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Despite wide investigation on molecular imaging contrast agents, there are still strong unmet medical needs to enhance their signal-to background ratio, brightness, photostability, and biocompatibility with multimodal imaging capability. Here, we assessed the feasibility of fluorescent nanodiamonds (FNDs) as carbon based photostable and biocompatible materials for molecular imaging applications. Because FNDs have negatively charged nitrogen vacancy (NV) centers, they can emit bright red light. FNDs were conjugated to hyaluronate (HA) for target-specific molecular imaging. HA is a biocompatible, biodegradable, and linear polysaccharide with abundant HA receptors in the liver, enabling liver targeted molecular imaging. In vitro cell viability tests revealed the biocompatibility of HA–FND conjugates and the competitive cellular uptake test confirmed their target-specific intracellular delivery to HepG2 cells with HA receptors. In addition, in vivo fluorescence lifetime (FLT) assessment revealed the imaging capability of FNDs and HA–FND conjugates. After that, we could confirm the statistically significant liver-targeted delivery of HA–FND conjugates by in vivo imaging system (IVIS) analysis and ex vivo biodistribution tests in various organs. The renal clearance test and histological analysis corroborated the in vivo biocompatibility and safety of HA–FND conjugates. All these results demonstrated the feasibility of HA–FND conjugates for further molecular imaging applications., Fluorescent nanodiamond conjugated with hyaluronate is developed as a carbon based photostable and biocompatible material for liver-targeted molecular imaging applications.

Magnesium (Mg) and its alloys have presented a paradigm for biodegradability in the field of biomedical devices. However, biodegradation of Mg and its alloys cause the formation of hydrogen gas and...

In this paper, the effect of lead nitrate stabilizer concentration on the electroless nickel (EN) plating properties of gray cast iron was investigated in a sulfuric acid plating bath. The specific critical stabilizer concentration was found to vary the EN coating properties. At the critical stabilizer concentration or more, plating rate and the chemical composition of the EN coating were changed because the deposition of Ni and P was inhibited by excessive stabilizer concentration. The surface morphology of the EN coating was strongly influenced by the plating rate change with the stabilizer concentration and the galvanic coupling effect due to the microstructure of the substrate. The crystallinity of the EN coating tended to increase with increasing stabilizer concentration. As a result, the EN plating properties of gray cast iron were greatly affected by the stabilizer concentration in the plating bath and the microstructure of the substrate.

Anodization using an electrolyte, oxygen plasma method, chemical oxidation method and oxide coating method through CVD are generally used to generate oxide film. Among them, alloys other than pure metals are mainly used since anodization using aluminum is important for strength and workability. Even if an alloy is made of the same alloy, the film formation rate and characteristics greatly vary depending on the degree of dispersion of the additive element. In particular, anodization using an electrolyte has been studied for a long time in industrial applications and attracted attention in various fields because cost reduction, high productivity, and application to complex shapes are possible. In this study, electrochemical experiment was conducted to select the optimal surface modification current density to have excellent corrosion resistance in a marine environment using 5083-O aluminum alloy. The result of experiment showed that the current flow and the formation of a thick barrier layer affected the electrochemical characteristics according to the pore diameter; however, the corrosion current density was significantly lower when anodization was performed.

In this study, the oxidation and sulfidation characteristics of modified 9Cr 1Mo steels according to Cr-rich M23C6 distributed in grain boundaries in the N2-O2-CO2-SO2 atmosphere at 650 °C were analyzed. The oxidation kinetic was obeyed by the parabolic law. The oxide layer presented a three-layer structure consisting of hematite, magnetite, and Fe Cr spinel from the outside. In the initial oxidation stage, Cr-rich M23C6 exposed to the surface acted as nuclei of Cr-rich oxide. However, it is thought to hardly effect on the growth of the outer oxide layer. The Cr-rich M23C6 distributed in grain boundaries preferentially formed a Cr2O3 layer at the oxide/matrix interface, and internal oxidation characteristics were shown to be different depending on the presence or absence of SO2 in the atmosphere.

