Surface Bulge Research Articles

Microstructural Characterization of Epitaxial Cubic Silicon Carbide Using Transmission Electron Microscopy

Microstructures of switch-back epitaxy cubic silicon carbide (3C-SiC) before and after Al ion implantation were investigated by transmission electron microscopy (TEM). Stacking faults aligned along the {111} were observed in 3C-SiC. A surface bulge was observed in some regions and planar defects were observed under the bulge region. After ion implantation of 3C-SiC, defects were observed to be distributed up to a depth approximately 500 nm from the surface.

Mg/Al complex oxides-A new type of solid basic catalyst for epoxidation

Hydrotalcites known as anionic clays are found in nature. Hydrotalcites, hydrotalcite-like compounds, and calcined hydrotalcites (as mixed or complex oxides) as highly active, selective catalysts play an important role in many base/catalyzed reactions. Mg/Al hydrotalcite (MAH) as precursor was used to prepare Mg/Al metal complex oxides (MAO), used as epoxidation catalysts in the current research. In this paper, some primary physical and catalytic properties of MAH and MAO were investigated. The results indicated that the qualified MAH (Mg/Al mol ratio of 3) can be achieved when the suspension was crystallized under 80°C for 16h, and after being filtered, dried at 100 °C for 5h in a oven. MAO was prepared by calcining MAH for 4h in a muffle furnace, and calcination temperature was determined to be 500 °C by a differential scanning calorimeter (DSC). Crystal structure and parameters of MAH and MAO were characterized by X/ray diffraction (XRD), good crystal structure was observed and typical peaks of MAH were detected when 2θ was at 11.5 (003), 23.0 (006), 35.0 (009), and 61.0 (110), respectively. The morphology of calcined precursor, i.e. MAO, was investigated with scanning electron microscopy (SEM); the finer lamellar structure and smaller average size of 3μm was observed. Molding research was performed and confirmed by SEM, the results indicated that the surface bulge and cavity with size of several micrometers were increased, which simultaneously suggested the increasing of specific surface area. The catalytic activity of molding MAO was finally examined by using octanol as starting reagent and ethylene oxide as reactant, and narrower molecular distribution was observed comparing with the traditional catalyst-KOH.

Microchannel Induced Surface Bulging of a Soft Elastomeric Layer

When a wetting liquid fills in microchannels embedded inside a thin elastomeric layer, the surface of the layer does not remain smooth but bulges out in the vicinity of the channels. The height of the bulge depends on the deformability of the layer and the surface tension of liquid; in addition, it depends also on the vertical location of the channel from the surface of the layer and the channel diameter. While, for liquids of low viscosity ∼500 cP bulging occurs instantaneously, for liquids of high viscosity ∼4000 cP, it occurs over a period of time. Concomitant to bulging of the layer, the cross section of the channel alters too in its shape and size suggesting that the elastic energy penalty associated with the bulging of the layer is supplied by the interfacial energy of the liquid–air and liquid–solid interfaces. Local bulging of the layer alters also its local deformability which is demonstrated by contact mechanics experiments: indentation with a spherical indenter yields a non-circular contact area, the shape and size of which vary with the depth of indentation. Thus, sub-surface microchannels can be suitably used for generating surface patterns on the elastomer and also for modulating its modulus.

Papillary Thyroid Carcinoma With Prominent Hobnail Features: A New Aggressive Variant of Moderately Differentiated Papillary Carcinoma. A Clinicopathologic, Immunohistochemical, and Molecular Study of Eight Cases

