Glass Formation

The ability to form a glass, i.e., the ability to form bonds which lead to a vitreous network, appears periodically in the classification chart of the elements. Thus simple glasses containing only one kind of atom are formed by the elements of Group VI of the periodic table (O, S, Se, and Te). Only these elements are known to form monatomic (primary) glasses and they retain the ability to form a vitreous network when mixed or chemically bound to each other. The elements of Group VI also form binary glasses, i.e., glasses containing two kinds of atoms, with the elements of Groups III, IV, and V. Experimental evidence of the glassforming capacities of these elements and compounds is given; about twenty new glasses suggested by the foregoing were prepared in the author's laboratory. Binary glasses are also known to exist composed of an element of Group VII (F, Cl, I, or Br) and an element of one of Groups II, III, and IV or a transition element. Experimental evidence for these glasses is presented.     

The influence of retention hole and adhesive systems on the shear bond strengths of resin composite to amalgam

The aim of the study is to evaluate the influence of surface-treatment methods with and without the use of a retention hole on the shear bond strength of a resin composite adhered to amalgam using an adhesive system. Amalgam specimens were divided into six groups. Group 1 (Bur) specimens were roughened with a diamond bur, Group 2 (Al₂O₃) specimens were sandblasted with a 50?μm aluminum oxide powder, Group 3 (CoJet^®) specimens were sandblasted with 30?μm CoJet^® Sand, Group 4 (Bur?+?Rh) specimen surfaces were prepared with a retention hole 1?mm in diameter and 1?mm deep and roughened with a diamond bur, Group 5 (Al₂O₃?+?Rh) specimens were also prepared with a retention hole and sandblasted with 50?μm aluminum oxide powder, and Group 6 (CoJet^®?+?Rh) surfaces were prepared with a retention hole and sandblasted with 30?μm CoJet^® Sand. Resin composite cylinders were bonded onto the amalgam surfaces using Xeno^® IV, Optibond? All-In-One, Clearfil? SE Bond, Adper? Single Bond Plus, and Scotchbond? Multi-Purpose adhesive systems. In addition, silane (Monobond S) was used for Groups 5 and 6. The shear bond was determined and statistically analyzed using two-way analysis of variance and post hoc Tukey’s tests (p?≤?0.05). The surface treatment significantly affected the shear bond strengths of the adhesive systems. The shear bond strengths of Optibond? All-In-One (2.661?±?0.48?MPa) in Group 1 and Scotchbond Multi-Purpose (3.818?±?0.98) in Group 4 were significantly higher than those of the other adhesive systems. Silica coating of the amalgam surface significantly improved the shear bond strength of the resin composites. The addition of a retention hole on the amalgam affects the bonding strength of the composite adhesion.     

Incorporation of EGCG into an etch-and-rinse adhesive system: mechanical properties and bond strength to caries affected dentin

This study evaluated how a matrix metalloproteinase (MMP) inhibitor (EGCG) incorporated into an etch-and-rinse adhesive system (AS) affects the long-term microtensile bond strength (MTBS) to caries affected dentin (CAD) and flexural strength (FS) of AS. Forty CAD surfaces received acid conditioning and were randomly divided into four groups (n?=?10): EGCG-PRE – dentin treatment with 200?μg/mL EGCG solution; EGCG-INC – 200?μg/mL EGCG solution incorporated into SA; CHX-PRE – dentin treatment with 2% digluconate solution; NT – no treatment. The AS (Adper Single Bond 2, 3M ESPE) was applied and resin composite blocks were built on the dentin. Beam-shaped specimens (0.8?mm²) were obtained submitted to MTBS testing following 24?h, 6 months or 1 year of water storage (WS). Adhesive interface was analyzed by SEM. FS testing was performed by preparing specimens with the adhesive system, with or without the EGCG solution (200?μg/mL) (n?=?10). Tests were carried out in a universal machine (0.5?mm/min). MTBS data were submitted to two-way ANOVA and Tukey’s test, whereas FS data, to the Student’s t-test (α?=?0.05). MTBS values were not affected by EGCG application, either incorporated or used as a dentin treatment agent, regardless of the WS period; however, CHX negatively affected MTBS to CAD (p?<?0.001). WS significantly reduced MTBS values (p?<?0.001) from the 6-months time point. FS was not affected by EGCG incorporation into the SA (p?=?0.2527). EGCG incorporation into AS was unable to maintain bond stability to CAD over time, whereas it did not compromise adhesive’s property.     

