Assessment of a highly-filled flowable composite for the repair of indirect composites.

PURPOSE: To compare the shear-bond-strength (SBS) of a highly-filled-flowable composite (HFFC) and a paste-type composite for indirect composite repair and to evaluate the effect of different surface treatments (ST), concerning the composite repair protocol. METHODS: Eighty-four 5 × 5 × 2 mm cylindrical specimens were prepared using Gradia Plus and SR Nexco indirect composite materials. The samples were thermocycled 5,000 times. According to the ST, the samples were divided into three groups (control, bur, and air-abrasion). After ST, the sample subgroups were divided into two sub-groups according to the repair material: paste-type composite and HFFC (n = 7). Another 5,000 cycles of aging were performed. SBS values were measured with a universal testing machine (Shimadzu, Japan). Shapiro-Wilk, 3-way ANOVA, and Tukey HSD test were used to evaluate data (P < 0.05). RESULTS: ST was considered significant for SBS (P < 0.001). The mean values were (13.9 ± 5.7), (17.0 ± 6.4), (20.4 ± 4.9) MPa for the control, bur and phosphoric acid, and air-abrasion groups, respectively. The surface treatment and repair material interaction was considered significant for SBS (P = 0.044). The highest mean bond strength (24.5 ± 4.5 MPa) was observed for the interaction of SR Nexco, air-abrasion ST, and HFFC repair. CONCLUSION: Repairing with HFFC following air abrasion might enhance the SBS for indirect composite restorations.

Characterization of MSW incineration bottom ash for use as structural fill in reinforced soil structures: Geoenvironmental, geotechnical and economical assessment.

The study presents the geoenvironmental and geotechnical characterization of MSW incineration bottom ash (IBA) and examines its reuse as structural fill in reinforced soil structures (RSS).The suitability of reuse has been assessed with regard to international regulatory standards. The prime focus of the work remains on evaluating the pullout response of geosynthetic reinforcements through IBA fill to determine the interaction coefficient, which has never been addressed in the literature. The economic viability of using IBA instead of locally available river sand for a 12 m high MSE wall is also established. The column leaching test results confirm that IBA can be utilized in RSS with suitable design measures. The geotechnical investigation shows that IBA is a well-graded, non-plastic lightweight material with adequate drainage and high shear strength. The pullout test results demonstrate that the interaction coefficient of polymeric strips and geogrid in IBA (0.73-1.53 and 0.79-1.91, respectively) is comparable or higher to materials conventionally used as structural fill in RSS, indicating adequate bondage between IBA and geosynthetic reinforcement. Further, it is estimated that using IBA as a substitute for available river sand in the vicinity can potentially reduce the overall RSS project cost by 15-20%, even if IBA has to be transported 50 km away from the project site.

Assessment of Caries-Affected Dentin Adhesive Interface Treated with Contemporary Conditioning Techniques.

Objective: The aim of this study was to assess shear bond strength (SBS) and failure analysis of adhesion of composite resin (CR) to caries-affected dentin (CAD) pretreated with the Er,Cr:YSGG (ECY) laser, photodynamic therapy (PDT), and etch and rinse (ER) used for cavity disinfection. Materials and methods: Methods used in this study included scanning electron microscopy (SEM), SBS analysis, failure analysis, and digital microscopy. The methods were adopted to assess bond integrity, CAD interface, smear layer, and hybridization. Thirty human third molars assessed clinically and having scores of 4 and 5 based on International Caries Detection and Assessment System (ICDAS) criteria were inspected. Infected dentin was removed. Dentin that was hard and stained pink was categorized as CAD. Ten samples were used in each group for pretreatment of CAD. Ten samples of healthy dentin [sound dentin (SD)] were collected separately and taken as controls. Samples were divided into the following groups: group 1: SD+ER; group 2: CAD+ER; group 3: CAD+ECY; and group 4: CAD+PDT after the pretreatment bonding agent was applied and the restorative procedure was performed using CR. Results: CAD conditioned with PDT before bonding to CR demonstrated the lowest SBS values (11.22 ± 0.77 MPa), whereas the highest SBS values were observed in the SD surface treated with ER (18.25 ± 1.22 MPa). In CAD and SD pretreated with ER, majority of failure modes were cohesive failure and admixed failure, whereas in CAD pretreated with PDT and the ECY laser, the adhesive failure mode was pertinent. Conclusions: The use of the ECY laser and PDT on CAD for cavity disinfection does not have potential for application in clinical settings as it decreases bond integrity of CR. Moreover, the ER pretreatment method for CAD and SD remains the gold standard.

