Ion chemistry in space Larsson, M; Geppert, W D; Nyman, G
Reports on progress in physics,
06/2012, Letnik:
75, Številka:
6
Journal Article
Recenzirano
We review the gas-phase chemistry in extraterrestrial space that is driven by reactions with atomic and molecular ions. Ions are ubiquitous in space and are potentially responsible for the formation ...of increasingly complex interstellar molecules. Until recently, positively charged atoms and molecules were the only ions known in space; however, this situation has changed with the discovery of various molecular anions. This review covers not only the observation, distribution and reactions of ions in space, but also laboratory-based experimental and theoretical methods for studying these ions. Recent results from space-based instruments, such as those on the Cassini-Huygens space mission and the Herschel Space Observatory, are highlighted.
Melatonin has potential neuroprotective capabilities after neonatal hypoxia-ischemia (HI), but long-term effects have not been investigated. We hypothesized that melatonin treatment directly after HI ...could protect against early and delayed brain injury. Unilateral HI brain injury was induced in postnatal day 7 rats. An intraperitoneal injection of either melatonin or vehicle was given at 0, 6 and 25 hours after hypoxia. In-vivo MRI was performed 1, 7, 20 and 43 days after HI, followed by histological analysis. Forelimb asymmetry and memory were assessed at 12-15 and at 36-43 days after HI. More melatonin treated than vehicle treated animals (54.5% vs 15.8%) developed a mild injury characterized by diffusion tensor values, brain volumes, histological scores and behavioral parameters closer to sham. However, on average, melatonin treatment resulted only in a tendency towards milder injury on T2-weighted MRI and apparent diffusion coefficient maps day 1 after HI, and not improved long-term outcome. These results indicate that the melatonin treatment regimen of 3 injections of 10 mg/kg within the first 25 hours only gave a transient and subtle neuroprotective effect, and may not have been sufficient to mitigate long-term brain injury development following HI.
Abstract
Using multi-electron–ion coincidence measurements combined with high level calculations, we show that double ionisation of SO
2
at 40.81 eV can be state selective. It leads to high energy ...products, in good yield, via a newly identified mechanism, which is likely to apply widely to multiple ionisation by almost all impact processes.
The formation of CN and its isotopologue C15N through radiative association has been investigated. We considered two processes for the collisions of ground state C(3P) and N(4S) atoms (A2Π → X2Σ+ and ...b4Π → a4Σ+), as well as, for the first time, we investigated the radiative association of ground state C(3P) and excited N(2D) atoms (B2Σ+ → X2Σ+). The cross-sections for the three processes have been calculated using semi-classical, quantum mechanical, and Breit–Wigner theories. The rate constants, derived from the combination of semi-classical and Breit–Wigner results, have been fitted to the Kooij formula to be used in astrochemical modeling. The rate constant for the B2Σ+ → X2Σ+ process dominates in the investigated temperature range (10–10 000 K), when its own asymptotic energy is used as a reference level. Moreover, the B2Σ+ → X2Σ+ process presents the most pronounced isotope effect on the rate constant. We suggest considering these newly investigated radiative association processes for the formation of CN and C15N in the interstellar medium.
An understanding of the normal bacterial microbiota of any organ is essential to provide the background to conditions and interventions that might cause the microbiota to change. In the vagina of the ...mare, a change of bacterial microbiota could be induced by introduction of semen, treatment with antibiotics, discharge from an unhealthy uterus etc. Previous studies on equine vaginal bacteria are not all conducted in the same way and results are not altogether consistent. Therefore, this study was designed to provide a deeper understanding of the bacterial microbiota of the mare vagina, and possible changes throughout the estrous cycle. The cranial portion of the vagina was sampled on day 0 (ovulation), day 3, day 7, and day 14 of the estrous cycle. The vaginal sampling was conducted with double-guarded occluded swabs from the cranial floor of the vagina. Ovulation was determined by rectal palpation and ultrasonic examination, and the day 0 samples were taken within ±24 h of ovulation. Swabs were brought to the laboratory in Amies medium within 2–3 h and were plated out immediately on both selective and non-selective agars. Results were registered as amount of growth (qualitatively), bacterial species and number of isolates. Bacterial growth was highest on day 3 and 7, representing the beginning and middle of diestrus. The dominant bacteria were Escherichia coli and Streptococcus zooepidemicus. Escherichia coli was especially dominant in maiden mares, compared to the mares that had foaled. An increase in bacterial diversity throughout the estrous cycle was observed, being highest on day 14. These results suggest that there are changes in the bacterial microbiota of the mare vagina throughout the normal estrous cycle.
•Equine vaginal bacteria were sampled on days 0, 3, 7 and 14 of the estrous cycle.•Bacterial growth was highest on day 3 and 7, during diestrus.•Bacterial diversity increased throughout the cycle, being highest on day 14.•Differences in microbiota were seen in maiden mares compared to foaled mares.•Knowledge of cyclical changes in normal flora is needed.
