Context. Knowledge about the composition and structure of interstellar ices is mainly based on the comparison between astronomical and laboratory spectra of astrophysical ice analogues. Carbon ...monoxide is one of the main components of the icy mantles of dust grains in the interstellar medium. Because of its relevance, several authors have studied the spectral properties of solid CO both pure and in mixtures. Aims. The aim of this work is to study the profile (shape, width, peak position) of the solid CO band centered at about 2140 cm-1 at low temperature, during warm up, and after ion irradiation to search for a structural variation of the ice sample. We also report on the appearance of the longitudinal optical-transverse optical (LO-TO) splitting in the infrared spectra of CO films to understand if this phenomenon can be related to a phase change. Methods. We studied the profile of the 2140 cm-1 band of solid CO by means of infrared and Raman spectroscopy. We used a free web interface that we developed that allows us to calculate the refractive index of the sample to measure the thickness of the film. Results. The profile of the fundamental band of solid CO obtained with infrared and Raman spectroscopy does not show any relevant modification after warm up or ion bombardment in the dose range investigated. We explain that the LO-TO splitting is not connected to a structural variation of the film. Ion irradiation causes the formation of new molecular species. Raman spectroscopy allowed us to detect, among other bands, a band centered at 1817 cm-1 that has been attributed to the infrared inactive species C2 and a band centered at 1767 cm-1 that remains unidentified.
Water ice exists on many objects in space. The most abundant icy species, among them water, are present in the icy satellites of the outer Solar System giant planets. The nuclei of comets, which are ...mainly composed of water ice, give another example of its abundance. In the interstellar medium (ISM), ice mantles, formed by molecular species sticking on dust grains, consist mainly of water ice. All these objects are exposed to ionizing radiation like ions, UV photons, and electrons. Sputtering of atoms, molecules, ions, and radicals from icy surfaces may populate and maintain exospheres of icy objects in the Solar System. In other respects, ionized hydrides such as OH+, H2O+, and H3O+ have been detected in the gas phase in star-forming regions. Interactions with cosmic rays could be an additional explanation to the current models for the formation of those species. In fact, laboratory simulations showed that the main components of the sputtered ionic species from water ice are oxygen hydrides. In this work, water ice targets were irradiated at several temperatures (10–200 K) by 90 keV O6+ ions, yielding an electronic stopping power of about 12 eV/Å, when the nuclear stopping power is comparable to the electronic stopping power. Sputtering of secondary ions after bombardment of the ice target was analyzed by time-of-flight mass spectrometry (TOF-SIMS). Besides hydrogen ions (H+, H2 +, H3 +), also O+, O2+, OH+, (H2O)+, and clusters of (H2O) n H+ with n = 1–8 are emitted. Our results show a progressive yield decrease with increasing temperature of all of the detected species. This is related to the structure of the ice: the ionic sputtering yield for crystalline ice is much lower than for an amorphous ice. For instance, amorphous ice at 10 K exhibits a yield of the order of 2 × 10–6 secondary (H2O) n H+ hydride ions/projectile (with n = 1–8). As the temperature is increasing toward the phase transition to crystalline ice, the yields decrease by about one order of magnitude.
Context. Sulfur is an abundant element in the cosmos and it is thus an important contributor to astrochemistry in the interstellar medium and in the solar system. Astronomical observations of the gas ...and of the solid phases in the dense interstellar/circumstellar regions have evidenced that sulfur is underabundant. The hypothesis to explain such a circumstance is that it is incorporated in some species in the solid phase (i.e. as frozen gases and/or refractory solids) and/or in the gas phase, which for different reasons have not been observed so far. Aims. Here we wish to give a contribution to the field by studying the chemistry induced by thermal and energetic processing of frozen mixtures of sulfur dioxide (one of the most abundant sulfur-bearing molecules observed so far) and water. Methods. We present the results of a series of laboratory experiments concerning thermal processing of different H2O:SO2 mixtures and ion bombardment (30 keV He+) of the same mixtures. We used in situ Fourier transform infrared (FTIR) spectroscopy to investigate the induced effects. Results. The results indicate that ionic species such as HSO3−, HSO4−, and S2O52− are easily produced. Energetic processing also produces SO3 polymers and a sulfurous refractory residue. Conclusions. The produced ionic species exhibit spectral features in a region that, in astronomical spectra of dense molecular clouds, is dominated by strong silicate absorption. However, such a dominant feature is associated with some spectral features, some of which have not yet been identified. We suggest adding the sulfur-bearing ionic species to the list of candidates to help explain some of those features. In addition, we suggest that once expelled in the gas phase by sublimation, due to the temperature increase, and/or by non-thermal erosion those species would constitute a class of molecular ions not detected so far. We also suggest that molecular sulfur-bearing ions could be present on the surfaces and/or in the atmospheres of several objects in the solar system, for example icy satellites of the giant planets and comets.
