Stromatolite-like Structures Within Microbially Laminated Sandstones of the Paleoarchean Moodies Group, Barberton Greenstone Belt, South Africa.

We report abundant small calcareous mounds associated with fossilized kerogenous microbial mats in tidal-facies sandstones of the predominantly siliciclastic Moodies Group (ca. 3.22 Ga) of the Barberton Greenstone Belt (BGB), South Africa and Eswatini. Most of the bulbous, internally microlaminated mounds are several centimeters in diameter and formed at the sediment-water interface contemporaneously with sedimentation. They originally consisted of Fe-Mg-Mn carbonate, which is now largely silicified; subtle internal compositional laminations are composed of organic matter and sericite. Their presence for >6 km along strike, their restriction to the inferred photic zone, and the internal structure suggest that mineral precipitation was induced by photosynthetic microorganisms. Similar calcareous mounds in this unit also occur within and on top of fluid-escape conduits, suggesting that carbonate precipitation may either have occurred abiogenically or involved chemotrophic metabolism(s) utilizing the oxidation of organic matter, methane, or hydrogen, the latter possibly generated by serpentinization of underlying ultramafic rocks. Alternatively or additionally, carbonate may have precipitated abiotically where heated subsurface fluids, sourced by the intrusion of a major Moodies-age sill, reached the tidal flats. In summary, precipitation mechanisms may have been variable; the calcareous mounds may represent "hybrid carbonates" that may have originated from the small-scale overlap of bioinduced and abiotic processes in space and time. Significantly, the widespread occurrence of these stromatolite-like structures in a fully siliciclastic, high-energy tidal setting broadens search criteria in the search for life on Mars while their possible hybrid origin challenges our ability to unambiguously identify a biogenic component.

Development and implementation of an analytical procedure for the quantification of natural and synthetic steroid hormones in whole surface waters.

Natural and synthetic steroid hormones are chronically released into aquatic spheres. Whereas knowledge on their combined mode of action and the cocktail effect are needed, only few multi-class methods address the challenge of their trace quantification in surface waters. The current study describes a sensitive multi-residue analytical strategy aiming to quantify 23 steroid hormones belonging to androgens, estrogens, glucocorticoids and progestogens in whole surface waters. The procedure relies on a two-step solid-phase extraction followed by an ultra-performance liquid chromatography separation coupled to tandem mass spectrometry detection (UPLC-MS/MS). Isotope dilution was implemented when possible in order to ensure the reliability of the measurement. The procedure was optimized toward the reliable quantification of the 23 target compounds at the predicted no-effect concentrations when existing or below the ng L-1 level. Satisfactory absolute global recoveries ≥ 77% were obtained for almost all compounds (21 out of 23) in intermediate precision conditions. Measurement errors were comprised between -27% and +17% for the great majority of compounds (21 out of 23) with standard deviations < 20% in intermediate precision conditions. Despite signal suppression was observed in water samples, satisfactory limits of quantification were achieved, ranging from 0.035 ng L-1 for 17alpha-ethinylestradiol to 1 ng L-1 for 6beta-hydroxycortisol and 6beta-hydroxydexamethasone. Abiotic stability was demonstrated for the great majority of target compounds (22 out of 23) in reference water samples stored at 4 ± 3 °C during 48 h, driving our sampling strategy. To demonstrate its fitness for purpose, the procedure was implemented in a preliminary monitoring survey of Belgian surface waters. As a result, 6 out of 23 target compounds were detected or quantified, showing a contamination by some estrogens and glucocorticoids at levels ranging from 0.1 to 0.9 ng L-1.

Rotating Binary Bose-Einstein Condensates and Vortex Clusters in Quantum Droplets.

Quantum droplets may form out of a gaseous Bose-Einstein condensate, stabilized by quantum fluctuations beyond mean field. Determining the ground state of a rotating binary condensate, we show that multiple singly quantized vortices may form in these droplets at moderate angular momenta in two dimensions. Droplets carrying these precursors of an Abrikosov lattice remain self-bound for certain timescales after switching off an initial harmonic confinement. Intriguingly, we find evidence of a metastable persistent current in these new types of binary condensates. We discuss how this finding can be used to experimentally generate vortex-carrying quantum droplets.

