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Aim: To mimic the ultrastructural morphology of the meniscus with nanofiber scaffolds coupled with controlled growth factor delivery to modulate cellular performance for tissue engineering of menisci. Methods: The authors functionalized collagen nanofibers by conjugating heparin to the following growth factors for sustained release: PDGF-BB, TGF-β1 and CTGF. Results: Incorporating growth factors increased human meniscal and synovial cell viability, proliferation and infiltration in vitro, ex vivo and in vivo; upregulated key genes involved in meniscal extracellular matrix synthesis and enhanced generation of meniscus-like tissue. Conclusion: The authors' results indicate that functionalizing collagen nanofibers can create a cell-favorable micro- and nanoenvironment and can serve as a system for sustained release of bioactive factors.

Purpose The purpose of this study is to improve the accuracy of a fused deposition modeling three-dimensional (3D) printer by identifying and compensating for position-independent geometric errors using a face-diagonal length test featuring a designed artifact and a Vernier caliper. Design/methodology/approach An artifact that does not require support when printing was designed and printed to allow performance of the face-diagonal length test. A Vernier caliper was used to measure the lengths of diagonals in the XY, YZ and ZX planes of the printed artifact specimen; this completed the face-diagonal length test. The relationships between position-independent geometric errors of the linear axes X, Y and Z and the measured diagonal lengths of the three planes were determined to identify geometric errors. Findings The approach was applied to a commercial fused deposition modeling 3D printer, and three position-independent geometric errors were rapidly identified. The artifact was re-printed after model-based compensation for these errors and the diagonal lengths were re-measured. The results were verified via coordinate measuring machine measurement of a simple test piece without and with model-based compensation for identified geometric errors. Furthermore, the proposed approach was applied to a commercial 3D printer. Research limitations/implications The measured diagonal lengths of the printed artifacts varied greatly. Thus, further studies should investigate the effects of printing materials and parameters on the length discrepancies of 3D printed artifacts. Practical implications A software-based compensation of identified position-independent geometric errors has to be used at commercial 3D printers for accuracy improvements of printed parts. Originality/value Thus, the approach is of practical utility; it can be periodically used to identify position-independent geometric errors and ensure that the 3D printer is consistently accurate.

In this paper, a method is proposed for identification of 11 position-independent geometric errors (PIGEs) of five-axis machine tools with a tilting/rotary table via single-ball measurements and three-dimensional (3D) geometric sensitivity analysis. Eleven PIGEs were identified, including three squareness errors between three linear axes, two offset errors, and two squareness errors for the tilting/rotary axis. The approach uses a set-up of a ball and three circular measurements involving simultaneous control of two linear axes and a tilting/rotary axis. A 3D geometric sensitivity analysis is carried out to investigate the effects of the 11 PIGEs on each of the measurement’s paths and between the measurement paths. The particular measurement paths used allow the radius of the circular path at the first measurement, and the distance between the circular paths of the second and third measurements, to be increased for accurate identification of the 11 PIGEs. The proposed method was also used to derive root-sum-square values of sensitivity coefficients, and then applied to a commercial five-axis machine tool for experimental verification. It calculates the peak-to-valley values of the positional deviations in the x-, y-, and z-directions along the test paths as 152.1, 118.2, and 47.1 μm, respectively, without compensation for the identified PIGEs, and as 17.6, 15.0, and 11.4 μm, respectively, with compensation. The results confirm the validity of our proposed method.

