Electrochemical dissolution and passivation phenomena of gold cyanidation from roasted ore in the presence of iron oxides

Cette thèse de doctorat est divisée en des études sur l'or pur; la corrosion galvanique; et la polarisation de l'or en présence d'oxydes de fer contenus dans un minerai d'or grillé. La dissolution de l’or diminue en présence de magnétite et, augmente en présence d’hématite et de maghémite. Des produits de corrosion et des couches adsorbées ralentissent la dissolution d’or. Pour les études sur l’or pur, une augmentation du pH de 10 à 11 a réduit de 35 fois la densité de courant, alors qu'elle a augmentée de 32 fois en diminuant l'agitation de 100 à 60 tr/min. Les études potentiostatiques, à trois potentiels anodiques, montrent que l'augmentation de la concentration de cyanure, du pH, et du potentiel diminuent la densité de courant. Des films d'oxydes d'or ont été identifiés par XPS. La mesure du bruit électrochimique est un outil prometteur pour estimer la vitesse de corrosion in situ. Pendant les tests de corrosion galvanique, utilisés en mode ampèremètre zéro-résistance, les électrodes minérales testées ont eu un effet négatif sur la lixiviation de l’or selon l’ordre décroissant : magnétite, magnétite-hématite avec des surfaces égales, et minerai d'or grillé. Cependant, la maghémite et l'hématite ont eu un effet positif. La concentration d'ions solubles et la vitesse de diffusion pourraient retarder ou favoriser la dissolution. L’argent a été identifié par XPS sur la surface de l’or, suggérant, une passivation partielle. À partir des études de polarisation potentiodynamique, l'hématite, en tant que composé système “combiné d'anode Au-hématite”, favorise le courant de corrosion anodique de 12%, alors que la magnétite abaisse le courant (de 11%). Les études de deux cellules séparées ont été réalisées pour révéler l’influence des ions solubles dans la dissolution de l’or. Le balayage du potentiel circuit ouvert jusqu’à vers des valeurs cathodiques en présence d'oxygène atmosphérique et de cyanure montre des vitesses de corrosion, déduites des pentes de Tafel, sont proches des à valeurs industrielles. La vitesse de lixiviation de l'or diminue de 40% en présence de pulpe de magnétite, alors que celle-ci augmente, respectivement de 25% et 10% pour l'hématite et la maghémite. MEB-EDX confirment l'effet négatif de la magnétite par la présence d’une forte accumulation d’oxydes de fer sur la surface de l'or. De faibles quantités d'or ont été identifiées sur les particules de magnétite par XPS. La séparation magnétique des résidus de cyanuration a été suivie la caractérisation électrochimique du concentré et des rejets.This Ph.D. thesis is divided into studies using pure gold; galvanic corrosion; and gold polarization in presence of iron oxides of roasted gold ore. Gold dissolution decreases in the presence of magnetite, and increases in the presence of hematite, and maghemite. The corrosion products and adsorbed layers lead to a slowdown of gold dissolution. For pure gold study, increasing pH from 10 to 11 results in a current density lower by 35 times, while it increases by 32 times with decreasing agitation from 100 to 60 rpm. At three anodic potentials, potentiostatic studies show that increasing cyanide concentration, pH, and potential decrease the current density. Au oxides have been identified by XPS. Electrochemical noise measurement is promising tool with its in-situ corrosion rate estimation. In galvanic corrosion studies, employing zero-resistance ammeter (ZRA) mode, the tested mineral electrodes show a negative effect on gold leaching in decreasing order: magnetite, magnetite-hematite with equal surfaces, and roasted gold ore. However, maghemite and hematite show a positive effect. Concentration of soluble ions and diffusion rate could retard or promote gold dissolution. Silver has been identified by XPS on gold surface suggesting partial passivation. In potentiodynamic polarization studies, hematite, as a part of the combined “Au-hematite anode” system promotes anodic corrosion current by 12%, while magnetite shows negative effect (11%). Two separate container tests have been considered to examine the influence of soluble ions on gold dissolution. Scanning from open circuit potential to more cathodic values in presence of atmospheric oxygen and cyanide shows corrosion rates obtained from Tafel slopes close to industrial practice. Gold leach rate decreases by 40% with magnetite slurry, whereas it increased by 25% and 10% for hematite and maghemite, respectively. SEM-EDS findings have confirmed the negative effect of magnetite due to the high accumulation of iron oxides on the gold surface. Low amounts of gold in magnetite particles are identified by XPS. Magnetic separation of leach tailings has been followed by electrochemical characterisation of the concentrate and the residues

Could ratio of hemoglobin to red cell distribution width and ratio of absolute lymphocyte count to absolute monocyte count be a prognostic tool in newly diagnosed multiple myeloma patients?

