95 research outputs found
Random Co(II)–Ni(II) Ferromagnetic Chains Showing Coexistent Antiferromagnetism, Metamagnetism, and Single-Chain Magnetism
A series
of isomorphous compounds of general formula [Co<sub>1–<i>x</i></sub>Ni<sub><i>x</i></sub>(tzpo)Â(N<sub>3</sub>)Â(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub>·<i>n</i>H<sub>2</sub>O (<i>x</i> = 0, 0.19,
0.38, 0.53, 0.68, 0.84, and 1; tzpo = 4-(5-tetrazolate)Âpyridine-<i>N</i>-oxide) was prepared. The compounds consist of homometallic
or heterometallic chains with simultaneous azide-tetrazolate bridges.
The heterometallic systems feature random distribution of metal ions.
All compounds across the series exhibit intrachain ferromagnetic coupling,
interchain antiferromagnetic (AF) ordering, field-induced metamagnetic
transition, and, except the Ni-only compound, single-chain magnetic
dynamics. The AF ordering temperature, the metamagnetic critical field,
and the relaxation parameters show different composition dependence.
Notably, the blocking temperature for the Co-rich materials is higher
than the Co-only compound, suggesting synergy between the randomly
distributed CoÂ(II) and NiÂ(II) ions in promoting slow relaxation. The
results imply rich physics in the random mixed-metal systems and demonstrate
the possibility of improving single-chain relaxation properties by
blending metal ions
Entrance Effects Induced Rectified Ionic Transport in a Nanopore/Channel
The nanofluidic diode, as one of
the emerging nanofluidic logic
devices, has been used in many fields such as biosensors, energy harvesting,
and so on. However, the entrance effects of the nanofluidic ionic
conductance were less discussed, which can be a crucial factor for
the ionic conduction. Here we calculate the ionic conductance as a
function of the length-to-pore ratio (<i>L</i>/<i>r</i>), which has a clear boundary between nanopore (surface dominated)
and nanochannel (geometry dominated) electrically in diluted salt
solution. These entrance effects are even more obvious in the rectified
ionic conduction with oppositely charged exterior surfaces of a nanopore.
We build three modelsî—¸Exterior Charged Surface model (ECS),
Inner Charged Surface model (ICS), and All Charged Surface model (ACS)î—¸to
discuss the entrance effects on the ionic conduction. Our results
demonstrate, for a thin nanopore, that the ECS model has a larger
ionic rectification factor (<i>Q</i>) than that of ICS model,
with a totally reversed tendency of <i>Q</i> compared to
the ICS and ACS models as <i>L</i>/<i>r</i> increases.
Our models predict an alternative option of building nanofluidic biosensors
that only need to modify the exterior surface of a nanopore, avoiding
the slow diffusion of molecules in the nanochannel
Molecular Reactive Force-Field Simulations on the Carbon Nanocavities from Methane Pyrolysis
Hydrocarbon
pyrolysis is the main way to achieve carbonaceous materials,
while most related conversion mechanisms still remain unclear. This
work images pyrolysis of methane at various temperatures and densities
by molecular reactive force field (ReaxFF) simulations. First, it
is interesting to find that the methane decay is dominated by intermolecular
collision displacement instead of direct molecular decomposition.
Second, a conversion of 1200 methane molecules into a regular carbon
nanocavity (CNC) is realized at 3500 K temperature and 0.1 g/cm<sup>3</sup> density after a simulation lasting for 10 ns, with 923 carbon
atoms and a diameter of 3.4 nm. Such CNC is a perfect precursor of
carbon nanotubes, which is confirmed by a sequent simulation on a
larger system of 2400 methane molecules and in agreement with several
experimental observations. It is found that the CNC growth obeys a
polyyne model, without any single aromatic ring formed in the growth.
Furthermore, the complex CNC growth appears in some successive stages:
primary methane decay, chain elongation and branching, cyclization
and condensation, and final sheeting and curling. The regular rearrangement
of CNC is thought to be attributed to the limited active centers formed
at the initial cyclization and condensation stage; that is, it is
a key to control the primary active centers to form regular carbonaceous
materials. Polyyne is found in the pyrolysis of both methane and acetylene
at high temperatures, suggesting that carbyne, a novel valuable carbonaceous
material, may be obtained by hydrocarbon pyrolysis
Tunable Streaming Current in a pH-Regulated Nanochannel by a Field Effect Transistor
Many experimental results demonstrated
that ion transport phenomena
in nanofluidic devices are strongly dependent on the surface charge
property of the nanochannel. In this study, active control of the
surface charge property and the streaming current, generated by a
pressure-driven flow, in a pH-regulated nanochannel using a field
effect transistor (FET) are analyzed for the first time. Analytical
expressions for the surface charge property and the streaming current/conductance
have been derived taking into account multiple ionic species, surface
chemistry reactions, and the Stern layer effect. The model is validated
by the experimental data of the streaming conductance in the silica
nanochannel available in the literature. Results show that the pH-dependent
streaming conductance of the gated silica nanochannel is consistent
with its modulated zeta potential; however, the salt concentration-dependent
streaming conductance might be different from the zeta potential behavior,
depending on the solution pH and the gate potential imposed. The performance
of the field effect modulation of the zeta potential and the streaming
conductance is significant for lower solution pH and salt concentration.
