To evaluate the effects of type of micaceous mineral and degree of weathering on the ability to adsorb and desorb radiocaesium (RCs) ions, various levels of weathering were induced (K‐depletion) in ...three types of micaceous minerals: biotite, muscovite and illite. The ability to adsorb RCs was represented by RCs interception potential (RIP) and a desorption ratio was determined by the amount of 137Cs desorbed from the minerals by 1 M ammonium acetate (137Cs desorption ratio). The RIP values were in the order of illite > biotite > muscovite. The RIP values for biotite gradually increased with the release of up to ~50% of the K+ from interlayer sites but then decreased with the further release of K+, up to ~100%, which was associated with the formation of a fully expanded interlayer: vermiculite. The change from increasing to decreasing RIP due to the weathering of the biotite strongly indicated that the selective adsorption sites for RCs are not located in an expanded interlayer but in intermediate sites between non‐expanded and expanded interlayers: frayed edge sites (FES). In contrast, for both the muscovite and illite, the RIP only increased. The 137Cs desorption ratio, <7% for all the samples, tended to decrease with increasing degrees of weathering and did not differ greatly by mineral type. These results contribute to a more accurate prediction of the risk of RCs transfer from soils to crops and the understanding of the weathering processes of micaceous minerals in soils.
Highlights
Radiocaesium adsorption and desorption was investigated for gradually K‐removed biotite, muscovite and illite.
Vermiculitization of biotite via K removal firstly increased then decreased the frayed edge sites (FES).
Adsorption was influenced by di/trioctahedral character and charge localization, and desorption by degree of weathering.
These results lead to better understanding of the weathering processes of micaceous minerals and fate of RCs in soils.
•Combining 133Cs ssNMR and XRD data allows for explicit identification of Cs binding sites within composite amorphous-crystalline geopolymers.•133Cs ssNMR reports on a non-random distribution of Cs ...ions between the phases within the geopolymer matrix, with preferential incorporation of Cs into the zeolite F phase.•Post-leaching ssNMR data reveal changes in this distribution following leaching experiments, showing retention of Cs in the zeolite F phase, and its selective depletion from the amorphous phase.
Geopolymers are promising candidates for nuclear-waste immobilization, and more specifically for the immobilization of radioactive cesium. Low-Si metakaolin-based geopolymers cured at temperatures of 40 °C in the presence of Cs ions generate a mixture of amorphous and crystalline phases including a Cs-bearing zeolite F phase. Using a combination of 133Cs solid-state NMR and X-ray powder diffraction measurements we were able to show that Cs preferentially binds to zeolite F even when zeolite F is not the dominant phase in the matrix. Moreover, post-leaching NMR experiments indicate that zeolite F binds Cs more efficiently than the remaining crystalline or amorphous phases. Tailoring geopolymer formulations so that a large fraction of zeolite F is generated may therefore be a promising route for the production of immobilization matrices for cesium.
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The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the most significant quantity of radiocesium into the environment since Chernobyl, and detailed measurements over the initial 5 ...years provide new insights into fluvial redistribution of radiocesium. We found that the high initial activity concentration of 137Cs-bearing suspended sediment in rivers was followed by a steep exponential decline (λ1) which extended to approximately 1 year after the accident, while the rate of initial decline in radiocesium activity concentration in water was an order of magnitude higher than rates measured after Chernobyl. Fluvial transport of 137Cs to the ocean from the Abukuma river totaled 12 TBq between June 2011 and August 2015 and almost all this radiocesium (96.5%) was transported in the particulate form. The primary sources of 137Cs were paddy fields, farmland, and urban areas plaque-forming unit (PFU), discharging 85% of the exported 137Cs from 38% of the watershed area. After 1 year, activity concentrations were lower and exhibited a more gradual secondary decline (λ2) which was associated with reduced radiocesium losses from PFU areas, while forest areas continue to represent more stable contaminant stores.
