While metabolomics is increasingly used to investigate the food metabolome and identify new markers of food exposure, limited attention has been given to the validation of such markers. The main objectives of the present study were to (1) discover potential food exposure markers (PEMs) for a range of plant foods in a study setting with a mixed dietary background and (2) validate PEMs found in a previous meal study. Three-day weighed dietary records and 24-h urine samples were collected three times during a 6-month parallel intervention study from 107 subjects randomized to two distinct dietary patterns. An untargeted UPLC-qTOF-MS metabolomics analysis was performed on the urine samples, and all features detected underwent strict data analyses, including an iterative paired t test and sensitivity and specificity analyses for foods. A total of 22 unique PEMs were identified that covered 7 out of 40 investigated food groups (strawberry, cabbages, beetroot, walnut, citrus, green beans and chocolate). The PEMs reflected foods with a distinct composition rather than foods eaten more frequently or in larger amounts. We found that 23 % of the PEMs found in a previous meal study were also valid in the present intervention study. The study demonstrates that it is possible to discover and validate PEMs for several foods and food classes in an intervention study with a mixed dietary background, despite the large variability in such a dataset. Final validation of PEMs for intake of foods should be performed by quantitative analysis.
Figure
Examples of two urinary exposure markers for cabbage (left) and beetroot (right) found in the study from an untargeted LC‐MS metabolomics analysis of urine samples and self‐reported food intake data 相似文献
This work presents analytical, numerical and experimental demonstrations of light diffracted through a logarithmic spiral (LS) nanoslit, which forms a type of switchable and focus‐tunable structure. Owing to a strong dependence on the incident photon spin, the proposed LS‐nanoslit converges incoming light of opposite handedness (to that of the LS‐nanoslit) into a confined subwavelength spot, while it shapes light with similar chirality into a donut‐like intensity profile. Benefitting from the varying width of the LS‐nanoslit, different incident wavelengths interfere constructively at different positions, i.e., the focal length shifts from 7.5 μm (at λ = 632.8 nm) to 10 μm (at λ = 488 nm), which opens up new opportunities for tuning and spatially separating broadband light at the micrometer scale.
Phase transitions in molecular crystals are often determined by intermolecular interactions. The cage complex of [Co(C12H30N8)]3+ ⋅ 3 NO3− is reported to undergo a disorder-order phase transition at Tc1 ≈133 K upon cooling. Temperature-dependent neutron and synchrotron diffraction experiments revealed satellite reflections in addition to main reflections in the diffraction patterns below Tc1. The modulation wave vector varies as function of temperature and locks in at Tc3≈98 K. Here, we demonstrate that the crystal symmetry lowers from hexagonal to monoclinic in the incommensurately modulated phases in Tc1<T<Tc3. Distinctive levels of competitions: trade-off between longer N−H⋅⋅⋅O and shorter C−H⋅⋅⋅O hydrogen bonds; steric constraints to dense C−H⋅⋅⋅O bonds give rise to pronounced modulation of the basic structure. Severely frustrated crystal packing in the incommensurate phase is precursor to optimal balance of intermolecular interactions in the lock-in phase. 相似文献
A photoswitchable ligand and palladium(II) ions form a dynamic mixture of self-assembled metallosupramolecular structures. The photoswitching ligand is an ortho-fluoroazobenzene with appended pyridyl groups. Combining the E-isomer with palladium(II) salts affords a double-walled triangle with composition [Pd3L6]6+ and a distorted tetrahedron [Pd4L8]8+ (1 : 2 ratio at 298 K). Irradiation with 410 nm light generates a photostationary state with approximately 80 % of the E-isomer of the ligand and results in the selective disassembly of the tetrahedron, the more thermodynamically stable structure, and the formation of the triangle, the more kinetically inert product. The triangle is then slowly transformed back into the tetrahedron over 2 days at 333 K. The Z-isomer of the ligand does not form any well-defined structures and has a thermal half-life of 25 days at 298 K. This approach shows how a thermodynamically preferred self-assembled structure can be reversibly pumped to a kinetic trap by small perturbations of the isomer distribution using non-destructive visible light. 相似文献
