Micro-CT evaluation of microleakage under orthodontic ceramic brackets bonded with different bonding techniques and adhesives.

AIM: The aim of this study was to evaluate microleakage under orthodontic ceramic brackets bonded with direct and different indirect bonding techniques and adhesives using micro-computed tomography. MATERIALS AND METHODS: A total of 30 human maxillary premolars were randomly separated into five groups with six teeth in each group. In group I, teeth were bonded directly with Transbond XT (3M Unitek). In group II, group III, group IV, and group V, teeth were bonded through an indirect technique with Custom I.Q. (Reliance Orthodontic Products), Sondhi Rapid-Set (3M Unitek), RMbond (RMO), and Transbond IDB (3M Unitek), respectively, following the manufacturer's instructions. Micro-CT system model 1172 of Skyscan (Kontich, Belgium) was used to scan all samples. NRecon (Skyscan) version 1.6, CT-Analyser V.1.11 (Skyscan), and TView (SkyScan, Bvba) software programs were used for microleakage evaluation. Microleakage values between the test groups were assessed using the Kruskal-Wallis test, while the Wilcoxon signed rank test was used for within-group comparisons. The level of significance was set at P < 0.05. RESULTS: According to the Kruskal-Wallis analysis of variance test, there were no significant differences among the tested groups, with regard to volume and percentage (microleakage/region of interest × 100) of microleakage values (P < 0.05). The Wilcoxon signed rank test showed that coronal microleakage volume and percentage values significantly differed for RMbond and Transbond IDB groups. LIMITATIONS: In the study, only ceramic brackets were used and microleakage into mini gaps did not show up on the micro-CT image because 50% silver nitrate solution could not penetrate into mini gaps which are smaller than silver nitrate particles. CONCLUSION: Use of direct and indirect bonding techniques with different adhesives did not significantly affect the amount of microleakage.

Cu nanoparticles electrodeposited at liquid-liquid interfaces: a highly efficient catalyst for the hydrogen evolution reaction.

The electrochemical deposition of Cu nanoparticles with an average diameter of approximately 25-35 nm has been reported at liquid-liquid interfaces by using the organic-phase electron-donor decamethylferrocene (DMFc). The electrodeposited Cu nanoparticles display excellent catalytic activity for the hydrogen evolution reaction (HER); this is the first reported catalytic effect of Cu nanoparticles at liquid-liquid interfaces.

An electrochemical and computational study for discrimination of D- and L-cystine by reduced graphene oxide/ß-cyclodextrin.

Here, we report a novel enantioselective electrochemical biosensor for the discrimination of cystine enantiomers (d- and l-cystine) using a chiral interface for the specific recognition of d- and l-cystine. The biosensor is based on reduced graphene oxide modified by ß-cyclodextrin (rGO/ß-CD) at the GCE surface. During the preparation of rGO/ß-CD/GCE, the modified electrode surfaces were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The electrochemical behaviours of the d- and l-cystine were investigated using the rGO/ß-CD/GCE by CV and compared to bare GCE. A clear separation between the oxidation peak potentials of d- and l-cystine was observed at 1.32 and 1.42 V, respectively. The electrochemical discrimination performance of the fabricated chiral sensor was also examined by differential pulse voltammetry (DPV) in a mixed solution of d- and l-cystine. In addition, the DPV technique was used for the determination of d- and l-cystine at low concentration values in the range of 1.0-10.0 µM. To investigate the amperometric response of rGO/ß-CD/GCE towards d- and l-cystine, the chronoamperometry technique was used in the concentration range of 10.0-100.0 µM. The interactions of the enantiomers with rGO/ß-CD were modelled by molecular docking using AutoDock Vina, and the interaction energies were predicted to be -4.8 and -5.3 kcal mol(-1) for d- and l-cystine, respectively. The corresponding values of binding constants were calculated to be 3.32 × 10(3) and 7.71 × 10(3) M(-1), respectively. The experimental and molecular docking results indicate that the rGO/ß-CD/GCE has a different affinity for each enantiomer.

Calixarene assembly with enhanced photocurrents using P(SNS-NH2)/CdS nanoparticle structure modified Au electrode systems.

