Probe Rotation Research Articles

A probe-based force-controlled nanoindentation system using an axisymmetric four-beam spring

This paper proposes a probe-based force-controlled nanoindentation system employing a four-beam spring. The applied normal load is obtained by a force-modulation module with a four-beam spring and a capacitive displacement sensor, and the maximum normal force can be provided by this system is about 500 mN, which is determined by the precision approaching range of the probe in the vertical direction and the elastic yield strength of the four-beam spring. The closed-loop control accuracy of the normal force is about 0.3 mN. The penetration depth during the indentation process can be obtained by comparing the deflection of the four-beam spring with the elongation of the piezoelectric ceramic transducer (PZT). A rotating ring is utilized to control the orientation of the probe to broaden the machining diversity. The force-modulation module is set on a three-axes moving platform, and the relatively position between the probe and the sample surface can be controlled with a resolution of 1 nm in the horizontal plane, which indicates the high feeding accuracy between two adjacent indentations. Nanoindentation tests were performed using finite element (FE) simulation and experimental approaches with two typical indenters. In addition, 20 × 20 indentation arrays obtained by the probe rotation angles of 0° and 45° are also fabricated successfully. Based on these results, the feasibility of the developed system is verified for the probe-based force-controlled indentation-type micromachining.

Microscopic Viscoelasticity of Polymer Solutions and Gels Observed from Translation and Rotation of Anisotropic Colloid Probes

We probe the mechanics of two different viscoelastic complex systems at a microscopic length scale. The first is made of cross-linked polymer gel, and the second consists of a polysaccharide solution, in which spherical birefringent colloidal tracers have been embedded. This method is widely known as optical microrheology. In the present work we focus on both the translational and the rotational motions of the tracers. The significant discrepancies observed between the results obtained by translational and rotational microrheology imply that the two types of motion probe the mechanical response of the matrix in different ways. We also suggest a simplified theoretical model to explain the experimentally observed discrepancies in terms of the relationship between the viscoelastic moduli obtained from rotational and translational tracer dynamics. Our results have implications for the insights obtainable by rotational and translational microrheology and for the role of compressibility.

Biphasic rate exchange in supercooled o -terphenyl from an ensemble analysis of single-molecule data

Heterogeneity in relaxation rates is a key feature of supercooled liquids. It implies the existence of a rate-exchange process to restore ergodicity, but the experimental characterization of that exchange has been incomplete and controversial. Here, a recently proposed, ensemble-based analysis is applied to single-molecule dichroism data to extract a detailed correlation function for rotational-rate exchange. A large, late phase is $8.7\ifmmode\pm\else\textpm\fi{}0.3$ times slower than the probe rotation and 22 times the alpha-relaxation time, and it has its own exchange-rate dispersion. A small, early phase tracks the initial rotational decay. We propose that the late phase is due to molecules in the core of spatial regions of correlated rates and that the early phase is due to molecules on the boundaries. The results imply that multiple processes and spatial fields are involved in the primary relaxation in supercooled liquids.

Crystallographic Texture Investigation of Thick Section Friction Stir Welded AA6082 and AA5083 Using EBSD

In the present work, a FEI Sirion FEG-SEM equipped with a Nordlys CCD camera controlled by HKL Channel 5 software has been used to characterize the crystallographic texture of 20mm thick friction stir welded AA6082-T651 and AA5083-O. The crystallogaphic texture has been nvestigated near the top surface of the weld nugget at the shoulder affected region and near the base of the nugget in the probe affected region. The crystallographic texture in the shoulder affected region is complex in terms of determing the local reference frame of deformation and it requires complicated rotations to resemble the ideal simple shear texture. This implies the complex deformation histroy experinced in this region. However, the crystallographic texture in the probe-dominated region is simple shear texture. This implies that the deformation conditions across the whole weld nugget in this region are mianly dominated by the shear deformation generated by the probe rotation with the forward motion of the tool only playing a minor role in determining the local deformation gradient. Alternating bands between (+)and (C) was observed in the NG region of FSWed AA6082. The existence of A component is observed with an existence of strong C texture component which implies that when the C component is strong it can be associated with the A texture components.The crystallographic texture of AA5083 at both the shoulder and the probe dominated region is weak relative to that of the AA6082 .