IntroductionHemoglobin/red cell distribution width (RDW) ratio (HRR) and lymphocyte-to-monocyte ratio (LMR) are two novel bio-markers associated with overall survival (OS) and prognosis in several types of cancers. The aim of this study is to investigate the value of HRR and LMR in newly diagnosed multiple myeloma (MM) patients. MethodsA total of 180 patients were included in this study. Patients diagnosed with MM between May 2013 and May 2019 at a single center were evaluated. HRR was calculated by dividing hemoglobin to RDW, both measured from the same sample. LMR was calculated by dividing absolute lymphocyte count (ALC) to absolute monocyte count (AMC). ResultsThe cutoff value for HRR was taken as 0.61, and the cutoff value for LMR was taken as 3.28. Patients were divided into low HRR, high HRR, low LMR, and high LMR groups. OS of the patients with low HRR was found lower compared with high HRR (36.7 months for low HRR and 53.2 months for high HRR, < 0.001). Also, OS was found lower in the low LMR group (39.4 months for low LMR and 51.7 months for high LMR, = 0.016). On multivariate analysis, low HRR and low LMR were predictive factors of OS (hazard ratio (HR) 2.08, 95% confidence intervals (CI) 1.31–3.03, and = 0.002 for low HRR; HR 1.47, 95% CI 0.92–2.29, and = 0.010 for low LMR). ConclusionCombining both HRR and LMR could be a prognostic biomarker and it reflects the status of the immune system in newly diagnosed MM patients

Volume CXIV, Number 4, November 7, 1996

Objective: Turner syndrome (TS) is a chromosomal disorder caused by complete or partial X chromosome monosomy that manifests various clinical features depending on the karyotype and on the genetic background of affected girls. This study aimed to systematically investigate the key clinical features of TS in relationship to karyotype in a large pediatric Turkish patient population.Methods: Our retrospective study included 842 karyotype-proven TS patients aged 0-18 years who were evaluated in 35 different centers in Turkey in the years 2013-2014.Results: The most common karyotype was 45,X (50.7%), followed by 45,X/46,XX (10.8%), 46,X,i(Xq) (10.1%) and 45,X/46,X,i(Xq) (9.5%). Mean age at diagnosis was 10.2±4.4 years. The most common presenting complaints were short stature and delayed puberty. Among patients diagnosed before age one year, the ratio of karyotype 45,X was significantly higher than that of other karyotype groups. Cardiac defects (bicuspid aortic valve, coarctation of the aorta and aortic stenosis) were the most common congenital anomalies, occurring in 25% of the TS cases. This was followed by urinary system anomalies (horseshoe kidney, double collector duct system and renal rotation) detected in 16.3%. Hashimoto's thyroiditis was found in 11.1% of patients, gastrointestinal abnormalities in 8.9%, ear nose and throat problems in 22.6%, dermatologic problems in 21.8% and osteoporosis in 15.3%. Learning difficulties and/or psychosocial problems were encountered in 39.1%. Insulin resistance and impaired fasting glucose were detected in 3.4% and 2.2%, respectively. Dyslipidemia prevalence was 11.4%.Conclusion: This comprehensive study systematically evaluated the largest group of karyotype-proven TS girls to date. The karyotype distribution, congenital anomaly and comorbidity profile closely parallel that from other countries and support the need for close medical surveillance of these complex patients throughout their lifespa

Early mobilisation in critically ill COVID-19 patients: a subanalysis of the ESICM-initiated UNITE-COVID observational study

