Fiber Jacket Research Articles

Finite element analysis of optimized novel additively manufactured non-articulating prostheses for cervical total disc replacement.

Ball-and-socket designs of cervical total disc replacement (TDR) have been popular in recent years despite the disadvantages of polyethylene wear, heterotrophic ossification, increased facet contact force, and implant subsidence. In this study, a non-articulating, additively manufactured hybrid TDR with an ultra-high molecular weight polyethylene core and polycarbonate urethane (PCU) fiber jacket, was designed to mimic the motion of normal discs. A finite element (FE) study was conducted to optimize the lattice structure and assess the biomechanical performance of this new generation TDR with an intact disc and a commercial ball-and-socket Baguera®C TDR (Spineart SA, Geneva, Switzerland) on an intact C5-6 cervical spinal model. The lattice structure of the PCU fiber was constructed using the Tesseract or the Cross structures from the IntraLattice model in the Rhino software (McNeel North America, Seattle, WA) to create the hybrid I and hybrid II groups, respectively. The circumferential area of the PCU fiber was divided into three regions (anterior, lateral and posterior), and the cellular structures were adjusted. Optimal cellular distributions and structures were A2L5P2 in the hybrid I and A2L7P3 in the hybrid II groups. All but one of the maximum von Mises stresses were within the yield strength of the PCU material. The range of motions, facet joint stress, C6 vertebral superior endplate stress and path of instantaneous center of rotation of the hybrid I and II groups were closer to those of the intact group than those of the Baguera®C group under 100N follower load and pure moment of 1.5 Nm in four different planar motions. Restoration of normal cervical spinal kinematics and prevention of implant subsidence could be observed from the FE analysis results. Superior stress distribution in the PCU fiber and core in the hybrid II group revealed that the Cross lattice structure of a PCU fiber jacket could be a choice for a next-generation TDR. This promising outcome suggests the feasibility of implanting an additively manufactured multi-material artificial disc that allows for better physiological motion than the current ball-and-socket design.

Warp-knitted fabric structures for a novel biomimetic artificial intervertebral disc for the cervical spine

As an attempt to better replicate the complex kinematics of a natural disc, a novel biomimetic artificial intervertebral disc replacement (bioAID) has been developed containing a swelling hydrogel core as nucleus pulposus, a fiber jacket as annulus fibrosus and metal endplates to connect the device to the adjacent vertebrae. The first prototype consisted of a weft-knitted fiber jacket, in which only a single fiber was used to create the jacket structure. This can endanger the structural integrity of the complete device upon yarn damage. Therefore, in this study, several warp-knitted textile structures were assessed to (1) ensure structural integrity, (2) while allowing for swelling constraint of the hydrogel and (3) behaving as one integrated unit similar to the natural IVD. Moreover, the fiber jacket should (4) act as a scaffold that allows bone ingrowth to ensure long-term stability and (5) have a good durability, (6) be wear resistant and (7) have good manufacturing feasibility with good quality control. In this study, 4 different stitch patterns, including 2 × 1 and 1 × 1 lapping with and without a pillar stitch, were produced. The effect of the stitch pattern and stitch density on the fabric mechanical properties and device swelling and compressive strength was assessed. As a next step, the effect of using multiple layers of fabrics, mimicking the layered structure of annulus fibrosus, on the functional capacity of the bioAID was characterized. All textile structures were capable of limiting the swelling of the hydrogel while withstanding its internal pressure and showing sufficient wear resistance. However, only the 2 × 1 and 2 × 1 with pillar stitch had a pore size range that was suitable for cell infiltration to facilitate osseointegration as well as having the highest strength of the complete device to ensure safety under compression loading. Incorporating different number of jacket layers of these two stitch patterns did not show any significant effect. When also taking the structural parameters into consideration, the 2 × 1 lapping design with 4 layers was able to constrain hydrogel swelling, provide a high compressive strength, could facilitate cell infiltration and had dimensions within the range of a natural intervertebral disc.