Towards Zero Re-Training for Long-Term Hand Gesture Recognition via Ultrasound Sensing.

While myoelectric pattern recognition is a prevailing way for gesture recognition, the inherent nonstationarity of electromyography signals hinders its long-term application. This study aims to prove a hypothesis that morphological information of muscle contraction detected by ultrasound image is potentially suitable for long-term use. A set of ultrasound-based algorithms are proposed to realize robust hand gesture recognition over multiple days, with user training only at the first day. A markerless calibration algorithm is first presented to position the ultrasound probe during donning and doffing; an algorithm combining speeded-up robust features and bag-of-features model being immune to ultrasound probe shift and rotation is then introduced; a self-enhancing classification method is next adopted to update classification model automatically by incorporating useful knowledge from testing data; finally the performance of long-term hand gesture recognition with zero re-training is validated by a six-day experiment of six healthy subjects, whose outcomes strongly support the hypothesis with about 94% of gesture recognition accuracy for each testing day. This study confirms the feasibility of adoption of ultrasound sensing for long-term musculature related applications.

An in silico framework to analyze the anisotropic shear wave mechanics in cardiac shear wave elastography

Shear wave elastography (SWE) is a potential tool to non-invasively assess cardiac muscle stiffness. This study focused on the effect of the orthotropic material properties and mechanical loading on the performance of cardiac SWE, as it is known that these factors contribute to complex 3D anisotropic shear wave propagation. To investigate the specific impact of these complexities, we constructed a finite element model with an orthotropic material law subjected to different uniaxial stretches to simulate SWE in the stressed cardiac wall. Group and phase speed were analyzed in function of tissue thickness and virtual probe rotation angle. Tissue stretching increased the group and phase speed of the simulated shear wave, especially in the direction of the muscle fiber. As the model provided access to the true fiber orientation and material properties, we assessed the accuracy of two fiber orientation extraction methods based on SWE. We found a higher accuracy (but lower robustness) when extracting fiber orientations based on the location of maximal shear wave speed instead of the angle of the major axis of the ellipsoidal group speed surface. Both methods had a comparable performance for the center region of the cardiac wall, and performed less well towards the edges. Lastly, we also assessed the (theoretical) impact of pathology on shear wave physics and characterization in the model. It was found that SWE was able to detect changes in fiber orientation and material characteristics, potentially associated with cardiac pathologies such as myocardial fibrosis. Furthermore, the model showed clearly altered shear wave patterns for the fibrotic myocardium compared to the healthy myocardium, which forms an initial but promising outcome of this modeling study.

A novel method for testing the electrical property of arc column in plasma arc welding

The electrical property in arc column plays a fundamental role in understanding, controlling, and developing arc processes. In this study, a novel dual active probe method is proposed to measure the arc conductivity, as measured by the voltage-to-current ratio (V-I ratio), and study its electrical property distribution. The probes were partially coated except for their tips such that the electrical conductivity can be accurately tested with fine resolution. During test, the two probes moved into the arc column to detect the V-I ratio of selected zone between the probe tips. Since the speed of the movement is relatively slow, the moving probes are expected to have no significant interruption to the arc. The effect of the probe rotation angular velocity was examined. It was found that with the decrease of probe angular velocity, the instantaneous V-I ratio of the arc between two probes firstly decreases and then tends to be constant. Analysis suggests that the dynamics of the detection circuit is responsible. The testing current applied and the application positions (probe tips), as parameters of the detection circuit, were then analyzed using the circuit model. This novel method provides an effective new approach to study fundamental properties of welding.

