682 research outputs found
1-[4-(3-{[5-(4-Chlorophenyl)furan-2-yl]methylideneamino}-2,5-dioxoimidazolidin-1-yl)butyl]-4-methylpiperazine-1,4-diium dichloride hemihydrate
The title compound, C23H30ClN5O3
2+·2Cl−·0.5H2O, was synthesized by N-alkylation of 1-({[5-(4-chlorophenyl)-2-furanyl]methylene}amino)-2,4-imidazolidinedione with 1-bromo-4-chlorobutane, and N-methylpiperazine. In the crystal, the cations, anions and water molecules are linked by O—H⋯Cl and N—H⋯Cl hydrogen bonds
(R)-[1-(2-Chlorophenyl)-2-methoxy-2-oxoethyl][2-(thiophen-2-yl)ethyl]ammonium (+)-camphor-10-sulfonate acetone monosolvate
The title compound, C15H17ClNO2S+·C10H15O4S−·C3H6O, was synthesized by N-alkylation of α-amino-(2-chlorophenyl)acetate with 2-thienylethyl p-toluenesulfonate, followed by reaction with (+)-camphor-10-sulfonic acid. In the crystal, the cations and anions are linked through N—H⋯O hydrogen bonds. The thiophene ring of the cation was found to be disordered over two sites, with refined occupancies of 0.798 (4) and 0.202 (4)
Sub-micrometer phonon mean free paths in metal-organic frameworks revealed by machine-learning molecular dynamics simulations
Metal-organic frameworks (MOFs) are a family of materials that have high
porosity and structural tunability and hold great potential in various
applications, many of which requiring a proper understanding of the thermal
transport properties. Molecular dynamics (MD) simulations play an important
role in characterizing the thermal transport properties of various materials.
However, due to the complexity of the structures, it is difficult to construct
accurate empirical interatomic potentials for reliable MD simulations of MOFs.
To this end, we develop a set of accurate yet highly efficient machine-learned
potentials for three typical MOFs, including MOF-5, HKUST-1, and ZIF-8, using
the neuroevolution potential approach as implemented in the GPUMD package, and
perform extensive MD simulations to study thermal transport in the three MOFs.
Although the lattice thermal conductivity (LTC) values of the three MOFs are
all predicted to be smaller than 1 at room temperature, the
phonon mean free paths (MFPs) are found to reach the sub-micrometer scale in
the low-frequency region. As a consequence, the apparent LTC only converges to
the diffusive limit for micrometer single crystals, which means that the LTC is
heavily reduced in nanocrystalline MOFs. The sub-micrometer phonon MFPs are
also found to be correlated with a moderate temperature dependence of LTC
between those in typical crystalline and amorphous materials. Both the large
phonon MFPs and the moderate temperature dependence of LTC fundamentally change
our understanding of thermal transport in MOFs.Comment: 12 pages, 9 figure
Accurate prediction of heat conductivity of water by a neuroevolution potential
We propose an approach that can accurately predict the heat conductivity of
liquid water. On the one hand, we develop an accurate machine-learned potential
based on the neuroevolution-potential approach that can achieve
quantum-mechanical accuracy at the cost of empirical force fields. On the other
hand, we combine the Green-Kubo method and the spectral decomposition method
within the homogeneous nonequilibrium molecular dynamics framework to account
for the quantum-statistical effects of high-frequency vibrations. Excellent
agreement with experiments under both isobaric and isochoric conditions within
a wide range of temperatures is achieved using our approach.Comment: 8 pages, 7 figure
Systematically characterizing dysfunctional long intergenic noncoding RNAs in multiple brain regions of major psychosis
Alzheimer\u27s disease (AD), the most common form of dementia, is a chronic neurodegenerative disease. The HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1 (HACE1) gene is expressed in human brain and may play a role in the pathogenesis of neurodegenerative disorders. Till now, no previous study has reported the association of the HACE1 gene with the risk and age at onset (AAO) of AD; while few studies have checked the proportional hazards assumption in the survival analysis of AAO of AD using Cox proportional hazards model. In this study, we examined the associations of 14 single nucleotide polymorphisms (SNPs) in the HACE1 gene with the risk and the AAO of AD using 791 AD patients and 782 controls. Multiple logistic regression model identified one SNP (rs9499937 with p = 1.8×10-3) to be associated with the risk of AD. For survival analysis of AAO, both classic Cox regression model and Bayesian survival analysis using the Cox proportional hazards model were applied to examine the association of each SNP with the AAO. The hazards ratio (HR) with its 95% confidence interval (CI) was estimated. Survival analysis using the classic Cox regression model showed that 4 SNPs were significantly associated with the AAO (top SNP rs9499937 with HR=1.33, 95%CI=1.13-1.57, p=5.0×10-4). Bayesian Cox regression model showed similar but a slightly stronger associations (top SNP rs9499937 with HR=1.34, 95%CI=1.11-1.55) compared with the classic Cox regression model. Using an independent family-based sample, one SNP rs9486018 was associated with the risk of AD (p=0.0323) and the T-T-G haplotype from rs9786015, rs9486018 and rs4079063 showed associations with both the risk and AAO of AD (p=2.27×10-3 and 0.0487, respectively). The findings of this study provide first evidence that several genetic variants in the HACE1 gene were associated with the risk and AAO of AD
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