Increase in CFC-11 emissions from eastern China based on atmospheric observations.

The recovery of the stratospheric ozone layer relies on the continued decline in the atmospheric concentrations of ozone-depleting gases such as chlorofluorocarbons1. The atmospheric concentration of trichlorofluoromethane (CFC-11), the second-most abundant chlorofluorocarbon, has declined substantially since the mid-1990s2. A recently reported slowdown in the decline of the atmospheric concentration of CFC-11 after 2012, however, suggests that global emissions have increased3,4. A concurrent increase in CFC-11 emissions from eastern Asia contributes to the global emission increase, but the location and magnitude of this regional source are unknown3. Here, using high-frequency atmospheric observations from Gosan, South Korea, and Hateruma, Japan, together with global monitoring data and atmospheric chemical transport model simulations, we investigate regional CFC-11 emissions from eastern Asia. We show that emissions from eastern mainland China are 7.0 ± 3.0 (±1 standard deviation) gigagrams per year higher in 2014-2017 than in 2008-2012, and that the increase in emissions arises primarily around the northeastern provinces of Shandong and Hebei. This increase accounts for a substantial fraction (at least 40 to 60 per cent) of the global rise in CFC-11 emissions. We find no evidence for a significant increase in CFC-11 emissions from any other eastern Asian countries or other regions of the world where there are available data for the detection of regional emissions. The attribution of any remaining fraction of the global CFC-11 emission rise to other regions is limited by the sparsity of long-term measurements of sufficient frequency near potentially emissive regions. Several considerations suggest that the increase in CFC-11 emissions from eastern mainland China is likely to be the result of new production and use, which is inconsistent with the Montreal Protocol agreement to phase out global chlorofluorocarbon production by 2010.

Quantum Szilard Engine with Attractively Interacting Bosons.

We show that a quantum Szilard engine containing many bosons with attractive interactions enhances the conversion between information and work. Using an ab initio approach to the full quantum-mechanical many-body problem, we find that the average work output increases significantly for a larger number of bosons. The highest overshoot occurs at a finite temperature, demonstrating how thermal and quantum effects conspire to enhance the conversion between information and work. The predicted effects occur over a broad range of interaction strengths and temperatures.

Continued Emissions of the Ozone-Depleting Substance Carbon Tetrachloride From Eastern Asia.

Carbon tetrachloride (CCl4) is an ozone-depleting substance, accounting for about 10% of the chlorine in the troposphere. Under the terms of the Montreal Protocol, its production for dispersive uses was banned from 2010. In this work we show that, despite the controls on production being introduced, CCl4 emissions from the eastern part of China did not decline between 2009 and 2016. This finding is in contrast to a recent bottom-up estimate, which predicted a significant decrease in emissions after the introduction of production controls. We find eastern Asian emissions of CCl4 to be 16 (9-24) Gg/year on average between 2009 and 2016, with the primary source regions being in eastern China. The spatial distribution of emissions that we derive suggests that the source distribution of CCl4 in China changed during the 8-year study period, indicating a new source or sources of emissions from China's Shandong province after 2012.

Development of a multi-residue method for scrutinizing psychotropic compounds in natural waters.

The present work describes a multi-residue SPE-UPLC-MS/MS method aiming at the characterization of 68 compounds in natural waters, including parent compounds as well as their major metabolites and glucuronide conjugates. Development was conducted toward the quantitative determination of a broad range of analytes belonging to different class of psychotropic drugs such as benzodiazepines, antidepressants, stimulants, opiates and opioids, anticonvulsants, anti-dementia drugs, analgesic and anti-inflammatory drugs (as anthropic indicators) in the low ngL-1 range of concentration. Satisfactory extraction recoveries >70% were obtained for the majority of analytes (49 out of 68) allowing low limits of quantification. LOQ ranged between 0.1 and 17.8ngL-1 and were lower than 5ngL-1 for 94% of investigated analytes. Furthermore, addition of 25 isotopic labeled standards allowed to ensure reliability of the optimized method. Quantification errors were typically below 15% with relative standard variations <10% in intermediate precision conditions. Finally, the developed method was implemented in natural waters; sampling campaigns were conducted in the Seine River as a demonstration of the applicability and adequation of the method for its purpose. As a result, 48 out of 68 analytes were identified or quantified; some of them like memantine, rivastigmine, zolpidem 4-phenyl-carboxylic acid, zolpidem 6-carboxylic acid for one of the first time in surface waters. Among investigated psychotropic compounds and metabolites, tramadol, codeine, oxazepam, venlafaxine, O-desmethylvenlafaxine, gabapentin, carbamazepine and 10,11-dihydro-10,11-dihydroxycarbamazepine were found to be the most abundant.

