The energy storage performance of lithium-ion batteries (LIBs) depends on the electrode capacity and electrode/cell design parameters, which have previously been addressed separately, leading to a ...failure in practical implementation. Here, we show how conformal graphene (Gr) coating on Ni-rich oxides enables the fabrication of highly packed cathodes containing a high content of active material (~99 wt%) without conventional conducting agents. With 99 wt% LiNi
Co
Al
O
(NCA) and electrode density of ~4.3 g cm
, the Gr-coated NCA cathode delivers a high areal capacity, ~5.4 mAh cm
(~38% increase) and high volumetric capacity, ~863 mAh cm
(~34% increase) at a current rate of 0.2 C (~1.1 mA cm
); this surpasses the bare electrode approaching a commercial level of electrode setting (96 wt% NCA; ~3.3 g cm
). Our findings offer a combinatorial avenue for materials engineering and electrode design toward advanced LIB cathodes.
The first rechargeable aqueous Na–air battery has been fabricated, and its electrochemical properties and reversibility are reported herein. The charge–discharge properties of the battery were tested ...using both Vulcan XC72R- and Pt/C-coated carbon paper as the air electrode. Pt/C-coated carbon paper exhibited a voltage efficiency of 84.3%, whereas, for Vulcan XC72R-coated carbon paper and uncoated carbon paper, the observed efficiencies were 78.0% and 72.4%, respectively. Use of Pt/C-coated carbon paper led to a high and stable discharging voltage of 2.85V. The reported rechargeable aqueous Na–air battery is a potential candidate for high energy density batteries in the future.
Display omitted
•A rechargeable aqueous Na–air battery was fabricated.•Discharge voltage of 2.85V was obtained.•Designed battery showed a small voltage gap between charge and discharge curve.•Highly improved voltage efficiency of 84.3% was achieved.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Interest in mechanical compliance has been motivated by the development of flexible electronics and mechanosensors. In particular, studies and characterization of structural deformation at the ...fundamental scale can offer opportunities to improve the device sensitivity and spatiotemporal response; however, the development of precise measurement tools with the appropriate resolution remains a challenge. Here we report a flexible and stretchable photonic crystal nanolaser whose spectral and modal behaviours are sensitive to nanoscale structural alterations. Reversible spectral tuning of ∼26 nm in lasing wavelength, with a sub-nanometre resolution of less than ∼0.6 nm, is demonstrated in response to applied strain ranging from -10 to 12%. Instantaneous visualization of the sign of the strain is also characterized by exploring the structural and corresponding modal symmetry. Furthermore, our high-resolution strain-gauge nanolaser functions as a stable and deterministic strain-based pH sensor in an opto-fluidic system, which may be useful for further analysis of chemical/biological systems.
Understanding the thermal behavior of the solid-electrolyte interphase (SEI) is important for ensuring the overall safety and reliability of Li-ion batteries (LIBs). However, it is difficult to ...detect intrinsic exothermic heat flows from metastable SEI species during typical thermal characterization because of the high heat capacity of other cell components, such as active materials, binders, and current collectors, in samples. Here, we report a new approach to thermal and chemical characterization of the SEI on LIB anodes. By sampling the separator containing a top part of the SEI from cycled cells (graphite|LiCoO2), and conducting differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we found that the SEI on the detached separator consisted mainly of metastable organic components, such as polycarbonates and Li alkyl carbonates, which were accumulated over repeated cycles and responsible for large amounts of exothermic signals at low temperatures, as shown in the DSC curves. These findings show that our sampling method enables a detailed thermal analysis on the metastable SEI alone, which can result in self-heating of cells under typical usage conditions.