Context
Hypogonadism in Prader–Willi syndrome (PWS) is generally attributed to hypothalamic dysfunction or to primary gonadal defect. MKRN3
,
a maternal imprinted gene located on 15q11.2-q13 region, ...encodes makorin ring finger protein 3, whose deficiency causes precocious puberty, an extremely rare symptom in PWS.
Objective
This study aimed to evaluate MKRN3 levels in patients with PWS and to analyze its correlation with sexual hormone levels, insulin resistance and Body Mass Index (BMI).
Methods
We performed an observational cross-sectional study and enrolled 80 patients with genetically confirmed diagnosis of PWS with median age of 9.6 years.
Results
MKRN3 levels were measurable in 49 PWS patients with a geometric mean of 34.9 ± 22 pg/ml (median: 28.4). Unmeasurable levels of MKRN3 were found in 31 patients. No statistically significant differences were found between patients with and without measurable MKRN3 levels for any clinical, biochemical, or genetic characteristics. However, MKRN3 levels were inversely correlated with HOMA-IR index (
p
: 0.005) and HbA1c (
p
: 0.046) values. No statistically significant correlations were found between MKRN3 and LH, estradiol and testosterone concentrations, pubertal development and genetic defect, whereas a direct correlation with FSH was found (
p
: 0.007).
Conclusions
The typical genetic defect of PWS should lead to unmeasurable levels of the MKRN3 protein due to the inactivation of the paternal allele. Measurable circulating MKRN3 could suggest the possible involvement of tissue-specific imprinting mechanisms and other regulatory factors in gene expression. Correlations with HOMA-IR index, HbA1c, and FSH suggest peripheral actions of MKRN3, but future studies are warranted to investigate this topic.
The structure and bonding of solid acetonitrile (CH3CN) films on amorphous silica are studied, and chemical and physical processes under irradiation with 200 keV protons and 250-400 eV electrons are ...quantified using transmission infrared spectroscopy, reflection-absorption infrared spectroscopy and temperature-programmed desorption, with the assistance of basic computational chemistry and nuclear materials calculations. The thermal desorption profiles are found to depend strongly on the balance between CH3CN-surface and CH3CN-CH3CN interactions, passing from a sub-monolayer regime (binding energy: 35-50 kJ mol−1) to a multilayer regime (binding energy: 38.2±1.0 kJ mol−1) via a fractional order desorption regime characteristic of islanding as the coverage increases. Calculations using the SRIM code reveal that the effects of the ion irradiation are dominated by electronic stopping of incident protons, and the subsequent generation of secondary electrons. Therefore, ion irradiation and electron irradiation experiments can be quantitatively compared. During ion irradiation of thicker CH3CN films, a cross section for secondary electron-promoted chemical destruction of CH3CN of 4 (±1)×10−18 cm2 was measured, while electron-promoted desorption was not detected. A significantly higher cross section for electron-promoted desorption of 0.82-3.2×10−15 cm2 was measured during electron irradiation of thinner CH3CN films, while no chemical products were detected. The differences between the experimental results can be rationalized by recognizing that chemical reaction is a bulk effect in the CH3CN film, whereas desorption is a surface sensitive process. In thicker films, electron-promoted desorption is expected to occur a rate that is independent of the film thickness; i.e. show zeroth-order kinetics with respect to the surface concentration.
OBJECTIVE Adverse events related to spine surgery sometimes lead to litigation. Few studies have evaluated the association between spine surgical complications and medical malpractice proceedings, ...outcomes, and awards. The aim of this study was to identify the most frequent causes of alleged malpractice in spine surgery and to gain insight into patient demographic and clinical characteristics associated with medical negligence litigation. METHODS A search for "spine surgery" spanning February 1988 to May 2015 was conducted utilizing the medicolegal research service VerdictSearch (ALM Media Properties, LLC). Demographic data for the plaintiff and defendant in addition to clinical data for the procedure and legal outcomes were examined. Spinal cord injury, anoxic/hypoxic brain injury, and death were classified as catastrophic complications; all other complications were classified as noncatastrophic. Both chi-square and t-tests were used to evaluate the effect of these variables on case outcomes and awards granted. RESULTS A total of 569 legal cases were examined; 335 cases were excluded due to irrelevance or insufficient information. Of the 234 cases included in this investigation, 54.2% (127 cases) resulted in a defendant ruling, 26.1% (61) in a plaintiff ruling, and 19.6% (46) in a settlement. The awards granted for plaintiff rulings ranged from $134,000 to $38,323,196 (mean $4,045,205 ± $6,804,647). Awards for settlements ranged from $125,000 to $9,000,000 (mean $1,930,278 ± $2,113,593), which was significantly less than plaintiff rulings (p = 0.022). Compared with cases without a delay in diagnosis of the complication, the cases with a diagnostic delay were more likely to result in a plaintiff verdict or settlement (42.9% vs 72.7%, p = 0.007) than a defense verdict, and were more likely