HPr prevents FruR-mediated facilitation of RNA polymerase binding to the fru promoter in Vibrio cholerae.

Phosphorylation state-dependent interactions of the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) components with transcription factors play a key role in carbon catabolite repression (CCR) by glucose in bacteria. Glucose inhibits the PTS-dependent transport of fructose and is preferred over fructose in Vibrio cholerae, but the mechanism is unknown. We have recently shown that, contrary to Escherichia coli, the fructose-dependent transcriptional regulator FruR acts as an activator of the fru operon in V. cholerae and binding of the FruR-fructose 1-phosphate (F1P) complex to an operator facilitates RNA polymerase (RNAP) binding to the fru promoter. Here we show that, in the presence of glucose, dephosphorylated HPr, a general PTS component, binds to FruR. Whereas HPr does not affect DNA-binding affinity of FruR, regardless of the presence of F1P, it prevents the FruR-F1P complex from facilitating the binding of RNAP to the fru promoter. Structural and biochemical analyses of the FruR-HPr complex identify key residues responsible for the V. cholerae-specific FruR-HPr interaction not observed in E. coli. Finally, we reveal how the dephosphorylated HPr interacts with FruR in V. cholerae, whereas the phosphorylated HPr binds to CcpA, which is a global regulator of CCR in Bacillus subtilis and shows structural similarity to FruR.

Transient receptor potential vanilloid 4 regulates extracellular matrix composition and mediates load-induced intervertebral disc degeneration in a mouse model.

OBJECTIVE: Transient receptor potential vanilloid 4 (TRPV4) is a multi-modally activated cation channel that mediates mechanotransduction pathways by which musculoskeletal tissues respond to mechanical load and regulate tissue health. Using conditional Trpv4 knockout mice, we investigated the role of Trpv4 in regulating intervertebral disc (IVD) health and injury-induced IVD degeneration. METHODS: Col2-Cre;Trpv4fl/f (Trpv4 KO) mice were used to knockout Trpv4 in all type 2 collagen-expressing cells. Effects of gene targeting alone was assessed in lumbar spines, using vertebral bone length measurement, histological, immunohistochemistry and gene expression analyses, and mechanical testing. Disc puncture was performed on caudal IVDs of wild-type (WT) and Trpv4 KO mice at 2.5- and 6.5-months-of-age. Six weeks after puncture (4- and 8-months-of-age at sacrifice), caudal spines were assessed using histological analyses. RESULTS: While loss of Trpv4 did not significantly alter vertebral bone length and tissue histomorphology compared to age-matched WT mice, Trpv4 KO mice showed decreased proteoglycan and PRG4 staining in the annulus fibrosus compared to WT. At the gene level, Trpv4 KO mice showed significantly increased expression of Acan, Bgn, and Prg4 compared to WT. Functionally, loss of Trpv4 was associated with significantly increased neutral zone length in lumbar IVDs. Following puncture, both Trpv4 KO and WT mice showed similar signs of degeneration at the site of injury. Interestingly, loss of Trpv4 prevented mechanically-induced degeneration in IVDs adjacent to sites of injury. CONCLUSION: These studies suggest a role for Trpv4 in regulating extracellular matrix synthesis and mediating the response of IVD tissues to mechanical stress.

Exploring the exponential sensitivity of risk perception in the COVID-19 pandemic.

Individual's risk perception regarding specific hazards is a dynamic process that evolves over time. This study analyzed the relationship between the number of COVID-19 cases and the South Korean public's risk perceptions from the outset of the pandemic to the recent past. More than 70 repeated cross-sectional surveys were conducted biweekly to measure individuals' risk perception. An autoregressive integrated moving average with explanatory variable time series analysis was used to characterize the relationship between the number of COVID-19 cases and level of risk perceptions. It revealed that individuals' risk perception and the number of COVID-19 cases were not linearly related but were logarithmically correlated. This finding can be understood as a psychic numbing effect, suggesting that people's perception of risk is not linear but rather exponentially sensitive to changes. The findings also revealed a significant influence of individuals' trust in local governments on their risk perceptions, highlighting the substantial role played by local governments in direct risk management during the COVID-19 pandemic.

Vibrio cholerae FruR facilitates binding of RNA polymerase to the fru promoter in the presence of fructose 1-phosphate.

