Agitation Techniques Research Articles

Effectiveness of Different Final Irrigant Activation Protocols on Smear Layer Removal in Curved Canals

Introduction A final flush with chelating agents and antiseptic irrigating solutions is needed to remove the smear layer. The improvement of these protocols is possible by using specific delivery and agitation techniques. This study examined the effect of different final irrigation regimens and methods of activation on smear layer removal in curved canals after root canal instrumentation. Methodology Mesial root canals of 50 extracted mandibular molars were prepared using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland) and 3% NaOCl. Teeth were then allocated to two control groups and four experimental groups ( n = 10) for final irrigation as follows: no-activation group (final rinse with a 27-gauge needle and 17% EDTA/3% NaOCl), manual-dynamic activation group (final rinse 17% EDTA/3% NaOCl + gutta-percha agitation), automated-dynamic activation group (final rinse 17% EDTA/3% NaOCl + RinsEndo [Dürr Dental GmbH & Co KG, Bietigheim-Bissingen, Germany]), and sonic-activation group (final rinse 17% EDTA/3% NaOCl + Endoactivator [Advanced Endodontics, Santa Barbara, CA]). All mesial roots were split with a new approach to allow visualization of every third of the canal, particularly the apical third. The samples were prepared for scanning electron microscopic observation to assess the smear layer removal. Blind scoring was performed by two calibrated observers using a five-score scale. The differences in smear layer scores between the experimental groups were analyzed with the Kruskal-Wallis test and the Mann-Whitney U test. The level of significance was set at p = 0.05. Results Very high levels of root canal cleanliness (≤score 3) were found for each test group with activation. For the middle and apical third, the no-activation group was significantly less effective than the three other activation groups (p < 0.05). The manual-dynamic activation group (final rinse 17%EDTA/3%NaOCl + gutta-percha agitation) and the sonic-activation group (final rinse 17%EDTA/3%NaOCl + Endoactivator) showed significantly better smear layer removal (p < 0.05) in comparison with the other test groups in the apical third. Conclusion Root canal cleanliness benefits from solutions activation (especially sonic activation and manual-dynamic activation) in comparison with no activation during the final irrigation regimen.

Effect of dentine smear layer on the performance of self‐etching adhesive systems: A micro‐tensile bond strength study

This study aimed to evaluate the effect of the smear layer on the micro-tensile bond strength when two self-etching adhesives were used with different techniques. Flat dentine surfaces were prepared using either medium grit diamond burs or tungsten carbide burs. Ten specimens from each prepared surfaces were subjected for smear layer evaluation under SEM. Forty specimens from each of the prepared surfaces were further divided into two groups, bonded with either Clearfil SE Bond (SE) or Clearfil S(3) Bond (S3) using one of four applications (as manufacturer's instructions, agitation, reapplication, and increased application time), restored with composites and subjected to a micro-tensile bond strength test. Smear layers created with diamond burs were thicker than those created with tungsten carbide burs. Surfaces prepared with tungsten carbide burs produced a higher bond strength than those prepared with diamond burs and the same type of adhesive resin. SE demonstrated a higher bond strength than S3 for all surfaces. S3 applied with the agitation technique demonstrated a higher bond strength to dentine prepared with tungsten carbide and diamond burs than that applied with other techniques. SE applied with increased time on dentine treated with carbide burs produced the highest bond strength. In conclusion, a thick smear layer decreased bond strength to dentine, and this might be improved by modification of application technique.

A breakthrough technique for the preparation of high-yield precipitated calcium carbonate

Precipitated calcium carbonate (PCC) is conventionally produced through the gas–solid–liquid carbonation route, which consists on bubbling gaseous CO 2 through a concentrated calcium hydroxide (Ca(OH) 2) slurry. However, atmospheric carbonation processes are slow and have low carbonation efficiency. A novel technology based on the combination of supercritical carbon dioxide (scCO 2) and ultrasonic agitation is described here for the preparation of high-yield PCC. The combination of both techniques has demonstrated to produce outstanding improvement for the conversion of Ca(OH) 2 to the stable calcite polymorph of calcium carbonate (CaCO 3). These experiments were carried out at 313 K and 13 MPa using a high-pressure reactor immersed in an ultrasounds cleaner bath. The process kinetics and the characteristics of the precipitated particles using ultrasonic agitation were compared with those obtained under similar experimental conditions using mechanical stirring and non-agitated systems. The crystal characteristics of the samples obtained using the three different agitation techniques were characterized by X-ray diffraction and scanning electron microscopy.

