4,417 research outputs found
Small volume laboratory on a chip measurements incorporating the quartz crystal microbalance to measure the viscosity-density product of room temperature ionic liquids
A microfluidic glass chip system incorporating a quartz crystal microbalance (QCM) to measure the square root of the viscosity-density product of room temperature ionic liquids (RTILs) is presented. The QCM covers a central recess on a glass chip, with a seal formed by tightly clamping from above outside the sensing region. The change in resonant frequency of the QCM allows for the determination of the square root viscosity-density product of RTILs to a limit of ∼ 10 kg m−2 s−0.5. This method has reduced the sample size needed for characterization from 1.5 ml to only 30 μl and allows the measurement to be made in an enclosed system
2-(4-Aminopyridinio)acetate
In the title compound, C7H8N2O2, the dihedral angle between the pyridinium ring and the carboxylatomethyl group is 74.5 (1)°. Strong intermolecular N—H⋯O hydrogen bonds between the amine and carboxylate groups form a layered hydrogen-bonded network perpendicular to [010]. In addition, there are some weak C—H⋯O hydrogen bonds present in the structure
2-Amino-5,7-bis(4-fluorophenyl)-1′,3′-dimethyl-7,8-dihydrospiro[pyrido[2,3-d]pyrimidine-6(5H),5′-pyrimidine]-2′,4,4′,6′(3H,1′H,3′H,5′H)-tetraone ethanol solvate
In the molecule of the title compound, C24H20F2N6O4·C2H5OH, the pyrimidine ring is oriented at dihedral angles of 42.64 (3) and 62.94 (3)° with respect to the benzene rings, while the dihedral angle between the benzene rings is 74.45 (3)°. The pyridine ring adopts an envelope conformation. In the crystal structure, intermolecular N—H⋯O and O—H⋯N hydrogen bonds link the molecules into a two-dimensional network, forming R
2
2(8) ring motifs. π–π contacts between the pyrimidine and benzene rings [centroid–centroid distances = 3.516 (1) and 3.927 (1) Å] may further stabilize the structure
N′-(2-Methoxybenzylidene)-2-nitrobenzohydrazide
The title compound, C15H13N3O4, was synthesized by the reaction of equimolar quantities of 2-methoxybenzaldehyde and 2-nitrobenzohydrazide in methanol. The dihedral angle between the two substituted benzene rings is 68.3 (2)°. In the crystal structure, inversion dimers linked by pairs of N—H⋯O hydrogen bonds occur
Chandra observations of Abell 2199
We present results from an analysis of two Chandra observations of the rich,
nearby galaxy cluster Abell 2199. We find evidence (having corrected for
projection effects) for radial gradients in temperature and metallicity in the
X-ray emitting gas: the temperature drops from kT~4.2 keV at R=200 kpc to 1.6
keV within R=5 kpc of the centre. The metallicity rises from ~0.3 solar at
R=200 kpc to ~0.7 solar at R=30 kpc before dropping to 0.3 solar within the
central 5 kpc. We find evidence for structure in the surface brightness
distribution associated with the central radio source 3C338. No evidence is
found for the gas having a large spread in temperature at any particular
location despite the cooling time being short (<10**9yr) within the central ~15
kpc. Heating and mass cooling rates are calculated for various assumptions
about the state of the gas.Comment: 10 pages, 12 figures. Accepted by MNRAS. Minor changes following
referee's comment
Improving Code Generation by Dynamic Temperature Sampling
Recently, Large Language Models (LLMs) have shown impressive results in code
generation. However, existing decoding strategies are designed for Natural
Language (NL) generation, overlooking the differences between NL and
programming languages (PL). Due to this oversight, a better decoding strategy
for code generation remains an open question. In this paper, we conduct the
first systematic study to explore a decoding strategy specialized in code
generation. With an analysis of loss distributions of code tokens, we find that
code tokens can be divided into two categories: challenging tokens that are
difficult to predict and confident tokens that can be easily inferred. Among
them, the challenging tokens mainly appear at the beginning of a code block.
