Evaluation of performance metrics for high energy density rechargeable lithium-oxygen batteries.

The demand for practical implementation of rechargeable lithium-oxygen batteries (LOBs) has grown owing to their extremely high theoretical energy density. However, the factors determining the performance of cell-level high energy density LOBs remain unclear. In this study, LOBs with a stacked-cell configuration were fabricated and their performance evaluated under different experimental conditions to clarify the unique degradation phenomenon under lean-electrolyte and high areal capacity conditions. First, the effect of the electrolyte amount against areal capacity ratio (E/C) on the battery performance was evaluated, revealing a complicated voltage profile for an LOB cell operated under high areal capacity conditions. Second, the impact of different kinds of gas-diffusion layer materials on the "sudden death" phenomenon during the charging process was investigated. The results obtained in the present study reveal the importance of these factors when evaluating the performance metrics of LOBs, including cycle life, and round-trip energy efficiency. We believe that adopting a suitable experimental setup with appropriate technological parameters is crucial for accurately interpreting the complicated phenomenon in LOBs with cell-level high energy density.

Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu2.

The Kondo effect between localized f-electrons and conductive carriers leads to exotic physical phenomena. Among them, heavy-fermion (HF) systems, in which massive effective carriers appear due to the Kondo effect, have fascinated many researchers. Dimensionality is also an important characteristic of the HF system, especially because it is strongly related to quantum criticality. However, the realization of the perfect two-dimensional (2D) HF materials is still a challenging topic. Here, we report the surface electronic structure of the monoatomic-layer Kondo lattice YbCu2 on a Cu(111) surface observed by synchrotron-based angle-resolved photoemission spectroscopy. The 2D conducting band and the Yb 4f state, located very close to the Fermi level, are observed. These bands are hybridized at low-temperature, forming the 2D HF state, with an evaluated coherence temperature of about 30 K. The effective mass of the 2D state is enhanced by a factor of 100 by the development of the HF state. Furthermore, clear evidence of the hybridization gap formation in the temperature dependence of the Kondo-resonance peak has been observed below the coherence temperature. Our study provides a new candidate as an ideal 2D HF material for understanding the Kondo effect at low dimensions.

Breakdown of bulk-projected isotropy in surface electronic states of topological Kondo insulator SmB6(001).

The topology and spin-orbital polarization of two-dimensional (2D) surface electronic states have been extensively studied in this decade. One major interest in them is their close relationship with the parities of the bulk (3D) electronic states. In this context, the surface is often regarded as a simple truncation of the bulk crystal. Here we show breakdown of the bulk-related in-plane rotation symmetry in the topological surface states (TSSs) of the Kondo insulator SmB6. Angle-resolved photoelectron spectroscopy (ARPES) performed on the vicinal SmB6(001)-p(2 × 2) surface showed that TSSs are anisotropic and that the Fermi contour lacks the fourfold rotation symmetry maintained in the bulk. This result emphasizes the important role of the surface atomic structure even in TSSs. Moreover, it suggests that the engineering of surface atomic structure could provide a new pathway to tailor various properties among TSSs, such as anisotropic surface conductivity, nesting of surface Fermi contours, or the number and position of van Hove singularities in 2D reciprocal space.

Theoretical evaluation of supersaturation of amorphous solid dispersion formulations with different drug/polymer combinations using mathematical modeling.

Amorphous solid dispersion (ASD) is a preparation widely used for improving the solubility and low oral absorbability of poorly water-soluble drugs, but the quantitative analysis of its dissolution profiles and its supersaturation status remains an important issue. We previously reported a new mathematical model for analyzing the dissolution characteristics of ASD preparations that enabled evaluation of theoretical solubility of ASDs and crystal precipitation rate constants of ASD preparations. In this study, to analyze the relationship between the mathematical parameters of the model and the dissolution behavior in detail, we simulated the dissolution behaviors upon changing parameters. We quantitatively evaluated the supersaturation of ASD preparations composed of various combinations of two drugs (ibuprofen or indomethacin) and three polymers (polyvinylpyrrolidone (PVP), copovidone or hydroxypropylmethylcellulose (HPMC)). Based on parameter comparison, the difference in the peak of drug concentration between IB/PVP and IB/HPMC ASDs was found to be derived from precipitation rate constant, not the theoretical solubility. In addition, although IMC/PVP ASD had higher solubility than IMC/HPMC ASDs, HPMC could suppress crystal precipitation and maintain supersaturation at higher concentrations than IMC/PVP ASD by comparing parameters derived from model fitting. Thus, our results show that the use of mathematical parameters can illuminate theoretical mechanical information regarding dissolution behaviors of various ASDs and permit a visualization of the character of the dissolution process.