Two novel calix[n]arene-adorned gold electrodes producing high photocurrent intensities were successfully constructed by embedding gold electrode surfaces with both P(4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine) conducting polymer and 4-mercaptoboronic acid-functionalized semiconductor CdS nanoparticles to facilitate the binding of calix[n]arene sulfonic acids with nanoparticles. This structure enabled an electron transfer cascade that both induced effective charge separation and efficiently generated photocurrent. The prepared electrodes were used to generate photocurrent by relying on the host-guest interactions of guests Br3(-) and I3(-), which if positioned well in the system was able to fill electron-hole pairs of CdS nanoparticles. As a result, host calixarene derivatives crucially held Br3(-) and I3(-) ions at a substantial distance from CdS nanoparticles. Furthermore, the effects of various calixarenes on the photocurrent obtained indicate that the generation of photocurrent intensities by the system depends on the cavity sizes of calixarene derivatives, which provide an essential center for Br3(-) and I3(-) ions.

Voltammetric discrimination of mandelic acid enantiomers.

We report a novel electrochemical biosensor for direct discrimination of D- and L-mandelic acid (D- and L-MA) in aqueous medium. The glassy carbon electrode (GCE) surface was modified with reduced graphene oxide (rGO) and γ-globulin (GLOB). Electrochemical characterization of the modified electrodes was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode surfaces were also characterized by scanning electron microscopy. Electrochemical response of the prepared electrode (GCE/rGO/GLOB) for discrimination of D- and L-MA enantiomers was investigated by cyclic voltammetry and was compared with bare GCE in the concentration range of 2 to 10 mM. Whereas the bare GCE showed no electrochemical response for the MA enantiomers, the GCE/rGO/GLOB electrode exhibited direct and selective discrimination with different oxidation potential values of 1.47 and 1.71 V and weak reduction peaks at potential values of -1.37 and -1.48 V, respectively. In addition, electrochemical performance of the modified electrode was investigated in mixed solution of D- and L-MA. The results show that the produced electrode can be used as electrochemical chiral biosensor for MA.

Photocatalytic hydrogen evolution by oleic acid-capped CdS, CdSe, and CdS0.75Se0.25 alloy nanocrystals.

Photocatalytic generation of hydrogen by using oleic acid-capped CdS, CdSe, and CdS(0.75)Se(0.25) alloy nanocrystals (quantum dots) has been investigated under visible-light irradiation by employing Na(2)S and Na(2)SO(3) as hole scavengers. Highly photostable CdS(0.75)Se(0.25) alloy nanocrystals gave the highest hydrogen evolution rate (1466 µmol h(-1) g(-1)), which was about three times higher than that of CdS and seven times higher than that of CdSe.

Facial soft-tissue thickness in patients affected by bilateral cleft lip and palate: a retrospective cone-beam computed tomography study.

INTRODUCTION: The purposes of this study were to evaluate the facial soft-tissue thicknesses and craniofacial morphologies of patients affected by bilateral cleft lip and palate (BCLP) and to compare the findings with a well-matched control group without any clefts using cone-beam computed tomography. METHODS: The study sample consisted of 40 retrospectively and randomly selected patients divided into 2 groups: a BCLP group (20 patients; mean age, 13.78 ± 3.20 years) and an age- and sex-matched control group without clefts (20 patients; mean age, 13.94 ± 2.52 years). Craniofacial and facial soft-tissue thickness measurements were made with cone-beam computed tomography. The Student t test and multiple linear regression analyses were performed for the statistical evaluations. RESULTS: The BCLP group had an increased SN-MP angle (P = 0.003), a decreased Co-A (P = 0.000), and retruded maxillary (P = 0.000) and mandibular (P = 0.026) incisors. In addition, patients affected by BCLP had statistically significantly decreased thickness measurements for the variables subnasale (P = 0.005) and labrale superior (P = 0.026) compared with the controls. The most predictive variables were found at U1-SN (r = 0.417, P = 0.004), IMPA (r = 0.368, P = 0.010), and ANB (r = -0.297, P = 0.031) for subnasale and U1-SN (r = 0.284, P = 0.038) for labrale superior. CONCLUSIONS: The BCLP group showed greater vertical growth, greater retrusion of the maxilla and the maxillary and mandibular incisors, and decreased subnasale and labrale superior thicknesses compared with the well-matched controls without clefts. These differences should be taken into account when planning orthodontic and orthognathic surgery treatment for those patients.