Corrosion characteristics of SUS 304 and SUS 316L under the marine environment were investigated by plasma ion nitriding at 450 °C with a gas ratio of 25% N₂ and 75% H₂ for 10 hours. In the anodic polarization experiment performed in natural seawater, noble pitting potential and wide passive region were exhibited in SUS 316L due to the synergistic effect of molybdenum and nitrogen even after plasma ion nitriding compared with SUS 304. In the corrosion rate obtained by an extrapolation method after plasma ion nitriding, a similar result of corrosion current density represented in SUS 304 while lower corrosion current density was analyzed in SUS 316L.

Naturally grown aluminum oxide film is about 10 nm in thickness, which is extremely thin with low commercial value, so that Al and its alloys are electrochemically treated to form a layer much thicker than the natural one. Such film received attention from academic and industrial for its high hardness and excellent corrosion resistance, which allows it to be colored in the desired shade. However, almost no investigations have been conducted to improve durability with anodizing process application on aluminum vessels so far. In this study, the optimum process time was established by applying anodizing technology to artificially form oxide film with excellent wear resistance on the material surface. The results of the experiments revealed that the quality of oxide film affected the cavitation resistance depending on the different anodizing process times. Consequently, 40 minutes of process time is determined to be the optimum, showing least amount of damage.

The simultaneous neural signal monitoring and stimulation can allow accurate neurotransmitter regulation for patients in various degrees of neural degeneration disorders. Here, we developed a residue-free graphene device as an effective electrical neural interface for dopamine sensing and secretion. We demonstrated the ultrasensitive dopamine sensing of residue-free graphene devices cultured with PC12 cells and the on-demand functional electrical stimulation for electroceutical applications. The doping effect of graphene by the released dopamine from living cells was confirmed from the electrical current change. The dopamine release could be also quantitatively analyzed by ELISA. Then, Ca2+ ion-dependent dopamine release was optically observed by fluorescence microscopy during the stimulation. Taken together, this study confirms the feasibility of graphene surface as a neural interface for electroceutical applications to various central nerve system disorders.

Small-molecule natural products have been an essential source of pharmaceuticals to treat human diseases, but very little is known about their behavior inside dynamic, live human cells. Here, we demonstrate the first structure-activity-distribution relationship (SADR) study of complex natural products, the anti-cancer antimycin-type depsipeptides, using the emerging bioorthogonal Stimulated Raman Scattering (SRS) Microscopy. Our results show that the intracellular enrichment and distribution of these compounds are driven by their potency and specific protein targets, as well as the lipophilic nature of compounds.

Small-molecule natural products have been an essential source of pharmaceuticals to treat human diseases, but very little is known about their behavior inside dynamic, living human cells. Here, we demonstrate the first structure-activity-distribution study of complex natural products, the anti-cancer antimycin-type depsipeptides, using the emerging bioorthogonal Stimulated Raman Scattering (SRS) Microscopy. Our results show that the intracellular enrichment and distribution of these compounds are driven by their potency and specific protein targets, as well as the lipophilic nature of compounds.

Plasma electrolytic oxidation (PEO) is a promising coating process to produce ceramic oxide on valve metals such as Al, Mg and Ti. The PEO coating is carried out with a dilute alkaline electrolyte solution using a similar technique to conventional anodizing. The coating process involves multiple process parameters which can influence the surface properties of the resultant coating, including power mode, electrolyte solution, substrate, and process time. In this study, ceramic oxide coatings were prepared on commercial Al alloy in electrolytes with different KOH concentrations (0.5 ~ 4 g/L) by plasma electrolytic oxidation. Microstructural and electrochemical characterization were conducted to investigate the effects of electrolyte concentration on the microstructure and electrochemical characteristics of PEO coating. It was revealed that KOH concentration exert a great influence not only on voltage-time responses during PEO process but also on surface morphology of the coating. In the voltage-time response, the dielectric breakdown voltage tended to decrease with increasing KOH concentration, possibly due to difference in solution conductivity. The surface morphology was pancake-like with lower KOH concentration, while a mixed form of reticulate and pancake structures was observed for higher KOH concentration. The KOH concentration was found to have little effect on the electrochemical characteristics of coating, although PEO treatment improved the corrosion resistance of the substrate material significantly.

