A network of vertical static pendulums (tiltmeters) has been in operation in Central Europe since July 2007. Hundred and eighty three seismic events of magnitude 7 and greater have occurred worldwide ...(EMSC) during the ten-year period. Several kinds of tilt anomalies were recognised within days up to months before the mainshocks. The most typical anomaly was a sudden tilting, parallel with the geologic structure, where the pendulum was installed. Based on the observations, we are proposing an asperity model, explaining the generation of so called “stress waves” before the mainshocks. Such stress waves of very low frequency (i.e. periods of days up to the first months) could be detected anywhere on the globe, especially on active geological structures, parallel with the fault, where a mainshock can happen. The observations suggest that we could estimate that part of the global fault system, which generates the detected stress wave, and which reaches the critical state. The estimation can be performed according to the amplitude of the stress wave, compared with stress waves detected on other structures of different orientations. According to the length of the stress wave (its period) and the tilt amplitude, it could be possible to estimate the magnitude of the mainshock.
New crystals of di-µ-methoxido-bis(2-ethylhexanoato-κ
O
)oxido(1,10-phenanthroline-κ
2
N,N
')vanadium(IV), C
42
H
52
N
4
O
8
V
2
, have been synthesized, characterized by elemental analysis, infrared ...spectroscopy, electron paramagnetic resonance and X-ray diffraction analysis. The compound crystallizes in the monoclinic space group
P
2
1
/
c
:
a
= 13.0656(11) Å,
b
= 9.1474(8) Å,
c
= 17.0299(14) Å, β = 94.387(4)°,
Z
= 2,
R
gt
= 0.0617,
wR
(
F
2
) = 0.169,
T
= 150(2) K. The dimeric oxidovanadium(IV) complex consists of two V
IV
O(OCOC
7
H
15
)(phen) units connected with two methanolate bridges. The vanadium atoms have a distorted octahedral environment with four oxygen and two nitrogen atoms. The V=O bond length is 1.601(3) Å; the V–O bond lengths in the symmetrical V
2
O
2
core are 1.973(2) and 2.007(3) Å. The vanadium–oxygen bond lengths in the carboxylate are 1.974(3) Å. The V–N interatomic distances depend on the configuration towards the oxidoligand. Preliminary experiments on solvent-borne alkyd resins revealed promising catalytic activity in the auto-oxidation process.
— Detailed analysis of the fragmentation of the Morávka meteoroid during the atmospheric entry is presented. The analysis is based on the measurement of trajectories and decelerations of fragments ...seen in a video and at the locations of energetic fragmentation events from seismic data obtained at several stations in the vicinity of the fireball trajectory. About 100 individual fragments are seen on video frames. Significant deceleration of the fireball at heights of ˜45 km revealed that the meteoroid had already fragmented into ˜10 pieces with masses of 100–200 kg, though the fireball still appeared as a single object. At heights of 37–29 km, all primary fragments broke‐up again under dynamic pressures up to 5 MPa. The cascade fragmentation then continued, even though smaller pieces breaking off from the larger masses were increasingly decelerated and the dynamic pressure acting upon them decreased. At each fragmentation, a significant part of the mass was lost in the form of dust or tiny particles. This was the dominant process of mass loss. The continuous ablation due to melting and evaporation of the meteoroid surface was less efficient with a corresponding ablation coefficient of only 0.003 s2 km‐2. During fragmentation, some pieces achieved lateral velocities up to 300 m/s, about an order of magnitude more than can be explained by aerodynamic loading. The fragmentation continued even after ablation ceased, as demonstrated by the incomplete fusion crust covering all recovered fragments. We estimate that several hundreds of meteorites of a total mass of ˜100 kg landed, mostly in a mountainous area not suitable for systematic meteorite searches. Six meteorites with a total mass of 1.4 kg were recovered up to the end of May 2003. Their positions are consistent with the calculated strewn field.
The Chelyabinsk superbolide of February 15, 2013, was caused by the atmospheric entry of a ~19 m asteroid with a kinetic energy of 500 kT TNT just south of the city of Chelyabinsk, Russia. It was a ...rare event; impacts of similar energy occur on the Earth only a few times per century. Impacts of this energy near such a large urban area are expected only a few times per 10 000 years. A number of video records obtained by casual eyewitnesses, dashboard cameras in cars, security, and traffic cameras were made publicly available by their authors on the Internet. These represent a rich repository for future scientific studies of this unique event. To aid researchers in the archival study of this airburst, we provide and document a catalog of 960 videos showing various aspects of the event. Among the video records are 400 distinct videos showing the bolide itself and 108 videos showing the illumination caused by the bolide. Other videos show the dust trail left in the atmosphere, the arrival of the blast wave on the ground, or the damage caused by the blast wave. As these video recordings have high scientific, historical, and archival value for future studies of this airburst, a systematic documentation and description of records is desirable. Many have already been used for scientific analyses. We give the exact locations where 715 videos were taken as well as details of the visible/audible phenomena in each video recording. An online version of the published catalog has been developed and will be regularly updated to provide a long–term database for investigators.