Removal of Chromium(VI) and Chromium(III) from Aqueous Solution by Grainless Stalk of Corn

Abstract

Grainless stalk of corn (GLSC) was tested for removal of Cr(VI) and Cr(III) from aqueous solution at different pH, contact time, temperature, and chromium/adsorbent ratio. The results show that the optimum pH for removal of Cr(VI) is 0.84, while the optimum pH for removal of Cr(III) is 4.6. The adsorption processes of both Cr(VI) and Cr(III) onto GLSC were found to follow first-order kinetics. Values of k _ads of 0.037 and 0.018 min^?1 were obtained for Cr(VI) and Cr(III), respectively. The adsorption capacity of GLSC was calculated from the Langmuir isotherm as 7.1 mg g^?1 at pH 0.84 for Cr(VI), and as 7.3 mg g^?1 at pH 4.6 for Cr(III), at 20°C. At the optimum pH for Cr(VI) removal, Cr(VI) reduces to Cr(III). EPR spectroscopy shows the presence of Cr(V) + Cr(III)-bound-GLSC at short contact times and adsorbed Cr(III) as the final oxidation state of Cr(VI)-treated GLSC. The results indicate that, at pH ≈ 1, GLSC can completely remove Cr(VI) from aqueous solution through an adsorption-coupled reduction mechanism to yield adsorbed Cr(III) and the less toxic aqueous Cr(III), which can be further removed at pH 4.6.     

Raman spectroscopy of the polymorphic forms and liquid state of cocoa butter

Raman spectroscopy was used to characterize the polymorphs and liquid state of cocoa butter, with emphasis placed on the evolution of the ester carbonyl stretching region (1800–1700 cm^?1), along with complementary analysis and comparison of the Raman‐active C? C (1200–1000 cm^?1), C?C (1660 cm^?1), C? H (3000–2700 cm^?1) and CH₂ (1500–1250 cm^?1) vibrational modes. Unique Raman signatures were obtained for all cocoa butter polymorphs, with their identity confirmed using DSC and XRD. The ester carbonyl region permitted polymorph discrimination due to differences in the number of modes, their relative frequencies and their full‐widths at half‐maximum. The C? C stretching modes, which provided insight into the trans/gauche content, were polymorph‐independent. C? H stretching generally increased with polymorph stability, indicating the dominance of antisymmetric C? H methylene vibrations as the cocoa butter crystal lattice became more ordered. The change in the intensities of the C? H stretching bands used to probe the order–disorder transition of forms IV, V and VI hinted at pre‐melt structural changes mostly in forms IV and V. Overall, Raman spectroscopy clearly demonstrated that the different functional groups studied could be characterized independently, allowing for the understanding of their role in cocoa butter polymorphism. Practical applications : Fat bloom is the unwanted, uncontrolled re‐crystallization or polymorphic transition of CB form V crystals into form VI normally caused by the migration of lower‐melting fats (e.g. in centre‐filled products) and/or temperature fluctuations during storage. In its mildest form, it appears as an overall dulling of the chocolate surface. In its extreme form, the appearance of the chocolate deteriorates significantly with the development of distinct white patches. Though forms V and VI can be clearly distinguished via XRD, we present evidence that Raman spectral characterization of the ester carbonyl stretching (1800–1700 cm^?1), C? C (1200–1000 cm^?1), C?C (1660 cm^?1), C? H (3000–2700 cm^?1) and CH₂ (1500–1250 cm^?1) vibrational modes yields distinct liquid–solid and polymorph‐dependent differences in CB. From a practical standpoint, the unique signatures associated with forms V and VI offer novel possibilities in the study of fat bloom formation, such as the development of predictive tools.     

