Surface Properties

Nine non-noble-metal catalysts (NNMCs) from five different laboratories were investigated for the catalysis of O 2 electroreduction in an acidic medium. The catalyst precursors were synthesized by wet impregnation, planetary ball milling, a foamingagent technique, or a templating method. All catalyst precursors were subjected to one or more heat treatments at 700-1050°C in an inert or reactive atmosphere. These catalysts underwent an identical set of electrochemical characterizations, including rotatingdisk-electrode and polymer-electrolyte membrane fuel cell (PEMFC) tests and voltammetry under N 2 . Ex situ characterization was comprised of X-ray photoelectron spectroscopy, neutron activation analysis, scanning electron microscopy, and N 2 adsorption and its analysis with an advanced model for carbonaceous powders. In PEMFC, several NNMCs display mass activities of 10-20 A g -1 at 0.8 V versus a reversible hydrogen electrode, and one shows 80 A g -1 . The latter value corresponds to a volumetric activity of 19 A cm -3 under reference conditions and represents one-seventh of the target defined by the U.S. Department of Energy for 2010 (130 A cm -3 ). The activity of all NNMCs is mainly governed by the microporous surface area, and active sites seem to be hosted in pore sizes of 5-15 Å. The nitrogen and metal (iron or cobalt) seem to be present in sufficient amounts in the NNMCs and do not limit activity. The paper discusses probable directions for synthesizing more active NNMCs. This could be achieved through multiple pyrolysis steps, ball-milling steps, and control of the powder morphology by the addition of foaming agents and/or sulfur.

d e n t a l m a t e r i a l s 2 6 ( 2 0 1 0 ) 600-607 a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . i n t l . e l s e v i e r h e a l t h . c o m / j o u r n a l s / d e m a a b s t r a c t Objectives. Resin-modified glass ionomers (RMGI) have demonstrated clinical success providing immediate and long-term relief from root sensitivity. RMGIs have been recently introduced as paste-liquid systems for convenience of clinical usage. The objective of this study was to measure the ability of a new paste-liquid RMGI to reduce fluid flow through human dentin, compared to an established single-bottle nanofilled total etch resin adhesive indicated for root desensitization.

Introduction-Eliminating and/or inhibiting bacterial growth within the root canal system have been shown to play a key role in the regenerative outcome. The aim of this study was to synthesize and determine in vitro both the antimicrobial effectiveness and cytocompatibility of bi-mix antibiotic-containing polydioxanone (PDS)-based polymer scaffolds. Methods-Antibiotic-containing (metronidazole, MET and ciprofloxacin, CIP) polymer solutions (distinct antibiotic weight ratios) were spun into fibers as a potential mimic to the double antibiotic paste (DAP, a MET/CIP mixture). Fiber morphology, chemical characteristics, and tensile strength were evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and tensile testing, respectively. Antimicrobial efficacy was tested over time (aliquot collection) against Enterococcus faecalis (Ef), Porphyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn). Similarly, cytotoxicity was evaluated in human dental pulp stem cells (hDPSCs). Data were statistically analyzed (p<0.05). Results-SEM and FTIR confirmed that electrospinning was able to produce antibioticcontaining fibers with diameter mostly in the nanoscale. Tensile strength of 1:1MET/CIP scaffolds was significantly (p<0.05) higher than pure PDS (control). Meanwhile, all other groups presented similar strength as the control. Aliquots obtained from antibiotic-containing scaffolds inhibited growth of Ef, Pg and Fn, except pure MET that did not show an inhibitory action towards Pg or Fn. Antibiotic-containing aliquots promoted slight hDPSCs viability reduction, but none of them were considered to be cytotoxic.

Coupling of localized surface plasmon resonances results in singular effects at the void space between noble metal nanoparticles. However, implementation of practical applications based on plasmon coupling calls for the high yield production of metal nanoparticle clusters (dimers, trimers, tetramers,.) with small gaps. Therefore, controlled assembly using colloid chemistry methods is an emerging and promising field. We present a brief overview over the controlled assembly of plasmonic nanoparticle clusters by colloid chemistry methods, together with a description of their plasmonic properties and some applications, with an emphasis in sensing through surface-enhanced Raman scattering spectroscopy for bio-detection purposes. We point out the important role of separation methods to obtain colloidal clusters in high yield. A special encouragement to explore assembly of anisotropic building blocks is pursued.

