Test Measurements Research Articles

Micro tensile tester measurement of biomechanical properties and adhesion force of microtubule-polymerization-inhibited cancer cells

Both mechanical and adhesion properties of cancer cells are complex and reciprocally related to migration, invasion, and metastasis with large cell deformation. Therefore, we evaluated these properties for human cervical cancer cells (HeLa) simultaneously using our previously developed micro tensile tester system. For efficient evaluation, we developed image analysis software to modify the system. The software can analyze the tensile force in real time. The modified system can evaluate the tensile stiffness of cells to which a large deformation is applied, also evaluate the adhesion strength of cancer cells that adhered to a culture substrate and were cultured for several days with their adhesion maturation. We used the modified system to simultaneously evaluate the stiffness of the cancer cells to which a large deformation was applied and their adhesion strength. The obtained results revealed that the middle phase of tensile stiffness and adhesion force of the microtubule-depolymerized group treated with colchicine (an anti-cancer drug) (stiffness, 13.4 ± 7.5 nN/%; adhesion force, 460.6 ± 258.2 nN) were over two times larger than those of the control group (stiffness, 5.0 ± 3.5 nN/%; adhesion force, 168.2 ± 98.0 nN). Additionally, the same trend was confirmed with the detailed evaluation of cell surface stiffness using an atomic force microscope. Confocal fluorescence microscope observations showed that the stress fibers (SFs) of colchicine-treated cells were aligned in the same direction, and focal adhesions (FAs) of the cells developed around both ends of the SFs and aligned parallel to the developed direction of the SFs. There was a possibility that the microtubule depolymerization by the colchicine treatment induced the development of SFs and FAs and subsequently caused an increment of cell stiffness and adhesion force. From the above results, we concluded the modified system would be applicable to cancer detection and anti-cancer drug efficacy tests.

The impact of progressive overload on the proportion and frequency of positive cardio-respiratory fitness responders

The proportion of individuals whose cardio-respiratory fitness change after endurance training does not exceed the test's measurement error can be 40 %. We determined if progressively increasing treadmill run intensity compared to maintaining the same run intensity, improved the responder proportion to a 6-week 20-minute treadmill training regimen. The intervention response standard deviation method estimated the proportion of responders attributable to progressively increasing run intensity. The mixed-effects model demonstrated V̇O2 peak improved significantly more in the progressive versus constant run intensity group. The proportion of V̇O2 peak responses above the smallest worthwhile change attributable to progressively increasing run intensity was 63.6 %.

Development of a Cryogenic Tester with Air Bearing to Test Sliding-Rolling Contact Friction

This study aimed to test the friction coefficient of cryogenic bearing lubrication materials. A ball-on-disc type friction tester was developed in our lab using air bearings that could simulate the movement of cryogenic bearings under sliding-rolling contact. The tester is equipped with a temperature-controlled chamber to provide a minimum −175 °C low-temperature environment. Using air bearings is an important technique to reduce the base friction of the tester measurement system and ensure the accuracy of the friction coefficient measurement. The friction coefficients of the Ag coating and the PTFE coating were measured at different sliding-rolling velocities on this tester, and the results showed that the friction coefficient curves agreed well with the Gupta sliding model. The developed tester will provide important data for the dynamic analysis and life evaluation of the cryogenic bearings.

