Semicircular Regions Research Articles

T1rho MR properties of human patellar cartilage: correlation with indentation stiffness and biochemical contents.

Cartilage degeneration involves structural, compositional, and biomechanical alterations that may be detected non-invasively using quantitative MRI. The goal of this study was to determine if topographical variation in T1rho values correlates with indentation stiffness and biochemical contents of human patellar cartilage. Cadaveric patellae from unilateral knees of 5 donors with moderate degeneration were imaged at 3-Telsa with spiral chopped magnetization preparation T1rho sequence. Indentation testing was performed, followed by biochemical analyses to determine water and sulfated glycosaminoglycan contents. T1rho values were compared to indentation stiffness, using semi-circular regions of interest (ROIs) of varying sizes at each indentation site. ROIs matching the resected tissues were analyzed, and univariate and multivariate regression analyses were performed to compare T1rho values to biochemical contents. Grossly, superficial degenerative change of the cartilage (i.e., roughened texture and erosion) corresponded with regions of high T1rho values. High T1rho values correlated with low indentation stiffness, and the strength of correlation varied slightly with the ROI size. Spatial variations in T1rho values correlated positively with that of the water content (R2 = 0.10, p < 0.05) and negatively with the variations in the GAG content (R2 = 0.13, p < 0.01). Multivariate correlation (R2 = 0.23, p < 0.01) was stronger than either of the univariate correlations. These results demonstrate the sensitivity of T1rho values to spatially varying function and composition of cartilage and that the strength of correlation depends on the method of data analysis and consideration of multiple variables.

Exudate identification in retinal fundus images using precise textural verifications

One of the most salient diseases of retina is Diabetic Retinopathy (DR) which may lead to irreparable damages to eye vision in the advanced phases. A large number of the people infected with diabetes experience DR. The early identification of DR signs facilitates the treatment process and prevents from blindness. Hard Exudates (HE) are bright lesions appeared in retinal fundus images of DR patients. Thus, the detection of HEs is an important task preventing the progress of DR. However, the detection of HEs is a challenging process due to their different appearance features. In this paper, an automatic method for the identification of HEs with various sizes and shapes is proposed. The method works based on a pixel-wise approach. It considers several semi-circular regions around each pixel. For each semi-circular region, the intensity changes around several directions and non-necessarily equal radiuses are computed. All pixels for which several semi-circular regions include considerable intensity changes are considered as the pixels located in HEs. In order to reduce false positives, an optic disc localization method is proposed in the post-processing phase. The performance of the proposed method has been evaluated on DIARETDB0 and DIARETDB1 datasets. The experimental results confirm the improved performance of the suggested method in term of accuracy.

Electrochemical impedance spectroscopy analysis of plasma-treated, spray-coated single-walled carbon-nanotube film electrodes for chemical and electrochemical devices

In this study, carbon-nanotube (CNT) surfaces were treated with oxygen plasma, and the improvement in surface inertness was analyzed using electrochemical impedance spectroscopy (EIS). Among nanomaterials, CNTs are the most attractive owing to their outstanding properties. However, the chemical inertness of CNT surfaces hinders the widespread implementation of CNTs in bioanalytical applications. Therefore, we present in detail the electrochemical properties of CNTs treated in various plasma conditions. The single-walled carbon nanotube (SWCNT) films were spray-coated onto working electrodes with a three-electrode configuration fabricated on a glass substrate and activated at various plasma conditions. The EIS spectra of the SWCNT film revealed typical porous structure characteristics. As the thickness of the SWCNT film increased by spray coating, the charge-transfer resistance sharply increased owing to the reduction of the effective electrode area caused by the decreased roughness and porosity of the SWCNT film. The Nyquist plots of the plasma-treated SWCNT electrodes featured two semicircular regions at high and intermediate frequencies, as well as one straight line at low frequencies. The plasma-treated SWCNT electrode had a less distinct separation of the second arc and straight line than the untreated SWCNT electrode because the time constant was lowered owing to the diffusion process generated where the charge-transfer reaction occurred. We analyzed the change in the electrodes through EIS, which can identify individual contributions to the total impedance of an electrochemical system.

