Combined use of UAV-SfM surveys, soil particle tracking with RFID tags and a sediment connectivity index to study plot-scale sediment transport.

To explore the processes of soil erosion at the plot scale, Digital surface model of Differences (DoD) maps (Unmanned Aerial Vehicle - Structure from Motion (UAV-SfM) method) and data from Radio Frequency Identification (RFID) tags were analysed. The comparison of differences in accuracy of UAV-SfM and 3D terrestrial laser scanner (TLS) measurements, and the integration of the UAV-SfM method and soil particle tracing with RFID tag locations were conducted to assess sediment transport in a plot in Fukushima prefecture, Japan. The Universal Soil Loss Equation (USLE) plot was installed and kept with no vegetation and no cultivation. Water and sediment discharges were measured at the outlet of the plot, and the topographic index of runoff and sediment connectivity (IC) -focused on surface roughness- was also estimated. Based on field surveys, four periods were defined. Locations of RFID tags were firstly determined by using orthoimages derived from the UAV-SfM method and then compared with those locations measured with a laser total station. The mean and standard deviation of difference amounts of UAV-SfM were of 1 and 3.3 mm, respectively. On average, the RFID tags were located with an accuracy of 3.1 cm (RMSE). Although data of tags tracing showed short transport distances with rill erosion, the results of the UAV-SfM surveys showed an increase of sediment connectivity (SC) over the study period that may explain the largest sediment discharge, especially of fine soil particles. The concurrence of higher values of SC as well as the development of new and longer rills demonstrated the important activity of net soil loss in our study site. The combination of distinct methods and techniques, all providing accurate measurements, shed light on the sediment transport process at short distances, which affects the net water and sediment discharge at larger scales.

Preparation of Biocompatible Poly(2-(methacryloyloxy)ethyl phosphorylcholine) Hollow Particles Using Silica Particles as a Template.

Hydrophilic poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) shows biocompatibility because the pendant phosphorylcholine group has the same chemical structure as the hydrophilic part of phospholipids that form cell membranes. Hollow particles can be used in various fields, such as a carrier in drug delivery systems because they can encapsulate hydrophilic drugs. In this study, vinyl group-decorated silica particles with a radius of 150 nm were covered with cross-linked PMPC based on the graft-through method. The radius of PMPC-coated silica particles increased compared to that of the original silica particles. The PMPC-coated silica particles were immersed in a hydrogen fluoride aqueous solution to remove template silica particles to prepare the hollow particles. The PMPC hollow particles were characterized by dynamic light scattering, infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy observations. The thickness of the hollow particle shell can be controlled by the polymerization solvent quality. When a poor solvent for PMPC was used for the polymerization, PMPC hollow particles with thick shells can be obtained. The PMPC hollow particles can encapsulate hydrophilic guest molecules by immersing the hollow particles in a high-concentration guest molecule solution. The biocompatible PMPC hollow particles can be used in a drug carrier.

Impacts of freeze-thaw processes and subsequent runoff on 137Cs washoff from bare land in Fukushima.

The deposited 137Cs is one of the long-lived radionuclides, that was released following the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, has been hydrologically transported as particulates in the terrestrial environment of the Fukushima region. The impact of freeze-thaw processes and subsequent runoff affecting the 137Cs flux and concentration in sediment discharge were revealed in bare land erosion plot following the FDNPP accident by detailed monitoring and laser scanner measurement on the soil surface. We found that surface topographic changes due to the frost-heaving during the winter-spring period, and rill formation during the summer. We also found the evident seasonal changes in 137Cs concentration; high during the early spring and gradually decreased thereafter, then surface runoff from the plot frequently occurred during spring and autumn when rainfall was high and reached a maximum in summer. From these results, the higher 137Cs concentration in spring was caused by a mixture of unstable surface sediment following freeze-thaw processes and then transported in the early spring, but erosion amount is not significant because of the less rainfall event. The sediment with a lower 137Cs concentration, which was supplied from the rill erosion and its expansion, was wash-offed during the summer, contributing most of the flux from erosion in bare land in Fukushima region. In case, heavy rainfall occurs in the early spring, caution is required because high concentrations of cesium may flow down into the river.

Thermo-Responsive Behavior of Amphoteric Diblock Copolymers Bearing Sulfonate and Quaternary Amino Pendant Groups.

Amphoteric diblock copolymers (S82A n) composed of poly(2-acrylamido-2-methylpropanesulfonic acid sodium salt) (PAMPS) with poly(3-(acrylamido)propyl trimethylammonium chloride) (PAPTAC) blocks were synthesized via reversible addition-fragmentation chain transfer (RAFT) radical polymerization. Three S82A n were prepared with a fixed degree of polymerization (DP) for the PAMPS block (= 82) and different DP values for the PAPTAC blocks ( n = 37, 83, and 183). The solubility of S82A n was studied at different sodium chloride (NaCl) concentrations. S82A83 precipitated in pure water due to attractive electrostatic interactions with interpolymer chains. Conversely, S82A37 and S82A183 dissolved in pure water. In pure water S82A37 dissolved as a unimer state due to electrostatic repulsion of excess anionic charges in the polymer chain. The long anionic PAMPS block segment in S82A37 covered the short cationic PAPTAC block segment within a single polymer chain. In pure water S82A183 dispersed as polyion complex micelles due to electrostatic repulsion of the cationic PAPTAC shells. The oppositely charged PAMPS and PAPTAC blocks in S82A183 formed a core, while the excess PAPTAC block formed shells. S82A n showed lower critical solution temperature (LCST)-type thermo-responsive behavior at certain NaCl concentrations, and the LCST increased with the NaCl concentration. The mechanism of LCST behavior involves hydrogen bonding interactions between the pendant amide groups and water molecules.