8 research outputs found
Residual stress measurements on a deep rolled aluminum specimen through X-Ray Diffraction and Hole-Drilling, validated on a calibration bench
Residual stress measurements are notably affected by a high sensitivity to errors in input data. Measurements should then be presented together with an estimation of their accuracy. A common strategy is to carry out more measurements and/or to compare the results of different techniques. However, error contributions due to biases could be dangerously left unseen. In a previous work, the authors presented a calibration bench which can impose a known bending stress distribution on a specimen while simultaneously performing X-Ray Diffraction (XRD) or Hole-Drilling Method (HDM) residual stress measurements. Since the external load can freely be applied and removed, the superposition principle can be exploited to simultaneously identify either the reference bending stress distribution or the actual residual stress distribution, with the same experimental setup. A deep rolling treatment was measured and analyzed on the calibration bench with both XRD and HDM. First, residual stresses on the surface were evaluated with XRD measurements, then electrochemical material removal was performed to investigate stresses at higher depths. After that, HDM measurements were carried out and compared with the results of XRD. Both methods were also used to identify the known bending stresses, providing an additional validation of the residual stress results
Trace element determination in soy sauce: A novel total reflection X-ray fluorescence procedure and comparison with inductively coupled plasma\u2013mass spectrometry
Soy sauce is a widespread food commodity very common in East and Southeast Asia. It features a complex matrix, including a highly saline matrix (NaCl up to 15%) and a relevant organic component, typically around 15%. Methods for trace element determination in this matrix have been scarcely reported and no procedure has been proposed including Total Reflection X-Ray Fluorescence (TXRF). Aim of the present paper is to setup a TXRF method requiring minimum sample treatment and suitable for process control and risk assessment related to soy sauce consumption. Accordingly, a digestion (HNO3/H2O2) plus dilution (1:5 w/w) procedure was developed, applied to six soy samples from the Chinese market and the results compared to Inductively Coupled Plasma\u2013Mass Spectrometry data. As a result, the procedure was fully validated for the six elements that could be compared: Cu, Fe, Mn, Rb, Sr and Zn. A dilution only procedure was also assessed showing, on average, a 125% bias only. Accordingly, sample digestion yields highly accurate data, whereas a simple 1:5 dilution may be perfectly suited for most purposes. Regarding detection capabilities, the limits of detection are typically below 0.5 mg/kg for both digested + diluted and diluted only samples. The reported procedures are accordingly fit for purpose in quality assurance/quality control procedures and risk assessment related to soy sauce consumption
Phase Evolution in Synthesis of Manganese Ferrite Nanoparticles
Physico-chemical equilibria that influence oxide powders’ precipitation
from an aqueous solution can be substantially altered
when the process is carried out in a microemulsion system. To
obtain nanosizedMnFe2O4 and gain information about the physico-
chemical characteristics of products, Mn21 and Fe31 metal
ions were induced to precipitate in a toluene/water/sodium dodecylbenzenesulfonate
microemulsion system. Portions of the
precipitated powder were differently treated, both in solution
and in the solid state, and the role of restricted aqueous domains
in the obtained materials was investigated. X-ray diffraction
profile-fitting methods and chemical analysis were applied to
characterize the powder particles. Samples obtained from the
selected microemulsion were identified as nanosized mixed hydroxide
compounds. A low metal content and a limited matter
exchange among aqueous nanodroplets appear to inhibit hydroxide
to oxide transformation inside the selected micellar system.
A calcination process of precipitated powder was required
to obtain a manganese ferrite compound