Bulk-sensitive spin-resolved resonant electron energy-loss spectroscopy (SR-rEELS): Observation of element- and spin-selective bulk plasmons.

We have developed spin-resolved resonant electron energy-loss spectroscopy with the primary energy of 0.3-1.5 keV, which corresponds to the core excitations of 2p-3d absorption of transition metals and 3d-4f absorption of rare-earths, with the energy resolution of about 100 meV using a spin-polarized electron source as a GaAs/GaAsP strained superlattice photocathode. Element- and spin-selective carrier and valence plasmons can be observed using the resonance enhancement of core absorptions and electron spin polarization. Furthermore, bulk-sensitive electron energy-loss spectroscopy spectra can be obtained because the primary energy corresponds to the mean free path of 1-10 nm. The methodology is expected to provide us with novel information about elementary excitations by resonant inelastic x-ray scattering and resonant photoelectron spectroscopy.

Author Correction: Transdermal delivery of nobiletin using ionic liquids.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Transdermal delivery of nobiletin using ionic liquids.

Nobiletin (NOB), a flavonoid, has extremely low water solubility and low oral bioavailability; however, despite these problems, various physiological effects have been investigated in vitro. In the present study, we investigated the transdermal delivery of NOB using choline and geranic acid (CAGE), which is a biocompatible material that has been reported to be a promising transdermal delivery approach. The feasibility was evaluated by a set of in vitro and in vivo tests. A solubility evaluation demonstrated that CAGE induced excellent solubility of NOB induced by multipoint hydrogen bonding between NOB and CAGE. In vitro transdermal tests using a Franz diffusion cell showed that CAGE was effective in enhancing transdermal absorption of NOB, compared to other penetration enhancers. Subsequent in vivo tests demonstrated that CAGE significantly improved area under the concentration-time curve of NOB in vivo and NOB/CAGE sample showed 20-times higher bioavailability than oral administration of NOB crystal. Furthermore, NOB/CAGE sample also showed significant drops of the blood glucose level in rats derived from hypoglycemic activity of NOB. Thus, transdermal administration of NOB using CAGE was shown to be feasible, which indicates that the use of CAGE may be adapted for other flavonoids that also show both low water solubility and low permeability.

Controlled-Release Fine Particles Prepared by Melt Adsorption for Orally Disintegrating Tablets.

Melt adsorption is a manufacturing method that offers precise control of particle size distribution of granules and circumvents the disadvantages of conventional melt granulation. However, drug release from particles adsorbed with hydrophobic materials has not been fully investigated, and there are missing details as to whether particles manufactured by this technique can be applied to orally disintegrating tablets (ODT). In this report, we aimed to optimize process parameters and formulation to manufacture ODT containing melt adsorption-particles with the specific characteristic of sustained release. Melt adsorption particles containing Neusilin US2 as the adsorbent were prepared by using various waxes to determine the most suitable material for controlled release formulation. Glycerol fatty acid ester (Poem TR-FB: TR-FB) was the optimal wax examined because of its drug release pattern and tabletability. We then optimized manufacturing conditions by examining granulation time, disintegrant amount per tablet and compression force on the tablet for ODT that meet the criteria of controlled drug release, tensile strength and disintegration of the tablet. Multiple regression analysis revealed the effect of process parameters on tablet properties and drug release with increasing the granulation time affording sustained release of the drug. The analysis also showed that a high compression force crushed the granules coated by TR-FB, which impaired sustained drug release. From the regression model the optimal manufacturing conditions were determined, and the tablet prepared under these conditions concurred with the predicted values and met all criteria. This new technique should contribute to the development of ODT to improve medication adherence.

Crystal Structures of Flavone C-Glycosides from Oolong Tea Leaves: Chafuroside A Dihydrate and Chafuroside B Monohydrate.

Chafuroside A and chafuroside B are flavone C-glycosides isolated from oolong tea leaves. They have a number of beneficial pharmacological activities related to antiinflammation at various concentrations. However, no crystallographic study of chafurosides has yet been reported. In the present study, the crystal structures of chafuroside A and chafuroside B were investigated using single-crystal X-ray diffraction. The asymmetric unit of the chafuroside A crystal consists of one chafuroside A and two water molecules, and that of chafuroside B contains one chafuroside B and one water molecule. The flavone moiety of chafuroside A is curved, i.e., the angle between the best-fit planes of the chromene and phenyl rings is 18.9°, whereas the chafuroside B flavone moiety is relatively flat. A comparison of the curvatures of the flavone moieties of various C-glycosides showed that the curvature of chafuroside A is significantly larger than those of the others. This structural feature might contribute to the differences between the strengths of the pharmacological activities of chafurosides A and B.

