Pusan National University

About: Pusan National University is a education organization based out in Busan, South Korea. It is known for research contribution in the topics: Catalysis & Population. The organization has 24124 authors who have published 45054 publications receiving 819356 citations. The organization is also known as: Busan National University & Pusan University.

Soil macronutrient sensing for precision agriculture

Abstract: Accurate measurements of soil macronutrients (i.e., nitrogen, phosphorus, and potassium) are needed for efficient agricultural production, including site-specific crop management (SSCM), where fertilizer nutrient application rates are adjusted spatially based on local requirements. Rapid, non-destructive quantification of soil properties, including nutrient levels, has been possible with optical diffuse reflectance sensing. Another approach, electrochemical sensing based on ion-selective electrodes or ion-selective field effect transistors, has been recognized as useful in real-time analysis because of its simplicity, portability, rapid response, and ability to directly measure the analyte with a wide range of sensitivity. Current sensor developments and related technologies that are applicable to the measurement of soil macronutrients for SSCM are comprehensively reviewed. Examples of optical and electrochemical sensors applied in soil analyses are given, while advantages and obstacles to their adoption are discussed. It is proposed that on-the-go vehicle-based sensing systems have potential for efficiently and rapidly characterizing variability of soil macronutrients within a field.

Room-temperature ferromagnetism in (Zn1-xmnx)GeP2 semiconductors

Abstract: We report on the discovery of a room-temperature ferromagnetic semiconductor in chalcopyrite $({\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}){\mathrm{GeP}}_{2}$ with ${T}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}312\mathrm{K}$. We have also observed that, at temperatures below 47 K, samples for $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.056$ and 0.2 show a transition to the antiferromagnetic (AFM) state, so that ferromagnetism is well defined to be present between 47 and 312 K. The observation that the AFM phase is most stable at low temperatures is consistent with the predictions of full-potential linearized augmented plane wave total energy calculations and has consequences for other chalcopyrite materials.

Few layered black phosphorus/MoS2 nanohybrid: A promising co-catalyst for solar driven hydrogen evolution

Abstract: Exploring active and stable photocatalysts is an essential requirement for boosting the efficiency of photocatalytic water splitting to obtain clean hydrogen fuel. Here, a few layered black phosphorus/MoS2 (BP-MoS2) nanohybrid was successfully prepared and verified it for photocatalytic hydrogen evolution using CdS nanorods as light absorbers. The resulting nanohybrids manifest remarkable catalytic performance with high amount of H2 production (CdS/BP-MoS2: 183.24 mmol h–1 g–1) and outstanding catalytic stability. The observed amount of H2 is much higher than that of various CdS/BP and CdS/MoS2 based nanohybrids reported earlier. We expect that the demonstrated new heterostructured design strategy may bring novel insights to develop low-price noble metal free photocatalysts for hydrogen evolution.

Wrinkled Surface-Mediated Antibacterial Activity of Graphene Oxide Nanosheets

Abstract: Surface wrinkles are commonly observed in large-scale of graphene films. As a new feature, the wrinkled surface of graphene films may directly affect bacterial viability by means of various interactions of bacterial cells with graphene sheets. In the present study, we introduce a wrinkled surface geometry of graphene oxide (GO) thin films for antibacterial application. Highly wrinkled GO films were formed by vacuum filtration of a GO suspension through a prestrained filter. Several types of wrinkled GO surfaces were obtained with different roughness grades determined by root-mean-square values. Antibacterial activity of the fabricated GO films toward three different bacterial species, Escherichia coli, Mycobacterium smegmatis, and Staphylococcus aureus, was evaluated in relation to surface roughness. Because of their nanoscopically corrugated nature, the wrinkled GO films exhibited excellent antibacterial properties. On the basis of our detailed observations, we propose a novel concept of the surrounded contact-based mechanism for antimicrobial activity of wrinkled GO films. It postulates formation of a mechanically robust GO surface "trap" that prompts interaction of bacteria with the diameter-matched GO sink, which results in substantial damages to the bacterial cell membrane. We believe that our approach uncovered a novel use of a promising two-dimensional material for highly effective antibacterial treatment.