Radial Extension Research Articles

A fracture evaluation by acoustic logging technology in oil-based mud: A case from tight sandstone reservoirs in Keshen area of Kuqa Depression, Tarim Basin, NW China

Abstract To solve the problem of poor fracture identifying effect on electrical logging in oil-based mud, the application of acoustic logging to the quantitative characterisation of fractures is expanded from three aspects, namely, Stoneley waves, longitudinal and transverse waves and cross dipole acoustic waves, and a fracture logging evaluation model closely related to production capacity is established considering the radial extension characteristics of fractures. The Stoneley reflection coefficient is used to determine fractures locations to help detect fractures during normal micro-resistivity imaging logging. Based on the experiment on the relationship between fracture width and acoustic attenuation coefficient, empirical formulae for calculating fracture width have been established by primary wave and shear wave energy information considering the effect of porosity. The new parameters, including spectrum correlation coefficient and energy difference from cross dipole array acoustic logging data, can be used for fractures evaluation. The more developed the fractures are, the greater the energy difference becomes, and the smaller the spectrum correlation coefficient is, the higher the production is. The fracture effective evaluation parameters can be separated into two components, specified as the degree of fracture vertical opening and radial extension. Combining the conventional logging and array acoustic logging (including cross dipole array acoustic logging), a fracture radial extension evaluation model is presented closely related to productivity.

On the influence of thermally induced radial pipe extension on the axial friction resistance

Within the design process of district heating networks, the maximum friction forces between the pipeline and the surrounding soil are calculated from the radial stress state and the coefficient of contact friction. For the estimation of the radial stresses, the soil unit weight, geometric properties such as the pipe's diameter and the depth of embedment, as well as the groundwater level are taken into account. For the coefficient of contact friction, different values are proposed, dependent on the thermal loading condition of the pipeline. Although this is an assumption of practical use, physically the coefficient of friction is a material constant.To revise the interaction behavior of the soil-pipeline system with respect to thermally induced radial pipe extension, a two-dimensional finite element model has been developed. Here, the frictional contact was established using Coulomb's friction law. For the embedment, sand at different states of relative density was considered. This noncohesive, granular material was described by the constitutive model HSsmall, which is able to predict the complex non-linear soil behavior in a realistic manner by stress-dependency of stiffness as well as isotropic frictional and volumetric hardening. In addition to the basic Hardening Soil model, the HSsmall model accounts for an increased stiffness in small strain regions, which is crucial for the presented investigation.After a model validation, a parametric study was carried out wherein a radial pipe displacement was applied due to thermal changes of the transported medium. Different combinations of geometry and soil property were studied. We conclude by presenting a corrective term that enables for an incorporation of thermal expansion effects into the prediction of the maximum friction force.

Initiation and growth of salt diapirs in tectonically stable settings: Upbuilding and megaflaps

We use finite element modeling to show that upbuilding can be a significant component of salt diapir growth in tectonically stable systems when basin sediments are elastoplastic mudrocks. The ability of such sediments to deform plastically and the dependence of their strength on confining pressure enable structural thinning, which allows salt to pierce through a relatively thick roof. Once pierced, the originally continuous roof uplifts to form a megaflap. We show that the evolution to an upturned megaflap adjacent to a salt stock causes shortening of the bedding layers in the radial and vertical directions and extension in the hoop (circumferential) direction. These deformations lead to significant shear strains within the sediments; as a result, in some areas within the upturned megaflap, mudrocks have reached their maximum level of shear resistance and are failing. Thinning and shear failure of sediments are also significant near salt walls, despite the absence of out-of-plane deformation. We illustrate that cross-sectional area and bedding line lengths are not necessarily preserved. Based on our results, we re-evaluate traditional assumptions of kinematic restoration and show that established workflows may not properly restore salt systems that interact with shallow plastic sediments. Finally, we show that when wall rocks are deformable, salt diapir shapes are not necessarily a simple function of sedimentation and salt flux rates (qfx/A) and that the diapir hourglass shape might result from lateral deformation of the megaflap.

