Changes of phosphorus and trace elements species in rye and oat flakes and oat porridge induced by simulated digestion

Fractionation of chemical species of phosphorus, manganese, iron, nickel, copper, zinc and molybdenum in rye and oat flakes and porridge made of oat flakes was studied by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry. The effect of in vitro simulated digestion of the samples was elucidated by comparison of the digestates and the extracts of the samples (in the Tris–HCl buffer solution, pH = 7.5). The procedure of simulated digestion included two steps: the pepsin-catalysed hydrolysis in diluted hydrochloric acid (pH = 1.7) followed by the pancreatin-catalysed hydrolysis at pH = 7.5. The enzyme-catalysed digestion of the samples results in alteration of iron, copper and zinc species distribution. The species of phosphorus in original cereal samples are distributed between two fractions: a medium-molecular mass fraction (15 kDa) and a low-molecular mass fraction (2 kDa). This pattern is also kept basically in the sample digestates. In digested samples, the majority of soluble iron is bound in a medium-molecular mass fraction (20 kDa), while in the extracts only traces of iron were found in a high-molecular mass fraction. Approximately 90% of the soluble zinc in the digestates of cereal flakes is represented by non-bound zinc ions. The bound zinc is mostly concentrated in a low-molecular mass fraction (1–2 kDa) together with some copper and almost all nickel. The low-molecular mass fractions (1–2 kDa) of nickel, copper and zinc present in extracts of original samples correspond quite well to those in the respective digestates. Molybdenum species occurs in another low-molecular mass fraction.     

Transport properties and observation of quantum Hall effects of InAs0.1Sb0.9 thin layers sandwiched between Al0.1In0.9Sb layers

InAs_0.1Sb_0.9 active layers sandwiched between Al_0.1In_0.9Sb insulating buffer layers were grown on GaAs (1 0 0) substrates by molecular beam epitaxy. The basic transport properties at room temperature and quantum Hall effects at low temperature of the InAs_0.1Sb_0.9 were studied as a function of InAs_0.1Sb_0.9 thickness. The electron mobility of the InAs_0.1Sb_0.9 active layers had a very high value and very small thickness dependence at less than 500 nm. The quantum Hall effects of the InAs_0.1Sb_0.9 were observed at thicknesses 15, 20, 30, 50, 70, and 100 nm. The observation of the quantum Hall effect at thickness more than 50 nm strongly suggests the existence of two-dimensional electron gas in the InAs_0.1Sb_0.9 layer sandwiched between Al_0.1In_0.9Sb layers.     

Application of Terahertz Field Enhancement Effect in Metal Microstructures

Applications of high-field terahertz pulses are attractive in physics and terahertz technology. In this study, two applications related to high-intensity terahertz pulses are demonstrated. The field enhancement effect by subwavelength metallic microstructures is utilized for terahertz excitation measurement. The spin precession dynamics in magnetic materials was induced by a terahertz magnetic field. Spin precession was amplified by one order of magnitude in amplitude by the enhanced magnetic terahertz field in orthoferrite ErFeO₃ with metal microstructures. The induced spin dynamics was analyzed and explained by LLG-LCR model. Moreover, a detection method for terahertz pulses was developed using a cholesteric liquid crystal at room temperature without any electronic devices. The beam profile of terahertz pulses was visualized and compared to other methods such as the knife edge method using pyroelectric detector and micro-bolometer array. The liquid crystal terahertz imager is very simple and has good applicability as a portable terahertz-sensing card.     

Analysis of element species fractions in buckwheat and amaranth flours by SEC/ICP-MS and MALDI-MS

