Abstract  Abstract: α-PW12O40 ^{3−} (PW12) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH3PW12) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry. There is an ionic bonding character between PW12 and the surface amino groups of modified silica, which greatly improves the stability of SiNH3PW12-modified carbon paste electrode due to insolubility of silica gel in water. The SiNH3PW12 bulk-modified carbon paste electrode not only maintains the electrochemical activity of PW12, but also exhibits remarkable advantages of renewability, as well as simple preparation and inexpensive material. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of IO3 ^{−} and hydrogen peroxide. The SiNH3PW12-CPE is successfully applied as an electrochemical detector to monitor IO3 ^{−} in flow injection analysis (FIA). The catalytic peak current was found to be linear with the IO3 ^{−} concentration in the range 5×10^{−6} to 1×10^{−3} molL^{−1}. The detection limit of the proposed method was found to be 3.1×10^{−6} molL^{−1} for IO3 ^{−} determination. [Copyright 2008 Elsevier] Copyright of Talanta is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)

Abstract  The study evaluated the effect of ozone application on the composite-to-composite bond. Three hundred and twenty cylindrical composite specimens were divided into two groups: group 1 was subjected to a 60 s ozone application, whereas group 2 remained untreated. Four subgroups were obtained from each group according to the intermediate repair agent: an adhesive, a silane, silane/adhesive combination, or flowable composite. Repair composite cylinders were built-up. The composite repair strength was tested after 24 h and after thermocycling with a shear test. Additionally, 4 mm x 4 mm x 2 mm composite specimens were prepared and stored 24 h in deionized water. Half of the specimens were subjected to ozone application and the other served as control. The elastic modulus (E) and the Vicker's hardness (VH) of the composite surfaces were tested immediately and after thermocycling. Significant differences among the experimental groups were detected (p < 0.001). The composite repair strength was affected by the pretreatment and by the intermediate agent, whereas, the thermocycling was not significant. The partial eta-squared statistics showed that the intermediate agent was the main factor affecting the composite repair strength, whereas the pretreatment played a minor role. No differences were observed between ozone and control groups when the same intermediate agent and the same aging conditions were applied. Repairing with flowable composite tended to achieve higher bond strengths (20.7 and 26.5 MPa in ozone and control groups, respectively, after 24 h). The use of silane coupling agent showed the lowest composite repair strengths. Ozone did not affect E and VH (p > 0.05) and the thermocycling affected only E (p < 0.05). In conclusion, the application of ozone does not impair the composite-to-composite bond.

Abstract  Superhydrophobic cotton textiles are prepared by a simple, one-step and inexpensive phase separation method under ambient conditions by which a layer of polymethylsilsesquioxane (PMSQ) nanostructures is covered onto the cellulose fibers. By changing the silane precursor concentration, PMSQ nanostructures with various shapes, morphologies and sizes were fabricated. Nanostructures were characterized using SEM, EDS, and attenuated total reflectance FTIR. The wettability of the modified cellulose surfaces was characterized with contact-angle goniometry and sliding angle technique, respectively. The water contact angle of modified cotton is measured to be higher than 150°, which is high enough to exhibit the lotus effect as a result of the superhydrophobicity. Tunable water-repellent properties of the fabric are also demonstrated, with sliding contact angles varying from "sticky" to "slippery" depending upon different nanostructures on the surface of the fibers. It is expected that this simple technique will accelerate the large-scale production of superhydrophobic cellulosic materials with new industrial applications.

Abstract  Layer-by-layer covalent assembly of an oligoimide on an anhydride- derivatized silicon dioxide surface is investigated using supercritical carbon dioxide (SCCO2) as the depositing medium. The deposited films were characterized by X-ray photoelectron spectroscopy (XPS), ellipsometry (VASE), UV-visible spectroscopy, electrochemical impedance spectroscopy, nano indentation, and atomic force microscopy (AFM) and the properties of the films compared with those of an oligoimide deposited on amine-derivatized surfaces. Films formed on the anhydride surface are more uniform and stable possibly because the silane precursor for the anhydride is anchored to the surface through two (-Si-O-Si-) tripods. XPS results indicate that the interfacial reaction resulting in amide formation is almost complete in the case of the anhydride, but not in the case of the amine. We infer that the twin tripods linking the anhydride group to the surface may have improved the accessibility of the functional groups for immobilization of the next layer, thereby contributing to the better quality.