Odor similarity between stress-inducing odorants in wistar rats

Odor similarity to the odor of 4-mercapto-4-methyl-2-pentanone (I) was measured on eight rats by generalization of a conditioned avoidance response tocis- andtrans-8-mercapto-p-menthan-3-one (II and III), 3-mercapto-3-methyl-2-pentanone (V), andt-amyl mercaptan (VI). Previously, these odorants had been found to induce stress in rats in an open-field situation. In the present experiment, rats generalized the avoidance response learned with I, for V, VI, and to a lesser extenttrans-isomer III, implying odor similarities;cis isomer II was discriminated. Odor similarity between mercapto ketone I and mercaptan VI is surprising since VI lacks the keto group.     

Formaldehyde and VOCs emissions from bio-particleboards

Formaldehyde and other volatile organic compounds (VOCs) emissions were determined from particleboards manufactured with natural adhesives. Thus, mimosa tannin with hexamine solution (T) and a blending of glyoxalated wheat straw lignin solution mixing with mimosa tannin and hexamine (TL) in 50/50 proportion were used as resins. These ones were compared with a traditional synthetic urea formaldehyde (UF) adhesive. Formaldehyde and other VOCs were determined and quantified with high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS) methods. Formaldehyde, acetaldehyde, acetone/acroleine and hexanaldehyde were the main compounds detected by HPLC. Toluene, ethylbenzene, xylene and following terpenes: α-pinene, β-pinene, 3-carene and limonene were determined by GC–MS. Results were obtained according to the EN-16000. After three days, emission results were the following: (a) formaldehyde UF: 240?>?T:66?>?TL:34?μg/m²?h; (b) acetaldehyde TL:46?>?T:40?>?UF:29?μg/m²?h; (c) acetone/acroleine TL:53.9?>?UF:39.5?>?29.3?μg/m²?h; (d) hexanaldehyde T:14.6?>?TL:13.7?>?UF:11.7?μg/m²?h; (e) toluene UF:19.4?>?TL and T: 9.4?μg/m²?h; (f) ethylbenzene UF:17.4?>?TL and T: 7.6?μg/m²?h; (g) m-xylene UF 69.11?>?TL and T 26.6?μg/m²?h; (h) o-xylene UF:16.0?>?TL and T: 5.6?μg/m²?h; and (i) terpenes were emitted with lower rate than all the other compounds. In general, higher emissions have been noticed in natural adhesives than in the UF. Thus, the main terpenes found were α-pinene: UF:8.5?<?TL:14.8?<?T:19.7; β-pinene: UF:1.8?<?TL:2.6?<?T:3.6 and 3-carene UF:3.6?<?TL and T: 4.9. Concerning limonene, no difference was observed whether the used adhesive was natural or not.     

Adhesion of resin cement to contemporary hybrid ceramic and polymeric CAD/CAM materials: effect of conditioning methods and ageing

