High Pressure Melting of Iron with Nonmetals Sulfur, Carbon, Oxygen, and Hydrogen: Implications for Planetary Cores

The earth's core consists of a solid metallic center surrounded by a liquid metallic outer layer. Understanding the compositions of the inner and outer cores allows us to better understand the dynamics of the earth's core, as well as the dynamics of the cores of other terrestrial planets and moons. The density and size of the earth's core indicate that it is approximately 90% metallic, predominantly iron, with about 10% light elements. Iron meteorites, believed to be the remnants of planetary cores, provide further constraints on the composition of the earth's core, indicating a composition of 86% iron, 4% nickel, and 10% light elements. Any potential candidate for the major light element core component must meet two criteria: first, it must have high cosmic abundances and second, it must be compatible with Fe. Given these two constraints there are five plausible elements that could be the major light element in the core: H, O, C, S, and Si. Of these five possible candidates this thesis focuses on S and C as well exploring the effect of minor amounts of O and H on the eutectic temperature in a Fe-FeS core. We look at two specific aspects of the Fe-FeS system: first, the shape of the liquidus as a function of pressure, second, a possible cause for the reported variations in the eutectic temperature, which draws on the effect of H and O. Finally we look at the effect of S and C on partitioning behavior of Ni, Pt, Re,Co, Os and W between cohenite and metallic liquid. We are interested in constraining the shape of the Fe-FeS liquidus because as a planet with a S-enriched core cools, the thermal and compositional evolution of its core is constrained by this liquidus. In Chapter 1 I present an equation that allows for calculation of the temperature along the liquidus as a function of pressure and composition for Fe-rich compositions and pressures from 1 bar to 10 GPa. One particularly interesting feature of the Fe -rich side of the Fe-FeS eutectic is the sigmoidal shape of the liquidus. This morphology indicates non-ideal liquid solution behavior and suggests the presence of a metastable solvus beneath the liquidus. An important consequence of such curved liquidi is that isobaric, uniform cooling requires substantial variations in the solidification rate of the core. Additionally, in bodies large enough for P variation within the core to be significant, solidification behavior is further complicated by the P dependence of the liquidus shape. Brett and Bell (1969) show that at 3 GPa, the liquidus curvature relaxes, implying that the liquid solution becomes more ideal. By 10 GPa, the liquidus approaches nearly ideal behavior (Chen et al., 2008b). However, at 14 GPa, the liquidus again assumes a sigmoidal curvature (Chen et al., 2008a; Chen et al., 2008b), suggesting a fundamental change in the thermodynamic behavior of the liquid. Chapter 1 of this thesis accounts for the observed complexity in the liquidus up to 10 GPa thus enabling more accurate modeling of the evolution of the cores of small planets (Buono and Walker, 2011). Accurately knowing the eutectic temperature for the Fe-FeS system is important because it places a minimum bound on the temperature of a S-enriched core that has a solid and liquid component which are in equilibrium. Unfortunately literature values for the 1 bar to 10 GPa eutectic temperature in the Fe-FeS system are highly variable making the estimation of core temperature, an important geodynamic parameter, very difficult. In Chapter 2 we look at a possible cause of this observed variation by experimentally investigating the effects of H on the eutectic temperature in the Fe-FeS system at 6 and 8 GPa. We find that H causes a decrease in the eutectic temperature (but that O does not) and that this decrease can explain some of the observed scatter in the available data. The effect of H on the eutectic temperature increases with increasing pressure (i.e. the eutectic temperature is more depressed at higher pressures), matching the trend reported for the Fe-FeS system (Fei et al., 1997). Our work suggests a significantly higher eutectic temperature than is commonly used in the Fe-S system and explains the lower observed eutectic temperatures by employing the ternary Fe-S-H system. Additionally, we report an equation which allows for accurate prediction of the composition of the eutectic in the Fe-FeS system. The constraints presented here (eutectic temperature in the Fe-FeS system are 990 °C up to at least 8 GPa in conjunction with the equation presented in Chapter 1, allows for complete prediction of the Fe-rich liquidus in the Fe-FeS system to 8 GPa. It is important to understand the partitioning behavior of trace elements between the solid and liquid components of a system because it fundamentally informs our understanding of that systems chemical evolution. In light of this, we investigate partitioning behavior in the context of the Fe-S-Ni-C system in Chapter 3. Choice of this system was motivated by work outside the scope of this thesis investigating the liquidus relationships in the Fe-S-C system (Dasgupta et al., 2009). In these experiments, cohenite (Fe3C) is the stable solid phase, instead of Fe-metal and we find that the partition coefficients between cohenite and Fe-C-S liquids are significantly lower than those between Fe-metal and Fe-S liquids. There are two potential situations to which this work can be applied. With respect to core formation, although it is unlikely that any planets entire inner core is carbide, it is possible that in a C-rich planet, as the Fe core crystallizes, C in the liquid phase could be enriched to the point where cohenite is a stable crystalizing phase. Under these circumstances, we would predict smaller depletions of the elements studied in the outer core than would be the case for Fe-metal crystallization. This work can also be applied to the earth's upper mantle which is thought to become Fe-Ni metal-saturated as shallow as 250 km. Under these circumstances, the sub-system Fe-Ni-C (diamond) -S (sulfide) becomes relevant and Fe-Ni carbide rather than metallic Fe-Ni alloy could become the crystalline phase of interest. Our study implies that if cohenite and Fe-C-S melt are present in the mantle, the mantle budget of Ni, Co, and Pt may be dominated by Fe-C-S liquid. Additionally, in the case of a S-free system, W, Re, and Os will also be slightly enriched in Fe-Ni-C liquid over cohenite. In total this body of work better constrains several key aspects of the compositional and thermal evolution of cores in small planetary bodies and has potential implications for the earth's mantle

