Rotational spectroscopic study of S-methyl thioformate: A global laboratory analysis of ground and excited torsional states up to 660 GHz.

CONTEXT: S-methyl thioformate CH3SC(O)H is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM). S-methyl thioformate being, thermodynamically, the most stable isomer, it can be reasonably proposed for detection in the ISM. AIMS: This work aims to experimentally study and theoretically analyze the ground and first torsional excited states for CH3SC(O)H in a large spectral range for astrophysical use. METHODS: S-methyl thioformate was synthesized as a result of a reaction of methyl mercaptan with acetic-formic anhydride. The millimeter-wave spectrum was then recorded for the first time from 150 to 660 GHz with the solid-state spectrometer located at Lille. RESULTS: A set of 3545 lines is determined and combined with 54 previously measured lines in the microwave region, belonging to ground state ν t = 0 as well as 1391 transitions in the first excited state of torsion ν 18 = 1. Some 164 lines were also assigned to ν 18 = 2 for the A-species. A global fit was performed using the BELGI-Cs code taking into account the large splitting of A and E lines due to methyl internal rotation motion with a relatively low barrier, V3 = 127.4846(15) cm-1. CONCLUSIONS: Using our spectroscopy work, a deep search of S-methyl thioformate was carried out in the IRAM 30m and ALMA data of different high-mass star-forming regions (Orion KL and Sgr B2). We derived an upper limit to the CH3SC(O)H column density in these regions.

Ab initio calculations of torsionally mediated hyperfine splittings in E states of acetaldehyde.

Quantum chemistry packages can be used to predict with reasonable accuracy spin-rotation hyperfine interaction constants for methanol, which contains one methyl-top internal rotor. In this work we use one of these packages to calculate components of the spin-rotation interaction tensor for acetaldehyde. We then use torsion-rotation wavefunctions obtained from a fit to the acetaldehyde torsion-rotation spectrum to calculate the expected magnitude of hyperfine splittings analogous to those observed at relatively high J values in the E symmetry states of methanol. We find that theory does indeed predict doublet splittings at moderate J values in the acetaldehyde torsion-rotation spectrum, which closely resemble those seen in methanol, but that the factor of three decrease in hyperfine spin-rotation constants compared to methanol puts the largest of the acetaldehyde splittings a factor of two below presently available Lamb-dip resolution.

Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol.

This paper presents an explanation based on torsionally mediated proton-spin-overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = - 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e., to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric "torsionally mediated spin-rotation operators" by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e(±niα). The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A1 and A2 states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.

Influence of the geometry of a hydrogen bond on conformational stability: a theoretical and experimental study of ethyl carbamate.

Spectra of ethyl carbamate (urethane) in the gas phase have been recorded in the microwave (4-20 GHz), millimeter-wave (49-118 GHz and 150-235 GHz) and mid-infrared (1000-1900 cm(-1)) regions. At the same time, high level ab initio calculations have been performed in order to both predict the experimental results and help in understanding the physical properties of the system. An extensive set of spectroscopic constants for the two most stable conformers in the gas phase, that might be useful for astrophysical databases, has been derived from the observed signals. The most stable conformer has been unambiguously identified. Then, the influence of a weak intramolecular hydrogen bond on the conformational stability has been discussed on the basis of theoretical and experimental results.

The Ground and First Excited Torsional States of Acetic Acid.

A global fit of microwave and millimeter-wave rotational transitions in the ground and first excited torsional states (v(t) = 0 and 1) of acetic acid (CH(3)COOH) is reported, which combines older measurements from the literature with new measurements from Kharkov, Lille, and NIST. The fit uses a model developed initially for acetaldehyde and methanol-type internal rotor molecules. It requires 34 parameters to achieve a unitless weighted standard deviation of 0.84 for a total of 2518 data and includes A- and E-species transitions with J

[Effect of gravitation loading and retabolil on development of atrophy in muscles and bones of rats due to suspension]. / Vliianie opornykh nagruzok i retabolila na razvitie atroficheskikh protsessov v myshtsakh i kostiakh krys pri vyveshivanii.