Contrast Agent-Free Assessment of Blood Flow and Wall Shear Stress in the Rabbit Aorta using Ultrasound Image Velocimetry.

Blood flow velocity and wall shear stress (WSS) influence and are influenced by vascular disease. Their measurement is consequently useful in the laboratory and clinic. Contrast-enhanced ultrasound image velocimetry (UIV) can estimate them accurately but the need to inject contrast agents limits utility. Singular value decomposition and high-frame-rate imaging may render contrast agents dispensable. Here we determined whether contrast agent-free UIV can measure flow and WSS. In simulation, accurate measurements were achieved with a signal-to-noise ratio of 13.5 dB or higher. Signal intensity in the rabbit aorta increased monotonically with mechanical index; it was lowest during stagnant flow and uneven across the vessel. In vivo measurements with contrast-free and contrast-enhanced UIV differed by 4.4% and 1.9% for velocity magnitude and angle and by 9.47% for WSS. Bland-Altman analysis of waveforms revealed good agreement between contrast-free and contrast-enhanced UIV. In five rabbits, the root-mean-square errors were as low as 0.022 m/s (0.81%) and 0.11 Pa (1.7%). This study indicates that with an optimised protocol, UIV can assess flow and WSS without contrast agents. Unlike contrast-enhanced UIV, contrast-free UIV could be routinely employed.

Transperineal ultrasound shear-wave elastography is a reliable tool for assessment of the elastic properties of the levator ani muscle in women.

Our main objective was to assess the intraoperator intersession reproducibility of transperineal ultrasound Shear Wave Elastography (SWE) to measure the levator ani muscle (LAM) elastic properties. Secondary objective was to compare reproducibility when considering the mean of three consecutives measurements versus one. In this prospective study involving non-pregnant nulliparous women, two visits were planned, with a measurement of the shear modulus (SM) on the right LAM at rest, during Valsalva maneuver and maximal contraction. Assessments were done with a transperineal approach, using an AIXPLORER device with a linear SL 18-5 (5-18 MHz) probe. For each condition, 3 consecutive measures were performed at each visit. The mean of the three measures, then the first one, were considered for the reproducibility by calculating intraclass correlation coefficient (ICC), and coefficient of variation (CV). Twenty women were included. Reproducibility was excellent when considering the mean of the 3 measures at rest (ICC = 0.90; CV = 15.7%) and Valsalva maneuver (ICC = 0.94; CV = 10.6%), or the first of the three measures at rest (ICC = 0.87; CV = 18.6%) and Valsalva maneuver (ICC = 0.84; CV = 19.9%). Reproducibility was fair for measurement during contraction. Transperineal ultrasound SWE is a reliable tool to investigate LAM elastic properties at rest and during Valsalva maneuver.

Investigation of ANN architecture for predicting shear strength of fiber reinforcement bars concrete beams.

