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The crystal structures of SdgB and SdgA from Staphylococcus aureus provide functional and structural insights into the glycosylation mechanism in staphylococcal adhesion., The initiation of infection of host tissues by Staphylococcus aureus requires a family of staphylococcal adhesive proteins containing serine–aspartate repeat (SDR) domains, such as ClfA. The O-linked glycosylation of the long-chain SDR domain mediated by SdgB and SdgA is a key virulence factor that protects the adhesive SDR proteins against host proteolytic attack in order to promote successful tissue colonization, and has also been implicated in staphylococcal agglutination, which leads to sepsis and an immunodominant epitope for a strong antibody response. Despite the biological significance of these two glycosyltransferases involved in pathogenicity and avoidance of the host innate immune response, their structures and the molecular basis of their activity have not been investigated. This study reports the crystal structures of SdgB and SdgA from S. aureus as well as multiple structures of SdgB in complex with its substrates (for example UDP, N-acetylglucosamine or SDR peptides), products (glycosylated SDR peptides) or phosphate ions. Together with biophysical and biochemical analyses, this structural work uncovered the novel mechanism by which SdgB and SdgA carry out the glycosyl-transfer process to the long SDR region in SDR proteins. SdgB undergoes dynamic changes in its structure such as a transition from an open to a closed conformation upon ligand binding and takes diverse forms, both as a homodimer and as a heterodimer with SdgA. Overall, these findings not only elucidate the putative role of the three domains of SdgB in recognizing donor and acceptor substrates, but also provide new mechanistic insights into glycosylation of the SDR domain, which can serve as a starting point for the development of antibacterial drugs against staphylococcal infections.

Toxin-antitoxin (TA) systems are ubiquitously found in bacteria and are related to cell maintenance and survival under environmental stresses such as heat shock, nutrient starvation, and antibiotic treatment. Here, we report for the first time the crystal structure of the Staphylococcus aureus TA complex YoeBSa1-YefMSa1 at a resolution of 1.7 A. This structure reveals a heterotetramer with a 2:2 stoichiometry between YoeBSa1 and YefMSa1. The N-terminal regions of the YefMSa1 antitoxin form a homodimer characteristic of a hydrophobic core, and the C-terminal extended region of each YefMSa1 protomer makes contact with each YoeBSa1 monomer. The binding stoichiometry of YoeBSa1 and YefMSa1 is different from that of YoeB and YefM of E. coli (YoeBEc and YefMEc), which is the only structural homologue among YoeB-YefM families; however, the structures of individual YoeBSa1 and YefMSa1 subunits in the complex are highly similar to the corresponding structures in E. coli. In addition, docking simulation with a minimal RNA substrate provides structural insight into the guanosine specificity of YoeBSa1 for cleavage in the active site, which is distinct from the specificity of YoeBEc for adenosine rather than guanosine. Given the previous finding that YoeBSa1 exhibits fatal toxicity without inducing persister cells, the structure of the YoeBSa1-YefMSa1 complex will contribute to the design of a new category of anti-staphylococcal agents that disrupt the YoeBSa1-YefMSa1 complex and increase YoeBSa1 toxicity.

The crystal structure of SAV0491, a TatD-related DNase from the Gram-positive bacterium Staphylococcus aureus, was determined at 1.85 Å resolution, providing functional and structural insights into a putative DNA-binding mode of SAV0491., TatD has been thoroughly investigated as a DNA-repair enzyme and an apoptotic nuclease, and still-unknown TatD-related DNases are considered to play crucial cellular roles. However, studies of TatD from Gram-positive bacteria have been hindered by an absence of atomic detail and the resulting inability to determine function from structure. In this study, an X-ray crystal structure of SAV0491, which is the TatD enzyme from the Gram-positive bacterium Staphylococcus aureus (SaTatD), is reported at a high resolution of 1.85 Å with a detailed atomic description. Although SaTatD has the common TIM-barrel fold shared by most TatD-related homologs, and PDB entry 2gzx shares 100% sequence identity with SAV0491, the crystal structure of SaTatD revealed a unique binding mode of two phosphates interacting with two Ni2+ ions. Through a functional study, it was verified that SaTatD has Mg2+-dependent nuclease activity as a DNase and an RNase. In addition, structural comparison with TatD homologs and the identification of key residues contributing to the binding mode of Ni2+ ions and phosphates allowed mutational studies to be performed that revealed the catalytic mechanism of SaTatD. Among the key residues composing the active site, the acidic residues Glu92 and Glu202 had a critical impact on catalysis by SaTatD. Furthermore, based on the binding mode of the two phosphates and structural insights, a putative DNA-binding mode of SaTatD was proposed using in silico docking. Overall, these findings may serve as a good basis for understanding the relationship between the structure and function of TatD proteins from Gram-positive bacteria and may provide critical insights into the DNA-binding mode of SaTatD.

This work offers a simple fabrication of porous boron-nitride-(BN)/polyimide-(PI) composite films with high thermal diffusivities and low dielectric constants by combining high-internal-phase Pickering emulsification (HIPPE) and subsequent hot-pressing. BN nanoparticles in composite foams were well dispersed and three-dimensionally connected following the surface of the PI skeleton used as the polymer matrix. The BN contents in the BN/PI composite foams were adjusted in the range of 20–80 wt%. The porosities of the composite films were controlled according to the hot-pressing conditions such as the temperature. The porous BN/PI composite films exhibited high thermal diffusivities of 0.059–1.033 mm2/s and low dielectric constants of 2.08–3.48 at 1 GHz for BN contents of 20–80 wt%. In particular, the BN/PI composite films had extremely low dielectric loss values, close to zero (