Few-Body Precursor of the Higgs Mode in a Fermi Gas.

We demonstrate that an undamped few-body precursor of the Higgs mode can be investigated in a harmonically trapped Fermi gas. Using exact diagonalization, the lowest monopole mode frequency is shown to depend nonmonotonically on the interaction strength, having a minimum in a crossover region. The minimum deepens with increasing particle number, reflecting that the mode is the few-body analogue of a many-body Higgs mode in the superfluid phase, which has a vanishing frequency at the quantum phase transition point to the normal phase. We show that this mode mainly consists of coherent excitations of time-reversed pairs, and that it can be selectively excited by modulating the interaction strength, using, for instance, a Feshbach resonance in cold atomic gases.

Validation and uncertainties evaluation of an isotope dilution-SPE-LC-MS/MS for the quantification of drug residues in surface waters.

The present work describes the development and validation of a reference method conducted at the French National Institute of Metrology (LNE) for the quantitative determination of psychoactive compounds in the dissolved fraction of surface waters. More specifically an isotope dilution-SPE-LC-MS/MS based method has been implemented for the characterization of a broad range of analytes belonging to different classes of psychotropic drugs such as benzodiazepines, antidepressants, stimulants, opiates and opioids, anticonvulsants, anti-dementia drugs, analgesics as well as the anti-inflammatory drug diclofenac in the low ng L(-1) range of concentration. Full validation of the method was performed following procedures described by the French standard NF T90-210. Limits of quantification between 0.14 and 3.54 ng L(-1) were obtained. Method recoveries from 71 to 123% were observed with standard deviation below 10% in intermediate precision conditions. Accuracy was determined for every compound: measurement errors were between -4 and +1% and standard deviations in intermediate precision conditions were included within a 1-9% interval. Finally, measurement uncertainties were evaluated following the Guide to the expression of uncertainty in measurement (GUM). Expanded uncertainties (k=2) ranged from 2% for carbamazepine, EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) and venlafaxine to 17% for diazepam. The validated method was implemented to Seine river surface waters demonstrating its fitness for purpose. All compounds were detected and 22 out of 25 analytes were quantified. More specifically, measured concentration ranged from 0.39 ng L(-1) for MDMA (3,4-methylene-dioxy-N-methylamphetamine) to 182 ng L(-1) for gabapentine.

In vivo measurements and numerical analysis of the biomechanical characteristics of the human periodontal ligament.

The periodontal ligament is a complex tissue with respect to its biomechanical behaviour. It is important to understand the mechanical behaviour of the periodontal ligament during physiological loading in healthy patients as well as during the movement of the tooth in orthodontic treatment or in patients with periodontal disease, as these might affect the mechanical properties of the periodontal ligament (PDL). Up to now, only a limited amount of in vivo data is available concerning this issue. The aim of this study has been to determine the time dependent material properties of the PDL in an experimental in vivo study, using a novel device that is able to measure tooth displacement intraorally. Using the intraoral loading device, tooth deflections at various velocities were realised in vivo on human teeth. The in vivo investigations were performed on the upper left central incisors of five volunteers aged 21-33 years with healthy periodontal tissue. A deflection, applied at the centre of the crown, was linearly increased from 0 to 0.15mm in a loading period of between 0.1 and 5.0s. Individual numerical models were developed based on the experimental results to simulate the relationship between the applied force and tooth displacement. The numerical force/displacement curves were fitted to the experimental ones to obtain the material properties of the human PDL. For the shortest loading time of 0.1s, the experimentally determined forces were between 7.0 and 16.2N. The numerically calculated Young's modulus varied between 0.9MPa (5.0s) and 1.2MPa (0.1s). By considering the experimentally and numerically obtained force curves, forces decreased with increasing loading time. The experimental data gained in this study can be used for the further development and verification of a multiphasic constitutive law of the PDL.

