Plateau Length Research Articles

Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

Efficient Anion-Exchange Membranes with Anti-Scaling Properties Obtained by Surface Modification of Commercial Membranes Using a Polyquaternium-22.

Anion-exchange membranes modified with a polyquaternium-22 (PQ-22) polymer were studied for their use in electrodialysis. The use of PQ-22 for modification makes it possible to "replace" weakly basic amino groups on the membrane surface with quaternary amino groups. It was found that the content of quaternary amino groups in PQ-22 is higher than the content of carboxyl groups, which is the reason for the effectiveness of this polymer even when modifying Ralex AHM-PES membranes that initially contain only quaternary amino groups. In the case of membranes containing weakly basic amino groups, the PQ-22 polymer modification efficiency is even higher. The surface charge of the modified MA-41P membrane increased, while the limiting current density on the current-voltage curves increased by more than 1.5 times and the plateau length decreased by 2.5 times. These and other characteristics indicate that the rate of water splitting decreased and the electroconvective mixing at the membrane surface intensified, which was confirmed by direct visualization of vortex structures. Increasing the surface charge of the commercial MA-41P anion-exchange membrane, reducing the rate of water splitting, and enhancing electroconvection leads to mitigated scaling on its surface during electrodialysis.

Structure Identification for Force-Induced Reaction Using Single-Molecule Conductance Measurement

Structure Identification for Force-Induced Reaction Using Single-Molecule Conductance Measurement

Influence of cycle number on the compression behavior of nonlinear periodically gradient porous structures produced by laser powder bed fusion

This research presents a design method of the nonlinear periodic gradient triply periodic minimal surface structures (NL-TPMS). The gradient porosity of NL-TPMS was controlled by a sinusoidal function and the influence of the number of cycles on the compression failure mechanism has been investigated. Homogenous TPMS and NL-TPMS were manufactured by laser powder bed fusion (LPBF) with 316L stainless steel powder. Digital image correlation (DIC) and finite element analysis (FEA) were applied to explore the compression behavior of NL-TPMS. The strain of the plateau end of homogenous TPMS decreases as the porosity increases, and the DIC results show that homogenous TPMS deformed with a 45° diagonal shear band. The compression results show that anisotropy of mechanical properties exists in NL-TPMS. The length of the first plateau and compressive proof strength increase as the number of cycles of porosity increases. The cycle of gradient porosity also influences the compression behavior of NL-TPMS, and a periodic failure deformation was observed in the NL-TPMS rather than a layer-by-layer compression deformation in normal gradient porous structures. The maximum principal strain of NL-TPMS detected by DIC presents a periodic distribution, which corresponds to the sinusoidal period designed function of NL-TPMS.

Morphometry of the Tibial Footprint of the Anterior Cruciate Ligament in Punjabi Population

Background: The anterior cruciate ligament (ACL) is responsible for knee joint stability during all possible movements. The purpose of our present study was to estimate normal values of the position and dimensions of the tibial attachment of ACL for its successful reconstruction. Methodology: A sagittal magnetic resonance imaging (MRI) sample of the knee joint of 120 patients (58 men and 62 women) of 18–50 years of age was reviewed. Results: Anterior end of the tibial footprint was located at a mean of 14.92 mm ± 3.42 mm from the anterior end of the tibial plateau. The posterior end of the tibial footprint was located with a mean of 28.76 mm (±7.02) from the anterior end of the tibial plateau. The mean tibial footprint sagittal length was 14.56 mm ± 0.66 mm. The mean anterior cruciate sagittal center was located at 42.62% ±2.99% of the anteroposterior length of the tibial plateau. The present study will provide the baseline morphometric data for the position and size of the tibial footprint of the ACL on MRI in Punjab. Mean roof angle in the present study was 35.16° (±3.49°). Mean ACL-inclination angle was 50.13°(±4.56°). Mean ACL-Bluemensaat angle in the present study was 4.23°(±2.87°). Conclusion: Present study can help surgeons to ascertain the positioning of the tibial tunnel in routine ACL reconstruction as well as revised ACL reconstruction surgeries.