In this paper, an extensive simulation program is conducted to find out the optimal ANN model to predict the shear strength of fiber-reinforced polymer (FRP) concrete beams containing both flexural and shear reinforcements. For acquiring this purpose, an experimental database containing 125 samples is collected from the literature and used to find the best architecture of ANN. In this database, the input variables consist of 9 inputs, such as the ratio of the beam width, the effective depth, the shear span to the effective depth, the compressive strength of concrete, the longitudinal FRP reinforcement ratio, the modulus of elasticity of longitudinal FRP reinforcement, the FRP shear reinforcement ratio, the tensile strength of FRP shear reinforcement, the modulus of elasticity of FRP shear reinforcement. Thereafter, the selection of the appropriate architecture of ANN model is performed and evaluated by common statistical measurements. The results show that the optimal ANN model is a highly efficient predictor of the shear strength of FRP concrete beams with a maximum R2 value of 0.9634 on the training part and an R2 of 0.9577 on the testing part, using the best architecture. In addition, a sensitivity analysis using the optimal ANN model over 500 Monte Carlo simulations is performed to interpret the influence of reinforcement type on the stability and accuracy of ANN model in predicting shear strength. The results of this investigation could facilitate and enhance the use of ANN model in different real-world problems in the field of civil engineering.

Dentin Conditioning Using Different Laser Prototypes (Er,Cr:YSGG; Er:YAG) on Bond Assessment of Resin-modified Glass Ionomer Cement.

AIM: The aim of this study was to evaluate and compare various conditioning regimes (laser and conventional) on shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) bonded to dentin. MATERIALS AND METHODS: Sixty non-carious intact maxillary molars were cleaned, isolated, and randomly divided into six groups (n = 10). Before randomization, the dentin surface was exposed and finished. Samples in group I were conditioned using Er,Cr:YSGG laser (ECYL). Specimens in group II were conditioned using Er:YAG laser (EYL), and the dentin surfaces of specimens in group III and group IV were conditioned using cavity conditioner and K930. Similarly, the samples in group V and group VI were surface treated using 17% EDTA and total etch. All samples were bonded with RMGIC following conditioning regime. For SBS testing, the samples were placed in universal testing machine. A fracture analysis of debonded surfaces was evaluated using stereomicroscope at 40× magnification. Means and standard deviations (SDs) were calculated using analysis of variance (ANOVA) and Tukey's post hoc test at a significant level of p < 0.05. RESULTS: The maximum bond strength values were observed in group VI total etch (23.85 ± 3.67). The lowest bond strength was displayed in laser dentin group II conditioned by EYL (11.65 ± 2.77). Dentin conditioned with ECYL, cavity conditioner, K930 conditioner, and 17% ethylenediaminetetraacetic acid (EDTA) were found to be comparable, p > 0.05. Cohesive failure was dominant among experimental groups. CONCLUSION: Er,Cr:YSGG laser has a potential to be recommended for dentin conditioning prior to application of RMGIC. CLINICAL SIGNIFICANCE: Dentin conditioning enhances adhesion of RMGIC for improved prognosis and treatment outcome.

[Comparative assessment of the human blood plasma impact on the properties of various adhesive systems]. / Sravnitel'naya otsenka stepeni vliyaniya plazmy krovi cheloveka na svoistva razlichnykh adgezivnykh sistem.

OBJECTIVE: To assess the degree of influence of human blood plasma simulating dentinal fluid on the composite resin adhesion to dental hard tissues. MATERIAL AND METHODS: The strength of the adhesive bond between the composite material and dental hard tissues was studied using a shear test machine Zwick Roell Z 010 («Zwick¼, Germany) on extracted human teeth. XP Bond one-component adhesive system and XENOV self-etching adhesive system (DENTSPLY, Germany), high-definition micrometric restoration material Esthet X HD (DENTSPLY, Germany), as well as centrifuged blood plasma were used. RESULTS: Adhesion strength decreased by 26-78% when blood plasma weighing from 0.2 to 2.0 mg mixed up the self-etching system (weight 6.6 mg). A significant decrease in the adhesion force occurred when plasma with a mass of 0.7 mg or more mixed up with the monomer (a decrease in adhesion by 19.1%). A critical decrease in the adhesion force (43% or more) occurred with the mixture of blood plasma weighing 2.0 mg or more.

Mechanical Model for Catch-Bond-Mediated Cell Adhesion in Shear Flow.