Mechanical characterization of a novel biomimetic artificial disc for the cervical spine

A novel biomimetic artificial intervertebral disc (bioAID) replacement implant has been developed containing a swelling hydrogel representing the nucleus pulposus, a tensile strong fiber jacket as annulus fibrosus and titanium endplates with pins to primarily secure the device between the vertebral bodies. In this study, the design safety of this novel implant was evaluated based on several biomechanical parameters, namely compressive strength, shear-compressive strength, risk of subsidence and device expulsion as well as identifying the diurnal creep-recovery characteristics of the device.The bioAID remained intact up to 1 kN under static axial compression and only 0.4 mm of translation was observed under a compressive shear load of 20 N. No subsidence was observed after 0.5 million cycles of sinusoidal compressive loading between 50 and 225 N. After applying 400 N in antero-posterior direction under 100 N axial compressive preload, approximately 2 mm displacement was found, being within the range of displacements reported for other commercially available cervical disc replacement devices. The diurnal creep recovery behavior of the bioAID closely resembled what has been reported for natural intervertebral discs in literature.Overall, these results indicate that the current design can withstand (shear-compression loads and is able to remain fixed in a mechanical design resembling the vertebral bodies. Moreover, it is one of the first implants that can closely mimic the poroelastic and viscoelastic behavior of natural disc under a diurnal loading pattern.

MP68-01 PATTERN ANALYSIS OF LASER FIBER DEGRADATION ACCORDING TO THE LASER SETTING: IN VITRO STUDY OF THE DOUBLE-FIRING PHENOMENON

You have accessJournal of UrologyCME1 Apr 2023MP68-01 PATTERN ANALYSIS OF LASER FIBER DEGRADATION ACCORDING TO THE LASER SETTING: IN VITRO STUDY OF THE DOUBLE-FIRING PHENOMENON Sang Won So, Gyoohwan Jung, Hyeji Park, and Sung Yong Cho Sang Won SoSang Won So More articles by this author , Gyoohwan JungGyoohwan Jung More articles by this author , Hyeji ParkHyeji Park More articles by this author , and Sung Yong ChoSung Yong Cho More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003331.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: It is essential to understand the mechanism of the various causes of laser fiber damage and an ideal method of reducing endoscope damage induced by laser emission in multiple sites. This study classified the different patterns of laser fiber degradation according to laser settings and analyzed the role of cavitation bubbles to find a desirable way of minimizing endoscope damage. METHODS: A total of 118 laser fibers were analyzed after 1-,3-, and 5-min laser emission to artificial stones under the settings of 1J-10Hz, 1J-20Hz, 1J-30Hz, and 2J-10Hz. Every 3cm from the fiber tip was marked and examined with a digital microscope and a high-speed camera. The images of the fibers and the movement of cavitation bubbles were taken with a distance of 1 to 5 mm from the gel. RESULTS: Seven types of fiber damage (charring, limited and extensive peeled-off, bumpy, whitish plaque, crack, and break-off) coincided during laser emission. Damages rapidly increased with emission time>3 min regardless of the laser settings. The damaged lengths covered 5 mm on average, and the fibers at 5-min emission were significantly shorter than others. The fiber durability of 1J-10Hz setting was better than other settings after 3-min laser emission. Backward movement of the cavitation bubbles was found at the 1-mm distance from the gel, and the damaged lengths were longer than the diameters of the cavitation bubbles because of their proximal movement. CONCLUSIONS: The damage patterns of the laser fiber tips were classified into seven types. The heat damage around the surface of the laser fiber can be increased according to the high-energy or high-frequency laser setting, a short distance to the stone, a short distance from the tips of flexible ureteroscopes, no cutting laser fiber procedures, and the inappropriate use of irrigation fluid or laser fiber jacket. Source of Funding: This work was supported by a grant No. 2019R1C1C1008339 mainly and another one No. 2017R1A2B3007907 in part of the National Research Foundation (NRF) grant funded by the Korean government (MSIT) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e952 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Sang Won So More articles by this author Gyoohwan Jung More articles by this author Hyeji Park More articles by this author Sung Yong Cho More articles by this author Expand All Advertisement PDF downloadLoading ...