Individual Differences in Speech Recognition Changes After Cochlear Implantation

Cochlear implantation is highly effective at improving hearing outcomes, but results have been limited to groupwise analysis. That is, limited data are available for individual patients that report comparisons of preoperative aided speech recognition and postimplantation speech recognition. To assess changes in preoperative aided vs postoperative speech recognition scores for individual patients receiving cochlear implants when considering the measurement error for each speech recognition test. This cross-sectional study used a prospectively maintained database of patients who received cochlear implants between January 1, 2012, and December 31, 2017, at a tertiary, university-based referral center. Adults with bilateral sensorineural hearing loss undergoing cochlear implantation with 6- or 12-month postoperative measures using 1 or more speech recognition tests were studied. Cochlear implantation. Postoperative word recognition (consonant-nucleus-consonant word test), sentence recognition (AzBio sentences in quiet), and sentence recognition in noise (AzBio sentences in +10-dB signal-to-noise ratio) scores, and association of each speech recognition score change with aided preoperative score to each test's measurement error. Analysis of data from a total of 470 implants from 323 patients included 253 male (53.8%) patients; the mean (SD) age was 61.2 (18.3) years. Most patients had statistically significant improvement in all speech recognition tests postoperatively beyond measurement error, including 262 (84.8%) for word recognition, 226 (87.6%) for sentence recognition, and 33 (78.6%) for sentence recognition in noise. A small number of patients had equivalent preoperative and postoperative scores, including 45 (14.5%) for word recognition, 28 (10.9%) for sentence recognition, and 9 (21.4%) for sentence recognition in noise. Four patients (1.6%) had significantly poorer scores in sentence recognition after implantation. The associations between age at implantation and change in speech recognition scores were -0.12 (95% CI, -0.23 to -0.01) for word recognition, -0.22 (95% CI, -0.34 to -0.10) for sentence recognition, and -0.10 (95% CI, -0.39 to 0.21) for sentence recognition in noise. Patients with no significant improvement were similarly distributed between all preoperative aided speech scores for word recognition (range, 0%-58%) and sentence recognition (range, 0%-56%) testing. In this cross-sectional study, with respect to preoperative aided speech recognition, postoperative cochlear implant outcomes for individual patients were largely encouraging. However, improvements in scores for individual patients remained highly variable, which may not be adequately represented in groupwise analyses and reporting of mean scores. Presenting individual patient data from a large sample of individuals with cochlear implants provides a better understanding of individual differences in speech recognition outcomes and contributes to more complete interpretations of successful outcomes after cochlear implantation.

Measurement of Earth Value Using Earth Tester Measurement at Efarina University

Grounding refers to the connection of an electrical equipment or installation to the ground so that it can protect humans from electric shock , and secure installation components from the danger of abnormal current voltages . This grounding system has low resistance properties, so that the overcurrent in the installation network can be flowed quickly to the ground to minimize damage to equipment in the building and protect the people inside. This study reviews the measurement of grounding around the earth at the efarina university. To find out the condition of the grounding resistance at each grounding, it is necessary to measure each grounding by measuring directly on the grounding installation network using an earth tester using an electrode pin. The calculation of grounding resistance is based on the type of soil, the depth of the electrode rod. The results show that the earth around the campus lobby has met the General Electrical Installation Requirements (PUIL) standard, which is smaller than 5 ohms. However, for earthing around the health faculty, it does not meet the PUIL standard, which is less than 5 ohms.

Addressing Higher Order Serial Correlation in Techniques for Gross Error Detection

Serial correlation present in the process measurement data may affect the performance of gross error detection (GED) techniques significantly. It has been our observation that most of the GED techniques assume that the data are not serially correlated. However, serial correlation can occur in measurement data due to delay in the process loop, signal processing elements, and other process phenomena. Performance of GED techniques depends on accurate estimation of variances of measured variables. Serial correlation in measured data increases the variance. Therefore, it is important to eliminate the effect of serial correlation in the measured data. Two approaches are proposed to handle serial correlation, one based on variance correction, and the other on prewhitening of residuals. This paper presents the performance of serial elimination techniques of higher order correlation applied in the measurement test (MT).

