Search

Natural products (NPs) especially the secondary metabolites originated from microbes exhibit great importance in biomedical, industrial and agricultural applications. However, mining biosynthetic gene clusters (BGCs) to produce novel NPs has been hindered owing that a large population of environmental microbes are unculturable. In the past decade, strategies to explore BGCs directly from (meta)genomes have been established along with the fast development of high-throughput sequencing technologies and the powerful bioinformatics data-processing tools, which greatly expedited the exploitations of novel BGCs from unculturable microbes including the extremophilic microbes. In this review, we firstly summarized the popular bioinformatics tools and databases available to mine novel BGCs from (meta)genomes based on either pure cultures or pristine environmental samples. Noticeably, approaches rooted from machine learning and deep learning with focuses on the prediction of ribosomally synthesized and post-translationally modified peptides (RiPPs) were dramatically increased in recent years. Moreover, synthetic biology techniques to express the novel BGCs in culturable native microbes or heterologous hosts were introduced. This working pipeline including the discovery and biosynthesis of novel NPs will greatly advance the exploitations of the abundant but unexplored microbial BGCs.

Geosmin and 2-methylisoborneol (2-MIB) are organic compounds known to cause earthy and musty odors in drinking water. In Korea, during the summer of 2012, a geosmin outbreak in the drinking water supply prompted further research to identify the source of the odorous materials, since these occurrences were not well understood or monitored. The purpose of this study was to investigate how important a role actinomycetes play in the production of geosmin and 2-MIB in Paldang Lake by measurement of microbial density (the number of colony-forming units), pyrosequencing of 16S rRNA genes, and determination of the prevalence of the geosmin synthase gene. Three sampling sites (P1, P2, and P3) were selected. The increase in geosmin concentration was paralleled by an increase in actinomycetes (Streptomyces spp.) and cyanobacteria (Anabaena spp.) populations. The bacterial communities in Paldang Lake were characterized by 454 pyrosequencing based on 16S rRNA gene sequences. P1 (North Han River) showed the hig...

The abundant use of chemicals to remove phosphorus in water could pose a problem to the safety of drinking water. In this study, we investigated the amount of residual aluminum and iron remaining in river. Paldang lake consists of two major tributaries (North Han River and South Han River) and one minor tributary (Gyung-an Stream). As a result of a total inspection on 45 phosphorus removal treatment plants in Paldang watershed of Han River, it was found that 39 treatment plants used aluminum-related coagulants while six treatment plants used iron salts. We investigated aluminum and iron concentrations in influent and effluent from six representative phosphorus removal treatment plants (A–F) in three tributaries and found that iron concentrations in A and C and aluminum concentrations in B and D exceeded drinking water standards. The background concentrations of aluminum and iron not affected by treatment plants nearby were 0.04–0.20 and 0.09–0.11 mg/L, respectively. In sediments, the background co...

From 1931 to 1941, when China and Japan were at undeclared war, China's propaganda was fairly well-circulated in America through her American friends who played a leading role in shaping American opinions on the Far Eastern crisis. But the United States State Department maintained a neutral stance toward the Sino–Japanese conflict until after 1939 and considered the pro-Chinese opinion not so much a national consensus for policy consideration as a partisan view propped up by propaganda groups. Thus, the State Department guarded its Asian policy from the pressure of propaganda activities and partisan opinions on the Asian conflict, whilst utilising them occasionally as tools of diplomacy toward China and Japan. This article examines the State Department's attitude toward public opinion and propaganda on the Far Eastern conflict from 1931 to 1941 to illustrate how American officials handled partisan opinions on a foreign crisis when most of the information on foreign policy was privately initiated and circu...

Highly efficient red phosphorescent OLEDs (PHOLEDs) with a simple, organic, triple‐layer structure was developed using the narrow‐bandgap fluorescent host material bis(10‐hydroxybenzo[h] quinolinato)beryllium complex (Bebq2) and the deep‐red dopant tris(1‐phenylisoquinoline)iridium (Ir(piq)3). The maximum current and power efficiency values of 12.71 cd/A and 16.02 lm/W, respectively, with an extremely low doping technology of 1%, are demonstrated herein. The results reveal a practical, cost‐saving host dopant system for the fabrication of highly efficient PHOLEDs involving the simple structure presented herein, with a reduction of expensive Ir dopants.