Recent advances and applications of nanostructured membranes in water purification.

In recent years, water pollution caused by hazardous materials such as metals, drugs, pesticides, and insecticides has become a very serious environmental and health problem that needs to be addressed urgently. The nutritional needs associated with the increasing population also increase the demand for water use and rapidly increase the rate of freshwater consumption. Since most of the water in the universe is in the form of sea water, which cannot be directly used, freshwater resources are limited, compared to the existing available water. When addressing the purification of all kinds of pollution in environmental research, nanostructured membranes attract attention as alternative solutions for water treatment. Nanostructured membranes, which can be used for filtration and water treatment process, are summarized in recent research. Various types of nanostructured membranes are presented and used to remove salts and metallic ions in water treatment processes. The representations and application areas of these membrane systems are explained. Consequently, new water treatment nanostructured membranes that can be developed and their effective separation performances are described. The benefits of nanostructured membranes for water treatment and their progress in purification are discussed.

Enhancing visible light photocatalytic activity of holmium doped g-C3N4 and DFT theoretical insights.

In the search of novel photocatalysts to increase the effect of visible light in photocatalysis, g-C3N4 (CN) has become a shining star. Rare earth metals have been used as dopant material to reinforce the photocatalytic activity of CN due to their unique electron configuration recently. In this present study, the pure and different amounts of Ho-doped g-C3N4 (HoCN) photocatalysts were successfully synthesized using urea as a precursor by the one-pot method. Morphological, structural, optical, and vibrational properties of the synthesized photocatalysts were characterized by SEM, EDX, XRD, TGA, XPS, FTIR, PL, TRPL, Raman, DRS, and BET analyses. In addition, theoretical calculations using density functional theory (DFT) were meticulously carried out to delve the changes in the structural and electronic structure of CN with holmium doping. According to calculations, the chemical potential, electrophilicity, and chemical softness are higher for HoCN, while HOMO-LUMO gap, dipole moment, and the chemical hardness are lower for the pure one. Thus, holmium doping becomes desirable with low chemical hardness which indicates more effectivity and smaller HOMO-LUMO gap designate high chemical reactivity. To determine the photocatalytic efficiency of the pure and doped CN photocatalysts, the degradation of methylene blue (MB) was monitored under visible light. The results indicate that holmium doping has improved the photocatalytic activities of CN samples. Most strikingly, this improvement is noticeable for the 0.2 mmol doped CN sample that showed two times better photocatalytic activity than the pure one.

Effects of maternal left lateral position and rest on amniotic fluid index: a prospective clinical study.

OBJECTIVE: To compare the effect of both maternal rest and activity on the amniotic fluid index (AFI). STUDY DESIGN: Power analysis indicated that in order to achieve 20 mm of increase in AFI with 90% of power at one side alpha of 0.01, we needed at least 51 women in each group. The study group was comprised of pregnant women (n = 152) with a normal AFI and a singleton pregnancy at 26-40 weeks' gestation. Their AFI was determined by averaging the 2 repetitive measurements of the 4 amniotic fluid quadrants. The "rest" group (n = 77) was instructed to lie and rest in the left lateral position, and the "mild activity" group (n = 75) was instructed to sit and walk. RESULTS: AFI increased significantly, from 151.25 +/- 37.40 mm to 173.79 +/- 39.76 mm, in the "rest" group (p = 0.00). However, the change from 153.69 +/- 37.94 to 152.34 +/- 36.62 mm was not significant in the "mild activity" group (p = 0.167). CONCLUSION: Maternal rest in the left lateral position increases the AFI.

Effects of force magnitude on relapse: An experimental study in rabbits.

