Transdermal drug delivery by microneedles: does skin metabolism matter?

Microneedle arrays have been shown to increase skin permeability for the transdermal delivery of drugs with high molecular weights. Various theoretical studies have been proposed to predict the drug transport behaviour after drug injection using microneedles. However it is important for the optimal design of microneedle systems to consider the effects of biological factors such as skin metabolism and variations in pharmacokinetic parameters as well as to improve the enhancement of skin permeability. A mathematical model for microneedle systems is introduced and applied to simulate the verapamil transport with metabolism in the skin. A comparative analysis for a transdermal delivery of verapamil from microneedles is presented in this paper. The results indicate that the skin metabolism does not markedly affect the skin permeation after verapamil injection using microneedles

Synthesis, Direct Formation under High Pressure, Structure, and Electronic Properties of LiNbO₃‑type Oxide PbZnO₃

A novel LiNbO₃-type (LN-type) lead zinc oxide, PbZnO₃, was successfully synthesized under high pressure and temperature. Rietveld structure refinement using synchrotron powder X-ray diffraction (XRD) data demonstrated that LN-type PbZnO₃ crystallized into a trigonal structure with a polar space group (<i>R</i>3<i>c</i>). The bond valence sum estimated from the interatomic distances indicated that the sample possesses a Pb⁴⁺Zn²⁺O₃ valence state. Polarization could evolve as a result of the repulsion between constituent cations because PbZnO₃ does not contain a stereochemical 6s² cation or a Jahn–Teller active d⁰ cation. Distortion of ZnO₆ octahedra resulting from cation shift is comparable with that of d⁰ TiO₆ in ZnTiO₃ and MnTiO₃ with LN-type oxides, which leads to stabilization of the polar structure. PbZnO₃ exhibited metallic behavior and temperature-independent diamagnetic character. <i>In situ</i> XRD measurement revealed that the formation of LN-type PbZnO₃ occurred directly without the formation of a perovskite phase, which is unusual among LN-type materials obtained by high-pressure synthesis

Polymer/Polymer Blend Solar Cells Improved by Using High-Molecular-Weight Fluorene-Based Copolymer as Electron Acceptor

The highest power conversion efficiency (PCE) of 2.7% has been achieved for all-polymer solar cells made with a blend of poly­(3-hexylthiophene) (P3HT, electron donor) and poly­[2,7-(9,9-didodecylfluorene)-<i>alt</i>-5,5-(4′,7′-bis­(2-thienyl)-2′,1′,3′-benzothiadiazole)] (PF12TBT, electron acceptor). The PCE of the P3HT/PF12TBT solar cells increases from 1.9% to 2.7% with an increase in the molecular weight (<i>M</i>_w) of PF12TBT from 8500 to 78 000 g mol^–1. In a device with high-molecular-weight PF12TBT, efficient charge generation is maintained even at high annealing temperatures because of the small phase separation on the length scale of exciton diffusion due to an increase in the glass transition temperature (<i>T</i>_g) and a reduced diffusional mobility of the PF12TBT chains above <i>T</i>_g. On the other hand, efficient charge transport is also achieved through the formation of interconnected networks of PF12TBT-rich domains, which is facilitated by the high molecular weight of PF12TBT, and the ordering of P3HT chains in P3HT-rich domains, which is a result of high-temperature annealing. Thus, when high-molecular-weight PF12TBT is used, an optimal blend morphology that supports efficient charge generation as well as charge transport can be obtained by thermal annealing, and consequently, the highest PCE reported so far for an all-polymer solar cell is achieved

High-Energy-Density Rechargeable Lithium–Nickel Chloride Aqueous Solution Batteries

High-energy-density rechargeable batteries with performance beyond that of lithium-ion batteries are required for next-generation electric vehicles. We propose a novel rechargeable battery with a lithium anode and a NiCl₂ aqueous cathode that is separated Li_1.4Al_0.4Ge_0.2Ti_1.4(PO₄)₃ as a water-stable lithium-ion-conducting solid electrolyte. The cell was discharged up to 93% of the theoretical cathode capacity at 0.5 mA cm^–2 and 25 °C. The calculated energy density, based on the weights of NiCl₂ and Li, and the average discharge voltage of 2.4 V at 0.5 mA cm^–2, was 852 Wh kg^–1, which is more than twice as high as that of conventional lithium-ion batteries. The cell was successfully cycled for 50 cycles without any degradation of the charge and discharge voltages at 0.5 mA cm^–2 and 25 °C for 5 h charge and 5 h discharge, where the utilization of NiCl₂ was 80%

Charge Transport in Intermixed Regions of All-Polymer Solar Cells Studied by Conductive Atomic Force Microscopy