This paper deals with the study of properties of anticorrosion pigments of varying chemical composition in epoxyester paints. Two type lines of paints were prepared. The first line comprised an ...anticorrosion pigment with a PVC concentration of 10% while the other line comprised an anticorrosion pigment with a PVC concentration
=
CPVC. The following nontoxic anticorrosion pigments were observed: zinc phosphate, zinc phosphomolybdate, calcium hydrogen phosphate, zinc phosphate modified with an organic corrosion inhibitor, strontium–aluminum polyphosphosilicate, zinc–aluminum polyphosphate, calcium metaborate, calcium ferrite, calcium borosolicate, and strontium chromate. The epoxyester primers were observed for the effect of the type of pigment on the anticorrosion properties. Anticorrosion efficiency was derived from tests in a condenser chamber and in a salt spray cabinet as well as from a test of chemical resistance of pigmented coatings. The evaluation of anticorrosion efficiency of inorganic nonmetal pigments was carried out by means of comparison with anticorrosion efficiency of metal dust.
Talc and muscovite particles were coated with hematite. The aim was to formulate paints with pigments which show the properties of specularite (lamellar hematite) but eliminating the sedimentation of ...the pigment particles in a liquid environment. Model paints based on epoxy-ester resin were prepared. They were subjected to corrosion and mechanical tests. Natural specularite and muscovite were also tested in those paints for comparison.
— The Morávka (Czech Republic) meteorite fall occurred on May 6, 2000, 11:52 UT, during the daytime. Six H5–6 ordinary chondrites with a total mass of 1.4 kg were recovered. The corresponding ...fireball was witnessed by thousands of people and also videotaped by 3 casual witnesses. Sonic booms were recorded by 16 seismic stations in the Czech Republic and Poland and by one infrasonic station in Germany. A total of 2.5% of the fireball eyewitnesses reported electrophonic sounds. Satellites in Earth orbit detected part of the fireball light curve.
In this first paper from a series of 4 papers devoted to the Morávka meteorite fall, we describe the circumstances of the fall and determine the fireball trajectory and orbit from calibrated video records. Morávka becomes one of only 6 meteorites with a known orbit. The slope of the trajectory was 20.4° to the horizontal, the initial velocity was 22.5 km/s, and the terminal height of the fireball was 21 km. The semimajor axis of the orbit was 1.85 AU, the perihelion distance was 0.982 AU, and the inclination was 32.2°. The fireball reached an absolute visual magnitude of −20 at a height of 33 km.
Purpose - To investigate the properties of coatings containing various types of fillers from the point of view of their physical-mechanical properties and anticorrosive properties.Design methodology ...approach - Research used fillers of different types varying in morphology and or chemical composition; these were then compared with selected pigments and zinc phosphate, an anticorrosive pigment. The following parameters were observed for all of the fillers and pigments: oil absorption, CPVC value, density, extract pH, specific surface, particle size, and water-soluble substances. The morphology of particles was observed by means of an electron-scanning microscope. The coatings of these fillers and pigments were formulated on an epoxy resin binder basis cured with a polyamine hardener. The coatings prepared were subjected to the measurement of physical-mechanical properties such as hardness and deepening resistance, flex resistance, adhesion to steel, and the gloss of the coatings. The coatings containing the fillers and pigments studied underwent corrosion tests in a condenser chamber and in a salt-spray cabinet.Findings - The results obtained through the tests allowed the selection of the optimum filler for an epoxy coating with barrier anticorrosive properties. As per respective findings, some fillers in these coatings of significant thickness can be comparable to their zinc phosphate counterparts.Research limitations implications - The anticorrosive properties of the coatings studied can also be tested in paints by means of atmospheric exposure, for instance, with the aid of a Florida test.Practical implications - The findings are helpful towards applications in the formulations of anticorrosive coatings of significant thickness that offer an effective barrier mechanism.Originality value - The research presents the results of the properties of a whole range of industrially employed fillers and pigments contained in paints. Based on this study, the formulation of steel protecting coatings can be optimised.
We analyze the possible effect of solid Earth tidal stresses upon a vertical strike-slip fault in NW-Bohemia/Vogtland, central Europe, typical by occurrence of swarm earthquakes. The horizontal ...components of solid Earth tidal stresses were found strongly to prevail and to reach the level of 2 kPa. We examined tidal triggering as influence of tidal stresses to launching the swarm activity in relative absence of other stress disturbances. The onset times of 46 swarms of mostly
M
L
<
3 earthquakes that occurred in the period 1991–2005 displayed an increased occurrence near the fortnightly maximum of tidal extensive normal stress. The statistical test however did not prove a statistically significant correlation indicating a triggering effect of fault extension due to tidal loading. We also examined tidal effects to the already running seismic activity of the prominent 2000 swarm by comparing the tidal stress distribution in the investigated period with the distribution of tidal stresses in the occurrence times of each earthquake. The results show that these distributions are almost similar, which indicates that individual earthquakes occur independent of tidal stresses. The unclear tidal correlation of the swarm seismicity may be interpreted by small amplitudes and rates of tidal stress changes compared to the amplitudes and rates of coseismic stress perturbations and of pressure bursts of deep generated fluids.
We report the thorough study on glass forming ability and properties of the TeO2-ZnO-BaO (TZB) optical glasses prepared by the melt-quenching method at 900 °C. The attention has been paid to ...investigation of thermal, structural, and optical properties of glasses with content of TeO2 from 52.5 up to 90%. The introduction of ZnO and/or BaO into TeO2-based glass results in increase of the glass transition temperature Tg from 319 to 369 °C and decrease of the refractive index and density of prepared glasses. The structure of studied TZB glasses was investigated by Raman scattering. Since the TZB glasses exhibit good thermal stability, wide spectral region of transparency from ultraviolet (UV), λ ≈ 0.35 μm, up to mid-infrared (MIR), λ ≈ 6 μm, wavelengths with high values of refractive index (n1550 ≈ 1.87–2.04), they may be utilized as optical materials, which can be designed on the results presented in this paper.
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