Abstract  PURPOSE: This paper aims to examine varied surface treatments combined with adhesive bonding to ascertain the highest bond strength of the composite resin repair. MATERIALS AND METHODS: A total of 100 specimens was made using an increment technique. The prepared specimens were aged for 20 days in 37 degrees +/- 20 degrees C water and then kept for 24 h at room temperature. The samples were separated into 5 groups of 20, and each group then received a different surface treatment (control group, phosphoric acid, diamond bur, air abrasion, silane primer combined with a diamond bur treatment). The effect of each surface treatment on the bond strength was determined by a shear bond test. RESULTS: Specimens that received surface treatment with a diamond bur exhibited higher shear bond strengths than any of the other repaired groups (p < 0.05). Those treated with air abrasion had the second highest shear bond strengths, but without a statistically significant difference when compared to the control group (p > 0.05). Specimens treated with phosphoric acid showed virtually no difference compared to the specimens of the control group (p > 0.05). CONCLUSION: Statistical analysis revealed that surface treatment with a diamond bur results in higher shear bond strength than other tested methods.

Abstract  PURPOSE: To investigate the effect of different light-curing units and adhesive systems on the bonding of leucite ceramic to dentin. MATERIALS AND METHODS: Flat dentin surfaces were ground occlusally on human molars (n = 60). Hot-pressed ceramic blocks of IPS Empress (Ivoclar-Vivadent) were fabricated, air-particle abraded, and cleaned in distilled water. Following acid etching and silane treatment of ceramic, bonding procedures were performed. The teeth were divided into two groups according to the type of the adhesive system: (1) total-etch: etchant (Etch 37) and adhesive (One Step Plus); (2) self-etching: self-priming etchant (Tyrian SPE) and adhesiveOne Step Plus) (n = 30). Ceramic blocks were bonded to the dentin surfaces with dual-polymerizing resin luting cement (Duolink). For polymerization, the QTH (Blue Swan Digital, Dentanet) was used in soft-up and high-power mode, the LED (Elipar Freelight 2, 3M Espe) in exponential and standard mode, and the PAC (PlasmaStar, SP-2000, Monitex) in normal and ramp-curing mode (n = 5). Following storage in distilled water for 24 h, the samples were thermocycled for 6000 cycles. The bonded specimens were serially sectioned and trimmed to hourglass shapes with approximately 1.6 +/- 0.16 mm2 cross-sectional areas, then tested with the microtensile tester at a rate of 1 mm/min. Fracture surfaces (were analyzed with SEM. The data were analyzed with three-way analysis of variance (ANOVA). RESULTS: ANOVA revealed that adhesive systems (p < 0.001) and light-curing units (p = 0.015) had a significant effect on bond strength values. Bond strength means (+/- SD) in MPa were as follows: total-etch system: QTH/soft-up mode = 16.2 (5.4); QTH/high power mode = 15 (5.4); LED/standard mode = 12.1 (3.3); LED/exponential mode = 15 (5); PAC/normal mode = 19.3 (7); PAC/ramp-curing mode = 19.6 (7.4). Self-etching system: QTH/soft-up mode = 9.9 (2.1); QTH/high-power mode = 12.5 (4.3); LED/standard mode = 8.6 (2); LED/exponential mode = 13 (3.8); PAC/normal mode = 13.1 (3.9); PAC/ramp-curing mode = 8.9 (2.2). CONCLUSION: Results indicated that the conventional total-etch system provided more reliable bonding compared to the self-etching system. The PAC light-curing unit together with the total-etch adhesive system showed the highest mean micro-TBS values with either normal mode or ramp-curing mode.