Antiferromagnetic Heisenberg Spin Chain of a Few Cold Atoms in a One-Dimensional Trap.

We report on the deterministic preparation of antiferromagnetic Heisenberg spin chains consisting of up to four fermionic atoms in a one-dimensional trap. These chains are stabilized by strong repulsive interactions between the two spin components without the need for an external periodic potential. We independently characterize the spin configuration of the chains by measuring the spin orientation of the outermost particle in the trap and by projecting the spatial wave function of one spin component on single-particle trap levels. Our results are in good agreement with a spin-chain model for fermionized particles and with numerically exact diagonalizations of the full few-fermion system.

Density-Functional Theory for Strongly Correlated Bosonic and Fermionic Ultracold Dipolar and Ionic Gases.

We introduce a density functional formalism to study the ground-state properties of strongly correlated dipolar and ionic ultracold bosonic and fermionic gases, based on the self-consistent combination of the weak and the strong coupling limits. Contrary to conventional density functional approaches, our formalism does not require a previous calculation of the interacting homogeneous gas, and it is thus very suitable to treat systems with tunable long-range interactions. Because of its asymptotic exactness in the regime of strong correlation, the formalism works for systems in which standard mean-field theories fail.

Effect of archwire qualities and bracket designs on the force systems during leveling of malaligned teeth.

OBJECTIVES: The force systems during multiband treatment are influenced by the selection of the bracket-archwire combinations. Resin models replicated from casts reflecting the pretreatment intraoral situation of a patient's mandible were used to explore how different bracket systems and archwire qualities would affect the force systems developing during simulated orthodontic leveling of several malaligned teeth. MATERIALS AND METHODS: Leveling movements of the malaligned teeth 32, 33, and 34 were simulated using the orthodontic measurement and simulation system (OMSS). Two bracket types and three archwire qualities were compared, the former featuring a slot width of 0.022" (0.56 mm) and including one conventional (Freedom MIM Roth by ODS) and one passive self-ligating (Carriere MBT by ODS) design. Both were combined with three NiTi round 0.014" (0.36 mm) archwire products, two of them standard products (CuNiTi by Ormco; EuroArch by ODS) and one being a low-cost (NiTi Superelastic by Modern Arch) product. Measured parameters included force, torque, translation, and rotation. RESULTS: Archwire qualities are critical to the force systems developing in the leveling stage. On the other hand, the finding that lower force/torque values result in less tooth movement is not primarily due to wire selection. Our most striking result was that the ODS EuroArch wire resulted in very low force and torque values both with the conventional and with the self-ligating brackets. Almost identical patterns with these two bracket designs were found, and none of the measured parameters revealed a significant advantage for any of the bracket-archwire combinations over the others. CONCLUSION: In our experimental simulations of tooth leveling, wire-quality selection was found to be a key modifier of force, torque, translation, and rotation. Clearly, however, neither the wire qualities nor the bracket designs made a decisive difference to the amounts of leveling movement induced to malaligned teeth; other factors like tooth class or nature of the malalignment seem to be more important in this regard. A therapeutic benefit of self-ligating over conventional brackets was not demonstrable.

Growth in stratospheric chlorine from short-lived chemicals not controlled by the Montreal Protocol.

We have developed a chemical mechanism describing the tropospheric degradation of chlorine containing very short-lived substances (VSLS). The scheme was included in a global atmospheric model and used to quantify the stratospheric injection of chlorine from anthropogenic VSLS ( ClyVSLS) between 2005 and 2013. By constraining the model with surface measurements of chloroform (CHCl3), dichloromethane (CH2Cl2), tetrachloroethene (C2Cl4), trichloroethene (C2HCl3), and 1,2-dichloroethane (CH2ClCH2Cl), we infer a 2013 ClyVSLS mixing ratio of 123 parts per trillion (ppt). Stratospheric injection of source gases dominates this supply, accounting for ∼83% of the total. The remainder comes from VSLS-derived organic products, phosgene (COCl2, 7%) and formyl chloride (CHClO, 2%), and also hydrogen chloride (HCl, 8%). Stratospheric ClyVSLS increased by ∼52% between 2005 and 2013, with a mean growth rate of 3.7 ppt Cl/yr. This increase is due to recent and ongoing growth in anthropogenic CH2Cl2-the most abundant chlorinated VSLS not controlled by the Montreal Protocol.

