Some factors affecting magnesium uptake by citrus leaves : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University, Palmerston North, New Zealand

Pineapple sweet orange seedlings and rooted leaf bud cuttings of Meyer lemons were used to investigate the effects of some of the factors affecting magnesium uptake by leaves. Magnesium was determined by thiazole yellow method of Drosdoff and Nearpass (1948) and uptake was usually measured 24 hours after spray treatment. It was shown that the addition of wetting agents to magnesium nitrate sprays significantly increased the uptake of magnesium by leaves. The nonionic wetter (Terric GN9) at the very low (0.01% a.i.) and high (0.08 - 0.1% a.i.) concentrations did. not affect magnesium uptake, whereas at intermediate concentrations, magnesium uptake was increased. Use of the humectant glycerine at 1 or 2 percent significantly increased the uptake of magnesium by leaves, compared with sprays to which no glycerine was added, but had no beneficial effect over sprays which contained a nonionic wetter (Terric GN9). Magnesium uptake by leaves grown in 100% relative humidity for two weeks was greater than the uptake by leaves grown in average relative humidity of 71% Both morning and the evening sprays resulted in greater uptake of magnesium by leaves, compared with afternoon sprays. A significant increase in leaf magnesium concentration occurred after 2 hours of a magnesium nitrate spray application. Leaf magnesium concentration rose steeply for 24 hours after spraying, thereafter remaining constant. (Because it was not possible to measure the degree of magnesium transport out of the leaf, it is not clear whether magnesium uptake, in fact, stopped after 24 hours). Of the three magnesium salts used, magnesium nitrate and magnesium chloride sprays resulted in greater magnesium uptake by leaves, compared with magnesium sulphate sprays. Uptake varied with the concentration of magnesium in. the leaves. The lower the concentration of magnesium in the leaves, the loss the uptake of magnesium by leaves, and the higher the concentration of magnesium, the higher the uptake of magnesium. Leaf nitrogen also affected uptake of magnesium by leaves. High leaf nitrogen (2.92% of dry weight) resulted in greater uptake of magnesium than the low leaf nitrogen (2.08% of dry weight). The average increase in the concentration of magnesium in the leaves of low nitrogen plants was 0.09% of dry weight, while in leaves of high nitrogen plants the increase was 0.19%. Thus the increase in the % leaf concentration of magnesium in the high nitrogen plants was double that of the low nitrogen plants. This may be a direct effect of the low leaf nitrogen or an indirect one due to the induced low leaf magnesium in those plants

Higher dietary magnesium intake and higher magnesium status are associated with lower prevalence of coronary heart disease in patients with Type 2 Diabetes

In type 2 diabetes mellitus (T2D), the handling of magnesium is disturbed. Magnesium deficiency may be associated with a higher risk of coronary heart disease (CHD). We investigated the associations between (1) dietary magnesium intake; (2) 24 h urinary magnesium excretion; and (3) plasma magnesium concentration with prevalent CHD in T2D patients. This cross-sectional analysiswas performed on baseline data fromthe DIAbetes and LifEstyle Cohort Twente-1 (DIALECT-1, n = 450, age 63 � 9 years, 57%men, and diabetes duration of 11 (7–18) years). Prevalence ratios (95% CI) of CHD by sex-specific quartiles of magnesium indicators, as well as by magnesium intake per dietary source, were determined using multivariable Cox proportional hazard models. CHD was present in 100 (22%) subjects. Adjusted CHD prevalence ratios for the highest compared to the lowest quartiles were 0.40 (0.20, 0.79) for magnesium intake, 0.63 (0.32, 1.26) for 24 h urinary magnesium excretion, and 0.62 (0.32, 1.20) for plasma magnesium concentration. For every 10 mg increase of magnesium intake from vegetables, the prevalence of CHD was, statistically non-significantly, lower (0.75 (0.52, 1.08)). In this T2D cohort, higher magnesium intake, higher 24 h urinary magnesium excretion, and higher plasma magnesium concentration are associated with a lower prevalence of CHD