Lateral compression and energy absorption of foamed concrete-filled polyethylene circular pipe as yielding layer for high geo-stress soft rock tunnels

Foamed concrete as energy absorption material for high geo-stress soft rock tunnels has been proven to be feasible due to its high compressibility and lightweight. However, the lengthy curing and defoaming problems caused by the cast-in-place method of large-volume foamed concrete remain unsolved. In this study, we propose a novel energy absorber composed of foamed concrete-filled polyethylene (FC-PE) pipe and analyze its deformation and energy absorption capacity via quasi-static lateral compression experiments. Results show that FC-PE pipes exhibit typical three-stage deformation characteristics, comprising the elastic stage, the plastic plateau, and the densification stage. Furthermore, the plateau stress, energy absorption, and specific energy absorption of the specimens are 0.81–1.91 MPa, 164–533 J, and 1.4–3.6 J/g, respectively. As the density of the foamed concrete increases, the plateau stress and energy absorption increase significantly. Conversely, the length of the plastic plateau and energy absorption efficiency decrease. Moreover, based on the vertical slice method, progressive compression of core material, and the 6 plastic hinges deformation mechanism of the pipe wall, a theoretical calculation method for effective energy absorption is established and achieves good agreement with experimental results, which is beneficial to the optimization of the composite structure.

Can MRI knee joint measurements predict the population at risk of ACL injury?

BackgroundAnterior cruciate ligament (ACL) injuries have been increasing significantly over time. The relationship between the ACL injury and the knee joint structures is poorly understood. The purpose of this study is to examine whether the measurements of different structures in the knee joint are linked with ACL injury in affected patients.MethodsThis retrospective case–control study included patients who suffered from ACL tears and underwent magnetic resonance imaging (MRI). A control group of patients with no knee pathologies on MRI was included. Fourteen knee variables, including lateral meniscus (LM) posterior horn height, length, depth, and volume; medial meniscus (MM) posterior horn height, length, depth, and volume; lateral and medial (MFC) femoral condyle sphere diameter; lateral and medial tibial plateau length; and patella tendon horizontal and vertical diameter, were collected. A multivariate logistic regression including LM posterior horn depth, MM posterior horn length, MM volume, MFC sphere diameter, and patella tendon horizontal diameter and receiver operating characteristic curve, was used to compare the two groups.ResultsA total of 85 patients were included in our study; 54 suffered from ACL injuries and 31 as a control group with normal knee MRI. Logistic regression revealed that increased LM posterior horn depth (OR = 1.27; 95% CI = 1.03–1.56; p = 0.028), decreased MM posterior horn length (OR = 0.71; 95% CI = 0.55–0.93; p = 0.013), and MFC sphere diameter (OR = 1.20; 95% CI = 1.01–1.43; p = 0.035) were independent risk factors for ACL rupture. The MFC sphere diameter yielded the highest area under the curve: 0.747 (95% CI, 0.632–0.862). No difference was found in the other measurements between the two groups.ConclusionsConcerning the difference in anatomical variations, the lateral meniscus posterior horn depth and medial femoral condyle sphere diameter were higher, while medial meniscus posterior horn length was lower in patients with an ACL injury. These structural knee measurements could have a possible increase in the likelihood of sustaining an ACL injury and can be used by clinicians to predict ACL injury.

Evaluation of morphological characteristics for incomplete discoid medial meniscus with an oversized posterior segment

BackgroundA discoid medial meniscus is rare in comparison with a discoid lateral meniscus. We encountered a new type of incomplete discoid with an oversized posterior segment. Therefore, this study aimed to report cases of medial meniscus with an oversized posterior segment and analyze the morphological characteristics by comparing them to cases with a discoid medial meniscus and normal medial meniscus.MethodsFour patients with an oversized posterior segment medial meniscus (oversize group, mean age: 25.3 ± 12.0 years) and seven patients with a discoid medial meniscus (discoid group, mean age: 34.4 ± 19.6) were identified using magnetic resonance imaging (MRI) and diagnosed by arthroscopic findings in our hospital. Fifty patients without medial meniscal injury were retrospectively selected as the normal group (normal group, mean age: 24.0 ± 11.3 years). The clinical symptoms were examined. The anteroposterior (AP) length of both the anterior and posterior segments, AP length ratio of the posterior segment to the AP length of the medial tibial plateau, and mediolateral (ML) width of the mid-body of the medial meniscus were also evaluated using MRI and compared among the three groups.ResultsAll patients in the oversize group complained of medial knee pain during deep knee flexion. In sagittal MRI, posteriorly deviated indentations were also observed at the medial tibial plateau in all cases in the oversize group. There was a significant difference in the AP length of the posterior segment between the normal and oversize groups (14.3 ± 2.8 vs. 23.6 ± 2.8 mm, P < 0.001), whereas there was no significant difference in the AP length of the anterior segment (9.1 ± 2.1 vs. 9.5 ± 1.9 mm, P = 0.869). The ML width of the mid-body in the normal, oversize, and discoid groups was 9.3 ± 1.8, 19.9 ± 2.6, and 25.8 ± 1.9 mm, respectively (normal vs. oversize group: P < 0.001, oversize vs discoid group: P = 0.01, normal vs. discoid group: P < 0.001).ConclusionsOversized posterior and normal anterior segments characterize this new type of incomplete discoid medial meniscus as a morphological abnormality.