Numerical study on the behavior and strength of concrete beam strengthening with fiber reinforced concrete jackets

The recent experimental results for slender reinforced concrete beams with a thin steel fiber reinforced concrete (SFRC) jacket have demonstrated their feasibility in enhancing the performance in terms of serviceability and ultimate limit states and strongly suggested the need for a comprehensive analysis to show the effect of important parameters. Within this context, the bond between reinforced concrete (RC) beams and SFRC jacket is an essential parameter to avoid any slippage failure before the beam achieves its shear capacity. The behavior of the bonded element is affected by slip at the interface between the old and new concrete. However, it is common in design to ignore slip and consider the bonded element monolithic. The values of slip and shear stress relation of the strengthened element are reviewed in this paper. In addition, an analytical procedure for predicting the distribution of slip along the interface between the initial beam and the new layer of concrete is presented. The research paper aims to develop a detailed three-dimensional (3D) finite element (FE) model for evaluating the structural performance of RC beams strengthened with SFRC jackets taking into accountthe effect of the bond between the beam and the jacket. It also aims to investigate the effect of significant parameters on the response of strengthened RC beams in shear. These parameters are as follows: jacket compressive strength (30, 60, and 85 MPa), fiber volume fraction (0.5, 1.0, 1.5, and 3.0%), jacket thickness (30, 40, 50, and 60 mm), and spacing between shear connectors (100, 200, and 500 mm). The proposed model's results were compared to those of previous experimental research. The analysis result showsgood agreement with the correlating experimental measurement. The parametric study results proved that increasing the volume fraction of fiber, jacket thickness, and compressive strength of the jacketincreases ductility and shear capacity. Increasing the spacing between shear connectors has no noticeable effect on shear capacity but prevents debonding. Finally, reference equations were made to study the behavior of RC beams strengthened with SFRC jackets, taking into accountthe effect of the bond between the beam and the jacket.

Biomechanical evaluation of a novel biomimetic artificial intervertebral disc in canine cervical cadaveric spines.

Cervical disc replacement (CDR) aims to restore motion of the treated level to reduce the risk of adjacent segment disease (ASD) compared with spinal fusion. However, first-generation articulating devices are unable to mimic the complex deformation kinematics of a natural disc. Thus, a biomimetic artificial intervertebral CDR (bioAID), containing a hydroxyethylmethacrylate (HEMA)-sodium methacrylate (NaMA) hydrogel core representing the nucleus pulposus, an ultra-high-molecular-weight-polyethylene fiber jacket as annulus fibrosus, and titanium endplates with pins for primary mechanical fixation, was developed. To assess the initial biomechanical effect of the bioAID on the kinematic behavior of the canine spine, an ex vivo biomechanical study in 6-degrees-of-freedom was performed. A canine cadaveric biomechanical study. Six cadaveric canine specimens (C3-C6) were tested in flexion-extension (FE), lateral bending (LB) axial rotation (AR) using a spine tester in three conditions: intact, after C4-C5 disc replacement with bioAID, and after C4-C5 interbody fusion. A hybrid protocol was used where first the intact spines were subjected to a pure moment of ±1Nm, whereafter the treated spines were subjected to the full range of motion (ROM) of the intact condition. 3D segmental motions at all levels were measured while recording the reaction torsion. Biomechanical parameters studied included ROM, neutral zone (NZ), and intradiscal pressure (IDP) at the adjacent cranial level (C3-C4). The bioAID retained the sigmoid shape of the moment-rotation curves with a NZ similar to the intact condition in LB and FE. Additionally, the normalized ROMs at the bioAID-treated level were statistically equivalent to intact during FE and AR while slightly decreased in LB. At the two adjacent levels, ROMs showed similar values for the intact compared to the bioAID for FE and AR and an increase in LB. In contrast, levels adjacent to the fused segment showed an increased motion in FE and LB as compensation for the loss of motion at the treated level. The IDP at the adjacent C3-C4 level after implantation of bioAID was close to intact values. After fusion, increased IDP was found compared with intact but did not reach statistical significance. This study indicates that the bioAID can mimic the kinematic behavior of the replaced intervertebral disc and preserves that for the adjacent levels better than fusion. As a result, CDR using the novel bioAID is a promising alternative treatment for replacing severely degenerated intervertebral discs.

Surface modifications to promote the osteoconductivity of ultra-high-molecular-weight-polyethylene fabrics for a novel biomimetic artificial disc prosthesis: An in vitro study.