Catch bond, whose lifetime increases with applied tensile force, can often mediate rolling adhesion of cells in a hydrodynamic environment. However, the mechanical mechanism governing the kinetics of rolling adhesion of cells through catch-bond under shear flow is not yet clear. In this study, a mechanical model is proposed for catch-bond-mediated cell adhesion in shear flow. The stochastic reaction of bond formation and dissociation is described as a Markovian process, whereas the dynamic motion of cells follows classical analytical mechanics. The steady state of cells significantly depends on the shear rate of flow. The upper and lower critical shear rates required for cell detachment and attachment are extracted, respectively. When the shear rate increases from the lower threshold to the upper threshold, cell rolling became slower and more regular, implying the flow-enhanced adhesion phenomenon. Our results suggest that this flow-enhanced stability of rolling adhesion is attributed to the competition between stochastic reactions of bonds and dynamics of cell rolling, instead of force lengthening the lifetime of catch bonds, thereby challenging the current view in understanding the mechanism behind this flow-enhanced adhesion phenomenon. Moreover, the loading history of flow defining bistability of cell adhesion in shear flow is predicted. These theoretical predictions are verified by Monte Carlo simulations and are related to the experimental observations reported in literature.

Assessment of neonatal, cord, and adult platelet granule trafficking and secretion.

Despite the transient hyporeactivity of neonatal platelets, full-term neonates do not display a bleeding tendency, suggesting potential compensatory mechanisms which allow for balanced and efficient neonatal hemostasis. This study aimed to utilize small-volume, whole blood platelet functional assays to assess the neonatal platelet response downstream of the hemostatic platelet agonists thrombin and adenosine diphosphate (ADP). Thrombin activates platelets via the protease-activated receptors (PARs) 1 and 4, whereas ADP signals via the receptors P2Y1 and P2Y12 as a positive feedback mediator of platelet activation. We observed that neonatal and cord blood-derived platelets exhibited diminished PAR1-mediated granule secretion and integrin activation relative to adult platelets, correlating to reduced PAR1 expression by neonatal platelets. PAR4-mediated granule secretion was blunted in neonatal platelets, correlating to lower PAR4 expression as compared to adult platelets, while PAR4 mediated GPIIb/IIIa activation was similar between neonatal and adult platelets. Under high shear stress, cord blood-derived platelets yielded similar thrombin generation rates but reduced phosphatidylserine expression as compared to adult platelets. Interestingly, we observed enhanced P2Y1/P2Y12-mediated dense granule trafficking in neonatal platelets relative to adults, although P2Y1/P2Y12 expression in neonatal, cord, and adult platelets were similar, suggesting that neonatal platelets may employ an ADP-mediated positive feedback loop as a potential compensatory mechanism for neonatal platelet hyporeactivity.

Shear-thinning behaviour of blood in response to active hyperaemia: Implications for the assessment of arterial shear stress-mediated dilatation.

NEW FINDINGS: What is the central question of this study? Quantitative values of shear rate-specific blood viscosity and shear stress in the human macrovasculature in response to exercise hyperaemia are unknown. What is the main finding and its importance? Using the handgrip exercise model, we showed that an increase in brachial artery shear rate led to a decrease in blood viscosity, despite concomitant haemoconcentration. This shear-thinning behaviour of blood, secondary to increased erythrocyte deformability, blunted the expected increase in brachial artery shear stress based on shear rate prediction. Our data yield new insights into the magnitude and regulation of macrovascular blood viscosity and shear stress in physiological conditions of elevated metabolic demand and blood flow in humans. ABSTRACT: Blood viscosity is a well-known determinant of shear stress and vascular resistance; however, accurate quantitative assessments of shear rate-specific blood viscosity in the macrovasculature in conditions of elevated blood flow are inherently difficult, owing to the shear-thinning behaviour of blood. Herein, 12 men performed graded rhythmic handgrip exercise at 20, 40, 60 and 80% of their maximal workload. Brachial artery shear rate and diameter were measured via high-resolution Duplex ultrasound. Blood was sampled serially from an i.v. cannula in the exercising arm for the assessment of blood viscosity (cone-plates viscometer). We measured ex vivo blood viscosity at 10 discrete shear rates within the physiological range documented for the brachial artery in basal and exercise conditions. Subsequently, the blood viscosity data were fitted with a two-phase exponential decay, facilitating interpolation of blood viscosity values corresponding to the ultrasound-derived shear rate. Brachial artery shear rate and shear stress increased in a stepwise manner with increasing exercise intensity, reaching peak values of 940 ± 245 s-1 and 3.68 ± 0.92 Pa, respectively. Conversely, brachial artery shear rate-specific blood viscosity decreased with respect to baseline values throughout all exercise intensities by ∼6-11%, reaching a minimal value of 3.92 ± 0.35 mPa s, despite concomitant haemoconcentration. This shear-thinning behaviour of blood, secondary to increased erythrocyte deformability, blunted the expected increase in shear stress based on shear rate prediction. Consequently, the use of shear stress yielded a higher slope for the brachial artery stimulus versus dilatation relationship than shear rate. Collectively, our data refute the use of shear rate to infer arterial shear stress-mediated processes.