NEUROENDOCRINE CARCINOMA OF THE LARYNX WITH LAMBERT-EATON MYASTHENIC SYNDROME: A RARE CASE REPORT.

Neuroendocrine carcinomas (necs) of the larynx are varied and heterogeneous tumours of rare observation in clinical practice. The WHO classification of 2017 divides them into: (i) well differentiated neuroendocrine carcinomas (WD-NEC); (ii) moderately differentiated neuroendocrine carcinomas (MD-NEC); and (iii) poorly differentiated neuroendocrine carcinomas (PD-NEC), which includes (a) small cell neuroendocrine carcinoma (smcc) and (b) large cell neuroendocrine carcinoma (LCNEC)

Neuroendocrine carcinoma of the larynx with Lambert-Eaton myasthenic syndrome: a rare case report and literature review

This current report describes a rare clinical case of neuroendocrine carcinoma (NEC) of the larynx with associated Lambert-Eaton myasthenic paraneoplastic syndrome (LEMS). A 68-year-old male patient presented with severe dysphonia and dysphagia. He underwent a total laryngectomy and the excised lesion was extremely large. A pathological examination demonstrated 'morphological findings of a poorly differentiated carcinoma (G3) with aspects of neuroendocrine differentiation' (i.e. a poorly differentiated neuroendocrine carcinomas [PD-NEC]). Based on the patient's medical history and the immunohistochemical findings, he was treated with three cycles of neoadjuvant chemotherapy (cisplatin-etoposide) and then radiotherapy with a total dose of 70 Gy. Of the 10 cases of paraneoplastic syndrome (PNS) related to laryngeal NEC reported in the literature, nine of these syndromes were of an endocrine type. Only one case of PNS associated with laryngeal cancer had a neurological manifestation, which was LEMS. To the best of our knowledge, this current case has only one similar precedent in the literature and it is the second report of an association between a PD-NEC and LEMS. Laryngeal NECs are rare lesions with different prognostic characteristics. The diagnosis should be made using an endocrinological, neurological, radiological and histological multidisciplinary approach. A radical surgical approach is recommended

Small-Cell Carcinoma of Nasopharynx: A Case Report of Unusual Localization

Neuroendocrine tumors are a spectrum of rare and highly heterogeneous neoplasms with distinct functional and biological behavior in relation to location, tumor size, and histological differentiation. Neuroendocrine tumors arise from the neuroendocrine cells of the diffuse neuroendocrine system located in almost every organ. Neuroendocrine tumors in the head and neck district are usually reported in sinonasal cavities and larynx. We present the case of a nasopharyngeal small-cell neuroendocrine carcinoma, which, as far as we know, is the 16th case reported in literature

Low NT-proBNP levels in overweight and obese patients do not rule out a diagnosis of heart failure with preserved ejection fraction

Background Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome that presents clinicians with a diagnostic challenge. The use of natriuretic peptides to exclude a diagnosis of HFpEF has been proposed. We sought to compare HFpEF patients with N-terminal pro-brain natriuretic peptide (NT-proBNP) level above and below the proposed cut-off. Methods Stable patients (n = 30) with left ventricular (LV) ejection fraction ≥ 50% were eligible if they had a diagnosis of HF according to the European Society of Cardiology diagnostic criteria. Characteristics of patients with NT-proBNP below (≤125 pg/mL) and above (\u3e125 pg/mL) the diagnostic criterion were compared. Results There were 19 (66%) women with median age 54 years. Half were African American (16, 53%), and most were obese. There were no significant differences in clinical characteristics or medication use between groups. LV end-diastolic volume index was greater in high NT-proBNP patients (P = 0.03). Left atrial volume index, E/e\u27 ratio, and E/e\u27 ratio at peak exercise were not significantly different between NT-proBNP groups. Peak oxygen consumption (VO2), VO2 at ventilatory threshold, and ventilatory efficiency measures were impaired in all patients and were not significantly different between high and low NT-proBNP patients. Conclusions NT-proBNP was below the proposed diagnostic cut-off point of 125 pg/mL in half of this obese study cohort. Cardiac diastolic dysfunction and cardiorespiratory fitness were not significantly different between high and low NT-proBNP patients. These data indicate that excluding the diagnosis of HFpEF based solely on NT-proBNP levels should be discouraged

