2,911 research outputs found
3-Carboxypyrazino[2,3-f][1,10]phenanthrolin-9-ium-2-carboxylate
In the title zwitterionic compound, C16H8N4O4, the dihedral angle between the carboxyl and carboxylate groups is 72.14 (2)°. In the crystal, molecules are linked by strong intermolecular O—H⋯O− and N+—H⋯O− hydrogen bonds into double chains extended along [001]. These chains are additionally stabilized by π–π stacking interactions between the pyridine and benzene rings [centroid–centroid distance = 3.5542 (8) Å]
Origin of the Temperature Oscillation in Turbulent Thermal Convection
We report an experimental study of the three-dimensional spatial structure of
the low frequency temperature oscillations in a cylindrical Rayleigh-B\'{e}nard
convection cell. It is found that thermal plumes are not emitted periodically,
but randomly and continuously, from the top and bottom plates. We further found
that the oscillation of the temperature field does not originate from the
boundary layers, but rather is a result of the horizontal motion of the hot
ascending and cold descending fluids being modulated by the twisting and
sloshing motion of the bulk flow field.Comment: 5 figure
4-({4-[1-(Methoxyimino)ethyl]anilino}(phenyl)methylene)-3-methyl-2-phenyl-1H-pyrazol-5(4H)-one
In the title compound, C26H24N4O2, the dihedral angles between the central pyrazole ring and the other three benzene rings are 40.02 (3), 77.51 (5) and 55.72 (3)°. A strong intramolecular N—H⋯O hydrogen bond forms a six-membered ring with an S(6) motif. In the crystal structure, a weak intermolecular C—H⋯N interaction with graph-set motif R
2
2(8) and C—H⋯O hydrogen bonds link each molecule to three others, forming an infinite two-dimensional supramolecular structure
Mendelian randomization analysis does not reveal a causal influence of mental diseases on osteoporosis
IntroductionOsteoporosis (OP) is primarily diagnosed through bone mineral density (BMD) measurements, and it often leads to fracture. Observational studies suggest that several mental diseases (MDs) may be linked to OP, but the causal direction of these associations remain unclear. This study aims to explore the potential causal association between five MDs (Schizophrenia, Depression, Alzheimer's disease, Parkinson's disease, and Epilepsy) and the risk of OP.MethodsFirst, single-nucleotide polymorphisms (SNPs) were filtered from summary-level genome-wide association studies using quality control measures. Subsequently, we employed two-sample Mendelian randomization (MR) analysis to indirectly analyze the causal effect of MDs on the risk of OP through bone mineral density (in total body, femoral neck, lumbar spine, forearm, and heel) and fractures (in leg, arm, heel, spine, and osteoporotic fractures). Lastly, the causal effect of the MDs on the risk of OP was evaluated directly through OP. MR analysis was performed using several methods, including inverse variance weighting (IVW)-random effects, IVW-fixed effects, maximum likelihood, weighted median, MR-Egger regression, and penalized weighted median.ResultsThe results did not show any evidence of a causal relationship between MDs and the risk of OP (with almost all P values > 0.05). The robustness of the above results was proved to be good.DiscussionIn conclusion, this study did not find evidence supporting the claim that MDs have a definitive impact on the risk of OP, which contradicts many existing observational reports. Further studies are needed to determine the potential mechanisms of the associations observed in observational studies
5-Amino-7-(4-bromophenyl)-3,7-dihydro-2H-thieno[3,2-b]pyran-6-carbonitrile 1,1-dioxide
In the title compound, C14H11BrN2O3S, the 2,3-dihydrothiophene ring is almost planar [maximum deviation = 0.006 (1) Å]. The pyran ring is in an envelope conformation [puckering parameters Q = 0.115 (2) Å, θ = 77.5 (10), ϕ = 172.9 (10)°]. The pyran and phenyl rings are approximately perpendicular, making a dihedral angle of −76.4 (2)°. The crystal packing is stabilized by intermolecular N—H⋯O hydrogen bonds, with the sulfone O atoms acting as acceptors
Ethyl 3-(2,4-difluorophenoxy)-2-(4-methoxyphenyl)acrylate
In the title molecule, C18H16F2O4, the two benzene rings form a dihedral angle of 55.2 (2)°. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules into chains propagating along the c axis
Flow reversals in thermally driven turbulence
We analyze the reversals of the large scale flow in Rayleigh-B\'enard
convection both through particle image velocimetry flow visualization and
direct numerical simulations (DNS) of the underlying Boussinesq equations in a
(quasi) two-dimensional, rectangular geometry of aspect ratio 1. For medium
Prandtl number there is a diagonal large scale convection roll and two smaller
secondary rolls in the two remaining corners diagonally opposing each other.
These corner flow rolls play a crucial role for the large scale wind reversal:
They grow in kinetic energy and thus also in size thanks to plume detachments
from the boundary layers up to the time that they take over the main, large
scale diagonal flow, thus leading to reversal. Based on this mechanism we
identify a typical time scale for the reversals. We map out the Rayleigh number
vs Prandtl number phase space and find that the occurrence of reversals very
sensitively depends on these parameters.Comment: 4 pages, 4 figure
Poly[[hemi-μ4-oxalato-hemi-μ2-oxalato-bis(μ3-pyrazine-2-carboxylato)erbium(III)silver(I)] monohydrate]
The asymmetric unit of the title complex, {[AgEr(C5H3N2O2)2(C2O4)]·H2O}n, contains one ErIII atom, one AgI atom, two pyrazine-2-carboxylate (pyc) ligands, two half oxalate ligands (each lying on an inversion center) and one uncoordinated water molecule. The ErIII atom is coordinated by two O atoms and two N atoms from two pyc ligands, one O atom from a third pyc ligand and four O atoms from two oxalate ligands in a distorted monocapped square-antiprismatic geometry. The AgI atom is coordinated by two N atoms from two pyc ligands, one O atom from a third pyc ligand and one O atom from one oxalate ligand. The crystal structure exhibits a three-dimensional heterometallic polymeric network. O—H⋯O hydrogen bonding between the uncoordinated water molecule and carboxylate O atoms is observed
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