Oral administration of active pharmaceutical ingredients is desirable because it is easy, safe, painless, and can be performed by patients, resulting in good medication adherence. The mucus layer in the gastrointestinal (GI) tract generally acts as a barrier to protect the epithelial membrane from foreign substances; however, in the absorption process after oral administration, it can also disturb effective drug absorption by trapping it in the biological sieve structured by mucin, a major component of mucus, and eliminating it by mucus turnover. Recently, functional nanocarriers (NCs) have attracted much attention due to their immense potential and effectiveness in the field of oral drug delivery. Among them, NCs with mucopenetrating and mucoadhesive properties are promising dosage options for controlling drug absorption from the GI tracts. Mucopenetrating and mucoadhesive NCs can rapidly deliver encapsulated drugs to the absorption site and/or prolong the residence time of NCs close to the absorption membrane, providing better medications than conventional approaches. The surface characteristics of NCs are important factors that determine their functionality, owing to the formation of various kinds of interactions between the particle surface and mucosal components. Thus, a deeper understanding of surface modifications on the biopharmaceutical characteristics of NCs is necessary to develop the appropriate mucosal drug delivery systems (mDDS) for the treatment of target diseases. This review summarizes the basic information and functions of the mucosal layer, highlights the recent progress in designing functional NCs for mDDS, and discusses their performance in the GI tract.

We have studied the magnetic and Fermi surface properties in a ferromagnet UGa ₂ . The electrical resistivity, elastic constant, thermal expansion coefficient, thermoelectric power, magnetic susceptibility and Hall coefficient indicate highly anisotropic properties, reflecting the hexagonal structure. The 5 f ² - and 5 f ³ -CEF schemes, based on the localized 5 f -electron nature, are discussed to understand the magnetic susceptibility and magnetization data. We have also done the magnetoresistance and de Haas-van Alphen (dHvA) experiments to investigate the Fermi surface properties. Both data are very complicated, implying that the Fermi surface is a multiply-connected one. They are explained neither by the localized 5 f ² - and 5 f ³ -core models nor by the spin-polarized 5 f -itinerant model. The cyclotron mass is, however, rather light, ranging from 0.17 to 6.2 m ₀ , which is consistent with the electronic specific heat coefficient of 11 mJ/K ² ·mol.

We performed muon spin relaxation measurements on randomly aligned single-crystalline samples of SmRu ₄ P ₁₂ down to 0.02 K to investigate static and dynamical magnetic properties in low fields. The local field at the muon site develops gradually with decreasing temperature below a metal–insulator transition temperature of T _MI =16.5 K, growing steeply below T ^′ =3 K with an accompanying suppression of magnetic fluctuations. We discuss the contribution of a possible octupole moment to the local magnetic states and the magnetic anomaly at T ^′ .

We have investigated high field magnetization on single-crystalline CeFe ₂ Ge ₂ which is classified as a heavy fermion with a non-magnetic ground state. A clear metamagnetic anomaly, which resembles those reported in CeRu ₂ Si ₂ , was observed around 300 kOe for the field along the c -axis. The T ^3/2 dependence of the electrical resistivity in a wide temperature range from around 15 K down to 2 K, followed by T ² dependence at lower temperatures, is apparently similar to that in CeNi ₂ Ge ₂ which is close to a quantum critical point.