321034 research outputs found
Sort by
Three-dimensional architecture and linearized mapping of vibrissa follicle afferents
No full textUnderstanding vibrissal transduction has advanced by serial sectioning and identified afferent recordings, but afferent mapping onto the complex, encapsulated follicle remains unclear. Here, we reveal male rat C2 vibrissa follicle innervation through synchrotron X-ray phase contrast tomograms. Morphological analysis identified 5% superficial, ~32 % unmyelinated and 63% myelinated deep vibrissal nerve axons. Myelinated afferents consist of each one third Merkel and club-like, and one sixth Ruffini-like and lanceolate endings. Unsupervised clustering of afferent properties aligns with classic morphological categories and revealed previously unrecognized club-like afferent subtypes distinct in axon diameter and Ranvier internode distance. Myelination and axon diameters indicate a proximal-to-distal axon-velocity gradient along the follicle. Axons innervate preferentially dorso-caudally to the vibrissa, presumably to sample contacts from vibrissa protraction. Afferents organize in axon-arms innervating discrete angular territories. The radial axon-arm arrangement around the vibrissa maps into a linear representation of axon-arm bands in the nerve. Such follicle linearization presumably instructs downstream linear brainstem barrelettes. Synchrotron imaging provides a synopsis of afferents and mechanotransductory machinery
Structural elucidation and characterization of GH 29 A α‐ l ‐fucosidases and the effect of p H on their transglycosylation
No full textGH29A α-l-fucosidases (EC 3.2.1.51) catalyze the release of α-l-fucosyl moieties from the nonreducing end of glycoconjugates by hydrolysis and some also catalyze transglycosylation. The latter is particularly interesting with regard to designing enzymatic synthesis of human milk oligosaccharides (HMOs). We combined the bioinformatics tool conserved unique peptide patterns (CUPP) and phylogenetic clustering to discover new microbial GH29A α-l-fucosidases of the underexplored CUPP group GH29:13.1. Three uncharacterized bacterial enzymes (EaGH29, SeGH29, and PmGH29) and two previously identified GH29A α-l-fucosidases (BF3242 and TfFuc1) were selected for reaction optimization, biochemical, and structural characterization. Kinetics, pH-temperature optima, and substrate preference for 2-chloro-4-nitrophenyl-α-l-fucopyranoside (CNP-α-l-Fuc) and 2′-fucosyllactose (2′FL) were determined. Transglycosylation was favored at high neutral to alkaline pH, especially for EaGH29, SeGH29, TfFuc1, and BF3242, mainly because hydrolysis was decreased. The α-l-fucosidases exhibited medium regioselectivity in transglycosylation, generally forming two out of five detected lacto-N-fucopentaose (LNFP) isomers from 2′FL and lacto-N-tetraose (LNT). Alkaline pH also affected the transglycosylation product regioselectivity of SeGH29, which was also affected by a Leu/Phe exchange in the acceptor binding site. New crystal structures of TfFuc1 and BF3242 showed congruence in active site topology between these two enzymes and contributed to understanding the function of GH29A α-l-fucosidases. Notably, the structural data provide new insight into the role of an Asn residue located between the two catalytic residues in the active site
In-situ X-ray analysis of cold alkali dissolution of cellulose pulps of various origin
No full textThis article elucidates the dissolution of cellulose from different raw materials in NaOH aqueous solution via the combination of synchrotron-radiation-based SAXS/WAXS characterization. The X-ray measurements probed the mesostructure of the cellulose samples during the freeze-thawing cycle allowing tracking the initial swelling of the structure, the kinetics of disintegration of the cellulose crystallites as well as controlling the final state of the cellulose solution, i.e. presence or absence of cellulose aggregates. The individual SAXS and WAXS measurements were fitted and modelled to enable visualisation and tracking of the changes in the structure in relation to temperature during cooling and warming phases. To further increase the understanding of the parameters affecting dissolution different cellulose samples and solution compositions were considered. For this purpose the effect of increasing the concentration of NaOH and adding Zn2+ has been carefully investigated as well as the importance of the cellulose origin. We found consistent development that the dissolution occurs faster at higher concentrations of NaOH and with Zn2+ regardless the origin. Nevertheless, SAXS data show that materials with a larger amount of cellulose I show more apparent swelling in mesoscopic structure than bleached agricultural containing cellulose II. Despite few crystalline residues after the complete cooling-heating cycle shown by WAXS, some cellulose was not completely dissolved as some network structure remained in the samples under the test condition as suggested by SAXS
Correction to “Three-Dimensional Orientation of Nanofibrils in Axially Symmetric Systems Using Small-Angle X-ray Scattering”