By varying the sound-absorption treatments in a simulated classroom, experimental results were compared with analytical and computer predictions of reverberation time. Analytical predictions were made with different absorption exponents, which are the result of different weighting procedures involving room surface areas and the sound-absorption coefficients. Sound scattering was found to influence measured reverberation times. With the amount of sound scattering provided, more accurate analytical predictions were obtained with absorption exponents that give reverberation times longer than those obtained with the Sabine absorption exponent, which consistently underpredicted reverberation times. However, none of the absorption exponents could be singled out as more adequate because of similar average accuracy. Computer predictions of reverberation time were accomplished with two commercially available ray-based programs, RAYNOISE 3.0 and ODEON 2.6, with specular and calibrated diffuse reflection procedures. Neither type of procedure, in either program, was more accurate than the best analytical predictions. With RAYNOISE, neither the specular nor the calibrated diffuse reflection procedure could be singled out as more adequate. For ODEON, the calibrated diffuse reflection procedure gave consistently more accurate predictions than its specular reflection procedure, with the best accuracy of the computer predictions. ͓S0001-4966͑00͒04710-X͔

Currently, no consensus exists regarding the best adhesion protocol for zirconia used in dentistry; this is important particularly for restorations where mechanical retention is deficient. This systematic review analyzed the adhesion potential of resin-based and glass-ionomer luting cements to zirconia and aimed to highlight the possible dominant factors affecting the bond strength results to this substrate. Original scientific papers on adhesion to zirconia published in the MEDLINE (PubMed) database between 01/01/1995 and 01/06/2011 were included in this systematic review. The following MeSH terms, search terms, and their combinations were used: &quot;Dental bonding&quot;, &quot;Zirconium&quot;, &quot;Zirconia&quot;, &quot;Y-TZP&quot;, &quot;Y-TZP ceramic&quot;, &quot;Materials Testing/methods&quot;, &quot;Test&quot;, &quot;Cement&quot;, and &quot;Resin bonding&quot;. Two reviewers performed screening and data abstraction. Descriptive statistics were performed and the frequencies o...

Aim  To evaluate marginal seal, water sorption, solubility and loss of mass after brushing of several temporary filling materials.Methodology  For marginal seal, Class I cavities, including endodontic access preparations, were made in human molar teeth and restored using one or other of several temporary filling materials (n = 10): zinc oxide/calcium sulphate-based cement (Cavit, 3M,ESPE, St. Paul, MN, USA), zinc oxide/eugenol cement (IRM, Dentsply Caulk, Milford, DE, USA), glass ionomer cement (Vidrion R, SSWhite, Rio de Janeiro, RJ, Brazil) or a dimethacrylate-based filling (Bioplic, Biodinâmica, Londrina, PR, Brazil). Dye penetration was assessed after thermocycling and immersion in 0.5% basic fuchsine solution. For water sorption, solubility and loss of mass analyses, disc-shaped specimens were made. Water sorption and solubility were evaluated by mass alteration after storage in distilled water for 7 days (n = 7). Loss of mass was calculated based on the difference of mass after abrasion with a toothbrush (n = 5), and surfaces were analysed by SEM. Data of water sorption, solubility and loss of mass were submitted to anova and Tukey’s test, and marginal sealing data to Kruskal–Wallis test (P < 0.05).Results  Statistically significant differences were observed for marginal sealing (P < 0.0001), water sorption (P < 0.01), solubility (P < 0.01) and loss of mass (P < 0.05). Bioplic had the best marginal seal. Cavit had the greatest water sorption and solubility. Vidrion R and Bioplic had the lowest solubility. Loss of mass after brushing was higher for Cavit, followed by Bioplic, IRM and Vidrion R. Cavit and Vidrion R were worn aggressively by brushing.Conclusions  The resin-based temporary filling Bioplic produced the best marginal seal, and was associated with the lowest water sorption, solubility and loss of mass.

d e n t a l m a t e r i a l s 2 8 ( 2 0 1 2 ) 467-477 Adhesion Dental materials Zirconia Titanium Resin composites and cements a b s t r a c t Objectives. To give an overview of aspects of silane coupling agents and surface conditioning in dentistry.

This study was aimed to formulate and evaluate anti-aging effects of a topical cream (w/o emulsion) containig extract of Fennel (Foeniculum vulgare) versus its base. Formulation containing 4% concentrated extract of Foeniculum vulgare was developed by entrapping in the inner aqueous phase of w/o emulsion and base contained no extract. Both the base and formulation were stored under different storage conditions to predict their stability. The formulation and base were evaluated for effect on skin moisture and transepidermal water loss (TEWL). The base showed insignificant while the formulation showed significant effects on skin moisture and TEWL. The parameter volume and surface evaluation of living skin (SELS) parameters SEr, SEsc, SEsm, SEw were also evaluated and showed a significant (p ≤ 0.05) decline. The texture parameter energy showed a significant increase proving that the formulation possesses potential anti-aging effects.