Modeling the stress effect on the measurement of magnetostriction in electrical sheets under rotational magnetization

The magnetostriction in electrical steel under rotational magnetization is usually measured with cross-shaped samples. However, the inhomogeneity of the magnetization and stress in the sample might hinder the measured results. In this paper, we investigate this phenomenon by using a magneto-mechanically coupled energy-based model to simulate the sample in a single sheet tester measurement setup, and compare the simulations and measurements. The results show that some anomalies in the measured magnetostriction can be explained by the inhomogeneous magnetization in the sample and the form effect, which result in inhomogeneous stresses and thus affect the observed quantities. The validity of the model as well as the presented statements are ascertained through experiments on the single sheet tester. The backgrounds of the used modelization technique are also detailed.

Plastic Deformation and Thermal Induced Phase Transformation in 2507 Type Super Duplex Stainless Steel

The aim of this study was to investigate the effect of the previously applied cold rolling and the latter heat treatment for the eutectoidal decomposition of δ-ferrite in 2507 type superduplex stainless steel (SDSS). The samples were cold rolled at seven different deformation rates which was followed by heat treatment at were 20, 700, 750, 800 and 850 °C temperatures. The rolled and heat treated samples were investigated by hardness tester, AC magnetometer and thermoelectric power measurement. The activation energy of the decomposition was determined by the Arrhenius equation through the results of the AC magnetometer measurement.

Preparation and dielectric properties of SiO2/silicate-1 ceramics

For exploring the using of silicate-1 zeolite in dielectric ceramic, SiO2@silicate-1 ceramics were fabricated by combining oxidation-bonding, sol–gel directional infiltration and sintering methods. The resulting samples were analyzed by X-ray diffraction, scanning electron microscope, energy dispersive spectrometer, digital hardness tester and microwave dielectric measurement system. It can be found that silicate-1 particles are well bond by silica sol. And the pores of perform are partially filled with silica. The sintering temperature has great effect on microstructure and properties of SiO2@silicate-1 ceramics. When the ceramic is sintered at 400 and 600 °C, it keeps the MFI-type structure and almost has the same low-dielectric-constant (5.71 and 5.62, respectively). When the ceramic is sintered at 800 and 1000 °C, its MFI-type structure is broken down and its dielectric constant is 7.38 and 6.75, respectively.

Sandwich-structured graphite-metallic silicon@C nanocomposites for Li-ion batteries

In this work, we synthesize a sandwich-structured graphite-metallic silicon@C (MS-G@C) composite, which shows good electrochemical performance compared to metallic silicon or graphite-metallic silicon. The improved electrochemical performance may be ascribed to the sandwich structure of the composite with the carbon coating on metallic Si and to the metallic Si particles with high electronic conductivity according to the results of four probe tester measurement and a density functional theory study. When evaluated as an anode material for LIBs, the low cost MS-G@C anodes Exhibit 830mAhg−1 at 0.5C, 650mAhg−1 at 1C, and 251.2mAhg−1 at 5C, respectively, and after 100 cycles with an average capacity loss of only 0.02% per cycle at 0.5C. The synthetic method presented in this paper is provided a facile and low-cost strategy for the large-scale production of silicon-based material as an anode in LIBs.

Adaptive Control of Quadruped Locomotion Through Variable Compliance of Revolute Spiral Feet

In this article we present a novel mechanical design of a robot leg that possesses active and variable passive compliance properties. The hip and knee joints provide active compliance, while the variable passive compliance comes from the spiral foot spring, mounted on the ankle joint, which changes its stiffness by rotating and changing contact angle with the ground. The stiffness of the foot for various contact angles was identified experimentally by using the strength tester measurement system. The method for damping coefficient identification, based on the observation of energy losses during the stance phase of leg hopping motion, is described and used to obtain the foot damping model. The adaptation of spiral foot stiffness to varying ground stiffness is achieved by extracting a leg contact time from a feedback signal provided by a flex sensor mounted on the foot. The experiments on a single leg and quadruped platforms have confirmed that the presented spiral foot design provides stiffness adaptability, partial recovery of the energy from the previous hop and restriction of stance contact time, which are all necessary conditions to obtain more efficient quadruped locomotion.

