Phenolic from apple blossom "Hongro" inhibits the expression of proteins related to melanogenesis in B16F10 melanoma cells.

This study aimed to assess apple blossom extracts as potential natural whitening agents due to their ability to inhibit melanogenesis. Ethanol extracts of apple blossom (ABE) were assessed for biological activity in the B16F10 mouse melanoma cell line. ABE toxicity was assessed by thiazolyl blue tetrazolium bromide (MTT) assay. Levels of melanogenic enzyme expression in response to ABE supplementation were assessed by western blotting. Also assessed purified kaempferol, one of the phenolic compounds extracted from apple blossom, was evaluated using western blot analysis. The expression levels of cellular tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase-related protein (TRP)-1, and TRP-2 proteins related to melanogenesis decreased in a dose-dependent manner with ABE treatment of cells. Using nuclear magnetic resonance, we identified kaempferol in the ABE. Treatment of cells with purified kaempferol decreased the expression levels of tyrosinase and the MITF protein to a similar degree as that observed with ABE treatment. This suggests that the efficacy of melanogenesis-related inhibition demonstrated by ABE was due to kaempferol. ABE has an inhibitive effect on melanogenic enzymes and potentially can be applied to functional foods and cosmetics having a whitening effect as a natural material.

Increased incidence of respiratory tract cancers in people living near Portland cement plants in Korea.

PURPOSE: Portland cement contains carcinogens such as chromium and free silica, and hence, inhalation of cement dust can cause respiratory tract cancers. The purpose of this study was to determine whether living near a cement plant increases the risk of respiratory tract cancers. METHODS: The study population consisted of 341,793 people, all of whom lived in administrative districts within 3-km radius of ten cement plants in Korea. The respiratory tract cancer incidence data (International Classification of Diseases, ten revision code C00-C14 and C30-C34) for 2008-2012 were obtained from regional cancer registries. Standardized incidence ratios (SIRs) for each cancer site in the respiratory tract were calculated using an indirect standardization method. RESULTS: Compared with the general Korean population, the incidence of lung and bronchus cancer (C33-C34) was significantly higher in all subjects [SIR 1.15, 95% confidence interval (CI) 1.02-1.29] and especially in the men subjects (SIR 1.47, 95% CI 1.29-1.68) in our study population. In addition, the incidence of larynx cancer in men (SIR 1.64, 95% CI 0.97-2.59) and salivary gland cancer in women (SIR 3.03, 95% CI 0.98-7.07) living near cement plants was marginally increased. CONCLUSIONS: These results suggest that environmental exposure to Portland cement dust is a risk factor for respiratory tract cancers.

Reliable Piezoelectricity in Bilayer WSe2 for Piezoelectric Nanogenerators.

Recently, piezoelectricity has been observed in 2D atomically thin materials, such as hexagonal-boron nitride, graphene, and transition metal dichalcogenides (TMDs). Specifically, exfoliated monolayer MoS2 exhibits a high piezoelectricity that is comparable to that of traditional piezoelectric materials. However, monolayer TMD materials are not regarded as suitable for actual piezoelectric devices due to their insufficient mechanical durability for sustained operation while Bernal-stacked bilayer TMD materials lose noncentrosymmetry and consequently piezoelectricity. Here, it is shown that WSe2 bilayers fabricated via turbostratic stacking have reliable piezoelectric properties that cannot be obtained from a mechanically exfoliated WSe2 bilayer with Bernal stacking. Turbostratic stacking refers to the transfer of each chemical vapor deposition (CVD)-grown WSe2 monolayer to allow for an increase in degrees of freedom in the bilayer symmetry, leading to noncentrosymmetry in the bilayers. In contrast, CVD-grown WSe2 bilayers exhibit very weak piezoelectricity because of the energetics and crystallographic orientation. The flexible piezoelectric WSe2 bilayers exhibit a prominent mechanical durability of up to 0.95% of strain as well as reliable energy harvesting performance, which is adequate to drive a small liquid crystal display without external energy sources, in contrast to monolayer WSe2 for which the device performance becomes degraded above a strain of 0.63%.

Surface energy and wettability of van der Waals structures.

The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of hexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London-vdW force-mediated wettability.