Heat transfer characteristics of jet impingement onto the concave surface of a cone

ABSTRACT Heat transfer coefficient measurements for jet impingement onto the concave surface of a cone with apex angles equal to 30° and 70° are reported in this study. Static pressure measurements along the cone surface are also reported which aid in explaining the results from the heat transfer measurements. The conical geometry finds application for the heating of aircraft gas turbine engine nose bullet region which could experience ice formation whenever aircraft operates at higher altitudes. The concave surface of the cone is heated by impinging hot air tapped from the compressor. The heat transfer coefficients, which are significantly different compared to flat surface impingement, and are scarcely available, are reported in this study. The influence of the jet axis coincident with the cone axis and impinging into apex region was studied first. The methodology where a thin stainless-steel foil is heated with a known heat flux by passing electric current through it and then measuring the detailed surface temperature using an infrared thermal camera, was used to compute the wall Nusselt distribution. The Nusselt number variation is presented as a function of nondimensional apex to nozzle spacing (L/D) and the nondimensional axis displacement (O/D). Three different diameter (D equal to 10 mm,14 mm and 20 mm) pipes were used for the concentric impingement case and the Nusselt number distribution was observed not depend on the injection diameter. The jet Reynolds number was varied between 25000 and 82000. The peak Nusselt number values are similar to those for flat plate impingement and do not occur at the cone apex, but at a nondimensional distance between 3.2 and 3.9 for 4.25 < L/D < 10.25 for the 30° cone. The peak Nusselt number values increase by almost 30% with decrease in the L/D from 10.2 to 3.0. Wall static pressure measurements indicated that the peak Nusselt number values occur in regions where the interaction between the incoming and outgoing streams is strongest – these regions occur at distances downstream from the stagnation region toward cone exit. The peak heat transfer coefficient location could not be obtained for the 70° cone, but the measured maximum values are higher by 30–50% compared to those for the 30° case. The jet is able to penetrate further toward the apex of the cone for 70° cone compared to 30° cone shifting the peak heat transfer locations closer to the apex for larger apex angle case. There is insignificant influence of jet diameter on Nusselt number variation for the three diameter values investigated in this study. The influence of displacing the jet axis by a distance equal to half the jet diameter in a direction perpendicular to the cone axis was also studied but detailed measurements were possible only for the 30° cone. Two semi-circular regions, one close to the impingement tube and the other away from the tube, displaying similar heat transfer coefficient behavior were observed. A peak in the Nusselt number occurs in each semi-circular region and the magnitude of the peaks are nearly same and they lie on either side of the peak location observed for the concentric impingement case when the flow geometric parameters are similar for the two cases. The measurements for the 70° cone exhibited all features of the 30° cone but the maximum values were higher by nearly 40% for this case.

Local Enhancement of Dopant Diffusion from Polycrystalline Silicon Passivating Contacts.

Passivating contacts consisting of heavily doped polycrystalline silicon (poly-Si) and ultrathin interfacial silicon oxide (SiOx) films enable the fabrication of high-efficiency Si solar cells. The electrical properties and working mechanism of such poly-Si passivating contacts depend on the distribution of dopants at their interface with the underlying Si substrate of solar cells. Therefore, this distribution, particularly in the vicinity of pinholes in the SiOx film, is investigated in this work. Technology computer-aided design (TCAD) simulations were performed to study the diffusion of dopants, both phosphorus (P) and boron (B), from the poly-Si film into the Si substrate during the annealing process typically applied to poly-Si passivating contacts. The simulated 2D doping profiles indicate enhanced diffusion under pinholes, yielding deeper semicircular regions of increased doping compared to regions far removed from the pinholes. Such regions with locally enhanced doping were also experimentally demonstrated using high-resolution (5-10 nm/pixel) scanning spreading resistance microscopy (SSRM) for the first time. The SSRM measurements were performed on a variety of poly-Si passivating contacts, fabricated using different approaches by multiple research institutes, and the regions of doping enhancement were detected on samples where the presence of pinholes had been reported in the related literature. These findings can contribute to a better understanding, more accurate modeling, and optimization of poly-Si passivating contacts, which are increasingly being introduced in the mass production of Si solar cells.