A novel biomimetic artificial intervertebral disc (bioAID) for the cervical spine was developed, containing a hydrogel core representing the nucleus pulposus, an UHMWPE fiber jacket as annulus fibrosis, and titanium endplates with pins for mechanical fixation. Osseointegration of the UHMWPE fibers to adjacent bone structures is required to achieve proper biomimetic behavior and to provide long-term stability. Therefore, the aim of this study was to assess the osteoconductivity of several surface modifications of UHMWPE fabrics, 2D weft-knitted, using non-treated UHMWPE fibers (N), plasma treated UHMWPE fibers (PT), 10% hydroxy apatite (HA) loaded UHMWPE fibers (10%HA), plasma treated 10%HA UHMWPE fibers (PT-10%HA), 15%HA loaded UHMWPE fibers (15%HA) and plasma treated 15%HA UHMWPE fibers (PT-15%HA). Scanning electron microscopy (SEM) was used for surface characterization. Biological effects were assessed by evaluating initial cell attachment (SEM, DNA content), metabolic activity (PrestoBlue assay), proliferation, differentiation (alkaline phosphatase activity) and mineralization (energy dispersive x-ray, EDX analysis) using human bone marrow stromal cells. Plasma treated samples showed increased initial cell attachment, indicating the importance of hydrophilicity for cell attachment. However, incorporation only of HA or plasma treatment alone was not sufficient to result in upregulated alkaline phosphatase activity (ALP) activity. Combining HA loaded fibers with plasma treatment showed a combined effect, leading to increased cell attachment and upregulated ALP activity. Based on these results, combination of HA loaded UHMWPE fibers and plasma treatment provided the most promising fabric surface for facilitating bone ingrowth.

Pattern Analysis of Laser Fiber Degradation According to the Laser Setting: In Vitro Study of the Double-Firing Phenomenon.

BackgroundIt is essential to understand the mechanism of the various causes of laser fiber damage and an ideal method of reducing endoscope damage induced by laser emission in multiple sites. This study classified the different patterns of laser fiber degradation according to laser settings and analyzed the role of cavitation bubbles to find a desirable way of minimizing endoscope damage.MethodsA total of 118 laser fibers were analyzed after 1-,3-, and 5-min laser emission to artificial stones under the settings of 1 J-10 Hz, 1 J-20 Hz, 1 J-30 Hz, and 2 J-10 Hz. Every 3 cm from the fiber tip was marked and examined with a digital microscope and a high-speed camera. The images of the fibers and the movement of cavitation bubbles were taken with a distance of 1 to 5 mm from the gel.ResultsSeven types of fiber damage (charring, limited and extensive peeled-off, bumpy, whitish plaque, crack, and break-off) coincided during laser emission. Damages rapidly increased with emission time > 3 minutes regardless of the laser settings. The damaged lengths covered 5 mm on average, and the fibers at 5-min emission were significantly shorter than others. The fiber durability of 1J-10Hz setting was better than other settings after 3-min laser emission. Backward movement of the cavitation bubbles was found at the 1-mm distance from the gel, and the damaged lengths were longer than the diameters of the cavitation bubbles because of their proximal movement.ConclusionThe damage patterns of the laser fiber tips were classified into seven types. The heat damage around the surface of the laser fiber can be increased according to the high-energy or high-frequency laser setting, a short distance to the stone, a short distance from the tips of flexible ureteroscopes, no cutting laser fiber procedures, and the inappropriate use of irrigation fluid or laser fiber jacket.

Experimental analysis and design strength models adopted by international guides for FRP-confined concrete columns subjected to axial compression

Carbon fiber jacketing is an efficient technique for increasing the strength and strain capacity of concrete circular and square section columns subjected to axial load, although confinement efficiency decreases for rectangular cross-section members. The research project BIA 2016-80310-P includes an experimental program on intermediate-size plain concrete specimens strengthened with carbon fiber jackets, mostly with square and rectangular cross-sections. The results, alongside others with similar characteristics from two databases published, are compared to predictions of four international guides. The incidence of the key parameters in the experimental results is analyzed, such as the aspect ratio of the section, the effective strain in FRP jacket attained at failure or the rounded corner radius. As a result, two efficiency strain factors are proposed, one for circular and another for rectangular specimens. The predictions contained in certain guides, based on a simple linear design-model, are improved by using the proposed efficiency strain factor for rectangular sections.