This study assessed the effect of different surface conditioning methods and ageing protocols on adhesion of resin cement to hybrid ceramic and polymeric CAD/CAM materials. CAD/CAM materials (n?=?360, n?=?30 per group), namely (a) Lithium disilicate (IPS e.max CAD-LIS), (b) Zirconia (IPS e.max ZirCAD-ZIR), (c) Polymer (Lava Ultimate-LAV), (d) Polymer infiltrated ceramic network (Enamic-ENA), (e) Polymer infiltrated ceramic (Experimental-1-CS1), (f) Polymer infiltrated ceramic (Experimental-2-CS2), (g) Lithium disilicate reinforced alumina (n!ce-NIC) were cut into slices (3?×?6 × 8?mm³) and conditioned: (a) Method 1: 5% hydrofluoric acid etching (H)+silane and (b) Method 2: Silica coating (CoJet (A)+silane). Group LIS was conditioned with only Method 1 and Group ZIR only with Method 2 (control). Resin cement (Variolink Esthetic II) was bonded onto the conditioned specimens and photopolymerized. One-half of the specimens was subjected to ageing (thermocycling 5–55°, 5000 cycles) and the other half was stored in distilled water (37?°C, 24?h). The resin-substrate interface was loaded under shear forces in a Universal Testing Machine (1?mm/min). Data (MPa) were analyzed using two-way ANOVA and Tukey`s tests (α?=?0.05). Substrate type, conditioning method and ageing had a significant effect on adhesion values (p?<?.05). In aged conditions, ENA-H, ENA-A, LAV-H, LAV-A, CS2-A (15?±?4 – 11.6?±?5) showed no significant difference (p?>?.05), with the CS2-A (15?±?4) showing the least reduction (5.5%) compared to all other groups (5.8–62.6%). CS1-A (100%) followed by ENA-H, ENA-A (93%), CS2-A (80%) presented the highest incidence of cohesive failures after ageing.     

Adhesion of bulk-fill resin composites as core and intraradicular post materials only versus the use of glass-fiber posts in different regions of root dentin

This study assessed adhesion of bulk-fill resin-composites as core and post materials only versus the use of fiber resin composite (FRC) posts. Human teeth (N?=?84) were cut at the CEJ and endodontically treated and randomly divided into seven groups: TP: Titanium post (Flat Head T); SFRC: S2-glass FRC (Pinpost); EFRC1: E-glass FRC (GC Everstick) directly bonded; GFRC: E-glass FRC (Glassix Nordin); EFRC2: E-glass FRC (Everstick); BF1: Bulk-fill resin (Surefill SDR); BF2: Bulk-fill resin (SonicFill). Groups TP, SFRC, EFRC and GFRC were cemented (Panavia 21), while other groups were bonded directly to the intraradicular dentin. The core parts were constructed using a resin composite (G-aenial) except for Groups BF1 and BF2. The core-cervical dentin interface was loaded under shear forces. Push-out tests were performed in a Universal Testing Machine (1?mm/min). Data (MPa) were analyzed using two-way ANOVA and Tukey`s tests (α?=?0.05). Not the root level (p?>?0.05) but the type of core and post material significantly affected shear and push-out bond results (p?<?0.001). BF1 (9.2?±?2.1) and BF2 (9.3?±?3.1) showed significantly lower bond strength to the cervical dentin (p?<?0.05) compared to other groups (11.6?±?2.5–19?±?6.8). FRC post types did not show significant difference being higher than those of TP, BF1 and BF2 (0.57?±?0.37–2.34?±?1.98) (p?>?0.05). Partial cohesive core fracture was more common while BF1 and BF2 showed exclusively adhesive failures. Cohesive failure in the cement was frequent in Group TP (53%) compared to other groups (3–24%). BF1 and BF2 presented exclusively complete adhesive failure of the bulk-fill material.     

Preparation,characterization and application of iron (III)-loaded chitosan hollow fiber membranes as a new bio-based As (V) sorbent

Fe (III)-loaded chitosan (CS) hollow fibers (CS-Fe (III) HF) were successfully prepared according to the dry-wet spinning technique. The CS-Fe (III) HFs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). Removal of pentavalent arsenic was studied through biosorption on CS-Fe (III) HF adsorptive membranes. The response surface methodology (RSM) was applied to investigate the influence of the main operating parameters such as contact time, pH, initial As (V) concentration and HFs dosage on the adsorption capacity of As (V). From the Pareto analysis, pH, [As (V)]_o, [CS-Fe (III) HF membranes] and squared effect of [As(V)]_o were found to produce the largest effect on biosorption of As (V). Kinetic studies showed that the pseudo-second-order kinetic model provides the best correlation to the experimental results. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 3,703 μg g^?1. A laboratory scale glass membrane module consisting of three CS-Fe(III) HFs has also been prepared and tested for biosorption of As (V) at a real scale. Permeability of As (V) ions through the CS-Fe (III) HF membranes was 0.145 μmol m^?2 h^?1 bar ^?1.     