American oyster defensin (AOD) was previously purified from acidified gill extract of the American oyster, Crassostrea virginica. AOD is composed of 38 amino acids with three disulfide bonds and exhibits strong antimicrobial activity against Gram-positive bacteria as well as significant activity against Gram-negative bacteria. Here, to develop promising peptides into antibiotic candidates, we designed five arginine-rich analogs (A0, A1, A2, A3, and A4), predicted their loop and extended strand/random structures—including nine amino acids and a disulfide bond derived from the C-terminus of AOD—and described their antimicrobial and cytotoxic effects, as well as their modes of action. In our experimental results, the A3 and A4 analogs exhibited potent antimicrobial activity against all test organisms—including four Gram-positive bacteria, six Gram-negative bacteria, and Candida albicans—without cell toxicity. A sequence of experiments, including a membrane permeabilization assay, DNA binding study, and DNA polymerization inhibition test, indicated that the two analogs (A3 and A4) possibly&nbsp, did not act directly on the bacterial membrane but instead interacted with intracellular components such as DNA or DNA amplification reactions. AOD analogs also showed strong bacterial inhibition activity in the plasma environment. In addition, analog-treated microbial cells clearly exhibited membrane disruption, damage, and leakage of cytoplasmic contents. Collectively, our results suggest that two analogs, A3 and A4, have potent antimicrobial activity via DNA interaction and have the potential for development into novel antimicrobial agents.

The synthesis and characterization of poly(phenylene polysulfide) networks (PSNs) with controlled average sulfur ranks, from elemental sulfur (ES) and p-diiodobenzene (DIB), are investigated. The P...

Thermadapt shape memory polymers (SMPs), utilizing a variety of dynamic covalent bond exchange mechanisms, have been extensively studied in recent years but it is still challenging to address several constraints in terms of limited accuracy and complexity for constructing 3D shape memory structures. Here, an effective and facile preparation of thermadapt SMPs based on elemental sulfur-derived poly(phenylene polysulfide) networks (PSNs) is presented. These SMPs possess intrinsic near-infrared (NIR)-induced photothermal conversion properties for spatiotemporal control of their plasticity and elasticity. The NIR-controllable plasticity and elasticity of the PSNs enable versatile shape manipulation of 3D multi-shape memory structures, including building block assembly, reconfiguration, shape fixing/recovery, and repair.

The high energy cost to recover heavier alcohols, such as n-butanol, from dilute aqueous solution is a significant practical barrier to their large-scale bioproduction. Membrane pervaporation offers an energy-efficient alternative, provided membrane materials can be developed which provide both good alcohol selectivity and high flux. Previous work has revealed that vinyl addition polynorbornenes bearing substituents—especially hydroxyhexafluoroisopropyl—with an affinity for n-butanol have potential in this application, as their high glass transition temperature allows the formation of thin but mechanically robust selective layers in thin-film composite (TFC) membranes. In the present work, we synthesize both microphase-separated gradient copolymers, and homogeneous random copolymers, of hydroxyhexafluoroisopropylnorbornene (HFANB) with norbornylnorbornene (NBANB) and evaluate their n-butanol/water pervaporation performance. Compared with analogous copolymers of HFANB and n-butylnorbornene (BuNB), the grea...

Two species of brown seaweeds, Saccharina japonica and Undaria pinnatifida were fermented by the red molds; Monascus purpureus and Monascus kaoliang to increase their bio-functional properties. The phenolic contents of S. japonica fermented by M. purpureus (SjMp) and M. kaoliang (SjMk) were the highest 71.53 ± 2.25 and 66.50 ± 4.64 mg gallic acid equivalent/g extract, respectively, whereas the highest flavonoid content was evident in S. japonica fermented by M. purpureus (SjMp) and U. pinnatifida fermented by M. purpureus (UpMp) (27.93 ± 0.28 and 26.88 ± 1.24 mg quercetin equivalent/g extract, respectively). Reducing sugar, protein and essential fatty acids levels also increased in fermented seaweeds. The antioxidant activities of fermented seaweed extracts exhibited significantly (p

Carboxylate-functionalized polymers of intrinsic microporosity (PIMs) are promising materials for gas separation application. However, highly carboxylate-functionalized PIMs (HCPIMs) have not been reported owing to overlooked intermediate products. Herein, we successfully prepared HCPIMs (∼92 mol % of carboxylic acid group) through a prolonged alkaline hydrolysis process (360 h). HCPIMs were found to be soluble in various organic solvents, such as tetrahydrofuran and dimethyl sulfoxide, and then free-standing HCPIM membranes could be prepared by the common solution casting method. The HCPIM membranes were found to have smaller interchain distances and higher CO2 affinity than original PIM-1 films. For example, small gas molecules, such as carbon dioxide, were effectively separated due to the enhanced diffusivity selectivity combined with the smaller cavity size. Further, strong interactions between carbon dioxide and the carboxylic acid groups increased solubility selectivity. These synergetic effects end...

In this work, we investigated the effects of the flow modifier addition on the rheological behavior and mechanical properties of high-filled polyamide 66 composites prepared from melt compounding. The flow modifiers were prepared from various amine monomers and fatty acids, and their structures were analyzed by Fourier transform infrared spectroscopy. The synthesized flow modifiers were added simultaneously during melt compounding. The presence of flow modifiers significantly reduced torque in neat polyamide 66 polymer and glass fiber-reinforced polyamide 66 composites, respectively, while the torque during compounding in composites with glass fiber contents of 50 wt% has decreased by approximately 12% after the addition of 1 phr of hexamethylene bis -stearamide indicating the simultaneous enhancement in flowability. The presence of the synthesized flow modifiers in matrix polymers improves flowability of the composites during injection molding without compromising the mechanical properties.

The multifunctional properties of 2D boron nitride nanoflakes (BNNFs) in gel polymer electrolytes (GPEs) are presented. A small addition (0.5 wt%) of BNNFs into the GPE substantially improves all the advantageous properties of the GPE including ionic conductivity, Li+ transference number, mechanical modulus, and dendrite-suppressing capability, thereby enabling high performance lithium metal batteries.

