Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties

Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe(2)O(4) MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T(2) relaxivities (r(2)) at 4.7 T and room temperature in the range of 60 to 300 mM(−1)s(−1), depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe(2)O(4) MNPs could be used as initial base cores of MRI T(2) CAs, with almost unique T(2) relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis. PACS: 75.75.Fk, 78.67.Bf, 61.46.D

RECIPE: How to Integrate ChatGPT into EFL Writing Education

The integration of generative AI in the field of education is actively being explored. In particular, ChatGPT has garnered significant interest, offering an opportunity to examine its effectiveness in English as a foreign language (EFL) education. To address this need, we present a novel learning platform called RECIPE (Revising an Essay with ChatGPT on an Interactive Platform for EFL learners). Our platform features two types of prompts that facilitate conversations between ChatGPT and students: (1) a hidden prompt for ChatGPT to take an EFL teacher role and (2) an open prompt for students to initiate a dialogue with a self-written summary of what they have learned. We deployed this platform for 213 undergraduate and graduate students enrolled in EFL writing courses and seven instructors. For this study, we collect students' interaction data from RECIPE, including students' perceptions and usage of the platform, and user scenarios are examined with the data. We also conduct a focus group interview with six students and an individual interview with one EFL instructor to explore design opportunities for leveraging generative AI models in the field of EFL education

Continuous Lithium Extraction from Aqueous Solution Using Flow-Electrode Capacitive Deionization

Flow-electrode-based capacitive deionization (FCDI) is a desalination process that uses electrostatic adsorption and desorption of ions onto electrode materials. It provides a continuous desalination flow with high salt removal performance and low energy consumption. Since lithium has been regarded as an essential element for the last few decades, the efficient production of lithium from the natural environment has been intensively investigated. In this study, we have extracted lithium ions from aqueous solution by using FCDI desalination. We confirmed that lithium and chloride ions could be continuously collected and that the salt removal rate depends on various parameters, including feed-flow rate and a feed saline concentration. We found that the salt removal rate increases as the feed-flow rate decreases and the feed salt concentration increases. Furthermore, the salt removal rate depends on the circulation mode of the feed solution (continuous feed stream vs. batch feed stream), which allows control of the desalination performance (higher capacity vs. higher efficiency) depending on the purpose of the application. The salt removal rate was highest, at 215.06 μmol/m−2s−1, at the feed rate of 3 mL/min and the feed concentration of 100 mg/L. We believe that such efficient and continuous extraction of lithium chloride using FCDI desalination can open a new door for the current lithium-production industry, which typically uses natural water evaporation