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Singlet oxygen is a toxic chemical but powerful oxidant, exploited in many chemical and biological applications. However, the lifetime of singlet oxygen in air under atmospheric conditions is yet to be known. This has limited safe usage of singlet oxygen in air, despite being a strong antimicrobial agent with the unique property of relaxing to breathable oxygen after serving its purpose. Here, we solve this long-standing problem by combining experimental and theoretical research efforts; we generate singlet oxygen using a photosensitizer at a local source and monitor the time-dependent extent of singlet oxygen reaction with probe molecules at a detector, precisely controlling the detector distance from the source. To explain our experimental results, we employ a theoretical model that fully accounts for singlet oxygen diffusion, radiative and nonradiative relaxations, and the bimolecular reaction with probe molecules at the detector. For all cases investigated, our model, with only two adjustable parameters, provides an excellent quantitative explanation of the experiment. From this analysis, we extract the lifetime of singlet oxygen in the air to be 2.80 s at 23 °C under 1 atm, during which time singlet oxygen diffuses about 0.992 cm. The correctness of this estimation is confirmed by a simple mean-first-passage time analysis of the maximum distance singlet oxygen can reach from the source. We also confirm the sterilization effects of singlet oxygen for distances up to 0.6-0.8 cm, depending on the bacteria strain in question, between the bacteria and the singlet oxygen source.

Shin-Woo Ha,1 Jin-Kyu Lee,2 George R Beck Jr1,3,4 1Division of Endocrinology, Department of Medicine, Emory University, Atlanta, GA, USA; 2Department of Chemistry, Seoul National University, Seoul, South Korea; 3The Atlanta Department of Veterans Affairs Medical Center, Decatur, 4The Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA Abstract: To date, delivery of light-emitting diode (LED)-activated compounds to cells and tissue remains a challenge. Silica-based materials possess good biocompatibility and have advantages of control of size and shape. Fluorescent silica nanoparticles (NPs) have been synthesized and used for applications such as cell tracking and tumor identification. Here, we report the synthesis and optimization of fluorescent silica NPs, which incorporate a naphthalimide dye with triethoxysilanes that are excited by the blue LED wavelength (LEDex NPs). The NPs can be imaged in the 420–470nm wavelength, demonstrate a high quantum yield, are stable in a range of pH, and are taken into the cells. Therefore, these NPs represent a novel imaging technology for biomedical applications. Keywords: naphthalimide, imaging, bone marrow stromal cell migration, reduced toxicity&nbsp

Recently, quantum dots (QDs) have been successfully developed as efficient color converters for light-emitting diodes (LEDs) display due to excellent optical properties of QDs. Herein, we demonstrate a new approach to form metal oxide layers (or metal oxide coating) on the exterior surface of gradient alloy QDs (the most advanced chemical architecture QDs developed thus far wherein the lattice parameter from the core to shell is changing in a gradient fashion) in order to improve the photochemical stability and photoluminescence efficiency. The resulting CdO-treated QDs are incorporated into polymer matrix films to fabricate a backlight unit as a part of display panel wherein CdO-treated gradient alloy QDs are utilized as color converters upon the blue-LED excitation. The fabricated 9.7 in. iPad 2 tablet liquid crystal display panel exhibited an excellent uniformity in terms of CIE chromaticity, luminance, and bright variation and superb durability test results (maintenance of ca. 110% brightness compared to initial value even after 3 weeks of operation).

Recently, it has been clearly elucidated that nanostructured Si-based composites hybridized with protective and conductive materials can present enhanced electrochemical performance as anodes for Li-ion batteries (LIBs). One of remaining issues is to develop a sustainable and economic method to synthesize these composites on a large scale for industrial applications. Herein, we introduce a modified magnesiothermic reaction route to prepare the aforementioned Si-based composite electrodes using sea-sand derived Mg 2 Si as a reactive precursor. Owing to its reducibility and lability, Mg 2 Si can readily reduce group IVA oxides, such as Na 2 CO 3 , SiO 2 , GeO 2 , and SnO 2 , resulting in macroporous Si surrounded by the reduced forms of the counter reactants (C, Si, Ge, and Sn, respectively), some of which can be electrochemically attractive. Notably, the porous Si-based composite can be synthesized by a simple solid state reaction, so simplicity and scalability can be obtained. Also, the sea sand precursor is naturally–abundant; hence this process can be cost-effective, scalable, and sustainable. Porous Si@C composite can be synthesized from the modified magnesiothermic reaction using a sea sand-derived Mg 2 Si precursor, showing a specific capacity of 1000 mAh/g at 200th cycle. Potentially this process can be used for practical synthesis of Si-based composites.

Simultaneously, the enhancement of power factor and reduction in thermal conductivity is a critical issue to improve the thermoelectric performance of a certain material. In the present work, the rare earth oxide, Pr6O11 was added to the Bi-Sb-Te material and the corresponding thermoelectric properties have been systematically investigated. The Seebeck coefficient was slightly improved due to the increase in effective mass by addition of rare earth oxides in BiSbTe matrix. The electrical conductivity was decreased with increasing rare earth oxide content due to the decreasing mobility owing to the carrier scattering at grain boundaries. The thermal conductivity was reduced of 8% for Pr6O11/BiSbTe composites in which the 4 wt% added Pr6O11 particles, act as a scattering center for middle to higher wavelength phonons and induce the phonon scattering. As a result, the maximum thermoelectric figure of merit, ZT of 0.71 was obtained for 2 wt% added BiSbTe/Pr6O11 composites at 350 K.