Abstract  Nanophase nc-Si/a-SiC films that contain Si quantum dots (QDs) embedded in an amorphous SiC matrix were deposited on single-crystal silicon substrates using inductively coupled plasma-assisted chemical vapor deposition from the reactive silane and methane precursor gases diluted with hydrogen at a substrate temperature of 200 degrees C. The effect of the hydrogen dilution ratio X (X is defined as the flow rate ratio of hydrogen-to-silane plus methane gases), ranging from 0 to 10.0, on the morphological, structural, and compositional properties of the deposited films, is extensively and systematically studied by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier-transform infrared absorption spectroscopy, and X-ray photoelectron spectroscopy. Effective nanophase segregation at a low hydrogen dilution ratio of 4.0 leads to the formation of highly uniform Si QDs embedded in the amorphous SiC matrix. It is also shown that with the increase of X, the crystallinity degree and the crystallite size increase while the carbon content and the growth rate decrease. The obtained experimental results are explained in terms of the effect of hydrogen dilution on the nucleation and growth processes of the Si QDs in the high-density plasmas. These results are highly relevant to the development of next-generation photovoltaic solar cells, light-emitting diodes, thin-film transistors, and other applications.

Abstract  This study reports the biosorption of Cr(VI) by chemically modified biomass of Rhizopus nigricans and the possible mechanism of Cr complexation to the adsorbent. The cell wall of this fungus possesses strong complexing property to effectively remove Cr(VI) anions from solution and wastewater. The mechanism of Cr adsorption by R. nigricans was ascertained by chemical modifications of the dead biomass followed by FTIR spectroscopic analysis of the cell wall constituents. Treatment of the biosorbent with mild alkalies (0.01 N NaOH and ammonia solution) and formaldehyde (10%, w/v) deteriorated the biosorption efficiency. However, extraction of the biomass powder in acids (0.1 N HCl and H2SO4), alcohols (50% v/v, CH3OH and C2H5OH) and acetone (50%, v/v) improved the Cr uptake capacity. Reaction of the cell wall amino groups with acetic anhydride reduced the biosorption potential drastically. Blocking of the-COOH groups by treatment with water soluble carbodiimide also resulted in initial lag in Cr binding. Biomass modification experiments conducted using Cetyl Trimethyl Ammonium Bromide (CTAB), Polyethylenimine (PEI), and Amino Propyl Trimethoxy Silane (APTS) improved the biosorption efficiency to exceptionally high levels. The FTIR spectroscopic analysis of the native, Cr bound and the other types of chemically modified biomass indicated the involvement of amino groups of Rhizopus cell wall in Cr binding. The adsorption data of the native and the most effectively modified biomass were evaluated by the Freundlich and the Langmuir adsorption isotherms and the possible adsorption phenomena are also discussed.

Abstract  A rapid vacuum-driven procedure, using pre-treated Sep-Pak C18 cartridges, has been developed for the simultaneous extraction of arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) from plasma. Non-specific interference was removed by fractional elution with an aqueous methanol/trifluoroacetic acid (TFA) mixture. AVP and ANP were coeluted under positive pressure with a methanol/TFA mixture and the eluates air-dried before measurement using separate radioimmunoassays. Assay ranges for AVP and ANP were 0.12-29.5 pmol/L and 0.65-162 pmol/L, respectively, with mean recoveries (standard deviation in parentheses) for AVP of 96.4% (5.5%) at a level of 11.8 pmol/L and for ANP of 94.8% (5.9%) at a level of 32.4 pmol/L. The extraction and assay procedures were validated by observing the changes in plasma AVP and ANP concentrations in normal subjects at different stages of hydration and in elderly patients during treatment for congestive cardiac failure.

Abstract  Hydrophobic organo-silane based monolithic capillary columns were prepared by thermally initiated free radical polymerisation within the confines of 200 microm i.d. fused silica capillaries. A novel crosslinker, namely bis(p-vinylbenzyl)dimethylsilane (BVBDMS), was copolymerised with p-methylstyrene (MS) in the presence of 2-propanol and toluene, using alpha,alpha'-azoisobutyronitrile (AIBN) as initiator. Monolithic capillary columns, differing in the total monomer, microporogen content and microporogen nature were fabricated and the chromatographic efficiency of each monolith, regarding the separation of proteins, peptides and oligonucleotides, was evaluated and compared. Changes in monolith morphology were monitored by scanning electron microscopy (SEM). Porosity and specific surface areas of the supports were studied by means of mercury intrusion porosimetry and BET measurements, respectively. Pressure drop vs. flow rate measurements proved the prepared poly(p-methylstyrene-co-bis(p-vinylbenzyl)dimethylsilane) (MS/BVBDMS) monoliths to be mechanically stable and swelling propensity (SP) factors of 0.78-1.10 indicate high crosslinking homogeneity.