•A new method for solid-electrolyte interphase (SEI) characterization is proposed.•SEI-containing separators are prepared by detaching them from cycled cells.•The detached SEI/separators show clear exothermic heat flows at low temperatures.•The SEI mainly consists of metastable polycarbonates and Li alkyl carbonates.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this work, amorphous atorvastatin calcium nanoparticles were successfully prepared using the supercritical antisolvent (SAS) process. The effect of process variables on particle size and ...distribution of atorvastatin calcium during particle formation was investigated. Solid state characterization, solubility, intrinsic dissolution, powder dissolution studies and pharmacokinetic study in rats were performed. Spherical particles with mean particle size ranging between 152 and 863
nm were obtained by varying process parameters such as precipitation vessel pressure and temperature, drug solution concentration and feed rate ratio of CO
2/drug solution. XRD, TGA, FT-IR, FT-Raman, NMR and HPLC analysis indicated that atorvastatin calcium existed as anhydrous amorphous form and no degradation occurred after SAS process. When compared with crystalline form (unprocessed drug), amorphous atorvastatin calcium nanoparticles were of better performance in solubility and intrinsic dissolution rate, resulting in higher solubility and faster dissolution rate. In addition, intrinsic dissolution rate showed a good correlation with the solubility. The dissolution rates of amorphous atorvastatin calcium nanoparticles were highly increased in comparison with unprocessed drug by the enhancement of intrinsic dissolution rate and the reduction of particle size resulting in an increased specific surface area. The absorption of atorvastatin calcium after oral administration of amorphous atorvastatin calcium nanoparticles to rats was markedly increased.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We created composite nanoparticles containing hydrophilic additives using a supercritical antisolvent (SAS) process to increase the solubility and dissolution properties of
-resveratrol for ...application in oral and skin delivery. Physicochemical properties of
-resveratrol-loaded composite nanoparticles were characterized. In addition, an in vitro dissolution-permeation study, an in vivo pharmacokinetic study in rats, and an ex vivo skin permeation study in rats were performed. The mean particle size of all the composite nanoparticles produced was less than 300 nm. Compared to micronized
-resveratrol, the
-resveratrol/hydroxylpropylmethyl cellulose (HPMC)/poloxamer 407 (1:4:1) nanoparticles with the highest flux (0.792 μg/min/cm
) exhibited rapid absorption and showed significantly higher exposure 4 h after oral administration. Good correlations were observed between in vitro flux and in vivo pharmacokinetic data. The increased solubility and flux of
-resveratrol generated by the HPMC/surfactant nanoparticles increased the driving force on the gastrointestinal epithelial membrane and rat skin, resulting in enhanced oral and skin delivery of
-resveratrol. HPMC/surfactant nanoparticles produced by an SAS process are, thus, a promising formulation method for
-resveratrol for healthcare products (owing to their enhanced absorption via oral administration) and for skin application with cosmetic products.
To confirm that the β-phenyl-α,β-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, ...twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies’ results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The aim of the present study was to investigate the effect of Soluplus® on the solubility of atorvastatin calcium and to develop a solid dispersion formulation that can improve the oral ...bioavailability of atorvastatin calcium. We demonstrated that Soluplus® increases the aqueous solubility of atorvastatin calcium. Several solid dispersion formulations of atorvastatin calcium with Soluplus® were prepared at various drug : carrier ratios by spray drying. Physicochemical analysis demonstrated that atorvastatin calcium is amorphous in each solid dispersion, and the 2 : 8 drug : carrier ratio provided the highest degree of sustained atorvastatin supersaturation. Pharmacokinetic analysis in rats revealed that the 2 : 8 dispersion significantly improved the oral bioavailability of atorvastatin. This study demonstrates that spray-dried Soluplus® solid dispersions can be an effective method for achieving higher atorvastatin plasma levels.
Photon-triggered nanowire transistors Kim, Jungkil; Lee, Hoo-Cheol; Kim, Kyoung-Ho ...
Nature nanotechnology,
10/2017, Volume:
12, Issue:
10
Journal Article
Peer reviewed
Photon-triggered electronic circuits have been a long-standing goal of photonics. Recent demonstrations include either all-optical transistors in which photons control other photons or ...phototransistors with the gate response tuned or enhanced by photons. However, only a few studies report on devices in which electronic currents are optically switched and amplified without an electrical gate. Here we show photon-triggered nanowire (NW) transistors, photon-triggered NW logic gates and a single NW photodetection system. NWs are synthesized with long crystalline silicon (CSi) segments connected by short porous silicon (PSi) segments. In a fabricated device, the electrical contacts on both ends of the NW are connected to a single PSi segment in the middle. Exposing the PSi segment to light triggers a current in the NW with a high on/off ratio of >8 × 10
. A device that contains two PSi segments along the NW can be triggered using two independent optical input signals. Using localized pump lasers, we demonstrate photon-triggered logic gates including AND, OR and NAND gates. A photon-triggered NW transistor of diameter 25 nm with a single 100 nm PSi segment requires less than 300 pW of power. Furthermore, we take advantage of the high photosensitivity and fabricate a submicrometre-resolution photodetection system. Photon-triggered transistors offer a new venue towards multifunctional device applications such as programmable logic elements and ultrasensitive photodetectors.
Full text
Available for:
IJS, NUK, SBMB, UL, UM, UPUK
A series of Ti–xZr alloys with Zr contents ranging from 5 to 20wt% was prepared and the effects of Zr addition on the microstructure, physical properties, and corrosion behavior of Ti alloys were ...investigated. The phase and microstructures were characterized using X-ray diffractometry (XRD), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The Ti–xZr alloys exhibited α-Ti structure at Zr content of 20wt% or below. Commercially pure titanium (cp-Ti) was used as a control. We also investigated the effects of alloying element Zr on the mechanical property, oxidation protection ability, and corrosion behavior of Ti–xZr binary alloys. The physical properties and corrosion behavior of Ti–xZr alloys were sensitive to the Zr content. The addition of Zr did contribute to the hardening of cp-Ti due to solid-solution strengthening of α-Ti. Ti–xZr alloys containing up to 10wt% Zr resulted in good oxidation resistance, while Ti–xZr alloys with above 10wt% Zr demonstrated higher oxidation weight gain than cp-Ti. Electrochemical experiments showed that the Ti–xZr alloys exhibited better corrosion resistance compared to that of cp-Ti.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
PDF