In this study, graphite nanoplatelets (GNPs), known as a thermally conductive and anisotropic carbon material, was used with polyvinyl alcohol (PVA) as matrix, which is a hydrophilic and biodegradable polymer. In order to expect enhanced thermal conductivity, silver nanoparticle-decorated graphite nanoplatelets (Ag-GNPs) were fabricated by adding silver acetate as a precursor using ‘mix-and-heat’ method. Polyvinyl alcohol composite films containing pristine GNPs and Ag-GNPs were prepared using solution casting method. The prepared composite films were uniaxially stretched to induce the filler alignment along the stretching direction as well as the strain-induced crystallization in polymer chains. The effects of the particle size of GNPs, the silver nanoparticle on the surface of GNPs, and the stretching ratios on the thermal conductivity of the composite films were investigated.

Graphene oxides coated by tannic acid (GOT) can be obtained easily by the self-polymerization of tannic acid in basic buffer solution on a graphene oxide surface. Polyamide reverse osmosis nanocomposite membranes containing GOT in the active layer were prepared by the interfacial polymerization using an organic solution containing trimesoyl chloride and an aqueous solution containing m -phenylene diamine and GOT. The polyamide membrane containing GOT (PA-GOT) showed significantly improved performances such as water flux, chlorine resistance, and antimicrobial properties, compared to the polyamide membrane without any additives and the polyamide membranes containing only tannic acid and/or graphene oxide. These high performances of PA-GOT membrane could be ascribed to a various of advantageous properties of GOT such as improved hydrophilicity, oxidative stress capability, barrier property, and compatibility with the polymer matrix.

Seaweeds have valuable pharmacological properties attributed to the presence of various bioactive compounds. In this study, the phytochemical composition and antioxidant activity of various crude extracts of Hypnea musciformis were determined. Phytochemical screening, Fourier transform infrared (FT-IR) and Gas chromatography-mass spectrometry (GC-MS) analysis were performed to identify the chemical composition of the crude extracts. Antioxidant activity was assayed by total antioxidant capacity for phosphomolybdenum, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and reducing power (RP) assays. The various extracts contained terpenoid, saponin, phlobatannin, cardiac glycosides, phenolics and flavonoids at varying concentrations. FT-IR results confirmed the presence of phenols, carboxylic acid, ketones, ethers, aromatics, amides and sulfonates. GC-MS of organic extracts showed that the extracts contain numerous high and low molecular weight compounds. Methanol extract showed the highest phenolic content and antioxidant activity measured by different assays such as phosphomolybdenum (8.2 mg ascorbic acid equivalent), DPPH (79.34%), ABTS (80.21%) and RP (2.36 absorbance at 700 nm) followed by butanol, chloroform and ethyl acetate. Furthermore, methanol and butanol extracts inhibited radical-induced DNA damage. Practical Applications Hypnea musciformis is widely known source for carrageenan but phytochemical composition and functional activities of this seaweed have not been well studied. Extraction of functional compound depends on solvent and method employed. Results found that the extract showed the presence of diversified phytochemical composition with its potent antioxidant activity at varying degrees. Our results can be used in the future to identify, isolate and characterize the specific compounds responsible for antioxidant activity.

Controlling the anisotropy of two-dimensional materials with orientation-dependent heat transfer characteristics is a possible solution to resolve severe thermal issues in future electronic devices. We demonstrate a dramatic enhancement in the in-plane thermal conductivity of stretchable poly(vinyl alcohol) (PVA) nanohybrid films containing small amounts (below 10 wt %) of hexagonal boron nitride ( h-BN) nanoplatelets. The h-BN nanoplatelets were homogeneously dispersed in the PVA polymer solution by ultrasonication without additional surface modification. The mixture was used to prepare thermally conductive nanocomposite films. The in-plane thermal conductivity of the resulting PVA/ h-BN nanocomposite films increased to 6.4 W/mK when the strain was increased from 0 to 100% in the horizontal direction. More specifically, the thermal conductivity of a PVA/ h-BN composite film with 10 wt % filler loading can be improved by up to 32 times as compared to pristine PVA. This outstanding thermal conductivity value is significantly larger than that of materials currently used in in-plane thermal management systems. This result is attributed to the anisotropic alignment of h-BN particles in the PVA chain matrix during stretching, enhancing phonon conductive paths and hence improving the thermal conductivity and thermal properties of PVA/ h-BN nanocomposite films. These polymer nanocomposites have low cost as the amount of expensive conductive fillers is reduced and can be potentially used as high-performance materials for thermal management systems such as heat sink and thermal interface materials, for future electronic and electrical devices.

We developed a solution-processable, thin, and high-dielectric polyurea-based organic gate insulator for low-voltage operation and high performance of organic thin-film transistors (OTFTs). A 60 nm-thick polyurea thin film exhibited a high dielectric constant of 5.82 and excellent electrical insulating properties owing to strong hydrogen bonding. The hydrogen bonding of the synthesized polyurea was confirmed using infrared spectroscopy and was quantitatively evaluated by measuring the interactive force using atomic force microscopy. Moreover, the effect of hydrogen bonding of polyurea on the insulating properties was systematically investigated through the combination of various monomers and control of the thickness of the polyurea film. The dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene-based OTFTs with the polyurea gate insulator showed excellent thin-film transistor (TFT) performance with a field-effect mobility of 1.390 cm2/V·s and an on/off ratio of ∼105 at a low operation voltage below 2 V. In addit...