To understand the relationship between the radioactive cesium (Cs) concentration in muscle of Japanese flounder Paralichthys olivaceus and the species' biological characteristics (size, sex, and age) ...under conditions of ecological equilibrium (i.e., distributed among ecosystem components over sufficient time, and with nearly constant ratios of Cs concentration in organisms to the concentration in water) as existed before the accident at the Fukushima Dai‐ichi Nuclear Power Station (FDNPS), Japan, in 2011, we examined stable Cs, as it is thought to exist in equilibrium in the environment and behave similarly to radioactive Cs in aquatic animals. The concentration of stable Cs in 241 P. olivaceus (range 216–782 mm total length TL) collected in Sendai Bay, approximately 90 km north of the FDNPS, in June–July 2015 was expressed as an exponential function with size as an independent variable; the results show the concentration of stable Cs doubled with an increase in TL of 442 mm. Next, to evaluate the cause of the size‐dependent change in stable Cs concentration, we examined 909 individuals (200–770 mm TL) collected in September 2013–July 2015 to determine their feeding habit based on size. Analysis of the frequency of occurrence of prey organisms in stomach contents showed that sand lance Ammodytes japonicus (55–180 mm standard length SL) was the most consistently consumed across size classes. Analysis on a wet‐mass basis showed that A. japonicus and anchovy Engraulis japonicus (65–130 mm SL) were the main food of P. olivaceus sized 200–599 mm TL, whereas chub mackerel Scomber japonicus (120–230 mm SL) and two species of flatfishes (180–205 mm SL) were abundant in the diet of P. olivaceus sized ≥600 mm TL. All these prey items were presumed to have similar concentrations of stable Cs. Based on the above, the effect of diet on the relationship between stable Cs in muscle and fish size was considered negligible. That the diet of P. olivaceus largely did not change with size was also confirmed by C and N stable isotope ratios in P. olivaceus and their prey species. Therefore, the Cs–size relationship is probably determined by changes in the balance between the rate of Cs intake from food and seawater and the excretion rate during growth, both of which change as functions of body mass. Values of stable Cs concentrations among environmental components and animals appear to be a valid indicator for understanding the radioactive Cs distribution in the marine environment and aquatic animals under the equilibrium state, as existed before the 2011 nuclear accident.
We report an idea for the synthesis of oligopeptides using a solvent‐free ball milling approach. Our concept is inspired by block play, in which it is possible to construct different objects using ...segments (blocks) of different sizes and lengths. We prove that by having a library of short peptides and employing the ball mill mechanosynthesis (BMMS) method, peptides can be easily coupled to form different oligopeptides with the desired functional and biological properties. Optimizing the BMMS process we found that the best yields we obtained when TBTU and cesium carbonate were used as reagents. The role of Cs2CO3 in the coupling mechanism was followed on each stage of synthesis by 1H, 13C and 133Cs NMR employing Magic Angle Spinning (MAS) techniques. It was found that cesium carbonate acts not only as a base but is also responsible for the activation of substrates and intermediates. The unique information about the BMMS mechanism is based on the analysis of 2D NMR data. The power of BMMS is proved by the example of different peptide combinations, 2+2, 3+2, 4+2, 5+2 and 4+4. The tetra‐, penta‐, hexa‐, hepta‐ and octapeptides obtained under this project were fully characterized by MS and NMR techniques.
We present a concept inspired by playing with blocks, in which it is possible to construct various objects from segments (blocks) of different sizes and lengths. An attempt is made to explain the mechanism of coupling reaction in a ball mill in the presence of cesium carbonate. The usefulness of the method in the synthesis of oligopeptides has been proven.
Cesium lead iodide (CsPbI
) is a promising semiconductor with a suitable band gap for optoelectronic devices. CsPbI
has a metastable perovskite phase that undergoes a phase transition into an ...unfavorable nonperovskite phase in an ambient environment. This phase transition changes the optoelectronic properties of CsPbI
and hinders its potential for device applications. Therefore, it is of central importance to understand the kinetics of such instability and develop strategies to control and stabilize the perovskite phase. Here, we use ultralong CsPbI
nanowires as a model platform to investigate the phase transition kinetics. Our results depict the role of environmental stressors (moisture and temperature) in controlling the phase transition dynamics of CsPbI
, which can serve as guiding principles for future phase transition studies and the design of related photovoltaics. Furthermore, we demonstrate the controllability of phase propagation on individual nanowires by varying the moisture level and temperature.
