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1.
2.
T. G. Sitnik 《Astronomy Reports》2010,54(4):317-326
Using the results of our Hα interferometric observations and observational data on the 21 cm and CO lines, we have analyzed the structure and kinematics
of the interstellar medium in the extended vicinity of the star WR 137 and the supernova remnants CTB 87 and G73.9+0.9. A
shell structure with a radius of up to 40′ observable in optical lines has been discovered around WR 137. The high-velocity
motions of ionized hydrogen inside this shell can be interpreted as expansion of the gas swept out by the wind of WR 137 at
velocities of up to 60 km/s. The ionized hydrogen near WR 137 emits at the systematic velocity V
LSR ∼ 6–18 km/s. The expansion ofG73.9+0.9 at a velocity of up to 55 km/s has been confirmed. The systematic velocities of the
ionized hydrogen toward this supernova remnant are V
LSR ≃ −14…+14 km/s. An HI shell around G73.9+0.9 has been detected at velocities V
LSR≃−14…−8 km/s. A very faint optical shell of CTB 87 with a size of about 20′ has also been detected. Evidence that CTB 87 is
located in the Cygnus Arm is presented. 相似文献
3.
Observations at 44 GHz in the 70−61
A
+ methanol line have been carried out on the 20-m telescope of the Onsala Space Observatory (Sweden) in the directions of the
poorly studied region G27.4–0.2 and of several supernova remnants, at the coordinates of the OH(1720) maser satellite emission,
with the aim of searching for Class I methanol maser emission in these sources. The region G27.4–0.2 has beenmapped, and contains
maser sources and two supernova remnants with similar coordinates and radial velocities, which may accelerate condensation
of the ambient gas-dust medium. This may play a role in enhancing the probability of methanol formation and maser emission.
This is the first detection of 44 GHz maser emission in this source, and this maser is among the 10% of the strongest Class
I methanol masers, within the uncertainties in the integrated flux (of a total of 198 currently knownmasers). A 27′ × 27′
region around the maser has been mapped at 44 GHz in steps of 1′. The 44-GHz emission forms only within the previously known
maser region. Further studies in water lines are needed to estimate the influence of shocks from supernovae. No 44-GHz Class
I methanol maser emission was detected at the 3σ level at the coordinates of the OH(1720) satellite emission in six supernova remnants; i.e., the presence of OH(1720) emission
is not a sufficient condition for the detection of Class I methanol masers. 相似文献
4.
G. K. Ustinova 《Geochemistry International》2011,49(6):555-567
Anomalous Xe enriched in both heavy and light isotopes (Xe-HL) was identified in the high-temperature Xe fraction in relict nanodiamond grains from chondrites, whereas the low-temperature
Xe fraction (Xe-P3) typically has the normal isotopic composition. The paper presents a concise review of current models put forth to account
for the genesis of nanodiamond with anomalous noble gas components and specifies a real process and major regularities during
the generation of the isotopic relations of the anomalous Xe-HL component in relict nanodiamond grains. This component is demonstrated to be formed and captured simultaneously with the
synthesis of nanodiamond, when shock waves induced by supernova explosions propagated. It is important that diamond synthesis
during the passage of shock waves and the enrichment of this diamond in Xe-HL are also possible in the wave forefront region under extremal P-T conditions, in the pressure drop region behind the wave front (by means of nucleation), and by means of irradiation of carbonic
grains with high-energy particles. The isotopic composition of Xe-HL results from an increase in the hardness of the spectrum of nuclear-active particles and its enrichment in heavy ions at
acceleration in shock waves. Arguments are presented in support of the hypothesis that the nanodiamond population found in
chondrites was produced during the latest supernova explosion before the development of the Solar System, with the supernova
likely being a SnIa carbon detonation supernova. This furnishes evidence in support of recently advanced hypotheses that the
nanodiamond population of chondrites is not presolar. 相似文献
5.