Fatigue and fracture resistance of minimally invasive ceramic and resin composite veneers with different designs bonded adhesively to severely eroded teeth

This study evaluated the load bearing capacity of minimal invasive restoration alternatives on severely worn teeth after cyclic loading. Sound human maxillary incisors (N?=?72, n?=?9 per group) were randomly divided into nine experimental groups to receive one of the following restoration types: Group 1: Intact tooth, Group 2: Direct resin composite, Group 3: Lingual: Indirect resin composite, Labial: Ceramic veneer with lingual overlap, Group 4: Lingual: Indirect resin composite with lingual overlap, Labial: Ceramic, Group 5: Lingual: Direct composite, Labial: Ceramic, Group 6: Lingual: Feldspathic Ceramic, Labial: Feldspathic ceramic, Group 7: Lithium disilicate crown, Group 8: Metal-ceramic crown. Teeth were prepared simulating erosion/wear conditions. Specimens were subjected to cyclic loading (1,200,000 cycles, 5–55?°C) and then loaded to failure from the lingual surface at 105° inclination (1?mm/min). Data (Newton) were analyzed using one-way ANOVA, Tukey`s tests and Weibull moduli were calculated (α?=?0.05). Significant differences were observed between the groups for the initial (p?=?0.006) and maximum fracture load (p?=?0.002). Group 3 (55?±?36) presented significantly lower initial fracture load compared to other groups (79?±?35–134?±?36) (p?<?0.05). When maximum fracture load is considered, control group (1) (602?±?355) and from restored groups 2 (449?±?144) and 4 (495?±?291) showed significantly higher results (p?<?0.05). Weibull modulus for the maximum fracture load was the highest for Group 2 (m?=?3.47) among all groups (m?=?1.61–4.18). Groups 2, 3, 6 presented the highest incidence of repairable failures. Based on the results, severely worn teeth could be restored with lingual direct resin composite and labial veneering with indirect resin with overlap.     

Evaluation of the effects of surface treatments on the cathodic delamination and anticorrosion performance of an epoxy-nanocomposite on steel substrate

The St-37 type steel substrates were pretreated with Cr(VI) and Cr(III) conversion coatings where the latter was then post-treated with Co(II) and Ni(II) chemical treatments. The epoxy coatings containing 3.5 wt% nano-sized ZnO particles were applied over the chemically treated steel samples. The corrosion resistance of the samples was studied by a DC polarization technique. A scanning electron microscope (SEM) was utilized to investigate the morphology of the pretreated and post-treated samples. Electrochemical impedance spectroscopy (EIS) was utilized to investigate the corrosion resistance of the epoxy nanocomposites for different immersion times in 3.5 wt% NaCl solution. The adhesion strengths of the coatings were measured before and after 120 days of immersion in the corrosive electrolyte using a pull-off test. The cathodic delamination (CD) of the painted samples was also investigated. Results showed that conversion coatings can significantly increase the corrosion resistance and adhesion strength of the epoxy coating on the steel, and also reduce the rate of CD in comparison with an untreated sample. The adhesion strength and corrosion resistance of the epoxy coating on the Cr(III) pretreated samples were significantly greater than on the Cr(VI) sample. The increase in adhesion strength and corrosion resistance was more pronounced on the samples that were post-treated with Co(II) and Ni(II) chemical treatments. The cathodic disbonded areas of the Cr(III)–Co(II) and Cr(III)–Ni(II) post-treated samples were significantly lower than the Cr(III) and Cr(VI) pretreated samples. Results showed that Cr(III)-based conversion coatings can improve the anticorrosion performance and reduce CD compared with those with Cr(VI).     