In most bacteria, efficient use of carbohydrates is primarily mediated by the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS), which concomitantly phosphorylates the substrates during import. Therefore, transcription of the PTS-encoding genes is precisely regulated by transcriptional regulators, depending on the availability of the substrate. Fructose is transported mainly through the fructose-specific PTS (PTSFru) and simultaneously converted into fructose 1-phosphate (F1P). In Gammaproteobacteria such as Escherichia coli and Pseudomonas putida, transcription of the fru operon encoding two PTSFru components, FruA and FruB, and the 1-phosphofructokinase FruK is repressed by FruR in the absence of the inducer F1P. Here, we show that, contrary to the case in other Gammaproteobacteria, FruR acts as a transcriptional activator of the fru operon and is indispensable for the growth of Vibrio cholerae on fructose. Several lines of evidence suggest that binding of the FruR-F1P complex to an operator which is located between the -35 and -10 promoter elements changes the DNA structure to facilitate RNA polymerase binding to the promoter. We discuss the mechanism by which the highly conserved FruR regulates the expression of its target operon encoding the highly conserved PTSFru and FruK in a completely opposite direction among closely related families of bacteria.

First report of Stagonosporopsis cucumeris causing internal fruit rot on Oriental melon (Cucumis melo L.) in Korea.

Oriental melon (Cucumis melo L.) is a popular Korean, Japanese, and Chinese fruit (Shin et al. 2017). In April 2022, abnormal fruit (n=20) that were collected in Sangju in Gyeongbuk Province (36°27'54.6"N, 128°10'49.7"E), Korea showed approximately 5% disease incidence with severity of 10-15%. Initial symptoms included shriveling, soaking, softening, dark discoloration, and sunken lesions. Internally, a rot extended to flesh, darkening from brown to black, and producing black mycelial masses. Two fungal strains (OM-rot-01 and OM-rot-02) were isolated and exhibited similar culture characteristics: aerial mycelium that was flat and pale grey to olivaceous on potato dextrose (PDA), malt extract (MEA), and oatmeal agar (OA) after seven days at 25°C and produced abundant buff-colored pycnidial ascomata on OA. Asci were bitunicate, clavate to cylindrical, 48.4 to 69.0 × 6.1 to 6.9 µm (n=10), and ascospores were biseriate, sparse, ellipsoidal, straight to slightly curved, hyaline, smooth, apex obtuse, 1-septate, 11.1 to 14.9 × 3.8 to 5.4 µm (n=20). Conidiomata were pycnidial, mostly solitary, irregular, pale brown to black, semi-immersed, 150 to 220 × 120 to 200 µm. Conidia were oblong or ovoid, smooth, thin-walled, hyaline, aseptate, 4.4 to 6.7 × 2.0 to 2.8 µm (n=35), with 1-3 guttules per conidium. The morphological characteristics corresponded to those of Stagonosporopsis cucumeris (Hou et al. 2020). For molecular identification, genomic DNA was extracted from strains (OM-rot-01 and OM-rot-02), and the ITS regions, partial 28S rDNA (LSU), beta-tubulin (TUB2), and RNA polymerase II second largest subunit (RPB2) genes were amplified and sequenced (White et al. 1990; Woudenberg et al. 2009; Vilgalys & Hester 1990; Liu et al. 1999). The obtained sequences revealed 99-100% homology with S. cucumeris accessions (MH858625, MH870265, MT005554, and MT018021). The sequences were deposited in GenBank with accession nos. for ITS regions (OP788058, OP788059), 28S rDNA (OP788094, OP788095), TUB2 (OP810568, OP810569), and RPB2 (OP810570, OP810571). Phylogenetic analysis combined with ITS, LSU, TUB2, and RPB2 concatenated sequences using neighbor-joining method revealed that the strains were S. cucumeris. To confirm pathogenicity, OM-rot-01 was inoculated onto ripe, asymptomatic Oriental melon fruit (n=6). After they were surface sterilized with 70% alcohol, fruit were wounded using a sterilized needle and corkborer, and 5-mm-diameter mycelial plugs were attached to the wound sites, followed by covering of the fruit with aluminum foil and maintenance in a plastic box (>90% relative humidity) at 25°C. Non-wounded fruit were inoculated and incubated in a similar manner, and fruit that were inoculated with PDA plugs served as controls (n=3). The aluminum foil was removed after three days of inoculation, and other conditions were kept constant. After six days, typical internal fruit rot symptoms were observed in both wounded and non-wounded fruit; brown to black rot extended into flesh, whereas control fruit remained asymptomatic. Fungi reisolated from lesions were morphologically identical to OM-rot-01; identity was confirmed by molecular analysis, fulfilling Koch's postulates, and the pathogenicity test was conducted three times. S. cucumeris was found as a canker on Cucumis sativus in the Netherlands (Hou et al. 2020), but has not been reported elsewhere as a pathogen on Cucumis spp. To our knowledge, this is the first report of S. cucumeris causing internal fruit rot on Oriental melon in Korea. This disease poses a threat to melon production, so accurate identification of the pathogen is a key starting point for development of sustainable management practices.