The key events of thrombus formation: platelet adhesion and aggregation.

Thrombus formation is a complex, dynamic and multistep process, involving biochemical reactions, mechanical stimulation, hemodynamics, and so on. In this study, we concentrate on its two crucial steps: (i) platelets adhered to a vessel wall, or simply platelet adhesion, and (ii) platelets clumping and arrested to the adherent platelets, named platelet aggregation. We report the first direct simulation of three modes of platelet adhesion, detachment, rolling adhesion and firm adhesion, as well as the formation, disintegration, arrestment and consolidation of platelet plugs. The results show that the bond dissociation in the detachment mode is mainly attributed to a high probability of rupturing bonds, such that any existing bond can be quickly ruptured and all bonds would be completely broken. In the rolling adhesion, however, it is mainly attributed to the strong traction from the shear flow or erythrocytes, causing that the bonds are ruptured at the trailing edge of the platelet. The erythrocytes play an important role in platelet activities, such as the formation, disintegration, arrestment and consolidation of platelet plugs. They exert an aggregate force on platelets, a repulsion at a near distance but an attraction at a far distance to the platelets. This aggregate force can promote platelets to form a plug and/or bring along a part of a platelet plug causing its disintegration. It also greatly influences the arrestment and consolidation of platelet plugs, together with the adhesive force from the thrombus.

Assessment of microcracks and shear bond strength after debonding orthodontic ceramic brackets on enamel priorly etched by different Er,Cr:YSGG and Er:YAG laser settings without acid application: An in vitro study.

BACKGROUND DATA: Enamel microcrack formation has a high incidence after mechanical debonding of ceramic brackets. This may be due to high delivered shear bond strength values when enamel is priorly etched by phosphoric acid. It is still not well elucidated in the literature if laser etching affects enamel the same way. The aim of the research was to analyze different Er,Cr:YSGG and Er:YAG laser etching settings as an alternative to phosphoric acid, in an attempt to prevent enamel microcrack formation during laser etching and mechanical debonding, while reducing the shear bond strength to the minimal clinical acceptable value. MATERIALS AND METHODS: One hundred and thirty-three teeth were randomly divided into 7 experimental groups according to their etching modalities. Settings used for enamel etching were in Er,Cr:YSGG groups: Er,Cr:YSGG (1.5Watt, W/20Hertz, Hz); Er,Cr:YSGG (1.5W/15Hz) and Er,Cr:YSGG (2W/20Hz) and settings used for enamel etching in Er:YAG groups were: Er:YAG (60 millijoules, mJ), Er:YAG (80mJ) and Er:YAG (100mJ). Group C etched with 37% phosphoric acid served as control. Microscopic analysis was performed to assess presence of enamel microcracks. Shear bond strength was evaluated after thermocycling using Weibull survival analysis. RESULTS: All groups showed a reduction in additional microcracks after debonding when compared to control, but only group Er:YAG (60mJ) exhibited a statistically significant difference. Groups Er:YAG (80mJ), control and Er:YAG (100mJ) showed respectively the highest probability of survival at various stress levels followed by groups Er:YAG (60mJ); Er,Cr:YSGG (1.5W/15Hz); Er,Cr:YSGG (2W/20Hz) and Er,Cr:YSGG (1.5W/20Hz) that presented a relatively considerable risk of failure, even at low stress levels. CONCLUSIONS: When considering reduction of enamel microcrack formation and clinical acceptable shear bond strength, none of the groups succeeded both. Etching by Er:YAG (60mJ) and Er,Cr:YSGG (1.5W/15Hz), showed the least overall microcrack incidence between groups, but Er:YAG (60mJ) displayed significant reduction compared to phosphoric acid. However, etching by Er:YAG (80mJ) had the most predictable results in term of shear bond strength.