to settle out of court (17.5% vs 40.9%, p = 0.008). Similarly, compared with cases without a delay in treatment of the complication, those with a therapeutic delay were more likely to result in a plaintiff verdict or settlement (43.7% vs 68.4%, p = 0.03) than a defense verdict, and were more likely to settle out of court (18.1% vs 36.8%, p = 0.04). Overall, 28% of cases (66/234) involved catastrophic complications. Physicians were more likely to lose cases (plaintiff verdict or settlement) with catastrophic complications (66.7% vs 37.5%, p < 0.001). In cases with a plaintiff ruling, catastrophic complications resulted in significantly larger mean awards than noncatastrophic complications ($6.1M vs $2.9M, p = 0.04). The medical specialty of the provider and the age or sex of the patient were not associated with the case outcome or award granted (p > 0.05). The average time to a decision for defendant verdicts was 5.1 years; for plaintiff rulings, 5.0 years; and for settlements, 3.4 years. CONCLUSIONS Delays in the diagnosis and the treatment of a surgical complication predict legal case outcomes favoring the plaintiff. Catastrophic complications are linked to large sums awarded to the plaintiff and are predictive of rulings against the physician. For physician defendants, the costs of settlements are significantly less than those of losing in court. Although this study provides potentially valuable data from a large series of postoperative litigation cases, it may not provide a true representation of all jurisdictions, each of which has variable malpractice laws and medicolegal environments.
We present the analyses results of two bulk Terminal Particles, C2112,7,171,0,0 and C2112,9,171,0,0, derived from the Jupiter‐family comet 81P/Wild 2 returned by the Stardust mission. Each particle ...embedded in a slab of silica aerogel was pressed in a diamond cell. This preparation, as expected, made it difficult to identify the minerals and organic materials present in these particles. This problem was overcome using a combination of three different analytical techniques, viz. FE‐SEM/EDS, IR, and Raman microspectroscopy that allowed identifying the minerals and small amounts of amorphous carbon present in both particles. TP2 and TP3 were dominated by Ca‐free and low‐Ca, Mg‐rich, Mg,Fe‐olivine. The presence of melilite in both particles is supported by IR microspectroscopy, but is not confirmed by Raman microspectroscopy, possibly because the amounts are too small to be detected. TP2 and TP3 show similar silicate mineral compositions, but Ni‐free and low‐Ni, subsulfur (Fe,Ni)S grains are present in TP2 only. TP2 contains indigenous amorphous carbon hot spots; no indigenous carbon was identified in TP3. These nonchondritic particles probably originated in a differentiated body. This work found an unanticipated carbon contamination following the FE‐SEM/EDS analyses. It is suggested that organic materials in the embedding silica aerogel are irradiated during FE‐SEM/EDS analyses creating a carbon gas that develops a strong fluorescence continuum. The combination of the selected analytical techniques can be used to characterize bulk Wild 2 particles without the need of extraction and removal of the encapsulating aerogel. This approach offers a relatively fast sample preparation procedure, but compressing the samples can cause spurious artifacts, viz. silica contamination. Because of the combination of techniques, we account for these artifacts.
Context. C2O and C3O belong to the carbon chain oxides family. Both molecules have been detected in the gas phase towards several star-forming regions, and to explain the observed abundances, ...ion-molecule gas-phase reactions have been invoked. On the other hand, laboratory experiments have shown that carbon chain oxides are formed after energetic processing of CO-rich solid mixtures. Therefore, it has been proposed that they are formed in the solid phase in dense molecular clouds after cosmic ion irradiation of CO-rich icy grain mantles and released in the gas phase after their desorption. Aims. In this work, we contribute to the understanding of the role of both gas-phase reactions and energetic processing in the formation of simple carbon chain oxides that have been searched for in various low-mass star-forming regions. Methods. We present observations obtained with the Noto-32m and IRAM-30 m telescopes towards star-forming regions. We compare these with the results of a gas-phase model that simulates C2O and C3O formation and destruction, and laboratory experiments in which both molecules are produced after energetic processing (with 200 keV protons) of icy grain mantle analogues. Results. New detections of both molecules towards L1544, L1498, and Elias 18 are reported. The adopted gas phase model is not able to reproduce the observed C2O/C3O ratios, while laboratory experiments show that the ion bombardment of CO-rich mixtures produces C2O/C3O ratios that agree with the observed values. Conclusions. Based on the results obtained here, we conclude that the synthesis of both species is due to the energetic processing of CO-rich icy grain mantles. Their subsequent desorption because of non-thermal processes allows the detection in the gas-phase of young star-forming regions. In more evolved objects, the non-detection of both C2O and C3O is due to their fast destruction in the warm gas.
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