Effect of the Lüders plateau on the relationship between fracture toughness and constraint for pipeline steels

The effect of Lüders plateau on the fracture response of pipeline steels is studied. The study is carried out by using the finite element analysis method combined with the material damage model. The single edge notched bending (SENB) specimens are used, and the complete Gurson model (CGM) is used to simulate the crack growth process. The results show that the Lüders plateau has an important effect on the relationship between the fracture toughness and the constraint. When the constraint level is low, the fracture toughness increases with the increase of the Lüders plateau length. When the constraint level is high, the fracture toughness decreases with the increase of the Lüders plateau length. With the increase of the Lüders plateau length, the fracture toughness is more sensitive to the change of the constraint, and the decrease of the fracture toughness with the increase of the constraint is more significant. A constraint-based fracture failure criterion considering the Lüders plateau is proposed and validated. The validation results show that the criterion has high accuracy and great application potential to the fracture analysis for pipeline steels with the Lüders plateau.

Compressive mechanical properties of self-expanding grouting materials with different densities

The compressive mechanical properties of self-expanding grouting materials with different densities are essential in evaluating the ultimate conditions of the repaired underground infrastructure. In this study, digital imaging correlation (DIC) and acoustic emission (AE) techniques were applied to monitor the compressive damage evolution process of self- expanding materials with different densities. It was found that the varied density exhibits great effect on the compressive response of self-expanding grouting materials, and that the length of the horizontal yield plateau decreases with the density. As the density increases to 0.399 g/cm3, the horizontal yield plateau diminishes and the materials present from plastic to brittle characteristics. Moreover, a statistical damage constitutive model of the ascending branch was developed and validated by experimental results.

In Situ Monitoring of Transmetallation in Electric Potential-Promoted Oxidative Coupling in a Single-Molecule Junction

In Situ Monitoring of Transmetallation in Electric Potential-Promoted Oxidative Coupling in a Single-Molecule Junction

Comparison of four methods to -determine cage width in tibial tuberosity advancement.

The objective of this study was to test a method for determining the width of the tibial tuberosity advancement (TTA) cage without the need for extension of the stifle joint, while producing preoperative radiographs. TTA cage size was determined by applying 4 different methods using radiograph images in mediolateral direction of fully extended stifles of dogs (n=43), with and without naturally occurring cranial cruciate ligament disease: parallel shift (PS) method, common tangent (CT) method, «2,1» method (cage size = 2,1 × tibia plateau length - tibial tuberosity width), and margo cranialis (MC) method (cage size = length of MC/6*1,75). Two new methods, «2,1», and MC were compared to the existing CT and PS methods. All 4 methods resulted in reliable cage sizes. Intraclass correlation coefficients showed an excellent reliability of the CT and PS to the «2,1» method and a good reliability in regards to the MC method. In conclusion, TTA cage size of the tibia anatomy alone can be determined on radiographs without the need of full extension of the stifle joint. Based on the results, two different methods of cage size measurement are recommended in order to increase diagnostic accuracy and to prevent the insertion of suboptimal cages.

Morphometric Anatomy of the Tibia Plateau in Nigerians.

There are increasing cases of osteoarthritis and associated disabilities with age, hence the need for knee replacement to restore the anatomy and function of the knee. The objective of this study was to determine the dimensions of the tibial plateau in dry human tibias of Nigerians. This will serve as a guide for the tibia components during total knee replacement procedure. This study adopted the descriptive method of the quantitative design and utilized 133 dry tibias. Total transverse width, total anteroposterior length of intercondylar region, transverse widths of medial and lateral tibia plateaus, and anteroposterior length of the plateaus were measured in millimeter (mm). Statistical analysis of the data was done using mean (SD), t-test and correlation, with the aid of SPSS 23. Statistical significance was fixed at p<0.05. Statistically, the differences between the right and left parameters were not significant. The mean total transverse width was longer than the total anteroposterior length. The mean anteroposterior length of the medial tibia plateau was significantly longer than that of the lateral tibia plateau. The difference between the transverse width of both the medial and lateral tibia plateau was not statistically significant. This study showed that the tibial plateau dimensions can act as guiding tools to the orthopedic surgeon during a knee replacement procedure; and those involved in the fabrication of knee replacement prostheses for Nigerians. The physical anthropologists will also find the anthropometric data invaluable in population studies.