Microscale assessment of corneal viscoelastic properties under physiological pressures.

The micromechanical behaviour of the cornea is important for understanding and modelling of many ocular disorders. Whereas inflation testing has been utilised to determine the bulk mechanical properties of the cornea under physiological pressures, micromechanical testing has been limited to unpressurised corneal samples. In this study the micromechanical properties of pressurised porcine corneas were determined using oscillatory nanoindentation coupled with a custom inflation method. Inflation was conducted in phosphate buffered saline (PBS) and tissue culture (TC) solutions. The shear storage modulus (G') and shear loss modulus (G") was determined for corneas inflated corneas with PBS and TC. Central corneal thickness (CCT) was monitored during the inflation (0-60 mmHg). Elastic modulus (E) was also calculated and quantitatively mapped for corneas. The results showed that G' at 15 mmHg was 86.18 ± 16 kPa and 88.86 + 13.54 kPa inflated by PBS and TC respectively. These values increased 3.2 times in an approximate linear relationship to 60 mmHg. G″ at 15 mmHg was 12.5 ± 2.5 kPa and 13.54 + 1.9 kPa inflated by PBS and TC respectively. G″ increased 1.9 times in an approximate linear relationship to 60 mmHg. No significant change was noticed in viscoelastic properties of corneas inflated by TC for 4 h whereas 4 h of hydration on PBS affected the mechanical properties. The central corneal region was found to be stiffer than in peripheral region. Mapping of elasticity revealed a symmetrical distribution of properties that varied with inflation. Our method has potential for measurement of viscoelastic properties of corneas in conditions where there have been localised changes in mechanical properties such as keratoconus.

Bidirectional Ultrasound Elastographic Imaging Framework for Non-invasive Assessment of the Non-linear Behavior of a Physiologically Pressurized Artery.

Studies of non-destructive bidirectional ultrasound assessment of non-linear mechanical behavior of the artery are scarce in the literature. We hereby propose derivation of a strain-shear modulus relationship as a new graphical diagnostic index using an ultrasound elastographic imaging framework, which encompasses our in-house bidirectional vascular guided wave imaging (VGWI) and ultrasound strain imaging (USI). This framework is used to assess arterial non-linearity in two orthogonal (i.e., longitudinal and circumferential) directions in the absence of non-invasive pressure measurement. Bidirectional VGWI estimates longitudinal (µL) and transverse (µT) shear moduli, whereas USI estimates radial strain (ɛr). Vessel-mimicking phantoms (with and without longitudinal pre-stretch) and in vitro porcine aortas under static and/or dynamic physiologic intraluminal pressure loads were examined. ɛr was found to be a suitable alternative to intraluminal pressure for representation of cyclic loading on the artery wall. Results revealed that µT values of all samples examined increased non-linearly with εr magnitude and more drastically than µL, whereas µL values of only the pre-stretched phantoms and aortas increased with ɛr magnitude. As a new graphical representation of arterial non-linearity and function, strain-shear modulus loops derived by the proposed framework over two consecutive dynamic loading cycles differentiated sample pre-conditions and corroborated direction-dependent non-linear mechanical behaviors of the aorta with high estimation repeatability.

Acoustoelasticity Analysis of Transient Waves for Non-Invasive In Vivo Assessment of Urinary Bladder.

