O 7 ) 2 /multi-walled carbon nanotube (MWCNT) composite was fabricated by a solid state reaction and was further used to fabricate a cathode for sodium-ion batteries. The electrochemical behaviors were thoroughly investigated in assembled non-aqueous Na 3.12 Fe 2.44 (P 2 O 7 ) 2 /MWCNT//Na cells, showing higher specific capacity (over 100 mA h g À1 at a rate of 0.15C) and better stable cycle performance than those of the pristine Na 3.12 Fe 2.44 (P 2 O 7 ) 2 -based one. It is noted that with increased charge-discharge cycles, the specific capacity of Na 3.12 Fe 2.44 (P 2 O 7 ) 2 /MWCNT gets close to the theoretical capacity (ca. 117.4 mA h g À1 ). These good performances could be attributed to the incorporated MWCNTs, which improve the conductivity for lower charge transfer resistance and shorten the diffusion length for faster Na + diffusion to access the reaction sites. Through systematic studies of EIS at different states of charge and discharge, it is discovered that R ct decreases with the increase of voltage and reaches a minimum value at redox sites, but R e and D Na + show the opposite trend.Moreover, a full cell test using a carbon black negative electrode also demonstrates good capacity retention up to 50 cycles and a reversible capacity of 145 mA h g À1 with the average operation voltage of 2.8 V.
Ultralong worm-like MoS2 nanostructures were assembled with a solvent-mediated solvothermal process by controlling the composition ratio of the miscible precursors in solution.
Ultralong cobalt sulfide (CoS(1.097)) nanotube networks are synthesized by a simple one-step solvothermal method without any surfactant or template. A possible formation mechanism for the growth processes is proposed. Owing to the hollow structure and large specific area, the novel CoS(1.097) materials present outstanding electrochemical properties. Electrochemical measurements for supercapacitors show that the as-prepared ultralong CoS(1.097) nanotube networks exhibit high specific capacity, good capacity retention, and excellent Coulombic efficiency.
Transparent e-skin that can fully
mimic human skin with J-shaped
mechanical-behavior and tactile sensing attributes have not yet been
reported. In this work, the skin-like hydrogel composite with J-shaped
mechanical behavior and highly transparent, tactile, soft but strong,
flexible, and stretchable attributes is developed as structural strain
sensing element for e-skin. Piezo-resistive polyacrylamide (PAAm)
hydrogel is used as supporting matrix to endow high transparency,
softness, flexibility, stretch-ability and strain sensing capability
desired for e-skin. Ultrahigh molecular weight polyethylene (UHMWPE)
fiber with a wavy configuration is designed as reinforcement filler
to provide the tunable strain-limiting effect. As a result, the as-prepared
UHMWPE fiber/PAAm composite e-skin presents unique “J-shape”
stress–strain behavior akin to human skin. And the PAAm composite
can switch from supersoft to highly stiff in the designed strain range
up to 100% with a prominent tensile strength of 48.3 MPa, which enables
it to have the high stretch-ability and excellent load-bearing ability,
simultaneously. Moreover, finite element model is developed to clarify
the stress distribution and damage evolution for the UHMWPE fiber/PAAm
composite during the tensile process. The PAAm composite exhibits
not only an excellent strain sensing performance with a long-term
reliability up to 5000 loading–unloading cycles but also an
extraordinary softness and mechanical strength with a low initial
modulus of 6.7 kPa, which is matchable with soft human epidermis.
Finally, the e-skin is used for demonstrations in monitoring various
human activities and protecting structural integrity in designed strain
ranges. The strategy for reinforcing piezo-resistive hydrogel with
wavy-shaped UHMWPE fibers proposed here is promising for the development
of transparent, flexible, soft but strong e-skin with a tunable strain-limiting
effect akin to human skin.
Inspired
by chameleons’ structural color regulation capability, a simple,
but effective, swelling method is proposed for the first time to prepare
an ionic polyacrylamide (PAAm) organogel for simultaneous tactile
sensing and interactive color changing. The PAAm organogel obtained
by swelling the PAAm scaffold in the dimethyl sulfoxide solution of
organic electrochromic material (OECM) shows an extremely large stretchability
with an elongation of 1600%, a supersoftness with a compressive modulus
of 7.2 kPa, an excellent transmittance up to 90%, and a very fast
response time of 0.5 s combined with the characteristic of interactive
color changing. The PAAm organogel also suggests a universal design
ability to tailor coloration spectra for tactile sensors via simply
changing the type and content of OECM. The tactile sensor based on
a PAAm organogel is capable of serving as a wearable device for precisely
tracing human body motion performance and directly visualizing the
stress distribution via interactive color changing capability. It
is demonstrated that the swelling method proposed here is a simple
and practical strategy to prepare ionic organogels with both piezo-resistive
and electrochromic effects.
Purpose To investigate and compare the contrast-enhanced ultrasound (CEUS) features of histologically proven HCA with those of contrast-enhanced computed tomography (CECT).MethodsEighteen patients with proven hepatic adenoma by pathology were retrospectively selected from the CEUS database. Fourteen of them had undergone liver CECT exams. The basic features on unenhanced imaging and the enhancement level and specific features on contrast-enhanced imaging were retrospectively analyzed, and the differences between CEUS and CECT were compared.ResultsAll the HCAs showed hyper-enhancement in the arterial phase. During the portal and late phases, 12 HCAs (12/18, 66.7 %) on CEUS and 11 (11/14, 78.6 %) on CT showed washout. On CEUS, 10 (10/18, 55.5 %) showed centripetal filling in the arterial phase and persistent peripheral rim enhancement. Five of them (61.1 %, 11/18) showed delayed central washout in the portal or late phase. However, on CECT, 2 (14.3 %, 2/14) and 4 (28.6 %, 4/14) HCAs showed persistent enhancement of the peripheral rim and central non-enhancing hemorrhage areas, respectively.ConclusionsCompared with dynamic CT, CEUS was superior at characterizing specific dynamic features. Considering that it is radiation-free, readily availability and easy to use, CEUS is suggested as the first line imaging tool to diagnose HCA.
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