Influence of Fiber Orientation on Deformation of Additive Manufactured Composites

Anisotropy caused by flow-induced fiber orientation of discontinuous fibers within the extrudate in the Extrusion Deposition Additive Manufacturing (EDAM) process gives rise to anisotropic shrinkage in printed parts and thereby, final part deformations. Three fiber orientation states, described by the second-order orientation tensor, were investigated to determine their influence upon final geometry. Two material systems were investigated including a short glass fiber-reinforced polyamide and a short carbon fiber-reinforced polyamide. A curvilinear geometry was modeled and printed virtually in the thermo-mechanical simulation, ADDITIVE3D©. The scale of the printed geometry was in the range of 300–400 mm and contained three semicircular geometry regions connected to linear regions, thereby inducing significant magnification of the spring-in deformation. The predicted deformation of the printed geometry for the three fiber orientation states and two material systems were compared. The deformation predicted for glass fiber-filled polyamide and carbon fiber-filled polyamide of the same fiber orientation states showed comparable deformations. The largest residual deformation was shown to correspond to the orientation tensor with the greatest degree of anisotropy.

An ultrastructural focus on the buccal cavity of the grey gurnard Eutrigla gurnardus (Linnaeus, 1758): Adaptative dietary implications.

The current investigation represented the first anatomical description of the buccal cavity of the grey gurnard Eutrigla gurnardus. For the achievement of this study, 10 heads of mature fish were used for SEM examinations. The morphological characteristic appearance of the buccal cavity has shown several adaptations in relation concerning its feeding habits. The median fissure of the upper lip divided the upper lip into two halves, this fissure appeared to be formed from many micro-tubercles with numerous taste buds which aid in holding mucus secretion to the cell surface, help in mucus spread, and provide mechanical protection to the epithelium. Velum had two regions: median and peripheral region. The epithelium covering of the median region of the upper velum had dots-like epithelial protrusion that carrying numerous taste buds, meanwhile, the epithelium covering of the lower velum not carried taste buds but instead carried numerous small scales-like structures. The palate is divided into two semicircular regions by small region of microridges into the anterior and posterior region. The slightly bifid tongue had a median tubercle with numerous small taste buds on its dorsal surface. Concluded, these data were necessary to understand the adaptation of fish to its habitat and in developing a new and better method for fishing of this type of fish.

EWOD-aided droplet transport on texture ratchets

We report a digital microfluidic device to transport aqueous droplets on an open surface in air using electrowetting-on-dielectric (EWOD) with anisotropic ratchet conveyors (ARCs). ARCs are micro-sized periodic semicircular hydrophilic regions on a hydrophobic background, providing anisotropic wettability. SiNx and Cytop are used as the dielectric layer between the water droplet and working electrodes. By adopting parylene as a stencil mask, hydrophilic patterning on the hydrophobic Cytop thin film layer is achieved without the loss of Cytop hydrophobicity. While the traditional EWOD platform requires the control of multiple electrodes to transport the droplet, our system utilizes only two controlling electrodes. We demonstrate that 15 μl water droplets are transported at a speed of 13 mm/s under 60 Vpeak sinusoid AC signal at 50 Hz. Droplet transport at 20 Hz is also presented, demonstrating that the system can operate within a range of frequencies.

Energy harvesting of beam vibration based on piezoelectric stacks

Piezoelectric stacks demonstrate excellent properties for energy harvesting owing to the high energy conversion efficiency and long lifetime. However, force amplification frames are commonly required to amplify the load applied to piezoelectric stacks. This paper proposes an energy harvester based on piezoelectric stacks without force amplification frames. The piezoelectric stacks are composed of annular piezoelectric sheets separated into several conductive sectors on the surface and mounted on a beam through a threaded sleeve and a nut. Experiments and simulations are carried out to evaluate the output performance of the energy harvester when the beam vibrates in transverse direction. The effects of excitation frequency, sector number, preload level, mounting position and piezoelectric sheet number on the output voltage are evaluated. Results from experiments and simulations show that the energy harvester gets the highest output gain as the excitation frequency reaches the resonant frequency of beam. When the piezoelectric sheets are divided into two insulated semi-circular regions, the best output performance can be obtained under the same loading conditions. Increasing the preload level is also beneficial for achieving high output voltage. However, this effect gets insignificant when the preload reaches to a certain value. The output gain of the energy harvester increases with the number of piezoelectric sheets. The output voltage is higher when the energy harvester is mounted at the beam center than that mounted at the beam ends.