We systematically investigated the effect of silver nanoparticles (Ag-NPs) on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Neat, spherical Ag-NPs at loading levels of 0.0, 0.5, 1.0, and 2.0 wt % were embedded into the titanium dioxide (TiO2) photoanode layer. The plasmonic effect of the Ag-NPs strongly enhanced the incident light absorption over a wide range of the visible wavelength region in addition to the inherent absorbance of the perovskite sensitizer. The low conduction energy level of the Ag-NPs compared to that of TiO2 provides trap sites for free charge carriers. Thus, the correlation between the enhancement of the optical absorption and the number of charge traps provided by the Ag-NPs is critical to determine the device performance, especially current density (Jsc) and PCE. This is confirmed by the quantitative comparison of the incident light absorption and the time-resolved photoluminescence decay according to the loading levels of the Ag-NPs in the TiO2 layer. The absorption enhancement from 380 to 750 nm in the UV-visible spectrum is proportional to the increase in the loading levels of the Ag-NPs. However, the Jsc increases with the device with 0.5 wt % Ag-NPs and gradually decreases with increases in the loading level above 0.5 wt % because of the different contributions to the absorbance and the charge trapping by different Ag-NP loading levels. In addition, the suppression of the surface roughness with dense packing by the Ag-NPs helps to improve the Jsc and the following PCE. Consequently, the PCE of the PSC with 0.5 wt % Ag-NPs is increased to 11.96%. These results are attributed to the balance between increased absorbance by the localized surface plasmon resonance and the decreased charge trapping as well as the decreased surface roughness of the TiO2 layer with the Ag-NPs.

The sizes of mono-dispersed titania nanoparticles (TNPs) can be precisely controlled within a diameter range of 70–650 nm by varying the concentration of water and titania precursor. The water content of the acetone solvent is varied, and ethylene glycol (EG)-stabilized titanium butoxide is used as the titania precursor. Increasing the amount of water can reduce the sizes of TNPs through the formation of a large number of small seeds in the initial reaction state. To obtain small TNPs without any aggregation, Tween 20 is used as a surfactant. Synthesis of TNPs using solvents and chelating agents other than acetone and EG, respectively, is also investigated. For example, other solvents, such as 1,4-dioxane and tetrahydrofuran, and chelating agents, such as triethylene glycol and catechol, are used for the synthesis and size control of TNPs.

Magnesiothermic reduction of various types of silica/carbon (SiO2/C) composites has been frequently used to synthesize silicon/carbon (Si/C) composites and silicon carbide (SiC) materials, which are of great interest in the research areas of lithium-ion batteries (LIBs) and nonmetal oxide ceramics, respectively. Up to now, however, it has not been comprehensively understood how totally different crystal phases of Si or SiC can result from the compositionally identical parent materials (SiO2/C) via magnesiothermic reduction. In this article, we propose a formation mechanism of Si and SiC by magnesiothermic reduction of SiO2/C; SiC is formed at the interface between SiO2 and carbon when silicon intermediates, mainly in situ-formed Mg2Si, encounter carbon through diffusion. Otherwise, Si is formed, which is supported by an ex situ reaction between Mg2Si and carbon nanosphere that results in SiC. In addition, the resultant crystalline phase ratio between Si and SiC can be controlled by manipulating the synthe...

Flower-like hierarchical iron oxide structures have attracted much research attention due to their large surface area, easy separation and re-use, and ability to adsorb toxic ions. However, harsh synthetic conditions such as the use of surfactants and autoclave reactors limit their broader application. Moreover, control over the porosity and morphology of such structures has not yet been investigated. Facile preparation of hierarchical Fe-glycolate particles is possible using pre-prepared (Fe, Ti) oxide nanoparticles without the use of surfactants or autoclave reactors as they act as both precursors and intermediate seeds for self-assembly. The porosity and morphology of the particles are controlled via variable rates of hydrolysis. Replacement of bulky glycolates with smaller water molecules induces surface area and porosity changes in the hierarchical structures. Hierarchical magnetite particles are obtained from the Fe-glycolate and hydrolyzed particles after reductive annealing, and exhibit different surface areas, porosities and magnetic properties. Porosity-controlled magnetites from hydrolyzed particles also show greater adsorption for removing toxic arsenate ions in water.

The particle size effects of TiO2 nanoparticles (TNPs), which are composed of small crystallites, on Li ion storage are a very fundamental and important subject. However, size control of TNPs under 200 nm using a sol-gel method has been limited due to the highly reactive precursor, titanium alkoxide. In this study, TNPs with various sizes even under 100 nm are obtained by controlling the reactant concentrations in a mixed solvent of ethanol and acetonitrile. Among them, three different sizes of TNPs are prepared to compare the Li ion storage capacity, and 60 nm TNPs are found to have the best reversible capacity of 182 mA h g(-1) after 50 cycles at 1 C and a remarkable rate performance of 120 mA h g(-1) at 10 C. Capacity increase upon cycling is observed in the size-controlled TNPs, and the explanation of this phenomenon is proposed to the lattice volume expansion of TiO2 upon intercalation for enabling further penetration of the electrolyte into the particles' interior. Moreover, the capacity at high rates is more closely related to the surface area from Hg porosimetry analysis than from typical N2 adsorption/desorption analysis.

