1,165 research outputs found
Effect of ozone gas processing on physical and chemical properties of wheat proteins
Purpose: To investigate the effects of ozone treatment on chemical and physical properties of wheat (Triticum aestivum L.) gluten, glutenin and gliadin.Methods: Wheat proteins isolated from wheat flour were treated with ozone gas. The physical and chemical properties of gluten proteins were investigated after treatment with ozone gas, with 5 g/h produced as a function of time (0, 30, and 60 min) in the study. To check whether the process of ozonation promoted changes in the quality of gluten proteins, sulfhydryl groups (SH), differential scanning calorimetry (DSC), secondary structure, SDS-PAGE, and rheology analyses were performed.Results: Sulfhydryl group contents of wheat proteins ranged from 1.1 to 7.12 ÎŒmol/g. Sulfhydryl group content for all ozonated proteins was significantly lower than that of the control samples. Gluten proteins showed reduced SDS-PAGE band intensities of both high (HMW) gluten and glutenin subunits with increasing ozone gas treatment. The denaturation temperatures (Td) of ozonated gluten proteins were higher (99.80â106.79 °C) and the enthalpies of the ozonated gluten proteins were lower than those of the control samples. The storage moduli (G') and loss moduli (Gâ) of gluten and glutenin tended to increase from 7.84 to 10.20 KPa and 43.19 to 48.28 KPa, and from 3.33 to 4.06 KPa and 20.74 to 22.56 KPa, respectively, as ozone exposure increased from 0 to 30 min.Conclusion: Ozone gas can oxidize wheat proteins. Exposing wheat proteins to ozone gas for an extended time (60 min) deteriorated wheat protein quality.Keywords: Ozone treatment, Gluten proteins, Chemical changes, Rheological studies, CD spectroscopy, Thermal propertie
Power-Law Decay of Standing Waves on the Surface of Topological Insulators
We propose a general theory on the standing waves (quasiparticle interference
pattern) caused by the scattering of surface states off step edges in
topological insulators, in which the extremal points on the constant energy
contour of surface band play the dominant role. Experimentally we image the
interference patterns on both BiTe and BiSe films by measuring
the local density of states using a scanning tunneling microscope. The observed
decay indices of the standing waves agree excellently with the theoretical
prediction: In BiSe, only a single decay index of -3/2 exists; while in
BiTe with strongly warped surface band, it varies from -3/2 to -1/2 and
finally to -1 as the energy increases. The -1/2 decay indicates that the
suppression of backscattering due to time-reversal symmetry does not
necessarily lead to a spatial decay rate faster than that in the conventional
two-dimensional electron system. Our formalism can also explain the
characteristic scattering wave vectors of the standing wave caused by
non-magnetic impurities on BiTe.Comment: 4 pages, 3 figure
A New ZrCuSiAs-Type Superconductor: ThFeAsN
We report the first nitrogen-containing iron-pnictide superconductor ThFeAsN,
which is synthesized by a solid-state reaction in an evacuated container. The
compound crystallizes in a ZrCuSiAs-type structure with the space group P4/nmm
and lattice parameters a=4.0367(1) {\AA} and c=8.5262(2) {\AA} at 300 K. The
electrical resistivity and dc magnetic susceptibility measurements indicate
superconductivity at 30 K for the nominally undoped ThFeAsN.Comment: 6 pages, 4 figures, 1 tabl
Type-II Ising Pairing in Few-Layer Stanene
Spin-orbit coupling has proven indispensable in realizing topological
materials and more recently Ising pairing in two-dimensional superconductors.
This pairing mechanism relies on inversion symmetry breaking and sustains
anomalously large in-plane polarizing magnetic fields whose upper limit is
expected to diverge at low temperatures, although experimental demonstration of
this has remained elusive due to the required fields. In this work, the
recently discovered superconductor few-layer stanene, i.e. epitaxially strained
-Sn, is shown to exhibit a new type of Ising pairing between carriers
residing in bands with different orbital indices near the -point. The
bands are split as a result of spin-orbit locking without the participation of
inversion symmetry breaking. The in-plane upper critical field is strongly
enhanced at ultra-low temperature and reveals the sought for upturn
Diversification of mitogenomes in three sympatric Altica flea beetles (Insecta, Chrysomelidae)
The Asian flea beetles Altica cirsicola, Altica fragariae and Altica viridicyanea are broadly sympatric and morphologically highly similar but feed on distantly related host plants. They have been suggested as a model for ecological speciation stud- ies. However, their phylogeny and species limits remain uncertain. In this study, we added mitochondrial genomes from multiple individuals of each species to the grow- ing database. Phylogenetic analyses based on 15 genes showed clear interspecific divergences of A. fragariae from the other species, but A. cirsicola and A. viridi- cyanea were not distinguishable by distanceâbased or treeâbased methods of species delimitation due to nonâmonophyly of mitogenomes relative to the morphologically defined entities, possibly affected by interspecific introgression. This was confirmed by wider sampling of mitochondrial COX1 (58 individuals) and the second internal transcribed spacer of nuclear ribosomal RNA cluster (ITS2; 68 individuals), which showed that ITS2, but not COX1, coincided with the morphological species limits. The full mitochondrial genomes are not able to shed further light on the species status, even with the most sensitive approach based on diagnostic characters, yet the whole mitogenome is useful to get improved estimates of intraâ and interspecific variation, not affected by the stochastic error seen in individual genes
TERT promoter methylation is associated with high expression of TERT and poor prognosis in papillary thyroid cancer