The restoration of anterior teeth is a difficult task, even for an experienced operator. Currently there are many different ceramic systems that can be used to achieve highly esthetic results. These include metal-ceramics with porcelain margins, Dicor, In-Ceram, Cerestore, Hi-Ceram, IPS-Empress, Cerapearl, Optec, and CAD/CAM ceramics. While metal-ceramics have been used for more than four decades, the quest for a material that transmits and refracts light like a natural tooth has inspired research into all-ceramic restorations. The purpose of this paper is to briefly discuss the properties of each of the above-mentioned materials and clinically evaluate the optical behavior of: (1) metal-ceramic crowns with castings 2 mm short of the shoulder preparation and 360-degree porcelain margins; (2) In-Ceram Spinell restorations; and (3) IPS Empress restorations, and to compare these with metal-ceramic crowns with copings to the shoulder preparation and 180-degree porcelain margins. Light t...

Surfaces that resist protein adsorption are important for many bioanalytical applications. Bovine serum albumin (BSA) coatings and multi-arm poly(ethylene glycol) (PEG) coatings display low levels of non-specific protein adsorption and have enabled highly quantitative single-molecule (SM) protein studies. Recently, a method was developed for coating a glass with PEG-BSA nanogels, a promising hybrid of these two low-background coatings. We characterized the nanogel coating to determine its suitability for SM protein experiments. SM adsorption counting revealed that nanogel-coated surfaces exhibit lower protein adsorption than covalently coupled BSA surfaces and monolayers of multi-arm PEG, so this surface displays one of the lowest degrees of protein adsorption yet observed. Additionally, the nanogel coating was resistant to DNA adsorption, underscoring the utility of the coating across a variety of SM experiments. The nanogel coating was found to be compatible with surfactants, whereas the BSA coating was not. Finally, applying the coating to a real-world study, we found that single ligand molecules could be tethered to this surface and detected with high sensitivity and specificity by a digital immunoassay. These results suggest that PEG -BSA nanogel coatings will be highly useful for the SM analysis of proteins.

A depth-enhanced three-dimensional integral imaging system with electrically variable image planes is proposed. For implementing the variable image planes, polymer-dispersed liquid-crystal (PDLC) films and a projector are adopted as a new display system in the integral imaging. Since the transparencies of PDLC films are electrically controllable, we can make each film diffuse the projected light successively with a different depth from the lens array. As a result, the proposed method enables control of the location of image planes electrically and enhances the depth. The principle of the proposed method is described, and experimental results are also presented.

Local wet etching technique was proposed to fabricate highperformance aspherical mirrors. In this process, only the limited area facing to the small nozzle is removed by etching on objective surface. The desired objective shape is deterministically fabricated by performing the numerically controlled scanning of the nozzle head. Using the technique, a plano-elliptical mirror to focus the neutron beam was successfully fabricated with the figure accuracy of less than 0.5µm and the focusing gain of 6. The strong and thin focused neutron beam is expected to be a useful tool for the analyses of various material properties.

Dimensional reduction of ZnO semiconductors is expected to create wide-ranging application possibilities from roomtemperature ultraviolet (UV) lasers, sensors, photocatalysts, solar cells, [4] to field-emission (FE) devices. In general, ZnO nanowires as one-dimensional (1D) materials with diameters of less than 10 nm are expected to display novel and unique physical and chemical properties due to quantum confinement. Furthermore, it is very important to fabricate a dense array of ZnO nanowires on an appropriate substrate so that the nanowires can be directly addressed, surface area can be optimized, and/or collective properties may be induced. A host of techniques have been developed for the synthesis of aligned 1D ZnO nanostructures with sizes in the range of 10-100 nm on a variety of substrates for nanodevice applications. [6] For example, well-aligned ZnO nanowires that are 10-15 nm across have been grown from patterned, thin gold dots on sapphire substrates by a vapor-liquid-solid (VLS) process. To our knowledge, however, little has been reported on the synthesis of well-aligned ZnO nanowires with diameters of less than 10 nm. Although 6nm ZnO nanobelts have been obtained by solid-vapor deposition, [9] they are randomly oriented. Therefore, one of the synthetic challenges of nanowire materials is to reduce the nanowire diameter and, at the same time, align the nanowires in a controlled fashion. Here, we demonstrate the first synthesis of aligned ZnO nanofibers, which are no thicker than 10 nm and % 500 nm in length, by hydrothermal treatment of a Zn foil in an ammonia/alcohol aqueous solution. It should be emphasized that the reaction was carried out at a relatively low temperature without any catalyst. We have established that the use of ammonia/alcohol is crucial to the growth of the aligned ultrathin ZnO nanofibers. Photoluminescence (PL) measurement at room temperature shows a prominent peak at 373 nm (3.32 eV), which is about 100 meV blue-shifted from the bulk ZnO emission (3.24 eV, 383 nm) due to the ultrafine dimension along the radial direction of the ZnO nanofibers.