INTRODUCTION: The aims of this study were to investigate the effects of 2 force levels on the amount of relapse and to determine whether there is a relationship between the rates of tooth movement and relapse. METHODS: Approximately 20-g (group I) and 60-g (group II) forces were applied to the maxillary central incisors of 25 young adult (14 weeks of age) New Zealand female rabbits. Active tooth movement lasted 20 days. Then, the appliances were removed, and the incisors were released. The distance between the incisors was measured daily from the midlevels of the crowns by using a digital caliper during the active phase of tooth movement for 20 days, and then relapse was measured at the same level for 37 days. Analysis of variance and the Bonferroni multiple range test were used for statistical analyses. RESULTS: After active tooth movement, the mean total opening amounts were 3.98 ± 0.59 mm in group I and 4.82 ± 0.82 mm in group II, and the mean difference was approximately 0.8 mm. A rapid relapse was observed on the initial days in both groups, and its rate decreased with time. Significant relapse was observed in the first 5 and 8 days of the experiment in 20-g and 60-g force groups, respectively. The relapse in group II was significantly greater than in group I only on the first day of experiment. Statistically significant correlations were found between total tooth movement and relapse (R = 0.896, P <0.001). CONCLUSIONS: These results showed a close relationship between the amount of relapse and orthodontic force magnitude. Greater relapse occurred during the initial days after appliance removal, and this indicates that retention appliances are needed immediately after the removal of orthodontic appliances.

Real-time cell analysis of the cytotoxicity of the components of orthodontic acrylic materials on gingival fibroblasts.

INTRODUCTION: The aim of this study was to evaluate the cytotoxicity of 3 orthodontic acrylic materials and 2 manipulation methods. METHODS: The orthodontic acrylic materials Orthocryl EQ (Dentaurum, Ispringen, Germany), Orthoplast (Vertex Dental, Zeist, The Netherlands), and O-80 (Imicryl, Konya, Turkey) were prepared with 2 polymerization methods (doughing and spray on). Totally, 60 cylinders (5 × 2 mm), fabricated by using a different acrylic and method, were divided into 6 groups. Gingival fibroblasts were isolated from gingival connective tissue of systemically healthy subjects. Materials were incubated in Dulbecco's modified eagle's medium culture medium (Biological Industries, Beit Haemek, Israel) for 72 hours according to ISO 10993-5 standards (surface area to volume ratio of the specimen to cell-culture medium: 3 cm(2)/mL). Gingival fibroblasts were maintained with Dulbecco's modified eagle medium containing 10% fetal bovine serum. A real-time cell analyzer (RT-CES, xCELLigence; Roche Applied Science, Mannheim, Germany, and ACEA Biosciences, San Diego, Calif) was used to evaluate cell survival. After seeding 200 µL of the cell suspensions into the wells (20,000 cells/well) of the E-plate 96, gingival fibroblasts were treated with bioactive components released by the acrylic materials (1/1 and 1/2 dilutions) and monitored every 15 minutes for 121 hours. For the proliferation experiments, the statistical analyses used were 1-way analysis of variance (ANOVA) and Tukey-Kramer multiple comparisons tests. RESULTS: There was no significant difference between the cell indexes of the control and study groups for the 1/1 and 1/2 dilutions at 21 and 32 hours. When evaluated at 68 hours, all 1/2 dilutions of acrylic materials showed statistically insignificant differences (P >0.05) except for Orthoplast (P <0.05). But all acrylic materials were different from the control group in the 1/1 dilutions (P <0.001). At 121 hours, all test groups were significantly different from the untreated control group (P <0.001). CONCLUSIONS: The results indicate that the long cycle increased the cytotoxicity of the tested materials, and there was no significant difference between the spray-on and doughing methods on cytotoxicity.

PAN-based activated carbon nanofiber/metal oxide composites for CO2 and CH4 adsorption: influence of metal oxide.

