Sommario
Denosumab (Dmab) è un potente farmaco anti-riassorbitivo impiegato per il trattamento dell’osteoporosi al dosaggio di 60 mg sottocute ogni sei 6 mesi. A differenza dei bisfosfonati (BPs), ...Dmab non si accumula nella matrice ossea e, in caso di ritardo o interruzione delle somministrazioni, è noto un effetto
rebound
sul turnover osseo, che si traduce in una rapida perdita di
Bone Mineral Density
(BMD) e in un aumento del rischio di fratture vertebrali, spesso cliniche e multiple. Data la rilevanza clinica di tale fenomeno, si rende quindi necessario per gli specialisti dedicati al trattamento delle patologie osteometaboliche conoscere nel dettaglio quali sono le evidenze attualmente disponibili, nonché le principali raccomandazioni relative alla gestione della terapia anti-osteoporotica con Dmab, con particolare attenzione alla sua interruzione (programmata o accidentale), su cui si focalizzerà la presente Rassegna.
Türkiye, yenilenebilir enerji kaynaklarına ve yeni enerji teknolojilerine yatırım yaparak fosil yakıtlara bağımlılığını azaltmayı hedeflemektedir. Rüzgâr ve güneş enerjisi santrallerinin sayısını her ...geçen gün arttırmakta ve bu santrallerin inşasında yerli üretimi teşvik etmektedir. Trafikte elektrikli araçların sayısını arttırmayı planlamakta ve bu kapsamda yerli elektrikli otomobilini üretmektedir. Bu teknolojilerin yapısından kaynaklı olarak Türkiye’nin hammadde ihtiyacı farklılaşmakta ve artmaktadır. Rüzgâr türbinleri, güneş panelleri, elektrikli araçlar ve enerji depolama birimlerinin üretimi için doğada az miktarda bulunan ve bu nedenle nadir toprak elementleri olarak adlandırılan hammaddelerin yanı sıra lityum, kobalt, bakır, nikel, germanyum, neodimyum gibi kritik minerallere ihtiyaç duymaktadır. Ancak bu kritik minerallerin tedariki, küresel ölçekte artan talep nedeniyle giderek zorlaşmaktadır. Kritik mineraller, diplomatik krizlere neden olmakta ve yeni enerji jeopolitiğinin öznesi haline gelmektedir. Türkiye, yenilenebilir enerji alanındaki hedefleriyle ve yatırımlarıyla mineral arz riski yaşaması kuvvetle muhtemel ülkelerden biridir. Bu kapsamda çalışmada Türkiye’nin enerji dönüşümü ele alınmaktadır ve kritik minerallerin bu dönüşümdeki rolü değerlendirilmektedir. Kritik minerallerin Türkiye’nin enerji güvenliğine etkisini tartışılmaktadır.
La béraunite, la fluorapatite et le xénotime-(Y) sont trois espèces nouvelles observées dans l'indice phosphaté de Haut-le-Wastia dont la minéralogie avait été initialement décrite en 1985 par R. Van ...Tassel. La présence de xénotime-(Y) en inclusion dans la fluorapatite et contenant un peu d'uranium, est une donnée nouvelle à considérer pour rendre compte de la radioactivité observée dans les couches de passage Viséen-Namurien du bassin de Dinant.
Beraunite, fluorapatite and xenotime-(Y) are three new species for the phosphate spot in Haut-le-Wastia. A small crystal of Xenotime-(Y) included in fluorapatite is observed with some amounts of uranium and it's a new data to understand the radioactivity of the Visean-Namurian shales in the Dinant margin.
The synthesis of 240 lead isotopes analyses, measured on Moroccan ore deposits of Ediacarian to Neogene ages located in all geotectonic domains of Morocco allows a global reflection on the ...metallogeny of Morocco. The isotopic compositions vary widely, from 17.738 (Bou Skour) to 18.905 (Draa Sfar) for the 206Pb/204Pb ratio, and from 15.521 to 15.706 for the 207Pb/204Pb ratio. The source of lead in the studied deposits is located in the upper continental crust, except for those in the Anti-Atlas (Bou Skour, Imiter, etc.) and some in the High Atlas (Azegour) with a clear mantellic contribution. Isotopic variations noted at the scale of a district result either from the presence of several superimposed hydrothermal events calling upon different local sources as at Tighza, or from a single event disturbed by the segmentation of a volcanosedimentary basin, as for the Jebilet and Guemassa ore deposits. At the scale of the deposit (Draa Sfar, Bou Skour), isotopic variations result from the superposition of several hydrothermal events each with their own lead and associated metals. Overall, we can distinguish three generations of lead incorporated successively into the Moroccan geological basement by magmatism and/or hydrothermalism, characterized by their 206Pb/204Pb ratios: 17.74–17.90 (Panafrican), 18.10–18.40 (Hercynian) and 18.75–18.90 (Alpine). Panafrican lead is present in the Anti-Atlas, and very locally in the Meseta (Bouznika), and feeds in part on the mafic magmatism of Gondwana. Hercynian lead is the most represented and displays a definitive rupture in the source of metals, which is now exclusively crustal. It invades all Moroccan areas, including the Anti-Atlas, where it re-mobilizes and mixes with the panafrican lead. Alpine lead, more discreet, marks out the large scarf going from Agadir to Nador which traces on the surface the mantle plume of the Canaries and accompanies a Neogene magmatism which may also have acted as a simple engine remobilizing Hercynian lead, in particular to form MVT deposits from Touissit. The Hercynian and Alpine lead influxes are partly responsible for resetting the Neoproterozoic mineralization, as at Bou Azzer or Imiter. In the Sawkins’s model, lead isotopic results support successive remobilisations of lead stored in primary and secondary tanks, as well as inheritance phenomena. Finally, the good transfer of the isotopic signature of lead from ore deposits to surface gossans shows that the isotopic geochemistry of lead is a useful tool for mineral exploration in Morocco, moreover for stratiform polymetallic sulphides ore deposits of Hajar type.
La symétrie des minéraux Frédéric Hatert
Bulletin de la Société royale des sciences de Liège,
01/2014, Letnik:
83
Journal Article
Recenzirano
Odprti dostop
Cet exposé présente la symétrie des minéraux à l’échelle macroscopique, où ils peuvent être classés en 7 systèmes cristallins, divisés eux-mêmes en 32 classes cristallines. À l’échelle atomique, la ...translation est possible, ce qui induit la présence de plans de glissements et d’axes hélicoïdaux, aboutissant finalement aux 230 groupes spatiaux. La symétrie du cristal se répercute au niveau de ses propriétés physiques ; les propriétés optiques et électriques sont envisagées dans le cadre de cet exposé. Optiquement, la symétrie est supérieure à la symétrie géométrique : les minéraux cubiques présentent une isotropie optique parfaite. Les propriétés de piézoélectricité et de pyroélectricité sont rendues possibles par l’absence de centre de symétrie dans les minéraux considérés.
This paper describes the symmetry of minerals at a macroscopic scale, where they can be classified in 7 crystal systems and 32 crystal classes. At the atomic scale, translation becomes possible, leading to the existence of glide planes and screw axes. The symmetry of crystal structures can be classified in 230 space groups. Symmetry also governs physical properties of minerals, as for example optical and electrical properties. The optical symmetry is higher than geometrical symmetry, thus explaining why cubic minerals show a perfect optical isotropy. Piezoelectricity and pyroelectricity properties are incompatible with the presence of a symmetry centre in minerals.
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