Search results for "CALCIUM"

A pilot-plant for the selective recovery of magnesium and calcium from waste brines

2021

Abstract The problem of brines disposal has raised great interest towards new strategies for their valorisation through the recovery of minerals or energy. As an example, the spent brine from ion exchange resins regeneration is often discharged into rivers or lakes, thus impacting on the process sustainability. However, such brines can be effectively reconcentrated, after removal of bivalent cations, and reused for the resins regeneration. This work focuses on developing and testing a pilot plant for selective recovery of magnesium and calcium from spent brines exploiting a novel proprietary crystallization unit. This is part of a larger treatment chain for the complete regeneration of the …

SELECTIVE CRYSTALLISATION OF MAGNESIUM AND CALCIUM HYDROXIDES FROM INDUSTRIAL WASTE BRINES: A PILOT STUDY

2021

In the last years, a rising interest has been focused on the valorization of waste brines from industrial processes, such as desalination plants. In most current scenarios, waste brines are disposed directly, or after being treated, into a receiving water bodies, often causing environmental concerns and, more importantly, renouncing to the possibility of using such a waste as source of valuable raw materials. In fact, these brines are typically rich in useful salts and minerals, whose recovery can increase the environmental and economical sustainability of the industrial process [1-2]. The ZERO BRINE EU-H2020 project aims at the development of technologies for the recovery of salts, mineral…

Therapeutic management of elderly hypertensives with concomitant ischaemic heart disease.

1992

CHARACTERISTICS OF ELDERLY HYPERTENSIVES: Hypertension is most prevalent in older patients and is associated with increasing morbidity and mortality with age. Elderly hypertensives often suffer from concomitant diseases, such as ischaemic heart disease, caused by age-induced modifications to the cardiovascular system, haemodynamic function and neurohormone activity. THERAPEUTIC MANAGEMENT: Therapeutic management of elderly hypertensives with concomitant ischaemic heart disease must take account of the pharmacodynamic and pharmacokinetic changes that occur in older subjects and drugs should be selected for their efficacy in both diseases. Since elderly subjects often metabolize drugs more sl…

Polymorphonuclear leukocyte membrane fluidity and cytosolic Ca2+ content at baseline and after activation in essential hypertension

2004

Obiective: To examine in essential hypertension (EH) the polymorphonuclear leukocyte (PMN) membrane fluidity and cytosolic Ca2+ content at baseline and after in vitro activation. Subjects and methods: In 45 hypertensive subjects (27 men and 18 women; mean age 45.8 +/- 11.3 years) we evaluated the PMN membrane fluidity, obtained by labeling PMNs with 1-[4-(trimethyImino)phenyl]-6phenyl-1,3,5-hexatriene (TMA-DPH) and considering the TMA-DPH polarization degree, inversely related to the membrane fluidity, and the PMN cytosolic Ca2+ content, obtained by marking PMNs with Fura 2-AM. These PMN parameters were examined at baseline and after in vitro activation (prolonged for 5 min) with two agents…

Analisi dei fattori di rischio dell'ipoparatiroidismo transitorio e definitivo nei pazienti sottoposti a tiroidectomia

2017

Obiettivi. Con questa revisione della letteratura ci proponiamo di valutare quali sono i fattori che possono essere valutati nei pazienti da sottoporre a tiroidectomia ai fini di una migliore gestione preoperatoria e post-operatoria dell’ipoparatiroidismo transitorio e definitivo. Discussione. L’ipoparatiroidismo transitorio è una complicanza potenzialmente grave che include una vasta gamma di segni e sintomi che permane solo per poche settimane dopo l’intervento chirurgico. L’ipoparatiroidismo definitivo si verifica quando è necessario un trattamento medico per un periodo maggiore di 12 mesi. I fattori di rischio che ne possono influenzare l’insorgenza in seguito ad interventi di tiroidect…

Calcium intake in the Mediterranean region

2014

A deficiency in calcium intake, is considered an important risk factor for the development of osteoporosis. Since the human body cannot produce calcium, individuals are recommended to maintain an adequate daily intake. The aim of the “Calcium Intake in the Mediterranean Region” Study is to evaluate the mean calcium intake in men and women between 40 and 80 residing in various areas of the Mediterranean basin. Enrolled subjects have been asked to fill out a self-administered questionnaire to evaluate the mean daily calcium intake from food, principle risk factors for osteoporosis were registered. A dual- energy X-ray absorptiometry (DEXA) has also been carried out to evaluate bone mineral de…

Ca-score nella valutazione del paziente a rischio intermedio di eventi cardiaci acuti: modificazioni del profilo di rischio

2008

Molecular Mechanism of Spicule Formation in the Demosponge Suberites domuncula: Silicatein-Collagen-Myotrophin

2003

In living organisms four major groups of biominerals exist: (1) iron compounds, which are restricted primarily to Prokaryota; (2) calcium phosphates, found in Metazoa; (3) calcium carbonates, used by Prokaryota, Protozoa, Plantae, Fungi and Metazoa and (4) silica (opal) present in sponges and diatoms (reviewed in: Bengtson 1994; Baeuerlein 2000). It is surprising that the occurrence of silica as a major skeletal element is restricted to some Protozoa and to sponges (Porifera). The element silicon (Si) contributes to 28% of the earth crust and is - after oxygen - the second most abundant element on earth (Windholz 1983).

Al-27 and Si-29 Solid-State NMR Characterization of Calcium-Aluminosilicate-Hydrate

2012

International audience; Calcium silicate hydrate (C-S-H) is the main constituent of hydrated cement paste and determines its cohesive properties. Because of the environmental impact of cement industry, it is more and more common to replace a part of the clinker in cement by secondary cementitious materials (SCMs). These SCMs are generally alumina-rich and as a consequence some aluminum is incorporated into the C-S-H. This may have consequences on the cohesion and durability of the material, and it is thus of importance to know the amount and the location of Al in C-S-H and what the parameters are that control these features. The present paper reports the Si-29 and Al-27 MAS NMR analyses of …

The structure and stoichiometry of C-S-H

2004

Abstract This review relates to the models describing the structural evolution of calcium silicate hydrate (C-S-H) at the crystal–chemical level as a function of composition in terms of calcium to silicon ratio. The different models are compared and discussed in the light of recent spectroscopic and microscopic data. Taking into account the structure and the morphological properties of C-S-H, a surface reaction thermodynamic model has been proposed and discussed to predict and correlate the chemical and structural evolution of C-S-H with solution chemistry.