Vibrating screen printed electrode of gold nanoparticle-modified carbon nanotubes for the determination of arsenic(III)

A linear sweep anodic stripping voltammetric method using a carbon nanotube–gold nanoparticle-modified vibrating screen printed electrode for the determination of arsenic(III) is reported. The experiments were conducted with a 0.1 mol L^?1 solution of H₂SO₄ in order to estimate the electrode area related to gold oxide formation. The results showed a clear reduction peak at approximately +0.85 V corresponding to the reduction of the gold surface oxide with a superficial area of 0.089 cm². A vibrating motor was attached to the screen printed electrode to create a portable and autonomous system with enhanced mass transfer. The repeatability of the measurements was 2.4 % (n = 10) at the level of 0.5 mg L^?1 of arsenic(III) under the best instrumental operating conditions. The peak current was linearly dependent on the arsenic(III) concentration, thus allowing the construction of a linear analytical curve in the range from 10 to 550 μg L^?1 with the equation: ?I_p (μA) = 0.05 + 134.59 [As(III) (μg L^?1)], R² = 0.99. The obtained detection and quantification limits were 0.5 (3 SD) and 1.5 (10 SD) μg L^?1, respectively, using 120 s as the deposition time. It was shown that Cu(II) does not interfere in the detection of As(III) using the proposed method.     

The Effect of Different Polishing Sequences on the Adhesion of Streptococcus mutans to Feldspathic Porcelain

The aim of this research was to determine whether extra-oral surface treatments on feldspathic porcelain surfaces influence initial adhesion of Streptococcus mutans. Ninety-six porcelain specimen discs were fabricated and divided into six equal groups according to surface treatment: fine-grit diamond polishing (Group 1); self-glazing (Group 2); overglazing (Group 3); overglazing followed by a finishing procedure and then overglazing (Group 4); Pearl Surface polishing (Group 5); and Diamond Twist SCL^TM polishing (Group 6). Surface roughness and hydrophobicity were assessed. An S. mutans suspension was incubated on each specimen group and evaluated. A one-way analysis of variance, post-hoc Tukey honestly significantly different test, Friedman test, and t-test were used for statistical analysis. Group 1 showed the highest surface roughness (p < 0.001) and bacterial adhesion (p < 0.05). Groups 5 and 6 specimen surfaces presented significantly higher contact angles (p < 0.05). Group 1 had the highest S. mutans adhesion, followed by Groups 3, 5, 6, 2, and 4 (p < 0.05). Reglazing after grinding may therefore decrease bacterial adhesion beneficially.     

Adsorptive removal of hexavalent chromium using sawdust: Enhancement of biosorption and bioreduction

Simultaneous biosorption and bioreduction experienced by Cr(VI) species were initially validated by mixing 500 µM of Cr(VI) with 0.20 g of sawdust biosorbent. Accordingly, a complete disappearance of Cr(VI) species with emergence of 25% of Cr(III) ions was recorded; evidencing that both processes transpired simultaneously. An increase in the initial Cr(VI) concentration to 1500 µM could further induce more reduced Cr(VI) concentration. The enhancement of Cr(VI) biosorption and bioreduction was found to occur upon increasing the sawdust dosage to 4 g L^?1 and decreasing the solution pH to 2. However, the presence of a Zn(II) co-pollutant at 2500 µM had deteriorated the removal of Cr(VI) species.     