Fabrication of Zero-Order Sustained-Release Floating Tablets via Fused Depositing Modeling 3D Printer.

A three-dimensional (3D) printer is a powerful tool that can be used to enhance personalized medicine. A fused deposition modeling (FDM) 3D printer can fabricate 3D objects with different internal structures that provides the opportunity to introduce one or more specific functionalities. In this study, zero-order sustained-release floating tablet was fabricated using FDM 3D printer. Filaments comprising poorly water-soluble weak base drug, itraconazole (ITZ) and polymers (hydroxypropyl cellulose and polyvinylpyrrolidone) were prepared, and tablets with a hollow structure and different outside shell thicknesses were fabricated. In the 3D printed tablets, ITZ existed as an amorphous state and its solubility improved markedly. As the outside shell thickness of the tablet increased, drug release was delayed and floating time was prolonged. In the tablets with 0.5 mm of the upper and bottom layer thickness and 1.5 mm of the side layer thickness, holes were not formed in the tablets during the dissolution test, and the tablets floated for a long period (540 min) and showed nearly zero-order drug release for 720 min. These findings may be useful for improving the bioavailability of several drugs by effective absorption from the upper small intestine, with floating gastric retention system.

Development of muco-adhesive orally disintegrating tablets containing tamarind gum-coated tea powders for oral care.

The aim of this study was to design and evaluate muco-adhesive orally disintegrating tablets manufactured by microwave irradiation and containing polysaccharide. We prepared orally disintegrating tea tablets (ODTTs) containing a 1 w/w% mass fraction of one of five polysaccharides (gum arabic, carrageenan, guar gum, tamarind gum, or pectin) and evaluated the swelling degree, tablet hardness, friability, disintegration time, and adhesive properties. All tablets had a swelling degree of about 1 mm, a hardness of over 13 N, and a friability degree of <1%. Tablets containing gum arabic and tamarind gum had disintegration times of 30 s or less and satisfied requirements as orally disintegrating tablets. This could be attributed to their high void contents, which allowed for water penetration. The adhesive properties and particle retention ratios were highest in ODTTs containing tamarind gum, which was thought to be caused by the rapid disintegration and high viscosity of the tamarind gum itself. When we investigated changing the mass fraction of tamarind gum, we found 1 w/w% was most suitable for rapid disintegration and high adhesiveness. The ODTTs containing 1 w/w% tamarind gum showed significant growth inhibition towards Streptococcus mutans. Therefore, microwave irradiation technology and addition of tamarind gum could be used to manufacture muco-adhesive orally disintegrating tablets for oral care.

Relaxation dynamics of [Re(CO)2(bpy){P(OEt)3}2](PF6) in TEOA solvent measured by time-resolved attenuated total reflection terahertz spectroscopy.

To reveal highly efficient photocatalytic properties of an artificial photosynthesis material [Re(CO)2(bpy){P(OEt)3}2](PF6), we have directly observed the photo-induced relaxation dynamics and reductive quenching process of the photo-excited state on a photosynthesis material in Triethanolamine (TEOA) solvent as an electron donor by time-resolved attenuated total reflection spectroscopy in the terahertz (THz) region. The spectrum of the complex in TEOA has an intermolecular vibrational mode between the complex and TEOA molecules, which reflects the precursor of the reductive quenching process. The intermolecular vibrational mode has three-step relaxation process in a picosecond timescale after photo-excitation, where firstly the triplet metal-to-ligand charge transfer excited state is vibrationally cooled down, secondly the distance between Re and TEOA is reduced by the rotation of TEOA molecules due to dipole-dipole interaction accelerated by heat transfer, and finally electrons transfer from TEOA to Re. These observations provide us the detailed information of the electron transfer process of photocatalytic properties of [Re(CO)2(bpy){P(OEt)3}2](PF6) in TEOA solvent.

Novel Dissolution Approach for Tacrolimus-Loaded Microspheres Using a Dialysis Membrane for in Vitro-in Vivo Correlation.