Hydrogels are commonly used in wound dressing, as they retain moisture, accelerate healing, and break down necrotic tissue. This process enhances patient comfort levels while simultaneously reducing pain caused by dead tissue. The purpose of this study was to investigate the in vivo toxicity of a dual hydrogel consisting of type I atelocollagen cross-linked with sodium hyaluronate hydrogel used for wound dressing. Porcine type I atelocollagen was cross-linked with sodium hyaluronate to form the hydrogel. For subcutaneous implantation, 0.5 ml of dual hydrogel was injected into two different sites of twenty rats per group. High density polyethylene rods were implanted subcutaneously to serve as a control material. Hematological assessment, blood biochemistry, histopathological, and histological evaluations were scored and graded after 4 weeks. A bioreactivity rating was used for evaluation of subacute toxicity. Differences observed in blood chemical analysis and hematological analysis between control and test groups were within normal variations and considered unrelated to the test article implantation. No significant implantation-related lesions were observed in any of the major organs of all test animals. The overall histopathological index of the test article implantation sites was evaluated as 0. The bioreactivity rating was evaluated as non-irritant after 4-week subcutaneous implantation. Overall, these results indicate that the dual hydrogel of type I atelocollagen and sodium hyaluronate is biologically and chemically safe for clinical application as a wound dressing.

We propose a technique to measure position-independent geometric errors (PIGEs) in the rotary and spindle axes of a hybrid parallel kinematic machine (PKM). The PKM investigated here includes one more rotary axis than an Exechon PKM, which is used to improve the productivity of hybrid processes, such as machining and direct-energy-deposition three-dimensional metal printing. Errors in the measured position and orientation of the rotary axis, and the orientation of the spindle axis produce volumetric errors in the processed workpiece. If accuracy is to be improved, the deviation of each axis must be measured and compensated. In our approach, errors are measured using three methodologies that require only control of the rotary axis: in the first, no offset is applied to account for positional deviation of the rotary axis; in the second, an offset is used to correct the orientation of the rotary axis; and in the third, a tool offset is used to correct the orientation of the spindle axis. We developed an algorithm that uses the three measured datasets to identify PIGEs. The proposed method was applied to a hybrid PKM and the PIGEs were measured and compensated. This technique uses simple measurement paths and sequential measurements to correct rotary and spindle axis errors, and could therefore be widely used in industry.

This paper presents a double ballbar method with an extension fixture to identify the position-independent geometric errors of three-axis machine tools with respect to their entire workspace by conducting face- and body-diagonal length tests. To extend the length of the double ballbar to the required nominal length in the face- and body-diagonal directions, an extension fixture is designed and manufactured using a fused-deposition-modeling 3D printer to ensure that it is lightweight. Inherent position-independent geometric errors can be calculated from measured lengths by using homogeneous transformation matrices, which are multiplied under the assumption of small values, to determine the volumetric error produced by a machine tool. The relationships between the position-independent geometric errors, roll-pitch-yaw errors, and measured lengths can be derived according to the definition of the straightness errors, based on the end-point of the reference straight line. Finally, the position-independent geometric errors, with analysis of measurement uncertainties, can be identified by substituting the values of the roll-pitch-yaw errors, measured by a multi-axis calibrator, into the derived relations. The results can then be validated by re-measuring the face- and body-diagonal lengths with error compensation. The main advantage of the proposed approach is that it can be used to identify the inherent position-independent geometric errors of machine tool workspaces. This could contribute to reducing volumetric errors in machine-tool workspaces by allowing compensation for measurement errors, thus making machine tools more effective.

We introduce a prototype “machine tool analyzer” (MTA), consisting of a nest of five displacement sensors and a dual-ball system with two centering structures, designed to identify 13 position-independent geometric errors (PIGEs) in five-axis machine tools. The 13 PIGEs include three squareness errors in the three linear axes, two squareness errors and two offset errors in the rotary/tilting axis, and two squareness errors in the spindle axis. The MTA completes four circular paths, during which an identification algorithm identifies thirteen possible PIGEs and set-up errors. The MTA was applied to a commercial five-axis machine tool with a swivel head/rotary table and verified experimentally. Cost-effective measurements were achieved using a single set-up of the nest and associated system. In addition, a circular test using a double ball-bar was used to test the volumetric accuracy of the five-axis machine tool and verify the identified PIGEs. The maximum deviation, minimum deviation, and PV values in the circular test were 109, 55, and 55 μm, respectively, without compensation for errors imparted by the PIGEs, and 38, 5, and 33 μm, respectively, with compensation. This demonstrated the validity of the proposed method.