Rotational diffusion of magnetic nanoparticles in protein solutions

The rotational diffusion of polyethylene glycol coated magnetic nanoparticles in serum albumin solutions was investigated in a range spanning 0mgmL−1 to 200mgmL−1. Rotational diffusivities were determined from dynamic magnetic susceptibility measurements, which provide a non-optical means to probe rotation of nanoparticles in small volume samples. Experimental rotational diffusivities were compared to those estimated using the Stokes-Einstein relation and macroscopic measurements of the viscosity of the protein solutions. Excellent agreement was found between experimental measurements and theoretical predictions for serum albumin solutions buffered at physiological pH and for serum albumin solutions at acidic pH prepared using simple acids at physiological ionic strengths. For serum albumin solutions prepared using citrate buffer at acidic pH, we observed a discrepancy between the experimental rotational diffusivity and that predicted from the Stokes-Einstein relation. In contrast, when the pH was adjusted with a simple acid and salt at physiological ionic strength we observed agreement between the experimental rotational diffusivity and that predicted from the Stokes-Einstein relation. Because of the role of citrate ions in causing protein aggregation, we believe these observations suggest that dynamic magnetic susceptibility measurement of the rotational diffusivity of the nanoparticles is sensitive to gelation/crosslinking of proteins.

Evaluation of pelvic floor kinematics in continent and incontinent women during running: An exploratory study.

Impact activity like running is associated with an increase in intra-abdominal pressure which needs to be sufficiently countered by pelvic floor muscle (PFM) activity to secure continence. The aim of this study was to investigate and compare PFM kinematics in continent and incontinent women during running. Three-dimensional position and orientation was measured with the electromagnetic tracking device trakSTAR™. One sensor was attached to the vaginal probe and a second one was secured to the subjects' skin at the height of the second sacral vertebrae. Cranial-caudal and forward-backward displacement of the vaginal probe was measured during 10 sec running on a treadmill at the speeds 7, 11, and 15 km/h. Displacement data from 100 ms before to 300 ms after heel-strike were analyzed. Nineteen incontinent and twenty-seven continent women were included in this study. Before the foot touched the ground caudal translation and forward rotation of the vaginal probe was detected, whereas after heel-strike a cranial translation and backward rotation was measured. Cranial-caudal translation as well as backward-forward-rotation did not differ significantly between continent and incontinent subjects for the three speeds. Analysis of maximum displacements showed significantly increasing displacement with increasing speeds. Kinematic measurements during impact activity of running demonstrated caudal translation before and cranial translation after heel-strike. The hypothesis of caudal translation through impact activity was not confirmed. Patterns seem similar between continent and incontinent subjects. Associations between the direction of displacement and muscle action of PFMs remain assumptions.

Magnetic stage with environmental control for optical microscopy and high-speed nano- and microrheology

A novel design of a low-field magnetic stage for optical microscopy of droplets and films within a controlled environment is described. The stage consists of five magnetic coils with a 3D magnetic sensor in a feedback control loop, which allows one to manipulate magnetic nano- and microprobes with microtesla fields. A locally uniform time-dependent field within the focal plane of the microscope objective enables one to rotate the probes in a precisely set manner and observe their motion. The probe tracking protocol was developed to follow the probe rotation in real time and relate it with the viscosity of the host liquid. Using this magnetic stage, a method for measuring mPa s-level viscosity of nanoliter droplets and micron thick films in a 10–20 s timeframe is presented and validated. The viscosity of a rapidly changing liquid can be tracked by using only a few visible probes rotating simultaneously. Vapor pressure and temperature around the sample can be controlled to directly measure viscosity as a function of equilibrium vapor pressure; this addresses a significant challenge in characterization of volatile nanodroplets and thin films. Thin films of surfactant solutions undergoing phase transitions upon solvent evaporation were studied and their rheological properties were related to morphological changes in the material.