Polyethlene terephthalate films were surface-modified with polyethylene oxide (18 500 g/mol) using a solution technique described previously. These films were investigated for their resistance to bacterial adhesion. Three bacterial strains most commonly associated with implant infections, Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa, were cultured in tryptic soya broth, human plasma and human serum on the polymeric substrates. Significant reductions (between 70 and 95%) in adherent bacteria were observed on the polyethylene oxide-modified substrates compared to the untreated control polyethylene terephthalate.

We investigated the effect of optical thick metal films on the surface-enhanced Raman scattering (SERS) activity of individual Au nanoparticle (NP) monomers and dimers. The film presence is revealed to be positive for the SERS activity of individual NP monomers, while it is not always positive for the electromagnetic enhancement at hot spots for SERS of the dimer, which is explained well by our numerical simulations. The polarized SERS signals from the NP dimer are elucidated well in terms of the plasmon hybridization of the dimer. SERS contributions both from individual NP surfaces and the junction between the NP and its supporting substrate were discussed as well.

Cytocompatible, co-doped cerium oxide nanoparticles exhibited strong upconversion properties that were found to kill lung cancer cells by inducing apoptosis thereby demonstrating the potential to be used as clinical contrast agents for imaging and as therapeutic agents for treatment of cancer.

Subsurface scattering within translucent objects is a complex phenomenon. Designing and rendering this kind of material requires a faithful description of their aspects as well as a realistic simulation of their interaction with light. This paper presents an efficient rendering technique of multilayered translucent objects. We present a new method for modeling and rendering such complex organic materials made up of multiple layers of variable thickness. Based on the relief texture mapping algorithm, our method calculates the single scattering contribution for this kind of material in real-time using commodity graphics hardware. Our approach needs the calculation of distances traversed by a light ray through a translucent object. This calculation is required for evaluating the attenuation of light within the material. We use a surface approximation algorithm to quickly evaluate these distances. Our whole algorithm is implemented using pixel shaders.

The aim of the present study was to prepare, optimize and characterize ketoprofen proniosomes. The niosomes were prepared using a slurry method followed by in vitro evaluation after embedding the proniosomes-derived niosomes into a carbopol matrix. A central, composite Box-Wilson design was used for the optimization with the total lipid concentration (X 1 ), surfactant loading (X 2 ) and amount of drug (X 3 ) as the independent variables. Prepared proniosomes were characterized for percentage drug entrapment (PDE) and mean volume diameter (MVD). Multiple regression analysis and contour plots were used to relate the dependent and independent variables. Checkpoint batches were also prepared to prove the validity of the evolved mathematical model and contour plots. The optimization model predicted the levels of X 1 , X 2 and X 3 (-1, -0.3 and 0.92, respectively), for a maximized response of PDE with constraints of ≤ 5 μm on MVD. Optimized batch was used to prepare a niosomal gel, which showed significantly higher cumulative amount of drug permeated and steady state transdermal flux compared to plain gel. This work has demonstrated the use of the central composite Box-Wilson design, regression analysis, and contour plots in optimizing ketoprofen proniosomes. Developed niosomal gel formulation has also demonstrated permeation enhancement of ketoprofen compared to plain gel.

Determinations of IgG subclasses were made by electroimmunoassay and crossed immunoelectrophoresis, and Gm markers were typed in sera from seventeen patients with well-defined immunodeficiency diseases. Certain IgG subclass and Gm patterns were recognized in various diseases: IgG2 deficiency and homozygosity of Gm(4,5) in the cartilage-hair-hypoplasia syndrome, in the ataxia telangiectasia syndrome and in selective IgG subclass deficiency; and IgG3 deficiency and homozygosity of Gm(1,-5) in the Wiskott-Aldrich syndrome. The findings suggest a common structural or regulator gene defect in some immunodeficiency diseases. In IgA deficiencies, the levels of IgG1 were raised. In patients with IgG subclass deficiencies there was sometimes a compensatory increase of the remaining IgG subclasses, with a preponderance of IgG1 and IgG3. The increased IgGI showed restricted heterogeneity with only an increase ofthe electrophoretically cathodal part. This part contained both kappa and lambda chains. IgG subclass deficiency indicates treatment with gammaglobulin even if the serum levels of IgG are normal or increased.

