Magnesium Oxide

Os utensílios culinários podem liberar alguns componentes inorgânicos durante a cocção de alimentos. A migração destes pode ser interessante desde que ocorra em quantidades adequadas às necessidades nutricionais do usuário ou não existam implicações toxicológicas. Foi avaliada a migração de metais (Fe, Mg, Mn, Cr, Ni, Ca, Zn, Pb, Cd e Hg) por espectrometria de emissão óptica, utilizando ácidos láctico e acético como simulantes do alimento em panelas de aço inoxidável (304), ferro fundido (GG-10) e pedra-sabão (esteatito), durante 15 cocções seqüenciais. O comportamento da migração durante cinco ciclos de estocagem a 22ºC também foi estudado. Análise de regressão dos dados revelou que, em função do uso, as panelas de inox apresentam redução da migração de metais de forma rápida, enquanto as de pedra-sabão mostram um declínio suave na migração, contrastando com as de ferro, que apresentam aumento na migração de Fe e Mn com o uso contínuo. Em nenhum utensílio foi observada a liberação de metais pesados, como Pb, Cd ou Hg.

To test different Cerec CAD/CAM system ceramic blocks, comparing mean flexural strength (sigma), Weibull modulus (m), and Weibull characteristic strength (sigma0) in an ISO standardized set-up. Following the recent ISO Standard (ISO 6872:2008), 11 types of ceramic blocks were tested: IPS e.max CAD MO, IPS e.max CAD LT and IPS e.max CAD HT (lithium disilicate glass-ceramic); In-Ceram SPINELL, In-Ceram Alumina and In-Ceram Zirconia (glass-infiltrated materials); inCoris AL and In-Ceram AL (densely sintered alumina); In-Ceram YZ, IPS e.max Zir-CAD and inCoris ZI (densely sintered zirconia). Specimens were cut out from ceramic blocks, finished, crystallized/infiltrated/sintered, polished, and tested in a three-point bending test apparatus. Flexural strength, Weibull characteristic strength, and Weibull modulus were obtained. A statistically significant difference was found (P < 0.001) among lithium disilicate glass-ceramic (sigma = 272.6 +/- 376.8 MPa, m = 6.2 +/- 11.3, sigma0 = 294....

Intro The empirical formula of a substance is the simplest whole number ratio of the number of atoms of each element in the compound. This can be calculated knowing the mass of each element and using this to calculate the number of moles of each element. In this experiment, you will carry out the following reaction: Magnesium + Oxygen  Magnesium Oxide Aim: To determine the empirical formula of Magnesium Oxide by burning magnesium. Hypothesis: The empirical formula will be MgO. Method: 1. Heat crucible + lid for five minutes and allow it to cool. (to remove water moisture for accurate mass) 2. Weigh crucible + lid. 3. Clean surface of a 5cm piece of Magnesium using steel wool. 4. Coil the Magnesium and place it in the crucible and record mass of Magnesium with crucible + lid. 5. Place crucible + contents onto a pipe clay triangle on top of a tripod. 6. Heat using blue flame until Magnesium burns. 7. Replace lid and heat for ten minutes. 8. Allow to cool then record mass. Results Object Mass (g) Crucible + lid 31.45g Crucible + lid + magnesium 31.62g Magnesium 0.17g Crucible + lid + magnesium oxide 31.70g Magnesium oxide 0.25g Oxygen 0.08g Steps to determine empirical formula of magnesium oxide: 1. Calculate moles of magnesium and oxygen. 2. Determine moles of magnesium to moles of oxygen. 3. Determine empirical formula of magnesium oxide. 4. Compare class results. 5. Compare actual ratio of practical. 6. Identify likely sources of error.

Three dimensional (3D) nano-structured crystals have received extensive attention for their superior properties over zero dimensional (0D), one dimensional (1D), or two dimensional (2D) nanomaterials in many areas. This review is generalized for the group of chalcogenide nanoflowers (NFs) by the synthetic techniques, such as solvothermal, wet chemical, sol-gel, surface oxidation, microwave, coating, electrochemical, and several other methods. The formation mechanism was also described for the purpose of opening up new food for thoughts to bring up new functionality of materials by tuning the morphology of crystals. The pH value or the template plays fundamental role in forming the nano-flowered structure. Moreover, the correlations between the surface area (SA), contact angle (CA), and the NFs are also discussed within the context. Here, we also discussed some patents relevant to the topic.