The influence on response of axial rotation of a six-group local-conductance probe in horizontal oil–water two-phase flow

Water volume fraction is an important parameter of two-phase flow measurement, and it is an urgent task for accurate measurement in horizontal oil field development and optimization of oil production. The previous ring-shaped conductance water-cut meter cannot obtain the response values corresponding to the oil field water conductivity for oil–water two-phase flow in horizontal oil-producing wells characterized by low yield liquid, low velocity and high water cut. Hence, an inserted axisymmetric array structure sensor, i.e. a six-group local-conductance probe (SGLCP), is proposed in this paper. Firstly, the electric field distributions generated by the exciting electrodes of SGLCP are investigated by the finite element method (FEM), and the spatial sensitivity distributions of SGLCP are analyzed from the aspect of different separations between two electrodes and different axial rotation angles respectively. Secondly, the numerical simulation responses of SGLCP in horizontal segregated flow are calculated from the aspect of different water cut and heights of the water layer, respectively. Lastly, an SGLCP-based well logging instrument was developed, and experiments were carried out in a horizontal pipe with an inner diameter of 125 mm on the industrial-scale experimental multiphase flow setup in the Daqing Oilfield, China. In the experiments, the different oil–water two-phase flow, mineralization degree, temperature and pressure were tested. The results obtained from the simulation experiments and simulation well experiments demonstrate that the designed and developed SGLCP-based instrument still has a good response characteristic for measuring water conductivity under the different conditions mentioned above. The validity and reliability of obtaining the response values corresponding to the water conductivity through the designed and developed SGLCP-based instrument are verified by the experimental results. The significance of this work can provide an effective technology for measuring the water volume fraction of oil–water two-phase flow in horizontal oil-producing wells.

Gas transport and characterization of poly(3 hydroxybutyrate) films

Renewable biodegradable films of poly(3-hydroxybutyrate) (PHB) were produced via thermo-compression and casting method (specimens 1 and 2). On specimens 1, gas permeability coefficients with CO2, O2, N2, and C2H4 gases were measured at 277K, 288K and 296K. The physicochemical characteristics of PHB based on calorimetric, mechanical, and thermal examination were performed for both specimens. SEM and probe ESR technique showed the dramatic differences in their surface morphology and segmental motilities in polymer bulk. In the selected temperature range, the gas permeability ranking (Pi) for the thermo-compressed films is as follows: P(CO2)>P(O2)>P(N2)≈P(C2H4). The gas diffusion coefficients were considered to be dependent on the gas critical volume, in accordance with the semi-logarithmic function, consistent with a free volume model. The activation energies of permeability, diffusivity and spin probe rotation, as well as the apparent heat of sorption equilibrium, forecast the values of PHB barrier characteristics in the range of foodstuffs stored temperatures.

EPR SPECTROSCOPY STUDIES OF CHANGES IN ERYTHROCYTE MEMBRANES IN PATIENTS WITH LARYNGEAL CANCER

To evaluate microviscosity and sorption capacity of erythrocyte membranes (SCEM) from patients with laryngeal cancer (LC). Samples from 35 patients with LC of stages II and III and 20 healthy volunteers were investigated by electron paramagnetic resonance with Bis(1-oxyl-2,2,6,6-tetramethylpiperidinyl-4)-ester of 5,7-dimethyladamantane-1,3-dicarbonic acid (AdTEMPO) probe. SCEM was evaluated by amount of unabsorbed methylene blue. Microviscosity of erythrocyte membranes was determined by the effective rotational diffusion correlation times (τeff) and a decrease in radical spectrum signal intensity per hour. The most apparent decrease in mobility of the AdTEMPO in erythrocytes was observed prior to washing of erythrocytes with 0.9% NaCl for 5 min after probe insertion. The deceleration after 60 min was observed only in stage II LC. τeff was at control values after washing of erythrocytes of stage II LC 5 min after probe insertion and was significantly reduced in stage III LC in comparison to control. Radical spectrum signal intensity per hour in samples of stage II and III patients prior to and after washing of erythrocytes was on average 1.5-fold higher than that of control. SCEM in samples of stage II and III LC was found in 40 and 33% cases, respectively and was on average significantly reduced in comparison to control. The initial interaction of AdTEMPO with erythrocyte membranes of stage II and III LC patients is accompanied by an increase in τeff, indicating deceleration of probe rotation. τeff of the probe in membranes remains unchanged in 60 min, indicating changes in the structural organization of lipid bilayer and its associated proteins in particular. The similarity of SCEM for both studied groups reflects the pathological changes in function of erythrocyte membranes.