Generation of genome-edited dogs by somatic cell nuclear transfer.

BACKGROUND: Canine cloning technology based on somatic cell nuclear transfer (SCNT) combined with genome-editing tools such as CRISPR-Cas9 can be used to correct pathogenic mutations in purebred dogs or to generate animal models of disease. RESULTS: We constructed a CRISPR-Cas9 vector targeting canine DJ-1. Genome-edited canine fibroblasts were established using vector transfection and antibiotic selection. We performed canine SCNT using genome-edited fibroblasts and successfully generated two genome-edited dogs. Both genome-edited dogs had insertion-deletion mutations at the target locus, and DJ-1 expression was either downregulated or completely repressed. CONCLUSION: SCNT successfully produced genome-edited dogs by using the CRISPR-Cas9 system for the first time.

Deinococcus taeanensis sp. nov., a Radiation-Resistant Bacterium Isolated from a Coastal Dune.

A Gram-stain-negative, nonspore-forming, nonmotile, aerobic, rod-shaped, and very pale orange-colored bacterial strain, designated TS293T, was isolated from a sand sample obtained from a coastal dune after exposure to 3kGy of gamma (γ)-radiation. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the isolate was a member of the genus Deinococcus and clustered with D. deserti VCD115T. The genome of strain TS293T was 4.62 Mbp long (68.2% G + C content and 4124 predicted genes) divided into a 2.86Mb main chromosome and five plasmids. Many genes considered to be important to the γ-radiation and oxidative stress resistance of Deinococcus were conserved in TS293T, but genome features that could differentiate TS293T from D. deserti and D. radiodurans, the type species of the Deinococcus genus, were also detected. Strain TS293T showed resistance to γ-radiation with D10 values (i.e., the dose required to reduce the bacterial population by tenfold) of 3.1kGy. The predominant fatty acids of strain TS293T were summed feature 3 (C16:1 ω6c and/or C16:1 ω7c) and iso-C16:0. The major polar lipids were two unidentified phosphoglycolipids and one unidentified glycolipid. The main respiratory quinone was menaquinone-8. Based on the phylogenetic, genomic, physiological, and chemotaxonomic characteristics, strain TS293T represents a novel species, for which the name Deinococcus taeanensis sp. nov. is proposed. The type strain is TS293T (= KCTC 43191T = JCM 34027T).

Effect of Passage Number of Conditioned Medium Collected from Equine Amniotic Fluid Mesenchymal Stem Cells: Porcine Oocyte Maturation and Embryo Development.

Oocyte in vitro maturation (IVM) is the most important first step in in vitro embryo production. One prerequisite for the success of IVM in oocytes is to provide a rich culture microenvironment that meets the nutritional needs of developing oocytes. We applied different equine amniotic fluid mesenchymal stem cell conditioned medium (eAFMSC-CM) from passages 7, 18, and 27 to porcine oocytes during IVM to determine its effects on oocyte development and subsequent embryo development, specifically. The eAFMSC-CM from passage 7 (eAFMSC-CMp7) has a considerable impact on 9 genes: BAX, BCL2, SOD2, NRF2, TNFAIP6, PTGS2, HAS2, Cx37, and Cx43, which are associated with cumulus cell mediated oocyte maturation. GSH levels and distribution of mitochondrial and cortical granules were significantly increased in oocytes incubated with eAFMSC-CMp7. In addition, catalase and superoxide dismutase activities were high after IVM 44 h with eAFMSC-CMp7. After in vitro fertilization, blastocyst quality was significantly increased in the eAFMSC-CMp7 group compared to control. Lastly, the antioxidant effect of eAFMSC-CMp7 substantially regulated the expression of apoptosis, pluripotency related genes and decreased autophagy activity in blastocysts. Taken together, this study demonstrated that the eAFMSC-CMp7 enhanced the cytoplasmic maturation of oocytes and subsequent embryonic development by generating high antioxidant activity.