A compact configuration of semicircular metasurface loaded slot antenna for beam steering application

In this article, a compact beam steering antenna configuration is presented. The proposed structure comprises a semicircular radially gradient metasurface (SCRGM) and a slot antenna. This metasurface (MS) with the dimensions of 3.17λ02 covers only half of the antenna aperture by placing it at a height of 0.16λ0 from the slot antenna. The SCRGM is made up of four different semicircular regions, which introduce progressive phase delay to the impinging spherical electromagnetic waves from the slot antenna. The placement of the SCRGM tilts the main beam by 30° away from the normal direction. Furthermore, in-plane movement (rotation and translation) of the SCRGM facilitates beam steering in the elevation plane (E-plane) with the total scanning range of 60°. Moreover, in simulation, two SCRGMs are placed at both sides of antenna aperture to independently control the beam directions in both upper and lower hemispheres of the slot antenna. Due to the symmetry of the slot antenna, only one SCRGM is tested during the measurement process and the same outcome is expected for the other MS. Considerably small volume (0.50λ03) of the structure revealed compact antenna configuration. Moreover, independent control of the beam directions in both of the hemispheres makes proposed antenna a suitable candidate for various applications.

Simultaneous Impact of Multiple Droplets on Liquid Film

Multiple droplets impinging on a thin liquid film simultaneously is numerically studied using a three-dimensional model with an implement of a random disturbance subjected to Gaussian distribution. This model is very effective to predict droplet splashing under relatively high impingement momentum. Interface evolutions and field distributions are addressed after droplets impact. Besides, a geometric model is built up to demarcate the impact region into two semicircular regions and a series of rectangular regions during simultaneous impact, further to discuss the variations of area and residual film thickness in each region as well as the total area and average film thickness.

Bent-fiber intermodal interference based dual-channel fiber optic refractometer.

We present a novel dual-channel fiber optic interferometer based on intermodal interference from single-mode fiber (SMF) bending. This dual-channel interferometer has simple structure, consisting of two bare fiber semicircular bending regions with different bending radiuses connected by a section of straight fiber. A dual-channel interferometer with bending radiuses of 4 mm and 4.3 mm is fabricated and refractive index (RI) sensing is realized by measuring the wavelength shift of the resonance dips in the transmission spectrum of the dual-channel interferometer. In the RI range of 1.3403 to 1.3726, the corresponding RI sensitivities for these two channels are 207 and 245 nm/RIU (refractive index unit) and the RI resolutions are about 6.57 × 10⁻⁵ RIU and 5.55 × 10⁻⁵ RIU, respectively.

Preparation of hybrid thiol-acrylate emulsion-templated porous polymers by interfacial copolymerization of high internal phase emulsions.

Emulsion-templated highly porous polymers (polyHIPEs), containing distinct regions differing in composition, morphology, and/or properties, are prepared by the simultaneous polymerization of two high internal phase emulsions (HIPEs) contained within the same mould. The HIPEs are placed together in the mould and subjected to thiol-acrylate photopolymerization. The resulting polyHIPE material is found to contain two distinct semicircular regions, reflecting the composition of each HIPE. The original interface between the two emulsions becomes a copolymerized band between 100 and 300 μm wide, which is found to be mechanically robust. The separate polyHIPE layers are distinguished from one another by their differing average void diameter, chemical composition, and extent of contraction upon drying.

Semicircular canal-dependent developmental tuning of translational vestibulo-ocular reflexes in Xenopus laevis.

