on total reduction of shear resistance around the caisson wall during installation in sand

Prevalence of asthma symptoms in Golestan schoolchildren aged 6�7 and 13�14 years in Northeast Iran

Asthma is the most common chronic disease among children, and its incidences are often imminent among elementary schoolchildren. This study aimed to examine the prevalence of asthma symptoms in Golestan schoolchildren aged 6�7 and 13�14 years in Northeast Iran. The prevalence rate was compared according to age group (aged 6�7 years vs. aged 13�14 years) and gender (male vs. female). In this cross-sectional study, 1706 Iranian schoolchildren aged 6�7 and 13�14 years in Golestan Province were enrolled. Participants completed questionnaires between February and July 2014. Asthma symptoms were assessed using the questionnaire of the International Study of Asthma and Allergies in Childhood protocol in Persian. The logistic regression model was used to estimate the odds ratios (ORs) and 95 confidence intervals (CIs) of the asthma symptoms for each of the gender and age groups. The prevalence rates of �current asthma� symptoms and �asthma ever� in all the children were estimated as 9.5 and 7.5, respectively. The prevalence of asthma (�asthma ever� and �wheezing in the past 12 months�) in junior high schoolchildren (aged 13�14 years) is higher than that in elementary schoolchildren (aged 6�7 years) (P < 0.05). The prevalence of the severity of wheezing in girls is lower than that in boys (OR = 1.7, 95CI = 1.06�2.96, P = 0.02). Asthma is still a major public health problem. This study shows that the prevalence of the asthma symptoms in boys is lower than that in girls in both age groups, and the severity of asthma in girls is higher than that in boys aged 13�14 years. � 2016, Higher Education Press and Springer-Verlag Berlin Heidelberg

Suction caisson installation in sand with isotropic permeability varying with depth

Suction-induced seepage is pivotal to the installation of caisson foundations in sand. Indeed, the upward pore water flow on the inner side of the caisson wall causes a release of a fraction of soil resistance due to the reduction of the lateral effective stress. A safe caisson installation requires a reliable prediction of soil conditions, especially soil resistance and critical suction for piping. These soil conditions must be predicted for the whole installation process. In this paper, we examine the effect on such prediction of the assumed permeability profile, which is described as a function of depth below the mudline. This study is motivated by the fact that marine sediments generally exhibit a permeability that decreases with depth because of consolidation under gravity. Hence, the question is whether conventional theories based on a constant permeability lead to a conservative prediction of soil conditions or not. Our conclusion is affirmative only regarding piping condition. As for soil resistance, a prediction based on the assumption of a constant permeability is non-conservative. This is due to an overestimated reduction in effective stresses under suction-induced seepage