Probe rotation effects on direction of arrival estimation in array‐type directional borehole radar

ABSTRACTThis paper discusses the relationship between feeding line delay compensation and direction of arrival estimation in an array‐type directional borehole radar. In this radar, since the space available for an array antenna is limited by the borehole diameter, direction of arrival estimation is based on small travel time differences among array elements, and an accurate compensation of feeding line delays is important. Computer simulation confirmed that the radar probe rotation in a borehole leads to errors in the direction of arrival estimation of greater than 15° if the delays associated with the feeding array antenna elements are not compensated to within 0.1 ns. This may be caused by a failure to measure the time delays of electrical circuits around the feeding points of the antenna elements. In this case, we suggest that the lengths of system components other than the coaxial cables should be kept to less than 3 cm. Based on these investigations, we developed an array‐type directional borehole radar for a geotechnical project to locate foundation piles. In a field experiment, we confirmed that direction of arrival estimation errors were below about 15°, although the radar probe rotated through more than 180° during the measurement, thanks to correct compensation of the cables. With the correct compensation, we demonstrated three‐dimensional location of a buried cylindrical conducting object, which was located at 2 m from the radar in wet soil. We were able to estimate the reflection point position with an accuracy of 34 cm, which is the averaged error of the three‐dimensional location, while allowing the radar probe to rotate.

Development and Assessment of a Novel Task Trainer and Targeting Tasks for Ultrasound-guided Invasive Procedures

The American Institute of Ultrasound in Medicine (AIUM) recommends that all providers performing ultrasound-guided invasive procedures be competent in a core set of guidance skills common to all ultrasound-guided procedures, including in-plane and out-of-plane needle guidance and needle imaging optimization techniques such as probe translation, rotation, and heel-toe standoff. To allow for the practice and assessment of these core skills, we have created a novel task trainer and set of targeting tasks, and sought to obtain validity evidence in the content and response process domains for this training and assessment system according to the Standards for Educational and Psychological Testing. We have constructed an ultrasound-guided invasive procedure training system and five targeting tasks that focused on the needle guidance skills outlined by the AIUM. All tasks were performed by obstetrics and gynecology or maternal-fetal medicine physicians with and without experience in ultrasound-guided invasive procedures during a series of simulation workshops. All participants completed a survey regarding the trainer's and the tasks' usefulness in the training of inexperienced physicians. The physicians who completed the tasks had favorable views of task trainer and curriculum. The targeting curriculum was felt to allow practice of all of the core guidance skills outlined by the AIUM. The average response provided for all of the tasks was 4.0 or greater, with half of the items having an average response of 4.5 or higher. We have constructed a task trainer that incorporates all of the core skills outlined by the AIUM. All five tasks received very favorable reviews from both experienced and inexperienced providers. Taken together, our findings suggest they have strong content and response process validity evidence.

Comparison of selected vegetable oils rheologic properties

The article is focused on measuring and comparison of rheologic parameters of selected vegetable oils. Determined were these properties: density, dynamic, kinematic viscosity and fluidity. Measurements were performed in approximate temperature range (5 - 32) °C on two samples of vegetable oils: sunflower oil and olive oil. Density of vegetable oils was determined by oscillation method using digital densimeter Anton Paar DMA 4500 M at different temperatures. For dynamic viscosity measurement was used rotational viscometer Anton Paar DV-3P, which principle is based on dependency of sample resistance against the probe rotation. Other rheologic parameters as kinematic viscosity and fluidity were determined according to the definitions. Results of measurements are shown as graphical dependencies of rheologic parameters to the temperature. Temperature dependencies of vegetable oils dynamic and kinematic viscosity had decreasing exponential shape which is in accordance with Arrhenius equation and temperature dependencies of fluidity had an increasing exponential shape for both samples. Dependencies of samples density on temperature were characterized by decreasing linear function in measured temperature range. Similar results were obtained by other authors. From measured values can be seen that dynamic viscosity of olive oil is higher than viscosity of sunflower oil. This proportion is caused by different composition of oils.