A supernova explosion in a close binary system in which one of the components is a compact magnetized object (neutron star or white dwarf) can form a narrow “tail” with length l t ～109 cm, width h t ～108 cm, and magnetic field B t ～106, due to the resulting shock wave flowing around the magnetosphere of the compact object. The energy released by the reconnection of magnetic field lines in this tail can accelerate electrons to relativistic speeds (γ≈104), creating the conditions required for powerful synchrotron radiation at energies from hundreds of keV to several MeV, i.e., for a gamma-ray burst (GRB). The duration of this radiation will depend on the power of the shock that forms during the supernova. If the shock is not sufficiently powerful to tear off the magnetosphere tail from the compact object, the duration of the GRB will not exceed l t /V A ≤1 s, and the conditions necessary for an “afterglow” at softer energies will not arise. If the shock is more powerful, the tail can be torn from the magnetosphere, forming a narrow ejection, which is perceived in its relativistic motion toward the observer(Γ～104) as an afterglow whose duration grows from tens of seconds at gamma-ray energies to tens of days in the optical. This may explain why afterglows are observed only in association with long GRBs (T 90>10 s). Very short GRBs (T 90<0.1 s) may be local, i.e., low-power, phenomena occurring in close pairs containing compact, magnetized objects, in which there is again an interaction between the magnetosphere of the compact object and a shock wave, but the shock is initiated by a flare on the companion, which is a red-dwarf cataclysmic variable, rather than by a supernova. 相似文献
6.
Hongwu Xu Yusheng Zhao Sven C. Vogel Donald D. Hickmott Luke L. Daemen Monika A. Hartl 《Physics and Chemistry of Minerals》2010,37(2):73-82
The structure of deuterated jarosite, KFe3(SO4)2(OD)6, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals
that with increasing temperature, its c dimension expands at a rate ~10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH)6] octahedra and [SO4] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion,
α = α0 + α1
T, where α0 = 1.01 × 10−4 K−1 and α1 = −1.15 × 10−7 K−2. On heating, the hydrogen bonds, O1···D–O3, through which the (001) octahedral–tetrahedral sheets are held together, become
weakened, as reflected by an increase in the D···O1 distance and a concomitant decrease in the O3–D distance with increasing
temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well
as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together. 相似文献
7.
The pulsar PSR B2111+46 has been observed at 112 MHz, and a new approach to analyzing pulsar pulses scattered in turbulent
interstellar plasma applied. This method is based on the dependence of the normalized energy in the trailing part of a pulse
on the intrapulse time. Since the trailing edge of a pulse follow exponential law to high accuracy, the inner turbulence scale
of the interstellar plasma exceeds the field coherence scale. The measured scattering parameter is τ
sc
= 147 ± 1 ms. Analysis of the parameters of diffractive and refractive scintillations of the pulsar at 610 MHz together with
the 112 MHz data shows that the spectrum of the interstellar plasma toward PSR B2111+46 is a piecewise power law: on scales
of 1013–1014 cm, the exponent of the turbulence spectrum is n ≃ 4, whereas n = 3.5 on scales of 2 × 108−1013 cm. The spectrum flattens with approach to the inner turbulence scale l: n = 3–3.2. The obtained inner turbulence scale is l = (3.5 ± 1.5) × 107 cm. The distribution of the interstellar plasma toward the pulsar is close to statistically homogeneous. The local density
(N
e
= 0.4 cm−3) and filling factor (F = 0.04) of the interstellar plasma have been estimated. The similarity of N
e
estimates obtained from the inner scale of the inhomogeneities and the ratio of the emission measure to the dispersion measure
provides evidence that the inner turbulence scale corresponds to the ion inertial length. 相似文献
8.
V. G. Krivovichev M. V. Charykova O. S. Yakovenko W. Depmeier 《Geology of Ore Deposits》2011,53(7):514-527
The behavior of selenium at the Earth’s surface and nearby at low temperatures and pressures is controlled by variations of
the redox potential and the acidity of solutions. These parameters determine the migration of selenium and its precipitation
as various solid phases. Understanding the mechanism of selenium’s behavior under surface conditions, which is important for
solving environmental problems, is an urgent task of contemporary mineralogy and geochemistry. The activities of components
in natural waters beyond the zones of natural (oxidation zones) and man-made contamination with selenium (a
ΣSe = 10−9, a
ΣFe = 10−5, a
ΣCu = 10−7, a
ΣZn = 5 × 10−7, a
ΣCo = 10−8, a
ΣNi = 6 × 10−8, a
ΣPb = 10−8) and in waters formed in the oxidation zone (a
ΣSe = 10−5–10−4, a
ΣFe = 10−2, a
ΣCu = 10−2, a
ΣZn = 5 × 10−2, a
ΣCo = 10−3, a
ΣNi = 10−2, a
ΣPb = 10−4) have been estimated. Eh-pH diagrams were calculated and plotted using the Geochemist’s Workbench (GMB 7.0) software package.
