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

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

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

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

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

Lightweight magnesium-lithium alloys show promise

Evaluation tests show that magnesium-lithium alloys are lighter and more ductile than other magnesium alloys. They are being used for packaging, housings, containers, where light weight is more important than strength

Effects of magnesium with or without boron on headshaking behavior in horses with trigeminal-mediated headshaking.

BackgroundOral administration of magnesium and boron might have a beneficial effect on headshaking behavior in horses.ObjectiveEvaluate the effects of oral magnesium alone or in combination with boron on headshaking behavior in affected horses.AnimalsTwelve geldings (6 healthy controls and 6 affected).MethodsProspective randomized controlled dietary trial over 42 days in 12 horses (6 horses diagnosed with trigeminal-mediated headshaking and 6 unaffected healthy controls). All horses received a hay diet and were randomized into 3 treatment groups: pelleted feed combination (PF), pelleted feed combination with magnesium (M), and pelleted feed combination with magnesium-boron (MB) with a week washout of hay only between treatments. Headshaking behavior and biochemical blood variables were assessed at baseline (hay only) and then after each week of supplementation.ResultsAll 3 diet interventions increased blood ionized and total magnesium. Groups M and MB further increased Mg2+ when compared to PF. Horses receiving treatments had a significant reduction in headshaking behavior, as measured by incidence rate ratio (IRR), when compared to unsupplemented hay diet (44% for PF, IRR, 0.558; CI, 0.44, 0.72; P < .001; 52% for M, IRR, 0.476; CI, 0.37, 0.62; P < .001; and 64% for MB, IRR, 0.358; CI, 0.27, 0.48; P < .001).Conclusions and clinical importanceMagnesium in combination with boron had the greatest decrease in headshaking. Oral supplementation with magnesium or magnesium in combination with boron should be considered in horses affected with headshaking

Evolution of electronic and ionic structure of Mg-clusters with the growth cluster size

The optimized structure and electronic properties of neutral and singly charged magnesium clusters have been investigated using ab initio theoretical methods based on density-functional theory and systematic post-Hartree-Fock many-body perturbation theory accounting for all electrons in the system. We have systematically calculated the optimized geometries of neutral and singly charged magnesium clusters consisting of up to 21 atoms, electronic shell closures, binding energies per atom, ionization potentials and the gap between the highest occupied and the lowest unoccupied molecular orbitals. We have investigated the transition to the hcp structure and metallic evolution of the magnesium clusters, as well as the stability of linear chains and rings of magnesium atoms. The results obtained are compared with the available experimental data and the results of other theoretical works.Comment: 30 pages, 10 figures, 3 table

Determination of hydroxyl content in impure magnesium oxide

Three-step thermal process quantitatively determines the hydroxyl content in samples of magnesium oxide. Analytical method can be adapted to large-scale production of hydroxyl-free magnesium oxide