Anodizing is a technology to generate thicker and high-quality films than natural oxide films by treating metals via electrochemical methods. Electrochemical manufacturing method of nano structure is an efficient technology in terms of cost reduction, high productivity and complicated shapes, which receives the spotlight in diverse areas. Especially, artificial films generated by anodizing technology possess excellent mechanical characteristics including hardness and wear resistance. It is also easy to modify thickness and adjust shape of those artificial films so that they are mainly used in sensors, filters, optical films and electrolytic condensers. In this study, experiment was performed to observe the effect of current density on porous film formation in two-step anodizing for Al alloy. Anodizing process was performed with 10 vol.% sulfuric acid electrolyte while the temperature was maintained at 10℃ using a double beaker. and 10 ~ 30 mA/㎠ was applied for 40 minutes using a galvanostatic method. As a result, both pore diameters and distances between pores tended to increase as the local temperature and electrolysis activity increased due to the increase in applied current density.

Aluminum is extremely active metal on the surface of which the oxide is instantly created when exposed to atmosphere. This naturally generated film has little industrial value as it has thickness as thin as 10 nm. Hence, oxide films are often made thick by electrochemical method. The characteristics of the films can be controlled by varying process parameters including composition, concentration, additives, solution temperature, voltage etc. These films have high hardness and excellent corrosion resistance. Therefore, they are receiving great amount of attention in both academic and industrial areas with their diverse applicability. In this paper, the optimal electrolyte concentration was investigated to produce oxide film with excellent corrosion resistance. The results reveal that Al2O3 oxide film was created on the surface for all tested electrolyte concentrations. Moreover, the films have a considerably lower corrosion current density than that of the substrate, implying excellent corrosion resistance.

In this study, Al and Zn arc thermal spray coatings were carried out onto the substrate of SS400 steel to improve corrosion resistance and durability of hull structural steel for ship in marine environment. Therefore cavitation-erosion test was conducted to evaluate the durability of painted and thermal spray coated specimens. And then the damaged surface morphology and weight loss were obtained to compare with each other, respectively. As a result, the painted specimen was the poorest cavitation resistance characteristics because surface damage behavior appeared to be exfoliated in bulk shape during the cavitation experiment. And Zn thermal spray coating layer presented the significant surface damage depth due to relatively low surface hardness and local cavitation damage tendency. On the other hand, as a result of the weight loss analysis, the painting layer presented the poorest cavitation resistance and the Al thermal spray coating layer relatively showed the best results after cavitation experiment.

Aluminum alloy is a very strong reactivity material, but it has excellent corrosion resistance due to protective oxide film created in air. However, it is not practical because the film thickness is uneven and varies depending on the generation condition. Therefore, aluminum anodizing was performed to form film with commercially applicable hardness, corrosion resistance, and wear resistance. This offers such advantages as commercial applicability to large areas and low prices. In this study, the electrochemical characteristics with concentration of sulfuric acid electrolyte were compared with the two-step anodizing method which is widely used. A surface observation revealed regular structures and pores with the size of several tens of nm, and the anodized film presented excellent corrosion resistance with considerably low corrosion current density in sea water.

In this study, aluminum titanium nitride (AlTiN) coating was deposited by arc ion plating onto mirror finish STS 304 plate. The surface and cross-section of the coating was characterized by SEM and EDX analysis. Several electrochemical corrosion experiments were performed including rest potential measurement, potentiodynamic polarization experiment and Tafel analysis. The result of the experiments indicated that the AlTiN coating presented lower corrosion current density than the substrate material (STS 304) under uniform corrosion environment. It was also observed that AlTiN coating may have a risk of being attacked by localized corrosion attack such as pitting when pores or micro/nano particles in the coating are exposed to chloride ion containing corrosion environment, especially marine environment.

Covering: up to 2016 Antimycin-type depsipeptides are a family of natural products with great structural diversity and outstanding biological activities. These compounds have typically been isolated from actinomycetes and are generated from hybrid nonribosomal peptide synthetase (NRPS)-polyketide synthase (PKS) assembly lines. This review covers the literature on the four classes of antimycin-type depsipeptides, which differ by macrolactone ring size, and it discusses the discovery, biosynthesis, chemical synthesis, and biological activities of this family of compounds.