FLEXURAL BEHAVIOR OF STRENGTHENED AND RPIARED SUSTAINABLE R.C. BEAMS USING REACTIVE POWDER CONCRETE JACKET

Thin fiber reinforcement and rehabilitation of reinforced concrete beams Concrete jackets have several benefits, including increased ultimate load and improved serviceability limit condition. The current paper was carried out to investigate the effect of the strengthening and repairing by using reactive powder concrete(RPC) jacket for reinforced concrete beams that’s casted with recycled coarse aggregate (RCA) in enhancement the mechanical properties such as load capacity and deflection . Nine reinforced concrete beams mm were casted by using RCA with constant details and jacketed with RPC with variable of steel fiber content and jacket thickness to estimate the optimum details. The result showed the effectiveness of the proposed technique in both deflection and ultimate load.

How to reduce 'double-firing'-induced scope damage by investigating the relationship between laser fiber core degradation and fiber jacket burn?

Purpose'Double-firing effect' in which laser firing occurs in the fiber tip and its proximal part is caused by different breakdown rates between fiber jackets and cores. This study investigated a new safe distance concept to prevent scope damage by analyzing the breakdown of the laser fiber jacket and cores.MethodsLaser fibers were fixed in a benchtop simulation model. The fiber tip was in contact with uniform phantom stones and submerged in saline. Four different energy settings (1.0 or 2.0J x 10Hz or 30Hz) and two different fiber sizes (200 μm and 365 μm) were tested. After three minutes of use at each energy setting, the length of fiber shortening and jacket burn were measured. The fibers were stripped to measure the length of core degradation.ResultsMean degradation lengths were 4.2 to 7.8 mm. There was no statistical difference in the mean lengths of fiber core degradation and jacket burn. However, core degradation was longer than the jacket burn in half of the samples. The mean difference in lengths between core degradation and jacket burn was 0.49 ± 0.90 mm. Lengths of core degradation and the jacket burn were longer at the setting of high-power energy and 200 μm fiber - 2J with 30 Hz.ConclusionTo reduce ‘double-firing’-induced damage, the authors recommend that laser fiber should be cut 1.0 mm longer than visible jacket burn at high-power settings after 3-min continuous fragmentation. After cutting the fiber, the laser should be checked whether ‘double-firing’ is no more seen.

Performance Characteristics of Photoacoustic Imaging Probes with Varying Frequencies and Light-delivery Schemes.

Photoacoustic imaging (PAI) is an emerging biomedical imaging technique that utilizes a combination of light and ultrasound to detect photoabsorbers embedded within tissues. While the clinical utility of PAI has been widely explored for several applications, limitations in light penetration and detector sensitivity have restricted these studies to mostly superficial sites. Given the importance of PA signal generation and detection on light delivery and ultrasound detector frequency, there is an ongoing effort to optimize these parameters to enhance photoabsorber detection at increased depths. With this in mind, in this study we examined performance benchmarks of a commercially available PAI/ultrasound linear array system when using different imaging frequencies and light delivery schemes. A modified light fiber jacket providing focused light delivery (FLD) at the center of the probe was compared with the built-in fiber optics lining the length of the probe. Studies were performed in vitro to compare performance characteristics such as imaging resolution, maximum imaging depth, and sensitivity to varying hematocrit concentration for each frequency and light delivery method. Monte Carlo simulations of each light delivery method revealed increased light penetration with FLD. In tissue-mimicking phantoms, vascular channels used to simulate blood vessels could be visualized at a depth of 2.4 cm when lowering imaging frequency and utilizing FLD. Imaging at lower frequencies with FLD also enabled enhanced detection of varying hematocrit concentration levels at increased depths, although lateral imaging resolution was reduced. Finally, a proof of concept in vivo probe comparison study in a mouse tumor model provided supportive evidence of our in vitro results. Collectively, our findings show that adjusting imaging frequency and applying FLD can be a straightforward approach for improving PAI performance.

Thulium fiber laser ablation of kidney stones using an automated, vibrating fiber.