Preparation of short, robust and highly ordered TiO2 nanotube arrays and their applications as electrode

The short, robust and highly ordered TiO2 nanotube arrays (TNAs) electrode was prepared by sonoelectrochemical anodization of titanium in HF–H2O electrolyte solution (referred as short TNAs, STNAs). The self-organized arrays of titania nanotubes of approximately 12–65nm in diameter and 75–280nm in length can be synthesized at anodic voltage of 5–20V. The electron transport process within the STNAs electrode was much favorable in comparison with that for the long TNAs electrode synthesized by conventional magnetic agitation technique (referred as long TNAs, LTNAs), as confirmed by the obviously enhanced photocurrent response of STNAs electrode either in 0.02M Na2SO4 electrolyte solution or in different concentrations of glucose solution or under different intensities of UV illumination. To investigate their photoelectrochemical applications, degradation of tetracycline, a typical pharmaceutical and personal care products (PPCPs), was carried out using photoelectrocatalytic (PEC) means, comparing with electrochemical (EC) and photocatalytic (PC) processes. The kinetic constant of the PEC process of STNAs electrode was ∼3.17 times as high as its PC process. The color removal rate of tetracycline by STNAs electrode achieved 81% within 3h, which was 21% higher than that for LTNAs electrode. In degrading tetracycline, 41% of TOC was mineralized using the STNAs electrode against 23% using LTNAs electrode under similar conditions. Such kind of titania nanotubes will have many potential applications in various areas as an outstanding photoelectrochemical material.

An In Vitro Comparison of New Irrigation and Agitation Techniques to Ultrasonic Agitation in Removing Bacteria From a Simulated Root Canal

Introduction This in vitro study compared 3 agitation and 2 irrigation devices to ultrasonic agitation at mechanically removing bacteria from a plastic simulated canal, instrumented to 35/.06. Methods The plastic blocks were divided into seven groups. The control (C) group with brain-heart infusion (BHI) broth (sterile) received only needle irrigation. The remaining groups were incubated with BHI inoculated with Enterococcus faecalis. Irrigation and agitation techniques were ultrasonic, needle irrigation, EndoVac irrigation (Smart Endodontics; Discus Dental, Culver City, CA), EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK), F-File (Plastic Endo, Lincolnshire, IL), and sonic. Sterile water was the irrigant in all treatments. Remaining bacteria were stained with 0.1% crystal violet. The crystal violet was extracted using a detergent and measured spectrophotometrically. Results The results of this study show that ultrasonic agitation was not significantly different (p > 0.05, Tukey test) from the control. There was no significant difference (p > 0.05, Tukey test) between the ultrasonic agitation and the use of EndoActivator, F-File, and sonic agitation. Ultrasonic agitation was significantly more effective at removing bacteria than needle irrigation and EndoVac irrigation (p < 0.05, Tukey test). Conclusion In a plastic simulated canal, ultrasonic agitation was significantly more effective than needle irrigation and EndoVac irrigation at removing intracanal bacteria. Ultrasonic, EndoActivator, F-File, and sonic agitation are similar in their ability to remove bacteria in a plastic simulated canal.

High-temperature mechanical and electrical properties of W-particle-reinforced Cu-matrix composites from improved electroless plated powders

Copper (Cu)-matrix composites combine the high electrical and thermal conductivities of Cu with the enhanced wear resistance and strength of the reinforcement material, and are therefore widely used for electrical contact applications in a diverse range of fields. In the current study, tungsten-reinforced copper (W—Cu) composite powders are fabricated using a novel electroless Cu plating process in which the homogeneity of the powder mixture is improved via the use of an ultrasonic agitation technique. The volume content of the tungsten particle reinforcement in the composite specimens is 3, 6, and 12 per cent, respectively, and standard powder metallurgical techniques are then applied to produce the final composite powders. The mechanical and electrical properties of the composite powders are evaluated at room temperature and at temperatures ranging from 100 to 300 °C. Fracture surfaces of the composite samples are ana-lysed using scanning electron microscopy. The results show that the mechanical properties of the W—Cu composite samples are significantly better than those of pure Cu specimens, particularly at higher temperatures. Furthermore, the addition of 3 vol% W particles to the W—Cu composite is found to yield a reduction of not more than 2 per cent in the electrical conductivity of the composite sample compared to that of a pure Cu specimen. Overall, the results indicate that the optimal mechanical and electrical properties are obtained by mixing pure Cu powder with 3 vol% of Cu-plated W particles with a mean dimension of 1 μm.