Inspired by the above findings, we propose a simple yet effective method:
Adaptive Temperature (AdapT) sampling, which dynamically adjusts the
temperature coefficient when decoding different tokens. We apply a larger
temperature when sampling for challenging tokens, allowing LLMs to explore
diverse choices. We employ a smaller temperature for confident tokens avoiding
the influence of tail randomness noises. We apply AdapT sampling to LLMs with
different sizes and conduct evaluations on two popular datasets. Results show
that AdapT sampling significantly outperforms state-of-the-art decoding
strategy
Cyclin D1 in ASM Cells from Asthmatics Is Insensitive to Corticosteroid Inhibition
Hyperplasia of airway smooth muscle (ASM) is a feature of the remodelled airway in asthmatics. We examined the antiproliferative effectiveness of the corticosteroid dexamethasone on expression of the key regulator of G1 cell cycle progression—cyclin D1—in ASM cells from nonasthmatics and asthmatics stimulated with the mitogen platelet-derived growth factor BB. While cyclin D1 mRNA and protein expression were repressed in cells from nonasthmatics in contrast, cyclin D1 expression in asthmatics was resistant to inhibition by dexamethasone. This was independent of a repressive effect on glucocorticoid receptor translocation. Our results corroborate evidence demonstrating that corticosteroids inhibit mitogen-induced proliferation only in ASM cells from subjects without asthma and suggest that there are corticosteroid-insensitive proliferative pathways in asthmatics
Hopeahainol C monohydrate
In the structure of the title compound, C28H16O6·H2O [systematic name 3,11-bis(4-hydroxyphenyl)-4,12-dioxapentacyclo[8.6.1.12,5.013,17.09,18]octadeca-1(16),2,5(18),6,8,10,13(17),14-octaene-7,15-diol monohydrate], the hopeahainol C molecule lies about an inversion center with the solvent water molecule located on a crystallographic twofold axis. Hopeahainol C is an oligostillbenoid compound and was isolated from the bark of Shorea roxburghii G. Don. The five central fused rings are essentially planar with an r.m.s. deviation of 0.0173 (3) Å. The 4-hydroxyphenyl ring is twisted with respect to this plane, with the dihedral angle between the phenyl ring and the fused-ring system being 41.70 (10)°. The crystal features intermolecular O—H⋯O hydrogen bonds. These interactions link the hopeahainol C molecules into chains along the b axis. Water molecules are located interstitially between the hopeahainol C molecules linked by O(water)—H⋯O(hydroxy) and O(hydroxy)—H⋯O(water) hydrogen bonds. π–π interactions are also observed with centroid–centroid distances of 3.6056 (17) and 3.5622 (17) Å. Short O⋯O contacts [2.703 (2)–2.720 (3) Å] are also present in the crystal
Magnetic fields in the Centaurus cluster
We present multi-frequency VLA observations of the radio galaxy PKS 1246-410
at the center of the Centaurus Cluster, and compare these results to recent
Chandra observations. The unusual radio morphology of PKS 1246-410 probably
results from interactions with the hot, X-ray emitting gas. This gas, along
with cluster magnetic fields, also produces substantial Faraday Rotation
Measures towards PKS 1246-410. We discuss these observations in the context of
a sample of 14 luminous X-ray clusters with embedded radio galaxies and
possible cooling flows. A correlation is found between the cooling flow rate
and the maximum Faraday Rotation Measures. Magnetic fields of strength 10-40 uG
are found to be common to the centers of clusters with strong cooling flows,
and somewhat lower field strengths of 2-10 uG are found in the non cooling-flow
clusters.Comment: 7 pages, 10 figures (3 colour), submitted to MNRA
1-(3-Bromopropoxy)-4-chlorobenzene
In the molecule of the title compound, C8H8BrClO, the Cl atom lies slightly out of the aromatic ring plane [displacement = 0.072 (3) Å]. In the crystal structure, a π–π contact between the phenyl rings [centroid–centroid distance = 3.699 (3) Å] may stabilize the structure. There also exists a C—H⋯π contact between the methylene group and the chlorophenyl ring
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