The database comprises the thermodynamic parameters of 46 elements, 47 main particles, 48 redox pairs, 551 particles in solution,
624 solid phases, and 10 gases. The Eh-pH diagrams of the Me-Se-H2O systems (Me = Co, Ni, Fe, Cu, Zn, Pb) were plotted for the average contents of these elements in underground water and for
their contents in oxidation zones of sulfide deposits. The formation of Co, Ni, Fe, Cu, Zn, and Pb selenites and selenates
at the surface is discussed. 相似文献
9.
M. V. Charykova V. G. Krivovichev O. S. Yakovenko W. Depmeier 《Geology of Ore Deposits》2011,53(7):501-513
The behavior of arsenic at the Earth’s surface and nearby at low temperatures and pressures depends mainly on the redox potential
and the acidity-alkalinity of the crystallization media. These parameters determine the migration of arsenic compounds and
their precipitation as various solid phases. Understanding the mechanism of arsenic’s behavior under surface conditions, which
is important for solving environmental problems, is an urgent task of contemporary mineralogy and geochemistry. The activities
of the components in natural waters beyond the zones of natural (oxidation zones) and man-made contamination with arsenic
(a
ΣAs = 3 × 10−8, a
ΣFe = 10−5, a
ΣCu = 10−7, a
ΣZn = 5 × 10−7, a
ΣCo = 10−8, a
ΣNi = 6 × 10−8, a
ΣPb = 10−8) and in waters formed in the oxidation zone (a
ΣSe = 10−3, a
ΣFe = 10−2, a
ΣCu = 10−2, a
ΣZn = 5 × 10−2, a
ΣCo = 10−3, a
ΣNi = 10−2, a
ΣPb = 10−4) have been estimated. Eh-pH diagrams were calculated and plotted using the Geochemist’s Workbench (GMB 7.0) software package.
The database comprises the thermodynamic parameters of 46 elements, 47 main particles, 48 redox pairs, 551 particles in solution,
624 solid phases, and 10 gases. The Eh-pH diagrams of the Me-As-H2O systems (Me = Co, Ni, Fe, Cu, Zn, Pb) were plotted for the average contents of these elements in the underground water and
for their higher contents in the oxidation zones of sulfide deposits. The formation of Co, Ni, Fe, Cu, Zn, and Pb arsenates
at the surface is discussed. 相似文献
10.
T. G. Sitnik 《Astronomy Reports》2011,55(7):616-621
The structure and kinematics of the ISM in an extended vicinity of the star WR 139 is analyzed using the results of original
Hα interferometric observations together with radio and infrared data. A CO cavity with a size of up to 40′ has been detected
around the star at velocities of V
LSR ∼ 2.5–10 km/s; the cavity is bounded to the North by a shell radiating in the optical. Ionized hydrogen emits at the systematic
velocities V
LSR ∼ 6–14 km/s toward the CO cavity, and at V
LSR ≃ 4–11 km/s toward the shell. High-velocity motions of ionized hydrogen inside the cavity testify to the probable expansion
of gas that has been swept out by the stellar wind of WR 139 at velocities of up to 60–80 km/s. 相似文献
11.
Magnesium, potassium and calcium isotope compositions in terrestrial samples and refractory phases from primitive meteorites
are determined using an ion microprobe. A thorough investigation of the different instrument parameters is carried out to
ensure that conditions necessary for high mass resolution and high precision isotopic studies are adequately satisfied. The
instrument can be tuned to achieve mass resolution (M/ΔM) of up to 10,000 (M≤60); it has a very good dynamic stability (ΔB/B≤10
ppm over durations of ≤40 minutes) and the counting system has an effective dead-time of ≤25 nsec and a dynamic background
of ≤0·01 c/s. Reproducibility and precision of isotopic measurements are checked by analyzing magnesium and titanium isotopic
compositions in terrestrial standards and isotopically doped silicate glasses. A precision of 2‰ (2σ
m
) was achieved during magnesium isotopic analysis in samples with low Mg content (200 ppm). Results from studies of magnesium
and potassium isotopic compositions in several Ca−Al-rich refractory inclusions (CAIs) from the primitive meteorites Efremovka
and Grosnaja, representing some of the early solar system objects, are presented. The well-behaved Mg−Al isotopic systematics
confirm the pristine nature of the Efremovka CAIs inferred earlier from petrographic and trace element studies. The Grosnaja
CAIs that have experienced secondary alterations show disturbed magnesium isotopic systematics. Observation of excess26Mg in several of the analyzed CAIs confirms the presence of the now extinct26Al (t
1/2=7×105 years) in the solar nebula at the time of CAI formation. Our data also suggest a relatively uniform distribution of26Al in the solar nebula. Several Efremovka CAIs with excess26Mg also have excess41K resulting from the decay of41Ca (t
1/2≃105 years). This observation constrains the time interval between cessation of nucleosynthetic input to the solar nebula and
the formation of some of the first solar system solids (CAIs) to less than a million years. 相似文献
12.