Voltage-Tunable Ultra-Steep Slope Atomic Switch with Selectivity over 1010.

Atomic switch-based selectors, which utilize the formation of conductive filaments by the migration of ions, are researched for cross-point array architecture due to their simple structure and high selectivity. However, the difficulty in controlling the formation of filaments causes uniformity and reliability issues. Here, a multilayer selector with Pt/Ag-doped ZnO/ZnO/Ag-doped ZnO/Pt structure by the sputtering process is presented. A multilayer structure enables control of the filament formation by preventing excessive influx of Ag ions. The multilayer selector device exhibits a high on-current density of 2 MA cm-2 , which can provide sufficient current for the operation with the memory device. Also, the device exhibits high selectivity of 1010 and a low off-current of 10-13 A. The threshold voltage of selector devices can be controlled by modulating the thickness of the ZnO layer. By connecting a multilayer selector device to a resistive switching memory, the leakage current of the memory device can be reduced. These results demonstrate that a multilayer structure can be used in a selector device to improve selectivity and reliability for use in high-density memory devices.

Hymenobacter busanensis sp. nov., radiation-resistant species isolated from soil in South Korea.

Two bacterial strains designated as MA3T and BT182 were isolated from a soil sample in South Korea. Cells of the two strains were Gram-stain-negative, non-motile, rod-shaped and formed red colonies on R2A agar at 25 °C. The 16S rRNA genes of the two strains shared a sequence similarity of 99.8%. Both strains shared the highest 16S rRNA gene similarity of 96.8% with Hymenobacter edaphi NLT, followed by Hymenobacter paludis KBP-30T (96.3%), Hymenobacter coalescens WW84T (96.3%) and Hymenobacter gummosus ANT-18T (96.3%). Growth was observed at 15-37 °C (optimum 30 °C), pH 6-8 (optimum pH 7) and in the presence up to 1% NaCl. The genome size of strains MA3T and BT182 is 4.9 Mb and 4.8 Mb, respectively. The genomic G + C content of both strains is 62.0 mol%. The main polar lipid of the strains was phosphatidylethanolamine, the only respiratory quinone detected was menaquinone-7 and the major fatty acids were anteiso-C15:0, iso-C15:0, summed feature 4 (iso-C17:1 I/anteiso-C17:1 B) and summed feature 3 (C16:1 ω6c/C16:1 ω7c), supporting the affiliation of these strains with the genus Hymenobacter. Based on the phylogenetic, genotypic, phenotypic and chemotaxonomic data, strains MA3T and BT182 represent a novel species of the genus Hymenobacter, for which the name Hymenobacter busanensis is proposed. The type strain is MA3T (= KCTC 72631T = NBRC 114193T).

Hymenobacter taeanensis sp. nov., radiation resistant bacterium isolated from coastal sand dune.

An aerobic, Gram-stain-negative, non-motile, non-spore-forming, rod-shaped, and light pink-colored bacterial strain, designated TS19T, was isolated from a sand sample obtained from a coastal sand dune after exposure to 3 kGy of gamma radiation. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the isolate was a member of the genus Hymenobacter and was most closely related to H. wooponensis WM78T (98.3% similarity). Strain TS19T and H. wooponensis showed resistance to gamma radiation with D10 values (i.e., the dose required to reduce the bacterial population by tenfold) of 7.3 kGy and 3.5 kGy, respectively. The genome of strain TS19T consists of one contig with 4,879,662 bp and has a G + C content of 56.2%. The genome contains 3,955 protein coding sequences, 44 tRNAs, and 12 rRNAs. The predominant fatty acids of strain TS19T were iso-C15:0, summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B), summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), and C16:1 ω5c. The major polar lipids were phosphatidylethanolamine, and one unidentified aminophospholipid. The main respiratory quinone was menaquinone-7. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain TS19T represents a novel species, for which the name Hymenobacter taeanensis sp. nov. is proposed. The type strain is TS19T (= KCTC 72897T = JCM 34023T).

Spirosoma profusum sp. nov., and Spirosoma validum sp. nov., radiation-resistant bacteria isolated from soil in South Korea.