Gaze stabilization during head/body movements is achieved to a large extent by vestibular-evoked compensatory eye movements. These reflexes derive from semicircular canal and otolith organs and depend on the transformation of the respective sensory signals into extraocular motor commands. To elicit directionally and dynamically appropriate compensatory eye movements, extraocular motoneurons require spatiotemporally specific inputs from semicircular canals and regions of the utricular epithelium with matching directional sensitivity. The ontogenetic establishment and maturation of the directional tuning of otolith inputs in extraocular motoneurons was studied in Xenopus laevis tadpoles. In young larvae at stage 46-48, superior oblique (SO) extraocular motoneurons receive omnidirectional utricular signals during horizontal translational motion, indicating an absence of spatial tuning. In contrast, in older larvae beyond stage 49 these motoneurons were activated by directionally more restricted otolith inputs with an increasingly enhanced spatial tuning until stage 53. This developmental process limited the origin of otolith signals to a utricular epithelial sector with a hair cell sensitivity that is coaligned with the pulling direction of the SO eye muscle. The maturation of the otolith response vector was abolished by enzymatic prevention of semicircular canal formation in postembryonic tadpoles at stage 44, suggesting that functionally intact semicircular canals are causally responsible for the observed directional tuning of utricular responses. A likely mechanism by which semicircular canals might influence the tuning of the otolith responses includes stabilization of coactivated and centrally converging sensory signals from semicircular canal and spatially aligned epithelial utricular regions during natural head/body motion.

Internal Stress-Induced Orthorhombic Phase in 5-Fold-Twinned Noble Metal Nanowires

We use atomistic simulations to show that 5-fold-twinned nanowires of several face-centered cubic metals (Ag, Au, Cu, and Pd) exhibit an overall body-centered orthorhombic phase resulting from the large internal stress associated with their twinned structure. The distribution of atomic stress in the nanowires confirms the existence of a disclination at the 5-fold axis, in addition to an anisotropic distortion of the lattice. We find that two regions of the nanowire are highly stressed: local stress maxima are distributed in the shape of leaflets running along each twin boundary, as well as in semicircular regions near the free surfaces. The large elastic strain energy associated with the distortion may be partially released via the formation and propagation of partial dislocations, which are restricted to a single subunit of the nanowire. Our calculations are in line with experiment and indicate the complex ways in which the structures of these metal nanocrystals can depend on their shape.

Posterior Cutaneous Nerve of the Thigh Relating to the Restoration of the Gluteal Fold

The aim of this study was to elucidate the anatomic relationship between the posterior cutaneous nerve of the thigh (PCNT) and the gluteal fold.A total of 20 amputated thighs from 10 fresh Korean cadavers were used in this study (10 men; age range, 52-76 years). The PCNT was located at an average distance of 13.1 +/- 1.7 cm (medial range, 10.5-16.0 cm) medial to the gluteal fold. The majority of the PCNT travels along the middle 1/3 of the thigh at the level of the gluteal fold (medial 3/10 to 6/10; average, 42.1% +/- 8.7%; range, 23.8%-59.2%). The majority (85%) of the sites of emergence of the perineal branches were located within a rectangular region that covered the medial 1/4 to 1/2 of the thigh on the x axis and the proximal 1/12 to 1/4 of the thigh on the y axis. Most (78%) of the sites of emergence of the inferior cluneal nerve were located within 2 semicircular regions, an upper semicircle and a lower semicircle. The upper semicircle was 3 cm in diameter, and its center was located in the medial 2/5 of the thigh on the x axis. The lower semicircle was 2.5 cm in diameter, and its center was located at the midpoint of the thigh on the x axis. The majority (90%) of the main branches of the PCNT were located within a rectangular region, the base of which extended from the medial 1/3 to 2/3 of the thigh on the x axis and the height of which was in the proximal 1/10 to 2/5 of the thigh on the y axis. Our study describes the characterization of the site and reach of the PCNT in the thigh. It is imperative to know the exact location of the PCNT to avoid causing injury to the nerve during buttock lift.