Abstract  A novel thin-film nanocomposite (TFN) nanofiltration membrane has been developed via interfacial incorporation of aminosilanized TiO2 nanoparticles. Polyethersulfone (PES) barrier coating on a porous alpha -Al2O3 ceramic hollow fibre membrane was employed as the substrate layer. TiO2 nanoparticles were incorporated in pure and functionalized forms into trimesoyl chloride (TMC) organic phase and m-phenylenediamine (m-PDA) aqueous phase, respectively. The surface functionalization of TiO2 nanoparticle was confirmed by XRD, FTIR and UV-vis reflectance spectral analysis. Surface properties of the fabricated composite membranes were investigated using SEM, EDX, AFM and contact angle goniometry. Heat resistibility of polyamide layers were examined using thermo-gravimetric analysis (TGA). Membranes intrinsic properties such as: the permeability, selectivity and pore size determination were also elucidated. The silane coupling agent containing amino-functional groups reinforced TiO2 nano fillers for the good dispersion inside the polyamide skin layer by reducing their surface energy. At ultra-low concentration (0.005wt.%), the functionalized TiO2 nanoparticles improved the salt rejection to 54% as well as water flux to 12.3l/m2h. By incorporating a higher concentration of TiO2 nanoparticles, water flux was increased up to 2-fold compared with the pure polyamide membrane with negligible rejection loss. These results demonstrated competency of using functionalized inorganic nanoparticles to increase the product flux and the separation efficiency.

Abstract  A quantification method was developed for the two basic impurities, one of which is also a metabolite, of Nicergoline (NIC), by using reversed-phase high performance liquid chromatography (RP-HPLC) and diode array detector (DAD). One of these compounds,10-methoxy-6-methylergoline-8beta-methanol-5-bromo-3-pyridinecarboxylate (1-DN) is the metabolite as well as the impurity whereas, the other 10-methoxy-1,6-dimethylergoline-8beta-methanol-5-chloro-3-pyridinecarboxylate (5-CN) is only an impurity. The chromatographic column was Phenomenex, Luna, 5 microm, C18 (2), 250 mm x 4.6 mm. Mobile phase was 0.1 M ammonium acetate (NH4Ac) solution containing 4 mM 1-octanesulfonicacid sodium salt (OSASS) and 6 mM tetrabutylammonium hydrogen sulphate (TBAHS) (pH: 5.9)/acetonitrile (ACN) (62:38) for 1-DN and (64:36) for 5-CN. Flow rate was 1.0 mL min-1. The diode array detector was operated at 285 nm, band width: 4 nm. Linearity was obtained in the concentration range of 0.032 x 10-5 to 3.828 x 10-5 M, y = 116.88x + 0.2773 (r2 = 0.99989); the limit of detection (LOD) and limit of quantification (LOQ) were determined as 0.012 x 10-5 and 0.041 x 10-5 M for 1-DN, respectively. Linearity was obtained in the concentration range of 0.034 x 10-5 to 4.092 x 10-5 M, y = 104.24x + 0.7486 (r2 = 0.99996); (LOD) and (LOQ) were determined as 0.014 x 10-5 and 0.046 x 10-5 M for 5-CN, respectively. The recovery was 100.65% for 1-DN and 100.32% for 5-CN. The amount of 1-DN in 30 mg NIC was found as 209.65 microg (0.70%) and the amount of 5-CN in 30 mg NIC was found as 27.62 microg (0.09%).

Abstract  Starting from 2-(triphenylsilyl)ethanol a new oxycarbonyl protecting group cleavable by fluoride ion induced Peterson-elimination has been developed. Known 2-(triphenylsilyl)ethanol has been prepared from commercially available triphenylvinyl-silane by a hydroboration-oxidation sequence using the sterically hindered borane reagent 9-BBN. The silyl alcohol was subsequently transformed into its chloroformate, imidazolylcarboxylic acid ester and p-nitrophenyl carbonate and used in standard protocols for the formation of carbamates and carbonates. The Tpseoc group proved to be highly resistant against acidic conditions applied in removal of tert-butyl esters and the t-Boc-group. It also withstood catalytic hydrogenation, treatment with morpholine, methylhydrazine and Pd-reagents/allyl-scavanger combinations, conditions required to cleave Cbz-, Fmoc-, phthalimide- and Alloc-groups. The Tpseoc-group is cleaved upon treatment with TBAF/CsF at 0 °C or r.t. with cleavage times reaching from.