Spray drying techniques have been applied to improve the solubility and dissolution rate of poorly water-soluble salicylic acid. Spray drying of the acid dispersed in acacia solutions resulted in as much as a 50% improvement in the solubility of the product. Solubility improvement was closely related not only to the concentration of acacia but also the amount of amorphous material in the spray-dried products. The heat of solution was inversely related to these parameters. The dissolution rate of spray-dried product was almost instantaneous being about 60 times faster than that of the original powder. A great improvement in the wettability of the spray-dried material seemed to be mainly responsible for the increase of dissolution rate.

Phosphate-based glasses have been examined in many studies as a potential biomaterial for bone repair because of its degradation properties, which can be controlled and allow the release of various elements to promote osteogenic tissue growth. However most of these experiments studied either tertiary or quaternary glass systems. This study investigated a qinternary system that included titanium dioxide for degradation rate control and zinc that is considered to have a role in bone formation. Zinc and titanium phosphate glass discs of different compositions were melt synthesized and samples of each composition was tested for different physical, chemical and biological characteristics via density measurement, X-ray diffraction, differential thermal analysis, mass loss, ion release, scanning electron microscopy, biocompatibility studies via live/dead assays at three time points (day 1, 4, and 7). The results showed that the glass was amorphous and that the all thermal variables decreas...

of the bur. Additional abrasion mesial and distal to the center line of the base can further reduce the force needed to fracture the bracket in debonding (C). Once the fracture line has been created, use either a Weingart or a How plier to squeeze and fracture the tie wings (D). How pliers tend to produce better results than Weingart pliers because of the greater distance between the plier hinge and tips, which makes for a better fit between the internal surfaces of the tips and the external surfaces of the tie wings. In most cases, the two halves of the bracket will debond simultaneously. If one half stays on the tooth, it is easily removed by applying a rocking motion with the same plier. Ceramic fragments often remain on the enamel after debonding of monocrystalline brackets1 (E), requiring removal with the same high-speed diamond bur under water cooling. Any adhesive remnants should be removed by using a low-speed, sixor 12-blade tungsten carbide bur with a smooth, rounded tip. ...

The aim of this study was to evaluate the effects of different techniques of surface treatment on the microleakage of fissure sealants in permanent molar teeth in vitro. 96 extracted impacted human third molars were randomly divided into 8 surface treatment groups (n=12/group) as 1. Er: YAG laser ; (Fidelis II, Fotona, Ljubljana, Slovenia) (125 mj, 20Hz) ; 2. Er: YAG laser + 37% H3PO4 (15s) ; 3. ER: AG laser + 37% H3PO4+Prime&Bond NT ; 4. Er: YAG laser + G Bond ; 5. Er: YAG laser + Prime&Bond NT ; 6. 37% H3PO4 ; 7. 37% H3PO4 + Prime&Bond NT ; 8. G Bond. Sealant material (Clinpro, 3M ESPE, Seefeld, Germany), was applied into the fissures and light-cured for 20s with LED (Bluephase C5, Ivoclar-Vivadent, Schaan, Liechtenstein). Specimens were subjected to thermocycling (1000×, 5-55°C, dwell time: 15s) and immersed in 0.5% basic fuchsin solution for 24h at 37°C. The samples were sectioned and scored on a 3 point rating scale using a light microscope with a magnification of ×20. One-way ...

Replacement of lost teeth using oral implants is an accepted treatment modality with well-documented high long-term success rates. Conventional screw- or threaded cylinder-type implants have been used almost exclusively. Their incongruence with the extraction socket necessitates the use of a barrier membrane or bone augmentation to prevent down-growth of connective tissue or epithelium between the implant and socket. Although some minor changes in implant design have been made, the neck and abutment connection areas have not changed much in the past 30 years. Custom-made root analog implants have been employed clinically in rare instances; however, they yielded failure rates of up to 96% at 1 year of follow-up. So far, ovoid implants are the closest in design regarding resemblance to the natural tooth anatomy. Root analog zirconia implants with macroretentions were developed and produced for immediate single-stage replacement of missing or hopeless teeth. This article discusses the ...