In spite of highly advanced paint coating techniques, corrosion damage of marine metal and alloys increase more and more due to inherent micro-cracks and porosities in coatings formed during the coating process.Furthermore, flowing seawater conditions promote the breakdown of the protective oxide of the materials introducing more oxygen into marine environments, leading to the acceleration of corrosion. Various corrosion protection methods are available to prevent steel from marine corrosion. Cathodic protection is one of the useful corrosion protection methods by which the potential of the corroded metal is intentionally lowered to an immune state having the advantage of providing additional protection barriers to steel exposed to aqueous corrosion or soil corrosion, in addition to the coating. In the present investigation, the effect of flow velocity was examined for the determination of the optimum corrosion protection current density in cathodic protection as well as the corrosion rate of the steel. It is demonstrated from the result that the material corrosion under dynamic flowing conditions seems more prone to corrosion than under static conditions.

The cyclizidine biosynthetic gene cluster was identified from Streptomyces NCIB 11649, which revealed the polyketide biosynthetic machinery for cyclizidine alkaloid biosynthesis. Both in vivo mutagenesis study and in vitro biochemical analysis provided insight into the timing and mechanism of the biosynthetic enzymes that produce cyclizidine-type indolizidine alkaloids.

Plasma electrolytic oxidation (PEO) is an electrochemical-based surface modification technique that produces oxide layers on valve metals. The PEO process is performed in an electrolyte solution, which offers the possibility of particles’ incorporation into the growing oxide layer. In this study, we employed a PEO technique on a commercial Al alloy in an aqueous suspension of carbon nanotubes (CNTs) to fabricate CNT-incorporated oxide layer. The voltage–time response was recorded during the process. The surface of the resulting oxide layer was characterized by means of a scanning electron microscope (SEM), an energy-dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD). It was found from the SEM observation that the CNTs were successfully incorporated into the oxide layer. The PEO with the addition of CNTs led to a delay in time to breakdown (50[Formula: see text][Formula: see text][Formula: see text]s) and a decrease in breakdown voltage (442[Formula: see text][Formula: see text][Formula: see text]V) in the voltage–time curve. The microstructural feature was clearly distinguishable between the oxide layers produced with and without CNTs: a pancake-like structure for PEO without CNTs, and a doughnut-like structure for PEO with CNTs. However, neither the results of the structure analysis nor the elemental analysis provides a clear indication of carbon, even though the presence of CNTs in the oxide layer is evident, suggesting that further optimization of CNT concentration is required.

In this study, plasma electrolytic oxidation (PEO) was performed on the commercial aluminum 5083-O alloy using pulsed direct current (DC) power source. The coating process was carried out in KOH 2 g/L + Na2SiO3 2 g/L electrolyte with the systematic change of frequency (100–2000 Hz) and duty ratio (20–80%). The coating was characterized by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), and potentiodynamic polarization experiment. The coating layers showed different growth behavior and chemical composition by frequency and duty ratio. The PEO coating improved the corrosion resistance of Al 5083-O from a minimum of three times to a maximum of one order. In conclusion, it was found that the frequency and duty ratio had a considerable influence on the coating properties of Al 5083-O in DC power mode.

Top-seeded solution growth (TSSG) has received considerable attention as a promising growth method for obtaining high-quality silicon carbide (SiC) single crystals. However, low carbon solubility in the TSSG method prevents rapid growth of bulk SiC single crystals. In this study, we propose cobalt (Co), for the first-ever use in this method, with the aim of improving the SiC growth rate and crystal quality realized through the TSSG method with a Si0.6Cr0.4 solvent. The surface morphology of crystals grown with the Si0.6Cr0.4 solvent was characterized by significant step bunching. However, the growth surface generated by a Si0.56Cr0.4Co0.04 solvent was characterized by a smooth surface with step-flow growth, and the crystal grown with this solvent contained almost no Co. Furthermore, the growth rate in the Si0.56Cr0.4Co0.04 solvent was three times higher than that in the Si0.6Cr0.4 solvent. Based on the aforementioned results, Si0.56Cr0.4Co0.04 represents a promising solvent that can be used to enhance the growth rate and improve the quality of SiC single crystals.