Transition metal oxides have been considered as promising lithium storage materials that undergo a conversion reaction, exhibiting high specific capacity. However, capacity fading during cycling is the most serious obstacle for their commercialization. In order to overcome this, we have added PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) to Mn 2 O 3 nanowires. PEDOT:PSS was successfully coated onto Mn 2 O 3 nanowires while maintaining the structure of Mn 2 O 3 . The coating of PEDOT:PSS reduced the resistance of the surface and protected the surface electron channels from the pulverization effect of the charge–discharge operation. α-Mn 2 O 3 /PEDOT:PSS showed excellent cyclability with a reversible capacity of 1450 mAh g −1 after 200 cycles at a current density of 100 mA g −1 . An increase in capacity was observed with continuous cycling, which may be attributed to further oxidation of the manganese species and a reversible reaction of the gel-like polymer on the manganese surface. The results demonstrate that PEDOT:PSS enhances the electrochemical activity by providing electron channels and prevents pulverization caused by the charge and discharge process.

Immensely sensitive, accurate, and simple on-site colorimetric sensor has been developed for the quantitative detection of the sulfide ion in human blood plasma. The colorimetric sensor consists of lead-ion-modified silica-gel powders placed in a glass tube. The powder color changes upon reaction with sulfide ions in blood plasma. It is capable of easily detecting toxic sulfide ion by using a glass tube with an inner diameter of 3 mm. By employing the type of colorimetric sensor to a blood sample, it is possible to detect the sulfide ion with a concentration limit of 0.1 ppm and excellent reproducibility, thus making it superior to conventional analysis methods that need multiple preparation processes and various sophisticated instruments. Since the sensor reported here is insensitive to environmental conditions such as temperature or humidity, and is featured by simplicity, fast response, high sensitivity, and easily understandable results based on absolute affirmative/negative response, it is expected to be effectively used for on-site applications such as detecting poisonous ions in blood samples.

A highly sensitive on-site colorimetric forensic sensor has been developed for the quantitative detection of hydrogen sulfide and ammonia gases. The sensor consists of metal-ion-modified silica-gel powders placed in a glass tube. The powder color changes upon reaction with toxic hydrogen sulfide and ammonia gases. It is capable of easily detecting toxic gases in the concentration range between 100 ppm, which is considered as immediately dangerous to life and health, and 3000 ppm, which may cause death, by using a glass tube with an inner diameter of 3 mm. As the sensor reported here is insensitive to environmental conditions such as temperature or humidity, and is featured by simplicity, fast response, high sensitivity, and easily understandable results based on absolute affirmative/negative response, it is expected to be effectively used for on-site applications such as testing the existence of toxic gases in confined working and industrial spaces.

A transmission electron microscopy analysis was conducted on the oxide layers of Mg–5.5Al–0.25Mn (AM60) alloys with different levels of CaO content formed in a thermogravimetric analyzer (TGA) system at 450 °C for 7 h. It was found that the oxide layer in AM60 + CaO grew as a columnar structure and, resultantly, that the oxide layers had different thicknesses with different levels of CaO content. The columnar oxide grains that were formed on the Mg + CaO alloy grew on the [1 0 0] MgO , resulting in a more compact and thicker initial oxide layer compared to the normal oxide layer. The columnar growth of the oxide layer in AM60 + CaO formed due to the Ca, which dissolved from CaO.

Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C.

Nano-sized TiC ceramic powders were fabricated by very high speed planetary ball milling, especially using coarse (micron-sized) starting powders with the help of process control agents, and their refinement behavior was investigated as a function of the milling time and ball size. Fine and uniform TiC nano-particles were achieved through a short-time mechanical milling for 60 min, in which small-sized milling balls were fairly advantageous to homogeneous particle refinement by inducing low-energy, but high-frequency collisions. Moreover, a liquid-type process control agent such as toluene played a crucial role in refining the TiC nano-particles, owing to its superior capability for heat dissipation during the milling process. Under the estimated optimal milling conditions, it is notable that the particle size of the TiC powders was effectively reduced well below 50 nm, which was reliably characterized by direct transmission electron microscopy along with a complementary acoustic particle size analysis.

Hydrophobic gradient alloy quantum dots (QDs) were prepared through a facile organic route. The amphiphilic, non-ionic polymer (PVP) was absorbed onto the surface of QDs, and therefore, the PVP coated QD (QD@PVP) could be dispersible in both polar and non-polar solvents. The QD@PVP was dispersed in ethanol and tetraethyl orthosilicate (TEOS) was added with a basic catalyst in order to generate silica shell encapsulated QDs (QD@SiO2). We report a preparation method for QD@SiO2 that maintains their high luminescence and thermal- and photo-stability using dimethylamine (DMA) as a basic catalyst. White light-emitting-diodes (WLEDs) incorporating the QD@SiO2 exhibited good performance in terms of superior luminescence efficiency and high color purity.