Simultaneous data reconciliation and gross error detection for dynamic systems using particle filter and measurement test

Good dynamic model estimation plays an important role for both feedforward and feedback control, fault detection, and system optimization. Attempts to successfully implement model estimators are often hindered by severe process nonlinearities, complicated state constraints, systematic modeling errors, unmeasurable perturbations, and irregular measurements with possibly abnormal behaviors. Thus, simultaneous data reconciliation and gross error detection (DRGED) for dynamic systems are fundamental and important. In this research, a novel particle filter (PF) algorithm based on the measurement test (MT) is used to solve the dynamic DRGED problem, called PFMT-DRGED. This strategy can effectively solve the DRGED problem through measurements that contain gross errors in the nonlinear dynamic process systems. The performance of PFMT-DRGED is demonstrated through the results of two statistical performance indices in a classical nonlinear dynamic system. The effectiveness of the proposed PFMT-DRGED applied to a nonlinear dynamic system and a large scale polymerization process is illustrated.

Some problems of the IEC single sheet tester measurement method for electrical steel sheet from a view point of material evaluation

Some problems of the IEC single sheet tester measurement method for electrical steel sheet from a view point of material evaluation

Influences of Surface Nanocrystallization Induced by High-Energy Spot Peening on Microstructure and Properties of Magnesium Alloy

As relatively new structure materials, magnesium and its alloys demonstrated significant potential for applications in many industries. However, magnesium alloys were easy to be corroded which greatly limited their development. AZ31B and AZ91D, two widely used commercial magnesium alloys in various industries, were chosen to be produced nanostructure on the surface layer, called Surface Nanocrystallization (SNC) by High Energy Spot Peening (HESP). The microstructure was characterized by Scan Electronic Microscopy (SEM) and X-ray diffraction (XRD) in this paper. Microhardness and corrosion resistance were measured by microhardness tester and electrochemical measurement system respectively. Experimental results showed that after HESP the grain sizes in the surface layer were obviously reduced into nanoscale; microhardness was greatly increased in the treated surface, about two times as much as that of original and corrosion current density in polarization curve was evidently raised while corrosion potential changed little.

Difficulty and Discrimination Parameters of Boston Naming Test Items in a Consecutive Clinical Series

The Boston Naming Test is one of the most widely used neuropsychological instruments; yet, there has been limited use of modern psychometric methods to investigate its properties at the item level. The current study used Item response theory to examine each item's difficulty and discrimination properties, as well as the test's measurement precision across the range of naming ability. Participants included 300 consecutive referrals to the outpatient neuropsychology service at Mayo Clinic in Florida. Results showed that successive items do not necessarily reflect a monotonic increase in psychometric difficulty, some items are inadequate to distinguish individuals at various levels of naming ability, multiple items provide redundant psychometric information, and measurement precision is greatest for persons within a low-average range of ability. These findings may be used to develop short forms, improve reliability in future test versions by replacing psychometrically poor items, and analyze profiles of intra-individual variability.

Identification of the 2D vector Preisach hysteresis model

PurposeThe purpose of this paper is to present a Preisach model to simulate the vector hysteresis properties of ferromagnetic materials.Design/methodology/approachThe vector behavior has been studied at low frequency applying a single‐sheet tester with a round‐shaped specimen, and the locus of the magnetic flux density vector has been controlled by a digital measurement system. An inverse vector Preisach hysteresis model has been developed and identified by using the measured data.FindingsFinally, the inverse model has been inserted into a finite element procedure through the combination of the fixed point technique and the reduced magnetic scalar potential formulation. The developed single‐sheet tester measurement system has been simulated. The applicability of the realized measurement system as well as the developed model has been proven by comparing measured and simulated results.Originality/valueThe identification technique is original, based on a previous work of the author.