Two novel Gram-negative, rod-shaped bacterial strains BT702T and BT704T were isolated from soil collected in Jeongseon (37° 22' 45″ N, 128° 39' 53″ E), Gangwon province, South Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains BT702T and BT704T belong to distinct lineage within the genus Spirosoma (family Cytophagaceae, order Cytophagales, class Cytophagia and phylum Bacteroidetes). The strain BT702T was closely related to Spirosoma flavus 15J11-2T (96.7% 16S rRNA gene similarity) and Spirosoma metallilatum TX0405T (93.3%). The strain BT704T was closely related to Spirosoma koreense 15J8-5T (94.6%), Spirosoma endophyticum DSM 26130T (93.8%) and Spirosoma humi S7-4-1T (93.8%). The genome sizes of type strains BT702T and BT704T are 8,731,341 bp and 8,221,062 bp, respectively. The major cellular fatty acids of strains BT702T and BT704T were C16:1 ω5c and summed feature 3 (C16:1 ω6c/C16:1 ω7c). The strains were found to have the same quinone system, with MK-7 as the major respiratory quinone. The major polar lipids of strain BT702T was identified to be phosphatidylethanolamine (PE), aminophospholipid (APL) and aminolipid (AL), while that of strain BT704T consisted of phosphatidylethanolamine (PE) and aminophospholipid (APL). Based on the polyphasic analysis (phylogenetic, chemotaxonomic and biochemical), strains BT702T and BT704T can be suggested as two new bacterial species within the genus Spirosoma and the proposed names are Spirosoma profusum and Spirosoma validum, respectively. The type strain of Spirosoma profusum is BT702T (= KCTC 82115T = NBRC 114859T) and type strain of Spirosoma validum is BT704T (= KCTC 82114T = NBRC 114966T).

Spirosoma taeanense sp. nov., a radiation resistant bacterium isolated from a coastal sand dune.

An aerobic, Gram-negative, non-motile, non-spore-forming, rod-shaped, and pale yellow-colored bacterial strain, designated TS118T, was isolated from a sand sample obtained from a coastal sand dune after exposure to 3 kGy of gamma radiation. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was a member of the genus Spirosoma and most closely related to Spirosoma metallicum PR1014kT (95.1% similarity). The genome of strain TS118T is constituted by one chromosome (5,691,492 bp) and one plasmid (28,440 bp) and has a G + C content of 52.7%. The genome contains 4641 protein coding sequences (CDSs), 38 tRNAs, and 11 rRNAs. The predominant fatty acids of strain TS118T were C16:1 ω5c, iso-C15:0, C16:0, summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), and iso-C17:0 3-OH. The major polar lipids were phosphatidylethanolamine, an unidentified amino lipid and an unidentified aminophospholipid. The main respiratory quinone was menaquinone-7 (MK-7). The novel strain showed resistance to gamma radiation with a D10 value (i.e., the dose required to reduce the bacterial population by tenfold) of 4.3 kGy. Based on the phylogenetic, physiological, and chemotaxonomic characteristics, strain TS118T represents a novel species, for which the name Spirosoma taeanense sp. nov. is proposed. The type strain is TS118T (=KCTC 72898T =JCM 34024T).

Optimal Treatment of 6-Dimethylaminopurine Enhances the In Vivo Development of Canine Embryos by Rapid Initiation of DNA Synthesis.

Artificial activation of oocytes is an important step for successful parthenogenesis and somatic cell nuclear transfer (SCNT). Here, we investigated the initiation of DNA synthesis and in vivo development of canine PA embryos and cloned embryos produced by treatment with 1.9 mM 6-dimethylaminopurine (6-DMAP) for different lengths of time. For experiments, oocytes for parthenogenesis and SCNT oocytes were cultured for 4 min in 10 µM calcium ionophore, and then divided into 2 groups: (1) culture for 2 h in 6-DMAP (DMAP-2h group); (2) culture for 4 h in DMAP (DMAP-4h group). DNA synthesis was clearly detected in all parthenogenetic (PA) embryos and cloned embryos incorporated BrdU 4 h after activation in DMAP-2h and DMAP-4h groups. In vivo development of canine parthenogenetic fetuses was observed after embryo transfer and the implantation rates of PA embryos in DMAP-2h were 34%, which was significantly higher than those in DMAP-4h (6.5%, p < 0.05). However, in SCNT, there was no significant difference in pregnancy rate (DMAP-2h: 41.6% vs. DMAP-4h: 33.3%) and implantation rates (DMAP-2h: 4.94% vs. DMAP-4h: 3.19%) between DMAP-2h and DMAP-4h. In conclusion, the use of DMAP-2h for canine oocyte activation may be ideal for the in vivo development of PA zygotes, but it was not more effective in in vivo development of canine reconstructed SCNT oocytes. The present study demonstrated that DMAP-2h treatment on activation of canine parthenogenesis and SCNT could effectively induce the onset of DNA synthesis during the first cell cycle.

