Crucible aperture: an effective way to reduce source oxidation in oxide molecular beam epitaxy process

Growing multi-elemental complex-oxide structures using an MBE (Molecular Beam Epitaxy) technique requires precise control of each source flux. However, when the component elements have significantly different oxygen affinities, maintaining stable fluxes for easily oxidizing elements is challenging because of a source oxidation problem. Here, using Sr as a test source, we show that a crucible aperture insert scheme significantly reduces the source oxidation in an oxide-MBE environment. The crucible aperture insert was shaped like a disk with a hole at the center and was mounted inside the crucible; it blocks most of the oxygen species coming to the source, thus reducing the source oxidation. However, the depth of the aperture disk was critical for its performance; an ill-positioned aperture could make the flux stability even worse. With an optimally positioned aperture insert, the crucible exhibited more than four times improvement in Sr flux stability, compared to a conventional, non-apertured crucible.Comment: 13 pages, 3 figure

Comparison of metformin and insulin in the treatment of gestational diabetes: a retrospective study

Background: As various data are available on treatment of gestational diabetes mellitus (GDM), our aim is to compare the effect of treatment of metformin, insulin and diet control in GDM on maternal and neonatal outcomes.Methods: A retrospective study was conducted and it includes 50 women of GDM treated with Metformin, 50 women with insulin and 50 with only diet control without any drug.Results: The outcome was not much different in all groups studied. Maternal outcomes were similar in all three groups. The difference was: post prandial glucose values after 2 hour of oral glucose were slightly high in the insulin group than in the metformin group (p <0.003). Neonatal outcome was also not different in all groups. But the incidence of neonatal hypoglycemia was higher in the insulin group (p = 0.03).Conclusions: The study suggests that metformin is effective for GDM and maternal or neonatal outcomes were similar as compared with insulin

Broad ligament ectopic pregnancy: a dilemma to diagnose

Broad ligament ectopic pregnancy is a rare and serious form of extrauterine pregnancy with a high risk of maternal mortality. There are no specific clinical features. Ultrasonography may help in diagnosis, but definitive diagnosis is made only during surgery. Authors are reporting a case of 30 years female G3P1L1A1 seven weeks pregnancy with previous lower segment cesarean section and previous history of right sided salpingectomy with no complaints. Ultrasound was advised to know the location of sac this time, in which, she was diagnosed as a case right sided unruptured live ovarian ectopic pregnancy. On examination, signs and symptoms of ectopic pregnancy were absent. On laparoscopy, she was diagnosed as a case of right sided live unruptured broad ligament ectopic pregnancy as her right ovary was absent because of previous surgery.  With advances in sonography and laparoscopic skills, more cases can be diagnosed in the first trimester and can be safely managed laparoscopically.

Obstetrics outcome in pregnant women with cardiac disease in tertiary care center, Dehradun, India

Background: Incidence of heart disease in pregnancy is about 1%. Pregnant patient with cardiac disease can present with lot of challenges for the obstetrician, paediatrician and the cardiologist. With improvement in diagnostic, medical, surgical management, more patient with cardiac diseases especially congenital are able to reach reproductive age. Therefore, still a cardiac disease remains a significant cause of maternal death. Maternal and fetal prognosis both is affected by the care given and the skills used in the treatment of the individual patient. Hospital has resulted in majority of cardiac disease patient being managed in a tertiary care center and this provide an opportunity to report on clinical experiences of pregnancy with cardiac disease, their management and obstetrical outcomes.Methods: This was a retrospective study, with all the patients detailed demographic information, diagnosis, course in the hospital, management, maternal and fetal outcome was obtained from the medical records and files.Results: Incidence of cardiac disease was found to be 0.7%, 47% of pregnant women fell in age group of 26-30 years, 38.2% were primigravida, only 23.53% were booked, and half of them belonged to NYHA II class. 73.5% had Rheumatic heart disease and the most common obstetrics complications were preterm labor and anemia. LSCS was done in 29.4% cases and 38.2% of the newborns were premature.Conclusions: Prematurity anaemia, IUGR, are the common obstetrical complication in pregnant patient with cardiac disease which can be taken care with increased awareness and pre-conceptional counselling especially in patient with congenital heart disease. For optimization of maternal and neonatal outcomes in these patients, dedicated team of obstetrician, fetal medicine specialist, pediatricians, cardiologist and anesthesiologist is the prime requirement

Sr flux stability against oxidation in oxide-MBE environment: flux, geometry, and pressure dependence

Maintaining stable fluxes for multiple source elements is a challenging task when the source materials have significantly different oxygen affinities in a complex-oxide molecular-beam-epitaxy (MBE) environment. Considering that Sr is one of the most easily oxidized and widely used element in various complex oxides, we took Sr as a probe to investigate the flux stability problem in a number of different conditions. Source oxidation was less for higher flux, extended port geometry, and un-melted source shape. The extended port geometry also eliminated the flux transient after opening a source shutter as observed in the standard port. We also found that the source oxidation occurred more easily on the crucible wall than on the surface of the source material. Atomic oxygen, in spite of its stronger oxidation effectiveness, did not make any difference in source oxidation as compared to molecular oxygen in this geometry. Our results may provide a guide for solutions to the source oxidation problem in oxide-MBE system.Comment: 22 pages, 7 figure