A non-invasive method for measurement of the bladder wall nonlinear elastic behavior is presented. The method is based on acoustoelasticity modeling of the elasticity changes in bladder tissue modulus at different volumetric strain levels. At each volume, tissue strain is obtained from the real-time ultrasound images. Using acoustic radiation force, a transient Lamb wave is excited on the bladder wall and instantaneous modulus of shear elasticity is obtained from the 2-D Fourier analysis of the spatial-temporal dispersion maps. Measured elasticity and strain data are then used in an acoustoelasticity formulation to obtain the third order elastic coefficient, referred to as nonlinearity parameter A, and initial resting elasticity µ0. The method was tested in ex vivo porcine bladder samples (N = 9) before and after treatment with formalin. The estimated nonlinearity parameter, A, was significantly higher in the treated samples compared to intact (p < 0.00062). The proposed method was also applied on 16 patients with neurogenic bladders (10 compliant and 6 non-compliant subjects). The estimated nonlinearity parameter A was significantly higher in the non-compliant cases compared to the compliant (p < 0.0293). These preliminary results promise a new method for non-invasive evaluation of the bladder tissue nonlinearity which may serve as a new diagnostic and prognostic biomarker for management of the patients with neurogenic bladders.

Magnetic Resonance Elastography in the Assessment of Acute Effects of Kinesio Taping on Lumbar Paraspinal Muscles.

BACKGROUND: Kinesio tape (KT) is an elastic therapeutic tape used for treating sports-related injuries and a number of other disorders. To date, the objective evidence to link pathophysiological effects and actual reactions triggered by KT is limited. PURPOSE: To explore the effect of KT on the lumbar paraspinal muscles by magnetic resonance (MR) elastography. STUDY TYPE: Prospective observational study. POPULATION: Sixty-six asymptomatic volunteers with 31 women and 35 men. FIELD STRENGTH/SEQUENCE: 3.0T MRI and elastography with vibration frequency of 120 Hz. ASSESSMENT: The 5-cm-width KT with full tension was placed on a single side of the lumbar paraspinal muscle. The taping side and adhering direction were randomly decided. Two rectangular regions of interest (ROIs) of 5- and 2.5-cm-width were positioned at the bilateral paraspinal regions from the L2 to L4 level on the confidence map of MR elastography before and after KT taping. The mean shear stiffness values of the ROIs at the superficial, middle, and deep depths were recorded; then the differences between the taping and reference sides were calculated. STATISTICAL TESTS: Paired t-test and Pearson correlations were used to evaluate the stiffness changes after KT application and intraoperator errors of the stiffness measures on the reference side, respectively. RESULTS: A significant decrease in the muscle stiffness value between taping and reference sides (-0.71 kPa ± 0.60 with KT and -0.25 kPa ± 0.78 without KT, P < 0.0001 for 5-cm ROI; -0.67 kPa ± 1.12 with KT and -0.16 kPa ± 1.17 without KT, P = 0.0004 for 2.5-cm ROI) was found in the superficial depth, but no significant differences in the middle and deep depths (P = 0.25 and P = 0.79 for 5-cm ROI; P = 0.09 and P = 0.67 for 2.5-cm ROI, respectively). There were no significant differences of muscle stiffness differences between gender (P = 0.11 for superficial, P = 0.37 for middle, P = 0.78 for deep) and taping direction (P = 0.18 for superficial, P = 0.13 for middle, P = 0.15 for deep). DATA CONCLUSION: Our results demonstrate that KT can reduce the MR elastography-derived shear stiffness in the superficial depth of paraspinal muscles. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1039-1045.

Mechanical properties of the supersonic atmospheric plasma sprayed CaP coating post-processed by a microwave-hydrothermal method.