Nonlinear phenomena in hybrid Couette flow composed of planar and circular shear

Results are presented from an experimental investigation of a novel shear flow. Two parallel sections of planar Couette flow are connected by two semicircular sections of circular Couette flow to give a flow domain with the shape of a running track. Driving the flow with a moving inner boundary leads to centrifugal instability in the curved regions as in conventional Taylor–Couette flow. This is in contrast to the planar regions, which are linearly stable and are characterized instead by finite-amplitude instability. In the steady regime, the entire flow field is dominated by structures akin to Taylor vortices. The mechanism of exchange between a four-cell and a six-cell flow over a range of aspect ratio is qualitatively the same as for the standard Taylor–Couette problem. In the unsteady regime, the flow is characterized by various spatiotemporal modes, the selection of which is dependent on the manner of flow evolution. Quasistatic increase of the Reynolds number from zero typically results in flow with a banded spatial structure and low-dimensional dynamics, both of which are associated with instability in the semicircular regions. However, an abrupt step-like increase of Reynolds number produces a persistent flow state with strong spatial disorder and a broadband dynamical spectrum. The results of this study have implications for the conventional distinctions between the properties of open and closed flows, and suggest the possibility of intermediate flows which are worthy of investigation in their own right.

Experimental study of natural convection heat transfer in a semicircular enclosure

An experimental study of natural convection heat transfer in a differentially heated semicircular enclosure was carried out. The flat surface was heated and the radial surface was cooled isothermally. The effects of angle of enclosure inclination on the heat transfer across semicircular regions of several radii were measured for Rayleigh numbers RaR ranging from 6.72 × 106 to 2.33 × 108, using water as the working fluid. The angle of inclination varied from −90 degrees to 90 degrees with radii R of 50, 40, and 30 mm. The flow patterns were sketched from the results of a visualization experiment using aluminum powder. The temperature measurements in the enclosure were carried out using liquid crystals and thermocouples. The results indicate that different flow patterns were encountered as the angle of inclination varied, and the heat transfer rate was largely dependent on the flow pattern. In particular, enhanced heat transfer rates can be obtained when plume-like flow occurs along both hot and cold walls in the case of an upward-facing hot wall. Heat transfer for the inclined enclosure can be predicted using the equation for a vertical enclosure presented in this paper. © 1998 Scripta Technica, Inc. Heat Trans Jpn Res, 26(2): 131–142, 1997

Experimental study of natural convection heat transfer in a semicircular enclosure

An experimental study of natural convection heat transfer in a differentially heated semicircular enclosure was carried out. The flat surface was heated and the radial surface was cooled isothermally. The effects of angle of enclosure inclination on the heat transfer across semicircular regions of several radii were measured for Rayleigh numbers RaR ranging from 6.72 × 106 to 2.33 × 108, using water as the working fluid. The angle of inclination varied from −90 degrees to 90 degrees with radii R of 50, 40, and 30 mm. The flow patterns were sketched from the results of a visualization experiment using aluminum powder. The temperature measurements in the enclosure were carried out using liquid crystals and thermocouples. The results indicate that different flow patterns were encountered as the angle of inclination varied, and the heat transfer rate was largely dependent on the flow pattern. In particular, enhanced heat transfer rates can be obtained when plume-like flow occurs along both hot and cold walls in the case of an upward-facing hot wall. Heat transfer for the inclined enclosure can be predicted using the equation for a vertical enclosure presented in this paper. © 1998 Scripta Technica, Inc. Heat Trans Jpn Res, 26(2): 131–142, 1997

Faradaic Impedance of Polarized Porous Electrodes: II . Nonlinear Kinetics

A previous analysis of the Faradaic impedance of polarized porous gas diffusion electrodes has been extended to include kinetic rate expressions which are other than first order. An approximate analysis reveals impedance characteristics which are qualitatively similar to those for first order kinetics for reaction orders greater than unity and less than 1/2. However for orders between one and 1/2, the Argand diagram exhibits two semicircular regions instead of one, as well as the inductive characteristic at sufficiently high frequency. These curves are compared with the data of Brodd on Leclanché cells which exhibit similar characteristics.