1,393 research outputs found
Geological Structure and Tectonics of the Ogcheon Zone in the Chungju-Jangseonri Area, South Korea
The Ogcheon Zone of the Chungju-Jangseonri area consists of some nappes, in descending order of structural level Kyemeongsan nappe and Chungju nappe which overlie the Busan nappe I composed of the Precambrian Busan gneiss complex with its cover rocks (A-unit), Busan nappe II whose basal part contains a small-scale slice of Precambrian gneiss complex, and Sanjeoteo nappe which overlies the Precambrian Bakdalryeong gneiss complex with its cover rocks (A-unit). The Kyemyeongsan nappe, Chungju nappe, Busan nappe II and Sanjeoteo nappe consist of two units, upper unit in which acidic rocks are predominant among original igneous constituents of metamorphic rocks with subordi-nate amount of basic rocks and lower unit in which basic rocks are predominant, showing that the magmatism was of bimodal type but that the predominant magmatism was of basic type during the earlier phase of the development of the Ogcheon sedimentary basin and of acidic type during the later phase. The acidic rocks of the Kyemeongsan nappe are plutonic rocks with volcanic rocks, but these of the Chungju nappe, Busan nappe II and Sanjeoteo nappe are only of volcanic type, showing that the Kyemeongsan nappe appears to have been derived from an activity center of acidic volcano-plutonism in the Ogcheon sedimentary basin as an intracontinental rift zone. The metamorphic rocks of the Ogcheon Zone of the Chungju-Jangseonri area were produced by a medium pressure type metamorphism during the first phase and by an andalusite type metamorphism during the second phase. The first phase metamorphism occurred in the metamorphic field which showed a downward increase of temperature from the upper unit to the lower unit, giving rise to kyanite, staurolite and garnet in the lower unit, though in the Kyemeongsan nappe such metamorphic minerals crystallized also in its upper unit. The exhumation of the medium pressure type metamorphic rocks occurred forming the above-mentioned nappes. It was followed by the folding with westward vergence throughout the nappes. The andalusite type metamorphism occurred throughout the nappes after this folding
Cosmic Ray Acceleration and Nonthermal Radiation at Accretion Shocks in the Outer Regions of Galaxy Clusters
Cosmology models predict that external accretion shocks form in the outer
region of galaxy clusters due to supersonic gas infall from filaments and voids
in the cosmic web. They are characterized by high sonic and Alfv\'enic Mach
numbers, and , and propagate into weakly
magnetized plasmas of . Although strong
accretion shocks are expected to be efficient accelerators of cosmic rays
(CRs), nonthermal signatures of shock-accelerated CRs around clusters have not
been confirmed, and detailed acceleration physics at such shocks has yet to be
understood. In this study, we first establish through two-dimensional
particle-in-cell simulations that at strong high- shocks electrons can
be pre-energized via stochastic Fermi acceleration owing to the ion-Weibel
instability in the shock transition region, possibly followed by injection into
diffusive shock acceleration. Hence, we propose that the models derived from
conventional thermal leakage injection may be employed for the acceleration of
electrons and ions at accretion shocks as well. Applying these analytic models
to numerical shock zones identified in structure formation simulations, we
estimate nonthermal radiation, such as synchrotron and inverse-Compton (IC)
emission due to CR electrons, and -decay -rays due to CR
protons, around simulated clusters. Our models with the injection parameter,
, predict synthetic synchrotron maps, which seem consistent
with recent radio observations of the Coma cluster. However, the detection of
nonthermal IC X-rays and -rays from accretion shocks would be quite
challenging. We suggest that the proposed analytic models may be adopted as
generic recipes for CR production at cosmological shocks.Comment: 21 pages, 12 figure
Minimum Surgico-Orthopedic Treatment using Computer-Assisted Single-Tooth Osteotomy in an Adolescent Skeletal Class III Patient with Anterior Ankylosed Tooth: A Case Report
Traumatic tooth avulsion can lead to ankylosis, which may interfere with growth of the alveolar bone in a growing patient. The resulting difference in alveolar bone height and position can lead to esthetic problems such as open bite.A growing 13-year-old female patient presented skeletal Class III malocclusion with bone ankylosis of a maxillary anterior tooth. Even after 2 years of orthopedic and orthodontic treatment, little improvement was achieved regarding the positions of the anterior maxillary teeth, or the vertical position of the maxillary right central incisor. Therefore, surgical treatment by single-tooth osteotomy (STO) and corticotomy for the anterior ankylosed tooth were considered and performed using a CAD/CAM surgical guide, based on presurgical computer-based simulation surgery. Orthodontic and orthopedic treatments were completed at 10 months after surgery. The patient showed a favorable course of healing, with no mobility issues or gingival recession 3 years after single-tooth osteotomy and corticotomy surgeries. A favorable outcome was finally achieved by applying orthopedic treatment combined with STO and corticotomy for the anterior ankylosed tooth. Orthodontic treatment with minimally surgical method is recommended in an adolescent patient with skeletal Class III malocclusion and anterior open bite
Iron and Magnesium Impregnation of Avocado Seed Biochar for Aqueous Phosphate Removal
