ИССЛЕДОВАНИЕ ГЕТЕРОСТРУКТУР МЕТОДОМ РЕНТГЕНОВСКОЙ ОДНОКРИСТАЛЬНОЙ ДИФРАКТОМЕТРИИ

The capabilities of an XMD−300 diffractometer were explored in three measurement setups, i.e. sliding primary beam, diffracted primary beam, θ–2θ setup for the crystalline perfection investigations of semiconductor heterostructures (SOS, SOI, AlGaN/GaN/Si, ion implanted silicon layers). We show that measurementsusing these three setups in scattered radiation and at direct validity of Bragg’s diffraction condition allowed receiving diffraction interference patterns simultaneously from the crystal lattice of several layers and interferential picks of maximum intensity for each individual layer.Рассмотрены возможности использования дифрактометра XMD−300 при трех схемах съемки: скользящего первичного пучка, скользящего дифрагированного пучка, схемы θ—2θ для исследования кристаллического совершенства полупроводниковых гетероструктур (кремний−на−сапфире, кремний−на−изоляторе, ионно−легированные слои кремния, структуры AlGaN/GaN/Si). Показано, что измерения с использованием трех схем в рассеянном излучении и при точном соблюдении условия брегговской дифракции позволяют получить интерференционную картину дифракции одновременно от кристаллических решеток нескольких слоев гетероструктуры и интерференционные пики максимальной интенсивностидля каждого отдельного слоя

Risk factors for pre-term birth in Iraq: a case-control study

BACKGROUND: Preterm birth (PTB)is a major clinical problem associated with perinatal mortality and morbidity. The aim of the present study is to identify risk factors associated with PTB in Mosul, Iraq. METHODS: A case-control study was conducted in Mosul, Iraq, from 1(st )September, 2003 to 28(th )February, 2004. RESULTS: A total of 200 cases of PTB and 200 controls of full-term births were screened and enrolled in the study. Forward logistic regression analysis was used in the analysis. Several significant risk associations between PTB and the following risk factors were identified: poor diet (OR = 4.33), heavy manual work (OR = 1.70), caring for domestic animals (OR = 5.06), urinary tract infection (OR = 2.85), anxiety (OR = 2.16), cervical incompetence (OR = 4.74), multiple pregnancies (OR = 7.51), direct trauma to abdomen (OR = 3.76) and abortion (OR = 6.36). CONCLUSION: The main determinants of PTB in Iraq were low socio-economic status and factors associated with it, such as heavy manual work and caring for domestic animals, in addition to urinary tract infections and poor obstetric history