Radiolysis of Solid-State Nitrogen Heterocycles Provides Clues to Their Abundance in the Early Solar System

We studied the radiolysis of a wide variety of N-heterocycles, including many of biological importance, and find that the majority are remarkably stable in the solid-state when subjected to large doses of ionizing gamma radiation from a 60Co source. Degradation of N-heterocycles as a function of dose rate and total dose was measured using high performance liquid chromatography with UV detection. Many N-heterocycles show little degradation when γ-irradiated up to a total dose of ~1 MGy, which approximates hundreds of millions of years’ worth of radiation emitted in meteorite parent bodies due to slow radionuclide decay. Extrapolation of these results suggests that these N-heterocyclic compounds would be stable in dry parent bodies over solar system time-scales. We suggest that the abundance of these N-heterocycles as measured presently in carbonaceous meteorites is largely reflective of their abundance at the time aqueous alteration stopped in their parent bodies, and the absence of certain compounds in present-day samples is either due to the formation mechanisms or degradation which occurred during periods of aqueous alteration or thermal metamorphism

Antenatal antiarrhythmic treatment for fetal tachyarrhythmias: a study protocol for a prospective multicentre trial

Introduction Several retrospective or single-centrestudies demonstrated the efficacy of transplacentaltreatment of fetal tachyarrhythmias. Our retrospectivenationwide survey showed that the fetal therapy willbe successful at an overall rate of 90%. For fetuseswith hydrops, the treatment success rate will be 80%.However, standard protocol has not been established.The objective of this study is to evaluate the efficacy andsafety of the protocol-defined transplacental treatment offetal tachyarrhythmias. Participant recruitment began inOctober 2010.Methods and analysis The current study is a multicentre,single-arm interventional study. A total of 50 fetuseswill be enrolled from 15 Japanese institutions. Theprotocol-defined transplacental treatment is performed forsingletons with sustained fetal tachyarrhythmia ≥180 bpm,with a diagnosis of supraventricular tachycardia or atrialflutter. Digoxin, sotalol, flecainide or a combination is usedfor transplacental treatment. The primary endpoint isdisappearance of fetal tachyarrhythmias. The secondaryendpoints are fetal death related to tachyarrhythmia,proportion of preterm birth, rate of caesarean sectionattributable to fetal arrhythmia, improvement in fetalhydrops, neonatal arrhythmia, neonatal central nervoussystem disorders and neonatal survival. Maternal, fetal andneonatal adverse events are evaluated at 1 month afterbirth. Growth and development are also evaluated at 18and 36 months of corrected age.Ethics and dissemination The Institutional Review Boardof the National Cerebral and Cardiovascular Center ofJapan has approved this study. Our findings will be widelydisseminated through conference presentations and peerreviewedpublications

Postural change for supine position does not disturb toddlers\u27 nap

This study examined whether forced postural change from prone to supine during toddlers’ nap, a preventative measure taken in Japan for sudden unexplained death in childhood (SUDC), disturbs toddlers’ sleep. When the "Back to Sleep" campaign (BSC) was introduced to Japan in 1996, its recommendations were also applied to infants aged 1 year old and over with the expectation that the BSC recommendations may also contribute to a decrease in the occurrence rate of SUDC. Since then, Japanese nurseries have routinely conducted sleeping position checks and positional adjustments of toddlers every 5–10 min during naps. A total of 52 toddlers (age 18.4 ± 3.3 months, means ± SD) were continuously monitored for 8 h during daytime at nursery schools for wake-sleep status and body position (prone, supine and lateral) with actigraphs and 3-orthogonal-axis accelerometers. Out of the 52 toddlers, 24 toddlers adopted prone positions during naps, which were adjusted by nursery staff back to supine. When nursery staff manually changed the toddlers position from prone to supine, the toddlers either did not wake or woke only briefly (3.1 ± 4.9 min) and returned to sleep soon after the positional change. Our study indicates that manual change of toddlers’ sleeping position from prone to supine, a potential SUDC prevention method, does not disturb toddlers’ sleep during their naps

Daytime nap and nighttime breastfeeding are associated with toddlers\u27 nighttime sleep