Comparison of shear bond strength of plastic and ceramic brackets.

OBJECTIVES: The purpose of this in vitro study is to compare the shear bond strength of various esthetic brackets used in conjunction with two different adhesive systems. METHODS: Five non-silanized ceramic brackets (Aspire Gold/Forestadent, Clarity™/3M Unitek, CLEAR/Adenta, Contour Twin/ODS, QuicKlear/Forestadent) and four plastic brackets (Aesthetik-Line®/Forestadent, Brillant®/Forestadent, Composite Clear®/ODS, Elegance®/Dentaurum) were bonded either with Transbond™ XT (3M Unitek, Monrovia, CA, USA) or with ConTec SE (Dentaurum, Ispringen, Germany) to bovine permanent mandibular incisors. Twelve specimens were tested in each group, thus, bonding 60 ceramic and 48 plastic brackets with either adhesive to a total of 216 teeth. Shear bond strength was measured in accordance with the DIN 13990-2 standard governing test methods for the entire attachment-adhesive-enamel system. The fracture surfaces resulting from shear-induced debonding were analyzed via light microscopy. RESULTS: The combinations Clarity™ + Transbond™ XT, CLEAR® + Transbond™ XT, and Contour Twin + Transbond™ XT exhibited shear bond strengths of over 10 MPa. The Adhesive Remnant Index scores of the various bracket types varied widely according to the different bracket-base designs. No enamel fractures were observed. CONCLUSION: Some bracket-adhesive combinations in this study attained shear bond strengths approaching those of metal brackets. The risk of debonding-related enamel defects is comparable with different esthetic bracket combinations. Manufacturers' recommendations for the adhesive systems to be used with their brackets should be strictly adhered to.

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique.

OBJECTIVES: The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1. MATERIALS AND METHODS: Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth. RESULTS: Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region. CONCLUSIONS: These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system. CLINICAL RELEVANCE: These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.

Numerical simulation and biomechanical analysis of an orthodontically treated periodontally damaged dentition.

BACKGROUND AND OBJECTIVE: Once periodontitis has been completely resolved, one common follow-up method is to carry out orthodontic treatment to take advantage of the residual bone, i.e., via tooth intrusion. In this study, the biomechanical behavior of teeth in a reduced periodontium was studied by numerically simulating upper-incisor intrusion accomplished with various orthodontic mechanics. MATERIALS AND METHODS: Using the finite element method, a patient-customized 3D model of a periodontally reduced dentition was generated in order to simulate tooth movement. The morphology of this upper-jaw model was derived from cone-beam computed tomography (CBCT) datasets of four patients. Material parameters were adopted from previous investigations, including teeth (E=20 GPa), periodontal ligament (PDL) (bilinear elastic; E1=0.05 MPa; E2=0.20 MPa; ε12=7%), and bone (homogeneous, isotropic; E=2 GPa). Two intrusion scenarios were used, the first drawing from Burstone's segmented-arch technique to intrude four splinted incisors at a time, and the second one using cantilevers to intrude single incisors. The aforementioned PDL material parameters were varied in several ways to simulate different biological and biomechanical states of PDL. All simulations were recalculated with an idealized, periodontally intact model to assess the effect of bone loss by way of comparison. RESULTS: Single-tooth intrusion via cantilever mechanics was accompanied by less rotation than the segmented-arch approach. Both intrusion systems involved significantly greater degrees of tooth displacement and PDL load in the periodontally reduced model. CONCLUSION: Periodontally reduced dentitions are associated with an increased load on periodontal tissue. This can be counteracted by reducing orthodontic force levels and by selecting mechanics that do not harm the tissue. In so doing, the use of numerical methods may greatly facilitate individualized computer-aided treatment-planning strategies.