Hexagonal Phase of CdS Thin Films Obtained by Oscillating Chemical Bath

Cadmium sulfide thin films were deposited in an oscillating chemical bath using a Teflon vane connected to an electrical dental brush oscillating at . The range of the bath temperature was from 65 to in intervals of and different deposition times. By this agitation technique we obtained films with a highly oriented hexagonal structure (α-greenockite) in the (002) direction as measured by X-ray diffraction patterns. Images of atomic force microscopy and stoichiometry values obtained by energy-dispersive analysis by X-ray confirm the good quality of deposited films. High stoichiometry on the films was measured by elemental analysis with variations less than 3.5% in all samples. The mean value of the gap energy was about , a close value for these films.

Interlaminar shear strength of glass fiber reinforced epoxy composites enhanced with multi-walled carbon nanotubes

In this study, we examine the interlaminar shear strength (ILSS) of traditional glass fiber reinforced epoxy composites enhanced by strategically injecting multi-walled carbon nanotube (MWNT)–epoxy suspensions into stationary glass fiber mats. The suspensions were prepared by combining the techniques of high-speed mechanical stirring, ultrasonic agitation and acid oxidation. Two types of process designs were introduced to fabricate the hybrid MWNT/glass/epoxy composites and their relative merits were discussed. Short beam shear (SBS) and compression shear tests (CST) were conducted on the manufactured components to characterize the influence of the process and the weight percentage of nanotubes on the ILSS. The results show that the introduction of MWNT into the composite increased the ILSS by up to 33%. The preferential orientation of the MWNTs in the thickness direction was found to contribute to the increase in the interlaminar shear properties.

Measurement and enhancement of gas–liquid mass transfer in milliliter-scale slurry reactors

Due to the limited availability of chemical reactants in the early process development of pharmaceuticals and fine chemicals, and sometimes the high-cost of catalyst, it is increasingly popular to use milliliter-scale slurry reactors with reaction volumes of 20 ml or less to screen catalyst candidates for three-phase reactions. To ensure the success of catalyst screening, it is advantageous to run reactions under kinetically controlled conditions so that the activities of different catalysts can be compared. Because catalysts with small particle sizes are used in slurry reactors, the reactions are susceptible to gas–liquid mass transfer limitations. This work presents an efficient way of enhancing gas–liquid mass transfer in milliliter-scale reactors through the use of magnetically driven agitation with complex motion. In the reactor described here, gas–liquid mass transfer coefficients can be doubled over those obtained with the agitation technique used in commercial milliliter-scale units. In addition, the reactor can achieve the top range of mass transfer coefficients obtained in a full-scale reactor. This work also presents the first measurements of gas–liquid mass transfer coefficients in milliliter-scale reactors, which are two orders-of-magnitude smaller than systems for which mass transfer coefficients have been reported earlier. Both physical and chemical absorption techniques are used.

Oxidation of aniline over titania pillared montmorillonite clays

Titania pillared clays (Ti-PILC) have been synthesized employing conventional stirring (method I) and ultrasonic agitation (method II) techniques followed by hydrothermal treatment. The characterization results revealed the formation of Ti-PILC with significant reduction of time when ultrasonic method was used. Subsequent hydrothermal treatment on the samples has resulted in the increase in the crystallinity and the transformation of anatase TiO2 to rutile TiO2. The rutile phase is more prominent in the samples prepared by stirring method. UV–Vis studies on the samples exhibit blue shift in the absorption band due to the quantum size effect. This indicates that a major part of TiO2 in the pillared clay could be well below 10 nm in size, which is supported by XRD and the average pore size. The pillared clay catalysts have proved to be promising in aniline oxidation with H2O2, selectively forming azoxybenzene under the working conditions. The aniline conversion and the product distribution largely depended on the catalyst concentration, H2O2 to aniline mole ratio, the nature of the solvent and the oxidant. Higher conversion of aniline and greater selectivity for azoxybenzene was obtained with methanol as the solvent.

Effects of surfactants on the PTFE particle sizes in electroless plating Ni-P-PTFE coatings

SUMMARYThe size and distribution uniformity of PTFE particles incorporated into Ni-P matrix has a significant effect on the morphology and antifouling properties of the Ni-P-PTFE composite coatings. In this paper five types of surfactants were used to disperse PTFE particles in plating suspensions and the effects of the surfactants on the size and distribution of PTFE particles in Ni-P-PTFE coatings were investigated. The effects of the surfactants on the deposition rate and PTFE content in the electroless Ni-P-PTFE coatings were also investigated. An optimum surfactant was determined, leading to the uniform distribution of nano-PTFE particles throughout the Ni-P matrix, without using additional mechanical or ultrasonic agitation technique. The optimum ratio of the surfactant concentration to PTFE particle concentration in the plating solution and the corresponding optimum operating conditions for electroless plating Ni-P-PTFE coatings were obtained. The morphology of Ni-P-PTFE coatings was evaluated by SEM.