The Inhibitory Effects of Plant Derivate Polyphenols on the Main Protease of SARS Coronavirus 2 and Their Structure-Activity Relationship.

The main protease (Mpro) is a major protease having an important role in viral replication of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus that caused the pandemic of 2020. Here, active Mpro was obtained as a 34.5 kDa protein by overexpression in E. coli BL21 (DE3). The optimal pH and temperature of Mpro were 7.5 and 37 °C, respectively. Mpro displayed a Km value of 16 µM with Dabcyl-KTSAVLQ↓SGFRKME-Edans. Black garlic extract and 49 polyphenols were studied for their inhibitory effects on purified Mpro. The IC50 values were 137 µg/mL for black garlic extract and 9-197 µM for 15 polyphenols. The mixtures of tannic acid with puerarin, daidzein, and/or myricetin enhanced the inhibitory effects on Mpro. The structure-activity relationship of these polyphenols revealed that the hydroxyl group in C3', C4', C5' in the B-ring, C3 in the C-ring, C7 in A-ring, the double bond between C2 and C3 in the C-ring, and glycosylation at C8 in the A-ring contributed to inhibitory effects of flavonoids on Mpro.

Crystal structure of the AhpD-like protein DR1765 from Deinococcus radiodurans R1.

Deinococcus radiodurans is well known for its extreme resistance to ionizing radiation (IR). Since reactive oxygen species generated by IR can damage various cellular components, D. radiodurans has developed effective antioxidant systems to cope with this oxidative stress. dr1765 from D. radiodurans is predicted to encode an alkyl hydroperoxidase-like protein (AhpD family), which is implicated in the reduction of hydrogen peroxide (H2O2) and organic hydroperoxides. In this study, we constructed a dr1765 mutant strain (Δdr1765) and examined the survival rate after H2O2 treatment. Δdr1765 showed a significant decrease in the H2O2 resistance compared to the wild-type strain. We also determined the crystal structure of DR1765 at 2.27 Å resolution. DR1765 adopted an all alpha helix protein fold representative of the AhpD-like superfamily. Structural comparisons of DR1765 with its structural homologues revealed that DR1765 possesses the Glu74-Cys86-Tyr88-Cys89-His93 signature motif, which is conserved in the proton relay system of AhpD. Complementation of Δdr1765 with dr1765 encoding C86A or C89A mutation failed to restore the survival rate to wild-type level. Taken together, these results suggest that DR1765 might function as an AhpD to protect cells from oxidative stress.

Morphological-Electrical Property Relation in Cu(In,Ga)(S,Se)2 Solar Cells: Significance of Crystal Grain Growth and Band Grading by Potassium Treatment.

Solution-processed Cu(In,Ga)(S,Se)2  (CIGS) has a great potential for the production of large-area photovoltaic devices at low cost. However, CIGS solar cells processed from solution exhibit relatively lower performance compared to vacuum-processed devices because of a lack of proper composition distribution, which is mainly instigated by the limited Se uptake during chalcogenization. In this work, a unique potassium treatment method is utilized to improve the selenium uptake judiciously, enhancing grain sizes and forming a wider bandgap minimum region. Careful engineering of the bandgap grading structure also results in an enlarged space charge region, which is favorable for electron-hole separation and efficient charge carrier collection. Besides, this device processing approach has led to a linearly increasing electron diffusion length and carrier lifetime with increasing the grain size of the CIGS film, which is a critical achievement for enhancing photocurrent yield. Overall, 15% of power conversion efficiency is achieved in solar cells processed from environmentally benign solutions. This approach offers critical insights for precise device design and processing rules for solution-processed CIGS solar cells.

Facile Synthetic Route To Prepare Ultrathin Silver Nanosheets by Reducing Silver Thiolates in Interlayer Surface of Layered Double Hydroxides.