Total current blockade in an ultracold dipolar quantum wire.

Cold-atom systems offer a great potential for the future design of new mesoscopic quantum systems with properties that are fundamentally different from semiconductor nanostructures. Here, we investigate the quantum-gas analogue of a quantum wire and find a new scenario for the quantum transport: Attractive interactions may lead to a complete suppression of current in the low-bias range, a total current blockade. We demonstrate this effect for the example of ultracold quantum gases with dipolar interactions.

Material testing of reconditioned orthodontic brackets.

OBJECTIVE: While all manufacturers of orthodontic brackets label these products for single use, there are commercial providers offering bracket reconditioning (or "recycling"). We conducted this study to investigate the effects of different recycling techniques on material-related parameters in orthodontic brackets, aiming to derive indications for clinical use and conclusions about the biocompatibility, longevity, and application of recycled brackets. MATERIALS AND METHODS: New metal brackets (equilibrium(®); Dentaurum, Ispringen, Germany) were compared to brackets recycled by different techniques, including direct flaming with a Bunsen burner, chemical reconditioning in an acid bath, a commercial unit (Big Jane; Esmadent, IL, USA), and outsourcing to a company (Ortho Clean, Dellstedt, Germany). Material-related examinations included the following: (1) corrosion behavior by static immersion testing and use of a mass spectrometer to determine nickel-ion concentrations in the corrosive medium, (2) surface features in scanning electron micrographs before and after corrosion testing, (3) Vickers hardness using a hardness testing machine, (4) shear bond strength as defined in DIN 13990-1, (5) dimensional stability of the bracket slots by light microscopy, and (6) frictional loss as assessed by an orthodontic measurement and simulation system (OMSS). Each examination was performed on ten brackets. Student's t-test was used for statistical analysis. RESULTS: Compared to the new brackets, those recycled in an acid bath or by a commercial provider revealed significant dimensional changes (p<0.05). Corrosion on the recycled brackets varied according to the recycling techniques employed. The group of brackets recycled by one company revealed hardness values that differed from those of all the other groups. No significant differences were observed in nickel-ion release, frictional loss, and shear bond strength. CONCLUSION: Recycling was found to significantly reduce the corrosion resistance and dimensional stability of orthodontic brackets. As the savings generated by recycling do not justify the risks involved, the practice of labeling orthodontic brackets for single use remains a responsible precaution that safeguards patients and orthodontists against definite risks.

Torque capabilities of self-ligating and conventional brackets under the effect of bracket width and free wire length.

OBJECTIVES: To numerically investigate the torque capacity of conventional and self-ligating brackets under the effect of varying bracket width and free wire length. MATERIAL AND METHODS: Finite element models of three kinds of orthodontic brackets in the 0.022-inch slot size were investigated: Discovery, Damon 3MX, Speed. Additionally, finite element (FE) models of Speed and Damon brackets were generated with the same width as the Discovery. From the left upper incisor to the right upper canine, four brackets each were modelled. The total wire length at the upper right incisor was kept constant at 12 mm for all brackets types. For the Discovery brackets, the wire length was increased from 12 to 16 mm in 2-mm steps. A torque of 20° was applied to the upper right incisor with 0.46 × 0.64 mm(2) (0.018″ × 0.025″) and 0.48 × 0.64 mm(2) (0.019″ × 0.025″) wires. Wires made of stainless steel, titanium molybdenum and nickel titanium were studied. Torque angle/moment characteristics were recorded. RESULTS: Wider brackets showed more torque control capability (e.g. Discovery: 10.6 Nmm, Damon: 9.2 Nmm, Speed: 4.0 Nmm for the NiTi wire). Even with the same width as the Discovery bracket, Damon and Speed brackets showed lower torque capability than the Discovery bracket. Increasing the free wire length decreased the torsional stiffness of the wire and thus decreased the torque capability. CONCLUSION: The results showed that the bracket design has less influence on the torquing moment than other parameters, such as bracket width, free wire length, wire/slot play or misalignment.