Thermal signature of LIPSS formation revealed by infrared diagnostics

Formation of Laser Induced Periodic Surface Structures (LIPSS) is a very interesting phenomenon. As the process is now moving towards the industry for the production of functional surfaces, a monitoring technique for online process control is needed. In the present work, the process was investigated for the first time using fast infrared radiometry. An advanced multi-beam laser system with 2601 beams using DOE and 200 W picosecond laser was used. Heat accumulation was measured during the 50 pulses of LIPSS fabrication on steel for fluences from 0.07 to 0.31 J/cm2 and frequency 50 kHz. Interestingly, on the cooling part of the curves, plateaus were observed after each laser pulse, for high pulse energies even double plateaus. The observed shapes of the signal evolution in time represent thermal signature of the LIPSS formation. The results are promising that process control will be feasible by monitoring heat accumulation or plateau length.

Comparison of the High Cycle Fatigue Behavior of the Orthodontic NiTi Wires: An in Vitro Study

Objective: To compare the high-cycle fatigue behavior of four commercially available NiTi orthodontic wires. Material and Methods: Twelve NiTi orthodontic wires, round, 0.016-in, three per brand, were selected and divided into four groups: G1 - Heat-activated NiTi, G2 - Superelastic NiTi, G3 - Therma-Ti, and G4 - CopperNiTi. The atomic absorption spectrometry method was used to determine the chemical composition of investigated NiTi wires. We also performed a fatigue test at three-point bending using a universal testing machine for 1000 cycles in a 35 °C water bath. For the first and thousandth cycle, the average plateau load and the plateau length were determined in the unloading area of the force versus displacement diagram. In addition, we calculated the difference between the average plateau load of the first and thousandth cycle (∆F), as well as the difference between the plateau length of both cases (∆L). Results: According to our results, there were no significant differences between the average plateau load of the first and thousandth cycles of each group (p>0.05) and in the plateau length of the first and thousandth cycles of the groups (p>0.05). Conclusion: There were no significant differences between the groups changing the superelasticity property after high-cycle fatigue.

LIPSS-based functional surfaces produced by multi-beam nanostructuring with 2601 beams and real-time thermal processes measurement

A unique combination of the ultrashort high-energy pulsed laser system with exceptional beam quality and a novel Diffractive Optical Element (DOE) enables simultaneous production of 2601 spots organized in the square-shaped 1 × 1 mm matrix in less than 0.01 ms. By adjusting the laser and processing parameters each spot can contain Laser Induced Periodic Surface Structures (LIPSS, ripples), including high-spatial frequency LIPSS (HFSL) and low-spatial frequency LIPSS (LSFL). DOE placed before galvanometric scanner allows easy integration and stitching of the pattern over larger areas. In addition, the LIPSS formation was monitored for the first time using fast infrared radiometry for verification of real-time quality control possibilities. During the LIPSS fabrication, solidification plateaus were observed after each laser pulse, which enables process control by monitoring heat accumulation or plateau length using a new signal derivation approach. Analysis of solidification plateaus after each laser pulse enabled dynamic calibration of the measurement. Heat accumulation temperatures from 200 to 1000 °C were observed from measurement and compared to the theoretical model. The temperature measurements revealed interesting changes in the physics of the laser ablation process. Moreover, the highest throughput on the area of 40 × 40 mm reached 1910 cm2/min, which is the highest demonstrated throughput of LIPSS nanostructuring, to the best of our knowledge. Thus, showing great potential for the efficient production of LIPSS-based functional surfaces which can be used to improve surface mechanical, biological or optical properties.

Web-Based Open-Source Tool for Isotachophoresis.

We present the development of a client-side web-based simulator for complex electrophoresis phenomena, including isotachophoresis. The simulation tool is called Client-based Application for Fast Electrophoresis Simulation (CAFES). CAFES uses the broad cross-browser compatibility of JavaScript to provide a rapid and easy-to-use tool for coupled unsteady electromigration, diffusion, and equilibrium electrolyte reactions among multiple weak electrolytes. The code uses a stationary grid (for simplicity) and an adaptive time step to provide reliable estimates of ion concentration dynamics (including pH profile evolution), requiring no prior installation nor compilation. CAFES also offers a large database of commonly used species and their relevant physicochemical properties. We present a validation of predictions from CAFES by comparing them to experimental data of peak- and plateau-mode isotachophoresis experiments. The code yields accurate estimates of interface velocity, plateau length and relative intensity, and pH variations while significantly reducing the computation time compared to existing codes. The tool is open-source and available for free at https://microfluidics.stanford.edu/cafes.