Disentangling Time-series Spectra with Gaussian Processes: Applications to Radial Velocity Analysis

Abstract Measurements of radial velocity variations from the spectroscopic monitoring of stars and their companions are essential for a broad swath of astrophysics; these measurements provide access to the fundamental physical properties that dictate all phases of stellar evolution and facilitate the quantitative study of planetary systems. The conversion of those measurements into both constraints on the orbital architecture and individual component spectra can be a serious challenge, however, especially for extreme flux ratio systems and observations with relatively low sensitivity. Gaussian processes define sampling distributions of flexible, continuous functions that are well-motivated for modeling stellar spectra, enabling proficient searches for companion lines in time-series spectra. We introduce a new technique for spectral disentangling, where the posterior distributions of the orbital parameters and intrinsic, rest-frame stellar spectra are explored simultaneously without needing to invoke cross-correlation templates. To demonstrate its potential, this technique is deployed on red-optical time-series spectra of the mid-M-dwarf binary LP661-13. We report orbital parameters with improved precision compared to traditional radial velocity analysis and successfully reconstruct the primary and secondary spectra. We discuss potential applications for other stellar and exoplanet radial velocity techniques and extensions to time-variable spectra. The code used in this analysis is freely available as an open-source Python package.

Quantifying bamboo coral growth rate nonlinearity with the radiocarbon bomb spike: A new model for paleoceanographic chronology development

Bamboo corals, long-lived cold water gorgonin octocorals, offer unique paleoceanographic archives of the intermediate ocean. These Isididae corals are characterized by alternating gorgonin nodes and high Mg-calcite internodes, which synchronously extend radially. Bamboo coral calcite internodes have been utilized to obtain geochemical proxy data, however, growth rate uncertainty has made it difficult to construct precise chronologies for these corals. Previous studies have relied upon a single tie point from records of the anthropogenic Δ14C bomb spike preserved in the gorgonin nodes of live-collected corals to calculate a mean radial extension rate for the outer ~50 years of skeletal growth. Bamboo coral chronologies are typically constructed by applying this mean extension rate to the entire coral record, assuming constant radial extension with coral age. In this study, we aim to test this underlying assumption by analyzing the organic nodes of six California margin bamboo corals at high enough resolution (<0.5mm) to identify the Δ14C bomb spike, including two tie points at 1957 and 1970, plus the coral collection date (2007.5) for four samples. Radial extension rates between tie points ranged from 10 to 204µm/year, with a decrease in growth rate evident between the 1957–1970 and 1970–2007.5 periods for all four corals. A negative correlation between growth rate and coral radius (r =−0.7; p=0.04) was determined for multiple bamboo coral taxa and individuals from the California margin, demonstrating a decline in radial extension rate with specimen age and size. To provide a mechanistic basis for these observations, a simple mathematical model was developed based on the assumption of a constant increase in circular cross sectional area with time to quantify this decline in radial extension rate with coral size between chronological tie points. Applying the area-based model to our Δ14C bomb spike time series from individual corals improves chronology accuracy for all live-collected corals with complete Δ14C bomb spikes. Hence, this study provides paleoceanographers utilizing bamboo corals with a method for reducing age model uncertainty within the anthropogenic bomb spike era (~1957-present). Chronological uncertainty is larger for the earliest portion of coral growth, particularly for skeleton precipitated prior to bomb spike tie points, meaning age estimations for samples living before 1957 remain uncertain. Combining this technique with additional chronological markers could improve age models for an entire bamboo coral. Finally, the relative consistency in growth rate in similarly-aged corals of the same depth and location supports the hypothesis that skeletal growth may be limited by local environmental conditions.

The evolution history of the extended solar neighbourhood

AbstractOur detailed analytic local disc model (JJ-model) quantifies the interrelation between kinematic properties (e.g. velocity dispersions and asymmetric drift), spatial parameters (scale-lengths and vertical density profiles), and properties of stellar sub-populations (age and abundance distributions). We discuss a radial extension of the disc evolution model representing an inside-out growth of the thin disc with constant thickness. Based on metallicity distributions of APOGEE red clump stars we derive the AMR as function of galactrocentric distance and show that mono-abundance as well as mono-age populations are flaring. The predictions of the JJ-model are consistent with the TGAS-RAVE data, which provide a significant improvement of the kinematic data and unbiased distances for more than 250,000 stars.