The formation of a salivary pellicle is a prerequisite of bacterial colonization on the tooth, and the aim of this study has been to further the understanding of the role of surface properties in the formation of the salivary pellicle and subsequent adhesion of oral bacteria. Surface modification as a means of interfering with pellicle and plaque formation has been investigated. Five different silicone-containing compounds were used for the surface treatments: polydimethylsiloxane containing aminoalkyl groups {I), polydimethylsiloxane containing partially neutralized aminoalkyl groups (Ill, ethyl silicate (llt), potassium methyl siliconate (IV) and sodium silicate (V). Studies of water wetting, surface charge, oral bacterial adherence and pellicle formation were performed on glass slides and hydroxyapatite beads coated by the test compounds. No correlation was found between contact angle and surface charge, and evidently hydrophobicity, as expressed by water wetting, is not necessarily an indication of a low surface concentration of polar groups. All compounds reduced bacterial adherence after saliva contact, compound IV by around 90%. Different pauerns were seen in the adsorption of pellicle proteins on the different polysiloxanes.

Supporting information AFM Studies. Alkanethiol materials. 1-adamantanethiol (AD) of 95% purity was purchased from Sigma-Aldrich (Missouri, USA) and was used as received. Ethanol solvent of 99.99% purity was purchased from Gold Shield Chemical Co. (California, USA) and served as the solvent for AD. Preparation of 1-adamantanethiol Self-Assembled Monolayers (SAM). The SAM preparation used in this study follows established procedures. 1, 2 Gold with 99,999% purity was purchased from Alfa Aesar (Massachusetts, USA) was deposited in a high-vacuum evaporator (Model DV502-A, Denton Vacuum, New Jersey, USA) at a base pressure below 2 x 10-7 Torr onto freshly cleaved mica substrates

Sum frequency generation (SFG) vibrational spectroscopy has been applied to investigate surface structures of an amphiphilic surface-active block copolymer (SABC) film deposited on a CaF 2 substrate, in air and in water in situ. Developed as a surface-active component of an antifouling coating for marine applications, this amphiphilic triblock copolymer contains both hydrophobic fluorinated alkyl groups as well as hydrophilic ethoxy groups. It was found that surface structures of the copolymer film in air and in water cannot be probed directly using the SFG experimental geometry we adopted because SFG signals can be contributed from the polymer/air (or polymer/water) interface as well as the buried polymer/CaF 2 substrate interface. Using polymer films with varied thicknesses, structural information about the polymer surfaces in air and in water can be deduced from the detected SFG signals. With SFG, surface restructuring of this polymer has been observed in water, especially the methyl and methylene groups change orientations upon contact with water. However, the hydrophobic fluoroalkyl group was present on the surface in both air and water, and we believe that it was held near the surface in water by its neighboring ethoxy groups.

A series of ceria nanoparticles were synthesized by using a microemulsion method. The effect of relative concentration of surfactant/water on the size and the surface roughness of ceria nanoparticles was examined using transmission electron microscopy (TEM) and atomic force microscopy (AFM) respectively. The investigation confirmed a relationship between the size and the roughness properties of the nanoceria as a function of the water to surfactant ratio. With increasing dilution of the surfactant, the size distribution became narrow such that average particle size decreased linearly as the ratio increased without affecting lower size threshold of particles (∼10 nm). The surface roughness, on the other hand was found to increase with increasing water to surfactant ratio implying diluted surfactant would provide rougher surface of ceria nanoparticles. The information can be used to tailor the adhesion properties of nanoceria by optimizing the size distribution as well as surface roughness as a function of water to surfactant ratio.

We report on a method for the large-scale production of graphene micropatterns by a self-assembly mediated process. The evaporation-induced self-assembly technique was engineered to produce highly ordered graphene patterns on flexible substrates in a simplified and scalable manner. The crossed stripe graphene patterns have been produced over a large area with regions consisting of single-and two-layer graphene. Based on these graphene patterns, flexible graphene-based field effect transistors have been fabricated with an ion-gel gate dielectric, which operates at low voltages of < 2 V with a hole and electron mobility of 214 and 106 cm 2 /V·s, respectively. The self-assembly approach described here may pave the way for the nonlithographic production of graphene patterns, which is scalable to large areas and compatible with roll-to-roll system.

The self-assembly of the trifluoroacetate salt of the short peptide (ala) 6 -lys (A 6 K) in water has been investigated by cryo-transmission electron microscopy and small-angle X-ray scattering. For concentrations below ca. 12%, the peptide does not self-assemble but forms a molecularly dispersed solution. Above this critical concentration, however, A 6 K self-assembles into several-micrometer-long hollow nanotubes with a monodisperse crosssectional radius of 26 nm. Because the peptides carry a positive charge, the nanotubes are charge-stabilized. Because of the very large aspect ratio, the tubes form an ordered phase that presumably is nematic. (16) Knaapila, M.; Svensson, C.; Barauskas, J.; Zackrisson, M.; Nielsen, S. S.; Toft, K. N.; Vestergaard, B.; Arleth, L.; Olsson, U.; Pedersen, J. S.; Cerenius, Y.