We develop a novel method to measure six geometric errors (two position-independent geometric errors and four position-dependent geometric errors) of a rotary manipulator; we use two displacement sensors and one measurement target to this end. To enhance measurement accuracy, the method initially removes setup errors that distort the sensor data and then models the geometric errors using an nth-order polynomial equation exhibiting C1-continuity. The data are used to define the relative positions of the reference and measurement co-ordinate systems using a homogeneous transform matrix. The geometric errors of a rotary manipulator are measured using the least squares method to exploit the linear relationship between the errors and the measurement target profile. We validate our method via simulation and assess measuring uncertainties with consideration of measurement noise.

Meniscus tears common injuries of the knee joint and a major osteoarthritis (OA) risk factor. Knowledge gaps that limit development of therapeutic approaches for meniscus injury and degeneration concern transcription factors that control the meniscus cell phenotype. Analysis of RNA-sequencing data from 37 human tissues in the Genotype-Tissue Expression (GTEx) database and RNA-sequencing data from meniscus and articular cartilage showed that transcription factor Mohawk (MKX) is highly enriched in meniscus. In human meniscus cells, MKX regulates expression of meniscus marker genes, OA-related genes and other transcription factors, including Scleraxis (SCX), SRY Box 5 (SOX5), and Runt domain-related transcription factor 2 (RUNX2). In mesenchymal stem cells, the combination of adenoviral MKX (Ad-MKX) and Transforming growth factor-β3 (TGF-β3) induced a meniscus cell phenotype. When Ad-MKX-transduced mesenchymal stem cells (MSCs) were seeded on TGF-β3-conjugated decellularized meniscus scaffold (DMS) and inserted into experimental tears in meniscus explants, they increased glycosaminoglycan content, extracellular matrix interconnectivity, cell infiltration into the DMS and improved biomechanical properties. Ad-MKX injection into mouse knee joints with experimental OA induced by surgical destabilization of the meniscus suppressed meniscus and cartilage damage, reducing OA severity. Ad-MKX injection into human OA meniscus tissue explants corrected pathogenic gene expression. These results identify MKX as a previously unidentified key transcription factor that regulates the meniscus cell phenotype. The combination of Ad-MKX with TGF-β3 is effective for differentiation of MSCs to a meniscus cell phenotype and useful for meniscus repair. MKX is a promising therapeutic target for meniscus tissue engineering, repair and prevention of OA.

The objective of this study was to examine FoxO expression and FoxO function in meniscus. In menisci from human knee joints with osteoarthritis (OA), FoxO1 and 3 expression were significantly reduced compared with normal menisci from young and old normal donors. The expression of FoxO1 and 3 was also significantly reduced in mouse menisci during aging and OA induced by surgical meniscus destabilization or mechanical overuse. Deletion of FoxO1 and combined FoxO1, 3, and 4 deletions induced abnormal postnatal meniscus development in mice and these mutant mice spontaneously displayed meniscus pathology at 6 mo. Mice with Col2Cre-mediated deletion of FoxO3 or FoxO4 had normal meniscus development but had more severe aging-related damage. In mature AcanCreERT2 mice, the deletion of FoxO1, 3, and 4 aggravated meniscus lesions in all experimental OA models. FoxO deletion suppressed autophagy and antioxidant defense genes and altered several meniscus-specific genes. Expression of these genes was modulated by adenoviral FoxO1 in cultured human meniscus cells. These results suggest that FoxO1 plays a key role in meniscus development and maturation, and both FoxO1 and 3 support homeostasis and protect against meniscus damage in response to mechanical overuse and during aging and OA.