No full textIn our manuscript, we provide MATLAB code to perform the reconstruction from projected orientation distribution functions (ODFs) to three-dimensional ODFs. Recently, it has come to our attention that the file “LegendrePolynomials.mat” requires an installation of the “Symbolic Math Toolbox” in MATLAB to be loaded correctly. Otherwise, it will just be loaded as an empty 1 × 15 cell object, causing errors in the reconstruction steps
A comprehensive study on loading/deloading with PdAg alloy thin films using in-situ synchrotron radiation X-ray diffraction
No full textThe present study gives a comprehensive picture of interaction of hydrogen with PdAg and PdAg alloy thin films, at RT, 50 °C, 100 °C, 150 °C and200 °C, based on the experiments reported in the present work. During hydrogenation, the diffraction peaks shifted towards a lower angle, indicating an expansion of the lattice due to hydrogen incorporation revealed by in-situ synchrotron XRD. The cycles of hydrogen absorption and desorption were fully reversible, and no hysteresis was observed in the synthesized films. Our experiments suggest that at room temperature the magnitude of peak-shift on hydrogenation is larger with lower concentrations of Ag in Pd. Additionally, the interaction of PdAg alloy with hydrogen was observed to be temperature dependent. Increased hydrogenation temperature reduces the hydrogen sticking coefficient, reducing the peak shift magnitude for both samples. Additionally, at higher temperatures, hydrogen absorption is higher in Pd54Ag46 having smaller crystallite sizes than in Pd88Ag12
Luminescent Properties of -Doped Crystallites
No full textResearch is ongoing to develop new phosphors capable of emitting light across a broad spectrum, ranging from the ultraviolet (UV) to the infrared region, with potential applications in diverse fields. Using the method of solid-state reactions, a series of LiBaF3:Pr3+ phosphors were obtained, and their luminescent properties in the UV−visible range were studied. The photon cascade emission (PCE) phenomenon has been observed under excitation of the 4f5d bands of Pr3+. The spectral and kinetic luminescent characteristics of LiBaF3:Pr3+ under X-ray excitation (40 keV) were studied. The X-ray excited luminescence spectrum of LiBaF3:Pr3+ consists of the emission of Pr3+ ions, the emission of self- trapped excitons, and the core−valence luminescence of the LiBaF3 host. In addition, the study assessed the optical-thermometric properties of LiBaF3:Pr3+ in the temperature range of 83−563 K, revealing the potential of temperature sensing in the physiological range. This study not only describes the luminescent properties of the newly synthesized LiBaF3:Pr3+ but also explores its potential applications as a fast ultraviolet scintillator and an optical temperature sensor
Optimal transport on gas networks
No full textOptimal transport tasks naturally arise in gas networks, which include a variety of constraints such as physical plausibility of the transport and the avoidance of extreme pressure fluctuations. To define feasible optimal transport plans, we utilize a p-Wasserstein metric and similar dynamic formulations minimizing the kinetic energy necessary for moving gas through the network, which we combine with suitable versions of Kirchhoff’s law as coupling condition at the nodes. In contrast to existing literature, we especially focus on the non-standard case p=2 to derive an overdamped isothermal model for gases through p-Wasserstein gradient flows in order to uncover and analyze underlying dynamics. We introduce different options for modeling the gas network as an oriented graph including the possibility to store gas at interior vertices and to put in or take out gas at boundary vertices
Future Collider Measurements for Cosmic-ray-induced Air Shower Modelling
No full textThe identification of gamma-ray induced air showers with Cherenkov telescopes suffers from contamination with a specific class of cosmic ray induced air showers. The predictions for this background show strong discrepancies between the available event generators. In this study, we identify collision events of cosmic rays with atmospheric nuclei in which a large fraction of the original beam energy is transmitted to the electromagnetic part of the shower as the main source for this background. Consequently, we define a pseudorapidity region of interest for hadron collider experiments that corresponds to this background, taking into account the center-of-mass energy. This region of interest is compared with the available datasets and the pseudorapidity coverage of the detectors that recorded it. We find that the LHCf and RHICf detectors are the only ones covering substantial parts of this region of interest and suggest a measurement of the energy spectra of reconstructed neutral pions to be made with this data. Such results could serve as valuable constraints for a future parameter tuning of the event generators to improve the background estimation uncertainties for gamma-ray induced air shower identification
Arrival Time Analysis of the Pump-Probe Laser at the XPB Experiment at the EuXFEL
No full textThe arrival time of a pump-probe laser with 2 stage NOPA is measured after transport, showing that great care has to be given to the beamline implementation