Carnitine (CAR), an amino acid derivative, has great potential as a facial exfoliating agent owing to its calcium chelating property under weakly acidic or neutral conditions. However, its application is limited by its poor transdermal penetration. To optimise its exfoliation efficacy with minimal concentration, we propose the ion-pair method. The ionic interaction between CAR and a zwitterionic substance was successfully monitored by measuring conductivity. The alterations of penetration and exfoliation efficacy for CAR addition to different types of counter ions were investigated in vitro and in vivo. We found that hydrogenated soya phosphatidylcholine (HSC), an amphiphilic counter ion, significantly increases the stratum corneum penetration and exfoliation efficacy of CAR. The changes of the CAR-HSC ionic interaction in the presence of calcium ions were also investigated by 1H nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra for amino groups of CAR first decreased with HSC and then gradually recovered and shifted as calcium ions were added. From the results, a noble exfoliating complex of CAR with high exfoliation efficacy could be proposed. Moreover, the results demonstrate that NMR spectroscopy is useful to obtain direct experimental evidence of the molecular dynamics simulations of the alteration of an exfoliating complex as it penetrates.

Solar light may cause skin photoaging, which may lead to erythema associated with inflammation, decreased skin elasticity, and wrinkles caused by collagen reduction. 1,2 Human skin synthesizes dark pigment known as melanin from melanocytes in epidermis to protect the skin cells from the solar radiation. However, individuals who do not desire hyperpigmentation seek cosmetical or pharmaceutical assistant to maintain a brighter skin color. Skin-brightening agents prevent melanogenesis via many pathways, resulting in reduced melanin production. 3,4 Since less melanin leads to less protection against solar lights, the contradictory between beauty and protection rises. To overcome the lack of protection, the application of additional protective agents, such as UV filters and skin-soothing agents, is essential. 2,5

In the stratum corneum, the intercellular junction made up of cadherin proteins provides the structural integrity of the framework. Ca 2+ ions are known to play a key role in maintaining this junction. In this study, we hypothesized that Ca 2+ chelation in stratum corneum will weaken the bond of the tissue and consequently promote exfoliation. Amino acids, ubiquitously existing as metabolites and building blocks of the body, have the molecular property to chelate Ca 2+ ions. In the current study, we verified the Ca 2+ chelating property of amino acids and demonstrated that amino acids can interfere with the interaction of cadherins, separate stratum corneum into pieces, and thereby stimulate the exfoliation process of skin. These results validate the importance of Ca 2+ ion in the skin exfoliation process. Importantly, our findings indicate that amino acids may be efficiently used for improving skin conditions.

4) Digital divide commonly means the gap among diverse stakeholders, businesses, physical areas, and individual people in terms of opportunities, accessibilities, and usabilities (Acılar, 2011). Lee and Park (2011) and Barzilai-Nahon (2006) suggested that the digital divide issues should be considered as an important public issue because proper public response may enhance or reduce the information gaps by the digital divide. This study is a follow-up study of the study of Lee and Park. This study's main aim is to clarify the changes of the digital divide in the rural areas during five years and to find out meaningful factors to reduce the gaps between the rural area and urban area. To achieve the research aim, this study analyzes the public data by ITSTAT and previous studies on the digital divide. Also this study follows the system thinking approach to model the causal relationships among diverse factors on the digital divide. With the results, this study suggests that the factors to measure the digital divide should be re-designed including smartphone penetration and accessibilities. Especially, current digital divide scoring factors should be considered in the way of social welfare.