Investigation of low-pressure adhesion performance of mushroom shaped biomimetic dry adhesives

The effectiveness of biomimetic dry adhesives at different ambient pressures was investigated. Biomimetic dry adhesives have great potential for space applications but there have been few studies on how these adhesives perform in low-pressure environments. The best performing geometry for dry adhesives with respect to normal adhesion has previously been determined to be mushroom shaped fibers, but the pressure sensitivity of these designs has been unclear – with some groups reporting pressure dependent adhesion, and others claiming no effect. We have compared the microscale adhesion of mushroom shaped polymer fibers at different ambient pressures and have determined that suction cup effects are negligible for fibers with caps less than 16.4?μm in diameter. Further investigation in this work showed that a simple suction cup model provided estimates for the geometry requirements for a non-negligible suction cup effect and determined that the minimum cap radius for the 10?μm pillar diameter used in this study should be over 26?μm – past the dimension that can be successfully fabricated using this technology.     

Effect of different air-abrasion protocols on topography,surface wettability and adhesion of MDP monomer-based resin cement to zirconia

This study evaluated the effect of air-abrasion protocols on the topography, surface wettability and adhesion of resin cement to zirconia. Ceramic specimens (N?=?49; n?=?7) (15?mm × 2?mm) were randomly allocated to seven groups to be treated with: (1) Air-abrasion with 45?μm Al₂O₃ (A45), (2) 80?μm Al₂O₃ (A80), (3) 30?μm Al₂O₃ coated with SiO₂ (CoJet) (C30), (4) 30?μm Al₂O₃ coated with SiO₂ (Rocatec Soft) (R30), (5) 110?μm Al₂O₃ coated with SiO₂ (Rocatec Plus) (R110); (6) R110R30 (Rocatec) (R110R30) and (7) control, no conditioning (NC). Air-abrasion was performed using a chairside air-abrasion device (2.5?bar, 10?mm, 90?s). Contact angle measurements were performed using goniometry (n?=?5). MDP-based dual resin cement (Panavia F2.0) was bonded on four locations after air-abrasion protocols (n?=?20 per group). Half of the specimens were tested after 24?h and the other half after thermal cycling (×3000, 5–55?°C). Data were analyzed using 1-, 2-way ANOVA and Tukey’s test (alpha = 0.05). Significantly lower contact angle values were observed for groups C30 (62.6?±?0.91), R30 (61.91?±?1.05) and R110R30 (61.54?±?1.02) compared to those of other groups (65.5?±?0.9–110.61?±?0.9) (p?<?0.05). In dry conditions, surface conditioning methods tested did not show significant effect on bond strength (MPa) (10.57?±?1.42–16.86?±?2.54) (p?=?0.238). After thermocycling, bond strength results decreased significantly (p?<?0.05) (12.6–51.2%). R110 (7.18?±?1.34) and A80 (4.92?±?1.53) showed significantly higher bond strength compared to other groups (2.13?±?0.73–4.16?±?1.34) (p?<?0.05). The best wettability and adhesion results with MDP-based resin cement to zirconia was achieved with A80 and R110 air-abrasion.     

Separation and Spectrophotometric Determination of Osmium(IV) and Ruthenium(III) with O-methoxyphenyl Thiourea as Chromogenic Legand: Sequential Separation of Osmium(IV), Ruthenium(III), and Platinum(IV)

