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Frasca D, Diaz A, Romero M, Landin AM, Blomberg BB: Age effects on B cells and humoral immunity in humans. Ageing Res Rev 10, 330–335 (2011) Blomberg BB Age effects on B cells and

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References 1. E.G. Lakatta D. Levy 2003 Arterial and cardiac aging: major

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Lakatta, E. G., Levy, D.: Arterial and cardiac aging: major shareholders in cardiovascular disease enterprises. Part I: Aging arteries: a “set up” for vascular disease. Circulation, 2003, 107

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Ageing of wet-synthesized oxide powders

Role of surface carbonation, effect on sintering, restoration

Journal of Thermal Analysis and Calorimetry
Authors: Laura Montanaro, K. Belgacem, P. Llewellyn, F. Rouquerol, F. Merlo, and Paola Palmero

Abstract  

Wet chemical synthesis of precursor oxide ceramics is a method to obtain small particulate powders. Such powders are far more prone to ageing in air than more traditional precursors. Thermogravimetric analysis is used to highlight the species responsible for the ageing of ceramic precursors. Indeed water and carbon dioxide are observed to evolve from aged powders. Ceramics obtained from aged precursors can reach a very low final density with respect to the theoretical value. A large degree of the original sintering properties can be recovered after washing the aged powders with ethanol in a basic medium.

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Az Eurostat előrejelzése szerint az EU27 népességének 45,52%-a lesz 2040-ben 65 év feletti. A nagyarányú nyugdíjaztatások következtében hiány lesz a magasan kvalifikált munkaerőből csaknem valamennyi területen. Amikor 2050-re átlagosan már csak két aktív dolgozó jut egy nyugdíjasra, a jóléti ellátások Európa-szerte drasztikusan hanyatlani fognak, és növekszenek majd az egészségügyi és nyugdíjrendszerek kiadásai. Amennyiben az európai gazdaság az elkövetkező években magához tér, továbbra is szüksége lesz mérnökökre, orvosokra, különféle szakemberekre, akikből máris számos országban súlyos hiány mutatkozik. A problémát súlyosbítja, hogy a felsőoktatás általában nem követi a munkaerőpiac szükségleteit és voltaképpen növeli a fiatal diplomások munkanélküliségét. Az elöregedő európai társadalom szakemberszükségletét várhatóan néhány évtized múlva más forrásokból kell biztosítani, és erre kínálkozik a hatalmassá növekedett indiai felsőoktatás; Indiában ma is mintegy 120-140 millióan beszélnek jól angolul. Azonban az indiai felsőoktatás mai helyzete számos problémát mutat, amelyeket várhatóan az elkövetkező évtizedekben leküzdenek és keletkezik majd ott jól képzett munkaerő, amely bárhol a világon képes munkát vállalni, ehhez azonban arra van szükség, hogy a saját gondjait is megoldó európai felsőoktatás rendszeres és szoros munkakapcsolatot építsen ki az indiai felsőoktatási intézményekkel annak érdekében, hogy kölcsönösen megismerjék az elvárásokat és lehetőségeket.

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Abstract  

Wood protection in exterior use is generally achieved with a stain. This protective product is often obtained from an alkyd resin. A natural and artificial agening have been studied by measuring the glass transition temperature (T g) of the finish variations in terms of time. In both ageings, theT g variations are the same; there is an increase inT g during the first steps of ageing and then a stabilization. A behaviour equation is proposed and is perfectly suitable to both ageings. Time constants are calculated. This equation shows that the artificial ageing machine chosen is a good means of artificial ageing. It allows the reproduction and the acceleration by 10 times of phenomena which are observed during the natural ageing.

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]. Biological ageing is associated with a progressive decrease in cardiac myositis as a result of age-related cardiac diseases [ 27 ]. There is evidence that indicates cardiomyocytes are able to regenerate in the human heart, but this process seems to be very

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Artificial ageing of double base rocket propellant

Effect on dynamic mechanical properties

Journal of Thermal Analysis and Calorimetry
Authors: S. Matečić Mušanić and M. Sućeska

Abstract  

The ageing of double base rocket propellants (DB rocket propellants), which is a consequence of chemical reactions and physical processes that take place over time, has significant effect on their relevant properties (e.g. chemical composition, mechanical properties, ballistic properties, etc.). The changes of relevant properties limit the safe and reliable service life of DB rocket propellants. This is the reason why numerous research efforts are devoted to finding out reliable methods to measure the changes caused by ageing, to assess the quality at a given moment of time, and to predict remaining life-time of DB rocket propellants. In this work we studied dynamic mechanical properties of DB rocket propellant artificially aged at elevated temperatures, in order to detect and quantify changes in dynamic mechanical properties caused by the ageing. Dynamic mechanical properties were studied using dynamic mechanical analyser (DMA). The results obtained have shown that the ageing causes significant changes of DMA curve’s shape and positions. These changes are quantified by following some characteristic points on DMA curves (e.g. glass transition temperatures; storage modulus, loss modulus and tanδ at characteristic temperatures, etc.). It has been found out that the most sensitive parameters to the ageing process are: storage modulus at viscoelastic and softening region, peak width and height on loss modulus curve, glass transition and softening temperature, and tanδ at viscoelastic region.

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Journal of Thermal Analysis and Calorimetry
Authors: E. T. Stepkowska, S. Yariv, J. L. Pérez-Rodríguez, A. Justo, A. Ruiz-Conde, and P. Sánchez-Soto

Abstract

A dredged sludge was studied to investigate the influence of ageing and of pretreatment on its drying rate, water sorption/retention, thermal mass loss, XRD and microstructure (SEM).

Ageing caused change in particle thickness and specific surface, a gradual aggregation to form units of the size 10–50 μm, formation of macropores of similar size, unhomogeneity and fissures between aggregates and “super-aggregates”. Macropores were detectable by the initial drying rate especially at 45°C. They indicated a tendency of collapsing at a lower drying rate at 30°C. This is consistent with SEM observations. With ageing the aggregates were more compact and less sensitive to drying.

The aggregated system indicated a higher initial drying rate (higher permeability), whereas stirring induced a lower drying rate, favouring the formation of compact laminar structure.

XRD peak intensity was lowered with ageing due to decrease in crystallinity (stacking faults and/or decrease in crystallite size). The content of amorphous material was lowered as well, reducing water sorption/desorption, which indicated that the specific surface is lower.

From the suitable microstructure induced by ageing some new phases may form (feldspar, zeolites), preferably in the coarser fraction of the sludge. This is disturbed by stirring which operation expels also carbonates from the particle edges and this may reduce the structural strength of the sludge. In aged bentonite suspension a similar tendency was observed of formation of specific microstructures capable of phase transformation, e.g. to feldspar.

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Abstract  

It is well known that SiO2 -based inorganic-organic hybrid materials present significant differences due to the organic moieties bound to the inorganic network and to the preparation conditions. In the present work the ageing effect on the thermal stability of the SiO2 -based inorganic-organic hybrid materials prepared using tetraethoxysilan (TEOS), triethoxymethylsilan (MTEOS), triethoxyvinylsilan (VTEOS), tetramethoxysilan (TMOS), trimethoxymethylsilan (MTMOS) and trimethoxyvinylsilan (VTMOS) was studied. TG/DTA-MS was used to study the decomposition process of the materials. The structural modifications of the materials during ageing were studied using spectral methods. The gels obtained starting with more reactive alkoxides, of methoxy-type, present more complex structures and are less stable during ageing.

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