Magnesium and magnesium alloys as degradable metallic biomaterials

Drawbacks associated with permanent metallic implants lead to the search for degradable metallic biomaterials. Magnesium has been considered as it is essential to bodies and has a high biodegradation potential. For magnesium and its alloys to be used as biodegradable implant materials, their degradation rates should be consistent with the rate of healing of the affected tissue, and the release of the degradation products should be within the body's acceptable absorption levels. Conventional magnesium degrades rapidly, which is undesirable. In this study, biodegradation behaviours of high purity magnesium and commercial purity magnesium alloy AZ31 in both static and dynamic Hank's solution have been systematically investigated. The results show that magnesium purification and selective alloying are effective approaches to reduce the degradation rate of magnesium. In the static condition, the corrosion products accumulate on the materials surface as a protective layer, which results in a lower degradation rate than the dynamic condition. Anodised coating can significantly further reduce the degradation rate of magnesium. This study indicates that magnesium can be used as degradable implant materials as long as the degradation is controlled at a low rate. Magnesium purification, selective alloying and anodised coating are three effective approaches to reduce the rate of degradation

Improved magnesia for thermal control coatings

Formation of radiation-generated color centers using single crystals of magnesium oxide is discussed. Crystal structure of magnesium oxide is described. Chemical processes used to produce magnesium oxide with desired color center kinetics are presented. Proton irradiation of magnesium oxide crystals was conducted to determine lattice defects

A study on factors affecting the degradation of magnesium and a magnesium-yttrium alloy for biomedical applications.

Controlling degradation of magnesium or its alloys in physiological saline solutions is essential for their potential applications in clinically viable implants. Rapid degradation of magnesium-based materials reduces the mechanical properties of implants prematurely and severely increases alkalinity of the local environment. Therefore, the objective of this study is to investigate the effects of three interactive factors on magnesium degradation, specifically, the addition of yttrium to form a magnesium-yttrium alloy versus pure magnesium, the metallic versus oxide surfaces, and the presence versus absence of physiological salt ions in the immersion solution. In the immersion solution of phosphate buffered saline (PBS), the magnesium-yttrium alloy with metallic surface degraded the slowest, followed by pure magnesium with metallic or oxide surfaces, and the magnesium-yttrium alloy with oxide surface degraded the fastest. However, in deionized (DI) water, the degradation rate showed a different trend. Specifically, pure magnesium with metallic or oxide surfaces degraded the slowest, followed by the magnesium-yttrium alloy with oxide surface, and the magnesium-yttrium alloy with metallic surface degraded the fastest. Interestingly, only magnesium-yttrium alloy with metallic surface degraded slower in PBS than in DI water, while all the other samples degraded faster in PBS than in DI water. Clearly, the results showed that the alloy composition, presence or absence of surface oxide layer, and presence or absence of physiological salt ions in the immersion solution all influenced the degradation rate and mode. Moreover, these three factors showed statistically significant interactions. This study revealed the complex interrelationships among these factors and their respective contributions to degradation for the first time. The results of this study not only improved our understanding of magnesium degradation in physiological environment, but also presented the key factors to consider in order to satisfy the degradation requirements for next-generation biodegradable implants and devices

Magnesium-Containing Slurry as Technogenic Alternative Raw Material for Magnesium Oxychloride Cement

It has been shown experimentally that a waste of magnesium metal production is a realistic alternative to naturally occurring cement raw materials. The waste is the carnallite slurry forming during the chlorination stage. The slurry contains magnesium oxide (MgO) and magnesium chloride (MgCl2) in a mass ratio close to their optimal ratio when preparing Sorel cement. It is found that the magnesium oxide in the slurry is highly reactive. MgO extracted from the slurry and MgCl2 solution are mixed forming homogeneous magnesium oxychloride cement (MOC) paste in which bonding crystalline structures typical for Sorel cement are formed during hardening. © 2019 Published under licence by IOP Publishing Ltd

