Microstructural properties, thermal stability and superplasticity of a ZK60 Mg alloy processed by high-pressure torsion

An extruded ZK60 magnesium alloy was used to investigate microstructure, hardness and tensile properties after processing by 5 turns of high-pressure torsion (HPT) at room temperature. EBSD results confirmed the successful production of an ultrafine-grained structure with a mean grain size of ~700 nm with reasonable homogeneity and a majority of grains oriented parallel to the shear direction. This material also reached a homogeneous microhardness across the disk with an average hardness value saturated at Hv ?124 from the as-received hardness value of Hv ?74. The obtained high value is due to a high density of dislocations, the very small grain size and texture strengthening. The microhardness retained homogeneity after annealing samples processed by HPT for 40 hours at 448 K. However, the hardness value dropped to Hv ?85 while the mean grain size increased to ~2.1 ?m. These changes may be a result of restoration processes and consequent texture softening. Specimens processed by 5 turns of HPT exhibit excellent superplastic properties with a maximum elongation of 940% at 523 K and an optimum strain rate of 1.0×10-4 s-1. Significant superplasticity was observed at 448 K due to the stability of the bimodal structure at lower temperatures. This can assist the microstructure to accommodate grain boundary sliding and intragranular slip simultaneously and postpone any necking

Lifetime prevalence, sociodemographic predictors, and comorbidities of oppositional defiant disorder: The national epidemiology of iranian child and adolescent psychiatric disorders (IRCAP)

Objective: This was the first national epidemiological study on oppositional defiant disorder (ODD) in Iran, which provided new information about the prevalence, comorbidities, and sociodemographic predictors of ODD. Methods: Data from a face-to-face household survey of 30,532 children and adolescents aged 6-18 years were collected from across all 31 provinces of Iran using a multistage cluster sampling design. The Persian version of the Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children � Present and Lifetime Version (K-SADS-PL) was used in this study. Results: The lifetime prevalence of ODD was found to be 3.9. ODD was significantly more common in boys than girls and appeared in late adolescence more frequently than in childhood. A lower prevalence of ODD was found among participants who lived in rural areas. ODD is highly likely to co-occur with attention deficit hyperactivity disorder, separation anxiety disorder, generalized anxiety disorder, and depressive disorders. Conclusions: The findings of this national population-based study confirm and extend previous findings on the prevalence, comorbidities, and sociodemographic predictors of ODD. © 2020, Associacao Brasileira de Psiquiatria. All rights reserved

Prevalence and correlates of psychiatric disorders in a national survey of Iranian children and adolescents

Objective: Considering the impact of rapid sociocultural, political, and economical changes on societies and families, population-based surveys of mental disorders in different communities are needed to describe the magnitude of mental health problems and their disabling effects at the individual, familial, and societal levels. Method: A population-based cross sectional survey (IRCAP project) of 30 532 children and adolescents between 6 and 18 years was conducted in all provinces of Iran using a multistage cluster sampling method. Data were collected by 250 clinical psychologists trained to use the validated Persian version of the semi-structured diagnostic interview Kiddie-Schedule for Affective Disorders and Schizophrenia-PL (K-SADS-PL). Results: In this national epidemiological survey, 6209 out of 30 532 (22.31) were diagnosed with at least one psychiatric disorder. The anxiety disorders (14.13) and behavioral disorders (8.3) had the highest prevalence, while eating disorders (0.13) and psychotic symptoms (0.26) had the lowest. The prevalence of psychiatric disorders was significantly lower in girls (OR = 0.85; 95 CI: 0.80-0.90), in those living in the rural area (OR = 0.80; 95 CI: 0.73-0.87), in those aged 15-18 years (OR = 0.92; 95 CI: 0.86-0.99), as well as that was significantly higher in those who had a parent suffering from mental disorders (OR = 1.96; 95 CI: 1.63-2.36 for mother and OR = 1.33; 95 CI: 1.07-1.66 for father) or physical illness (OR = 1.26; 95 CI: 1.17-1.35 for mother and OR = 1.19; 95 CI: 1.10-1.28 for father). Conclusion: About one fifth of Iranian children and adolescents suffer from at least one psychiatric disorder. Therefore, we should give a greater priority to promoting mental health and public health, provide more accessible services and trainings, and reduce barriers to accessing existing services. © 2019 Tehran University of Medical Sciences. All rights reserved