The locations of sites of primary energy release of solar flares are studied. Magnetic singularities revealed earlier—self-intersections
(reconnections) of F = 0 surfaces, where F is a differential factor determining the structural singularity in a potential magnetic field—are considered as possible
sites of energy release. Six flare events demonstrating paired sources of non-thermal hard X-rays emission observed on March
17, 2002, July 17, 2002, April 6, 2004, November 4, 2004, November 6, 2004, and December 1, 2004 are analyzed for probable
singularities. In each event analyzed, each source of non-thermal hard X-rays emission can be associated with an individual
magnetic singularity; in other words, there is a magnetic-field line passing near the singularity and ending near (i.e. within
about 10″) the source located on the photosphere (in the chromosphere). For the homologous flares observed on November 4 and
6, 2004, the same magnetic singularity is responsible for the source of non-thermal hard X-rays emission observed in the eastern
sector of the flare region on November 4 and the source observed in the western part on November 6. A proposed interpretation
associates these observations with a reversal of the electric field generated in the magnetic singularity on November 6, compared
with the electric field generated on November 4, attributed to corresponding changes occurring in the photospheric magnetic
field. 相似文献
13.
P. Linsalata H. J. Simpson C. R. Olsen N. Cohen R. M. Trier 《Environmental Geology》1985,7(4):193-204
Isotopes of plutonium (Pu), cesium (Cs), and cobalt (Co) introduced into the Hudson River Estuary from fallout deposition,
the erosion of fallout-contaminated surface soils, and nuclear reactor effluent (isotopes of Cs and Co only) have been measured
in water column samples collected from 1975 to 1980 Isotopic measurements conducted independently by two research groups utilizing
different sampling and analytical techniques have been summarized. The major conclusions drawn from the work are that for
water samples collected by the two laboratories over similar time periods, the mean concentrations of nonfilterable239,240Pu (<0.45 μm) were identical at 0.13 fCi/l, mean concentrations of both137Cs and239,240Pu in suspended particulates were more divergent at 2,270±920 pCi/kg (±1 SD) and 1,430±430 pCi/kg for137Cs, and 19±8 pCi/kg and 12±4 pCi/kg for239,240Pu
The behavior of239,240Pu and137Cs within the water column is shown to diverge within brackish waters Specifically, the magnitude of the137Cs distribution coefficient (K
d
) can be expressed as an inverse power function of the chloride ion concentrations for chlorinities between 0.1 and 4 g Cl−/l No difference in the239,240PuK
d
has been observed between fresh and brackish waters
Based on the expected inventories of239,240Pu and137Cs within watershed soils, the current downstream transport of these radionuclides represents fractional mobilization rates
on the order of 1–4 (×10−4) per year 相似文献
14.