.Our preliminary study investigates an automated, vibrating fiber optic tip for dusting of kidney stones during thulium fiber laser (TFL) lithotripsy. A (0.75-mm diameter and 5-mm length) magnetic bead was attached to the fiber jacket, centered 2 cm from distal fiber tip. A solenoid was placed parallel to the fiber with a 0.5-mm gap between solenoid and magnetic bead on fiber. The solenoid was used to create a magnetic force on the bead, inducing fiber vibration. Calibration tests for fiber motion in both air and water were performed. The ablation crater characteristics (surface area, volume, depth, and major/minor axis) of uric acid stones were measured using optical coherence tomography, after delivery of 1500 TFL pulses at 1908 nm, 33 mJ, , and up to 300 Hz, through 50-, 100-, and -core fibers. The resonant frequency was dependent on fiber diameter and rigidity, with a cutoff pivot point for optimum vibration amplitude at 4 cm. Maximum fiber displacement is about 1 mm in water and 4 mm in air. For 50-, 100-, and -core fibers, ablated surface area averaged 1.7, 1.7, and 2.8 times greater with vibrating fiber than fixed fiber, respectively. For these fibers, ablation volume averaged 1.1, 1.5, and 1.1 times greater with vibrating fiber than fixed fiber, given a fixed energy per pulse, respectively. Our preliminary study demonstrates the functionality of an automated, vibrating fiber system for stone “dusting,” with significantly larger surface area but similar ablation volumes as a fixed fiber. Future studies will focus on optimization of fiber parameters (especially displacement) and miniaturization of system components to facilitate integration into ureteroscopes.

Inscribing an output coupler grating directly through the fiber coating with a 266 nm femtosecond laser

We inscribe with 266nm femtosecond pulses a ∼0.75% output coupler for a 1550nm fiber laser directly through the coating of an SMF-28. The output coupler was inscribed with the phase-mask technique without H2 loading. This output coupler was spliced to an active Er/Yb fiber, and a fiber laser with an output power of ∼6.4 W and a slope efficiency of ∼30% was obtained. To the best of our knowledge, this is the first reported attempt to inscribe a fiber Bragg grating through the polymer jacket of an optical fiber with a UV femtosecond laser.

Detection of Thermal Strain in Steel Rails with BOTDA

Rail transportation is one of the most important and efficient forms of transportation. Large thermal strain can develop in the rail steel due to extreme climatic conditions resulting in safety related issues. We carried out a thermal-strain monitoring test on the rail specimen over a large temperature range from −40 ∘ C to +50 ∘ C using a Brillouin optical time-domain analyzer (BOTDA) for the first time, to the best of our knowledge. Two jacketed fibers and small-diameter carbon/polyimide-coating single-mode fiber were used for the purpose of investigating the jacket effect of thermal-strain detection on the rail. Although a nonlinear response to the temperature of the loose jacketed fiber was found, it was applicable for thermal strain monitoring when glued on the surface of the rail sample. The measured thermal strain in the rail specimen was validated by the results obtained by the strain gauge. The thermally induced strain from the large rail specimen was found to have suppressed the nonlinear impact of the fiber jacket.

TH-AB-201-11: A Systematic Characterization of the Low Energy Response of Plastic Scintillation Detectors

Purpose: To characterize the low energy behavior of scintillating material used in plastic scintillation detectors. Methods: Four plastic scintillation detectors (PSDs) were developed using three different scintillating material (BCF-10, BCF-12, BCF-60) and one scintillator-free fiber. The scintillators were 1 mm in diameter and 10 mm-long, coupled to a 15 meter long clear PMMA optical fiber. A photomultiplier tube was connected to this fiber to collect the scintillator’s light signal. All fibers were covered by a light-tight polyethylene jacket. The PSDs were exposed to AAPM accredited low energy beam qualities ranging from 20 kVp to 250 kVp. Their response described the dose in polystyrene and was compared to the dose in air measured by a primary calibration chamber located at the beam exit. The mean energy and the spectral method were used to extract the effective mass energy-absorption coefficient using NIST database for each beam quality reference spectrum. Attenuation in air and in the fiber jacket were also considered. The scintillators expected response was compared to the experimental measurements and an energy-dependent correction factor was identified to account for low energy quenching occurring within the scintillators. Results: The clear optical fiber response was below 0.5% of the scintillator’s light, which indicated that a negligible amount of fluorescence contamination was produced. The scintillators response increased by a factor 3.65 ± 0.07 between a 20 kVp and a 250 kVp beam. The correction factor varied with beam energy and remained above 84% for beam qualities of 30 kVp and above, but drops for very low energy (20 kVp) to about 77%. Conclusion: This work describes the PSD energy dependence to low energy beam qualities and identifies a correction factor related to low energy quenching. A detailed comprehension of intrinsic scintillator response is essential when designing accurate PSD dosimeters for radiology purposes. This work was supported in part by a NIH/NCI SBIR grant R44CA153824 and by grant # 435510 from the NSERC. JB is supported by a FQRNT doctoral research scholarchip and acknowledges partial support by the NSERC CREATE Medical Physics Research Training Network grant # 432290.