Magnesium sulfate is a complex fertiliser. This simple salt is a source of two nutrients – magnesium and sulfur. Magnesium sulfate occurs naturally as the mineral kieserite, MgSO 4 .H 2 O. This is dissolved in water (usually hot) and the purified sulfate is obtained by crystallisation from solution. Industrially, the crystals are centrifuged, dried and sieved. It is also prepared from magnesium oxide. This is obtained by the thermal decomposition of:  magnesium hydroxide (obtained from sea water): Mg(OH) 2 (s)  MgO(s) + H 2 O(g)  magnesium carbonate (from the ore magnesite): MgCO 3 (s)  MgO(s) + CO 2 (g) In either case, the oxide is reacted with sulfuric acid to produce magnesium sulphate: MgO(s) + H 2 SO 4 (aq)  MgSO 4 (aq)

Nervous disorders affect the central nervous system and cause progressive impairment of the nervous system. These disorders are usually incurable and debilitating and are characterised by a loss of nerve cell function. The most common chronic neurological disorders are Parkinson's disease (PD) and Alzheimer's disease (AD). Damage to the nerves usually progresses with age, as seen in AD and PD. Although Parkinson's and Alzheimer's diseases are multifactorial, exposure to heavy metals in neurons could increase the risk of developing these diseases. Metals are essential for maintaining cellular homeostasis and life. They have critical structural, catalytic, and regulatory functions in various types of proteins such as receptors, enzymes, and transporters. However, high and toxic concentrations of metals can stimulate the formation of reactive oxygen species (ROS) via a vicious cycle by impairing mitochondrial function, leading to a reduction in ATP and eventually cell death through an apoptotic mechanism. As life expectancy increases, individuals are certainly exposed to higher metal concentrations over a long period of time, which may lead to an increase in the incidence of neurological diseases. The aim of this study was to describe the effects of heavy metals such as manganese, lead and cadmium on the progression of the neurological diseases Parkinson's and Alzheimer's disease.

Steep rise of carbon dioxide level in the atmosphere is one of the main causes of global warming. This increase is ascribed to the fact that, since the beginning of industrial revolution, natural processes for CO2 sequestration are no more able to cope with the excess of CO2 produced by anthropogenic activities. In the recent years, research has been focused on defining artificial CO2 cycles to support the natural one. Element magnesium is used in this review as leitmotif to explore the majority of systems involved in any step of natural and artificial CO2 cycles (separation, storage, sequestration or recycling). Magnesium is in fact ubiquitous, being present in the mesosphere as global layers, on the Earth surface in the most important enzyme for carbon fixation (Rubisco) and in silicates, that constitute the most part of rocks, where CO2 is sequestered through natural weathering. For what concerns synthetic materials, zeolites, metal-supported particles and metal-organic frameworks are only few of the systems considered in literature. The intent of this review is to connect different fields of study to create an interdisciplinary review in the chemistry domain. Research outlooks are suggested for the different fields. In the end, a qualitative analysis of the advantages and limits of different processes and a rough estimate of their potential are given in terms of the time needed to reduce the atmospheric CO2 level. Although economical, political and health evaluations would be also necessary, this analysis indicates that forestation could be the possible winning solution in the short-middle term for lowering atmospheric CO2 concentration.

New compositions of bioactive glasses are proposed in the CaO–MgO–SiO2–Na2O–P2O5–CaF2 system. Mineralization tests with immersion of the investigated glasses in simulated body fluid (SBF) at 37°C showed that the glasses favour the surface formation of hydroxyapatite (HA) from the early stages of the experiments. In the case of daily renewable SBF, monetite (CaHPO4) formation competed with the formation of HA. The influence of structural features of the glasses on their mineralization (bioactivity) performance is discussed. Preliminary in vitro experiments with osteoblasts’ cell-cultures showed that the glasses are biocompatible and there is no evidence of toxicity. Sintering and devitrification studies of glass powder compacts were also performed. Glass-ceramics with attractive properties were obtained after heat treatment of the glasses at relatively low temperatures (up to 850°C).