348 research outputs found
Construction of the ACDE Ring System of Calyciphylline A-type Alkaloids via Intramolecular Diels-Alder Reaction of a Tetrasubstituted Olefin
A concise synthesis of the ACDE tetracyclic ring system of calyciphylline A-type alkaloids was investigated. The intramolecular Diels–Alder reaction of a tetrasubstituted olefin with furan enabled the construction of the ACD ring system bearing two contiguous quaternary carbons in one step, and subsequent intramolecular [3+2] cycloaddition successfully gave the E ring
LIPUS effect on lateral tooth movement
Introduction: Because mechanical stimulation of the periodontal ligament (PDL) by low-intensity pulsed ultrasound (LIPUS) has been shown to increase the speed of bone remodeling, the aim of this study was to examine the effects of LIPUS stimulation on the rate of tooth movement and bone remodeling during lateral tooth movement. Methods: Twelve-week-old Wistar rats were divided into two groups. The LIPUS group received experimental tooth movement with LIPUS stimulation, and the tooth movement (TM) group had experimental tooth movement without LIPUS. For the LIPUS and TM groups, the upper right first molars were moved labially with fixed appliances. LIPUS exposure was placed in the region corresponding to the right maxillary first molar. Three days after tooth movement, tartrate-resistant acid phosphatase (TRAP) was examined. Fourteen days after tooth movement, the intermolar width, bone mineral content (BMC), and bone volume fraction (BV/TV) were examined by micro computed tomography (micro-CT), and newly formed bone was measured histomorphometrically. Results: The number of TRAP-positive cells at the compressed region was obviously greater in the LIPUS group. The intermolar width was significantly greater in the LIPUS group than in the TM group. The alveolar bone around the maxillary first molar showed no differences in BMC or BV/TV between the LIPUS and TM groups. The LIPUS group exhibited a significantly greater amount of newly formed alveolar bone than the TM group. Conclusions: The present study provides evidence of the beneficial effects of LIPUS on the lateral tooth movement
High-Flux Triple Bed Circulating Fluidized Bed (TBCFB) Gasifier for Exergy Recuperative IGCC/IGFC
The flow behavior of silica sand, of average particle size 128 μm, was investigated using a large-scale triple-bed combined circulating fluidized bed (TBCFB) cold model, which was composed of a 0.1 m I.D. ×16.6 m tall riser, a solids distributor, a 0.1m I.D. × 6.5 m long downer, a gas-solids separator, a 0.75 m × 0.27 m × 3.4 m bubbling fluidized bed and a 0.158 m I.D. × 5.0 m tall gas-sealing bed (GSB) with a high solids mass flux. The main focus of this study is to determine effect of riser secondary air injection on solids mass flux (Gs) and solid holdup. Gs slightly increased by secondary air injection when the riser gas velocity (Ugr) was less than 10 m/s. This was caused by the increase in the pressure difference between the GSB and the riser. Secondary air injection had little influence on the solid holdup in the riser. The mixing between silica sand and coal particles was investigated for two different coal feeding arrangements by coupling Computational Fluid Dynamics (CFD) with the Discrete Element Method (DEM). The results show a tangential arrangement provided better mixing than a normal arrangement except near the entrance
FLOW BEHAVIORS IN A HIGH SOLID FLUX CIRCULATING FLUIDIZED BED COMPOSED OF A RISER, A DOWNER AND A BUBBLING FLUIDIZED BED
A circulating fluidized bed coal gasifier cold model which consists of an acrylic riser, a downer, and a bubbling fluidized bed were set up. Flow behaviors were investigated using silica sand with the solid mass flux up to 336 kg/m2•s. The effects of the solid inventory and the seals between the three reaction zones on the solid mass flux were investigated and discussed
The French Immigration Policy in the Interwar Period(3) : ―The Ideas of William Oualid―
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Anomalous elastic softening of SmRu_{4}P_{12} under high pressure
The filled skutterudite compound SmRu_4P_{12} undergoes a complex evolution
from a paramagnetic metal (phase I) to a probable multipolar ordering insulator
(phase II) at T_{MI} = 16.5 K, then to a magnetically ordered phase (phase III)
at T_{N} = 14 K. Elastic properties under hydrostatic pressures were
investigated to study the nature of the ordering phases. We found that distinct
elastic softening above T_{MI} is induced by pressure, giving evidence of
quadrupole degeneracy of the ground state in the crystalline electric field. It
also suggests that quadrupole moment may be one of the order parameters below
T_{MI} under pressure. Strangely, the largest degree of softening is found in
the transverse elastic constant C_{T} at around 0.5-0.6 GPa, presumably having
relevancy to the competing and very different Gruneisen parameters \Omega of
T_{MI} and T_{N}. Interplay between the two phase transitions is also verified
by the rapid increase of T_{MI} under pressure with a considerably large \Omega
of 9. Our results can be understood on the basis of the proposed octupole
scenario for SmRu_4P_{12}.Comment: 7 pages, 7 figure
The dual origin of the peripheral olfactory system: placode and neural crest
<p>Abstract</p> <p>Background</p> <p>The olfactory epithelium (OE) has a unique capacity for continuous neurogenesis, extending axons to the olfactory bulb with the assistance of olfactory ensheathing cells (OECs). The OE and OECs have been believed to develop solely from the olfactory placode, while the neural crest (NC) cells have been believed to contribute only the underlying structural elements of the olfactory system. In order to further elucidate the role of NC cells in olfactory development, we examined the olfactory system in the transgenic mice Wnt1-Cre/Floxed-EGFP and P0-Cre/Floxed-EGFP, in which migrating NC cells and its descendents permanently express GFP, and conducted transposon-mediated cell lineage tracing studies in chick embryos.</p> <p>Results</p> <p>Examination of these transgenic mice revealed GFP-positive cells in the OE, demonstrating that NC-derived cells give rise to OE cells with morphologic and antigenic properties identical to placode-derived cells. OECs were also positive for GFP, confirming their NC origin. Cell lineage tracing studies performed in chick embryos confirmed the migration of NC cells into the OE. Furthermore, spheres cultured from the dissociated cells of the olfactory mucosa demonstrated self-renewal and trilineage differentiation capacities (neurons, glial cells, and myofibroblasts), demonstrating the presence of NC progenitors in the olfactory mucosa.</p> <p>Conclusion</p> <p>Our data demonstrates that the NC plays a larger role in the development of the olfactory system than previously believed, and suggests that NC-derived cells may in part be responsible for the remarkable capacity of the OE for neurogenesis and regeneration.</p
A new cosmic ray observation at Syowa Station in the antarctic
A set of Cosmic Ray detectors was newly installed in Syowa Station, in the Antarctic, to observe CR neutrons and muons simultaneously at the same location. The observing system has started working in February 2018 and is in stable operation with a high operation rate, >90%. We describe the new systems and show its stability
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