In this study, the current density requirements of zinc sacrificial anode for corrosion protection of AA5083-H321 aluminum hull for the ship was determined through various electrochemical tests. Surface observation and chemical composition analysis were performed after the galvanostatic test for various current density requirements determined by the cathodic polarization experiment. As a result, the most appropriate current density requirement range was determined as 3.7 × 10−6–5.8 × 10−6 A/cm2. Excessive current density over 7.6 × 10−6 A/cm2 caused local surface damage due to the effect of Mg-rich and Fe-rich intermetallic phases. In addition, the self-consumption of zinc sacrificial anode was determined through Tafel's extrapolation method.

This study investigated the cavitation erosion resistance of electroless Ni-P (EN) coated gray cast iron (GCI) in seawater solution. Furthermore, the optimum coating design parameters were examined to minimize cavitation erosion damage through analysis of variance (ANOVA) based on the L9 orthogonal array. In this study, four coating design factors were used: concentration of source of nickel (A), concentration of reducer agent (B), deposition temperature (C), and pressure of shot peening (D). In accordance with the regulation of the modified ASTM G32, the cavitation erosion experiment was conducted for 1 hour in a seawater solution to find the optimum design parameters which can minimize the cavitation erosion damage. Besides, ANOVA was performed to verify the contribution of each coating design parameter. As a result, the concentration of reducer agent among the EN process parameters was determined as the most significant factor in the cavitation erosion behavior.

Division of Marine Engineering, Mokpo National Maritime University, Haeyangdaehak-ro 91, Mokpo-si, Jeonnam, Korea, 530-729(Received June 10, 2015; Revised June 25, 2015; Accepted June 26, 2015)The commercialization of aluminum had been delayed than other metals because of its high oxygen affinity. Anodizing is a process in which oxide film is formed on the surface of a valve metal in an electrolyte solution by anodic oxidation reaction. Aluminum has thin oxide film on surface but the oxide film is inhomogeneous having a thickness only in the range of several nanometers. Anodizing process increases the thickness of the oxide film significantly. In this study, porous type oxide film was produced on the surface of aluminum in sulfuric acid as a function of electrolyte temperature, and the optimum condition were determined for anodizing film to exhibit excellent cavitation resistance in seawater environment. The result revealed that the oxide film formed at 10 represented the highest cavitation resistance, while the oxide film formed at 15 showed the lowest resistance to cavitation in spite of its high hardness.Keywords: aluminum, anodizing, oxide film, cavitation, seawater

Aluminum acts as sacrificial anode and corrosion protection with Al₂O₃ formation. If the same current on material for Al ships with steel ships supplies, the more hydrogen would be occurred, that result is bring about over-protection. For this reason, the damage by hydrogen embrittlement leads to the serious accident. In this study, we evaluate electrochemical behavior with rotation speed of 5083-H116 Al alloy material for Al ship in seawater. To examine the electrochemical characteristics with rotation speed and its effects on performance, experiments were conducted at four rotation speed. Results of experiments, the corrosion current density and damage were increased by applying the rotation speed compared to static state.

Polyketides are an important class of bioactive small molecules valued not only for their diverse therapeutic applications, but also for their role in controlling interesting biological phenotypes in their producing organisms. While numerous examples of polyketides derived from aerobic organisms exist, only a single family of polyketides has been identified from anaerobic organisms. Here we uncover a novel family of polyketides native to the anaerobic bacteriumClostridium acetobutylicum, an organism well-known for its historical use as an industrial producer of the organic solvents acetone, butanol, and ethanol. Through mutational analysis and chemical complementation assays, we demonstrate that these polyketides influence butanol production and act as chemical triggers of sporulation and granulose accumulation in this strain. This study represents a significant addition to the body of work demonstrating the existence and importance of polyketides in anaerobes, and showcases a novel strategy of manipulating the secondary metabolism of an organism to improve traits significant for industrial applications.

