Deleterious effects in reproduction and developmental immunity elicited by pulmonary iron oxide nanoparticles

With the extensive application of iron oxide nanoparticles (FeNPs), attention about their potential risks to human health is also rapidly raising, particularly in sensitive subgroups such as pregnant women and babies. In this study, we a single instilled intratracheally FeNPs (1, 2, and 4 mg/kg) to the male and female parent mice, mated, then assessed reproductive toxicity according to the modified OECD TG 421. During the pre-mating period (14 days), two female parent mice died at 4 mg/kg dose, and the body weight gain dose-dependently decreased in male and female parent mice exposed to FeNPs. Additionally, iron accumulation and the enhanced expression of MHC class II molecules were observed in the ovary and the testis of parent mice exposed to the highest dose of FeNPs, and the total sex ratio (male/female) of the offspring mice increased in the groups exposed to FeNPs. Following, we a single instilled intratracheally to their offspring mice with the same doses and evaluated the immunotoxic response on day 28. The increased mortality and significant hematological- and biochemical- changes were observed in offspring mice exposed at 4 mg/kg dose, especially in female mice. More interestingly, balance of the immune response was shifted to a different direction in male and female offspring mice. Taken together, we conclude that the NOAEL for reproductive and developmental toxicity of FeNPs may be lower than 2 mg/kg, and that female mice may show more sensitive response to FeNPs exposure than male mice. Furthermore, we suggest that further studies are necessary to identify causes of both the alteration in sex ratio of offspring mice and different immune response in male and female offspring mice.

Biological Toxicity and Inflammatory Response of Semi-Single-Walled Carbon Nanotubes

The toxicological studies on carbon nanotubes (CNTs) have been urgently needed from the emerging diverse applications of CNTs. Physicochemical properties such as shape, diameter, conductance, surface charge and surface chemistry of CNTs gained during manufacturing processes play a key role in the toxicity. In this study, we separated the semi-conductive components of SWCNTs (semi-SWCNTs) and evaluated the toxicity on days 1, 7, 14 and 28 after intratracheal instillation in order to determine the role of conductance. Exposure to semi-SWCNTs significantly increased the growth of mice and significantly decreased the relative ratio of brain weight to body weight. Recruitment of monocytes into the bloodstream increased in a time-dependent manner, and significant hematological changes were observed 28 days after exposure. In the bronchoalveolar lavage (BAL) fluid, secretion of Th2-type cytokines, particularly IL-10, was more predominant than Th1-type cytokines, and expression of regulated on activation normal T cell expressed and secreted (RANTES), p53, transforming growth factor (TGF)-β, and inducible nitric oxide synthase (iNOS) increased in a time-dependent manner. Fibrotic histopathological changes peaked on day 7 and decreased 14 days after exposure. Expression of cyclooxygenase-2 (COX-2), mesothelin, and phosphorylated signal transducer and activator of transcription 3 (pSTAT3) also peaked on day 7, while that of TGF-β peaked on days 7 and 14. Secretion of histamine in BAL fluid decreased in a time-dependent manner. Consequently, we suggest that the brain is the target organ of semi-SWCNTs brought into the lung, and conductance as well as length may be critical factors affecting the intensity and duration of the inflammatory response following SWCNT exposure

Quantitative agreement of Dzyaloshinskii-Moriya interactions for domain-wall motion and spin-wave propagation

The magnetic exchange interaction is the one of the key factors governing the basic characteristics of magnetic systems. Unlike the symmetric nature of the Heisenberg exchange interaction, the interfacial Dzyaloshinskii-Moriya interaction (DMI) generates an antisymmetric exchange interaction which offers challenging opportunities in spintronics with intriguing antisymmetric phenomena. The role of the DMI, however, is still being debated, largely because distinct strengths of DMI have been measured for different magnetic objects, particularly chiral magnetic domain walls (DWs) and non-reciprocal spin waves (SWs). In this paper, we show that, after careful data analysis, both the DWs and SWs experience the same strength of DMI. This was confirmed by spin-torque efficiency measurement for the DWs, and Brillouin light scattering measurement for the SWs. This observation, therefore, indicates the unique role of the DMI on the magnetic DW and SW dynamics and also guarantees the compatibility of several DMI-measurement schemes recently proposed.Comment: 24 pages, 5 figure

Floristic study of Cheondeungsan Mountain in Korea

AbstractThe distribution of native plants of Cheondeungsan Mountain (807 m, N 37°05'00“–37°05'30”, E 128°00'0“–128°02'0”) in Chungcheongbuk-do was determined and the major flora were identified. During field investigations carried out from May 2011 to October 2011, 87 families, 254 genera, and 369 taxonomic groups (327 species, 4 subspecies, 33 varieties, and 5 forms) were confirmed, and the distribution of 219 taxonomic groups was discovered for the first time. The distribution of four endemic plants of Korea, including Ajuga spectabilis Nakai and Salvia chanryoenica Nakai, and that of Penthorum chinense Pursh, a Grade V specific plant species, was found. There were 20 taxa of naturalized plants at Cheondeungsan; the growth and development of plants that are harmful to the ecosystem, such as Ambrosia artemisiifolia L., Ambrosia trifida L., Eupatorium rugosum Houtt., and Aster pilosus Willd., was observed around the forest paths and lowlands

All-fiber wavelengthtunable acousto-optic switch,”

Abstract-In this paper, we demonstrate a novel all-fiber wavelength-tunable acoustooptic switch utilizing intermodal coupling in a two-mode fiber (TMF). Its all-fiber configuration consisting of a fiber acoustooptic tunable filter and a mode-selective coupler results in the low loss ( 2 dB) operation. The operating bandwidth 50 nm, the switching time of 40 sec, and the crosstalk of 20 dB were achieved. By controlling the design parameters of the two-mode fiber, the 3-dB bandwidth of the switched signal was varied from 2.5 nm to 35 nm. A novel all-fiber dynamic optical add-drop multiplexer is also demonstrated using two acoustooptic switches in series. Index Terms-Acoustooptic devices, acoustooptic switches, optical fiber devices, optical fiber switches, wavelength division multiplexing (WDM)

Spacer grid effects on the heat transfer enhancement during a reflood

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.An experimental study using 6x6 and 2x2 square lattice rod bundles has been performed to investigate the effects of spacer grids on the heat transfer enhancement during a bottom-reflood phase. The spacer grids improve a turbulent mixing of flow and induces breakup of large droplets into smaller ones. These result in the heat transfer enhancement between the fuel rods and the surrounding fluid. Since the geometry of the spacer grid affects the turbulent mixing and droplet breakup behaviors, three types of spacer grids with different geometry were tested in the present study. In order to investigate the heat transfer enhancement by spacer grids, single-phase steam cooling and droplet breakup by spacer grid were separately investigated. For the convective heat transfer enhancement in singlephase steam flow, the heater rod surface temperatures were measured in the vicinity of the space grid. In single-phase steam cooling experiment, the heat transfer was enhanced at upstream and downstream of spacer grids. Downstream of the spacer, the heat transfer enhancement decays with the distance from the top end of the spacer grid exponentially. The heat transfer enhancement depends on the Reynolds number as well as the flow blockage ratio. A new empirical correlation was developed in order to account for the effect of the Reynolds number. For the droplet breakup experiment, the sizes and velocities of droplets were measured across the spacer grid. The droplet breakup ratio decreases with increasing the Weber number of the droplet impacting on the spacer grid. The droplet breakup ratio by spacer grids was relatively higher than conventional correlations.dc201