Magnetic-field enhanced modulation transfer spectroscopy: theory and experiment.

We herein present a theoretical and experimental study on magnetic-field enhanced modulation transfer spectroscopy (MTS) for the 5S1/2 (F = 1) → 5P3/2 (F' = 0, 1, and 2) transitions of 87Rb atoms. The density matrix equations are solved numerically to obtain the MTS spectra and an excellent agreement is found between the experimental and calculated results. In particular, the enhancement of the MTS signal for the F = 1 → F' = 0 transition in the presence of the magnetic field is directly verified based on the comparison of the results calculated by neglecting with those calculated including the Zeeman coherences in the F = 1 ground state. The unexpected behaviors of the F = 1 → F' = 1 transition are also examined.

Atmospheric deposition of inorganic nutrients to the Western North Pacific Ocean.

We evaluated the potential impacts of atmospheric deposition on marine productivity and inorganic carbon chemistry in the northwestern Pacific Ocean (8-39°N, 125-157°E). The nutrient concentration in atmospheric total suspended particles decreased exponentially with increasing distance from the closest land-mass (Asia), clearly revealing anthropogenic and terrestrial contributions. The predicted mean depositional fluxes of inorganic nitrogen were approximately 34 and 15 µmol m-2 d-1 to the west and east of 140°E, respectively, which were at least two orders of magnitude greater than the inorganic phosphorus flux. On average, atmospheric particulate deposition would support 3-4% of the net primary production along the surveyed tracks, which is equivalent to ~2% of the dissolved carbon increment caused by the penetration of anthropogenic CO2. Our observations generally fell within the ranges observed over the past 18 years, despite an increasing trend of atmospheric pollution in the source regions during the same period, which implies high temporal and spatial variabilities of atmospheric nutrient concentration in the study area. Continued atmospheric anthropogenic nitrogen deposition may alter the relative abundances of nitrogen and phosphorus.

Sedimentation history and excess metal deposition in estuarine barrier-island system of the Nakdong River, South Korea.

Human activities, such as dam construction and reclamation, can affect sedimentation rates as well as sediment topography and transport in estuaries such as the Nakdong River Estuary. To investigate the sedimentation history, two sediment cores (1-2 m long) were sampled in tidal flats of the estuary. In addition, surface sediments were collected to study present sedimentation environments that appear to be three environments locally: 1) fine-grained sediment deposition; 2) sediments under stronger hydraulic energy; and 3) sandy sediments with good sorting. At the fine sediment deposition, environmental sensitive fraction of elements (Cu, Pb, As, and Co) show an increased sedimentation flux after the dam construction. On the other hand, organic matter-normalized Pb-210 concentrations in sediment core reveal that marine-originated organic matter is predominant in the upper ~45 cm of sediment layers, indicating a significant change in sedimentation history related to massive sedimentation within the Nakdong River Estuary.

Atmospheric deposition of anthropogenic inorganic nitrogen in airborne particles and precipitation in the East Sea in the northwestern Pacific Ocean.

The atmospheric deposition of anthropogenic nitrogen is an increasingly important new source of nitrogen to the ocean. Coastal areas east of the Korean Peninsula are suitable for the investigation of the effects of atmospheric anthropogenic nitrogen on the ocean nutrient system because of the low riverine discharge rates and the prevailing influence of the East Asian outflow. Thus, we measured the concentrations of nitrate (NO3-) and ammonium (NH4+) in airborne particles and in precipitation from March 2014 to February 2016 at a coastal site (37.08°N, 129.41°E) on the east coast of Korea. The dry deposition of NO3- (27-30 mmol N m-2 yr-1) was far greater than that of NH4+ (6-8 mmol N m-2 yr-1). The greater rate of dry NO3- deposition was associated with air masses traveling over northeastern China and central Korea. In contrast, the rates of wet deposition of NO3- (17-24 mmol N m-2 yr-1) and NH4+ (14-27 mmol N m-2 yr-1) were comparable and were probably associated with in-cloud scavenging of these ions. The results indicate that the total deposition of NO3- and NH4+ combined could contribute to ~2.4% and ~1.9% of the primary production in the coastal areas east of the Korean Peninsula and in the East Asian marginal seas, respectively, which would be a lower bound because the dry deposition of reactive nitrogen gas was not included. Our study shows that the atmospheric input of anthropogenic NO3- and NH4+ may substantially increase phytoplankton biomass in the coastal waters of the East Sea near the Korean Peninsula.

Depositional environment classification based on environmental variables of South Korea's Nakdong River Estuary barrier-lagoon system.

Anthropogenic activities have altered the geomorphological and ecological conditions of the Nakdong River Estuary (NRE) dramatically over the last century. The objectives of this study were to classify NRE sub-environments and to identify their unique ecological functions. The first step in classification was the establishment of 14 a priori sub-environmental groups based on landscape factors. Surface sediments obtained for these groups were analyzed for factors related to grain size and organic matter. Based on the results, the NRE was divided into two primary estuarine environment divisions: (1) a mixed marine and terrestrial environment influenced primarily by land; and (2) a principally marine environment influenced primarily by the ocean. Using multivariate analysis, we subdivided these primary estuarine divisions into six sub-environments, including Sub-1 and -2 in the former and Sub-3, -4, -5, and -6 in the latter.

Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.

We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10-5 g/m2/yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems.

Strategic approaches for enhancement of in vivo transbuccal peptide drug delivery in rabbits using iontophoresis and chemical enhancers.