D7-brane dynamics and thermalization in the Kuperstein–Sonnenschein model

We study the temperature of rotating probe D7-branes, dual to the temperature of flavored quarks, in the Kuperstein–Sonnenschein holographic model including the effects of spontaneous breakdown of the conformal and chiral flavor symmetry. The model embeds probe D7-branes into the Klebanov–Witten gravity dual of conformal gauge theory, with the embedding parameter, given by the minimal radial extension of the probe, setting the IR scale of conformal and chiral flavor symmetry breakdown. We show that when the minimal extension is positive definite and additional spin is turned on, the induced world volume metrics on the probe admit thermal horizons and Hawking temperatures despite the absence of black holes in the bulk. We find the scale and behavior of the temperature in flavored quarks are controlled dramatically by the IR scale of symmetry breaking, and by the strength and sort of external fields. We also derive the energy-stress tensor of the rotating probe and study its backreaction and energy dissipation. We show that at the IR scale the backreaction is nonnegligible and find the energy can flow from the probe to the bulk, dual to the energy dissipation from the flavor sector into the gauge theory.

Flow field inside a leading edge cooling channel with turbulence promoters in rotating conditions

The present work deepens the analysis of the flow field inside a triangular equilateral channel with turbulence promoters, perpendicular to the radial direction, on both leading and trailing sides, under rotation and both isothermal and nonisothermal conditions (i.e. with centrifugal buoyancy forces). Simulations have been performed at constant Re = 10,000, Ro = 0–0.2–0.6, and Bo = 0–0.08–0.7, the latter corresponding to 80℃ temperature difference between fluid and walls. These conditions match those of the particle image velocimetry measurements, used for comparison against predictions. After proper validation, the numerical modeling helped with the assessment of the flow field evolution along the radial extension of the cooling channel. It has been possible to determine the path of the coolant throughout the channel and localize where the heat transfer would have been enhanced/decreased by secondary flow structures, with respect to the stationary case. Furthermore, a rather Bo-independency of the flow field in this kind of geometry has been confirmed. The analysis presented in this paper finds support from the thermal data available from the open literature, which is rich of thermal analysis indeed, but lacks a detailed description of internal flow fields.

Evolutionary Optimization of Centrifugal Nozzles for Organic Vapours

This paper discusses the shape-optimization of non-conventional centrifugal turbine nozzles for Organic Rankine Cycle applications. The optimal aerodynamic design is supported by the use of a non-intrusive, gradient-free technique specifically developed for shape optimization of turbomachinery profiles. The method is constructed as a combination of a geometrical parametrization technique based on B-Splines, a high-fidelity and experimentally validated Computational Fluid Dynamic solver, and a surrogate-based evolutionary algorithm. The non-ideal gas behaviour featuring the flow of organic fluids in the cascades of interest is introduced via a look-up-table approach, which is rigorously applied throughout the whole optimization process. Two transonic centrifugal nozzles are considered, featuring very different loading and radial extension. The use of a systematic and automatic design method to such a non-conventional configuration highlights the character of centrifugal cascades; the blades require a specific and non-trivial definition of the shape, especially in the rear part, to avoid the onset of shock waves. It is shown that the optimization acts in similar way for the two cascades, identifying an optimal curvature of the blade that both provides a relevant increase of cascade performance and a reduction of downstream gradients.

Electrogoniometer measurement and directional analysis of wrist angles and movements during the Sollerman hand function test

Study DesignClinical measurement. IntroductionTo investigate the characteristics of wrist motion (area, axis, and location) during activities of daily living (ADL) using electrogoniometry. MethodsA sample of 83 normal volunteers performed the Sollerman hand function test (SHFT) with a flexible biaxial electrogoniometer applied to their wrists. This technique is accurate and reliable and has been used before for assessment of wrist circumduction in normal volunteers. A software package was used to overlay an ellipse of best fit around the 2-dimensional trace of the electrogoniometer mathematically computing the area, location, and axis angle of the ellipse. ResultsMost ADL could be completed within 20% of the total area of circumduction (3686°° ± 1575°°) of a normal wrist. An oblique plane in radial extension and ulnar flexion (dart-throwing motion plane) was used for rotation (−14° ± 32°) and power grip tasks (−29° ± 25°) during ADL; however, precision tasks (4° ± 28°), like writing, were performed more often in the flexion extension plane. In the dominant hand, only 2 power tasks were located in flexion region (cutting play dough [ulnar] and pouring carton [radial]), precision tasks were located centrally, and rotation and other power tasks were located in extension region. DiscussionThis study has identified that wrist motion during the ADL requires varying degrees of movement in oblique planes. Using electrogoniometry, we could visualize the area, location, and plane of motion during ADL. This could assist future researchers to compare procedures leading to loss of motion in specific quadrants of wrist motion and its impact on patient's ability in performing particular ADL. It could guide hand therapists to specifically focus on retraining the ADL that may be affected when wrist range of motion is lost after injury. Level of EvidenceDiagnostic level III.