Development of High-Speed Electroforming Technique.

Two types of electroforming techniques that can produce thick electroformed coatings were developed to utilize the coatings as microgrinding tools. Sedimented abrasive grains on the cathode were agitated continuously at a low speed to increase the nickel ion density near the cathode when the low-speed agitation technique was employed. In addition, an open space 3 mm square and 15 mm in length was grooved on a cylindrical aclylic insulator that covered the columnar anode, and an attempt to fill the space with the deposited coating was made by rotating the cathode at a low speed when the low-speed rotation technique was employed. It became obvious that an electric force line was concentrated at the edge of the cathode, so that a coating with uniform thickness could not be realized when the low-speed agitation technique was employed. 0n the other hand, high-speed electroforming that can produce a thick coating 3 mm square and 15 mm in length in 18.3 hours was accomplished when the low-speed rotation technique was employed.

Analysis of bacteriophage inactivation and its attenuation by adsorption onto colloidal particles by batch agitation techniques

A batch agitation technique was designed to specify the different parameters that influence the inactivation and adsorption mechanisms of viruses in water. The advantage of this method over the classical procedures is that the kinetic reactions of the different subfractions of the virus population can be described simultaneously. A first set of experiments with phage T7 showed that this phage is rapidly inactivated in a constantly agitated liquid medium. This inactivation rate is highly influenced by temperature, but variation of the pH (from 5 to 9) and increase in salt concentration have no effect on it. The addition of colloidal clay particles (CCPs) of montmorillonite and attapulgite into the liquid medium considerably modifies this behavior, even at very low concentrations (0.025 mg/mL). The experiments show that the viruses react quickly with the particles and that bonding is not permanent. Viruses establish a dynamic equilibrium, which is strongly dependent on physicochemical parameters such as pH, ionic concentrations, and the presence of proteins or protein hydrolysates. A major environmental consequence is that the presence of CCPs seems to effectively protect the coliphage T7 from rapid inactivation.Key words: bacteriophage T7, viruses, inactivation and adsorption kinetics, colloidal particles, protective effect.

Analysis of bacteriophage inactivation and its attenuation by adsorption onto colloidal particles by batch agitation techniques

Analysis of bacteriophage inactivation and its attenuation by adsorption onto colloidal particles by batch agitation techniques

Determination of carbonyl compounds in water by derivatization–solid-phase microextraction and gas chromatographic analysis

The solid-phase microextraction (SPME) technique was evaluated for the determination of 23 carbonyl compounds in water. The carbonyl compounds in water were derivatized with o-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA), extracted with SPME from liquid or headspace and analyzed by GC with electron capture detection (GC–ECD). The effects of agitation techniques and the addition of salt (NaCl) on extraction, the absorption–time and absorption–concentration profiles were examined. The precision of the SPME technique for the determination of carbonyl compounds was evaluated with spiked bidistilled water, ozonated drinking water, and rain water. The relative standard deviations obtained from different spiked water matrix were similar, and in the range of 5.7–21.1%. The precision can be further improved by using an internal standard. With 4 ml of water sample, the limits of detection for most of the tested carbonyl compounds using liquid or headspace SPME–GC–ECD were similar and in the range of 0.006–0.2 μg/l, except for glyoxal and methylglyoxal, which showed low sensitivity when using headspace SPME. In the analysis of an ozonated drinking water sample, the SPME techniques gave comparable results to those of the conventional liquid–liquid extraction method.

Quantification of epiphyte removal efficiency from submersed aquatic plants

Three independent methods were used to quantify the efficiency of a mechanical agitation technique for the removal of epiphytes from four submersed macrophyte species. Time course samples were collected for epiphytic chlorophyll, dry weight, and algal and diatom cell counts following cumulative agitation periods of 10, 30, 60, 90, and 120 s. Statistically identical removal efficiencies were found for all macrophyte host species. Mean removal time for over 88% removal efficiency was 40 ± 6 s.