The aim of this study was to establish a novel approach to in vitro dissolution evaluation using a combination of the paddle method and a dialysis membrane, both to predict the overall in vivo performance of tacrolimus microspheres and also to identify a suitable dissolution test method to describe the in vivo initial burst phenomenon. This new dissolution method for evaluating the release of tacrolimus from microspheres consisted of rotating a customized paddle inside a dialysis membrane using a conventional paddle apparatus. Findings were compared with a method in which the paddle was rotated outside the dialysis membrane, the conventional paddle method, and the flow-through cell method. We concluded that the paddle method with a dialysis membrane and internal agitation, which was designed to mimic in vivo conditions, predicted the overall pharmacokinetic (PK) profile of tacrolimus microspheres whereas the conventional paddle method described the initial burst. These findings suggest that it may not be possible to predict both the PK profile and initial burst using a single analysis method. We therefore recommend that evaluation of the initial burst be performed separately. In conclusion, we propose that combination of the paddle method with a dialysis membrane and internal agitation to evaluate the overall PK profile, together with the paddle method to describe the in vivo initial burst, represents a novel approach to in vitro dissolution evaluation for microsphere formulations.

Non-trivial surface states of samarium hexaboride at the (111) surface.

The peculiar metallic electronic states observed in the Kondo insulator, samarium hexaboride (SmB6), has stimulated considerable attention among those studying non-trivial electronic phenomena. However, experimental studies of these states have led to controversial conclusions mainly due to the difficulty and inhomogeneity of the SmB6 crystal surface. Here, we show the detailed electronic structure of SmB6 with angle-resolved photoelectron spectroscopy measurements of the three-fold (111) surface where only two inequivalent time-reversal-invariant momenta (TRIM) exist. We observe the metallic two-dimensional state was dispersed across the bulk Kondo gap. Its helical in-plane spin polarisation around the surface TRIM indicates that SmB6 is topologically non-trivial, according to the topological classification theory for weakly correlated systems. Based on these results, we propose a simple picture of the controversial topological classification of SmB6.

In vivo temperature-sensitive drug release system trigged by cooling using low-melting-point microcrystalline wax.

Temperature-sensitive formulations are attractive controlled-release formulations, which release an incorporated drug by changes in body temperature induced by external temperature stimulation. Recently, it has been reported that wax matrix (WM) particles composed of a low-melting-point microcrystalline wax (MCW) released only a small amount of the drug at 37 °C, whereas faster drug release occurred at 25 °C. In this study, temperature-sensitive formulations composed of low-melting-point MCW that release drugs triggered by cooling, rather than heating, were developed. In an in vitro dissolution test in which the test medium was repeatedly cooled from 37 to 25 °C, control of the promotion and suppression of drug release was achieved. The drug concentration in the plasma of rats administered the particles was significantly increased by cooling compared with non-cooling, indicating that the drug release from the particles was promoted by cooling both in vitro and in vivo. Therefore, particles composed of low-melting-point MCW should be useful for the development of cooling-triggered, temperature-sensitive formulations.

Evidence for a preformed Cooper pair model in the pseudogap spectra of a Ca10(Pt4As8)(Fe2As2)5 single crystal with a nodal superconducting gap.

For high-Tc superconductors, clarifying the role and origin of the pseudogap is essential for understanding the pairing mechanism. Among the various models describing the pseudogap, the preformed Cooper pair model is a potential candidate. Therefore, we present experimental evidence for the preformed Cooper pair model by studying the pseudogap spectrum observed in the optical conductivity of a Ca10(Pt4As8)(Fe2As2)5 (Tc = 34.6 K) single crystal. We observed a clear pseudogap structure in the optical conductivity and observed its temperature dependence. In the superconducting (SC) state, one SC gap with a gap size of Δ = 26 cm-1, a scattering rate of 1/τ = 360 cm-1 and a low-frequency extra Drude component were observed. Spectral weight analysis revealed that the SC gap and pseudogap are formed from the same Drude band. This means that the pseudogap is a gap structure observed as a result of a continuous temperature evolution of the SC gap observed below Tc. This provides clear experimental evidence for the preformed Cooper pair model.

Mechanism of Drug Release From Temperature-Sensitive Formulations Composed of Low-Melting-Point Microcrystalline Wax.

It was reported that wax matrix (WM) particles composed of low-melting-point microcrystalline wax showed unique release behaviors; the particles released only a small amount of the entrapped drug (non-diffusion-controlled release) at 37°C, whereas it showed comparatively fast drug release in a diffusion-controlled manner at 25°C. However, the mechanism of the drug release is still unclear. The objective of this study was to determine the mechanism of drug release from the WM particles using X-ray computed tomography. In the WM particles collected during dissolution tests at 25°C, the void space derived from drug release increased with increasing time, and there was no change in the structure, indicating that the WM particles released drug while maintaining the particle shape at 25°C. In the WM particles collected during dissolution tests at 37°C, the void space was confirmed at initial time point; however, at subsequent time points, the void space was disappeared, and the roughness of the surface was evident. This structural change may have blocked the conveyance pathway of the outer medium, which would inhibit the drug release. The difference between the drug-release mechanisms of the WM particles at the 2 temperatures will be valuable for developing cooling-triggered, temperature-sensitive formulations.

