THE ORIGIN OF MARCHING MODULUS OF SILICA-FILLED TIRE TREAD COMPOUNDS

ABSTRACT Silica-reinforced S-SBR/BR tire tread compounds often show characteristic vulcanization profiles that do not exhibit a distinct maximum in the cure curve nor a plateau profile within acceptable time scales (marching modulus). In such a situation, it is difficult to determine the optimum curing time, and as a consequence, the physical properties of the rubber compounds may vary. Previous studies stated that the curing behavior of silica-filled rubber compounds is related to the degree of filler dispersion, the silanization, and the filler–polymer coupling reaction, as well as to the donation of free sulfur from the silane coupling agent. Such results imply that these are the key factors for minimization of the marching modulus. Various silane coupling agents with different sulfur ranks and functionalities were mixed at varied silanization temperatures. The correlation between these factors and their effect on the marching modulus intensity (MMI) were investigated. The MMI was monitored by measuring the vulcanization rheograms using a rubber process analyzer at small (approximately 7%) and large (approximately 42%) strains to discriminate the effects of filler–filler and filler–polymer interactions on the marching modulus of the silica-filled rubber compounds. Both factors have an intricate influence on the marching modulus, determined by the degree of filler–filler interaction and the coupling agent.

Satellite-Based Characterization of Convective Growth and Glaciation and Its Relationship to Precipitation Formation over Central Europe

The growth phase of convective storms and their transition to maturity is investigated based on more than 100 cases selected from the years 2012–14 over central Europe. Dynamical growth properties as well as cloud-top glaciation and microphysical characteristics are derived from the SEVIRI imaging radiometer aboard the geostationary Meteosat satellites. In addition, onset and intensity of surface precipitation are related to growth and glaciation processes using observations from the radar network of the German Weather Service. The majority of analyzed cases shows a distinct maximum in cloud-top cooling rate, which is used here for temporal synchronization. Cloud growth spans a period of approximately half an hour. Glaciation rate indicators suggest that freezing 15 min prior to the maximum cooling plays an important role in invigorating convective updrafts through the release of latent heat. Smaller ice particles are found for larger cloud-top cooling, which provides observational evidence that ice particles form later and have less time to grow in stronger convective updrafts. Furthermore, maximum cloud-top height, anvil expansion rate, maximum precipitation intensity, and core size are found to be positively correlated. With respect to the onset of precipitation, this analysis shows a high probability that significant precipitation already occurs 30 min prior to maximum cloud-top cooling.

The Correlations between Dynamic Interactions in Antiferromagnetic Multiferroics

In this work we have researched the features of dynamic magnetoelectric and magnetoelastic interactions in multiferroic crystal, influenced by various external fields, with the group of symmetry . Based on the integrated approach, which combines N. N. Bogolyubov’s quantum-statistic methods, Green’s temperature functions, diagram technique and symmetry, energy spectrum’s and static spin susceptibility’s dependences on the temperature and external fields were calculated. The effective parameters of magnetoelectric and magnetoelastic interactions dependences on the external fields’ intesities were analysed. It is shown that these parameters have a distinct maximum in the resonance value. As was shown, it is possible to enhance the interactions between spins, ferroelectric and fonons subsystems in multiferroics by applicating the external fields in different crystallographic directions.

Electro-Optic Tuneable of Direct Current Voltage in Ring Resonator

In this paper, a new design of the electro-optical tuning voltage in buried fiber ring resonator (BFRR) system is proposed. The crystals of LiNbO3, (Ba, Sr)TiO3, K(Ta, Nb)O3 and KH2PO4 are used as electro-optic core materials. The applied voltage can generate different refractive index deformation when used different electro-optic crystals. Different electro-optic crystals produce distinct maximum power loss within BFRR. The power loss in an electro-optic crystal can be controlled by tuning the applied voltage. The K(Ta, Nb)O3 crystal produce maximum power loss with lower voltage compared to other crystals.

Shape and size of Antarctic icebergs derived from ship observation data

We have examined information on the shape and size of Antarctic icebergs as derived from the ship data archive of Arctic and Antarctic Research Institute. The data in the archive cover the period from 1957–2009. For each of five major iceberg shapes we have established their relative frequency of occurrence in the Southern Ocean and the frequency distribution of the iceberg length and freeboard. Weathered and tabular icebergs were observed most often and comprised 66.9% and 22.6% of all reported icebergs respectively. Sloping, pinnacle, and dome icebergs represented correspondingly only 5.6%, 3.2% and 1.7% of the total number of icebergs observed. A distinct maximum was found in frequency distributions of the iceberg length and freeboard for all iceberg shapes. The most frequently observed iceberg lengths (modal length) ranged from 100–200 m for weathered and pinnacled icebergs to 400–600 m for tabular and dome-shaped iceberg. The modal freeboard of icebergs changed from 30–40 m for tabular and weathered icebergs to 50–60 m for domed, pinnacle and sloping icebergs. To calculate the overall mean size parameters of Antarctic icebergs we totalled corresponding mean values for each iceberg shape weighted by the frequency of occurrence of icebergs of each shape. The mean iceberg length and the standard deviation obtained within this approach were correspondingly 381 m and 349 m. The mean iceberg freeboard was equal to 41.2 m with a standard deviation of 12.1 m.