G. Diego Gatta Marco Merlini Hanns-Peter Liermann André Rothkirch Mauro Gemmi Alessandro Pavese 《Physics and Chemistry of Minerals》2012,39(5):385-397
The thermoelastic behavior of a natural clintonite-1M [with composition: Ca1.01(Mg2.29Al0.59Fe0.12)Σ3.00(Si1.20Al2.80)Σ4.00O10(OH)2] has been investigated up to 10 GPa (at room temperature) and up to 960°C (at room pressure) by means of in situ synchrotron
single-crystal and powder diffraction, respectively. No evidence of phase transition has been observed within the pressure
and temperature range investigated. P–V data fitted with an isothermal third-order Birch–Murnaghan equation of state (BM-EoS) give V
0 = 457.1(2) ?3, K
T0 = 76(3)GPa, and K′ = 10.6(15). The evolution of the “Eulerian finite strain” versus “normalized stress” shows a linear positive trend. The
linear regression yields Fe(0) = 76(3) GPa as intercept value, and the slope of the regression line leads to a K′ value of 10.6(8). The evolution of the lattice parameters with pressure is significantly anisotropic [β(a) = 1/3K
T0(a) = 0.0023(1) GPa−1; β(b) = 1/3K
T0(b) = 0.0018(1) GPa−1; β(c) = 1/K
T0(c) = 0.0072(3) GPa−1]. The β-angle increases in response to the applied P, with: βP = β0 + 0.033(4)P (P in GPa). The structure refinements of clintonite up to 10.1 GPa show that, under hydrostatic pressure, the structure rearranges
by compressing mainly isotropically the inter-layer Ca-polyhedron. The bulk modulus of the Ca-polyhedron, described using
a second-order BM-EoS, is K
T0(Ca-polyhedron) = 41(2) GPa. The compression of the bond distances between calcium and the basal oxygens of the tetrahedral
sheet leads, in turn, to an increase in the ditrigonal distortion of the tetrahedral ring, with ∂α/∂P ≈ 0.1°/GPa within the P-range investigated. The Mg-rich octahedra appear to compress in response to the applied pressure, whereas the tetrahedron
appears to behave as a rigid unit. The evolution of axial and volume thermal expansion coefficient α with temperature was
described by the polynomial α(T) = α0 + α1
T
−1/2. The refined parameters for clintonite are as follows: α0 = 2.78(4) 10−5°C−1 and α1 = −4.4(6) 10−5°C1/2 for the unit-cell volume; α0(a) = 1.01(2) 10−5°C−1 and α1(a) = −1.8(3) 10−5°C1/2 for the a-axis; α0(b) = 1.07(1) 10−5°C−1 and α1(b) = −2.3(2) 10−5°C1/2 for the b-axis; and α0(c) = 0.64(2) 10−5°C−1 and α1(c) = −7.3(30) 10−6°C1/2for the c-axis. The β-angle appears to be almost constant within the given T-range. No structure collapsing in response to the T-induced dehydroxylation was found up to 960°C. The HP- and HT-data of this study show that in clintonite, the most and the less expandable directions do not correspond to the most and
the less compressible directions, respectively. A comparison between the thermoelastic parameters of clintonite and those
of true micas was carried out. 相似文献
15.
Hydraulic properties of the crystalline basement 总被引：1，自引：1，他引：1
Hydraulic tests in boreholes, up to 4.5 km deep, drilled into continental crystalline basement revealed hydraulic conductivity
(K) values that range over nine log-units from 10−13−10−4 m s−1. However, K values for fractured basement to about 1 km depth are typically restricted to the range from 10−8 to 10−6 m s−1. New data from an extended injection test at the KTB research site (part of the Continental Deep Drilling Program in Germany)
at 4 km depth provide K=5 10−8 m s−1. The summarized K-data show a very strong dependence on lithology and on the local deformation history of a particular area. In highly fractured
regions, granite tends to be more pervious than gneiss. The fracture porosity is generally saturated with Na–Cl or Ca–Na–Cl
type waters with salinities ranging from <1 to >100 g L−1. The basement permeability is well within the conditions for advective fluid and heat transport. Consequently, fluid pressure
is hydrostatic and a Darcy flow mechanism is possible to a great depth. Topography-related hydraulic gradients in moderately
conductive basement may result in characteristic advective flow rates of up to 100 L a−1 m−2 and lead to significant advective heat and solute transfer in the upper brittle crust.
An erratum to this article can be found at 相似文献
16.
On February 13, 1981 a relatively strong earthquake occurred in the Lake Vänern region in south-central Sweden. The shock had a magnitude ofML = 3.3 and was followed within three weeks by three aftershocks, with magnitudes 0.5 ≤ ML ≤ 1.0. The focal mechanism solution of the main shock indicates reverse faulting with a strike in the N-S or NE-SW direction and a nearly horizontal compressional stress. The aftershocks were too small to yield data for a full mechanism solution, but first motions of P-waves, recorded at two stations, are consistent for the aftershocks. Dynamic source parameters, derived from Pg- and Sg-wave spectra, show similar stress drops for the main shock (2 bar) and the aftershocks (1 bar), while the differences in seismic moment (1.5·1020 resp. 4·1018dyne cm), fault length (0.7 resp. 0.2 km) and relative displacement (0.15 resp. 0.03 cm) are significant. 相似文献
17.
This paper presents the computation of time series of the 22 July 2007 M 4.9 Kharsali earthquake. It occurred close to the Main Central Thrust (MCT) where seismic gap exists. The main shock and
17 aftershocks were located by closely spaced eleven seismograph stations in a network that involved VSAT based real-time
seismic monitoring. The largest aftershock of M 3.5 and other aftershocks occurred within a small volume of 4 × 4 km horizontal extent and between depths of 10 and 14 km.