In a 3-wk experiment with tail-suspended rats histological and histomorphometric methods were used to determine the effects of graded gravitational loading (GGL) and anabolic steroid retabolil (nortestosterone decanoate) on the course of atrophy in soleus m. (SM), gastrocnemius m. (GM), tibia and humerus, and functioning of somatotrophic hormones (STH) of the pituitary and thyrocytes of the thyroid. Suspension was found to produce atrophy in SM and, to a less degree, in GM, partial transformation of SM slow fibers into the fast ones, suppression of the tibial longitudinal growth, demineralization of the tibial and humeral spongious metaphyses; besides, functional activities of STH-cells and thyrocytes were inhibited. Graded gravitational loading of rats by intermittence of suspension for 2 hrs slowed down atrophy in both muscles and osteopenia in tibia, stimulated the synthetic and secretory functions of STH-cells without any marked effect on thyrocytes or humeral osteopenia. GGL failed to influence the slow-to-fast transformation of SM fibers. Two injections of retabolil at the total dose of 3 mg/kg of the body mass somewhat interfered with the SM atrophy and humoral osteopenia, and were favorable to the synthetic but not secretory activity of STH-cells. Neither SM and tibial atrophies nor thyroid activity of the gland were improved. The prophylactic action of GGL upon the SM and humeral atrophies was significantly higher when combined with retabolil, whereas GM and tibia were not noticeably cured by retabolil. Inhibition of the SM atrophy and humeral osteopenia in rats treated with GGL and retabolil concurred with elevated activities of STH-cells and thyrocytes indirectly suggesting their more intensive production of the growth hormone and thyroid hormones, respectively.

[Birth injuries of the spine]. / Rodovye povrezhdeniia pozvonochnika.

Results of treatment of 204 children with labour traumas of the vertebral column are presented. Among the 204 patients there were 151 neonates, 28 infants and 25 patients with consequences of labour trauma. The cervical part is traumatized most frequently. Injury of the cervical vertebrae was diagnozed in 154 patients, of lumbar vertebrae in 18 patients. One child has an injury of the cervical and thoracic vertebra. In 41 patients there were ischemias in the vertebrobasilar area. An associated labour trauma of the vertebral column was diagnozed in 36% of the cases. Results of treatment were followed-up in 174 patients. Good results were obtained in 133 patients (76%). Satisfactory results were noted in 36 children (20%). Five patients died. Early and complex treatment gave good results in 93% of the cases.

[Evaluation of the action of ivermectin on blood-sucking mosquitoes]. / Otsenka deistviia ivermektina na krovososushchikh komarov.

The effect of Ivomec, a formulation of ivermectin administered by various routes: through biological membrane and feeder animal was assessed. Higher insecticidal effect was obtained by feeding mosquitoes with blood containing ivermectin through biological membrane. Anopheles stephensi females were the most sensitive of 3 species under study. Their total death after feeding was observed at 1 ppm, while for Aedes aegypti the lethal dose was 2.5 ppm and for An. sacharovi, 50 ppm. Subcutaneous injection of the drug to rabbits at the dose 0.34 mg/kg wt with further feeding on it of 3 Anopheles species demonstrated the highest drug sensitivity of An. stephensi mosquitoes. Death rates among the females fed on the rabbit 4-6 days after injection of the drug were 93, 70 and 79%, respectively. Death rates among An. sacharovi and An. atroparvus differed only slightly from that of the control group. In some experiments ivermectin effect on female fertility and larvae hatching from ova can be traced. Probably, increasing the preparation dose, administered to an animal-feeder, may change significantly characteristics of the malaria carrier natural population. Moreover, further use of ivermectin versus helminths and mosquitoes in zootechnical practice may produce a side-effect on mosquitoes, feeding recurrently on domestic animals, thus increasing the effect of malaria zoological control.

[Possibility of predicting and preventing postoperative complications leading to relaparotomy]. / Vozmozhnosti prognozirovaniia i profilaktiki posleoperatsionnykh oslozhnenii, privodiashchikh k relaparotomii.

The occurrence of relaparotomies is known to be 1,2% of operations on the abdomen organs. Pyo-inflammatory complications are responsible for more than half cases resulting in relaparotomies. Relaparotomies are divided into emergent and urgent, radical and palliative. A system for prognosis of complications and differential diagnosis of postoperative paresis of the gastro-intestinal tract and postoperative peritonitis is presented. Prophylactics of postoperative complications reduced lethality after relaparotomies from 79% to 56%.