Oxidative stresses, such as reactive oxygen species, reactive electrophilic species, reactive nitrogen species, and reactive chlorine species, can damage cellular components, leading to cellular malfunction and death. In response to oxidative stress, bacteria have evolved redox-responsive sensors that enable them to simultaneously monitor and eradicate potential oxidative stress. Specifically, redox-sensing transcription regulators react to oxidative stress by means of modifying the thiol groups of cysteine residues, functioning as part of an efficient survival mechanism for many bacteria. In general, oxidative molecules can induce changes in the three-dimensional structures of redox sensors, which, in turn, affects the transcription of specific genes in detoxification pathways and defense mechanisms. Moreover, pathogenic bacteria utilize these redox sensors for adaptation and to evade subsequent oxidative attacks from host immune defense. For this reason, the redox sensors of pathogenic bacteria are potential antibiotic targets. Understanding the regulatory mechanisms of thiol-based redox sensors in bacteria will provide insight and knowledge into the discovery of new antibiotics.

Vinyl addition polymers of substituted norbornene (NB) monomers possess very high glass-transition temperatures, making them useful in diverse applications; however, until very recently, the lack of an applicable living polymerization chemistry has precluded the synthesis of such polymers with controlled architecture, or copolymers with controlled sequence distribution. In the present work, block and random copolymers of NB monomers bearing hydroxyhexafluoroisopropyl and n-butyl substituents (HFANB and BuNB) are synthesized via living vinyl addition polymerization, using (η3-allyl)Pd(i-Pr3P)Cl activated by [Li(OEt2)2.5]B(C6F5)4 as the initiator. Both series of polymers are cast into the selective skin layers of thin film composite (TFC) membranes, and these organophilic membranes are investigated for the concentration of n-butanol from dilute aqueous solution via pervaporation. The block copolymers show well-defined microphase-separated morphologies, both in bulk and as the selective skin layers on TFC me...

Core-shell silica particles with ion-conducting poly(ethylene glycol) and anion-trapping boron moiety in the shell layer were prepared to be used as fillers for polymer composite electrolytes based on organic/inorganic hybrid branched copolymer as polymer matrix for all-solid-state lithium-ion battery applications. The core-shell silica particles were found to improve mechanical strength and thermal stability of the polymer matrix and poly(ethylene glycol) and boron moiety in the shell layer increase compatibility between filler and polymer matrix. Furthermore, boron moiety in the shell layer increases both ionic conductivity and lithium transference number of the polymer matrix because lithium salt can be more easily dissociated by the anion-trapping boron. Interfacial compatibility with lithium metal anode is also improved because well-dispersed silica particles serve as protective layer against interfacial side reactions. As a result, all-solid-state battery performance was found to be enhanced when the copolymer having core-shell silica particles with the boron moiety was used as solid polymer electrolyte.

The vinyl addition polymerization of substituted norbornene (NB) monomers, via (t-Bu3P)PdMeCl activated by [Li(OEt2)2.5]B(C6F5)4, is investigated. NB monomers bearing alkyl, aryl, fluoroaryl, and even hexafluoroisopropanol substituents yield polymers exhibiting monomodal and narrow molecular weight distributions, with molecular weight controlled by reaction time and monomer to initiator ratio, demonstrating the living nature of these polymerizations. These polymers are soluble in common organic solvents and possess excellent thermal stability. Block copolymers are also prepared via sequential monomer addition; these are the first examples of well-defined block copolymers of substituted NB monomers enchained by vinyl addition polymerization.

The ywpF gene (SAV2097) of the Staphylococcus aureus strain Mu50 encodes the YwpF protein, which may play a role in antibiotic resistance. Here, we report the first crystal structure of the YwpF superfamily from S. aureus at 2.5-A resolution. The YwpF structure consists of two regions: an N-terminal core β-barrel domain that shows structural similarity to type VI secretion system (T6SS) proteins (e.g., Hcp1, Hcp3, and EvpC) and a C-terminal two-helix pair. Although the monomer structure of S. aureus YwpF resembles those of T6SS proteins, the dimer/tetramer model of S. aureus YwpF is distinct from the functionally important hexameric ring of T6SS proteins. We therefore suggest that the S. aureus YwpF may have a different function compared to T6SS proteins. Proteins 2015; 83:781–788. © 2015 Wiley Periodicals, Inc.

The pretilt angles of liquid crystals (LCs) could be controlled over the range, 0o to 90°, using LC/photocurable monomer (NOA65) mixture system through UV irradiation. The pretilt angles could be controlled using LC/NOA65 mixture in planar polyimide coated LC cell, by changing the mixture ratio ranging from 99.9/0.1 to 99.0/1.0 and UV irradiation time (10 and 20 min). Planar and tilted alignment was observed in LC/NOA65 mixture of 99.9/0.1 and 99.8/0.2, respectively, after UV irradiation for 20 min. Finally, homeotropic (or vertical) alignment was observed in weight ratio of over 99.7/0.3. The LC alignment behavior was well correlated with the wettability of the alignment films due to the surface morphology on the alignment layer surfaces by photopolymerization-induced phase separation. This study contributes to the latest efforts to develop new method for pretilt angle control.

A series of poly(methyl methacrylate) derivatives containing polyhedral oligomeric silsesquioxane (POSS) groups (MCP#) were synthesised via free radical polymerisation (FRP) using methacryl isobutyl POSS (MA-POSS) and methyl methacrylate as monomers to investigate liquid crystal (LC) alignment property of these polymer films. The LC cells made from the films of the polymers having 100 mol% of MA-POSS units (MCP100) showed vertical LC alignment having a pretilt angle of about 90°. The vertical LC alignment behaviour on the MCP100 film was ascribed to the very hydrophobic MCP100 surface having the surface energy value smaller than about 23 mJ/m2 generated by the nonpolar bulky POSS group. Good electro-optical characteristics, such as voltage holding ratio (VHR) and residual DC voltage (R-DC), were observed for the LC cells fabricated using MCP100 as a LC alignment layer.