Papillary thyroid carcinomas (PTC) are the most common thyroid tumors that usually have a good prognosis. Recurrence, metastases, and cancer death may occur in a few patients and are more commonly associated with more aggressive tumors, such as tall cell, columnar cell, or diffuse sclerosing variants of the PTC. We present the clinicopathologic, immunohistochemical, and molecular features of a rare aggressive variant of the PTC showing prominent hobnail features. The patients included 6 females and 2 males. Ages ranged from 28 to 78 years (mean 57.6). Patients presented with a neck mass and cervical lymphadenopathy. Tumor size ranged from 1.0 cm to 4.0 cm (mean 2.5 cm). The tumors were usually multifocal with variably sized complex papillary structures lined by cells with increased nuclear/cytoplasmatic ratios and apically placed nuclei that produced a surface bulge (hobnail appearance). Thyroglobulin, TTF-1, HBME-1, and p53 were positive in all cases, and there was membrane staining for beta-catenin and E-cadherin. The proliferative index with Ki67 ranged from 2% to 20% with a mean of 10%. BRAF mutation was present in 4/7 (57.1%) cases. Distant metastases to liver, lung, bone, brain, muscle, and pancreas developed in 5 patients. The average follow-up time was 77.2 months. Four patients died of disease after a mean of 42.8 months. Two patients are alive with disease after 4 and 87 months, respectively. Two patients are alive without disease after 120 and 236 months. PTC with a prominent hobnail pattern is a moderately differentiated PTC variant with aggressive clinical behavior and significant mortality.

Resistance Changes in Eutectic Sn-Bi Solder Joints During Electromigration

The resistance of electronic interconnects made with Sn-based solders experiences significant deterioration during service in high-performance electronic products. During electromigration damage, metal atoms/ions can migrate in the direction of electron flow. Accordingly, accumulation of metal atoms/ions at the anode interface can induce surface bulging. On the other hand, depletion of metal atoms/ions at the cathode interface can induce surface dimpling. In addition, the different α-rich and β-rich phases in a binary eutectic system were found to separate in the bulk region of eutectic Sn-Bi solder joints. Such atomic movement leads to complex interactions between the resistance changes of electronic solder joints during the different stages of electromigration. In order to clarify such scenarios, a LabVIEW ® -controlled system was employed to quantitatively measure the instantaneous resistance values after an electric current was applied. This study investigated the effects of a high current density (10 4 A/cm 2 ) at two different ambient temperatures (25°C and 80°C) on the deterioration of resistance changes during the early stage of the electromigration process.

Ice flow across a warm-based/cold-based transition at a glacier margin

AbstractWhere polythermal glaciers have frozen margins that buttress otherwise temperate-based sliding ice, longitudinal compression can strongly influence ice-flow trajectory, and consequently sediment transport paths. Past efforts to model flow in the vicinity of a basal thermal transition (BTT) have generally relied on simplified boundary conditions or rheological idealizations, making these model results difficult to apply to real glacier termini. Herein, we present results of numerical simulations using a power-law rheology and with boundary conditions that better represent the frozen margin. Model results indicate that a transition to a non-sliding frozen margin causes a decline in surface velocity made possible by upward ice flow, implying either enhanced ablation for steady-state simulations or the formation of a surface bulge. Permitting ice loss by ablation combined with numerical smoothing of the basal slip transition subdues basal stress concentrations and thereby inhibits development of structural discontinuities such as thrust faults. Upward ice flow is accommodated by vertical extension up-glacier of the BTT. This strain regime can potentially account for key structural features in polythermal glacier termini without appealing to thrusting.

Serous Cells in the Parotid Glands of Two Species of Tamarins: Polarized Secretory Granules

The parotid glands of two species of tamarins were examined by electron microscopy. Endpiece cells are typical in appearance, with an extensive rough endoplasmic reticulum, prominent Golgi apparatuses, and numerous serous granules. In the saddleback tamarin, the secretory granules contain a dense spherule pressed against the inner aspect of the limiting membrane, leading to a surface bulge. During the course of merocrine secretion (a form of exocytosis), such morphologically polarized granules approach the luminal plasma membranes with the bulge in the vanguard. It is these protuberances that fuse with the plasmalemma. In contrast, although serous granules in the cotton top tamarin contain a spherule, they lack surface bulges and their docking on luminal membranes seems to be a random event with respect to their surface morphology. Moreover, certain other types of cells in a taxonomically wide spectrum of species have granules with a less obvious structural polarity, as well as cells whose granules lack morphological polarity but have a functional polarity that comes into play during exocytosis of such secretory granules.