Oxidation Protection of Titanium Aluminides and Ni-Base Superalloys at High Temperatures by the Halogen Effect – Principles and Applications

The oxidation protection of TiAl-alloys at temperatures above 750°C can be improved by the fluorine effect. The results of thermodynamical calculations predict a corridor for a positive fluorine effect. Ion implantation of F was performed because of giving the best results. After a high F-loss during heating a thin protective alumina scale acts as a diffusion barrier. The F-depth profiles show a distinct maximum at the metal/oxide interface. The diffusion coefficient of F in TiAl for 900°C was determined. The stability of the F-effect after long oxidation time at 900°C and 1000°C can be explained by the existence of a constant F-amount at the metal/oxide interface ensuring a slow growth of the alumina scale. The fluorine effect was also applied to Ni-base superalloys to improve their high temperature oxidation resistance by forming a dense continuous protective alumina scale.

Spring ammonium maximum in the mid-depth layer of Lake Biwa, JapanA paper submitted to the Journal of Environmental Engineering and Science.

The spatio-temporal variation in ammonium-nitrogen (NH4-N) profiles was investigated in the North Basin of Lake Biwa in 2002, 2004, and 2005 and in the Uso River in 2004–2005. The in-lake concentration of NH4-N was low throughout the water column, except between late April and mid-June, when a distinct maximum developed between 10 and 25 m depth, in and below the thermocline. This layer extended offshore from both east and west boundaries to the center of the lake. By comparing water temperature estimates from the Uso River with water temperatures measured in the lake, we hypothesize that cooler water intrudes into the lake during the night at depths between 8 and 28 m. The intrusions are likely more pronounced from mid to late May when the NH4-N concentration in the Uso River is highest. This suggests that riverine input is an important factor in the formation of the mid-depth ammonium maximum in Lake Biwa. These findings underscore the importance of fluvial discharge and lateral transport of dissolved nutrients in temperate lakes.

Temporal and Spatial Growth of Wind Waves

A solution of Rayleigh’s instability equation, which circumvents the apparent critical-layer singularity, is provided. The temporal and spatial growth rates of water waves exposed to a logarithmic wind profile are calculated and discussed. The findings are similar to previously published results, except for shear velocity–to–wave celerity ratios larger than 2, where the newly calculated growth rates start to decrease after having reached a distinct maximum. The ratio of the spatial to temporal growth rates is examined. It is shown to deviate by up to 20% from the leading-order value of 2. The implications of the growth rate to the modal distributions of energy input from wind to waves, for young and mature seas, and in temporal/spatial growth scenarios, are analyzed.

Topochemical investigation on phenolic deposits in the vessels of afzelia (Afzelia spp.) and merbau (Intsia spp.) heartwood

The topochemical distribution of phenolic deposits in the vessels of afzelia (Afzelia spp.) and merbau (Intsia spp.) heartwood was investigated by means of cellular UV microspectrophotometry (UMSP) to characterise the chemical composition and synthesis by pit membrane-associated enzymes. UV absorbance spectra of the deposits attached to the vessel walls of merbau are characterised by a distinct maximum at a wavelength of 368 nm representing the UV absorbance of pure robinetin (C15H10O7). Deposits in the vessels of afzelia display a typical spectrum of kaempferol (C15H10O2) with two distinct maxima at 270 and 350 nm. The pit membranes and pit canals of associated vessel and parenchyma cells are impregnated by these compounds. These results verify the assumption that the synthesis of deposits in afzelia and merbau is regulated by pit membrane-associated enzymes.

Microstructural Aspects of the Ionic Transport Properties of Strontium-Substituted Lanthanum Cobaltites

ABSTRACTThe ionic conductivity and microstructure of selected compositions of the solid solution La1-xSrxCoO3-δ (LSC) were examined with respect to possible vacancy ordering phenomena. Homogeneous samples of LSC were prepared by the glycine nitrate process. The ionic conductivity was obtained as a function of the oxygen partial pressure (-3.5 ≤ log[p(O2)/atm] ≤ 0.5) using a recently developed galvanostatic polarization technique. At 825°C the p(O2)-dependence of the ionic conductivity of La1-xSrxCoO3-° (x = 0.4 and 0.6) shows a distinct maximum. Although this behavior has yet to be explained unambiguously it is indicative of decreasing mobility of ionic charge carriers, e. g. due to cooperative vacancy ordering. From the temperature dependence of the ionic conductivity of La1-xSrxCoO3-° (x = 0.6) activation energies at constant nonstoichiometry (0.20 ≤ ° ≤ 0.28) were obtained. As vacancy association and microstructure are presumed to play a significant role we combined the results of ionic conductivity measurements and electron microscopical investigations. HRTEM images revealed a superstructure within microdomains of about 100 nm in size.