A series of white polymer light-emitting devices has been fabricated by using a spiropolyfluorene (SF) blue polymer with an orange Ir complex as a blend system. A SF single polymer host and mixed co-host with CBP (4,4-N,N-dicarbazolebiphenyl) or PBD (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole) are investigated to get high efficiency white OLEDs. A good color coordination of (0.34, 0.36) with a good current efficiency of 1.52 cd/A at 2% doped condition in a CBP mixed co-host system is reported.

We have developed a selective coating technology for large-area polymer light-emitting devices (PLEDs). This can be done by using the different surface energy on the anode electrode. Teflon thin film can be used to make a hydrophobic surface (low surface energy) on the hydrophilic surface (high surface energy) of ITO for patterning of polymer film. Contact angle of ITO surface and Teflon coated one were 3 and 130°, respectively. In order to demonstrate PLED by spontaneous patterning of polymer film we have fabricated PLED consist of 4 and 8 elements in series on the same substrate. The voltage of the devices required to achieve a particular brightness scales approximately with the number of elements in series.

For the realization of reliable nonvolatile phase-change memory operations, it is very important to understand the long-term behaviors of memory states with different resistance values. We investigated the time-dependent behaviors of RESET resistance states (RR) for the fabricated memory devices using Sn-doped GST, in which Sn amounts were varied to control the initial values of RR. It was found that the transient variations of RR showed an increasing trend with time, and that their behaviors were closely related to the microstructure of amorphous phase in the phase-change material.

We have fabricated white polymer light-emitting devices (WPLEDs) from RGB polymer blending systems using ITO/PEDOT:PSS/blended polymers/LiF/Al structure. The highest current efficiency reached 5.34 cd/A and the maximum brightness value of 27,000 cd/m2 at 11.4 V was obtained. As the green dopant concentration increased, the spectrum deviated from the white because of more energy transfer from host to guest. As a result, the 450 nm blue peak was reduced by increasing green dopant ratio. On the other hand, 600 nm red shoulder peaks were slightly increased at the same conditions. Therefore, red-orange and green electroluminescence emissions are promoted by excitation energy and charge transfer from the blue host polymer to the dopants.

We have fabricated white polymeric light-emitting devices (WPLEDs) from polyfluorene-based (PFO) blue and MEH-PPV polymer blending systems. A device structure of ITO/PEDOT:PSS/Blending polymer/Blue polymer/LiF/Al was employed. This double emissive structure results in the significant improvement of white color shift phenomenon. A current efficiency of 4.67 cd/A (3,900 cd/m2, 6.4 V) and a brightness value of 17,600 cd/m2 at 9.4 V with (0.34, 0.35) CIE coordinates at 5 V and (0.29, 0.29) at 9 V were obtained.

We synthesized a cDNA library from the intertidal copepod Tigriopus japonicus, converted it to phagemids and sequenced expressed sequence tags (ESTs). Of these, Tigriopus translationally controlled tumor protein/histamine releasing factor (TCTP/HRF) was further characterized. The Tigriopus TCTP/HRF gene encoded 172 amino acid residues and showed high similarity to Drosophila but moderate similarity to other annelids (e.g. Brugia, Wuchereria and C. elegans). The Tigriopus TCTP/HRF gene appeared in the same clade as the annelids. Here, we describe the analysis of the Tigriopus TCTP/HRF gene.

Highly efficient red phosphorescent organic light-emitting devices (PHOLEDs) were fabricated using extremely low doping technology in a simple device configuration. They were developed by making use of the narrow-bandgap fluorescent host material bis(10-hydroxybenzo[h] quinolinato)beryllium complex (Bebq2) and red dopant tris(1-phenylisoquinoline)iridium (Ir(piq)3). Maximum current and power efficiencies of 11.60 cd/A and 13.02 lm/W, respectively, are demonstrated with an extremely low doping level of 1 wt%. These results reveal a practical way to make highly efficient PHOLEDs by reducing dopant self quenching.

We report highly efficient red phosphorescent organic light-emitting diodes with a triplet p-i-n single quantum well (QW) structure. This p-i-n single QW structure is realized using p-doped and n-doped wide band-gap hole and electron injection and transporting layers with narrow band-gap host and dopant materials. The maximum current and power efficiencies of 11.1 cd/A and 14.4 lm/W, respectively, are demonstrated by a good carrier confinement effect of QW. Very low driving voltage characteristics of 3.7 ∼ 3.9 V at 1000 cd/m2 are realized by almost no injection barrier with high conductivity configuration in our p-i-n structure.