In the present study, we successfully prepared two different electrospun polyacrylonitrile (PAN) based-activated carbon nanofiber (ACNF) composites by incorporation of well-distributed Fe2O3 and Co3O4 nanoparticles (NPs). The influence of metal oxide on the structural, morphological, and textural properties of final composites was thoroughly investigated. The results showed that the morphological and textural properties could be easily tuned by changing the metal oxide NPs. Even though, the ACNF composites were not chemically activated by any activation agent, they presented relatively high surface areas (SBET) calculated by Brunauer-Emmett-Teller (BET) equation as 212.21 and 185.12 m2/g for ACNF/Fe2O3 and ACNF/Co3O4 composites, respectively. Furthermore, the ACNF composites were utilized as candidate adsorbents for CO2 and CH4 adsorption. The ACNF/Fe2O3 and ACNF/Co3O4 composites resulted the highest CO2 adsorption capacities of 1.502 and 2.166 mmol/g at 0 °C, respectively, whereas the highest CH4 adsorption capacities were obtained to be 0.516 and 0.661 mmol/g at 0 °C by ACNF/Fe2O3 and ACNF/Co3O4 composites, respectively. The isosteric heats calculated lower than 80 kJ/mol showed that the adsorption processes of CO2 and CH4 were mainly dominated by physical adsorption for both ACNF composites. Our findings indicated that ACNF-metal oxide composites are useful materials for designing of CO2 and CH4 adsorption systems.

Rhenium/rhenium oxide nanoparticles production using femtosecond pulsed laser ablation in liquid.

In this study, rhenium/rhenium oxide nanoparticles (Re / ReO3 NPs) have been produced for the first time in ultrapure water by using Femtosecond Pulsed Laser Ablation in Liquid (fsPLAL) method. X-Ray Diffraction (XRD) measurements and results obtained for NPs show the existence of well-crystallized peaks and preferred phases. Re NPs have hexagonal structure while ReO3 NPs have the perovskite-like cubic crystal structures. The Re / ReO3 ratio is also determined to be 53 / 47 with ~ 20 nm crystallite size, while pure ReO3 crystallite sizes were measured to be ~ 25 nm. The TEM results have shown that the produced particles have a spherical shape, and particle sizes changes between ~ 20 nm and ~ 60 nm. The crystallite size is similar due to XRD results. Obtained nanoparticles exhibit promising applications for photonic devices with broad bandgap values which have measured to be 4.71 eV for Re / ReO3 NPs mixture and 4.36 eV for pure ReO3 NPs.

Oxygen reduction catalyzed by a fluorinated tetraphenylporphyrin free base at liquid/liquid interfaces.

The diprotonated form of a fluorinated free base porphyrin, namely 5-(p-aminophenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (H(2)FAP), can catalyze the reduction of oxygen by a weak electron donor, namely ferrocene (Fc). At a water/1,2-dichloroethane interface, the interfacial formation of H(4)FAP(2+) is observed by UV-vis spectroscopy and ion-transfer voltammetry, due to the double protonation of H(2)FAP at the imino nitrogen atoms in the tetrapyrrole ring. H(4)FAP(2+) is shown to bind oxygen, and the complex in the organic phase can easily be reduced by Fc to produce hydrogen peroxide as studied by two-phase reactions with the Galvani potential difference between the two phases being controlled by the partition of a common ion. Spectrophotometric measurements performed in 1,2-dichloroethane solutions clearly evidence that reduction of oxygen by Fc catalyzed by H(4)FAP(2+) only occurs in the presence of the tetrakis(pentafluorophenyl)borate (TB(-)) counteranion in the organic phase. Finally, ab initio computations support the catalytic activation of H(4)FAP(2+) on oxygen.

Effects of force magnitude on tooth movement: an experimental study in rabbits.

The aim of the present study was to investigate the effects of two different force levels on the amount of total and daily tooth movement in rabbits and to determine whether any increase in tooth movement is equal to the increase in force. Forces of approximately 20 (group I) and 60 (group II) g (19.6 and 58.8 cN) were applied to the upper central incisors of 25 young adult (14 weeks of age) New Zealand female rabbits. The distance between the incisors was measured daily from the mid-levels of the crowns using a digital calliper for 20 days. Analysis of variance and Bonferroni multiple range test were used for statistical analyses. The distance between the teeth in group II was significantly greater than that in group I during the first 3 days. Between days 4 and 14, no significant difference was observed. During the last 6 days, except for day 19, tooth movement in group II again increased, resulting in the distance between the teeth being greater in group II. The mean total opening was 3.98 +/- 0.59 mm in group I and 4.82 +/- 0.82 mm in group II, and the mean difference was approximately 0.8 mm. The results of this study show that there was a close relationship between tooth movement and force magnitude. However, higher forces did not produce force-equal tooth movements.

