Perinatal outcomes in twin late preterm pregnancies: results from an Italian area-based, prospective cohort study

Background: Multiple gestations represent a considerable proportion of pregnancies delivering in the late preterm (LP) period. Only 30% of LP twins are due to spontaneous preterm labor and 70% are medically indicated; among this literature described that 16–50% of indicated LP twin deliveries are non-evidence based. As non-evidence-based delivery indications account for iatrogenic morbidity that could be prevented, the objective of our observational study is to investigate first neonatal outcomes of LP twin pregnancies according to gestational age at delivery, chorionicity and delivery indication, then non evidence-based delivery indications. Methods: Prospective cohort study among twins infants born between 34 + 0 and 36 + 6 weeks, in Emilia Romagna, Italy, during 2013–2015. The primary outcome was a composite of adverse perinatal outcomes. Results: Among 346 LP twins, 84 (23.4%) were monochorionic and 262 (75.7%) were dichorionic; spontaneous preterm labor accounted for 85 (24.6%) deliveries, preterm prelabor rupture of membranes for 66 (19.1%), evidence based indicated deliveries were 117 (33.8%), while non-evidence-based indications were 78 (22.5%). When compared to spontaneous preterm labor or preterm prelabor rupture of membranes, pregnancies delivered due to maternal and/or fetal indications were associated with higher maternal age (p < 0.01), higher gestational age at delivery (p < 0.01), Caucasian race (p 0.04), ART use (p < 0.01), gestational diabetes (p < 0.01), vaginal bleeding (p < 0.01), antenatal corticosteroids (p < 0.01), diagnosis of fetal growth restriction (FGR) (p < 0.01), and monochorionic (p < 0.01). Two hundred twenty-six pregnancies (65.3%) had at least one fetus experiencing one composite of adverse perinatal outcome. Multivariate analysis confirmed that delivery indication did not affect the composite of adverse perinatal outcomes; the only characteristic that affect the outcome after controlling for confounding was gestational age at delivery (p < 0.01). Moreover, there was at least one adverse neonatal outcome for 94% of babies born at 34 weeks, for 73% of those born at 35 weeks and for 46% of those born at 36 weeks (p < 0.01). Conclusion: Our study suggests that the decision to deliver or not twins in LP period should consider gestational age at delivery as the main determinant infants’ prognosis. Delivery indications should be accurately considered, to avoid iatrogenic early birth responsible of preventable complications

A PROFILE-FITTING PROCEDURE FOR ANALYSIS OF BROADENED X-RAY-DIFFRACTION PEAKS .2. APPLICATION AND DISCUSSION OF THE METHODOLOGY

The convolutive X-ray peak profile-fitting methodology described in the previous paper [Enzo, Fagherazzi, Benedetti & Polizzi (1988). J. Appl. Cryst. 21, 536-542] has been applied to a series of fluorite samples milled for different times and two zirconia ultrafine powders, by using either pseudo-Voigt or Voigt (in the Kielkopf approximation) functions, in order to investigate the broadening due to microstructural factors (crystallite size and lattice distortions). In the fluorite milled powders Fourier analysis (Warren & Averbach and Vogel, Haase & Hosemann methods) has shown that lattice disorder is due to dislocations. Values for the crystallite size as well as for the lattice distortion parameters similar to those obtained with Fourier methods have been found using a suitable integral breadth plot based on an assumed Cauchyian shape for the broadened profiles. A very high computability limit was reached for the crystallite size (about 5000 A). In the ultrafine powders of zirconia the cubic, tetragonal and monoclinic polymorphs were studied. The noticeable Gaussian content present in the 222 reflections for both cubic and tetragonal forms can be explained in terms of the presence of'intercrystalline'-like distortions. This kind of lattice distortion, detected by means of the Fourier analysis, has also been confirmed by 'simplified' methods (two-line and single-line procedures). Examples of limitations of the present methodology are reported and discussed

Corrosion Protection and mechanical performance of SiO2 films deposited via PECVD on OT59 brass

SiO2 layers deposited on OT59 brass substrate (BS) via Plasma Enhanced Chemical Vapour Deposition (PECVD) were tested to examine their corrosion performance and nano-mechanical characteristics. The electrochemical tests were carried out in a standard very aggressive solution (aerated 1N H2SO4 at 25°C) by means of DC (Tafel curves) and AC (Electrochemical Impedance Spectroscopy - EIS) techniques. After a week (168h) of immersion time the best PECVD treatment was reached by a layer thickness of 1950 nm, even if thinner coatings had a non negligible effect. The hardness and the elastic modulus of the films and the BS were measured by load-depth nano-indentation tests. The results highlighted a significant increase in the Berkovich hardness of annealed coated samples compared to that of the bulk brass. The excellent protection was also certified after examining some industrial objects treated by means of the same industrial PECVD process