The aim of this study was to examine the potential of platelet-derived growth factor (PDGF)-coated decellularized meniscus scaffold in mediating integrative healing of meniscus tears by inducing endogenous cell migration. Fresh bovine meniscus was chemically decellularized and covalently conjugated with heparin and PDGF-BB. In vitro PDGF release kinetics was measured. The scaffold was transplanted into experimental tears in avascular bovine meniscus explants and cultured for 2 and 4 weeks. The number migrating and proliferating cells at the borderline between the scaffold and injured explant and PDGF receptor-β (PDGFRβ) expressing cells were counted. The alignment of the newly produced ECM and collagen was analyzed by Safranin-O, picrosirius red staining, and differential interference contrast (DIC). Tensile testing of the explants was performed after culture for 2 and 4 weeks. Heparin conjugated scaffold showed immobilization of high levels of PDGF-BB, with sustained release over 2 weeks. Insertion of the PDGF-BB treated scaffold in defects in avascular meniscus led to increased PDGFRβ expression, cell migration and proliferation into the defect zone. Safranin-O, picrosirius red staining and DIC showed tissue integration between the scaffold and injured explants. Tensile properties of injured explants treated with PDGF-BB coated scaffold were significantly higher than in the scaffold without PDGF. In conclusion, PDGF-BB-coated scaffold increased PDGFRβ expression and promoted migration of endogenous meniscus cells to the defect area. New matrix was formed that bridged the space between the native meniscus and the scaffold and this was associated with improved biomechanical properties. The PDGF-BB-coated scaffold will be promising for clinical translation to healing of meniscus tears. Statement of Significance Meniscus tears are the most common injury of the knee joint. The most prevalent forms that occur in the inner third typically do not spontaneously heal and represent a major risk factor for the development of knee osteoarthritis. The goal of this project was to develop an approach that is readily applicable for clinical use. We selected a natural and readily available decellularized meniscus scaffold and conjugated it with PDGF, which we had previously found to have strong chemotactic activity for chondrocytes and progenitor cells. The present results show that insertion of the PDGF-conjugated scaffold in defects in avascular meniscus led to endogenous cell migration and proliferation into the defect zone with tissue integration between the scaffold and injured explants and improved tensile properties. This PDGF-conjugated scaffold will be promising for a translational approach to healing of meniscus tears.

This study proposes an optimal on-machine measurement method to measure position-independent geometric errors of five-axis machines, including machine tools and coordinate measuring machines, with a universal head. This measurement requires only a calibrated three-dimensional (3-D) probe and a precision sphere, which are fundamental components of on-machine measurement systems in general, to minimize measurement costs, including operator effort and operating time. Eight position-independent geometric errors are used to describe the coordinate systems of the two rotary axes through a kinematic analysis. The center of the precision sphere, which is stationary during the measurement, is measured at various angles of the rotary axes. Then, the linearized relationship between the measured positions of the precision sphere and the geometric errors is derived using an error synthesis model under rigid-body and small-value assumptions. The proposed method is tested through a simulation for validation. The geometric errors of a five-axis coordinate measuring machine with a universal head are measured with measurement uncertainty by applying the proposed method. Then, the measurement results are confirmed by comparing the measured positions of the precision sphere and calculated positions using the measured geometric errors at the other (i.e., the arbitrary, or not measured) angles of rotary axes.

This study proposes a method for a quick, simple interim check and practical accuracy improvement of machine tools using just a double ball-bar. The double ball-bar is used to measure sequentially the length of the six sides of a virtual regular tetrahedron within the workspace of the machine tool. Then, the scale and squareness errors of and between the three linear axes are calculated from the length results, and the measured lengths and the calculated errors can be used as criteria for the interim check. The calculated errors can also be compensated for to improve the accuracy of experimented machine tools practically. A sample machine tool was subjected to experimental interim checks applying the proposed method; it showed primarily large length deviations for the six sides due to geometric errors mainly. To improve the geometric accuracy practically, the calculated errors were compensated for and the measurements were repeated, showing significantly improved length deviations for the six sides. The main advantage of the proposed method is that it requires only a double ball-bar and sequential measurements; thus, it is a simple procedure with a measuring time of ∼5 min for a virtual regular tetrahedron. Additionally, the size of the virtual regular tetrahedron can be readily modified by changing the nominal length of the double ball-bar, increasing measurement flexibility. Thus, the proposed method is suitable for quick, simple, cost-effective daily and periodic interim checks, with practical improvement of machine tool accuracy.