Perceptual organization reconsidered in the light of the watercolor illusion: The problem of perception of holes and the object-hole effect

The watercolor illusion is a long-range color assimilation (coloration effect) imparting a figure-ground segregation (figural effect) across large enclosed areas (B. Pinna, 1987; B. Pinna, G. Brelstaff, & L. Spillmann, 2001; B. Pinna, L. Spillmann, & J. S. Werner, 2003; B. Pinna, J. S. Werner, & L. Spillmann, 2003). The watercolored figure has a very poorly reversible or univocal figure-ground segregation and strongly enhances the unilateral belongingness of the boundaries (E. Rubin, 1915), a principle stating that the boundaries belong only to the figure and not to the background. The figural effect determines grouping and figure-ground segregation more strongly than the well-known Gestalt principles. Under watercolor conditions both the figure and the background assume new properties becoming respectively bulging object and hole both with a 3-D volumetric appearance (object-hole effect). Our purposes were: (i) to demonstrate that the hole induced by the watercolor illusion has unique figural properties comparable to those of the object and not present in the background induced by the known figure-ground principles; (ii) to demonstrate a dissociation of the object-hole effect from the coloration one; (iii) to demonstrate that the object-hole effect depends on a new principle. This was psychophysically tested by weakening (ungrouping) the whole figural organization of the watercolor illusion, i.e. by imparting motion to only some components of a stimulus, while other components remain stationary. The results showed that (i) subjects perceived moving holes more strongly than moving figures or objects enlarging and shrinking. (ii) Paradoxically, moving holes appear more as figures than the bulging surfaces. (iii) When motion was imparted to components that while stationary were perceived as objects, their figurality is further enhanced (summation effect). (iv) When object-hole and coloration effects were dissociated no significant difference compared to illusory colored conditions was reported. Coloration can be considered independent from the object-hole effect of the watercolor illusion. The object-hole effect may depend on the "asymmetric luminance contrast principle" (B. Pinna, 2005).

In vitro tympanic membrane position identification with a co-axial fiber-optic otoscope

Otitis media diagnosis can be assisted by measuring the shape of the tympanic membrane. We have developed an ear speculum for an otoscope, including spatially distributed source and detector optical fibers, to generate source-detector intensity matrices (SDIMs), representing the curvature of surfaces. The surfaces measured were a model ear with a latex membrane and harvested temporal bones including intact tympanic membranes. The position of the tympanic membrane was shifted from retracted to bulging by air pressure and that of the latex membrane by water displacement. The SDIM was normalized utilizing both external (a sheared flat plastic cylinder) and internal references (neutral position of the membrane). Data was fitted to a two-dimensional Gaussian surface representing the shape by its amplitude and offset. Retracted and bulging surfaces were discriminated for the model ear by the sign of the Gaussian amplitude for both internal and external reference normalization. Tympanic membranes were separated after a two-step normalization: first to an external reference, adjusted for the distance between speculum and the surfaces, and second by comparison with an average normally positioned SDIM from tympanic membranes. In conclusion, we have shown that the modified otoscope can discriminate between bulging and retracted tympanic membranes in a single measurement, given a two-step normalization.

MUC16 Is Lost from the Uterodome (Pinopode) Surface of the Receptive Human Endometrium: In Vitro Evidence That MUC16 Is a Barrier to Trophoblast Adherence1

In order for the preimplantation embryo to implant into the uterus, the trophoblast cells must initially adhere to the uterine epithelial surface. In preparation, the luminal secretory cells of the epithelium lose their nonadhesive character and their surface microvilli and bulge into the lumen, forming uterodomes (pinopodes; uterodome is used instead of pinopode, since in humans the surface membrane exocytoses rather than endocytoses (Murphy, Hum Reprod 2000; 15:2451-2454). Previous research has led to the hypothesis that loss of the nonadhesive membrane-spanning mucin MUC1 from the uterodome surface allows trophoblast adherence. Immunofluorescence microscopic assay of luminal epithelia on human uterine biopsies taken from LH+0 to LH+13 show that another membrane-spanning mucin, MUC16, was lost from uterodome surfaces in all samples taken during the receptive phase, LH+6 to LH+8 (n = 12), and that MUC1 was present on uterodomes in 4 of 12 samples and on all ciliated cells of the epithelium in the receptive phase. Short interfering RNA (siRNA) knockdown of MUC16 in a uterine epithelial cell line ECC-1 that, like uterine epithelium, expresses MUC16 and MUC1 allowed increased adherence of cells of a trophoblast cell line. In parallel experiments, siRNA knockdown of MUC1 did not affect trophoblast cell adherence. These data indicate that MUC16 is a membrane component of the nonreceptive luminal uterine surface, which prevents cell adhesion, and that its removal during uterodome formation facilitates adhesion of the trophoblast.