Four cultivars of strawberries (Senga Sengana, BFr77111, Elsanta, and Honeoye) were studied for their content of antioxidants, total antioxidant capacity, and low molecular weight carbohydrates in ...relation to harvest year, ripening stage, and cold storage. For ascorbic acid, chlorogenic acid, ellagic acid, and total antioxidative capacity, measured in both water-soluble and water-insoluble extracts, there was a 2-5-fold variation among cultivars. Unripe berries contained lower concentrations of chlorogenic acid and p-coumaric acid and also quercetin and kaempferol compared with riper berries. During cold storage for up to 3 days, relatively few changes in the concentration of the different antioxidants occurred. The concentrations of several investigated parameters were interrelated, for example, for ascorbic acid and water-soluble antioxidant capacity and for ellagic acid and water-insoluble antioxidant capacity. The dominating sugars in strawberries were fructose and glucose, but considerable amounts of sucrose were also present, and their contents varied among cultivars, giving a predicted glycemic index of ~81. Verbascose, raffinose, and stachyose were found in only minor amounts. The study shows that the concentration of a number of bioactive compounds in strawberries varied according to cultivar, ripening stage, and storage. This information should make it possible to select strawberries with an optimal content of bioactive compounds.
Summary
Background
Administration of pulsed inhaled nitric oxide (PiNO) improves arterial oxygenation in spontaneously breathing anaesthetised healthy horses and in horses undergoing colic surgery. ...However, because hypoventilation commonly occurs, horses are often mechanically ventilated to prevent hypercarbia.
Objectives
To evaluate the effects of PiNO on arterial oxygenation during anaesthesia in mechanically ventilated healthy horses and horses undergoing colic surgery.
Study design
Prospective nonblinded clinical trial.
Methods
Fifty horses undergoing elective arthroscopy (Group A) and 30 horses undergoing colic surgery (Group C) in dorsal recumbency were included in the study. Every second horse in each group received PiNO (A‐INO, C‐INO), the others served as controls (A‐CN, C‐CN). All horses were mechanically ventilated and anaesthesia was maintained with isoflurane. PiNO was mechanically delivered at the proximal end of the endotracheal tube as a pulse during the first part of each inspiration. Data were collected at the start (baseline, before PiNO) and at the end of inhalation anaesthesia. The Tukey method was used to compare baseline and end values for each parameter.
Results
Arterial oxygen tension (PaO2) increased from (median IQR) 13.6 (9.3, 30.1) at baseline to 24.2 (18.6, 37.0) kPa at the end of anaesthesia in A‐INO (P = 0.005) and from 7.7 (6.4, 8.5) to 15.5 (9.9, 26.9) kPa in C‐INO (P = 0.007). Mean (95% CI) difference in F‐shunt between baseline and end were −6 (−10; −1) and −11 (−22; −1) % in A‐INO (P = 0.005) and C‐INO (P = 0.04) respectively. There was no change in PaO2 or F‐shunt from baseline to end of anaesthesia in A‐CN or C‐CN.
Main limitations
Cardiac output was not measured, thus O2 delivery could not be calculated.
Conclusions
The combination of mechanical ventilation and PiNO improved pulmonary gas exchange during anaesthesia by a simultaneous decrease in F‐shunt and improved alveolar ventilation.
Background
The surgical repair of H-type tracheo-oesophageal fistulas situated below the level of the second thoracic vertebra requires an open thoracotomy or a thoracoscopy. We describe a novel ...technique that allows for the use of a cervical incision to repair a fistula situated in the thorax, thus diminishing surgical risk.
Case presentation
In this report, we describe a 3-day-old term baby with an H-type tracheo-oesophageal fistula where flexible bronchoscopy and gastroscopy were used to cannulate the fistula with a soft ureteric catheter. This allowed for it to be tractioned into the cervical region where it was surgically dissected and isolated. There was no need for re-intervention in the first 3 months after surgery.
Conclusion
Flexible bronchoscopy-aided cannulation of H-type fistulas can assist in intraoperative identification of the fistulous tract as well as help traction it into a surgically more accessible area like the cervical region.
One-neutron knockout reactions from Borromean nuclei are analyzed using a profile function analysis technique. The profile function, which is derived as the square root of the variance of the ...measured fragment + neutron momenta as a function of their relative energy, is shown to be very sensitive to the angular momentum of the knocked out neutron. Three cases are studied here: 7He, where the profile function analysis shows a presence of (s1/2)2 component in the 8He ground-state wave-function, 10Li, where the presence of a 11(2)% d-wave contribution to the relative energy spectrum above 1.5 MeV is found and, finally, the presence of a major s contribution around 0.5 MeV relative energy in the 13Be case and that the observed decay to the 12Be 2+ state originates in a d state in 13Be.
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