Carbon Atom Condensation on NH3-H2O Ices. An Alternative Pathway to Interstellar Methanimine and Methylamine.

The recent discovery of the nature and behavior of carbon atoms interacting with interstellar ices has prompted a number of investigations on the chemistry initiated by carbon accretion on icy interstellar dust. In this work, we expand the range of processes promoted by carbon accretion to the chemistry initiated by the interaction of this atom with ammonia (NH3) using quantum chemical calculations. We found that carbon addition to the ammonia molecule forms a rather stable radical, CNH3, that is easily hydrogenated. The complete hydrogenation network is later studied. Our calculations reveal that while conversion to simpler molecules like HCN and HNC is indeed a possible outcome promoted by H-abstraction reactions, methylamine is also easily formed (CH3NH2). In fact, the stability of methylamine against hydrogen abstraction makes this molecule the preferred product of the reaction network. Our results serve as a stepping stone toward the accurate modeling of C-addition reactions in realistic astrochemical kinetic models.

Floating in Space: How to Treat the Weak Interaction between CO Molecules in Interstellar Ices.

In the interstellar medium, six molecules have been conclusively detected in the solid state in interstellar ices, and a few dozen have been hypothesized and modeled to be present in the solid state as well. The icy mantles covering micrometer-sized dust grains are, in fact, thought to be at the core of complex molecule formation as a consequence of the local high density of molecules that are simultaneously adsorbed. From a structural perspective, the icy mantle is considered to be layered, with an amorphous water-rich inner layer surrounding the dust grain, covered by an amorphous CO-rich outer layer. Moreover, recent studies have suggested that the CO-rich layer might be crystalline and possibly even be segregated as a single crystal atop the ice mantle. If so, there are far-reaching consequences for the formation of more complex organic molecules, such as methanol and sugars, that use CO as a backbone. Validation of these claims requires further investigation, in particular on acquiring atomistic insight into surface processes, such as adsorption, diffusion, and reactivity on CO ices. Here, we present the first detailed computational study toward treating the weak interaction of (pure) CO ices. We provide a benchmark of the performance of various density functional theory methods in treating the binding of pure CO ices. Furthermore, we perform an atomistic and in-depth study of the binding energy of CO on amorphous and crystalline CO ices using a pair-potential-based force field. We find that CO adsorption is represented by a large distribution of binding energies (200-1600 K) on amorphous CO, including a significant amount of weak binding sites (<350 K). Increasing both the cluster size and the number of neighbors increases the mean of the observed binding energy distribution. Finally, we find that CO binding energies are dominated by dispersion and, as such, exchange-correlation functionals need to include a treatment of dispersion to accurately simulate surface processes on CO ices. In particular, we find the ωB97M-V functional to be a strong candidate for such simulations.

Relationship between Antenatal Mental Health and Facial Emotion Recognition Bias for Children's Faces among Pregnant Women.

The importance of identification of facial emotion recognition (FER) bias for a child's face has been reinforced from the perspective of risk screening for future peripartum mental health problems. We attempted to clarify the relationship of FER bias for children's faces with antenatal depression and bonding failure among pregnant women, taking into consideration their broad social cognitive abilities and experience in child raising. This study had a cross-sectional design, and participants were women in their second trimester of pregnancy. Seventy-two participants were assessed by the Edinburgh Postnatal Depression Scale (EPDS), the Mother-to-Infant Bonding Questionnaire (MIBQ), and a series of social cognitive tests. FER bias for a child's face was assessed by Baby Cue Cards (BCC), and a larger number of disengagement responses suggest greater sensitivity to a child's disengagement facial expressions. In a regression analysis conducted using EPDS as the dependent variable, a larger number of disengagement responses to the BCC (ß = 0.365, p = 0.001) and the primipara status (ß = -0.263, p = 0.016) were found to significantly contribute to antenatal depressive symptoms. Also, more disengagement responses to the BCC also significantly contributed to bonding failure as measured by the MIBQ (ß = 0.234, p = 0.048). Maternal sensitivity to the child's disengagement cues was associated with antenatal depressive symptoms and bonding failure more than the other social cognitive variables. The effects of FER bias on postpartum mental health and abusive behavior needs to be clarified by further longitudinal studies.

Psychological impacts of the COVID-19 pandemic on one-month postpartum mothers in a metropolitan area of Japan.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has recently become the most important issue in the world. Very few reports in Japan have examined the impact of the COVID-19 pandemic on peripartum mental health. We examined the status of postpartum mental health before and during COVID-19 pandemic from a consecutive database in a metropolitan area of Japan. METHODS: The subjects were women who had completed a maternity health check-up at a core regional hospital in Yokohama during the period from April 1, 2017, to December 31, 2020. We collected the subjects' scores for the Edinburgh Postnatal Depression Scale (EPDS) and the Mother-to-Infant Bonding Scale (MIBS) at 1 month postpartum. The subjects were divided into four groups (three Before COVID-19 groups and a During COVID-19 group). MANOVA and post-hoc tests were used to determine mental health changes in the postpartum period among the four groups. RESULTS: The Before and During COVID-19 groups contained 2844 and 1095 mothers, respectively. There were no significant difference in the total scores of the EPDS and MIBS among the four groups. However, the EPDS items related to anxiety factors were significantly higher and the EPDS items related to anhedonia and depression factors (excluding thoughts of self-harm) were significantly lower in the During COVID-19 group. CONCLUSION: The EPDS scores changed in connection with the COVID-19 pandemic. Anxiety, which represent hypervigilance, was significantly higher and anhedonia and depression were significantly lower in the During COVID-19 group. Our results may reflect COVID-19-related health concerns and a lack of social support caused by the COVID-19 pandemic.