The telomerase reverse transcriptase (TERT) is overexpressed and associated with poor prognosis in papillary thyroid cancer (PTC), the most common subtype of thyroid cancer. The overexpression of TERT in PTC was partially attributed to transcriptional activation by two hotspot mutations in the core promoter region of this gene. As one of the major epigenetic mechanisms of gene expression regulation, DNA methylation has been proved to regulate several tumor-related genes in PTC. However, the association of TERT promoter DNA methylation with TERT expression and PTC progression is still unclear. By treating PTC cell lines with demethylating agent decitabine, we found that the TERT promoter methylation and the genesâ expression were remarkably decreased. Consistently, PTC patients with TERT hypermethylation had significantly higher TERT expression than patients with TERT hypomethylation. Moreover, TERT hypermethylated patients showed significant higher rates of poor clinical outcomes than patients with TERT hypomethylation. Results from the cox regression analysis showed that the hazard ratios (HRs) of TERT hypermethylation for overall survival, disease-specific survival, disease-free interval (DFI) and progression-free interval (PFI) were 4.81 (95% CI, 1.61-14.41), 8.28 (95% CI, 2.14-32.13), 3.56 (95% CI, 1.24-10.17) and 3.32 (95% CI, 1.64-6.71), respectively. The HRs for DFI and PFI remained significant after adjustment for clinical risk factors. These data suggest that promoter DNA methylation upregulates TERT expression and associates with poor clinical outcomes of PTC, thus holds the potential to be a valuable prognostic marker for PTC risk stratification
A controllable superconducting electromechanical oscillator with a suspended membrane
We fabricate a microscale electromechanical system, in which a suspended
superconducting membrane, treated as a mechanical oscillator, capacitively
couples to a superconducting microwave resonator. As the microwave driving
power increases, nonmonotonic dependence of the resonance frequency of the
mechanical oscillator on the driving power has been observed. We also
demonstrate the optical switching of the resonance frequency of the mechanical
oscillator. Theoretical models for qualitative understanding of our
experimental observations are presented. Our experiment may pave the way for
the application of a mechanical oscillator with its resonance frequency
controlled by the electromagnetic and/or optical fields, such as a
microwave-optical interface and a controllable element in a
superqubit-mechanical oscillator hybrid system.Comment: 8 pages,4 figure
Effect of phosphogypsum and poultry manure on aggregate-associated alkaline characteristics in bauxite residue
Bauxite residue is a highly alkaline solid waste with poor physical structure which ultimately limits plant growth. Ecological reconstruction is an effective strategy to improve its environmental management, although soil formation process still requires further investigation. Here, an incubation experiment was used to investigate the effects of phosphogypsum and poultry manure, on aggregate size distribution and aggregate-associated exchangeable bases of bauxite residue. Phosphogypsum and poultry manure additions significantly increased the proportion of 2â1 mm residue aggregates and enhanced mean weight diameter (MWD) of residues in the 0â20 cm and 20â40 cm layers, although little effect was evident in the 40â60 cm layer. Phosphogypsum addition reduced pH and EC values to approximately 8.5 and 200 mS/cm in different size aggregates at 0â20 cm. Exchangeable Ca2+ concentration was improved, especially in 0.25â0.05 mm and 0.25 mm aggregate fractions were relatively higher, which was consistent with changes in pH. Phosphogypsum and poultry manure changed the microstructure and surrounding pores of residue aggregates, whilst the concentration of Ca on microaggregate surfaces was higher than that on macroaggregates. These findings reveal that application of phosphogypsum and poultry manure directly alter the distribution of exchangeable bases and alkaline indicators within residue aggregates, resulting in aggregate size distribution and microstructure variations
Evaluating aggregate stability, surface properties and disintegration behavior of bauxite residue induced by Ca/Na
Bauxite residue, a typical industrial solid waste which contains a large amount of Na+, is usually physically degraded. Understandings of aggregate formation, which is a critical process in soil development, are essential to facilitate ecological rehabilitation on the disposal areas. However, few studies have investigated the aggregation behavior and mechanisms of key salt ions (Ca2+ and Na+) in residue aggregates. Therefore, an integrated method of Le Bissonnaisâ method, the combined determination method, and laser diffraction measurements was applied to evaluate aggregate stability, surface properties and disintegration behavior of bauxite residue following Ca/Na additions. With increasing Ca2+ addition, mean weight diameter (MWD) increased, indicating improved resistance to dispersion. Ca2+ had a positive effect on flocculation of siltâsize microaggregates, whilst disintegration was induced following Na+ addition. Repeated laser diffraction analysis of residue samples circulating in 50âmmol Lâ1 electrolyte solution (Ca2+/Na+) provided a detailed view of the changes in particle size distribution as aggregates fragmented. The visualized threeâdimensional surface map revealed that Na+ promoted the disintegration of >250 ÎŒm aggregates into finer dispersed particles, whilst Ca2+ protected the microaggregates from fragmenting into smaller particles. Variation in electrochemical properties of aggregate surfaces affected the microâmorphology significantly. The findings provide a new approach to specify pedogenic aggregate behavior of bauxite residue, whilst revealing the effects of Ca2+/Na+ on aggregate stability, surface electrochemical properties and its micromorphology. The results will provide a detailed understanding of aggregate behavior during soil formation process in bauxite residue
- âŠ