The results gathered are informative for the design of the next-generation
nanofluidics-based power generation apparatus
Influence of bubble deformation on the signal characteristics generated using an optical fiber gas–liquid two-phase flow sensor
The use of optical fiber probe in two-phase flow measurements is very frequently encountered, especially in the applications of chemical engineering and petroleum industries. In this work,
the influence of bubble piercing signals caused by bubble deformation is studied experimentally
using a laboratory-prepared wedge-shaped fiber probe in a lab-scale gas–liquid flow generator. A
three-dimensional simulation model is established to study the influence of bubble deformation
on the piercing signals. A theoretical analysis of the characteristics of the pre-signal influenced
by the bubble deformations is undertaken for a wide range of different modeled bubble shapes.
Combining the experimental and simulation results, a promising analytical method to estimate
the bubble shapes by analyzing the characteristics of pre-signals is proposed. The results of this
investigation demonstrate that it is possible to estimate the bubble shapes before the fiber probe
contacts the bubble surface. The method developed in this investigation is therefore highly promising
for reducing errors caused by deformation during the probe piercing process
Additional file 2: of Peripheral-blood gene expression profiling studies for coronary artery disease and its severity in Xinjiang population in China
Table S2. Gene list of the coronary artery stenosis-related down-regulated genes identified by linear mixed effects model analysis. (XLSX 52 kb
Additional file 1: of Peripheral-blood gene expression profiling studies for coronary artery disease and its severity in Xinjiang population in China
Table S1. Gene list of the coronary artery stenosis-related up-regulated genes identified by linear mixed effects model analysis. (XLSX 77 kb
High-Performance Liquid Chromatographic Enantioseparation of Racemic Drugs Based on Homochiral Metal–Organic Framework
Homochiral metal–organic frameworks
with fine-tuned pore
sizes/walls and large surface areas are promising porous materials
for enantioseparation considering the traditional zeolite molecular
sieves have no chirality. Using enantiopure pyridyl-functionalized
salen [(<i>N</i>-(4-Pyridylmethyl)-l-leucine·HBr)]
as a starting material, we have prepared a noninterpenetrated three-dimensional
homochiral metal organic framework {[ZnLBr]·H<sub>2</sub>O}<i><sub>n</sub></i>, which was further used as a chiral stationary
phase for high-performance liquid chromatography to enantioseparate
racemic drugs, showing excellent performances in enantioseparation
of drugs. The metal–organic framework can be regarded as a
novel molecular sieve-like material with a chiral separation function
based on the relative sizes of the chiral channels and the resolved
molecules
Mechanical and Antimicrobial Properties of Boron Nitride/Methacrylic Acid Quaternary Ammonium Composites Reinforced Dental Flowable Resins
Dental resin composites (DRCs) are
commonly used to restore teeth
affected by dental caries or defects. These materials must possess
excellent properties to withstand the complex oral environment. The
objective of this study was to prepare and characterize Boron nitride
nanosheets (BNN)/ dimethyl amino hexadecyl methacrylate (DMAHDM) composites
(BNN/DMA), and to evaluate them as functional fillers to enhance the
mechanical and antimicrobial properties of dental resins. The BNN/DMA
composites were successfully prepared under the theoretical guidance
of molecular dynamics (MD), and then the physicochemical and morphological
characterization of the BNN/DMA composites were carried out by using
various test methods, such as FT-IR, XRD, UV–vis spectroscopy,
SEM, TEM, and AFM. It was doped into the dental flowable resin in
a certain proportion, and the results showed that the flexural strength
(FS), elastic modulus (EM), compressive strength (CS), and microhardness
(MH) of the modified resin composites were increased by 53.29, 47.8,
97.59, and 37.1%, respectively, with the addition of 0.8 wt % of BNN/DMA
composite fillers. It has a good inhibition effect on Streptococcus mutans, with an inhibition rate as
high as 90.43%. Furthermore, this effect persists even after one month
of aging. In conclusion, the modification of flowable resins with
low-concentration BNN/DMA composites favorably integrates the mechanical
properties and long-term antimicrobial activity of dental resins.
At the same time, they have good biocompatibility and do not affect
the aesthetics. The BNN/DMA composite modified flowable resin has
the potential to become a new type of antimicrobial dental restorative
material
Definitions of exposure, outcomes, adjusted confounders, and quality score of 41 included studies.
<p><b>Outcome:</b> a. 30-day mortality, b. 90-day mortality, c. all-cause mortality in influenza seasons, d. long-term mortality, e. Death attributable to Bacteremia, f. in-hospital mortality, g. mortality for sepsis, h. OR is calculated by events.</p><p>
<b>Exposure:</b></p>*<p>current exposure</p>†<p>recent or former exposure</p>♦<p>Past exposure</p>‡<p>prior use</p>◊<p>continued use.</p><p><b>Adjusted confounders:</b> 1. Age, 2. Gender, 3. comorbid diseases, 4. smoking, 5. other drugs (antibiotics, aspirin, immunosuppressive agent, Angiotensin inhibitors, angiotensin-converting enzyme), 6. Charlson Comorbidity Index, 7. severity of disease, 8. other treatment in hospital, 9. APACHE score, 10. Crises signs, 11. time in ICU, 12. type of infection, 13. vaccine inoculation, 14. other library test data, 15. BMI, 16. alcohol drinking, 17. marital status, 18. race, 19. effect of health, 20. mental state, 21. antiviralinitiation.</p
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