Current opinion on the regulation of small intestinal magnesium absorption

Magnesium(Mg^(2+))has an important role in numerous biological functions,and Mg^(2+)deficiency is associated with several diseases.Therefore,adequate intestinal absorption of Mg^(2+)is vital for health.The small intestine was previously thought to absorb digested Mg^(2+)exclusively through an unregulated paracellular mechanism,which is responsible for approximately 90%of total Mg^(2+)absorption.Recent studies,however,have revealed that the duodenum,jejunum,and ileum absorb Mg^(2+)through both transcellular and paracellular routes.Several regulatory factors of small intestinal Mg^(2+)uptake also have been explored,e.g.,parathyroid hormone,fibroblast growth factor-23,apical acidity,proton pump inhibitor,and pH-sensing channel and receptors.The mechanistic factors underlying proton pump inhibitor suppression of small intestinal Mg^(2+),such as magnesiotropic protein dysfunction,higher mucosal bicarbonate secretion,Paneth cell dysfunction,and intestinal inflammation,are currently being explored.The potential role of small intestinal microbiomes in Mg^(2+)absorption has also been proposed.In this article,we reviewed the current knowledge on the mechanisms and regulatory factors of small intestinal Mg^(2+)absorption.

Influence of nitrogen and magnesium doping on the properties of ZnO films

Undoped ZnO and doped ZnO films were deposited on the MgO（111） substrates using oxygen plasma-assisted molecular beam expitaxy. The orientations of the grown ZnO thin film were investigated by in situ reflection high-energy electron diffraction and ex situ x-ray diffraction（XRD）. The film roughness was measured by atomic force microscopy, which was correlated with the grain sizes determined by XRD. Synchrotron-based x-ray absorption spectroscopy was performed to study the doping effect on the electronic properties of the ZnO films, compared with density functional theory calculations.It is found that, nitrogen doping would hinder the growth of thin film, and generate the NOdefect, while magnesium doping promotes the quality of nitrogen-doped ZnO films, inhibiting（N_2）Oproduction and increasing nitrogen content.

Microstructure and microwave absorption properties of MWCNTs reinforced magnesium matrix composites fabriccated by FSP

Multiwall carbon nanotubes(MWCNTs) reinforced magnesium matrix(MWCNTs/Mg) composites were successfully fabricated by friction stir processing(FSP). Microstructure and microwave-absorption properties of WCNTs/Mg composites are studied. The results show that with increasing the MWCNTs content to 7.1% in volume fraction,the agglomeration of MWCNTs is found in the WCNTs/Mg composites. The addition of MWCNTs has little effect on microwave-absorption properties. With increasing the frequency from 2 GHz to 18 GHz,the microwave absorption of the composites decreases. Compared with the absorption loss of the MWCNTs,the reflection loss of base material takes the most part of the loss of the microwave,and the increase of the reflection loss can promote electromagnetic shielding properties of the composites. Moreover,the electromagnetic shielding properties of the composites are less than-85 d B in the lower frequency range from 0.1 MHz to 3 GHz. With increasing the content of MWCNTs,the electrical conductivity of the composites is decreased,and the electromagnetic shielding properties is slightly enhanced.