CO2 and steam/CO2 electroreduction to CO and methane in solid oxide electrolytic cells (SOEC) has gained major attention in the past few years. This work evaluates, for the very first time, the performance of two different ZnO–Ag cathodes: one where ZnO nanopowder was mixed with Ag powder for preparing the cathode ink (ZnOmix–Ag cathode) and the other one where Ag cathode was infiltrated with a zinc nitrate solution (ZnOinf –Ag cathode). ZnOmix–Ag cathode had a better distribution of ZnO particles throughout the cathode, resulting in almost double CO generation while electrolysing both dry CO2 and H2/CO2 (4:1 v/v). A maximum overall CO2 conversion of 48% (in H2/CO2) at 1.7 V and 700 °C clearly indicated that as low as 5 wt% zinc loading is capable of CO2 electroreduction. It was further revealed that for ZnOinf –Ag cathode, most of CO generation took place through RWGS reaction, but for ZnOmix–Ag cathode, it was the synergistic effect of both RWGS reaction and CO2 electrolysis. Although ZnOinf –Ag cathode produced trace amount of methane at higher voltages, with ZnOmix–Ag cathode, there was absolutely no methane. This seems to be due to strong electronic interaction between Zn and Ag that might have suppressed the catalytic activity of the cathode towards methanation.
Cyclodextrins (CDs) are cyclic oligosaccharides that have found widespread application in numerous fields. CDs have revealed a number of various health benefits, making them potentially useful food supplements and nutraceuticals. In this study, the impact of α-, β-, and γ-CD at different concentrations (up to 8% of the flour weight) on the wheat dough and bread properties were investigated. The impact on dough properties was assessed by alveograph analysis, and it was found that especially β-CD affected the viscoelastic properties. This behavior correlates well with a direct interaction of the CDs with the proteins of the gluten network. The impact on bread volume and bread staling was also assessed. The bread volume was in general not significantly affected by the addition of up to 4% CD, except for 4% α-CD, which slightly increased the bread volume. Larger concentrations of CDs lead to decreasing bread volumes. Bread staling was investigated by texture analysis and low field nuclear magnetic resonance spectroscopy (LF-NMR) measurements, and no effect of the addition of CDs on the staling was observed. Up to 4% CD can, therefore, be added to wheat bread with only minor effects on the dough and bread properties. 相似文献
Using molecular simulations, we show that the aperiodic growth of quasicrystals is controlled by the ability of the growing quasicrystal nucleus to incorporate kinetically trapped atoms into the solid phase with minimal rearrangement. In the system under investigation, which forms a dodecagonal quasicrystal, we show that this process occurs through the assimilation of stable icosahedral clusters by the growing quasicrystal. Our results demonstrate how local atomic interactions give rise to the long-range aperiodicity of quasicrystals. 相似文献
In situ missions of exploration require analytical methods that are capable of detecting a wide range of molecular targets in complex matrices without a priori assumptions of sample composition. Furthermore, these methods should minimize the number of reagents needed and any sample preparation steps. We have developed a method for the detection of metabolically relevant inorganic and organic anions that is suitable for implementation on in situ spaceflight missions. Using 55 mM acetic acid, 50 mM triethylamine, and 5% glycerol, more than 21 relevant anions are separated in less than 20 min. The method is robust to sample ionic strength, tolerating high concentrations of background salts (up to 900 mM NaCl and 300 mM MgSO4). This is an important feature for future missions to ocean worlds. The method was validated using a culture of Escherichia coli and with high salinity natural samples collected from Mono Lake, California. 相似文献
Non‐invasive and real‐time analysis of cellular redox processes has been greatly hampered by lack of suitable measurement techniques. Here we describe an in‐cell nuclear magnetic resonance (NMR) based method for measuring the intracellular glutathione redox potential by direct and quantitative measurement of isotopically labeled glutathione introduced exogenously into living yeast. By using this approach, perturbations in the cellular glutathione redox homeostasis were also monitored as yeast cells were subjected to oxidative stress. 相似文献