The stellar mass distribution in early-type disc galaxies: surface photometry and bulge–disc decompositions

We present deep B- and R-band surface photometry for a sample of 21 early-type disc galaxies with morphological types between S0 and Sab and absolute B-band magnitudes between −17 and −22. Six galaxies were also observed in the I-band. We present radial profiles of surface brightness, colour, ellipticity, position angle and deviations of axisymmetry for all galaxies, as well as isophotal and effective radii and total magnitudes. We have decomposed the images into contributions from a spheroidal bulge with a general Sersic profile and a flat disc with an arbitrary intensity distribution, using an interactive, 2D decomposition technique. We caution against the use of simple 1D decomposition methods and show that they can lead to systematic biases, particularly in the derived bulge parameters. We study in detail the relations between various bulge and disc parameters. In particular, we find that the bulges of our galaxies have surface brightness profiles ranging from exponential to De Vaucouleurs, with the average value of the Sersic shape parameter n being 2.5. In agreement with previous studies, we find that the shape of the bulge intensity distribution depends on luminosity, with the more luminous bulges having more centrally peaked light profiles (i.e. higher n). By comparing the ellipticity of the isophotes in the bulges to those in the outer, disc-dominated regions, we are able to derive the intrinsic axis ratio qb of the bulges. The average axis ratio is 0.55, with a rms spread of 0.12. None of the bulges in our sample is spherical, whereas in some cases, the bulges can be as flat as qb = 0.3-0.4. The bulge flattening seems to be weakly coupled to luminosity, more luminous bulges being on average slightly more flattened than their lower luminosity counterparts. Our finding that most bulges are significantly flattened and have an intensity profile shallower than R 1/4 suggests that 'pseudo-bulges', formed from disc material by secular processes, do not occur in late-type spiral galaxies only, but are a common feature in early-type disc galaxies as well. Most galaxies in our sample have radial colour gradients, becoming bluer towards larger radii. Although this can partly be explained by the radially declining contribution of the red bulges to the observed light, we show that discs must also have intrinsic colour gradients.

Elastic theory of surface deformation in C 60 adsorption

In molecular physisorption, beyond attractive and repulsive forces, a third contribution arises from the elastic deformation of the surface. In this paper the dimple appearing on a gold surface upon physisorption of a C 60 molecule is studied and its effect on the adsorption energy is evaluated. The depth and shape of the dimple are studied on the basis of the theory of elasticity. The equilibrium equation is solved in the presence of the body forces originating from a suitable Au–C 60 interaction potential and the solution for the deformation field is obtained by means of a two-step procedure. In the first step a curl-free deformation field is obtained, which takes the effects of the body forces into account, but generates mismatch of the boundary conditions. In the second step the solution of the equilibrium problem in the absence of body force is generated, which compensates the previous boundary condition violation. Thanks to linearity, the final solution is obtained as the sum of the results of the two steps. An (approximate) iterative scheme is applied for taking the surface deformation into account in imposing that no forces act on the Au surface. When the distance z 0 of the centre of the C 60 cage from the surface is rather large, the dimple is represented by a bulging surface, but, as the C 60 approaches the Au surface, the surface recedes and a well formed dimple appears. The corresponding depth at the mechanical equilibrium position ( z 0 = 4.8 Å) turns out to be 36.3 pm.