The purpose of the present study is to examine the association between toddlers\u27 sleep arrangements and their nighttime sleep duration and other sleep variables. For this investigation, we performed a study in which child activity and sleep levels were recorded using actigraphy. The parents of 1.5-year-old toddlers (n = 106) were asked to attach an actigraphy unit to their child’s waist with an adjustable elastic belt and complete a sleep diary for 7 consecutive days. Questionnaires were used to assess the sleep arrangements of the toddlers. There was a significant negative correlation between nap duration and nighttime sleep duration, suggesting that longer nap sleep induces shorter nighttime sleep duration. Among the sleep arrangements, such as nighttime breastfeeding or co-sleeping, only nighttime breastfeeding predicted shorter nighttime sleep duration. Our findings indicate that shorter naps induce a longer nighttime sleep in 1.5-year-old toddlers while nighttime breastfeeding decreases their nighttime sleep duration

Sleep maturation influences cognitive development of preterm toddlers

Our recent study on full-term toddlers demonstrated that daytime nap properties affect the distribution ratio between nap and nighttime sleep duration in total sleep time but does not affect the overall total amount of daily sleep time. However, there is still no clear scientific consensus as to whether the ratio between naps and nighttime sleep or just daily total sleep duration itself is more important for healthy child development. In the current study, to gain an answer to this question, we examined the relationship between the sleep properties and the cognitive development of toddlers born prematurely using actigraphy and the Kyoto scale of psychological development (KSPD) test. 101 premature toddlers of approximately 1.5 years of age were recruited for the study. Actigraphy units were attached to their waist with an adjustable elastic belt for 7 consecutive days and a child sleep diary was completed by their parents. In the study, we found no significant correlation between either nap or nighttime sleep duration and cognitive development of the preterm toddlers. In contrast, we found that stable daily wake time was significantly associated with better cognitive development, suggesting that sleep regulation may contribute to the brain maturation of preterm toddlers

Preterm toddlers have low nighttime sleep quality and high daytime activity.

A number of studies have been made on the sleep characteristics of children born preterm in an attempt to develop methods to address the sleep problems commonly observed among such children. However, the reported sleep characteristics from these studies vary depending on the observation methods used, i.e., actigraphy, polysomnography and questionnaire. In the current study, to obtain reliable data on the sleep characteristics of preterm-born children, we investigated the difference in sleep properties between 97 preterm and 97 term toddlers of approximately 1.5 years of age using actigraphy. Actigraphy units were attached to the toddlers’ waists with an adjustable elastic belt for 7 consecutive days, and a child sleep diary was completed by their parents. In the study, we found that preterm toddlers had more nocturnal awakenings and more daytime activity, suggesting that preterm-born children may have a different process of sleep development in their early development

Anisotropic phonon density of states in FePt nanoparticles with L1_{0} structure

The phonon states of iron atoms in the easy-axis aligned L1_{0}-FePt nanoparticles were investigated using 57Fe nuclear-resonant inelastic scattering. It was revealed that the phonon density of states (PDOS) in the L1_{0}-FePt has a pronounced anisotropy. To study the results from a theoretical point of view, we calculated the PDOS of the L1_{0}-FePt in the bulk state by means of the first-principles method. The results were in good agreement with the experimental results

Estimating the capacity for production of formamide by radioactive minerals on the prebiotic Earth

Water creates special problems for prebiotic chemistry, as it is thermodynamically favorable for amide and phosphodiester bonds to hydrolyze. The availability of alternative solvents with more favorable properties for the formation of prebiotic molecules on the early Earth may have helped bypass this so-called “water paradox”. Formamide (FA) is one such solvent, and can serve as a nucleobase precursor, but it is difficult to envision how FA could have been generated in large quantities or accumulated in terrestrial surface environments. We report here the conversion of aqueous acetonitrile (ACN) via hydrogen cyanide (HCN) as an intermediate into FA by γ-irradiation under conditions mimicking exposure to radioactive minerals. We estimate that a radioactive placer deposit could produce 0.1‒0.8 mol FA km−2 year−1. A uraninite fission zone comparable to the Oklo reactors in Gabon can produce 0.1‒1 mol m−2 year−1, orders of magnitude greater than other scenarios of FA production or delivery for which reaching sizeable concentrations of FA are problematic. Radioactive mineral deposits may be favorable settings for prebiotic compound formation through emergent geologic processes and FA-mediated organic chemistry