Haptic technology is used in various fields to transmit information to the user with or without visual and auditory cues. This study aimed to provide preliminary data for use in developing a haptic interface for an antigravity (anti-G) suit. With the structural characteristics of the anti-G suit in mind, we determined five areas on the body (lower back, outer thighs, inner thighs, outer calves, and inner calves) on which to install ten bar-type eccentric rotating mass (ERM) motors as vibration actuators. To determine the design factors of the haptic anti-G suit, we conducted three experiments to find the absolute threshold, moderate intensity, and subjective assessments of vibrotactile stimuli. Twenty-six fighter pilots participated in the experiments, which were conducted in a fixed-based flight simulator. From the results of our study, we recommend 1) absolute thresholds of ∼11.98–15.84 Hz and 102.01–104.06 dB, 2) moderate intensities of 74.36 Hz and 126.98 dB for the lower back and 58.65 Hz and 122.37 dB for either side of the thighs and calves, and 3) subjective assessments of vibrotactile stimuli (displeasure, easy to perceive, and level of comfort). The results of this study will be useful for the design of a haptic anti-G suit.

In this study, parallelism errors between the spindle axis and the linear axis of machine tools were measured using a double ball-bar. Specifically, two circular tests were performed to measure the parallelism errors using tool balls with different tool lengths and a workpiece ball fixed to a workpiece table. Parallelism errors were calculated by analyzing, simultaneously, the measured double ball-bar (DBB) data from the circular tests. The proposed method provides accurate measurements due to a large offset between the circular tests within the working space of machine tools. Additionally, the approach only requires a DBB and adjustment/extension fixtures; thus, it simplifies measurements and is cost-effective.

Biologic augmentation for rotator cuff repair is a challenging treatment in patients with chronic large, massive, and irreparable rotator cuff injuries. Particularly, the use of an extracellular matrix (ECM) patch such as dermal tissue offered improved biomechanical properties in previous studies. Cytokines induce cell chemotaxis, proliferation, matrix synthesis, and cell differentiation. Moreover, osteoinductive growth factors such as bone morphogenetic protein-2 (BMP-2) affect the formation of new bone and fibrocartilage in lesions. However, the effects of using a dermal patch in combination with BMP-2 have not been evaluated to date, although many researchers have recognized the importance thereof. In this study, rhBMP-2-coated dermal patch (1 cm × 2 cm) isolated from human cadaveric donor was inserted in a rabbit model of chronic rotator cuff injury for in vivo evaluation. Bone mineral density and biomechanical strength were tested and histological and histomorphometric analyses were performed. The results showed that insertion of an rhBMP-2-coated acellular dermal patch not only significantly ameliorated new bone formation, it also improved biomechanical properties such as ultimate tensile strength. Thus, the use of this combination may improve the chronic rotator cuff injury-healing rate and clinical outcomes after rotator cuff repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1840-1846, 2017.

We report a compensation system for geometric errors of a linear axis to achieve the ultra-precision positioning. The system was miniaturized by integrating the drive and measuring components. A novel joint with three DOFs based on a flexure hinge was developed to obtain the ultra-precision positioning. The drive component, which was adapted to the parallel mechanism, had a high structural stiffness and rapid response characteristics. The rotational stiffness of the joint was calculated and the mode shapes were analyzed to verify the feasibility of three-DOF motion. The measurement component consisted of capacitive sensors and a reference mirror to measure the three geometric errors of the linear axis. In addition, the optimal position between the reference coordinate system and a sensor was determined to minimize the standard uncertainties of the measured errors. The compensation system was fabricated and evaluated experimentally. A compensation algorithm based on a recursive technique was developed to improve the positioning accuracy of the system. The geometric errors of the linear axis were measured and compensated for, and a marked improvement was observed compared to the case with no error compensation. The peak-to-valley error of the translational and rotational errors were reduced by 92% and 98%, respectively.