Closed-Cell Powder Metallurgical Aluminium Foams Reinforced with 3 vol.% SiC and 3 vol.% Graphite

Closed-cell aluminium foams (nominal composition: AlSi12Mg0.6Fe0.3) were prepared by the powder metallurgical route (using 0.4 wt.% TiH2 untreated powder as the foaming agent). Pure foams and foams with the addition of 3 vol.% graphite or SiC powder were prepared. The microstructure and mechanical properties of the prepared aluminium foams containing reinforcing particles were investigated at constant density and compared to those of the pure foam. Vibration measurements were performed to determine the damping properties and modulus of elasticity of the foams. Uniaxial compression tests were performed to determine the following mechanical properties: collapse stress, efficiency of energy absorption, plateau length and densification strain of the foams. All the foams behaved in a brittle manner during compression. Finally, the effect of admixed graphite and SiC powders on the properties of the investigated foam was evaluated, discussed and modelled. The addition of powders changed all investigated properties of the foams. Only the efficiency of energy absorption at constant density was almost identical.

Analytical Model for Bond Behavior Prediction of CFRP-Concrete Joints with End Anchorage.

Use of the end anchorages can significantly control the debonding of CFRP-to-concrete bond interface, and improve the bearing capacity of CFRP strengthened concrete member. An analytical model was presented in this paper to predict the bond behavior and debonding process of CFRP-concrete bonded joint with end anchorage. The calculation formulas of bond failure load and effective bond length for anchored CFRP-concrete joint are derived from the proposed analytical model. According to these models and formulas, the influence of different bond lengths on the mechanical behaviors during the debonding process was analyzed. Results show the load-slip curves of end anchored CFRP-concrete joints could be divided into three branches: elastic stage, stable stage, and enhancement stage. As the bond length increases, the plateau length in stable stage increases. Besides, the bond failure load decreased firstly to a lower limit and then increased with the increase of bond length. The effective bond length of CFRP-concrete joint with end anchorage was longer than that of the external bonded joint, and the value of effective bond length for end anchored joint shall be at least 7.2/AB, where the parameters A and B were related to the interfacial properties of bonded joint. Furthermore, a single shear test was carried out on the end anchored CFRP-concrete bonded joint with different bond lengths, to verify the consistency of the proposed model and formulas. The analytical result of load-slip response at the load end, as well as the strain distribution of CFRP material and the bond failure load, was compared with the experimental result. The comparisons showed that the analytical results had a good agreement with the experimental results.

Relationship Between Simulated Gadolinium-Based Contrast Agent Injection Profile and Achievable Resolution Metrics in Contrast-Enhanced Magnetic Resonance Angiography.

Contrast bolus variation during contrast-enhanced magnetic resonance angiography (CE-MRA) acquisition may lead to vessel blurring. To combine knowledge of how contrast signal intensity (SI) evolves for different injection strategies with anatomically familiar parametric computer models to measure and visually assess the effects of a wide range of variables on modeled CE-MRA, and in doing so develop contrast rate injection guidelines. Computer modeling. Digital three-dimensional phantom consisting of orthogonal "aorta," 7 mm diameter "renal arteries" (with 57% and 86% diameter stenoses), and 7 mm diameter "superior mesenteric artery" (with 57% diameter stenosis). One millimeter in-plane resolution arterial CE-MRA imaging at 3 T. "Background" (time invariant) and "vascular" (time varying) components of the phantom were each Fourier transformed into the spatial frequency domain, the latter modulated by the SI evolution of a contrast bolus of varying "plateau" lengths and "tail" heights. Data are presented as surface plots of stenosis measurement error and blurring vs. a reference-standard injection. Descriptive. Shorter plateau lengths and lower tail heights resulted in increased measured stenosis error and blurring vs. the reference standard. Under a 44-second acquisition, full width half maximum stenosis error of the 86% stenosis with 25% plateau length and 25% tail height is 24% as compared to that from the reference standard. As plateau length and tail height approach 100%, stenosis error and blurring approach a floor defined by the MR acquisition's limitations. We propose that to achieve minimal degradation with CE-MRA, one can create a contrast bolus with either 60% plateau and 50% tail height or 80% plateau with any tail. These considerations may well prove to be of practical importance, possibly via manipulating the tail by means of multiphasic contrast injections. 3 TECHNICAL EFFICACY: Stage 1.