Organic/inorganic hybrid semi-interpenetrating network (semi-IPN) polymer electrolytes (HIPEs) based on poly(ethylene oxide- co -ethylene carbonate) (PEOEC) have been developed for all-solid-state lithium battery applications. In comparison to those of poly(ethylene oxide) (PEO), salient features of the PEOEC are the amorphous nature and high dielectric constant, which provide enhanced ionic conductivity. The organic/inorganic hybrid network matrix in the HIPEs is composed of different contents of photo-cross-linked octa-functional POSS acrylate (OA-POSS) and ethoxylated trimethylolpropane triacrylate (ETPTA). The effect of OA-POSS on solid-state electrolyte properties of the HIPEs is investigated in terms of the dimensional stability, thermal behavior, and ionic conductivity. Due to the presence of the rigid and bulky POSS moiety, the HIPEs exhibit improvement in ionic conductivity along with enhanced dimensional stability. The high capacity and good cycle performance of lithium batteries with the HIPEs demonstrate feasibility of applying the HIPEs to solid-state electrolytes for all-solid-state lithium batteries that can operate at elevated temperatures.

Polyamide reverse osmosis (RO) membranes with carbon nanotubes (CNTs) are prepared by interfacial polymerization using trimesoyl chloride (TMC) solutions in n-hexane and aqueous solutions of m-phenylenediamine (MPD) containing functionalized CNTs. The functionalized CNTs are prepared by the reactions of pristine CNTs with acid mixture (sulfuric acid and nitric acid of 3:1 volume ratio) by varying amounts of acid, reaction temperature, and reaction time. CNTs prepared by an optimized reaction condition are found to be well-dispersed in the polyamide layer, which is confirmed from atomic force microscopy, scanning electron microscopy, and Raman spectroscopy studies. The polyamide RO membranes containing well-dispersed CNTs exhibit larger water flux values than polyamide membrane prepared without any CNTs, although the salt rejection values of these membranes are close. Furthermore, the durability and chemical resistance against NaCl solutions of the membranes containing CNTs are found to be improved compared with those of the membrane without CNTs. The high membrane performance (high water flux and salt rejection) and the improved stability of the polyamide membranes containing CNTs are ascribed to the hydrophobic nanochannels of CNTs and well-dispersed states in the polyamide layers formed through the interactions between CNTs and polyamide in the active layers.

A series of composite polymer electrolytes were prepared using an organic/inorganic hybrid branched-graft copolymer (BCP) based on poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3-(3,5,7,9,11,13,15-heptaisobutylpentacyclo-[9.5.1.13,9.15,15.17,13]octasiloxane-1-yl)propyl methacrylate (MA-POSS) as the polymer matrix and poly(ethylene glycol)-grafted graphene oxide (PGO) as the filler material, and they were applied as solid-state polymer electrolytes (SPEs) for lithium-ion battery applications. The ionic conductivity of the composite polymer electrolyte containing 0.2 wt% of PGO (2.1 × 10−4 S cm−1 at 30 °C) was found to be one order of magnitude higher than that of the BCP (1.1 × 10−5 S cm−1 at 30 °C); the pristine polymer matrix, because of the larger amount of lithium salt, can be dissociated in the composite polymer electrolyte by Lewis acid–base interactions between the PGO and lithium salt. The thermal and mechanical stabilities of the composite polymer electrolytes were also improved by introducing PGO fillers and reasonable storage modulus values were maintained even at elevated temperatures up to 150 °C. All-solid-state battery performance was evaluated with the composite polymer electrolyte containing 0.2 wt% of PGO, resulting in superior cycle performance compared to that of the BCP due to the enhanced ionic conductivity as well as additional ion-conducting paths provided by the PGO fillers.

Polymers containing a renewable cardanol moiety were prepared via radical polymerization of 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) and methyl methacrylate (MMA), where HCPM was synthesized by a reaction of cardanol with glycidyl methacrylate in the presence of a base catalyst. Incorporation of the cardanol moiety into PMMA was found to increase the thermal and mechanical stability of the brittle PMMA. When the cardanol based polymers were irradiated with UV light, the mechanical stability increased further because cross-linked networks were formed between the double bonds in the cardanol moieties. Cross-linked polymer films containing the cardanol moiety exhibited high gloss and transparency to visible light. Cardanol-containing polymers with and without the cross-linked networks and other cardanol-based polymers such as poly(cardanyl acrylate) and poly(2-acetoxy-3-cardanylpropyl methacrylate) all showed high antibacterial activity against Escherichia coli (E. coli), indicating that the disappearance of double bonds and/or the structure changes of connecting groups do not diminish the intrinsic bactericidal properties of the cardanol moieties.

A series of organic/inorganic hybrid branched (BCPs) and linear (LCPs)-graft copolymers comprising poly(ethylene glycol) methyl ether methacrylate (PEGMA), 3-(3,5,7,9,11,13,15-heptaisobutyl-pentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane-1-yl)propyl methacrylate (MA-POSS), and ethylene glycol dimethacrylate (EGDMA) were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization for application to solid polymer electrolyte (SPE) materials in high-temperature lithium-ion batteries. Dimensionally stable free-standing films were obtained when the MA-POSS contents in BCPs and LCPs are larger than 21 mol% and maintained their original shape and storage modulus even if the temperature increases up to 90 °C. The maximum ionic conductivity value of the BCP electrolyte containing 21 mol% of MA-POSS was 1.6 × 10−4 S cm−1 at 60 °C and that of the LCP electrolyte containing 21 mol% of MA-POSS was 5.6 × 10−5 S cm−1 at 60 °C, indicating that the branched-graft copolymer electrolyte has higher ionic conductivity than the linear-graft counterpart, due to the increased chain mobility, as estimated by a smaller Tg value. All-solid-state batteries prepared using the BCP electrolyte showed a reasonable cell performance at 60 °C without causing safety problems, demonstrating great potential of BCPs as SPE materials for high-temperature battery systems.