Abstract  Ligand-stabilized copper(I)-hydride catalyzes the dehydrogenative Si-O coupling of alcohols and silanes-a process that was found to proceed without racemization at the silicon atom if asymmetrically substituted. The present investigation starts from this pivotal observation since silicon-stereogenic silanes are thereby suitable for the reagent-controlled kinetic resolution of racemic alcohols, in which asymmetry at the silicon atom enables discrimination of enantiomeric alcohols. In this full account, we summarize our efforts to systematically examine this unusual strategy of diastereoselective alcohol silylation. Ligand (sufficient reactivity with moderately electron-rich monophosphines), silane (reasonable diastereocontrol with cyclic silanes having a distinct substitution pattern) as well as substrate identification (chelating donor as a requirement) are introductorily described. With these basic data at hand, the substrate scope was defined employing enantiomerically enriched tert-butyl-substituted 1-silatetraline and highly reactive 1-silaindane. The synthetic part is complemented by the determination of the stereochemical course at the silicon atom in the Si-O coupling step followed by its quantum-chemical analysis thus providing a solid mechanistic picture of this remarkable transformation.

Abstract  To isolate the anti-inflammatory components in Siegesbeckia pubescens root, we performed activity-guided fractionation using a carrageenan-induced edema rat model. Antinociceptive effects were followed using acetic acid-induced abdominal constriction and hot plate tests in mice. Chloroform extract was subjected to silica gel and octadesyl silane (ODS) column chromatography, and a diterpene was isolated which was identified as ent-16alphaH,17-hydroxy-kauran-19-oic acid (siegeskaurolic acid). Pretreatment with siegeskaurolic acid (20 or 30 mg/kg/day, p.o.) exhibited anti-inflammatory and antinociceptive effects in these animal models. To investigate the mechanisms underlying this anti-inflammatory action, we investigated the effect of siegeskaurolic acid on lipopolysaccharide (LPS)-induced responses in a murine macrophage cell line, RAW 264.7. Siegeskaurolic acid was found to significantly inhibit the productions of nitric oxide (NO), prostaglandin E(2) (PGE(2)), and tumor necrosis factor-alpha (TNF-alpha). Consistent with these findings, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins, and iNOS, COX-2, and TNF-alpha mRNAs were found to be inhibited by siegeskaurolic acid. Furthermore, siegeskaurolic acid inhibited the nuclear factor-kappaB (NF-kappaB) activation induced by LPS, and this was associated with the prevention of inhibitor kappaB degradation (I kappaB), and subsequently with decreased nuclear p65 and p50 protein levels. Taken together, our data indicate that the anti-inflammatory and antinociceptive properties of siegeskaurolic acid may be due to iNOS, COX-2 and TNF-alpha inhibition via the down-regulation of NF-kappaB binding activity.

Abstract  We demonstrate the synthesis and characterization of star-shaped crystalline-coil block copolymers with four arms consisting of an inner block of poly(ethylene oxide) and an outer semicrystalline compartment of poly(ferrocenyldimethylsilane), [PEO(50) -b-PFDMS(35)](4). The materials were synthesized by transition-metal-catalyzed ring-opening polymerization of dimethylsila[1]ferrocenophane in the presence of silane-functionalized four-arm PEO stars as macroinitiators and they exhibited a moderate polydispersity (PDI≅1.4). Self-assembly in mixtures of THF and different alcohols as selective solvents for the PEO block resulted in the formation of semicrystalline vesicles (ethanol, 1-butanol) or large, rather ill-defined, spherical structures (methanol). Further, both the rate of addition of the selective co-solvent and the overall solvent/non-solvent ratio drastically affected the size and stability of the self-assembled particles. We could also show that a photoacid generator, as a model for an active substance, can be encapsulated and the UV-induced generation of HCl resulted in a straightforward degradation of the organometallic vesicles.