Fluorescent nanohybrid materials, europium(III) complex intercalated Na+-smectite clay minerals (synthetic hectorite and natural montmorillonite), have been developed to visualize latent fingerprints. The guest europium(III) complex ([EuCl2(Phen)2(H2O)2]Cl·H2O) was obtained by simple complex reaction between europium chloride hexahydrate (EuCl3·6H2O) and 1,10-phenanthroline (Phen) as a 1:2 molar ratio of Eu3 + ion to ligand molecules. The intercalated nanohybrids ([Eu(Phen)2]3 +-clay minerals) were obtained through ion exchange reaction of interlayer sodium cation with europium complex ion. Guest europium(III) complex and [Eu(Phen)2]3 +-clay mineral hybrids were characterized by powder X-ray diffraction, Fourier transform infrared, thermogravimetry-differential thermal analysis (TG-DTA), elemental analysis, UV–visible and fluorescence spectroscopy. The intercalated complex maintains a characteristic red 5D0–7F2 emission at wavelength 617 nm, which is comparable to that of the free complex. The 5D0–7F2 emission intensity of [Eu(Phen)2]3 +-laponite was ca. 3.5 times higher than that of [Eu(Phen)2]3 +-montmorillonite, due to the presence of quenching impurities in natural montmorillonite itself. Fingerprint residues on glass slides were harvested by using [Eu(Phen)2]3 +-clay mineral powders, resulting in good definition for enhanced latent fingerprint detection. Particularly, [Eu(Phen)2]3 +-hectorite hybrid powder was more clearly separated from the background compared to the montmorillonite hybrid powder.

The coarsening behavior of copper nanopowders (50–150 nm in size) during mechanical milling was investigated as a function of milling atmosphere and milling time. Pure copper powders were milled under argon and air atmospheres for up to 80 h and the crystal structure, microstructure, and composition of the milled powders were investigated. It was shown that on milling the powders for 80 h under air atmosphere, the particle size was in the range of 7 to 80 μm due to sphere-to-sphere and/or sphere-to-flake welding and from the aggregation of the copper particles during milling. On the other hand, the particle size was only 7 to 35 μm, when milled under argon atmosphere even after 80 h of milling. There was no difference either in the crystal structure or lattice parameter of the copper powder after milling in the two atmospheres. The powders got contaminated with oxygen; the oxygen content increased with increasing milling time, reaching up to 4.97 wt.% when milled in air for 80 h. The oxygen got incorporated into the copper powders to form oxide layers, which were broken down during milling and thus played an important role in determining the final particle size and microstructure of the powder. A viable explanation was provided to explain the differences in the microstructure and sizes of the powder particles milled under the argon and air atmospheres.

Magnetic multi-granule nanoclusters (MGNCs) were investigated as an inexpensive means to effectivelyremove arsenic from aqueous environment, particularly groundwater sources consumed by humans. Varioussize MGNCs were examined to determin e both their capacity and efficiency for arsenic adsorption for differentinitial arsenic concentrations. The MGNCs showed highly efficient arsenic adsorption characteristics, therebymeeting the allowable safety limit of 10 g/L (ppb), prescribed by the Worl d Health Organization (WHO), andconfirming that 0.4 g and 0.6 g of MGNCs were sufficient to remove 0.5 mg/L and 1.0 mg/L of arsenate(AsO

SiO2–polyimide nanocomposites were successfully fabricated by surface modification of silica nanoparticles. In order to create structural similarity between the polymer and the SiO2 surface and to generate interfacial interaction with the polymer chain, (3-trimethoxysilylpropyl)diethylenetriamine was attached to the surface, and then, the surface amines were reacted with phthalic anhydride. The modified silica nanoparticles in polyamic acid solution were subjected to thermal imidization to obtain SiO2–polyimide (PI) nanocomposite films. Cross-sectional transmission electron microscopy results showed no significant aggregation in any of the SiO2–PI nanocomposite films having up to 20 wt% of silica nanoparticles. The effects of silica nanoparticles as a filler material on the thermal, optical, and mechanical properties of the SiO2–PI nanocomposite films were studied in comparison with those of PI by UV-vis spectrometry, thermal gravimetric analysis, thermal mechanical analysis, and nanoindentation.

The thermal decomposition of Cd(oleate)2, a metal organocarboxylate complex, in the presence of alkylamine was studied in order to understand the formation mechanism of CdSe nanocrystals (quantum dots, QDs) in the hot-injection method. The major intermediates and side products were characterized by nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the nucleophilic attack of the metal-coordinated amine toward the most electron-deficient carbonyl carbon of the oleate ligands initiated decomposition to generate a CdO cluster (or oligomer). Based on our experimental results, we proposed a two-step formation mechanism of CdSe QDs involving the formation of CdO intermediates with alkylamines playing a critical role as nucleophiles in the thermolysis process, followed by a metathesis reaction with trioctylphosphine selenide (TOPSe) as a chalcogenide source.

Background/aim Recently, a novel circulatory system, the primo vascular system (PVS), was found to be a potent metastatic route of cancer cells. The aim of the current work is to demonstrate that cancer cells injected into the testis migrate through the primo vessel (PV). Materials and methods NCI-H460 cells labeled with fluorescent nanoparticles (FNP) or green fluorescent protein (GFP) gene transfection were injected into testicular parenchyma in 24 rats. After 24 hours of injection, the abdominal cavity was investigated via a stereomicroscope, to detect the PVS, and the samples were analyzed histologically with 4′,6-diamidino-2-phenylindole (DAPI) and hematoxylin and eosin. Results Injected cancer cells were detected inside the PVS distributed on the abdominal organs. Some were detected inside intestinal parenchyma into which the attached primo vessels (PVs) entered. Conclusion The results supported the fact that the PVS may be a novel migration path of cancer cells, in addition to the lymphatic and hematogenous routes.

