1,574 research outputs found
Influence of thermal history on the structure and properties of silicate glasses
We studied a set of float glass samples prepared with different fictive
temperature by previous annealing around the glass transition temperature. We
compared the results to previous measurements on a series of amorphous silica
samples, also prepared with different fictive temperature. We showed that the
modifications on the structure at a local scale are very small, the changes of
physical properties are moderate but the changes on density fluctuations at a
nanometer scale are rather large: 12 and 20% in float glass and silica, for
relative changes of fictive temperature equal to 13 and 25% respectively. Local
order and mechanical properties of silica vary in the opposite way compared to
float glass (anomalous behavior) but the density fluctuations in both glasses
increase with temperature and fictive temperature
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Studying Lactoferrin N-Glycosylation.
Lactoferrin is a multifunctional glycoprotein found in the milk of most mammals. In addition to its well-known role of binding iron, lactoferrin carries many important biological functions, including the promotion of cell proliferation and differentiation, and as an anti-bacterial, anti-viral, and anti-parasitic protein. These functions differ among lactoferrin homologs in mammals. Although considerable attention has been given to the many functions of lactoferrin, its primary nutritional contribution is presumed to be related to its iron-binding characteristics, whereas the role of glycosylation has been neglected. Given the critical role of glycan binding in many biological processes, the glycan moieties in lactoferrin are likely to contribute significantly to the biological roles of lactoferrin. Despite the high amino acid sequence homology in different lactoferrins (up to 99%), each exhibits a unique glycosylation pattern that may be responsible for heterogeneity of the biological properties of lactoferrins. An important task for the production of biotherapeutics and medical foods containing bioactive glycoproteins is the assessment of the contributions of individual glycans to the observed bioactivities. This review examines how the study of lactoferrin glycosylation patterns can increase our understanding of lactoferrin functionality
GENNESYS - Primer Congrés Internacional de Nanotecnologia
Centenars de cientÃfics i polÃtics de tot el món han participat, del 26 al 28 de maig, en el Primer Congrés Internacional GENNESYS de Nanotecnologia i Infraestructures de Recerca. Es tracta del primer esdeveniment a nivell internacional sobre aquest camp, que serà clau en el futur per a la recerca cientÃfica d'alt nivell i per al desenvolupament d'innovacions industrials. El congrés, que ha tingut lloc en el Centre de Convencions Internacional de Barcelona, ha estat organitzat pel Parc de Recerca UAB, l'Institut de Ciència de Materials de Barcelona, l'International Iberian Nanotechnology Laboratory i el Deutsches Elektronen-Synchroton DESY.From 26 to 28 May, hundreds of scientists and politicians around the world have participated at the First International GENNESYS Congress of Nanotechnology and Infrastructure Research. This is the first international event on the field, which will be key in the future for high- level scientific research and development of industrial innovation. The conference, hold in Barcelona International Convention Center, has been organized by the UAB Research Park, the Institute of Materials Science of Barcelona, the International Iberian Nanotechnology Laboratory and the Deutsches Elektronen-Synchroton DESY
In situ measurements of density fluctuations and compressibility in silica glass as a function of temperature and thermal history
In this paper, small-angle X-ray scattering measurements are used to
determine the different compressibility contributions, as well as the
isothermal compressibility, in thermal equilibrium in silica glasses having
different thermal histories. Using two different methods of analysis, in the
supercooled liquid and in the glassy state, we obtain respectively the
temperature and fictive temperature dependences of the isotheraml
compressibility. The values obtained in the glass and supercooled liquid states
are very close to each other. They agree with previous determinations of the
literature. The compressibility in the glass state slightly decreases with
increasing fictive temperature. The relaxational part of the compressibility is
also calculated and compared to previous determinations. We discussed the small
differences between the different determinations
Characterization of recombinant human lactoferrin N-glycans expressed in the milk of transgenic cows.
Lactoferrin (LF) is one of the most abundant bioactive glycoproteins in human milk. Glycans attached through N-glycosidic bonds may contribute to Lactoferrin functional activities. In contrast, LF is present in trace amounts in bovine milk. Efforts to increase LF concentration in bovine milk led to alternative approaches using transgenic cows to express human lactoferrin (hLF). This study investigated and compared N-glycans in recombinant human lactoferrin (rhLF), bovine lactoferrin (bLF) and human lactoferrin by Nano-LC-Chip-Q-TOF Mass Spectrometry. The results revealed a high diversity of N-glycan structures, including fucosylated and sialylated complex glycans that may contribute additional bioactivities. rhLF, bLF and hLF had 23, 27 and 18 N-glycans respectively with 8 N-glycan in common overall. rhLF shared 16 N-glycan with bLF and 9 N-glycan with hLF while bLF shared 10 N-glycan with hLF. Based on the relative abundances of N-glycan types, rhLF and hLF appeared to contain mostly neutral complex/hybrid N-glycans (81% and 52% of the total respectively) whereas bLF was characterized by high mannose glycans (65%). Interestingly, the majority of hLF N-glycans were fucosylated (88%), whereas bLF and rhLF had only 9% and 20% fucosylation, respectively. Overall, this study suggests that rhLF N-glycans share more similarities to bLF than hLF
Dynamic sound attenuation at hypersonic frequencies in silica glass
In order to clarify the origin of the dominant processes responsible for the
acoustic attenuation of phonons, which is a much debatted topic, we present
Bril louin scattering experiments in various silica glasses of different OH
impurities content. A large temperature range, from 5 to 1500 K is
investigated, up to the glass transition temperature. Comparison of the
hypersonic wave attenuation in various samples allows to identify two different
processes. The first one induce s a low temperature peak related to
relaxational processes; it is strongly sensitive to the extrinsic defects. The
second, dominant in the hig h temperature range, is weakly dependent on the
impurities and can be ascribed to anharmonic interactions
Transforming Basic Robotic Platforms into Easily Deployable and Web Remotely Controllable Robots
International audienceThis paper describes a way to transform basic robotic platforms into Web remotely controllable robots. Our goal is to achieve robot deployment anywhere, at anytime, at low-cost. As soon as full or even restricted Internet access is available (WiFi or 3G), the robot can be deployed and Webcontrolled. The distant user can send commands to the robot and monitor the state of the robot. For example, the distant user can make the robot move and get snapshots taken by the robot
Characterization of the glass transition in vitreous silica by temperature scanning small-angle X-ray scattering
The temperature dependence of the x-ray scattering in the region below the
first sharp diffraction peak was measured for silica glasses with low and high
OH content (GE-124 and Corning 7980). Data were obtained upon scanning the
temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements
resolve, for the first time, the hysteresis between heating and cooling through
the glass transition for silica glass, and the data have a better signal to
noise ratio than previous light scattering and differential thermal analysis
data. For the glass with the higher hydroxyl concentration the glass transition
is broader and at a lower temperature. Fits of the data to the
Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very
strong glass. The temperature derivative of the observed X-ray scattering
matches that of light scattering to within 14%.Comment: EurophysicsLetters, in pres
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