A series of composite electrolytes (CEs) consisting of organic/inorganic hybrid star-shaped polymer (SPP13), plasticizer (PEG-functionalized POSS derivatives), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were prepared to investigate the effects of the composite compositions and PEG chain length of PEs on the properties of CEs. SPP13 was prepared via ATRP from poly(ethylene glycol) methyl ether methacrylate (PEGMA) and methacryl-cyclohexyl-POSS (MA-POSS) using an octafunctional initiator, and the PEG-functionalized POSS derivatives were synthesized by the hydrosilylation reaction of octakis(dimethylsilyloxy)silsesquioxane (OHPS) and allyl-PEG. The CEs were found to be dimensionally-stable enough to separate the electrodes in batteries, but they still possessed high mobility of ion-conducting P(PEGMA) segments, as estimated by the low glass transition temperatures ( T g ). The CEs having solid-state show quite high ionic conductivity (4.5 × 10 −5 S cm −1 at 30 °C) which is about three times of magnitude larger than that of the matrix polymer (SPP13) electrolyte (1.5 × 10 −5 S cm −1 at 30 °C). The CEs were electrochemically stable up to +4.2 V without the decomposition of electrolytes. An all-solid-state lithium battery prepared from the CEs exhibited larger discharge capacity than that prepared from the SPP13 electrolyte at 60 °C.

A Gram-negative, non-spore-forming, aerobic, motile and rod-shaped or ovoid bacterial strain, designated MA1-3(T), was isolated from a sea squirt (Halocynthia roretzi) collected from the South sea in South Korea. Strain MA1-3(T) was found to grow optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain MA1-3(T) fell within the clade comprising Colwellia species, clustering coherently with the type strains of Colwellia aestuarii, Colwellia polaris and Colwellia chukchiensis, showing sequence similarity values of 97.2, 96.4 and 95.6 %, respectively. It exhibited 16S rRNA gene sequence similarity values of 93.9-96.1 % to the type strains of the other Colwellia species. Strain MA1-3(T) was found to contain Q-8 as the predominant ubiquinone and C16:1 ω7c and/or C16:1 ω6c, C16:0 and C16:1 ω9c as the major fatty acids. The DNA G+C content of strain MA1-3(T) was determined to be 39.1 mol% and its mean DNA-DNA relatedness value with the type strain of C. aestuarii was 13 ± 5.4 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that the novel strain is separated from other Colwellia species. On the basis of the data presented, strain MA1-3(T) is considered to represent a novel species of the genus Colwellia, for which the name Colwellia meonggei sp. nov. is proposed. The type strain is MA1-3(T) (=KCTC 32380(T) = CECT 8302(T)).

We identified full-length cDNAs encoding pituitary adenylyl cyclase-activating polypeptide (PACAP), PACAP-related peptide (PRP), and PACAP-specific receptor (PAC1R) from olive flounder, Paralichthys olivaceus. Two variant mRNA forms were created by alternative splicing. Comparison of genomic and cDNA sequences of the PRP-PACAP precursor revealed that skipping of exon 4 within PRP resulted in two variant transcripts: a long form encoding both PRP and PACAP and a short form encoding PACAP only. Both transcripts were constitutively observed only in the brain, whereas the short form appeared in gut tissues, such as the intestine and pyloric cecum in fish challenged with a pathogen, but not in healthy fish. Furthermore, expression of the long PRP/PACAP transcript gradually increased in the intestine of flounder challenged with bacteria, suggesting that PRP and/or PACAP may serve as a regulator(s) of the immune system, especially in the gastrointestinal tract of olive flounder. The biological functions of PACAP and PRP were investigated by exogenous treatment of flounder embryogenic cells (hirame natural embryonic cells, HINAE cells) with synthetic peptides of fPACAP-38 and/or fPRP-45. Intracellular cyclic adenosine monophosphate (cAMP) production in PAC1R-overexpressing HINAE cells was regulated by fPACAP-38 in a concentration-dependent manner, but was not regulated by fPRP-45. Results from real-time quantitative polymerase chain reaction revealed that PAC1R mRNA was specifically induced by fPACAP-38 but not by fPRP-45; PACAP significantly increased TNF-α mRNA but not growth hormone (GH) mRNA in HINAE cells; however, PRP affected GH but not TNF-α mRNA expression. These results suggest that the expression ratio of PRP and PACAP is regulated at the transcriptional level depending on the tissues and conditions, and that the unique biological roles of PRP and PACAP differ from that of mammalian PRP.

For bacteria, cysteine thiol groups in proteins are commonly used as thiol-based switches for redox sensing to activate specific detoxification pathways and restore the redox balance. Among the known thiol-based regulatory systems, the MarR/DUF24 family regulators have been reported to sense and respond to reactive electrophilic species, including diamide, quinones, and aldehydes, with high specificity. Here, we report that the prototypical regulator YodB of the MarR/DUF24 family from Bacillus subtilis uses two distinct pathways to regulate transcription in response to two reactive electrophilic species (diamide or methyl-p-benzoquinone), as revealed by X-ray crystallography, NMR spectroscopy, and biochemical experiments. Diamide induces structural changes in the YodB dimer by promoting the formation of disulfide bonds, whereas methyl-p-benzoquinone allows the YodB dimer to be dissociated from DNA, with little effect on the YodB dimer. The results indicate that B. subtilis may discriminate toxic quinones, such as methyl-p-benzoquinone, from diamide to efficiently manage multiple oxidative signals. These results also provide evidence that different thiol-reactive compounds induce dissimilar conformational changes in the regulator to trigger the separate regulation of target DNA. This specific control of YodB is dependent upon the type of thiol-reactive compound present, is linked to its direct transcriptional activity, and is important for the survival of B. subtilis. This study of B. subtilis YodB also provides a structural basis for the relationship that exists between the ligand-induced conformational changes adopted by the protein and its functional switch.