Background:Anterior cruciate ligament (ACL) reconstruction is the current standard of care for ACL tears. However, the results are not consistently successful; autografts or allografts have certain disadvantages; and synthetic grafts have had poor clinical results.Purpose:To determine if recellularization of decellularized tendons combined with mechanical stimulation in a bioreactor could replicate the mechanical properties of the native ACL and be successfully used for ACL reconstruction in vivo.Study Design:Controlled laboratory study.Methods:Porcine tibialis tendons were decellularized and then recellularized with human adult bone marrow–derived stem cells. Tendons were cultured in a tissue bioreactor that provided biaxial cyclic loading for up to 7 days. To reproduce mechanical stresses similar to those experienced by the ACL within the knee joint, the tendons were subjected to simultaneous tension and torsion in the bioreactor. Expression of tendon-specific genes and newly synthesized collagen and glycosaminoglycan were used to quantify the efficacy of recellularization and dynamic bioreactor culture. The ultimate tensile load to failure and stiffness of recellularized constructs were measured after dynamic stimulation. Finally, the tissue-engineered tendons were used to reconstruct the ACL in 24 pigs, and ultimate tensile load to failure and stiffness were assessed after 3 months.Results:Dynamic bioreactor culture significantly increased the expression of tendon-specific genes, the quantity of newly synthesized collagen and glycosaminoglycan, and the ultimate tensile load and stiffness of recellularized tendons. After in vivo reconstruction, the ultimate tensile load and stiffness of the tissue-engineered tendons increased significantly up to 3 months after surgery and were within 80% of the ultimate tensile load of the natural ACL.Conclusion:This translational study indicates that recellularization and dynamic mechanical stimuli can significantly enhance matrix synthesis and ultimate tensile load of decellularized porcine tibialis tendons. This approach to tissue engineering can be very useful for ACL reconstruction and may overcome some of the disadvantages of autografts and allografts.Clinical Relevance:Dynamic bioreactor cultivation of tissue-engineered tendons may overcome the limitations of autografts and allografts.

We describe a method to separate, measure, and compensate for position-independent and position-dependent geometric errors in the rotary axes of a five-axis machine tool with a tilting rotary table using double ball-bar measurements. The measurement paths require control of a single rotary axis, and they are not affected by the accuracy of the linear axes. The positions of the balls of the double ball-bar are modeled as the nominal positions, with geometric errors considered via a kinematic analysis to represent the measurement configuration. The method is applied to measure both position-independent and position-dependent geometric errors, and the results are verified via measurements with compensation for the geometric errors. Furthermore, the possible range of the measured geometric errors is determined by analyzing the contributors.

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This study examines the hypothesis that injectable collagen gel can be an effective carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2)'s localization to the healing tendon-bone interface. In 36 mature New Zealand White rabbits, the upper long digital extensor tendon was cut and inserted into the proximal tibial bone tunnel. Then a rhBMP-2-containing collagen gel was injected into the tendon-bone tunnel interface, using a syringe. Histological and biomechanical assessments of the tendon-bone interface were conducted at 3 and 6 weeks after implantation. In vitro testing showed that the semi-viscous collagen gel at room temperature was transformed into a firm gel state at 37°C. The rhBMP-2 release profile showed that rhBMP-2 was released from the collagen gel for more than 28 days. In vivo testing showed that fibrocartilage and new bone are formed at the interface at 6 weeks after injection of rhBMP-2. On radiography, spotty calcification appeared and enthesis-like tissue was produced successfully in the tendon at 6 weeks after injection of rhBMP-2. Use of the viscous collagen gel and rhBMP-2 mixture increased the fusion rate between the bone tunnel and tissue graft. This study demonstrates that viscous collagen gel can be an effective carrier for rhBMP-2 delivery into surgical sites, and that the injectable rhBMP-2-containing collagen gel may be applied for the enhancement of tendon-bone interface healing in the future. Copyright © 2015 John Wiley & Sons, Ltd.

