138 research outputs found
Fabrication of Porous Carbon/TiO<sub>2</sub> Composites through Polymerization-Induced Phase Separation and Use As an Anode for Na-Ion Batteries
Polymerization-induced phase separation
of nanoparticle-filled solution is demonstrated as a simple approach
to control the structure of porous composites. These composites are
subsequently demonstrated as the active component for sodium ion battery
anode. To synthesize the composites, we dissolved/dispersed titanium
oxide (anatase) nanoparticles (for sodium insertion) and polyÂ(hydroxybutyl
methacrylate) (PHBMA, porogen) in furfuryl alcohol (carbon precursor)
containing a photoacid generator (PAG). UV exposure converts the PAG
to a strong acid that catalyzes the furfuryl alcohol polymerization.
This polymerization simultaneously decreases the miscibility of the
PHBMA and reduces the mobility in the mixture to kinetically trap
the phase separation. Carbonization of this polymer composite yields
a porous nanocomposite. This nanocomposite exhibits nearly 3-fold
greater gravimetric capacity in Na-ion batteries than the same titanium
oxide nanoparticles that have been coated with carbon. This improved
performance is attributed to the morphology as the carbon content
in the composite is five times that of the coated nanoparticles. The
porous composite materials exhibit stable cyclic performance. Moreover,
the battery performance using materials from this polymerization-induced
phase separation method is reproducible (capacity within 10% batch-to-batch).
This simple fabrication methodology may be extendable to other systems
and provides a facile route to generate reproducible hierarchical
porous morphology that can be beneficial in energy storage applications
A Tough and High-Performance Transparent Electrode from a Scalable and Transfer-Free Method
Conductive metal films are patterned into transparent metal nanowire networks by using electrospun fibers as a mask. Both the transmittance and sheet resistance (6 Ω/□ at 83% transmittance and 24 Ω/□ at 92% transmittance) of the metal nanowire-based electrode out-perform commercial indium doped tin oxide (ITO) electrodes. The metal nanowire-based transparent electrodes were fabricated on both rigid glass and flexible polyethylene terephthalate (PET) substrates. In addition to state of art performance, the transparent electrodes also exhibit outstanding toughness. They can withstand repeated scotch tape peeling and various bending tests. The method for making the metal nanowire is scalable, and a touch screen on flexible substrate is demonstrated
Syndiotactic Polystyrene-Based Ionogel Membranes for High Temperature Electrochemical Applications
This
work focuses on ionogel membranes for use in Li-ion batteries
fabricated from syndiotactic polystyrene (sPS) gels filled with ionic
liquids (ILs). The aim is to increase the operating temperature of
Li-ion batteries. Thermal stability and safe operation of Li-ion batteries
are two key attributes for their success in hybrid vehicles and other
high-temperature applications. The volatility of the liquid electrolytes
in current lithium-ion battery technology causes thermal runaway leading
to fire, explosion, and swelling of the cell. The approach followed
in this work combines the thermal stability and ruggedness of sPS
and the extremely low volatility of ILs. The performances of lithium
metal/graphite half-cells fabricated with ionogel membranes and those
with Celgard-3501 membranes are evaluated at both room temperature
and at elevated temperatures of 100 °C. Our data show that the
cells with ionogel membranes can be operated continuously at 100 °C
without failure. In addition, better charge–discharge capacity
is obtained due to high ionic conductivity and high electrolyte retention
both derived from high porosity of sPS gels and better wetting of
sPS by the ILs
Additional file 2 of An optimized optical-flow-based method for quantitative tracking of ultrasound-guided right diaphragm deformation
Supplementary Material
Additional file 1 of An optimized optical-flow-based method for quantitative tracking of ultrasound-guided right diaphragm deformation
Supplementary Material
Data_Sheet_1_Warming-induced drought leads to tree growth decline in subtropics: Evidence from tree rings in central China.zip
