2,219 research outputs found
Trapped ion mobility spectrometry and PASEF enable in-depth lipidomics from minimal sample amounts
A comprehensive characterization of the lipidome from limited starting material remains very challenging. Here we report a high-sensitivity lipidomics workflow based on nanoflow liquid chromatography and trapped ion mobility spectrometry (TIMS). Taking advantage of parallel accumulation-serial fragmentation (PASEF), we fragment on average 15 precursors in each of 100 ms TIMS scans, while maintaining the full mobility resolution of co-eluting isomers. The acquisition speed of over 100 Hz allows us to obtain MS/MS spectra of the vast majority of isotope patterns. Analyzing 1 mu L of human plasma, PASEF increases the number of identified lipids more than three times over standard TIMS-MS/MS, achieving attomole sensitivity. Building on high intra- and inter-laboratory precision and accuracy of TIMS collisional cross sections (CCS), we compile 1856 lipid CCS values from plasma, liver and cancer cells. Our study establishes PASEF in lipid analysis and paves the way for sensitive, ion mobility-enhanced lipidomics in four dimensions
Textural Properties and Structure of Starch-Reinforced Surimi Gels as Affected by Heat-Setting
The gel forming behavior of red hake (Urophycis chuss) surimi with and without starch and its relationship to the structure of the gel matrix were studied. For surimi gels without starch, a combination of preheat- setting at 40 C and cooking at 90 C resulted in significantly greater gel strength than cooking alone. However, preheat - setting of gels containing wheat or potato starch had no significant effect on gel strength demonstrating an opposite trend in gel strength due to the differences in swelling power, water holding ability and gelatinization temperature between potato and wheat starches. This difference in gel forming behavior due to the sources of starch and heat- setting prior to cooking correlated with changes in the structure of the matrix as evidenced by the results of image analysis. An examination of the microstructure of the gel matrix by light and electron microscopy showed that the structural differences may be due to the different protein matrix density as reflected in the increased gel strength
Textural and Microstructural Properties of Frozen Fish Mince as Affected by the Addition of Nonfish Proteins and Sorbitol
Changes in textural and microstructural properties of washed and unwashed frozen fish mince were studied as affected by the addition of non fish proteins (soy protein isolate, milk protein isolate, egg white, and wheat gluten at 2 , 4 or 6%) and 6% crystalline sorbitol. Soy and milk proteins and sorbitol reduced the hardness of frozen fish mince, while egg white and wheat gluten made the texture firmer without rubberiness developing after frozen storage. All nonfish proteins and sorbitol stabilized the myofibrillar organization by reducing freeze-induced contraction of myofibrils.
The mechanisms of reducing texture hardening appear to be different between sorbitol and nonfish proteins. Water binding properties and dispersibility made the difference among nonfish proteins in reducing freeze-contraction of myofibrils. Nonfish proteins not only reduced texture hardening during frozen storage, but also modified texture during cooki ng as they underwent thermal gelation specific to each protein used
Effects of TemperatureâClimate Patterns on the Production of Some Competitive Species on Grounds of Modelling
Climate change has serious effects on the setting
up and the operation of natural ecosystems. Small increase
in temperature could cause rise in the amount of some
species or potential disappearance of others. During our
researches, the dispersion of the species and biomass
production of a theoretical ecosystem were examined on
the effect of the temperatureâclimate change. The answers
of the ecosystems which are given to the climate change
could be described by means of global climate modelling
and dynamic vegetation models. The examination of the
operation of the ecosystems is only possible in huge centres
on supercomputers because of the number and the
complexity of the calculation. The number of the calculation
could be decreased to the level of a PC by considering
the temperature and the reproduction during modelling a
theoretical ecosystem, and several important theoretical
questions could be answered
Metal-insulator transitions in cyclotron resonance of periodic nanostructures due to avoided band crossings
A recently found metal-insulator transition in a model for cyclotron
resonance in a two-dimensional periodic potential is investigated by means of
spectral properties of the time evolution operator. The previously found
dynamical signatures of the transition are explained in terms of avoided band
crossings due to the change of the external electric field. The occurrence of a
cross-like transport is predicted and numerically confirmed
Universal Slip Dynamics in Metallic Glasses and Granular Matter â Linking Frictional Weakening with Inertial Effects
Slowly strained solids deform via intermittent slips that exhibit a material-independent critical size distribution. Here, by comparing two disparate systems - granular materials and bulk metallic glasses - we show evidence that not only the statistics of slips but also their dynamics are remarkably similar, i.e. independent of the microscopic details of the material. By resolving and comparing the full time evolution of avalanches in bulk metallic glasses and granular materials, we uncover a regime of universal deformation dynamics. We experimentally verify the predicted universal scaling functions for the dynamics of individual avalanches in both systems, and show that both the slip statistics and dynamics are independent of the scale and details of the material structure and interactions, thus settling a long-standing debate as to whether or not the claim of universality includes only the slip statistics or also the slip dynamics. The results imply that the frictional weakening in granular materials and the interplay of damping, weakening and inertial effects in bulk metallic glasses have strikingly similar effects on the slip dynamics. These results are important for transferring experimental results across scales and material structures in a single theory of deformation dynamics
A Closest Point Proposal for MCMC-based Probabilistic Surface Registration
We propose to view non-rigid surface registration as a probabilistic
inference problem. Given a target surface, we estimate the posterior
distribution of surface registrations. We demonstrate how the posterior
distribution can be used to build shape models that generalize better and show
how to visualize the uncertainty in the established correspondence.
Furthermore, in a reconstruction task, we show how to estimate the posterior
distribution of missing data without assuming a fixed point-to-point
correspondence.
We introduce the closest-point proposal for the Metropolis-Hastings
algorithm. Our proposal overcomes the limitation of slow convergence compared
to a random-walk strategy. As the algorithm decouples inference from modeling
the posterior using a propose-and-verify scheme, we show how to choose
different distance measures for the likelihood model.
All presented results are fully reproducible using publicly available data
and our open-source implementation of the registration framework
Bulk Metallic Glasses Deform via Slip Avalanches
Inelastic deformation of metallic glasses occurs via slip events with
avalanche dynamics similar to those of earthquakes. For the first time in these
materials, measurements have been obtained with sufficiently high temporal
resolution to extract both the exponents and the scaling functions that
describe the nature, statistics and dynamics of the slips according to a simple
mean-field model. These slips originate from localized deformation in shear
bands. The mean-field model describes the slip process as an avalanche of
rearrangements of atoms in shear transformation zones (STZs). Small slips show
the predicted power-law scaling and correspond to limited propagation of a
shear front, while large slips are associated with uniform shear on
unconstrained shear bands. The agreement between the model and data across
multiple independent measures of slip statistics and dynamics provides
compelling evidence for slip avalanches of STZs as the elementary mechanism of
inhomogeneous deformation in metallic glasses.Comment: Article: 11 pages, 4 figures, plus Supplementary Material: 16 pages,
8 figure
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