Selective partial oxidation of methane to syngas over LaNiO 3 , La 0.8 Ca(or Sr) 0.2 NiO 3 and LaNi 1−x Co x O 3 (where x = 0.2-1) perovskites at extremely short contact time ( ≈0.8 ms) has been investigated. Also, simultaneous oxidative conversion and steam and CO 2 reforming of methane to syngas over LaNiO 3 at short contact time ( ≈9 ms) has been studied at different temperatures and CH 4 /O 2 feed ratios. The catalysts, before and after reaction, were characterized by XRD and SEM. LaNiO 3 perovskite shows high activity and selectivity in the oxidative conversion of methane to syngas. However, the partial substitution of its La by Ca or Sr and also the partial or complete substitution of its Ni by Co causes a large decrease in both its activity and its selectivity. LaNiO 3 is transformed to its catalytically active form, Ni 0 /La 2 O 3 , during the initial period of the process. This catalyst shows very good performance in the simultaneous oxidative conversion (which is exothermic) and steam and CO 2 reforming reactions (which are endothermic) of methane to syngas, at short contact time, operating in a most energy efficient manner and also requiring only a little or no external energy.

Pseudomonads are able to form a variety of biofilms that colonize the air-liquid (A-L) interface of static liquid microcosms, and differ in matrix composition, strength, resilience and degrees of attachment to the microcosm walls. From Pseudomonas fluorescens SBW25, mutants have evolved during prolonged adaptation-evolution experiments which produce robust biofilms of the physically cohesive class at the A-L interface, and which have been well characterized. In this study we describe a novel A-L interface biofilm produced by SBW25 that is categorized as a viscous mass (VM)-class biofilm. Several metals were found to induce this biofilm in static King's B microcosms, including copper, iron, lead and manganese, and we have used iron to allow further examination of this structure. Iron was demonstrated to induce SBW25 to express cellulose, which provided the matrix of the biofilm, a weak structure that was readily destroyed by physical disturbance. This was confirmed in situ by a low (0.023-0.047 g) maximum deformation mass and relatively poor attachment as measured by crystal violet staining. Biofilm strength increased with increasing iron concentration, in contrast to attachment levels, which decreased with increasing iron. Furthermore, iron added to mature biofilms significantly increased strength, suggesting that iron also promotes interactions between cellulose fibres that increase matrix interconnectivity. Whilst weak attachment is important in maintaining the biofilm at the A-L interface, surface-interaction effects involving cellulose, which reduced surface tension bỹ 3.8 mN m "1 , may also contribute towards this localization. The fragility and viscoelastic nature of the biofilm were confirmed by controlled-stress amplitude sweep tests to characterize critical rheological parameters, which included a shear modulus of 0.75 Pa, a zero shear viscosity of 0.24 Pa s "1 and a flow point of 0.028 Pa. Growth and morphological data thus far support a non-specific metal-associated physiological, rather than mutational, origin for production of the SBW25 VM biofilm, which is an example of the versatility of bacteria to inhabit optimal niches within their environment.