PURPOSE: To evaluate the feasibility of iontophoresis and the combination effects with chemical enhancers on in vivo hypocalcemic effect of transbuccally delivered salmon calcitonin (sCT). METHODS: N-acetyl-L-cysteine (NAC), sodium deoxyglycocholate (SDGC), and ethanol were used as chemical enhancers; and 0.5 mA/cm(2) fixed electric current was employed as a physical enhancer. sCT hydrogel was applied to rabbit buccal mucosa, and blood samples were obtained via the central auricular artery. Blood calcium level was measured by calcium kit and the conformational changes of buccal mucosa were investigated with FT-IR spectroscopy. Hematoxylin/eosin staining was used for the histological evaluation of buccal mucosa. RESULTS: Iontophoresis groups except iontophoresis-NAC group showed significant hypocalcemic effect compared to negative control, in particular iontophoresis-SDGC combination group showed fast onset of action as well as sustained hypocalcemic effect (p < 0.05). FT-IR result demonstrated the reduction of buccal barrier function, and the histological study showed a decrease in buccal thickness as well as minor damage to the dermal-epidermal junctions in the enhancing method groups; however, the damaged tissues virtually recovered within 24 h after the removal of electrodes. CONCLUSIONS: Iontophoresis and combination with SDGC were found to be safe and potential strategies for transbuccal peptide delivery in vivo.

Enhanced transbuccal salmon calcitonin (sCT) delivery: effect of chemical enhancers and electrical assistance on in vitro sCT buccal permeation.

This study investigates the combined effect of absorption enhancers and electrical assistance on transbuccal salmon calcitonin (sCT) delivery, using fresh swine buccal tissue. We placed 200 IU (40 µg/mL) of each sCT formulation--containing various concentrations of ethanol, N-acetyl-L-cysteine (NAC), and sodium deoxyglycocholate (SDGC)--onto the donor part of a Franz diffusion cell. Then, 0.5 mA/cm(2) of fixed anodal current was applied alone or combined with chemical enhancers. The amount of permeated sCT was analyzed using an ELISA kit, and biophysical changes of the buccal mucosa were investigated using FT-IR spectroscopy, and hematoxylin-eosin staining methods were used to evaluate histological alteration of the buccal tissues. The flux (J(s)) of sCT increased with the addition of absorption enhancer groups, but it was significantly enhanced by the application of anodal iontophoresis (ITP). FT-IR study revealed that all groups caused an increase in lipid fluidity but only the groups containing SDGC showed statistically significant difference. Although the histological data of SDGC groups showed a possibility for tissue damage, the present enhancing methods appear to be safe. In conclusion, the combination of absorption enhancers and electrical assistance is a potential strategy for the enhancement of transbuccal sCT delivery.

Atmospheric transport of water-soluble ions (NO3(-), NH4(+) and nss-SO4(2-)) to the southern East Sea (Sea of Japan).

Atmospheric deposition of different types of aerosols over the southern East Sea has received little attention in terms of seawater biogeochemistry. We investigated the concentrations of water-soluble ions (NO3(-), NH4+ and nss-SO4(2-)) in the aerosols associated with air mass transport patterns arriving at the east coast of Korea, adjacent to the southern East Sea, in order to determine source regions affecting chemical composition of aerosols and to assess the atmospheric pathway as a significant controlling mechanism of the biogeochemistry in this marginal sea. Concentrations of certain elements (Al, Na, Ca, V, Zn and Pb) together with the water-soluble ions were measured in the aerosol samples (n=34) collected during the period March 2002-February 2003. The geometric mean concentrations of the water-soluble ions were NO3(-) 2.98 (0.56-16.22), NH4+ 1.42 (0.37-6.73) and nss-SO4(2-) 2.47 (0.17-17.35) microgm(-3). The backward trajectories revealed that air masses passing slowly over eastern China contributed more to increases in the concentrations of water-soluble ions than those associated with fast-moving northwesterly and maritime winds. Therefore, the correlation between the NH4+ and NO3+ concentrations increased, suggesting that gas-phase NH3 and HNO3 was forming fine-mode NH4NO3. The atmospheric N input accounted for approximately 10% of new production over the southern East Sea on an annual scale, while it accounted for over approximately 25% of new production during the water column stratification seasons (summer and early fall).

Atmospheric metal and phosphorus concentrations, inputs, and their biogeochemical significances in the Japan/East Sea.

Atmospheric metals and phosphorus over the southern Japan/East Sea were investigated in order to evaluate their sources, concentrations and inputs, and to identify their biogeochemical roles in this marginal sea. Aerosols were collected on the east coast of Korea from February 2002 to April 2003 (n=101) as well as at a remote island (Ulleung) and on a ship from February 2002 to June 2003 (n=13). The aerosols were analyzed for Al, Co, Cu, Ni, P, Pb and Zn. Simultaneous collections of aerosols at both coast and offshore were performed, and several high dust aerosols (Al>5 microg m(-3)) were collected at both regions. At the coastal site, both dust mineral and pollutants were transported by westerly winds from the Asian continent, but local emissions were significant (e.g., Cu, Ni, P and Zn) as well during the summer monsoon (May-August). The experimental relationships between the coast and offshore sites were defined. From these relationships, it was possible to obtain the annually averaged atmospheric metal and P concentrations over the southern Japan/East Sea, which has increased by over 2 times for the last decade. Through the estimation of atmospheric metal and phosphorus fluxes and comparisons with inputs from the Tsushima Warm Current, the atmospheric pathway was found to be a significant source for Al, Pb and Zn.