Case of Macular Hole Secondary to Ocular Toxoplasmosis Treated Successfully by Vitrectomy with Inverted Internal Limiting Membrane Flap.

We report a case of ocular toxoplasmosis that developed a full-thickness macular hole (FTMH) which was successfully treated by pars plana vitrectomy combined with an inverted internal limiting membrane (ILM) flap. A 49-years-old Japanese man was aware of blurred vision in his right eye. Slit-lamp biomicroscopy, ophthalmoscopy, and optical coherence tomography (OCT) of the right eye showed that there was a grayish-white subretinal lesion at the macula accompanied by retinal exudation and mild vitreous flare and iritis. An increase in the level of serum IgM for toxoplasma led to a diagnosis of ocular toxoplasmosis. He developed a FTMH adjacent to the lesion 2 weeks after administering sulfamethoxazole/trimethoprim, and his decimal visual acuity was 0.15. Because the FTMH remained 3 months after the resolution of inflammation and his metamorphopsia persisted, vitrectomy with an inverted ILM flap was performed. After the surgery, the visual acuity improved to 0.2 with the closure of the FTMH confirmed by OCT. A FTMH in an eye with ocular toxoplasmosis was successfully closed by vitrectomy with an inverted ILM flap.

Worsening of Retinal Detachment after Cataract Surgery in the Eye with Persistent Fetal Vasculature.

PURPOSE: To report a case of persistent fetal vasculature (PFV) with a retinal detachment that worsened after cataract surgery. Pars plana vitrectomy (PPV) was performed which reduced the vitreous traction and reattached the retina. Observations. A 20-year-old Myanmarese woman presented with a mature cataract, and her vision was light perception. She underwent uneventful cataract surgery with implantation of an intraocular lens. Her visual acuity improved to 20/200 immediately after the surgery. However, fibrotic tissue was observed between the optic nerve head and the posterior capsule. She was diagnosed with PFV, and she was followed without any intervention. One and a half years after the cataract surgery, she had an advanced retinal detachment which extended over the inferior two quadrants. Her vision deteriorated to 20/400. She underwent PPV, and the PFV tissue was removed which resulted in the reattachment of the retina. The visual acuity improved to 20/60. CONCLUSIONS: Surgeons should be aware that it is possible to worsen a retinal detachment after cataract surgery in the eyes with PFV. A simple technique to release the anterior-posterior traction by the PPV was sufficient to achieve the reattachment of the retina.

First-Principles Study of the Reaction Mechanism of CHO + H on Graphene Surface.

Many organic molecules observed in the interstellar medium are considered to be formed on dust grains and populated into the gas phase. We analyzed the reaction of HCO + H on a graphene surface using ab initio molecular dynamics simulations as a case study of the formation and desorption of organic molecules on interstellar dust particles. During the reactions of chemisorbed CHO (chemisorbed at the C atom) with free H, CO was generated and efficiently desorbed from the surface. These results suggest that the reactions, of which the reactant forms a covalent bond with the surface while the product does not, cause efficient desorption of the product upon reaction. In such reactions a repulsive force between the product and the surface would be generated and accelerate translation of the product in a specific direction. In addition, it was also shown that the branching ratio of the reactions between radical species on the surface would be affected by the form of the adsorption on the surface, e.g., when a free H reacted with the CHO chemisorbed at the C atom, CH2O was not generated.

The comet-like composition of a protoplanetary disk as revealed by complex cyanides.

Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.

Methane clathrates in the solar system.

We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate layers may exist on Pluto as well. Key Words: Methane clathrate-Protosolar nebula-Terrestrial planets-Outer Solar System. Astrobiology 15, 308-326.

Change in the chemical composition of infalling gas forming a disk around a protostar.

IRAS 04368+2557 is a solar-type (low-mass) protostar embedded in a protostellar core (L1527) in the Taurus molecular cloud, which is only 140 parsecs away from Earth, making it the closest large star-forming region. The protostellar envelope has a flattened shape with a diameter of a thousand astronomical units (1 AU is the distance from Earth to the Sun), and is infalling and rotating. It also has a protostellar disk with a radius of 90 AU (ref. 6), from which a planetary system is expected to form. The interstellar gas, mainly consisting of hydrogen molecules, undergoes a change in density of about three orders of magnitude as it collapses from the envelope into the disk, while being heated from 10 kelvin to over 100 kelvin in the mid-plane, but it has hitherto not been possible to explore changes in chemical composition associated with this collapse. Here we report that the unsaturated hydrocarbon molecule cyclic-C3H2 resides in the infalling rotating envelope, whereas sulphur monoxide (SO) is enhanced in the transition zone at the radius of the centrifugal barrier (100 ± 20 AU), which is the radius at which the kinetic energy of the infalling gas is converted to rotational energy. Such a drastic change in chemistry at the centrifugal barrier was not anticipated, but is probably caused by the discontinuous infalling motion at the centrifugal barrier and local heating processes there.