The ocean is a rich resource of flora, fauna, and food. A wild-type bacterial strain showing confluent growth on marine agar with antibacterial activity was isolated from marine water, identified using 16S rDNA sequence analysis as Pseudoalteromonas sp., and designated as strain M2. This strain was found to produce various secondary metabolites including quinolone alkaloids. Using high-resolution mass spectrometry (MS) and nuclear magnetic resonance (NMR) analysis, we identified nine secondary metabolites of 4-hydroxy-2-alkylquinoline (pseudane-III, IV, V, VI, VII, VIII, IX, X, and XI). Additionally, this strain produced two novel, closely related compounds, 2-isopentylqunoline-4-one and 2-(2,3-dimetylbutyl) qunoline-4-(1H)-one, which have not been previously reported from marine bacteria. From the metabolites produced by Pseudoalteromonas sp. M2, 2-(2,3-dimethylbutyl) quinolin-4-one, pseudane-VI, and pseudane-VII inhibited melanin synthesis in Melan-A cells by 23.0%, 28.2%, and 42.7%, respectively, wherein pseudane-VII showed the highest inhibition at 8 mu g/mL. The results of this study suggest that liquid chromatography (LC)-MS/MS-based metabolite screening effectively improves the efficiency of novel metabolite discovery. Additionally, these compounds are promising candidates for further bioactivity development.

Amphiphilic organic/inorganic hybrid star-shaped polymers (SPP) were prepared by atom transfer radical polymerization (ATRP) using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3-(3,5,7,9,11,13,15-heptacyclohexyl-pentacyclo[9.5.1.1³,⁹.1⁵,¹⁵.1⁷,¹³]-octasiloxane-1-yl)propyl methacrylate (MA-POSS) as monomers and octakis(2-bromo-2-methylpropionoxypropyldimethylsiloxy)-octasilsesquioxane (OBPS) as an initiator. Star-shaped polymers (SPM) having PEGMA and methyl methacrylate (MMA) moieties were also prepared for comparative purposes. Polysulfone (PSf) ultrafiltration membranes coated with the SPP showed higher bio- and oil-fouling resistance and flux-recovery ability than the bare PSf membrane. Moreover, the SPP-coated membranes exhibited better antifouling properties than the SPM-coated membrane when they were used for oil/water emulsion filtration. The dual effective antifouling properties of the SPP were ascribed to the simultaneous enrichment of hydrophilic PEG and hydrophobic POSS moieties on the membrane surfaces resulting in the decrease in interactions with proteins and the increase in repellence to oils.

A series of branched polymers for chemically amplified resists (CARs) were prepared through the reversible addition–fragmentation chain-transfer (RAFT) copolymerization of three monomers with lithographic functionalities and an acid-cleavable dimethacrylate monomer. The three monomers with lithographic functionalities were 2-ethyl-2-adamantyl methacrylate, α-γ-butyrolactone methacrylate, and 3-hydroxy-1-adamantyl methacrylate. The acid-cleavable monomer was 2,5-dimethyl-2,5-hexanediol dimethacrylate (DMHDMA), and 2-cyanoprop-2-yl-1-dithionaphthalate was used as a chain-transfer agent. Because DMHDMA contains two methacrylate groups, it induced the branched structures of the polymers. The degree of branching could be controlled by the molar fraction of DMHDMA in the monomer mixtures. The size and structure of the polymers obtained after hydrolysis were very close to those of linear polymers prepared by RAFT copolymerization with the same amount of reagents, only without the acid-cleavable monomer. A preliminary lithography test using an argon fluoride source demonstrated that the acid-cleavable branched polymers could be promising candidates for CAR materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Comb-like polysiloxanes with polyhedral oligomeric silsesquioxane (POSS) and oligo(ethylene oxide) groups (EO) in the side chains were prepared through the hydrosilylation reaction of poly(ethylhydrosiloxane) (PEHS) with 1-allyl-3,5,7,9,11,13,15-heptacyclopentylpentacyclo-[9.5.1.13,9.15,15.17,13] octasiloxane (allyl-CyPOSS) and allyl-functionalized oligo(ethylene glycol) monomethyl ethers. The physical and chemical properties of these polysiloxanes were studied systematically by changing the content of bulky POSS groups and hydrophilic flexible oligo(ethylene oxide) groups with different lengths. For example, the glass transition temperature of the polymer increased with increasing content of POSS side groups, whereas the melting temperature and heat of fusion of the oligo(ethylene oxide) side group decreases. Furthermore, the glass transition temperature and melting temperature increase when the length of the EO group was increased, whereas the decomposition temperature decreased.

Linear polysiloxanes having different amounts of polyhedral oligomeric silsequioxane (POSS) side groups were prepared from the hydrosilylation reaction of poly(ethylhydrosiloxane) with different amount of POSS and 1-octene using platinum(0)-divinyl tetramethyldisiloxane as a catayst. 1-Octene and platinum(0)-divinyl tetramethyldisiloxane were found to be very important for the preparation of the linear polymer without any cross-linked structures. The linear polysiloxanes with POSS side groups are soluble in various organic solvents. When the content of POSS-containing monomeric unit is larger than 10 mol%, free standing films can be prepared from a routine solution casting method, although this polysiloxane is not cross-linked.

Vibrio anguillarum is the causative agent of the fish disease vibriosis and is the most intensely studied species of Vibrio. In the present study, specific primers and a PCR assay were designed to detect V. anguillarum. The primers were designed to amplify a 429-bp internal region of the V. anguillarum amiB gene, which encodes the peptidoglycan hydrolase N-acetylmuramoyl-L-alanine amidase. PCR specificity was demonstrated by successful amplification of DNA from V. anguillarum and by the absence of a PCR product from 25 other Vibrio strains and various enteric bacteria. The PCR produced a 429-bp amplified fragment from as little as 1 pg of V. anguillarum DNA. The limit of detection for this PCR technique was c. 20 bacterial colonies in 25 mg of infected flounder tissue. These results suggest that this PCR system is a sensitive and species-specific detection method, and is possible to use as a diagnostic tool to detect V. anguillarum.

Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10(-4) Scm(-1) at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt %) of the crosslinking agent and 2.0 wt % of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state.

A series of copolymers [PCD#s, where # is the weight percentage of dopamine methacrylamide (DMA) in polymers] containing mussel-inspired hydrophilic dopamine and plant-based hydrophobic cardanol moieties was prepared via radical polymerization using DMA and 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) as the monomers. PCD#s were used as coating materials to prevent flux decline of the membranes caused by the adhesion of biofoulants and oil-foulants. Polysulfone (PSf) ultrafiltration membranes coated with PCD#s showed higher biofouling resistance than the bare PSf membrane, and the bactericidal properties of the membranes increased upon increasing the content of HCPM units in the PCD#s. Serendipitously, the PSf membranes coated with the more or less amphiphilic PCD54 and PCD74, having the optimum amount of both hydrophilic DMA and hydrophobic HCPM moieties, showed noticeably higher oil-fouling resistance than the more hydrophilic PCD91-coated membrane, the more hydrophobic PCD0-coated membrane, and the bare PSf membrane. Therefore, multifunctional coating materials having biofouling- and oil-fouling-resistant and bactericidal properties could be prepared from the monomers containing mussel-inspired dopamine and plant-based cardanol groups.

A series of nitrogen- and sulfone-containing polymers with different molecular weights and monomer compositions were prepared via free radical polymerization to investigate the effect of polymer structure on the ArF lithographic performance in negative tone development (NTD) process. Conventional ArF photoresist polymers (Ref) were also prepared for comparison purposes. It was found that there are optimum molecular weights of the photoresist polymers to give good lithographic performance in NTD process. Photoresists with amine-containing polymers showed contact hole (CH) patterns with some defects, which could be due to the large amount of acid-quenchable amine moieties in the polymers. Lithographic performance of photoresists with sulfonate-containing polymers was close to that with Ref polymers and much better than that with sulfonamide-containing polymers.

Vibrio vulnificus is a causative agent of serious diseases in humans, resulting from the contact of wound with seawater or consumption of raw seafood. Several studies aimed at detecting V. vulnificus have targeted vvh as a representative virulence toxin gene belonging to the bacterium. In this study, we targeted the rpoS gene, a general stress regulator, to detect V. vulnificus. PCR specificity was identified by amplification of 8 V. vulnificus templates and by the loss of a PCR product with 36 non-V. vulnificus strains. The PCR assay had the 273-bp fragment and the sensitivity of 10 pg DNA from V. vulnificus. SYBR Green I-based real-time PCR assay targeting the rpoS gene showed a melting temperature of approximately 84 degrees for the V. vulnificus strains. The minimum level of detection by real-time PCR was 2 pg of purified genomic DNA, or 103 V. vulnificus cells from pure cultured broth and 103 cells in 1 g of oyster tissue homogenates. These data indicate that real-time PCR is a sensitive, species-specific, and rapid method for detecting this bacterium, using the rpoS gene in pure cultures and in infected oyster tissues.

Polyamide reverse osmosis (RO) membranes with deposited carbon nanotubes (CNTs) coated with poly(vinyl alcohol) (PVA) on the surface were prepared by interfacial polymerization followed by the deposition of oxidized CNTs and the coating of PVA on the surface. The polyamide membrane with the oxidized CNTs and PVA coating (PA–CNT–PVA membrane) showed much improved mechanical properties and durability compared with the polyamide membrane without CNTs (PA membrane). The PA–CNT–PVA membrane also exhibited much better antifouling properties than the PA membrane and the commercial RO membrane (LFC-1). The improved durability and antibiofouling performances of the PA–CNT–PVA membrane were possible when the CNTs were well-dispersed on the top of the polyamide active layers and stabilized by the thin crosslinked PVA coatings.

A series of star-shaped block (SBC) and random (SRC) copolymers containing poly(ethylene glycol) methyl ether methacrylate (PEGMA) and methyl methacrylate (MMA) moieties were prepared by atom transfer radical polymerization (ATRP), and used as membrane coating materials to investigate the effects of polymer structure and monomer content on the antifouling properties of the membranes. Polysulfone (PSf) ultrafiltration membranes coated with SBCs showed noticeably higher bio- and oil-fouling resistance than the bare PSf membrane. In addition, the SBC-coated membranes exhibited better antifouling properties than the SRC-coated membrane during both BSA solution and oil/water emulsion filtrations. The enhanced antifouling properties of the SBC-coated membrane compared to the SRC-coated one were ascribed to the larger content of denser PEG segments on the membrane surface, resulting in decreased interactions with proteins and oils.

Star-shaped polymers (SPCs) containing poly(ethylene glycol) (PEG) and renewable cardanol side groups were synthesized by atom transfer radical polymerization (ATRP). Water-soluble SPCs were turned into water-insoluble materials by self-cross-linking reaction of the unsaturated hydrocarbon chains of cardanol moieties upon UV irradiation. The SPC-coated membranes with UV curing exhibited noticeably higher bio- and oil-fouling resistance than the bare polysulfone (PSf) membrane during filtration experiments, whereas the SPC-coated membranes without UV curing showed a large flux-decline caused by fouling compared to that of the bare membrane, because SPCs were washed out during filtration. The enhanced antifouling properties of the SPC-coated membranes with UV curing were ascribed to a large quantity of PEG moieties on the surfaces stabilized by the cross-linked polymeric structure, leading to decreased interactions with proteins and oils.