An NT-MT Combined Method for Gross Error Detection and Data Reconciliation

An NT-MT combined method based on nodal test (NT) and measurement test (MT) is developed for gross error detection and data reconciliation for industrial application. The NT-MT combined method makes use of both NT and MT tests and this combination helps to overcome the defects in the respective methods. It also avoids any artificial manipulation and eliminates the huge combinatorial problem that is created in the combined method based on the nodal test in the case of more than one gross error for a large process system. Serial compensation strategy is also used to avoid the decrease of the coefficient matrix rank during the computation of the proposed method. Simulation results show that the proposed method is very effective and possesses good performance.

PECVD로 증착된 금속층을 포함하는 DLC 박막의 기계적 특성 분석

The properties of metal interlayered DLC films between the Si substrate and the DLC films were studied. DC magnetron sputtering method has been used to deposit intermediate layers of metals. And RF-PECVD method has been employed to synthesize DLC onto substrates of the silicon and metal layers. After we used metal Inter-layers, such as chromium, nickel, titanium and we studied tribological properties of the DLC films. The thickness of films were observed by field emission scanning electron microscope (FE-SEM). Also the surface morphology of the films were observed by an atomic force microscope (AFM). The crystallographic properties of the films were analyzed with X-ray diffraction (XRD), the friction coefficients were investigated by AFM in friction force microscope (FFM) mode. Tribological performances of the films were estimated by nano-indenter, stress tester measurement.

A comparison of two portable dynamometers in the assessment of shoulder and elbow strength

Objectives To compare the practical applicability and measurement properties of a hand-held dynamometer (MicroFET2 ®) and a fixed dynamometer (Isobex2.1 ®) in determining isometric strength of the shoulder and elbow. Design Muscle strength in four directions (glenohumeral abduction, external rotation and elevation and elbow flexion) was measured using both instruments by two examiners. The assessments were repeated by one of the examiners 3 days later. Setting Leiden University Medical Center. Participants Twenty healthy volunteers. Main outcome measures Time to complete a set of measurements and discomfort were recorded. To determine intra- and inter-observer reliability, intra-class correlation coefficients (ICCs), limits of agreement and smallest detectable difference were computed. Results The time to complete a set of measurements was significantly shorter for the hand-held dynamometer than for the fixed dynamometer in both examiners. The number of subjects reporting discomfort was similar with the two dynamometers. Except for glenohumeral abduction, the forces measured using the hand-held dynamometer were significantly higher than those when using the fixed dynamometer in both examiners. The intra- and inter-observer ICCs for the four directions ranged from 0.82 to 0.98 for both dynamometers. However, the mean differences between replications and the wide limits of agreement suggest substantial bias and variability. For example, for the measurement of shoulder abduction with the fixed dynamometer by one tester (190 N), the results suggest that on 95% of occasions the second tester's measurement would be between 158 and 275 N. Conclusions Although time taken and discomfort should be considered in the selection of dynamometers, due consideration should be given to the significant differences in absolute results. Neither the dynamometers nor the testers can be considered interchangeable. Both the intra- and inter-observer reliability of the two dynamometers were similar, yet both demonstrated systematic bias and variability in the measurements obtained.

PERFORMANCE EVALUATION OF PCA TESTS IN SERIAL ELIMINATION STRATEGIES FOR GROSS ERROR IDENTIFICATION

In this paper, the performance of the Principal Component Measurement Test (PCMT) is evaluated when used for the identification of multiple biases. A serial elimination strategy is implemented where a statistical test based on principal component analysis is used to identify the measurement to eliminate. A simulation procedure involving random measurement errors and fixed gross error sizes is applied to evaluate its performance. This performance is compared with the one obtained using serial elimination using the conventional Measurement Test (MT), as it is performed in some commercial simulators. The analysis indicates that principal component tests alone, without the aid of other collective tests, do not significantly enhance the ability in identification features of this strategy, performing worse in some cases. A few cases of severe failure of this strategy are shown and a suggestion to test other strategies is offered.