Fractionation of Co, Cu, Fe, Mn, Mo, Ni, P and Zn in extracts of buckwheat and amaranth flour in 0.02 mol·l⁻¹ Tris-HCl (pH = 7.5) buffer was performed by SEC/ICP-MS. All metals except for Fe and Mn (both samples) and Cu (amaranth only) are concentrated in a low-molecular fraction (M _r < 2 kDa). Fe is bound in a high-molecular fraction (M _r > 150 kDa). The main part of Mn is present as a labile complex or an ionic form. Cu in amaranth extract is also bound in medium-molecular fractions (10 and 40 kDa) and in a high-molecular one (M _r > 150 kDa). Fractions rich in trace metals were isolated using preparative-scale SEC and the organic ligands of metals were refined by immobilized metal affinity chromatography. Low content of sulphur-containing amino acids (Cys, Met) and high content of acidic amino acids (Glu, Asp) are typical for all these purified fractions. A part of Zn (buckwheat) and almost all Cu (amaranth) in the low-molecular fractions were located in phosphorus rich sub-fractions. However, all Ni (both samples), the majority of Zn (buckwheat) and all Cu (buckwheat) were found in phosphorus-less sub-fractions. No phytochelatins were found in MALDI-MS spectra of isolated ligands.     

Non-destructive evaluation of ATP content and plate count on pork meat surface by fluorescence spectroscopy

The potential of fluorescence spectroscopy was investigated for the non-destructive evaluation of ATP content and plate count on pork meat surface stored aerobically at 15 °C during three days. Excitation (Ex) Emission (Em) Matrix of fluorescence intensity was obtained and fluorescence from tryptophan (Ex = 295 nm and Em = 335 nm) and NADPH (Ex = 335 nm and Em = 450 nm) was detected. Because tryptophan and NADPH fluorescence changed along with the growth of microorganisms, microbial spoilage on meat could be detected from fluorescence. By applying PLSR (Partial Least Squares Regression) analysis, ATP content and plate count were predicted with good determination coefficient (0.94–0.97 in calibration and 0.84–0.88 in validation).     

Prediction of Aerobic Plate Count on Beef Surface Using Fluorescence Fingerprint

The potential of fluorescence fingerprint (FF) spectroscopy was investigated to develop a nondestructive prediction method of aerobic plate count on a beef surface. Sixty samples (e.g., 30 lean meat slices each of Australian cattle and Japanese cattle) stored aerobically at 15 °C were analyzed by front-face fluorescence spectrophotometry. FF and aerobic plate count (APC) were measured after 0, 12, 24, 36, and 48 h of storage. FFs were collected in both excitation and emission wavelength ranges of 200–900 nm. Partial least-squares regression (PLSR) performed on an FF dataset predicted an APC in the bacterial contamination load range from 1.7 to 7.8 log?colony-forming units (cfu)/cm² with a prediction error of 0.752 log cfu/cm². The regions where the regression coefficient of the PLSR model was relatively high were consistent with those of the FF peaks of five intrinsic fluorophores: tryptophan, NAD(P)H, vitamin A, porphyrins, and flavins. This suggests that changes in the autofluorescence of these intrinsic fluorophores due to the metabolism of bacterial flora on meat are reflected in the PLSR model for predicting APC from the FF dataset. FF spectroscopy coupled with multivariate analysis appeared to be applicable to the nondestructive determination of APC on the surface of lean beef.     

Effect of various triazine derivatives on the thermal oxidative degradation of isotactic polypropylene

A number of triazine derivatives, mostly aryloxy-s-triazines, were prepared, and the effects of these compounds on the thermal oxidative degradation of isotactic polypropylene were examined by conventional oxygen uptake. Almost all triazine derivatives prepared showed a more or less inhibitive effect on the degradation of the polymer. Among them, α- and β-napthyloxy-s-triazines were found to be excellent inhibitors. On the basis of the results obtained, the relationship between inhibitive effect and the structure of the triazine derivatives is discussed.     

Erbium:YAG laser lithotripsy by use of a flexible hollow waveguide with an end-scaling cap

An Er:YAG laser light delivery system composed of a polymer-coated silver hollow waveguide and a quartz sealing cap has been developed for calculus fragmentation. Sealing caps with various distal-end geometries were fabricated, and the focusing effects of these caps for Er:YAG laser light were measured both in air and in water. Owing to the high power capability of the quartz a beam of sealing caps, Er:YAG laser light with an output energy of 200 mJ and a repetition rate of 10 Hz was successfully transmitted in saline solution by use of the system. Calculus fragmentation experiments conducted in vitro showed that the delivery system is suitable for medical applications in lithotripsy. We also found that the cap with a focusing effect is more effective in cutting calculi. The deterioration of the sealing caps after calculus fragmentation is also discussed.