The values of seismic moment (M
∘) determined using P-wave spectra and Brune’s model based on f
2 spectral shape ranges from 1018 to 1023 dyne-cm. The initial aftershocks occurred at greater depth compared to the later aftershocks. The time series of ground motion
have been computed for recording sites using geometric ray theory and Green’s function approach. The method for computing
time series consists in integrating the far-field contributions of Green’s function for a number of distributed point source.
The generated waveforms have been compared with the observed ones. It has been inferred that the Kharsali earthquake occurred
due to a northerly dipping low angle thrust fault at a depth of 14 km taking strike N279°E, dip 14° and rake 117°. There are
two regions on the fault surface which have larger slip amplitudes (asperities) and the rupture which has been considered
as circular in nature initiated from the asperity at a greater depth shifting gradually upwards. The two asperities cover
only 10% of the total area of the causative fault plane. However, detailed seismic imaging of these two asperities can be
corroborated with structural heterogeneities associated with causative fault to understand how seismogenesis is influenced
by strong or weak structural barriers in the region. 相似文献
18.
The ten-year progress of Chinese polar geodesy from 1996 to 2006 is summarized. Research on plate motion, crustal movement,
orbit determination, and atmospheric monitoring, including the ionosphere and troposphere, were performed using GPS data of
the Great Wall Station, Zhongshan Station and Yellow River Station. GPS was also applied in the Amery Ice Shelf, Grove Mountains
and Dome A expeditions to study ice dynamics. During the 2004/2005 austral summer season, the absolute gravity and relative
gravity were measured at the Great Wall Station with precision within ± 3 × 10−8 ms−2 and ± 10 × 10−8 ms−2 respectively. The tide gauge, which was set up in Zhongshan Station to monitor sea level change in 2000, recorded the 2004
Indian Ocean tsunami. SAR interferometry was applied to build the DEM of ice sheet and monitor ice flow in the polar region.
__________
Translated from Advances in Earth Science, 2007, 22(8): 784–790 [译自: 地球科学进展] 相似文献
19.
D. M. Chate 《Natural Hazards》2011,56(1):81-91
A very high number concentration of aerosols in urban locations has a wide impact on health and ecosystem. The evolutions
of urban aerosol distributions at elapse-time 30 and 60 min are simulated at rainfall rates, 0.5 and 0.9 mm h−1 applying scavenging coefficients to initial aerosols number concentrations (before rain). We show how thunderstorm rain scavenges
number concentrations of urban aerosols in the ultrafine and fine modes. Elapsed-time evolutions of urban aerosols presented
in this work show washout of about 50–60 and 70–80% number concentrations of particles in the diameter range 0.02 μm ≤ D
p
≤ 0.1 μm after 30 and 60 min of thunderstorm rain when compared to initial number concentrations (before rain). Assuming
37 and 24% Sulfate and Organic Carbon particles in aerosol distributions in the urban environment and by applying scavenging
coefficients to these initial number concentrations, elapse-time evolutions after 30 and 60 min of thunderstorm rain are presented
in this work. The health impact is addressed in terms of depositions of particles within respiratory system by deposition
fractions as a function of particle size. For D
p
≤ 0.1 μm, 33 and 41% of initial number concentrations of Sulfate and Organic Carbon particles deposits within respiratory
system. Whereas elapsed-time evolutions show 60 and 80% cleansing of initial number concentrations of Sulfate and Organic
Carbon particles after 30 and 60 min of thunderstorm rain. 相似文献
20.
Thermal behaviour and kinetics of dehydration of gypsum in air have been investigated using in situ real-time laboratory parallel-beam
X-ray powder diffraction data evaluated by the Rietveld method. Thermal expansion has been analysed from 298 to 373 K. The
high-temperature limits for the cell edges and for the cell volume, calculated using the Einstein equation, are 4.29 × 10−6, 4.94 × 10−5, 2.97 × 10−5, and 8.21 × 10−5. Thermal expansion of gypsum is strongly anisotropic being larger along the b axis mainly due to the weakening of hydrogen bond. Dehydration of gypsum has been investigated in isothermal conditions within the 348–403 K range with a temperature
increase of 5 K. Dehydration proceeds through the CaSO4·2H2O → CaSO4·0.5H2O → γ-CaSO4 steps. Experimental data have been fitted with the Avrami equation to calculate the empirical activation energy of the process.
No change in transformation mechanism has been observed within the analysed temperature range and the corresponding E
a is 109(12) kJ/mol. 相似文献