Background Early mobilisation (EM) is an intervention that may improve the outcome of critically ill patients. There is limited data on EM in COVID-19 patients and its use during the first pandemic wave. Methods This is a pre-planned subanalysis of the ESICM UNITE-COVID, an international multicenter observational study involving critically ill COVID-19 patients in the ICU between February 15th and May 15th, 2020. We analysed variables associated with the initiation of EM (within 72 h of ICU admission) and explored the impact of EM on mortality, ICU and hospital length of stay, as well as discharge location. Statistical analyses were done using (generalised) linear mixed-effect models and ANOVAs. Results Mobilisation data from 4190 patients from 280 ICUs in 45 countries were analysed. 1114 (26.6%) of these patients received mobilisation within 72 h after ICU admission; 3076 (73.4%) did not. In our analysis of factors associated with EM, mechanical ventilation at admission (OR 0.29; 95% CI 0.25, 0.35; p = 0.001), higher age (OR 0.99; 95% CI 0.98, 1.00; p ≤ 0.001), pre-existing asthma (OR 0.84; 95% CI 0.73, 0.98; p = 0.028), and pre-existing kidney disease (OR 0.84; 95% CI 0.71, 0.99; p = 0.036) were negatively associated with the initiation of EM. EM was associated with a higher chance of being discharged home (OR 1.31; 95% CI 1.08, 1.58; p = 0.007) but was not associated with length of stay in ICU (adj. difference 0.91 days; 95% CI − 0.47, 1.37, p = 0.34) and hospital (adj. difference 1.4 days; 95% CI − 0.62, 2.35, p = 0.24) or mortality (OR 0.88; 95% CI 0.7, 1.09, p = 0.24) when adjusted for covariates. Conclusions Our findings demonstrate that a quarter of COVID-19 patients received EM. There was no association found between EM in COVID-19 patients' ICU and hospital length of stay or mortality. However, EM in COVID-19 patients was associated with increased odds of being discharged home rather than to a care facility. Trial registration ClinicalTrials.gov: NCT04836065 (retrospectively registered April 8th 2021)

Bidding for Olympic and Paralympic Games, transportation investments and tourism: the case of Istanbul

International audienc

High speed rail and spatial equity in developing countries: the case of Turkish high-speed railways

International audienc

Retinopathy of prematurity (ROP): From the perspective of the neonatologist

Retinopathy of prematurity (ROP) is a serious morbidity of prematurity. It is a pathophysiological condition that occurs due to abnormal proliferation of the retinal vessels. The incidence and severity of ROP increase with decreasing gestational age (GA) and birth weight (BW).The enhanced chance of survival of premature babies in parallel with the developments in neonatal care increased the incidence of ROP. Early diagnosis and timely and appropriate treatment of ROP increases the quality of life by preventing vision loss.Many risk factors were reported besides prematurity and inappropriate oxygen treatment for preterm infants. Pediatricians and neonatologists play important role in prevention, detection and management of ROP. It should be kept in mind that ROP may also lead to medicolegal problems

Percutaneous transcatheter embolization of gastrointestinal bleeding in a child with polyarteritis nodosa

Background: Polyarteritis nodosa is a form of necrotizing vasculitis of small and medium-sized arteries. Major gastrointestinal complications are ulceration, perforation, hemorrhage, and obstruction. Case Report: We report on a clinical case of a 16-year-old female patient with massive hematemesis, who was successfully treated with embolization with a 1:2 dilution of N-butyl cyanoacrylate glue. Conclusions: To the best of our knowledge, this is the youngest child reported on with massive GI bleeding secondary to PAN, treated with successful percutaneous transcatheter embolization under emergency conditions

Diagnosis and management of pediatric adrenal insufficiency

Background: Adrenal insufficiency (AI) is a wellknown cause of potentially life-threatening disorders. Defects at each level of the hypothalamic-pituitary-adrenal axis can impair adrenal function, leading to varying degrees of glucocorticoid (GC) deficiency. Iatrogenic AI induced by exogenous GCs is the most common cause of AI. The criteria for the diagnosis and management of iatrogenic AI, neonatal AI, and critical illness-related corticosteroid insufficiency (CIRCI) are not clear