Department of Electrical and Electronic Engineering, Anyang University, Anyang 430-714, Korea(Received October 8, 2013; Revised December 9, 2013; Accepted December 11, 2013)Abstract: Silicon nitride thin film deposited with Plasma Enhanced Chemical Vapor Deposition was treated by a nitrogen plasma generated by Inductively Coupled Plasma at room temperature. The treatment was investigated by Fourier Transform Infrared Spectroscopy and Atomic Force Microscopy on the surface at various RF source powers at two RF bias powers. The amount of hydrogen was reduced and the surface roughness of the films was decreased remarkably after the plasma treatment. In order to understand the causes, we analyzed the plasma diagnostics by Optical Emission Spectroscopy and Double Langmuir Probe. Based on these analysis results, we show that the nitrogen plasma treatment was effective in the improving of the properties silicon nitride thin film for flexible display.Keywords: Plasma nitridation, Silicon nitride, Thin film, Low temperature, Flexible display, ICP, PECVD, FT-IR, AFM, OES, DLP

In this study, the influences of electrolytic gas generation on the surface of aluminum as a cushioning media against cavitation bubbles were experimentally investigated. The electrolytic gas evolution was controlled by applying electric current to the metal with different polarity and current densities. The surface of the metal specimen was either polarized anodically or cathodically while simultaneously being subject to vibratory cavitation. It was revealed that the surface damage behavior was mainly dependent on the current densities applied to the metal. It was apparent that a moderate current density range of between [Formula: see text] and [Formula: see text] A/cm2 applied cathodically can produce electrolytic gas evolution to cushion the cavitation bubbles sufficiently. However, application of a too a high current density (greater than [Formula: see text] A/cm[Formula: see text] may lead to cathodic corrosion of Al alloys.

This study aims to characterize the cavitation damage behavior of aluminum alloys in seawater and thus to enhance its cavitation resistance. Potentiostatic experiments were performed under various potential conditions to determine the optimum protection potentials, at which cavitation damage was suppressed. A potential range was selected for the experiment from −2.2 to −1.4 V, which corresponded to the concentration and activation polarization regions on the cathodic polarization curve of the 5083-H116 alloy. After the experiments, the current density–time behavior was investigated, and the degree of surface damage was observed using three-dimensional microscopy and scanning electron microscopy (SEM). The optimum protection potential was determined to be in the range of −1.9 to −1.5 V under which the cavitation damage was reduced significantly.

Recently, demand for environment protection and reduction of energy consumption has led to active development of technology to reduce the weight of transportation devices. Furthermore, due to the development of the ocean leisure industry, there is a increasing number of small shipbuilding including yacht using aluminum. However, there are a lot of problems to be solved in aluminum ship welding from the technological, economic and environmental perspectives. An alternative to solve these problems is the friction stir welding technique. But, inflow frictional heat is generated in case of friction stir welding of 6061-T6 alloy, and the crystalline structure grows, resulting in weak mechanical strength. Accordingly, this study is to improve the mechanical characteristics and corrosion resistance of FSWed 6061-T6 alloy through annealing heat treatment. This study compared the characteristics with time of heat treatment at a constant temperature for the annealing heat treatment. Results of electrochemical experiments, the stir zone in annealing time 60min. showed the low corrosion current density. Micro-Vickers hardness in 60min. presents the higher value than the other conditions.

The Al alloy is environmental friendly, easy to recycle, and provides a high added value to fishing boats. Aluminum alloy do not corrode due to the formation of an anticorrosive passive film, such as Al2O3or Al2O33H2O, which resists corrosion in neutral solution. In seawater, however, Cl-ions destroy this passive film. We investigated on several electrochemical tests undertaken to determine the optimum conditions in seawater for corrosion protection of casted AC7AV aluminum alloy. The components of casted AC7AV aluminum alloy are similar with Al-Mg alloys (5xxx series) which are used for ship. Result of electochemical experiment, the optimum protection potential range with regards to hydrogen embrittlement and stress corrosion cracking was determined to lie between-1.3 and-0.7 V(vs Ag/AgCl).

