The consumption of dietary supplements is widely spread and on the rise. These dietary supplements are generally used without prescriptions, proper counseling or any awareness of their health risk. The current study aimed at analyzing the metals in 33 samples of imported dietary supplements highly consumed by the Lebanese population, using 3 different techniques, to ensure the safety and increase the awareness of the citizen to benefit from these dietary supplements. Some samples had levels of metals above their maximum allowable levels (Fe: 24%, Zn: 33%, Mn: 27%, Se: 15%, Mo: 12% of samples), but did not pose any health risk because they were below permitted daily exposure limit and recommended daily allowance except for Fe in 6% of the samples. On the other hand, 34% of the samples had Cu levels above allowable limit where 18% of them were above their permitted daily exposure and recommended daily allowance. In contrast, all samples had concentration of Cr, Hg, and Pb below allowable limits and daily exposure. Whereas, 30% of analyzed samples had levels of Cd above allowable levels, and were statistically correlated with Ca, and Zn essential minerals. Similarly 62% of the samples had levels of As above allowable limits and As levels were associated with Fe and Mn essential minerals. Dietary supplements consumed as essential nutrients for their Ca, Zn, Fe and Mn content should be monitored for toxic metal levels due to their natural geochemical association with these essential metals to provide citizens the safe allowable amounts.

/pdf/evaluation-of-heavy-metals-content-in-dietary-supplements-in-19ypotvg2s.pdf

Evaluation of heavy metals content in dietary supplements in Lebanon

We present a full analysis of the contrast mechanisms for the detection of ferroelectric domains on all (x, y and z) faces of bulk single crystals using scanning force microscopy. The experiments were carried out with hexagonally poled lithium niobate to ensure access to a well-defined domain structure on every crystal face. The domain contrast can be attributed to three different mechanisms: (i) the thickness change of the sample due to an out-of-plane piezoelectric response (standard piezoresponse force microscopy), (ii) the lateral displacement of the sample surface due to an in-plane piezoresponse and (iii) the electrostatic tip–sample interaction at the domain boundaries caused by surface charges on the crystallographic y- and z-faces. A careful analysis of the movement of the cantilever with respect to its orientation relative to the crystallographic axes of the sample allows clear attribution of the observed domain contrast to the driving forces.

Contrast mechanisms for the detection of ferroelectric domains with scanning force microscopy

Information on the concentration of major, minor and trace elements in fruit juices is very important because the popularity of these beverages and the rate of their consumption have rapidly increased in the past 20 years. For the overwhelming majority of cases, the elemental analysis of fruit juices is carried out using spectrochemical analytical methods, which normally require samples of fruit juices to be prepared by decomposing their organic matrix and releasing elements in a form suitable for measurement. This review covers different aspects of the elemental analysis of fruit juices and the societal implications related to the presence of various elements in these beverages. We review in detail sample-preparation procedures executed before the elemental analysis together with calibration strategies used, and quality assurance and quality control of results.

Developments and strategies in the spectrochemical elemental analysis of fruit juices

We present a full analysis of the contrast mechanisms for the detection of ferroelectric domains on all faces of bulk single crystals using scanning force microscopy exemplified on hexagonally poled lithium niobate. The domain contrast can be attributed to three different mechanisms: i) the thickness change of the sample due to an out-of-plane piezoelectric response (standard piezoresponse force microscopy), ii) the lateral displacement of the sample surface due to an in-plane piezoresponse, and iii) the electrostatic tip-sample interaction at the domain boundaries caused by surface charges on the crystallographic y- and z-faces. A careful analysis of the movement of the cantilever with respect to its orientation relative to the crystallographic axes of the sample allows a clear attribution of the observed domain contrast to the driving forces respectively.

/pdf/contrast-mechanisms-for-the-detection-of-ferroelectric-3eatlpr59l.pdf

Contrast Mechanisms for the Detection of Ferroelectric Domains with Scanning Force Microscopy

Determination of phosphorus in food samples by X-ray fluorescence spectrometry and standard spectrophotometric method

X-Ray fluorescence analysis of trace elements in fruit juice

Quadratic polynomial technique for absorption correction in X-ray fluorescence spectrometry using continuous scattered background

Nanoscale switching of the lamellar 90∘ domains ({a-a} domains) of PbTiO3 grains in the surface of sol-gel-derived PbTiO3/Pb(Zr0.58Ti0.42)O3/PbTiO3 thin films is studied by three-dimensional piezoresponse force microscopy. It is demonstrated that the lamellar domain pattern in the PbTiO3 grains can be rotated 90∘ in the plane of film by the electric field at the tip. It is found that the rotation of lamellar domain pattern involves transverse growth of the existing embedded a-a domain nucleus, whose domain walls are perpendicular to the surrounding ones. During the transverse growth, the existing 90∘ domains extend along length direction and penetrate into neighboring domain walls, while formation of new 90∘ domain walls was mediated by the nanoscale 45∘ tilted spike domains.

In-Plane 90∘ Rotation of Lamellar Domains in PbTiO3 Grains Revealed by Piezoresponse Force Microscopy

An X-ray fluorescence technique was developed for the analysis of Al2O3, SiO2 and impurities in Kaolin concentrate Two standard series, one for dual series of Al2O3-SiO2 and the other for all of the impurities, were prepared, respectively, from spectral pure agents based on the estimates of analyte content ranges and matrix effects in Kaolin concentrate Powderd sample after determination of loss of ignition was pressed into disc by means of a little powderd sample preparation method modyfied in this paper All analyte contents were calculated directly from the calibration curves without any matrix correction In contrast to fusion technique the method has no the effects of flux impurities and dilute ration on the determination of minor and micro components in Kaolin concentrate Errors of the results are < 1% for major component Al2O3, SiO2 and total, and < 5% for most and < 10% for few of the impurities

Sheng-Xiang Bao

Papers

X-Ray fluorescence analysis of trace elements in fruit juice

Quadratic polynomial technique for absorption correction in X-ray fluorescence spectrometry using continuous scattered background

In-Plane 90∘ Rotation of Lamellar Domains in PbTiO3 Grains Revealed by Piezoresponse Force Microscopy

[X-ray fluorescence analysis of Kaolin concentrate].