Diagnosi molecolare di sindrome di Brugada in un giovane atleta mediante il sequenziamento di un pannello multigenico con tecniche di nuova generazione

Mutations in genes driving the molecular pathways that regulate myocardial functions can predispose to many independent cardiopathies and also to sudden cardiac death (SCD) even in asymptomatic subjects. The overlapping clinical signs or symptoms or even silent phenotypes make it difficult to diagnose these diseases, therefore the risk of undiagnosed disease could be high especially in young adults and athletes, which may then incur in SCD. We describe the case of a clinical asymptomatic eight-year-old child, practicing soccer game, who underwent a screening medical examination to undertake the path of an increasing physical activity to become a competitive athlete, where abnormal signs at ECG indicated a suspicion of an arrhythmogenic heart disease. Molecular screening analysis, to discriminate among the various predisposing gene alterations, was performed using a 75 gene-panel for arrhythmias customized in our laboratory. The child resulted carrier of a loss-of-function mutation in the SCN5A gene (c.1126C>T). About 25% of Brugada patients carry mutations in this gene coding for the cardiac sodium channel. The loss-of-function mutations in SCN5A gene induce alterations of sodium ion conduction in cardiomyocytes, compatible with the Brugada Syndrome. This case report highlights the importance of the implementation of a rapid, sensitive and wide molecular screening to shed light on possible genetic alterations present also in asymptomatic athletes with negative family history, which may often remain undiagnosed, thus exposed to high risk of sudden death

Giant subcutaneous lipomatosis in Myoclonic Epilepsy with Ragged Red Fibers syndrome: The first literature report of "laparoscopic" excision

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Regular football training down-regulates miR-1303 muscle expression in veterans

Purpose: Regular exercise affects the expression of several genes, proteins and microRNAs (miRNAs) in time- and intensity-dependent manner promoting longevity. We previously identified from GeneChip Array analysis several differentially expressed genes and miRNAs in muscle from veteran football players (VPG) compared to active untrained elderly subjects (CG); here we focussed on miRNA-1303 (miR-1303). The aims of the present research were: to analyse the effects of football training on the expression of miR-1303 and to identify its putative target involved in the longevity pathways in skeletal muscle from VPG compared to CG. Methods: RNA samples from 12 VPG and 12 CG muscle biopsies were used to validate miR-1303 expression. Crossing four different bioinformatic algorithms, we identified 16 putative targets of miR-1303; from these, BAG-2, KLHL7 and KBTBD6 were chosen for further validation by Western blot analysis in LHCN-M2 human myoblasts transiently transfected with miR-1303. Results: Football training down-regulates miR-1303 expression in muscle from VPG compared to CG and the expression of BAG-2, a chaperon protein involved in the autophagy pathway, inversely correlated to overexpression of miR-1303 in a time-dependent manner, indicating that it is a miR-1303 potential target. Conclusions: This is the first report, to our knowledge, describing miR-1303 regulation in skeletal muscle by football training and the identification of a target protein, BAG-2, involved in the autophagy pathway. This result contributes to the enlargement of knowledge on the molecular mechanisms linking football training, autophagy and longevity

Robotic versus laparoscopic sacrocolpopexy for apical prolapse: a case-control study

The apical prolapse has always been considered the most complex of the defects of the pelvic floor, for both the difficulty of the surgical corrective technique and for the high post-surgical recurrence rate. Today, the laparoscopic sacrocolpopexy can be considered the standard treatment for apical prolapse. In the last years, several author performed robotic sacrocolpopexy, obtaining positive results. So, we developed a casecontrol study in order to compare the surgical outcome of robotic group with a control group of laparoscopic approach in patients with symptomatic apical pro-lapsed between January 2015 and December 2015 at University Hospital Policlinico "P. Giaccone" and Ospedali Riuniti "Villa Sofia-Cervello", Palermo. Our experience shows that robotic sacrocolpopexy can be considered in positive way for clinical results obtained: all procedures were executed with no complications, we noted a lower intraoperative blood loss and a shorter hospital stay than in laparoscopic group. Although the mean operative time and the economic costs are higher in robotic surgery, this study demonstrates that the use of robotic platform for repairing of symptomatic apical vaginal prolapse is feasible, safe and associated with short-term satisfactory results, representing therefore a valid alternative to laparoscopic approach