In order to use iron oxide nanoparticles (Fe3O4) in various applications, a surface modification that provides colloidal stability and additional functionality to the nanoparticles is necessary. For the modification of the nanoparticle surface with ligand molecules, the ligand molecule should contain an anchor group that has a strong affinity for the surface. However, currently used anchor groups have shown some problems such as low affinity and stability as well as reactivity with the surface. In this study, arsonic acid (RAsO(OH)2) was investigated as a novel anchor group. It was possible to introduce azide groups on the surface of iron oxide nanoparticles using 4-azidophenylarsonic acid, and the desired functional molecules could be chemically attached to the surface via copper-catalyzed azide-alkyne cycloaddition (click chemistry). By quantifying and comparing the amount of attached anchors on the surface, it was found that arsonic acid displays better affinity than other currently used anchors (catechol, carboxylic acid). Furthermore, we examined the binding reversibility, long-term anchoring stability, and anchoring stability at various pH values. It was revealed that arsonic acid is a stable anchor in various conditions.

E-mail: jinklee@snu.ac.krReceived May 1, 2013, Accepted May 15, 2013Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption ofthe anionic form of arsenic oxyacids, arsenite (AsO

Nanomaterials are diverse in size, shape and charge and these differences likely alter their physicochemical properties in biological systems. We have investigated how these properties alter the initial and long-term dynamics of endocytosis, cell viability, cell division, exocytosis, and interaction with a collagen extracellular matrix using silica-based fluorescent nanoparticles and the murine pre-osteoblast cell line, MC3T3-E1. Three surface modified nanoparticles were analyzed: positively charged (PTMA), negatively charged (OH), and neutrally charged polyethylene glycol (PEG). Positively charged PTMA-modified nanoparticles demonstrated the most rapid uptake, within 2 hours, while PEG modified and negatively charged OH nanoparticles demonstrated slower uptake. Cell viability was >80% irrespective of nanoparticle surface charge suggesting a general lack of toxicity. Long-term monitoring of fluorescent intensity revealed that nanoparticles were passed to daughter cells during mitotic cell division with a corresponding decrease in fluorescent intensity. These data suggest that irrespective of surface charge silica nanoparticles have the potential to internalize into osteoblasts, albeit with different kinetics. Furthermore, long lived nanoparticles have the potential to be transferred to daughter cells during mitosis and can be maintained for weeks intracellularly or within a collagen matrix without toxicity and limited exocytosis.

Legacy constrained condylar knee (LCCK) components are designed in the way that they can also be used in conjunction with a posterior-stabilized (PS) polyethylene insert, when adequate collateral stability is present. This study comprised 27 revision total knee arthroplasties (TKA) treated using an LCCK prosthesis and a PS polyethylene insert. Substantial range of motion and Knee Society score improvements were achieved in all subjects. Radiolucent lines between the block-cement were noted in 6 of 27 knees, but not significant. During TKA requiring the use of a femoral augment or stem extension, the design offering least constraint can be chosen, and an LCCK prosthesis with a PS polyethylene insert could be a satisfactory option.

(FITC) nanocomposites were prepared by the simple polyol process and Stber method. Fluorescence enhancement of fluorescein moiety (fluorescein isothiocyanate, FITC) was investigated in the presence of silver nanoparticles in (FITC) system with varying thickness (X nm) of first silica shell. Maximum enhancement factor of 4.3 fold was achieved in (FITC) structure with the first silica shell thickness of 8 nm and the average separation distance of 11 nm between the surface of silver nanoparticle and fluorescein moiety. The enhancement is believed to be originated from increased excitation rate of fluorescein moiety due to concentrated local electromagnetic field which was improved by interaction of light with silver nanoparticles.

Fluorescent silica nanoparticles (FSNPs) are synthesized through the Stober method by incorporating silane-modified organic dye molecules. The modified fluorescent organic dye molecule is able to be prepared by allylation and hydrosilylation reactions. The optical properties of as-prepared FSNPs are shown the similar optical properties of PR254A (allylated Pigment Red 254) and have outstanding photostability. The polyvinylpyrrolidone (PVP) is introduced onto the surface of FSNP to enhance the binding affinity of PVP-coated FSNP for latent fingerprints (LFPs) detection. The simple preparation and easy control of surface properties of FSNPs show potential as a fluorescent labeling material for enhanced latent fingerprint detection on hydrophilic and hydrophobic substrates in forensic science for individual identification.