A precise and selective method has been developed for extraction spectrophotometric determination of osmium(IV) and ruthenium(III) using o-methoxyphenyl thiourea (OMePT) as a chromogenic ligand. The basis of the proposed methods are osmium(IV)-OMePT complex was formed in 0.8 mol L^?1 at room temperature while ruthenium(III)-OMePT complex was formed in 3.4 mol L^?1 aqueous hydrochloric acid media after 5.0 min heating in boiling water bath. The osmium(IV)-OMePT and ruthenium(III)-OMePT complex were measured at 518 and 640 nm against the reagent blank, respectively. Complexes were also extracted in 10 mL chloroform and showed comparable absorbance values. Beer’s law was obeyed up to 110.0 μg mL^?1 for osmium(IV)-OMePT complex and up to 50.0 μg mL^?1 for ruthenium(III)-OMePT complex. Molar absorptivity and Sandell’s sensitivity of osmium(IV)-OMePT and ruthenium(III)-OMePT complexes were 2.12 × 10³ L mol^?1 cm^?1, 0.089 μg cm^?2 and 2.34 × 10³ L mol^?1 cm^?1, 0.043 μg cm^?2, respectively. The stoichiometry of osmium(IV)-OMePT and ruthenium(III)-OMePT complex was 1:1 and 1:2, respectively. Stability of osmium(IV)-OMePT complex was > 8 days and that of ruthenium(III)-OMePT complex was > 48 h. The proposed method was successfully applied for determination of osmium(IV) and ruthenium(III) from synthetic mixtures corresponding to platinum-osmium alloy and fissium alloy, respectively. The method was successfully applied for sequential separation of osmium(IV), ruthenium(III), and platinum(IV).     

Effect of an electric field on the transport of Th(IV) in the presence of Eu(III) and U(VI) through supported liquid membrane containing di‐2‐ethylhexylphosphoric acid

This paper investigates the transport of Th(IV) ions in nitric acid media through a supported liquid membrane (SLM) impregnated with di‐2‐ethylhexylphosphoric acid (HDEHP) in kerosene using an electric field. The transport was carried out in a three compartment cell fitted with microporous cellulose nitrate (SLM) and cation exchange membrane (Nafion). The effect of different parameters including nitric acid concentration in the feed solution, HDEHP concentration in the membrane, and HCl concentration were studied. The optimal conditions for Th(IV) transport were 0.1 mol dm^?3 HDEHP, 10^?3 mol dm^?3 HNO₃ in the feed solution, 1 mol dm^?3 HCl in compartment 2 and 1 mol dm^?3 HCl in compartment 3 at 25 °C. Under the optimal conditions of Th(IV) transport the recovery factor after 90 min was 0.25 without applying an electrostatic field, compared with 0.9 when the electric field was applied. The effect of electric current on the flux of Th(IV) through the membrane was also studied. The flux increased as the current density increased from 10 to 30 mA cm^?2 to reach a maximum value at 30 mA cm^?2 (8 × 10^?9 g eq cm^?2 s^?1). The transport percentages of 0.3 g dm^?3 Th(IV) in the presence of 0.1 g dm^?3 Eu(III) and 1 g dm^?3 U(VI) were 66, 84 and 15%, respectively. The determined selectivities of U(VI)–Th(IV) and Th(IV)–Eu(III) were 0.12 and 0.3, respectively, after 90 min. Therefore, the order of selectivity of this system is Eu(III) > Th(IV) > U(VI). © 2001 Society of Chemical Industry     

Serial Changes of Serum Growth Factor Levels and Liver Regeneration after Partial Hepatectomy in Healthy Humans

This study aimed to investigate the associations of the serial changes of serum levels of various growth factors with liver regeneration after hepatectomy in healthy liver donors. Sixteen healthy liver donors who underwent conventional liver resection were included. Serum levels of various growth factors before hepatectomy and on postoperative day (POD) 1, 3, 5 and 7 were measured. Liver volume data calculated by multi-detector computed tomography using workstation. The ratio of remnant liver volume on POD 0 to liver volume before the operation was 51% ± 20%. The ratio of liver volume on POD 14 to liver volume on POD 0 were inversely correlated with remnant liver volume on POD 0 (r = −0.91). The ratio of liver volume on POD 14 to liver volume on POD 0 were significantly correlated with serum hepatocyte growth factor (HGF) levels on POD 1 (r = 0.54), serum leptin levels on POD 1 (r = 0.54), and serum macrophage colony-stimulating factor (M-CSF) levels on POD 5 (r = 0.76) and POD 7 (r = 0.80). These results suggest that early-phase elevation of serum levels of HGF, leptin and M-CSF may be associated with the acceleration of liver regeneration after hepatectomy in humans.