2,751 research outputs found
Note On Certain Inequalities for Neuman Means
In this paper, we give the explicit formulas for the Neuman means ,
, and , and present the best possible upper and lower
bounds for theses means in terms of the combinations of harmonic mean ,
arithmetic mean and contraharmonic mean .Comment: 9 page
Filament L1482 in the California molecular cloud
Aims. The process of gravitational fragmentation in the L1482 molecular
filament of the California molecular cloud is studied by combining several
complementary observations and physical estimates. We investigate the kinematic
and dynamical states of this molecular filament and physical properties of
several dozens of dense molecular clumps embedded therein.
Methods. We present and compare molecular line emission observations of the
J=2--1 and J=3--2 transitions of 12CO in this molecular complex, using the
KOSMA 3-meter telescope. These observations are complemented with archival data
observations and analyses of the 13CO J=1--0 emission obtained at the Purple
Mountain Observatory 13.7-meter radio telescope at Delingha Station in QingHai
Province of west China, as well as infrared emission maps from the Herschel
Space Telescope online archive, obtained with the SPIRE and PACS cameras.
Comparison of these complementary datasets allow for a comprehensive
multi-wavelength analysis of the L1482 molecular filament.
Results. We have identified 23 clumps along the molecular filament L1482 in
the California molecular cloud. All these molecular clumps show supersonic
non-thermal gas motions. While surprisingly similar in mass and size to the
much better known Orion molecular cloud, the formation rate of high-mass stars
appears to be suppressed in the California molecular cloud relative to that in
the Orion molecular cloud based on the mass-radius threshold derived from the
static Bonnor Ebert sphere. Our analysis suggests that these molecular
filaments are thermally supercritical and molecular clumps may form by
gravitational fragmentation along the filament. Instead of being static, these
molecular clumps are most likely in processes of dynamic evolution.Comment: 10 pages, 9 figures, 2 tables, accepted to Astronomy and Astrophysic
Bis(N′-benzoylpyridine-4-carbohydrazide)(1,10-phenanthroline)copper(II) dinitrate
In the title complex, [Cu(C13H11N3O2)2(C12H8N2)](NO3)2, the CuII atom (site symmetry 2) is coordinated by four N atoms from one 1,10-phenanthroline and two hydrazine ligands, respectively. The hydrazine ligands coordinate to the CuIIatom by a pyridine N atom. These four atoms form a slightly distorted square-planar N4 donor set. In the packing, two additional Cu⋯O interactions occur [Cu⋯O = 2.462 (2) Å], resulting in a typical Jahn–Teller-distorted octahedral environment around the Cu atom. N—H⋯O hydrogen bonds result in a three-dimensional network. The O atoms of the anion are disordered over two positions in a 0.68 (2):0.32 (2) ratio
{N,N-Dimethyl-N′-[phenyl(2-pyridyl)methylene]ethane-1,2-diamine-κ3 N,N′,N′′}dithiocyanato-κN,κS-copper(II)
In the title complex, [Cu(NCS)2(C16H19N3)], the CuII atom is coordinated by a total of four N atoms; three from one tridentate Schiff base ligand and one from one of the NCS− ions. The S atom from the other NCS− ion completes the distorted square-pyramidal coordination
Aqua[N-(2,5-dihydroxybenzyl)iminodiacetato]copper(II)
The title complex, [Cu(C11H11NO6)(H2O)], contains a CuII atom in a distorted square-pyramidal geometry. The metal centre is coordinated in the basal sites by one water molecule and two carboxylate O atoms and one N atom of the tetradentate ligand [Cu—O range, 1.9376 (11)–1.9541 (12), Cu—N, 1.9929 (12) Å] while the apical site is occupied by a hydroquinone O donor atom [Cu—O, 2.3746 (12) Å]. Intermolecular hydrogen bonding interactions involving both hydroquinone hydroxy groups and the coordinated water as donors give a three-dimensional framework structure
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Ion liquid chromatography on-a-chip with beads-packed parylene column
A parylene-MEMS ion-exchange Liquid Chromatography (LC) chip is presented here. The chip is integrated with microfluidic I/O ports, a separation column, frits/filters, and a conductivity detector. The column is packed with conventional LC stationary phase support materials, i.e. micro-beads with surface functional groups. To withstand high pressure normally encountered in high performance liquid chromatography (HPLC), a self-aligned, channel-anchoring technique is developed to increase the pressure rating of the parylene microfluidic devices from 30 to at least 800psi. On-chip injection, separation and detection of anions in water, with ~25 ppm concentration, have been successfully demonstrated. To our knowledge, this is the first demonstration of microbeads-packed column ion liquid Chromatography (LC) on a chip
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