We report the synthesis of a novel heat shock protein 90 (hsp90) inhibitor conjugated to a star polymer. Using reversible addition-fragmentation chain-transfer (RAFT) polymerization, we prepared star polymers comprised of PEG attached to a predesigned functional core. The stars were cross-linked using disulfide linkers, and a tagged version of our hsp90 inhibitor was conjugated to the polymer core to generate nanoparticles (14 nM). Dynamic light scattering showed that the nanoparticles were stable in cell growth media for 5 days, and HPLC analysis of compound-release at 3 different pH values showed that release was pH dependent. Cell cytotoxicity studies and confocal microscopy verify that our hsp90 inhibitor was delivered to cells using this nanoparticle delivery system. Further, delivery of our hsp90 inhibitor using star polymer induces apoptosis by a caspase 3-dependent pathway. These studies show that we can deliver our hsp90 inhibitor effectively using star polymers, and induce apoptosis by the same pathway as the parent compound.

In this study, we replaced the expensive blade material with an aluminum–bronze alloy that has excellent corrosion resistance and cavitation characteristics and developed the corrosion protection method to improve durability using an electrochemical method. The objective of this study was to identify the electrochemical corrosion protection conditions to minimize cavitation damage due to generating hydrogen gas (2H2O + 2e− → 2OH− + H2) by means of hydrogen overvoltage before the impact pressure of the cavity is transferred to the surface. In the constant potential experiment under the cavitation environment, the energy was reflected or cancelled out by collision of the cavities with the hydrogen gas generated by the hydrogen overvoltage. As a result, the optimal corrosion prevention potential in the dynamic state is assumed to be the range of −1.4 to −1.7 V, which is the range at which active polarization took place.

This investigation was to identify the electrochemical corrosion protection conditions to minimize the cavitation damage by generating hydrogen gas with the means of hydrogen overvoltage before the impact pressure of the cavity is transferred to the surface. The hybrid potentiostatic test method is designed to evaluate a complexed cavitation and electrochemical characteristic for ALBC3 alloy that is diverse and its broad applications fields in marine industry. The surface observation showed that neither the cavitation damage nor the electrochemical damage by the hydrogen gas generation occurred in the potential of -2.6 V under the cavitation environment. In the potentiostatic experiments under the cavitation environment, the cavities were reflected or cancelled out by the collision of the cavities with the hydrogen gas generated by the hydrogen overvoltage.

The optimum corrosion protection potentials were examined for 5052-O Al alloy, which is mainly used in ships. Various electrochemical experiments were carried out and the surface morphologies of specimens were observed by scanning electron microscopy (SEM) in order to determine the optimum corrosion protection potential to overcome pitting, corrosion, stress corrosion cracking (SCC), and hydrogen embrittlement in sea water. An optimum protection potential range of −1.3 V to −0.7 V was determined under the application of an impressed current cathodic protection (ICCP) system. The low current densities were shown in the range of −1.3 V to −0.7 V in the electrochemical experiments and good specimen surface morphologies were observed after potentiostatic experiment.

We report the synthesis, cytotoxicity, and phenotypic analysis of oxazole and thiazole containing fragments. Evaluating the optimal size and heterocycle for growth inhibition and apoptosis showed that activity required at least two thiazoles sequentially connected. This is the first detailed comparison of biological activity between multi-heterocyclic containing fragments.

Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A) confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved relatively straightforward. Given the ease with which the oxazole Ustat A precursor is formed via our solid phase approach, this route is amenable to rapid analog synthesis.

In general, aluminum alloys forms the passive film(, ) in neutral solution. However, the passive film created on the surface will be destroyed by chloride ions contained in sea water so the corrosion will occur. In this study, in order to solve the problem of corrosion under a seawater environment, potentiostatic protection techniques were applied to Al-4.5%Mg-0.6%Mn aluminum alloy in seawater. At polarization experiments, active state were observed at anodic polarization and concentration polarization by reduction of dissolves oxygen and activation polarization were found at anodic polarization. As a results of potentiostatic experiment, calcareous deposit were created much more as applying time increase from the turning point of the concentration polarization and activation polarization and crevice corrosion was partially observed between calcareous deposit and surface of base metal. Overall potentiostatic anodic polarization experiment was difficult to apply potentiostatic corrosion protection technology by occurrence of active state, whereas potentiostatic cathodic polarization experiment examined optimum corrosion protection condition of -1.1 V~-0.75 V within the range of concentration polarization considered various applying time.