In-situ grain structure and texture evolution during friction stir welding of austenite stainless steel

The in-situ grain structure and texture evolution during the whole process of friction stir welding (FSW) are clarified. As the base material approached the probe, grains were compressed, forming compression zone (CPZ). The grains evolved to fine equiaxed grains mainly through discontinue dynamic recrystallization (DDRX) and twining as it approached the tool. As material in MFZ rotated around the probe, the fraction of low-angle grain boundaries (LAGBs) was reduced, the ratio of twin boundaries increased, and the grain size distribution became wider, while the average grain size was fairly constant despite the increase in strain. After the material was deposited behind the probe, the grains began to grow. Deformation caused by tool shoulder disrupted the twin boundaries and generated some segments of LAGBs. In the post-weld zone, some LAGBs disappeared and new twin boundaries developed as a result of elevated temperatures. The B component {112} 〈110〉 was developed and was sustained in the MFZ with its shear direction being consisted with the local probe rotation. The shear plan of B component maintained approximately 30deg. away from the probe surface. In the weld zone behind the probe, the B component was weakened and evolved to a C component {001}〈110〉.

On the feasibility of using sodium octyl sulfate micelles for template polymerization of a cationic monomer

Spin probe EPR spectroscopy has been employed to study the effect of a cationic monomer, trimethyl(methacryloxyethyl)ammonium methyl sulfate, on the formation, local structure, and dynamics of sodium octyl sulfate micelles in aqueous solutions. It has been established that the monomer does not affect significantly the parameters of probe rotation in micelles of this surfactant, thereby indicating a weak interaction between the studied monomer and surfactant micelles. The absence of a template effect upon monomer polymerization in micellar sodium octyl sulfate solutions, which has been confirmed by unchanged molecular-mass characteristics of obtained polymers, indicates that it is inefficient to use sodium octyl sulfate micelles as a template for radical polymerization of cationic monomers in aqueous media, in contrast to sodium dodecyl sulfate micelles studied previously.

A Comparison Study for DNA Motif Modeling on Protein Binding Microarray.

Transcription factor binding sites (TFBSs) are relatively short (5-15 bp) and degenerate. Identifying them is a computationally challenging task. In particular, protein binding microarray (PBM) is a high-throughput platform that can measure the DNA binding preference of a protein in a comprehensive and unbiased manner; for instance, a typical PBM experiment can measure binding signal intensities of a protein to all possible DNA k-mers (k = 8∼10). Since proteins can often bind to DNA with different binding intensities, one of the major challenges is to build TFBS (also known as DNA motif) models which can fully capture the quantitative binding affinity data. To learn DNA motif models from the non-convex objective function landscape, several optimization methods are compared and applied to the PBM motif model building problem. In particular, representative methods from different optimization paradigms have been chosen for modeling performance comparison on hundreds of PBM datasets. The results suggest that the multimodal optimization methods are very effective for capturing the binding preference information from PBM data. In particular, we observe a general performance improvement if choosing di-nucleotide modeling over mono-nucleotide modeling. In addition, the models learned by the best-performing method are applied to two independent applications: PBM probe rotation testing and ChIP-Seq peak sequence prediction, demonstrating its biological applicability.

Dynamic Viscosity and Activation Energy of Wort During Fermentation and Storing

This paper presents the results of wort dynamic viscosity and activation energy during fermentation. The effect of temperature and storing time on both parameters was investigated. Measurements were performed on two wort samples. The first sample was taken at the beginning of fermentation, and the second sample after three hours of fermentation. Both samples were also measured after three weeks of storing. Dynamic viscosity measurements were performed with a digital rotational viscometer Anton Paar DV-3P, the principle of which is based on the dependency of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of both analysed parameters on temperature. The temperature dependence of dynamic viscosity can be characterised by a decreasing exponential function, while in case of activation energy linear increasing characters were obtained. Longer fermentation and storing period caused a decrease in both analysed parameters, due to the structural changes in wort samples during fermentation and storing.