Stimulatory Effect of Notochordal Cell-Conditioned Medium in a Nucleus Pulposus Explant Culture

Introduction Notochordal cell-conditioned medium (NCCM) has shown to stimulate matrix production by nucleus pulposus cells (NPCs) in alginate bead cultures.1,2 This cell culture method, however, provides a markedly different environment than the nucleus pulposus (NP) tissue, in which the bioactive factors should exert their effect. Therefore, the main objective of this study was to test the stimulatory effect of NCCM in an NP explant culture system. Materials and Methods NCCM was generated by incubating porcine NC-rich NP tissue in plain high glucose DMEM (hgDMEM) at 37°C, 5% CO2 and 5% O2 for 4 days. The medium was filtered and the filtrate was resuspended in fresh hgDMEM. NP tissue samples were isolated from the caudal IVDs of 2-year old cows ( n = 5), excluding the annulus fibrosus (AF) tissue. The NP tissues were cultured, according to a previously established method,3 in a fiber jacket, constraining the tissue and thereby acting as an AF. Samples were cultured in base medium (BM: hgDMEM supplemented with pen/strep, ITS, ascorbic acid, proline, bovine serum albumin, and sodium pyruvate), NCCM, supplemented with the same factors as BM, or positive control medium (Pos, BM supplemented with 1 µg/mL Link-N). After 4 weeks, NP tissue explants were assayed for water, GAG, DNA, and hydroxyproline content, histology with safranin O/fast green staining and gene expression of collagen type 1 and 2, aggrecan, and SOX9. Results The GAG content of tissue explants treated with NCCM significantly increased ( p < 0.05) compared with day 0 and BM ( Fig. 1a ). GAG content in the positive control group tended to increase compared with BM ( p = 0.086). This was confirmed by safranin O/fast green staining, showing a more intense red staining for the NCCM culture group ( Fig. 1b ). No significant differences were observed between groups regarding water, DNA, and hydroxyproline content. Gene expression results did not confirm the finding of the biochemical content assays. The relative expression of collagen type 1 and 2, aggrecan and SOX9 did not differ between groups, and only minor changes were observed compared with day 0. NCCM may have an initial and a transient stimulatory effect on transcriptional level, which could explain why the stimulatory effect of NCCM after 4 weeks of culture was not observed at the gene level. Nevertheless, we cannot exclude that GAGs originating from the NCCM may have been incorporated into the NP tissue explant during culture. Conclusion These results confirm the stimulatory effect of NCCM in an NP tissue explant culture. Moreover, NCCM appears to be at least as potent as Link-N, of which the stimulatory effect on NP tissue has been previously established in vivo.4 This study, therefore provides further evidence for the promising role of NCCM in the treatment of IVD regeneration. Identification of the bioactive factors in NCCM will be helpful to further develop a treatment method and achieve maximal anabolic effects. Acknowledgment This work was supported by AOSpine International through an AOSpine Research Network grant (SRN2011_11). [Figure: see text] References Potier E, de Vries S, van Doeselaar M, Ito K. Potential application of notochordal cells for intervertebral disc regeneration: an in vitro assessment. Eur Cell Mater 2014;28:68–80, discussion 80–81 Abbott RD, Purmessur D, Monsey RD, Iatridis JC. Regenerative potential of TGFb3 + Dex and notochordal cell conditioned media on degenerated human intervertebral disc cells. J Orthop Res 2012;30(3):482–488 van Dijk BG, Potier E, Ito K. Long-term culture of bovine nucleus pulposus explants in a native environment. Spine J 2013;13(4):454–463 Mwale F, Masuda K, Pichika R, et al. The efficacy of Link N as a mediator of repair in a rabbit model of intervertebral disc degeneration. Arthritis Res Ther 2011;13(4):R120