The severe phenotypic effects of altered glycosylation in the congenital muscular dystrophies, including Walker-Warburg syndrome, muscle-eye-brain disease, Fukuyama congenital muscular dystrophy, and congenital muscular dystrophy 1D, are caused by mutations resulting in altered glycans linked to proteins through O-linked mannose. A glycosyltransferase that branches O-Man, N-acetylglucosaminyltransferase Vb (GnT-Vb), is highly expressed in neural tissues. To understand the expression and function of GnT-Vb, we studied its expression during neuromorphogenesis and generated GnT-Vb null mice. A paralog of GnT-Vb, N-acetylglucosaminyltransferase (GnT-V), is expressed in many tissues and brain, synthesizing N-linked, β1,6-branched glycans, but its ability to synthesize O-mannosyl-branched glycans is unknown; conversely, although GnT-Vb can synthesize N-linked glycans in vitro, its contribution to their synthesis in vivo is unknown. Our results showed that deleting both GnT-V and GnT-Vb results in the total loss of both N-linked and O-Man-linked β1,6-branched glycans. GnT-V null brains lacked N-linked, β1,6-glycans but had normal levels of O-Man β1,6-branched structures, showing that GnT-Vb could not compensate for the loss of GnT-V. By contrast, GnT-Vb null brains contained normal levels of N-linked β1,6-glycans but low levels of some O-Man β1,6-branched glycans. Therefore, GnT-V could partially compensate for GnT-Vb activity in vivo. We found no apparent change in α-dystroglycan binding of glycan-specific antibody IIH6C4 or binding to laminin in GnT-Vb null mice. These results demonstrate that GnT-V is involved in synthesizing branched O-mannosyl glycans in brain, but the function of these branched O-mannosyl structures is unresolved using mice that lack these glycosyltransferases.

Zn-containing room temperature ionic liquids (Zn-RTILs), prepared from the reactions of ZnBr 2 with 1-alkyl-3-methylimidazolium dialkyphosphates ([RMIm][R 2 PO 4 ]), were highly active for the coupling reactions of CO 2 with epoxides, producing corresponding cyclic carbonates in high yields. FAB-mass spectral and computational results suggest that [ZnBr(R 2 PO 4 ) 2 ] − could be an active species for the coupling reaction. Decomposition of cyclic carbonates into epoxides and CO 2 during the product recovery process via vacuum distillation was almost negligible even in the presence of a Zn-RTIL up to 130 °C.

Carbon nanotubes (CNTs) have specific properties, including electrical and thermal conductivity, great strength, and rigidity, that allow them to be used in many fields. However, this increasing contact with humans and the environment is also raising health and safety concerns. Thus, research on the safety of CNTs has attracted much interest, including a comparison of the toxic effects of asbestos and carbon nanotubes, due to their physical similarity of a high aspect ratio (length/diameter). Nonetheless, there has not yet been a toxicogenomic comparison. Therefore, to examine toxicogenomic effects, the 50% growth inhibition (GI(50)) concentration was determined for multi-wall carbon nanotubes (MWCNTs) and asbestos (crocidolite) and found to be approximately 0.0135 and 0.066%, respectively, in the case of 24-h treatment of normal human bronchial epithelia (NHBE) cells. Using these GI(50) concentrations, NHBE cells were then treated with MWCNTs and asbestos for 6 and 24 h, followed by a DNA microarray analysis. Among 31,647 genes, 1,201 and 1,252 were up-regulated by both asbestos and MWCNTs after 6 and 24 h of exposure, respectively. Meanwhile, 1,977 and 1,542 genes were down-regulated by both asbestos and MWNCTs after 6 and 24 h of exposure, respectively. In particular, the asbestos and MWCNTs both induced an over twofold up- and down-regulated expression of 12 mesothelioma-related genes and 22 lung cancer-related genes when compared with the negative control. Plus, the genes induced by the MWCNT exposure were expressed in the brain, lungs, epithelium, liver, and colon.

The spectroscopy, electrochemistry, and electrochemiluminescence (ECL) of cyclometalated iridium(III) bis(2-(p-tolyl)pyridinato-N, C2′) (picolinate) [(tpy)2Ir(pico)] was investigated. (tpy)2Ir(pico) shows high photoluminescence efficiency (ΦPL = ∼0.31) and quasi-reversible redox behaviors in acetonitrile solution. Intense green ECL was observed from all three modes of ECL generation (annihilation, oxidative-reduction, and reductive-oxidation). Relative ECL efficiencies with or without coreactants from (tpy)2Ir(pico) were estimated using Ru(bpy)32+ (bpy, 2,2′-bipyridine) as a relative standard. Typically, in the reductive-oxidation process with peroxodisulfate (S2O82−), (tpy)2Ir(pico) produces 8-fold more efficient ECL at approximately 531 nm than Ru(bpy)32. This efficient green ECL indicates potential for the development of multicolored ECL analysis in addition to standard Ru(bpy)32+ systems.