The Fukushima nuclear accident released radioactive materials into the environment over the entire Northern Hemisphere in March 2011, and the Japanese government is spending large amounts of money to ...clean up the contaminated residential areas and agricultural fields. However, we still do not know the exact physical and chemical properties of the radioactive materials. This study directly observed spherical Cs-bearing particles emitted during a relatively early stage (March 14-15) of the accident. In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble. Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition. The finding of the spherical Cs particles will be a key to understand the processes of the accident and to accurately evaluate the health impacts and the residence time in the environment.
A facile synthetic procedure for the preparation of α‐trifluoromethyl carboxylic acids and esters was achieved through multicomponent coupling reactions between gem‐difluoroalkenes, cesium fluoride, ...and carbon dioxide. The products were generated in moderate to excellent yields, and the synthetic utility of this method was demonstrated through the preparation of trifluoromethylated versions of popular nonsteroidal anti‐inflammatory drugs (NSAIDs).
Easy as 1‐2‐3: Three‐component coupling reactions of gem‐difluoroalkenes with cesium fluoride and carbon dioxide affords α‐trifluoromethyl carboxylic acids and esters in moderate to excellent yields. The synthetic utility of this method was demonstrated by the preparation of trifluoromethylated versions of popular nonsteroidal anti‐inflammatory drugs (NSAIDs).
Wild boar meat containing radioactive cesium (Cs) of approximately 1,000 Bq/kg (134Cs+137Cs) was processed into bacon, sausage, and ham. To understand the concentration and quantity change of ...radioactive Cs, the processing factor (Pf) and food processing retention factor (Fr) were calculated. The radioactive Cs quantity in the meat did not reduce during smoking. The dehydration-related meat mass reduction during smoking without decrease of radioactive Cs led to Cs condensation in the bacon compared with the raw rib meat before processing, resulting in a Pf of 1.18. Soaking in liquid, such as pickling in liquid and desalting or boiling in water, effectively removed radioactive Cs by leakage into water. Therefore, the Fr value of the boiled ham produced from a loin meat block through three liquid-soaking processes was 0.27. The Pf value of the boiled ham was 0.30 due to meat block mass reduction after boiling as a result of dehydration, along with protein thermal denaturation-related muscle tissue shrinkage. The steamed ham Fr value was 0.53, because the removal of radioactive Cs was less efficient by steaming than by boiling. The Pf value of the steamed ham was 0.54, almost the same as the Fr value, because the mass decrease rate was the same as the radioactive Cs decrease rate by steaming. The Fr and the Pf values of the boiled sausage, whose processing did not include soaking in the pickling liquid, were 0.64 and 0.62, respectively. Steaming the sausage meat did not remove radioactive Cs during the dehydration-related mass reduction, leading to Fr and Pf values of 1.01 and 1.17, respectively. This study found that processing into boiled ham was the most effective measure for reducing radioactive Cs quantity and concentration in raw meat. Processing into bacon and steamed sausage showed no Cs quantity reduction, with the moisture loss resulting in Cs condensation compared with the raw material.
Device performance and in particular device stability for blue perovskite light-emitting diodes (PeLEDs) remain considerable challenges for the whole community. In this manuscript, we conceive an ...approach by tuning the 'A-site' cation composition of perovskites to develop blue-emitters. We herein report a Rubidium-Cesium alloyed, quasi-two-dimensional perovskite and demonstrate its great potential for pure-blue PeLED applications. Composition engineering and in-situ passivation are conducted to further improve the material's emission property and stabilities. Consequently, we get a prominent film photoluminescence quantum yield of around 82% under low excitation density. Encouraged by these findings, we finally achieve a spectra-stable blue PeLED with the peak external quantum efficiency of 1.35% and a half-lifetime of 14.5 min, representing the most efficient and stable pure-blue PeLEDs reported so far. The strategy is also demonstrated to be able to generate efficient perovskite blue emitters and PeLEDs in the whole blue spectral region (from 454 to 492 nm).
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