Proton-coupled oxygen reduction at liquid-liquid interfaces catalyzed by cobalt porphine.

Cobalt porphine (CoP) dissolved in the organic phase of a biphasic system is used to catalyze O(2) reduction by an electron donor, ferrocene (Fc). Using voltammetry at the interface between two immiscible electrolyte solutions (ITIES), it is possible to drive this catalytic reduction at the interface as a function of the applied potential difference, where aqueous protons and organic electron donors combine to reduce O(2). The current signal observed corresponds to a proton-coupled electron transfer (PCET) reaction, as no current and no reaction can be observed in the absence of either the aqueous acid, CoP, Fc, or O(2).

Hydrogen evolution at liquid-liquid interfaces.

Blowing bubbles: Hydrogen evolution by proton reduction with [(C(5)Me(5))(2)Fe] occurs at a soft interface between water and 1,2-dichloroethane (DCE). The reaction proceeds by proton transfer assisted by [(C(5)Me(5))(2)Fe] across the water-DCE interface with subsequent proton reduction in DCE. The interface essentially acts as a proton pump, allowing hydrogen evolution by directly using the aqueous proton.

Synthesis, characterization, and sorption properties of silica gel-immobilized Schiff base derivative.

Silica gel was derivatized with benzophenone 4-aminobenzoylhydrazone (BAH), a Schiff base derivative, after silanization of silica by 3-chloropropyltrimethoxysilane (CPTS) by using a reported method. Characterization of the surface modification was confirmed through infrared spectroscopy, thermogravimetry, and elemental analysis. The immobilized surface was used for Cu(II), Ni(II), Zn(II), and Co(II) sorption from aqueous solutions. The influence of the amount of sorbent, ion concentration, pH, and temperature was investigated. The sorption data followed Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms. The mean sorption energy (E) of benzophenone 4-aminobenzoylhydrazone (BAH) immobilization onto silica gel was calculated from D-R isotherms, indicating a chemical sorption mode for four cations. Thermodynamic parameters, i.e., DeltaG, DeltaS, and DeltaH, were also calculated for the system. From these parameters, DeltaH values were found to be endothermic: 27.0, 22.7, 32.6, and 34.6 kJ mol(-1) for Cu(II), Ni(II), Co(II), and Zn(II) metal ions, respectively. DeltaS values were calculated to be positive for the sorption of the same sequence of divalent cations onto sorbent. Negative DeltaG values indicated that the sorption process for these three metal ions onto immobilized silica gel is spontaneous.

Evaluation of antibacterial properties on polysulfone composite membranes using synthesized biogenic silver nanoparticles with Ulva compressa (L.) Kütz. and Cladophora glomerata (L.) Kütz. extracts.

Polysulfone (PS) composite membrane using green synthesized biogenic silver nanoparticles (Ag-NPs) with Ulva compressa (L.) Kütz. and Cladophora glomerata (L.) Kütz. extract were prepared by spin coating technique and are tested for antimicrobial activity using a direct contact test for the first time. Initially green synthesis of Ag-NPs was accomplished utilizing green macro algae i.e. U. compressa (L.) Kütz. and C. glomerata (L.) Kütz. by the reduction of AgNO3. The Ag-NPs/PS composite membranes from both algae revealed outstanding antimicrobial activity against all bacteria i.e. K. pneumonia, P. aeruginasa, E. coli, E. faecium and S. aureus. Bacterial growth was monitored for 17h with a temperature controlled microplate spectrophotometer. The kinetics of the outgrowth in each well were recorded continuously at 630nm every 60min. Thus present work remarkably offers a feasible, cheap and efficient alternative for making Ag-NPs and their utilization as antimicrobial agent on the PS composite membrane.