Circular tests to determine the circular/spherical deviation of machine tools based on double ball-bar measurements are proposed and applied to machine tools for accurate performance evaluation. In current circular tests, eccentricity is mathematically removed from the measured data to evaluate performance. However, eccentricity is affected not only by set-up error of the double ball-bar, which is trivial, but also by geometric error, which this test is intended to determine. The relationship between eccentricity and geometric error was investigated during circular deviation measurements using a simple example. The results demonstrated that the measured data must be evaluated as they are, without any mathematical modifications. Additionally, the circular test must be performed while ensuring negligible set-up error. The proposed approach was applied to three machine tools to investigate the effect of eccentricity when circular/spherical deviation appears.

In vitro experiment using degenerated human ligamentum flavum (LF) and herniated intervertebral disk (IVD).To investigate the role and effect of degenerated and herniated IVDs on LF hypertrophy and ossification.Spinal stenosis is caused, in part, by hypertrophy and ossification of the LF, which are induced by aging and degenerative process. It is well known that degenerated IVDs spontaneously produce inflammatory cytokines. Therefore, we hypothesized that degenerated IVD may affect adjacent LF through secreted inflammatory cytokines.LF and herniated lumbar IVD tissues were obtained during surgical spinal procedures. LF fibroblasts were isolated by enzymatic digestion of LF tissue. LF cell cultures were treated with disk supernatant from herniated IVDs. Secreted cytokines from IVD tissue culture were detected by enzyme-linked immunosorbent assay. After analysis of cytotoxicity, DNA synthesis was measured. Reverse transcription-polymerase chain reaction for mRNA expressions of types I, II, III, V, and XI collagen and osteocalcin, and histochemical stains were performed.Supernatant from tissue culture of herniated IVD showed increased production of interleukin-1α, interleukin-6, tumor necrosis factor-α, prostaglandin E2, and nitric oxide compared with disk tissue culture from traumatic condition. There was no cytotoxicity in LF cells treated with disk supernatant from herniated IVDs. There was significant increase in DNA synthesis, upregulation in mRNA expression of types III, XI collagen and osteocalcin, whereas variable expression pattern of type I and V, and strong positive stains for Von Kossa and alkaline phosphatase in LF cultures with disk supernatant.Degenerated and herniated IVDs provide an important pathomechanism in hypertrophy and ossification of the LF through inflammatory cytokines.

In this study, the five-DOF motion at ultra-precision linear stage under static and dynamic conditions are evaluated through the extending application of ISO 230-2. As the performance factors, the bi-directional accuracy and repeatability of the five-DOF motion are quantitatively evaluated with the measurement uncertainties which are determined using the standard uncertainty of equipment used in experiment. The motion under static condition are analyzed using geometric errors. The five geometric errors except the linear displacement error are measured using optimal measurement system which is designed to enhance the standard uncertainty of geometric errors. In addition, the motion under dynamic conditions are analyzed with respect to the conditions with different feed rate of the stage. The experimental results shows that the feed rate of stage has a significant effect on straightness motions.

In this study, the performance of five-DOF motion in ultra-precision linear stage is evaluated accurately by extending the application of the ISO 230-2 International Standard, which is focused only on the linear displacement motion of a linear stage. The bidirectional accuracy and bidirectional repeatability of positioning in five-DOF motion are calculated by measured geometric errors. Five geometric errors except for the linear displacement error of a linear stage are measured simultaneously using the optimal measurement system, which is designed to enhance the standard uncertainty of the estimated geometric errors. The geometric errors are in good agreement with those from the laser interferometer. In addition, the confidence intervals of the performances are determined by the uncertainties of the equipment used in the experiment.