No Forward Shifting of Posterior Corneal Surface in Eyes Undergoing LASIK

To evaluate structural changes in the cornea and anterior chamber (AC) after LASIK for myopia. Retrospective nonrandomized study. One hundred sixty-one eyes of 83 patients (mean age, 34.5+/-8.3 years) who underwent uneventful LASIK for myopia and myopic astigmatism. The preoperative refractive error (spherical equivalent) and corneal thickness were -6.02+/-2.10 diopters (D) and 549.9+/-29.3 mum, respectively. The AC volume (ACV), AC depth (ACD), corneal thickness, central corneal true net power, and posterior corneal tangential curvature were measured using a rotating Scheimpflug camera before and 1 week and 1 month after surgery. In 84 eyes of 42 cases, anterior and posterior corneal elevations and corneal thicknesses also were measured by scanning-slit topography before and 1 month after surgery. Time course of the ACV, ACD (central, midperiphery, periphery), corneal thickness, central corneal true net power, posterior corneal tangential curvature using the Scheimpflug camera, and amount of forward shifting of the posterior corneal surface at the center of the difference map using scanning-slit topography. Preoperative and 1-month postoperative mean ACVs were 198.1 mm3 and 196.4 mm3, respectively, and preoperative and postoperative mean ACDs (center, midperiphery, periphery) were 3.24, 2.65, and 1.89 mm, and 3.21, 2.63, and 1.87 mm, respectively. The corneal thickness within the optical zone, subjective refraction, and central corneal true net power significantly changed by tissue subtraction after LASIK (P<0.0001). There were no significant differences in the ACV, ACDs (center, midperiphery, periphery), peripheral corneal thickness, and posterior corneal tangential curvature from preoperatively to 1 month after LASIK. However, using scanning-slit topography, the posterior corneal surface displayed a mean forward shift of 29.0+/-19.0 microm 1 month after surgery. The posterior corneal curvature, peripheral corneal thickness, ACDs, and ACV were consistent. These observations indicated that neither forward shifting of the central posterior corneal surface (bulging) nor backward shifting of the peripheral posterior corneal surface due to corneal swelling after ablation occurred after LASIK.

Effect of Microstructure on Crack of Al-Mg-Si Alloy Extrusions during Axial Compression

Effect of microstructure on micro-cracking behavior of Al-Mg-Si alloy extrusions during axial compressive deformation was studied. Extrusions of Al-Mg-Si alloys with two different compositions were used for the mechanical tests and microstructure observation. Compressive loads were applied parallel to the axes of the tubular specimens with rectangular cross section. As deformation proceeded, the specimens changed their shape into bellows-like ones. Specimens with finer grains showed higher critical strength and strain for crack initiation. Microscopic observation showed that cracks initiated at the bulge surface of the bellows and propagated into the depth. The observed behavior of crack initiation and propagation was interpreted in connection with those in simple tensile tests. The stress and strain at the crack initiation site of the bulge were assumed to correspond to the tensile strength of the alloy. The effect of grain size on the crack behavior was well explained by the grain size dependence of stress concentration at grain boundaries due to dislocation pile-ups. The effects of over-aging on the microstructure and crack initiation behavior were also discussed.

Equilibrium Disk‐Bulge‐Halo Models for the Milky Way and Andromeda Galaxies

We describe a new set of self-consistent, equilibrium disk galaxy models that incorporate an exponential disk, a Hernquist model bulge, an NFW halo, and a central supermassive black hole. The models are derived from explicit distribution functions for each component, and the large number of parameters permit detailed modeling of actual galaxies. We present techniques that use structural and kinematic data such as radial surface brightness profiles, rotation curves, and bulge velocity dispersion profiles to find the best-fit models for the Milky Way and M31. Through N-body realizations of these models we explore their stability against the formation of bars. The models permit the study of a wide range of dynamical phenomenon with a high degree of realism.

Elastic theory of surface deformation in molecular physisorption

In molecular physisorption, beyond attractive and repulsive forces, a third contribution arises from the elastic deformation of the surface. In the present work the dimple appearing on a deformable surface upon physisorption of a foreign molecule is studied and its effect on the adsorption energy is calculated. The depth and shape of the physisorption dimple are studied on the basis of the theory of elasticity. The problem of the deformation of a semi-infinite elastic medium, subject to central body forces, is solved, with the centre (i.e., the molecule) placed outside the medium. A vectorial Poisson equation for the displacement field is solved with the boundary condition that no surface forces act. For a centrosymmetrical molecule the solution is obtained in two steps, whose results are then superposed: (1) the deformation field in an infinite elastic medium subject to a central body force field, whose centre coincides with the centre of the molecule, is evaluated (the solution generates mismatch of the boundary conditions); (2) a complementary homogeneous problem is solved with boundary conditions compensating the spurious contributions generated in step (1). Specific attention is given to methane adsorption both on a metal surface (Au) and on a molecular crystal surface (solid Ar). The shape function ζ( R) is always positive (indicating a bulging surface) if the distance z of the molecule (i.e., of the carbon atom) from the surface is large, but becomes largely negative for z smaller, showing a definite dimple. The minimum energy (adsorption equilibrium) corresponds to the latter case. The dimple depth turns out to be 10.0 pm in the case of Au, while for Ar we find a depth of 30.5 pm at 80 K and 25.6 pm at 0 K. A discussion of the asymptotic behaviour (proportional, off equilibrium, to R −1) of the deformation at long distances R from the adsorbed molecule is also given.