Charge transport in intermixed regions of all-polymer solar cells based on a blend of poly­(3-hexyl­thiophene) (P3HT; electron donor) with poly­[2,7-(9,9-didodecyl­fluorene)-<i>alt</i>-5,5-(4′,7′-bis­(2-thienyl)-2′,1′,3′-benzo­thiadiazole)] (PF12TBT; electron acceptor) was studied by conductive atomic force microscopy (C-AFM). For a blend film fabricated from a chlorobenzene solution, intermixed regions were detected between the P3HT-rich and PF12TBT-rich domains. The overall hole current in the intermixed regions remained almost constant, both before and after thermal annealing at 80 °C, but it increased in the P3HT-rich domains. For a blend film fabricated from a chloroform solution, the entire observed area constituted an intermixed region, both before and after thermal annealing. The overall hole current in this film was significantly improved following thermal annealing at 120 °C. These finely mixed structures with efficient charge transport yielded a maximum power conversion efficiency of 3.5%. The local charge-transport properties in the intermixed region, as observed via C-AFM, was found to be closely related to the photovoltaic properties, rather than the bulk-averaged properties or topological features

High-Pressure Synthesis, Crystal Structure, and Phase Stability Relations of a LiNbO₃‑Type Polar Titanate ZnTiO₃ and Its Reinforced Polarity by the Second-Order Jahn–Teller Effect

A polar LiNbO₃-type (LN-type) titanate ZnTiO₃ has been successfully synthesized using ilmenite-type (IL-type) ZnTiO₃ under high pressure and high temperature. The first principles calculation indicates that LN-type ZnTiO₃ is a metastable phase obtained by the transformation in the decompression process from the perovskite-type phase, which is stable at high pressure and high temperature. The Rietveld structural refinement using synchrotron powder X-ray diffraction data reveals that LN-type ZnTiO₃ crystallizes into a hexagonal structure with a polar space group <i>R</i>3<i>c</i> and exhibits greater intradistortion of the TiO₆ octahedron in LN-type ZnTiO₃ than that of the SnO₆ octahedron in LN-type ZnSnO₃. The estimated spontaneous polarization (75 μC/cm², 88 μC/cm²) using the nominal charge and the Born effective charge (BEC) derived from density functional perturbation theory, respectively, are greater than those of ZnSnO₃ (59 μC/cm², 65 μC/cm²), which is strongly attributed to the great displacement of Ti from the centrosymmetric position along the <i>c</i>-axis and the fact that the BEC of Ti (+6.1) is greater than that of Sn (+4.1). Furthermore, the spontaneous polarization of LN-type ZnTiO₃ is greater than that of LiNbO₃ (62 μC/cm², 76 μC/cm²), indicating that LN-type ZnTiO₃, like LiNbO₃, is a candidate ferroelectric material with high performance. The second harmonic generation (SHG) response of LN-type ZnTiO₃ is 24 times greater than that of LN-type ZnSnO₃. The findings indicate that the intraoctahedral distortion, spontaneous polarization, and the accompanying SHG response are caused by the stabilization of the polar LiNbO₃-type structure and reinforced by the second-order Jahn–Teller effect attributable to the orbital interaction between oxygen ions and d⁰ ions such as Ti⁴⁺

High-Pressure Synthesis of <i>A</i>‑Site Ordered Double Perovskite CaMnTi₂O₆ and Ferroelectricity Driven by Coupling of <i>A</i>‑Site Ordering and the Second-Order Jahn–Teller Effect

We successfully synthesized a novel ferroelectric <i>A</i>-site-ordered double perovskite CaMnTi₂O₆ under high-pressure and investigated its structure, ferroelectric, magnetic and dielectric properties, and high-temperature phase transition behavior. Optical second harmonic generation signal, by frequency doubling 1064 nm radiation to 532 nm, was observed and its efficiency is about 9 times as much as that of SiO₂ (α-quartz). This compound possesses a tetragonal polar structure with space group <i>P</i>4₂<i>mc</i>. <i>P</i>-<i>E</i> hysteresis measurement demonstrated that CaMnTi₂O₆ is also ferroelectric. A spontaneous polarization calculated by use of point charge model and the observed remnant polarization are 24 and 3.5 μC/cm², respectively. CaMnTi₂O₆ undergoes a ferroelectric–paraelectric order–disorder-type phase transition at 630 K. The structural analysis implies that both the ordering of shift of Mn²⁺ from the square-planar and the off-center displacement of Ti⁴⁺ in TiO₆ octahedra are responsible for ferroelectricity. CaMnTi₂O₆ belongs to a new class of ferroelectrics in which <i>A</i>-site ordering and second-order Jahn–Teller distortion are cooperatively coupled. The finding gave us a new concept for the design of ferroelectric materials

Changes in functional connectivity in resting state networks.

<p>Regions showing significant changes in functional connectivity in the (A) right executive control network (RECN), (B) left executive control network (LECN), and (C) ventral default mode network (vDMN) (p < 0.05 TFCE-cluster corrected for multiple comparison). HC–healthy control, BT–patients with brain tumor. Resting state networks are shown in yellow. Center of the cursor locates maximum significance.</p

Spatial distribution of tumors in MNI standard space superimposed on a standard anatomical template.

<p>This frequency map shows the number of patients with tumor in a given voxel.</p

Regions correlated with the right angular gyrus (Fig. 2C) obtained using seed-based connectivity analysis in (A) healthy controls and (B) patients with gliomas.

<p>Correlations in several regions in the left hemisphere, indicated by yellow circle in (A), are no longer significant in patients with gliomas although only the region in the middle temporal gyrus showed statistical significance. The maps showed voxels with t values < 3.5.</p