Maternal and neonatal serum magnesium concentrations in neural tube defects pregnancies in Gorgan (North of Iran) - A case control study

Objective: Neural tube defects (NTD) comprise a group of congenital malformations that include spinabifida, anencephaly and encephalocele. Previous studies have reported the embryotoxic and teratogenic effects of Magnesium deficiency in animal models. Therefore, this study was conducted to determine an association between Magnesium deficiency and neural tube defects in Northern Iran, which was reported to have a high prevalence of neural tube defects. Methods: This hospital based case control study was conducted on 13 mothers with newborns having neural tube defects and 35 healthy mothers as controls in Northern Iran during 2005-2006. Serum Magnesium was measured by spectrophotometery. Results: Serum Magnesium levels in mothers with NTD affected newborns and in mothers with healthy newborns were 1.5±0.6 and 1.32±0.3 micromol/litter, respectively. Overall, 46.2% mothers in the case group and 48.6 % mothers in the control group had Magnesium deficiency. Logistic regression analysis showed no association between the presence of NTD and Magnesium deficiency (OR =0.9, 95% Cl: 0.2-3.9, p=0.88). Serum Magnesium levels in newborns with NTD and healthy normal newborns were 1.4±0.6 micromol/litter and 1.3±0.4 micromol/litter, respectively. Overall, 30.8% newborns in the case group and 37.1 % newborns in the control group had Magnesium deficiency. Logistic regression analysis showed no association between the presence of NTD and Magnesium deficiency (OR =0.8, 95% Cl: 0.1-3.4 p=0.68). Conclusion: The present study did not find any association between the occurrence of NTD and Magnesium deficiency

Vapor condensation process produces slurry of magnesium particles in liquid hydrocarbons

Vapor condensation apparatus produces a physically stable, homogeneous slurry of finely divided magnesium and liquid hydrocarbons. The magnesium is vaporized and the resultant vapor is cooled rapidly with a liquid hydrocarbon spray, which also serves as the dispersing medium for the condensed magnesium particles

Magnesium Oxide Use as a Pigment in Coating Formulations

The objective of this project was to evaluate the performance of magnesium oxide as a possible pigment for use in paper coatings. The use of magnesium oxide as a pigment in coatings is not currently nor has it ever been practiced in a mill situation. The principle goal of using magnesium oxide was to increase brightness and opacity in coatings at the level of performance found with titanium dioxide at a far lower cost. The evaluation was done of the basis of rheological performance as well as optical testing. Coatings of various levels of magnesium oxide and titanium dioxide were applied to a recycled base sheet similar to that of a topliner of a coated board. The coatings were applied on the Dow Laboratory coater at low speeds with a blade applicator. All coatings were evaluated by the Brookfield viscometer as well as the Hercules high shear viscometer before coating was done so coating could be analyzed at similar viscosities. The results during experimentation have given the following conclusions. Some shear thinning occurred with the substitution of magnesium oxide for titanium dioxide at high shear rates. Dispersion without any dispersant caused rheological problems with the magnesium oxide. At similar coat weights, the optical objectives of the experiment were satisfied with these results: equal brightness with 100% substitution of magnesium oxide for titanium dioxide, higher gardner gloss with magnesium oxide than titanium dioxide, equal opacity for pure substitution, with optimum opacity coming at an even 50/50 split of the pigments, improved smoothness with total replacement, as measured by Parker Print Surf, and a higher ink absorbtivity in the magnesium oxide coatings due to less dense coating structure containing more pores. Overall, the use of magnesium oxide is warranted if the problems of dispersion and coater rheology are overcome or managed with the use of dispersant. The unknowns to be explored with further study are the runnability on a machine coater and the abrasiveness of the magnesium oxide on equipment