Silver metal nanostructures have gained much interest, due to their utility in various fields, based on their unique properties at nanosize. Tremendous research efforts have been made to establish synthetic methods to manipulate their shape and size. The most challenging synthesis in silver nanostructures has been known as a plate-like shape having a few nanometers size thickness and high aspect ratio. Here, we demonstrate a novel and facile synthetic route for ultrathin (≤1 nm) silver nanosheets using silver carboxylthiolate as precursor. Such silver thiolate formed single-layered colloid in aqueous basic solution, due to the electrostatic repulsion between carboxylate groups. These single layers of silver thiolates were stabilized within the interlayer space of layered double hydroxide (LDH). When silver thiolates confined in LDHs were calcined under reductive atmosphere, the LDHs effectively suppressed the vertical growth of silver crystals.

Spirosoma aureum sp. nov., and Hymenobacter russus sp. nov., radiation-resistant bacteria in Cytophagales order isolated from soil.

A Gram-stain-negative, aerobic, nonmotile, yellow-colored strain BT328T and Gram-stain-negative, aerobic, non-motile, red-colored strain BT18T were isolated from the soil collected in Korea. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain BT328T formed a distinct lineage within the family Spirosomaceae (order Cytophagales, class Cytophagia) and was most closely related to a member of the genus Spirosoma, Spirosoma terrae 15J9-4T (95.9% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C, pH 7.0 and in the absence of NaCl. The predominant cellular fatty acids were summed feature 3 (C16:1 ω6c/C16:1 ω7c) and C16:1 ω5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain BT18T formed a distinct lineage within the family Hymenobacteraceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes) and was most closely related to members of the genus Hymenobacter, Hymenobacter knuensis 16F7C-2T (97.0% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 °C and pH 7.0 without NaCl. The major fatty acids were iso-C15:0 and anteiso-C15:0. The major menaquinone was MK-7. The major polar lipid was phosphatidylethanolamine. Biochemical, chemotaxonomic and phylogenetic analyses indicated that strains BT328T and BT18T represents a novel bacterial species within the genus Spirosoma and Hymenobacter, respectively. For which the name Spirosoma aureum and Hymenobacter russus is proposed. The type strain of S. aureum is BT328T (=KCTC 72365T = NBRC 114506T) and the type strain of H. russus is BT18T (=KCTC 62610T = NBRC 114380T).

Rhodocytophaga rosea sp. nov. and Nibribacter ruber sp. nov., two radiation-resistant bacteria isolated from soil.

Two bacterial strains, 172606-1T and BT10T, were isolated from soil, Korea. Both strains were Gram-stain-negative and rod-shaped bacteria. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 172606-1T formed a distinct lineage within the family Cytophagaceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes). Strain 172606-1T was most closely related to a member of the genus Rhodocytophaga (93.8% 16S rRNA gene sequence similarity to Rhodocytophaga aerolata 5416T-29T). The complete genome sequence of strain 172606-1T is 8,983,451 bp size. Optimal growth occurred at 25 °C and pH 7.0 without NaCl. The major cellular fatty acids were identified as iso-C15:0 and C16:1 ω5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain BT10T belongs to the genus Nibribacter and is closely related to Nibribacter koreensis GSR 3061T (96.5%), Rufibacter glacialis MDT1-10-3T (95.7%), Rufibacter sediminis H-1T (95.1%) and Rufibacter quisquiliarum CAI-18bT (94.9%). The complete genome sequence of strain BT10T is 4,374,810 bp size. The predominant (> 10%) cellular fatty acids of strain BT10T were iso-C15:0 and summed feature 4 (anteiso-C17:1 B/iso-C17:1 I) and a predominant quinone was MK-7. In addition, strain BT10T has phosphatidylethanolamine (PE) as the major polar lipid. On the basis of biochemical, chemotaxonomic and phylogenetic analyses, strain 172606-1T represents a novel bacterial species of the genus Rhodocytophaga, for which the name Rhodocytophaga rosea is proposed and strain BT10T represents a novel species of the genus Nibribacter, for which the name Nibribacter ruber is proposed. The type strains of Rhodocytophaga rosea and Nibribacter ruber are 172606-1T (= KCTC 62096T = NBRC 114410T) and BT10T (= KCTC 62607T = NBRC 114383T), respectively.