Clay Dispersion in Relation to Sodicity, Electrolyte Concentration, and Mechanical Effects

AbstractClay dispersion is one of the major processes causing structural problems in lands irrigated with sodic waters. The dispersion characteristics of a group of prairie soils (Haploborolls) from southern Saskatchewan (Canada) were determined after reaction with solutions that had a range of sodium adsorption ratios [SAR = Na/(Ca/2)1/2, where concentrations are expressed in mmolc L−1], and electrolyte concentrations. When the input of mechanical energy was high (i.e., 16‐h shaking), a well‐defined threshold electrolyte concentration existed at each SAR, below which extensive clay dispersion occurred. The threshold concentration for dispersion ranged from 1 to 3 mmolc L−1 at SAR 0 and increased linearly as SAR increased to reach 21 to 50 mmolc L−1 at SAR 40. In contrast, when dispersion was measured after minimal shaking by hand, distinct thresholds were absent. Instead, dispersion increased gradually at each SAR as electrolyte concentration decreased. Threshold concentrations determined with low‐energy inputs are likely to be most indicative of field dispersibility. Such threshold values can be substantially lower than those measured using vigorous agitation techniques, particularly when sodicity levels are low. Our results do not support recent reports that silt dispersion is a better indicator of structural stability in the presence of exchangeable Na than is clay dispersion. Such findings are probably the result of an experimental artifact caused by the inappropriate use of Stokes' law in estimating the particle size distribution of soil suspensions. Simple tests of clay dispersibility in water or of aggregate stability may be useful in screening soils for sensitivity to sodic irrigation waters.

Gradient for D-glucose and linoleic acid uptake along the crypt-villus axis of rabbit jejunal brush border membrane vesicles.

Glucose uptake into jejunal brush border membrane (BBM) varies along the crypt-villus axis (CVA). In the present study, the question was addressed whether uptake of the essential long-chain fatty acid linoleic acid also varies along the CVA. Using agitation techniques, five jejunal enterocyte fractions were sequentially isolated from female New Zealand white rabbits. A sixth and final fraction of lower-villus/crypt cells was obtained by the scraping of the remaining jejunal mucosa. Cell fraction along the CVA was proven histologically, by noting decreasing alkaline phosphatase activities in sequentially isolated fractions, and by demonstrating [3H-methyl]thymidine uptake mainly in the final fraction of the lower villus/crypt cells. BBM vesicles were prepared from the upper, mid- and lower-villus/crypt enterocyte fractions, using differential centrifugation and divalent ion precipitation. D-Glucose uptake into each fraction showed an Na(+)-gradient dependent time-course "overshoot" with linear uptake to 15 s and a subsequent decline to a steady-state plateau. Varying D-glucose concentrations from 50-1000 microM demonstrated saturation kinetics of uptake, with maximal transport rates (Vmax) and Michaelis affinity constants (Km) varying between fractions; the Km and Vmax were both lowest in the upper-villus fraction. A linear relationship existed between linoleic acid concentration (25-200 microM) and uptake in each fraction. Linoleic acid uptake was equivalent in all fractions when expressed per mg protein, but when expressed in terms of the estimated minimal BBM, vesicle surface area uptake was greater in the upper- than in the lower-villus/crypt fractions. Thus, BBM vesicle uptake of both linoleic acid and glucose vary along the crypt-villus axis of the rabbit jejunum.

Mechanical effect on the stabilization of sol derived from Ti(i-OBu)4

Sol-gel synthesis of transition metal oxides via polymerization of molecular precursors such as alkoxides provides an alternative path to produce ceramic materials at moderate temperatures which are homogeneous and non-porous with high mechanical strength. Stabilization of sol is one of the critical factors in controlling the strucure of the final products and their processing properties. Parameters such as temperature, catalysts and additives are known to change the content of water in titanium tetra isobutoxide (TTIB) sol and hence the stability of the sol. Here some preliminary results are reported on how agitation techniques can stabilize TTIB sol with higher water/TTIB ratio.

On-line monitoring of flowing samples using solid phase microextraction-gas chromatography

The rapid sampling and concentration response of solid phase microextraction (SPME) facilitate the monitoring of organic analytes present in a flowing stream. It was determined that in addition to convection introduced by flow in the system, an efficient means of agitation is required to achieve rapid extractions. Three agitation techniques; magnetic mixing, intrusive mixing and sonication were tested. While magnetic stirring is inexpensive and easy to automate, it exhibited low mixing efficiency. Intrusive mixing allows efficient agitation but caused sample heating and is not easily amenable to on-line analysis. Sonication proved to be the most efficient and the most convenient means of agitation for sampling from flowing streams. For example, toluene, equilibrates in less then 1 min, which is very close to theoretical predictions assuming perfect agitation conditions. The on-line SPME-GC technique allows gas chromatography to be incorporated into a flow-injection analysis system.