Tube inflation of viscoelastic fluids at a constant growth rate

ABSTRACTThe simultaneous radial inflation and axisymmetric extension of an incompressible viscoelastic tube is modeled analytically as an idealization of the blow-molding process. The working fluid is assumed to obey a single integral constitutive model with a power-law damping function, accommodating behavior ranging from extreme strain hardening (akin to the Lodge–Maxwell model) to strain thinning leading to plastic flow. The tube is sufficiently long so that end effects can be neglected. The axial and radial extension rates at the outer tube radius are assumed to be constant in time. Exact analytical expressions are derived for the tube thickness H, the pressure difference ΔP across the tube wall, and the axial force F required for sustaining the tube inflation with constant stretch history. Their evolution is studied over a variety of deformation intensities, operating conditions, and flow geometries. A valuable insight in the effects of rheology on the blow-molding process is gained.

An updated three-zone heat transfer model for slug flow boiling in microchannels

This work proposes a novel physics-based model for the fluid mechanics and heat transfer associated with slug flow boiling in horizontal circular microchannels to update the widely used three-zone model of Thome et al. (2004). The heat transfer model has a convective boiling nature and predicts the time-dependent variation of the local heat transfer coefficient during the cyclic passage of a liquid slug, an evaporating elongated bubble and a vapor plug. The capillary flow theory, extended to incorporate evaporation effects, is applied to estimate the bubble velocity along the channel. A liquid film thickness prediction method also considering bubble proximity effects, which may limit the radial extension of the film, is included. The minimum liquid film thickness at dryout is set to the channel wall roughness. Theoretical heat transfer models accounting for the thermal inertia of the liquid film and for the recirculating flow within the liquid slug are utilized. The heat transfer model is compared to experimental data taken from three independent studies. The 833 slug flow boiling data points cover the fluids R134a, R245fa and R236fa, and channel diameters below 1 mm. The proposed evaporation model predicts more than 80% of the database to within ±30%. It demonstrates a stronger contribution to heat transfer by the liquid slugs and correspondingly less by the thin film evaporation process compared to the original three-zone model. This model represents a new step towards a complete physics-based modelling of the bubble dynamics and heat transfer within microchannels under evaporating flow conditions.

Stress variability in the Parnaíba Basin, Brazil, during Cretaceous rifting

The Cretaceous section of the Parnaíba Basin, designated as Grajaú Basin, represents an intracontinental half-graben formed during the Early Cretaceous due to the separation between the South American and African continents during the final dispersal of Western Gondwana. Here, through a synergetic approach between fluid inclusion planes (FIPs), outcropping geologic structures, borehole breakouts and remote sensing data, we elucidate in different scales the main structural features and their kinematic indicators. Normal faults strike mainly NNE–SSW and WNW–ESE, while deformation bands and extension joints trend to NW–SE and NE–SW, and FIPs to NE–SW and WNW–ESE. In addition, normal fault-generated scarps border geomorphological units and constitute dense zones of deformation bands and fluidization. Microthermometric FIP analyses suggest this fracturing event occurred at shallow basin levels, at temperatures below 50°C. Furthermore, joints, bands and FIPs present mutually cross-cutting relationships, thus indicating contemporaneity. The numerical inversions applied to striated faults, non-striated faults, joints, deformation bands and FIPs suggest the occurrence of an extensional event characterized by variable direction of extension (σ3) trending from NW–SE to WNW–ESE or NE–SE to NNE-SSW. This event probably started in the Albian during the final Gondwana fragmentation stages. The quasi-perpendicular σ3 trend could be caused by one or all of the following phenomena: a) stress ratio R values obtained (<0.4) indicate the possibility of radial extension (σ2≈σ3), perhaps in response to the deformation partitioning due to kinematic simple-shearing constraints along the Equatorial Atlantic transform margin; b) along the WNW-oriented release normal faults, the local extension (NNE–SSW) switch positions in relation to the regional extension (WNW–ESE) by rotating 90°; c) influence of the pre-existing structures on the regional stress field. Thus, the spatial and temporal relationships between Cretaceous fault activity, stress field and the development of the geomorphological features in the Grajaú Basin contribute to understanding of the Brazilian Equatorial margin geodynamics.

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies.

Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90-3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a maximum in the 150-200 keV energy range; as for LET, it peaks at 90 keV. We also show that fragmentation starts to be significant for proton fluences greater than 1 × 1011 cm-2 at the Bragg-peak energies. Finally, we determine the average proton track radial extension, rmax, corresponding to an occupation probability of 100% DSB in the Bragg-peak region. The rmax values determined are in excellent agreement with the radial extensions of proton tracks determined by simulation approaches in water. When plotted as a function of LET, both SSB and DSB cross sections bend back at high LETs.

&amp;lt;i&amp;gt;In vitro&amp;lt;/i&amp;gt; Evaluation of Growth Inhibition of Some Common Soil Fungi by Selective and Non-selective Herbicides

The indiscriminate and excessive use of herbicides being witnessed in recent times portends possible danger to environmental and human health. To gage the likely impacts of herbicides onfungal ecosystem services, the influence of three narrow [selective (atrazine, butachlor and 2,4-D)] and two broad [non-selective (glyphosate and paraquat)] spectrum herbicides at various concentrations of 0, 0.01, 0.1, 0.5 and 1% v/v on the radial mycelial extension growth, mycelial extension growth rate, percentage mycelial growth inhibition and minimum sporulation time of four common soil fungi, Aspergillus niger, A. flavus, Trichoderma viride and Penicillium sp. were investigated on PDA plates for a period of 96 h at 30 ± 2°C (room temperature). The radial mycelial extension growth of fungi decreased with increased concentrations of the herbicides except for T. viride where atrazine did not show any significant difference among all the concentrations tested (P≤0.05). The fastest mycelia extension growth rate for all fungi was recorded in Atrazine at the highest concentration tested, with T. viride being the fastest at 0.44 mm h-1. At 1% v/v, save for atrazine, all the herbicides inhibited at least 66% mycelial growth with 2,4-D showing a 100% inhibition. The minimum sporulation time for all fungi in the presence of the herbicides was 48 h. There was no sporulation in A. flavus and T. viride in presence of paraquat and 2,4-D above 0.1% v/v concentration within the 96 h of investigation. The results of this study suggest that indiscriminate and excessive use of herbicides could negatively affect ecosystem function.

A Review on the Biomechanical Effects of Fatigue on the Porcine Bioprosthetic Heart Valve.

Characterization of the mechanisms of degeneration of porcine bioprosthetic heart valves (BHV) during long-term cyclic loading is required for predicting and ultimately preventing their failure. Isolation of purely mechanical effects from host biological ones is a necessary first step in understanding the fatigue process as a whole. Thus, in this review we focus on mechanical factors alone as a means of isolating their role in altering biomechanical properties and ultimately their contribution to the fatigue damage process. Mechanical evaluations included tension controlled biaxial, 3-point flexural, and uniaxial failure tests performed on cuspal tissue following 0, 50, 100, 200, and 300 × 106 in vitro accelerated test cycles. Overall, biaxial mechanical results indicate a decreasing radial extensibility that can be explained by stiffening of the effective collagen fiber network as well as a small decrease in the splay of the collagen fibers. Moreover, these results suggest that the loss in flexural rigidity with fatigue that we have previously measured (ASAIO 1999; 45:59-63) may not be because of loss of collagen stiffness alone, but also to fiber debonding and degradation of the amorphous extracellular matrix. We discuss the implications of these results that point toward the development of chemical-treatment methods that seek to maintain the integrity of the amorphous extracellular matrix to ultimately extend BHV long-term durability.

Learning curve of femtosecond laser-assisted cataract surgery: Experience of surgeons new to femtosecond laser platform.

Purpose:The purpose of this study is to assess the learning curve in the initial 100 cases of cataract surgery performed using femtosecond laser-assisted cataract surgery (FLACS) by experienced cataract surgeons without prior experience in femtosecond laser platform.Methods:This study was conducted at tertiary care eye hospital, South India. This was a prospective interventional study. The first 100 consecutive eyes undergoing FLACS were studied to understand docking time, number of docking attempts, problems encountered during docking, and complications attributable to docking. Phacoemulsification performed after femtosecond laser was also studied for complications, need for additional instrumentation, and total time required for surgery. Comparison was also made between two operating surgeons.Results:Successful docking was recorded in 70% eyes at the first attempt. Mean time taken for successful docking was 9.3 ± 6.4 min (median = 6 min, interquartile range (IQR) = 5–10 min, range = 4–35 min). When surgeries were divided into quartiles, docking time reduced significantly from 16.2 ± 7.9 min in the first quartile to 6.2 ± 2.7 min in the fourth quartile (P < 0.001). Phacoemulsification postdocking required 12.9 ± 6.2 min (median = 10 min, IQR = 9–17.5 min). Six eyes showed anterior capsular tags, one had radial extension of capsulorhexis, and two eyes showed pupillary miosis after femtosecond laser application. At 6 weeks, 79% eyes attained uncorrected vision of 20/20, and all eyes had best-corrected vision of 20/20.Conclusion:Approximately 25–30 cases were required before obtaining reproducible results with FLACS, irrespective of cataract surgical experience, suggesting that training programs must offer a minimum 25 surgeries. Very few complications occurred during the learning curve, making it patient friendly.