Coating fabricated by supersonic atmospheric plasma spraying (SAPS) technique is post-treated by a microwave-hydrothermal (MH) method. In this case, after the surface defects are reduced, the mechanical properties between the sprayed CaP coating treated by the MH process and carbon/carbon (C/C) substrate are also studied. Accordingly, observation of the surface morphology and the cross-section of the coating are all performed by scanning electron microscopy. The phase composition and the chemical groups are examined by X-ray diffraction and Fourier Transform Infrared. Besides, a number of required measuring methods have been performed, which include shear strength, modulus of elasticity, hardness and friction coefficient. They are carried out using shear test, nanoindentation, and friction test in the mechanical property evaluation. It's obviously found that the MH method after the SAPS technique can enhance the mechanical properties at the coating-C/C substrate interface. The results show that the bonding strength of the coating after MH treatment, which is 10.46 MPa, increases by 33.25% compared to the bonding strength of the sprayed CaP coating (7.85 MPa). And the modulus of elasticity and hardness are also increased (33.74% and 38.13%). Additionally, the friction coefficient of the coating has been improved in the stable state. Finally, in simulated body fluid (SBF) experiment, the sprayed CaP coating after MH post-treatment also exhibits the bioactive behavior.

Bond strength assessment of a universal adhesive system in etch-and-rinse and self-etch modes / Avaliação da resistência de união de um sistema adesivo universal no modo convencional e autocondicionante

Abstract Introduction Modern dentistry is reflected in the insertion of new materials with different adhesion forms in dental structures, such as the Universal adhesive system. Objective To evaluate the bond strength of the universal dentin adhesive system, in the form of self-etching and conventional application, compared with a simplified conventional adhesive system, in two distinct periods: 1 week and 6 months. Material and method 48 bovine incisors separated into 6 groups, stored for 7 days, were selected. Worn out the buccal enamel until dentin exposure. Adper Single Bond 2 (3M Espe) or SingleBond Universal (3M Espe) adhesives were applied, and catheters filled with Opallis Flow (FGM) composite were placed. After photoactivation, the catheters were removed and the specimens (n ​​= 48), stored in distilled water at 37 °C for one week and six months, were exposed. The specimens were fixed to a universal testing machine (EMIC DL 2000) with a speed of 0.5 mm / min. Bond strength (BS) was calculated in MPa, and data were statistically analyzed by Anova and Tukey test at 5% significance level. Result For Adper Single bond, the BS was equivalent in the times tested; for Universal conventional and self-conditioning time influenced the BS, with a decrease in the results. At 1 week, all stickers were different from each other, with higher BS for Universal conventional mode, followed by universal self-etching mode and then Adper Single bond. Conclusion The best results were achieved with universal adhesive in conventional mode for both tested times.

Resumo Introdução A odontologia moderna é refletida na inserção de novos materiais com diferentes formas de adesão nas estruturas dentárias, como o sistema adesivo Universal. Objetivo Avaliar a resistência adesiva do sistema adesivo universal em dentina, na forma de aplicação auto condicionante e convencional, comparando com um sistema adesivo convencional simplificado, em dois períodos distintos: 1 semana e 6 meses. Material e método Foram selecionados 48 incisivos bovinos separados em 6 grupos, armazenados por 7 dias. Desgastado o esmalte vestibular, até exposição da dentina. Aplicaram-se os adesivos Adper Single Bond 2 (3M Espe) ou SingleBond Universal (3M Espe), e sobre este, posicionados cateteres preenchidos com o compósito Opallis Flow (FGM). Após fotoativação, removeram-se os cateteres e expuseram-se os corpos de prova (n=48), armazenados em água destilada a 37 °C por uma semana e seis meses. Os corpos de prova foram fixados uma máquina universal de ensaios (EMIC DL 2000), com velocidade de 0,5 mm/min. A resistência de união (RU) foi calculada em MPa, e os dados foram analisados estatisticamente pela Anova e pelo teste de Tukey ao nível de 5% de significância. Resultado Para Adper Single bond, a RU foi equivalente nos tempos testados; para Universal modo convencional e autocondicionante o tempo influenciou na RU, havendo um decréscimo nos resultados. Em 1 semana, todos os adesivos foram diferentes entre si, com maior RU para Universal modo convencional, seguido por universal modo autocondicionante e então pelo Adper Single bond. Conclusão O melhor desempenho foi do adesivo universal na forma convencional nos dois tempos testados.