ABSTRACTPurpose:: The purpose of this study was to determine the wear resistance of five different packable composites versus two different composite controls using a laboratory toothbrushing simulation test.The purpose of this study was to determine the wear resistance of five different packable composites versus two different composite controls using a laboratory toothbrushing simulation test.Materials and Methods: Twelve samples measuring 5 mm in diameter and 3 mm thick were prepared from the following resin composites: Packable resin composites SureFil® (Dentsply Ind. Com. Ltda, Petrópolis, Rio de Janeiro, Brazil), Alert® (Jeneric Pentron Incorporated, Wallingford, CT, USA), Filtek P60™ (3M ESPE Dental Products, St. Paul, MN, USA), Prodigy Condensable® (sds Kerr, Orange CA, USA), Solitaire® (Heraeus Kulzer GmbH, Wehrheim, Germany), and control resin composites Z100 Restorative™ (3M ESPE) and Silux Plus™ (3M ESPE). Finishing and polishing were conducted with Sof-Lex™ disks (3M ESPE), and baseline weight (grams) and surface roughness (measured with Hommel Tester® T 1000, Hommelwerke, GmbH, Alte Tuttinger Strebe 20. D-7730 VS-Schwenningen, Germany) were recorded. Specimens were aged for 2 weeks until they reached a weight that remained constant for 5 consecutive days, and then were subjected to 100,000 cycles of brushing (representative of 4.2 yr) using a toothbrushing testing machine. Toothbrush heads with soft bristle tips (Colgate Classic™, Colgate-Palmolive Co., Osasco, São Paulo, Brazil) with dentifrice suspension (Colgate MFP™, Colgate-Palmolive Co.) in deionized water were used under a 200 g load. Changes in weight and surface roughness were determined after toothbrushing cycles.Twelve samples measuring 5 mm in diameter and 3 mm thick were prepared from the following resin composites: Packable resin composites SureFil® (Dentsply Ind. Com. Ltda, Petrópolis, Rio de Janeiro, Brazil), Alert® (Jeneric Pentron Incorporated, Wallingford, CT, USA), Filtek P60™ (3M ESPE Dental Products, St. Paul, MN, USA), Prodigy Condensable® (sds Kerr, Orange CA, USA), Solitaire® (Heraeus Kulzer GmbH, Wehrheim, Germany), and control resin composites Z100 Restorative™ (3M ESPE) and Silux Plus™ (3M ESPE). Finishing and polishing were conducted with Sof-Lex™ disks (3M ESPE), and baseline weight (grams) and surface roughness (measured with Hommel Tester® T 1000, Hommelwerke, GmbH, Alte Tuttinger Strebe 20. D-7730 VS-Schwenningen, Germany) were recorded. Specimens were aged for 2 weeks until they reached a weight that remained constant for 5 consecutive days, and then were subjected to 100,000 cycles of brushing (representative of 4.2 yr) using a toothbrushing testing machine. Toothbrush heads with soft bristle tips (Colgate Classic™, Colgate-Palmolive Co., Osasco, São Paulo, Brazil) with dentifrice suspension (Colgate MFP™, Colgate-Palmolive Co.) in deionized water were used under a 200 g load. Changes in weight and surface roughness were determined after toothbrushing cycles.Results: Significant differences of weight loss and surface roughness were found (paired t-test, p < .05). Weight loss percentage (mean [SD]) ranged from 0.38 to 1.69% (analysis of variance and Tukey's least significant difference, p < .05); the weight loss of the materials ranked from least to most as follows: SureFil (0.38 [0.56]), Alert (0.52 [0.18]), Z100 (1.16 [0.27]), Filtek P60 (1.31 [0.17]), Solitaire (1.51 [0.45]), Prodigy Condensable (1.55 [0.47]), and Silux Plus (1.69 [0.66]). Regarding surface roughness, Prodigy Condensable (0.19 [0.08]), Solitaire (0.28 [0.06]), and Z100 (0.30 [0.07]) became less rough after toothbrushing, whereas all the others were rendered rougher: Alert (0.49 [0.29]), Filtek P60 (0.28 [0.08]), Silux Plus (0.39 [0.09]), and SureFil (0.81 [0.32]).Significant differences of weight loss and surface roughness were found (paired t-test, p < .05). Weight loss percentage (mean [SD]) ranged from 0.38 to 1.69% (analysis of variance and Tukey's least significant difference, p < .05); the weight loss of the materials ranked from least to most as follows: SureFil (0.38 [0.56]), Alert (0.52 [0.18]), Z100 (1.16 [0.27]), Filtek P60 (1.31 [0.17]), Solitaire (1.51 [0.45]), Prodigy Condensable (1.55 [0.47]), and Silux Plus (1.69 [0.66]). Regarding surface roughness, Prodigy Condensable (0.19 [0.08]), Solitaire (0.28 [0.06]), and Z100 (0.30 [0.07]) became less rough after toothbrushing, whereas all the others were rendered rougher: Alert (0.49 [0.29]), Filtek P60 (0.28 [0.08]), Silux Plus (0.39 [0.09]), and SureFil (0.81 [0.32]).Conclusion: SureFil and Alert were statistically more resistant to wear (less weight loss) than were the other materials. SureFil became significantly rougher than did all the others.SureFil and Alert were statistically more resistant to wear (less weight loss) than were the other materials. SureFil became significantly rougher than did all the others.

We have investigated the structure and energies of lithium microclusters containing 3±10 atoms in the fcc(100) and fcc surface symmetries, and the interaction of an oxygen and hydrogen atom with these lithium microclusters for the on-top, open and bridge sites approaches. The calculations have been performed with molecular dynamics simulation methods (MDSM) at 1 K temperature and the results were compared with the literature. q