There has been increasing interest in using biochar for nutrient removal from water, and its application for anionic nutrient removal such as in phosphate (PO43−) necessitates surface modifications of raw biochar. This study produced avocado seed biochar (AB), impregnated Fe- or Mg-(hydr)oxide onto biochar (post-pyrolysis), and tested their performance for aqueous phosphate removal. The Fe- or Mg-loaded biochar was prepared in either high (1:8 of biochar to metal salt in terms of mass ratio) or low (1:2) loading rates via the co-precipitation method. A total of 5 biochar materials (unmodified AB, AB + High Fe, AB + Low Fe, AB + High Mg, and AB + Low Mg) were characterized according to their selected physicochemical properties, and their phosphate adsorption performance was tested through pH effect and adsorption isotherm experiments. Fe-loaded AB contained Fe3O4, while Mg-loaded AB contained Mg(OH)2. The metal (hydr)oxide inclusion was higher in Fe-loaded AB. Mg-loaded AB showed a unique free O–H functional group, while Fe-loaded AB showed an increase in its specific surface area more than 10-times compared to unmodified AB (1.8 m2 g−1). The effect of the initial pH on phosphate adsorption was not consistent between Fe-(anion adsorption envelope) vs. Mg-loaded AB. The phosphate adsorption capacity was higher with Fe-loaded AB in low concentration ranges (≤50 mg L−1), while Mg-loaded AB outperformed Fe-loaded AB in high concentration ranges (75–500 mg L−1). The phosphate adsorption isotherm by Fe-loaded AB fit well with the Langmuir model (R2 = 0.91–0.96), indicating the adsorptive surfaces were relatively homogeneous. Mg-loaded biochar, however, fit much better with Freundlich model (R2 = 0.94–0.96), indicating the presence of heterogenous adsorptive surfaces. No substantial benefit of high loading rates in metal impregnation was found for phosphate adsorption. The enhanced phosphate removal by Mg-loaded biochar in high concentration ranges highlights the important role of the chemical precipitation of phosphate associated with dissolved Mg2+
Pressure dependence of upper critical fields in FeSe single crystals
We investigate the pressure dependence of the upper critical fields
({\mu}) for FeSe single crystals with pressure up to 2.57 GPa.
The superconducting (SC) properties show a disparate behavior across a critical
pressure where the pressure-induced antiferromagnetic phase coexists with
superconductivity. The magnetoresistance for and is very
different: for , magnetic field induces and enhances a hump in the
resistivity close to the for pressures higher than 1.2 GPa, while it is
absent for . Since the measured {\mu} for FeSe samples is
smaller than the orbital limited upper critical field ()
estimated by the Werthamer Helfand and Hohenberg (WHH) model, the Maki
parameter ({\alpha}) related to Pauli spin-paramagnetic effects is additionally
considered to describe the temperature dependence of {\mu}().
Interestingly, the {\alpha} value is hardly affected by pressure for ,
while it strongly increases with pressure for . The pressure evolution of
the {\mu}(0)s for the FeSe single crystals is found to be almost
similar to that of (), suggesting that the pressure-induced magnetic
order adversely affects the upper critical fields as well as the SC transition
temperature.Comment: 23 pages, 6 figures, 1 tabl
Methanoldinitrato[N-(2-pyridylmethylene)aniline]copper(II)
The Cu atom in the title compound, [Cu(NO3)2(C12H10N2)(CH3OH)], adopts a square-pyramidal geometry, being ligated by two N atoms of the bidentate N-(2-pyridylmethylene)aniline (ppma) ligand, two O atoms of NO3 ligands and one O atom of a methanol molecule, which occupies the apical position. The phenyl ring on the ppma ligand is twisted out of the pyridine plane, forming a dihedral angle of 42.9 (1)°. In the crystal, intermolecular O—H⋯O hydrogen bonds between methanol and NO3 ligands form an extensive one-dimensional network extending parallel to [100]
Dichlorido[N,N-diethyl-N′-(2-pyridylmethylene)ethane-1,2-diamine]mercury(II)
The Hg atom in the title compound, [HgCl2(C12H19N3)], adopts a distorted trigonal-bipyramidal geometry, being ligated by two Cl atoms and three N atoms of the N,N-diethyl-N′-(2-pyridylmethylene)ethane-1,2-diamine ligand. The dihedral angle between the HgN3 and HgCl2 least-squares planes is 88.6 (1)°. The Hg—N distances including the pyridine N and the ammonium N atom are about 0.20 Å longer than the Hg—N distance including the imino N atom
Microinstabilities in the Transition Region of Weak Quasi-perpendicular Intracluster Shocks
Microinstabilities play important roles in both entropy generation and particle acceleration in collisionless shocks. Recent studies have suggested that in the transition region of quasi-perpendicular (Q(perpendicular to)) shocks in the high-beta (beta = P-gas/P-B) intracluster medium (ICM), the ion temperature anisotropy due to the reflected-gyrating ions could trigger the Alfven ion cyclotron (AIC) instability and the ion-mirror instability, while the electron temperature anisotropy induced by magnetic field compression could excite the whistler instability and the electron-mirror instability. Adopting the numerical estimates for ion and electron temperature anisotropies found in the particle-in-cell (PIC) simulations of Q(perpendicular to) shocks with sonic Mach numbers, M-s = 2-3, we carry out a linear stability analysis for these microinstabilities. The kinetic properties of the microinstabilities and the ensuing plasma waves on both ion and electron scales are described for wide ranges of parameters, including beta and the ion-to-electron mass ratio. In addition, the nonlinear evolution of the induced plasma waves are examined by performing 2D PIC simulations with periodic boundary conditions. We find that for beta approximate to 20-100, the AIC instability could induce ion-scale waves and generate shock surface ripples in supercritical shocks above the AIC critical Mach number, M-AIC* approximate to 2.3. Also, electron-scale waves are generated primarily by the whistler instability in these high-beta shocks. The resulting multiscale waves from electron to ion scales are thought to be essential in the electron injection to diffusive shock acceleration in Q(perpendicular to) shocks in the ICM
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