Comparison of muscle activity of wrist extensors and kinematics of wrist joint during wrist extension in automobile assembly line workers with and without lateral epicondylitis.

Overuse of the extensor carpi radialis (ECR) may play a role in the development of lateral epicondylitis (LE). However, no studies have investigated the muscle activity ratio between the ECR and extensor carpi ulnaris (ECU) associated with the kinematics during wrist extension in workers with LE. We compared the ratio (ECR/ECU) of muscle activity between the ECR and ECU and the kinematics of the wrist during wrist extension between workers with and without LE. Fifteen automobile assembly line workers with LE and 15 workers without LE participated in this study. The ratio of muscle activity was measured using surface electromyography, and wrist kinematics were measured by a three-dimensional motion analysis system while the workers extended their wrists actively to the maximum range to which they did not feel uncomfortable. Significantly greater ratios of muscle activity, ranges of radial deviation, and combined motion of radial deviation and extension (CMDE) were shown in workers with LE compared to those without LE. Also, the range of wrist extension was significantly lower in workers with LE than in those without LE. Quantifying the ratio of muscle activity with altered kinematics of wrist extension may help researchers to understand why overuse of ECR is occurring and explain LE development in automobile assembly line workers.

Intact-decay transitions in profiles of density-calibratable resistance drilling devices using long thin needles

In 1986, two German universities started developing resistance drilling for tree-ring analysis in a joint physics–botany project. In order to differentiate between early wood and late wood zones of tree-rings, the system had to provide a minimum spatial (>10 points per mm) and signal (>10 Bit) resolution combined with a high (preferably linear) correlation to wood density (r² > 0.8). The same conditions have to be fulfilled when decay in trees and timber should be identified reliably because the stages of decomposition by fungal decay are largely characterised and differentiated by the corresponding loss in density. Experiences from thousands of drillings in trees since 1986 suggest that the profile trend in the transition zone from intact to decayed wood seems to indicate the speed of radial extension of the decomposition. For a few of the various types of resistance drills used on the market, a sufficient resolution and precision in combination with a high correlation to wood density was already shown. Consequently, these device types deliver correspondingly reliable profiles enabling experts to estimate trends in future radial increments as well as in radial spread of decay.

Nerve Guidance by a Decellularized Fibroblast Extracellular Matrix

Spinal cord and peripheral nerve injuries require the regeneration of nerve fibers across the lesion site for successful recovery. Providing guidance cues and soluble factors to promote neurite outgrowth and cell survival can enhance repair. The extracellular matrix (ECM) plays a key role in tissue repair by controlling cell adhesion, motility, and growth. In this study, we explored the ability of a mesenchymal ECM to support neurite outgrowth from neurons in the superior cervical ganglia (SCG). Length and morphology of neurites extended on a decellularized fibroblast ECM were compared to those on substrates coated with laminin, a major ECM protein in neural tissue, or fibronectin, the main component of a mesenchymal ECM. Average radial neurite extension was equivalent on laminin and on the decellularized ECM, but contrasted with the shorter, curved neurites observed on the fibronectin substrate. Differences between neurites on fibronectin and on other substrates were confirmed by fast Fourier transform analyses. To control the direction of neurite outgrowth, we developed an ECM with linearly aligned fibril organization by orienting the fibroblasts that deposit the matrix on a polymeric surface micropatterned with a striped chemical interface. Neurites projected from SCGs appeared to reorient in the direction of the pattern. These results highlight the ability of a mesenchymal ECM to enhance neurite extension and to control the directional outgrowth of neurites. This micropatterned decellularized ECM architecture has potential as a regenerative microenvironment for nerve repair.