Melanin-like nanoparticles were synthesized with size control through neutralization of dopamine hydrochloride with NaOH, followed by spontaneous air oxidation of dopamine. Although the particle characteristic of natural melanins was understood to be significantly affected by the biological and structural environment, melanin-lke nanoparticles can be realized through the chemical reactions only. Melanin-like nanoparticles that are

In this study, light-emitting electrochemical cells (LECs) based on neutral iridium(III) bis(2-phenylquinolato-N,C2′)(3-isoquinaldate) were fabricated. An admixed solid supporting electrolyte tetra-n-butylammonium tetrafluoroborate (TBABF4) is employed in the emitting layer, and it facilitates charge injection with decreasing the potential barrier under a biased voltage. The cells generate an electroluminescence (EL) of 300 cd m-2 at −3.8 V. When the molar ratio of TBABF4 to the complex in the device was 2:1, a fast EL response of 0.8 s was obtained at −4.0 V after the several times of preconditioning. As the quantity of the supporting electrolyte increased, a faster and brighter EL response was obtained. Keywords: Light-emitting electrochemical cell, LEC, Iridium(III), Supporting electrolyte, Response time

The reaction of PdCl 2 dispersed in tetra-n-butylammonium bromide with tributyl amine at 120 °C under argon leads to stable isolable nanometric particles. X-ray diffraction analysis of the material indicated that it is constituted of Pd(0). Transmission electron microscopy analysis of the particles dispersed in acetone shows the mean particle size distribution (4 ± 1 nm). The isolated palladium nanoparticles can be dispersed in an ionic liquid or in methanol or used in solventless condition for selective hydrogenation of 2-hexyne under mild reaction conditions(0.2 MPa and 20 °C). The commercial variety of the Lindlar catalyst was also studied for comparative investigations.

We have developed a simple, efficient, and highly reproducible method to fabricate the large-area biomimetic superhydrophobic polymer surfaces having hierarchical structures of micrometer-sized irregular steps and nanometer-sized fibrils. Commercial Al plates (99.0%) were etched using Beck's dislocation etchant (mixture of HCl and HF) for different time periods in order to alter the structure of the etched Al surfaces from micrometer-sized to highly rough nanometer-sized irregular steps. These hierarchical structures could be easily replicated onto the surface of various thermoplastic polymer plates from the etched Al templates by applying heat and pressure; many polymer replicas without any significant deviations from each other could be duplicated from the same etched Al master templates. All of thermoplastic polymer replicas having hierarchical structures exhibited superhydrophobic properties with water contact angles of larger than 150 degrees. Especially, the surfaces of the high-density polyethylene (HDPE) replicas having nanometer-sized curled strands exhibited superhydrophobicity with a static water contact angle of approximately 160 degrees and a sliding angle of less than 2 degrees. These superhydrophobic HDPE replicas having nanometer-sized curled strands showed excellent stability after being exposed to various organic solvents and aqueous solutions of various pH.

The cephalosporin class antibacterial agent, cefazolin, was intercalated into layered double hydroxides (LDHs) in order to improve the drug efficiency as well as to achieve the controlled release property. Cefazolin molecules were incorporated into LDH through conventional ion exchange reaction. X-ray diffraction pattern analyses confirmed that cefazolin molecules were intercalated between the interlayer spaces of LDH. Fourier-transform infrared spectra and high performance liquid chromatographs clearly showed that the drug molecules were stabilized in LDH lattice through electrostatic interaction and released without any changes in their chemical integrity. Antibacterial activity of the cefazolin-LDH nanohybrid was also examined by an in vitro test, such as the minimal inhibitory concentration (MIC) by dilution method. Consequently, the cefazolin-LDH nanohybrid revealed an enhanced antibacterial activity compared to the cefazolin itself not only due to an improvement of chemical stability of cefazolin molecules but also due to a controlled release property.

By means of X-ray photoelectron spectrometry depth profile and transmission electron microscopy analysis, this study reveals that amorphous Cu54Ni6Zr22Ti18 powders are enveloped by a thick (∼30 nm) oxide skin and a subsequent oxidation-induced partially nanocrystallized zone. The thick oxide skin changes the metallic glass surface to oxide ceramic. It is proposed that effective disruption of the oxide skin is essential to the sintering of metallic glass.

Thermally stable vinyl polymerized polynorbornene (PNB) is one of the challenging materials in porous low dielectric films for packaging applications. Nanoporous PNB thin films were obtained with poly(d,l-lactide) (PLA)-grafted norbornene copolymers. Thermally labile PLA chains act as pore generators in PNB films. Thermally stable PNB main chains were synthesized by Pd-catalyzed vinyl polymerization and PLA side chains were grafted onto the PNB main chains by ring opening polymerization. The brittle and poor processible properties of PNB could easily be controlled by the copolymerization with norbornene derivatives. In thin films, the PLA chains were found to thermally decompose at about 250 °C while the PNB matrix was stable during this pore generating process. The porosity of the porous PNB thin films could be controlled up to 18% with pore sizes below 5 nm range by varying the chain length of grafted PLA. Introduction of cross-linking epoxy groups onto the PNB main chains resulted in the formation of w...

Tungsten oxide was successfully deposited on the surface of copper powder and the thickness of coating layer was dependent on deposition time. Because a spontaneous reaction occurred on the interface between copper and tungsten-peroxo electrolyte, there was a maximum thickness that could be obtained, as confirmed from XRD and EDX results. Mesoporous tungsten oxide was also deposited using SDS as a structure directing agent. As-synthesized tungsten oxide was amorphous and, after calcination at 450 °C, crystallized tungsten oxide was produced. Compared to pure tungsten oxide, the tungsten oxide coated copper oxide showed enhanced absorption in the visible region.