The hull of a fast sailing aluminium ship are generally prone to erosion owing to the impact of seawater. At this time, synergistic effects of the erosion and the corrosion by aggressive ions such as chlorides tend to aggravate the damage. There have been various attempts, including selection of erosion-resistant materials, cathodic protection and addition of corrosion inhibitors, to overcome damage by erosion or corrosion under marine environments. These approaches, however, have limits on identifying the damage mechanism clearly, because they depend on analogical interpretation by correlating two damage behaviors after the individual studies are assessed. In this research, it was devised a hybrid testing apparatus that integrates electrochemical corrosion test and cavitation test, and thus the erosion-corrosion behavior by cavitation was investigated more reliably. As a result, the slightest damage was observed at the potentials between -1.6 V and -1.5 V. This is considered to be due to a reflection or counterbalancing effect caused by collision of the cavitation cavities and the hydrogen gas formed by activation polarization.

Among the environmentally friendly marine energies, tidal current power plants require low cost because they do not need to construct a large dam. Tidal power is particularly reliable energy source because the power generation capacity is predictable regardless of weather or season. Composite materials or stainless steel have been used as materials of blades for current power plant. However, their strength and welding performance generated many problems in field application. Copper alloys with excellent cavitation resistance and corrosion resistance were applied as blade materials to improve the durability of copper alloys. They were coated with WC–27NiCr and WC–10Co4Cr using the high velocity oxy-fuel (HVOF) method. The metal spray coating technology has the advantage in terms of the selection of materials for cost effectiveness and environmental effects of corrosion because the properties of the coat layer can be controlled intentionally. Coating with WC–27NiCr and WC–10Co4Cr by HVOF, WC–27NiCr shows better corrosion resistance overall. The reason for this seems to be that corrosion resistance improves and a stable passive film forms due to the effects of Ni and Cr.

We report our progress toward the synthesis of Urukthapelstatin A (Ustat A) and two analogues. Our retrosynthetic strategy involved the synthesis of three fragments: a tri-heteroaromatic moiety, a phenyl oxazole fragment, and a dipeptide. Described are the syntheses of three unique tri-heteroaromatic moieties. In addition, the corresponding linear precursors of Ustat A and two analogues are presented.

This study evaluated the effectiveness of antioxidants in animal models with damaged lungs such as inflammatory mediator-induced acute respiratory distress syndrome (ARDS) and established an ARDS therapy technique by suppressing active oxygen with membrane oxygenator. When inflammatory mediator that has an endotoxin, such as LPS, was injected directly into the airway, inflammatory pulmonary edema developed in the lung, and could induce ARDS. To treat such endotoxin-induced ARDS, the antioxidants such as taurine and dexamethasone were injected and their antioxidant effects were evaluated. They turned the blood pH to the normal condition, increased blood hemoglobin and hemocrit concentration and oxygen partial pressure (PO2), and improved survival. When a membrane oxygenator was used alone on the animal models with ARDS, similar antioxidant effects were identified. When a membrane oxygenator and antioxidants were used simultaneously, synergistic antioxidant effects were revealed. Therefore, the simultaneous use of antioxidants and membrane oxygenator is more effective than the use of either of them in treating the animal models with ARDS. This result indicates that bilateral use of antioxidants and membrane oxygenator may be useful as a potential therapy technique for the treatment of acute respiratory distress syndrome.

Aluminum alloys for ships have high mechanical strength and light, and their specific strength is higher than steel ships, enabling high speed and light weight. To lengthen the life of aluminum alloy ships, many studies are being conducted to improve durability through heat treatment and the addition of various elements, but they are still exposed to the harsh ocean environment. As the possibility of cavitation damage is getting higher because of the high speed of aluminum ships, it is critical to select aluminum alloys for ships that have excellent characteristics in ocean environment. For this purpose, cavitation experiments were conducted for the Al-Mg alloy of the 5000 series as hull materials that directly contact seawater, and their behaviors were examined and compared. The cavitation experiments revealed that the 5083-O and the 5083-H116 alloys showed the largest and the smallest weight loss, respectively. Copyright © 2012 John Wiley & Sons, Ltd.