Combination of Roll Grinding and High-Pressure Homogenization Can Prepare Stable Bicelles for Drug Delivery.

To improve the solubility of the drug nifedipine (NI), NI-encapsulated lipid-based nanoparticles (NI-LNs) have been prepared from neutral hydrogenated soybean phosphatidylcholine and negatively charged dipalmitoylphosphatidylglycerol at a molar ratio of 5/1 using by roll grinding and high-pressure homogenization. The NI-LNs exhibited high entrapment efficiency, long-term stability, and enhanced NI bioavailability. To better understand their structures, cryo transmission electron microscopy and atomic force microscopy were performed in the present study. Imaging from both instruments revealed that the NI-LNs were bicelles. Structures prepared with a different drug (phenytoin) or with phospholipids (dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine, and distearoylphosphatidylcholine) were also bicelles. Long-term storage, freeze-drying, and high-pressure homogenization did not affect the structures; however, different lipid ratios, or the presence of cholesterol, did result in liposomes (5/0) or micelles (0/5) with different physicochemical properties and stabilities. Considering the result of long-term stability, standard NI-LN bicelles (5/1) showed the most long-term stabilities, providing a useful preparation method for stable bicelles for drug delivery.

N-methyl-d-aspartate receptor dysfunction in the prefrontal cortex of stroke-prone spontaneously hypertensive rat/Ezo as a rat model of attention deficit/hyperactivity disorder.

AIM: We previously reported that stroke-prone spontaneously hypertensive rat/Ezo (SHRSP/Ezo) has high validity as an attention deficit/hyperactivity disorder (AD/HD) animal model, based on its behavioral phenotypes, such as inattention, hyperactivity, and impulsivity. Fronto-cortical dysfunction is implicated in the pathogenesis of AD/HD. In this study, we investigated prefrontal cortex (PFC) function in SHRSP/Ezo rats by electrophysiological methods and radioreceptor assay. METHODS: We recorded excitatory postsynaptic potential in layer V pyramidal neurons in the PFC by intracellular recording method to assess synaptic plasticity in the form of long-term potentiation (LTP). We also performed N-methyl-d-aspartate acid (NMDA) receptor binding assay in the PFC and hippocampus using radiolabeled NMDA receptor antagonist [3 H]MK-801. RESULTS: Theta-burst stimulation induced LTP in the PFC of genetic control, WKY/Ezo, whereas failed to induce LTP in that of SHRSP/Ezo. The Kd value of [3 H]MK-801 binding for NMDA receptors in the PFC of SHRSP/Ezo was higher than in the WKY/Ezo. Neither the Bmax nor Kd of [3 H]MK-801 binding in the SHRSP/Ezo hippocampus was significantly different to WKY/Ezo. CONCLUSION: These results suggest that the AD/HD animal model SHRSP/Ezo has NMDA receptor dysfunction in the PFC.

Temperature dependence of the superconducting energy gaps in Ca9.35La0.65(Pt3As8)(Fe2As2)5 single crystal.

We measured the optical reflectivity R(ω) for an underdoped (Ca0.935La0.065)10(Pt3As8)(Fe2As2)5 single crystal and obtained the optical conductivity [Formula: see text] using the K-K transformation. The normal state [Formula: see text] at 30 K is well fitted by a Drude-Lorentz model with two Drude components (ωp1 = 1446 cm-1 and ωp2 = 6322 cm-1) and seven Lorentz components. Relative reflectometry was used to accurately determine the temperature dependence of the superconducting gap at various temperatures below Tc. The results clearly show the opening of a superconducting gap with a weaker second gap structure; the magnitudes for the gaps are estimated from the generalized Mattis-Bardeen model to be Δ1 = 30 and Δ2 = 50 cm-1, respectively, at T = 8 K, which both decrease with increasing temperature. The temperature dependence of the gaps was not consistent with one-band BCS theory but was well described by a two-band (hence, two gap) BCS model with interband interactions. The temperature dependence of the superfluid density is flat at low temperatures, indicating an s-wave full-gap superconducting state.