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Résumé -Séparation des asphaltènes par nano et ultrafiltration -Comparaison avec la méthode de floculation -Les asphaltènes contiennent une multitude de composés très polydisperses en terme de composition chimique et en terme de taille, ce qui rend leurs propriétés et leur comportement difficiles à décrire. Afin de mieux caractériser ces espèces, une voie envisagée est de réduire cette polydispersité. Dans cette étude, nous avons proposé deux approches différentes : la floculation (en faisant appel à des solvants et anti-solvants) et la filtration membranaire. Les différentes fractions d'asphaltènes obtenues par chaque méthode sont caractérisées en utilisant les techniques suivantes : la chromatographie d'exclusion stérique (SEC), l'analyse élémentaire, la résonance magnétique nucléaire (RMN-13 C) et la diffusion des rayons X aux petits angles (SAXS). Il a été montré que des agrégats asphalténiques de différentes tailles peuvent être séparés par la filtration membranaire d'une façon plus sélective qu'en utilisant la méthode conventionnelle de floculation. Comparés aux grands agrégats, les petits agrégats asphalténiques présen-tent une aromaticité plus faible et un caractère aliphatique plus élevé. Leurs chaînes alkyles semblent être également plus courtes et plus ramifiées. De plus, l'analyse élémentaire indique que les plus petits asphaltènes contiennent une concentration inférieure en métaux et sont préférentiellement enrichis en vanadium plutôt qu'en nickel. Les effets de la température et de la concentration sur la performance de la séparation membranaire sont étudiés. Abstract

ABSTRACT.Purpose: To determine the age-and sex-specific prevalence of early and late age-related macular degeneration (AMD) in two Portuguese population-based samples and to identify its risk factors. Population: A population of 6023 adults aged ≥55 years was recruited from two Portuguese primary healthcare units in the central region of Portugal -one from a coastal (n = 3000) and another from an inland town (n = 3023). Methods: Cross-sectional population-based study. Participants were enrolled in the two locations between August 2009 and October 2013. Responders underwent standardized interviews and ophthalmologic examination, including digital fundus imaging. All fundus photographs were graded according to an International Classification and Grading System. The main outcome measures consisted of age-and sex-adjusted prevalence of early and late AMD. Potential epidemiologic risk factors were also evaluated using logistic regression analysis. Results: Of the 6023 subjects enrolled, 5996 had gradable fundus images and were included in the analysis. The crude prevalence of early and late AMD was 6.99 and 0.67%, respectively, for the coastal town and 15.39 and 1.29% for the inland town. Age-and sex-adjusted prevalence of any AMD for the Portuguese population was 12.48% (95% CI: 11.61-13.33) with late AMD accounting for 1.16% (95% CI: 0.85-1.46). Neovascular AMD (NV-AMD) and geographic atrophy (GA) accounted for 0.55% (95% CI: 0.36-0.75) and 0.61% (95% CI: 0.37-0.84) of individuals, respectively. After adjusting for possible confounding factors, prevalence of early and late AMD increased with increasing age (OR = 1.35; 95% CI: 1.23-1.49 for early and OR = 3.01; 95% CI: 2.22-4.08 for late AMD, per each decade of age increase, p < 0.001). After adjustment for age, sex, family history, smoking history, hypertension, diabetes and BMI, subjects from the inland town presented a significantly higher OR of early and late AMD than subjects from the coastal town (OR = 2.57, 95% CI: 2.12-3.12, p < 0.001 for early and OR = 2.06, 95% CI: 1.07-3.95, p = 0.029 for late AMD). Conclusions: The prevalence of early and late AMD in this Portuguese population was similar to other large-scale population-based cohorts. After controlling for confounders, age and study site of inclusion were significant independent predictors for both early and late forms of the disease. Further analysis will be needed to completely unravel the underlying reasons for this difference regarding geographic location.

Cystinosis, a rare autosomal recessive disease caused by intracellular cystine accumulation, occurs in an estimated 1/100,000–200,000 live births. Ocular non-nephropathic cystinosis is typically diagnosed during adulthood, when patients present with corneal crystal deposition and no systemic involvement. Due to the rarity of the condition, diagnosis is often delayed and can have a significant impact on the overall prognosis of the disease. Early diagnosis is therefore imperative to ensure successful treatment and improve quality of life, as most of its clinical manifestations can be prevented or delayed. Early detection strategies and practical approaches for the ocular management of cystinosis were discussed during the Ophthalmology Cystinosis Forum, a 1-day meeting held in Berlin, Germany during June 2017. Recommendations for early detection comprise ophthalmic assessment, including self- and clinician-assessed recording of photophobia, and visual acuity, slit-lamp examination and tonometry ophthalmic examinations. In vivo confocal microscopy and anterior segment optical coherence tomography were highlighted as valuable techniques in evaluating cystine crystals in the cornea, in vivo and non-invasively. The mainstay of ocular cystinosis treatment is the cystine-depleting aminothiol cysteamine. Indeed, early treatment with and strict adherence to cysteamine therapy has a considerable impact on the long-term prognosis of ocular cystinosis. In rare diseases such as ocular cystinosis, standardised guidelines and recommendations for detection, patient care and follow-up assessments are essential. Such guidelines provide a support tool for healthcare professionals caring for ocular cystinosis patients. Multidisciplinary teams (MDTs) are essential for delivering gold standard care and improving quality of life for patients and their families. This review paper highlights current early detection policies, clinical treatment strategies and practical approaches for the ocular management of cystinosis, including implementing a cystinosis MDT. Additionally, discussions of the Ophthalmology Cystinosis Forum held in 2017 are summarised.FundingOrphan Europe.Plain Language SummaryPlain language summary available for this article.

The most abundant metals in heavy feedstocks, vanadium and nickel, are mainly concentrated in the asphaltenes fraction, a petroleum fraction which precipitates in presence of paraffinic solvents. Characterization of vanadium and nickel complexes is therefore important to the development of demetallation and conversion strategies used to process heavy crudes. The dependence of vanadyl structures on the geographic origin of feedstocks and their evolution during hydroprocessing in an ebullated-bed pilot unit were studied. The aim of this contribution is to assess the possibilities of the EPR spectroscopy to provide information on the structure of the vanadyl species. This work shows that pulsed EPR spectroscopy is a powerful technique that allows to distinguish several types of environments of vanadium species, amongst which are porphyrinic ligands, even in very complex samples such as C 7 asphaltenes from heavy feedstocks.

This work concerns the study of sediment formation in ebullated-bed hydroconversion of vacuum residues and investigates ways to avoid their formation at high conversion operation. Tests were carried out in a bench-scale unit at high temperature using a vacuum residue feedstock. Feeds and effluents were characterized to follow sediment formation, as well as conversion, yield structure, and hydrotreating performances. It was found that co-processing a vacuum residue feedstock with low amounts (<15 wt %) of heavy cycle oil from a fluidized catalytic cracking (FCC) unit can significantly improve the stability of the unconverted effluents. A detailed characterization of feedstock and products was carried out to understand the stabilization mechanisms. The effect of heavy cycle oil (HCO) on sediment reduction was attributed to the polycondensed tri-, tetra-, and pentaaromatics. It was also found that these species do not affect the hydroconversion performances and are refractory to conversion.