Mesoporous Pt–Au alloy films were successfully fabricated on ITO-coated glass from an aqueous mixture of H 2 PtCl 6 and HAuCl 4 by electrodeposition method using proper amount of poly(ethylene glycol)–poly(propylene glycol)–poly(ethylene glycol) (P123) as a templating agent. For comparison, nonporous Pt and mesoporous Pt were electrodeposited. Crystallinity of synthesized film was investigated by X-ray diffraction (XRD) analysis, and film composition was determined by energy dispersive X-ray spectroscopy (EDS). Scanning electron microscopy (SEM) was utilized to examine surface morphology and it was observed that the addition of P123 affected the particle growth, resulting in a significant change of surface morphology. The mesoporous structure was confirmed by transmission electron microscopy (TEM), and it was concluded that the formation of mesoporous structure strongly depended on electrodeposition conditions, such as deposition voltage, deposition time, temperature and P123 concentration. Compared with pure Pt electrodes, mesoporous Pt–Au film showed higher catalytic activities and stability for methanol oxidation.

Well-defined hierarchical structures, 3-dimensional upright structures containing aligned nanoembosses or nanoposts within micron-sized patterned areas, were realized on a polymer surface by utilizing patterned anodized aluminum oxide (AAO) and electrochemical reactions followed by a heat- and pressure-driven polymer imprinting technique. Sputtered Al on AAO could work excellently as a mask for the selective etching of AAO and successive anodization processes and many interesting hierarchical structures could be generated on an Al surface, from which hierarchical structures could be reproducibly duplicated onto polymer surfaces.

This work is to report not only the effect of rapid solidification of alloys on the micro-structure, but also the extrusion behavior on the materials properties. The average grain size of the atomized powders was about . The alloy powders of , consisted of I-Phase (Icosahedral, ) as well as Cubic structured W-Phase (), which was finely distributed within matrix. The oxide layer formed along the Mg surface was about 48 nm in thickness. In order to study the consolidation behavior of Mg alloy powders, extrusion was carried out with the area reduction ratio of 10:1 to 20:1. As the ratio increased, fully deformed and homogeneous microstructure could be obtained, and the mechanical properties such as tensile strength and elongation were simultaneously increased.

Molten Mg alloys burn rapidly in air if not protected. In order to handle molten Mg safely, the molten metal should be protected from oxidation by covering the surface with flux or protective gases. Sulfur hexafluoride (SF6) gas is widely used for Mg alloy as a cover gas and has proved to be a successful inhibitor. However, the use of SF6 gas is limited because of its high cost and its significant impact on global warming potential (GWP). Therefore, SF6 gas is being replaced by alternative protection gases such as tetrafluoro ethane (HFC-134a) and 3M NovecTM 612. These gases are less expensive and have lower GWP, compared with SF6 gas. Recent studies show that there has been another attempt by adding CaO into Mg alloys to manufacture CaO added AZ31Mg alloy in terms of increasing ignition temperature and reducing protective cover gas amount during melting and casting. This paper discusses effect of CaO on ignition and oxidation behaviors of AZ31 Mg alloy as well as on surface roughness and mechanical properties of AZ31 Mg alloy extruded bars.

Two types of porogens were tested to prepare porous low dielectric films. PCL porogens as well as Tetronic block copolymer porogens generate pores within the films thus lowering the dielectric constant. Tetronic porogens, however, yield porous films without significant matrix-porogen interactions and thus result in higher mechanical properties with lower dielectric constant, when compared with the PCL porogens.

Nanomaterials are used in diverse fields including food, cosmetic, and medical industries. Titanium dioxide nanoparticles (TiO2-NP) are widely used, but their effects on biological systems and mechanism of toxicity have not been elucidated fully. Here, we report the toxicological mechanism of TiO2-NP in cell organelles. Human bronchial epithelial cells (16HBE14o-) were exposed to 50 and 100 mu g/mL TiO2-NP for 24 and 48 h. Our results showed that TiO2-NP induced endoplasmic reticulum (ER) stress in the cells and disrupted the mitochondria-associated endoplasmic reticulum membranes (MAMs) and calcium ion balance, thereby increasing autophagy. In contrast, an inhibitor of ER stress, tauroursodeoxycholic acid (TUDCA), mitigated the cellular toxic response, suggesting that TiO2-NP promoted toxicity via ER stress. This novel mechanism of TiO2-NP toxicity in human bronchial epithelial cells suggests that further exhaustive research on the harmful effects of these nanoparticles in relevant organisms is needed for their safe application.

Polymer-supported Zn catalysts for the transesterification were successfully prepared by deliberately choosing the polymer surface anchored AMP (2-aminomethylpyridine) as a ligand and they showed a heterogeneous catalytic activity with an easy recyclability on the transesterification reaction of various substrates by methanol at room temperature under the mild and neutral conditions.

Processible norbornene copolymers were realized by judiciously designing norbornene comonomers, which were themselves prepared by the Diels-Alder reaction of cyclopentadiene and benzoquinone followed by the isomerization and alkylation of alcohols. The norbornene copolymers containing these derivatized comonomers, prepared by [Pd(NCCH2CH3)4][SbF6]2 catalyst, exhibited excellent solubility in many organic solvents as well as good thermal stability, as evidenced by their high glass transition (Tg) and decomposition (∼350°C) temperatures. In addition, fairly strong adhesion to substrates such as glasses and silicon wafers was also achieved with these copolymers to overcome the limitations experienced by polynorbornene homopolymers and to make them attractive for many important industrial applications.