Abstract  For the purpose of the development of a new recycling technique of thermosetting silane-crosslinked polyethylene (silane-XLPE) turned into thermoplastic polyethylene, the optimum conditions are determined to decompose crosslinking points consisting of siloxane bonds, while keeping the main chain consisting of carbon-carbon bonds in silane-XLPE using supercritical alcohols. As a result, more than 90% of the siloxane bonds are broken selectively and rapidly without the destruction of the main chain and silane-XLPE is converted to thermoplastic polyethylene using supercritical primary alcohols such as methanol at 320-360 degree C, 10 MPa in 20 min. On the other hand, in the case of supercritical secondary alcohol such as iso- propanol, around two thirds of the siloxane bonds did not decompose even at the high temperature region above 350 degree C. This is because it was difficult for bulky secondary alcohol to approach the crosslinking points inside the polymer. The reaction rates are measured for the decomposition of the crosslinking points with supercritical methanol and n-propanol. They are expressed by the first-order as well as the second-order reaction models well, because the alcohol concentration is much higher than that of the crosslinking points and can be considered to be constant during the reaction. Arrhenius plots of the second-order rate constants lay well on straight lines for both alcohols and the activation energies are 21.7 kJ/mol for supercritical methanol and 66.5 kJ/mol for supercritical n-propanol.

Abstract  A new preparation method of 3,5-dinitrobenzoyl-bonded silica gel stationary phase (DNB) for high performance liquid chromatography has been developed by using N-(beta-aminoethyl)-gamma-aminopropyl-methyldimethoxy silane as coupling reagent. Its structure was characterized by elemental analysis, diffuse reflectance Fourier transform infrared spectroscopy and thermal analysis. The surface concentration of 3,5-dinitrobenzoyl ligand was 2.08 micromol/m2 according to the carbon content from elemental analysis. The chromatographic performance of the new packing was evaluated by using different solute probes, such as polycyclic aromatic hydrocarbons (PAHs), phenols, naphthalene derivatives, nitrophenol positional isomers and sulfonamides. The results show that comparing with ODS, DNB has weaker hydrophobicity and more versatile chromatographic properties. The charge-transfer between the dinitrobenzoyl ligand and the analytes plays a significant role in the separation of phenols and naphthalene derivatives. In addition, static electric, hydrogen-bonding and dipole-dipole interactions are responsible for the above separations and improve the selectivity of DNB for solutes. An advantage of DNB is that it is suitable for the separation of the basic compounds containing nitrogen atoms without capped process because the spacer containing nitrogen atoms can shield the residual silanols on DNB.

Abstract  PURPOSE: Despite the undeniable potential of cell adhesion molecules such as fibronectin to support osteogenic cell responses and consecutive dental implant healing, the most beneficial mode of application onto titanium implant surfaces still requires investigation. Unspecific fibronectin adsorption on titanium dioxide (TiO(2)) surfaces can result in low-loading, high-desorption rates and protein-metal interactions with impaired biologic activity. The aim of the present study was to monitor the osteogenic cell responses (cell adhesion, proliferation, and differentiation) specifically to fibronectin biofunctionalized TiO(2).

MATERIALS AND METHODS: An innovative biomimetic streptavidin-biotin layer system allows flexible, but stable, specific binding of biotinylated biomolecules such as fibronectin on TiO(2) surfaces. Transparent glass disks were sputtered with TiO(2). The biomimetic layer system was immobilized by self-assembly and consisted of silane, biotin-derivate, streptavidin, and biotinylated fibronectin (bFN). For the control group, unbiotinylated fibronectin was directly coated onto TiO(2). Early cell adhesion dynamics were quantified using automated processing of light microscopy images within the first 24 hours. Relative mRNA expression of integrin-β1, cyclin D1, runt-related gene 2, alkaline phosphatase, and osteocalcin was obtained using quantitative real-time polymerase chain reactions 3 and 7 days after incubation.

RESULTS: Although untreated TiO(2) preserved a rather immature osteogenic phenotype, both unbiotinylated fibronectin and bFN promoted osteogenic cell adhesion and cell differentiation. In particular, runt-related gene 2 expression was significantly promoted by bFN after 3 days. In contrast, cyclin D1 expression was decreased for unbiotinylated fibronectin and bFN after 7 days.