Embedded Fiber Optic Sensors Within Additive Layer Manufactured Components

Smart materials with integrated sensing capabilities are now ubiquitous in many structures and devices manufactured from composite materials and they offer enhanced safety, reliability and efficiency in such smart devices. This paper explores the application of embedded sensors to components manufactured using additive layer manufacturing (ALM) technology. ALM offers the ability to create physical parts with little or no restriction in shape and complexity. In this paper, optical fiber sensors incorporating fiber Bragg gratings are embedded inside a component made by, and during a powder-bed-based, layer-by-layer, additive manufacturing process. A commercial EOS P730 system is used, where a laser is employed to sinter the polymeric powder into a 3D component. The fiber embedding approach is based upon insertion of a “fiber-carrier” component, which replaces a removable “place-holder” component during an interruption of the ALM build process. Tensile test specimens fabricated this way are subjected to extended cyclic tensile loading trials at low strain levels of up to 580 μe . The test specimens demonstrate stable and reproducible responses over a period in excess of 720 days and 311000 load cycles. Polyimide and acrylic jacketed fibers are trialled, and the resulting deformations of the component through internal stresses depending on the fiber jacket type are discussed.

Long-term culture of bovine nucleus pulposus explants in a native environment

Background contextChronic low back pain is a disease with tremendous financial and social implications, and it is often caused by intervertebral disc degeneration. Regenerative therapies for disc repair are promising treatments, but they need to be tested in physiological models. PurposeTo develop a physiological in vitro explant model that incorporates the native environment of the intervertebral disc, for example, hypoxia, low glucose, and high tissue osmolarity. Study designBovine nucleus pulposus (NP) explants were cultured for 42 days in conditions mimicking the native physiological environment. Two different approaches were used to balance the swelling pressure of the NP: raised medium osmolarity or an artificial annulus. MethodsBovine NP explants were either cultured in media with osmolarity balanced at isotonic and hypertonic levels compared with the native tissue or cultured inside a fiber jacket used as an artificial annulus. Oxygen and glucose levels were set at either standard (21% O2 and 4.5 g/L glucose) or physiological (5% O2 and 1 g/L glucose) levels. Samples were analyzed at Day 0, 3, and 42 for tissue composition (water, sulfated glycosaminoglycans, DNA, and hydroxyproline contents and fixed charge density), tissue histology, cell viability, and cellular behavior with messenger RNA (mRNA) expression. ResultsBoth the hypertonic culture and the artificial annulus approach maintained the tissue matrix composition for 42 days. At Day 3, mRNA expressions of aggrecan, collagen Type I, and collagen Type II in both hypertonic and artificial annulus cultures were not different from Day 0; however, at Day 42, the artificial annulus preserved the mRNA expression closer to Day 0. Gene expressions of matrix metalloprotease 13, tissue inhibitor of matrix metalloprotease 1, and tissue inhibitor of matrix metalloprotease 2 were downregulated under physiological O2 and glucose levels, whereas the other parameters analyzed were not affected. ConclusionsAlthough the hypertonic culture and the artificial annulus approach are both promising models to test regenerative therapies, the artificial annulus was better able to maintain a cellular behavior closer to the native tissue in longer term cultures.

Characterization of Mortar with Mineral Additives

ABSTRACTIt has been an increase on the number of concrete structures with corrosion induced damage in Mexico in recent years. It is also well known that cathodic protection (CP) is the only method that stops corrosion in an efficient way. Since the 1990’s Florida and other USA states have been installing in concrete pile substructures, in bridges and piers, a three part hybrid galvanic CP system. This hybrid galvanic CP system includes a thermal sprayed part (located at the aerial zone of the pile), a zinc mesh encapsulated in mortar and inside a glass fiber jacket (located at the change in ties zone), and a submerged zinc bulk anode (in the submerged zone). From a previous investigation performed by the present authors, it has been found that the mortar inside the fiberglass form may decrease the mesh anode activation and thus decrease the CP system efficiency. Therefore, this investigation includes an evaluation of different additions placed in mortar to increase its electrical and ionic conductivity to increase the efficiency of the entire hybrid system. Additions include carbon, zinc and alumina powders, and this investigation presents preliminary experimental results obtained from the tested mortars (i.e. mortar physical characterization: electrical resistivity, ultrasonic pulse velocity, and total void content).