In this study, the accuracy of a machine tool was evaluated by modeling the spherical deviation based on double ball-bar measurements under unloaded conditions. Circular measurement paths on the XY -, YZ -, and ZX- planes were planned, and three linear axis drives were commanded to follow the paths describing a nominal sphere. The spherical deviation, defined as the maximum radial range of deviations around a least-squares sphere, is affected by the accuracies of the three linear axes together. Therefore, the spherical deviation represents the accuracy of machine tools by quantifying the effect of the accuracies of three linear axes, whereas the circular deviation only quantifies the accuracies of two linear axes among the three linear axes. In this experimental study, spherical deviations of vertical/horizontal machine tools were measured and analyzed under various nominal lengths of a double ball-bar for various feed rates. The measurement uncertainty of the measured spherical deviation was investigated to determine the confidence interval.

In this study, a measurement method of double ball-bar is proposed to measure the geometric errors of an ultra-precision roll mold machine tool. A volumetric error model of the machine tool is established to investigate the effects of the geometric errors to a radius error and a cylindricity of the roll mold. A measurement path is suggested for the geometric errors, and a ball-bar equation is derived to represent the relation between the geometric errors and a measured data of the double ball-bar. Set-up errors, which are inevitable at the double ball-bar installation, also are analyzed and are removed mathematically for the measurement accuracy. In addition, standard uncertainty of the measured geometric errors is analyzed to determine the experimental condition. Finally, the proposed method is tested and verified through simulation.

In this study, position-independent geometric errors, including offset errors and squareness errors of rotary axes of a five-axis machine tool are measured using a double ball-bar and are verified through compensation. In addition, standard uncertainties of measurement results are calculated to establish their confidence intervals. This requires two measurement paths for each rotary axis, which are involving control of single rotary axis during measurement. So, the measurement paths simplify the measurement process, and reduce measurement cost including less operator effort and measurement time. Set-up errors, which are inevitable during the installation of the balls, are modeled as constants. Their effects on the measurement results are investigated to improve the accuracy of the measurement result. A novel fixture consisting of flexure hinges and two pairs of bolts is used to minimize set-up error by adjusting the ball's position located at the tool nose. Simulation is performed to check the validation of measurement and to analyze the standard uncertainties of the measurement results. Finally, the position-independent geometric errors of the five-axis machine tool (involving a rotary axis and a trunnion axis) are measured using proposed method.

It is essential and fundamental to extract boundary information of target object via massive three-dimensional point data acquired from laser scanner. Especially extracting boundary information of manmade features such as buildings is quite important because building is one of the major components consisting complex contemporary urban area, and has artificially defined shape. In this research, extended -algorithm using geometry information of point data was proposed to extract boundary information of building from three-dimensional point data consisting building. The proposed algorithm begins with composing Delaunay triangulation process for given points and removes edges satisfying specific conditions process. Additionally, to make whole boundary extraction process efficient, we used Sweep-hull algorithm for constructing Delaunay triangulation. To verify the performance of the proposed extended -algorithm, we compared the proposed algorithm with Encasing Polygon Generating Algorithm and -Shape Algorithm, which had been researched in the area of feature extraction. Further, the extracted boundary information from the proposed algorithm was analysed against manually digitized building boundary in order to test accuracy of the result of extracting boundary. The experimental results showed that extended -algorithm proposed in this research proved to improve the speed of extracting boundary information compared to the existing algorithm with a higher accuracy for detecting boundary information.

In this study, we propose a robust and simple method using double ball-bar to measure position-independent geometric errors of a rotary axis involving single axis control during the measurement. The standard uncertainty for the proposed method is analyzed to quantify the confidence interval of the measurement result. Two measurement paths are planned to measure the position-independent geometric errors, including two offset errors and two squareness errors of a rotary axis. An error synthesis model using homogenous transform matrices and a ball-bar equation to represent the relation between the positions of two balls and the measured distance between them are used. Set-up errors, which are inevitable during the installation of the balls, are modeled as constants and added to the design position of the balls. Their effects on the measurement result are investigated in detail. Furthermore, a novel fixture consisting of flexure-hinges located at the tool nose is developed to minimize the set-up errors of the ball and to robustly keep the position of the ball during measurements. Finally, the proposed method is validated using simulation and is applied to the rotary axis located on a five-axis machine tool.