CONCLUSIONS: The introduced biomimetic layer system contributes a coherent immobilization approach of adhesion molecules with promotion of osteogenic cell response in vitro.

Abstract  A walk through survey of the Hewlett Packard Company (SIC-3674) facility in San Jose, California, was prompted by an interest in the use of gallium-arsenide (1303000) as an alternative to silicon for the semiconductor industry. This facility produced gallium-arsenide and gallium-phosphide (12063988). Potential hazards existed from solvents, acids, and gases employed in wafer production. Some of the solvents included fluorocarbon compounds, xylene (1330207), and 1,1,1-trichloroethane (25323891). Arsine (7784421), phosphine (7803512), hydrogen (1333740), and silane (7803625) gases were used in the production processes. In the crystal growing area, operators wore smocks, disposable gloves and safety glasses. Disposable respirators were no longer required during cleaning of the crystal pullers. However, supplied air lines were required during the gas cylinder change operation. Self contained breathing apparatus was available for emergency situations. Worker exposures to gallium-arsenide or arsenic (7440382) dust were lower during the cleaning operation than they had been in other similar facilities, perhaps due to the small size of the crystal pullers used at this particular facility. According to the author, this facility is a possible candidate for an in depth industry survey, but may not be representative of the entire industry.

Abstract  A walk through survey evaluated technology available for control of hazardous substances resulting from gallium-arsenide (1303000) (GA) use, especially GA dusts, in semiconductor production at the Raytheon Company, Northborough, Massachusetts. The OSHA standard was 10 micrograms per cubic meter for arsenic. Potential hazards identified included solvent, acid, and gas exposure in production of GA wafers and radio frequency exposure during metallization. In the event of droppage of arsenic-trichloride (7784341), ventilation would shut down, leaving exhaust operational. Leakage in silane (7803625) and hydrogen (1333740) carrying piping would be a fire and explosion hazard. Interlocks were planned for the radio frequency sputterer. Other engineering controls were directed at ventilation, exhaust, and laminar air flow in relevant operations. Safe work practices included aqua-regia (8007565) preparation while most staff were absent, and carrying arsenic-trichloride ampules in plastic containers. Routine air monitoring was not done by the company, but previous personal samples in the epitaxy area did not show detectable levels of arsenic (7440382) or arsine (7784421). A full time nurse was available on site, and safety glasses and polyvinyl-chloride gloves were used where relevant. Recommendations include a regular program of air and wipe sampling and protection of piping. The authors conclude that an in depth survey will probably not be necessary.

Abstract  OBJECTIVES: To determine the influence of titanium dioxide (TiO2) nanoparticle addition on the opalescence, color, translucency and fluorescence of experimental resin composites.

METHODS: A light curing resin matrix was made by mixing 60 wt.% Bis-GMA and 40 wt.% TEGDMA. Silane coated glass filler (mean particle size: 1.55 microm) was added in the ratio of 50 wt.% of the resin composites. A fluorescent whitening agent was also added (0.05 wt.%). TiO2 nanoparticles (<40 nm) were added with the concentrations of 0, 0.1, 0.25 and 0.5 wt.%. Reflected and transmitted colors of 1 and 2 mm thick specimens were measured relative to the illuminant D65 with reflection spectrophotometers. Opalescence parameter (OP), color difference (DeltaE*ab), translucency parameter (TP), fluorescence parameter (FL), and fluorescence and opalescence spectra were calculated.

RESULTS: For the 1 mm thick specimens measured with 3 mm x 8 mm rectangular aperture, when the concentration of TiO2 increased from 0% to 0.5%, OP increased from 2.4 to 18.0, TP decreased from 35.4 to 13.1, and fluorescence spectra remained unchanged. Color difference between these specimens was in the range of 3.4-6.6 DeltaE*ab units. OP values were significantly influenced by the thickness of the specimens and the configuration of the spectrophotometers (p<0.05).

SIGNIFICANCE: Addition of TiO2 nanoparticles significantly increased the opalescence of resin composites while leaving the fluorescence spectra unchanged; however, it significantly decreased the translucency and also changed the color (p<0.05). Resin composites with 0.1-0.25% TiO2 nanoparticle would simulate the opalescence of human enamel.