Surface and Orbscan II slit-scanning elevation topography in circumscribed posterior keratoconus

We used an Orbscan II topography system (Bausch & Lomb) to study anterior and posterior surface abnormalities, keratometry, and topographic pachymetry in a patient with circumscribed posterior keratoconus. This system clearly showed a marked localized paracentral annular elevation in the posterior corneal surface that corresponded to an abrupt decrease in thickness and a slightly localized anterior surface bulge in the anterior float.

Long-term evaluation of laser in situ keratomileusis for extremely high myopia

To evaluate the long-term efficacy and safety of laser in situ keratomileusis (LASIK) for extremely high myopia (with a preoperative refraction more than -10.00 diopters). 173 eyes of 99 patients with a mean spherical equivalent (SE) of (-13.70 +/- 3.60) D (range -10.00 approximately 23.50 D), including 41 eyes with more than -15.00 D, were treated with LASIK and followed up for more than 18 months. The examinations included slitlamp microscopy, fundus examination, Orbscan II corneal topography system, tonometry, pachymetry, cycloplegic and subjective refraction. At 18 months postoperatively, the uncorrected visual acuity (UCVA) was 0.5 or better in 148 eyes (85.6%), and the best spectacle-corrected visual acuity (BSCVA) remained the same or increased in 147 eyes (84.4%). No eye lost more than two lines of BSCVA. 109 eyes (63.0%) were within +/- 1.00 D of emmetropia. The percentage was 73.5% and 29.3% in eyes with a preoperative SE of less than -14.75 D and more than -15.00 D, respectively. Postoperatively, the posterior corneal surface bulge was detected in all eyes. The mean elevation of the posterior corneal surface against the best-fit sphere was (0.029 +/- 0.010) mm preoperatively, (0.069 +/- 0.031) mm at 3 months, (0.065 +/- 0.025) mm at 18 months. At final follow-up, corneal flap folds were found in 2 eyes, and 6 patients (10 eyes) complained of glare or decreased scotopic vision. LASIK appeared to be an effective and safe treatment for correction of extremely high myopia. Meanwhile the candidates should be carefully screened.

Nuclear Properties of a Sample of Nearby Spiral Galaxies fromHubble Space TelescopeSTIS Imaging

We present surface photometry for the central regions of a sample of 48 spiral galaxies (mostly unbarred and barred of types Sbc or Sc) observed with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Surface brightness profiles were derived and modeled with a Nuker law. We also analyzed archival Wide Field Planetary Camera~2 images with a larger field of view, available for 18 galaxies in our sample. We modeled the extracted bulge surface brightness profiles with an exponential, a de Vaucouleurs or a Sersic profile. In agreement with previous studies, we find that bulges of Sbc galaxies fall into two categories: bulges well described by an exponential profile and those well described by an de Vaucouleurs profile. Only one galaxy requires the use of a more general Sersic profile to properly describe the bulge. Nuclear photometrically distinct components are found in ~55% of the galaxies. For those that we classify as star clusters based on their resolved extent we find absolute magnitudes that are brighter on average than those previously identified in spiral galaxies. This might be due to a bias in our sample toward star forming galaxies, combined with a trend for star forming galaxies to host brighter central clusters.

Gear Forging: Mathematical Modeling and Experimental Validation

A useful facility to the adaptation of precision gear forging by industry, is a quick method of load and flow predictions. In this work, the process of precision forging spur and helical gears is modeled by means of an upper bound analysis. A new velocity field, which includes bulging of the tooth form, is proposed and a computerized incremental procedure for the prediction of the bulged surface profile of the teeth, the forging load, and its increase due to corner filling is presented. The effect of workpiece/die interface friction, gear module, numbers of teeth, helix angle, gear height and bore size on forging pressure are determined. Experimental results obtained for room and elevated temperature forgings compared well with theoretical predictions.