Subtropical forests provide diverse ecosystem services to human society. However, how subtropical tree species respond to climate change is still unclear. Using a dendrochronological method, we studied the radial growth patterns and species-specific responses of four main tree species in subtropical China to recent warming and drought. Results showed that the long-term drought caused by global warming and reduced precipitation since 1997 had resulted in the growth decline of Pinus massoniana, Castanea henryi and Castanopsis eyrei but not for Liquidambar formosana. Four species had similar sensitivities to the previous year and the current year, which is probably due to the carryover effect and temporal autocorrelation of climate data. Tree growth was positively correlated with growing season precipitation and relative humidity while negatively correlated with vapor pressure deficit. The negative relationship of tree radial growth with temperatures in the previous and current summer and the positive correlation with precipitation gradually strengthened after 1997. Therefore, we highlighted that drought-induced tree decline in subtropical forests is probably a common phenomenon, and it needed to verify by more tree-ring studies on a large scale. The species-specific responses of tree radial growth to climate change are not obvious, but they still should be considered in regional carbon balance and forest dynamics. Considering future climate change, species that are more drought tolerant should be considered as potential plantation species.</p
Correlation between classification and secondary screw penetration in proximal humeral fractures
<div><p>Objectives</p><p>In this study, we investigated the correlation between fracture classification and secondary screw penetration.</p><p>Methods</p><p>We retrospectively identified 189 patients with displaced proximal humeral fractures treated by ORIF at our hospital between June 2006 and June 2013. All fractures were classified radiographically before surgery and follow-up for least 2 years after surgery was recommended. At each follow-up, radiographs were taken in three orthogonal views to evaluate secondary screw penetration.</p><p>Results</p><p>The study population consisted of 189 patients. Of these, 70 were male and 119 female, with a mean age of 59.1 years; the mean follow-up time was 28.5 months. Secondary screw penetration occurred in 26 patients. The risk of developing secondary screw penetration was 11.3-fold higher in four-part fractures than two-part fractures (<i>P</i> < 0.05), 8.6-fold higher for type C fractures than type A fractures (<i>P</i> < 0.05) and 11.0-fold higher for medial hinge disruption group than intact medial hinge group fractures (<i>P</i> < 0.05). However there was no difference between three-part fractures and two-part fractures (<i>P</i> = 0.374), and between type B and type A fractures (<i>P</i> = 0.195). Age, gender, time to surgery and the number of screw in humeral head had no influence on the secondary screw penetration rate (<i>P</i> > 0.05).</p><p>Conclusions</p><p>Patients with four-part fractures, type C fractures and medial hinges disruption are vulnerable to secondary screw penetration. This allows additional precautions to be instituted and measures to be taken as needed.</p></div
Three-Dimensional Bicontinuous Graphene Monolith from Polymer Templates
The two-dimensional single-layer and few-layered graphene exhibit many attractive properties such as large specific surface area and high charge carrier mobility. However, graphene sheets tend to stack together and form aggregates, which do not possess the desirable properties associated with graphene. Herein, we report a method to fabricate three-dimensional (3D), bicontinuous graphene monolith through a versatile hollow nickel (Ni) template derived from polymer blends. The poly(styrene)/poly(ethylene oxide) were used to fabricate a bicontinuous gyroid template using controlled phase separation. The Ni template was formed by electroless metal depositing on the polymer followed by removing the polymer phase. The resulting hollow Ni structure was highly porous (95.2%). Graphene was then synthesized from this hollow Ni template using chemical vapor deposition and the free-standing bicontinuous graphene monolith was obtained in high-throughput process. Finally, the bicontinuous graphene monolith was used directly as binder-free electrode in supercapacitor applications. The supercapacitor devices exhibited excellent stability
Trauma-series x-rays of a 75-year-old woman at the follow-up of three months after surgery, the black arrow pointed at the screw penetrating the joint while it was missed on the true glenoid anteroposterior and transscapular lateral radiographs.
<p>Trauma-series x-rays of a 75-year-old woman at the follow-up of three months after surgery, the black arrow pointed at the screw penetrating the joint while it was missed on the true glenoid anteroposterior and transscapular lateral radiographs.</p
Screw penetration rate in the three fracture classification systems.
<p>Screw penetration rate in the three fracture classification systems.</p
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